Bug Summary

File:build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/llvm/lib/Analysis/ScalarEvolution.cpp
Warning:line 4432, column 32
Dereference of null pointer (loaded from variable 'PtrOp')

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name ScalarEvolution.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/build-llvm -resource-dir /usr/lib/llvm-15/lib/clang/15.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I lib/Analysis -I /build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/llvm/lib/Analysis -I include -I /build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/llvm/include -D _FORTIFY_SOURCE=2 -D NDEBUG -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-15/lib/clang/15.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fmacro-prefix-map=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/build-llvm=build-llvm -fmacro-prefix-map=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/= -fcoverage-prefix-map=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/build-llvm=build-llvm -fcoverage-prefix-map=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/= -O3 -Wno-unused-command-line-argument -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/build-llvm -fdebug-prefix-map=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/build-llvm=build-llvm -fdebug-prefix-map=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/= -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -fcolor-diagnostics -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2022-04-20-140412-16051-1 -x c++ /build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/llvm/lib/Analysis/ScalarEvolution.cpp
1//===- ScalarEvolution.cpp - Scalar Evolution Analysis --------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file contains the implementation of the scalar evolution analysis
10// engine, which is used primarily to analyze expressions involving induction
11// variables in loops.
12//
13// There are several aspects to this library. First is the representation of
14// scalar expressions, which are represented as subclasses of the SCEV class.
15// These classes are used to represent certain types of subexpressions that we
16// can handle. We only create one SCEV of a particular shape, so
17// pointer-comparisons for equality are legal.
18//
19// One important aspect of the SCEV objects is that they are never cyclic, even
20// if there is a cycle in the dataflow for an expression (ie, a PHI node). If
21// the PHI node is one of the idioms that we can represent (e.g., a polynomial
22// recurrence) then we represent it directly as a recurrence node, otherwise we
23// represent it as a SCEVUnknown node.
24//
25// In addition to being able to represent expressions of various types, we also
26// have folders that are used to build the *canonical* representation for a
27// particular expression. These folders are capable of using a variety of
28// rewrite rules to simplify the expressions.
29//
30// Once the folders are defined, we can implement the more interesting
31// higher-level code, such as the code that recognizes PHI nodes of various
32// types, computes the execution count of a loop, etc.
33//
34// TODO: We should use these routines and value representations to implement
35// dependence analysis!
36//
37//===----------------------------------------------------------------------===//
38//
39// There are several good references for the techniques used in this analysis.
40//
41// Chains of recurrences -- a method to expedite the evaluation
42// of closed-form functions
43// Olaf Bachmann, Paul S. Wang, Eugene V. Zima
44//
45// On computational properties of chains of recurrences
46// Eugene V. Zima
47//
48// Symbolic Evaluation of Chains of Recurrences for Loop Optimization
49// Robert A. van Engelen
50//
51// Efficient Symbolic Analysis for Optimizing Compilers
52// Robert A. van Engelen
53//
54// Using the chains of recurrences algebra for data dependence testing and
55// induction variable substitution
56// MS Thesis, Johnie Birch
57//
58//===----------------------------------------------------------------------===//
59
60#include "llvm/Analysis/ScalarEvolution.h"
61#include "llvm/ADT/APInt.h"
62#include "llvm/ADT/ArrayRef.h"
63#include "llvm/ADT/DenseMap.h"
64#include "llvm/ADT/DepthFirstIterator.h"
65#include "llvm/ADT/EquivalenceClasses.h"
66#include "llvm/ADT/FoldingSet.h"
67#include "llvm/ADT/None.h"
68#include "llvm/ADT/Optional.h"
69#include "llvm/ADT/STLExtras.h"
70#include "llvm/ADT/ScopeExit.h"
71#include "llvm/ADT/Sequence.h"
72#include "llvm/ADT/SetVector.h"
73#include "llvm/ADT/SmallPtrSet.h"
74#include "llvm/ADT/SmallSet.h"
75#include "llvm/ADT/SmallVector.h"
76#include "llvm/ADT/Statistic.h"
77#include "llvm/ADT/StringRef.h"
78#include "llvm/Analysis/AssumptionCache.h"
79#include "llvm/Analysis/ConstantFolding.h"
80#include "llvm/Analysis/InstructionSimplify.h"
81#include "llvm/Analysis/LoopInfo.h"
82#include "llvm/Analysis/ScalarEvolutionExpressions.h"
83#include "llvm/Analysis/TargetLibraryInfo.h"
84#include "llvm/Analysis/ValueTracking.h"
85#include "llvm/Config/llvm-config.h"
86#include "llvm/IR/Argument.h"
87#include "llvm/IR/BasicBlock.h"
88#include "llvm/IR/CFG.h"
89#include "llvm/IR/Constant.h"
90#include "llvm/IR/ConstantRange.h"
91#include "llvm/IR/Constants.h"
92#include "llvm/IR/DataLayout.h"
93#include "llvm/IR/DerivedTypes.h"
94#include "llvm/IR/Dominators.h"
95#include "llvm/IR/Function.h"
96#include "llvm/IR/GlobalAlias.h"
97#include "llvm/IR/GlobalValue.h"
98#include "llvm/IR/InstIterator.h"
99#include "llvm/IR/InstrTypes.h"
100#include "llvm/IR/Instruction.h"
101#include "llvm/IR/Instructions.h"
102#include "llvm/IR/IntrinsicInst.h"
103#include "llvm/IR/Intrinsics.h"
104#include "llvm/IR/LLVMContext.h"
105#include "llvm/IR/Operator.h"
106#include "llvm/IR/PatternMatch.h"
107#include "llvm/IR/Type.h"
108#include "llvm/IR/Use.h"
109#include "llvm/IR/User.h"
110#include "llvm/IR/Value.h"
111#include "llvm/IR/Verifier.h"
112#include "llvm/InitializePasses.h"
113#include "llvm/Pass.h"
114#include "llvm/Support/Casting.h"
115#include "llvm/Support/CommandLine.h"
116#include "llvm/Support/Compiler.h"
117#include "llvm/Support/Debug.h"
118#include "llvm/Support/ErrorHandling.h"
119#include "llvm/Support/KnownBits.h"
120#include "llvm/Support/SaveAndRestore.h"
121#include "llvm/Support/raw_ostream.h"
122#include <algorithm>
123#include <cassert>
124#include <climits>
125#include <cstdint>
126#include <cstdlib>
127#include <map>
128#include <memory>
129#include <tuple>
130#include <utility>
131#include <vector>
132
133using namespace llvm;
134using namespace PatternMatch;
135
136#define DEBUG_TYPE"scalar-evolution" "scalar-evolution"
137
138STATISTIC(NumTripCountsComputed,static llvm::Statistic NumTripCountsComputed = {"scalar-evolution"
, "NumTripCountsComputed", "Number of loops with predictable loop counts"
}
139 "Number of loops with predictable loop counts")static llvm::Statistic NumTripCountsComputed = {"scalar-evolution"
, "NumTripCountsComputed", "Number of loops with predictable loop counts"
};
140STATISTIC(NumTripCountsNotComputed,static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution"
, "NumTripCountsNotComputed", "Number of loops without predictable loop counts"
}
141 "Number of loops without predictable loop counts")static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution"
, "NumTripCountsNotComputed", "Number of loops without predictable loop counts"
};
142STATISTIC(NumBruteForceTripCountsComputed,static llvm::Statistic NumBruteForceTripCountsComputed = {"scalar-evolution"
, "NumBruteForceTripCountsComputed", "Number of loops with trip counts computed by force"
}
143 "Number of loops with trip counts computed by force")static llvm::Statistic NumBruteForceTripCountsComputed = {"scalar-evolution"
, "NumBruteForceTripCountsComputed", "Number of loops with trip counts computed by force"
};
144
145#ifdef EXPENSIVE_CHECKS
146bool llvm::VerifySCEV = true;
147#else
148bool llvm::VerifySCEV = false;
149#endif
150
151static cl::opt<unsigned>
152MaxBruteForceIterations("scalar-evolution-max-iterations", cl::ReallyHidden,
153 cl::ZeroOrMore,
154 cl::desc("Maximum number of iterations SCEV will "
155 "symbolically execute a constant "
156 "derived loop"),
157 cl::init(100));
158
159static cl::opt<bool, true> VerifySCEVOpt(
160 "verify-scev", cl::Hidden, cl::location(VerifySCEV),
161 cl::desc("Verify ScalarEvolution's backedge taken counts (slow)"));
162static cl::opt<bool> VerifySCEVStrict(
163 "verify-scev-strict", cl::Hidden,
164 cl::desc("Enable stricter verification with -verify-scev is passed"));
165static cl::opt<bool>
166 VerifySCEVMap("verify-scev-maps", cl::Hidden,
167 cl::desc("Verify no dangling value in ScalarEvolution's "
168 "ExprValueMap (slow)"));
169
170static cl::opt<bool> VerifyIR(
171 "scev-verify-ir", cl::Hidden,
172 cl::desc("Verify IR correctness when making sensitive SCEV queries (slow)"),
173 cl::init(false));
174
175static cl::opt<unsigned> MulOpsInlineThreshold(
176 "scev-mulops-inline-threshold", cl::Hidden,
177 cl::desc("Threshold for inlining multiplication operands into a SCEV"),
178 cl::init(32));
179
180static cl::opt<unsigned> AddOpsInlineThreshold(
181 "scev-addops-inline-threshold", cl::Hidden,
182 cl::desc("Threshold for inlining addition operands into a SCEV"),
183 cl::init(500));
184
185static cl::opt<unsigned> MaxSCEVCompareDepth(
186 "scalar-evolution-max-scev-compare-depth", cl::Hidden,
187 cl::desc("Maximum depth of recursive SCEV complexity comparisons"),
188 cl::init(32));
189
190static cl::opt<unsigned> MaxSCEVOperationsImplicationDepth(
191 "scalar-evolution-max-scev-operations-implication-depth", cl::Hidden,
192 cl::desc("Maximum depth of recursive SCEV operations implication analysis"),
193 cl::init(2));
194
195static cl::opt<unsigned> MaxValueCompareDepth(
196 "scalar-evolution-max-value-compare-depth", cl::Hidden,
197 cl::desc("Maximum depth of recursive value complexity comparisons"),
198 cl::init(2));
199
200static cl::opt<unsigned>
201 MaxArithDepth("scalar-evolution-max-arith-depth", cl::Hidden,
202 cl::desc("Maximum depth of recursive arithmetics"),
203 cl::init(32));
204
205static cl::opt<unsigned> MaxConstantEvolvingDepth(
206 "scalar-evolution-max-constant-evolving-depth", cl::Hidden,
207 cl::desc("Maximum depth of recursive constant evolving"), cl::init(32));
208
209static cl::opt<unsigned>
210 MaxCastDepth("scalar-evolution-max-cast-depth", cl::Hidden,
211 cl::desc("Maximum depth of recursive SExt/ZExt/Trunc"),
212 cl::init(8));
213
214static cl::opt<unsigned>
215 MaxAddRecSize("scalar-evolution-max-add-rec-size", cl::Hidden,
216 cl::desc("Max coefficients in AddRec during evolving"),
217 cl::init(8));
218
219static cl::opt<unsigned>
220 HugeExprThreshold("scalar-evolution-huge-expr-threshold", cl::Hidden,
221 cl::desc("Size of the expression which is considered huge"),
222 cl::init(4096));
223
224static cl::opt<bool>
225ClassifyExpressions("scalar-evolution-classify-expressions",
226 cl::Hidden, cl::init(true),
227 cl::desc("When printing analysis, include information on every instruction"));
228
229static cl::opt<bool> UseExpensiveRangeSharpening(
230 "scalar-evolution-use-expensive-range-sharpening", cl::Hidden,
231 cl::init(false),
232 cl::desc("Use more powerful methods of sharpening expression ranges. May "
233 "be costly in terms of compile time"));
234
235static cl::opt<unsigned> MaxPhiSCCAnalysisSize(
236 "scalar-evolution-max-scc-analysis-depth", cl::Hidden,
237 cl::desc("Maximum amount of nodes to process while searching SCEVUnknown "
238 "Phi strongly connected components"),
239 cl::init(8));
240
241static cl::opt<bool>
242 EnableFiniteLoopControl("scalar-evolution-finite-loop", cl::Hidden,
243 cl::desc("Handle <= and >= in finite loops"),
244 cl::init(true));
245
246//===----------------------------------------------------------------------===//
247// SCEV class definitions
248//===----------------------------------------------------------------------===//
249
250//===----------------------------------------------------------------------===//
251// Implementation of the SCEV class.
252//
253
254#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
255LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void SCEV::dump() const {
256 print(dbgs());
257 dbgs() << '\n';
258}
259#endif
260
261void SCEV::print(raw_ostream &OS) const {
262 switch (getSCEVType()) {
263 case scConstant:
264 cast<SCEVConstant>(this)->getValue()->printAsOperand(OS, false);
265 return;
266 case scPtrToInt: {
267 const SCEVPtrToIntExpr *PtrToInt = cast<SCEVPtrToIntExpr>(this);
268 const SCEV *Op = PtrToInt->getOperand();
269 OS << "(ptrtoint " << *Op->getType() << " " << *Op << " to "
270 << *PtrToInt->getType() << ")";
271 return;
272 }
273 case scTruncate: {
274 const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(this);
275 const SCEV *Op = Trunc->getOperand();
276 OS << "(trunc " << *Op->getType() << " " << *Op << " to "
277 << *Trunc->getType() << ")";
278 return;
279 }
280 case scZeroExtend: {
281 const SCEVZeroExtendExpr *ZExt = cast<SCEVZeroExtendExpr>(this);
282 const SCEV *Op = ZExt->getOperand();
283 OS << "(zext " << *Op->getType() << " " << *Op << " to "
284 << *ZExt->getType() << ")";
285 return;
286 }
287 case scSignExtend: {
288 const SCEVSignExtendExpr *SExt = cast<SCEVSignExtendExpr>(this);
289 const SCEV *Op = SExt->getOperand();
290 OS << "(sext " << *Op->getType() << " " << *Op << " to "
291 << *SExt->getType() << ")";
292 return;
293 }
294 case scAddRecExpr: {
295 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(this);
296 OS << "{" << *AR->getOperand(0);
297 for (unsigned i = 1, e = AR->getNumOperands(); i != e; ++i)
298 OS << ",+," << *AR->getOperand(i);
299 OS << "}<";
300 if (AR->hasNoUnsignedWrap())
301 OS << "nuw><";
302 if (AR->hasNoSignedWrap())
303 OS << "nsw><";
304 if (AR->hasNoSelfWrap() &&
305 !AR->getNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW)))
306 OS << "nw><";
307 AR->getLoop()->getHeader()->printAsOperand(OS, /*PrintType=*/false);
308 OS << ">";
309 return;
310 }
311 case scAddExpr:
312 case scMulExpr:
313 case scUMaxExpr:
314 case scSMaxExpr:
315 case scUMinExpr:
316 case scSMinExpr:
317 case scSequentialUMinExpr: {
318 const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(this);
319 const char *OpStr = nullptr;
320 switch (NAry->getSCEVType()) {
321 case scAddExpr: OpStr = " + "; break;
322 case scMulExpr: OpStr = " * "; break;
323 case scUMaxExpr: OpStr = " umax "; break;
324 case scSMaxExpr: OpStr = " smax "; break;
325 case scUMinExpr:
326 OpStr = " umin ";
327 break;
328 case scSMinExpr:
329 OpStr = " smin ";
330 break;
331 case scSequentialUMinExpr:
332 OpStr = " umin_seq ";
333 break;
334 default:
335 llvm_unreachable("There are no other nary expression types.")::llvm::llvm_unreachable_internal("There are no other nary expression types."
, "llvm/lib/Analysis/ScalarEvolution.cpp", 335);
336 }
337 OS << "(";
338 ListSeparator LS(OpStr);
339 for (const SCEV *Op : NAry->operands())
340 OS << LS << *Op;
341 OS << ")";
342 switch (NAry->getSCEVType()) {
343 case scAddExpr:
344 case scMulExpr:
345 if (NAry->hasNoUnsignedWrap())
346 OS << "<nuw>";
347 if (NAry->hasNoSignedWrap())
348 OS << "<nsw>";
349 break;
350 default:
351 // Nothing to print for other nary expressions.
352 break;
353 }
354 return;
355 }
356 case scUDivExpr: {
357 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(this);
358 OS << "(" << *UDiv->getLHS() << " /u " << *UDiv->getRHS() << ")";
359 return;
360 }
361 case scUnknown: {
362 const SCEVUnknown *U = cast<SCEVUnknown>(this);
363 Type *AllocTy;
364 if (U->isSizeOf(AllocTy)) {
365 OS << "sizeof(" << *AllocTy << ")";
366 return;
367 }
368 if (U->isAlignOf(AllocTy)) {
369 OS << "alignof(" << *AllocTy << ")";
370 return;
371 }
372
373 Type *CTy;
374 Constant *FieldNo;
375 if (U->isOffsetOf(CTy, FieldNo)) {
376 OS << "offsetof(" << *CTy << ", ";
377 FieldNo->printAsOperand(OS, false);
378 OS << ")";
379 return;
380 }
381
382 // Otherwise just print it normally.
383 U->getValue()->printAsOperand(OS, false);
384 return;
385 }
386 case scCouldNotCompute:
387 OS << "***COULDNOTCOMPUTE***";
388 return;
389 }
390 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 390);
391}
392
393Type *SCEV::getType() const {
394 switch (getSCEVType()) {
395 case scConstant:
396 return cast<SCEVConstant>(this)->getType();
397 case scPtrToInt:
398 case scTruncate:
399 case scZeroExtend:
400 case scSignExtend:
401 return cast<SCEVCastExpr>(this)->getType();
402 case scAddRecExpr:
403 return cast<SCEVAddRecExpr>(this)->getType();
404 case scMulExpr:
405 return cast<SCEVMulExpr>(this)->getType();
406 case scUMaxExpr:
407 case scSMaxExpr:
408 case scUMinExpr:
409 case scSMinExpr:
410 return cast<SCEVMinMaxExpr>(this)->getType();
411 case scSequentialUMinExpr:
412 return cast<SCEVSequentialMinMaxExpr>(this)->getType();
413 case scAddExpr:
414 return cast<SCEVAddExpr>(this)->getType();
415 case scUDivExpr:
416 return cast<SCEVUDivExpr>(this)->getType();
417 case scUnknown:
418 return cast<SCEVUnknown>(this)->getType();
419 case scCouldNotCompute:
420 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "llvm/lib/Analysis/ScalarEvolution.cpp", 420);
421 }
422 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 422);
423}
424
425bool SCEV::isZero() const {
426 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
427 return SC->getValue()->isZero();
428 return false;
429}
430
431bool SCEV::isOne() const {
432 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
433 return SC->getValue()->isOne();
434 return false;
435}
436
437bool SCEV::isAllOnesValue() const {
438 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
439 return SC->getValue()->isMinusOne();
440 return false;
441}
442
443bool SCEV::isNonConstantNegative() const {
444 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(this);
445 if (!Mul) return false;
446
447 // If there is a constant factor, it will be first.
448 const SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0));
449 if (!SC) return false;
450
451 // Return true if the value is negative, this matches things like (-42 * V).
452 return SC->getAPInt().isNegative();
453}
454
455SCEVCouldNotCompute::SCEVCouldNotCompute() :
456 SCEV(FoldingSetNodeIDRef(), scCouldNotCompute, 0) {}
457
458bool SCEVCouldNotCompute::classof(const SCEV *S) {
459 return S->getSCEVType() == scCouldNotCompute;
460}
461
462const SCEV *ScalarEvolution::getConstant(ConstantInt *V) {
463 FoldingSetNodeID ID;
464 ID.AddInteger(scConstant);
465 ID.AddPointer(V);
466 void *IP = nullptr;
467 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
468 SCEV *S = new (SCEVAllocator) SCEVConstant(ID.Intern(SCEVAllocator), V);
469 UniqueSCEVs.InsertNode(S, IP);
470 return S;
471}
472
473const SCEV *ScalarEvolution::getConstant(const APInt &Val) {
474 return getConstant(ConstantInt::get(getContext(), Val));
475}
476
477const SCEV *
478ScalarEvolution::getConstant(Type *Ty, uint64_t V, bool isSigned) {
479 IntegerType *ITy = cast<IntegerType>(getEffectiveSCEVType(Ty));
480 return getConstant(ConstantInt::get(ITy, V, isSigned));
481}
482
483SCEVCastExpr::SCEVCastExpr(const FoldingSetNodeIDRef ID, SCEVTypes SCEVTy,
484 const SCEV *op, Type *ty)
485 : SCEV(ID, SCEVTy, computeExpressionSize(op)), Ty(ty) {
486 Operands[0] = op;
487}
488
489SCEVPtrToIntExpr::SCEVPtrToIntExpr(const FoldingSetNodeIDRef ID, const SCEV *Op,
490 Type *ITy)
491 : SCEVCastExpr(ID, scPtrToInt, Op, ITy) {
492 assert(getOperand()->getType()->isPointerTy() && Ty->isIntegerTy() &&(static_cast <bool> (getOperand()->getType()->isPointerTy
() && Ty->isIntegerTy() && "Must be a non-bit-width-changing pointer-to-integer cast!"
) ? void (0) : __assert_fail ("getOperand()->getType()->isPointerTy() && Ty->isIntegerTy() && \"Must be a non-bit-width-changing pointer-to-integer cast!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 493, __extension__
__PRETTY_FUNCTION__))
493 "Must be a non-bit-width-changing pointer-to-integer cast!")(static_cast <bool> (getOperand()->getType()->isPointerTy
() && Ty->isIntegerTy() && "Must be a non-bit-width-changing pointer-to-integer cast!"
) ? void (0) : __assert_fail ("getOperand()->getType()->isPointerTy() && Ty->isIntegerTy() && \"Must be a non-bit-width-changing pointer-to-integer cast!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 493, __extension__
__PRETTY_FUNCTION__));
494}
495
496SCEVIntegralCastExpr::SCEVIntegralCastExpr(const FoldingSetNodeIDRef ID,
497 SCEVTypes SCEVTy, const SCEV *op,
498 Type *ty)
499 : SCEVCastExpr(ID, SCEVTy, op, ty) {}
500
501SCEVTruncateExpr::SCEVTruncateExpr(const FoldingSetNodeIDRef ID, const SCEV *op,
502 Type *ty)
503 : SCEVIntegralCastExpr(ID, scTruncate, op, ty) {
504 assert(getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&(static_cast <bool> (getOperand()->getType()->isIntOrPtrTy
() && Ty->isIntOrPtrTy() && "Cannot truncate non-integer value!"
) ? void (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate non-integer value!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 505, __extension__
__PRETTY_FUNCTION__))
505 "Cannot truncate non-integer value!")(static_cast <bool> (getOperand()->getType()->isIntOrPtrTy
() && Ty->isIntOrPtrTy() && "Cannot truncate non-integer value!"
) ? void (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate non-integer value!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 505, __extension__
__PRETTY_FUNCTION__));
506}
507
508SCEVZeroExtendExpr::SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID,
509 const SCEV *op, Type *ty)
510 : SCEVIntegralCastExpr(ID, scZeroExtend, op, ty) {
511 assert(getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&(static_cast <bool> (getOperand()->getType()->isIntOrPtrTy
() && Ty->isIntOrPtrTy() && "Cannot zero extend non-integer value!"
) ? void (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot zero extend non-integer value!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 512, __extension__
__PRETTY_FUNCTION__))
512 "Cannot zero extend non-integer value!")(static_cast <bool> (getOperand()->getType()->isIntOrPtrTy
() && Ty->isIntOrPtrTy() && "Cannot zero extend non-integer value!"
) ? void (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot zero extend non-integer value!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 512, __extension__
__PRETTY_FUNCTION__));
513}
514
515SCEVSignExtendExpr::SCEVSignExtendExpr(const FoldingSetNodeIDRef ID,
516 const SCEV *op, Type *ty)
517 : SCEVIntegralCastExpr(ID, scSignExtend, op, ty) {
518 assert(getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&(static_cast <bool> (getOperand()->getType()->isIntOrPtrTy
() && Ty->isIntOrPtrTy() && "Cannot sign extend non-integer value!"
) ? void (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot sign extend non-integer value!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 519, __extension__
__PRETTY_FUNCTION__))
519 "Cannot sign extend non-integer value!")(static_cast <bool> (getOperand()->getType()->isIntOrPtrTy
() && Ty->isIntOrPtrTy() && "Cannot sign extend non-integer value!"
) ? void (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot sign extend non-integer value!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 519, __extension__
__PRETTY_FUNCTION__));
520}
521
522void SCEVUnknown::deleted() {
523 // Clear this SCEVUnknown from various maps.
524 SE->forgetMemoizedResults(this);
525
526 // Remove this SCEVUnknown from the uniquing map.
527 SE->UniqueSCEVs.RemoveNode(this);
528
529 // Release the value.
530 setValPtr(nullptr);
531}
532
533void SCEVUnknown::allUsesReplacedWith(Value *New) {
534 // Clear this SCEVUnknown from various maps.
535 SE->forgetMemoizedResults(this);
536
537 // Remove this SCEVUnknown from the uniquing map.
538 SE->UniqueSCEVs.RemoveNode(this);
539
540 // Replace the value pointer in case someone is still using this SCEVUnknown.
541 setValPtr(New);
542}
543
544bool SCEVUnknown::isSizeOf(Type *&AllocTy) const {
545 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
546 if (VCE->getOpcode() == Instruction::PtrToInt)
547 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
548 if (CE->getOpcode() == Instruction::GetElementPtr &&
549 CE->getOperand(0)->isNullValue() &&
550 CE->getNumOperands() == 2)
551 if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(1)))
552 if (CI->isOne()) {
553 AllocTy = cast<GEPOperator>(CE)->getSourceElementType();
554 return true;
555 }
556
557 return false;
558}
559
560bool SCEVUnknown::isAlignOf(Type *&AllocTy) const {
561 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
562 if (VCE->getOpcode() == Instruction::PtrToInt)
563 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
564 if (CE->getOpcode() == Instruction::GetElementPtr &&
565 CE->getOperand(0)->isNullValue()) {
566 Type *Ty = cast<GEPOperator>(CE)->getSourceElementType();
567 if (StructType *STy = dyn_cast<StructType>(Ty))
568 if (!STy->isPacked() &&
569 CE->getNumOperands() == 3 &&
570 CE->getOperand(1)->isNullValue()) {
571 if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(2)))
572 if (CI->isOne() &&
573 STy->getNumElements() == 2 &&
574 STy->getElementType(0)->isIntegerTy(1)) {
575 AllocTy = STy->getElementType(1);
576 return true;
577 }
578 }
579 }
580
581 return false;
582}
583
584bool SCEVUnknown::isOffsetOf(Type *&CTy, Constant *&FieldNo) const {
585 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
586 if (VCE->getOpcode() == Instruction::PtrToInt)
587 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
588 if (CE->getOpcode() == Instruction::GetElementPtr &&
589 CE->getNumOperands() == 3 &&
590 CE->getOperand(0)->isNullValue() &&
591 CE->getOperand(1)->isNullValue()) {
592 Type *Ty = cast<GEPOperator>(CE)->getSourceElementType();
593 // Ignore vector types here so that ScalarEvolutionExpander doesn't
594 // emit getelementptrs that index into vectors.
595 if (Ty->isStructTy() || Ty->isArrayTy()) {
596 CTy = Ty;
597 FieldNo = CE->getOperand(2);
598 return true;
599 }
600 }
601
602 return false;
603}
604
605//===----------------------------------------------------------------------===//
606// SCEV Utilities
607//===----------------------------------------------------------------------===//
608
609/// Compare the two values \p LV and \p RV in terms of their "complexity" where
610/// "complexity" is a partial (and somewhat ad-hoc) relation used to order
611/// operands in SCEV expressions. \p EqCache is a set of pairs of values that
612/// have been previously deemed to be "equally complex" by this routine. It is
613/// intended to avoid exponential time complexity in cases like:
614///
615/// %a = f(%x, %y)
616/// %b = f(%a, %a)
617/// %c = f(%b, %b)
618///
619/// %d = f(%x, %y)
620/// %e = f(%d, %d)
621/// %f = f(%e, %e)
622///
623/// CompareValueComplexity(%f, %c)
624///
625/// Since we do not continue running this routine on expression trees once we
626/// have seen unequal values, there is no need to track them in the cache.
627static int
628CompareValueComplexity(EquivalenceClasses<const Value *> &EqCacheValue,
629 const LoopInfo *const LI, Value *LV, Value *RV,
630 unsigned Depth) {
631 if (Depth > MaxValueCompareDepth || EqCacheValue.isEquivalent(LV, RV))
632 return 0;
633
634 // Order pointer values after integer values. This helps SCEVExpander form
635 // GEPs.
636 bool LIsPointer = LV->getType()->isPointerTy(),
637 RIsPointer = RV->getType()->isPointerTy();
638 if (LIsPointer != RIsPointer)
639 return (int)LIsPointer - (int)RIsPointer;
640
641 // Compare getValueID values.
642 unsigned LID = LV->getValueID(), RID = RV->getValueID();
643 if (LID != RID)
644 return (int)LID - (int)RID;
645
646 // Sort arguments by their position.
647 if (const auto *LA = dyn_cast<Argument>(LV)) {
648 const auto *RA = cast<Argument>(RV);
649 unsigned LArgNo = LA->getArgNo(), RArgNo = RA->getArgNo();
650 return (int)LArgNo - (int)RArgNo;
651 }
652
653 if (const auto *LGV = dyn_cast<GlobalValue>(LV)) {
654 const auto *RGV = cast<GlobalValue>(RV);
655
656 const auto IsGVNameSemantic = [&](const GlobalValue *GV) {
657 auto LT = GV->getLinkage();
658 return !(GlobalValue::isPrivateLinkage(LT) ||
659 GlobalValue::isInternalLinkage(LT));
660 };
661
662 // Use the names to distinguish the two values, but only if the
663 // names are semantically important.
664 if (IsGVNameSemantic(LGV) && IsGVNameSemantic(RGV))
665 return LGV->getName().compare(RGV->getName());
666 }
667
668 // For instructions, compare their loop depth, and their operand count. This
669 // is pretty loose.
670 if (const auto *LInst = dyn_cast<Instruction>(LV)) {
671 const auto *RInst = cast<Instruction>(RV);
672
673 // Compare loop depths.
674 const BasicBlock *LParent = LInst->getParent(),
675 *RParent = RInst->getParent();
676 if (LParent != RParent) {
677 unsigned LDepth = LI->getLoopDepth(LParent),
678 RDepth = LI->getLoopDepth(RParent);
679 if (LDepth != RDepth)
680 return (int)LDepth - (int)RDepth;
681 }
682
683 // Compare the number of operands.
684 unsigned LNumOps = LInst->getNumOperands(),
685 RNumOps = RInst->getNumOperands();
686 if (LNumOps != RNumOps)
687 return (int)LNumOps - (int)RNumOps;
688
689 for (unsigned Idx : seq(0u, LNumOps)) {
690 int Result =
691 CompareValueComplexity(EqCacheValue, LI, LInst->getOperand(Idx),
692 RInst->getOperand(Idx), Depth + 1);
693 if (Result != 0)
694 return Result;
695 }
696 }
697
698 EqCacheValue.unionSets(LV, RV);
699 return 0;
700}
701
702// Return negative, zero, or positive, if LHS is less than, equal to, or greater
703// than RHS, respectively. A three-way result allows recursive comparisons to be
704// more efficient.
705// If the max analysis depth was reached, return None, assuming we do not know
706// if they are equivalent for sure.
707static Optional<int>
708CompareSCEVComplexity(EquivalenceClasses<const SCEV *> &EqCacheSCEV,
709 EquivalenceClasses<const Value *> &EqCacheValue,
710 const LoopInfo *const LI, const SCEV *LHS,
711 const SCEV *RHS, DominatorTree &DT, unsigned Depth = 0) {
712 // Fast-path: SCEVs are uniqued so we can do a quick equality check.
713 if (LHS == RHS)
714 return 0;
715
716 // Primarily, sort the SCEVs by their getSCEVType().
717 SCEVTypes LType = LHS->getSCEVType(), RType = RHS->getSCEVType();
718 if (LType != RType)
719 return (int)LType - (int)RType;
720
721 if (EqCacheSCEV.isEquivalent(LHS, RHS))
722 return 0;
723
724 if (Depth > MaxSCEVCompareDepth)
725 return None;
726
727 // Aside from the getSCEVType() ordering, the particular ordering
728 // isn't very important except that it's beneficial to be consistent,
729 // so that (a + b) and (b + a) don't end up as different expressions.
730 switch (LType) {
731 case scUnknown: {
732 const SCEVUnknown *LU = cast<SCEVUnknown>(LHS);
733 const SCEVUnknown *RU = cast<SCEVUnknown>(RHS);
734
735 int X = CompareValueComplexity(EqCacheValue, LI, LU->getValue(),
736 RU->getValue(), Depth + 1);
737 if (X == 0)
738 EqCacheSCEV.unionSets(LHS, RHS);
739 return X;
740 }
741
742 case scConstant: {
743 const SCEVConstant *LC = cast<SCEVConstant>(LHS);
744 const SCEVConstant *RC = cast<SCEVConstant>(RHS);
745
746 // Compare constant values.
747 const APInt &LA = LC->getAPInt();
748 const APInt &RA = RC->getAPInt();
749 unsigned LBitWidth = LA.getBitWidth(), RBitWidth = RA.getBitWidth();
750 if (LBitWidth != RBitWidth)
751 return (int)LBitWidth - (int)RBitWidth;
752 return LA.ult(RA) ? -1 : 1;
753 }
754
755 case scAddRecExpr: {
756 const SCEVAddRecExpr *LA = cast<SCEVAddRecExpr>(LHS);
757 const SCEVAddRecExpr *RA = cast<SCEVAddRecExpr>(RHS);
758
759 // There is always a dominance between two recs that are used by one SCEV,
760 // so we can safely sort recs by loop header dominance. We require such
761 // order in getAddExpr.
762 const Loop *LLoop = LA->getLoop(), *RLoop = RA->getLoop();
763 if (LLoop != RLoop) {
764 const BasicBlock *LHead = LLoop->getHeader(), *RHead = RLoop->getHeader();
765 assert(LHead != RHead && "Two loops share the same header?")(static_cast <bool> (LHead != RHead && "Two loops share the same header?"
) ? void (0) : __assert_fail ("LHead != RHead && \"Two loops share the same header?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 765, __extension__
__PRETTY_FUNCTION__));
766 if (DT.dominates(LHead, RHead))
767 return 1;
768 else
769 assert(DT.dominates(RHead, LHead) &&(static_cast <bool> (DT.dominates(RHead, LHead) &&
"No dominance between recurrences used by one SCEV?") ? void
(0) : __assert_fail ("DT.dominates(RHead, LHead) && \"No dominance between recurrences used by one SCEV?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 770, __extension__
__PRETTY_FUNCTION__))
770 "No dominance between recurrences used by one SCEV?")(static_cast <bool> (DT.dominates(RHead, LHead) &&
"No dominance between recurrences used by one SCEV?") ? void
(0) : __assert_fail ("DT.dominates(RHead, LHead) && \"No dominance between recurrences used by one SCEV?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 770, __extension__
__PRETTY_FUNCTION__));
771 return -1;
772 }
773
774 // Addrec complexity grows with operand count.
775 unsigned LNumOps = LA->getNumOperands(), RNumOps = RA->getNumOperands();
776 if (LNumOps != RNumOps)
777 return (int)LNumOps - (int)RNumOps;
778
779 // Lexicographically compare.
780 for (unsigned i = 0; i != LNumOps; ++i) {
781 auto X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
782 LA->getOperand(i), RA->getOperand(i), DT,
783 Depth + 1);
784 if (X != 0)
785 return X;
786 }
787 EqCacheSCEV.unionSets(LHS, RHS);
788 return 0;
789 }
790
791 case scAddExpr:
792 case scMulExpr:
793 case scSMaxExpr:
794 case scUMaxExpr:
795 case scSMinExpr:
796 case scUMinExpr:
797 case scSequentialUMinExpr: {
798 const SCEVNAryExpr *LC = cast<SCEVNAryExpr>(LHS);
799 const SCEVNAryExpr *RC = cast<SCEVNAryExpr>(RHS);
800
801 // Lexicographically compare n-ary expressions.
802 unsigned LNumOps = LC->getNumOperands(), RNumOps = RC->getNumOperands();
803 if (LNumOps != RNumOps)
804 return (int)LNumOps - (int)RNumOps;
805
806 for (unsigned i = 0; i != LNumOps; ++i) {
807 auto X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
808 LC->getOperand(i), RC->getOperand(i), DT,
809 Depth + 1);
810 if (X != 0)
811 return X;
812 }
813 EqCacheSCEV.unionSets(LHS, RHS);
814 return 0;
815 }
816
817 case scUDivExpr: {
818 const SCEVUDivExpr *LC = cast<SCEVUDivExpr>(LHS);
819 const SCEVUDivExpr *RC = cast<SCEVUDivExpr>(RHS);
820
821 // Lexicographically compare udiv expressions.
822 auto X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getLHS(),
823 RC->getLHS(), DT, Depth + 1);
824 if (X != 0)
825 return X;
826 X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getRHS(),
827 RC->getRHS(), DT, Depth + 1);
828 if (X == 0)
829 EqCacheSCEV.unionSets(LHS, RHS);
830 return X;
831 }
832
833 case scPtrToInt:
834 case scTruncate:
835 case scZeroExtend:
836 case scSignExtend: {
837 const SCEVCastExpr *LC = cast<SCEVCastExpr>(LHS);
838 const SCEVCastExpr *RC = cast<SCEVCastExpr>(RHS);
839
840 // Compare cast expressions by operand.
841 auto X =
842 CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getOperand(),
843 RC->getOperand(), DT, Depth + 1);
844 if (X == 0)
845 EqCacheSCEV.unionSets(LHS, RHS);
846 return X;
847 }
848
849 case scCouldNotCompute:
850 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "llvm/lib/Analysis/ScalarEvolution.cpp", 850);
851 }
852 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 852);
853}
854
855/// Given a list of SCEV objects, order them by their complexity, and group
856/// objects of the same complexity together by value. When this routine is
857/// finished, we know that any duplicates in the vector are consecutive and that
858/// complexity is monotonically increasing.
859///
860/// Note that we go take special precautions to ensure that we get deterministic
861/// results from this routine. In other words, we don't want the results of
862/// this to depend on where the addresses of various SCEV objects happened to
863/// land in memory.
864static void GroupByComplexity(SmallVectorImpl<const SCEV *> &Ops,
865 LoopInfo *LI, DominatorTree &DT) {
866 if (Ops.size() < 2) return; // Noop
867
868 EquivalenceClasses<const SCEV *> EqCacheSCEV;
869 EquivalenceClasses<const Value *> EqCacheValue;
870
871 // Whether LHS has provably less complexity than RHS.
872 auto IsLessComplex = [&](const SCEV *LHS, const SCEV *RHS) {
873 auto Complexity =
874 CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LHS, RHS, DT);
875 return Complexity && *Complexity < 0;
876 };
877 if (Ops.size() == 2) {
878 // This is the common case, which also happens to be trivially simple.
879 // Special case it.
880 const SCEV *&LHS = Ops[0], *&RHS = Ops[1];
881 if (IsLessComplex(RHS, LHS))
882 std::swap(LHS, RHS);
883 return;
884 }
885
886 // Do the rough sort by complexity.
887 llvm::stable_sort(Ops, [&](const SCEV *LHS, const SCEV *RHS) {
888 return IsLessComplex(LHS, RHS);
889 });
890
891 // Now that we are sorted by complexity, group elements of the same
892 // complexity. Note that this is, at worst, N^2, but the vector is likely to
893 // be extremely short in practice. Note that we take this approach because we
894 // do not want to depend on the addresses of the objects we are grouping.
895 for (unsigned i = 0, e = Ops.size(); i != e-2; ++i) {
896 const SCEV *S = Ops[i];
897 unsigned Complexity = S->getSCEVType();
898
899 // If there are any objects of the same complexity and same value as this
900 // one, group them.
901 for (unsigned j = i+1; j != e && Ops[j]->getSCEVType() == Complexity; ++j) {
902 if (Ops[j] == S) { // Found a duplicate.
903 // Move it to immediately after i'th element.
904 std::swap(Ops[i+1], Ops[j]);
905 ++i; // no need to rescan it.
906 if (i == e-2) return; // Done!
907 }
908 }
909 }
910}
911
912/// Returns true if \p Ops contains a huge SCEV (the subtree of S contains at
913/// least HugeExprThreshold nodes).
914static bool hasHugeExpression(ArrayRef<const SCEV *> Ops) {
915 return any_of(Ops, [](const SCEV *S) {
916 return S->getExpressionSize() >= HugeExprThreshold;
917 });
918}
919
920//===----------------------------------------------------------------------===//
921// Simple SCEV method implementations
922//===----------------------------------------------------------------------===//
923
924/// Compute BC(It, K). The result has width W. Assume, K > 0.
925static const SCEV *BinomialCoefficient(const SCEV *It, unsigned K,
926 ScalarEvolution &SE,
927 Type *ResultTy) {
928 // Handle the simplest case efficiently.
929 if (K == 1)
930 return SE.getTruncateOrZeroExtend(It, ResultTy);
931
932 // We are using the following formula for BC(It, K):
933 //
934 // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / K!
935 //
936 // Suppose, W is the bitwidth of the return value. We must be prepared for
937 // overflow. Hence, we must assure that the result of our computation is
938 // equal to the accurate one modulo 2^W. Unfortunately, division isn't
939 // safe in modular arithmetic.
940 //
941 // However, this code doesn't use exactly that formula; the formula it uses
942 // is something like the following, where T is the number of factors of 2 in
943 // K! (i.e. trailing zeros in the binary representation of K!), and ^ is
944 // exponentiation:
945 //
946 // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / 2^T / (K! / 2^T)
947 //
948 // This formula is trivially equivalent to the previous formula. However,
949 // this formula can be implemented much more efficiently. The trick is that
950 // K! / 2^T is odd, and exact division by an odd number *is* safe in modular
951 // arithmetic. To do exact division in modular arithmetic, all we have
952 // to do is multiply by the inverse. Therefore, this step can be done at
953 // width W.
954 //
955 // The next issue is how to safely do the division by 2^T. The way this
956 // is done is by doing the multiplication step at a width of at least W + T
957 // bits. This way, the bottom W+T bits of the product are accurate. Then,
958 // when we perform the division by 2^T (which is equivalent to a right shift
959 // by T), the bottom W bits are accurate. Extra bits are okay; they'll get
960 // truncated out after the division by 2^T.
961 //
962 // In comparison to just directly using the first formula, this technique
963 // is much more efficient; using the first formula requires W * K bits,
964 // but this formula less than W + K bits. Also, the first formula requires
965 // a division step, whereas this formula only requires multiplies and shifts.
966 //
967 // It doesn't matter whether the subtraction step is done in the calculation
968 // width or the input iteration count's width; if the subtraction overflows,
969 // the result must be zero anyway. We prefer here to do it in the width of
970 // the induction variable because it helps a lot for certain cases; CodeGen
971 // isn't smart enough to ignore the overflow, which leads to much less
972 // efficient code if the width of the subtraction is wider than the native
973 // register width.
974 //
975 // (It's possible to not widen at all by pulling out factors of 2 before
976 // the multiplication; for example, K=2 can be calculated as
977 // It/2*(It+(It*INT_MIN/INT_MIN)+-1). However, it requires
978 // extra arithmetic, so it's not an obvious win, and it gets
979 // much more complicated for K > 3.)
980
981 // Protection from insane SCEVs; this bound is conservative,
982 // but it probably doesn't matter.
983 if (K > 1000)
984 return SE.getCouldNotCompute();
985
986 unsigned W = SE.getTypeSizeInBits(ResultTy);
987
988 // Calculate K! / 2^T and T; we divide out the factors of two before
989 // multiplying for calculating K! / 2^T to avoid overflow.
990 // Other overflow doesn't matter because we only care about the bottom
991 // W bits of the result.
992 APInt OddFactorial(W, 1);
993 unsigned T = 1;
994 for (unsigned i = 3; i <= K; ++i) {
995 APInt Mult(W, i);
996 unsigned TwoFactors = Mult.countTrailingZeros();
997 T += TwoFactors;
998 Mult.lshrInPlace(TwoFactors);
999 OddFactorial *= Mult;
1000 }
1001
1002 // We need at least W + T bits for the multiplication step
1003 unsigned CalculationBits = W + T;
1004
1005 // Calculate 2^T, at width T+W.
1006 APInt DivFactor = APInt::getOneBitSet(CalculationBits, T);
1007
1008 // Calculate the multiplicative inverse of K! / 2^T;
1009 // this multiplication factor will perform the exact division by
1010 // K! / 2^T.
1011 APInt Mod = APInt::getSignedMinValue(W+1);
1012 APInt MultiplyFactor = OddFactorial.zext(W+1);
1013 MultiplyFactor = MultiplyFactor.multiplicativeInverse(Mod);
1014 MultiplyFactor = MultiplyFactor.trunc(W);
1015
1016 // Calculate the product, at width T+W
1017 IntegerType *CalculationTy = IntegerType::get(SE.getContext(),
1018 CalculationBits);
1019 const SCEV *Dividend = SE.getTruncateOrZeroExtend(It, CalculationTy);
1020 for (unsigned i = 1; i != K; ++i) {
1021 const SCEV *S = SE.getMinusSCEV(It, SE.getConstant(It->getType(), i));
1022 Dividend = SE.getMulExpr(Dividend,
1023 SE.getTruncateOrZeroExtend(S, CalculationTy));
1024 }
1025
1026 // Divide by 2^T
1027 const SCEV *DivResult = SE.getUDivExpr(Dividend, SE.getConstant(DivFactor));
1028
1029 // Truncate the result, and divide by K! / 2^T.
1030
1031 return SE.getMulExpr(SE.getConstant(MultiplyFactor),
1032 SE.getTruncateOrZeroExtend(DivResult, ResultTy));
1033}
1034
1035/// Return the value of this chain of recurrences at the specified iteration
1036/// number. We can evaluate this recurrence by multiplying each element in the
1037/// chain by the binomial coefficient corresponding to it. In other words, we
1038/// can evaluate {A,+,B,+,C,+,D} as:
1039///
1040/// A*BC(It, 0) + B*BC(It, 1) + C*BC(It, 2) + D*BC(It, 3)
1041///
1042/// where BC(It, k) stands for binomial coefficient.
1043const SCEV *SCEVAddRecExpr::evaluateAtIteration(const SCEV *It,
1044 ScalarEvolution &SE) const {
1045 return evaluateAtIteration(makeArrayRef(op_begin(), op_end()), It, SE);
1046}
1047
1048const SCEV *
1049SCEVAddRecExpr::evaluateAtIteration(ArrayRef<const SCEV *> Operands,
1050 const SCEV *It, ScalarEvolution &SE) {
1051 assert(Operands.size() > 0)(static_cast <bool> (Operands.size() > 0) ? void (0)
: __assert_fail ("Operands.size() > 0", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 1051, __extension__ __PRETTY_FUNCTION__));
1052 const SCEV *Result = Operands[0];
1053 for (unsigned i = 1, e = Operands.size(); i != e; ++i) {
1054 // The computation is correct in the face of overflow provided that the
1055 // multiplication is performed _after_ the evaluation of the binomial
1056 // coefficient.
1057 const SCEV *Coeff = BinomialCoefficient(It, i, SE, Result->getType());
1058 if (isa<SCEVCouldNotCompute>(Coeff))
1059 return Coeff;
1060
1061 Result = SE.getAddExpr(Result, SE.getMulExpr(Operands[i], Coeff));
1062 }
1063 return Result;
1064}
1065
1066//===----------------------------------------------------------------------===//
1067// SCEV Expression folder implementations
1068//===----------------------------------------------------------------------===//
1069
1070const SCEV *ScalarEvolution::getLosslessPtrToIntExpr(const SCEV *Op,
1071 unsigned Depth) {
1072 assert(Depth <= 1 &&(static_cast <bool> (Depth <= 1 && "getLosslessPtrToIntExpr() should self-recurse at most once."
) ? void (0) : __assert_fail ("Depth <= 1 && \"getLosslessPtrToIntExpr() should self-recurse at most once.\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1073, __extension__
__PRETTY_FUNCTION__))
1073 "getLosslessPtrToIntExpr() should self-recurse at most once.")(static_cast <bool> (Depth <= 1 && "getLosslessPtrToIntExpr() should self-recurse at most once."
) ? void (0) : __assert_fail ("Depth <= 1 && \"getLosslessPtrToIntExpr() should self-recurse at most once.\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1073, __extension__
__PRETTY_FUNCTION__));
1074
1075 // We could be called with an integer-typed operands during SCEV rewrites.
1076 // Since the operand is an integer already, just perform zext/trunc/self cast.
1077 if (!Op->getType()->isPointerTy())
1078 return Op;
1079
1080 // What would be an ID for such a SCEV cast expression?
1081 FoldingSetNodeID ID;
1082 ID.AddInteger(scPtrToInt);
1083 ID.AddPointer(Op);
1084
1085 void *IP = nullptr;
1086
1087 // Is there already an expression for such a cast?
1088 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
1089 return S;
1090
1091 // It isn't legal for optimizations to construct new ptrtoint expressions
1092 // for non-integral pointers.
1093 if (getDataLayout().isNonIntegralPointerType(Op->getType()))
1094 return getCouldNotCompute();
1095
1096 Type *IntPtrTy = getDataLayout().getIntPtrType(Op->getType());
1097
1098 // We can only trivially model ptrtoint if SCEV's effective (integer) type
1099 // is sufficiently wide to represent all possible pointer values.
1100 // We could theoretically teach SCEV to truncate wider pointers, but
1101 // that isn't implemented for now.
1102 if (getDataLayout().getTypeSizeInBits(getEffectiveSCEVType(Op->getType())) !=
1103 getDataLayout().getTypeSizeInBits(IntPtrTy))
1104 return getCouldNotCompute();
1105
1106 // If not, is this expression something we can't reduce any further?
1107 if (auto *U = dyn_cast<SCEVUnknown>(Op)) {
1108 // Perform some basic constant folding. If the operand of the ptr2int cast
1109 // is a null pointer, don't create a ptr2int SCEV expression (that will be
1110 // left as-is), but produce a zero constant.
1111 // NOTE: We could handle a more general case, but lack motivational cases.
1112 if (isa<ConstantPointerNull>(U->getValue()))
1113 return getZero(IntPtrTy);
1114
1115 // Create an explicit cast node.
1116 // We can reuse the existing insert position since if we get here,
1117 // we won't have made any changes which would invalidate it.
1118 SCEV *S = new (SCEVAllocator)
1119 SCEVPtrToIntExpr(ID.Intern(SCEVAllocator), Op, IntPtrTy);
1120 UniqueSCEVs.InsertNode(S, IP);
1121 registerUser(S, Op);
1122 return S;
1123 }
1124
1125 assert(Depth == 0 && "getLosslessPtrToIntExpr() should not self-recurse for "(static_cast <bool> (Depth == 0 && "getLosslessPtrToIntExpr() should not self-recurse for "
"non-SCEVUnknown's.") ? void (0) : __assert_fail ("Depth == 0 && \"getLosslessPtrToIntExpr() should not self-recurse for \" \"non-SCEVUnknown's.\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1126, __extension__
__PRETTY_FUNCTION__))
1126 "non-SCEVUnknown's.")(static_cast <bool> (Depth == 0 && "getLosslessPtrToIntExpr() should not self-recurse for "
"non-SCEVUnknown's.") ? void (0) : __assert_fail ("Depth == 0 && \"getLosslessPtrToIntExpr() should not self-recurse for \" \"non-SCEVUnknown's.\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1126, __extension__
__PRETTY_FUNCTION__));
1127
1128 // Otherwise, we've got some expression that is more complex than just a
1129 // single SCEVUnknown. But we don't want to have a SCEVPtrToIntExpr of an
1130 // arbitrary expression, we want to have SCEVPtrToIntExpr of an SCEVUnknown
1131 // only, and the expressions must otherwise be integer-typed.
1132 // So sink the cast down to the SCEVUnknown's.
1133
1134 /// The SCEVPtrToIntSinkingRewriter takes a scalar evolution expression,
1135 /// which computes a pointer-typed value, and rewrites the whole expression
1136 /// tree so that *all* the computations are done on integers, and the only
1137 /// pointer-typed operands in the expression are SCEVUnknown.
1138 class SCEVPtrToIntSinkingRewriter
1139 : public SCEVRewriteVisitor<SCEVPtrToIntSinkingRewriter> {
1140 using Base = SCEVRewriteVisitor<SCEVPtrToIntSinkingRewriter>;
1141
1142 public:
1143 SCEVPtrToIntSinkingRewriter(ScalarEvolution &SE) : SCEVRewriteVisitor(SE) {}
1144
1145 static const SCEV *rewrite(const SCEV *Scev, ScalarEvolution &SE) {
1146 SCEVPtrToIntSinkingRewriter Rewriter(SE);
1147 return Rewriter.visit(Scev);
1148 }
1149
1150 const SCEV *visit(const SCEV *S) {
1151 Type *STy = S->getType();
1152 // If the expression is not pointer-typed, just keep it as-is.
1153 if (!STy->isPointerTy())
1154 return S;
1155 // Else, recursively sink the cast down into it.
1156 return Base::visit(S);
1157 }
1158
1159 const SCEV *visitAddExpr(const SCEVAddExpr *Expr) {
1160 SmallVector<const SCEV *, 2> Operands;
1161 bool Changed = false;
1162 for (auto *Op : Expr->operands()) {
1163 Operands.push_back(visit(Op));
1164 Changed |= Op != Operands.back();
1165 }
1166 return !Changed ? Expr : SE.getAddExpr(Operands, Expr->getNoWrapFlags());
1167 }
1168
1169 const SCEV *visitMulExpr(const SCEVMulExpr *Expr) {
1170 SmallVector<const SCEV *, 2> Operands;
1171 bool Changed = false;
1172 for (auto *Op : Expr->operands()) {
1173 Operands.push_back(visit(Op));
1174 Changed |= Op != Operands.back();
1175 }
1176 return !Changed ? Expr : SE.getMulExpr(Operands, Expr->getNoWrapFlags());
1177 }
1178
1179 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
1180 assert(Expr->getType()->isPointerTy() &&(static_cast <bool> (Expr->getType()->isPointerTy
() && "Should only reach pointer-typed SCEVUnknown's."
) ? void (0) : __assert_fail ("Expr->getType()->isPointerTy() && \"Should only reach pointer-typed SCEVUnknown's.\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1181, __extension__
__PRETTY_FUNCTION__))
1181 "Should only reach pointer-typed SCEVUnknown's.")(static_cast <bool> (Expr->getType()->isPointerTy
() && "Should only reach pointer-typed SCEVUnknown's."
) ? void (0) : __assert_fail ("Expr->getType()->isPointerTy() && \"Should only reach pointer-typed SCEVUnknown's.\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1181, __extension__
__PRETTY_FUNCTION__));
1182 return SE.getLosslessPtrToIntExpr(Expr, /*Depth=*/1);
1183 }
1184 };
1185
1186 // And actually perform the cast sinking.
1187 const SCEV *IntOp = SCEVPtrToIntSinkingRewriter::rewrite(Op, *this);
1188 assert(IntOp->getType()->isIntegerTy() &&(static_cast <bool> (IntOp->getType()->isIntegerTy
() && "We must have succeeded in sinking the cast, " "and ending up with an integer-typed expression!"
) ? void (0) : __assert_fail ("IntOp->getType()->isIntegerTy() && \"We must have succeeded in sinking the cast, \" \"and ending up with an integer-typed expression!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1190, __extension__
__PRETTY_FUNCTION__))
1189 "We must have succeeded in sinking the cast, "(static_cast <bool> (IntOp->getType()->isIntegerTy
() && "We must have succeeded in sinking the cast, " "and ending up with an integer-typed expression!"
) ? void (0) : __assert_fail ("IntOp->getType()->isIntegerTy() && \"We must have succeeded in sinking the cast, \" \"and ending up with an integer-typed expression!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1190, __extension__
__PRETTY_FUNCTION__))
1190 "and ending up with an integer-typed expression!")(static_cast <bool> (IntOp->getType()->isIntegerTy
() && "We must have succeeded in sinking the cast, " "and ending up with an integer-typed expression!"
) ? void (0) : __assert_fail ("IntOp->getType()->isIntegerTy() && \"We must have succeeded in sinking the cast, \" \"and ending up with an integer-typed expression!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1190, __extension__
__PRETTY_FUNCTION__));
1191 return IntOp;
1192}
1193
1194const SCEV *ScalarEvolution::getPtrToIntExpr(const SCEV *Op, Type *Ty) {
1195 assert(Ty->isIntegerTy() && "Target type must be an integer type!")(static_cast <bool> (Ty->isIntegerTy() && "Target type must be an integer type!"
) ? void (0) : __assert_fail ("Ty->isIntegerTy() && \"Target type must be an integer type!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1195, __extension__
__PRETTY_FUNCTION__));
1196
1197 const SCEV *IntOp = getLosslessPtrToIntExpr(Op);
1198 if (isa<SCEVCouldNotCompute>(IntOp))
1199 return IntOp;
1200
1201 return getTruncateOrZeroExtend(IntOp, Ty);
1202}
1203
1204const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op, Type *Ty,
1205 unsigned Depth) {
1206 assert(getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(Op->getType()
) > getTypeSizeInBits(Ty) && "This is not a truncating conversion!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) && \"This is not a truncating conversion!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1207, __extension__
__PRETTY_FUNCTION__))
1207 "This is not a truncating conversion!")(static_cast <bool> (getTypeSizeInBits(Op->getType()
) > getTypeSizeInBits(Ty) && "This is not a truncating conversion!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) && \"This is not a truncating conversion!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1207, __extension__
__PRETTY_FUNCTION__));
1208 assert(isSCEVable(Ty) &&(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1209, __extension__
__PRETTY_FUNCTION__))
1209 "This is not a conversion to a SCEVable type!")(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1209, __extension__
__PRETTY_FUNCTION__));
1210 assert(!Op->getType()->isPointerTy() && "Can't truncate pointer!")(static_cast <bool> (!Op->getType()->isPointerTy(
) && "Can't truncate pointer!") ? void (0) : __assert_fail
("!Op->getType()->isPointerTy() && \"Can't truncate pointer!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1210, __extension__
__PRETTY_FUNCTION__));
1211 Ty = getEffectiveSCEVType(Ty);
1212
1213 FoldingSetNodeID ID;
1214 ID.AddInteger(scTruncate);
1215 ID.AddPointer(Op);
1216 ID.AddPointer(Ty);
1217 void *IP = nullptr;
1218 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1219
1220 // Fold if the operand is constant.
1221 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1222 return getConstant(
1223 cast<ConstantInt>(ConstantExpr::getTrunc(SC->getValue(), Ty)));
1224
1225 // trunc(trunc(x)) --> trunc(x)
1226 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op))
1227 return getTruncateExpr(ST->getOperand(), Ty, Depth + 1);
1228
1229 // trunc(sext(x)) --> sext(x) if widening or trunc(x) if narrowing
1230 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1231 return getTruncateOrSignExtend(SS->getOperand(), Ty, Depth + 1);
1232
1233 // trunc(zext(x)) --> zext(x) if widening or trunc(x) if narrowing
1234 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1235 return getTruncateOrZeroExtend(SZ->getOperand(), Ty, Depth + 1);
1236
1237 if (Depth > MaxCastDepth) {
1238 SCEV *S =
1239 new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator), Op, Ty);
1240 UniqueSCEVs.InsertNode(S, IP);
1241 registerUser(S, Op);
1242 return S;
1243 }
1244
1245 // trunc(x1 + ... + xN) --> trunc(x1) + ... + trunc(xN) and
1246 // trunc(x1 * ... * xN) --> trunc(x1) * ... * trunc(xN),
1247 // if after transforming we have at most one truncate, not counting truncates
1248 // that replace other casts.
1249 if (isa<SCEVAddExpr>(Op) || isa<SCEVMulExpr>(Op)) {
1250 auto *CommOp = cast<SCEVCommutativeExpr>(Op);
1251 SmallVector<const SCEV *, 4> Operands;
1252 unsigned numTruncs = 0;
1253 for (unsigned i = 0, e = CommOp->getNumOperands(); i != e && numTruncs < 2;
1254 ++i) {
1255 const SCEV *S = getTruncateExpr(CommOp->getOperand(i), Ty, Depth + 1);
1256 if (!isa<SCEVIntegralCastExpr>(CommOp->getOperand(i)) &&
1257 isa<SCEVTruncateExpr>(S))
1258 numTruncs++;
1259 Operands.push_back(S);
1260 }
1261 if (numTruncs < 2) {
1262 if (isa<SCEVAddExpr>(Op))
1263 return getAddExpr(Operands);
1264 else if (isa<SCEVMulExpr>(Op))
1265 return getMulExpr(Operands);
1266 else
1267 llvm_unreachable("Unexpected SCEV type for Op.")::llvm::llvm_unreachable_internal("Unexpected SCEV type for Op."
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1267);
1268 }
1269 // Although we checked in the beginning that ID is not in the cache, it is
1270 // possible that during recursion and different modification ID was inserted
1271 // into the cache. So if we find it, just return it.
1272 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
1273 return S;
1274 }
1275
1276 // If the input value is a chrec scev, truncate the chrec's operands.
1277 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
1278 SmallVector<const SCEV *, 4> Operands;
1279 for (const SCEV *Op : AddRec->operands())
1280 Operands.push_back(getTruncateExpr(Op, Ty, Depth + 1));
1281 return getAddRecExpr(Operands, AddRec->getLoop(), SCEV::FlagAnyWrap);
1282 }
1283
1284 // Return zero if truncating to known zeros.
1285 uint32_t MinTrailingZeros = GetMinTrailingZeros(Op);
1286 if (MinTrailingZeros >= getTypeSizeInBits(Ty))
1287 return getZero(Ty);
1288
1289 // The cast wasn't folded; create an explicit cast node. We can reuse
1290 // the existing insert position since if we get here, we won't have
1291 // made any changes which would invalidate it.
1292 SCEV *S = new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator),
1293 Op, Ty);
1294 UniqueSCEVs.InsertNode(S, IP);
1295 registerUser(S, Op);
1296 return S;
1297}
1298
1299// Get the limit of a recurrence such that incrementing by Step cannot cause
1300// signed overflow as long as the value of the recurrence within the
1301// loop does not exceed this limit before incrementing.
1302static const SCEV *getSignedOverflowLimitForStep(const SCEV *Step,
1303 ICmpInst::Predicate *Pred,
1304 ScalarEvolution *SE) {
1305 unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
1306 if (SE->isKnownPositive(Step)) {
1307 *Pred = ICmpInst::ICMP_SLT;
1308 return SE->getConstant(APInt::getSignedMinValue(BitWidth) -
1309 SE->getSignedRangeMax(Step));
1310 }
1311 if (SE->isKnownNegative(Step)) {
1312 *Pred = ICmpInst::ICMP_SGT;
1313 return SE->getConstant(APInt::getSignedMaxValue(BitWidth) -
1314 SE->getSignedRangeMin(Step));
1315 }
1316 return nullptr;
1317}
1318
1319// Get the limit of a recurrence such that incrementing by Step cannot cause
1320// unsigned overflow as long as the value of the recurrence within the loop does
1321// not exceed this limit before incrementing.
1322static const SCEV *getUnsignedOverflowLimitForStep(const SCEV *Step,
1323 ICmpInst::Predicate *Pred,
1324 ScalarEvolution *SE) {
1325 unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
1326 *Pred = ICmpInst::ICMP_ULT;
1327
1328 return SE->getConstant(APInt::getMinValue(BitWidth) -
1329 SE->getUnsignedRangeMax(Step));
1330}
1331
1332namespace {
1333
1334struct ExtendOpTraitsBase {
1335 typedef const SCEV *(ScalarEvolution::*GetExtendExprTy)(const SCEV *, Type *,
1336 unsigned);
1337};
1338
1339// Used to make code generic over signed and unsigned overflow.
1340template <typename ExtendOp> struct ExtendOpTraits {
1341 // Members present:
1342 //
1343 // static const SCEV::NoWrapFlags WrapType;
1344 //
1345 // static const ExtendOpTraitsBase::GetExtendExprTy GetExtendExpr;
1346 //
1347 // static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1348 // ICmpInst::Predicate *Pred,
1349 // ScalarEvolution *SE);
1350};
1351
1352template <>
1353struct ExtendOpTraits<SCEVSignExtendExpr> : public ExtendOpTraitsBase {
1354 static const SCEV::NoWrapFlags WrapType = SCEV::FlagNSW;
1355
1356 static const GetExtendExprTy GetExtendExpr;
1357
1358 static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1359 ICmpInst::Predicate *Pred,
1360 ScalarEvolution *SE) {
1361 return getSignedOverflowLimitForStep(Step, Pred, SE);
1362 }
1363};
1364
1365const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
1366 SCEVSignExtendExpr>::GetExtendExpr = &ScalarEvolution::getSignExtendExpr;
1367
1368template <>
1369struct ExtendOpTraits<SCEVZeroExtendExpr> : public ExtendOpTraitsBase {
1370 static const SCEV::NoWrapFlags WrapType = SCEV::FlagNUW;
1371
1372 static const GetExtendExprTy GetExtendExpr;
1373
1374 static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1375 ICmpInst::Predicate *Pred,
1376 ScalarEvolution *SE) {
1377 return getUnsignedOverflowLimitForStep(Step, Pred, SE);
1378 }
1379};
1380
1381const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
1382 SCEVZeroExtendExpr>::GetExtendExpr = &ScalarEvolution::getZeroExtendExpr;
1383
1384} // end anonymous namespace
1385
1386// The recurrence AR has been shown to have no signed/unsigned wrap or something
1387// close to it. Typically, if we can prove NSW/NUW for AR, then we can just as
1388// easily prove NSW/NUW for its preincrement or postincrement sibling. This
1389// allows normalizing a sign/zero extended AddRec as such: {sext/zext(Step +
1390// Start),+,Step} => {(Step + sext/zext(Start),+,Step} As a result, the
1391// expression "Step + sext/zext(PreIncAR)" is congruent with
1392// "sext/zext(PostIncAR)"
1393template <typename ExtendOpTy>
1394static const SCEV *getPreStartForExtend(const SCEVAddRecExpr *AR, Type *Ty,
1395 ScalarEvolution *SE, unsigned Depth) {
1396 auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
1397 auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
1398
1399 const Loop *L = AR->getLoop();
1400 const SCEV *Start = AR->getStart();
1401 const SCEV *Step = AR->getStepRecurrence(*SE);
1402
1403 // Check for a simple looking step prior to loop entry.
1404 const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Start);
1405 if (!SA)
1406 return nullptr;
1407
1408 // Create an AddExpr for "PreStart" after subtracting Step. Full SCEV
1409 // subtraction is expensive. For this purpose, perform a quick and dirty
1410 // difference, by checking for Step in the operand list.
1411 SmallVector<const SCEV *, 4> DiffOps;
1412 for (const SCEV *Op : SA->operands())
1413 if (Op != Step)
1414 DiffOps.push_back(Op);
1415
1416 if (DiffOps.size() == SA->getNumOperands())
1417 return nullptr;
1418
1419 // Try to prove `WrapType` (SCEV::FlagNSW or SCEV::FlagNUW) on `PreStart` +
1420 // `Step`:
1421
1422 // 1. NSW/NUW flags on the step increment.
1423 auto PreStartFlags =
1424 ScalarEvolution::maskFlags(SA->getNoWrapFlags(), SCEV::FlagNUW);
1425 const SCEV *PreStart = SE->getAddExpr(DiffOps, PreStartFlags);
1426 const SCEVAddRecExpr *PreAR = dyn_cast<SCEVAddRecExpr>(
1427 SE->getAddRecExpr(PreStart, Step, L, SCEV::FlagAnyWrap));
1428
1429 // "{S,+,X} is <nsw>/<nuw>" and "the backedge is taken at least once" implies
1430 // "S+X does not sign/unsign-overflow".
1431 //
1432
1433 const SCEV *BECount = SE->getBackedgeTakenCount(L);
1434 if (PreAR && PreAR->getNoWrapFlags(WrapType) &&
1435 !isa<SCEVCouldNotCompute>(BECount) && SE->isKnownPositive(BECount))
1436 return PreStart;
1437
1438 // 2. Direct overflow check on the step operation's expression.
1439 unsigned BitWidth = SE->getTypeSizeInBits(AR->getType());
1440 Type *WideTy = IntegerType::get(SE->getContext(), BitWidth * 2);
1441 const SCEV *OperandExtendedStart =
1442 SE->getAddExpr((SE->*GetExtendExpr)(PreStart, WideTy, Depth),
1443 (SE->*GetExtendExpr)(Step, WideTy, Depth));
1444 if ((SE->*GetExtendExpr)(Start, WideTy, Depth) == OperandExtendedStart) {
1445 if (PreAR && AR->getNoWrapFlags(WrapType)) {
1446 // If we know `AR` == {`PreStart`+`Step`,+,`Step`} is `WrapType` (FlagNSW
1447 // or FlagNUW) and that `PreStart` + `Step` is `WrapType` too, then
1448 // `PreAR` == {`PreStart`,+,`Step`} is also `WrapType`. Cache this fact.
1449 SE->setNoWrapFlags(const_cast<SCEVAddRecExpr *>(PreAR), WrapType);
1450 }
1451 return PreStart;
1452 }
1453
1454 // 3. Loop precondition.
1455 ICmpInst::Predicate Pred;
1456 const SCEV *OverflowLimit =
1457 ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(Step, &Pred, SE);
1458
1459 if (OverflowLimit &&
1460 SE->isLoopEntryGuardedByCond(L, Pred, PreStart, OverflowLimit))
1461 return PreStart;
1462
1463 return nullptr;
1464}
1465
1466// Get the normalized zero or sign extended expression for this AddRec's Start.
1467template <typename ExtendOpTy>
1468static const SCEV *getExtendAddRecStart(const SCEVAddRecExpr *AR, Type *Ty,
1469 ScalarEvolution *SE,
1470 unsigned Depth) {
1471 auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
1472
1473 const SCEV *PreStart = getPreStartForExtend<ExtendOpTy>(AR, Ty, SE, Depth);
1474 if (!PreStart)
1475 return (SE->*GetExtendExpr)(AR->getStart(), Ty, Depth);
1476
1477 return SE->getAddExpr((SE->*GetExtendExpr)(AR->getStepRecurrence(*SE), Ty,
1478 Depth),
1479 (SE->*GetExtendExpr)(PreStart, Ty, Depth));
1480}
1481
1482// Try to prove away overflow by looking at "nearby" add recurrences. A
1483// motivating example for this rule: if we know `{0,+,4}` is `ult` `-1` and it
1484// does not itself wrap then we can conclude that `{1,+,4}` is `nuw`.
1485//
1486// Formally:
1487//
1488// {S,+,X} == {S-T,+,X} + T
1489// => Ext({S,+,X}) == Ext({S-T,+,X} + T)
1490//
1491// If ({S-T,+,X} + T) does not overflow ... (1)
1492//
1493// RHS == Ext({S-T,+,X} + T) == Ext({S-T,+,X}) + Ext(T)
1494//
1495// If {S-T,+,X} does not overflow ... (2)
1496//
1497// RHS == Ext({S-T,+,X}) + Ext(T) == {Ext(S-T),+,Ext(X)} + Ext(T)
1498// == {Ext(S-T)+Ext(T),+,Ext(X)}
1499//
1500// If (S-T)+T does not overflow ... (3)
1501//
1502// RHS == {Ext(S-T)+Ext(T),+,Ext(X)} == {Ext(S-T+T),+,Ext(X)}
1503// == {Ext(S),+,Ext(X)} == LHS
1504//
1505// Thus, if (1), (2) and (3) are true for some T, then
1506// Ext({S,+,X}) == {Ext(S),+,Ext(X)}
1507//
1508// (3) is implied by (1) -- "(S-T)+T does not overflow" is simply "({S-T,+,X}+T)
1509// does not overflow" restricted to the 0th iteration. Therefore we only need
1510// to check for (1) and (2).
1511//
1512// In the current context, S is `Start`, X is `Step`, Ext is `ExtendOpTy` and T
1513// is `Delta` (defined below).
1514template <typename ExtendOpTy>
1515bool ScalarEvolution::proveNoWrapByVaryingStart(const SCEV *Start,
1516 const SCEV *Step,
1517 const Loop *L) {
1518 auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
1519
1520 // We restrict `Start` to a constant to prevent SCEV from spending too much
1521 // time here. It is correct (but more expensive) to continue with a
1522 // non-constant `Start` and do a general SCEV subtraction to compute
1523 // `PreStart` below.
1524 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start);
1525 if (!StartC)
1526 return false;
1527
1528 APInt StartAI = StartC->getAPInt();
1529
1530 for (unsigned Delta : {-2, -1, 1, 2}) {
1531 const SCEV *PreStart = getConstant(StartAI - Delta);
1532
1533 FoldingSetNodeID ID;
1534 ID.AddInteger(scAddRecExpr);
1535 ID.AddPointer(PreStart);
1536 ID.AddPointer(Step);
1537 ID.AddPointer(L);
1538 void *IP = nullptr;
1539 const auto *PreAR =
1540 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
1541
1542 // Give up if we don't already have the add recurrence we need because
1543 // actually constructing an add recurrence is relatively expensive.
1544 if (PreAR && PreAR->getNoWrapFlags(WrapType)) { // proves (2)
1545 const SCEV *DeltaS = getConstant(StartC->getType(), Delta);
1546 ICmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE;
1547 const SCEV *Limit = ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(
1548 DeltaS, &Pred, this);
1549 if (Limit && isKnownPredicate(Pred, PreAR, Limit)) // proves (1)
1550 return true;
1551 }
1552 }
1553
1554 return false;
1555}
1556
1557// Finds an integer D for an expression (C + x + y + ...) such that the top
1558// level addition in (D + (C - D + x + y + ...)) would not wrap (signed or
1559// unsigned) and the number of trailing zeros of (C - D + x + y + ...) is
1560// maximized, where C is the \p ConstantTerm, x, y, ... are arbitrary SCEVs, and
1561// the (C + x + y + ...) expression is \p WholeAddExpr.
1562static APInt extractConstantWithoutWrapping(ScalarEvolution &SE,
1563 const SCEVConstant *ConstantTerm,
1564 const SCEVAddExpr *WholeAddExpr) {
1565 const APInt &C = ConstantTerm->getAPInt();
1566 const unsigned BitWidth = C.getBitWidth();
1567 // Find number of trailing zeros of (x + y + ...) w/o the C first:
1568 uint32_t TZ = BitWidth;
1569 for (unsigned I = 1, E = WholeAddExpr->getNumOperands(); I < E && TZ; ++I)
1570 TZ = std::min(TZ, SE.GetMinTrailingZeros(WholeAddExpr->getOperand(I)));
1571 if (TZ) {
1572 // Set D to be as many least significant bits of C as possible while still
1573 // guaranteeing that adding D to (C - D + x + y + ...) won't cause a wrap:
1574 return TZ < BitWidth ? C.trunc(TZ).zext(BitWidth) : C;
1575 }
1576 return APInt(BitWidth, 0);
1577}
1578
1579// Finds an integer D for an affine AddRec expression {C,+,x} such that the top
1580// level addition in (D + {C-D,+,x}) would not wrap (signed or unsigned) and the
1581// number of trailing zeros of (C - D + x * n) is maximized, where C is the \p
1582// ConstantStart, x is an arbitrary \p Step, and n is the loop trip count.
1583static APInt extractConstantWithoutWrapping(ScalarEvolution &SE,
1584 const APInt &ConstantStart,
1585 const SCEV *Step) {
1586 const unsigned BitWidth = ConstantStart.getBitWidth();
1587 const uint32_t TZ = SE.GetMinTrailingZeros(Step);
1588 if (TZ)
1589 return TZ < BitWidth ? ConstantStart.trunc(TZ).zext(BitWidth)
1590 : ConstantStart;
1591 return APInt(BitWidth, 0);
1592}
1593
1594const SCEV *
1595ScalarEvolution::getZeroExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) {
1596 assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(Op->getType()
) < getTypeSizeInBits(Ty) && "This is not an extending conversion!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1597, __extension__
__PRETTY_FUNCTION__))
1597 "This is not an extending conversion!")(static_cast <bool> (getTypeSizeInBits(Op->getType()
) < getTypeSizeInBits(Ty) && "This is not an extending conversion!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1597, __extension__
__PRETTY_FUNCTION__));
1598 assert(isSCEVable(Ty) &&(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1599, __extension__
__PRETTY_FUNCTION__))
1599 "This is not a conversion to a SCEVable type!")(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1599, __extension__
__PRETTY_FUNCTION__));
1600 assert(!Op->getType()->isPointerTy() && "Can't extend pointer!")(static_cast <bool> (!Op->getType()->isPointerTy(
) && "Can't extend pointer!") ? void (0) : __assert_fail
("!Op->getType()->isPointerTy() && \"Can't extend pointer!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1600, __extension__
__PRETTY_FUNCTION__));
1601 Ty = getEffectiveSCEVType(Ty);
1602
1603 // Fold if the operand is constant.
1604 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1605 return getConstant(
1606 cast<ConstantInt>(ConstantExpr::getZExt(SC->getValue(), Ty)));
1607
1608 // zext(zext(x)) --> zext(x)
1609 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1610 return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1);
1611
1612 // Before doing any expensive analysis, check to see if we've already
1613 // computed a SCEV for this Op and Ty.
1614 FoldingSetNodeID ID;
1615 ID.AddInteger(scZeroExtend);
1616 ID.AddPointer(Op);
1617 ID.AddPointer(Ty);
1618 void *IP = nullptr;
1619 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1620 if (Depth > MaxCastDepth) {
1621 SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
1622 Op, Ty);
1623 UniqueSCEVs.InsertNode(S, IP);
1624 registerUser(S, Op);
1625 return S;
1626 }
1627
1628 // zext(trunc(x)) --> zext(x) or x or trunc(x)
1629 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1630 // It's possible the bits taken off by the truncate were all zero bits. If
1631 // so, we should be able to simplify this further.
1632 const SCEV *X = ST->getOperand();
1633 ConstantRange CR = getUnsignedRange(X);
1634 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1635 unsigned NewBits = getTypeSizeInBits(Ty);
1636 if (CR.truncate(TruncBits).zeroExtend(NewBits).contains(
1637 CR.zextOrTrunc(NewBits)))
1638 return getTruncateOrZeroExtend(X, Ty, Depth);
1639 }
1640
1641 // If the input value is a chrec scev, and we can prove that the value
1642 // did not overflow the old, smaller, value, we can zero extend all of the
1643 // operands (often constants). This allows analysis of something like
1644 // this: for (unsigned char X = 0; X < 100; ++X) { int Y = X; }
1645 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
1646 if (AR->isAffine()) {
1647 const SCEV *Start = AR->getStart();
1648 const SCEV *Step = AR->getStepRecurrence(*this);
1649 unsigned BitWidth = getTypeSizeInBits(AR->getType());
1650 const Loop *L = AR->getLoop();
1651
1652 if (!AR->hasNoUnsignedWrap()) {
1653 auto NewFlags = proveNoWrapViaConstantRanges(AR);
1654 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), NewFlags);
1655 }
1656
1657 // If we have special knowledge that this addrec won't overflow,
1658 // we don't need to do any further analysis.
1659 if (AR->hasNoUnsignedWrap())
1660 return getAddRecExpr(
1661 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1),
1662 getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
1663
1664 // Check whether the backedge-taken count is SCEVCouldNotCompute.
1665 // Note that this serves two purposes: It filters out loops that are
1666 // simply not analyzable, and it covers the case where this code is
1667 // being called from within backedge-taken count analysis, such that
1668 // attempting to ask for the backedge-taken count would likely result
1669 // in infinite recursion. In the later case, the analysis code will
1670 // cope with a conservative value, and it will take care to purge
1671 // that value once it has finished.
1672 const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(L);
1673 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
1674 // Manually compute the final value for AR, checking for overflow.
1675
1676 // Check whether the backedge-taken count can be losslessly casted to
1677 // the addrec's type. The count is always unsigned.
1678 const SCEV *CastedMaxBECount =
1679 getTruncateOrZeroExtend(MaxBECount, Start->getType(), Depth);
1680 const SCEV *RecastedMaxBECount = getTruncateOrZeroExtend(
1681 CastedMaxBECount, MaxBECount->getType(), Depth);
1682 if (MaxBECount == RecastedMaxBECount) {
1683 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
1684 // Check whether Start+Step*MaxBECount has no unsigned overflow.
1685 const SCEV *ZMul = getMulExpr(CastedMaxBECount, Step,
1686 SCEV::FlagAnyWrap, Depth + 1);
1687 const SCEV *ZAdd = getZeroExtendExpr(getAddExpr(Start, ZMul,
1688 SCEV::FlagAnyWrap,
1689 Depth + 1),
1690 WideTy, Depth + 1);
1691 const SCEV *WideStart = getZeroExtendExpr(Start, WideTy, Depth + 1);
1692 const SCEV *WideMaxBECount =
1693 getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1);
1694 const SCEV *OperandExtendedAdd =
1695 getAddExpr(WideStart,
1696 getMulExpr(WideMaxBECount,
1697 getZeroExtendExpr(Step, WideTy, Depth + 1),
1698 SCEV::FlagAnyWrap, Depth + 1),
1699 SCEV::FlagAnyWrap, Depth + 1);
1700 if (ZAdd == OperandExtendedAdd) {
1701 // Cache knowledge of AR NUW, which is propagated to this AddRec.
1702 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNUW);
1703 // Return the expression with the addrec on the outside.
1704 return getAddRecExpr(
1705 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1706 Depth + 1),
1707 getZeroExtendExpr(Step, Ty, Depth + 1), L,
1708 AR->getNoWrapFlags());
1709 }
1710 // Similar to above, only this time treat the step value as signed.
1711 // This covers loops that count down.
1712 OperandExtendedAdd =
1713 getAddExpr(WideStart,
1714 getMulExpr(WideMaxBECount,
1715 getSignExtendExpr(Step, WideTy, Depth + 1),
1716 SCEV::FlagAnyWrap, Depth + 1),
1717 SCEV::FlagAnyWrap, Depth + 1);
1718 if (ZAdd == OperandExtendedAdd) {
1719 // Cache knowledge of AR NW, which is propagated to this AddRec.
1720 // Negative step causes unsigned wrap, but it still can't self-wrap.
1721 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNW);
1722 // Return the expression with the addrec on the outside.
1723 return getAddRecExpr(
1724 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1725 Depth + 1),
1726 getSignExtendExpr(Step, Ty, Depth + 1), L,
1727 AR->getNoWrapFlags());
1728 }
1729 }
1730 }
1731
1732 // Normally, in the cases we can prove no-overflow via a
1733 // backedge guarding condition, we can also compute a backedge
1734 // taken count for the loop. The exceptions are assumptions and
1735 // guards present in the loop -- SCEV is not great at exploiting
1736 // these to compute max backedge taken counts, but can still use
1737 // these to prove lack of overflow. Use this fact to avoid
1738 // doing extra work that may not pay off.
1739 if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards ||
1740 !AC.assumptions().empty()) {
1741
1742 auto NewFlags = proveNoUnsignedWrapViaInduction(AR);
1743 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), NewFlags);
1744 if (AR->hasNoUnsignedWrap()) {
1745 // Same as nuw case above - duplicated here to avoid a compile time
1746 // issue. It's not clear that the order of checks does matter, but
1747 // it's one of two issue possible causes for a change which was
1748 // reverted. Be conservative for the moment.
1749 return getAddRecExpr(
1750 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1751 Depth + 1),
1752 getZeroExtendExpr(Step, Ty, Depth + 1), L,
1753 AR->getNoWrapFlags());
1754 }
1755
1756 // For a negative step, we can extend the operands iff doing so only
1757 // traverses values in the range zext([0,UINT_MAX]).
1758 if (isKnownNegative(Step)) {
1759 const SCEV *N = getConstant(APInt::getMaxValue(BitWidth) -
1760 getSignedRangeMin(Step));
1761 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, AR, N) ||
1762 isKnownOnEveryIteration(ICmpInst::ICMP_UGT, AR, N)) {
1763 // Cache knowledge of AR NW, which is propagated to this
1764 // AddRec. Negative step causes unsigned wrap, but it
1765 // still can't self-wrap.
1766 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNW);
1767 // Return the expression with the addrec on the outside.
1768 return getAddRecExpr(
1769 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1770 Depth + 1),
1771 getSignExtendExpr(Step, Ty, Depth + 1), L,
1772 AR->getNoWrapFlags());
1773 }
1774 }
1775 }
1776
1777 // zext({C,+,Step}) --> (zext(D) + zext({C-D,+,Step}))<nuw><nsw>
1778 // if D + (C - D + Step * n) could be proven to not unsigned wrap
1779 // where D maximizes the number of trailing zeros of (C - D + Step * n)
1780 if (const auto *SC = dyn_cast<SCEVConstant>(Start)) {
1781 const APInt &C = SC->getAPInt();
1782 const APInt &D = extractConstantWithoutWrapping(*this, C, Step);
1783 if (D != 0) {
1784 const SCEV *SZExtD = getZeroExtendExpr(getConstant(D), Ty, Depth);
1785 const SCEV *SResidual =
1786 getAddRecExpr(getConstant(C - D), Step, L, AR->getNoWrapFlags());
1787 const SCEV *SZExtR = getZeroExtendExpr(SResidual, Ty, Depth + 1);
1788 return getAddExpr(SZExtD, SZExtR,
1789 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
1790 Depth + 1);
1791 }
1792 }
1793
1794 if (proveNoWrapByVaryingStart<SCEVZeroExtendExpr>(Start, Step, L)) {
1795 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNUW);
1796 return getAddRecExpr(
1797 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1),
1798 getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
1799 }
1800 }
1801
1802 // zext(A % B) --> zext(A) % zext(B)
1803 {
1804 const SCEV *LHS;
1805 const SCEV *RHS;
1806 if (matchURem(Op, LHS, RHS))
1807 return getURemExpr(getZeroExtendExpr(LHS, Ty, Depth + 1),
1808 getZeroExtendExpr(RHS, Ty, Depth + 1));
1809 }
1810
1811 // zext(A / B) --> zext(A) / zext(B).
1812 if (auto *Div = dyn_cast<SCEVUDivExpr>(Op))
1813 return getUDivExpr(getZeroExtendExpr(Div->getLHS(), Ty, Depth + 1),
1814 getZeroExtendExpr(Div->getRHS(), Ty, Depth + 1));
1815
1816 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1817 // zext((A + B + ...)<nuw>) --> (zext(A) + zext(B) + ...)<nuw>
1818 if (SA->hasNoUnsignedWrap()) {
1819 // If the addition does not unsign overflow then we can, by definition,
1820 // commute the zero extension with the addition operation.
1821 SmallVector<const SCEV *, 4> Ops;
1822 for (const auto *Op : SA->operands())
1823 Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1));
1824 return getAddExpr(Ops, SCEV::FlagNUW, Depth + 1);
1825 }
1826
1827 // zext(C + x + y + ...) --> (zext(D) + zext((C - D) + x + y + ...))
1828 // if D + (C - D + x + y + ...) could be proven to not unsigned wrap
1829 // where D maximizes the number of trailing zeros of (C - D + x + y + ...)
1830 //
1831 // Often address arithmetics contain expressions like
1832 // (zext (add (shl X, C1), C2)), for instance, (zext (5 + (4 * X))).
1833 // This transformation is useful while proving that such expressions are
1834 // equal or differ by a small constant amount, see LoadStoreVectorizer pass.
1835 if (const auto *SC = dyn_cast<SCEVConstant>(SA->getOperand(0))) {
1836 const APInt &D = extractConstantWithoutWrapping(*this, SC, SA);
1837 if (D != 0) {
1838 const SCEV *SZExtD = getZeroExtendExpr(getConstant(D), Ty, Depth);
1839 const SCEV *SResidual =
1840 getAddExpr(getConstant(-D), SA, SCEV::FlagAnyWrap, Depth);
1841 const SCEV *SZExtR = getZeroExtendExpr(SResidual, Ty, Depth + 1);
1842 return getAddExpr(SZExtD, SZExtR,
1843 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
1844 Depth + 1);
1845 }
1846 }
1847 }
1848
1849 if (auto *SM = dyn_cast<SCEVMulExpr>(Op)) {
1850 // zext((A * B * ...)<nuw>) --> (zext(A) * zext(B) * ...)<nuw>
1851 if (SM->hasNoUnsignedWrap()) {
1852 // If the multiply does not unsign overflow then we can, by definition,
1853 // commute the zero extension with the multiply operation.
1854 SmallVector<const SCEV *, 4> Ops;
1855 for (const auto *Op : SM->operands())
1856 Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1));
1857 return getMulExpr(Ops, SCEV::FlagNUW, Depth + 1);
1858 }
1859
1860 // zext(2^K * (trunc X to iN)) to iM ->
1861 // 2^K * (zext(trunc X to i{N-K}) to iM)<nuw>
1862 //
1863 // Proof:
1864 //
1865 // zext(2^K * (trunc X to iN)) to iM
1866 // = zext((trunc X to iN) << K) to iM
1867 // = zext((trunc X to i{N-K}) << K)<nuw> to iM
1868 // (because shl removes the top K bits)
1869 // = zext((2^K * (trunc X to i{N-K}))<nuw>) to iM
1870 // = (2^K * (zext(trunc X to i{N-K}) to iM))<nuw>.
1871 //
1872 if (SM->getNumOperands() == 2)
1873 if (auto *MulLHS = dyn_cast<SCEVConstant>(SM->getOperand(0)))
1874 if (MulLHS->getAPInt().isPowerOf2())
1875 if (auto *TruncRHS = dyn_cast<SCEVTruncateExpr>(SM->getOperand(1))) {
1876 int NewTruncBits = getTypeSizeInBits(TruncRHS->getType()) -
1877 MulLHS->getAPInt().logBase2();
1878 Type *NewTruncTy = IntegerType::get(getContext(), NewTruncBits);
1879 return getMulExpr(
1880 getZeroExtendExpr(MulLHS, Ty),
1881 getZeroExtendExpr(
1882 getTruncateExpr(TruncRHS->getOperand(), NewTruncTy), Ty),
1883 SCEV::FlagNUW, Depth + 1);
1884 }
1885 }
1886
1887 // The cast wasn't folded; create an explicit cast node.
1888 // Recompute the insert position, as it may have been invalidated.
1889 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1890 SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
1891 Op, Ty);
1892 UniqueSCEVs.InsertNode(S, IP);
1893 registerUser(S, Op);
1894 return S;
1895}
1896
1897const SCEV *
1898ScalarEvolution::getSignExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) {
1899 assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(Op->getType()
) < getTypeSizeInBits(Ty) && "This is not an extending conversion!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1900, __extension__
__PRETTY_FUNCTION__))
1900 "This is not an extending conversion!")(static_cast <bool> (getTypeSizeInBits(Op->getType()
) < getTypeSizeInBits(Ty) && "This is not an extending conversion!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1900, __extension__
__PRETTY_FUNCTION__));
1901 assert(isSCEVable(Ty) &&(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1902, __extension__
__PRETTY_FUNCTION__))
1902 "This is not a conversion to a SCEVable type!")(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1902, __extension__
__PRETTY_FUNCTION__));
1903 assert(!Op->getType()->isPointerTy() && "Can't extend pointer!")(static_cast <bool> (!Op->getType()->isPointerTy(
) && "Can't extend pointer!") ? void (0) : __assert_fail
("!Op->getType()->isPointerTy() && \"Can't extend pointer!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 1903, __extension__
__PRETTY_FUNCTION__));
1904 Ty = getEffectiveSCEVType(Ty);
1905
1906 // Fold if the operand is constant.
1907 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1908 return getConstant(
1909 cast<ConstantInt>(ConstantExpr::getSExt(SC->getValue(), Ty)));
1910
1911 // sext(sext(x)) --> sext(x)
1912 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1913 return getSignExtendExpr(SS->getOperand(), Ty, Depth + 1);
1914
1915 // sext(zext(x)) --> zext(x)
1916 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1917 return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1);
1918
1919 // Before doing any expensive analysis, check to see if we've already
1920 // computed a SCEV for this Op and Ty.
1921 FoldingSetNodeID ID;
1922 ID.AddInteger(scSignExtend);
1923 ID.AddPointer(Op);
1924 ID.AddPointer(Ty);
1925 void *IP = nullptr;
1926 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1927 // Limit recursion depth.
1928 if (Depth > MaxCastDepth) {
1929 SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
1930 Op, Ty);
1931 UniqueSCEVs.InsertNode(S, IP);
1932 registerUser(S, Op);
1933 return S;
1934 }
1935
1936 // sext(trunc(x)) --> sext(x) or x or trunc(x)
1937 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1938 // It's possible the bits taken off by the truncate were all sign bits. If
1939 // so, we should be able to simplify this further.
1940 const SCEV *X = ST->getOperand();
1941 ConstantRange CR = getSignedRange(X);
1942 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1943 unsigned NewBits = getTypeSizeInBits(Ty);
1944 if (CR.truncate(TruncBits).signExtend(NewBits).contains(
1945 CR.sextOrTrunc(NewBits)))
1946 return getTruncateOrSignExtend(X, Ty, Depth);
1947 }
1948
1949 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1950 // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw>
1951 if (SA->hasNoSignedWrap()) {
1952 // If the addition does not sign overflow then we can, by definition,
1953 // commute the sign extension with the addition operation.
1954 SmallVector<const SCEV *, 4> Ops;
1955 for (const auto *Op : SA->operands())
1956 Ops.push_back(getSignExtendExpr(Op, Ty, Depth + 1));
1957 return getAddExpr(Ops, SCEV::FlagNSW, Depth + 1);
1958 }
1959
1960 // sext(C + x + y + ...) --> (sext(D) + sext((C - D) + x + y + ...))
1961 // if D + (C - D + x + y + ...) could be proven to not signed wrap
1962 // where D maximizes the number of trailing zeros of (C - D + x + y + ...)
1963 //
1964 // For instance, this will bring two seemingly different expressions:
1965 // 1 + sext(5 + 20 * %x + 24 * %y) and
1966 // sext(6 + 20 * %x + 24 * %y)
1967 // to the same form:
1968 // 2 + sext(4 + 20 * %x + 24 * %y)
1969 if (const auto *SC = dyn_cast<SCEVConstant>(SA->getOperand(0))) {
1970 const APInt &D = extractConstantWithoutWrapping(*this, SC, SA);
1971 if (D != 0) {
1972 const SCEV *SSExtD = getSignExtendExpr(getConstant(D), Ty, Depth);
1973 const SCEV *SResidual =
1974 getAddExpr(getConstant(-D), SA, SCEV::FlagAnyWrap, Depth);
1975 const SCEV *SSExtR = getSignExtendExpr(SResidual, Ty, Depth + 1);
1976 return getAddExpr(SSExtD, SSExtR,
1977 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
1978 Depth + 1);
1979 }
1980 }
1981 }
1982 // If the input value is a chrec scev, and we can prove that the value
1983 // did not overflow the old, smaller, value, we can sign extend all of the
1984 // operands (often constants). This allows analysis of something like
1985 // this: for (signed char X = 0; X < 100; ++X) { int Y = X; }
1986 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
1987 if (AR->isAffine()) {
1988 const SCEV *Start = AR->getStart();
1989 const SCEV *Step = AR->getStepRecurrence(*this);
1990 unsigned BitWidth = getTypeSizeInBits(AR->getType());
1991 const Loop *L = AR->getLoop();
1992
1993 if (!AR->hasNoSignedWrap()) {
1994 auto NewFlags = proveNoWrapViaConstantRanges(AR);
1995 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), NewFlags);
1996 }
1997
1998 // If we have special knowledge that this addrec won't overflow,
1999 // we don't need to do any further analysis.
2000 if (AR->hasNoSignedWrap())
2001 return getAddRecExpr(
2002 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
2003 getSignExtendExpr(Step, Ty, Depth + 1), L, SCEV::FlagNSW);
2004
2005 // Check whether the backedge-taken count is SCEVCouldNotCompute.
2006 // Note that this serves two purposes: It filters out loops that are
2007 // simply not analyzable, and it covers the case where this code is
2008 // being called from within backedge-taken count analysis, such that
2009 // attempting to ask for the backedge-taken count would likely result
2010 // in infinite recursion. In the later case, the analysis code will
2011 // cope with a conservative value, and it will take care to purge
2012 // that value once it has finished.
2013 const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(L);
2014 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
2015 // Manually compute the final value for AR, checking for
2016 // overflow.
2017
2018 // Check whether the backedge-taken count can be losslessly casted to
2019 // the addrec's type. The count is always unsigned.
2020 const SCEV *CastedMaxBECount =
2021 getTruncateOrZeroExtend(MaxBECount, Start->getType(), Depth);
2022 const SCEV *RecastedMaxBECount = getTruncateOrZeroExtend(
2023 CastedMaxBECount, MaxBECount->getType(), Depth);
2024 if (MaxBECount == RecastedMaxBECount) {
2025 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
2026 // Check whether Start+Step*MaxBECount has no signed overflow.
2027 const SCEV *SMul = getMulExpr(CastedMaxBECount, Step,
2028 SCEV::FlagAnyWrap, Depth + 1);
2029 const SCEV *SAdd = getSignExtendExpr(getAddExpr(Start, SMul,
2030 SCEV::FlagAnyWrap,
2031 Depth + 1),
2032 WideTy, Depth + 1);
2033 const SCEV *WideStart = getSignExtendExpr(Start, WideTy, Depth + 1);
2034 const SCEV *WideMaxBECount =
2035 getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1);
2036 const SCEV *OperandExtendedAdd =
2037 getAddExpr(WideStart,
2038 getMulExpr(WideMaxBECount,
2039 getSignExtendExpr(Step, WideTy, Depth + 1),
2040 SCEV::FlagAnyWrap, Depth + 1),
2041 SCEV::FlagAnyWrap, Depth + 1);
2042 if (SAdd == OperandExtendedAdd) {
2043 // Cache knowledge of AR NSW, which is propagated to this AddRec.
2044 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNSW);
2045 // Return the expression with the addrec on the outside.
2046 return getAddRecExpr(
2047 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this,
2048 Depth + 1),
2049 getSignExtendExpr(Step, Ty, Depth + 1), L,
2050 AR->getNoWrapFlags());
2051 }
2052 // Similar to above, only this time treat the step value as unsigned.
2053 // This covers loops that count up with an unsigned step.
2054 OperandExtendedAdd =
2055 getAddExpr(WideStart,
2056 getMulExpr(WideMaxBECount,
2057 getZeroExtendExpr(Step, WideTy, Depth + 1),
2058 SCEV::FlagAnyWrap, Depth + 1),
2059 SCEV::FlagAnyWrap, Depth + 1);
2060 if (SAdd == OperandExtendedAdd) {
2061 // If AR wraps around then
2062 //
2063 // abs(Step) * MaxBECount > unsigned-max(AR->getType())
2064 // => SAdd != OperandExtendedAdd
2065 //
2066 // Thus (AR is not NW => SAdd != OperandExtendedAdd) <=>
2067 // (SAdd == OperandExtendedAdd => AR is NW)
2068
2069 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNW);
2070
2071 // Return the expression with the addrec on the outside.
2072 return getAddRecExpr(
2073 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this,
2074 Depth + 1),
2075 getZeroExtendExpr(Step, Ty, Depth + 1), L,
2076 AR->getNoWrapFlags());
2077 }
2078 }
2079 }
2080
2081 auto NewFlags = proveNoSignedWrapViaInduction(AR);
2082 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), NewFlags);
2083 if (AR->hasNoSignedWrap()) {
2084 // Same as nsw case above - duplicated here to avoid a compile time
2085 // issue. It's not clear that the order of checks does matter, but
2086 // it's one of two issue possible causes for a change which was
2087 // reverted. Be conservative for the moment.
2088 return getAddRecExpr(
2089 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
2090 getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
2091 }
2092
2093 // sext({C,+,Step}) --> (sext(D) + sext({C-D,+,Step}))<nuw><nsw>
2094 // if D + (C - D + Step * n) could be proven to not signed wrap
2095 // where D maximizes the number of trailing zeros of (C - D + Step * n)
2096 if (const auto *SC = dyn_cast<SCEVConstant>(Start)) {
2097 const APInt &C = SC->getAPInt();
2098 const APInt &D = extractConstantWithoutWrapping(*this, C, Step);
2099 if (D != 0) {
2100 const SCEV *SSExtD = getSignExtendExpr(getConstant(D), Ty, Depth);
2101 const SCEV *SResidual =
2102 getAddRecExpr(getConstant(C - D), Step, L, AR->getNoWrapFlags());
2103 const SCEV *SSExtR = getSignExtendExpr(SResidual, Ty, Depth + 1);
2104 return getAddExpr(SSExtD, SSExtR,
2105 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
2106 Depth + 1);
2107 }
2108 }
2109
2110 if (proveNoWrapByVaryingStart<SCEVSignExtendExpr>(Start, Step, L)) {
2111 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNSW);
2112 return getAddRecExpr(
2113 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
2114 getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
2115 }
2116 }
2117
2118 // If the input value is provably positive and we could not simplify
2119 // away the sext build a zext instead.
2120 if (isKnownNonNegative(Op))
2121 return getZeroExtendExpr(Op, Ty, Depth + 1);
2122
2123 // The cast wasn't folded; create an explicit cast node.
2124 // Recompute the insert position, as it may have been invalidated.
2125 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
2126 SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
2127 Op, Ty);
2128 UniqueSCEVs.InsertNode(S, IP);
2129 registerUser(S, { Op });
2130 return S;
2131}
2132
2133const SCEV *ScalarEvolution::getCastExpr(SCEVTypes Kind, const SCEV *Op,
2134 Type *Ty) {
2135 switch (Kind) {
2136 case scTruncate:
2137 return getTruncateExpr(Op, Ty);
2138 case scZeroExtend:
2139 return getZeroExtendExpr(Op, Ty);
2140 case scSignExtend:
2141 return getSignExtendExpr(Op, Ty);
2142 case scPtrToInt:
2143 return getPtrToIntExpr(Op, Ty);
2144 default:
2145 llvm_unreachable("Not a SCEV cast expression!")::llvm::llvm_unreachable_internal("Not a SCEV cast expression!"
, "llvm/lib/Analysis/ScalarEvolution.cpp", 2145);
2146 }
2147}
2148
2149/// getAnyExtendExpr - Return a SCEV for the given operand extended with
2150/// unspecified bits out to the given type.
2151const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op,
2152 Type *Ty) {
2153 assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(Op->getType()
) < getTypeSizeInBits(Ty) && "This is not an extending conversion!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 2154, __extension__
__PRETTY_FUNCTION__))
2154 "This is not an extending conversion!")(static_cast <bool> (getTypeSizeInBits(Op->getType()
) < getTypeSizeInBits(Ty) && "This is not an extending conversion!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 2154, __extension__
__PRETTY_FUNCTION__));
2155 assert(isSCEVable(Ty) &&(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 2156, __extension__
__PRETTY_FUNCTION__))
2156 "This is not a conversion to a SCEVable type!")(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 2156, __extension__
__PRETTY_FUNCTION__));
2157 Ty = getEffectiveSCEVType(Ty);
2158
2159 // Sign-extend negative constants.
2160 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
2161 if (SC->getAPInt().isNegative())
2162 return getSignExtendExpr(Op, Ty);
2163
2164 // Peel off a truncate cast.
2165 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Op)) {
2166 const SCEV *NewOp = T->getOperand();
2167 if (getTypeSizeInBits(NewOp->getType()) < getTypeSizeInBits(Ty))
2168 return getAnyExtendExpr(NewOp, Ty);
2169 return getTruncateOrNoop(NewOp, Ty);
2170 }
2171
2172 // Next try a zext cast. If the cast is folded, use it.
2173 const SCEV *ZExt = getZeroExtendExpr(Op, Ty);
2174 if (!isa<SCEVZeroExtendExpr>(ZExt))
2175 return ZExt;
2176
2177 // Next try a sext cast. If the cast is folded, use it.
2178 const SCEV *SExt = getSignExtendExpr(Op, Ty);
2179 if (!isa<SCEVSignExtendExpr>(SExt))
2180 return SExt;
2181
2182 // Force the cast to be folded into the operands of an addrec.
2183 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) {
2184 SmallVector<const SCEV *, 4> Ops;
2185 for (const SCEV *Op : AR->operands())
2186 Ops.push_back(getAnyExtendExpr(Op, Ty));
2187 return getAddRecExpr(Ops, AR->getLoop(), SCEV::FlagNW);
2188 }
2189
2190 // If the expression is obviously signed, use the sext cast value.
2191 if (isa<SCEVSMaxExpr>(Op))
2192 return SExt;
2193
2194 // Absent any other information, use the zext cast value.
2195 return ZExt;
2196}
2197
2198/// Process the given Ops list, which is a list of operands to be added under
2199/// the given scale, update the given map. This is a helper function for
2200/// getAddRecExpr. As an example of what it does, given a sequence of operands
2201/// that would form an add expression like this:
2202///
2203/// m + n + 13 + (A * (o + p + (B * (q + m + 29)))) + r + (-1 * r)
2204///
2205/// where A and B are constants, update the map with these values:
2206///
2207/// (m, 1+A*B), (n, 1), (o, A), (p, A), (q, A*B), (r, 0)
2208///
2209/// and add 13 + A*B*29 to AccumulatedConstant.
2210/// This will allow getAddRecExpr to produce this:
2211///
2212/// 13+A*B*29 + n + (m * (1+A*B)) + ((o + p) * A) + (q * A*B)
2213///
2214/// This form often exposes folding opportunities that are hidden in
2215/// the original operand list.
2216///
2217/// Return true iff it appears that any interesting folding opportunities
2218/// may be exposed. This helps getAddRecExpr short-circuit extra work in
2219/// the common case where no interesting opportunities are present, and
2220/// is also used as a check to avoid infinite recursion.
2221static bool
2222CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M,
2223 SmallVectorImpl<const SCEV *> &NewOps,
2224 APInt &AccumulatedConstant,
2225 const SCEV *const *Ops, size_t NumOperands,
2226 const APInt &Scale,
2227 ScalarEvolution &SE) {
2228 bool Interesting = false;
2229
2230 // Iterate over the add operands. They are sorted, with constants first.
2231 unsigned i = 0;
2232 while (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
2233 ++i;
2234 // Pull a buried constant out to the outside.
2235 if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero())
2236 Interesting = true;
2237 AccumulatedConstant += Scale * C->getAPInt();
2238 }
2239
2240 // Next comes everything else. We're especially interested in multiplies
2241 // here, but they're in the middle, so just visit the rest with one loop.
2242 for (; i != NumOperands; ++i) {
2243 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[i]);
2244 if (Mul && isa<SCEVConstant>(Mul->getOperand(0))) {
2245 APInt NewScale =
2246 Scale * cast<SCEVConstant>(Mul->getOperand(0))->getAPInt();
2247 if (Mul->getNumOperands() == 2 && isa<SCEVAddExpr>(Mul->getOperand(1))) {
2248 // A multiplication of a constant with another add; recurse.
2249 const SCEVAddExpr *Add = cast<SCEVAddExpr>(Mul->getOperand(1));
2250 Interesting |=
2251 CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
2252 Add->op_begin(), Add->getNumOperands(),
2253 NewScale, SE);
2254 } else {
2255 // A multiplication of a constant with some other value. Update
2256 // the map.
2257 SmallVector<const SCEV *, 4> MulOps(drop_begin(Mul->operands()));
2258 const SCEV *Key = SE.getMulExpr(MulOps);
2259 auto Pair = M.insert({Key, NewScale});
2260 if (Pair.second) {
2261 NewOps.push_back(Pair.first->first);
2262 } else {
2263 Pair.first->second += NewScale;
2264 // The map already had an entry for this value, which may indicate
2265 // a folding opportunity.
2266 Interesting = true;
2267 }
2268 }
2269 } else {
2270 // An ordinary operand. Update the map.
2271 std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair =
2272 M.insert({Ops[i], Scale});
2273 if (Pair.second) {
2274 NewOps.push_back(Pair.first->first);
2275 } else {
2276 Pair.first->second += Scale;
2277 // The map already had an entry for this value, which may indicate
2278 // a folding opportunity.
2279 Interesting = true;
2280 }
2281 }
2282 }
2283
2284 return Interesting;
2285}
2286
2287bool ScalarEvolution::willNotOverflow(Instruction::BinaryOps BinOp, bool Signed,
2288 const SCEV *LHS, const SCEV *RHS) {
2289 const SCEV *(ScalarEvolution::*Operation)(const SCEV *, const SCEV *,
2290 SCEV::NoWrapFlags, unsigned);
2291 switch (BinOp) {
2292 default:
2293 llvm_unreachable("Unsupported binary op")::llvm::llvm_unreachable_internal("Unsupported binary op", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 2293);
2294 case Instruction::Add:
2295 Operation = &ScalarEvolution::getAddExpr;
2296 break;
2297 case Instruction::Sub:
2298 Operation = &ScalarEvolution::getMinusSCEV;
2299 break;
2300 case Instruction::Mul:
2301 Operation = &ScalarEvolution::getMulExpr;
2302 break;
2303 }
2304
2305 const SCEV *(ScalarEvolution::*Extension)(const SCEV *, Type *, unsigned) =
2306 Signed ? &ScalarEvolution::getSignExtendExpr
2307 : &ScalarEvolution::getZeroExtendExpr;
2308
2309 // Check ext(LHS op RHS) == ext(LHS) op ext(RHS)
2310 auto *NarrowTy = cast<IntegerType>(LHS->getType());
2311 auto *WideTy =
2312 IntegerType::get(NarrowTy->getContext(), NarrowTy->getBitWidth() * 2);
2313
2314 const SCEV *A = (this->*Extension)(
2315 (this->*Operation)(LHS, RHS, SCEV::FlagAnyWrap, 0), WideTy, 0);
2316 const SCEV *B = (this->*Operation)((this->*Extension)(LHS, WideTy, 0),
2317 (this->*Extension)(RHS, WideTy, 0),
2318 SCEV::FlagAnyWrap, 0);
2319 return A == B;
2320}
2321
2322std::pair<SCEV::NoWrapFlags, bool /*Deduced*/>
2323ScalarEvolution::getStrengthenedNoWrapFlagsFromBinOp(
2324 const OverflowingBinaryOperator *OBO) {
2325 SCEV::NoWrapFlags Flags = SCEV::NoWrapFlags::FlagAnyWrap;
2326
2327 if (OBO->hasNoUnsignedWrap())
2328 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
2329 if (OBO->hasNoSignedWrap())
2330 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
2331
2332 bool Deduced = false;
2333
2334 if (OBO->hasNoUnsignedWrap() && OBO->hasNoSignedWrap())
2335 return {Flags, Deduced};
2336
2337 if (OBO->getOpcode() != Instruction::Add &&
2338 OBO->getOpcode() != Instruction::Sub &&
2339 OBO->getOpcode() != Instruction::Mul)
2340 return {Flags, Deduced};
2341
2342 const SCEV *LHS = getSCEV(OBO->getOperand(0));
2343 const SCEV *RHS = getSCEV(OBO->getOperand(1));
2344
2345 if (!OBO->hasNoUnsignedWrap() &&
2346 willNotOverflow((Instruction::BinaryOps)OBO->getOpcode(),
2347 /* Signed */ false, LHS, RHS)) {
2348 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
2349 Deduced = true;
2350 }
2351
2352 if (!OBO->hasNoSignedWrap() &&
2353 willNotOverflow((Instruction::BinaryOps)OBO->getOpcode(),
2354 /* Signed */ true, LHS, RHS)) {
2355 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
2356 Deduced = true;
2357 }
2358
2359 return {Flags, Deduced};
2360}
2361
2362// We're trying to construct a SCEV of type `Type' with `Ops' as operands and
2363// `OldFlags' as can't-wrap behavior. Infer a more aggressive set of
2364// can't-overflow flags for the operation if possible.
2365static SCEV::NoWrapFlags
2366StrengthenNoWrapFlags(ScalarEvolution *SE, SCEVTypes Type,
2367 const ArrayRef<const SCEV *> Ops,
2368 SCEV::NoWrapFlags Flags) {
2369 using namespace std::placeholders;
2370
2371 using OBO = OverflowingBinaryOperator;
2372
2373 bool CanAnalyze =
2374 Type == scAddExpr || Type == scAddRecExpr || Type == scMulExpr;
2375 (void)CanAnalyze;
2376 assert(CanAnalyze && "don't call from other places!")(static_cast <bool> (CanAnalyze && "don't call from other places!"
) ? void (0) : __assert_fail ("CanAnalyze && \"don't call from other places!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 2376, __extension__
__PRETTY_FUNCTION__));
2377
2378 int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW;
2379 SCEV::NoWrapFlags SignOrUnsignWrap =
2380 ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
2381
2382 // If FlagNSW is true and all the operands are non-negative, infer FlagNUW.
2383 auto IsKnownNonNegative = [&](const SCEV *S) {
2384 return SE->isKnownNonNegative(S);
2385 };
2386
2387 if (SignOrUnsignWrap == SCEV::FlagNSW && all_of(Ops, IsKnownNonNegative))
2388 Flags =
2389 ScalarEvolution::setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask);
2390
2391 SignOrUnsignWrap = ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
2392
2393 if (SignOrUnsignWrap != SignOrUnsignMask &&
2394 (Type == scAddExpr || Type == scMulExpr) && Ops.size() == 2 &&
2395 isa<SCEVConstant>(Ops[0])) {
2396
2397 auto Opcode = [&] {
2398 switch (Type) {
2399 case scAddExpr:
2400 return Instruction::Add;
2401 case scMulExpr:
2402 return Instruction::Mul;
2403 default:
2404 llvm_unreachable("Unexpected SCEV op.")::llvm::llvm_unreachable_internal("Unexpected SCEV op.", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 2404);
2405 }
2406 }();
2407
2408 const APInt &C = cast<SCEVConstant>(Ops[0])->getAPInt();
2409
2410 // (A <opcode> C) --> (A <opcode> C)<nsw> if the op doesn't sign overflow.
2411 if (!(SignOrUnsignWrap & SCEV::FlagNSW)) {
2412 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
2413 Opcode, C, OBO::NoSignedWrap);
2414 if (NSWRegion.contains(SE->getSignedRange(Ops[1])))
2415 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
2416 }
2417
2418 // (A <opcode> C) --> (A <opcode> C)<nuw> if the op doesn't unsign overflow.
2419 if (!(SignOrUnsignWrap & SCEV::FlagNUW)) {
2420 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
2421 Opcode, C, OBO::NoUnsignedWrap);
2422 if (NUWRegion.contains(SE->getUnsignedRange(Ops[1])))
2423 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
2424 }
2425 }
2426
2427 // <0,+,nonnegative><nw> is also nuw
2428 // TODO: Add corresponding nsw case
2429 if (Type == scAddRecExpr && ScalarEvolution::hasFlags(Flags, SCEV::FlagNW) &&
2430 !ScalarEvolution::hasFlags(Flags, SCEV::FlagNUW) && Ops.size() == 2 &&
2431 Ops[0]->isZero() && IsKnownNonNegative(Ops[1]))
2432 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
2433
2434 // both (udiv X, Y) * Y and Y * (udiv X, Y) are always NUW
2435 if (Type == scMulExpr && !ScalarEvolution::hasFlags(Flags, SCEV::FlagNUW) &&
2436 Ops.size() == 2) {
2437 if (auto *UDiv = dyn_cast<SCEVUDivExpr>(Ops[0]))
2438 if (UDiv->getOperand(1) == Ops[1])
2439 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
2440 if (auto *UDiv = dyn_cast<SCEVUDivExpr>(Ops[1]))
2441 if (UDiv->getOperand(1) == Ops[0])
2442 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
2443 }
2444
2445 return Flags;
2446}
2447
2448bool ScalarEvolution::isAvailableAtLoopEntry(const SCEV *S, const Loop *L) {
2449 return isLoopInvariant(S, L) && properlyDominates(S, L->getHeader());
2450}
2451
2452/// Get a canonical add expression, or something simpler if possible.
2453const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
2454 SCEV::NoWrapFlags OrigFlags,
2455 unsigned Depth) {
2456 assert(!(OrigFlags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) &&(static_cast <bool> (!(OrigFlags & ~(SCEV::FlagNUW |
SCEV::FlagNSW)) && "only nuw or nsw allowed") ? void
(0) : __assert_fail ("!(OrigFlags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && \"only nuw or nsw allowed\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 2457, __extension__
__PRETTY_FUNCTION__))
2457 "only nuw or nsw allowed")(static_cast <bool> (!(OrigFlags & ~(SCEV::FlagNUW |
SCEV::FlagNSW)) && "only nuw or nsw allowed") ? void
(0) : __assert_fail ("!(OrigFlags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && \"only nuw or nsw allowed\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 2457, __extension__
__PRETTY_FUNCTION__));
2458 assert(!Ops.empty() && "Cannot get empty add!")(static_cast <bool> (!Ops.empty() && "Cannot get empty add!"
) ? void (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty add!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 2458, __extension__
__PRETTY_FUNCTION__));
2459 if (Ops.size() == 1) return Ops[0];
2460#ifndef NDEBUG
2461 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2462 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2463 assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType
()) == ETy && "SCEVAddExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVAddExpr operand types don't match!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 2464, __extension__
__PRETTY_FUNCTION__))
2464 "SCEVAddExpr operand types don't match!")(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType
()) == ETy && "SCEVAddExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVAddExpr operand types don't match!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 2464, __extension__
__PRETTY_FUNCTION__));
2465 unsigned NumPtrs = count_if(
2466 Ops, [](const SCEV *Op) { return Op->getType()->isPointerTy(); });
2467 assert(NumPtrs <= 1 && "add has at most one pointer operand")(static_cast <bool> (NumPtrs <= 1 && "add has at most one pointer operand"
) ? void (0) : __assert_fail ("NumPtrs <= 1 && \"add has at most one pointer operand\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 2467, __extension__
__PRETTY_FUNCTION__));
2468#endif
2469
2470 // Sort by complexity, this groups all similar expression types together.
2471 GroupByComplexity(Ops, &LI, DT);
2472
2473 // If there are any constants, fold them together.
2474 unsigned Idx = 0;
2475 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2476 ++Idx;
2477 assert(Idx < Ops.size())(static_cast <bool> (Idx < Ops.size()) ? void (0) : __assert_fail
("Idx < Ops.size()", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 2477, __extension__ __PRETTY_FUNCTION__));
2478 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2479 // We found two constants, fold them together!
2480 Ops[0] = getConstant(LHSC->getAPInt() + RHSC->getAPInt());
2481 if (Ops.size() == 2) return Ops[0];
2482 Ops.erase(Ops.begin()+1); // Erase the folded element
2483 LHSC = cast<SCEVConstant>(Ops[0]);
2484 }
2485
2486 // If we are left with a constant zero being added, strip it off.
2487 if (LHSC->getValue()->isZero()) {
2488 Ops.erase(Ops.begin());
2489 --Idx;
2490 }
2491
2492 if (Ops.size() == 1) return Ops[0];
2493 }
2494
2495 // Delay expensive flag strengthening until necessary.
2496 auto ComputeFlags = [this, OrigFlags](const ArrayRef<const SCEV *> Ops) {
2497 return StrengthenNoWrapFlags(this, scAddExpr, Ops, OrigFlags);
2498 };
2499
2500 // Limit recursion calls depth.
2501 if (Depth > MaxArithDepth || hasHugeExpression(Ops))
2502 return getOrCreateAddExpr(Ops, ComputeFlags(Ops));
2503
2504 if (SCEV *S = findExistingSCEVInCache(scAddExpr, Ops)) {
2505 // Don't strengthen flags if we have no new information.
2506 SCEVAddExpr *Add = static_cast<SCEVAddExpr *>(S);
2507 if (Add->getNoWrapFlags(OrigFlags) != OrigFlags)
2508 Add->setNoWrapFlags(ComputeFlags(Ops));
2509 return S;
2510 }
2511
2512 // Okay, check to see if the same value occurs in the operand list more than
2513 // once. If so, merge them together into an multiply expression. Since we
2514 // sorted the list, these values are required to be adjacent.
2515 Type *Ty = Ops[0]->getType();
2516 bool FoundMatch = false;
2517 for (unsigned i = 0, e = Ops.size(); i != e-1; ++i)
2518 if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2
2519 // Scan ahead to count how many equal operands there are.
2520 unsigned Count = 2;
2521 while (i+Count != e && Ops[i+Count] == Ops[i])
2522 ++Count;
2523 // Merge the values into a multiply.
2524 const SCEV *Scale = getConstant(Ty, Count);
2525 const SCEV *Mul = getMulExpr(Scale, Ops[i], SCEV::FlagAnyWrap, Depth + 1);
2526 if (Ops.size() == Count)
2527 return Mul;
2528 Ops[i] = Mul;
2529 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+Count);
2530 --i; e -= Count - 1;
2531 FoundMatch = true;
2532 }
2533 if (FoundMatch)
2534 return getAddExpr(Ops, OrigFlags, Depth + 1);
2535
2536 // Check for truncates. If all the operands are truncated from the same
2537 // type, see if factoring out the truncate would permit the result to be
2538 // folded. eg., n*trunc(x) + m*trunc(y) --> trunc(trunc(m)*x + trunc(n)*y)
2539 // if the contents of the resulting outer trunc fold to something simple.
2540 auto FindTruncSrcType = [&]() -> Type * {
2541 // We're ultimately looking to fold an addrec of truncs and muls of only
2542 // constants and truncs, so if we find any other types of SCEV
2543 // as operands of the addrec then we bail and return nullptr here.
2544 // Otherwise, we return the type of the operand of a trunc that we find.
2545 if (auto *T = dyn_cast<SCEVTruncateExpr>(Ops[Idx]))
2546 return T->getOperand()->getType();
2547 if (const auto *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
2548 const auto *LastOp = Mul->getOperand(Mul->getNumOperands() - 1);
2549 if (const auto *T = dyn_cast<SCEVTruncateExpr>(LastOp))
2550 return T->getOperand()->getType();
2551 }
2552 return nullptr;
2553 };
2554 if (auto *SrcType = FindTruncSrcType()) {
2555 SmallVector<const SCEV *, 8> LargeOps;
2556 bool Ok = true;
2557 // Check all the operands to see if they can be represented in the
2558 // source type of the truncate.
2559 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
2560 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Ops[i])) {
2561 if (T->getOperand()->getType() != SrcType) {
2562 Ok = false;
2563 break;
2564 }
2565 LargeOps.push_back(T->getOperand());
2566 } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
2567 LargeOps.push_back(getAnyExtendExpr(C, SrcType));
2568 } else if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Ops[i])) {
2569 SmallVector<const SCEV *, 8> LargeMulOps;
2570 for (unsigned j = 0, f = M->getNumOperands(); j != f && Ok; ++j) {
2571 if (const SCEVTruncateExpr *T =
2572 dyn_cast<SCEVTruncateExpr>(M->getOperand(j))) {
2573 if (T->getOperand()->getType() != SrcType) {
2574 Ok = false;
2575 break;
2576 }
2577 LargeMulOps.push_back(T->getOperand());
2578 } else if (const auto *C = dyn_cast<SCEVConstant>(M->getOperand(j))) {
2579 LargeMulOps.push_back(getAnyExtendExpr(C, SrcType));
2580 } else {
2581 Ok = false;
2582 break;
2583 }
2584 }
2585 if (Ok)
2586 LargeOps.push_back(getMulExpr(LargeMulOps, SCEV::FlagAnyWrap, Depth + 1));
2587 } else {
2588 Ok = false;
2589 break;
2590 }
2591 }
2592 if (Ok) {
2593 // Evaluate the expression in the larger type.
2594 const SCEV *Fold = getAddExpr(LargeOps, SCEV::FlagAnyWrap, Depth + 1);
2595 // If it folds to something simple, use it. Otherwise, don't.
2596 if (isa<SCEVConstant>(Fold) || isa<SCEVUnknown>(Fold))
2597 return getTruncateExpr(Fold, Ty);
2598 }
2599 }
2600
2601 if (Ops.size() == 2) {
2602 // Check if we have an expression of the form ((X + C1) - C2), where C1 and
2603 // C2 can be folded in a way that allows retaining wrapping flags of (X +
2604 // C1).
2605 const SCEV *A = Ops[0];
2606 const SCEV *B = Ops[1];
2607 auto *AddExpr = dyn_cast<SCEVAddExpr>(B);
2608 auto *C = dyn_cast<SCEVConstant>(A);
2609 if (AddExpr && C && isa<SCEVConstant>(AddExpr->getOperand(0))) {
2610 auto C1 = cast<SCEVConstant>(AddExpr->getOperand(0))->getAPInt();
2611 auto C2 = C->getAPInt();
2612 SCEV::NoWrapFlags PreservedFlags = SCEV::FlagAnyWrap;
2613
2614 APInt ConstAdd = C1 + C2;
2615 auto AddFlags = AddExpr->getNoWrapFlags();
2616 // Adding a smaller constant is NUW if the original AddExpr was NUW.
2617 if (ScalarEvolution::hasFlags(AddFlags, SCEV::FlagNUW) &&
2618 ConstAdd.ule(C1)) {
2619 PreservedFlags =
2620 ScalarEvolution::setFlags(PreservedFlags, SCEV::FlagNUW);
2621 }
2622
2623 // Adding a constant with the same sign and small magnitude is NSW, if the
2624 // original AddExpr was NSW.
2625 if (ScalarEvolution::hasFlags(AddFlags, SCEV::FlagNSW) &&
2626 C1.isSignBitSet() == ConstAdd.isSignBitSet() &&
2627 ConstAdd.abs().ule(C1.abs())) {
2628 PreservedFlags =
2629 ScalarEvolution::setFlags(PreservedFlags, SCEV::FlagNSW);
2630 }
2631
2632 if (PreservedFlags != SCEV::FlagAnyWrap) {
2633 SmallVector<const SCEV *, 4> NewOps(AddExpr->operands());
2634 NewOps[0] = getConstant(ConstAdd);
2635 return getAddExpr(NewOps, PreservedFlags);
2636 }
2637 }
2638 }
2639
2640 // Canonicalize (-1 * urem X, Y) + X --> (Y * X/Y)
2641 if (Ops.size() == 2) {
2642 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[0]);
2643 if (Mul && Mul->getNumOperands() == 2 &&
2644 Mul->getOperand(0)->isAllOnesValue()) {
2645 const SCEV *X;
2646 const SCEV *Y;
2647 if (matchURem(Mul->getOperand(1), X, Y) && X == Ops[1]) {
2648 return getMulExpr(Y, getUDivExpr(X, Y));
2649 }
2650 }
2651 }
2652
2653 // Skip past any other cast SCEVs.
2654 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddExpr)
2655 ++Idx;
2656
2657 // If there are add operands they would be next.
2658 if (Idx < Ops.size()) {
2659 bool DeletedAdd = false;
2660 // If the original flags and all inlined SCEVAddExprs are NUW, use the
2661 // common NUW flag for expression after inlining. Other flags cannot be
2662 // preserved, because they may depend on the original order of operations.
2663 SCEV::NoWrapFlags CommonFlags = maskFlags(OrigFlags, SCEV::FlagNUW);
2664 while (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[Idx])) {
2665 if (Ops.size() > AddOpsInlineThreshold ||
2666 Add->getNumOperands() > AddOpsInlineThreshold)
2667 break;
2668 // If we have an add, expand the add operands onto the end of the operands
2669 // list.
2670 Ops.erase(Ops.begin()+Idx);
2671 Ops.append(Add->op_begin(), Add->op_end());
2672 DeletedAdd = true;
2673 CommonFlags = maskFlags(CommonFlags, Add->getNoWrapFlags());
2674 }
2675
2676 // If we deleted at least one add, we added operands to the end of the list,
2677 // and they are not necessarily sorted. Recurse to resort and resimplify
2678 // any operands we just acquired.
2679 if (DeletedAdd)
2680 return getAddExpr(Ops, CommonFlags, Depth + 1);
2681 }
2682
2683 // Skip over the add expression until we get to a multiply.
2684 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
2685 ++Idx;
2686
2687 // Check to see if there are any folding opportunities present with
2688 // operands multiplied by constant values.
2689 if (Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx])) {
2690 uint64_t BitWidth = getTypeSizeInBits(Ty);
2691 DenseMap<const SCEV *, APInt> M;
2692 SmallVector<const SCEV *, 8> NewOps;
2693 APInt AccumulatedConstant(BitWidth, 0);
2694 if (CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
2695 Ops.data(), Ops.size(),
2696 APInt(BitWidth, 1), *this)) {
2697 struct APIntCompare {
2698 bool operator()(const APInt &LHS, const APInt &RHS) const {
2699 return LHS.ult(RHS);
2700 }
2701 };
2702
2703 // Some interesting folding opportunity is present, so its worthwhile to
2704 // re-generate the operands list. Group the operands by constant scale,
2705 // to avoid multiplying by the same constant scale multiple times.
2706 std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare> MulOpLists;
2707 for (const SCEV *NewOp : NewOps)
2708 MulOpLists[M.find(NewOp)->second].push_back(NewOp);
2709 // Re-generate the operands list.
2710 Ops.clear();
2711 if (AccumulatedConstant != 0)
2712 Ops.push_back(getConstant(AccumulatedConstant));
2713 for (auto &MulOp : MulOpLists) {
2714 if (MulOp.first == 1) {
2715 Ops.push_back(getAddExpr(MulOp.second, SCEV::FlagAnyWrap, Depth + 1));
2716 } else if (MulOp.first != 0) {
2717 Ops.push_back(getMulExpr(
2718 getConstant(MulOp.first),
2719 getAddExpr(MulOp.second, SCEV::FlagAnyWrap, Depth + 1),
2720 SCEV::FlagAnyWrap, Depth + 1));
2721 }
2722 }
2723 if (Ops.empty())
2724 return getZero(Ty);
2725 if (Ops.size() == 1)
2726 return Ops[0];
2727 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2728 }
2729 }
2730
2731 // If we are adding something to a multiply expression, make sure the
2732 // something is not already an operand of the multiply. If so, merge it into
2733 // the multiply.
2734 for (; Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx]); ++Idx) {
2735 const SCEVMulExpr *Mul = cast<SCEVMulExpr>(Ops[Idx]);
2736 for (unsigned MulOp = 0, e = Mul->getNumOperands(); MulOp != e; ++MulOp) {
2737 const SCEV *MulOpSCEV = Mul->getOperand(MulOp);
2738 if (isa<SCEVConstant>(MulOpSCEV))
2739 continue;
2740 for (unsigned AddOp = 0, e = Ops.size(); AddOp != e; ++AddOp)
2741 if (MulOpSCEV == Ops[AddOp]) {
2742 // Fold W + X + (X * Y * Z) --> W + (X * ((Y*Z)+1))
2743 const SCEV *InnerMul = Mul->getOperand(MulOp == 0);
2744 if (Mul->getNumOperands() != 2) {
2745 // If the multiply has more than two operands, we must get the
2746 // Y*Z term.
2747 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2748 Mul->op_begin()+MulOp);
2749 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2750 InnerMul = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2751 }
2752 SmallVector<const SCEV *, 2> TwoOps = {getOne(Ty), InnerMul};
2753 const SCEV *AddOne = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2754 const SCEV *OuterMul = getMulExpr(AddOne, MulOpSCEV,
2755 SCEV::FlagAnyWrap, Depth + 1);
2756 if (Ops.size() == 2) return OuterMul;
2757 if (AddOp < Idx) {
2758 Ops.erase(Ops.begin()+AddOp);
2759 Ops.erase(Ops.begin()+Idx-1);
2760 } else {
2761 Ops.erase(Ops.begin()+Idx);
2762 Ops.erase(Ops.begin()+AddOp-1);
2763 }
2764 Ops.push_back(OuterMul);
2765 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2766 }
2767
2768 // Check this multiply against other multiplies being added together.
2769 for (unsigned OtherMulIdx = Idx+1;
2770 OtherMulIdx < Ops.size() && isa<SCEVMulExpr>(Ops[OtherMulIdx]);
2771 ++OtherMulIdx) {
2772 const SCEVMulExpr *OtherMul = cast<SCEVMulExpr>(Ops[OtherMulIdx]);
2773 // If MulOp occurs in OtherMul, we can fold the two multiplies
2774 // together.
2775 for (unsigned OMulOp = 0, e = OtherMul->getNumOperands();
2776 OMulOp != e; ++OMulOp)
2777 if (OtherMul->getOperand(OMulOp) == MulOpSCEV) {
2778 // Fold X + (A*B*C) + (A*D*E) --> X + (A*(B*C+D*E))
2779 const SCEV *InnerMul1 = Mul->getOperand(MulOp == 0);
2780 if (Mul->getNumOperands() != 2) {
2781 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2782 Mul->op_begin()+MulOp);
2783 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2784 InnerMul1 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2785 }
2786 const SCEV *InnerMul2 = OtherMul->getOperand(OMulOp == 0);
2787 if (OtherMul->getNumOperands() != 2) {
2788 SmallVector<const SCEV *, 4> MulOps(OtherMul->op_begin(),
2789 OtherMul->op_begin()+OMulOp);
2790 MulOps.append(OtherMul->op_begin()+OMulOp+1, OtherMul->op_end());
2791 InnerMul2 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2792 }
2793 SmallVector<const SCEV *, 2> TwoOps = {InnerMul1, InnerMul2};
2794 const SCEV *InnerMulSum =
2795 getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2796 const SCEV *OuterMul = getMulExpr(MulOpSCEV, InnerMulSum,
2797 SCEV::FlagAnyWrap, Depth + 1);
2798 if (Ops.size() == 2) return OuterMul;
2799 Ops.erase(Ops.begin()+Idx);
2800 Ops.erase(Ops.begin()+OtherMulIdx-1);
2801 Ops.push_back(OuterMul);
2802 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2803 }
2804 }
2805 }
2806 }
2807
2808 // If there are any add recurrences in the operands list, see if any other
2809 // added values are loop invariant. If so, we can fold them into the
2810 // recurrence.
2811 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
2812 ++Idx;
2813
2814 // Scan over all recurrences, trying to fold loop invariants into them.
2815 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
2816 // Scan all of the other operands to this add and add them to the vector if
2817 // they are loop invariant w.r.t. the recurrence.
2818 SmallVector<const SCEV *, 8> LIOps;
2819 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
2820 const Loop *AddRecLoop = AddRec->getLoop();
2821 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2822 if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) {
2823 LIOps.push_back(Ops[i]);
2824 Ops.erase(Ops.begin()+i);
2825 --i; --e;
2826 }
2827
2828 // If we found some loop invariants, fold them into the recurrence.
2829 if (!LIOps.empty()) {
2830 // Compute nowrap flags for the addition of the loop-invariant ops and
2831 // the addrec. Temporarily push it as an operand for that purpose. These
2832 // flags are valid in the scope of the addrec only.
2833 LIOps.push_back(AddRec);
2834 SCEV::NoWrapFlags Flags = ComputeFlags(LIOps);
2835 LIOps.pop_back();
2836
2837 // NLI + LI + {Start,+,Step} --> NLI + {LI+Start,+,Step}
2838 LIOps.push_back(AddRec->getStart());
2839
2840 SmallVector<const SCEV *, 4> AddRecOps(AddRec->operands());
2841
2842 // It is not in general safe to propagate flags valid on an add within
2843 // the addrec scope to one outside it. We must prove that the inner
2844 // scope is guaranteed to execute if the outer one does to be able to
2845 // safely propagate. We know the program is undefined if poison is
2846 // produced on the inner scoped addrec. We also know that *for this use*
2847 // the outer scoped add can't overflow (because of the flags we just
2848 // computed for the inner scoped add) without the program being undefined.
2849 // Proving that entry to the outer scope neccesitates entry to the inner
2850 // scope, thus proves the program undefined if the flags would be violated
2851 // in the outer scope.
2852 SCEV::NoWrapFlags AddFlags = Flags;
2853 if (AddFlags != SCEV::FlagAnyWrap) {
2854 auto *DefI = getDefiningScopeBound(LIOps);
2855 auto *ReachI = &*AddRecLoop->getHeader()->begin();
2856 if (!isGuaranteedToTransferExecutionTo(DefI, ReachI))
2857 AddFlags = SCEV::FlagAnyWrap;
2858 }
2859 AddRecOps[0] = getAddExpr(LIOps, AddFlags, Depth + 1);
2860
2861 // Build the new addrec. Propagate the NUW and NSW flags if both the
2862 // outer add and the inner addrec are guaranteed to have no overflow.
2863 // Always propagate NW.
2864 Flags = AddRec->getNoWrapFlags(setFlags(Flags, SCEV::FlagNW));
2865 const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop, Flags);
2866
2867 // If all of the other operands were loop invariant, we are done.
2868 if (Ops.size() == 1) return NewRec;
2869
2870 // Otherwise, add the folded AddRec by the non-invariant parts.
2871 for (unsigned i = 0;; ++i)
2872 if (Ops[i] == AddRec) {
2873 Ops[i] = NewRec;
2874 break;
2875 }
2876 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2877 }
2878
2879 // Okay, if there weren't any loop invariants to be folded, check to see if
2880 // there are multiple AddRec's with the same loop induction variable being
2881 // added together. If so, we can fold them.
2882 for (unsigned OtherIdx = Idx+1;
2883 OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2884 ++OtherIdx) {
2885 // We expect the AddRecExpr's to be sorted in reverse dominance order,
2886 // so that the 1st found AddRecExpr is dominated by all others.
2887 assert(DT.dominates((static_cast <bool> (DT.dominates( cast<SCEVAddRecExpr
>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->
getLoop()->getHeader()) && "AddRecExprs are not sorted in reverse dominance order?"
) ? void (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 2890, __extension__
__PRETTY_FUNCTION__))
2888 cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(),(static_cast <bool> (DT.dominates( cast<SCEVAddRecExpr
>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->
getLoop()->getHeader()) && "AddRecExprs are not sorted in reverse dominance order?"
) ? void (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 2890, __extension__
__PRETTY_FUNCTION__))
2889 AddRec->getLoop()->getHeader()) &&(static_cast <bool> (DT.dominates( cast<SCEVAddRecExpr
>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->
getLoop()->getHeader()) && "AddRecExprs are not sorted in reverse dominance order?"
) ? void (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 2890, __extension__
__PRETTY_FUNCTION__))
2890 "AddRecExprs are not sorted in reverse dominance order?")(static_cast <bool> (DT.dominates( cast<SCEVAddRecExpr
>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->
getLoop()->getHeader()) && "AddRecExprs are not sorted in reverse dominance order?"
) ? void (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 2890, __extension__
__PRETTY_FUNCTION__));
2891 if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) {
2892 // Other + {A,+,B}<L> + {C,+,D}<L> --> Other + {A+C,+,B+D}<L>
2893 SmallVector<const SCEV *, 4> AddRecOps(AddRec->operands());
2894 for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2895 ++OtherIdx) {
2896 const auto *OtherAddRec = cast<SCEVAddRecExpr>(Ops[OtherIdx]);
2897 if (OtherAddRec->getLoop() == AddRecLoop) {
2898 for (unsigned i = 0, e = OtherAddRec->getNumOperands();
2899 i != e; ++i) {
2900 if (i >= AddRecOps.size()) {
2901 AddRecOps.append(OtherAddRec->op_begin()+i,
2902 OtherAddRec->op_end());
2903 break;
2904 }
2905 SmallVector<const SCEV *, 2> TwoOps = {
2906 AddRecOps[i], OtherAddRec->getOperand(i)};
2907 AddRecOps[i] = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2908 }
2909 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
2910 }
2911 }
2912 // Step size has changed, so we cannot guarantee no self-wraparound.
2913 Ops[Idx] = getAddRecExpr(AddRecOps, AddRecLoop, SCEV::FlagAnyWrap);
2914 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2915 }
2916 }
2917
2918 // Otherwise couldn't fold anything into this recurrence. Move onto the
2919 // next one.
2920 }
2921
2922 // Okay, it looks like we really DO need an add expr. Check to see if we
2923 // already have one, otherwise create a new one.
2924 return getOrCreateAddExpr(Ops, ComputeFlags(Ops));
2925}
2926
2927const SCEV *
2928ScalarEvolution::getOrCreateAddExpr(ArrayRef<const SCEV *> Ops,
2929 SCEV::NoWrapFlags Flags) {
2930 FoldingSetNodeID ID;
2931 ID.AddInteger(scAddExpr);
2932 for (const SCEV *Op : Ops)
2933 ID.AddPointer(Op);
2934 void *IP = nullptr;
2935 SCEVAddExpr *S =
2936 static_cast<SCEVAddExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2937 if (!S) {
2938 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2939 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2940 S = new (SCEVAllocator)
2941 SCEVAddExpr(ID.Intern(SCEVAllocator), O, Ops.size());
2942 UniqueSCEVs.InsertNode(S, IP);
2943 registerUser(S, Ops);
2944 }
2945 S->setNoWrapFlags(Flags);
2946 return S;
2947}
2948
2949const SCEV *
2950ScalarEvolution::getOrCreateAddRecExpr(ArrayRef<const SCEV *> Ops,
2951 const Loop *L, SCEV::NoWrapFlags Flags) {
2952 FoldingSetNodeID ID;
2953 ID.AddInteger(scAddRecExpr);
2954 for (const SCEV *Op : Ops)
2955 ID.AddPointer(Op);
2956 ID.AddPointer(L);
2957 void *IP = nullptr;
2958 SCEVAddRecExpr *S =
2959 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2960 if (!S) {
2961 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2962 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2963 S = new (SCEVAllocator)
2964 SCEVAddRecExpr(ID.Intern(SCEVAllocator), O, Ops.size(), L);
2965 UniqueSCEVs.InsertNode(S, IP);
2966 LoopUsers[L].push_back(S);
2967 registerUser(S, Ops);
2968 }
2969 setNoWrapFlags(S, Flags);
2970 return S;
2971}
2972
2973const SCEV *
2974ScalarEvolution::getOrCreateMulExpr(ArrayRef<const SCEV *> Ops,
2975 SCEV::NoWrapFlags Flags) {
2976 FoldingSetNodeID ID;
2977 ID.AddInteger(scMulExpr);
2978 for (const SCEV *Op : Ops)
2979 ID.AddPointer(Op);
2980 void *IP = nullptr;
2981 SCEVMulExpr *S =
2982 static_cast<SCEVMulExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2983 if (!S) {
2984 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2985 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2986 S = new (SCEVAllocator) SCEVMulExpr(ID.Intern(SCEVAllocator),
2987 O, Ops.size());
2988 UniqueSCEVs.InsertNode(S, IP);
2989 registerUser(S, Ops);
2990 }
2991 S->setNoWrapFlags(Flags);
2992 return S;
2993}
2994
2995static uint64_t umul_ov(uint64_t i, uint64_t j, bool &Overflow) {
2996 uint64_t k = i*j;
2997 if (j > 1 && k / j != i) Overflow = true;
2998 return k;
2999}
3000
3001/// Compute the result of "n choose k", the binomial coefficient. If an
3002/// intermediate computation overflows, Overflow will be set and the return will
3003/// be garbage. Overflow is not cleared on absence of overflow.
3004static uint64_t Choose(uint64_t n, uint64_t k, bool &Overflow) {
3005 // We use the multiplicative formula:
3006 // n(n-1)(n-2)...(n-(k-1)) / k(k-1)(k-2)...1 .
3007 // At each iteration, we take the n-th term of the numeral and divide by the
3008 // (k-n)th term of the denominator. This division will always produce an
3009 // integral result, and helps reduce the chance of overflow in the
3010 // intermediate computations. However, we can still overflow even when the
3011 // final result would fit.
3012
3013 if (n == 0 || n == k) return 1;
3014 if (k > n) return 0;
3015
3016 if (k > n/2)
3017 k = n-k;
3018
3019 uint64_t r = 1;
3020 for (uint64_t i = 1; i <= k; ++i) {
3021 r = umul_ov(r, n-(i-1), Overflow);
3022 r /= i;
3023 }
3024 return r;
3025}
3026
3027/// Determine if any of the operands in this SCEV are a constant or if
3028/// any of the add or multiply expressions in this SCEV contain a constant.
3029static bool containsConstantInAddMulChain(const SCEV *StartExpr) {
3030 struct FindConstantInAddMulChain {
3031 bool FoundConstant = false;
3032
3033 bool follow(const SCEV *S) {
3034 FoundConstant |= isa<SCEVConstant>(S);
3035 return isa<SCEVAddExpr>(S) || isa<SCEVMulExpr>(S);
3036 }
3037
3038 bool isDone() const {
3039 return FoundConstant;
3040 }
3041 };
3042
3043 FindConstantInAddMulChain F;
3044 SCEVTraversal<FindConstantInAddMulChain> ST(F);
3045 ST.visitAll(StartExpr);
3046 return F.FoundConstant;
3047}
3048
3049/// Get a canonical multiply expression, or something simpler if possible.
3050const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
3051 SCEV::NoWrapFlags OrigFlags,
3052 unsigned Depth) {
3053 assert(OrigFlags == maskFlags(OrigFlags, SCEV::FlagNUW | SCEV::FlagNSW) &&(static_cast <bool> (OrigFlags == maskFlags(OrigFlags, SCEV
::FlagNUW | SCEV::FlagNSW) && "only nuw or nsw allowed"
) ? void (0) : __assert_fail ("OrigFlags == maskFlags(OrigFlags, SCEV::FlagNUW | SCEV::FlagNSW) && \"only nuw or nsw allowed\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3054, __extension__
__PRETTY_FUNCTION__))
3054 "only nuw or nsw allowed")(static_cast <bool> (OrigFlags == maskFlags(OrigFlags, SCEV
::FlagNUW | SCEV::FlagNSW) && "only nuw or nsw allowed"
) ? void (0) : __assert_fail ("OrigFlags == maskFlags(OrigFlags, SCEV::FlagNUW | SCEV::FlagNSW) && \"only nuw or nsw allowed\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3054, __extension__
__PRETTY_FUNCTION__));
3055 assert(!Ops.empty() && "Cannot get empty mul!")(static_cast <bool> (!Ops.empty() && "Cannot get empty mul!"
) ? void (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty mul!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3055, __extension__
__PRETTY_FUNCTION__));
3056 if (Ops.size() == 1) return Ops[0];
3057#ifndef NDEBUG
3058 Type *ETy = Ops[0]->getType();
3059 assert(!ETy->isPointerTy())(static_cast <bool> (!ETy->isPointerTy()) ? void (0)
: __assert_fail ("!ETy->isPointerTy()", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 3059, __extension__ __PRETTY_FUNCTION__));
3060 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
3061 assert(Ops[i]->getType() == ETy &&(static_cast <bool> (Ops[i]->getType() == ETy &&
"SCEVMulExpr operand types don't match!") ? void (0) : __assert_fail
("Ops[i]->getType() == ETy && \"SCEVMulExpr operand types don't match!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3062, __extension__
__PRETTY_FUNCTION__))
3062 "SCEVMulExpr operand types don't match!")(static_cast <bool> (Ops[i]->getType() == ETy &&
"SCEVMulExpr operand types don't match!") ? void (0) : __assert_fail
("Ops[i]->getType() == ETy && \"SCEVMulExpr operand types don't match!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3062, __extension__
__PRETTY_FUNCTION__));
3063#endif
3064
3065 // Sort by complexity, this groups all similar expression types together.
3066 GroupByComplexity(Ops, &LI, DT);
3067
3068 // If there are any constants, fold them together.
3069 unsigned Idx = 0;
3070 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
3071 ++Idx;
3072 assert(Idx < Ops.size())(static_cast <bool> (Idx < Ops.size()) ? void (0) : __assert_fail
("Idx < Ops.size()", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 3072, __extension__ __PRETTY_FUNCTION__));
3073 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
3074 // We found two constants, fold them together!
3075 Ops[0] = getConstant(LHSC->getAPInt() * RHSC->getAPInt());
3076 if (Ops.size() == 2) return Ops[0];
3077 Ops.erase(Ops.begin()+1); // Erase the folded element
3078 LHSC = cast<SCEVConstant>(Ops[0]);
3079 }
3080
3081 // If we have a multiply of zero, it will always be zero.
3082 if (LHSC->getValue()->isZero())
3083 return LHSC;
3084
3085 // If we are left with a constant one being multiplied, strip it off.
3086 if (LHSC->getValue()->isOne()) {
3087 Ops.erase(Ops.begin());
3088 --Idx;
3089 }
3090
3091 if (Ops.size() == 1)
3092 return Ops[0];
3093 }
3094
3095 // Delay expensive flag strengthening until necessary.
3096 auto ComputeFlags = [this, OrigFlags](const ArrayRef<const SCEV *> Ops) {
3097 return StrengthenNoWrapFlags(this, scMulExpr, Ops, OrigFlags);
3098 };
3099
3100 // Limit recursion calls depth.
3101 if (Depth > MaxArithDepth || hasHugeExpression(Ops))
3102 return getOrCreateMulExpr(Ops, ComputeFlags(Ops));
3103
3104 if (SCEV *S = findExistingSCEVInCache(scMulExpr, Ops)) {
3105 // Don't strengthen flags if we have no new information.
3106 SCEVMulExpr *Mul = static_cast<SCEVMulExpr *>(S);
3107 if (Mul->getNoWrapFlags(OrigFlags) != OrigFlags)
3108 Mul->setNoWrapFlags(ComputeFlags(Ops));
3109 return S;
3110 }
3111
3112 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
3113 if (Ops.size() == 2) {
3114 // C1*(C2+V) -> C1*C2 + C1*V
3115 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1]))
3116 // If any of Add's ops are Adds or Muls with a constant, apply this
3117 // transformation as well.
3118 //
3119 // TODO: There are some cases where this transformation is not
3120 // profitable; for example, Add = (C0 + X) * Y + Z. Maybe the scope of
3121 // this transformation should be narrowed down.
3122 if (Add->getNumOperands() == 2 && containsConstantInAddMulChain(Add))
3123 return getAddExpr(getMulExpr(LHSC, Add->getOperand(0),
3124 SCEV::FlagAnyWrap, Depth + 1),
3125 getMulExpr(LHSC, Add->getOperand(1),
3126 SCEV::FlagAnyWrap, Depth + 1),
3127 SCEV::FlagAnyWrap, Depth + 1);
3128
3129 if (Ops[0]->isAllOnesValue()) {
3130 // If we have a mul by -1 of an add, try distributing the -1 among the
3131 // add operands.
3132 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) {
3133 SmallVector<const SCEV *, 4> NewOps;
3134 bool AnyFolded = false;
3135 for (const SCEV *AddOp : Add->operands()) {
3136 const SCEV *Mul = getMulExpr(Ops[0], AddOp, SCEV::FlagAnyWrap,
3137 Depth + 1);
3138 if (!isa<SCEVMulExpr>(Mul)) AnyFolded = true;
3139 NewOps.push_back(Mul);
3140 }
3141 if (AnyFolded)
3142 return getAddExpr(NewOps, SCEV::FlagAnyWrap, Depth + 1);
3143 } else if (const auto *AddRec = dyn_cast<SCEVAddRecExpr>(Ops[1])) {
3144 // Negation preserves a recurrence's no self-wrap property.
3145 SmallVector<const SCEV *, 4> Operands;
3146 for (const SCEV *AddRecOp : AddRec->operands())
3147 Operands.push_back(getMulExpr(Ops[0], AddRecOp, SCEV::FlagAnyWrap,
3148 Depth + 1));
3149
3150 return getAddRecExpr(Operands, AddRec->getLoop(),
3151 AddRec->getNoWrapFlags(SCEV::FlagNW));
3152 }
3153 }
3154 }
3155 }
3156
3157 // Skip over the add expression until we get to a multiply.
3158 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
3159 ++Idx;
3160
3161 // If there are mul operands inline them all into this expression.
3162 if (Idx < Ops.size()) {
3163 bool DeletedMul = false;
3164 while (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
3165 if (Ops.size() > MulOpsInlineThreshold)
3166 break;
3167 // If we have an mul, expand the mul operands onto the end of the
3168 // operands list.
3169 Ops.erase(Ops.begin()+Idx);
3170 Ops.append(Mul->op_begin(), Mul->op_end());
3171 DeletedMul = true;
3172 }
3173
3174 // If we deleted at least one mul, we added operands to the end of the
3175 // list, and they are not necessarily sorted. Recurse to resort and
3176 // resimplify any operands we just acquired.
3177 if (DeletedMul)
3178 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
3179 }
3180
3181 // If there are any add recurrences in the operands list, see if any other
3182 // added values are loop invariant. If so, we can fold them into the
3183 // recurrence.
3184 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
3185 ++Idx;
3186
3187 // Scan over all recurrences, trying to fold loop invariants into them.
3188 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
3189 // Scan all of the other operands to this mul and add them to the vector
3190 // if they are loop invariant w.r.t. the recurrence.
3191 SmallVector<const SCEV *, 8> LIOps;
3192 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
3193 const Loop *AddRecLoop = AddRec->getLoop();
3194 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3195 if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) {
3196 LIOps.push_back(Ops[i]);
3197 Ops.erase(Ops.begin()+i);
3198 --i; --e;
3199 }
3200
3201 // If we found some loop invariants, fold them into the recurrence.
3202 if (!LIOps.empty()) {
3203 // NLI * LI * {Start,+,Step} --> NLI * {LI*Start,+,LI*Step}
3204 SmallVector<const SCEV *, 4> NewOps;
3205 NewOps.reserve(AddRec->getNumOperands());
3206 const SCEV *Scale = getMulExpr(LIOps, SCEV::FlagAnyWrap, Depth + 1);
3207 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i)
3208 NewOps.push_back(getMulExpr(Scale, AddRec->getOperand(i),
3209 SCEV::FlagAnyWrap, Depth + 1));
3210
3211 // Build the new addrec. Propagate the NUW and NSW flags if both the
3212 // outer mul and the inner addrec are guaranteed to have no overflow.
3213 //
3214 // No self-wrap cannot be guaranteed after changing the step size, but
3215 // will be inferred if either NUW or NSW is true.
3216 SCEV::NoWrapFlags Flags = ComputeFlags({Scale, AddRec});
3217 const SCEV *NewRec = getAddRecExpr(
3218 NewOps, AddRecLoop, AddRec->getNoWrapFlags(Flags));
3219
3220 // If all of the other operands were loop invariant, we are done.
3221 if (Ops.size() == 1) return NewRec;
3222
3223 // Otherwise, multiply the folded AddRec by the non-invariant parts.
3224 for (unsigned i = 0;; ++i)
3225 if (Ops[i] == AddRec) {
3226 Ops[i] = NewRec;
3227 break;
3228 }
3229 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
3230 }
3231
3232 // Okay, if there weren't any loop invariants to be folded, check to see
3233 // if there are multiple AddRec's with the same loop induction variable
3234 // being multiplied together. If so, we can fold them.
3235
3236 // {A1,+,A2,+,...,+,An}<L> * {B1,+,B2,+,...,+,Bn}<L>
3237 // = {x=1 in [ sum y=x..2x [ sum z=max(y-x, y-n)..min(x,n) [
3238 // choose(x, 2x)*choose(2x-y, x-z)*A_{y-z}*B_z
3239 // ]]],+,...up to x=2n}.
3240 // Note that the arguments to choose() are always integers with values
3241 // known at compile time, never SCEV objects.
3242 //
3243 // The implementation avoids pointless extra computations when the two
3244 // addrec's are of different length (mathematically, it's equivalent to
3245 // an infinite stream of zeros on the right).
3246 bool OpsModified = false;
3247 for (unsigned OtherIdx = Idx+1;
3248 OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
3249 ++OtherIdx) {
3250 const SCEVAddRecExpr *OtherAddRec =
3251 dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]);
3252 if (!OtherAddRec || OtherAddRec->getLoop() != AddRecLoop)
3253 continue;
3254
3255 // Limit max number of arguments to avoid creation of unreasonably big
3256 // SCEVAddRecs with very complex operands.
3257 if (AddRec->getNumOperands() + OtherAddRec->getNumOperands() - 1 >
3258 MaxAddRecSize || hasHugeExpression({AddRec, OtherAddRec}))
3259 continue;
3260
3261 bool Overflow = false;
3262 Type *Ty = AddRec->getType();
3263 bool LargerThan64Bits = getTypeSizeInBits(Ty) > 64;
3264 SmallVector<const SCEV*, 7> AddRecOps;
3265 for (int x = 0, xe = AddRec->getNumOperands() +
3266 OtherAddRec->getNumOperands() - 1; x != xe && !Overflow; ++x) {
3267 SmallVector <const SCEV *, 7> SumOps;
3268 for (int y = x, ye = 2*x+1; y != ye && !Overflow; ++y) {
3269 uint64_t Coeff1 = Choose(x, 2*x - y, Overflow);
3270 for (int z = std::max(y-x, y-(int)AddRec->getNumOperands()+1),
3271 ze = std::min(x+1, (int)OtherAddRec->getNumOperands());
3272 z < ze && !Overflow; ++z) {
3273 uint64_t Coeff2 = Choose(2*x - y, x-z, Overflow);
3274 uint64_t Coeff;
3275 if (LargerThan64Bits)
3276 Coeff = umul_ov(Coeff1, Coeff2, Overflow);
3277 else
3278 Coeff = Coeff1*Coeff2;
3279 const SCEV *CoeffTerm = getConstant(Ty, Coeff);
3280 const SCEV *Term1 = AddRec->getOperand(y-z);
3281 const SCEV *Term2 = OtherAddRec->getOperand(z);
3282 SumOps.push_back(getMulExpr(CoeffTerm, Term1, Term2,
3283 SCEV::FlagAnyWrap, Depth + 1));
3284 }
3285 }
3286 if (SumOps.empty())
3287 SumOps.push_back(getZero(Ty));
3288 AddRecOps.push_back(getAddExpr(SumOps, SCEV::FlagAnyWrap, Depth + 1));
3289 }
3290 if (!Overflow) {
3291 const SCEV *NewAddRec = getAddRecExpr(AddRecOps, AddRecLoop,
3292 SCEV::FlagAnyWrap);
3293 if (Ops.size() == 2) return NewAddRec;
3294 Ops[Idx] = NewAddRec;
3295 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
3296 OpsModified = true;
3297 AddRec = dyn_cast<SCEVAddRecExpr>(NewAddRec);
3298 if (!AddRec)
3299 break;
3300 }
3301 }
3302 if (OpsModified)
3303 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
3304
3305 // Otherwise couldn't fold anything into this recurrence. Move onto the
3306 // next one.
3307 }
3308
3309 // Okay, it looks like we really DO need an mul expr. Check to see if we
3310 // already have one, otherwise create a new one.
3311 return getOrCreateMulExpr(Ops, ComputeFlags(Ops));
3312}
3313
3314/// Represents an unsigned remainder expression based on unsigned division.
3315const SCEV *ScalarEvolution::getURemExpr(const SCEV *LHS,
3316 const SCEV *RHS) {
3317 assert(getEffectiveSCEVType(LHS->getType()) ==(static_cast <bool> (getEffectiveSCEVType(LHS->getType
()) == getEffectiveSCEVType(RHS->getType()) && "SCEVURemExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3319, __extension__
__PRETTY_FUNCTION__))
3318 getEffectiveSCEVType(RHS->getType()) &&(static_cast <bool> (getEffectiveSCEVType(LHS->getType
()) == getEffectiveSCEVType(RHS->getType()) && "SCEVURemExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3319, __extension__
__PRETTY_FUNCTION__))
3319 "SCEVURemExpr operand types don't match!")(static_cast <bool> (getEffectiveSCEVType(LHS->getType
()) == getEffectiveSCEVType(RHS->getType()) && "SCEVURemExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3319, __extension__
__PRETTY_FUNCTION__));
3320
3321 // Short-circuit easy cases
3322 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
3323 // If constant is one, the result is trivial
3324 if (RHSC->getValue()->isOne())
3325 return getZero(LHS->getType()); // X urem 1 --> 0
3326
3327 // If constant is a power of two, fold into a zext(trunc(LHS)).
3328 if (RHSC->getAPInt().isPowerOf2()) {
3329 Type *FullTy = LHS->getType();
3330 Type *TruncTy =
3331 IntegerType::get(getContext(), RHSC->getAPInt().logBase2());
3332 return getZeroExtendExpr(getTruncateExpr(LHS, TruncTy), FullTy);
3333 }
3334 }
3335
3336 // Fallback to %a == %x urem %y == %x -<nuw> ((%x udiv %y) *<nuw> %y)
3337 const SCEV *UDiv = getUDivExpr(LHS, RHS);
3338 const SCEV *Mult = getMulExpr(UDiv, RHS, SCEV::FlagNUW);
3339 return getMinusSCEV(LHS, Mult, SCEV::FlagNUW);
3340}
3341
3342/// Get a canonical unsigned division expression, or something simpler if
3343/// possible.
3344const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS,
3345 const SCEV *RHS) {
3346 assert(!LHS->getType()->isPointerTy() &&(static_cast <bool> (!LHS->getType()->isPointerTy
() && "SCEVUDivExpr operand can't be pointer!") ? void
(0) : __assert_fail ("!LHS->getType()->isPointerTy() && \"SCEVUDivExpr operand can't be pointer!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3347, __extension__
__PRETTY_FUNCTION__))
3347 "SCEVUDivExpr operand can't be pointer!")(static_cast <bool> (!LHS->getType()->isPointerTy
() && "SCEVUDivExpr operand can't be pointer!") ? void
(0) : __assert_fail ("!LHS->getType()->isPointerTy() && \"SCEVUDivExpr operand can't be pointer!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3347, __extension__
__PRETTY_FUNCTION__));
3348 assert(LHS->getType() == RHS->getType() &&(static_cast <bool> (LHS->getType() == RHS->getType
() && "SCEVUDivExpr operand types don't match!") ? void
(0) : __assert_fail ("LHS->getType() == RHS->getType() && \"SCEVUDivExpr operand types don't match!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3349, __extension__
__PRETTY_FUNCTION__))
3349 "SCEVUDivExpr operand types don't match!")(static_cast <bool> (LHS->getType() == RHS->getType
() && "SCEVUDivExpr operand types don't match!") ? void
(0) : __assert_fail ("LHS->getType() == RHS->getType() && \"SCEVUDivExpr operand types don't match!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3349, __extension__
__PRETTY_FUNCTION__));
3350
3351 FoldingSetNodeID ID;
3352 ID.AddInteger(scUDivExpr);
3353 ID.AddPointer(LHS);
3354 ID.AddPointer(RHS);
3355 void *IP = nullptr;
3356 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
3357 return S;
3358
3359 // 0 udiv Y == 0
3360 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS))
3361 if (LHSC->getValue()->isZero())
3362 return LHS;
3363
3364 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
3365 if (RHSC->getValue()->isOne())
3366 return LHS; // X udiv 1 --> x
3367 // If the denominator is zero, the result of the udiv is undefined. Don't
3368 // try to analyze it, because the resolution chosen here may differ from
3369 // the resolution chosen in other parts of the compiler.
3370 if (!RHSC->getValue()->isZero()) {
3371 // Determine if the division can be folded into the operands of
3372 // its operands.
3373 // TODO: Generalize this to non-constants by using known-bits information.
3374 Type *Ty = LHS->getType();
3375 unsigned LZ = RHSC->getAPInt().countLeadingZeros();
3376 unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ - 1;
3377 // For non-power-of-two values, effectively round the value up to the
3378 // nearest power of two.
3379 if (!RHSC->getAPInt().isPowerOf2())
3380 ++MaxShiftAmt;
3381 IntegerType *ExtTy =
3382 IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt);
3383 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS))
3384 if (const SCEVConstant *Step =
3385 dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this))) {
3386 // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded.
3387 const APInt &StepInt = Step->getAPInt();
3388 const APInt &DivInt = RHSC->getAPInt();
3389 if (!StepInt.urem(DivInt) &&
3390 getZeroExtendExpr(AR, ExtTy) ==
3391 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
3392 getZeroExtendExpr(Step, ExtTy),
3393 AR->getLoop(), SCEV::FlagAnyWrap)) {
3394 SmallVector<const SCEV *, 4> Operands;
3395 for (const SCEV *Op : AR->operands())
3396 Operands.push_back(getUDivExpr(Op, RHS));
3397 return getAddRecExpr(Operands, AR->getLoop(), SCEV::FlagNW);
3398 }
3399 /// Get a canonical UDivExpr for a recurrence.
3400 /// {X,+,N}/C => {Y,+,N}/C where Y=X-(X%N). Safe when C%N=0.
3401 // We can currently only fold X%N if X is constant.
3402 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(AR->getStart());
3403 if (StartC && !DivInt.urem(StepInt) &&
3404 getZeroExtendExpr(AR, ExtTy) ==
3405 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
3406 getZeroExtendExpr(Step, ExtTy),
3407 AR->getLoop(), SCEV::FlagAnyWrap)) {
3408 const APInt &StartInt = StartC->getAPInt();
3409 const APInt &StartRem = StartInt.urem(StepInt);
3410 if (StartRem != 0) {
3411 const SCEV *NewLHS =
3412 getAddRecExpr(getConstant(StartInt - StartRem), Step,
3413 AR->getLoop(), SCEV::FlagNW);
3414 if (LHS != NewLHS) {
3415 LHS = NewLHS;
3416
3417 // Reset the ID to include the new LHS, and check if it is
3418 // already cached.
3419 ID.clear();
3420 ID.AddInteger(scUDivExpr);
3421 ID.AddPointer(LHS);
3422 ID.AddPointer(RHS);
3423 IP = nullptr;
3424 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
3425 return S;
3426 }
3427 }
3428 }
3429 }
3430 // (A*B)/C --> A*(B/C) if safe and B/C can be folded.
3431 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) {
3432 SmallVector<const SCEV *, 4> Operands;
3433 for (const SCEV *Op : M->operands())
3434 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
3435 if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands))
3436 // Find an operand that's safely divisible.
3437 for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) {
3438 const SCEV *Op = M->getOperand(i);
3439 const SCEV *Div = getUDivExpr(Op, RHSC);
3440 if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) {
3441 Operands = SmallVector<const SCEV *, 4>(M->operands());
3442 Operands[i] = Div;
3443 return getMulExpr(Operands);
3444 }
3445 }
3446 }
3447
3448 // (A/B)/C --> A/(B*C) if safe and B*C can be folded.
3449 if (const SCEVUDivExpr *OtherDiv = dyn_cast<SCEVUDivExpr>(LHS)) {
3450 if (auto *DivisorConstant =
3451 dyn_cast<SCEVConstant>(OtherDiv->getRHS())) {
3452 bool Overflow = false;
3453 APInt NewRHS =
3454 DivisorConstant->getAPInt().umul_ov(RHSC->getAPInt(), Overflow);
3455 if (Overflow) {
3456 return getConstant(RHSC->getType(), 0, false);
3457 }
3458 return getUDivExpr(OtherDiv->getLHS(), getConstant(NewRHS));
3459 }
3460 }
3461
3462 // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded.
3463 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(LHS)) {
3464 SmallVector<const SCEV *, 4> Operands;
3465 for (const SCEV *Op : A->operands())
3466 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
3467 if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) {
3468 Operands.clear();
3469 for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) {
3470 const SCEV *Op = getUDivExpr(A->getOperand(i), RHS);
3471 if (isa<SCEVUDivExpr>(Op) ||
3472 getMulExpr(Op, RHS) != A->getOperand(i))
3473 break;
3474 Operands.push_back(Op);
3475 }
3476 if (Operands.size() == A->getNumOperands())
3477 return getAddExpr(Operands);
3478 }
3479 }
3480
3481 // Fold if both operands are constant.
3482 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
3483 Constant *LHSCV = LHSC->getValue();
3484 Constant *RHSCV = RHSC->getValue();
3485 return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV,
3486 RHSCV)));
3487 }
3488 }
3489 }
3490
3491 // The Insertion Point (IP) might be invalid by now (due to UniqueSCEVs
3492 // changes). Make sure we get a new one.
3493 IP = nullptr;
3494 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
3495 SCEV *S = new (SCEVAllocator) SCEVUDivExpr(ID.Intern(SCEVAllocator),
3496 LHS, RHS);
3497 UniqueSCEVs.InsertNode(S, IP);
3498 registerUser(S, {LHS, RHS});
3499 return S;
3500}
3501
3502APInt gcd(const SCEVConstant *C1, const SCEVConstant *C2) {
3503 APInt A = C1->getAPInt().abs();
3504 APInt B = C2->getAPInt().abs();
3505 uint32_t ABW = A.getBitWidth();
3506 uint32_t BBW = B.getBitWidth();
3507
3508 if (ABW > BBW)
3509 B = B.zext(ABW);
3510 else if (ABW < BBW)
3511 A = A.zext(BBW);
3512
3513 return APIntOps::GreatestCommonDivisor(std::move(A), std::move(B));
3514}
3515
3516/// Get a canonical unsigned division expression, or something simpler if
3517/// possible. There is no representation for an exact udiv in SCEV IR, but we
3518/// can attempt to remove factors from the LHS and RHS. We can't do this when
3519/// it's not exact because the udiv may be clearing bits.
3520const SCEV *ScalarEvolution::getUDivExactExpr(const SCEV *LHS,
3521 const SCEV *RHS) {
3522 // TODO: we could try to find factors in all sorts of things, but for now we
3523 // just deal with u/exact (multiply, constant). See SCEVDivision towards the
3524 // end of this file for inspiration.
3525
3526 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS);
3527 if (!Mul || !Mul->hasNoUnsignedWrap())
3528 return getUDivExpr(LHS, RHS);
3529
3530 if (const SCEVConstant *RHSCst = dyn_cast<SCEVConstant>(RHS)) {
3531 // If the mulexpr multiplies by a constant, then that constant must be the
3532 // first element of the mulexpr.
3533 if (const auto *LHSCst = dyn_cast<SCEVConstant>(Mul->getOperand(0))) {
3534 if (LHSCst == RHSCst) {
3535 SmallVector<const SCEV *, 2> Operands(drop_begin(Mul->operands()));
3536 return getMulExpr(Operands);
3537 }
3538
3539 // We can't just assume that LHSCst divides RHSCst cleanly, it could be
3540 // that there's a factor provided by one of the other terms. We need to
3541 // check.
3542 APInt Factor = gcd(LHSCst, RHSCst);
3543 if (!Factor.isIntN(1)) {
3544 LHSCst =
3545 cast<SCEVConstant>(getConstant(LHSCst->getAPInt().udiv(Factor)));
3546 RHSCst =
3547 cast<SCEVConstant>(getConstant(RHSCst->getAPInt().udiv(Factor)));
3548 SmallVector<const SCEV *, 2> Operands;
3549 Operands.push_back(LHSCst);
3550 Operands.append(Mul->op_begin() + 1, Mul->op_end());
3551 LHS = getMulExpr(Operands);
3552 RHS = RHSCst;
3553 Mul = dyn_cast<SCEVMulExpr>(LHS);
3554 if (!Mul)
3555 return getUDivExactExpr(LHS, RHS);
3556 }
3557 }
3558 }
3559
3560 for (int i = 0, e = Mul->getNumOperands(); i != e; ++i) {
3561 if (Mul->getOperand(i) == RHS) {
3562 SmallVector<const SCEV *, 2> Operands;
3563 Operands.append(Mul->op_begin(), Mul->op_begin() + i);
3564 Operands.append(Mul->op_begin() + i + 1, Mul->op_end());
3565 return getMulExpr(Operands);
3566 }
3567 }
3568
3569 return getUDivExpr(LHS, RHS);
3570}
3571
3572/// Get an add recurrence expression for the specified loop. Simplify the
3573/// expression as much as possible.
3574const SCEV *ScalarEvolution::getAddRecExpr(const SCEV *Start, const SCEV *Step,
3575 const Loop *L,
3576 SCEV::NoWrapFlags Flags) {
3577 SmallVector<const SCEV *, 4> Operands;
3578 Operands.push_back(Start);
3579 if (const SCEVAddRecExpr *StepChrec = dyn_cast<SCEVAddRecExpr>(Step))
3580 if (StepChrec->getLoop() == L) {
3581 Operands.append(StepChrec->op_begin(), StepChrec->op_end());
3582 return getAddRecExpr(Operands, L, maskFlags(Flags, SCEV::FlagNW));
3583 }
3584
3585 Operands.push_back(Step);
3586 return getAddRecExpr(Operands, L, Flags);
3587}
3588
3589/// Get an add recurrence expression for the specified loop. Simplify the
3590/// expression as much as possible.
3591const SCEV *
3592ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
3593 const Loop *L, SCEV::NoWrapFlags Flags) {
3594 if (Operands.size() == 1) return Operands[0];
3595#ifndef NDEBUG
3596 Type *ETy = getEffectiveSCEVType(Operands[0]->getType());
3597 for (unsigned i = 1, e = Operands.size(); i != e; ++i) {
3598 assert(getEffectiveSCEVType(Operands[i]->getType()) == ETy &&(static_cast <bool> (getEffectiveSCEVType(Operands[i]->
getType()) == ETy && "SCEVAddRecExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(Operands[i]->getType()) == ETy && \"SCEVAddRecExpr operand types don't match!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3599, __extension__
__PRETTY_FUNCTION__))
3599 "SCEVAddRecExpr operand types don't match!")(static_cast <bool> (getEffectiveSCEVType(Operands[i]->
getType()) == ETy && "SCEVAddRecExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(Operands[i]->getType()) == ETy && \"SCEVAddRecExpr operand types don't match!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3599, __extension__
__PRETTY_FUNCTION__));
3600 assert(!Operands[i]->getType()->isPointerTy() && "Step must be integer")(static_cast <bool> (!Operands[i]->getType()->isPointerTy
() && "Step must be integer") ? void (0) : __assert_fail
("!Operands[i]->getType()->isPointerTy() && \"Step must be integer\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3600, __extension__
__PRETTY_FUNCTION__));
3601 }
3602 for (unsigned i = 0, e = Operands.size(); i != e; ++i)
3603 assert(isLoopInvariant(Operands[i], L) &&(static_cast <bool> (isLoopInvariant(Operands[i], L) &&
"SCEVAddRecExpr operand is not loop-invariant!") ? void (0) :
__assert_fail ("isLoopInvariant(Operands[i], L) && \"SCEVAddRecExpr operand is not loop-invariant!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3604, __extension__
__PRETTY_FUNCTION__))
3604 "SCEVAddRecExpr operand is not loop-invariant!")(static_cast <bool> (isLoopInvariant(Operands[i], L) &&
"SCEVAddRecExpr operand is not loop-invariant!") ? void (0) :
__assert_fail ("isLoopInvariant(Operands[i], L) && \"SCEVAddRecExpr operand is not loop-invariant!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3604, __extension__
__PRETTY_FUNCTION__));
3605#endif
3606
3607 if (Operands.back()->isZero()) {
3608 Operands.pop_back();
3609 return getAddRecExpr(Operands, L, SCEV::FlagAnyWrap); // {X,+,0} --> X
3610 }
3611
3612 // It's tempting to want to call getConstantMaxBackedgeTakenCount count here and
3613 // use that information to infer NUW and NSW flags. However, computing a
3614 // BE count requires calling getAddRecExpr, so we may not yet have a
3615 // meaningful BE count at this point (and if we don't, we'd be stuck
3616 // with a SCEVCouldNotCompute as the cached BE count).
3617
3618 Flags = StrengthenNoWrapFlags(this, scAddRecExpr, Operands, Flags);
3619
3620 // Canonicalize nested AddRecs in by nesting them in order of loop depth.
3621 if (const SCEVAddRecExpr *NestedAR = dyn_cast<SCEVAddRecExpr>(Operands[0])) {
3622 const Loop *NestedLoop = NestedAR->getLoop();
3623 if (L->contains(NestedLoop)
3624 ? (L->getLoopDepth() < NestedLoop->getLoopDepth())
3625 : (!NestedLoop->contains(L) &&
3626 DT.dominates(L->getHeader(), NestedLoop->getHeader()))) {
3627 SmallVector<const SCEV *, 4> NestedOperands(NestedAR->operands());
3628 Operands[0] = NestedAR->getStart();
3629 // AddRecs require their operands be loop-invariant with respect to their
3630 // loops. Don't perform this transformation if it would break this
3631 // requirement.
3632 bool AllInvariant = all_of(
3633 Operands, [&](const SCEV *Op) { return isLoopInvariant(Op, L); });
3634
3635 if (AllInvariant) {
3636 // Create a recurrence for the outer loop with the same step size.
3637 //
3638 // The outer recurrence keeps its NW flag but only keeps NUW/NSW if the
3639 // inner recurrence has the same property.
3640 SCEV::NoWrapFlags OuterFlags =
3641 maskFlags(Flags, SCEV::FlagNW | NestedAR->getNoWrapFlags());
3642
3643 NestedOperands[0] = getAddRecExpr(Operands, L, OuterFlags);
3644 AllInvariant = all_of(NestedOperands, [&](const SCEV *Op) {
3645 return isLoopInvariant(Op, NestedLoop);
3646 });
3647
3648 if (AllInvariant) {
3649 // Ok, both add recurrences are valid after the transformation.
3650 //
3651 // The inner recurrence keeps its NW flag but only keeps NUW/NSW if
3652 // the outer recurrence has the same property.
3653 SCEV::NoWrapFlags InnerFlags =
3654 maskFlags(NestedAR->getNoWrapFlags(), SCEV::FlagNW | Flags);
3655 return getAddRecExpr(NestedOperands, NestedLoop, InnerFlags);
3656 }
3657 }
3658 // Reset Operands to its original state.
3659 Operands[0] = NestedAR;
3660 }
3661 }
3662
3663 // Okay, it looks like we really DO need an addrec expr. Check to see if we
3664 // already have one, otherwise create a new one.
3665 return getOrCreateAddRecExpr(Operands, L, Flags);
3666}
3667
3668const SCEV *
3669ScalarEvolution::getGEPExpr(GEPOperator *GEP,
3670 const SmallVectorImpl<const SCEV *> &IndexExprs) {
3671 const SCEV *BaseExpr = getSCEV(GEP->getPointerOperand());
3672 // getSCEV(Base)->getType() has the same address space as Base->getType()
3673 // because SCEV::getType() preserves the address space.
3674 Type *IntIdxTy = getEffectiveSCEVType(BaseExpr->getType());
3675 const bool AssumeInBoundsFlags = [&]() {
3676 if (!GEP->isInBounds())
3677 return false;
3678
3679 // We'd like to propagate flags from the IR to the corresponding SCEV nodes,
3680 // but to do that, we have to ensure that said flag is valid in the entire
3681 // defined scope of the SCEV.
3682 auto *GEPI = dyn_cast<Instruction>(GEP);
3683 // TODO: non-instructions have global scope. We might be able to prove
3684 // some global scope cases
3685 return GEPI && isSCEVExprNeverPoison(GEPI);
3686 }();
3687
3688 SCEV::NoWrapFlags OffsetWrap =
3689 AssumeInBoundsFlags ? SCEV::FlagNSW : SCEV::FlagAnyWrap;
3690
3691 Type *CurTy = GEP->getType();
3692 bool FirstIter = true;
3693 SmallVector<const SCEV *, 4> Offsets;
3694 for (const SCEV *IndexExpr : IndexExprs) {
3695 // Compute the (potentially symbolic) offset in bytes for this index.
3696 if (StructType *STy = dyn_cast<StructType>(CurTy)) {
3697 // For a struct, add the member offset.
3698 ConstantInt *Index = cast<SCEVConstant>(IndexExpr)->getValue();
3699 unsigned FieldNo = Index->getZExtValue();
3700 const SCEV *FieldOffset = getOffsetOfExpr(IntIdxTy, STy, FieldNo);
3701 Offsets.push_back(FieldOffset);
3702
3703 // Update CurTy to the type of the field at Index.
3704 CurTy = STy->getTypeAtIndex(Index);
3705 } else {
3706 // Update CurTy to its element type.
3707 if (FirstIter) {
3708 assert(isa<PointerType>(CurTy) &&(static_cast <bool> (isa<PointerType>(CurTy) &&
"The first index of a GEP indexes a pointer") ? void (0) : __assert_fail
("isa<PointerType>(CurTy) && \"The first index of a GEP indexes a pointer\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3709, __extension__
__PRETTY_FUNCTION__))
3709 "The first index of a GEP indexes a pointer")(static_cast <bool> (isa<PointerType>(CurTy) &&
"The first index of a GEP indexes a pointer") ? void (0) : __assert_fail
("isa<PointerType>(CurTy) && \"The first index of a GEP indexes a pointer\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3709, __extension__
__PRETTY_FUNCTION__));
3710 CurTy = GEP->getSourceElementType();
3711 FirstIter = false;
3712 } else {
3713 CurTy = GetElementPtrInst::getTypeAtIndex(CurTy, (uint64_t)0);
3714 }
3715 // For an array, add the element offset, explicitly scaled.
3716 const SCEV *ElementSize = getSizeOfExpr(IntIdxTy, CurTy);
3717 // Getelementptr indices are signed.
3718 IndexExpr = getTruncateOrSignExtend(IndexExpr, IntIdxTy);
3719
3720 // Multiply the index by the element size to compute the element offset.
3721 const SCEV *LocalOffset = getMulExpr(IndexExpr, ElementSize, OffsetWrap);
3722 Offsets.push_back(LocalOffset);
3723 }
3724 }
3725
3726 // Handle degenerate case of GEP without offsets.
3727 if (Offsets.empty())
3728 return BaseExpr;
3729
3730 // Add the offsets together, assuming nsw if inbounds.
3731 const SCEV *Offset = getAddExpr(Offsets, OffsetWrap);
3732 // Add the base address and the offset. We cannot use the nsw flag, as the
3733 // base address is unsigned. However, if we know that the offset is
3734 // non-negative, we can use nuw.
3735 SCEV::NoWrapFlags BaseWrap = AssumeInBoundsFlags && isKnownNonNegative(Offset)
3736 ? SCEV::FlagNUW : SCEV::FlagAnyWrap;
3737 auto *GEPExpr = getAddExpr(BaseExpr, Offset, BaseWrap);
3738 assert(BaseExpr->getType() == GEPExpr->getType() &&(static_cast <bool> (BaseExpr->getType() == GEPExpr->
getType() && "GEP should not change type mid-flight."
) ? void (0) : __assert_fail ("BaseExpr->getType() == GEPExpr->getType() && \"GEP should not change type mid-flight.\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3739, __extension__
__PRETTY_FUNCTION__))
3739 "GEP should not change type mid-flight.")(static_cast <bool> (BaseExpr->getType() == GEPExpr->
getType() && "GEP should not change type mid-flight."
) ? void (0) : __assert_fail ("BaseExpr->getType() == GEPExpr->getType() && \"GEP should not change type mid-flight.\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3739, __extension__
__PRETTY_FUNCTION__));
3740 return GEPExpr;
3741}
3742
3743SCEV *ScalarEvolution::findExistingSCEVInCache(SCEVTypes SCEVType,
3744 ArrayRef<const SCEV *> Ops) {
3745 FoldingSetNodeID ID;
3746 ID.AddInteger(SCEVType);
3747 for (const SCEV *Op : Ops)
3748 ID.AddPointer(Op);
3749 void *IP = nullptr;
3750 return UniqueSCEVs.FindNodeOrInsertPos(ID, IP);
3751}
3752
3753const SCEV *ScalarEvolution::getAbsExpr(const SCEV *Op, bool IsNSW) {
3754 SCEV::NoWrapFlags Flags = IsNSW ? SCEV::FlagNSW : SCEV::FlagAnyWrap;
3755 return getSMaxExpr(Op, getNegativeSCEV(Op, Flags));
3756}
3757
3758const SCEV *ScalarEvolution::getMinMaxExpr(SCEVTypes Kind,
3759 SmallVectorImpl<const SCEV *> &Ops) {
3760 assert(SCEVMinMaxExpr::isMinMaxType(Kind) && "Not a SCEVMinMaxExpr!")(static_cast <bool> (SCEVMinMaxExpr::isMinMaxType(Kind)
&& "Not a SCEVMinMaxExpr!") ? void (0) : __assert_fail
("SCEVMinMaxExpr::isMinMaxType(Kind) && \"Not a SCEVMinMaxExpr!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3760, __extension__
__PRETTY_FUNCTION__));
3761 assert(!Ops.empty() && "Cannot get empty (u|s)(min|max)!")(static_cast <bool> (!Ops.empty() && "Cannot get empty (u|s)(min|max)!"
) ? void (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty (u|s)(min|max)!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3761, __extension__
__PRETTY_FUNCTION__));
3762 if (Ops.size() == 1) return Ops[0];
3763#ifndef NDEBUG
3764 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
3765 for (unsigned i = 1, e = Ops.size(); i != e; ++i) {
3766 assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType
()) == ETy && "Operand types don't match!") ? void (0
) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"Operand types don't match!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3767, __extension__
__PRETTY_FUNCTION__))
3767 "Operand types don't match!")(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType
()) == ETy && "Operand types don't match!") ? void (0
) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"Operand types don't match!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3767, __extension__
__PRETTY_FUNCTION__));
3768 assert(Ops[0]->getType()->isPointerTy() ==(static_cast <bool> (Ops[0]->getType()->isPointerTy
() == Ops[i]->getType()->isPointerTy() && "min/max should be consistently pointerish"
) ? void (0) : __assert_fail ("Ops[0]->getType()->isPointerTy() == Ops[i]->getType()->isPointerTy() && \"min/max should be consistently pointerish\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3770, __extension__
__PRETTY_FUNCTION__))
3769 Ops[i]->getType()->isPointerTy() &&(static_cast <bool> (Ops[0]->getType()->isPointerTy
() == Ops[i]->getType()->isPointerTy() && "min/max should be consistently pointerish"
) ? void (0) : __assert_fail ("Ops[0]->getType()->isPointerTy() == Ops[i]->getType()->isPointerTy() && \"min/max should be consistently pointerish\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3770, __extension__
__PRETTY_FUNCTION__))
3770 "min/max should be consistently pointerish")(static_cast <bool> (Ops[0]->getType()->isPointerTy
() == Ops[i]->getType()->isPointerTy() && "min/max should be consistently pointerish"
) ? void (0) : __assert_fail ("Ops[0]->getType()->isPointerTy() == Ops[i]->getType()->isPointerTy() && \"min/max should be consistently pointerish\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3770, __extension__
__PRETTY_FUNCTION__));
3771 }
3772#endif
3773
3774 bool IsSigned = Kind == scSMaxExpr || Kind == scSMinExpr;
3775 bool IsMax = Kind == scSMaxExpr || Kind == scUMaxExpr;
3776
3777 // Sort by complexity, this groups all similar expression types together.
3778 GroupByComplexity(Ops, &LI, DT);
3779
3780 // Check if we have created the same expression before.
3781 if (const SCEV *S = findExistingSCEVInCache(Kind, Ops)) {
3782 return S;
3783 }
3784
3785 // If there are any constants, fold them together.
3786 unsigned Idx = 0;
3787 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
3788 ++Idx;
3789 assert(Idx < Ops.size())(static_cast <bool> (Idx < Ops.size()) ? void (0) : __assert_fail
("Idx < Ops.size()", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 3789, __extension__ __PRETTY_FUNCTION__));
3790 auto FoldOp = [&](const APInt &LHS, const APInt &RHS) {
3791 if (Kind == scSMaxExpr)
3792 return APIntOps::smax(LHS, RHS);
3793 else if (Kind == scSMinExpr)
3794 return APIntOps::smin(LHS, RHS);
3795 else if (Kind == scUMaxExpr)
3796 return APIntOps::umax(LHS, RHS);
3797 else if (Kind == scUMinExpr)
3798 return APIntOps::umin(LHS, RHS);
3799 llvm_unreachable("Unknown SCEV min/max opcode")::llvm::llvm_unreachable_internal("Unknown SCEV min/max opcode"
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3799);
3800 };
3801
3802 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
3803 // We found two constants, fold them together!
3804 ConstantInt *Fold = ConstantInt::get(
3805 getContext(), FoldOp(LHSC->getAPInt(), RHSC->getAPInt()));
3806 Ops[0] = getConstant(Fold);
3807 Ops.erase(Ops.begin()+1); // Erase the folded element
3808 if (Ops.size() == 1) return Ops[0];
3809 LHSC = cast<SCEVConstant>(Ops[0]);
3810 }
3811
3812 bool IsMinV = LHSC->getValue()->isMinValue(IsSigned);
3813 bool IsMaxV = LHSC->getValue()->isMaxValue(IsSigned);
3814
3815 if (IsMax ? IsMinV : IsMaxV) {
3816 // If we are left with a constant minimum(/maximum)-int, strip it off.
3817 Ops.erase(Ops.begin());
3818 --Idx;
3819 } else if (IsMax ? IsMaxV : IsMinV) {
3820 // If we have a max(/min) with a constant maximum(/minimum)-int,
3821 // it will always be the extremum.
3822 return LHSC;
3823 }
3824
3825 if (Ops.size() == 1) return Ops[0];
3826 }
3827
3828 // Find the first operation of the same kind
3829 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < Kind)
3830 ++Idx;
3831
3832 // Check to see if one of the operands is of the same kind. If so, expand its
3833 // operands onto our operand list, and recurse to simplify.
3834 if (Idx < Ops.size()) {
3835 bool DeletedAny = false;
3836 while (Ops[Idx]->getSCEVType() == Kind) {
3837 const SCEVMinMaxExpr *SMME = cast<SCEVMinMaxExpr>(Ops[Idx]);
3838 Ops.erase(Ops.begin()+Idx);
3839 Ops.append(SMME->op_begin(), SMME->op_end());
3840 DeletedAny = true;
3841 }
3842
3843 if (DeletedAny)
3844 return getMinMaxExpr(Kind, Ops);
3845 }
3846
3847 // Okay, check to see if the same value occurs in the operand list twice. If
3848 // so, delete one. Since we sorted the list, these values are required to
3849 // be adjacent.
3850 llvm::CmpInst::Predicate GEPred =
3851 IsSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
3852 llvm::CmpInst::Predicate LEPred =
3853 IsSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
3854 llvm::CmpInst::Predicate FirstPred = IsMax ? GEPred : LEPred;
3855 llvm::CmpInst::Predicate SecondPred = IsMax ? LEPred : GEPred;
3856 for (unsigned i = 0, e = Ops.size() - 1; i != e; ++i) {
3857 if (Ops[i] == Ops[i + 1] ||
3858 isKnownViaNonRecursiveReasoning(FirstPred, Ops[i], Ops[i + 1])) {
3859 // X op Y op Y --> X op Y
3860 // X op Y --> X, if we know X, Y are ordered appropriately
3861 Ops.erase(Ops.begin() + i + 1, Ops.begin() + i + 2);
3862 --i;
3863 --e;
3864 } else if (isKnownViaNonRecursiveReasoning(SecondPred, Ops[i],
3865 Ops[i + 1])) {
3866 // X op Y --> Y, if we know X, Y are ordered appropriately
3867 Ops.erase(Ops.begin() + i, Ops.begin() + i + 1);
3868 --i;
3869 --e;
3870 }
3871 }
3872
3873 if (Ops.size() == 1) return Ops[0];
3874
3875 assert(!Ops.empty() && "Reduced smax down to nothing!")(static_cast <bool> (!Ops.empty() && "Reduced smax down to nothing!"
) ? void (0) : __assert_fail ("!Ops.empty() && \"Reduced smax down to nothing!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3875, __extension__
__PRETTY_FUNCTION__));
3876
3877 // Okay, it looks like we really DO need an expr. Check to see if we
3878 // already have one, otherwise create a new one.
3879 FoldingSetNodeID ID;
3880 ID.AddInteger(Kind);
3881 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3882 ID.AddPointer(Ops[i]);
3883 void *IP = nullptr;
3884 const SCEV *ExistingSCEV = UniqueSCEVs.FindNodeOrInsertPos(ID, IP);
3885 if (ExistingSCEV)
3886 return ExistingSCEV;
3887 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
3888 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
3889 SCEV *S = new (SCEVAllocator)
3890 SCEVMinMaxExpr(ID.Intern(SCEVAllocator), Kind, O, Ops.size());
3891
3892 UniqueSCEVs.InsertNode(S, IP);
3893 registerUser(S, Ops);
3894 return S;
3895}
3896
3897namespace {
3898
3899class SCEVSequentialMinMaxDeduplicatingVisitor final
3900 : public SCEVVisitor<SCEVSequentialMinMaxDeduplicatingVisitor,
3901 Optional<const SCEV *>> {
3902 using RetVal = Optional<const SCEV *>;
3903 using Base = SCEVVisitor<SCEVSequentialMinMaxDeduplicatingVisitor, RetVal>;
3904
3905 ScalarEvolution &SE;
3906 const SCEVTypes RootKind; // Must be a sequential min/max expression.
3907 const SCEVTypes NonSequentialRootKind; // Non-sequential variant of RootKind.
3908 SmallPtrSet<const SCEV *, 16> SeenOps;
3909
3910 bool canRecurseInto(SCEVTypes Kind) const {
3911 // We can only recurse into the SCEV expression of the same effective type
3912 // as the type of our root SCEV expression.
3913 return RootKind == Kind || NonSequentialRootKind == Kind;
3914 };
3915
3916 RetVal visitAnyMinMaxExpr(const SCEV *S) {
3917 assert((isa<SCEVMinMaxExpr>(S) || isa<SCEVSequentialMinMaxExpr>(S)) &&(static_cast <bool> ((isa<SCEVMinMaxExpr>(S) || isa
<SCEVSequentialMinMaxExpr>(S)) && "Only for min/max expressions."
) ? void (0) : __assert_fail ("(isa<SCEVMinMaxExpr>(S) || isa<SCEVSequentialMinMaxExpr>(S)) && \"Only for min/max expressions.\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3918, __extension__
__PRETTY_FUNCTION__))
3918 "Only for min/max expressions.")(static_cast <bool> ((isa<SCEVMinMaxExpr>(S) || isa
<SCEVSequentialMinMaxExpr>(S)) && "Only for min/max expressions."
) ? void (0) : __assert_fail ("(isa<SCEVMinMaxExpr>(S) || isa<SCEVSequentialMinMaxExpr>(S)) && \"Only for min/max expressions.\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 3918, __extension__
__PRETTY_FUNCTION__));
3919 SCEVTypes Kind = S->getSCEVType();
3920
3921 if (!canRecurseInto(Kind))
3922 return S;
3923
3924 auto *NAry = cast<SCEVNAryExpr>(S);
3925 SmallVector<const SCEV *> NewOps;
3926 bool Changed =
3927 visit(Kind, makeArrayRef(NAry->op_begin(), NAry->op_end()), NewOps);
3928
3929 if (!Changed)
3930 return S;
3931 if (NewOps.empty())
3932 return None;
3933
3934 return isa<SCEVSequentialMinMaxExpr>(S)
3935 ? SE.getSequentialMinMaxExpr(Kind, NewOps)
3936 : SE.getMinMaxExpr(Kind, NewOps);
3937 }
3938
3939 RetVal visit(const SCEV *S) {
3940 // Has the whole operand been seen already?
3941 if (!SeenOps.insert(S).second)
3942 return None;
3943 return Base::visit(S);
3944 }
3945
3946public:
3947 SCEVSequentialMinMaxDeduplicatingVisitor(ScalarEvolution &SE,
3948 SCEVTypes RootKind)
3949 : SE(SE), RootKind(RootKind),
3950 NonSequentialRootKind(
3951 SCEVSequentialMinMaxExpr::getEquivalentNonSequentialSCEVType(
3952 RootKind)) {}
3953
3954 bool /*Changed*/ visit(SCEVTypes Kind, ArrayRef<const SCEV *> OrigOps,
3955 SmallVectorImpl<const SCEV *> &NewOps) {
3956 bool Changed = false;
3957 SmallVector<const SCEV *> Ops;
3958 Ops.reserve(OrigOps.size());
3959
3960 for (const SCEV *Op : OrigOps) {
3961 RetVal NewOp = visit(Op);
3962 if (NewOp != Op)
3963 Changed = true;
3964 if (NewOp)
3965 Ops.emplace_back(*NewOp);
3966 }
3967
3968 if (Changed)
3969 NewOps = std::move(Ops);
3970 return Changed;
3971 }
3972
3973 RetVal visitConstant(const SCEVConstant *Constant) { return Constant; }
3974
3975 RetVal visitPtrToIntExpr(const SCEVPtrToIntExpr *Expr) { return Expr; }
3976
3977 RetVal visitTruncateExpr(const SCEVTruncateExpr *Expr) { return Expr; }
3978
3979 RetVal visitZeroExtendExpr(const SCEVZeroExtendExpr *Expr) { return Expr; }
3980
3981 RetVal visitSignExtendExpr(const SCEVSignExtendExpr *Expr) { return Expr; }
3982
3983 RetVal visitAddExpr(const SCEVAddExpr *Expr) { return Expr; }
3984
3985 RetVal visitMulExpr(const SCEVMulExpr *Expr) { return Expr; }
3986
3987 RetVal visitUDivExpr(const SCEVUDivExpr *Expr) { return Expr; }
3988
3989 RetVal visitAddRecExpr(const SCEVAddRecExpr *Expr) { return Expr; }
3990
3991 RetVal visitSMaxExpr(const SCEVSMaxExpr *Expr) {
3992 return visitAnyMinMaxExpr(Expr);
3993 }
3994
3995 RetVal visitUMaxExpr(const SCEVUMaxExpr *Expr) {
3996 return visitAnyMinMaxExpr(Expr);
3997 }
3998
3999 RetVal visitSMinExpr(const SCEVSMinExpr *Expr) {
4000 return visitAnyMinMaxExpr(Expr);
4001 }
4002
4003 RetVal visitUMinExpr(const SCEVUMinExpr *Expr) {
4004 return visitAnyMinMaxExpr(Expr);
4005 }
4006
4007 RetVal visitSequentialUMinExpr(const SCEVSequentialUMinExpr *Expr) {
4008 return visitAnyMinMaxExpr(Expr);
4009 }
4010
4011 RetVal visitUnknown(const SCEVUnknown *Expr) { return Expr; }
4012
4013 RetVal visitCouldNotCompute(const SCEVCouldNotCompute *Expr) { return Expr; }
4014};
4015
4016} // namespace
4017
4018const SCEV *
4019ScalarEvolution::getSequentialMinMaxExpr(SCEVTypes Kind,
4020 SmallVectorImpl<const SCEV *> &Ops) {
4021 assert(SCEVSequentialMinMaxExpr::isSequentialMinMaxType(Kind) &&(static_cast <bool> (SCEVSequentialMinMaxExpr::isSequentialMinMaxType
(Kind) && "Not a SCEVSequentialMinMaxExpr!") ? void (
0) : __assert_fail ("SCEVSequentialMinMaxExpr::isSequentialMinMaxType(Kind) && \"Not a SCEVSequentialMinMaxExpr!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4022, __extension__
__PRETTY_FUNCTION__))
4022 "Not a SCEVSequentialMinMaxExpr!")(static_cast <bool> (SCEVSequentialMinMaxExpr::isSequentialMinMaxType
(Kind) && "Not a SCEVSequentialMinMaxExpr!") ? void (
0) : __assert_fail ("SCEVSequentialMinMaxExpr::isSequentialMinMaxType(Kind) && \"Not a SCEVSequentialMinMaxExpr!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4022, __extension__
__PRETTY_FUNCTION__));
4023 assert(!Ops.empty() && "Cannot get empty (u|s)(min|max)!")(static_cast <bool> (!Ops.empty() && "Cannot get empty (u|s)(min|max)!"
) ? void (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty (u|s)(min|max)!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4023, __extension__
__PRETTY_FUNCTION__));
4024 if (Ops.size() == 1)
4025 return Ops[0];
4026 if (Ops.size() == 2 &&
4027 any_of(Ops, [](const SCEV *Op) { return isa<SCEVConstant>(Op); }))
4028 return getMinMaxExpr(
4029 SCEVSequentialMinMaxExpr::getEquivalentNonSequentialSCEVType(Kind),
4030 Ops);
4031#ifndef NDEBUG
4032 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
4033 for (unsigned i = 1, e = Ops.size(); i != e; ++i) {
4034 assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType
()) == ETy && "Operand types don't match!") ? void (0
) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"Operand types don't match!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4035, __extension__
__PRETTY_FUNCTION__))
4035 "Operand types don't match!")(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType
()) == ETy && "Operand types don't match!") ? void (0
) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"Operand types don't match!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4035, __extension__
__PRETTY_FUNCTION__));
4036 assert(Ops[0]->getType()->isPointerTy() ==(static_cast <bool> (Ops[0]->getType()->isPointerTy
() == Ops[i]->getType()->isPointerTy() && "min/max should be consistently pointerish"
) ? void (0) : __assert_fail ("Ops[0]->getType()->isPointerTy() == Ops[i]->getType()->isPointerTy() && \"min/max should be consistently pointerish\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4038, __extension__
__PRETTY_FUNCTION__))
4037 Ops[i]->getType()->isPointerTy() &&(static_cast <bool> (Ops[0]->getType()->isPointerTy
() == Ops[i]->getType()->isPointerTy() && "min/max should be consistently pointerish"
) ? void (0) : __assert_fail ("Ops[0]->getType()->isPointerTy() == Ops[i]->getType()->isPointerTy() && \"min/max should be consistently pointerish\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4038, __extension__
__PRETTY_FUNCTION__))
4038 "min/max should be consistently pointerish")(static_cast <bool> (Ops[0]->getType()->isPointerTy
() == Ops[i]->getType()->isPointerTy() && "min/max should be consistently pointerish"
) ? void (0) : __assert_fail ("Ops[0]->getType()->isPointerTy() == Ops[i]->getType()->isPointerTy() && \"min/max should be consistently pointerish\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4038, __extension__
__PRETTY_FUNCTION__));
4039 }
4040#endif
4041
4042 // Note that SCEVSequentialMinMaxExpr is *NOT* commutative,
4043 // so we can *NOT* do any kind of sorting of the expressions!
4044
4045 // Check if we have created the same expression before.
4046 if (const SCEV *S = findExistingSCEVInCache(Kind, Ops))
4047 return S;
4048
4049 // FIXME: there are *some* simplifications that we can do here.
4050
4051 // Keep only the first instance of an operand.
4052 {
4053 SCEVSequentialMinMaxDeduplicatingVisitor Deduplicator(*this, Kind);
4054 bool Changed = Deduplicator.visit(Kind, Ops, Ops);
4055 if (Changed)
4056 return getSequentialMinMaxExpr(Kind, Ops);
4057 }
4058
4059 // Check to see if one of the operands is of the same kind. If so, expand its
4060 // operands onto our operand list, and recurse to simplify.
4061 {
4062 unsigned Idx = 0;
4063 bool DeletedAny = false;
4064 while (Idx < Ops.size()) {
4065 if (Ops[Idx]->getSCEVType() != Kind) {
4066 ++Idx;
4067 continue;
4068 }
4069 const auto *SMME = cast<SCEVSequentialMinMaxExpr>(Ops[Idx]);
4070 Ops.erase(Ops.begin() + Idx);
4071 Ops.insert(Ops.begin() + Idx, SMME->op_begin(), SMME->op_end());
4072 DeletedAny = true;
4073 }
4074
4075 if (DeletedAny)
4076 return getSequentialMinMaxExpr(Kind, Ops);
4077 }
4078
4079 // Okay, it looks like we really DO need an expr. Check to see if we
4080 // already have one, otherwise create a new one.
4081 FoldingSetNodeID ID;
4082 ID.AddInteger(Kind);
4083 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
4084 ID.AddPointer(Ops[i]);
4085 void *IP = nullptr;
4086 const SCEV *ExistingSCEV = UniqueSCEVs.FindNodeOrInsertPos(ID, IP);
4087 if (ExistingSCEV)
4088 return ExistingSCEV;
4089
4090 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
4091 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
4092 SCEV *S = new (SCEVAllocator)
4093 SCEVSequentialMinMaxExpr(ID.Intern(SCEVAllocator), Kind, O, Ops.size());
4094
4095 UniqueSCEVs.InsertNode(S, IP);
4096 registerUser(S, Ops);
4097 return S;
4098}
4099
4100const SCEV *ScalarEvolution::getSMaxExpr(const SCEV *LHS, const SCEV *RHS) {
4101 SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
4102 return getSMaxExpr(Ops);
4103}
4104
4105const SCEV *ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
4106 return getMinMaxExpr(scSMaxExpr, Ops);
4107}
4108
4109const SCEV *ScalarEvolution::getUMaxExpr(const SCEV *LHS, const SCEV *RHS) {
4110 SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
4111 return getUMaxExpr(Ops);
4112}
4113
4114const SCEV *ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
4115 return getMinMaxExpr(scUMaxExpr, Ops);
4116}
4117
4118const SCEV *ScalarEvolution::getSMinExpr(const SCEV *LHS,
4119 const SCEV *RHS) {
4120 SmallVector<const SCEV *, 2> Ops = { LHS, RHS };
4121 return getSMinExpr(Ops);
4122}
4123
4124const SCEV *ScalarEvolution::getSMinExpr(SmallVectorImpl<const SCEV *> &Ops) {
4125 return getMinMaxExpr(scSMinExpr, Ops);
4126}
4127
4128const SCEV *ScalarEvolution::getUMinExpr(const SCEV *LHS, const SCEV *RHS,
4129 bool Sequential) {
4130 SmallVector<const SCEV *, 2> Ops = { LHS, RHS };
4131 return getUMinExpr(Ops, Sequential);
4132}
4133
4134const SCEV *ScalarEvolution::getUMinExpr(SmallVectorImpl<const SCEV *> &Ops,
4135 bool Sequential) {
4136 return Sequential ? getSequentialMinMaxExpr(scSequentialUMinExpr, Ops)
4137 : getMinMaxExpr(scUMinExpr, Ops);
4138}
4139
4140const SCEV *
4141ScalarEvolution::getSizeOfScalableVectorExpr(Type *IntTy,
4142 ScalableVectorType *ScalableTy) {
4143 Constant *NullPtr = Constant::getNullValue(ScalableTy->getPointerTo());
4144 Constant *One = ConstantInt::get(IntTy, 1);
4145 Constant *GEP = ConstantExpr::getGetElementPtr(ScalableTy, NullPtr, One);
4146 // Note that the expression we created is the final expression, we don't
4147 // want to simplify it any further Also, if we call a normal getSCEV(),
4148 // we'll end up in an endless recursion. So just create an SCEVUnknown.
4149 return getUnknown(ConstantExpr::getPtrToInt(GEP, IntTy));
4150}
4151
4152const SCEV *ScalarEvolution::getSizeOfExpr(Type *IntTy, Type *AllocTy) {
4153 if (auto *ScalableAllocTy = dyn_cast<ScalableVectorType>(AllocTy))
4154 return getSizeOfScalableVectorExpr(IntTy, ScalableAllocTy);
4155 // We can bypass creating a target-independent constant expression and then
4156 // folding it back into a ConstantInt. This is just a compile-time
4157 // optimization.
4158 return getConstant(IntTy, getDataLayout().getTypeAllocSize(AllocTy));
4159}
4160
4161const SCEV *ScalarEvolution::getStoreSizeOfExpr(Type *IntTy, Type *StoreTy) {
4162 if (auto *ScalableStoreTy = dyn_cast<ScalableVectorType>(StoreTy))
4163 return getSizeOfScalableVectorExpr(IntTy, ScalableStoreTy);
4164 // We can bypass creating a target-independent constant expression and then
4165 // folding it back into a ConstantInt. This is just a compile-time
4166 // optimization.
4167 return getConstant(IntTy, getDataLayout().getTypeStoreSize(StoreTy));
4168}
4169
4170const SCEV *ScalarEvolution::getOffsetOfExpr(Type *IntTy,
4171 StructType *STy,
4172 unsigned FieldNo) {
4173 // We can bypass creating a target-independent constant expression and then
4174 // folding it back into a ConstantInt. This is just a compile-time
4175 // optimization.
4176 return getConstant(
4177 IntTy, getDataLayout().getStructLayout(STy)->getElementOffset(FieldNo));
4178}
4179
4180const SCEV *ScalarEvolution::getUnknown(Value *V) {
4181 // Don't attempt to do anything other than create a SCEVUnknown object
4182 // here. createSCEV only calls getUnknown after checking for all other
4183 // interesting possibilities, and any other code that calls getUnknown
4184 // is doing so in order to hide a value from SCEV canonicalization.
4185
4186 FoldingSetNodeID ID;
4187 ID.AddInteger(scUnknown);
4188 ID.AddPointer(V);
4189 void *IP = nullptr;
4190 if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) {
4191 assert(cast<SCEVUnknown>(S)->getValue() == V &&(static_cast <bool> (cast<SCEVUnknown>(S)->getValue
() == V && "Stale SCEVUnknown in uniquing map!") ? void
(0) : __assert_fail ("cast<SCEVUnknown>(S)->getValue() == V && \"Stale SCEVUnknown in uniquing map!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4192, __extension__
__PRETTY_FUNCTION__))
4192 "Stale SCEVUnknown in uniquing map!")(static_cast <bool> (cast<SCEVUnknown>(S)->getValue
() == V && "Stale SCEVUnknown in uniquing map!") ? void
(0) : __assert_fail ("cast<SCEVUnknown>(S)->getValue() == V && \"Stale SCEVUnknown in uniquing map!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4192, __extension__
__PRETTY_FUNCTION__));
4193 return S;
4194 }
4195 SCEV *S = new (SCEVAllocator) SCEVUnknown(ID.Intern(SCEVAllocator), V, this,
4196 FirstUnknown);
4197 FirstUnknown = cast<SCEVUnknown>(S);
4198 UniqueSCEVs.InsertNode(S, IP);
4199 return S;
4200}
4201
4202//===----------------------------------------------------------------------===//
4203// Basic SCEV Analysis and PHI Idiom Recognition Code
4204//
4205
4206/// Test if values of the given type are analyzable within the SCEV
4207/// framework. This primarily includes integer types, and it can optionally
4208/// include pointer types if the ScalarEvolution class has access to
4209/// target-specific information.
4210bool ScalarEvolution::isSCEVable(Type *Ty) const {
4211 // Integers and pointers are always SCEVable.
4212 return Ty->isIntOrPtrTy();
4213}
4214
4215/// Return the size in bits of the specified type, for which isSCEVable must
4216/// return true.
4217uint64_t ScalarEvolution::getTypeSizeInBits(Type *Ty) const {
4218 assert(isSCEVable(Ty) && "Type is not SCEVable!")(static_cast <bool> (isSCEVable(Ty) && "Type is not SCEVable!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"Type is not SCEVable!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4218, __extension__
__PRETTY_FUNCTION__));
4219 if (Ty->isPointerTy())
4220 return getDataLayout().getIndexTypeSizeInBits(Ty);
4221 return getDataLayout().getTypeSizeInBits(Ty);
4222}
4223
4224/// Return a type with the same bitwidth as the given type and which represents
4225/// how SCEV will treat the given type, for which isSCEVable must return
4226/// true. For pointer types, this is the pointer index sized integer type.
4227Type *ScalarEvolution::getEffectiveSCEVType(Type *Ty) const {
4228 assert(isSCEVable(Ty) && "Type is not SCEVable!")(static_cast <bool> (isSCEVable(Ty) && "Type is not SCEVable!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"Type is not SCEVable!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4228, __extension__
__PRETTY_FUNCTION__));
4229
4230 if (Ty->isIntegerTy())
4231 return Ty;
4232
4233 // The only other support type is pointer.
4234 assert(Ty->isPointerTy() && "Unexpected non-pointer non-integer type!")(static_cast <bool> (Ty->isPointerTy() && "Unexpected non-pointer non-integer type!"
) ? void (0) : __assert_fail ("Ty->isPointerTy() && \"Unexpected non-pointer non-integer type!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4234, __extension__
__PRETTY_FUNCTION__));
4235 return getDataLayout().getIndexType(Ty);
4236}
4237
4238Type *ScalarEvolution::getWiderType(Type *T1, Type *T2) const {
4239 return getTypeSizeInBits(T1) >= getTypeSizeInBits(T2) ? T1 : T2;
4240}
4241
4242bool ScalarEvolution::instructionCouldExistWitthOperands(const SCEV *A,
4243 const SCEV *B) {
4244 /// For a valid use point to exist, the defining scope of one operand
4245 /// must dominate the other.
4246 bool PreciseA, PreciseB;
4247 auto *ScopeA = getDefiningScopeBound({A}, PreciseA);
4248 auto *ScopeB = getDefiningScopeBound({B}, PreciseB);
4249 if (!PreciseA || !PreciseB)
4250 // Can't tell.
4251 return false;
4252 return (ScopeA == ScopeB) || DT.dominates(ScopeA, ScopeB) ||
4253 DT.dominates(ScopeB, ScopeA);
4254}
4255
4256
4257const SCEV *ScalarEvolution::getCouldNotCompute() {
4258 return CouldNotCompute.get();
4259}
4260
4261bool ScalarEvolution::checkValidity(const SCEV *S) const {
4262 bool ContainsNulls = SCEVExprContains(S, [](const SCEV *S) {
4263 auto *SU = dyn_cast<SCEVUnknown>(S);
4264 return SU && SU->getValue() == nullptr;
4265 });
4266
4267 return !ContainsNulls;
4268}
4269
4270bool ScalarEvolution::containsAddRecurrence(const SCEV *S) {
4271 HasRecMapType::iterator I = HasRecMap.find(S);
4272 if (I != HasRecMap.end())
4273 return I->second;
4274
4275 bool FoundAddRec =
4276 SCEVExprContains(S, [](const SCEV *S) { return isa<SCEVAddRecExpr>(S); });
4277 HasRecMap.insert({S, FoundAddRec});
4278 return FoundAddRec;
4279}
4280
4281/// Return the ValueOffsetPair set for \p S. \p S can be represented
4282/// by the value and offset from any ValueOffsetPair in the set.
4283ArrayRef<Value *> ScalarEvolution::getSCEVValues(const SCEV *S) {
4284 ExprValueMapType::iterator SI = ExprValueMap.find_as(S);
4285 if (SI == ExprValueMap.end())
4286 return None;
4287#ifndef NDEBUG
4288 if (VerifySCEVMap) {
4289 // Check there is no dangling Value in the set returned.
4290 for (Value *V : SI->second)
4291 assert(ValueExprMap.count(V))(static_cast <bool> (ValueExprMap.count(V)) ? void (0) :
__assert_fail ("ValueExprMap.count(V)", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 4291, __extension__ __PRETTY_FUNCTION__));
4292 }
4293#endif
4294 return SI->second.getArrayRef();
4295}
4296
4297/// Erase Value from ValueExprMap and ExprValueMap. ValueExprMap.erase(V)
4298/// cannot be used separately. eraseValueFromMap should be used to remove
4299/// V from ValueExprMap and ExprValueMap at the same time.
4300void ScalarEvolution::eraseValueFromMap(Value *V) {
4301 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
4302 if (I != ValueExprMap.end()) {
4303 auto EVIt = ExprValueMap.find(I->second);
4304 bool Removed = EVIt->second.remove(V);
4305 (void) Removed;
4306 assert(Removed && "Value not in ExprValueMap?")(static_cast <bool> (Removed && "Value not in ExprValueMap?"
) ? void (0) : __assert_fail ("Removed && \"Value not in ExprValueMap?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4306, __extension__
__PRETTY_FUNCTION__));
4307 ValueExprMap.erase(I);
4308 }
4309}
4310
4311void ScalarEvolution::insertValueToMap(Value *V, const SCEV *S) {
4312 // A recursive query may have already computed the SCEV. It should be
4313 // equivalent, but may not necessarily be exactly the same, e.g. due to lazily
4314 // inferred nowrap flags.
4315 auto It = ValueExprMap.find_as(V);
4316 if (It == ValueExprMap.end()) {
4317 ValueExprMap.insert({SCEVCallbackVH(V, this), S});
4318 ExprValueMap[S].insert(V);
4319 }
4320}
4321
4322/// Return an existing SCEV if it exists, otherwise analyze the expression and
4323/// create a new one.
4324const SCEV *ScalarEvolution::getSCEV(Value *V) {
4325 assert(isSCEVable(V->getType()) && "Value is not SCEVable!")(static_cast <bool> (isSCEVable(V->getType()) &&
"Value is not SCEVable!") ? void (0) : __assert_fail ("isSCEVable(V->getType()) && \"Value is not SCEVable!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4325, __extension__
__PRETTY_FUNCTION__));
4326
4327 const SCEV *S = getExistingSCEV(V);
4328 if (S == nullptr) {
4329 S = createSCEV(V);
4330 // During PHI resolution, it is possible to create two SCEVs for the same
4331 // V, so it is needed to double check whether V->S is inserted into
4332 // ValueExprMap before insert S->{V, 0} into ExprValueMap.
4333 std::pair<ValueExprMapType::iterator, bool> Pair =
4334 ValueExprMap.insert({SCEVCallbackVH(V, this), S});
4335 if (Pair.second)
4336 ExprValueMap[S].insert(V);
4337 }
4338 return S;
4339}
4340
4341const SCEV *ScalarEvolution::getExistingSCEV(Value *V) {
4342 assert(isSCEVable(V->getType()) && "Value is not SCEVable!")(static_cast <bool> (isSCEVable(V->getType()) &&
"Value is not SCEVable!") ? void (0) : __assert_fail ("isSCEVable(V->getType()) && \"Value is not SCEVable!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4342, __extension__
__PRETTY_FUNCTION__));
4343
4344 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
4345 if (I != ValueExprMap.end()) {
4346 const SCEV *S = I->second;
4347 assert(checkValidity(S) &&(static_cast <bool> (checkValidity(S) && "existing SCEV has not been properly invalidated"
) ? void (0) : __assert_fail ("checkValidity(S) && \"existing SCEV has not been properly invalidated\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4348, __extension__
__PRETTY_FUNCTION__))
4348 "existing SCEV has not been properly invalidated")(static_cast <bool> (checkValidity(S) && "existing SCEV has not been properly invalidated"
) ? void (0) : __assert_fail ("checkValidity(S) && \"existing SCEV has not been properly invalidated\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4348, __extension__
__PRETTY_FUNCTION__));
4349 return S;
4350 }
4351 return nullptr;
4352}
4353
4354/// Return a SCEV corresponding to -V = -1*V
4355const SCEV *ScalarEvolution::getNegativeSCEV(const SCEV *V,
4356 SCEV::NoWrapFlags Flags) {
4357 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
4358 return getConstant(
4359 cast<ConstantInt>(ConstantExpr::getNeg(VC->getValue())));
4360
4361 Type *Ty = V->getType();
4362 Ty = getEffectiveSCEVType(Ty);
4363 return getMulExpr(V, getMinusOne(Ty), Flags);
4364}
4365
4366/// If Expr computes ~A, return A else return nullptr
4367static const SCEV *MatchNotExpr(const SCEV *Expr) {
4368 const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Expr);
4369 if (!Add || Add->getNumOperands() != 2 ||
4370 !Add->getOperand(0)->isAllOnesValue())
4371 return nullptr;
4372
4373 const SCEVMulExpr *AddRHS = dyn_cast<SCEVMulExpr>(Add->getOperand(1));
4374 if (!AddRHS || AddRHS->getNumOperands() != 2 ||
4375 !AddRHS->getOperand(0)->isAllOnesValue())
4376 return nullptr;
4377
4378 return AddRHS->getOperand(1);
4379}
4380
4381/// Return a SCEV corresponding to ~V = -1-V
4382const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) {
4383 assert(!V->getType()->isPointerTy() && "Can't negate pointer")(static_cast <bool> (!V->getType()->isPointerTy()
&& "Can't negate pointer") ? void (0) : __assert_fail
("!V->getType()->isPointerTy() && \"Can't negate pointer\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4383, __extension__
__PRETTY_FUNCTION__));
4384
4385 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
4386 return getConstant(
4387 cast<ConstantInt>(ConstantExpr::getNot(VC->getValue())));
4388
4389 // Fold ~(u|s)(min|max)(~x, ~y) to (u|s)(max|min)(x, y)
4390 if (const SCEVMinMaxExpr *MME = dyn_cast<SCEVMinMaxExpr>(V)) {
4391 auto MatchMinMaxNegation = [&](const SCEVMinMaxExpr *MME) {
4392 SmallVector<const SCEV *, 2> MatchedOperands;
4393 for (const SCEV *Operand : MME->operands()) {
4394 const SCEV *Matched = MatchNotExpr(Operand);
4395 if (!Matched)
4396 return (const SCEV *)nullptr;
4397 MatchedOperands.push_back(Matched);
4398 }
4399 return getMinMaxExpr(SCEVMinMaxExpr::negate(MME->getSCEVType()),
4400 MatchedOperands);
4401 };
4402 if (const SCEV *Replaced = MatchMinMaxNegation(MME))
4403 return Replaced;
4404 }
4405
4406 Type *Ty = V->getType();
4407 Ty = getEffectiveSCEVType(Ty);
4408 return getMinusSCEV(getMinusOne(Ty), V);
4409}
4410
4411const SCEV *ScalarEvolution::removePointerBase(const SCEV *P) {
4412 assert(P->getType()->isPointerTy())(static_cast <bool> (P->getType()->isPointerTy())
? void (0) : __assert_fail ("P->getType()->isPointerTy()"
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4412, __extension__
__PRETTY_FUNCTION__));
23
←
'?' condition is true
→
4413
4414 if (auto *AddRec
24.1
'AddRec' is null
 = dyn_cast<SCEVAddRecExpr>(P)) {
24
←
Assuming 'P' is not a 'SCEVAddRecExpr'
→
25
←
Taking false branch
→
4415 // The base of an AddRec is the first operand.
4416 SmallVector<const SCEV *> Ops{AddRec->operands()};
4417 Ops[0] = removePointerBase(Ops[0]);
4418 // Don't try to transfer nowrap flags for now. We could in some cases
4419 // (for example, if pointer operand of the AddRec is a SCEVUnknown).
4420 return getAddRecExpr(Ops, AddRec->getLoop(), SCEV::FlagAnyWrap);
4421 }
4422 if (auto *Add
26.1
'Add' is non-null
 = dyn_cast<SCEVAddExpr>(P)) {
26
←
Assuming 'P' is a 'SCEVAddExpr'
→
27
←
Taking true branch
→
4423 // The base of an Add is the pointer operand.
4424 SmallVector<const SCEV *> Ops{Add->operands()};
4425 const SCEV **PtrOp = nullptr;
28
←
'PtrOp' initialized to a null pointer value
→
4426 for (const SCEV *&AddOp : Ops) {
29
←
Assuming '__begin2' is equal to '__end2'
→
4427 if (AddOp->getType()->isPointerTy()) {
4428 assert(!PtrOp && "Cannot have multiple pointer ops")(static_cast <bool> (!PtrOp && "Cannot have multiple pointer ops"
) ? void (0) : __assert_fail ("!PtrOp && \"Cannot have multiple pointer ops\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4428, __extension__
__PRETTY_FUNCTION__));
4429 PtrOp = &AddOp;
4430 }
4431 }
4432 *PtrOp = removePointerBase(*PtrOp);
30
←
Dereference of null pointer (loaded from variable 'PtrOp')
4433 // Don't try to transfer nowrap flags for now. We could in some cases
4434 // (for example, if the pointer operand of the Add is a SCEVUnknown).
4435 return getAddExpr(Ops);
4436 }
4437 // Any other expression must be a pointer base.
4438 return getZero(P->getType());
4439}
4440
4441const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS, const SCEV *RHS,
4442 SCEV::NoWrapFlags Flags,
4443 unsigned Depth) {
4444 // Fast path: X - X --> 0.
4445 if (LHS == RHS)
18
←
Assuming 'LHS' is not equal to 'RHS'
→
19
←
Taking false branch
→
4446 return getZero(LHS->getType());
4447
4448 // If we subtract two pointers with different pointer bases, bail.
4449 // Eventually, we're going to add an assertion to getMulExpr that we
4450 // can't multiply by a pointer.
4451 if (RHS->getType()->isPointerTy()) {
4452 if (!LHS->getType()->isPointerTy() ||
21
←
Taking false branch
→
4453 getPointerBase(LHS) != getPointerBase(RHS))
20
←
Assuming the condition is false
→
4454 return getCouldNotCompute();
4455 LHS = removePointerBase(LHS);
22
←
Calling 'ScalarEvolution::removePointerBase'
→
4456 RHS = removePointerBase(RHS);
4457 }
4458
4459 // We represent LHS - RHS as LHS + (-1)*RHS. This transformation
4460 // makes it so that we cannot make much use of NUW.
4461 auto AddFlags = SCEV::FlagAnyWrap;
4462 const bool RHSIsNotMinSigned =
4463 !getSignedRangeMin(RHS).isMinSignedValue();
4464 if (hasFlags(Flags, SCEV::FlagNSW)) {
4465 // Let M be the minimum representable signed value. Then (-1)*RHS
4466 // signed-wraps if and only if RHS is M. That can happen even for
4467 // a NSW subtraction because e.g. (-1)*M signed-wraps even though
4468 // -1 - M does not. So to transfer NSW from LHS - RHS to LHS +
4469 // (-1)*RHS, we need to prove that RHS != M.
4470 //
4471 // If LHS is non-negative and we know that LHS - RHS does not
4472 // signed-wrap, then RHS cannot be M. So we can rule out signed-wrap
4473 // either by proving that RHS > M or that LHS >= 0.
4474 if (RHSIsNotMinSigned || isKnownNonNegative(LHS)) {
4475 AddFlags = SCEV::FlagNSW;
4476 }
4477 }
4478
4479 // FIXME: Find a correct way to transfer NSW to (-1)*M when LHS -
4480 // RHS is NSW and LHS >= 0.
4481 //
4482 // The difficulty here is that the NSW flag may have been proven
4483 // relative to a loop that is to be found in a recurrence in LHS and
4484 // not in RHS. Applying NSW to (-1)*M may then let the NSW have a
4485 // larger scope than intended.
4486 auto NegFlags = RHSIsNotMinSigned ? SCEV::FlagNSW : SCEV::FlagAnyWrap;
4487
4488 return getAddExpr(LHS, getNegativeSCEV(RHS, NegFlags), AddFlags, Depth);
4489}
4490
4491const SCEV *ScalarEvolution::getTruncateOrZeroExtend(const SCEV *V, Type *Ty,
4492 unsigned Depth) {
4493 Type *SrcTy = V->getType();
4494 assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&(static_cast <bool> (SrcTy->isIntOrPtrTy() &&
Ty->isIntOrPtrTy() && "Cannot truncate or zero extend with non-integer arguments!"
) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4495, __extension__
__PRETTY_FUNCTION__))
4495 "Cannot truncate or zero extend with non-integer arguments!")(static_cast <bool> (SrcTy->isIntOrPtrTy() &&
Ty->isIntOrPtrTy() && "Cannot truncate or zero extend with non-integer arguments!"
) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4495, __extension__
__PRETTY_FUNCTION__));
4496 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4497 return V; // No conversion
4498 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
4499 return getTruncateExpr(V, Ty, Depth);
4500 return getZeroExtendExpr(V, Ty, Depth);
4501}
4502
4503const SCEV *ScalarEvolution::getTruncateOrSignExtend(const SCEV *V, Type *Ty,
4504 unsigned Depth) {
4505 Type *SrcTy = V->getType();
4506 assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&(static_cast <bool> (SrcTy->isIntOrPtrTy() &&
Ty->isIntOrPtrTy() && "Cannot truncate or zero extend with non-integer arguments!"
) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4507, __extension__
__PRETTY_FUNCTION__))
4507 "Cannot truncate or zero extend with non-integer arguments!")(static_cast <bool> (SrcTy->isIntOrPtrTy() &&
Ty->isIntOrPtrTy() && "Cannot truncate or zero extend with non-integer arguments!"
) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4507, __extension__
__PRETTY_FUNCTION__));
4508 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4509 return V; // No conversion
4510 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
4511 return getTruncateExpr(V, Ty, Depth);
4512 return getSignExtendExpr(V, Ty, Depth);
4513}
4514
4515const SCEV *
4516ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, Type *Ty) {
4517 Type *SrcTy = V->getType();
4518 assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&(static_cast <bool> (SrcTy->isIntOrPtrTy() &&
Ty->isIntOrPtrTy() && "Cannot noop or zero extend with non-integer arguments!"
) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or zero extend with non-integer arguments!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4519, __extension__
__PRETTY_FUNCTION__))
4519 "Cannot noop or zero extend with non-integer arguments!")(static_cast <bool> (SrcTy->isIntOrPtrTy() &&
Ty->isIntOrPtrTy() && "Cannot noop or zero extend with non-integer arguments!"
) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or zero extend with non-integer arguments!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4519, __extension__
__PRETTY_FUNCTION__));
4520 assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(SrcTy) <= getTypeSizeInBits
(Ty) && "getNoopOrZeroExtend cannot truncate!") ? void
(0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrZeroExtend cannot truncate!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4521, __extension__
__PRETTY_FUNCTION__))
4521 "getNoopOrZeroExtend cannot truncate!")(static_cast <bool> (getTypeSizeInBits(SrcTy) <= getTypeSizeInBits
(Ty) && "getNoopOrZeroExtend cannot truncate!") ? void
(0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrZeroExtend cannot truncate!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4521, __extension__
__PRETTY_FUNCTION__));
4522 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4523 return V; // No conversion
4524 return getZeroExtendExpr(V, Ty);
4525}
4526
4527const SCEV *
4528ScalarEvolution::getNoopOrSignExtend(const SCEV *V, Type *Ty) {
4529 Type *SrcTy = V->getType();
4530 assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&(static_cast <bool> (SrcTy->isIntOrPtrTy() &&
Ty->isIntOrPtrTy() && "Cannot noop or sign extend with non-integer arguments!"
) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or sign extend with non-integer arguments!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4531, __extension__
__PRETTY_FUNCTION__))
4531 "Cannot noop or sign extend with non-integer arguments!")(static_cast <bool> (SrcTy->isIntOrPtrTy() &&
Ty->isIntOrPtrTy() && "Cannot noop or sign extend with non-integer arguments!"
) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or sign extend with non-integer arguments!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4531, __extension__
__PRETTY_FUNCTION__));
4532 assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(SrcTy) <= getTypeSizeInBits
(Ty) && "getNoopOrSignExtend cannot truncate!") ? void
(0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrSignExtend cannot truncate!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4533, __extension__
__PRETTY_FUNCTION__))
4533 "getNoopOrSignExtend cannot truncate!")(static_cast <bool> (getTypeSizeInBits(SrcTy) <= getTypeSizeInBits
(Ty) && "getNoopOrSignExtend cannot truncate!") ? void
(0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrSignExtend cannot truncate!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4533, __extension__
__PRETTY_FUNCTION__));
4534 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4535 return V; // No conversion
4536 return getSignExtendExpr(V, Ty);
4537}
4538
4539const SCEV *
4540ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, Type *Ty) {
4541 Type *SrcTy = V->getType();
4542 assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&(static_cast <bool> (SrcTy->isIntOrPtrTy() &&
Ty->isIntOrPtrTy() && "Cannot noop or any extend with non-integer arguments!"
) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or any extend with non-integer arguments!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4543, __extension__
__PRETTY_FUNCTION__))
4543 "Cannot noop or any extend with non-integer arguments!")(static_cast <bool> (SrcTy->isIntOrPtrTy() &&
Ty->isIntOrPtrTy() && "Cannot noop or any extend with non-integer arguments!"
) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or any extend with non-integer arguments!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4543, __extension__
__PRETTY_FUNCTION__));
4544 assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(SrcTy) <= getTypeSizeInBits
(Ty) && "getNoopOrAnyExtend cannot truncate!") ? void
(0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrAnyExtend cannot truncate!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4545, __extension__
__PRETTY_FUNCTION__))
4545 "getNoopOrAnyExtend cannot truncate!")(static_cast <bool> (getTypeSizeInBits(SrcTy) <= getTypeSizeInBits
(Ty) && "getNoopOrAnyExtend cannot truncate!") ? void
(0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrAnyExtend cannot truncate!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4545, __extension__
__PRETTY_FUNCTION__));
4546 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4547 return V; // No conversion
4548 return getAnyExtendExpr(V, Ty);
4549}
4550
4551const SCEV *
4552ScalarEvolution::getTruncateOrNoop(const SCEV *V, Type *Ty) {
4553 Type *SrcTy = V->getType();
4554 assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&(static_cast <bool> (SrcTy->isIntOrPtrTy() &&
Ty->isIntOrPtrTy() && "Cannot truncate or noop with non-integer arguments!"
) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or noop with non-integer arguments!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4555, __extension__
__PRETTY_FUNCTION__))
4555 "Cannot truncate or noop with non-integer arguments!")(static_cast <bool> (SrcTy->isIntOrPtrTy() &&
Ty->isIntOrPtrTy() && "Cannot truncate or noop with non-integer arguments!"
) ? void (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or noop with non-integer arguments!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4555, __extension__
__PRETTY_FUNCTION__));
4556 assert(getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(SrcTy) >= getTypeSizeInBits
(Ty) && "getTruncateOrNoop cannot extend!") ? void (0
) : __assert_fail ("getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && \"getTruncateOrNoop cannot extend!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4557, __extension__
__PRETTY_FUNCTION__))
4557 "getTruncateOrNoop cannot extend!")(static_cast <bool> (getTypeSizeInBits(SrcTy) >= getTypeSizeInBits
(Ty) && "getTruncateOrNoop cannot extend!") ? void (0
) : __assert_fail ("getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && \"getTruncateOrNoop cannot extend!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4557, __extension__
__PRETTY_FUNCTION__));
4558 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4559 return V; // No conversion
4560 return getTruncateExpr(V, Ty);
4561}
4562
4563const SCEV *ScalarEvolution::getUMaxFromMismatchedTypes(const SCEV *LHS,
4564 const SCEV *RHS) {
4565 const SCEV *PromotedLHS = LHS;
4566 const SCEV *PromotedRHS = RHS;
4567
4568 if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType()))
4569 PromotedRHS = getZeroExtendExpr(RHS, LHS->getType());
4570 else
4571 PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType());
4572
4573 return getUMaxExpr(PromotedLHS, PromotedRHS);
4574}
4575
4576const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(const SCEV *LHS,
4577 const SCEV *RHS,
4578 bool Sequential) {
4579 SmallVector<const SCEV *, 2> Ops = { LHS, RHS };
4580 return getUMinFromMismatchedTypes(Ops, Sequential);
4581}
4582
4583const SCEV *
4584ScalarEvolution::getUMinFromMismatchedTypes(SmallVectorImpl<const SCEV *> &Ops,
4585 bool Sequential) {
4586 assert(!Ops.empty() && "At least one operand must be!")(static_cast <bool> (!Ops.empty() && "At least one operand must be!"
) ? void (0) : __assert_fail ("!Ops.empty() && \"At least one operand must be!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4586, __extension__
__PRETTY_FUNCTION__));
4587 // Trivial case.
4588 if (Ops.size() == 1)
4589 return Ops[0];
4590
4591 // Find the max type first.
4592 Type *MaxType = nullptr;
4593 for (auto *S : Ops)
4594 if (MaxType)
4595 MaxType = getWiderType(MaxType, S->getType());
4596 else
4597 MaxType = S->getType();
4598 assert(MaxType && "Failed to find maximum type!")(static_cast <bool> (MaxType && "Failed to find maximum type!"
) ? void (0) : __assert_fail ("MaxType && \"Failed to find maximum type!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4598, __extension__
__PRETTY_FUNCTION__));
4599
4600 // Extend all ops to max type.
4601 SmallVector<const SCEV *, 2> PromotedOps;
4602 for (auto *S : Ops)
4603 PromotedOps.push_back(getNoopOrZeroExtend(S, MaxType));
4604
4605 // Generate umin.
4606 return getUMinExpr(PromotedOps, Sequential);
4607}
4608
4609const SCEV *ScalarEvolution::getPointerBase(const SCEV *V) {
4610 // A pointer operand may evaluate to a nonpointer expression, such as null.
4611 if (!V->getType()->isPointerTy())
4612 return V;
4613
4614 while (true) {
4615 if (auto *AddRec = dyn_cast<SCEVAddRecExpr>(V)) {
4616 V = AddRec->getStart();
4617 } else if (auto *Add = dyn_cast<SCEVAddExpr>(V)) {
4618 const SCEV *PtrOp = nullptr;
4619 for (const SCEV *AddOp : Add->operands()) {
4620 if (AddOp->getType()->isPointerTy()) {
4621 assert(!PtrOp && "Cannot have multiple pointer ops")(static_cast <bool> (!PtrOp && "Cannot have multiple pointer ops"
) ? void (0) : __assert_fail ("!PtrOp && \"Cannot have multiple pointer ops\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4621, __extension__
__PRETTY_FUNCTION__));
4622 PtrOp = AddOp;
4623 }
4624 }
4625 assert(PtrOp && "Must have pointer op")(static_cast <bool> (PtrOp && "Must have pointer op"
) ? void (0) : __assert_fail ("PtrOp && \"Must have pointer op\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4625, __extension__
__PRETTY_FUNCTION__));
4626 V = PtrOp;
4627 } else // Not something we can look further into.
4628 return V;
4629 }
4630}
4631
4632/// Push users of the given Instruction onto the given Worklist.
4633static void PushDefUseChildren(Instruction *I,
4634 SmallVectorImpl<Instruction *> &Worklist,
4635 SmallPtrSetImpl<Instruction *> &Visited) {
4636 // Push the def-use children onto the Worklist stack.
4637 for (User *U : I->users()) {
4638 auto *UserInsn = cast<Instruction>(U);
4639 if (Visited.insert(UserInsn).second)
4640 Worklist.push_back(UserInsn);
4641 }
4642}
4643
4644namespace {
4645
4646/// Takes SCEV S and Loop L. For each AddRec sub-expression, use its start
4647/// expression in case its Loop is L. If it is not L then
4648/// if IgnoreOtherLoops is true then use AddRec itself
4649/// otherwise rewrite cannot be done.
4650/// If SCEV contains non-invariant unknown SCEV rewrite cannot be done.
4651class SCEVInitRewriter : public SCEVRewriteVisitor<SCEVInitRewriter> {
4652public:
4653 static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE,
4654 bool IgnoreOtherLoops = true) {
4655 SCEVInitRewriter Rewriter(L, SE);
4656 const SCEV *Result = Rewriter.visit(S);
4657 if (Rewriter.hasSeenLoopVariantSCEVUnknown())
4658 return SE.getCouldNotCompute();
4659 return Rewriter.hasSeenOtherLoops() && !IgnoreOtherLoops
4660 ? SE.getCouldNotCompute()
4661 : Result;
4662 }
4663
4664 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4665 if (!SE.isLoopInvariant(Expr, L))
4666 SeenLoopVariantSCEVUnknown = true;
4667 return Expr;
4668 }
4669
4670 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4671 // Only re-write AddRecExprs for this loop.
4672 if (Expr->getLoop() == L)
4673 return Expr->getStart();
4674 SeenOtherLoops = true;
4675 return Expr;
4676 }
4677
4678 bool hasSeenLoopVariantSCEVUnknown() { return SeenLoopVariantSCEVUnknown; }
4679
4680 bool hasSeenOtherLoops() { return SeenOtherLoops; }
4681
4682private:
4683 explicit SCEVInitRewriter(const Loop *L, ScalarEvolution &SE)
4684 : SCEVRewriteVisitor(SE), L(L) {}
4685
4686 const Loop *L;
4687 bool SeenLoopVariantSCEVUnknown = false;
4688 bool SeenOtherLoops = false;
4689};
4690
4691/// Takes SCEV S and Loop L. For each AddRec sub-expression, use its post
4692/// increment expression in case its Loop is L. If it is not L then
4693/// use AddRec itself.
4694/// If SCEV contains non-invariant unknown SCEV rewrite cannot be done.
4695class SCEVPostIncRewriter : public SCEVRewriteVisitor<SCEVPostIncRewriter> {
4696public:
4697 static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE) {
4698 SCEVPostIncRewriter Rewriter(L, SE);
4699 const SCEV *Result = Rewriter.visit(S);
4700 return Rewriter.hasSeenLoopVariantSCEVUnknown()
4701 ? SE.getCouldNotCompute()
4702 : Result;
4703 }
4704
4705 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4706 if (!SE.isLoopInvariant(Expr, L))
4707 SeenLoopVariantSCEVUnknown = true;
4708 return Expr;
4709 }
4710
4711 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4712 // Only re-write AddRecExprs for this loop.
4713 if (Expr->getLoop() == L)
4714 return Expr->getPostIncExpr(SE);
4715 SeenOtherLoops = true;
4716 return Expr;
4717 }
4718
4719 bool hasSeenLoopVariantSCEVUnknown() { return SeenLoopVariantSCEVUnknown; }
4720
4721 bool hasSeenOtherLoops() { return SeenOtherLoops; }
4722
4723private:
4724 explicit SCEVPostIncRewriter(const Loop *L, ScalarEvolution &SE)
4725 : SCEVRewriteVisitor(SE), L(L) {}
4726
4727 const Loop *L;
4728 bool SeenLoopVariantSCEVUnknown = false;
4729 bool SeenOtherLoops = false;
4730};
4731
4732/// This class evaluates the compare condition by matching it against the
4733/// condition of loop latch. If there is a match we assume a true value
4734/// for the condition while building SCEV nodes.
4735class SCEVBackedgeConditionFolder
4736 : public SCEVRewriteVisitor<SCEVBackedgeConditionFolder> {
4737public:
4738 static const SCEV *rewrite(const SCEV *S, const Loop *L,
4739 ScalarEvolution &SE) {
4740 bool IsPosBECond = false;
4741 Value *BECond = nullptr;
4742 if (BasicBlock *Latch = L->getLoopLatch()) {
4743 BranchInst *BI = dyn_cast<BranchInst>(Latch->getTerminator());
4744 if (BI && BI->isConditional()) {
4745 assert(BI->getSuccessor(0) != BI->getSuccessor(1) &&(static_cast <bool> (BI->getSuccessor(0) != BI->getSuccessor
(1) && "Both outgoing branches should not target same header!"
) ? void (0) : __assert_fail ("BI->getSuccessor(0) != BI->getSuccessor(1) && \"Both outgoing branches should not target same header!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4746, __extension__
__PRETTY_FUNCTION__))
4746 "Both outgoing branches should not target same header!")(static_cast <bool> (BI->getSuccessor(0) != BI->getSuccessor
(1) && "Both outgoing branches should not target same header!"
) ? void (0) : __assert_fail ("BI->getSuccessor(0) != BI->getSuccessor(1) && \"Both outgoing branches should not target same header!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 4746, __extension__
__PRETTY_FUNCTION__));
4747 BECond = BI->getCondition();
4748 IsPosBECond = BI->getSuccessor(0) == L->getHeader();
4749 } else {
4750 return S;
4751 }
4752 }
4753 SCEVBackedgeConditionFolder Rewriter(L, BECond, IsPosBECond, SE);
4754 return Rewriter.visit(S);
4755 }
4756
4757 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4758 const SCEV *Result = Expr;
4759 bool InvariantF = SE.isLoopInvariant(Expr, L);
4760
4761 if (!InvariantF) {
4762 Instruction *I = cast<Instruction>(Expr->getValue());
4763 switch (I->getOpcode()) {
4764 case Instruction::Select: {
4765 SelectInst *SI = cast<SelectInst>(I);
4766 Optional<const SCEV *> Res =
4767 compareWithBackedgeCondition(SI->getCondition());
4768 if (Res.hasValue()) {
4769 bool IsOne = cast<SCEVConstant>(Res.getValue())->getValue()->isOne();
4770 Result = SE.getSCEV(IsOne ? SI->getTrueValue() : SI->getFalseValue());
4771 }
4772 break;
4773 }
4774 default: {
4775 Optional<const SCEV *> Res = compareWithBackedgeCondition(I);
4776 if (Res.hasValue())
4777 Result = Res.getValue();
4778 break;
4779 }
4780 }
4781 }
4782 return Result;
4783 }
4784
4785private:
4786 explicit SCEVBackedgeConditionFolder(const Loop *L, Value *BECond,
4787 bool IsPosBECond, ScalarEvolution &SE)
4788 : SCEVRewriteVisitor(SE), L(L), BackedgeCond(BECond),
4789 IsPositiveBECond(IsPosBECond) {}
4790
4791 Optional<const SCEV *> compareWithBackedgeCondition(Value *IC);
4792
4793 const Loop *L;
4794 /// Loop back condition.
4795 Value *BackedgeCond = nullptr;
4796 /// Set to true if loop back is on positive branch condition.
4797 bool IsPositiveBECond;
4798};
4799
4800Optional<const SCEV *>
4801SCEVBackedgeConditionFolder::compareWithBackedgeCondition(Value *IC) {
4802
4803 // If value matches the backedge condition for loop latch,
4804 // then return a constant evolution node based on loopback
4805 // branch taken.
4806 if (BackedgeCond == IC)
4807 return IsPositiveBECond ? SE.getOne(Type::getInt1Ty(SE.getContext()))
4808 : SE.getZero(Type::getInt1Ty(SE.getContext()));
4809 return None;
4810}
4811
4812class SCEVShiftRewriter : public SCEVRewriteVisitor<SCEVShiftRewriter> {
4813public:
4814 static const SCEV *rewrite(const SCEV *S, const Loop *L,
4815 ScalarEvolution &SE) {
4816 SCEVShiftRewriter Rewriter(L, SE);
4817 const SCEV *Result = Rewriter.visit(S);
4818 return Rewriter.isValid() ? Result : SE.getCouldNotCompute();
4819 }
4820
4821 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4822 // Only allow AddRecExprs for this loop.
4823 if (!SE.isLoopInvariant(Expr, L))
4824 Valid = false;
4825 return Expr;
4826 }
4827
4828 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4829 if (Expr->getLoop() == L && Expr->isAffine())
4830 return SE.getMinusSCEV(Expr, Expr->getStepRecurrence(SE));
4831 Valid = false;
4832 return Expr;
4833 }
4834
4835 bool isValid() { return Valid; }
4836
4837private:
4838 explicit SCEVShiftRewriter(const Loop *L, ScalarEvolution &SE)
4839 : SCEVRewriteVisitor(SE), L(L) {}
4840
4841 const Loop *L;
4842 bool Valid = true;
4843};
4844
4845} // end anonymous namespace
4846
4847SCEV::NoWrapFlags
4848ScalarEvolution::proveNoWrapViaConstantRanges(const SCEVAddRecExpr *AR) {
4849 if (!AR->isAffine())
4850 return SCEV::FlagAnyWrap;
4851
4852 using OBO = OverflowingBinaryOperator;
4853
4854 SCEV::NoWrapFlags Result = SCEV::FlagAnyWrap;
4855
4856 if (!AR->hasNoSignedWrap()) {
4857 ConstantRange AddRecRange = getSignedRange(AR);
4858 ConstantRange IncRange = getSignedRange(AR->getStepRecurrence(*this));
4859
4860 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
4861 Instruction::Add, IncRange, OBO::NoSignedWrap);
4862 if (NSWRegion.contains(AddRecRange))
4863 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNSW);
4864 }
4865
4866 if (!AR->hasNoUnsignedWrap()) {
4867 ConstantRange AddRecRange = getUnsignedRange(AR);
4868 ConstantRange IncRange = getUnsignedRange(AR->getStepRecurrence(*this));
4869
4870 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
4871 Instruction::Add, IncRange, OBO::NoUnsignedWrap);
4872 if (NUWRegion.contains(AddRecRange))
4873 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNUW);
4874 }
4875
4876 return Result;
4877}
4878
4879SCEV::NoWrapFlags
4880ScalarEvolution::proveNoSignedWrapViaInduction(const SCEVAddRecExpr *AR) {
4881 SCEV::NoWrapFlags Result = AR->getNoWrapFlags();
4882
4883 if (AR->hasNoSignedWrap())
4884 return Result;
4885
4886 if (!AR->isAffine())
4887 return Result;
4888
4889 const SCEV *Step = AR->getStepRecurrence(*this);
4890 const Loop *L = AR->getLoop();
4891
4892 // Check whether the backedge-taken count is SCEVCouldNotCompute.
4893 // Note that this serves two purposes: It filters out loops that are
4894 // simply not analyzable, and it covers the case where this code is
4895 // being called from within backedge-taken count analysis, such that
4896 // attempting to ask for the backedge-taken count would likely result
4897 // in infinite recursion. In the later case, the analysis code will
4898 // cope with a conservative value, and it will take care to purge
4899 // that value once it has finished.
4900 const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(L);
4901
4902 // Normally, in the cases we can prove no-overflow via a
4903 // backedge guarding condition, we can also compute a backedge
4904 // taken count for the loop. The exceptions are assumptions and
4905 // guards present in the loop -- SCEV is not great at exploiting
4906 // these to compute max backedge taken counts, but can still use
4907 // these to prove lack of overflow. Use this fact to avoid
4908 // doing extra work that may not pay off.
4909
4910 if (isa<SCEVCouldNotCompute>(MaxBECount) && !HasGuards &&
4911 AC.assumptions().empty())
4912 return Result;
4913
4914 // If the backedge is guarded by a comparison with the pre-inc value the
4915 // addrec is safe. Also, if the entry is guarded by a comparison with the
4916 // start value and the backedge is guarded by a comparison with the post-inc
4917 // value, the addrec is safe.
4918 ICmpInst::Predicate Pred;
4919 const SCEV *OverflowLimit =
4920 getSignedOverflowLimitForStep(Step, &Pred, this);
4921 if (OverflowLimit &&
4922 (isLoopBackedgeGuardedByCond(L, Pred, AR, OverflowLimit) ||
4923 isKnownOnEveryIteration(Pred, AR, OverflowLimit))) {
4924 Result = setFlags(Result, SCEV::FlagNSW);
4925 }
4926 return Result;
4927}
4928SCEV::NoWrapFlags
4929ScalarEvolution::proveNoUnsignedWrapViaInduction(const SCEVAddRecExpr *AR) {
4930 SCEV::NoWrapFlags Result = AR->getNoWrapFlags();
4931
4932 if (AR->hasNoUnsignedWrap())
4933 return Result;
4934
4935 if (!AR->isAffine())
4936 return Result;
4937
4938 const SCEV *Step = AR->getStepRecurrence(*this);
4939 unsigned BitWidth = getTypeSizeInBits(AR->getType());
4940 const Loop *L = AR->getLoop();
4941
4942 // Check whether the backedge-taken count is SCEVCouldNotCompute.
4943 // Note that this serves two purposes: It filters out loops that are
4944 // simply not analyzable, and it covers the case where this code is
4945 // being called from within backedge-taken count analysis, such that
4946 // attempting to ask for the backedge-taken count would likely result
4947 // in infinite recursion. In the later case, the analysis code will
4948 // cope with a conservative value, and it will take care to purge
4949 // that value once it has finished.
4950 const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(L);
4951
4952 // Normally, in the cases we can prove no-overflow via a
4953 // backedge guarding condition, we can also compute a backedge
4954 // taken count for the loop. The exceptions are assumptions and
4955 // guards present in the loop -- SCEV is not great at exploiting
4956 // these to compute max backedge taken counts, but can still use
4957 // these to prove lack of overflow. Use this fact to avoid
4958 // doing extra work that may not pay off.
4959
4960 if (isa<SCEVCouldNotCompute>(MaxBECount) && !HasGuards &&
4961 AC.assumptions().empty())
4962 return Result;
4963
4964 // If the backedge is guarded by a comparison with the pre-inc value the
4965 // addrec is safe. Also, if the entry is guarded by a comparison with the
4966 // start value and the backedge is guarded by a comparison with the post-inc
4967 // value, the addrec is safe.
4968 if (isKnownPositive(Step)) {
4969 const SCEV *N = getConstant(APInt::getMinValue(BitWidth) -
4970 getUnsignedRangeMax(Step));
4971 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT, AR, N) ||
4972 isKnownOnEveryIteration(ICmpInst::ICMP_ULT, AR, N)) {
4973 Result = setFlags(Result, SCEV::FlagNUW);
4974 }
4975 }
4976
4977 return Result;
4978}
4979
4980namespace {
4981
4982/// Represents an abstract binary operation. This may exist as a
4983/// normal instruction or constant expression, or may have been
4984/// derived from an expression tree.
4985struct BinaryOp {
4986 unsigned Opcode;
4987 Value *LHS;
4988 Value *RHS;
4989 bool IsNSW = false;
4990 bool IsNUW = false;
4991
4992 /// Op is set if this BinaryOp corresponds to a concrete LLVM instruction or
4993 /// constant expression.
4994 Operator *Op = nullptr;
4995
4996 explicit BinaryOp(Operator *Op)
4997 : Opcode(Op->getOpcode()), LHS(Op->getOperand(0)), RHS(Op->getOperand(1)),
4998 Op(Op) {
4999 if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(Op)) {
5000 IsNSW = OBO->hasNoSignedWrap();
5001 IsNUW = OBO->hasNoUnsignedWrap();
5002 }
5003 }
5004
5005 explicit BinaryOp(unsigned Opcode, Value *LHS, Value *RHS, bool IsNSW = false,
5006 bool IsNUW = false)
5007 : Opcode(Opcode), LHS(LHS), RHS(RHS), IsNSW(IsNSW), IsNUW(IsNUW) {}
5008};
5009
5010} // end anonymous namespace
5011
5012/// Try to map \p V into a BinaryOp, and return \c None on failure.
5013static Optional<BinaryOp> MatchBinaryOp(Value *V, DominatorTree &DT) {
5014 auto *Op = dyn_cast<Operator>(V);
5015 if (!Op)
5016 return None;
5017
5018 // Implementation detail: all the cleverness here should happen without
5019 // creating new SCEV expressions -- our caller knowns tricks to avoid creating
5020 // SCEV expressions when possible, and we should not break that.
5021
5022 switch (Op->getOpcode()) {
5023 case Instruction::Add:
5024 case Instruction::Sub:
5025 case Instruction::Mul:
5026 case Instruction::UDiv:
5027 case Instruction::URem:
5028 case Instruction::And:
5029 case Instruction::Or:
5030 case Instruction::AShr:
5031 case Instruction::Shl:
5032 return BinaryOp(Op);
5033
5034 case Instruction::Xor:
5035 if (auto *RHSC = dyn_cast<ConstantInt>(Op->getOperand(1)))
5036 // If the RHS of the xor is a signmask, then this is just an add.
5037 // Instcombine turns add of signmask into xor as a strength reduction step.
5038 if (RHSC->getValue().isSignMask())
5039 return BinaryOp(Instruction::Add, Op->getOperand(0), Op->getOperand(1));
5040 // Binary `xor` is a bit-wise `add`.
5041 if (V->getType()->isIntegerTy(1))
5042 return BinaryOp(Instruction::Add, Op->getOperand(0), Op->getOperand(1));
5043 return BinaryOp(Op);
5044
5045 case Instruction::LShr:
5046 // Turn logical shift right of a constant into a unsigned divide.
5047 if (ConstantInt *SA = dyn_cast<ConstantInt>(Op->getOperand(1))) {
5048 uint32_t BitWidth = cast<IntegerType>(Op->getType())->getBitWidth();
5049
5050 // If the shift count is not less than the bitwidth, the result of
5051 // the shift is undefined. Don't try to analyze it, because the
5052 // resolution chosen here may differ from the resolution chosen in
5053 // other parts of the compiler.
5054 if (SA->getValue().ult(BitWidth)) {
5055 Constant *X =
5056 ConstantInt::get(SA->getContext(),
5057 APInt::getOneBitSet(BitWidth, SA->getZExtValue()));
5058 return BinaryOp(Instruction::UDiv, Op->getOperand(0), X);
5059 }
5060 }
5061 return BinaryOp(Op);
5062
5063 case Instruction::ExtractValue: {
5064 auto *EVI = cast<ExtractValueInst>(Op);
5065 if (EVI->getNumIndices() != 1 || EVI->getIndices()[0] != 0)
5066 break;
5067
5068 auto *WO = dyn_cast<WithOverflowInst>(EVI->getAggregateOperand());
5069 if (!WO)
5070 break;
5071
5072 Instruction::BinaryOps BinOp = WO->getBinaryOp();
5073 bool Signed = WO->isSigned();
5074 // TODO: Should add nuw/nsw flags for mul as well.
5075 if (BinOp == Instruction::Mul || !isOverflowIntrinsicNoWrap(WO, DT))
5076 return BinaryOp(BinOp, WO->getLHS(), WO->getRHS());
5077
5078 // Now that we know that all uses of the arithmetic-result component of
5079 // CI are guarded by the overflow check, we can go ahead and pretend
5080 // that the arithmetic is non-overflowing.
5081 return BinaryOp(BinOp, WO->getLHS(), WO->getRHS(),
5082 /* IsNSW = */ Signed, /* IsNUW = */ !Signed);
5083 }
5084
5085 default:
5086 break;
5087 }
5088
5089 // Recognise intrinsic loop.decrement.reg, and as this has exactly the same
5090 // semantics as a Sub, return a binary sub expression.
5091 if (auto *II = dyn_cast<IntrinsicInst>(V))
5092 if (II->getIntrinsicID() == Intrinsic::loop_decrement_reg)
5093 return BinaryOp(Instruction::Sub, II->getOperand(0), II->getOperand(1));
5094
5095 return None;
5096}
5097
5098/// Helper function to createAddRecFromPHIWithCasts. We have a phi
5099/// node whose symbolic (unknown) SCEV is \p SymbolicPHI, which is updated via
5100/// the loop backedge by a SCEVAddExpr, possibly also with a few casts on the
5101/// way. This function checks if \p Op, an operand of this SCEVAddExpr,
5102/// follows one of the following patterns:
5103/// Op == (SExt ix (Trunc iy (%SymbolicPHI) to ix) to iy)
5104/// Op == (ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy)
5105/// If the SCEV expression of \p Op conforms with one of the expected patterns
5106/// we return the type of the truncation operation, and indicate whether the
5107/// truncated type should be treated as signed/unsigned by setting
5108/// \p Signed to true/false, respectively.
5109static Type *isSimpleCastedPHI(const SCEV *Op, const SCEVUnknown *SymbolicPHI,
5110 bool &Signed, ScalarEvolution &SE) {
5111 // The case where Op == SymbolicPHI (that is, with no type conversions on
5112 // the way) is handled by the regular add recurrence creating logic and
5113 // would have already been triggered in createAddRecForPHI. Reaching it here
5114 // means that createAddRecFromPHI had failed for this PHI before (e.g.,
5115 // because one of the other operands of the SCEVAddExpr updating this PHI is
5116 // not invariant).
5117 //
5118 // Here we look for the case where Op = (ext(trunc(SymbolicPHI))), and in
5119 // this case predicates that allow us to prove that Op == SymbolicPHI will
5120 // be added.
5121 if (Op == SymbolicPHI)
5122 return nullptr;
5123
5124 unsigned SourceBits = SE.getTypeSizeInBits(SymbolicPHI->getType());
5125 unsigned NewBits = SE.getTypeSizeInBits(Op->getType());
5126 if (SourceBits != NewBits)
5127 return nullptr;
5128
5129 const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(Op);
5130 const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(Op);
5131 if (!SExt && !ZExt)
5132 return nullptr;
5133 const SCEVTruncateExpr *Trunc =
5134 SExt ? dyn_cast<SCEVTruncateExpr>(SExt->getOperand())
5135 : dyn_cast<SCEVTruncateExpr>(ZExt->getOperand());
5136 if (!Trunc)
5137 return nullptr;
5138 const SCEV *X = Trunc->getOperand();
5139 if (X != SymbolicPHI)
5140 return nullptr;
5141 Signed = SExt != nullptr;
5142 return Trunc->getType();
5143}
5144
5145static const Loop *isIntegerLoopHeaderPHI(const PHINode *PN, LoopInfo &LI) {
5146 if (!PN->getType()->isIntegerTy())
5147 return nullptr;
5148 const Loop *L = LI.getLoopFor(PN->getParent());
5149 if (!L || L->getHeader() != PN->getParent())
5150 return nullptr;
5151 return L;
5152}
5153
5154// Analyze \p SymbolicPHI, a SCEV expression of a phi node, and check if the
5155// computation that updates the phi follows the following pattern:
5156// (SExt/ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy) + InvariantAccum
5157// which correspond to a phi->trunc->sext/zext->add->phi update chain.
5158// If so, try to see if it can be rewritten as an AddRecExpr under some
5159// Predicates. If successful, return them as a pair. Also cache the results
5160// of the analysis.
5161//
5162// Example usage scenario:
5163// Say the Rewriter is called for the following SCEV:
5164// 8 * ((sext i32 (trunc i64 %X to i32) to i64) + %Step)
5165// where:
5166// %X = phi i64 (%Start, %BEValue)
5167// It will visitMul->visitAdd->visitSExt->visitTrunc->visitUnknown(%X),
5168// and call this function with %SymbolicPHI = %X.
5169//
5170// The analysis will find that the value coming around the backedge has
5171// the following SCEV:
5172// BEValue = ((sext i32 (trunc i64 %X to i32) to i64) + %Step)
5173// Upon concluding that this matches the desired pattern, the function
5174// will return the pair {NewAddRec, SmallPredsVec} where:
5175// NewAddRec = {%Start,+,%Step}
5176// SmallPredsVec = {P1, P2, P3} as follows:
5177// P1(WrapPred): AR: {trunc(%Start),+,(trunc %Step)}<nsw> Flags: <nssw>
5178// P2(EqualPred): %Start == (sext i32 (trunc i64 %Start to i32) to i64)
5179// P3(EqualPred): %Step == (sext i32 (trunc i64 %Step to i32) to i64)
5180// The returned pair means that SymbolicPHI can be rewritten into NewAddRec
5181// under the predicates {P1,P2,P3}.
5182// This predicated rewrite will be cached in PredicatedSCEVRewrites:
5183// PredicatedSCEVRewrites[{%X,L}] = {NewAddRec, {P1,P2,P3)}
5184//
5185// TODO's:
5186//
5187// 1) Extend the Induction descriptor to also support inductions that involve
5188// casts: When needed (namely, when we are called in the context of the
5189// vectorizer induction analysis), a Set of cast instructions will be
5190// populated by this method, and provided back to isInductionPHI. This is
5191// needed to allow the vectorizer to properly record them to be ignored by
5192// the cost model and to avoid vectorizing them (otherwise these casts,
5193// which are redundant under the runtime overflow checks, will be
5194// vectorized, which can be costly).
5195//
5196// 2) Support additional induction/PHISCEV patterns: We also want to support
5197// inductions where the sext-trunc / zext-trunc operations (partly) occur
5198// after the induction update operation (the induction increment):
5199//
5200// (Trunc iy (SExt/ZExt ix (%SymbolicPHI + InvariantAccum) to iy) to ix)
5201// which correspond to a phi->add->trunc->sext/zext->phi update chain.
5202//
5203// (Trunc iy ((SExt/ZExt ix (%SymbolicPhi) to iy) + InvariantAccum) to ix)
5204// which correspond to a phi->trunc->add->sext/zext->phi update chain.
5205//
5206// 3) Outline common code with createAddRecFromPHI to avoid duplication.
5207Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
5208ScalarEvolution::createAddRecFromPHIWithCastsImpl(const SCEVUnknown *SymbolicPHI) {
5209 SmallVector<const SCEVPredicate *, 3> Predicates;
5210
5211 // *** Part1: Analyze if we have a phi-with-cast pattern for which we can
5212 // return an AddRec expression under some predicate.
5213
5214 auto *PN = cast<PHINode>(SymbolicPHI->getValue());
5215 const Loop *L = isIntegerLoopHeaderPHI(PN, LI);
5216 assert(L && "Expecting an integer loop header phi")(static_cast <bool> (L && "Expecting an integer loop header phi"
) ? void (0) : __assert_fail ("L && \"Expecting an integer loop header phi\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 5216, __extension__
__PRETTY_FUNCTION__));
5217
5218 // The loop may have multiple entrances or multiple exits; we can analyze
5219 // this phi as an addrec if it has a unique entry value and a unique
5220 // backedge value.
5221 Value *BEValueV = nullptr, *StartValueV = nullptr;
5222 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
5223 Value *V = PN->getIncomingValue(i);
5224 if (L->contains(PN->getIncomingBlock(i))) {
5225 if (!BEValueV) {
5226 BEValueV = V;
5227 } else if (BEValueV != V) {
5228 BEValueV = nullptr;
5229 break;
5230 }
5231 } else if (!StartValueV) {
5232 StartValueV = V;
5233 } else if (StartValueV != V) {
5234 StartValueV = nullptr;
5235 break;
5236 }
5237 }
5238 if (!BEValueV || !StartValueV)
5239 return None;
5240
5241 const SCEV *BEValue = getSCEV(BEValueV);
5242
5243 // If the value coming around the backedge is an add with the symbolic
5244 // value we just inserted, possibly with casts that we can ignore under
5245 // an appropriate runtime guard, then we found a simple induction variable!
5246 const auto *Add = dyn_cast<SCEVAddExpr>(BEValue);
5247 if (!Add)
5248 return None;
5249
5250 // If there is a single occurrence of the symbolic value, possibly
5251 // casted, replace it with a recurrence.
5252 unsigned FoundIndex = Add->getNumOperands();
5253 Type *TruncTy = nullptr;
5254 bool Signed;
5255 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
5256 if ((TruncTy =
5257 isSimpleCastedPHI(Add->getOperand(i), SymbolicPHI, Signed, *this)))
5258 if (FoundIndex == e) {
5259 FoundIndex = i;
5260 break;
5261 }
5262
5263 if (FoundIndex == Add->getNumOperands())
5264 return None;
5265
5266 // Create an add with everything but the specified operand.
5267 SmallVector<const SCEV *, 8> Ops;
5268 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
5269 if (i != FoundIndex)
5270 Ops.push_back(Add->getOperand(i));
5271 const SCEV *Accum = getAddExpr(Ops);
5272
5273 // The runtime checks will not be valid if the step amount is
5274 // varying inside the loop.
5275 if (!isLoopInvariant(Accum, L))
5276 return None;
5277
5278 // *** Part2: Create the predicates
5279
5280 // Analysis was successful: we have a phi-with-cast pattern for which we
5281 // can return an AddRec expression under the following predicates:
5282 //
5283 // P1: A Wrap predicate that guarantees that Trunc(Start) + i*Trunc(Accum)
5284 // fits within the truncated type (does not overflow) for i = 0 to n-1.
5285 // P2: An Equal predicate that guarantees that
5286 // Start = (Ext ix (Trunc iy (Start) to ix) to iy)
5287 // P3: An Equal predicate that guarantees that
5288 // Accum = (Ext ix (Trunc iy (Accum) to ix) to iy)
5289 //
5290 // As we next prove, the above predicates guarantee that:
5291 // Start + i*Accum = (Ext ix (Trunc iy ( Start + i*Accum ) to ix) to iy)
5292 //
5293 //
5294 // More formally, we want to prove that:
5295 // Expr(i+1) = Start + (i+1) * Accum
5296 // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum
5297 //
5298 // Given that:
5299 // 1) Expr(0) = Start
5300 // 2) Expr(1) = Start + Accum
5301 // = (Ext ix (Trunc iy (Start) to ix) to iy) + Accum :: from P2
5302 // 3) Induction hypothesis (step i):
5303 // Expr(i) = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum
5304 //
5305 // Proof:
5306 // Expr(i+1) =
5307 // = Start + (i+1)*Accum
5308 // = (Start + i*Accum) + Accum
5309 // = Expr(i) + Accum
5310 // = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum + Accum
5311 // :: from step i
5312 //
5313 // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy) + Accum + Accum
5314 //
5315 // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy)
5316 // + (Ext ix (Trunc iy (Accum) to ix) to iy)
5317 // + Accum :: from P3
5318 //
5319 // = (Ext ix (Trunc iy ((Start + (i-1)*Accum) + Accum) to ix) to iy)
5320 // + Accum :: from P1: Ext(x)+Ext(y)=>Ext(x+y)
5321 //
5322 // = (Ext ix (Trunc iy (Start + i*Accum) to ix) to iy) + Accum
5323 // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum
5324 //
5325 // By induction, the same applies to all iterations 1<=i<n:
5326 //
5327
5328 // Create a truncated addrec for which we will add a no overflow check (P1).
5329 const SCEV *StartVal = getSCEV(StartValueV);
5330 const SCEV *PHISCEV =
5331 getAddRecExpr(getTruncateExpr(StartVal, TruncTy),
5332 getTruncateExpr(Accum, TruncTy), L, SCEV::FlagAnyWrap);
5333
5334 // PHISCEV can be either a SCEVConstant or a SCEVAddRecExpr.
5335 // ex: If truncated Accum is 0 and StartVal is a constant, then PHISCEV
5336 // will be constant.
5337 //
5338 // If PHISCEV is a constant, then P1 degenerates into P2 or P3, so we don't
5339 // add P1.
5340 if (const auto *AR = dyn_cast<SCEVAddRecExpr>(PHISCEV)) {
5341 SCEVWrapPredicate::IncrementWrapFlags AddedFlags =
5342 Signed ? SCEVWrapPredicate::IncrementNSSW
5343 : SCEVWrapPredicate::IncrementNUSW;
5344 const SCEVPredicate *AddRecPred = getWrapPredicate(AR, AddedFlags);
5345 Predicates.push_back(AddRecPred);
5346 }
5347
5348 // Create the Equal Predicates P2,P3:
5349
5350 // It is possible that the predicates P2 and/or P3 are computable at
5351 // compile time due to StartVal and/or Accum being constants.
5352 // If either one is, then we can check that now and escape if either P2
5353 // or P3 is false.
5354
5355 // Construct the extended SCEV: (Ext ix (Trunc iy (Expr) to ix) to iy)
5356 // for each of StartVal and Accum
5357 auto getExtendedExpr = [&](const SCEV *Expr,
5358 bool CreateSignExtend) -> const SCEV * {
5359 assert(isLoopInvariant(Expr, L) && "Expr is expected to be invariant")(static_cast <bool> (isLoopInvariant(Expr, L) &&
"Expr is expected to be invariant") ? void (0) : __assert_fail
("isLoopInvariant(Expr, L) && \"Expr is expected to be invariant\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 5359, __extension__
__PRETTY_FUNCTION__));
5360 const SCEV *TruncatedExpr = getTruncateExpr(Expr, TruncTy);
5361 const SCEV *ExtendedExpr =
5362 CreateSignExtend ? getSignExtendExpr(TruncatedExpr, Expr->getType())
5363 : getZeroExtendExpr(TruncatedExpr, Expr->getType());
5364 return ExtendedExpr;
5365 };
5366
5367 // Given:
5368 // ExtendedExpr = (Ext ix (Trunc iy (Expr) to ix) to iy
5369 // = getExtendedExpr(Expr)
5370 // Determine whether the predicate P: Expr == ExtendedExpr
5371 // is known to be false at compile time
5372 auto PredIsKnownFalse = [&](const SCEV *Expr,
5373 const SCEV *ExtendedExpr) -> bool {
5374 return Expr != ExtendedExpr &&
5375 isKnownPredicate(ICmpInst::ICMP_NE, Expr, ExtendedExpr);
5376 };
5377
5378 const SCEV *StartExtended = getExtendedExpr(StartVal, Signed);
5379 if (PredIsKnownFalse(StartVal, StartExtended)) {
5380 LLVM_DEBUG(dbgs() << "P2 is compile-time false\n";)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "P2 is compile-time false\n"
;; } } while (false);
5381 return None;
5382 }
5383
5384 // The Step is always Signed (because the overflow checks are either
5385 // NSSW or NUSW)
5386 const SCEV *AccumExtended = getExtendedExpr(Accum, /*CreateSignExtend=*/true);
5387 if (PredIsKnownFalse(Accum, AccumExtended)) {
5388 LLVM_DEBUG(dbgs() << "P3 is compile-time false\n";)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "P3 is compile-time false\n"
;; } } while (false);
5389 return None;
5390 }
5391
5392 auto AppendPredicate = [&](const SCEV *Expr,
5393 const SCEV *ExtendedExpr) -> void {
5394 if (Expr != ExtendedExpr &&
5395 !isKnownPredicate(ICmpInst::ICMP_EQ, Expr, ExtendedExpr)) {
5396 const SCEVPredicate *Pred = getEqualPredicate(Expr, ExtendedExpr);
5397 LLVM_DEBUG(dbgs() << "Added Predicate: " << *Pred)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "Added Predicate: " <<
*Pred; } } while (false);
5398 Predicates.push_back(Pred);
5399 }
5400 };
5401
5402 AppendPredicate(StartVal, StartExtended);
5403 AppendPredicate(Accum, AccumExtended);
5404
5405 // *** Part3: Predicates are ready. Now go ahead and create the new addrec in
5406 // which the casts had been folded away. The caller can rewrite SymbolicPHI
5407 // into NewAR if it will also add the runtime overflow checks specified in
5408 // Predicates.
5409 auto *NewAR = getAddRecExpr(StartVal, Accum, L, SCEV::FlagAnyWrap);
5410
5411 std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> PredRewrite =
5412 std::make_pair(NewAR, Predicates);
5413 // Remember the result of the analysis for this SCEV at this locayyytion.
5414 PredicatedSCEVRewrites[{SymbolicPHI, L}] = PredRewrite;
5415 return PredRewrite;
5416}
5417
5418Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
5419ScalarEvolution::createAddRecFromPHIWithCasts(const SCEVUnknown *SymbolicPHI) {
5420 auto *PN = cast<PHINode>(SymbolicPHI->getValue());
5421 const Loop *L = isIntegerLoopHeaderPHI(PN, LI);
5422 if (!L)
5423 return None;
5424
5425 // Check to see if we already analyzed this PHI.
5426 auto I = PredicatedSCEVRewrites.find({SymbolicPHI, L});
5427 if (I != PredicatedSCEVRewrites.end()) {
5428 std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> Rewrite =
5429 I->second;
5430 // Analysis was done before and failed to create an AddRec:
5431 if (Rewrite.first == SymbolicPHI)
5432 return None;
5433 // Analysis was done before and succeeded to create an AddRec under
5434 // a predicate:
5435 assert(isa<SCEVAddRecExpr>(Rewrite.first) && "Expected an AddRec")(static_cast <bool> (isa<SCEVAddRecExpr>(Rewrite.
first) && "Expected an AddRec") ? void (0) : __assert_fail
("isa<SCEVAddRecExpr>(Rewrite.first) && \"Expected an AddRec\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 5435, __extension__
__PRETTY_FUNCTION__));
5436 assert(!(Rewrite.second).empty() && "Expected to find Predicates")(static_cast <bool> (!(Rewrite.second).empty() &&
"Expected to find Predicates") ? void (0) : __assert_fail ("!(Rewrite.second).empty() && \"Expected to find Predicates\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 5436, __extension__
__PRETTY_FUNCTION__));
5437 return Rewrite;
5438 }
5439
5440 Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
5441 Rewrite = createAddRecFromPHIWithCastsImpl(SymbolicPHI);
5442
5443 // Record in the cache that the analysis failed
5444 if (!Rewrite) {
5445 SmallVector<const SCEVPredicate *, 3> Predicates;
5446 PredicatedSCEVRewrites[{SymbolicPHI, L}] = {SymbolicPHI, Predicates};
5447 return None;
5448 }
5449
5450 return Rewrite;
5451}
5452
5453// FIXME: This utility is currently required because the Rewriter currently
5454// does not rewrite this expression:
5455// {0, +, (sext ix (trunc iy to ix) to iy)}
5456// into {0, +, %step},
5457// even when the following Equal predicate exists:
5458// "%step == (sext ix (trunc iy to ix) to iy)".
5459bool PredicatedScalarEvolution::areAddRecsEqualWithPreds(
5460 const SCEVAddRecExpr *AR1, const SCEVAddRecExpr *AR2) const {
5461 if (AR1 == AR2)
5462 return true;
5463
5464 auto areExprsEqual = [&](const SCEV *Expr1, const SCEV *Expr2) -> bool {
5465 if (Expr1 != Expr2 && !Preds->implies(SE.getEqualPredicate(Expr1, Expr2)) &&
5466 !Preds->implies(SE.getEqualPredicate(Expr2, Expr1)))
5467 return false;
5468 return true;
5469 };
5470
5471 if (!areExprsEqual(AR1->getStart(), AR2->getStart()) ||
5472 !areExprsEqual(AR1->getStepRecurrence(SE), AR2->getStepRecurrence(SE)))
5473 return false;
5474 return true;
5475}
5476
5477/// A helper function for createAddRecFromPHI to handle simple cases.
5478///
5479/// This function tries to find an AddRec expression for the simplest (yet most
5480/// common) cases: PN = PHI(Start, OP(Self, LoopInvariant)).
5481/// If it fails, createAddRecFromPHI will use a more general, but slow,
5482/// technique for finding the AddRec expression.
5483const SCEV *ScalarEvolution::createSimpleAffineAddRec(PHINode *PN,
5484 Value *BEValueV,
5485 Value *StartValueV) {
5486 const Loop *L = LI.getLoopFor(PN->getParent());
5487 assert(L && L->getHeader() == PN->getParent())(static_cast <bool> (L && L->getHeader() == PN
->getParent()) ? void (0) : __assert_fail ("L && L->getHeader() == PN->getParent()"
, "llvm/lib/Analysis/ScalarEvolution.cpp", 5487, __extension__
__PRETTY_FUNCTION__));
5488 assert(BEValueV && StartValueV)(static_cast <bool> (BEValueV && StartValueV) ?
void (0) : __assert_fail ("BEValueV && StartValueV",
"llvm/lib/Analysis/ScalarEvolution.cpp", 5488, __extension__
__PRETTY_FUNCTION__));
5489
5490 auto BO = MatchBinaryOp(BEValueV, DT);
5491 if (!BO)
5492 return nullptr;
5493
5494 if (BO->Opcode != Instruction::Add)
5495 return nullptr;
5496
5497 const SCEV *Accum = nullptr;
5498 if (BO->LHS == PN && L->isLoopInvariant(BO->RHS))
5499 Accum = getSCEV(BO->RHS);
5500 else if (BO->RHS == PN && L->isLoopInvariant(BO->LHS))
5501 Accum = getSCEV(BO->LHS);
5502
5503 if (!Accum)
5504 return nullptr;
5505
5506 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
5507 if (BO->IsNUW)
5508 Flags = setFlags(Flags, SCEV::FlagNUW);
5509 if (BO->IsNSW)
5510 Flags = setFlags(Flags, SCEV::FlagNSW);
5511
5512 const SCEV *StartVal = getSCEV(StartValueV);
5513 const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
5514 insertValueToMap(PN, PHISCEV);
5515
5516 // We can add Flags to the post-inc expression only if we
5517 // know that it is *undefined behavior* for BEValueV to
5518 // overflow.
5519 if (auto *BEInst = dyn_cast<Instruction>(BEValueV)) {
5520 assert(isLoopInvariant(Accum, L) &&(static_cast <bool> (isLoopInvariant(Accum, L) &&
"Accum is defined outside L, but is not invariant?") ? void (
0) : __assert_fail ("isLoopInvariant(Accum, L) && \"Accum is defined outside L, but is not invariant?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 5521, __extension__
__PRETTY_FUNCTION__))
5521 "Accum is defined outside L, but is not invariant?")(static_cast <bool> (isLoopInvariant(Accum, L) &&
"Accum is defined outside L, but is not invariant?") ? void (
0) : __assert_fail ("isLoopInvariant(Accum, L) && \"Accum is defined outside L, but is not invariant?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 5521, __extension__
__PRETTY_FUNCTION__));
5522 if (isAddRecNeverPoison(BEInst, L))
5523 (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
5524 }
5525
5526 return PHISCEV;
5527}
5528
5529const SCEV *ScalarEvolution::createAddRecFromPHI(PHINode *PN) {
5530 const Loop *L = LI.getLoopFor(PN->getParent());
5531 if (!L || L->getHeader() != PN->getParent())
5532 return nullptr;
5533
5534 // The loop may have multiple entrances or multiple exits; we can analyze
5535 // this phi as an addrec if it has a unique entry value and a unique
5536 // backedge value.
5537 Value *BEValueV = nullptr, *StartValueV = nullptr;
5538 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
5539 Value *V = PN->getIncomingValue(i);
5540 if (L->contains(PN->getIncomingBlock(i))) {
5541 if (!BEValueV) {
5542 BEValueV = V;
5543 } else if (BEValueV != V) {
5544 BEValueV = nullptr;
5545 break;
5546 }
5547 } else if (!StartValueV) {
5548 StartValueV = V;
5549 } else if (StartValueV != V) {
5550 StartValueV = nullptr;
5551 break;
5552 }
5553 }
5554 if (!BEValueV || !StartValueV)
5555 return nullptr;
5556
5557 assert(ValueExprMap.find_as(PN) == ValueExprMap.end() &&(static_cast <bool> (ValueExprMap.find_as(PN) == ValueExprMap
.end() && "PHI node already processed?") ? void (0) :
__assert_fail ("ValueExprMap.find_as(PN) == ValueExprMap.end() && \"PHI node already processed?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 5558, __extension__
__PRETTY_FUNCTION__))
5558 "PHI node already processed?")(static_cast <bool> (ValueExprMap.find_as(PN) == ValueExprMap
.end() && "PHI node already processed?") ? void (0) :
__assert_fail ("ValueExprMap.find_as(PN) == ValueExprMap.end() && \"PHI node already processed?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 5558, __extension__
__PRETTY_FUNCTION__));
5559
5560 // First, try to find AddRec expression without creating a fictituos symbolic
5561 // value for PN.
5562 if (auto *S = createSimpleAffineAddRec(PN, BEValueV, StartValueV))
5563 return S;
5564
5565 // Handle PHI node value symbolically.
5566 const SCEV *SymbolicName = getUnknown(PN);
5567 insertValueToMap(PN, SymbolicName);
5568
5569 // Using this symbolic name for the PHI, analyze the value coming around
5570 // the back-edge.
5571 const SCEV *BEValue = getSCEV(BEValueV);
5572
5573 // NOTE: If BEValue is loop invariant, we know that the PHI node just
5574 // has a special value for the first iteration of the loop.
5575
5576 // If the value coming around the backedge is an add with the symbolic
5577 // value we just inserted, then we found a simple induction variable!
5578 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(BEValue)) {
5579 // If there is a single occurrence of the symbolic value, replace it
5580 // with a recurrence.
5581 unsigned FoundIndex = Add->getNumOperands();
5582 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
5583 if (Add->getOperand(i) == SymbolicName)
5584 if (FoundIndex == e) {
5585 FoundIndex = i;
5586 break;
5587 }
5588
5589 if (FoundIndex != Add->getNumOperands()) {
5590 // Create an add with everything but the specified operand.
5591 SmallVector<const SCEV *, 8> Ops;
5592 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
5593 if (i != FoundIndex)
5594 Ops.push_back(SCEVBackedgeConditionFolder::rewrite(Add->getOperand(i),
5595 L, *this));
5596 const SCEV *Accum = getAddExpr(Ops);
5597
5598 // This is not a valid addrec if the step amount is varying each
5599 // loop iteration, but is not itself an addrec in this loop.
5600 if (isLoopInvariant(Accum, L) ||
5601 (isa<SCEVAddRecExpr>(Accum) &&
5602 cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) {
5603 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
5604
5605 if (auto BO = MatchBinaryOp(BEValueV, DT)) {
5606 if (BO->Opcode == Instruction::Add && BO->LHS == PN) {
5607 if (BO->IsNUW)
5608 Flags = setFlags(Flags, SCEV::FlagNUW);
5609 if (BO->IsNSW)
5610 Flags = setFlags(Flags, SCEV::FlagNSW);
5611 }
5612 } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(BEValueV)) {
5613 // If the increment is an inbounds GEP, then we know the address
5614 // space cannot be wrapped around. We cannot make any guarantee
5615 // about signed or unsigned overflow because pointers are
5616 // unsigned but we may have a negative index from the base
5617 // pointer. We can guarantee that no unsigned wrap occurs if the
5618 // indices form a positive value.
5619 if (GEP->isInBounds() && GEP->getOperand(0) == PN) {
5620 Flags = setFlags(Flags, SCEV::FlagNW);
5621
5622 const SCEV *Ptr = getSCEV(GEP->getPointerOperand());
5623 if (isKnownPositive(getMinusSCEV(getSCEV(GEP), Ptr)))
5624 Flags = setFlags(Flags, SCEV::FlagNUW);
5625 }
5626
5627 // We cannot transfer nuw and nsw flags from subtraction
5628 // operations -- sub nuw X, Y is not the same as add nuw X, -Y
5629 // for instance.
5630 }
5631
5632 const SCEV *StartVal = getSCEV(StartValueV);
5633 const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
5634
5635 // Okay, for the entire analysis of this edge we assumed the PHI
5636 // to be symbolic. We now need to go back and purge all of the
5637 // entries for the scalars that use the symbolic expression.
5638 forgetMemoizedResults(SymbolicName);
5639 insertValueToMap(PN, PHISCEV);
5640
5641 // We can add Flags to the post-inc expression only if we
5642 // know that it is *undefined behavior* for BEValueV to
5643 // overflow.
5644 if (auto *BEInst = dyn_cast<Instruction>(BEValueV))
5645 if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L))
5646 (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
5647
5648 return PHISCEV;
5649 }
5650 }
5651 } else {
5652 // Otherwise, this could be a loop like this:
5653 // i = 0; for (j = 1; ..; ++j) { .... i = j; }
5654 // In this case, j = {1,+,1} and BEValue is j.
5655 // Because the other in-value of i (0) fits the evolution of BEValue
5656 // i really is an addrec evolution.
5657 //
5658 // We can generalize this saying that i is the shifted value of BEValue
5659 // by one iteration:
5660 // PHI(f(0), f({1,+,1})) --> f({0,+,1})
5661 const SCEV *Shifted = SCEVShiftRewriter::rewrite(BEValue, L, *this);
5662 const SCEV *Start = SCEVInitRewriter::rewrite(Shifted, L, *this, false);
5663 if (Shifted != getCouldNotCompute() &&
5664 Start != getCouldNotCompute()) {
5665 const SCEV *StartVal = getSCEV(StartValueV);
5666 if (Start == StartVal) {
5667 // Okay, for the entire analysis of this edge we assumed the PHI
5668 // to be symbolic. We now need to go back and purge all of the
5669 // entries for the scalars that use the symbolic expression.
5670 forgetMemoizedResults(SymbolicName);
5671 insertValueToMap(PN, Shifted);
5672 return Shifted;
5673 }
5674 }
5675 }
5676
5677 // Remove the temporary PHI node SCEV that has been inserted while intending
5678 // to create an AddRecExpr for this PHI node. We can not keep this temporary
5679 // as it will prevent later (possibly simpler) SCEV expressions to be added
5680 // to the ValueExprMap.
5681 eraseValueFromMap(PN);
5682
5683 return nullptr;
5684}
5685
5686// Checks if the SCEV S is available at BB. S is considered available at BB
5687// if S can be materialized at BB without introducing a fault.
5688static bool IsAvailableOnEntry(const Loop *L, DominatorTree &DT, const SCEV *S,
5689 BasicBlock *BB) {
5690 struct CheckAvailable {
5691 bool TraversalDone = false;
5692 bool Available = true;
5693
5694 const Loop *L = nullptr; // The loop BB is in (can be nullptr)
5695 BasicBlock *BB = nullptr;
5696 DominatorTree &DT;
5697
5698 CheckAvailable(const Loop *L, BasicBlock *BB, DominatorTree &DT)
5699 : L(L), BB(BB), DT(DT) {}
5700
5701 bool setUnavailable() {
5702 TraversalDone = true;
5703 Available = false;
5704 return false;
5705 }
5706
5707 bool follow(const SCEV *S) {
5708 switch (S->getSCEVType()) {
5709 case scConstant:
5710 case scPtrToInt:
5711 case scTruncate:
5712 case scZeroExtend:
5713 case scSignExtend:
5714 case scAddExpr:
5715 case scMulExpr:
5716 case scUMaxExpr:
5717 case scSMaxExpr:
5718 case scUMinExpr:
5719 case scSMinExpr:
5720 case scSequentialUMinExpr:
5721 // These expressions are available if their operand(s) is/are.
5722 return true;
5723
5724 case scAddRecExpr: {
5725 // We allow add recurrences that are on the loop BB is in, or some
5726 // outer loop. This guarantees availability because the value of the
5727 // add recurrence at BB is simply the "current" value of the induction
5728 // variable. We can relax this in the future; for instance an add
5729 // recurrence on a sibling dominating loop is also available at BB.
5730 const auto *ARLoop = cast<SCEVAddRecExpr>(S)->getLoop();
5731 if (L && (ARLoop == L || ARLoop->contains(L)))
5732 return true;
5733
5734 return setUnavailable();
5735 }
5736
5737 case scUnknown: {
5738 // For SCEVUnknown, we check for simple dominance.
5739 const auto *SU = cast<SCEVUnknown>(S);
5740 Value *V = SU->getValue();
5741
5742 if (isa<Argument>(V))
5743 return false;
5744
5745 if (isa<Instruction>(V) && DT.dominates(cast<Instruction>(V), BB))
5746 return false;
5747
5748 return setUnavailable();
5749 }
5750
5751 case scUDivExpr:
5752 case scCouldNotCompute:
5753 // We do not try to smart about these at all.
5754 return setUnavailable();
5755 }
5756 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 5756);
5757 }
5758
5759 bool isDone() { return TraversalDone; }
5760 };
5761
5762 CheckAvailable CA(L, BB, DT);
5763 SCEVTraversal<CheckAvailable> ST(CA);
5764
5765 ST.visitAll(S);
5766 return CA.Available;
5767}
5768
5769// Try to match a control flow sequence that branches out at BI and merges back
5770// at Merge into a "C ? LHS : RHS" select pattern. Return true on a successful
5771// match.
5772static bool BrPHIToSelect(DominatorTree &DT, BranchInst *BI, PHINode *Merge,
5773 Value *&C, Value *&LHS, Value *&RHS) {
5774 C = BI->getCondition();
5775
5776 BasicBlockEdge LeftEdge(BI->getParent(), BI->getSuccessor(0));
5777 BasicBlockEdge RightEdge(BI->getParent(), BI->getSuccessor(1));
5778
5779 if (!LeftEdge.isSingleEdge())
5780 return false;
5781
5782 assert(RightEdge.isSingleEdge() && "Follows from LeftEdge.isSingleEdge()")(static_cast <bool> (RightEdge.isSingleEdge() &&
"Follows from LeftEdge.isSingleEdge()") ? void (0) : __assert_fail
("RightEdge.isSingleEdge() && \"Follows from LeftEdge.isSingleEdge()\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 5782, __extension__
__PRETTY_FUNCTION__));
5783
5784 Use &LeftUse = Merge->getOperandUse(0);
5785 Use &RightUse = Merge->getOperandUse(1);
5786
5787 if (DT.dominates(LeftEdge, LeftUse) && DT.dominates(RightEdge, RightUse)) {
5788 LHS = LeftUse;
5789 RHS = RightUse;
5790 return true;
5791 }
5792
5793 if (DT.dominates(LeftEdge, RightUse) && DT.dominates(RightEdge, LeftUse)) {
5794 LHS = RightUse;
5795 RHS = LeftUse;
5796 return true;
5797 }
5798
5799 return false;
5800}
5801
5802const SCEV *ScalarEvolution::createNodeFromSelectLikePHI(PHINode *PN) {
5803 auto IsReachable =
5804 [&](BasicBlock *BB) { return DT.isReachableFromEntry(BB); };
5805 if (PN->getNumIncomingValues() == 2 && all_of(PN->blocks(), IsReachable)) {
5806 const Loop *L = LI.getLoopFor(PN->getParent());
5807
5808 // We don't want to break LCSSA, even in a SCEV expression tree.
5809 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
5810 if (LI.getLoopFor(PN->getIncomingBlock(i)) != L)
5811 return nullptr;
5812
5813 // Try to match
5814 //
5815 // br %cond, label %left, label %right
5816 // left:
5817 // br label %merge
5818 // right:
5819 // br label %merge
5820 // merge:
5821 // V = phi [ %x, %left ], [ %y, %right ]
5822 //
5823 // as "select %cond, %x, %y"
5824
5825 BasicBlock *IDom = DT[PN->getParent()]->getIDom()->getBlock();
5826 assert(IDom && "At least the entry block should dominate PN")(static_cast <bool> (IDom && "At least the entry block should dominate PN"
) ? void (0) : __assert_fail ("IDom && \"At least the entry block should dominate PN\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 5826, __extension__
__PRETTY_FUNCTION__));
5827
5828 auto *BI = dyn_cast<BranchInst>(IDom->getTerminator());
5829 Value *Cond = nullptr, *LHS = nullptr, *RHS = nullptr;
5830
5831 if (BI && BI->isConditional() &&
5832 BrPHIToSelect(DT, BI, PN, Cond, LHS, RHS) &&
5833 IsAvailableOnEntry(L, DT, getSCEV(LHS), PN->getParent()) &&
5834 IsAvailableOnEntry(L, DT, getSCEV(RHS), PN->getParent()))
5835 return createNodeForSelectOrPHI(PN, Cond, LHS, RHS);
5836 }
5837
5838 return nullptr;
5839}
5840
5841const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) {
5842 if (const SCEV *S = createAddRecFromPHI(PN))
5843 return S;
5844
5845 if (const SCEV *S = createNodeFromSelectLikePHI(PN))
5846 return S;
5847
5848 // If the PHI has a single incoming value, follow that value, unless the
5849 // PHI's incoming blocks are in a different loop, in which case doing so
5850 // risks breaking LCSSA form. Instcombine would normally zap these, but
5851 // it doesn't have DominatorTree information, so it may miss cases.
5852 if (Value *V = SimplifyInstruction(PN, {getDataLayout(), &TLI, &DT, &AC}))
5853 if (LI.replacementPreservesLCSSAForm(PN, V))
5854 return getSCEV(V);
5855
5856 // If it's not a loop phi, we can't handle it yet.
5857 return getUnknown(PN);
5858}
5859
5860bool SCEVMinMaxExprContains(const SCEV *Root, const SCEV *OperandToFind,
5861 SCEVTypes RootKind) {
5862 struct FindClosure {
5863 const SCEV *OperandToFind;
5864 const SCEVTypes RootKind; // Must be a sequential min/max expression.
5865 const SCEVTypes NonSequentialRootKind; // Non-seq variant of RootKind.
5866
5867 bool Found = false;
5868
5869 bool canRecurseInto(SCEVTypes Kind) const {
5870 // We can only recurse into the SCEV expression of the same effective type
5871 // as the type of our root SCEV expression, and into zero-extensions.
5872 return RootKind == Kind || NonSequentialRootKind == Kind ||
5873 scZeroExtend == Kind;
5874 };
5875
5876 FindClosure(const SCEV *OperandToFind, SCEVTypes RootKind)
5877 : OperandToFind(OperandToFind), RootKind(RootKind),
5878 NonSequentialRootKind(
5879 SCEVSequentialMinMaxExpr::getEquivalentNonSequentialSCEVType(
5880 RootKind)) {}
5881
5882 bool follow(const SCEV *S) {
5883 Found = S == OperandToFind;
5884
5885 return !isDone() && canRecurseInto(S->getSCEVType());
5886 }
5887
5888 bool isDone() const { return Found; }
5889 };
5890
5891 FindClosure FC(OperandToFind, RootKind);
5892 visitAll(Root, FC);
5893 return FC.Found;
5894}
5895
5896const SCEV *ScalarEvolution::createNodeForSelectOrPHIInstWithICmpInstCond(
5897 Instruction *I, ICmpInst *Cond, Value *TrueVal, Value *FalseVal) {
5898 // Try to match some simple smax or umax patterns.
5899 auto *ICI = Cond;
5900
5901 Value *LHS = ICI->getOperand(0);
5902 Value *RHS = ICI->getOperand(1);
5903
5904 switch (ICI->getPredicate()) {
5905 case ICmpInst::ICMP_SLT:
5906 case ICmpInst::ICMP_SLE:
5907 case ICmpInst::ICMP_ULT:
5908 case ICmpInst::ICMP_ULE:
5909 std::swap(LHS, RHS);
5910 LLVM_FALLTHROUGH[[gnu::fallthrough]];
5911 case ICmpInst::ICMP_SGT:
5912 case ICmpInst::ICMP_SGE:
5913 case ICmpInst::ICMP_UGT:
5914 case ICmpInst::ICMP_UGE:
5915 // a > b ? a+x : b+x -> max(a, b)+x
5916 // a > b ? b+x : a+x -> min(a, b)+x
5917 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
5918 bool Signed = ICI->isSigned();
5919 const SCEV *LA = getSCEV(TrueVal);
5920 const SCEV *RA = getSCEV(FalseVal);
5921 const SCEV *LS = getSCEV(LHS);
5922 const SCEV *RS = getSCEV(RHS);
5923 if (LA->getType()->isPointerTy()) {
5924 // FIXME: Handle cases where LS/RS are pointers not equal to LA/RA.
5925 // Need to make sure we can't produce weird expressions involving
5926 // negated pointers.
5927 if (LA == LS && RA == RS)
5928 return Signed ? getSMaxExpr(LS, RS) : getUMaxExpr(LS, RS);
5929 if (LA == RS && RA == LS)
5930 return Signed ? getSMinExpr(LS, RS) : getUMinExpr(LS, RS);
5931 }
5932 auto CoerceOperand = [&](const SCEV *Op) -> const SCEV * {
5933 if (Op->getType()->isPointerTy()) {
5934 Op = getLosslessPtrToIntExpr(Op);
5935 if (isa<SCEVCouldNotCompute>(Op))
5936 return Op;
5937 }
5938 if (Signed)
5939 Op = getNoopOrSignExtend(Op, I->getType());
5940 else
5941 Op = getNoopOrZeroExtend(Op, I->getType());
5942 return Op;
5943 };
5944 LS = CoerceOperand(LS);
5945 RS = CoerceOperand(RS);
5946 if (isa<SCEVCouldNotCompute>(LS) || isa<SCEVCouldNotCompute>(RS))
5947 break;
5948 const SCEV *LDiff = getMinusSCEV(LA, LS);
5949 const SCEV *RDiff = getMinusSCEV(RA, RS);
5950 if (LDiff == RDiff)
5951 return getAddExpr(Signed ? getSMaxExpr(LS, RS) : getUMaxExpr(LS, RS),
5952 LDiff);
5953 LDiff = getMinusSCEV(LA, RS);
5954 RDiff = getMinusSCEV(RA, LS);
5955 if (LDiff == RDiff)
5956 return getAddExpr(Signed ? getSMinExpr(LS, RS) : getUMinExpr(LS, RS),
5957 LDiff);
5958 }
5959 break;
5960 case ICmpInst::ICMP_NE:
5961 // x != 0 ? x+y : C+y -> x == 0 ? C+y : x+y
5962 std::swap(TrueVal, FalseVal);
5963 LLVM_FALLTHROUGH[[gnu::fallthrough]];
5964 case ICmpInst::ICMP_EQ:
5965 // x == 0 ? C+y : x+y -> umax(x, C)+y iff C u<= 1
5966 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
5967 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
5968 const SCEV *X = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5969 const SCEV *TrueValExpr = getSCEV(TrueVal); // C+y
5970 const SCEV *FalseValExpr = getSCEV(FalseVal); // x+y
5971 const SCEV *Y = getMinusSCEV(FalseValExpr, X); // y = (x+y)-x
5972 const SCEV *C = getMinusSCEV(TrueValExpr, Y); // C = (C+y)-y
5973 if (isa<SCEVConstant>(C) && cast<SCEVConstant>(C)->getAPInt().ule(1))
5974 return getAddExpr(getUMaxExpr(X, C), Y);
5975 }
5976 // x == 0 ? 0 : umin (..., x, ...) -> umin_seq(x, umin (...))
5977 // x == 0 ? 0 : umin_seq(..., x, ...) -> umin_seq(x, umin_seq(...))
5978 // x == 0 ? 0 : umin (..., umin_seq(..., x, ...), ...)
5979 // -> umin_seq(x, umin (..., umin_seq(...), ...))
5980 if (isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero() &&
5981 isa<ConstantInt>(TrueVal) && cast<ConstantInt>(TrueVal)->isZero()) {
5982 const SCEV *X = getSCEV(LHS);
5983 while (auto *ZExt = dyn_cast<SCEVZeroExtendExpr>(X))
5984 X = ZExt->getOperand();
5985 if (getTypeSizeInBits(X->getType()) <= getTypeSizeInBits(I->getType())) {
5986 const SCEV *FalseValExpr = getSCEV(FalseVal);
5987 if (SCEVMinMaxExprContains(FalseValExpr, X, scSequentialUMinExpr))
5988 return getUMinExpr(getNoopOrZeroExtend(X, I->getType()), FalseValExpr,
5989 /*Sequential=*/true);
5990 }
5991 }
5992 break;
5993 default:
5994 break;
5995 }
5996
5997 return getUnknown(I);
5998}
5999
6000const SCEV *ScalarEvolution::createNodeForSelectOrPHIViaUMinSeq(
6001 Value *V, Value *Cond, Value *TrueVal, Value *FalseVal) {
6002 // For now, only deal with i1-typed `select`s.
6003 if (!V->getType()->isIntegerTy(1) || !Cond->getType()->isIntegerTy(1) ||
6004 !TrueVal->getType()->isIntegerTy(1) ||
6005 !FalseVal->getType()->isIntegerTy(1))
6006 return getUnknown(V);
6007
6008 // i1 cond ? i1 x : i1 C --> C + (i1 cond ? (i1 x - i1 C) : i1 0)
6009 // --> C + (umin_seq cond, x - C)
6010 //
6011 // i1 cond ? i1 C : i1 x --> C + (i1 cond ? i1 0 : (i1 x - i1 C))
6012 // --> C + (i1 ~cond ? (i1 x - i1 C) : i1 0)
6013 // --> C + (umin_seq ~cond, x - C)
6014 if (isa<ConstantInt>(TrueVal) || isa<ConstantInt>(FalseVal)) {
6015 const SCEV *CondExpr = getSCEV(Cond);
6016 const SCEV *TrueExpr = getSCEV(TrueVal);
6017 const SCEV *FalseExpr = getSCEV(FalseVal);
6018 const SCEV *X, *C;
6019 if (isa<ConstantInt>(TrueVal)) {
6020 CondExpr = getNotSCEV(CondExpr);
6021 X = FalseExpr;
6022 C = TrueExpr;
6023 } else {
6024 X = TrueExpr;
6025 C = FalseExpr;
6026 }
6027 return getAddExpr(
6028 C, getUMinExpr(CondExpr, getMinusSCEV(X, C), /*Sequential=*/true));
6029 }
6030
6031 return getUnknown(V);
6032}
6033
6034const SCEV *ScalarEvolution::createNodeForSelectOrPHI(Value *V, Value *Cond,
6035 Value *TrueVal,
6036 Value *FalseVal) {
6037 // Handle "constant" branch or select. This can occur for instance when a
6038 // loop pass transforms an inner loop and moves on to process the outer loop.
6039 if (auto *CI = dyn_cast<ConstantInt>(Cond))
6040 return getSCEV(CI->isOne() ? TrueVal : FalseVal);
6041
6042 if (auto *I = dyn_cast<Instruction>(V)) {
6043 if (auto *ICI = dyn_cast<ICmpInst>(Cond)) {
6044 const SCEV *S = createNodeForSelectOrPHIInstWithICmpInstCond(
6045 I, ICI, TrueVal, FalseVal);
6046 if (!isa<SCEVUnknown>(S))
6047 return S;
6048 }
6049 }
6050
6051 return createNodeForSelectOrPHIViaUMinSeq(V, Cond, TrueVal, FalseVal);
6052}
6053
6054/// Expand GEP instructions into add and multiply operations. This allows them
6055/// to be analyzed by regular SCEV code.
6056const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) {
6057 // Don't attempt to analyze GEPs over unsized objects.
6058 if (!GEP->getSourceElementType()->isSized())
6059 return getUnknown(GEP);
6060
6061 SmallVector<const SCEV *, 4> IndexExprs;
6062 for (Value *Index : GEP->indices())
6063 IndexExprs.push_back(getSCEV(Index));
6064 return getGEPExpr(GEP, IndexExprs);
6065}
6066
6067uint32_t ScalarEvolution::GetMinTrailingZerosImpl(const SCEV *S) {
6068 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
6069 return C->getAPInt().countTrailingZeros();
6070
6071 if (const SCEVPtrToIntExpr *I = dyn_cast<SCEVPtrToIntExpr>(S))
6072 return GetMinTrailingZeros(I->getOperand());
6073
6074 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(S))
6075 return std::min(GetMinTrailingZeros(T->getOperand()),
6076 (uint32_t)getTypeSizeInBits(T->getType()));
6077
6078 if (const SCEVZeroExtendExpr *E = dyn_cast<SCEVZeroExtendExpr>(S)) {
6079 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
6080 return OpRes == getTypeSizeInBits(E->getOperand()->getType())
6081 ? getTypeSizeInBits(E->getType())
6082 : OpRes;
6083 }
6084
6085 if (const SCEVSignExtendExpr *E = dyn_cast<SCEVSignExtendExpr>(S)) {
6086 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
6087 return OpRes == getTypeSizeInBits(E->getOperand()->getType())
6088 ? getTypeSizeInBits(E->getType())
6089 : OpRes;
6090 }
6091
6092 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) {
6093 // The result is the min of all operands results.
6094 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
6095 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
6096 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
6097 return MinOpRes;
6098 }
6099
6100 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
6101 // The result is the sum of all operands results.
6102 uint32_t SumOpRes = GetMinTrailingZeros(M->getOperand(0));
6103 uint32_t BitWidth = getTypeSizeInBits(M->getType());
6104 for (unsigned i = 1, e = M->getNumOperands();
6105 SumOpRes != BitWidth && i != e; ++i)
6106 SumOpRes =
6107 std::min(SumOpRes + GetMinTrailingZeros(M->getOperand(i)), BitWidth);
6108 return SumOpRes;
6109 }
6110
6111 if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
6112 // The result is the min of all operands results.
6113 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
6114 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
6115 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
6116 return MinOpRes;
6117 }
6118
6119 if (const SCEVSMaxExpr *M = dyn_cast<SCEVSMaxExpr>(S)) {
6120 // The result is the min of all operands results.
6121 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
6122 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
6123 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
6124 return MinOpRes;
6125 }
6126
6127 if (const SCEVUMaxExpr *M = dyn_cast<SCEVUMaxExpr>(S)) {
6128 // The result is the min of all operands results.
6129 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
6130 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
6131 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
6132 return MinOpRes;
6133 }
6134
6135 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
6136 // For a SCEVUnknown, ask ValueTracking.
6137 KnownBits Known = computeKnownBits(U->getValue(), getDataLayout(), 0, &AC, nullptr, &DT);
6138 return Known.countMinTrailingZeros();
6139 }
6140
6141 // SCEVUDivExpr
6142 return 0;
6143}
6144
6145uint32_t ScalarEvolution::GetMinTrailingZeros(const SCEV *S) {
6146 auto I = MinTrailingZerosCache.find(S);
6147 if (I != MinTrailingZerosCache.end())
6148 return I->second;
6149
6150 uint32_t Result = GetMinTrailingZerosImpl(S);
6151 auto InsertPair = MinTrailingZerosCache.insert({S, Result});
6152 assert(InsertPair.second && "Should insert a new key")(static_cast <bool> (InsertPair.second && "Should insert a new key"
) ? void (0) : __assert_fail ("InsertPair.second && \"Should insert a new key\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 6152, __extension__
__PRETTY_FUNCTION__));
6153 return InsertPair.first->second;
6154}
6155
6156/// Helper method to assign a range to V from metadata present in the IR.
6157static Optional<ConstantRange> GetRangeFromMetadata(Value *V) {
6158 if (Instruction *I = dyn_cast<Instruction>(V))
6159 if (MDNode *MD = I->getMetadata(LLVMContext::MD_range))
6160 return getConstantRangeFromMetadata(*MD);
6161
6162 return None;
6163}
6164
6165void ScalarEvolution::setNoWrapFlags(SCEVAddRecExpr *AddRec,
6166 SCEV::NoWrapFlags Flags) {
6167 if (AddRec->getNoWrapFlags(Flags) != Flags) {
6168 AddRec->setNoWrapFlags(Flags);
6169 UnsignedRanges.erase(AddRec);
6170 SignedRanges.erase(AddRec);
6171 }
6172}
6173
6174ConstantRange ScalarEvolution::
6175getRangeForUnknownRecurrence(const SCEVUnknown *U) {
6176 const DataLayout &DL = getDataLayout();
6177
6178 unsigned BitWidth = getTypeSizeInBits(U->getType());
6179 const ConstantRange FullSet(BitWidth, /*isFullSet=*/true);
6180
6181 // Match a simple recurrence of the form: <start, ShiftOp, Step>, and then
6182 // use information about the trip count to improve our available range. Note
6183 // that the trip count independent cases are already handled by known bits.
6184 // WARNING: The definition of recurrence used here is subtly different than
6185 // the one used by AddRec (and thus most of this file). Step is allowed to
6186 // be arbitrarily loop varying here, where AddRec allows only loop invariant
6187 // and other addrecs in the same loop (for non-affine addrecs). The code
6188 // below intentionally handles the case where step is not loop invariant.
6189 auto *P = dyn_cast<PHINode>(U->getValue());
6190 if (!P)
6191 return FullSet;
6192
6193 // Make sure that no Phi input comes from an unreachable block. Otherwise,
6194 // even the values that are not available in these blocks may come from them,
6195 // and this leads to false-positive recurrence test.
6196 for (auto *Pred : predecessors(P->getParent()))
6197 if (!DT.isReachableFromEntry(Pred))
6198 return FullSet;
6199
6200 BinaryOperator *BO;
6201 Value *Start, *Step;
6202 if (!matchSimpleRecurrence(P, BO, Start, Step))
6203 return FullSet;
6204
6205 // If we found a recurrence in reachable code, we must be in a loop. Note
6206 // that BO might be in some subloop of L, and that's completely okay.
6207 auto *L = LI.getLoopFor(P->getParent());
6208 assert(L && L->getHeader() == P->getParent())(static_cast <bool> (L && L->getHeader() == P
->getParent()) ? void (0) : __assert_fail ("L && L->getHeader() == P->getParent()"
, "llvm/lib/Analysis/ScalarEvolution.cpp", 6208, __extension__
__PRETTY_FUNCTION__));
6209 if (!L->contains(BO->getParent()))
6210 // NOTE: This bailout should be an assert instead. However, asserting
6211 // the condition here exposes a case where LoopFusion is querying SCEV
6212 // with malformed loop information during the midst of the transform.
6213 // There doesn't appear to be an obvious fix, so for the moment bailout
6214 // until the caller issue can be fixed. PR49566 tracks the bug.
6215 return FullSet;
6216
6217 // TODO: Extend to other opcodes such as mul, and div
6218 switch (BO->getOpcode()) {
6219 default:
6220 return FullSet;
6221 case Instruction::AShr:
6222 case Instruction::LShr:
6223 case Instruction::Shl:
6224 break;
6225 };
6226
6227 if (BO->getOperand(0) != P)
6228 // TODO: Handle the power function forms some day.
6229 return FullSet;
6230
6231 unsigned TC = getSmallConstantMaxTripCount(L);
6232 if (!TC || TC >= BitWidth)
6233 return FullSet;
6234
6235 auto KnownStart = computeKnownBits(Start, DL, 0, &AC, nullptr, &DT);
6236 auto KnownStep = computeKnownBits(Step, DL, 0, &AC, nullptr, &DT);
6237 assert(KnownStart.getBitWidth() == BitWidth &&(static_cast <bool> (KnownStart.getBitWidth() == BitWidth
&& KnownStep.getBitWidth() == BitWidth) ? void (0) :
__assert_fail ("KnownStart.getBitWidth() == BitWidth && KnownStep.getBitWidth() == BitWidth"
, "llvm/lib/Analysis/ScalarEvolution.cpp", 6238, __extension__
__PRETTY_FUNCTION__))
6238 KnownStep.getBitWidth() == BitWidth)(static_cast <bool> (KnownStart.getBitWidth() == BitWidth
&& KnownStep.getBitWidth() == BitWidth) ? void (0) :
__assert_fail ("KnownStart.getBitWidth() == BitWidth && KnownStep.getBitWidth() == BitWidth"
, "llvm/lib/Analysis/ScalarEvolution.cpp", 6238, __extension__
__PRETTY_FUNCTION__));
6239
6240 // Compute total shift amount, being careful of overflow and bitwidths.
6241 auto MaxShiftAmt = KnownStep.getMaxValue();
6242 APInt TCAP(BitWidth, TC-1);
6243 bool Overflow = false;
6244 auto TotalShift = MaxShiftAmt.umul_ov(TCAP, Overflow);
6245 if (Overflow)
6246 return FullSet;
6247
6248 switch (BO->getOpcode()) {
6249 default:
6250 llvm_unreachable("filtered out above")::llvm::llvm_unreachable_internal("filtered out above", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 6250);
6251 case Instruction::AShr: {
6252 // For each ashr, three cases:
6253 // shift = 0 => unchanged value
6254 // saturation => 0 or -1
6255 // other => a value closer to zero (of the same sign)
6256 // Thus, the end value is closer to zero than the start.
6257 auto KnownEnd = KnownBits::ashr(KnownStart,
6258 KnownBits::makeConstant(TotalShift));
6259 if (KnownStart.isNonNegative())
6260 // Analogous to lshr (simply not yet canonicalized)
6261 return ConstantRange::getNonEmpty(KnownEnd.getMinValue(),
6262 KnownStart.getMaxValue() + 1);
6263 if (KnownStart.isNegative())
6264 // End >=u Start && End <=s Start
6265 return ConstantRange::getNonEmpty(KnownStart.getMinValue(),
6266 KnownEnd.getMaxValue() + 1);
6267 break;
6268 }
6269 case Instruction::LShr: {
6270 // For each lshr, three cases:
6271 // shift = 0 => unchanged value
6272 // saturation => 0
6273 // other => a smaller positive number
6274 // Thus, the low end of the unsigned range is the last value produced.
6275 auto KnownEnd = KnownBits::lshr(KnownStart,
6276 KnownBits::makeConstant(TotalShift));
6277 return ConstantRange::getNonEmpty(KnownEnd.getMinValue(),
6278 KnownStart.getMaxValue() + 1);
6279 }
6280 case Instruction::Shl: {
6281 // Iff no bits are shifted out, value increases on every shift.
6282 auto KnownEnd = KnownBits::shl(KnownStart,
6283 KnownBits::makeConstant(TotalShift));
6284 if (TotalShift.ult(KnownStart.countMinLeadingZeros()))
6285 return ConstantRange(KnownStart.getMinValue(),
6286 KnownEnd.getMaxValue() + 1);
6287 break;
6288 }
6289 };
6290 return FullSet;
6291}
6292
6293/// Determine the range for a particular SCEV. If SignHint is
6294/// HINT_RANGE_UNSIGNED (resp. HINT_RANGE_SIGNED) then getRange prefers ranges
6295/// with a "cleaner" unsigned (resp. signed) representation.
6296const ConstantRange &
6297ScalarEvolution::getRangeRef(const SCEV *S,
6298 ScalarEvolution::RangeSignHint SignHint) {
6299 DenseMap<const SCEV *, ConstantRange> &Cache =
6300 SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED ? UnsignedRanges
6301 : SignedRanges;
6302 ConstantRange::PreferredRangeType RangeType =
6303 SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED
6304 ? ConstantRange::Unsigned : ConstantRange::Signed;
6305
6306 // See if we've computed this range already.
6307 DenseMap<const SCEV *, ConstantRange>::iterator I = Cache.find(S);
6308 if (I != Cache.end())
6309 return I->second;
6310
6311 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
6312 return setRange(C, SignHint, ConstantRange(C->getAPInt()));
6313
6314 unsigned BitWidth = getTypeSizeInBits(S->getType());
6315 ConstantRange ConservativeResult(BitWidth, /*isFullSet=*/true);
6316 using OBO = OverflowingBinaryOperator;
6317
6318 // If the value has known zeros, the maximum value will have those known zeros
6319 // as well.
6320 uint32_t TZ = GetMinTrailingZeros(S);
6321 if (TZ != 0) {
6322 if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED)
6323 ConservativeResult =
6324 ConstantRange(APInt::getMinValue(BitWidth),
6325 APInt::getMaxValue(BitWidth).lshr(TZ).shl(TZ) + 1);
6326 else
6327 ConservativeResult = ConstantRange(
6328 APInt::getSignedMinValue(BitWidth),
6329 APInt::getSignedMaxValue(BitWidth).ashr(TZ).shl(TZ) + 1);
6330 }
6331
6332 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
6333 ConstantRange X = getRangeRef(Add->getOperand(0), SignHint);
6334 unsigned WrapType = OBO::AnyWrap;
6335 if (Add->hasNoSignedWrap())
6336 WrapType |= OBO::NoSignedWrap;
6337 if (Add->hasNoUnsignedWrap())
6338 WrapType |= OBO::NoUnsignedWrap;
6339 for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i)
6340 X = X.addWithNoWrap(getRangeRef(Add->getOperand(i), SignHint),
6341 WrapType, RangeType);
6342 return setRange(Add, SignHint,
6343 ConservativeResult.intersectWith(X, RangeType));
6344 }
6345
6346 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
6347 ConstantRange X = getRangeRef(Mul->getOperand(0), SignHint);
6348 for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i)
6349 X = X.multiply(getRangeRef(Mul->getOperand(i), SignHint));
6350 return setRange(Mul, SignHint,
6351 ConservativeResult.intersectWith(X, RangeType));
6352 }
6353
6354 if (isa<SCEVMinMaxExpr>(S) || isa<SCEVSequentialMinMaxExpr>(S)) {
6355 Intrinsic::ID ID;
6356 switch (S->getSCEVType()) {
6357 case scUMaxExpr:
6358 ID = Intrinsic::umax;
6359 break;
6360 case scSMaxExpr:
6361 ID = Intrinsic::smax;
6362 break;
6363 case scUMinExpr:
6364 case scSequentialUMinExpr:
6365 ID = Intrinsic::umin;
6366 break;
6367 case scSMinExpr:
6368 ID = Intrinsic::smin;
6369 break;
6370 default:
6371 llvm_unreachable("Unknown SCEVMinMaxExpr/SCEVSequentialMinMaxExpr.")::llvm::llvm_unreachable_internal("Unknown SCEVMinMaxExpr/SCEVSequentialMinMaxExpr."
, "llvm/lib/Analysis/ScalarEvolution.cpp", 6371);
6372 }
6373
6374 const auto *NAry = cast<SCEVNAryExpr>(S);
6375 ConstantRange X = getRangeRef(NAry->getOperand(0), SignHint);
6376 for (unsigned i = 1, e = NAry->getNumOperands(); i != e; ++i)
6377 X = X.intrinsic(ID, {X, getRangeRef(NAry->getOperand(i), SignHint)});
6378 return setRange(S, SignHint,
6379 ConservativeResult.intersectWith(X, RangeType));
6380 }
6381
6382 if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) {
6383 ConstantRange X = getRangeRef(UDiv->getLHS(), SignHint);
6384 ConstantRange Y = getRangeRef(UDiv->getRHS(), SignHint);
6385 return setRange(UDiv, SignHint,
6386 ConservativeResult.intersectWith(X.udiv(Y), RangeType));
6387 }
6388
6389 if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) {
6390 ConstantRange X = getRangeRef(ZExt->getOperand(), SignHint);
6391 return setRange(ZExt, SignHint,
6392 ConservativeResult.intersectWith(X.zeroExtend(BitWidth),
6393 RangeType));
6394 }
6395
6396 if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) {
6397 ConstantRange X = getRangeRef(SExt->getOperand(), SignHint);
6398 return setRange(SExt, SignHint,
6399 ConservativeResult.intersectWith(X.signExtend(BitWidth),
6400 RangeType));
6401 }
6402
6403 if (const SCEVPtrToIntExpr *PtrToInt = dyn_cast<SCEVPtrToIntExpr>(S)) {
6404 ConstantRange X = getRangeRef(PtrToInt->getOperand(), SignHint);
6405 return setRange(PtrToInt, SignHint, X);
6406 }
6407
6408 if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) {
6409 ConstantRange X = getRangeRef(Trunc->getOperand(), SignHint);
6410 return setRange(Trunc, SignHint,
6411 ConservativeResult.intersectWith(X.truncate(BitWidth),
6412 RangeType));
6413 }
6414
6415 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) {
6416 // If there's no unsigned wrap, the value will never be less than its
6417 // initial value.
6418 if (AddRec->hasNoUnsignedWrap()) {
6419 APInt UnsignedMinValue = getUnsignedRangeMin(AddRec->getStart());
6420 if (!UnsignedMinValue.isZero())
6421 ConservativeResult = ConservativeResult.intersectWith(
6422 ConstantRange(UnsignedMinValue, APInt(BitWidth, 0)), RangeType);
6423 }
6424
6425 // If there's no signed wrap, and all the operands except initial value have
6426 // the same sign or zero, the value won't ever be:
6427 // 1: smaller than initial value if operands are non negative,
6428 // 2: bigger than initial value if operands are non positive.
6429 // For both cases, value can not cross signed min/max boundary.
6430 if (AddRec->hasNoSignedWrap()) {
6431 bool AllNonNeg = true;
6432 bool AllNonPos = true;
6433 for (unsigned i = 1, e = AddRec->getNumOperands(); i != e; ++i) {
6434 if (!isKnownNonNegative(AddRec->getOperand(i)))
6435 AllNonNeg = false;
6436 if (!isKnownNonPositive(AddRec->getOperand(i)))
6437 AllNonPos = false;
6438 }
6439 if (AllNonNeg)
6440 ConservativeResult = ConservativeResult.intersectWith(
6441 ConstantRange::getNonEmpty(getSignedRangeMin(AddRec->getStart()),
6442 APInt::getSignedMinValue(BitWidth)),
6443 RangeType);
6444 else if (AllNonPos)
6445 ConservativeResult = ConservativeResult.intersectWith(
6446 ConstantRange::getNonEmpty(
6447 APInt::getSignedMinValue(BitWidth),
6448 getSignedRangeMax(AddRec->getStart()) + 1),
6449 RangeType);
6450 }
6451
6452 // TODO: non-affine addrec
6453 if (AddRec->isAffine()) {
6454 const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(AddRec->getLoop());
6455 if (!isa<SCEVCouldNotCompute>(MaxBECount) &&
6456 getTypeSizeInBits(MaxBECount->getType()) <= BitWidth) {
6457 auto RangeFromAffine = getRangeForAffineAR(
6458 AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount,
6459 BitWidth);
6460 ConservativeResult =
6461 ConservativeResult.intersectWith(RangeFromAffine, RangeType);
6462
6463 auto RangeFromFactoring = getRangeViaFactoring(
6464 AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount,
6465 BitWidth);
6466 ConservativeResult =
6467 ConservativeResult.intersectWith(RangeFromFactoring, RangeType);
6468 }
6469
6470 // Now try symbolic BE count and more powerful methods.
6471 if (UseExpensiveRangeSharpening) {
6472 const SCEV *SymbolicMaxBECount =
6473 getSymbolicMaxBackedgeTakenCount(AddRec->getLoop());
6474 if (!isa<SCEVCouldNotCompute>(SymbolicMaxBECount) &&
6475 getTypeSizeInBits(MaxBECount->getType()) <= BitWidth &&
6476 AddRec->hasNoSelfWrap()) {
6477 auto RangeFromAffineNew = getRangeForAffineNoSelfWrappingAR(
6478 AddRec, SymbolicMaxBECount, BitWidth, SignHint);
6479 ConservativeResult =
6480 ConservativeResult.intersectWith(RangeFromAffineNew, RangeType);
6481 }
6482 }
6483 }
6484
6485 return setRange(AddRec, SignHint, std::move(ConservativeResult));
6486 }
6487
6488 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
6489
6490 // Check if the IR explicitly contains !range metadata.
6491 Optional<ConstantRange> MDRange = GetRangeFromMetadata(U->getValue());
6492 if (MDRange.hasValue())
6493 ConservativeResult = ConservativeResult.intersectWith(MDRange.getValue(),
6494 RangeType);
6495
6496 // Use facts about recurrences in the underlying IR. Note that add
6497 // recurrences are AddRecExprs and thus don't hit this path. This
6498 // primarily handles shift recurrences.
6499 auto CR = getRangeForUnknownRecurrence(U);
6500 ConservativeResult = ConservativeResult.intersectWith(CR);
6501
6502 // See if ValueTracking can give us a useful range.
6503 const DataLayout &DL = getDataLayout();
6504 KnownBits Known = computeKnownBits(U->getValue(), DL, 0, &AC, nullptr, &DT);
6505 if (Known.getBitWidth() != BitWidth)
6506 Known = Known.zextOrTrunc(BitWidth);
6507
6508 // ValueTracking may be able to compute a tighter result for the number of
6509 // sign bits than for the value of those sign bits.
6510 unsigned NS = ComputeNumSignBits(U->getValue(), DL, 0, &AC, nullptr, &DT);
6511 if (U->getType()->isPointerTy()) {
6512 // If the pointer size is larger than the index size type, this can cause
6513 // NS to be larger than BitWidth. So compensate for this.
6514 unsigned ptrSize = DL.getPointerTypeSizeInBits(U->getType());
6515 int ptrIdxDiff = ptrSize - BitWidth;
6516 if (ptrIdxDiff > 0 && ptrSize > BitWidth && NS > (unsigned)ptrIdxDiff)
6517 NS -= ptrIdxDiff;
6518 }
6519
6520 if (NS > 1) {
6521 // If we know any of the sign bits, we know all of the sign bits.
6522 if (!Known.Zero.getHiBits(NS).isZero())
6523 Known.Zero.setHighBits(NS);
6524 if (!Known.One.getHiBits(NS).isZero())
6525 Known.One.setHighBits(NS);
6526 }
6527
6528 if (Known.getMinValue() != Known.getMaxValue() + 1)
6529 ConservativeResult = ConservativeResult.intersectWith(
6530 ConstantRange(Known.getMinValue(), Known.getMaxValue() + 1),
6531 RangeType);
6532 if (NS > 1)
6533 ConservativeResult = ConservativeResult.intersectWith(
6534 ConstantRange(APInt::getSignedMinValue(BitWidth).ashr(NS - 1),
6535 APInt::getSignedMaxValue(BitWidth).ashr(NS - 1) + 1),
6536 RangeType);
6537
6538 // A range of Phi is a subset of union of all ranges of its input.
6539 if (const PHINode *Phi = dyn_cast<PHINode>(U->getValue())) {
6540 // Make sure that we do not run over cycled Phis.
6541 if (PendingPhiRanges.insert(Phi).second) {
6542 ConstantRange RangeFromOps(BitWidth, /*isFullSet=*/false);
6543 for (auto &Op : Phi->operands()) {
6544 auto OpRange = getRangeRef(getSCEV(Op), SignHint);
6545 RangeFromOps = RangeFromOps.unionWith(OpRange);
6546 // No point to continue if we already have a full set.
6547 if (RangeFromOps.isFullSet())
6548 break;
6549 }
6550 ConservativeResult =
6551 ConservativeResult.intersectWith(RangeFromOps, RangeType);
6552 bool Erased = PendingPhiRanges.erase(Phi);
6553 assert(Erased && "Failed to erase Phi properly?")(static_cast <bool> (Erased && "Failed to erase Phi properly?"
) ? void (0) : __assert_fail ("Erased && \"Failed to erase Phi properly?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 6553, __extension__
__PRETTY_FUNCTION__));
6554 (void) Erased;
6555 }
6556 }
6557
6558 return setRange(U, SignHint, std::move(ConservativeResult));
6559 }
6560
6561 return setRange(S, SignHint, std::move(ConservativeResult));
6562}
6563
6564// Given a StartRange, Step and MaxBECount for an expression compute a range of
6565// values that the expression can take. Initially, the expression has a value
6566// from StartRange and then is changed by Step up to MaxBECount times. Signed
6567// argument defines if we treat Step as signed or unsigned.
6568static ConstantRange getRangeForAffineARHelper(APInt Step,
6569 const ConstantRange &StartRange,
6570 const APInt &MaxBECount,
6571 unsigned BitWidth, bool Signed) {
6572 // If either Step or MaxBECount is 0, then the expression won't change, and we
6573 // just need to return the initial range.
6574 if (Step == 0 || MaxBECount == 0)
6575 return StartRange;
6576
6577 // If we don't know anything about the initial value (i.e. StartRange is
6578 // FullRange), then we don't know anything about the final range either.
6579 // Return FullRange.
6580 if (StartRange.isFullSet())
6581 return ConstantRange::getFull(BitWidth);
6582
6583 // If Step is signed and negative, then we use its absolute value, but we also
6584 // note that we're moving in the opposite direction.
6585 bool Descending = Signed && Step.isNegative();
6586
6587 if (Signed)
6588 // This is correct even for INT_SMIN. Let's look at i8 to illustrate this:
6589 // abs(INT_SMIN) = abs(-128) = abs(0x80) = -0x80 = 0x80 = 128.
6590 // This equations hold true due to the well-defined wrap-around behavior of
6591 // APInt.
6592 Step = Step.abs();
6593
6594 // Check if Offset is more than full span of BitWidth. If it is, the
6595 // expression is guaranteed to overflow.
6596 if (APInt::getMaxValue(StartRange.getBitWidth()).udiv(Step).ult(MaxBECount))
6597 return ConstantRange::getFull(BitWidth);
6598
6599 // Offset is by how much the expression can change. Checks above guarantee no
6600 // overflow here.
6601 APInt Offset = Step * MaxBECount;
6602
6603 // Minimum value of the final range will match the minimal value of StartRange
6604 // if the expression is increasing and will be decreased by Offset otherwise.
6605 // Maximum value of the final range will match the maximal value of StartRange
6606 // if the expression is decreasing and will be increased by Offset otherwise.
6607 APInt StartLower = StartRange.getLower();
6608 APInt StartUpper = StartRange.getUpper() - 1;
6609 APInt MovedBoundary = Descending ? (StartLower - std::move(Offset))
6610 : (StartUpper + std::move(Offset));
6611
6612 // It's possible that the new minimum/maximum value will fall into the initial
6613 // range (due to wrap around). This means that the expression can take any
6614 // value in this bitwidth, and we have to return full range.
6615 if (StartRange.contains(MovedBoundary))
6616 return ConstantRange::getFull(BitWidth);
6617
6618 APInt NewLower =
6619 Descending ? std::move(MovedBoundary) : std::move(StartLower);
6620 APInt NewUpper =
6621 Descending ? std::move(StartUpper) : std::move(MovedBoundary);
6622 NewUpper += 1;
6623
6624 // No overflow detected, return [StartLower, StartUpper + Offset + 1) range.
6625 return ConstantRange::getNonEmpty(std::move(NewLower), std::move(NewUpper));
6626}
6627
6628ConstantRange ScalarEvolution::getRangeForAffineAR(const SCEV *Start,
6629 const SCEV *Step,
6630 const SCEV *MaxBECount,
6631 unsigned BitWidth) {
6632 assert(!isa<SCEVCouldNotCompute>(MaxBECount) &&(static_cast <bool> (!isa<SCEVCouldNotCompute>(MaxBECount
) && getTypeSizeInBits(MaxBECount->getType()) <=
BitWidth && "Precondition!") ? void (0) : __assert_fail
("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 6634, __extension__
__PRETTY_FUNCTION__))
6633 getTypeSizeInBits(MaxBECount->getType()) <= BitWidth &&(static_cast <bool> (!isa<SCEVCouldNotCompute>(MaxBECount
) && getTypeSizeInBits(MaxBECount->getType()) <=
BitWidth && "Precondition!") ? void (0) : __assert_fail
("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 6634, __extension__
__PRETTY_FUNCTION__))
6634 "Precondition!")(static_cast <bool> (!isa<SCEVCouldNotCompute>(MaxBECount
) && getTypeSizeInBits(MaxBECount->getType()) <=
BitWidth && "Precondition!") ? void (0) : __assert_fail
("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 6634, __extension__
__PRETTY_FUNCTION__));
6635
6636 MaxBECount = getNoopOrZeroExtend(MaxBECount, Start->getType());
6637 APInt MaxBECountValue = getUnsignedRangeMax(MaxBECount);
6638
6639 // First, consider step signed.
6640 ConstantRange StartSRange = getSignedRange(Start);
6641 ConstantRange StepSRange = getSignedRange(Step);
6642
6643 // If Step can be both positive and negative, we need to find ranges for the
6644 // maximum absolute step values in both directions and union them.
6645 ConstantRange SR =
6646 getRangeForAffineARHelper(StepSRange.getSignedMin(), StartSRange,
6647 MaxBECountValue, BitWidth, /* Signed = */ true);
6648 SR = SR.unionWith(getRangeForAffineARHelper(StepSRange.getSignedMax(),
6649 StartSRange, MaxBECountValue,
6650 BitWidth, /* Signed = */ true));
6651
6652 // Next, consider step unsigned.
6653 ConstantRange UR = getRangeForAffineARHelper(
6654 getUnsignedRangeMax(Step), getUnsignedRange(Start),
6655 MaxBECountValue, BitWidth, /* Signed = */ false);
6656
6657 // Finally, intersect signed and unsigned ranges.
6658 return SR.intersectWith(UR, ConstantRange::Smallest);
6659}
6660
6661ConstantRange ScalarEvolution::getRangeForAffineNoSelfWrappingAR(
6662 const SCEVAddRecExpr *AddRec, const SCEV *MaxBECount, unsigned BitWidth,
6663 ScalarEvolution::RangeSignHint SignHint) {
6664 assert(AddRec->isAffine() && "Non-affine AddRecs are not suppored!\n")(static_cast <bool> (AddRec->isAffine() && "Non-affine AddRecs are not suppored!\n"
) ? void (0) : __assert_fail ("AddRec->isAffine() && \"Non-affine AddRecs are not suppored!\\n\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 6664, __extension__
__PRETTY_FUNCTION__));
6665 assert(AddRec->hasNoSelfWrap() &&(static_cast <bool> (AddRec->hasNoSelfWrap() &&
"This only works for non-self-wrapping AddRecs!") ? void (0)
: __assert_fail ("AddRec->hasNoSelfWrap() && \"This only works for non-self-wrapping AddRecs!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 6666, __extension__
__PRETTY_FUNCTION__))
6666 "This only works for non-self-wrapping AddRecs!")(static_cast <bool> (AddRec->hasNoSelfWrap() &&
"This only works for non-self-wrapping AddRecs!") ? void (0)
: __assert_fail ("AddRec->hasNoSelfWrap() && \"This only works for non-self-wrapping AddRecs!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 6666, __extension__
__PRETTY_FUNCTION__));
6667 const bool IsSigned = SignHint == HINT_RANGE_SIGNED;
6668 const SCEV *Step = AddRec->getStepRecurrence(*this);
6669 // Only deal with constant step to save compile time.
6670 if (!isa<SCEVConstant>(Step))
6671 return ConstantRange::getFull(BitWidth);
6672 // Let's make sure that we can prove that we do not self-wrap during
6673 // MaxBECount iterations. We need this because MaxBECount is a maximum
6674 // iteration count estimate, and we might infer nw from some exit for which we
6675 // do not know max exit count (or any other side reasoning).
6676 // TODO: Turn into assert at some point.
6677 if (getTypeSizeInBits(MaxBECount->getType()) >
6678 getTypeSizeInBits(AddRec->getType()))
6679 return ConstantRange::getFull(BitWidth);
6680 MaxBECount = getNoopOrZeroExtend(MaxBECount, AddRec->getType());
6681 const SCEV *RangeWidth = getMinusOne(AddRec->getType());
6682 const SCEV *StepAbs = getUMinExpr(Step, getNegativeSCEV(Step));
6683 const SCEV *MaxItersWithoutWrap = getUDivExpr(RangeWidth, StepAbs);
6684 if (!isKnownPredicateViaConstantRanges(ICmpInst::ICMP_ULE, MaxBECount,
6685 MaxItersWithoutWrap))
6686 return ConstantRange::getFull(BitWidth);
6687
6688 ICmpInst::Predicate LEPred =
6689 IsSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
6690 ICmpInst::Predicate GEPred =
6691 IsSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
6692 const SCEV *End = AddRec->evaluateAtIteration(MaxBECount, *this);
6693
6694 // We know that there is no self-wrap. Let's take Start and End values and
6695 // look at all intermediate values V1, V2, ..., Vn that IndVar takes during
6696 // the iteration. They either lie inside the range [Min(Start, End),
6697 // Max(Start, End)] or outside it:
6698 //
6699 // Case 1: RangeMin ... Start V1 ... VN End ... RangeMax;
6700 // Case 2: RangeMin Vk ... V1 Start ... End Vn ... Vk + 1 RangeMax;
6701 //
6702 // No self wrap flag guarantees that the intermediate values cannot be BOTH
6703 // outside and inside the range [Min(Start, End), Max(Start, End)]. Using that
6704 // knowledge, let's try to prove that we are dealing with Case 1. It is so if
6705 // Start <= End and step is positive, or Start >= End and step is negative.
6706 const SCEV *Start = AddRec->getStart();
6707 ConstantRange StartRange = getRangeRef(Start, SignHint);
6708 ConstantRange EndRange = getRangeRef(End, SignHint);
6709 ConstantRange RangeBetween = StartRange.unionWith(EndRange);
6710 // If they already cover full iteration space, we will know nothing useful
6711 // even if we prove what we want to prove.
6712 if (RangeBetween.isFullSet())
6713 return RangeBetween;
6714 // Only deal with ranges that do not wrap (i.e. RangeMin < RangeMax).
6715 bool IsWrappedSet = IsSigned ? RangeBetween.isSignWrappedSet()
6716 : RangeBetween.isWrappedSet();
6717 if (IsWrappedSet)
6718 return ConstantRange::getFull(BitWidth);
6719
6720 if (isKnownPositive(Step) &&
6721 isKnownPredicateViaConstantRanges(LEPred, Start, End))
6722 return RangeBetween;
6723 else if (isKnownNegative(Step) &&
6724 isKnownPredicateViaConstantRanges(GEPred, Start, End))
6725 return RangeBetween;
6726 return ConstantRange::getFull(BitWidth);
6727}
6728
6729ConstantRange ScalarEvolution::getRangeViaFactoring(const SCEV *Start,
6730 const SCEV *Step,
6731 const SCEV *MaxBECount,
6732 unsigned BitWidth) {
6733 // RangeOf({C?A:B,+,C?P:Q}) == RangeOf(C?{A,+,P}:{B,+,Q})
6734 // == RangeOf({A,+,P}) union RangeOf({B,+,Q})
6735
6736 struct SelectPattern {
6737 Value *Condition = nullptr;
6738 APInt TrueValue;
6739 APInt FalseValue;
6740
6741 explicit SelectPattern(ScalarEvolution &SE, unsigned BitWidth,
6742 const SCEV *S) {
6743 Optional<unsigned> CastOp;
6744 APInt Offset(BitWidth, 0);
6745
6746 assert(SE.getTypeSizeInBits(S->getType()) == BitWidth &&(static_cast <bool> (SE.getTypeSizeInBits(S->getType
()) == BitWidth && "Should be!") ? void (0) : __assert_fail
("SE.getTypeSizeInBits(S->getType()) == BitWidth && \"Should be!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 6747, __extension__
__PRETTY_FUNCTION__))
6747 "Should be!")(static_cast <bool> (SE.getTypeSizeInBits(S->getType
()) == BitWidth && "Should be!") ? void (0) : __assert_fail
("SE.getTypeSizeInBits(S->getType()) == BitWidth && \"Should be!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 6747, __extension__
__PRETTY_FUNCTION__));
6748
6749 // Peel off a constant offset:
6750 if (auto *SA = dyn_cast<SCEVAddExpr>(S)) {
6751 // In the future we could consider being smarter here and handle
6752 // {Start+Step,+,Step} too.
6753 if (SA->getNumOperands() != 2 || !isa<SCEVConstant>(SA->getOperand(0)))
6754 return;
6755
6756 Offset = cast<SCEVConstant>(SA->getOperand(0))->getAPInt();
6757 S = SA->getOperand(1);
6758 }
6759
6760 // Peel off a cast operation
6761 if (auto *SCast = dyn_cast<SCEVIntegralCastExpr>(S)) {
6762 CastOp = SCast->getSCEVType();
6763 S = SCast->getOperand();
6764 }
6765
6766 using namespace llvm::PatternMatch;
6767
6768 auto *SU = dyn_cast<SCEVUnknown>(S);
6769 const APInt *TrueVal, *FalseVal;
6770 if (!SU ||
6771 !match(SU->getValue(), m_Select(m_Value(Condition), m_APInt(TrueVal),
6772 m_APInt(FalseVal)))) {
6773 Condition = nullptr;
6774 return;
6775 }
6776
6777 TrueValue = *TrueVal;
6778 FalseValue = *FalseVal;
6779
6780 // Re-apply the cast we peeled off earlier
6781 if (CastOp.hasValue())
6782 switch (*CastOp) {
6783 default:
6784 llvm_unreachable("Unknown SCEV cast type!")::llvm::llvm_unreachable_internal("Unknown SCEV cast type!", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 6784);
6785
6786 case scTruncate:
6787 TrueValue = TrueValue.trunc(BitWidth);
6788 FalseValue = FalseValue.trunc(BitWidth);
6789 break;
6790 case scZeroExtend:
6791 TrueValue = TrueValue.zext(BitWidth);
6792 FalseValue = FalseValue.zext(BitWidth);
6793 break;
6794 case scSignExtend:
6795 TrueValue = TrueValue.sext(BitWidth);
6796 FalseValue = FalseValue.sext(BitWidth);
6797 break;
6798 }
6799
6800 // Re-apply the constant offset we peeled off earlier
6801 TrueValue += Offset;
6802 FalseValue += Offset;
6803 }
6804
6805 bool isRecognized() { return Condition != nullptr; }
6806 };
6807
6808 SelectPattern StartPattern(*this, BitWidth, Start);
6809 if (!StartPattern.isRecognized())
6810 return ConstantRange::getFull(BitWidth);
6811
6812 SelectPattern StepPattern(*this, BitWidth, Step);
6813 if (!StepPattern.isRecognized())
6814 return ConstantRange::getFull(BitWidth);
6815
6816 if (StartPattern.Condition != StepPattern.Condition) {
6817 // We don't handle this case today; but we could, by considering four
6818 // possibilities below instead of two. I'm not sure if there are cases where
6819 // that will help over what getRange already does, though.
6820 return ConstantRange::getFull(BitWidth);
6821 }
6822
6823 // NB! Calling ScalarEvolution::getConstant is fine, but we should not try to
6824 // construct arbitrary general SCEV expressions here. This function is called
6825 // from deep in the call stack, and calling getSCEV (on a sext instruction,
6826 // say) can end up caching a suboptimal value.
6827
6828 // FIXME: without the explicit `this` receiver below, MSVC errors out with
6829 // C2352 and C2512 (otherwise it isn't needed).
6830
6831 const SCEV *TrueStart = this->getConstant(StartPattern.TrueValue);
6832 const SCEV *TrueStep = this->getConstant(StepPattern.TrueValue);
6833 const SCEV *FalseStart = this->getConstant(StartPattern.FalseValue);
6834 const SCEV *FalseStep = this->getConstant(StepPattern.FalseValue);
6835
6836 ConstantRange TrueRange =
6837 this->getRangeForAffineAR(TrueStart, TrueStep, MaxBECount, BitWidth);
6838 ConstantRange FalseRange =
6839 this->getRangeForAffineAR(FalseStart, FalseStep, MaxBECount, BitWidth);
6840
6841 return TrueRange.unionWith(FalseRange);
6842}
6843
6844SCEV::NoWrapFlags ScalarEvolution::getNoWrapFlagsFromUB(const Value *V) {
6845 if (isa<ConstantExpr>(V)) return SCEV::FlagAnyWrap;
6846 const BinaryOperator *BinOp = cast<BinaryOperator>(V);
6847
6848 // Return early if there are no flags to propagate to the SCEV.
6849 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
6850 if (BinOp->hasNoUnsignedWrap())
6851 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
6852 if (BinOp->hasNoSignedWrap())
6853 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
6854 if (Flags == SCEV::FlagAnyWrap)
6855 return SCEV::FlagAnyWrap;
6856
6857 return isSCEVExprNeverPoison(BinOp) ? Flags : SCEV::FlagAnyWrap;
6858}
6859
6860const Instruction *
6861ScalarEvolution::getNonTrivialDefiningScopeBound(const SCEV *S) {
6862 if (auto *AddRec = dyn_cast<SCEVAddRecExpr>(S))
6863 return &*AddRec->getLoop()->getHeader()->begin();
6864 if (auto *U = dyn_cast<SCEVUnknown>(S))
6865 if (auto *I = dyn_cast<Instruction>(U->getValue()))
6866 return I;
6867 return nullptr;
6868}
6869
6870/// Fills \p Ops with unique operands of \p S, if it has operands. If not,
6871/// \p Ops remains unmodified.
6872static void collectUniqueOps(const SCEV *S,
6873 SmallVectorImpl<const SCEV *> &Ops) {
6874 SmallPtrSet<const SCEV *, 4> Unique;
6875 auto InsertUnique = [&](const SCEV *S) {
6876 if (Unique.insert(S).second)
6877 Ops.push_back(S);
6878 };
6879 if (auto *S2 = dyn_cast<SCEVCastExpr>(S))
6880 for (auto *Op : S2->operands())
6881 InsertUnique(Op);
6882 else if (auto *S2 = dyn_cast<SCEVNAryExpr>(S))
6883 for (auto *Op : S2->operands())
6884 InsertUnique(Op);
6885 else if (auto *S2 = dyn_cast<SCEVUDivExpr>(S))
6886 for (auto *Op : S2->operands())
6887 InsertUnique(Op);
6888}
6889
6890const Instruction *
6891ScalarEvolution::getDefiningScopeBound(ArrayRef<const SCEV *> Ops,
6892 bool &Precise) {
6893 Precise = true;
6894 // Do a bounded search of the def relation of the requested SCEVs.
6895 SmallSet<const SCEV *, 16> Visited;
6896 SmallVector<const SCEV *> Worklist;
6897 auto pushOp = [&](const SCEV *S) {
6898 if (!Visited.insert(S).second)
6899 return;
6900 // Threshold of 30 here is arbitrary.
6901 if (Visited.size() > 30) {
6902 Precise = false;
6903 return;
6904 }
6905 Worklist.push_back(S);
6906 };
6907
6908 for (auto *S : Ops)
6909 pushOp(S);
6910
6911 const Instruction *Bound = nullptr;
6912 while (!Worklist.empty()) {
6913 auto *S = Worklist.pop_back_val();
6914 if (auto *DefI = getNonTrivialDefiningScopeBound(S)) {
6915 if (!Bound || DT.dominates(Bound, DefI))
6916 Bound = DefI;
6917 } else {
6918 SmallVector<const SCEV *, 4> Ops;
6919 collectUniqueOps(S, Ops);
6920 for (auto *Op : Ops)
6921 pushOp(Op);
6922 }
6923 }
6924 return Bound ? Bound : &*F.getEntryBlock().begin();
6925}
6926
6927const Instruction *
6928ScalarEvolution::getDefiningScopeBound(ArrayRef<const SCEV *> Ops) {
6929 bool Discard;
6930 return getDefiningScopeBound(Ops, Discard);
6931}
6932
6933bool ScalarEvolution::isGuaranteedToTransferExecutionTo(const Instruction *A,
6934 const Instruction *B) {
6935 if (A->getParent() == B->getParent() &&
6936 isGuaranteedToTransferExecutionToSuccessor(A->getIterator(),
6937 B->getIterator()))
6938 return true;
6939
6940 auto *BLoop = LI.getLoopFor(B->getParent());
6941 if (BLoop && BLoop->getHeader() == B->getParent() &&
6942 BLoop->getLoopPreheader() == A->getParent() &&
6943 isGuaranteedToTransferExecutionToSuccessor(A->getIterator(),
6944 A->getParent()->end()) &&
6945 isGuaranteedToTransferExecutionToSuccessor(B->getParent()->begin(),
6946 B->getIterator()))
6947 return true;
6948 return false;
6949}
6950
6951
6952bool ScalarEvolution::isSCEVExprNeverPoison(const Instruction *I) {
6953 // Only proceed if we can prove that I does not yield poison.
6954 if (!programUndefinedIfPoison(I))
6955 return false;
6956
6957 // At this point we know that if I is executed, then it does not wrap
6958 // according to at least one of NSW or NUW. If I is not executed, then we do
6959 // not know if the calculation that I represents would wrap. Multiple
6960 // instructions can map to the same SCEV. If we apply NSW or NUW from I to
6961 // the SCEV, we must guarantee no wrapping for that SCEV also when it is
6962 // derived from other instructions that map to the same SCEV. We cannot make
6963 // that guarantee for cases where I is not executed. So we need to find a
6964 // upper bound on the defining scope for the SCEV, and prove that I is
6965 // executed every time we enter that scope. When the bounding scope is a
6966 // loop (the common case), this is equivalent to proving I executes on every
6967 // iteration of that loop.
6968 SmallVector<const SCEV *> SCEVOps;
6969 for (const Use &Op : I->operands()) {
6970 // I could be an extractvalue from a call to an overflow intrinsic.
6971 // TODO: We can do better here in some cases.
6972 if (isSCEVable(Op->getType()))
6973 SCEVOps.push_back(getSCEV(Op));
6974 }
6975 auto *DefI = getDefiningScopeBound(SCEVOps);
6976 return isGuaranteedToTransferExecutionTo(DefI, I);
6977}
6978
6979bool ScalarEvolution::isAddRecNeverPoison(const Instruction *I, const Loop *L) {
6980 // If we know that \c I can never be poison period, then that's enough.
6981 if (isSCEVExprNeverPoison(I))
6982 return true;
6983
6984 // For an add recurrence specifically, we assume that infinite loops without
6985 // side effects are undefined behavior, and then reason as follows:
6986 //
6987 // If the add recurrence is poison in any iteration, it is poison on all
6988 // future iterations (since incrementing poison yields poison). If the result
6989 // of the add recurrence is fed into the loop latch condition and the loop
6990 // does not contain any throws or exiting blocks other than the latch, we now
6991 // have the ability to "choose" whether the backedge is taken or not (by
6992 // choosing a sufficiently evil value for the poison feeding into the branch)
6993 // for every iteration including and after the one in which \p I first became
6994 // poison. There are two possibilities (let's call the iteration in which \p
6995 // I first became poison as K):
6996 //
6997 // 1. In the set of iterations including and after K, the loop body executes
6998 // no side effects. In this case executing the backege an infinte number
6999 // of times will yield undefined behavior.
7000 //
7001 // 2. In the set of iterations including and after K, the loop body executes
7002 // at least one side effect. In this case, that specific instance of side
7003 // effect is control dependent on poison, which also yields undefined
7004 // behavior.
7005
7006 auto *ExitingBB = L->getExitingBlock();
7007 auto *LatchBB = L->getLoopLatch();
7008 if (!ExitingBB || !LatchBB || ExitingBB != LatchBB)
7009 return false;
7010
7011 SmallPtrSet<const Instruction *, 16> Pushed;
7012 SmallVector<const Instruction *, 8> PoisonStack;
7013
7014 // We start by assuming \c I, the post-inc add recurrence, is poison. Only
7015 // things that are known to be poison under that assumption go on the
7016 // PoisonStack.
7017 Pushed.insert(I);
7018 PoisonStack.push_back(I);
7019
7020 bool LatchControlDependentOnPoison = false;
7021 while (!PoisonStack.empty() && !LatchControlDependentOnPoison) {
7022 const Instruction *Poison = PoisonStack.pop_back_val();
7023
7024 for (auto *PoisonUser : Poison->users()) {
7025 if (propagatesPoison(cast<Operator>(PoisonUser))) {
7026 if (Pushed.insert(cast<Instruction>(PoisonUser)).second)
7027 PoisonStack.push_back(cast<Instruction>(PoisonUser));
7028 } else if (auto *BI = dyn_cast<BranchInst>(PoisonUser)) {
7029 assert(BI->isConditional() && "Only possibility!")(static_cast <bool> (BI->isConditional() && "Only possibility!"
) ? void (0) : __assert_fail ("BI->isConditional() && \"Only possibility!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 7029, __extension__
__PRETTY_FUNCTION__));
7030 if (BI->getParent() == LatchBB) {
7031 LatchControlDependentOnPoison = true;
7032 break;
7033 }
7034 }
7035 }
7036 }
7037
7038 return LatchControlDependentOnPoison && loopHasNoAbnormalExits(L);
7039}
7040
7041ScalarEvolution::LoopProperties
7042ScalarEvolution::getLoopProperties(const Loop *L) {
7043 using LoopProperties = ScalarEvolution::LoopProperties;
7044
7045 auto Itr = LoopPropertiesCache.find(L);
7046 if (Itr == LoopPropertiesCache.end()) {
7047 auto HasSideEffects = [](Instruction *I) {
7048 if (auto *SI = dyn_cast<StoreInst>(I))
7049 return !SI->isSimple();
7050
7051 return I->mayThrow() || I->mayWriteToMemory();
7052 };
7053
7054 LoopProperties LP = {/* HasNoAbnormalExits */ true,
7055 /*HasNoSideEffects*/ true};
7056
7057 for (auto *BB : L->getBlocks())
7058 for (auto &I : *BB) {
7059 if (!isGuaranteedToTransferExecutionToSuccessor(&I))
7060 LP.HasNoAbnormalExits = false;
7061 if (HasSideEffects(&I))
7062 LP.HasNoSideEffects = false;
7063 if (!LP.HasNoAbnormalExits && !LP.HasNoSideEffects)
7064 break; // We're already as pessimistic as we can get.
7065 }
7066
7067 auto InsertPair = LoopPropertiesCache.insert({L, LP});
7068 assert(InsertPair.second && "We just checked!")(static_cast <bool> (InsertPair.second && "We just checked!"
) ? void (0) : __assert_fail ("InsertPair.second && \"We just checked!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 7068, __extension__
__PRETTY_FUNCTION__));
7069 Itr = InsertPair.first;
7070 }
7071
7072 return Itr->second;
7073}
7074
7075bool ScalarEvolution::loopIsFiniteByAssumption(const Loop *L) {
7076 // A mustprogress loop without side effects must be finite.
7077 // TODO: The check used here is very conservative. It's only *specific*
7078 // side effects which are well defined in infinite loops.
7079 return isFinite(L) || (isMustProgress(L) && loopHasNoSideEffects(L));
7080}
7081
7082const SCEV *ScalarEvolution::createSCEV(Value *V) {
7083 if (!isSCEVable(V->getType()))
7084 return getUnknown(V);
7085
7086 if (Instruction *I = dyn_cast<Instruction>(V)) {
7087 // Don't attempt to analyze instructions in blocks that aren't
7088 // reachable. Such instructions don't matter, and they aren't required
7089 // to obey basic rules for definitions dominating uses which this
7090 // analysis depends on.
7091 if (!DT.isReachableFromEntry(I->getParent()))
7092 return getUnknown(UndefValue::get(V->getType()));
7093 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
7094 return getConstant(CI);
7095 else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
7096 return GA->isInterposable() ? getUnknown(V) : getSCEV(GA->getAliasee());
7097 else if (!isa<ConstantExpr>(V))
7098 return getUnknown(V);
7099
7100 Operator *U = cast<Operator>(V);
7101 if (auto BO = MatchBinaryOp(U, DT)) {
7102 switch (BO->Opcode) {
7103 case Instruction::Add: {
7104 // The simple thing to do would be to just call getSCEV on both operands
7105 // and call getAddExpr with the result. However if we're looking at a
7106 // bunch of things all added together, this can be quite inefficient,
7107 // because it leads to N-1 getAddExpr calls for N ultimate operands.
7108 // Instead, gather up all the operands and make a single getAddExpr call.
7109 // LLVM IR canonical form means we need only traverse the left operands.
7110 SmallVector<const SCEV *, 4> AddOps;
7111 do {
7112 if (BO->Op) {
7113 if (auto *OpSCEV = getExistingSCEV(BO->Op)) {
7114 AddOps.push_back(OpSCEV);
7115 break;
7116 }
7117
7118 // If a NUW or NSW flag can be applied to the SCEV for this
7119 // addition, then compute the SCEV for this addition by itself
7120 // with a separate call to getAddExpr. We need to do that
7121 // instead of pushing the operands of the addition onto AddOps,
7122 // since the flags are only known to apply to this particular
7123 // addition - they may not apply to other additions that can be
7124 // formed with operands from AddOps.
7125 const SCEV *RHS = getSCEV(BO->RHS);
7126 SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op);
7127 if (Flags != SCEV::FlagAnyWrap) {
7128 const SCEV *LHS = getSCEV(BO->LHS);
7129 if (BO->Opcode == Instruction::Sub)
7130 AddOps.push_back(getMinusSCEV(LHS, RHS, Flags));
7131 else
7132 AddOps.push_back(getAddExpr(LHS, RHS, Flags));
7133 break;
7134 }
7135 }
7136
7137 if (BO->Opcode == Instruction::Sub)
7138 AddOps.push_back(getNegativeSCEV(getSCEV(BO->RHS)));
7139 else
7140 AddOps.push_back(getSCEV(BO->RHS));
7141
7142 auto NewBO = MatchBinaryOp(BO->LHS, DT);
7143 if (!NewBO || (NewBO->Opcode != Instruction::Add &&
7144 NewBO->Opcode != Instruction::Sub)) {
7145 AddOps.push_back(getSCEV(BO->LHS));
7146 break;
7147 }
7148 BO = NewBO;
7149 } while (true);
7150
7151 return getAddExpr(AddOps);
7152 }
7153
7154 case Instruction::Mul: {
7155 SmallVector<const SCEV *, 4> MulOps;
7156 do {
7157 if (BO->Op) {
7158 if (auto *OpSCEV = getExistingSCEV(BO->Op)) {
7159 MulOps.push_back(OpSCEV);
7160 break;
7161 }
7162
7163 SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op);
7164 if (Flags != SCEV::FlagAnyWrap) {
7165 MulOps.push_back(
7166 getMulExpr(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags));
7167 break;
7168 }
7169 }
7170
7171 MulOps.push_back(getSCEV(BO->RHS));
7172 auto NewBO = MatchBinaryOp(BO->LHS, DT);
7173 if (!NewBO || NewBO->Opcode != Instruction::Mul) {
7174 MulOps.push_back(getSCEV(BO->LHS));
7175 break;
7176 }
7177 BO = NewBO;
7178 } while (true);
7179
7180 return getMulExpr(MulOps);
7181 }
7182 case Instruction::UDiv:
7183 return getUDivExpr(getSCEV(BO->LHS), getSCEV(BO->RHS));
7184 case Instruction::URem:
7185 return getURemExpr(getSCEV(BO->LHS), getSCEV(BO->RHS));
7186 case Instruction::Sub: {
7187 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
7188 if (BO->Op)
7189 Flags = getNoWrapFlagsFromUB(BO->Op);
7190 return getMinusSCEV(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags);
7191 }
7192 case Instruction::And:
7193 // For an expression like x&255 that merely masks off the high bits,
7194 // use zext(trunc(x)) as the SCEV expression.
7195 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
7196 if (CI->isZero())
7197 return getSCEV(BO->RHS);
7198 if (CI->isMinusOne())
7199 return getSCEV(BO->LHS);
7200 const APInt &A = CI->getValue();
7201
7202 // Instcombine's ShrinkDemandedConstant may strip bits out of
7203 // constants, obscuring what would otherwise be a low-bits mask.
7204 // Use computeKnownBits to compute what ShrinkDemandedConstant
7205 // knew about to reconstruct a low-bits mask value.
7206 unsigned LZ = A.countLeadingZeros();
7207 unsigned TZ = A.countTrailingZeros();
7208 unsigned BitWidth = A.getBitWidth();
7209 KnownBits Known(BitWidth);
7210 computeKnownBits(BO->LHS, Known, getDataLayout(),
7211 0, &AC, nullptr, &DT);
7212
7213 APInt EffectiveMask =
7214 APInt::getLowBitsSet(BitWidth, BitWidth - LZ - TZ).shl(TZ);
7215 if ((LZ != 0 || TZ != 0) && !((~A & ~Known.Zero) & EffectiveMask)) {
7216 const SCEV *MulCount = getConstant(APInt::getOneBitSet(BitWidth, TZ));
7217 const SCEV *LHS = getSCEV(BO->LHS);
7218 const SCEV *ShiftedLHS = nullptr;
7219 if (auto *LHSMul = dyn_cast<SCEVMulExpr>(LHS)) {
7220 if (auto *OpC = dyn_cast<SCEVConstant>(LHSMul->getOperand(0))) {
7221 // For an expression like (x * 8) & 8, simplify the multiply.
7222 unsigned MulZeros = OpC->getAPInt().countTrailingZeros();
7223 unsigned GCD = std::min(MulZeros, TZ);
7224 APInt DivAmt = APInt::getOneBitSet(BitWidth, TZ - GCD);
7225 SmallVector<const SCEV*, 4> MulOps;
7226 MulOps.push_back(getConstant(OpC->getAPInt().lshr(GCD)));
7227 MulOps.append(LHSMul->op_begin() + 1, LHSMul->op_end());
7228 auto *NewMul = getMulExpr(MulOps, LHSMul->getNoWrapFlags());
7229 ShiftedLHS = getUDivExpr(NewMul, getConstant(DivAmt));
7230 }
7231 }
7232 if (!ShiftedLHS)
7233 ShiftedLHS = getUDivExpr(LHS, MulCount);
7234 return getMulExpr(
7235 getZeroExtendExpr(
7236 getTruncateExpr(ShiftedLHS,
7237 IntegerType::get(getContext(), BitWidth - LZ - TZ)),
7238 BO->LHS->getType()),
7239 MulCount);
7240 }
7241 }
7242 // Binary `and` is a bit-wise `umin`.
7243 if (BO->LHS->getType()->isIntegerTy(1))
7244 return getUMinExpr(getSCEV(BO->LHS), getSCEV(BO->RHS));
7245 break;
7246
7247 case Instruction::Or:
7248 // If the RHS of the Or is a constant, we may have something like:
7249 // X*4+1 which got turned into X*4|1. Handle this as an Add so loop
7250 // optimizations will transparently handle this case.
7251 //
7252 // In order for this transformation to be safe, the LHS must be of the
7253 // form X*(2^n) and the Or constant must be less than 2^n.
7254 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
7255 const SCEV *LHS = getSCEV(BO->LHS);
7256 const APInt &CIVal = CI->getValue();
7257 if (GetMinTrailingZeros(LHS) >=
7258 (CIVal.getBitWidth() - CIVal.countLeadingZeros())) {
7259 // Build a plain add SCEV.
7260 return getAddExpr(LHS, getSCEV(CI),
7261 (SCEV::NoWrapFlags)(SCEV::FlagNUW | SCEV::FlagNSW));
7262 }
7263 }
7264 // Binary `or` is a bit-wise `umax`.
7265 if (BO->LHS->getType()->isIntegerTy(1))
7266 return getUMaxExpr(getSCEV(BO->LHS), getSCEV(BO->RHS));
7267 break;
7268
7269 case Instruction::Xor:
7270 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
7271 // If the RHS of xor is -1, then this is a not operation.
7272 if (CI->isMinusOne())
7273 return getNotSCEV(getSCEV(BO->LHS));
7274
7275 // Model xor(and(x, C), C) as and(~x, C), if C is a low-bits mask.
7276 // This is a variant of the check for xor with -1, and it handles
7277 // the case where instcombine has trimmed non-demanded bits out
7278 // of an xor with -1.
7279 if (auto *LBO = dyn_cast<BinaryOperator>(BO->LHS))
7280 if (ConstantInt *LCI = dyn_cast<ConstantInt>(LBO->getOperand(1)))
7281 if (LBO->getOpcode() == Instruction::And &&
7282 LCI->getValue() == CI->getValue())
7283 if (const SCEVZeroExtendExpr *Z =
7284 dyn_cast<SCEVZeroExtendExpr>(getSCEV(BO->LHS))) {
7285 Type *UTy = BO->LHS->getType();
7286 const SCEV *Z0 = Z->getOperand();
7287 Type *Z0Ty = Z0->getType();
7288 unsigned Z0TySize = getTypeSizeInBits(Z0Ty);
7289
7290 // If C is a low-bits mask, the zero extend is serving to
7291 // mask off the high bits. Complement the operand and
7292 // re-apply the zext.
7293 if (CI->getValue().isMask(Z0TySize))
7294 return getZeroExtendExpr(getNotSCEV(Z0), UTy);
7295
7296 // If C is a single bit, it may be in the sign-bit position
7297 // before the zero-extend. In this case, represent the xor
7298 // using an add, which is equivalent, and re-apply the zext.
7299 APInt Trunc = CI->getValue().trunc(Z0TySize);
7300 if (Trunc.zext(getTypeSizeInBits(UTy)) == CI->getValue() &&
7301 Trunc.isSignMask())
7302 return getZeroExtendExpr(getAddExpr(Z0, getConstant(Trunc)),
7303 UTy);
7304 }
7305 }
7306 break;
7307
7308 case Instruction::Shl:
7309 // Turn shift left of a constant amount into a multiply.
7310 if (ConstantInt *SA = dyn_cast<ConstantInt>(BO->RHS)) {
7311 uint32_t BitWidth = cast<IntegerType>(SA->getType())->getBitWidth();
7312
7313 // If the shift count is not less than the bitwidth, the result of
7314 // the shift is undefined. Don't try to analyze it, because the
7315 // resolution chosen here may differ from the resolution chosen in
7316 // other parts of the compiler.
7317 if (SA->getValue().uge(BitWidth))
7318 break;
7319
7320 // We can safely preserve the nuw flag in all cases. It's also safe to
7321 // turn a nuw nsw shl into a nuw nsw mul. However, nsw in isolation
7322 // requires special handling. It can be preserved as long as we're not
7323 // left shifting by bitwidth - 1.
7324 auto Flags = SCEV::FlagAnyWrap;
7325 if (BO->Op) {
7326 auto MulFlags = getNoWrapFlagsFromUB(BO->Op);
7327 if ((MulFlags & SCEV::FlagNSW) &&
7328 ((MulFlags & SCEV::FlagNUW) || SA->getValue().ult(BitWidth - 1)))
7329 Flags = (SCEV::NoWrapFlags)(Flags | SCEV::FlagNSW);
7330 if (MulFlags & SCEV::FlagNUW)
7331 Flags = (SCEV::NoWrapFlags)(Flags | SCEV::FlagNUW);
7332 }
7333
7334 Constant *X = ConstantInt::get(
7335 getContext(), APInt::getOneBitSet(BitWidth, SA->getZExtValue()));
7336 return getMulExpr(getSCEV(BO->LHS), getSCEV(X), Flags);
7337 }
7338 break;
7339
7340 case Instruction::AShr: {
7341 // AShr X, C, where C is a constant.
7342 ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS);
7343 if (!CI)
7344 break;
7345
7346 Type *OuterTy = BO->LHS->getType();
7347 uint64_t BitWidth = getTypeSizeInBits(OuterTy);
7348 // If the shift count is not less than the bitwidth, the result of
7349 // the shift is undefined. Don't try to analyze it, because the
7350 // resolution chosen here may differ from the resolution chosen in
7351 // other parts of the compiler.
7352 if (CI->getValue().uge(BitWidth))
7353 break;
7354
7355 if (CI->isZero())
7356 return getSCEV(BO->LHS); // shift by zero --> noop
7357
7358 uint64_t AShrAmt = CI->getZExtValue();
7359 Type *TruncTy = IntegerType::get(getContext(), BitWidth - AShrAmt);
7360
7361 Operator *L = dyn_cast<Operator>(BO->LHS);
7362 if (L && L->getOpcode() == Instruction::Shl) {
7363 // X = Shl A, n
7364 // Y = AShr X, m
7365 // Both n and m are constant.
7366
7367 const SCEV *ShlOp0SCEV = getSCEV(L->getOperand(0));
7368 if (L->getOperand(1) == BO->RHS)
7369 // For a two-shift sext-inreg, i.e. n = m,
7370 // use sext(trunc(x)) as the SCEV expression.
7371 return getSignExtendExpr(
7372 getTruncateExpr(ShlOp0SCEV, TruncTy), OuterTy);
7373
7374 ConstantInt *ShlAmtCI = dyn_cast<ConstantInt>(L->getOperand(1));
7375 if (ShlAmtCI && ShlAmtCI->getValue().ult(BitWidth)) {
7376 uint64_t ShlAmt = ShlAmtCI->getZExtValue();
7377 if (ShlAmt > AShrAmt) {
7378 // When n > m, use sext(mul(trunc(x), 2^(n-m)))) as the SCEV
7379 // expression. We already checked that ShlAmt < BitWidth, so
7380 // the multiplier, 1 << (ShlAmt - AShrAmt), fits into TruncTy as
7381 // ShlAmt - AShrAmt < Amt.
7382 APInt Mul = APInt::getOneBitSet(BitWidth - AShrAmt,
7383 ShlAmt - AShrAmt);
7384 return getSignExtendExpr(
7385 getMulExpr(getTruncateExpr(ShlOp0SCEV, TruncTy),
7386 getConstant(Mul)), OuterTy);
7387 }
7388 }
7389 }
7390 break;
7391 }
7392 }
7393 }
7394
7395 switch (U->getOpcode()) {
7396 case Instruction::Trunc:
7397 return getTruncateExpr(getSCEV(U->getOperand(0)), U->getType());
7398
7399 case Instruction::ZExt:
7400 return getZeroExtendExpr(getSCEV(U->getOperand(0)), U->getType());
7401
7402 case Instruction::SExt:
7403 if (auto BO = MatchBinaryOp(U->getOperand(0), DT)) {
7404 // The NSW flag of a subtract does not always survive the conversion to
7405 // A + (-1)*B. By pushing sign extension onto its operands we are much
7406 // more likely to preserve NSW and allow later AddRec optimisations.
7407 //
7408 // NOTE: This is effectively duplicating this logic from getSignExtend:
7409 // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw>
7410 // but by that point the NSW information has potentially been lost.
7411 if (BO->Opcode == Instruction::Sub && BO->IsNSW) {
7412 Type *Ty = U->getType();
7413 auto *V1 = getSignExtendExpr(getSCEV(BO->LHS), Ty);
7414 auto *V2 = getSignExtendExpr(getSCEV(BO->RHS), Ty);
7415 return getMinusSCEV(V1, V2, SCEV::FlagNSW);
7416 }
7417 }
7418 return getSignExtendExpr(getSCEV(U->getOperand(0)), U->getType());
7419
7420 case Instruction::BitCast:
7421 // BitCasts are no-op casts so we just eliminate the cast.
7422 if (isSCEVable(U->getType()) && isSCEVable(U->getOperand(0)->getType()))
7423 return getSCEV(U->getOperand(0));
7424 break;
7425
7426 case Instruction::PtrToInt: {
7427 // Pointer to integer cast is straight-forward, so do model it.
7428 const SCEV *Op = getSCEV(U->getOperand(0));
7429 Type *DstIntTy = U->getType();
7430 // But only if effective SCEV (integer) type is wide enough to represent
7431 // all possible pointer values.
7432 const SCEV *IntOp = getPtrToIntExpr(Op, DstIntTy);
7433 if (isa<SCEVCouldNotCompute>(IntOp))
7434 return getUnknown(V);
7435 return IntOp;
7436 }
7437 case Instruction::IntToPtr:
7438 // Just don't deal with inttoptr casts.
7439 return getUnknown(V);
7440
7441 case Instruction::SDiv:
7442 // If both operands are non-negative, this is just an udiv.
7443 if (isKnownNonNegative(getSCEV(U->getOperand(0))) &&
7444 isKnownNonNegative(getSCEV(U->getOperand(1))))
7445 return getUDivExpr(getSCEV(U->getOperand(0)), getSCEV(U->getOperand(1)));
7446 break;
7447
7448 case Instruction::SRem:
7449 // If both operands are non-negative, this is just an urem.
7450 if (isKnownNonNegative(getSCEV(U->getOperand(0))) &&
7451 isKnownNonNegative(getSCEV(U->getOperand(1))))
7452 return getURemExpr(getSCEV(U->getOperand(0)), getSCEV(U->getOperand(1)));
7453 break;
7454
7455 case Instruction::GetElementPtr:
7456 return createNodeForGEP(cast<GEPOperator>(U));
7457
7458 case Instruction::PHI:
7459 return createNodeForPHI(cast<PHINode>(U));
7460
7461 case Instruction::Select:
7462 return createNodeForSelectOrPHI(U, U->getOperand(0), U->getOperand(1),
7463 U->getOperand(2));
7464
7465 case Instruction::Call:
7466 case Instruction::Invoke:
7467 if (Value *RV = cast<CallBase>(U)->getReturnedArgOperand())
7468 return getSCEV(RV);
7469
7470 if (auto *II = dyn_cast<IntrinsicInst>(U)) {
7471 switch (II->getIntrinsicID()) {
7472 case Intrinsic::abs:
7473 return getAbsExpr(
7474 getSCEV(II->getArgOperand(0)),
7475 /*IsNSW=*/cast<ConstantInt>(II->getArgOperand(1))->isOne());
7476 case Intrinsic::umax:
7477 return getUMaxExpr(getSCEV(II->getArgOperand(0)),
7478 getSCEV(II->getArgOperand(1)));
7479 case Intrinsic::umin:
7480 return getUMinExpr(getSCEV(II->getArgOperand(0)),
7481 getSCEV(II->getArgOperand(1)));
7482 case Intrinsic::smax:
7483 return getSMaxExpr(getSCEV(II->getArgOperand(0)),
7484 getSCEV(II->getArgOperand(1)));
7485 case Intrinsic::smin:
7486 return getSMinExpr(getSCEV(II->getArgOperand(0)),
7487 getSCEV(II->getArgOperand(1)));
7488 case Intrinsic::usub_sat: {
7489 const SCEV *X = getSCEV(II->getArgOperand(0));
7490 const SCEV *Y = getSCEV(II->getArgOperand(1));
7491 const SCEV *ClampedY = getUMinExpr(X, Y);
7492 return getMinusSCEV(X, ClampedY, SCEV::FlagNUW);
7493 }
7494 case Intrinsic::uadd_sat: {
7495 const SCEV *X = getSCEV(II->getArgOperand(0));
7496 const SCEV *Y = getSCEV(II->getArgOperand(1));
7497 const SCEV *ClampedX = getUMinExpr(X, getNotSCEV(Y));
7498 return getAddExpr(ClampedX, Y, SCEV::FlagNUW);
7499 }
7500 case Intrinsic::start_loop_iterations:
7501 // A start_loop_iterations is just equivalent to the first operand for
7502 // SCEV purposes.
7503 return getSCEV(II->getArgOperand(0));
7504 default:
7505 break;
7506 }
7507 }
7508 break;
7509 }
7510
7511 return getUnknown(V);
7512}
7513
7514//===----------------------------------------------------------------------===//
7515// Iteration Count Computation Code
7516//
7517
7518const SCEV *ScalarEvolution::getTripCountFromExitCount(const SCEV *ExitCount,
7519 bool Extend) {
7520 if (isa<SCEVCouldNotCompute>(ExitCount))
7521 return getCouldNotCompute();
7522
7523 auto *ExitCountType = ExitCount->getType();
7524 assert(ExitCountType->isIntegerTy())(static_cast <bool> (ExitCountType->isIntegerTy()) ?
void (0) : __assert_fail ("ExitCountType->isIntegerTy()",
"llvm/lib/Analysis/ScalarEvolution.cpp", 7524, __extension__
__PRETTY_FUNCTION__));
7525
7526 if (!Extend)
7527 return getAddExpr(ExitCount, getOne(ExitCountType));
7528
7529 auto *WiderType = Type::getIntNTy(ExitCountType->getContext(),
7530 1 + ExitCountType->getScalarSizeInBits());
7531 return getAddExpr(getNoopOrZeroExtend(ExitCount, WiderType),
7532 getOne(WiderType));
7533}
7534
7535static unsigned getConstantTripCount(const SCEVConstant *ExitCount) {
7536 if (!ExitCount)
7537 return 0;
7538
7539 ConstantInt *ExitConst = ExitCount->getValue();
7540
7541 // Guard against huge trip counts.
7542 if (ExitConst->getValue().getActiveBits() > 32)
7543 return 0;
7544
7545 // In case of integer overflow, this returns 0, which is correct.
7546 return ((unsigned)ExitConst->getZExtValue()) + 1;
7547}
7548
7549unsigned ScalarEvolution::getSmallConstantTripCount(const Loop *L) {
7550 auto *ExitCount = dyn_cast<SCEVConstant>(getBackedgeTakenCount(L, Exact));
7551 return getConstantTripCount(ExitCount);
7552}
7553
7554unsigned
7555ScalarEvolution::getSmallConstantTripCount(const Loop *L,
7556 const BasicBlock *ExitingBlock) {
7557 assert(ExitingBlock && "Must pass a non-null exiting block!")(static_cast <bool> (ExitingBlock && "Must pass a non-null exiting block!"
) ? void (0) : __assert_fail ("ExitingBlock && \"Must pass a non-null exiting block!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 7557, __extension__
__PRETTY_FUNCTION__));
7558 assert(L->isLoopExiting(ExitingBlock) &&(static_cast <bool> (L->isLoopExiting(ExitingBlock) &&
"Exiting block must actually branch out of the loop!") ? void
(0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 7559, __extension__
__PRETTY_FUNCTION__))
7559 "Exiting block must actually branch out of the loop!")(static_cast <bool> (L->isLoopExiting(ExitingBlock) &&
"Exiting block must actually branch out of the loop!") ? void
(0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 7559, __extension__
__PRETTY_FUNCTION__));
7560 const SCEVConstant *ExitCount =
7561 dyn_cast<SCEVConstant>(getExitCount(L, ExitingBlock));
7562 return getConstantTripCount(ExitCount);
7563}
7564
7565unsigned ScalarEvolution::getSmallConstantMaxTripCount(const Loop *L) {
7566 const auto *MaxExitCount =
7567 dyn_cast<SCEVConstant>(getConstantMaxBackedgeTakenCount(L));
7568 return getConstantTripCount(MaxExitCount);
7569}
7570
7571const SCEV *ScalarEvolution::getConstantMaxTripCountFromArray(const Loop *L) {
7572 // We can't infer from Array in Irregular Loop.
7573 // FIXME: It's hard to infer loop bound from array operated in Nested Loop.
7574 if (!L->isLoopSimplifyForm() || !L->isInnermost())
7575 return getCouldNotCompute();
7576
7577 // FIXME: To make the scene more typical, we only analysis loops that have
7578 // one exiting block and that block must be the latch. To make it easier to
7579 // capture loops that have memory access and memory access will be executed
7580 // in each iteration.
7581 const BasicBlock *LoopLatch = L->getLoopLatch();
7582 assert(LoopLatch && "See defination of simplify form loop.")(static_cast <bool> (LoopLatch && "See defination of simplify form loop."
) ? void (0) : __assert_fail ("LoopLatch && \"See defination of simplify form loop.\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 7582, __extension__
__PRETTY_FUNCTION__));
7583 if (L->getExitingBlock() != LoopLatch)
7584 return getCouldNotCompute();
7585
7586 const DataLayout &DL = getDataLayout();
7587 SmallVector<const SCEV *> InferCountColl;
7588 for (auto *BB : L->getBlocks()) {
7589 // Go here, we can know that Loop is a single exiting and simplified form
7590 // loop. Make sure that infer from Memory Operation in those BBs must be
7591 // executed in loop. First step, we can make sure that max execution time
7592 // of MemAccessBB in loop represents latch max excution time.
7593 // If MemAccessBB does not dom Latch, skip.
7594 // Entry
7595 // │
7596 // ┌─────▼─────┐
7597 // │Loop Header◄─────┐
7598 // └──┬──────┬─┘ │
7599 // │ │ │
7600 // ┌────────▼──┐ ┌─▼─────┐ │
7601 // │MemAccessBB│ │OtherBB│ │
7602 // └────────┬──┘ └─┬─────┘ │
7603 // │ │ │
7604 // ┌─▼──────▼─┐ │
7605 // │Loop Latch├─────┘
7606 // └────┬─────┘
7607 // ▼
7608 // Exit
7609 if (!DT.dominates(BB, LoopLatch))
7610 continue;
7611
7612 for (Instruction &Inst : *BB) {
7613 // Find Memory Operation Instruction.
7614 auto *GEP = getLoadStorePointerOperand(&Inst);
7615 if (!GEP)
7616 continue;
7617
7618 auto *ElemSize = dyn_cast<SCEVConstant>(getElementSize(&Inst));
7619 // Do not infer from scalar type, eg."ElemSize = sizeof()".
7620 if (!ElemSize)
7621 continue;
7622
7623 // Use a existing polynomial recurrence on the trip count.
7624 auto *AddRec = dyn_cast<SCEVAddRecExpr>(getSCEV(GEP));
7625 if (!AddRec)
7626 continue;
7627 auto *ArrBase = dyn_cast<SCEVUnknown>(getPointerBase(AddRec));
7628 auto *Step = dyn_cast<SCEVConstant>(AddRec->getStepRecurrence(*this));
7629 if (!ArrBase || !Step)
7630 continue;
7631 assert(isLoopInvariant(ArrBase, L) && "See addrec definition")(static_cast <bool> (isLoopInvariant(ArrBase, L) &&
"See addrec definition") ? void (0) : __assert_fail ("isLoopInvariant(ArrBase, L) && \"See addrec definition\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 7631, __extension__
__PRETTY_FUNCTION__));
7632
7633 // Only handle { %array + step },
7634 // FIXME: {(SCEVAddRecExpr) + step } could not be analysed here.
7635 if (AddRec->getStart() != ArrBase)
7636 continue;
7637
7638 // Memory operation pattern which have gaps.
7639 // Or repeat memory opreation.
7640 // And index of GEP wraps arround.
7641 if (Step->getAPInt().getActiveBits() > 32 ||
7642 Step->getAPInt().getZExtValue() !=
7643 ElemSize->getAPInt().getZExtValue() ||
7644 Step->isZero() || Step->getAPInt().isNegative())
7645 continue;
7646
7647 // Only infer from stack array which has certain size.
7648 // Make sure alloca instruction is not excuted in loop.
7649 AllocaInst *AllocateInst = dyn_cast<AllocaInst>(ArrBase->getValue());
7650 if (!AllocateInst || L->contains(AllocateInst->getParent()))
7651 continue;
7652
7653 // Make sure only handle normal array.
7654 auto *Ty = dyn_cast<ArrayType>(AllocateInst->getAllocatedType());
7655 auto *ArrSize = dyn_cast<ConstantInt>(AllocateInst->getArraySize());
7656 if (!Ty || !ArrSize || !ArrSize->isOne())
7657 continue;
7658
7659 // FIXME: Since gep indices are silently zext to the indexing type,
7660 // we will have a narrow gep index which wraps around rather than
7661 // increasing strictly, we shoule ensure that step is increasing
7662 // strictly by the loop iteration.
7663 // Now we can infer a max execution time by MemLength/StepLength.
7664 const SCEV *MemSize =
7665 getConstant(Step->getType(), DL.getTypeAllocSize(Ty));
7666 auto *MaxExeCount =
7667 dyn_cast<SCEVConstant>(getUDivCeilSCEV(MemSize, Step));
7668 if (!MaxExeCount || MaxExeCount->getAPInt().getActiveBits() > 32)
7669 continue;
7670
7671 // If the loop reaches the maximum number of executions, we can not
7672 // access bytes starting outside the statically allocated size without
7673 // being immediate UB. But it is allowed to enter loop header one more
7674 // time.
7675 auto *InferCount = dyn_cast<SCEVConstant>(
7676 getAddExpr(MaxExeCount, getOne(MaxExeCount->getType())));
7677 // Discard the maximum number of execution times under 32bits.
7678 if (!InferCount || InferCount->getAPInt().getActiveBits() > 32)
7679 continue;
7680
7681 InferCountColl.push_back(InferCount);
7682 }
7683 }
7684
7685 if (InferCountColl.size() == 0)
7686 return getCouldNotCompute();
7687
7688 return getUMinFromMismatchedTypes(InferCountColl);
7689}
7690
7691unsigned ScalarEvolution::getSmallConstantTripMultiple(const Loop *L) {
7692 SmallVector<BasicBlock *, 8> ExitingBlocks;
7693 L->getExitingBlocks(ExitingBlocks);
7694
7695 Optional<unsigned> Res = None;
7696 for (auto *ExitingBB : ExitingBlocks) {
7697 unsigned Multiple = getSmallConstantTripMultiple(L, ExitingBB);
7698 if (!Res)
7699 Res = Multiple;
7700 Res = (unsigned)GreatestCommonDivisor64(*Res, Multiple);
7701 }
7702 return Res.getValueOr(1);
7703}
7704
7705unsigned ScalarEvolution::getSmallConstantTripMultiple(const Loop *L,
7706 const SCEV *ExitCount) {
7707 if (ExitCount == getCouldNotCompute())
7708 return 1;
7709
7710 // Get the trip count
7711 const SCEV *TCExpr = getTripCountFromExitCount(ExitCount);
7712
7713 const SCEVConstant *TC = dyn_cast<SCEVConstant>(TCExpr);
7714 if (!TC)
7715 // Attempt to factor more general cases. Returns the greatest power of
7716 // two divisor. If overflow happens, the trip count expression is still
7717 // divisible by the greatest power of 2 divisor returned.
7718 return 1U << std::min((uint32_t)31,
7719 GetMinTrailingZeros(applyLoopGuards(TCExpr, L)));
7720
7721 ConstantInt *Result = TC->getValue();
7722
7723 // Guard against huge trip counts (this requires checking
7724 // for zero to handle the case where the trip count == -1 and the
7725 // addition wraps).
7726 if (!Result || Result->getValue().getActiveBits() > 32 ||
7727 Result->getValue().getActiveBits() == 0)
7728 return 1;
7729
7730 return (unsigned)Result->getZExtValue();
7731}
7732
7733/// Returns the largest constant divisor of the trip count of this loop as a
7734/// normal unsigned value, if possible. This means that the actual trip count is
7735/// always a multiple of the returned value (don't forget the trip count could
7736/// very well be zero as well!).
7737///
7738/// Returns 1 if the trip count is unknown or not guaranteed to be the
7739/// multiple of a constant (which is also the case if the trip count is simply
7740/// constant, use getSmallConstantTripCount for that case), Will also return 1
7741/// if the trip count is very large (>= 2^32).
7742///
7743/// As explained in the comments for getSmallConstantTripCount, this assumes
7744/// that control exits the loop via ExitingBlock.
7745unsigned
7746ScalarEvolution::getSmallConstantTripMultiple(const Loop *L,
7747 const BasicBlock *ExitingBlock) {
7748 assert(ExitingBlock && "Must pass a non-null exiting block!")(static_cast <bool> (ExitingBlock && "Must pass a non-null exiting block!"
) ? void (0) : __assert_fail ("ExitingBlock && \"Must pass a non-null exiting block!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 7748, __extension__
__PRETTY_FUNCTION__));
7749 assert(L->isLoopExiting(ExitingBlock) &&(static_cast <bool> (L->isLoopExiting(ExitingBlock) &&
"Exiting block must actually branch out of the loop!") ? void
(0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 7750, __extension__
__PRETTY_FUNCTION__))
7750 "Exiting block must actually branch out of the loop!")(static_cast <bool> (L->isLoopExiting(ExitingBlock) &&
"Exiting block must actually branch out of the loop!") ? void
(0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 7750, __extension__
__PRETTY_FUNCTION__));
7751 const SCEV *ExitCount = getExitCount(L, ExitingBlock);
7752 return getSmallConstantTripMultiple(L, ExitCount);
7753}
7754
7755const SCEV *ScalarEvolution::getExitCount(const Loop *L,
7756 const BasicBlock *ExitingBlock,
7757 ExitCountKind Kind) {
7758 switch (Kind) {
7759 case Exact:
7760 case SymbolicMaximum:
7761 return getBackedgeTakenInfo(L).getExact(ExitingBlock, this);
7762 case ConstantMaximum:
7763 return getBackedgeTakenInfo(L).getConstantMax(ExitingBlock, this);
7764 };
7765 llvm_unreachable("Invalid ExitCountKind!")::llvm::llvm_unreachable_internal("Invalid ExitCountKind!", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 7765);
7766}
7767
7768const SCEV *
7769ScalarEvolution::getPredicatedBackedgeTakenCount(const Loop *L,
7770 SmallVector<const SCEVPredicate *, 4> &Preds) {
7771 return getPredicatedBackedgeTakenInfo(L).getExact(L, this, &Preds);
7772}
7773
7774const SCEV *ScalarEvolution::getBackedgeTakenCount(const Loop *L,
7775 ExitCountKind Kind) {
7776 switch (Kind) {
7777 case Exact:
7778 return getBackedgeTakenInfo(L).getExact(L, this);
7779 case ConstantMaximum:
7780 return getBackedgeTakenInfo(L).getConstantMax(this);
7781 case SymbolicMaximum:
7782 return getBackedgeTakenInfo(L).getSymbolicMax(L, this);
7783 };
7784 llvm_unreachable("Invalid ExitCountKind!")::llvm::llvm_unreachable_internal("Invalid ExitCountKind!", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 7784);
7785}
7786
7787bool ScalarEvolution::isBackedgeTakenCountMaxOrZero(const Loop *L) {
7788 return getBackedgeTakenInfo(L).isConstantMaxOrZero(this);
7789}
7790
7791/// Push PHI nodes in the header of the given loop onto the given Worklist.
7792static void PushLoopPHIs(const Loop *L,
7793 SmallVectorImpl<Instruction *> &Worklist,
7794 SmallPtrSetImpl<Instruction *> &Visited) {
7795 BasicBlock *Header = L->getHeader();
7796
7797 // Push all Loop-header PHIs onto the Worklist stack.
7798 for (PHINode &PN : Header->phis())
7799 if (Visited.insert(&PN).second)
7800 Worklist.push_back(&PN);
7801}
7802
7803const ScalarEvolution::BackedgeTakenInfo &
7804ScalarEvolution::getPredicatedBackedgeTakenInfo(const Loop *L) {
7805 auto &BTI = getBackedgeTakenInfo(L);
7806 if (BTI.hasFullInfo())
7807 return BTI;
7808
7809 auto Pair = PredicatedBackedgeTakenCounts.insert({L, BackedgeTakenInfo()});
7810
7811 if (!Pair.second)
7812 return Pair.first->second;
7813
7814 BackedgeTakenInfo Result =
7815 computeBackedgeTakenCount(L, /*AllowPredicates=*/true);
7816
7817 return PredicatedBackedgeTakenCounts.find(L)->second = std::move(Result);
7818}
7819
7820ScalarEvolution::BackedgeTakenInfo &
7821ScalarEvolution::getBackedgeTakenInfo(const Loop *L) {
7822 // Initially insert an invalid entry for this loop. If the insertion
7823 // succeeds, proceed to actually compute a backedge-taken count and
7824 // update the value. The temporary CouldNotCompute value tells SCEV
7825 // code elsewhere that it shouldn't attempt to request a new
7826 // backedge-taken count, which could result in infinite recursion.
7827 std::pair<DenseMap<const Loop *, BackedgeTakenInfo>::iterator, bool> Pair =
7828 BackedgeTakenCounts.insert({L, BackedgeTakenInfo()});
7829 if (!Pair.second)
7830 return Pair.first->second;
7831
7832 // computeBackedgeTakenCount may allocate memory for its result. Inserting it
7833 // into the BackedgeTakenCounts map transfers ownership. Otherwise, the result
7834 // must be cleared in this scope.
7835 BackedgeTakenInfo Result = computeBackedgeTakenCount(L);
7836
7837 // In product build, there are no usage of statistic.
7838 (void)NumTripCountsComputed;
7839 (void)NumTripCountsNotComputed;
7840#if LLVM_ENABLE_STATS1 || !defined(NDEBUG)
7841 const SCEV *BEExact = Result.getExact(L, this);
7842 if (BEExact != getCouldNotCompute()) {
7843 assert(isLoopInvariant(BEExact, L) &&(static_cast <bool> (isLoopInvariant(BEExact, L) &&
isLoopInvariant(Result.getConstantMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!"
) ? void (0) : __assert_fail ("isLoopInvariant(BEExact, L) && isLoopInvariant(Result.getConstantMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 7845, __extension__
__PRETTY_FUNCTION__))
7844 isLoopInvariant(Result.getConstantMax(this), L) &&(static_cast <bool> (isLoopInvariant(BEExact, L) &&
isLoopInvariant(Result.getConstantMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!"
) ? void (0) : __assert_fail ("isLoopInvariant(BEExact, L) && isLoopInvariant(Result.getConstantMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 7845, __extension__
__PRETTY_FUNCTION__))
7845 "Computed backedge-taken count isn't loop invariant for loop!")(static_cast <bool> (isLoopInvariant(BEExact, L) &&
isLoopInvariant(Result.getConstantMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!"
) ? void (0) : __assert_fail ("isLoopInvariant(BEExact, L) && isLoopInvariant(Result.getConstantMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 7845, __extension__
__PRETTY_FUNCTION__));
7846 ++NumTripCountsComputed;
7847 } else if (Result.getConstantMax(this) == getCouldNotCompute() &&
7848 isa<PHINode>(L->getHeader()->begin())) {
7849 // Only count loops that have phi nodes as not being computable.
7850 ++NumTripCountsNotComputed;
7851 }
7852#endif // LLVM_ENABLE_STATS || !defined(NDEBUG)
7853
7854 // Now that we know more about the trip count for this loop, forget any
7855 // existing SCEV values for PHI nodes in this loop since they are only
7856 // conservative estimates made without the benefit of trip count
7857 // information. This invalidation is not necessary for correctness, and is
7858 // only done to produce more precise results.
7859 if (Result.hasAnyInfo()) {
7860 // Invalidate any expression using an addrec in this loop.
7861 SmallVector<const SCEV *, 8> ToForget;
7862 auto LoopUsersIt = LoopUsers.find(L);
7863 if (LoopUsersIt != LoopUsers.end())
7864 append_range(ToForget, LoopUsersIt->second);
7865 forgetMemoizedResults(ToForget);
7866
7867 // Invalidate constant-evolved loop header phis.
7868 for (PHINode &PN : L->getHeader()->phis())
7869 ConstantEvolutionLoopExitValue.erase(&PN);
7870 }
7871
7872 // Re-lookup the insert position, since the call to
7873 // computeBackedgeTakenCount above could result in a
7874 // recusive call to getBackedgeTakenInfo (on a different
7875 // loop), which would invalidate the iterator computed
7876 // earlier.
7877 return BackedgeTakenCounts.find(L)->second = std::move(Result);
7878}
7879
7880void ScalarEvolution::forgetAllLoops() {
7881 // This method is intended to forget all info about loops. It should
7882 // invalidate caches as if the following happened:
7883 // - The trip counts of all loops have changed arbitrarily
7884 // - Every llvm::Value has been updated in place to produce a different
7885 // result.
7886 BackedgeTakenCounts.clear();
7887 PredicatedBackedgeTakenCounts.clear();
7888 BECountUsers.clear();
7889 LoopPropertiesCache.clear();
7890 ConstantEvolutionLoopExitValue.clear();
7891 ValueExprMap.clear();
7892 ValuesAtScopes.clear();
7893 ValuesAtScopesUsers.clear();
7894 LoopDispositions.clear();
7895 BlockDispositions.clear();
7896 UnsignedRanges.clear();
7897 SignedRanges.clear();
7898 ExprValueMap.clear();
7899 HasRecMap.clear();
7900 MinTrailingZerosCache.clear();
7901 PredicatedSCEVRewrites.clear();
7902}
7903
7904void ScalarEvolution::forgetLoop(const Loop *L) {
7905 SmallVector<const Loop *, 16> LoopWorklist(1, L);
7906 SmallVector<Instruction *, 32> Worklist;
7907 SmallPtrSet<Instruction *, 16> Visited;
7908 SmallVector<const SCEV *, 16> ToForget;
7909
7910 // Iterate over all the loops and sub-loops to drop SCEV information.
7911 while (!LoopWorklist.empty()) {
7912 auto *CurrL = LoopWorklist.pop_back_val();
7913
7914 // Drop any stored trip count value.
7915 forgetBackedgeTakenCounts(CurrL, /* Predicated */ false);
7916 forgetBackedgeTakenCounts(CurrL, /* Predicated */ true);
7917
7918 // Drop information about predicated SCEV rewrites for this loop.
7919 for (auto I = PredicatedSCEVRewrites.begin();
7920 I != PredicatedSCEVRewrites.end();) {
7921 std::pair<const SCEV *, const Loop *> Entry = I->first;
7922 if (Entry.second == CurrL)
7923 PredicatedSCEVRewrites.erase(I++);
7924 else
7925 ++I;
7926 }
7927
7928 auto LoopUsersItr = LoopUsers.find(CurrL);
7929 if (LoopUsersItr != LoopUsers.end()) {
7930 ToForget.insert(ToForget.end(), LoopUsersItr->second.begin(),
7931 LoopUsersItr->second.end());
7932 }
7933
7934 // Drop information about expressions based on loop-header PHIs.
7935 PushLoopPHIs(CurrL, Worklist, Visited);
7936
7937 while (!Worklist.empty()) {
7938 Instruction *I = Worklist.pop_back_val();
7939
7940 ValueExprMapType::iterator It =
7941 ValueExprMap.find_as(static_cast<Value *>(I));
7942 if (It != ValueExprMap.end()) {
7943 eraseValueFromMap(It->first);
7944 ToForget.push_back(It->second);
7945 if (PHINode *PN = dyn_cast<PHINode>(I))
7946 ConstantEvolutionLoopExitValue.erase(PN);
7947 }
7948
7949 PushDefUseChildren(I, Worklist, Visited);
7950 }
7951
7952 LoopPropertiesCache.erase(CurrL);
7953 // Forget all contained loops too, to avoid dangling entries in the
7954 // ValuesAtScopes map.
7955 LoopWorklist.append(CurrL->begin(), CurrL->end());
7956 }
7957 forgetMemoizedResults(ToForget);
7958}
7959
7960void ScalarEvolution::forgetTopmostLoop(const Loop *L) {
7961 while (Loop *Parent = L->getParentLoop())
7962 L = Parent;
7963 forgetLoop(L);
7964}
7965
7966void ScalarEvolution::forgetValue(Value *V) {
7967 Instruction *I = dyn_cast<Instruction>(V);
7968 if (!I) return;
7969
7970 // Drop information about expressions based on loop-header PHIs.
7971 SmallVector<Instruction *, 16> Worklist;
7972 SmallPtrSet<Instruction *, 8> Visited;
7973 SmallVector<const SCEV *, 8> ToForget;
7974 Worklist.push_back(I);
7975 Visited.insert(I);
7976
7977 while (!Worklist.empty()) {
7978 I = Worklist.pop_back_val();
7979 ValueExprMapType::iterator It =
7980 ValueExprMap.find_as(static_cast<Value *>(I));
7981 if (It != ValueExprMap.end()) {
7982 eraseValueFromMap(It->first);
7983 ToForget.push_back(It->second);
7984 if (PHINode *PN = dyn_cast<PHINode>(I))
7985 ConstantEvolutionLoopExitValue.erase(PN);
7986 }
7987
7988 PushDefUseChildren(I, Worklist, Visited);
7989 }
7990 forgetMemoizedResults(ToForget);
7991}
7992
7993void ScalarEvolution::forgetLoopDispositions(const Loop *L) {
7994 LoopDispositions.clear();
7995}
7996
7997/// Get the exact loop backedge taken count considering all loop exits. A
7998/// computable result can only be returned for loops with all exiting blocks
7999/// dominating the latch. howFarToZero assumes that the limit of each loop test
8000/// is never skipped. This is a valid assumption as long as the loop exits via
8001/// that test. For precise results, it is the caller's responsibility to specify
8002/// the relevant loop exiting block using getExact(ExitingBlock, SE).
8003const SCEV *
8004ScalarEvolution::BackedgeTakenInfo::getExact(const Loop *L, ScalarEvolution *SE,
8005 SmallVector<const SCEVPredicate *, 4> *Preds) const {
8006 // If any exits were not computable, the loop is not computable.
8007 if (!isComplete() || ExitNotTaken.empty())
8008 return SE->getCouldNotCompute();
8009
8010 const BasicBlock *Latch = L->getLoopLatch();
8011 // All exiting blocks we have collected must dominate the only backedge.
8012 if (!Latch)
8013 return SE->getCouldNotCompute();
8014
8015 // All exiting blocks we have gathered dominate loop's latch, so exact trip
8016 // count is simply a minimum out of all these calculated exit counts.
8017 SmallVector<const SCEV *, 2> Ops;
8018 for (auto &ENT : ExitNotTaken) {
8019 const SCEV *BECount = ENT.ExactNotTaken;
8020 assert(BECount != SE->getCouldNotCompute() && "Bad exit SCEV!")(static_cast <bool> (BECount != SE->getCouldNotCompute
() && "Bad exit SCEV!") ? void (0) : __assert_fail ("BECount != SE->getCouldNotCompute() && \"Bad exit SCEV!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8020, __extension__
__PRETTY_FUNCTION__));
8021 assert(SE->DT.dominates(ENT.ExitingBlock, Latch) &&(static_cast <bool> (SE->DT.dominates(ENT.ExitingBlock
, Latch) && "We should only have known counts for exiting blocks that dominate "
"latch!") ? void (0) : __assert_fail ("SE->DT.dominates(ENT.ExitingBlock, Latch) && \"We should only have known counts for exiting blocks that dominate \" \"latch!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8023, __extension__
__PRETTY_FUNCTION__))
8022 "We should only have known counts for exiting blocks that dominate "(static_cast <bool> (SE->DT.dominates(ENT.ExitingBlock
, Latch) && "We should only have known counts for exiting blocks that dominate "
"latch!") ? void (0) : __assert_fail ("SE->DT.dominates(ENT.ExitingBlock, Latch) && \"We should only have known counts for exiting blocks that dominate \" \"latch!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8023, __extension__
__PRETTY_FUNCTION__))
8023 "latch!")(static_cast <bool> (SE->DT.dominates(ENT.ExitingBlock
, Latch) && "We should only have known counts for exiting blocks that dominate "
"latch!") ? void (0) : __assert_fail ("SE->DT.dominates(ENT.ExitingBlock, Latch) && \"We should only have known counts for exiting blocks that dominate \" \"latch!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8023, __extension__
__PRETTY_FUNCTION__));
8024
8025 Ops.push_back(BECount);
8026
8027 if (Preds)
8028 for (auto *P : ENT.Predicates)
8029 Preds->push_back(P);
8030
8031 assert((Preds || ENT.hasAlwaysTruePredicate()) &&(static_cast <bool> ((Preds || ENT.hasAlwaysTruePredicate
()) && "Predicate should be always true!") ? void (0)
: __assert_fail ("(Preds || ENT.hasAlwaysTruePredicate()) && \"Predicate should be always true!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8032, __extension__
__PRETTY_FUNCTION__))
8032 "Predicate should be always true!")(static_cast <bool> ((Preds || ENT.hasAlwaysTruePredicate
()) && "Predicate should be always true!") ? void (0)
: __assert_fail ("(Preds || ENT.hasAlwaysTruePredicate()) && \"Predicate should be always true!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8032, __extension__
__PRETTY_FUNCTION__));
8033 }
8034
8035 return SE->getUMinFromMismatchedTypes(Ops);
8036}
8037
8038/// Get the exact not taken count for this loop exit.
8039const SCEV *
8040ScalarEvolution::BackedgeTakenInfo::getExact(const BasicBlock *ExitingBlock,
8041 ScalarEvolution *SE) const {
8042 for (auto &ENT : ExitNotTaken)
8043 if (ENT.ExitingBlock == ExitingBlock && ENT.hasAlwaysTruePredicate())
8044 return ENT.ExactNotTaken;
8045
8046 return SE->getCouldNotCompute();
8047}
8048
8049const SCEV *ScalarEvolution::BackedgeTakenInfo::getConstantMax(
8050 const BasicBlock *ExitingBlock, ScalarEvolution *SE) const {
8051 for (auto &ENT : ExitNotTaken)
8052 if (ENT.ExitingBlock == ExitingBlock && ENT.hasAlwaysTruePredicate())
8053 return ENT.MaxNotTaken;
8054
8055 return SE->getCouldNotCompute();
8056}
8057
8058/// getConstantMax - Get the constant max backedge taken count for the loop.
8059const SCEV *
8060ScalarEvolution::BackedgeTakenInfo::getConstantMax(ScalarEvolution *SE) const {
8061 auto PredicateNotAlwaysTrue = [](const ExitNotTakenInfo &ENT) {
8062 return !ENT.hasAlwaysTruePredicate();
8063 };
8064
8065 if (!getConstantMax() || any_of(ExitNotTaken, PredicateNotAlwaysTrue))
8066 return SE->getCouldNotCompute();
8067
8068 assert((isa<SCEVCouldNotCompute>(getConstantMax()) ||(static_cast <bool> ((isa<SCEVCouldNotCompute>(getConstantMax
()) || isa<SCEVConstant>(getConstantMax())) && "No point in having a non-constant max backedge taken count!"
) ? void (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(getConstantMax()) || isa<SCEVConstant>(getConstantMax())) && \"No point in having a non-constant max backedge taken count!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8070, __extension__
__PRETTY_FUNCTION__))
8069 isa<SCEVConstant>(getConstantMax())) &&(static_cast <bool> ((isa<SCEVCouldNotCompute>(getConstantMax
()) || isa<SCEVConstant>(getConstantMax())) && "No point in having a non-constant max backedge taken count!"
) ? void (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(getConstantMax()) || isa<SCEVConstant>(getConstantMax())) && \"No point in having a non-constant max backedge taken count!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8070, __extension__
__PRETTY_FUNCTION__))
8070 "No point in having a non-constant max backedge taken count!")(static_cast <bool> ((isa<SCEVCouldNotCompute>(getConstantMax
()) || isa<SCEVConstant>(getConstantMax())) && "No point in having a non-constant max backedge taken count!"
) ? void (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(getConstantMax()) || isa<SCEVConstant>(getConstantMax())) && \"No point in having a non-constant max backedge taken count!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8070, __extension__
__PRETTY_FUNCTION__));
8071 return getConstantMax();
8072}
8073
8074const SCEV *
8075ScalarEvolution::BackedgeTakenInfo::getSymbolicMax(const Loop *L,
8076 ScalarEvolution *SE) {
8077 if (!SymbolicMax)
8078 SymbolicMax = SE->computeSymbolicMaxBackedgeTakenCount(L);
8079 return SymbolicMax;
8080}
8081
8082bool ScalarEvolution::BackedgeTakenInfo::isConstantMaxOrZero(
8083 ScalarEvolution *SE) const {
8084 auto PredicateNotAlwaysTrue = [](const ExitNotTakenInfo &ENT) {
8085 return !ENT.hasAlwaysTruePredicate();
8086 };
8087 return MaxOrZero && !any_of(ExitNotTaken, PredicateNotAlwaysTrue);
8088}
8089
8090ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E)
8091 : ExitLimit(E, E, false, None) {
8092}
8093
8094ScalarEvolution::ExitLimit::ExitLimit(
8095 const SCEV *E, const SCEV *M, bool MaxOrZero,
8096 ArrayRef<const SmallPtrSetImpl<const SCEVPredicate *> *> PredSetList)
8097 : ExactNotTaken(E), MaxNotTaken(M), MaxOrZero(MaxOrZero) {
8098 // If we prove the max count is zero, so is the symbolic bound. This happens
8099 // in practice due to differences in a) how context sensitive we've chosen
8100 // to be and b) how we reason about bounds impied by UB.
8101 if (MaxNotTaken->isZero())
8102 ExactNotTaken = MaxNotTaken;
8103
8104 assert((isa<SCEVCouldNotCompute>(ExactNotTaken) ||(static_cast <bool> ((isa<SCEVCouldNotCompute>(ExactNotTaken
) || !isa<SCEVCouldNotCompute>(MaxNotTaken)) &&
"Exact is not allowed to be less precise than Max") ? void (
0) : __assert_fail ("(isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute>(MaxNotTaken)) && \"Exact is not allowed to be less precise than Max\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8106, __extension__
__PRETTY_FUNCTION__))
8105 !isa<SCEVCouldNotCompute>(MaxNotTaken)) &&(static_cast <bool> ((isa<SCEVCouldNotCompute>(ExactNotTaken
) || !isa<SCEVCouldNotCompute>(MaxNotTaken)) &&
"Exact is not allowed to be less precise than Max") ? void (
0) : __assert_fail ("(isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute>(MaxNotTaken)) && \"Exact is not allowed to be less precise than Max\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8106, __extension__
__PRETTY_FUNCTION__))
8106 "Exact is not allowed to be less precise than Max")(static_cast <bool> ((isa<SCEVCouldNotCompute>(ExactNotTaken
) || !isa<SCEVCouldNotCompute>(MaxNotTaken)) &&
"Exact is not allowed to be less precise than Max") ? void (
0) : __assert_fail ("(isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute>(MaxNotTaken)) && \"Exact is not allowed to be less precise than Max\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8106, __extension__
__PRETTY_FUNCTION__));
8107 assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||(static_cast <bool> ((isa<SCEVCouldNotCompute>(MaxNotTaken
) || isa<SCEVConstant>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? void (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8109, __extension__
__PRETTY_FUNCTION__))
8108 isa<SCEVConstant>(MaxNotTaken)) &&(static_cast <bool> ((isa<SCEVCouldNotCompute>(MaxNotTaken
) || isa<SCEVConstant>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? void (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8109, __extension__
__PRETTY_FUNCTION__))
8109 "No point in having a non-constant max backedge taken count!")(static_cast <bool> ((isa<SCEVCouldNotCompute>(MaxNotTaken
) || isa<SCEVConstant>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? void (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8109, __extension__
__PRETTY_FUNCTION__));
8110 for (auto *PredSet : PredSetList)
8111 for (auto *P : *PredSet)
8112 addPredicate(P);
8113 assert((isa<SCEVCouldNotCompute>(E) || !E->getType()->isPointerTy()) &&(static_cast <bool> ((isa<SCEVCouldNotCompute>(E)
|| !E->getType()->isPointerTy()) && "Backedge count should be int"
) ? void (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(E) || !E->getType()->isPointerTy()) && \"Backedge count should be int\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8114, __extension__
__PRETTY_FUNCTION__))
8114 "Backedge count should be int")(static_cast <bool> ((isa<SCEVCouldNotCompute>(E)
|| !E->getType()->isPointerTy()) && "Backedge count should be int"
) ? void (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(E) || !E->getType()->isPointerTy()) && \"Backedge count should be int\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8114, __extension__
__PRETTY_FUNCTION__));
8115 assert((isa<SCEVCouldNotCompute>(M) || !M->getType()->isPointerTy()) &&(static_cast <bool> ((isa<SCEVCouldNotCompute>(M)
|| !M->getType()->isPointerTy()) && "Max backedge count should be int"
) ? void (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(M) || !M->getType()->isPointerTy()) && \"Max backedge count should be int\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8116, __extension__
__PRETTY_FUNCTION__))
8116 "Max backedge count should be int")(static_cast <bool> ((isa<SCEVCouldNotCompute>(M)
|| !M->getType()->isPointerTy()) && "Max backedge count should be int"
) ? void (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(M) || !M->getType()->isPointerTy()) && \"Max backedge count should be int\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8116, __extension__
__PRETTY_FUNCTION__));
8117}
8118
8119ScalarEvolution::ExitLimit::ExitLimit(
8120 const SCEV *E, const SCEV *M, bool MaxOrZero,
8121 const SmallPtrSetImpl<const SCEVPredicate *> &PredSet)
8122 : ExitLimit(E, M, MaxOrZero, {&PredSet}) {
8123}
8124
8125ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E, const SCEV *M,
8126 bool MaxOrZero)
8127 : ExitLimit(E, M, MaxOrZero, None) {
8128}
8129
8130/// Allocate memory for BackedgeTakenInfo and copy the not-taken count of each
8131/// computable exit into a persistent ExitNotTakenInfo array.
8132ScalarEvolution::BackedgeTakenInfo::BackedgeTakenInfo(
8133 ArrayRef<ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo> ExitCounts,
8134 bool IsComplete, const SCEV *ConstantMax, bool MaxOrZero)
8135 : ConstantMax(ConstantMax), IsComplete(IsComplete), MaxOrZero(MaxOrZero) {
8136 using EdgeExitInfo = ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo;
8137
8138 ExitNotTaken.reserve(ExitCounts.size());
8139 std::transform(
8140 ExitCounts.begin(), ExitCounts.end(), std::back_inserter(ExitNotTaken),
8141 [&](const EdgeExitInfo &EEI) {
8142 BasicBlock *ExitBB = EEI.first;
8143 const ExitLimit &EL = EEI.second;
8144 return ExitNotTakenInfo(ExitBB, EL.ExactNotTaken, EL.MaxNotTaken,
8145 EL.Predicates);
8146 });
8147 assert((isa<SCEVCouldNotCompute>(ConstantMax) ||(static_cast <bool> ((isa<SCEVCouldNotCompute>(ConstantMax
) || isa<SCEVConstant>(ConstantMax)) && "No point in having a non-constant max backedge taken count!"
) ? void (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(ConstantMax) || isa<SCEVConstant>(ConstantMax)) && \"No point in having a non-constant max backedge taken count!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8149, __extension__
__PRETTY_FUNCTION__))
8148 isa<SCEVConstant>(ConstantMax)) &&(static_cast <bool> ((isa<SCEVCouldNotCompute>(ConstantMax
) || isa<SCEVConstant>(ConstantMax)) && "No point in having a non-constant max backedge taken count!"
) ? void (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(ConstantMax) || isa<SCEVConstant>(ConstantMax)) && \"No point in having a non-constant max backedge taken count!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8149, __extension__
__PRETTY_FUNCTION__))
8149 "No point in having a non-constant max backedge taken count!")(static_cast <bool> ((isa<SCEVCouldNotCompute>(ConstantMax
) || isa<SCEVConstant>(ConstantMax)) && "No point in having a non-constant max backedge taken count!"
) ? void (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(ConstantMax) || isa<SCEVConstant>(ConstantMax)) && \"No point in having a non-constant max backedge taken count!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8149, __extension__
__PRETTY_FUNCTION__));
8150}
8151
8152/// Compute the number of times the backedge of the specified loop will execute.
8153ScalarEvolution::BackedgeTakenInfo
8154ScalarEvolution::computeBackedgeTakenCount(const Loop *L,
8155 bool AllowPredicates) {
8156 SmallVector<BasicBlock *, 8> ExitingBlocks;
8157 L->getExitingBlocks(ExitingBlocks);
8158
8159 using EdgeExitInfo = ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo;
8160
8161 SmallVector<EdgeExitInfo, 4> ExitCounts;
8162 bool CouldComputeBECount = true;
8163 BasicBlock *Latch = L->getLoopLatch(); // may be NULL.
8164 const SCEV *MustExitMaxBECount = nullptr;
8165 const SCEV *MayExitMaxBECount = nullptr;
8166 bool MustExitMaxOrZero = false;
8167
8168 // Compute the ExitLimit for each loop exit. Use this to populate ExitCounts
8169 // and compute maxBECount.
8170 // Do a union of all the predicates here.
8171 for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) {
8172 BasicBlock *ExitBB = ExitingBlocks[i];
8173
8174 // We canonicalize untaken exits to br (constant), ignore them so that
8175 // proving an exit untaken doesn't negatively impact our ability to reason
8176 // about the loop as whole.
8177 if (auto *BI = dyn_cast<BranchInst>(ExitBB->getTerminator()))
8178 if (auto *CI = dyn_cast<ConstantInt>(BI->getCondition())) {
8179 bool ExitIfTrue = !L->contains(BI->getSuccessor(0));
8180 if (ExitIfTrue == CI->isZero())
8181 continue;
8182 }
8183
8184 ExitLimit EL = computeExitLimit(L, ExitBB, AllowPredicates);
8185
8186 assert((AllowPredicates || EL.Predicates.empty()) &&(static_cast <bool> ((AllowPredicates || EL.Predicates.
empty()) && "Predicated exit limit when predicates are not allowed!"
) ? void (0) : __assert_fail ("(AllowPredicates || EL.Predicates.empty()) && \"Predicated exit limit when predicates are not allowed!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8187, __extension__
__PRETTY_FUNCTION__))
8187 "Predicated exit limit when predicates are not allowed!")(static_cast <bool> ((AllowPredicates || EL.Predicates.
empty()) && "Predicated exit limit when predicates are not allowed!"
) ? void (0) : __assert_fail ("(AllowPredicates || EL.Predicates.empty()) && \"Predicated exit limit when predicates are not allowed!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8187, __extension__
__PRETTY_FUNCTION__));
8188
8189 // 1. For each exit that can be computed, add an entry to ExitCounts.
8190 // CouldComputeBECount is true only if all exits can be computed.
8191 if (EL.ExactNotTaken == getCouldNotCompute())
8192 // We couldn't compute an exact value for this exit, so
8193 // we won't be able to compute an exact value for the loop.
8194 CouldComputeBECount = false;
8195 else
8196 ExitCounts.emplace_back(ExitBB, EL);
8197
8198 // 2. Derive the loop's MaxBECount from each exit's max number of
8199 // non-exiting iterations. Partition the loop exits into two kinds:
8200 // LoopMustExits and LoopMayExits.
8201 //
8202 // If the exit dominates the loop latch, it is a LoopMustExit otherwise it
8203 // is a LoopMayExit. If any computable LoopMustExit is found, then
8204 // MaxBECount is the minimum EL.MaxNotTaken of computable
8205 // LoopMustExits. Otherwise, MaxBECount is conservatively the maximum
8206 // EL.MaxNotTaken, where CouldNotCompute is considered greater than any
8207 // computable EL.MaxNotTaken.
8208 if (EL.MaxNotTaken != getCouldNotCompute() && Latch &&
8209 DT.dominates(ExitBB, Latch)) {
8210 if (!MustExitMaxBECount) {
8211 MustExitMaxBECount = EL.MaxNotTaken;
8212 MustExitMaxOrZero = EL.MaxOrZero;
8213 } else {
8214 MustExitMaxBECount =
8215 getUMinFromMismatchedTypes(MustExitMaxBECount, EL.MaxNotTaken);
8216 }
8217 } else if (MayExitMaxBECount != getCouldNotCompute()) {
8218 if (!MayExitMaxBECount || EL.MaxNotTaken == getCouldNotCompute())
8219 MayExitMaxBECount = EL.MaxNotTaken;
8220 else {
8221 MayExitMaxBECount =
8222 getUMaxFromMismatchedTypes(MayExitMaxBECount, EL.MaxNotTaken);
8223 }
8224 }
8225 }
8226 const SCEV *MaxBECount = MustExitMaxBECount ? MustExitMaxBECount :
8227 (MayExitMaxBECount ? MayExitMaxBECount : getCouldNotCompute());
8228 // The loop backedge will be taken the maximum or zero times if there's
8229 // a single exit that must be taken the maximum or zero times.
8230 bool MaxOrZero = (MustExitMaxOrZero && ExitingBlocks.size() == 1);
8231
8232 // Remember which SCEVs are used in exit limits for invalidation purposes.
8233 // We only care about non-constant SCEVs here, so we can ignore EL.MaxNotTaken
8234 // and MaxBECount, which must be SCEVConstant.
8235 for (const auto &Pair : ExitCounts)
8236 if (!isa<SCEVConstant>(Pair.second.ExactNotTaken))
8237 BECountUsers[Pair.second.ExactNotTaken].insert({L, AllowPredicates});
8238 return BackedgeTakenInfo(std::move(ExitCounts), CouldComputeBECount,
8239 MaxBECount, MaxOrZero);
8240}
8241
8242ScalarEvolution::ExitLimit
8243ScalarEvolution::computeExitLimit(const Loop *L, BasicBlock *ExitingBlock,
8244 bool AllowPredicates) {
8245 assert(L->contains(ExitingBlock) && "Exit count for non-loop block?")(static_cast <bool> (L->contains(ExitingBlock) &&
"Exit count for non-loop block?") ? void (0) : __assert_fail
("L->contains(ExitingBlock) && \"Exit count for non-loop block?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8245, __extension__
__PRETTY_FUNCTION__));
8246 // If our exiting block does not dominate the latch, then its connection with
8247 // loop's exit limit may be far from trivial.
8248 const BasicBlock *Latch = L->getLoopLatch();
8249 if (!Latch || !DT.dominates(ExitingBlock, Latch))
8250 return getCouldNotCompute();
8251
8252 bool IsOnlyExit = (L->getExitingBlock() != nullptr);
8253 Instruction *Term = ExitingBlock->getTerminator();
8254 if (BranchInst *BI = dyn_cast<BranchInst>(Term)) {
8255 assert(BI->isConditional() && "If unconditional, it can't be in loop!")(static_cast <bool> (BI->isConditional() && "If unconditional, it can't be in loop!"
) ? void (0) : __assert_fail ("BI->isConditional() && \"If unconditional, it can't be in loop!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8255, __extension__
__PRETTY_FUNCTION__));
8256 bool ExitIfTrue = !L->contains(BI->getSuccessor(0));
8257 assert(ExitIfTrue == L->contains(BI->getSuccessor(1)) &&(static_cast <bool> (ExitIfTrue == L->contains(BI->
getSuccessor(1)) && "It should have one successor in loop and one exit block!"
) ? void (0) : __assert_fail ("ExitIfTrue == L->contains(BI->getSuccessor(1)) && \"It should have one successor in loop and one exit block!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8258, __extension__
__PRETTY_FUNCTION__))
8258 "It should have one successor in loop and one exit block!")(static_cast <bool> (ExitIfTrue == L->contains(BI->
getSuccessor(1)) && "It should have one successor in loop and one exit block!"
) ? void (0) : __assert_fail ("ExitIfTrue == L->contains(BI->getSuccessor(1)) && \"It should have one successor in loop and one exit block!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8258, __extension__
__PRETTY_FUNCTION__));
8259 // Proceed to the next level to examine the exit condition expression.
8260 return computeExitLimitFromCond(
8261 L, BI->getCondition(), ExitIfTrue,
8262 /*ControlsExit=*/IsOnlyExit, AllowPredicates);
8263 }
8264
8265 if (SwitchInst *SI = dyn_cast<SwitchInst>(Term)) {
8266 // For switch, make sure that there is a single exit from the loop.
8267 BasicBlock *Exit = nullptr;
8268 for (auto *SBB : successors(ExitingBlock))
8269 if (!L->contains(SBB)) {
8270 if (Exit) // Multiple exit successors.
8271 return getCouldNotCompute();
8272 Exit = SBB;
8273 }
8274 assert(Exit && "Exiting block must have at least one exit")(static_cast <bool> (Exit && "Exiting block must have at least one exit"
) ? void (0) : __assert_fail ("Exit && \"Exiting block must have at least one exit\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8274, __extension__
__PRETTY_FUNCTION__));
8275 return computeExitLimitFromSingleExitSwitch(L, SI, Exit,
8276 /*ControlsExit=*/IsOnlyExit);
8277 }
8278
8279 return getCouldNotCompute();
8280}
8281
8282ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCond(
8283 const Loop *L, Value *ExitCond, bool ExitIfTrue,
8284 bool ControlsExit, bool AllowPredicates) {
8285 ScalarEvolution::ExitLimitCacheTy Cache(L, ExitIfTrue, AllowPredicates);
8286 return computeExitLimitFromCondCached(Cache, L, ExitCond, ExitIfTrue,
8287 ControlsExit, AllowPredicates);
8288}
8289
8290Optional<ScalarEvolution::ExitLimit>
8291ScalarEvolution::ExitLimitCache::find(const Loop *L, Value *ExitCond,
8292 bool ExitIfTrue, bool ControlsExit,
8293 bool AllowPredicates) {
8294 (void)this->L;
8295 (void)this->ExitIfTrue;
8296 (void)this->AllowPredicates;
8297
8298 assert(this->L == L && this->ExitIfTrue == ExitIfTrue &&(static_cast <bool> (this->L == L && this->
ExitIfTrue == ExitIfTrue && this->AllowPredicates ==
AllowPredicates && "Variance in assumed invariant key components!"
) ? void (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8300, __extension__
__PRETTY_FUNCTION__))
8299 this->AllowPredicates == AllowPredicates &&(static_cast <bool> (this->L == L && this->
ExitIfTrue == ExitIfTrue && this->AllowPredicates ==
AllowPredicates && "Variance in assumed invariant key components!"
) ? void (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8300, __extension__
__PRETTY_FUNCTION__))
8300 "Variance in assumed invariant key components!")(static_cast <bool> (this->L == L && this->
ExitIfTrue == ExitIfTrue && this->AllowPredicates ==
AllowPredicates && "Variance in assumed invariant key components!"
) ? void (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8300, __extension__
__PRETTY_FUNCTION__));
8301 auto Itr = TripCountMap.find({ExitCond, ControlsExit});
8302 if (Itr == TripCountMap.end())
8303 return None;
8304 return Itr->second;
8305}
8306
8307void ScalarEvolution::ExitLimitCache::insert(const Loop *L, Value *ExitCond,
8308 bool ExitIfTrue,
8309 bool ControlsExit,
8310 bool AllowPredicates,
8311 const ExitLimit &EL) {
8312 assert(this->L == L && this->ExitIfTrue == ExitIfTrue &&(static_cast <bool> (this->L == L && this->
ExitIfTrue == ExitIfTrue && this->AllowPredicates ==
AllowPredicates && "Variance in assumed invariant key components!"
) ? void (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8314, __extension__
__PRETTY_FUNCTION__))
8313 this->AllowPredicates == AllowPredicates &&(static_cast <bool> (this->L == L && this->
ExitIfTrue == ExitIfTrue && this->AllowPredicates ==
AllowPredicates && "Variance in assumed invariant key components!"
) ? void (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8314, __extension__
__PRETTY_FUNCTION__))
8314 "Variance in assumed invariant key components!")(static_cast <bool> (this->L == L && this->
ExitIfTrue == ExitIfTrue && this->AllowPredicates ==
AllowPredicates && "Variance in assumed invariant key components!"
) ? void (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8314, __extension__
__PRETTY_FUNCTION__));
8315
8316 auto InsertResult = TripCountMap.insert({{ExitCond, ControlsExit}, EL});
8317 assert(InsertResult.second && "Expected successful insertion!")(static_cast <bool> (InsertResult.second && "Expected successful insertion!"
) ? void (0) : __assert_fail ("InsertResult.second && \"Expected successful insertion!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8317, __extension__
__PRETTY_FUNCTION__));
8318 (void)InsertResult;
8319 (void)ExitIfTrue;
8320}
8321
8322ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondCached(
8323 ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, bool ExitIfTrue,
8324 bool ControlsExit, bool AllowPredicates) {
8325
8326 if (auto MaybeEL =
8327 Cache.find(L, ExitCond, ExitIfTrue, ControlsExit, AllowPredicates))
8328 return *MaybeEL;
8329
8330 ExitLimit EL = computeExitLimitFromCondImpl(Cache, L, ExitCond, ExitIfTrue,
8331 ControlsExit, AllowPredicates);
8332 Cache.insert(L, ExitCond, ExitIfTrue, ControlsExit, AllowPredicates, EL);
8333 return EL;
8334}
8335
8336ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondImpl(
8337 ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, bool ExitIfTrue,
8338 bool ControlsExit, bool AllowPredicates) {
8339 // Handle BinOp conditions (And, Or).
8340 if (auto LimitFromBinOp = computeExitLimitFromCondFromBinOp(
8341 Cache, L, ExitCond, ExitIfTrue, ControlsExit, AllowPredicates))
8342 return *LimitFromBinOp;
8343
8344 // With an icmp, it may be feasible to compute an exact backedge-taken count.
8345 // Proceed to the next level to examine the icmp.
8346 if (ICmpInst *ExitCondICmp = dyn_cast<ICmpInst>(ExitCond)) {
8347 ExitLimit EL =
8348 computeExitLimitFromICmp(L, ExitCondICmp, ExitIfTrue, ControlsExit);
8349 if (EL.hasFullInfo() || !AllowPredicates)
8350 return EL;
8351
8352 // Try again, but use SCEV predicates this time.
8353 return computeExitLimitFromICmp(L, ExitCondICmp, ExitIfTrue, ControlsExit,
8354 /*AllowPredicates=*/true);
8355 }
8356
8357 // Check for a constant condition. These are normally stripped out by
8358 // SimplifyCFG, but ScalarEvolution may be used by a pass which wishes to
8359 // preserve the CFG and is temporarily leaving constant conditions
8360 // in place.
8361 if (ConstantInt *CI = dyn_cast<ConstantInt>(ExitCond)) {
8362 if (ExitIfTrue == !CI->getZExtValue())
8363 // The backedge is always taken.
8364 return getCouldNotCompute();
8365 else
8366 // The backedge is never taken.
8367 return getZero(CI->getType());
8368 }
8369
8370 // If we're exiting based on the overflow flag of an x.with.overflow intrinsic
8371 // with a constant step, we can form an equivalent icmp predicate and figure
8372 // out how many iterations will be taken before we exit.
8373 const WithOverflowInst *WO;
8374 const APInt *C;
8375 if (match(ExitCond, m_ExtractValue<1>(m_WithOverflowInst(WO))) &&
8376 match(WO->getRHS(), m_APInt(C))) {
8377 ConstantRange NWR =
8378 ConstantRange::makeExactNoWrapRegion(WO->getBinaryOp(), *C,
8379 WO->getNoWrapKind());
8380 CmpInst::Predicate Pred;
8381 APInt NewRHSC, Offset;
8382 NWR.getEquivalentICmp(Pred, NewRHSC, Offset);
8383 if (!ExitIfTrue)
8384 Pred = ICmpInst::getInversePredicate(Pred);
8385 auto *LHS = getSCEV(WO->getLHS());
8386 if (Offset != 0)
8387 LHS = getAddExpr(LHS, getConstant(Offset));
8388 auto EL = computeExitLimitFromICmp(L, Pred, LHS, getConstant(NewRHSC),
8389 ControlsExit, AllowPredicates);
8390 if (EL.hasAnyInfo()) return EL;
8391 }
8392
8393 // If it's not an integer or pointer comparison then compute it the hard way.
8394 return computeExitCountExhaustively(L, ExitCond, ExitIfTrue);
8395}
8396
8397Optional<ScalarEvolution::ExitLimit>
8398ScalarEvolution::computeExitLimitFromCondFromBinOp(
8399 ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, bool ExitIfTrue,
8400 bool ControlsExit, bool AllowPredicates) {
8401 // Check if the controlling expression for this loop is an And or Or.
8402 Value *Op0, *Op1;
8403 bool IsAnd = false;
8404 if (match(ExitCond, m_LogicalAnd(m_Value(Op0), m_Value(Op1))))
8405 IsAnd = true;
8406 else if (match(ExitCond, m_LogicalOr(m_Value(Op0), m_Value(Op1))))
8407 IsAnd = false;
8408 else
8409 return None;
8410
8411 // EitherMayExit is true in these two cases:
8412 // br (and Op0 Op1), loop, exit
8413 // br (or Op0 Op1), exit, loop
8414 bool EitherMayExit = IsAnd ^ ExitIfTrue;
8415 ExitLimit EL0 = computeExitLimitFromCondCached(Cache, L, Op0, ExitIfTrue,
8416 ControlsExit && !EitherMayExit,
8417 AllowPredicates);
8418 ExitLimit EL1 = computeExitLimitFromCondCached(Cache, L, Op1, ExitIfTrue,
8419 ControlsExit && !EitherMayExit,
8420 AllowPredicates);
8421
8422 // Be robust against unsimplified IR for the form "op i1 X, NeutralElement"
8423 const Constant *NeutralElement = ConstantInt::get(ExitCond->getType(), IsAnd);
8424 if (isa<ConstantInt>(Op1))
8425 return Op1 == NeutralElement ? EL0 : EL1;
8426 if (isa<ConstantInt>(Op0))
8427 return Op0 == NeutralElement ? EL1 : EL0;
8428
8429 const SCEV *BECount = getCouldNotCompute();
8430 const SCEV *MaxBECount = getCouldNotCompute();
8431 if (EitherMayExit) {
8432 // Both conditions must be same for the loop to continue executing.
8433 // Choose the less conservative count.
8434 if (EL0.ExactNotTaken != getCouldNotCompute() &&
8435 EL1.ExactNotTaken != getCouldNotCompute()) {
8436 BECount = getUMinFromMismatchedTypes(
8437 EL0.ExactNotTaken, EL1.ExactNotTaken,
8438 /*Sequential=*/!isa<BinaryOperator>(ExitCond));
8439
8440 // If EL0.ExactNotTaken was zero and ExitCond was a short-circuit form,
8441 // it should have been simplified to zero (see the condition (3) above)
8442 assert(!isa<BinaryOperator>(ExitCond) || !EL0.ExactNotTaken->isZero() ||(static_cast <bool> (!isa<BinaryOperator>(ExitCond
) || !EL0.ExactNotTaken->isZero() || BECount->isZero())
? void (0) : __assert_fail ("!isa<BinaryOperator>(ExitCond) || !EL0.ExactNotTaken->isZero() || BECount->isZero()"
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8443, __extension__
__PRETTY_FUNCTION__))
8443 BECount->isZero())(static_cast <bool> (!isa<BinaryOperator>(ExitCond
) || !EL0.ExactNotTaken->isZero() || BECount->isZero())
? void (0) : __assert_fail ("!isa<BinaryOperator>(ExitCond) || !EL0.ExactNotTaken->isZero() || BECount->isZero()"
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8443, __extension__
__PRETTY_FUNCTION__));
8444 }
8445 if (EL0.MaxNotTaken == getCouldNotCompute())
8446 MaxBECount = EL1.MaxNotTaken;
8447 else if (EL1.MaxNotTaken == getCouldNotCompute())
8448 MaxBECount = EL0.MaxNotTaken;
8449 else
8450 MaxBECount = getUMinFromMismatchedTypes(EL0.MaxNotTaken, EL1.MaxNotTaken);
8451 } else {
8452 // Both conditions must be same at the same time for the loop to exit.
8453 // For now, be conservative.
8454 if (EL0.ExactNotTaken == EL1.ExactNotTaken)
8455 BECount = EL0.ExactNotTaken;
8456 }
8457
8458 // There are cases (e.g. PR26207) where computeExitLimitFromCond is able
8459 // to be more aggressive when computing BECount than when computing
8460 // MaxBECount. In these cases it is possible for EL0.ExactNotTaken and
8461 // EL1.ExactNotTaken to match, but for EL0.MaxNotTaken and EL1.MaxNotTaken
8462 // to not.
8463 if (isa<SCEVCouldNotCompute>(MaxBECount) &&
8464 !isa<SCEVCouldNotCompute>(BECount))
8465 MaxBECount = getConstant(getUnsignedRangeMax(BECount));
8466
8467 return ExitLimit(BECount, MaxBECount, false,
8468 { &EL0.Predicates, &EL1.Predicates });
8469}
8470
8471ScalarEvolution::ExitLimit
8472ScalarEvolution::computeExitLimitFromICmp(const Loop *L,
8473 ICmpInst *ExitCond,
8474 bool ExitIfTrue,
8475 bool ControlsExit,
8476 bool AllowPredicates) {
8477 // If the condition was exit on true, convert the condition to exit on false
8478 ICmpInst::Predicate Pred;
8479 if (!ExitIfTrue)
8480 Pred = ExitCond->getPredicate();
8481 else
8482 Pred = ExitCond->getInversePredicate();
8483 const ICmpInst::Predicate OriginalPred = Pred;
8484
8485 const SCEV *LHS = getSCEV(ExitCond->getOperand(0));
8486 const SCEV *RHS = getSCEV(ExitCond->getOperand(1));
8487
8488 ExitLimit EL = computeExitLimitFromICmp(L, Pred, LHS, RHS, ControlsExit,
8489 AllowPredicates);
8490 if (EL.hasAnyInfo()) return EL;
8491
8492 auto *ExhaustiveCount =
8493 computeExitCountExhaustively(L, ExitCond, ExitIfTrue);
8494
8495 if (!isa<SCEVCouldNotCompute>(ExhaustiveCount))
8496 return ExhaustiveCount;
8497
8498 return computeShiftCompareExitLimit(ExitCond->getOperand(0),
8499 ExitCond->getOperand(1), L, OriginalPred);
8500}
8501ScalarEvolution::ExitLimit
8502ScalarEvolution::computeExitLimitFromICmp(const Loop *L,
8503 ICmpInst::Predicate Pred,
8504 const SCEV *LHS, const SCEV *RHS,
8505 bool ControlsExit,
8506 bool AllowPredicates) {
8507
8508 // Try to evaluate any dependencies out of the loop.
8509 LHS = getSCEVAtScope(LHS, L);
8510 RHS = getSCEVAtScope(RHS, L);
8511
8512 // At this point, we would like to compute how many iterations of the
8513 // loop the predicate will return true for these inputs.
8514 if (isLoopInvariant(LHS, L) && !isLoopInvariant(RHS, L)) {
8515 // If there is a loop-invariant, force it into the RHS.
8516 std::swap(LHS, RHS);
8517 Pred = ICmpInst::getSwappedPredicate(Pred);
8518 }
8519
8520 bool ControllingFiniteLoop =
8521 ControlsExit && loopHasNoAbnormalExits(L) && loopIsFiniteByAssumption(L);
8522 // Simplify the operands before analyzing them.
8523 (void)SimplifyICmpOperands(Pred, LHS, RHS, /*Depth=*/0,
8524 (EnableFiniteLoopControl ? ControllingFiniteLoop
8525 : false));
8526
8527 // If we have a comparison of a chrec against a constant, try to use value
8528 // ranges to answer this query.
8529 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS))
8530 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(LHS))
8531 if (AddRec->getLoop() == L) {
8532 // Form the constant range.
8533 ConstantRange CompRange =
8534 ConstantRange::makeExactICmpRegion(Pred, RHSC->getAPInt());
8535
8536 const SCEV *Ret = AddRec->getNumIterationsInRange(CompRange, *this);
8537 if (!isa<SCEVCouldNotCompute>(Ret)) return Ret;
8538 }
8539
8540 // If this loop must exit based on this condition (or execute undefined
8541 // behaviour), and we can prove the test sequence produced must repeat
8542 // the same values on self-wrap of the IV, then we can infer that IV
8543 // doesn't self wrap because if it did, we'd have an infinite (undefined)
8544 // loop.
8545 if (ControllingFiniteLoop && isLoopInvariant(RHS, L)) {
8546 // TODO: We can peel off any functions which are invertible *in L*. Loop
8547 // invariant terms are effectively constants for our purposes here.
8548 auto *InnerLHS = LHS;
8549 if (auto *ZExt = dyn_cast<SCEVZeroExtendExpr>(LHS))
8550 InnerLHS = ZExt->getOperand();
8551 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(InnerLHS)) {
8552 auto *StrideC = dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this));
8553 if (!AR->hasNoSelfWrap() && AR->getLoop() == L && AR->isAffine() &&
8554 StrideC && StrideC->getAPInt().isPowerOf2()) {
8555 auto Flags = AR->getNoWrapFlags();
8556 Flags = setFlags(Flags, SCEV::FlagNW);
8557 SmallVector<const SCEV*> Operands{AR->operands()};
8558 Flags = StrengthenNoWrapFlags(this, scAddRecExpr, Operands, Flags);
8559 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), Flags);
8560 }
8561 }
8562 }
8563
8564 switch (Pred) {
8565 case ICmpInst::ICMP_NE: { // while (X != Y)
8566 // Convert to: while (X-Y != 0)
8567 if (LHS->getType()->isPointerTy()) {
8568 LHS = getLosslessPtrToIntExpr(LHS);
8569 if (isa<SCEVCouldNotCompute>(LHS))
8570 return LHS;
8571 }
8572 if (RHS->getType()->isPointerTy()) {
8573 RHS = getLosslessPtrToIntExpr(RHS);
8574 if (isa<SCEVCouldNotCompute>(RHS))
8575 return RHS;
8576 }
8577 ExitLimit EL = howFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit,
8578 AllowPredicates);
8579 if (EL.hasAnyInfo()) return EL;
8580 break;
8581 }
8582 case ICmpInst::ICMP_EQ: { // while (X == Y)
8583 // Convert to: while (X-Y == 0)
8584 if (LHS->getType()->isPointerTy()) {
8585 LHS = getLosslessPtrToIntExpr(LHS);
8586 if (isa<SCEVCouldNotCompute>(LHS))
8587 return LHS;
8588 }
8589 if (RHS->getType()->isPointerTy()) {
8590 RHS = getLosslessPtrToIntExpr(RHS);
8591 if (isa<SCEVCouldNotCompute>(RHS))
8592 return RHS;
8593 }
8594 ExitLimit EL = howFarToNonZero(getMinusSCEV(LHS, RHS), L);
8595 if (EL.hasAnyInfo()) return EL;
8596 break;
8597 }
8598 case ICmpInst::ICMP_SLT:
8599 case ICmpInst::ICMP_ULT: { // while (X < Y)
8600 bool IsSigned = Pred == ICmpInst::ICMP_SLT;
8601 ExitLimit EL = howManyLessThans(LHS, RHS, L, IsSigned, ControlsExit,
8602 AllowPredicates);
8603 if (EL.hasAnyInfo()) return EL;
8604 break;
8605 }
8606 case ICmpInst::ICMP_SGT:
8607 case ICmpInst::ICMP_UGT: { // while (X > Y)
8608 bool IsSigned = Pred == ICmpInst::ICMP_SGT;
8609 ExitLimit EL =
8610 howManyGreaterThans(LHS, RHS, L, IsSigned, ControlsExit,
8611 AllowPredicates);
8612 if (EL.hasAnyInfo()) return EL;
8613 break;
8614 }
8615 default:
8616 break;
8617 }
8618
8619 return getCouldNotCompute();
8620}
8621
8622ScalarEvolution::ExitLimit
8623ScalarEvolution::computeExitLimitFromSingleExitSwitch(const Loop *L,
8624 SwitchInst *Switch,
8625 BasicBlock *ExitingBlock,
8626 bool ControlsExit) {
8627 assert(!L->contains(ExitingBlock) && "Not an exiting block!")(static_cast <bool> (!L->contains(ExitingBlock) &&
"Not an exiting block!") ? void (0) : __assert_fail ("!L->contains(ExitingBlock) && \"Not an exiting block!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8627, __extension__
__PRETTY_FUNCTION__));
8628
8629 // Give up if the exit is the default dest of a switch.
8630 if (Switch->getDefaultDest() == ExitingBlock)
8631 return getCouldNotCompute();
8632
8633 assert(L->contains(Switch->getDefaultDest()) &&(static_cast <bool> (L->contains(Switch->getDefaultDest
()) && "Default case must not exit the loop!") ? void
(0) : __assert_fail ("L->contains(Switch->getDefaultDest()) && \"Default case must not exit the loop!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8634, __extension__
__PRETTY_FUNCTION__))
8634 "Default case must not exit the loop!")(static_cast <bool> (L->contains(Switch->getDefaultDest
()) && "Default case must not exit the loop!") ? void
(0) : __assert_fail ("L->contains(Switch->getDefaultDest()) && \"Default case must not exit the loop!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8634, __extension__
__PRETTY_FUNCTION__));
8635 const SCEV *LHS = getSCEVAtScope(Switch->getCondition(), L);
8636 const SCEV *RHS = getConstant(Switch->findCaseDest(ExitingBlock));
8637
8638 // while (X != Y) --> while (X-Y != 0)
8639 ExitLimit EL = howFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit);
8640 if (EL.hasAnyInfo())
8641 return EL;
8642
8643 return getCouldNotCompute();
8644}
8645
8646static ConstantInt *
8647EvaluateConstantChrecAtConstant(const SCEVAddRecExpr *AddRec, ConstantInt *C,
8648 ScalarEvolution &SE) {
8649 const SCEV *InVal = SE.getConstant(C);
8650 const SCEV *Val = AddRec->evaluateAtIteration(InVal, SE);
8651 assert(isa<SCEVConstant>(Val) &&(static_cast <bool> (isa<SCEVConstant>(Val) &&
"Evaluation of SCEV at constant didn't fold correctly?") ? void
(0) : __assert_fail ("isa<SCEVConstant>(Val) && \"Evaluation of SCEV at constant didn't fold correctly?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8652, __extension__
__PRETTY_FUNCTION__))
8652 "Evaluation of SCEV at constant didn't fold correctly?")(static_cast <bool> (isa<SCEVConstant>(Val) &&
"Evaluation of SCEV at constant didn't fold correctly?") ? void
(0) : __assert_fail ("isa<SCEVConstant>(Val) && \"Evaluation of SCEV at constant didn't fold correctly?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8652, __extension__
__PRETTY_FUNCTION__));
8653 return cast<SCEVConstant>(Val)->getValue();
8654}
8655
8656ScalarEvolution::ExitLimit ScalarEvolution::computeShiftCompareExitLimit(
8657 Value *LHS, Value *RHSV, const Loop *L, ICmpInst::Predicate Pred) {
8658 ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV);
8659 if (!RHS)
8660 return getCouldNotCompute();
8661
8662 const BasicBlock *Latch = L->getLoopLatch();
8663 if (!Latch)
8664 return getCouldNotCompute();
8665
8666 const BasicBlock *Predecessor = L->getLoopPredecessor();
8667 if (!Predecessor)
8668 return getCouldNotCompute();
8669
8670 // Return true if V is of the form "LHS `shift_op` <positive constant>".
8671 // Return LHS in OutLHS and shift_opt in OutOpCode.
8672 auto MatchPositiveShift =
8673 [](Value *V, Value *&OutLHS, Instruction::BinaryOps &OutOpCode) {
8674
8675 using namespace PatternMatch;
8676
8677 ConstantInt *ShiftAmt;
8678 if (match(V, m_LShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
8679 OutOpCode = Instruction::LShr;
8680 else if (match(V, m_AShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
8681 OutOpCode = Instruction::AShr;
8682 else if (match(V, m_Shl(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
8683 OutOpCode = Instruction::Shl;
8684 else
8685 return false;
8686
8687 return ShiftAmt->getValue().isStrictlyPositive();
8688 };
8689
8690 // Recognize a "shift recurrence" either of the form %iv or of %iv.shifted in
8691 //
8692 // loop:
8693 // %iv = phi i32 [ %iv.shifted, %loop ], [ %val, %preheader ]
8694 // %iv.shifted = lshr i32 %iv, <positive constant>
8695 //
8696 // Return true on a successful match. Return the corresponding PHI node (%iv
8697 // above) in PNOut and the opcode of the shift operation in OpCodeOut.
8698 auto MatchShiftRecurrence =
8699 [&](Value *V, PHINode *&PNOut, Instruction::BinaryOps &OpCodeOut) {
8700 Optional<Instruction::BinaryOps> PostShiftOpCode;
8701
8702 {
8703 Instruction::BinaryOps OpC;
8704 Value *V;
8705
8706 // If we encounter a shift instruction, "peel off" the shift operation,
8707 // and remember that we did so. Later when we inspect %iv's backedge
8708 // value, we will make sure that the backedge value uses the same
8709 // operation.
8710 //
8711 // Note: the peeled shift operation does not have to be the same
8712 // instruction as the one feeding into the PHI's backedge value. We only
8713 // really care about it being the same *kind* of shift instruction --
8714 // that's all that is required for our later inferences to hold.
8715 if (MatchPositiveShift(LHS, V, OpC)) {
8716 PostShiftOpCode = OpC;
8717 LHS = V;
8718 }
8719 }
8720
8721 PNOut = dyn_cast<PHINode>(LHS);
8722 if (!PNOut || PNOut->getParent() != L->getHeader())
8723 return false;
8724
8725 Value *BEValue = PNOut->getIncomingValueForBlock(Latch);
8726 Value *OpLHS;
8727
8728 return
8729 // The backedge value for the PHI node must be a shift by a positive
8730 // amount
8731 MatchPositiveShift(BEValue, OpLHS, OpCodeOut) &&
8732
8733 // of the PHI node itself
8734 OpLHS == PNOut &&
8735
8736 // and the kind of shift should be match the kind of shift we peeled
8737 // off, if any.
8738 (!PostShiftOpCode.hasValue() || *PostShiftOpCode == OpCodeOut);
8739 };
8740
8741 PHINode *PN;
8742 Instruction::BinaryOps OpCode;
8743 if (!MatchShiftRecurrence(LHS, PN, OpCode))
8744 return getCouldNotCompute();
8745
8746 const DataLayout &DL = getDataLayout();
8747
8748 // The key rationale for this optimization is that for some kinds of shift
8749 // recurrences, the value of the recurrence "stabilizes" to either 0 or -1
8750 // within a finite number of iterations. If the condition guarding the
8751 // backedge (in the sense that the backedge is taken if the condition is true)
8752 // is false for the value the shift recurrence stabilizes to, then we know
8753 // that the backedge is taken only a finite number of times.
8754
8755 ConstantInt *StableValue = nullptr;
8756 switch (OpCode) {
8757 default:
8758 llvm_unreachable("Impossible case!")::llvm::llvm_unreachable_internal("Impossible case!", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 8758);
8759
8760 case Instruction::AShr: {
8761 // {K,ashr,<positive-constant>} stabilizes to signum(K) in at most
8762 // bitwidth(K) iterations.
8763 Value *FirstValue = PN->getIncomingValueForBlock(Predecessor);
8764 KnownBits Known = computeKnownBits(FirstValue, DL, 0, &AC,
8765 Predecessor->getTerminator(), &DT);
8766 auto *Ty = cast<IntegerType>(RHS->getType());
8767 if (Known.isNonNegative())
8768 StableValue = ConstantInt::get(Ty, 0);
8769 else if (Known.isNegative())
8770 StableValue = ConstantInt::get(Ty, -1, true);
8771 else
8772 return getCouldNotCompute();
8773
8774 break;
8775 }
8776 case Instruction::LShr:
8777 case Instruction::Shl:
8778 // Both {K,lshr,<positive-constant>} and {K,shl,<positive-constant>}
8779 // stabilize to 0 in at most bitwidth(K) iterations.
8780 StableValue = ConstantInt::get(cast<IntegerType>(RHS->getType()), 0);
8781 break;
8782 }
8783
8784 auto *Result =
8785 ConstantFoldCompareInstOperands(Pred, StableValue, RHS, DL, &TLI);
8786 assert(Result->getType()->isIntegerTy(1) &&(static_cast <bool> (Result->getType()->isIntegerTy
(1) && "Otherwise cannot be an operand to a branch instruction"
) ? void (0) : __assert_fail ("Result->getType()->isIntegerTy(1) && \"Otherwise cannot be an operand to a branch instruction\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8787, __extension__
__PRETTY_FUNCTION__))
8787 "Otherwise cannot be an operand to a branch instruction")(static_cast <bool> (Result->getType()->isIntegerTy
(1) && "Otherwise cannot be an operand to a branch instruction"
) ? void (0) : __assert_fail ("Result->getType()->isIntegerTy(1) && \"Otherwise cannot be an operand to a branch instruction\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8787, __extension__
__PRETTY_FUNCTION__));
8788
8789 if (Result->isZeroValue()) {
8790 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
8791 const SCEV *UpperBound =
8792 getConstant(getEffectiveSCEVType(RHS->getType()), BitWidth);
8793 return ExitLimit(getCouldNotCompute(), UpperBound, false);
8794 }
8795
8796 return getCouldNotCompute();
8797}
8798
8799/// Return true if we can constant fold an instruction of the specified type,
8800/// assuming that all operands were constants.
8801static bool CanConstantFold(const Instruction *I) {
8802 if (isa<BinaryOperator>(I) || isa<CmpInst>(I) ||
8803 isa<SelectInst>(I) || isa<CastInst>(I) || isa<GetElementPtrInst>(I) ||
8804 isa<LoadInst>(I) || isa<ExtractValueInst>(I))
8805 return true;
8806
8807 if (const CallInst *CI = dyn_cast<CallInst>(I))
8808 if (const Function *F = CI->getCalledFunction())
8809 return canConstantFoldCallTo(CI, F);
8810 return false;
8811}
8812
8813/// Determine whether this instruction can constant evolve within this loop
8814/// assuming its operands can all constant evolve.
8815static bool canConstantEvolve(Instruction *I, const Loop *L) {
8816 // An instruction outside of the loop can't be derived from a loop PHI.
8817 if (!L->contains(I)) return false;
8818
8819 if (isa<PHINode>(I)) {
8820 // We don't currently keep track of the control flow needed to evaluate
8821 // PHIs, so we cannot handle PHIs inside of loops.
8822 return L->getHeader() == I->getParent();
8823 }
8824
8825 // If we won't be able to constant fold this expression even if the operands
8826 // are constants, bail early.
8827 return CanConstantFold(I);
8828}
8829
8830/// getConstantEvolvingPHIOperands - Implement getConstantEvolvingPHI by
8831/// recursing through each instruction operand until reaching a loop header phi.
8832static PHINode *
8833getConstantEvolvingPHIOperands(Instruction *UseInst, const Loop *L,
8834 DenseMap<Instruction *, PHINode *> &PHIMap,
8835 unsigned Depth) {
8836 if (Depth > MaxConstantEvolvingDepth)
8837 return nullptr;
8838
8839 // Otherwise, we can evaluate this instruction if all of its operands are
8840 // constant or derived from a PHI node themselves.
8841 PHINode *PHI = nullptr;
8842 for (Value *Op : UseInst->operands()) {
8843 if (isa<Constant>(Op)) continue;
8844
8845 Instruction *OpInst = dyn_cast<Instruction>(Op);
8846 if (!OpInst || !canConstantEvolve(OpInst, L)) return nullptr;
8847
8848 PHINode *P = dyn_cast<PHINode>(OpInst);
8849 if (!P)
8850 // If this operand is already visited, reuse the prior result.
8851 // We may have P != PHI if this is the deepest point at which the
8852 // inconsistent paths meet.
8853 P = PHIMap.lookup(OpInst);
8854 if (!P) {
8855 // Recurse and memoize the results, whether a phi is found or not.
8856 // This recursive call invalidates pointers into PHIMap.
8857 P = getConstantEvolvingPHIOperands(OpInst, L, PHIMap, Depth + 1);
8858 PHIMap[OpInst] = P;
8859 }
8860 if (!P)
8861 return nullptr; // Not evolving from PHI
8862 if (PHI && PHI != P)
8863 return nullptr; // Evolving from multiple different PHIs.
8864 PHI = P;
8865 }
8866 // This is a expression evolving from a constant PHI!
8867 return PHI;
8868}
8869
8870/// getConstantEvolvingPHI - Given an LLVM value and a loop, return a PHI node
8871/// in the loop that V is derived from. We allow arbitrary operations along the
8872/// way, but the operands of an operation must either be constants or a value
8873/// derived from a constant PHI. If this expression does not fit with these
8874/// constraints, return null.
8875static PHINode *getConstantEvolvingPHI(Value *V, const Loop *L) {
8876 Instruction *I = dyn_cast<Instruction>(V);
8877 if (!I || !canConstantEvolve(I, L)) return nullptr;
8878
8879 if (PHINode *PN = dyn_cast<PHINode>(I))
8880 return PN;
8881
8882 // Record non-constant instructions contained by the loop.
8883 DenseMap<Instruction *, PHINode *> PHIMap;
8884 return getConstantEvolvingPHIOperands(I, L, PHIMap, 0);
8885}
8886
8887/// EvaluateExpression - Given an expression that passes the
8888/// getConstantEvolvingPHI predicate, evaluate its value assuming the PHI node
8889/// in the loop has the value PHIVal. If we can't fold this expression for some
8890/// reason, return null.
8891static Constant *EvaluateExpression(Value *V, const Loop *L,
8892 DenseMap<Instruction *, Constant *> &Vals,
8893 const DataLayout &DL,
8894 const TargetLibraryInfo *TLI) {
8895 // Convenient constant check, but redundant for recursive calls.
8896 if (Constant *C = dyn_cast<Constant>(V)) return C;
8897 Instruction *I = dyn_cast<Instruction>(V);
8898 if (!I) return nullptr;
8899
8900 if (Constant *C = Vals.lookup(I)) return C;
8901
8902 // An instruction inside the loop depends on a value outside the loop that we
8903 // weren't given a mapping for, or a value such as a call inside the loop.
8904 if (!canConstantEvolve(I, L)) return nullptr;
8905
8906 // An unmapped PHI can be due to a branch or another loop inside this loop,
8907 // or due to this not being the initial iteration through a loop where we
8908 // couldn't compute the evolution of this particular PHI last time.
8909 if (isa<PHINode>(I)) return nullptr;
8910
8911 std::vector<Constant*> Operands(I->getNumOperands());
8912
8913 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
8914 Instruction *Operand = dyn_cast<Instruction>(I->getOperand(i));
8915 if (!Operand) {
8916 Operands[i] = dyn_cast<Constant>(I->getOperand(i));
8917 if (!Operands[i]) return nullptr;
8918 continue;
8919 }
8920 Constant *C = EvaluateExpression(Operand, L, Vals, DL, TLI);
8921 Vals[Operand] = C;
8922 if (!C) return nullptr;
8923 Operands[i] = C;
8924 }
8925
8926 if (CmpInst *CI = dyn_cast<CmpInst>(I))
8927 return ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0],
8928 Operands[1], DL, TLI);
8929 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
8930 if (!LI->isVolatile())
8931 return ConstantFoldLoadFromConstPtr(Operands[0], LI->getType(), DL);
8932 }
8933 return ConstantFoldInstOperands(I, Operands, DL, TLI);
8934}
8935
8936
8937// If every incoming value to PN except the one for BB is a specific Constant,
8938// return that, else return nullptr.
8939static Constant *getOtherIncomingValue(PHINode *PN, BasicBlock *BB) {
8940 Constant *IncomingVal = nullptr;
8941
8942 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
8943 if (PN->getIncomingBlock(i) == BB)
8944 continue;
8945
8946 auto *CurrentVal = dyn_cast<Constant>(PN->getIncomingValue(i));
8947 if (!CurrentVal)
8948 return nullptr;
8949
8950 if (IncomingVal != CurrentVal) {
8951 if (IncomingVal)
8952 return nullptr;
8953 IncomingVal = CurrentVal;
8954 }
8955 }
8956
8957 return IncomingVal;
8958}
8959
8960/// getConstantEvolutionLoopExitValue - If we know that the specified Phi is
8961/// in the header of its containing loop, we know the loop executes a
8962/// constant number of times, and the PHI node is just a recurrence
8963/// involving constants, fold it.
8964Constant *
8965ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN,
8966 const APInt &BEs,
8967 const Loop *L) {
8968 auto I = ConstantEvolutionLoopExitValue.find(PN);
8969 if (I != ConstantEvolutionLoopExitValue.end())
8970 return I->second;
8971
8972 if (BEs.ugt(MaxBruteForceIterations))
8973 return ConstantEvolutionLoopExitValue[PN] = nullptr; // Not going to evaluate it.
8974
8975 Constant *&RetVal = ConstantEvolutionLoopExitValue[PN];
8976
8977 DenseMap<Instruction *, Constant *> CurrentIterVals;
8978 BasicBlock *Header = L->getHeader();
8979 assert(PN->getParent() == Header && "Can't evaluate PHI not in loop header!")(static_cast <bool> (PN->getParent() == Header &&
"Can't evaluate PHI not in loop header!") ? void (0) : __assert_fail
("PN->getParent() == Header && \"Can't evaluate PHI not in loop header!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8979, __extension__
__PRETTY_FUNCTION__));
8980
8981 BasicBlock *Latch = L->getLoopLatch();
8982 if (!Latch)
8983 return nullptr;
8984
8985 for (PHINode &PHI : Header->phis()) {
8986 if (auto *StartCST = getOtherIncomingValue(&PHI, Latch))
8987 CurrentIterVals[&PHI] = StartCST;
8988 }
8989 if (!CurrentIterVals.count(PN))
8990 return RetVal = nullptr;
8991
8992 Value *BEValue = PN->getIncomingValueForBlock(Latch);
8993
8994 // Execute the loop symbolically to determine the exit value.
8995 assert(BEs.getActiveBits() < CHAR_BIT * sizeof(unsigned) &&(static_cast <bool> (BEs.getActiveBits() < 8 * sizeof
(unsigned) && "BEs is <= MaxBruteForceIterations which is an 'unsigned'!"
) ? void (0) : __assert_fail ("BEs.getActiveBits() < CHAR_BIT * sizeof(unsigned) && \"BEs is <= MaxBruteForceIterations which is an 'unsigned'!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8996, __extension__
__PRETTY_FUNCTION__))
8996 "BEs is <= MaxBruteForceIterations which is an 'unsigned'!")(static_cast <bool> (BEs.getActiveBits() < 8 * sizeof
(unsigned) && "BEs is <= MaxBruteForceIterations which is an 'unsigned'!"
) ? void (0) : __assert_fail ("BEs.getActiveBits() < CHAR_BIT * sizeof(unsigned) && \"BEs is <= MaxBruteForceIterations which is an 'unsigned'!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 8996, __extension__
__PRETTY_FUNCTION__));
8997
8998 unsigned NumIterations = BEs.getZExtValue(); // must be in range
8999 unsigned IterationNum = 0;
9000 const DataLayout &DL = getDataLayout();
9001 for (; ; ++IterationNum) {
9002 if (IterationNum == NumIterations)
9003 return RetVal = CurrentIterVals[PN]; // Got exit value!
9004
9005 // Compute the value of the PHIs for the next iteration.
9006 // EvaluateExpression adds non-phi values to the CurrentIterVals map.
9007 DenseMap<Instruction *, Constant *> NextIterVals;
9008 Constant *NextPHI =
9009 EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
9010 if (!NextPHI)
9011 return nullptr; // Couldn't evaluate!
9012 NextIterVals[PN] = NextPHI;
9013
9014 bool StoppedEvolving = NextPHI == CurrentIterVals[PN];
9015
9016 // Also evaluate the other PHI nodes. However, we don't get to stop if we
9017 // cease to be able to evaluate one of them or if they stop evolving,
9018 // because that doesn't necessarily prevent us from computing PN.
9019 SmallVector<std::pair<PHINode *, Constant *>, 8> PHIsToCompute;
9020 for (const auto &I : CurrentIterVals) {
9021 PHINode *PHI = dyn_cast<PHINode>(I.first);
9022 if (!PHI || PHI == PN || PHI->getParent() != Header) continue;
9023 PHIsToCompute.emplace_back(PHI, I.second);
9024 }
9025 // We use two distinct loops because EvaluateExpression may invalidate any
9026 // iterators into CurrentIterVals.
9027 for (const auto &I : PHIsToCompute) {
9028 PHINode *PHI = I.first;
9029 Constant *&NextPHI = NextIterVals[PHI];
9030 if (!NextPHI) { // Not already computed.
9031 Value *BEValue = PHI->getIncomingValueForBlock(Latch);
9032 NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
9033 }
9034 if (NextPHI != I.second)
9035 StoppedEvolving = false;
9036 }
9037
9038 // If all entries in CurrentIterVals == NextIterVals then we can stop
9039 // iterating, the loop can't continue to change.
9040 if (StoppedEvolving)
9041 return RetVal = CurrentIterVals[PN];
9042
9043 CurrentIterVals.swap(NextIterVals);
9044 }
9045}
9046
9047const SCEV *ScalarEvolution::computeExitCountExhaustively(const Loop *L,
9048 Value *Cond,
9049 bool ExitWhen) {
9050 PHINode *PN = getConstantEvolvingPHI(Cond, L);
9051 if (!PN) return getCouldNotCompute();
9052
9053 // If the loop is canonicalized, the PHI will have exactly two entries.
9054 // That's the only form we support here.
9055 if (PN->getNumIncomingValues() != 2) return getCouldNotCompute();
9056
9057 DenseMap<Instruction *, Constant *> CurrentIterVals;
9058 BasicBlock *Header = L->getHeader();
9059 assert(PN->getParent() == Header && "Can't evaluate PHI not in loop header!")(static_cast <bool> (PN->getParent() == Header &&
"Can't evaluate PHI not in loop header!") ? void (0) : __assert_fail
("PN->getParent() == Header && \"Can't evaluate PHI not in loop header!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 9059, __extension__
__PRETTY_FUNCTION__));
9060
9061 BasicBlock *Latch = L->getLoopLatch();
9062 assert(Latch && "Should follow from NumIncomingValues == 2!")(static_cast <bool> (Latch && "Should follow from NumIncomingValues == 2!"
) ? void (0) : __assert_fail ("Latch && \"Should follow from NumIncomingValues == 2!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 9062, __extension__
__PRETTY_FUNCTION__));
9063
9064 for (PHINode &PHI : Header->phis()) {
9065 if (auto *StartCST = getOtherIncomingValue(&PHI, Latch))
9066 CurrentIterVals[&PHI] = StartCST;
9067 }
9068 if (!CurrentIterVals.count(PN))
9069 return getCouldNotCompute();
9070
9071 // Okay, we find a PHI node that defines the trip count of this loop. Execute
9072 // the loop symbolically to determine when the condition gets a value of
9073 // "ExitWhen".
9074 unsigned MaxIterations = MaxBruteForceIterations; // Limit analysis.
9075 const DataLayout &DL = getDataLayout();
9076 for (unsigned IterationNum = 0; IterationNum != MaxIterations;++IterationNum){
9077 auto *CondVal = dyn_cast_or_null<ConstantInt>(
9078 EvaluateExpression(Cond, L, CurrentIterVals, DL, &TLI));
9079
9080 // Couldn't symbolically evaluate.
9081 if (!CondVal) return getCouldNotCompute();
9082
9083 if (CondVal->getValue() == uint64_t(ExitWhen)) {
9084 ++NumBruteForceTripCountsComputed;
9085 return getConstant(Type::getInt32Ty(getContext()), IterationNum);
9086 }
9087
9088 // Update all the PHI nodes for the next iteration.
9089 DenseMap<Instruction *, Constant *> NextIterVals;
9090
9091 // Create a list of which PHIs we need to compute. We want to do this before
9092 // calling EvaluateExpression on them because that may invalidate iterators
9093 // into CurrentIterVals.
9094 SmallVector<PHINode *, 8> PHIsToCompute;
9095 for (const auto &I : CurrentIterVals) {
9096 PHINode *PHI = dyn_cast<PHINode>(I.first);
9097 if (!PHI || PHI->getParent() != Header) continue;
9098 PHIsToCompute.push_back(PHI);
9099 }
9100 for (PHINode *PHI : PHIsToCompute) {
9101 Constant *&NextPHI = NextIterVals[PHI];
9102 if (NextPHI) continue; // Already computed!
9103
9104 Value *BEValue = PHI->getIncomingValueForBlock(Latch);
9105 NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
9106 }
9107 CurrentIterVals.swap(NextIterVals);
9108 }
9109
9110 // Too many iterations were needed to evaluate.
9111 return getCouldNotCompute();
9112}
9113
9114const SCEV *ScalarEvolution::getSCEVAtScope(const SCEV *V, const Loop *L) {
9115 SmallVector<std::pair<const Loop *, const SCEV *>, 2> &Values =
9116 ValuesAtScopes[V];
9117 // Check to see if we've folded this expression at this loop before.
9118 for (auto &LS : Values)
9119 if (LS.first == L)
9120 return LS.second ? LS.second : V;
9121
9122 Values.emplace_back(L, nullptr);
9123
9124 // Otherwise compute it.
9125 const SCEV *C = computeSCEVAtScope(V, L);
9126 for (auto &LS : reverse(ValuesAtScopes[V]))
9127 if (LS.first == L) {
9128 LS.second = C;
9129 if (!isa<SCEVConstant>(C))
9130 ValuesAtScopesUsers[C].push_back({L, V});
9131 break;
9132 }
9133 return C;
9134}
9135
9136/// This builds up a Constant using the ConstantExpr interface. That way, we
9137/// will return Constants for objects which aren't represented by a
9138/// SCEVConstant, because SCEVConstant is restricted to ConstantInt.
9139/// Returns NULL if the SCEV isn't representable as a Constant.
9140static Constant *BuildConstantFromSCEV(const SCEV *V) {
9141 switch (V->getSCEVType()) {
9142 case scCouldNotCompute:
9143 case scAddRecExpr:
9144 return nullptr;
9145 case scConstant:
9146 return cast<SCEVConstant>(V)->getValue();
9147 case scUnknown:
9148 return dyn_cast<Constant>(cast<SCEVUnknown>(V)->getValue());
9149 case scSignExtend: {
9150 const SCEVSignExtendExpr *SS = cast<SCEVSignExtendExpr>(V);
9151 if (Constant *CastOp = BuildConstantFromSCEV(SS->getOperand()))
9152 return ConstantExpr::getSExt(CastOp, SS->getType());
9153 return nullptr;
9154 }
9155 case scZeroExtend: {
9156 const SCEVZeroExtendExpr *SZ = cast<SCEVZeroExtendExpr>(V);
9157 if (Constant *CastOp = BuildConstantFromSCEV(SZ->getOperand()))
9158 return ConstantExpr::getZExt(CastOp, SZ->getType());
9159 return nullptr;
9160 }
9161 case scPtrToInt: {
9162 const SCEVPtrToIntExpr *P2I = cast<SCEVPtrToIntExpr>(V);
9163 if (Constant *CastOp = BuildConstantFromSCEV(P2I->getOperand()))
9164 return ConstantExpr::getPtrToInt(CastOp, P2I->getType());
9165
9166 return nullptr;
9167 }
9168 case scTruncate: {
9169 const SCEVTruncateExpr *ST = cast<SCEVTruncateExpr>(V);
9170 if (Constant *CastOp = BuildConstantFromSCEV(ST->getOperand()))
9171 return ConstantExpr::getTrunc(CastOp, ST->getType());
9172 return nullptr;
9173 }
9174 case scAddExpr: {
9175 const SCEVAddExpr *SA = cast<SCEVAddExpr>(V);
9176 if (Constant *C = BuildConstantFromSCEV(SA->getOperand(0))) {
9177 if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) {
9178 unsigned AS = PTy->getAddressSpace();
9179 Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS);
9180 C = ConstantExpr::getBitCast(C, DestPtrTy);
9181 }
9182 for (unsigned i = 1, e = SA->getNumOperands(); i != e; ++i) {
9183 Constant *C2 = BuildConstantFromSCEV(SA->getOperand(i));
9184 if (!C2)
9185 return nullptr;
9186
9187 // First pointer!
9188 if (!C->getType()->isPointerTy() && C2->getType()->isPointerTy()) {
9189 unsigned AS = C2->getType()->getPointerAddressSpace();
9190 std::swap(C, C2);
9191 Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS);
9192 // The offsets have been converted to bytes. We can add bytes to an
9193 // i8* by GEP with the byte count in the first index.
9194 C = ConstantExpr::getBitCast(C, DestPtrTy);
9195 }
9196
9197 // Don't bother trying to sum two pointers. We probably can't
9198 // statically compute a load that results from it anyway.
9199 if (C2->getType()->isPointerTy())
9200 return nullptr;
9201
9202 if (C->getType()->isPointerTy()) {
9203 C = ConstantExpr::getGetElementPtr(Type::getInt8Ty(C->getContext()),
9204 C, C2);
9205 } else {
9206 C = ConstantExpr::getAdd(C, C2);
9207 }
9208 }
9209 return C;
9210 }
9211 return nullptr;
9212 }
9213 case scMulExpr: {
9214 const SCEVMulExpr *SM = cast<SCEVMulExpr>(V);
9215 if (Constant *C = BuildConstantFromSCEV(SM->getOperand(0))) {
9216 // Don't bother with pointers at all.
9217 if (C->getType()->isPointerTy())
9218 return nullptr;
9219 for (unsigned i = 1, e = SM->getNumOperands(); i != e; ++i) {
9220 Constant *C2 = BuildConstantFromSCEV(SM->getOperand(i));
9221 if (!C2 || C2->getType()->isPointerTy())
9222 return nullptr;
9223 C = ConstantExpr::getMul(C, C2);
9224 }
9225 return C;
9226 }
9227 return nullptr;
9228 }
9229 case scUDivExpr: {
9230 const SCEVUDivExpr *SU = cast<SCEVUDivExpr>(V);
9231 if (Constant *LHS = BuildConstantFromSCEV(SU->getLHS()))
9232 if (Constant *RHS = BuildConstantFromSCEV(SU->getRHS()))
9233 if (LHS->getType() == RHS->getType())
9234 return ConstantExpr::getUDiv(LHS, RHS);
9235 return nullptr;
9236 }
9237 case scSMaxExpr:
9238 case scUMaxExpr:
9239 case scSMinExpr:
9240 case scUMinExpr:
9241 case scSequentialUMinExpr:
9242 return nullptr; // TODO: smax, umax, smin, umax, umin_seq.
9243 }
9244 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 9244);
9245}
9246
9247const SCEV *ScalarEvolution::computeSCEVAtScope(const SCEV *V, const Loop *L) {
9248 if (isa<SCEVConstant>(V)) return V;
9249
9250 // If this instruction is evolved from a constant-evolving PHI, compute the
9251 // exit value from the loop without using SCEVs.
9252 if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(V)) {
9253 if (Instruction *I = dyn_cast<Instruction>(SU->getValue())) {
9254 if (PHINode *PN = dyn_cast<PHINode>(I)) {
9255 const Loop *CurrLoop = this->LI[I->getParent()];
9256 // Looking for loop exit value.
9257 if (CurrLoop && CurrLoop->getParentLoop() == L &&
9258 PN->getParent() == CurrLoop->getHeader()) {
9259 // Okay, there is no closed form solution for the PHI node. Check
9260 // to see if the loop that contains it has a known backedge-taken
9261 // count. If so, we may be able to force computation of the exit
9262 // value.
9263 const SCEV *BackedgeTakenCount = getBackedgeTakenCount(CurrLoop);
9264 // This trivial case can show up in some degenerate cases where
9265 // the incoming IR has not yet been fully simplified.
9266 if (BackedgeTakenCount->isZero()) {
9267 Value *InitValue = nullptr;
9268 bool MultipleInitValues = false;
9269 for (unsigned i = 0; i < PN->getNumIncomingValues(); i++) {
9270 if (!CurrLoop->contains(PN->getIncomingBlock(i))) {
9271 if (!InitValue)
9272 InitValue = PN->getIncomingValue(i);
9273 else if (InitValue != PN->getIncomingValue(i)) {
9274 MultipleInitValues = true;
9275 break;
9276 }
9277 }
9278 }
9279 if (!MultipleInitValues && InitValue)
9280 return getSCEV(InitValue);
9281 }
9282 // Do we have a loop invariant value flowing around the backedge
9283 // for a loop which must execute the backedge?
9284 if (!isa<SCEVCouldNotCompute>(BackedgeTakenCount) &&
9285 isKnownPositive(BackedgeTakenCount) &&
9286 PN->getNumIncomingValues() == 2) {
9287
9288 unsigned InLoopPred =
9289 CurrLoop->contains(PN->getIncomingBlock(0)) ? 0 : 1;
9290 Value *BackedgeVal = PN->getIncomingValue(InLoopPred);
9291 if (CurrLoop->isLoopInvariant(BackedgeVal))
9292 return getSCEV(BackedgeVal);
9293 }
9294 if (auto *BTCC = dyn_cast<SCEVConstant>(BackedgeTakenCount)) {
9295 // Okay, we know how many times the containing loop executes. If
9296 // this is a constant evolving PHI node, get the final value at
9297 // the specified iteration number.
9298 Constant *RV = getConstantEvolutionLoopExitValue(
9299 PN, BTCC->getAPInt(), CurrLoop);
9300 if (RV) return getSCEV(RV);
9301 }
9302 }
9303
9304 // If there is a single-input Phi, evaluate it at our scope. If we can
9305 // prove that this replacement does not break LCSSA form, use new value.
9306 if (PN->getNumOperands() == 1) {
9307 const SCEV *Input = getSCEV(PN->getOperand(0));
9308 const SCEV *InputAtScope = getSCEVAtScope(Input, L);
9309 // TODO: We can generalize it using LI.replacementPreservesLCSSAForm,
9310 // for the simplest case just support constants.
9311 if (isa<SCEVConstant>(InputAtScope)) return InputAtScope;
9312 }
9313 }
9314
9315 // Okay, this is an expression that we cannot symbolically evaluate
9316 // into a SCEV. Check to see if it's possible to symbolically evaluate
9317 // the arguments into constants, and if so, try to constant propagate the
9318 // result. This is particularly useful for computing loop exit values.
9319 if (CanConstantFold(I)) {
9320 SmallVector<Constant *, 4> Operands;
9321 bool MadeImprovement = false;
9322 for (Value *Op : I->operands()) {
9323 if (Constant *C = dyn_cast<Constant>(Op)) {
9324 Operands.push_back(C);
9325 continue;
9326 }
9327
9328 // If any of the operands is non-constant and if they are
9329 // non-integer and non-pointer, don't even try to analyze them
9330 // with scev techniques.
9331 if (!isSCEVable(Op->getType()))
9332 return V;
9333
9334 const SCEV *OrigV = getSCEV(Op);
9335 const SCEV *OpV = getSCEVAtScope(OrigV, L);
9336 MadeImprovement |= OrigV != OpV;
9337
9338 Constant *C = BuildConstantFromSCEV(OpV);
9339 if (!C) return V;
9340 if (C->getType() != Op->getType())
9341 C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
9342 Op->getType(),
9343 false),
9344 C, Op->getType());
9345 Operands.push_back(C);
9346 }
9347
9348 // Check to see if getSCEVAtScope actually made an improvement.
9349 if (MadeImprovement) {
9350 Constant *C = nullptr;
9351 const DataLayout &DL = getDataLayout();
9352 if (const CmpInst *CI = dyn_cast<CmpInst>(I))
9353 C = ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0],
9354 Operands[1], DL, &TLI);
9355 else if (const LoadInst *Load = dyn_cast<LoadInst>(I)) {
9356 if (!Load->isVolatile())
9357 C = ConstantFoldLoadFromConstPtr(Operands[0], Load->getType(),
9358 DL);
9359 } else
9360 C = ConstantFoldInstOperands(I, Operands, DL, &TLI);
9361 if (!C) return V;
9362 return getSCEV(C);
9363 }
9364 }
9365 }
9366
9367 // This is some other type of SCEVUnknown, just return it.
9368 return V;
9369 }
9370
9371 if (isa<SCEVCommutativeExpr>(V) || isa<SCEVSequentialMinMaxExpr>(V)) {
9372 const auto *Comm = cast<SCEVNAryExpr>(V);
9373 // Avoid performing the look-up in the common case where the specified
9374 // expression has no loop-variant portions.
9375 for (unsigned i = 0, e = Comm->getNumOperands(); i != e; ++i) {
9376 const SCEV *OpAtScope = getSCEVAtScope(Comm->getOperand(i), L);
9377 if (OpAtScope != Comm->getOperand(i)) {
9378 // Okay, at least one of these operands is loop variant but might be
9379 // foldable. Build a new instance of the folded commutative expression.
9380 SmallVector<const SCEV *, 8> NewOps(Comm->op_begin(),
9381 Comm->op_begin()+i);
9382 NewOps.push_back(OpAtScope);
9383
9384 for (++i; i != e; ++i) {
9385 OpAtScope = getSCEVAtScope(Comm->getOperand(i), L);
9386 NewOps.push_back(OpAtScope);
9387 }
9388 if (isa<SCEVAddExpr>(Comm))
9389 return getAddExpr(NewOps, Comm->getNoWrapFlags());
9390 if (isa<SCEVMulExpr>(Comm))
9391 return getMulExpr(NewOps, Comm->getNoWrapFlags());
9392 if (isa<SCEVMinMaxExpr>(Comm))
9393 return getMinMaxExpr(Comm->getSCEVType(), NewOps);
9394 if (isa<SCEVSequentialMinMaxExpr>(Comm))
9395 return getSequentialMinMaxExpr(Comm->getSCEVType(), NewOps);
9396 llvm_unreachable("Unknown commutative / sequential min/max SCEV type!")::llvm::llvm_unreachable_internal("Unknown commutative / sequential min/max SCEV type!"
, "llvm/lib/Analysis/ScalarEvolution.cpp", 9396);
9397 }
9398 }
9399 // If we got here, all operands are loop invariant.
9400 return Comm;
9401 }
9402
9403 if (const SCEVUDivExpr *Div = dyn_cast<SCEVUDivExpr>(V)) {
9404 const SCEV *LHS = getSCEVAtScope(Div->getLHS(), L);
9405 const SCEV *RHS = getSCEVAtScope(Div->getRHS(), L);
9406 if (LHS == Div->getLHS() && RHS == Div->getRHS())
9407 return Div; // must be loop invariant
9408 return getUDivExpr(LHS, RHS);
9409 }
9410
9411 // If this is a loop recurrence for a loop that does not contain L, then we
9412 // are dealing with the final value computed by the loop.
9413 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(V)) {
9414 // First, attempt to evaluate each operand.
9415 // Avoid performing the look-up in the common case where the specified
9416 // expression has no loop-variant portions.
9417 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
9418 const SCEV *OpAtScope = getSCEVAtScope(AddRec->getOperand(i), L);
9419 if (OpAtScope == AddRec->getOperand(i))
9420 continue;
9421
9422 // Okay, at least one of these operands is loop variant but might be
9423 // foldable. Build a new instance of the folded commutative expression.
9424 SmallVector<const SCEV *, 8> NewOps(AddRec->op_begin(),
9425 AddRec->op_begin()+i);
9426 NewOps.push_back(OpAtScope);
9427 for (++i; i != e; ++i)
9428 NewOps.push_back(getSCEVAtScope(AddRec->getOperand(i), L));
9429
9430 const SCEV *FoldedRec =
9431 getAddRecExpr(NewOps, AddRec->getLoop(),
9432 AddRec->getNoWrapFlags(SCEV::FlagNW));
9433 AddRec = dyn_cast<SCEVAddRecExpr>(FoldedRec);
9434 // The addrec may be folded to a nonrecurrence, for example, if the
9435 // induction variable is multiplied by zero after constant folding. Go
9436 // ahead and return the folded value.
9437 if (!AddRec)
9438 return FoldedRec;
9439 break;
9440 }
9441
9442 // If the scope is outside the addrec's loop, evaluate it by using the
9443 // loop exit value of the addrec.
9444 if (!AddRec->getLoop()->contains(L)) {
9445 // To evaluate this recurrence, we need to know how many times the AddRec
9446 // loop iterates. Compute this now.
9447 const SCEV *BackedgeTakenCount = getBackedgeTakenCount(AddRec->getLoop());
9448 if (BackedgeTakenCount == getCouldNotCompute()) return AddRec;
9449
9450 // Then, evaluate the AddRec.
9451 return AddRec->evaluateAtIteration(BackedgeTakenCount, *this);
9452 }
9453
9454 return AddRec;
9455 }
9456
9457 if (const SCEVCastExpr *Cast = dyn_cast<SCEVCastExpr>(V)) {
9458 const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
9459 if (Op == Cast->getOperand())
9460 return Cast; // must be loop invariant
9461 return getCastExpr(Cast->getSCEVType(), Op, Cast->getType());
9462 }
9463
9464 llvm_unreachable("Unknown SCEV type!")::llvm::llvm_unreachable_internal("Unknown SCEV type!", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 9464);
9465}
9466
9467const SCEV *ScalarEvolution::getSCEVAtScope(Value *V, const Loop *L) {
9468 return getSCEVAtScope(getSCEV(V), L);
9469}
9470
9471const SCEV *ScalarEvolution::stripInjectiveFunctions(const SCEV *S) const {
9472 if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S))
9473 return stripInjectiveFunctions(ZExt->getOperand());
9474 if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S))
9475 return stripInjectiveFunctions(SExt->getOperand());
9476 return S;
9477}
9478
9479/// Finds the minimum unsigned root of the following equation:
9480///
9481/// A * X = B (mod N)
9482///
9483/// where N = 2^BW and BW is the common bit width of A and B. The signedness of
9484/// A and B isn't important.
9485///
9486/// If the equation does not have a solution, SCEVCouldNotCompute is returned.
9487static const SCEV *SolveLinEquationWithOverflow(const APInt &A, const SCEV *B,
9488 ScalarEvolution &SE) {
9489 uint32_t BW = A.getBitWidth();
9490 assert(BW == SE.getTypeSizeInBits(B->getType()))(static_cast <bool> (BW == SE.getTypeSizeInBits(B->getType
())) ? void (0) : __assert_fail ("BW == SE.getTypeSizeInBits(B->getType())"
, "llvm/lib/Analysis/ScalarEvolution.cpp", 9490, __extension__
__PRETTY_FUNCTION__));
9491 assert(A != 0 && "A must be non-zero.")(static_cast <bool> (A != 0 && "A must be non-zero."
) ? void (0) : __assert_fail ("A != 0 && \"A must be non-zero.\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 9491, __extension__
__PRETTY_FUNCTION__));
9492
9493 // 1. D = gcd(A, N)
9494 //
9495 // The gcd of A and N may have only one prime factor: 2. The number of
9496 // trailing zeros in A is its multiplicity
9497 uint32_t Mult2 = A.countTrailingZeros();
9498 // D = 2^Mult2
9499
9500 // 2. Check if B is divisible by D.
9501 //
9502 // B is divisible by D if and only if the multiplicity of prime factor 2 for B
9503 // is not less than multiplicity of this prime factor for D.
9504 if (SE.GetMinTrailingZeros(B) < Mult2)
9505 return SE.getCouldNotCompute();
9506
9507 // 3. Compute I: the multiplicative inverse of (A / D) in arithmetic
9508 // modulo (N / D).
9509 //
9510 // If D == 1, (N / D) == N == 2^BW, so we need one extra bit to represent
9511 // (N / D) in general. The inverse itself always fits into BW bits, though,
9512 // so we immediately truncate it.
9513 APInt AD = A.lshr(Mult2).zext(BW + 1); // AD = A / D
9514 APInt Mod(BW + 1, 0);
9515 Mod.setBit(BW - Mult2); // Mod = N / D
9516 APInt I = AD.multiplicativeInverse(Mod).trunc(BW);
9517
9518 // 4. Compute the minimum unsigned root of the equation:
9519 // I * (B / D) mod (N / D)
9520 // To simplify the computation, we factor out the divide by D:
9521 // (I * B mod N) / D
9522 const SCEV *D = SE.getConstant(APInt::getOneBitSet(BW, Mult2));
9523 return SE.getUDivExactExpr(SE.getMulExpr(B, SE.getConstant(I)), D);
9524}
9525
9526/// For a given quadratic addrec, generate coefficients of the corresponding
9527/// quadratic equation, multiplied by a common value to ensure that they are
9528/// integers.
9529/// The returned value is a tuple { A, B, C, M, BitWidth }, where
9530/// Ax^2 + Bx + C is the quadratic function, M is the value that A, B and C
9531/// were multiplied by, and BitWidth is the bit width of the original addrec
9532/// coefficients.
9533/// This function returns None if the addrec coefficients are not compile-
9534/// time constants.
9535static Optional<std::tuple<APInt, APInt, APInt, APInt, unsigned>>
9536GetQuadraticEquation(const SCEVAddRecExpr *AddRec) {
9537 assert(AddRec->getNumOperands() == 3 && "This is not a quadratic chrec!")(static_cast <bool> (AddRec->getNumOperands() == 3 &&
"This is not a quadratic chrec!") ? void (0) : __assert_fail
("AddRec->getNumOperands() == 3 && \"This is not a quadratic chrec!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 9537, __extension__
__PRETTY_FUNCTION__));
9538 const SCEVConstant *LC = dyn_cast<SCEVConstant>(AddRec->getOperand(0));
9539 const SCEVConstant *MC = dyn_cast<SCEVConstant>(AddRec->getOperand(1));
9540 const SCEVConstant *NC = dyn_cast<SCEVConstant>(AddRec->getOperand(2));
9541 LLVM_DEBUG(dbgs() << __func__ << ": analyzing quadratic addrec: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": analyzing quadratic addrec: "
<< *AddRec << '\n'; } } while (false)
9542 << *AddRec << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": analyzing quadratic addrec: "
<< *AddRec << '\n'; } } while (false);
9543
9544 // We currently can only solve this if the coefficients are constants.
9545 if (!LC || !MC || !NC) {
9546 LLVM_DEBUG(dbgs() << __func__ << ": coefficients are not constant\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": coefficients are not constant\n"
; } } while (false);
9547 return None;
9548 }
9549
9550 APInt L = LC->getAPInt();
9551 APInt M = MC->getAPInt();
9552 APInt N = NC->getAPInt();
9553 assert(!N.isZero() && "This is not a quadratic addrec")(static_cast <bool> (!N.isZero() && "This is not a quadratic addrec"
) ? void (0) : __assert_fail ("!N.isZero() && \"This is not a quadratic addrec\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 9553, __extension__
__PRETTY_FUNCTION__));
9554
9555 unsigned BitWidth = LC->getAPInt().getBitWidth();
9556 unsigned NewWidth = BitWidth + 1;
9557 LLVM_DEBUG(dbgs() << __func__ << ": addrec coeff bw: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": addrec coeff bw: "
<< BitWidth << '\n'; } } while (false)
9558 << BitWidth << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": addrec coeff bw: "
<< BitWidth << '\n'; } } while (false);
9559 // The sign-extension (as opposed to a zero-extension) here matches the
9560 // extension used in SolveQuadraticEquationWrap (with the same motivation).
9561 N = N.sext(NewWidth);
9562 M = M.sext(NewWidth);
9563 L = L.sext(NewWidth);
9564
9565 // The increments are M, M+N, M+2N, ..., so the accumulated values are
9566 // L+M, (L+M)+(M+N), (L+M)+(M+N)+(M+2N), ..., that is,
9567 // L+M, L+2M+N, L+3M+3N, ...
9568 // After n iterations the accumulated value Acc is L + nM + n(n-1)/2 N.
9569 //
9570 // The equation Acc = 0 is then
9571 // L + nM + n(n-1)/2 N = 0, or 2L + 2M n + n(n-1) N = 0.
9572 // In a quadratic form it becomes:
9573 // N n^2 + (2M-N) n + 2L = 0.
9574
9575 APInt A = N;
9576 APInt B = 2 * M - A;
9577 APInt C = 2 * L;
9578 APInt T = APInt(NewWidth, 2);
9579 LLVM_DEBUG(dbgs() << __func__ << ": equation " << A << "x^2 + " << Bdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": equation "
<< A << "x^2 + " << B << "x + " <<
C << ", coeff bw: " << NewWidth << ", multiplied by "
<< T << '\n'; } } while (false)
9580 << "x + " << C << ", coeff bw: " << NewWidthdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": equation "
<< A << "x^2 + " << B << "x + " <<
C << ", coeff bw: " << NewWidth << ", multiplied by "
<< T << '\n'; } } while (false)
9581 << ", multiplied by " << T << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": equation "
<< A << "x^2 + " << B << "x + " <<
C << ", coeff bw: " << NewWidth << ", multiplied by "
<< T << '\n'; } } while (false);
9582 return std::make_tuple(A, B, C, T, BitWidth);
9583}
9584
9585/// Helper function to compare optional APInts:
9586/// (a) if X and Y both exist, return min(X, Y),
9587/// (b) if neither X nor Y exist, return None,
9588/// (c) if exactly one of X and Y exists, return that value.
9589static Optional<APInt> MinOptional(Optional<APInt> X, Optional<APInt> Y) {
9590 if (X.hasValue() && Y.hasValue()) {
9591 unsigned W = std::max(X->getBitWidth(), Y->getBitWidth());
9592 APInt XW = X->sextOrSelf(W);
9593 APInt YW = Y->sextOrSelf(W);
9594 return XW.slt(YW) ? *X : *Y;
9595 }
9596 if (!X.hasValue() && !Y.hasValue())
9597 return None;
9598 return X.hasValue() ? *X : *Y;
9599}
9600
9601/// Helper function to truncate an optional APInt to a given BitWidth.
9602/// When solving addrec-related equations, it is preferable to return a value
9603/// that has the same bit width as the original addrec's coefficients. If the
9604/// solution fits in the original bit width, truncate it (except for i1).
9605/// Returning a value of a different bit width may inhibit some optimizations.
9606///
9607/// In general, a solution to a quadratic equation generated from an addrec
9608/// may require BW+1 bits, where BW is the bit width of the addrec's
9609/// coefficients. The reason is that the coefficients of the quadratic
9610/// equation are BW+1 bits wide (to avoid truncation when converting from
9611/// the addrec to the equation).
9612static Optional<APInt> TruncIfPossible(Optional<APInt> X, unsigned BitWidth) {
9613 if (!X.hasValue())
9614 return None;
9615 unsigned W = X->getBitWidth();
9616 if (BitWidth > 1 && BitWidth < W && X->isIntN(BitWidth))
9617 return X->trunc(BitWidth);
9618 return X;
9619}
9620
9621/// Let c(n) be the value of the quadratic chrec {L,+,M,+,N} after n
9622/// iterations. The values L, M, N are assumed to be signed, and they
9623/// should all have the same bit widths.
9624/// Find the least n >= 0 such that c(n) = 0 in the arithmetic modulo 2^BW,
9625/// where BW is the bit width of the addrec's coefficients.
9626/// If the calculated value is a BW-bit integer (for BW > 1), it will be
9627/// returned as such, otherwise the bit width of the returned value may
9628/// be greater than BW.
9629///
9630/// This function returns None if
9631/// (a) the addrec coefficients are not constant, or
9632/// (b) SolveQuadraticEquationWrap was unable to find a solution. For cases
9633/// like x^2 = 5, no integer solutions exist, in other cases an integer
9634/// solution may exist, but SolveQuadraticEquationWrap may fail to find it.
9635static Optional<APInt>
9636SolveQuadraticAddRecExact(const SCEVAddRecExpr *AddRec, ScalarEvolution &SE) {
9637 APInt A, B, C, M;
9638 unsigned BitWidth;
9639 auto T = GetQuadraticEquation(AddRec);
9640 if (!T.hasValue())
9641 return None;
9642
9643 std::tie(A, B, C, M, BitWidth) = *T;
9644 LLVM_DEBUG(dbgs() << __func__ << ": solving for unsigned overflow\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": solving for unsigned overflow\n"
; } } while (false);
9645 Optional<APInt> X = APIntOps::SolveQuadraticEquationWrap(A, B, C, BitWidth+1);
9646 if (!X.hasValue())
9647 return None;
9648
9649 ConstantInt *CX = ConstantInt::get(SE.getContext(), *X);
9650 ConstantInt *V = EvaluateConstantChrecAtConstant(AddRec, CX, SE);
9651 if (!V->isZero())
9652 return None;
9653
9654 return TruncIfPossible(X, BitWidth);
9655}
9656
9657/// Let c(n) be the value of the quadratic chrec {0,+,M,+,N} after n
9658/// iterations. The values M, N are assumed to be signed, and they
9659/// should all have the same bit widths.
9660/// Find the least n such that c(n) does not belong to the given range,
9661/// while c(n-1) does.
9662///
9663/// This function returns None if
9664/// (a) the addrec coefficients are not constant, or
9665/// (b) SolveQuadraticEquationWrap was unable to find a solution for the
9666/// bounds of the range.
9667static Optional<APInt>
9668SolveQuadraticAddRecRange(const SCEVAddRecExpr *AddRec,
9669 const ConstantRange &Range, ScalarEvolution &SE) {
9670 assert(AddRec->getOperand(0)->isZero() &&(static_cast <bool> (AddRec->getOperand(0)->isZero
() && "Starting value of addrec should be 0") ? void (
0) : __assert_fail ("AddRec->getOperand(0)->isZero() && \"Starting value of addrec should be 0\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 9671, __extension__
__PRETTY_FUNCTION__))
9671 "Starting value of addrec should be 0")(static_cast <bool> (AddRec->getOperand(0)->isZero
() && "Starting value of addrec should be 0") ? void (
0) : __assert_fail ("AddRec->getOperand(0)->isZero() && \"Starting value of addrec should be 0\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 9671, __extension__
__PRETTY_FUNCTION__));
9672 LLVM_DEBUG(dbgs() << __func__ << ": solving boundary crossing for range "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": solving boundary crossing for range "
<< Range << ", addrec " << *AddRec <<
'\n'; } } while (false)
9673 << Range << ", addrec " << *AddRec << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": solving boundary crossing for range "
<< Range << ", addrec " << *AddRec <<
'\n'; } } while (false);
9674 // This case is handled in getNumIterationsInRange. Here we can assume that
9675 // we start in the range.
9676 assert(Range.contains(APInt(SE.getTypeSizeInBits(AddRec->getType()), 0)) &&(static_cast <bool> (Range.contains(APInt(SE.getTypeSizeInBits
(AddRec->getType()), 0)) && "Addrec's initial value should be in range"
) ? void (0) : __assert_fail ("Range.contains(APInt(SE.getTypeSizeInBits(AddRec->getType()), 0)) && \"Addrec's initial value should be in range\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 9677, __extension__
__PRETTY_FUNCTION__))
9677 "Addrec's initial value should be in range")(static_cast <bool> (Range.contains(APInt(SE.getTypeSizeInBits
(AddRec->getType()), 0)) && "Addrec's initial value should be in range"
) ? void (0) : __assert_fail ("Range.contains(APInt(SE.getTypeSizeInBits(AddRec->getType()), 0)) && \"Addrec's initial value should be in range\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 9677, __extension__
__PRETTY_FUNCTION__));
9678
9679 APInt A, B, C, M;
9680 unsigned BitWidth;
9681 auto T = GetQuadraticEquation(AddRec);
9682 if (!T.hasValue())
9683 return None;
9684
9685 // Be careful about the return value: there can be two reasons for not
9686 // returning an actual number. First, if no solutions to the equations
9687 // were found, and second, if the solutions don't leave the given range.
9688 // The first case means that the actual solution is "unknown", the second
9689 // means that it's known, but not valid. If the solution is unknown, we
9690 // cannot make any conclusions.
9691 // Return a pair: the optional solution and a flag indicating if the
9692 // solution was found.
9693 auto SolveForBoundary = [&](APInt Bound) -> std::pair<Optional<APInt>,bool> {
9694 // Solve for signed overflow and unsigned overflow, pick the lower
9695 // solution.
9696 LLVM_DEBUG(dbgs() << "SolveQuadraticAddRecRange: checking boundary "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: checking boundary "
<< Bound << " (before multiplying by " << M
<< ")\n"; } } while (false)
9697 << Bound << " (before multiplying by " << M << ")\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: checking boundary "
<< Bound << " (before multiplying by " << M
<< ")\n"; } } while (false);
9698 Bound *= M; // The quadratic equation multiplier.
9699
9700 Optional<APInt> SO = None;
9701 if (BitWidth > 1) {
9702 LLVM_DEBUG(dbgs() << "SolveQuadraticAddRecRange: solving for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for "
"signed overflow\n"; } } while (false)
9703 "signed overflow\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for "
"signed overflow\n"; } } while (false);
9704 SO = APIntOps::SolveQuadraticEquationWrap(A, B, -Bound, BitWidth);
9705 }
9706 LLVM_DEBUG(dbgs() << "SolveQuadraticAddRecRange: solving for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for "
"unsigned overflow\n"; } } while (false)
9707 "unsigned overflow\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for "
"unsigned overflow\n"; } } while (false);
9708 Optional<APInt> UO = APIntOps::SolveQuadraticEquationWrap(A, B, -Bound,
9709 BitWidth+1);
9710
9711 auto LeavesRange = [&] (const APInt &X) {
9712 ConstantInt *C0 = ConstantInt::get(SE.getContext(), X);
9713 ConstantInt *V0 = EvaluateConstantChrecAtConstant(AddRec, C0, SE);
9714 if (Range.contains(V0->getValue()))
9715 return false;
9716 // X should be at least 1, so X-1 is non-negative.
9717 ConstantInt *C1 = ConstantInt::get(SE.getContext(), X-1);
9718 ConstantInt *V1 = EvaluateConstantChrecAtConstant(AddRec, C1, SE);
9719 if (Range.contains(V1->getValue()))
9720 return true;
9721 return false;
9722 };
9723
9724 // If SolveQuadraticEquationWrap returns None, it means that there can
9725 // be a solution, but the function failed to find it. We cannot treat it
9726 // as "no solution".
9727 if (!SO.hasValue() || !UO.hasValue())
9728 return { None, false };
9729
9730 // Check the smaller value first to see if it leaves the range.
9731 // At this point, both SO and UO must have values.
9732 Optional<APInt> Min = MinOptional(SO, UO);
9733 if (LeavesRange(*Min))
9734 return { Min, true };
9735 Optional<APInt> Max = Min == SO ? UO : SO;
9736 if (LeavesRange(*Max))
9737 return { Max, true };
9738
9739 // Solutions were found, but were eliminated, hence the "true".
9740 return { None, true };
9741 };
9742
9743 std::tie(A, B, C, M, BitWidth) = *T;
9744 // Lower bound is inclusive, subtract 1 to represent the exiting value.
9745 APInt Lower = Range.getLower().sextOrSelf(A.getBitWidth()) - 1;
9746 APInt Upper = Range.getUpper().sextOrSelf(A.getBitWidth());
9747 auto SL = SolveForBoundary(Lower);
9748 auto SU = SolveForBoundary(Upper);
9749 // If any of the solutions was unknown, no meaninigful conclusions can
9750 // be made.
9751 if (!SL.second || !SU.second)
9752 return None;
9753
9754 // Claim: The correct solution is not some value between Min and Max.
9755 //
9756 // Justification: Assuming that Min and Max are different values, one of
9757 // them is when the first signed overflow happens, the other is when the
9758 // first unsigned overflow happens. Crossing the range boundary is only
9759 // possible via an overflow (treating 0 as a special case of it, modeling
9760 // an overflow as crossing k*2^W for some k).
9761 //
9762 // The interesting case here is when Min was eliminated as an invalid
9763 // solution, but Max was not. The argument is that if there was another
9764 // overflow between Min and Max, it would also have been eliminated if
9765 // it was considered.
9766 //
9767 // For a given boundary, it is possible to have two overflows of the same
9768 // type (signed/unsigned) without having the other type in between: this
9769 // can happen when the vertex of the parabola is between the iterations
9770 // corresponding to the overflows. This is only possible when the two
9771 // overflows cross k*2^W for the same k. In such case, if the second one
9772 // left the range (and was the first one to do so), the first overflow
9773 // would have to enter the range, which would mean that either we had left
9774 // the range before or that we started outside of it. Both of these cases
9775 // are contradictions.
9776 //
9777 // Claim: In the case where SolveForBoundary returns None, the correct
9778 // solution is not some value between the Max for this boundary and the
9779 // Min of the other boundary.
9780 //
9781 // Justification: Assume that we had such Max_A and Min_B corresponding
9782 // to range boundaries A and B and such that Max_A < Min_B. If there was
9783 // a solution between Max_A and Min_B, it would have to be caused by an
9784 // overflow corresponding to either A or B. It cannot correspond to B,
9785 // since Min_B is the first occurrence of such an overflow. If it
9786 // corresponded to A, it would have to be either a signed or an unsigned
9787 // overflow that is larger than both eliminated overflows for A. But
9788 // between the eliminated overflows and this overflow, the values would
9789 // cover the entire value space, thus crossing the other boundary, which
9790 // is a contradiction.
9791
9792 return TruncIfPossible(MinOptional(SL.first, SU.first), BitWidth);
9793}
9794
9795ScalarEvolution::ExitLimit
9796ScalarEvolution::howFarToZero(const SCEV *V, const Loop *L, bool ControlsExit,
9797 bool AllowPredicates) {
9798
9799 // This is only used for loops with a "x != y" exit test. The exit condition
9800 // is now expressed as a single expression, V = x-y. So the exit test is
9801 // effectively V != 0. We know and take advantage of the fact that this
9802 // expression only being used in a comparison by zero context.
9803
9804 SmallPtrSet<const SCEVPredicate *, 4> Predicates;
9805 // If the value is a constant
9806 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
9807 // If the value is already zero, the branch will execute zero times.
9808 if (C->getValue()->isZero()) return C;
9809 return getCouldNotCompute(); // Otherwise it will loop infinitely.
9810 }
9811
9812 const SCEVAddRecExpr *AddRec =
9813 dyn_cast<SCEVAddRecExpr>(stripInjectiveFunctions(V));
9814
9815 if (!AddRec && AllowPredicates)
9816 // Try to make this an AddRec using runtime tests, in the first X
9817 // iterations of this loop, where X is the SCEV expression found by the
9818 // algorithm below.
9819 AddRec = convertSCEVToAddRecWithPredicates(V, L, Predicates);
9820
9821 if (!AddRec || AddRec->getLoop() != L)
9822 return getCouldNotCompute();
9823
9824 // If this is a quadratic (3-term) AddRec {L,+,M,+,N}, find the roots of
9825 // the quadratic equation to solve it.
9826 if (AddRec->isQuadratic() && AddRec->getType()->isIntegerTy()) {
9827 // We can only use this value if the chrec ends up with an exact zero
9828 // value at this index. When solving for "X*X != 5", for example, we
9829 // should not accept a root of 2.
9830 if (auto S = SolveQuadraticAddRecExact(AddRec, *this)) {
9831 const auto *R = cast<SCEVConstant>(getConstant(S.getValue()));
9832 return ExitLimit(R, R, false, Predicates);
9833 }
9834 return getCouldNotCompute();
9835 }
9836
9837 // Otherwise we can only handle this if it is affine.
9838 if (!AddRec->isAffine())
9839 return getCouldNotCompute();
9840
9841 // If this is an affine expression, the execution count of this branch is
9842 // the minimum unsigned root of the following equation:
9843 //
9844 // Start + Step*N = 0 (mod 2^BW)
9845 //
9846 // equivalent to:
9847 //
9848 // Step*N = -Start (mod 2^BW)
9849 //
9850 // where BW is the common bit width of Start and Step.
9851
9852 // Get the initial value for the loop.
9853 const SCEV *Start = getSCEVAtScope(AddRec->getStart(), L->getParentLoop());
9854 const SCEV *Step = getSCEVAtScope(AddRec->getOperand(1), L->getParentLoop());
9855
9856 // For now we handle only constant steps.
9857 //
9858 // TODO: Handle a nonconstant Step given AddRec<NUW>. If the
9859 // AddRec is NUW, then (in an unsigned sense) it cannot be counting up to wrap
9860 // to 0, it must be counting down to equal 0. Consequently, N = Start / -Step.
9861 // We have not yet seen any such cases.
9862 const SCEVConstant *StepC = dyn_cast<SCEVConstant>(Step);
9863 if (!StepC || StepC->getValue()->isZero())
9864 return getCouldNotCompute();
9865
9866 // For positive steps (counting up until unsigned overflow):
9867 // N = -Start/Step (as unsigned)
9868 // For negative steps (counting down to zero):
9869 // N = Start/-Step
9870 // First compute the unsigned distance from zero in the direction of Step.
9871 bool CountDown = StepC->getAPInt().isNegative();
9872 const SCEV *Distance = CountDown ? Start : getNegativeSCEV(Start);
9873
9874 // Handle unitary steps, which cannot wraparound.
9875 // 1*N = -Start; -1*N = Start (mod 2^BW), so:
9876 // N = Distance (as unsigned)
9877 if (StepC->getValue()->isOne() || StepC->getValue()->isMinusOne()) {
9878 APInt MaxBECount = getUnsignedRangeMax(applyLoopGuards(Distance, L));
9879 MaxBECount = APIntOps::umin(MaxBECount, getUnsignedRangeMax(Distance));
9880
9881 // When a loop like "for (int i = 0; i != n; ++i) { /* body */ }" is rotated,
9882 // we end up with a loop whose backedge-taken count is n - 1. Detect this
9883 // case, and see if we can improve the bound.
9884 //
9885 // Explicitly handling this here is necessary because getUnsignedRange
9886 // isn't context-sensitive; it doesn't know that we only care about the
9887 // range inside the loop.
9888 const SCEV *Zero = getZero(Distance->getType());
9889 const SCEV *One = getOne(Distance->getType());
9890 const SCEV *DistancePlusOne = getAddExpr(Distance, One);
9891 if (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_NE, DistancePlusOne, Zero)) {
9892 // If Distance + 1 doesn't overflow, we can compute the maximum distance
9893 // as "unsigned_max(Distance + 1) - 1".
9894 ConstantRange CR = getUnsignedRange(DistancePlusOne);
9895 MaxBECount = APIntOps::umin(MaxBECount, CR.getUnsignedMax() - 1);
9896 }
9897 return ExitLimit(Distance, getConstant(MaxBECount), false, Predicates);
9898 }
9899
9900 // If the condition controls loop exit (the loop exits only if the expression
9901 // is true) and the addition is no-wrap we can use unsigned divide to
9902 // compute the backedge count. In this case, the step may not divide the
9903 // distance, but we don't care because if the condition is "missed" the loop
9904 // will have undefined behavior due to wrapping.
9905 if (ControlsExit && AddRec->hasNoSelfWrap() &&
9906 loopHasNoAbnormalExits(AddRec->getLoop())) {
9907 const SCEV *Exact =
9908 getUDivExpr(Distance, CountDown ? getNegativeSCEV(Step) : Step);
9909 const SCEV *Max = getCouldNotCompute();
9910 if (Exact != getCouldNotCompute()) {
9911 APInt MaxInt = getUnsignedRangeMax(applyLoopGuards(Exact, L));
9912 Max = getConstant(APIntOps::umin(MaxInt, getUnsignedRangeMax(Exact)));
9913 }
9914 return ExitLimit(Exact, Max, false, Predicates);
9915 }
9916
9917 // Solve the general equation.
9918 const SCEV *E = SolveLinEquationWithOverflow(StepC->getAPInt(),
9919 getNegativeSCEV(Start), *this);
9920
9921 const SCEV *M = E;
9922 if (E != getCouldNotCompute()) {
9923 APInt MaxWithGuards = getUnsignedRangeMax(applyLoopGuards(E, L));
9924 M = getConstant(APIntOps::umin(MaxWithGuards, getUnsignedRangeMax(E)));
9925 }
9926 return ExitLimit(E, M, false, Predicates);
9927}
9928
9929ScalarEvolution::ExitLimit
9930ScalarEvolution::howFarToNonZero(const SCEV *V, const Loop *L) {
9931 // Loops that look like: while (X == 0) are very strange indeed. We don't
9932 // handle them yet except for the trivial case. This could be expanded in the
9933 // future as needed.
9934
9935 // If the value is a constant, check to see if it is known to be non-zero
9936 // already. If so, the backedge will execute zero times.
9937 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
9938 if (!C->getValue()->isZero())
9939 return getZero(C->getType());
9940 return getCouldNotCompute(); // Otherwise it will loop infinitely.
9941 }
9942
9943 // We could implement others, but I really doubt anyone writes loops like
9944 // this, and if they did, they would already be constant folded.
9945 return getCouldNotCompute();
9946}
9947
9948std::pair<const BasicBlock *, const BasicBlock *>
9949ScalarEvolution::getPredecessorWithUniqueSuccessorForBB(const BasicBlock *BB)
9950 const {
9951 // If the block has a unique predecessor, then there is no path from the
9952 // predecessor to the block that does not go through the direct edge
9953 // from the predecessor to the block.
9954 if (const BasicBlock *Pred = BB->getSinglePredecessor())
9955 return {Pred, BB};
9956
9957 // A loop's header is defined to be a block that dominates the loop.
9958 // If the header has a unique predecessor outside the loop, it must be
9959 // a block that has exactly one successor that can reach the loop.
9960 if (const Loop *L = LI.getLoopFor(BB))
9961 return {L->getLoopPredecessor(), L->getHeader()};
9962
9963 return {nullptr, nullptr};
9964}
9965
9966/// SCEV structural equivalence is usually sufficient for testing whether two
9967/// expressions are equal, however for the purposes of looking for a condition
9968/// guarding a loop, it can be useful to be a little more general, since a
9969/// front-end may have replicated the controlling expression.
9970static bool HasSameValue(const SCEV *A, const SCEV *B) {
9971 // Quick check to see if they are the same SCEV.
9972 if (A == B) return true;
9973
9974 auto ComputesEqualValues = [](const Instruction *A, const Instruction *B) {
9975 // Not all instructions that are "identical" compute the same value. For
9976 // instance, two distinct alloca instructions allocating the same type are
9977 // identical and do not read memory; but compute distinct values.
9978 return A->isIdenticalTo(B) && (isa<BinaryOperator>(A) || isa<GetElementPtrInst>(A));
9979 };
9980
9981 // Otherwise, if they're both SCEVUnknown, it's possible that they hold
9982 // two different instructions with the same value. Check for this case.
9983 if (const SCEVUnknown *AU = dyn_cast<SCEVUnknown>(A))
9984 if (const SCEVUnknown *BU = dyn_cast<SCEVUnknown>(B))
9985 if (const Instruction *AI = dyn_cast<Instruction>(AU->getValue()))
9986 if (const Instruction *BI = dyn_cast<Instruction>(BU->getValue()))
9987 if (ComputesEqualValues(AI, BI))
9988 return true;
9989
9990 // Otherwise assume they may have a different value.
9991 return false;
9992}
9993
9994bool ScalarEvolution::SimplifyICmpOperands(ICmpInst::Predicate &Pred,
9995 const SCEV *&LHS, const SCEV *&RHS,
9996 unsigned Depth,
9997 bool ControllingFiniteLoop) {
9998 bool Changed = false;
9999 // Simplifies ICMP to trivial true or false by turning it into '0 == 0' or
10000 // '0 != 0'.
10001 auto TrivialCase = [&](bool TriviallyTrue) {
10002 LHS = RHS = getConstant(ConstantInt::getFalse(getContext()));
10003 Pred = TriviallyTrue ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE;
10004 return true;
10005 };
10006 // If we hit the max recursion limit bail out.
10007 if (Depth >= 3)
10008 return false;
10009
10010 // Canonicalize a constant to the right side.
10011 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
10012 // Check for both operands constant.
10013 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
10014 if (ConstantExpr::getICmp(Pred,
10015 LHSC->getValue(),
10016 RHSC->getValue())->isNullValue())
10017 return TrivialCase(false);
10018 else
10019 return TrivialCase(true);
10020 }
10021 // Otherwise swap the operands to put the constant on the right.
10022 std::swap(LHS, RHS);
10023 Pred = ICmpInst::getSwappedPredicate(Pred);
10024 Changed = true;
10025 }
10026
10027 // If we're comparing an addrec with a value which is loop-invariant in the
10028 // addrec's loop, put the addrec on the left. Also make a dominance check,
10029 // as both operands could be addrecs loop-invariant in each other's loop.
10030 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(RHS)) {
10031 const Loop *L = AR->getLoop();
10032 if (isLoopInvariant(LHS, L) && properlyDominates(LHS, L->getHeader())) {
10033 std::swap(LHS, RHS);
10034 Pred = ICmpInst::getSwappedPredicate(Pred);
10035 Changed = true;
10036 }
10037 }
10038
10039 // If there's a constant operand, canonicalize comparisons with boundary
10040 // cases, and canonicalize *-or-equal comparisons to regular comparisons.
10041 if (const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS)) {
10042 const APInt &RA = RC->getAPInt();
10043
10044 bool SimplifiedByConstantRange = false;
10045
10046 if (!ICmpInst::isEquality(Pred)) {
10047 ConstantRange ExactCR = ConstantRange::makeExactICmpRegion(Pred, RA);
10048 if (ExactCR.isFullSet())
10049 return TrivialCase(true);
10050 else if (ExactCR.isEmptySet())
10051 return TrivialCase(false);
10052
10053 APInt NewRHS;
10054 CmpInst::Predicate NewPred;
10055 if (ExactCR.getEquivalentICmp(NewPred, NewRHS) &&
10056 ICmpInst::isEquality(NewPred)) {
10057 // We were able to convert an inequality to an equality.
10058 Pred = NewPred;
10059 RHS = getConstant(NewRHS);
10060 Changed = SimplifiedByConstantRange = true;
10061 }
10062 }
10063
10064 if (!SimplifiedByConstantRange) {
10065 switch (Pred) {
10066 default:
10067 break;
10068 case ICmpInst::ICMP_EQ:
10069 case ICmpInst::ICMP_NE:
10070 // Fold ((-1) * %a) + %b == 0 (equivalent to %b-%a == 0) into %a == %b.
10071 if (!RA)
10072 if (const SCEVAddExpr *AE = dyn_cast<SCEVAddExpr>(LHS))
10073 if (const SCEVMulExpr *ME =
10074 dyn_cast<SCEVMulExpr>(AE->getOperand(0)))
10075 if (AE->getNumOperands() == 2 && ME->getNumOperands() == 2 &&
10076 ME->getOperand(0)->isAllOnesValue()) {
10077 RHS = AE->getOperand(1);
10078 LHS = ME->getOperand(1);
10079 Changed = true;
10080 }
10081 break;
10082
10083
10084 // The "Should have been caught earlier!" messages refer to the fact
10085 // that the ExactCR.isFullSet() or ExactCR.isEmptySet() check above
10086 // should have fired on the corresponding cases, and canonicalized the
10087 // check to trivial case.
10088
10089 case ICmpInst::ICMP_UGE:
10090 assert(!RA.isMinValue() && "Should have been caught earlier!")(static_cast <bool> (!RA.isMinValue() && "Should have been caught earlier!"
) ? void (0) : __assert_fail ("!RA.isMinValue() && \"Should have been caught earlier!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10090, __extension__
__PRETTY_FUNCTION__));
10091 Pred = ICmpInst::ICMP_UGT;
10092 RHS = getConstant(RA - 1);
10093 Changed = true;
10094 break;
10095 case ICmpInst::ICMP_ULE:
10096 assert(!RA.isMaxValue() && "Should have been caught earlier!")(static_cast <bool> (!RA.isMaxValue() && "Should have been caught earlier!"
) ? void (0) : __assert_fail ("!RA.isMaxValue() && \"Should have been caught earlier!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10096, __extension__
__PRETTY_FUNCTION__));
10097 Pred = ICmpInst::ICMP_ULT;
10098 RHS = getConstant(RA + 1);
10099 Changed = true;
10100 break;
10101 case ICmpInst::ICMP_SGE:
10102 assert(!RA.isMinSignedValue() && "Should have been caught earlier!")(static_cast <bool> (!RA.isMinSignedValue() && "Should have been caught earlier!"
) ? void (0) : __assert_fail ("!RA.isMinSignedValue() && \"Should have been caught earlier!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10102, __extension__
__PRETTY_FUNCTION__));
10103 Pred = ICmpInst::ICMP_SGT;
10104 RHS = getConstant(RA - 1);
10105 Changed = true;
10106 break;
10107 case ICmpInst::ICMP_SLE:
10108 assert(!RA.isMaxSignedValue() && "Should have been caught earlier!")(static_cast <bool> (!RA.isMaxSignedValue() && "Should have been caught earlier!"
) ? void (0) : __assert_fail ("!RA.isMaxSignedValue() && \"Should have been caught earlier!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10108, __extension__
__PRETTY_FUNCTION__));
10109 Pred = ICmpInst::ICMP_SLT;
10110 RHS = getConstant(RA + 1);
10111 Changed = true;
10112 break;
10113 }
10114 }
10115 }
10116
10117 // Check for obvious equality.
10118 if (HasSameValue(LHS, RHS)) {
10119 if (ICmpInst::isTrueWhenEqual(Pred))
10120 return TrivialCase(true);
10121 if (ICmpInst::isFalseWhenEqual(Pred))
10122 return TrivialCase(false);
10123 }
10124
10125 // If possible, canonicalize GE/LE comparisons to GT/LT comparisons, by
10126 // adding or subtracting 1 from one of the operands. This can be done for
10127 // one of two reasons:
10128 // 1) The range of the RHS does not include the (signed/unsigned) boundaries
10129 // 2) The loop is finite, with this comparison controlling the exit. Since the
10130 // loop is finite, the bound cannot include the corresponding boundary
10131 // (otherwise it would loop forever).
10132 switch (Pred) {
10133 case ICmpInst::ICMP_SLE:
10134 if (ControllingFiniteLoop || !getSignedRangeMax(RHS).isMaxSignedValue()) {
10135 RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
10136 SCEV::FlagNSW);
10137 Pred = ICmpInst::ICMP_SLT;
10138 Changed = true;
10139 } else if (!getSignedRangeMin(LHS).isMinSignedValue()) {
10140 LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS,
10141 SCEV::FlagNSW);
10142 Pred = ICmpInst::ICMP_SLT;
10143 Changed = true;
10144 }
10145 break;
10146 case ICmpInst::ICMP_SGE:
10147 if (ControllingFiniteLoop || !getSignedRangeMin(RHS).isMinSignedValue()) {
10148 RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS,
10149 SCEV::FlagNSW);
10150 Pred = ICmpInst::ICMP_SGT;
10151 Changed = true;
10152 } else if (!getSignedRangeMax(LHS).isMaxSignedValue()) {
10153 LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
10154 SCEV::FlagNSW);
10155 Pred = ICmpInst::ICMP_SGT;
10156 Changed = true;
10157 }
10158 break;
10159 case ICmpInst::ICMP_ULE:
10160 if (ControllingFiniteLoop || !getUnsignedRangeMax(RHS).isMaxValue()) {
10161 RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
10162 SCEV::FlagNUW);
10163 Pred = ICmpInst::ICMP_ULT;
10164 Changed = true;
10165 } else if (!getUnsignedRangeMin(LHS).isMinValue()) {
10166 LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS);
10167 Pred = ICmpInst::ICMP_ULT;
10168 Changed = true;
10169 }
10170 break;
10171 case ICmpInst::ICMP_UGE:
10172 if (ControllingFiniteLoop || !getUnsignedRangeMin(RHS).isMinValue()) {
10173 RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS);
10174 Pred = ICmpInst::ICMP_UGT;
10175 Changed = true;
10176 } else if (!getUnsignedRangeMax(LHS).isMaxValue()) {
10177 LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
10178 SCEV::FlagNUW);
10179 Pred = ICmpInst::ICMP_UGT;
10180 Changed = true;
10181 }
10182 break;
10183 default:
10184 break;
10185 }
10186
10187 // TODO: More simplifications are possible here.
10188
10189 // Recursively simplify until we either hit a recursion limit or nothing
10190 // changes.
10191 if (Changed)
10192 return SimplifyICmpOperands(Pred, LHS, RHS, Depth + 1,
10193 ControllingFiniteLoop);
10194
10195 return Changed;
10196}
10197
10198bool ScalarEvolution::isKnownNegative(const SCEV *S) {
10199 return getSignedRangeMax(S).isNegative();
10200}
10201
10202bool ScalarEvolution::isKnownPositive(const SCEV *S) {
10203 return getSignedRangeMin(S).isStrictlyPositive();
10204}
10205
10206bool ScalarEvolution::isKnownNonNegative(const SCEV *S) {
10207 return !getSignedRangeMin(S).isNegative();
10208}
10209
10210bool ScalarEvolution::isKnownNonPositive(const SCEV *S) {
10211 return !getSignedRangeMax(S).isStrictlyPositive();
10212}
10213
10214bool ScalarEvolution::isKnownNonZero(const SCEV *S) {
10215 return getUnsignedRangeMin(S) != 0;
10216}
10217
10218std::pair<const SCEV *, const SCEV *>
10219ScalarEvolution::SplitIntoInitAndPostInc(const Loop *L, const SCEV *S) {
10220 // Compute SCEV on entry of loop L.
10221 const SCEV *Start = SCEVInitRewriter::rewrite(S, L, *this);
10222 if (Start == getCouldNotCompute())
10223 return { Start, Start };
10224 // Compute post increment SCEV for loop L.
10225 const SCEV *PostInc = SCEVPostIncRewriter::rewrite(S, L, *this);
10226 assert(PostInc != getCouldNotCompute() && "Unexpected could not compute")(static_cast <bool> (PostInc != getCouldNotCompute() &&
"Unexpected could not compute") ? void (0) : __assert_fail (
"PostInc != getCouldNotCompute() && \"Unexpected could not compute\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10226, __extension__
__PRETTY_FUNCTION__));
10227 return { Start, PostInc };
10228}
10229
10230bool ScalarEvolution::isKnownViaInduction(ICmpInst::Predicate Pred,
10231 const SCEV *LHS, const SCEV *RHS) {
10232 // First collect all loops.
10233 SmallPtrSet<const Loop *, 8> LoopsUsed;
10234 getUsedLoops(LHS, LoopsUsed);
10235 getUsedLoops(RHS, LoopsUsed);
10236
10237 if (LoopsUsed.empty())
10238 return false;
10239
10240 // Domination relationship must be a linear order on collected loops.
10241#ifndef NDEBUG
10242 for (auto *L1 : LoopsUsed)
10243 for (auto *L2 : LoopsUsed)
10244 assert((DT.dominates(L1->getHeader(), L2->getHeader()) ||(static_cast <bool> ((DT.dominates(L1->getHeader(), L2
->getHeader()) || DT.dominates(L2->getHeader(), L1->
getHeader())) && "Domination relationship is not a linear order"
) ? void (0) : __assert_fail ("(DT.dominates(L1->getHeader(), L2->getHeader()) || DT.dominates(L2->getHeader(), L1->getHeader())) && \"Domination relationship is not a linear order\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10246, __extension__
__PRETTY_FUNCTION__))
10245 DT.dominates(L2->getHeader(), L1->getHeader())) &&(static_cast <bool> ((DT.dominates(L1->getHeader(), L2
->getHeader()) || DT.dominates(L2->getHeader(), L1->
getHeader())) && "Domination relationship is not a linear order"
) ? void (0) : __assert_fail ("(DT.dominates(L1->getHeader(), L2->getHeader()) || DT.dominates(L2->getHeader(), L1->getHeader())) && \"Domination relationship is not a linear order\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10246, __extension__
__PRETTY_FUNCTION__))
10246 "Domination relationship is not a linear order")(static_cast <bool> ((DT.dominates(L1->getHeader(), L2
->getHeader()) || DT.dominates(L2->getHeader(), L1->
getHeader())) && "Domination relationship is not a linear order"
) ? void (0) : __assert_fail ("(DT.dominates(L1->getHeader(), L2->getHeader()) || DT.dominates(L2->getHeader(), L1->getHeader())) && \"Domination relationship is not a linear order\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10246, __extension__
__PRETTY_FUNCTION__));
10247#endif
10248
10249 const Loop *MDL =
10250 *std::max_element(LoopsUsed.begin(), LoopsUsed.end(),
10251 [&](const Loop *L1, const Loop *L2) {
10252 return DT.properlyDominates(L1->getHeader(), L2->getHeader());
10253 });
10254
10255 // Get init and post increment value for LHS.
10256 auto SplitLHS = SplitIntoInitAndPostInc(MDL, LHS);
10257 // if LHS contains unknown non-invariant SCEV then bail out.
10258 if (SplitLHS.first == getCouldNotCompute())
10259 return false;
10260 assert (SplitLHS.second != getCouldNotCompute() && "Unexpected CNC")(static_cast <bool> (SplitLHS.second != getCouldNotCompute
() && "Unexpected CNC") ? void (0) : __assert_fail ("SplitLHS.second != getCouldNotCompute() && \"Unexpected CNC\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10260, __extension__
__PRETTY_FUNCTION__));
10261 // Get init and post increment value for RHS.
10262 auto SplitRHS = SplitIntoInitAndPostInc(MDL, RHS);
10263 // if RHS contains unknown non-invariant SCEV then bail out.
10264 if (SplitRHS.first == getCouldNotCompute())
10265 return false;
10266 assert (SplitRHS.second != getCouldNotCompute() && "Unexpected CNC")(static_cast <bool> (SplitRHS.second != getCouldNotCompute
() && "Unexpected CNC") ? void (0) : __assert_fail ("SplitRHS.second != getCouldNotCompute() && \"Unexpected CNC\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10266, __extension__
__PRETTY_FUNCTION__));
10267 // It is possible that init SCEV contains an invariant load but it does
10268 // not dominate MDL and is not available at MDL loop entry, so we should
10269 // check it here.
10270 if (!isAvailableAtLoopEntry(SplitLHS.first, MDL) ||
10271 !isAvailableAtLoopEntry(SplitRHS.first, MDL))
10272 return false;
10273
10274 // It seems backedge guard check is faster than entry one so in some cases
10275 // it can speed up whole estimation by short circuit
10276 return isLoopBackedgeGuardedByCond(MDL, Pred, SplitLHS.second,
10277 SplitRHS.second) &&
10278 isLoopEntryGuardedByCond(MDL, Pred, SplitLHS.first, SplitRHS.first);
10279}
10280
10281bool ScalarEvolution::isKnownPredicate(ICmpInst::Predicate Pred,
10282 const SCEV *LHS, const SCEV *RHS) {
10283 // Canonicalize the inputs first.
10284 (void)SimplifyICmpOperands(Pred, LHS, RHS);
10285
10286 if (isKnownViaInduction(Pred, LHS, RHS))
10287 return true;
10288
10289 if (isKnownPredicateViaSplitting(Pred, LHS, RHS))
10290 return true;
10291
10292 // Otherwise see what can be done with some simple reasoning.
10293 return isKnownViaNonRecursiveReasoning(Pred, LHS, RHS);
10294}
10295
10296Optional<bool> ScalarEvolution::evaluatePredicate(ICmpInst::Predicate Pred,
10297 const SCEV *LHS,
10298 const SCEV *RHS) {
10299 if (isKnownPredicate(Pred, LHS, RHS))
10300 return true;
10301 else if (isKnownPredicate(ICmpInst::getInversePredicate(Pred), LHS, RHS))
10302 return false;
10303 return None;
10304}
10305
10306bool ScalarEvolution::isKnownPredicateAt(ICmpInst::Predicate Pred,
10307 const SCEV *LHS, const SCEV *RHS,
10308 const Instruction *CtxI) {
10309 // TODO: Analyze guards and assumes from Context's block.
10310 return isKnownPredicate(Pred, LHS, RHS) ||
10311 isBasicBlockEntryGuardedByCond(CtxI->getParent(), Pred, LHS, RHS);
10312}
10313
10314Optional<bool> ScalarEvolution::evaluatePredicateAt(ICmpInst::Predicate Pred,
10315 const SCEV *LHS,
10316 const SCEV *RHS,
10317 const Instruction *CtxI) {
10318 Optional<bool> KnownWithoutContext = evaluatePredicate(Pred, LHS, RHS);
10319 if (KnownWithoutContext)
10320 return KnownWithoutContext;
10321
10322 if (isBasicBlockEntryGuardedByCond(CtxI->getParent(), Pred, LHS, RHS))
10323 return true;
10324 else if (isBasicBlockEntryGuardedByCond(CtxI->getParent(),
10325 ICmpInst::getInversePredicate(Pred),
10326 LHS, RHS))
10327 return false;
10328 return None;
10329}
10330
10331bool ScalarEvolution::isKnownOnEveryIteration(ICmpInst::Predicate Pred,
10332 const SCEVAddRecExpr *LHS,
10333 const SCEV *RHS) {
10334 const Loop *L = LHS->getLoop();
10335 return isLoopEntryGuardedByCond(L, Pred, LHS->getStart(), RHS) &&
10336 isLoopBackedgeGuardedByCond(L, Pred, LHS->getPostIncExpr(*this), RHS);
10337}
10338
10339Optional<ScalarEvolution::MonotonicPredicateType>
10340ScalarEvolution::getMonotonicPredicateType(const SCEVAddRecExpr *LHS,
10341 ICmpInst::Predicate Pred) {
10342 auto Result = getMonotonicPredicateTypeImpl(LHS, Pred);
10343
10344#ifndef NDEBUG
10345 // Verify an invariant: inverting the predicate should turn a monotonically
10346 // increasing change to a monotonically decreasing one, and vice versa.
10347 if (Result) {
10348 auto ResultSwapped =
10349 getMonotonicPredicateTypeImpl(LHS, ICmpInst::getSwappedPredicate(Pred));
10350
10351 assert(ResultSwapped.hasValue() && "should be able to analyze both!")(static_cast <bool> (ResultSwapped.hasValue() &&
"should be able to analyze both!") ? void (0) : __assert_fail
("ResultSwapped.hasValue() && \"should be able to analyze both!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10351, __extension__
__PRETTY_FUNCTION__));
10352 assert(ResultSwapped.getValue() != Result.getValue() &&(static_cast <bool> (ResultSwapped.getValue() != Result
.getValue() && "monotonicity should flip as we flip the predicate"
) ? void (0) : __assert_fail ("ResultSwapped.getValue() != Result.getValue() && \"monotonicity should flip as we flip the predicate\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10353, __extension__
__PRETTY_FUNCTION__))
10353 "monotonicity should flip as we flip the predicate")(static_cast <bool> (ResultSwapped.getValue() != Result
.getValue() && "monotonicity should flip as we flip the predicate"
) ? void (0) : __assert_fail ("ResultSwapped.getValue() != Result.getValue() && \"monotonicity should flip as we flip the predicate\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10353, __extension__
__PRETTY_FUNCTION__));
10354 }
10355#endif
10356
10357 return Result;
10358}
10359
10360Optional<ScalarEvolution::MonotonicPredicateType>
10361ScalarEvolution::getMonotonicPredicateTypeImpl(const SCEVAddRecExpr *LHS,
10362 ICmpInst::Predicate Pred) {
10363 // A zero step value for LHS means the induction variable is essentially a
10364 // loop invariant value. We don't really depend on the predicate actually
10365 // flipping from false to true (for increasing predicates, and the other way
10366 // around for decreasing predicates), all we care about is that *if* the
10367 // predicate changes then it only changes from false to true.
10368 //
10369 // A zero step value in itself is not very useful, but there may be places
10370 // where SCEV can prove X >= 0 but not prove X > 0, so it is helpful to be
10371 // as general as possible.
10372
10373 // Only handle LE/LT/GE/GT predicates.
10374 if (!ICmpInst::isRelational(Pred))
10375 return None;
10376
10377 bool IsGreater = ICmpInst::isGE(Pred) || ICmpInst::isGT(Pred);
10378 assert((IsGreater || ICmpInst::isLE(Pred) || ICmpInst::isLT(Pred)) &&(static_cast <bool> ((IsGreater || ICmpInst::isLE(Pred)
|| ICmpInst::isLT(Pred)) && "Should be greater or less!"
) ? void (0) : __assert_fail ("(IsGreater || ICmpInst::isLE(Pred) || ICmpInst::isLT(Pred)) && \"Should be greater or less!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10379, __extension__
__PRETTY_FUNCTION__))
10379 "Should be greater or less!")(static_cast <bool> ((IsGreater || ICmpInst::isLE(Pred)
|| ICmpInst::isLT(Pred)) && "Should be greater or less!"
) ? void (0) : __assert_fail ("(IsGreater || ICmpInst::isLE(Pred) || ICmpInst::isLT(Pred)) && \"Should be greater or less!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10379, __extension__
__PRETTY_FUNCTION__));
10380
10381 // Check that AR does not wrap.
10382 if (ICmpInst::isUnsigned(Pred)) {
10383 if (!LHS->hasNoUnsignedWrap())
10384 return None;
10385 return IsGreater ? MonotonicallyIncreasing : MonotonicallyDecreasing;
10386 } else {
10387 assert(ICmpInst::isSigned(Pred) &&(static_cast <bool> (ICmpInst::isSigned(Pred) &&
"Relational predicate is either signed or unsigned!") ? void
(0) : __assert_fail ("ICmpInst::isSigned(Pred) && \"Relational predicate is either signed or unsigned!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10388, __extension__
__PRETTY_FUNCTION__))
10388 "Relational predicate is either signed or unsigned!")(static_cast <bool> (ICmpInst::isSigned(Pred) &&
"Relational predicate is either signed or unsigned!") ? void
(0) : __assert_fail ("ICmpInst::isSigned(Pred) && \"Relational predicate is either signed or unsigned!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10388, __extension__
__PRETTY_FUNCTION__));
10389 if (!LHS->hasNoSignedWrap())
10390 return None;
10391
10392 const SCEV *Step = LHS->getStepRecurrence(*this);
10393
10394 if (isKnownNonNegative(Step))
10395 return IsGreater ? MonotonicallyIncreasing : MonotonicallyDecreasing;
10396
10397 if (isKnownNonPositive(Step))
10398 return !IsGreater ? MonotonicallyIncreasing : MonotonicallyDecreasing;
10399
10400 return None;
10401 }
10402}
10403
10404Optional<ScalarEvolution::LoopInvariantPredicate>
10405ScalarEvolution::getLoopInvariantPredicate(ICmpInst::Predicate Pred,
10406 const SCEV *LHS, const SCEV *RHS,
10407 const Loop *L) {
10408
10409 // If there is a loop-invariant, force it into the RHS, otherwise bail out.
10410 if (!isLoopInvariant(RHS, L)) {
10411 if (!isLoopInvariant(LHS, L))
10412 return None;
10413
10414 std::swap(LHS, RHS);
10415 Pred = ICmpInst::getSwappedPredicate(Pred);
10416 }
10417
10418 const SCEVAddRecExpr *ArLHS = dyn_cast<SCEVAddRecExpr>(LHS);
10419 if (!ArLHS || ArLHS->getLoop() != L)
10420 return None;
10421
10422 auto MonotonicType = getMonotonicPredicateType(ArLHS, Pred);
10423 if (!MonotonicType)
10424 return None;
10425 // If the predicate "ArLHS `Pred` RHS" monotonically increases from false to
10426 // true as the loop iterates, and the backedge is control dependent on
10427 // "ArLHS `Pred` RHS" == true then we can reason as follows:
10428 //
10429 // * if the predicate was false in the first iteration then the predicate
10430 // is never evaluated again, since the loop exits without taking the
10431 // backedge.
10432 // * if the predicate was true in the first iteration then it will
10433 // continue to be true for all future iterations since it is
10434 // monotonically increasing.
10435 //
10436 // For both the above possibilities, we can replace the loop varying
10437 // predicate with its value on the first iteration of the loop (which is
10438 // loop invariant).
10439 //
10440 // A similar reasoning applies for a monotonically decreasing predicate, by
10441 // replacing true with false and false with true in the above two bullets.
10442 bool Increasing = *MonotonicType == ScalarEvolution::MonotonicallyIncreasing;
10443 auto P = Increasing ? Pred : ICmpInst::getInversePredicate(Pred);
10444
10445 if (!isLoopBackedgeGuardedByCond(L, P, LHS, RHS))
10446 return None;
10447
10448 return ScalarEvolution::LoopInvariantPredicate(Pred, ArLHS->getStart(), RHS);
10449}
10450
10451Optional<ScalarEvolution::LoopInvariantPredicate>
10452ScalarEvolution::getLoopInvariantExitCondDuringFirstIterations(
10453 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS, const Loop *L,
10454 const Instruction *CtxI, const SCEV *MaxIter) {
10455 // Try to prove the following set of facts:
10456 // - The predicate is monotonic in the iteration space.
10457 // - If the check does not fail on the 1st iteration:
10458 // - No overflow will happen during first MaxIter iterations;
10459 // - It will not fail on the MaxIter'th iteration.
10460 // If the check does fail on the 1st iteration, we leave the loop and no
10461 // other checks matter.
10462
10463 // If there is a loop-invariant, force it into the RHS, otherwise bail out.
10464 if (!isLoopInvariant(RHS, L)) {
10465 if (!isLoopInvariant(LHS, L))
10466 return None;
10467
10468 std::swap(LHS, RHS);
10469 Pred = ICmpInst::getSwappedPredicate(Pred);
10470 }
10471
10472 auto *AR = dyn_cast<SCEVAddRecExpr>(LHS);
10473 if (!AR || AR->getLoop() != L)
10474 return None;
10475
10476 // The predicate must be relational (i.e. <, <=, >=, >).
10477 if (!ICmpInst::isRelational(Pred))
10478 return None;
10479
10480 // TODO: Support steps other than +/- 1.
10481 const SCEV *Step = AR->getStepRecurrence(*this);
10482 auto *One = getOne(Step->getType());
10483 auto *MinusOne = getNegativeSCEV(One);
10484 if (Step != One && Step != MinusOne)
10485 return None;
10486
10487 // Type mismatch here means that MaxIter is potentially larger than max
10488 // unsigned value in start type, which mean we cannot prove no wrap for the
10489 // indvar.
10490 if (AR->getType() != MaxIter->getType())
10491 return None;
10492
10493 // Value of IV on suggested last iteration.
10494 const SCEV *Last = AR->evaluateAtIteration(MaxIter, *this);
10495 // Does it still meet the requirement?
10496 if (!isLoopBackedgeGuardedByCond(L, Pred, Last, RHS))
10497 return None;
10498 // Because step is +/- 1 and MaxIter has same type as Start (i.e. it does
10499 // not exceed max unsigned value of this type), this effectively proves
10500 // that there is no wrap during the iteration. To prove that there is no
10501 // signed/unsigned wrap, we need to check that
10502 // Start <= Last for step = 1 or Start >= Last for step = -1.
10503 ICmpInst::Predicate NoOverflowPred =
10504 CmpInst::isSigned(Pred) ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
10505 if (Step == MinusOne)
10506 NoOverflowPred = CmpInst::getSwappedPredicate(NoOverflowPred);
10507 const SCEV *Start = AR->getStart();
10508 if (!isKnownPredicateAt(NoOverflowPred, Start, Last, CtxI))
10509 return None;
10510
10511 // Everything is fine.
10512 return ScalarEvolution::LoopInvariantPredicate(Pred, Start, RHS);
10513}
10514
10515bool ScalarEvolution::isKnownPredicateViaConstantRanges(
10516 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS) {
10517 if (HasSameValue(LHS, RHS))
10518 return ICmpInst::isTrueWhenEqual(Pred);
10519
10520 // This code is split out from isKnownPredicate because it is called from
10521 // within isLoopEntryGuardedByCond.
10522
10523 auto CheckRanges = [&](const ConstantRange &RangeLHS,
10524 const ConstantRange &RangeRHS) {
10525 return RangeLHS.icmp(Pred, RangeRHS);
10526 };
10527
10528 // The check at the top of the function catches the case where the values are
10529 // known to be equal.
10530 if (Pred == CmpInst::ICMP_EQ)
10531 return false;
10532
10533 if (Pred == CmpInst::ICMP_NE) {
10534 if (CheckRanges(getSignedRange(LHS), getSignedRange(RHS)) ||
10535 CheckRanges(getUnsignedRange(LHS), getUnsignedRange(RHS)))
10536 return true;
10537 auto *Diff = getMinusSCEV(LHS, RHS);
10538 return !isa<SCEVCouldNotCompute>(Diff) && isKnownNonZero(Diff);
10539 }
10540
10541 if (CmpInst::isSigned(Pred))
10542 return CheckRanges(getSignedRange(LHS), getSignedRange(RHS));
10543
10544 return CheckRanges(getUnsignedRange(LHS), getUnsignedRange(RHS));
10545}
10546
10547bool ScalarEvolution::isKnownPredicateViaNoOverflow(ICmpInst::Predicate Pred,
10548 const SCEV *LHS,
10549 const SCEV *RHS) {
10550 // Match X to (A + C1)<ExpectedFlags> and Y to (A + C2)<ExpectedFlags>, where
10551 // C1 and C2 are constant integers. If either X or Y are not add expressions,
10552 // consider them as X + 0 and Y + 0 respectively. C1 and C2 are returned via
10553 // OutC1 and OutC2.
10554 auto MatchBinaryAddToConst = [this](const SCEV *X, const SCEV *Y,
10555 APInt &OutC1, APInt &OutC2,
10556 SCEV::NoWrapFlags ExpectedFlags) {
10557 const SCEV *XNonConstOp, *XConstOp;
10558 const SCEV *YNonConstOp, *YConstOp;
10559 SCEV::NoWrapFlags XFlagsPresent;
10560 SCEV::NoWrapFlags YFlagsPresent;
10561
10562 if (!splitBinaryAdd(X, XConstOp, XNonConstOp, XFlagsPresent)) {
10563 XConstOp = getZero(X->getType());
10564 XNonConstOp = X;
10565 XFlagsPresent = ExpectedFlags;
10566 }
10567 if (!isa<SCEVConstant>(XConstOp) ||
10568 (XFlagsPresent & ExpectedFlags) != ExpectedFlags)
10569 return false;
10570
10571 if (!splitBinaryAdd(Y, YConstOp, YNonConstOp, YFlagsPresent)) {
10572 YConstOp = getZero(Y->getType());
10573 YNonConstOp = Y;
10574 YFlagsPresent = ExpectedFlags;
10575 }
10576
10577 if (!isa<SCEVConstant>(YConstOp) ||
10578 (YFlagsPresent & ExpectedFlags) != ExpectedFlags)
10579 return false;
10580
10581 if (YNonConstOp != XNonConstOp)
10582 return false;
10583
10584 OutC1 = cast<SCEVConstant>(XConstOp)->getAPInt();
10585 OutC2 = cast<SCEVConstant>(YConstOp)->getAPInt();
10586
10587 return true;
10588 };
10589
10590 APInt C1;
10591 APInt C2;
10592
10593 switch (Pred) {
10594 default:
10595 break;
10596
10597 case ICmpInst::ICMP_SGE:
10598 std::swap(LHS, RHS);
10599 LLVM_FALLTHROUGH[[gnu::fallthrough]];
10600 case ICmpInst::ICMP_SLE:
10601 // (X + C1)<nsw> s<= (X + C2)<nsw> if C1 s<= C2.
10602 if (MatchBinaryAddToConst(LHS, RHS, C1, C2, SCEV::FlagNSW) && C1.sle(C2))
10603 return true;
10604
10605 break;
10606
10607 case ICmpInst::ICMP_SGT:
10608 std::swap(LHS, RHS);
10609 LLVM_FALLTHROUGH[[gnu::fallthrough]];
10610 case ICmpInst::ICMP_SLT:
10611 // (X + C1)<nsw> s< (X + C2)<nsw> if C1 s< C2.
10612 if (MatchBinaryAddToConst(LHS, RHS, C1, C2, SCEV::FlagNSW) && C1.slt(C2))
10613 return true;
10614
10615 break;
10616
10617 case ICmpInst::ICMP_UGE:
10618 std::swap(LHS, RHS);
10619 LLVM_FALLTHROUGH[[gnu::fallthrough]];
10620 case ICmpInst::ICMP_ULE:
10621 // (X + C1)<nuw> u<= (X + C2)<nuw> for C1 u<= C2.
10622 if (MatchBinaryAddToConst(RHS, LHS, C2, C1, SCEV::FlagNUW) && C1.ule(C2))
10623 return true;
10624
10625 break;
10626
10627 case ICmpInst::ICMP_UGT:
10628 std::swap(LHS, RHS);
10629 LLVM_FALLTHROUGH[[gnu::fallthrough]];
10630 case ICmpInst::ICMP_ULT:
10631 // (X + C1)<nuw> u< (X + C2)<nuw> if C1 u< C2.
10632 if (MatchBinaryAddToConst(RHS, LHS, C2, C1, SCEV::FlagNUW) && C1.ult(C2))
10633 return true;
10634 break;
10635 }
10636
10637 return false;
10638}
10639
10640bool ScalarEvolution::isKnownPredicateViaSplitting(ICmpInst::Predicate Pred,
10641 const SCEV *LHS,
10642 const SCEV *RHS) {
10643 if (Pred != ICmpInst::ICMP_ULT || ProvingSplitPredicate)
10644 return false;
10645
10646 // Allowing arbitrary number of activations of isKnownPredicateViaSplitting on
10647 // the stack can result in exponential time complexity.
10648 SaveAndRestore<bool> Restore(ProvingSplitPredicate, true);
10649
10650 // If L >= 0 then I `ult` L <=> I >= 0 && I `slt` L
10651 //
10652 // To prove L >= 0 we use isKnownNonNegative whereas to prove I >= 0 we use
10653 // isKnownPredicate. isKnownPredicate is more powerful, but also more
10654 // expensive; and using isKnownNonNegative(RHS) is sufficient for most of the
10655 // interesting cases seen in practice. We can consider "upgrading" L >= 0 to
10656 // use isKnownPredicate later if needed.
10657 return isKnownNonNegative(RHS) &&
10658 isKnownPredicate(CmpInst::ICMP_SGE, LHS, getZero(LHS->getType())) &&
10659 isKnownPredicate(CmpInst::ICMP_SLT, LHS, RHS);
10660}
10661
10662bool ScalarEvolution::isImpliedViaGuard(const BasicBlock *BB,
10663 ICmpInst::Predicate Pred,
10664 const SCEV *LHS, const SCEV *RHS) {
10665 // No need to even try if we know the module has no guards.
10666 if (!HasGuards)
10667 return false;
10668
10669 return any_of(*BB, [&](const Instruction &I) {
10670 using namespace llvm::PatternMatch;
10671
10672 Value *Condition;
10673 return match(&I, m_Intrinsic<Intrinsic::experimental_guard>(
10674 m_Value(Condition))) &&
10675 isImpliedCond(Pred, LHS, RHS, Condition, false);
10676 });
10677}
10678
10679/// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is
10680/// protected by a conditional between LHS and RHS. This is used to
10681/// to eliminate casts.
10682bool
10683ScalarEvolution::isLoopBackedgeGuardedByCond(const Loop *L,
10684 ICmpInst::Predicate Pred,
10685 const SCEV *LHS, const SCEV *RHS) {
10686 // Interpret a null as meaning no loop, where there is obviously no guard
10687 // (interprocedural conditions notwithstanding).
10688 if (!L) return true;
10689
10690 if (VerifyIR)
10691 assert(!verifyFunction(*L->getHeader()->getParent(), &dbgs()) &&(static_cast <bool> (!verifyFunction(*L->getHeader()
->getParent(), &dbgs()) && "This cannot be done on broken IR!"
) ? void (0) : __assert_fail ("!verifyFunction(*L->getHeader()->getParent(), &dbgs()) && \"This cannot be done on broken IR!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10692, __extension__
__PRETTY_FUNCTION__))
10692 "This cannot be done on broken IR!")(static_cast <bool> (!verifyFunction(*L->getHeader()
->getParent(), &dbgs()) && "This cannot be done on broken IR!"
) ? void (0) : __assert_fail ("!verifyFunction(*L->getHeader()->getParent(), &dbgs()) && \"This cannot be done on broken IR!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10692, __extension__
__PRETTY_FUNCTION__));
10693
10694
10695 if (isKnownViaNonRecursiveReasoning(Pred, LHS, RHS))
10696 return true;
10697
10698 BasicBlock *Latch = L->getLoopLatch();
10699 if (!Latch)
10700 return false;
10701
10702 BranchInst *LoopContinuePredicate =
10703 dyn_cast<BranchInst>(Latch->getTerminator());
10704 if (LoopContinuePredicate && LoopContinuePredicate->isConditional() &&
10705 isImpliedCond(Pred, LHS, RHS,
10706 LoopContinuePredicate->getCondition(),
10707 LoopContinuePredicate->getSuccessor(0) != L->getHeader()))
10708 return true;
10709
10710 // We don't want more than one activation of the following loops on the stack
10711 // -- that can lead to O(n!) time complexity.
10712 if (WalkingBEDominatingConds)
10713 return false;
10714
10715 SaveAndRestore<bool> ClearOnExit(WalkingBEDominatingConds, true);
10716
10717 // See if we can exploit a trip count to prove the predicate.
10718 const auto &BETakenInfo = getBackedgeTakenInfo(L);
10719 const SCEV *LatchBECount = BETakenInfo.getExact(Latch, this);
10720 if (LatchBECount != getCouldNotCompute()) {
10721 // We know that Latch branches back to the loop header exactly
10722 // LatchBECount times. This means the backdege condition at Latch is
10723 // equivalent to "{0,+,1} u< LatchBECount".
10724 Type *Ty = LatchBECount->getType();
10725 auto NoWrapFlags = SCEV::NoWrapFlags(SCEV::FlagNUW | SCEV::FlagNW);
10726 const SCEV *LoopCounter =
10727 getAddRecExpr(getZero(Ty), getOne(Ty), L, NoWrapFlags);
10728 if (isImpliedCond(Pred, LHS, RHS, ICmpInst::ICMP_ULT, LoopCounter,
10729 LatchBECount))
10730 return true;
10731 }
10732
10733 // Check conditions due to any @llvm.assume intrinsics.
10734 for (auto &AssumeVH : AC.assumptions()) {
10735 if (!AssumeVH)
10736 continue;
10737 auto *CI = cast<CallInst>(AssumeVH);
10738 if (!DT.dominates(CI, Latch->getTerminator()))
10739 continue;
10740
10741 if (isImpliedCond(Pred, LHS, RHS, CI->getArgOperand(0), false))
10742 return true;
10743 }
10744
10745 // If the loop is not reachable from the entry block, we risk running into an
10746 // infinite loop as we walk up into the dom tree. These loops do not matter
10747 // anyway, so we just return a conservative answer when we see them.
10748 if (!DT.isReachableFromEntry(L->getHeader()))
10749 return false;
10750
10751 if (isImpliedViaGuard(Latch, Pred, LHS, RHS))
10752 return true;
10753
10754 for (DomTreeNode *DTN = DT[Latch], *HeaderDTN = DT[L->getHeader()];
10755 DTN != HeaderDTN; DTN = DTN->getIDom()) {
10756 assert(DTN && "should reach the loop header before reaching the root!")(static_cast <bool> (DTN && "should reach the loop header before reaching the root!"
) ? void (0) : __assert_fail ("DTN && \"should reach the loop header before reaching the root!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10756, __extension__
__PRETTY_FUNCTION__));
10757
10758 BasicBlock *BB = DTN->getBlock();
10759 if (isImpliedViaGuard(BB, Pred, LHS, RHS))
10760 return true;
10761
10762 BasicBlock *PBB = BB->getSinglePredecessor();
10763 if (!PBB)
10764 continue;
10765
10766 BranchInst *ContinuePredicate = dyn_cast<BranchInst>(PBB->getTerminator());
10767 if (!ContinuePredicate || !ContinuePredicate->isConditional())
10768 continue;
10769
10770 Value *Condition = ContinuePredicate->getCondition();
10771
10772 // If we have an edge `E` within the loop body that dominates the only
10773 // latch, the condition guarding `E` also guards the backedge. This
10774 // reasoning works only for loops with a single latch.
10775
10776 BasicBlockEdge DominatingEdge(PBB, BB);
10777 if (DominatingEdge.isSingleEdge()) {
10778 // We're constructively (and conservatively) enumerating edges within the
10779 // loop body that dominate the latch. The dominator tree better agree
10780 // with us on this:
10781 assert(DT.dominates(DominatingEdge, Latch) && "should be!")(static_cast <bool> (DT.dominates(DominatingEdge, Latch
) && "should be!") ? void (0) : __assert_fail ("DT.dominates(DominatingEdge, Latch) && \"should be!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10781, __extension__
__PRETTY_FUNCTION__));
10782
10783 if (isImpliedCond(Pred, LHS, RHS, Condition,
10784 BB != ContinuePredicate->getSuccessor(0)))
10785 return true;
10786 }
10787 }
10788
10789 return false;
10790}
10791
10792bool ScalarEvolution::isBasicBlockEntryGuardedByCond(const BasicBlock *BB,
10793 ICmpInst::Predicate Pred,
10794 const SCEV *LHS,
10795 const SCEV *RHS) {
10796 if (VerifyIR)
10797 assert(!verifyFunction(*BB->getParent(), &dbgs()) &&(static_cast <bool> (!verifyFunction(*BB->getParent(
), &dbgs()) && "This cannot be done on broken IR!"
) ? void (0) : __assert_fail ("!verifyFunction(*BB->getParent(), &dbgs()) && \"This cannot be done on broken IR!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10798, __extension__
__PRETTY_FUNCTION__))
10798 "This cannot be done on broken IR!")(static_cast <bool> (!verifyFunction(*BB->getParent(
), &dbgs()) && "This cannot be done on broken IR!"
) ? void (0) : __assert_fail ("!verifyFunction(*BB->getParent(), &dbgs()) && \"This cannot be done on broken IR!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10798, __extension__
__PRETTY_FUNCTION__));
10799
10800 // If we cannot prove strict comparison (e.g. a > b), maybe we can prove
10801 // the facts (a >= b && a != b) separately. A typical situation is when the
10802 // non-strict comparison is known from ranges and non-equality is known from
10803 // dominating predicates. If we are proving strict comparison, we always try
10804 // to prove non-equality and non-strict comparison separately.
10805 auto NonStrictPredicate = ICmpInst::getNonStrictPredicate(Pred);
10806 const bool ProvingStrictComparison = (Pred != NonStrictPredicate);
10807 bool ProvedNonStrictComparison = false;
10808 bool ProvedNonEquality = false;
10809
10810 auto SplitAndProve =
10811 [&](std::function<bool(ICmpInst::Predicate)> Fn) -> bool {
10812 if (!ProvedNonStrictComparison)
10813 ProvedNonStrictComparison = Fn(NonStrictPredicate);
10814 if (!ProvedNonEquality)
10815 ProvedNonEquality = Fn(ICmpInst::ICMP_NE);
10816 if (ProvedNonStrictComparison && ProvedNonEquality)
10817 return true;
10818 return false;
10819 };
10820
10821 if (ProvingStrictComparison) {
10822 auto ProofFn = [&](ICmpInst::Predicate P) {
10823 return isKnownViaNonRecursiveReasoning(P, LHS, RHS);
10824 };
10825 if (SplitAndProve(ProofFn))
10826 return true;
10827 }
10828
10829 // Try to prove (Pred, LHS, RHS) using isImpliedViaGuard.
10830 auto ProveViaGuard = [&](const BasicBlock *Block) {
10831 if (isImpliedViaGuard(Block, Pred, LHS, RHS))
10832 return true;
10833 if (ProvingStrictComparison) {
10834 auto ProofFn = [&](ICmpInst::Predicate P) {
10835 return isImpliedViaGuard(Block, P, LHS, RHS);
10836 };
10837 if (SplitAndProve(ProofFn))
10838 return true;
10839 }
10840 return false;
10841 };
10842
10843 // Try to prove (Pred, LHS, RHS) using isImpliedCond.
10844 auto ProveViaCond = [&](const Value *Condition, bool Inverse) {
10845 const Instruction *CtxI = &BB->front();
10846 if (isImpliedCond(Pred, LHS, RHS, Condition, Inverse, CtxI))
10847 return true;
10848 if (ProvingStrictComparison) {
10849 auto ProofFn = [&](ICmpInst::Predicate P) {
10850 return isImpliedCond(P, LHS, RHS, Condition, Inverse, CtxI);
10851 };
10852 if (SplitAndProve(ProofFn))
10853 return true;
10854 }
10855 return false;
10856 };
10857
10858 // Starting at the block's predecessor, climb up the predecessor chain, as long
10859 // as there are predecessors that can be found that have unique successors
10860 // leading to the original block.
10861 const Loop *ContainingLoop = LI.getLoopFor(BB);
10862 const BasicBlock *PredBB;
10863 if (ContainingLoop && ContainingLoop->getHeader() == BB)
10864 PredBB = ContainingLoop->getLoopPredecessor();
10865 else
10866 PredBB = BB->getSinglePredecessor();
10867 for (std::pair<const BasicBlock *, const BasicBlock *> Pair(PredBB, BB);
10868 Pair.first; Pair = getPredecessorWithUniqueSuccessorForBB(Pair.first)) {
10869 if (ProveViaGuard(Pair.first))
10870 return true;
10871
10872 const BranchInst *LoopEntryPredicate =
10873 dyn_cast<BranchInst>(Pair.first->getTerminator());
10874 if (!LoopEntryPredicate ||
10875 LoopEntryPredicate->isUnconditional())
10876 continue;
10877
10878 if (ProveViaCond(LoopEntryPredicate->getCondition(),
10879 LoopEntryPredicate->getSuccessor(0) != Pair.second))
10880 return true;
10881 }
10882
10883 // Check conditions due to any @llvm.assume intrinsics.
10884 for (auto &AssumeVH : AC.assumptions()) {
10885 if (!AssumeVH)
10886 continue;
10887 auto *CI = cast<CallInst>(AssumeVH);
10888 if (!DT.dominates(CI, BB))
10889 continue;
10890
10891 if (ProveViaCond(CI->getArgOperand(0), false))
10892 return true;
10893 }
10894
10895 return false;
10896}
10897
10898bool ScalarEvolution::isLoopEntryGuardedByCond(const Loop *L,
10899 ICmpInst::Predicate Pred,
10900 const SCEV *LHS,
10901 const SCEV *RHS) {
10902 // Interpret a null as meaning no loop, where there is obviously no guard
10903 // (interprocedural conditions notwithstanding).
10904 if (!L)
10905 return false;
10906
10907 // Both LHS and RHS must be available at loop entry.
10908 assert(isAvailableAtLoopEntry(LHS, L) &&(static_cast <bool> (isAvailableAtLoopEntry(LHS, L) &&
"LHS is not available at Loop Entry") ? void (0) : __assert_fail
("isAvailableAtLoopEntry(LHS, L) && \"LHS is not available at Loop Entry\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10909, __extension__
__PRETTY_FUNCTION__))
10909 "LHS is not available at Loop Entry")(static_cast <bool> (isAvailableAtLoopEntry(LHS, L) &&
"LHS is not available at Loop Entry") ? void (0) : __assert_fail
("isAvailableAtLoopEntry(LHS, L) && \"LHS is not available at Loop Entry\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10909, __extension__
__PRETTY_FUNCTION__));
10910 assert(isAvailableAtLoopEntry(RHS, L) &&(static_cast <bool> (isAvailableAtLoopEntry(RHS, L) &&
"RHS is not available at Loop Entry") ? void (0) : __assert_fail
("isAvailableAtLoopEntry(RHS, L) && \"RHS is not available at Loop Entry\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10911, __extension__
__PRETTY_FUNCTION__))
10911 "RHS is not available at Loop Entry")(static_cast <bool> (isAvailableAtLoopEntry(RHS, L) &&
"RHS is not available at Loop Entry") ? void (0) : __assert_fail
("isAvailableAtLoopEntry(RHS, L) && \"RHS is not available at Loop Entry\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 10911, __extension__
__PRETTY_FUNCTION__));
10912
10913 if (isKnownViaNonRecursiveReasoning(Pred, LHS, RHS))
10914 return true;
10915
10916 return isBasicBlockEntryGuardedByCond(L->getHeader(), Pred, LHS, RHS);
10917}
10918
10919bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, const SCEV *LHS,
10920 const SCEV *RHS,
10921 const Value *FoundCondValue, bool Inverse,
10922 const Instruction *CtxI) {
10923 // False conditions implies anything. Do not bother analyzing it further.
10924 if (FoundCondValue ==
10925 ConstantInt::getBool(FoundCondValue->getContext(), Inverse))
10926 return true;
10927
10928 if (!PendingLoopPredicates.insert(FoundCondValue).second)
10929 return false;
10930
10931 auto ClearOnExit =
10932 make_scope_exit([&]() { PendingLoopPredicates.erase(FoundCondValue); });
10933
10934 // Recursively handle And and Or conditions.
10935 const Value *Op0, *Op1;
10936 if (match(FoundCondValue, m_LogicalAnd(m_Value(Op0), m_Value(Op1)))) {
10937 if (!Inverse)
10938 return isImpliedCond(Pred, LHS, RHS, Op0, Inverse, CtxI) ||
10939 isImpliedCond(Pred, LHS, RHS, Op1, Inverse, CtxI);
10940 } else if (match(FoundCondValue, m_LogicalOr(m_Value(Op0), m_Value(Op1)))) {
10941 if (Inverse)
10942 return isImpliedCond(Pred, LHS, RHS, Op0, Inverse, CtxI) ||
10943 isImpliedCond(Pred, LHS, RHS, Op1, Inverse, CtxI);
10944 }
10945
10946 const ICmpInst *ICI = dyn_cast<ICmpInst>(FoundCondValue);
10947 if (!ICI) return false;
10948
10949 // Now that we found a conditional branch that dominates the loop or controls
10950 // the loop latch. Check to see if it is the comparison we are looking for.
10951 ICmpInst::Predicate FoundPred;
10952 if (Inverse)
10953 FoundPred = ICI->getInversePredicate();
10954 else
10955 FoundPred = ICI->getPredicate();
10956
10957 const SCEV *FoundLHS = getSCEV(ICI->getOperand(0));
10958 const SCEV *FoundRHS = getSCEV(ICI->getOperand(1));
10959
10960 return isImpliedCond(Pred, LHS, RHS, FoundPred, FoundLHS, FoundRHS, CtxI);
10961}
10962
10963bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, const SCEV *LHS,
10964 const SCEV *RHS,
10965 ICmpInst::Predicate FoundPred,
10966 const SCEV *FoundLHS, const SCEV *FoundRHS,
10967 const Instruction *CtxI) {
10968 // Balance the types.
10969 if (getTypeSizeInBits(LHS->getType()) <
10970 getTypeSizeInBits(FoundLHS->getType())) {
10971 // For unsigned and equality predicates, try to prove that both found
10972 // operands fit into narrow unsigned range. If so, try to prove facts in
10973 // narrow types.
10974 if (!CmpInst::isSigned(FoundPred) && !FoundLHS->getType()->isPointerTy() &&
10975 !FoundRHS->getType()->isPointerTy()) {
10976 auto *NarrowType = LHS->getType();
10977 auto *WideType = FoundLHS->getType();
10978 auto BitWidth = getTypeSizeInBits(NarrowType);
10979 const SCEV *MaxValue = getZeroExtendExpr(
10980 getConstant(APInt::getMaxValue(BitWidth)), WideType);
10981 if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_ULE, FoundLHS,
10982 MaxValue) &&
10983 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_ULE, FoundRHS,
10984 MaxValue)) {
10985 const SCEV *TruncFoundLHS = getTruncateExpr(FoundLHS, NarrowType);
10986 const SCEV *TruncFoundRHS = getTruncateExpr(FoundRHS, NarrowType);
10987 if (isImpliedCondBalancedTypes(Pred, LHS, RHS, FoundPred, TruncFoundLHS,
10988 TruncFoundRHS, CtxI))
10989 return true;
10990 }
10991 }
10992
10993 if (LHS->getType()->isPointerTy() || RHS->getType()->isPointerTy())
10994 return false;
10995 if (CmpInst::isSigned(Pred)) {
10996 LHS = getSignExtendExpr(LHS, FoundLHS->getType());
10997 RHS = getSignExtendExpr(RHS, FoundLHS->getType());
10998 } else {
10999 LHS = getZeroExtendExpr(LHS, FoundLHS->getType());
11000 RHS = getZeroExtendExpr(RHS, FoundLHS->getType());
11001 }
11002 } else if (getTypeSizeInBits(LHS->getType()) >
11003 getTypeSizeInBits(FoundLHS->getType())) {
11004 if (FoundLHS->getType()->isPointerTy() || FoundRHS->getType()->isPointerTy())
11005 return false;
11006 if (CmpInst::isSigned(FoundPred)) {
11007 FoundLHS = getSignExtendExpr(FoundLHS, LHS->getType());
11008 FoundRHS = getSignExtendExpr(FoundRHS, LHS->getType());
11009 } else {
11010 FoundLHS = getZeroExtendExpr(FoundLHS, LHS->getType());
11011 FoundRHS = getZeroExtendExpr(FoundRHS, LHS->getType());
11012 }
11013 }
11014 return isImpliedCondBalancedTypes(Pred, LHS, RHS, FoundPred, FoundLHS,
11015 FoundRHS, CtxI);
11016}
11017
11018bool ScalarEvolution::isImpliedCondBalancedTypes(
11019 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS,
11020 ICmpInst::Predicate FoundPred, const SCEV *FoundLHS, const SCEV *FoundRHS,
11021 const Instruction *CtxI) {
11022 assert(getTypeSizeInBits(LHS->getType()) ==(static_cast <bool> (getTypeSizeInBits(LHS->getType(
)) == getTypeSizeInBits(FoundLHS->getType()) && "Types should be balanced!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(FoundLHS->getType()) && \"Types should be balanced!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11024, __extension__
__PRETTY_FUNCTION__))
11023 getTypeSizeInBits(FoundLHS->getType()) &&(static_cast <bool> (getTypeSizeInBits(LHS->getType(
)) == getTypeSizeInBits(FoundLHS->getType()) && "Types should be balanced!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(FoundLHS->getType()) && \"Types should be balanced!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11024, __extension__
__PRETTY_FUNCTION__))
11024 "Types should be balanced!")(static_cast <bool> (getTypeSizeInBits(LHS->getType(
)) == getTypeSizeInBits(FoundLHS->getType()) && "Types should be balanced!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(FoundLHS->getType()) && \"Types should be balanced!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11024, __extension__
__PRETTY_FUNCTION__));
11025 // Canonicalize the query to match the way instcombine will have
11026 // canonicalized the comparison.
11027 if (SimplifyICmpOperands(Pred, LHS, RHS))
11028 if (LHS == RHS)
11029 return CmpInst::isTrueWhenEqual(Pred);
11030 if (SimplifyICmpOperands(FoundPred, FoundLHS, FoundRHS))
11031 if (FoundLHS == FoundRHS)
11032 return CmpInst::isFalseWhenEqual(FoundPred);
11033
11034 // Check to see if we can make the LHS or RHS match.
11035 if (LHS == FoundRHS || RHS == FoundLHS) {
11036 if (isa<SCEVConstant>(RHS)) {
11037 std::swap(FoundLHS, FoundRHS);
11038 FoundPred = ICmpInst::getSwappedPredicate(FoundPred);
11039 } else {
11040 std::swap(LHS, RHS);
11041 Pred = ICmpInst::getSwappedPredicate(Pred);
11042 }
11043 }
11044
11045 // Check whether the found predicate is the same as the desired predicate.
11046 if (FoundPred == Pred)
11047 return isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS, CtxI);
11048
11049 // Check whether swapping the found predicate makes it the same as the
11050 // desired predicate.
11051 if (ICmpInst::getSwappedPredicate(FoundPred) == Pred) {
11052 // We can write the implication
11053 // 0. LHS Pred RHS <- FoundLHS SwapPred FoundRHS
11054 // using one of the following ways:
11055 // 1. LHS Pred RHS <- FoundRHS Pred FoundLHS
11056 // 2. RHS SwapPred LHS <- FoundLHS SwapPred FoundRHS
11057 // 3. LHS Pred RHS <- ~FoundLHS Pred ~FoundRHS
11058 // 4. ~LHS SwapPred ~RHS <- FoundLHS SwapPred FoundRHS
11059 // Forms 1. and 2. require swapping the operands of one condition. Don't
11060 // do this if it would break canonical constant/addrec ordering.
11061 if (!isa<SCEVConstant>(RHS) && !isa<SCEVAddRecExpr>(LHS))
11062 return isImpliedCondOperands(FoundPred, RHS, LHS, FoundLHS, FoundRHS,
11063 CtxI);
11064 if (!isa<SCEVConstant>(FoundRHS) && !isa<SCEVAddRecExpr>(FoundLHS))
11065 return isImpliedCondOperands(Pred, LHS, RHS, FoundRHS, FoundLHS, CtxI);
11066
11067 // There's no clear preference between forms 3. and 4., try both. Avoid
11068 // forming getNotSCEV of pointer values as the resulting subtract is
11069 // not legal.
11070 if (!LHS->getType()->isPointerTy() && !RHS->getType()->isPointerTy() &&
11071 isImpliedCondOperands(FoundPred, getNotSCEV(LHS), getNotSCEV(RHS),
11072 FoundLHS, FoundRHS, CtxI))
11073 return true;
11074
11075 if (!FoundLHS->getType()->isPointerTy() &&
11076 !FoundRHS->getType()->isPointerTy() &&
11077 isImpliedCondOperands(Pred, LHS, RHS, getNotSCEV(FoundLHS),
11078 getNotSCEV(FoundRHS), CtxI))
11079 return true;
11080
11081 return false;
11082 }
11083
11084 auto IsSignFlippedPredicate = [](CmpInst::Predicate P1,
11085 CmpInst::Predicate P2) {
11086 assert(P1 != P2 && "Handled earlier!")(static_cast <bool> (P1 != P2 && "Handled earlier!"
) ? void (0) : __assert_fail ("P1 != P2 && \"Handled earlier!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11086, __extension__
__PRETTY_FUNCTION__));
11087 return CmpInst::isRelational(P2) &&
11088 P1 == CmpInst::getFlippedSignednessPredicate(P2);
11089 };
11090 if (IsSignFlippedPredicate(Pred, FoundPred)) {
11091 // Unsigned comparison is the same as signed comparison when both the
11092 // operands are non-negative or negative.
11093 if ((isKnownNonNegative(FoundLHS) && isKnownNonNegative(FoundRHS)) ||
11094 (isKnownNegative(FoundLHS) && isKnownNegative(FoundRHS)))
11095 return isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS, CtxI);
11096 // Create local copies that we can freely swap and canonicalize our
11097 // conditions to "le/lt".
11098 ICmpInst::Predicate CanonicalPred = Pred, CanonicalFoundPred = FoundPred;
11099 const SCEV *CanonicalLHS = LHS, *CanonicalRHS = RHS,
11100 *CanonicalFoundLHS = FoundLHS, *CanonicalFoundRHS = FoundRHS;
11101 if (ICmpInst::isGT(CanonicalPred) || ICmpInst::isGE(CanonicalPred)) {
11102 CanonicalPred = ICmpInst::getSwappedPredicate(CanonicalPred);
11103 CanonicalFoundPred = ICmpInst::getSwappedPredicate(CanonicalFoundPred);
11104 std::swap(CanonicalLHS, CanonicalRHS);
11105 std::swap(CanonicalFoundLHS, CanonicalFoundRHS);
11106 }
11107 assert((ICmpInst::isLT(CanonicalPred) || ICmpInst::isLE(CanonicalPred)) &&(static_cast <bool> ((ICmpInst::isLT(CanonicalPred) || ICmpInst
::isLE(CanonicalPred)) && "Must be!") ? void (0) : __assert_fail
("(ICmpInst::isLT(CanonicalPred) || ICmpInst::isLE(CanonicalPred)) && \"Must be!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11108, __extension__
__PRETTY_FUNCTION__))
11108 "Must be!")(static_cast <bool> ((ICmpInst::isLT(CanonicalPred) || ICmpInst
::isLE(CanonicalPred)) && "Must be!") ? void (0) : __assert_fail
("(ICmpInst::isLT(CanonicalPred) || ICmpInst::isLE(CanonicalPred)) && \"Must be!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11108, __extension__
__PRETTY_FUNCTION__));
11109 assert((ICmpInst::isLT(CanonicalFoundPred) ||(static_cast <bool> ((ICmpInst::isLT(CanonicalFoundPred
) || ICmpInst::isLE(CanonicalFoundPred)) && "Must be!"
) ? void (0) : __assert_fail ("(ICmpInst::isLT(CanonicalFoundPred) || ICmpInst::isLE(CanonicalFoundPred)) && \"Must be!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11111, __extension__
__PRETTY_FUNCTION__))
11110 ICmpInst::isLE(CanonicalFoundPred)) &&(static_cast <bool> ((ICmpInst::isLT(CanonicalFoundPred
) || ICmpInst::isLE(CanonicalFoundPred)) && "Must be!"
) ? void (0) : __assert_fail ("(ICmpInst::isLT(CanonicalFoundPred) || ICmpInst::isLE(CanonicalFoundPred)) && \"Must be!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11111, __extension__
__PRETTY_FUNCTION__))
11111 "Must be!")(static_cast <bool> ((ICmpInst::isLT(CanonicalFoundPred
) || ICmpInst::isLE(CanonicalFoundPred)) && "Must be!"
) ? void (0) : __assert_fail ("(ICmpInst::isLT(CanonicalFoundPred) || ICmpInst::isLE(CanonicalFoundPred)) && \"Must be!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11111, __extension__
__PRETTY_FUNCTION__));
11112 if (ICmpInst::isSigned(CanonicalPred) && isKnownNonNegative(CanonicalRHS))
11113 // Use implication:
11114 // x <u y && y >=s 0 --> x <s y.
11115 // If we can prove the left part, the right part is also proven.
11116 return isImpliedCondOperands(CanonicalFoundPred, CanonicalLHS,
11117 CanonicalRHS, CanonicalFoundLHS,
11118 CanonicalFoundRHS);
11119 if (ICmpInst::isUnsigned(CanonicalPred) && isKnownNegative(CanonicalRHS))
11120 // Use implication:
11121 // x <s y && y <s 0 --> x <u y.
11122 // If we can prove the left part, the right part is also proven.
11123 return isImpliedCondOperands(CanonicalFoundPred, CanonicalLHS,
11124 CanonicalRHS, CanonicalFoundLHS,
11125 CanonicalFoundRHS);
11126 }
11127
11128 // Check if we can make progress by sharpening ranges.
11129 if (FoundPred == ICmpInst::ICMP_NE &&
11130 (isa<SCEVConstant>(FoundLHS) || isa<SCEVConstant>(FoundRHS))) {
11131
11132 const SCEVConstant *C = nullptr;
11133 const SCEV *V = nullptr;
11134
11135 if (isa<SCEVConstant>(FoundLHS)) {
11136 C = cast<SCEVConstant>(FoundLHS);
11137 V = FoundRHS;
11138 } else {
11139 C = cast<SCEVConstant>(FoundRHS);
11140 V = FoundLHS;
11141 }
11142
11143 // The guarding predicate tells us that C != V. If the known range
11144 // of V is [C, t), we can sharpen the range to [C + 1, t). The
11145 // range we consider has to correspond to same signedness as the
11146 // predicate we're interested in folding.
11147
11148 APInt Min = ICmpInst::isSigned(Pred) ?
11149 getSignedRangeMin(V) : getUnsignedRangeMin(V);
11150
11151 if (Min == C->getAPInt()) {
11152 // Given (V >= Min && V != Min) we conclude V >= (Min + 1).
11153 // This is true even if (Min + 1) wraps around -- in case of
11154 // wraparound, (Min + 1) < Min, so (V >= Min => V >= (Min + 1)).
11155
11156 APInt SharperMin = Min + 1;
11157
11158 switch (Pred) {
11159 case ICmpInst::ICMP_SGE:
11160 case ICmpInst::ICMP_UGE:
11161 // We know V `Pred` SharperMin. If this implies LHS `Pred`
11162 // RHS, we're done.
11163 if (isImpliedCondOperands(Pred, LHS, RHS, V, getConstant(SharperMin),
11164 CtxI))
11165 return true;
11166 LLVM_FALLTHROUGH[[gnu::fallthrough]];
11167
11168 case ICmpInst::ICMP_SGT:
11169 case ICmpInst::ICMP_UGT:
11170 // We know from the range information that (V `Pred` Min ||
11171 // V == Min). We know from the guarding condition that !(V
11172 // == Min). This gives us
11173 //
11174 // V `Pred` Min || V == Min && !(V == Min)
11175 // => V `Pred` Min
11176 //
11177 // If V `Pred` Min implies LHS `Pred` RHS, we're done.
11178
11179 if (isImpliedCondOperands(Pred, LHS, RHS, V, getConstant(Min), CtxI))
11180 return true;
11181 break;
11182
11183 // `LHS < RHS` and `LHS <= RHS` are handled in the same way as `RHS > LHS` and `RHS >= LHS` respectively.
11184 case ICmpInst::ICMP_SLE:
11185 case ICmpInst::ICMP_ULE:
11186 if (isImpliedCondOperands(CmpInst::getSwappedPredicate(Pred), RHS,
11187 LHS, V, getConstant(SharperMin), CtxI))
11188 return true;
11189 LLVM_FALLTHROUGH[[gnu::fallthrough]];
11190
11191 case ICmpInst::ICMP_SLT:
11192 case ICmpInst::ICMP_ULT:
11193 if (isImpliedCondOperands(CmpInst::getSwappedPredicate(Pred), RHS,
11194 LHS, V, getConstant(Min), CtxI))
11195 return true;
11196 break;
11197
11198 default:
11199 // No change
11200 break;
11201 }
11202 }
11203 }
11204
11205 // Check whether the actual condition is beyond sufficient.
11206 if (FoundPred == ICmpInst::ICMP_EQ)
11207 if (ICmpInst::isTrueWhenEqual(Pred))
11208 if (isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS, CtxI))
11209 return true;
11210 if (Pred == ICmpInst::ICMP_NE)
11211 if (!ICmpInst::isTrueWhenEqual(FoundPred))
11212 if (isImpliedCondOperands(FoundPred, LHS, RHS, FoundLHS, FoundRHS, CtxI))
11213 return true;
11214
11215 // Otherwise assume the worst.
11216 return false;
11217}
11218
11219bool ScalarEvolution::splitBinaryAdd(const SCEV *Expr,
11220 const SCEV *&L, const SCEV *&R,
11221 SCEV::NoWrapFlags &Flags) {
11222 const auto *AE = dyn_cast<SCEVAddExpr>(Expr);
11223 if (!AE || AE->getNumOperands() != 2)
11224 return false;
11225
11226 L = AE->getOperand(0);
11227 R = AE->getOperand(1);
11228 Flags = AE->getNoWrapFlags();
11229 return true;
11230}
11231
11232Optional<APInt> ScalarEvolution::computeConstantDifference(const SCEV *More,
11233 const SCEV *Less) {
11234 // We avoid subtracting expressions here because this function is usually
11235 // fairly deep in the call stack (i.e. is called many times).
11236
11237 // X - X = 0.
11238 if (More == Less)
11239 return APInt(getTypeSizeInBits(More->getType()), 0);
11240
11241 if (isa<SCEVAddRecExpr>(Less) && isa<SCEVAddRecExpr>(More)) {
11242 const auto *LAR = cast<SCEVAddRecExpr>(Less);
11243 const auto *MAR = cast<SCEVAddRecExpr>(More);
11244
11245 if (LAR->getLoop() != MAR->getLoop())
11246 return None;
11247
11248 // We look at affine expressions only; not for correctness but to keep
11249 // getStepRecurrence cheap.
11250 if (!LAR->isAffine() || !MAR->isAffine())
11251 return None;
11252
11253 if (LAR->getStepRecurrence(*this) != MAR->getStepRecurrence(*this))
11254 return None;
11255
11256 Less = LAR->getStart();
11257 More = MAR->getStart();
11258
11259 // fall through
11260 }
11261
11262 if (isa<SCEVConstant>(Less) && isa<SCEVConstant>(More)) {
11263 const auto &M = cast<SCEVConstant>(More)->getAPInt();
11264 const auto &L = cast<SCEVConstant>(Less)->getAPInt();
11265 return M - L;
11266 }
11267
11268 SCEV::NoWrapFlags Flags;
11269 const SCEV *LLess = nullptr, *RLess = nullptr;
11270 const SCEV *LMore = nullptr, *RMore = nullptr;
11271 const SCEVConstant *C1 = nullptr, *C2 = nullptr;
11272 // Compare (X + C1) vs X.
11273 if (splitBinaryAdd(Less, LLess, RLess, Flags))
11274 if ((C1 = dyn_cast<SCEVConstant>(LLess)))
11275 if (RLess == More)
11276 return -(C1->getAPInt());
11277
11278 // Compare X vs (X + C2).
11279 if (splitBinaryAdd(More, LMore, RMore, Flags))
11280 if ((C2 = dyn_cast<SCEVConstant>(LMore)))
11281 if (RMore == Less)
11282 return C2->getAPInt();
11283
11284 // Compare (X + C1) vs (X + C2).
11285 if (C1 && C2 && RLess == RMore)
11286 return C2->getAPInt() - C1->getAPInt();
11287
11288 return None;
11289}
11290
11291bool ScalarEvolution::isImpliedCondOperandsViaAddRecStart(
11292 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS,
11293 const SCEV *FoundLHS, const SCEV *FoundRHS, const Instruction *CtxI) {
11294 // Try to recognize the following pattern:
11295 //
11296 // FoundRHS = ...
11297 // ...
11298 // loop:
11299 // FoundLHS = {Start,+,W}
11300 // context_bb: // Basic block from the same loop
11301 // known(Pred, FoundLHS, FoundRHS)
11302 //
11303 // If some predicate is known in the context of a loop, it is also known on
11304 // each iteration of this loop, including the first iteration. Therefore, in
11305 // this case, `FoundLHS Pred FoundRHS` implies `Start Pred FoundRHS`. Try to
11306 // prove the original pred using this fact.
11307 if (!CtxI)
11308 return false;
11309 const BasicBlock *ContextBB = CtxI->getParent();
11310 // Make sure AR varies in the context block.
11311 if (auto *AR = dyn_cast<SCEVAddRecExpr>(FoundLHS)) {
11312 const Loop *L = AR->getLoop();
11313 // Make sure that context belongs to the loop and executes on 1st iteration
11314 // (if it ever executes at all).
11315 if (!L->contains(ContextBB) || !DT.dominates(ContextBB, L->getLoopLatch()))
11316 return false;
11317 if (!isAvailableAtLoopEntry(FoundRHS, AR->getLoop()))
11318 return false;
11319 return isImpliedCondOperands(Pred, LHS, RHS, AR->getStart(), FoundRHS);
11320 }
11321
11322 if (auto *AR = dyn_cast<SCEVAddRecExpr>(FoundRHS)) {
11323 const Loop *L = AR->getLoop();
11324 // Make sure that context belongs to the loop and executes on 1st iteration
11325 // (if it ever executes at all).
11326 if (!L->contains(ContextBB) || !DT.dominates(ContextBB, L->getLoopLatch()))
11327 return false;
11328 if (!isAvailableAtLoopEntry(FoundLHS, AR->getLoop()))
11329 return false;
11330 return isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, AR->getStart());
11331 }
11332
11333 return false;
11334}
11335
11336bool ScalarEvolution::isImpliedCondOperandsViaNoOverflow(
11337 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS,
11338 const SCEV *FoundLHS, const SCEV *FoundRHS) {
11339 if (Pred != CmpInst::ICMP_SLT && Pred != CmpInst::ICMP_ULT)
11340 return false;
11341
11342 const auto *AddRecLHS = dyn_cast<SCEVAddRecExpr>(LHS);
11343 if (!AddRecLHS)
11344 return false;
11345
11346 const auto *AddRecFoundLHS = dyn_cast<SCEVAddRecExpr>(FoundLHS);
11347 if (!AddRecFoundLHS)
11348 return false;
11349
11350 // We'd like to let SCEV reason about control dependencies, so we constrain
11351 // both the inequalities to be about add recurrences on the same loop. This
11352 // way we can use isLoopEntryGuardedByCond later.
11353
11354 const Loop *L = AddRecFoundLHS->getLoop();
11355 if (L != AddRecLHS->getLoop())
11356 return false;
11357
11358 // FoundLHS u< FoundRHS u< -C => (FoundLHS + C) u< (FoundRHS + C) ... (1)
11359 //
11360 // FoundLHS s< FoundRHS s< INT_MIN - C => (FoundLHS + C) s< (FoundRHS + C)
11361 // ... (2)
11362 //
11363 // Informal proof for (2), assuming (1) [*]:
11364 //
11365 // We'll also assume (A s< B) <=> ((A + INT_MIN) u< (B + INT_MIN)) ... (3)[**]
11366 //
11367 // Then
11368 //
11369 // FoundLHS s< FoundRHS s< INT_MIN - C
11370 // <=> (FoundLHS + INT_MIN) u< (FoundRHS + INT_MIN) u< -C [ using (3) ]
11371 // <=> (FoundLHS + INT_MIN + C) u< (FoundRHS + INT_MIN + C) [ using (1) ]
11372 // <=> (FoundLHS + INT_MIN + C + INT_MIN) s<
11373 // (FoundRHS + INT_MIN + C + INT_MIN) [ using (3) ]
11374 // <=> FoundLHS + C s< FoundRHS + C
11375 //
11376 // [*]: (1) can be proved by ruling out overflow.
11377 //
11378 // [**]: This can be proved by analyzing all the four possibilities:
11379 // (A s< 0, B s< 0), (A s< 0, B s>= 0), (A s>= 0, B s< 0) and
11380 // (A s>= 0, B s>= 0).
11381 //
11382 // Note:
11383 // Despite (2), "FoundRHS s< INT_MIN - C" does not mean that "FoundRHS + C"
11384 // will not sign underflow. For instance, say FoundLHS = (i8 -128), FoundRHS
11385 // = (i8 -127) and C = (i8 -100). Then INT_MIN - C = (i8 -28), and FoundRHS
11386 // s< (INT_MIN - C). Lack of sign overflow / underflow in "FoundRHS + C" is
11387 // neither necessary nor sufficient to prove "(FoundLHS + C) s< (FoundRHS +
11388 // C)".
11389
11390 Optional<APInt> LDiff = computeConstantDifference(LHS, FoundLHS);
11391 Optional<APInt> RDiff = computeConstantDifference(RHS, FoundRHS);
11392 if (!LDiff || !RDiff || *LDiff != *RDiff)
11393 return false;
11394
11395 if (LDiff->isMinValue())
11396 return true;
11397
11398 APInt FoundRHSLimit;
11399
11400 if (Pred == CmpInst::ICMP_ULT) {
11401 FoundRHSLimit = -(*RDiff);
11402 } else {
11403 assert(Pred == CmpInst::ICMP_SLT && "Checked above!")(static_cast <bool> (Pred == CmpInst::ICMP_SLT &&
"Checked above!") ? void (0) : __assert_fail ("Pred == CmpInst::ICMP_SLT && \"Checked above!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11403, __extension__
__PRETTY_FUNCTION__));
11404 FoundRHSLimit = APInt::getSignedMinValue(getTypeSizeInBits(RHS->getType())) - *RDiff;
11405 }
11406
11407 // Try to prove (1) or (2), as needed.
11408 return isAvailableAtLoopEntry(FoundRHS, L) &&
11409 isLoopEntryGuardedByCond(L, Pred, FoundRHS,
11410 getConstant(FoundRHSLimit));
11411}
11412
11413bool ScalarEvolution::isImpliedViaMerge(ICmpInst::Predicate Pred,
11414 const SCEV *LHS, const SCEV *RHS,
11415 const SCEV *FoundLHS,
11416 const SCEV *FoundRHS, unsigned Depth) {
11417 const PHINode *LPhi = nullptr, *RPhi = nullptr;
11418
11419 auto ClearOnExit = make_scope_exit([&]() {
11420 if (LPhi) {
11421 bool Erased = PendingMerges.erase(LPhi);
11422 assert(Erased && "Failed to erase LPhi!")(static_cast <bool> (Erased && "Failed to erase LPhi!"
) ? void (0) : __assert_fail ("Erased && \"Failed to erase LPhi!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11422, __extension__
__PRETTY_FUNCTION__));
11423 (void)Erased;
11424 }
11425 if (RPhi) {
11426 bool Erased = PendingMerges.erase(RPhi);
11427 assert(Erased && "Failed to erase RPhi!")(static_cast <bool> (Erased && "Failed to erase RPhi!"
) ? void (0) : __assert_fail ("Erased && \"Failed to erase RPhi!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11427, __extension__
__PRETTY_FUNCTION__));
11428 (void)Erased;
11429 }
11430 });
11431
11432 // Find respective Phis and check that they are not being pending.
11433 if (const SCEVUnknown *LU = dyn_cast<SCEVUnknown>(LHS))
11434 if (auto *Phi = dyn_cast<PHINode>(LU->getValue())) {
11435 if (!PendingMerges.insert(Phi).second)
11436 return false;
11437 LPhi = Phi;
11438 }
11439 if (const SCEVUnknown *RU = dyn_cast<SCEVUnknown>(RHS))
11440 if (auto *Phi = dyn_cast<PHINode>(RU->getValue())) {
11441 // If we detect a loop of Phi nodes being processed by this method, for
11442 // example:
11443 //
11444 // %a = phi i32 [ %some1, %preheader ], [ %b, %latch ]
11445 // %b = phi i32 [ %some2, %preheader ], [ %a, %latch ]
11446 //
11447 // we don't want to deal with a case that complex, so return conservative
11448 // answer false.
11449 if (!PendingMerges.insert(Phi).second)
11450 return false;
11451 RPhi = Phi;
11452 }
11453
11454 // If none of LHS, RHS is a Phi, nothing to do here.
11455 if (!LPhi && !RPhi)
11456 return false;
11457
11458 // If there is a SCEVUnknown Phi we are interested in, make it left.
11459 if (!LPhi) {
11460 std::swap(LHS, RHS);
11461 std::swap(FoundLHS, FoundRHS);
11462 std::swap(LPhi, RPhi);
11463 Pred = ICmpInst::getSwappedPredicate(Pred);
11464 }
11465
11466 assert(LPhi && "LPhi should definitely be a SCEVUnknown Phi!")(static_cast <bool> (LPhi && "LPhi should definitely be a SCEVUnknown Phi!"
) ? void (0) : __assert_fail ("LPhi && \"LPhi should definitely be a SCEVUnknown Phi!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11466, __extension__
__PRETTY_FUNCTION__));
11467 const BasicBlock *LBB = LPhi->getParent();
11468 const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS);
11469
11470 auto ProvedEasily = [&](const SCEV *S1, const SCEV *S2) {
11471 return isKnownViaNonRecursiveReasoning(Pred, S1, S2) ||
11472 isImpliedCondOperandsViaRanges(Pred, S1, S2, FoundLHS, FoundRHS) ||
11473 isImpliedViaOperations(Pred, S1, S2, FoundLHS, FoundRHS, Depth);
11474 };
11475
11476 if (RPhi && RPhi->getParent() == LBB) {
11477 // Case one: RHS is also a SCEVUnknown Phi from the same basic block.
11478 // If we compare two Phis from the same block, and for each entry block
11479 // the predicate is true for incoming values from this block, then the
11480 // predicate is also true for the Phis.
11481 for (const BasicBlock *IncBB : predecessors(LBB)) {
11482 const SCEV *L = getSCEV(LPhi->getIncomingValueForBlock(IncBB));
11483 const SCEV *R = getSCEV(RPhi->getIncomingValueForBlock(IncBB));
11484 if (!ProvedEasily(L, R))
11485 return false;
11486 }
11487 } else if (RAR && RAR->getLoop()->getHeader() == LBB) {
11488 // Case two: RHS is also a Phi from the same basic block, and it is an
11489 // AddRec. It means that there is a loop which has both AddRec and Unknown
11490 // PHIs, for it we can compare incoming values of AddRec from above the loop
11491 // and latch with their respective incoming values of LPhi.
11492 // TODO: Generalize to handle loops with many inputs in a header.
11493 if (LPhi->getNumIncomingValues() != 2) return false;
11494
11495 auto *RLoop = RAR->getLoop();
11496 auto *Predecessor = RLoop->getLoopPredecessor();
11497 assert(Predecessor && "Loop with AddRec with no predecessor?")(static_cast <bool> (Predecessor && "Loop with AddRec with no predecessor?"
) ? void (0) : __assert_fail ("Predecessor && \"Loop with AddRec with no predecessor?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11497, __extension__
__PRETTY_FUNCTION__));
11498 const SCEV *L1 = getSCEV(LPhi->getIncomingValueForBlock(Predecessor));
11499 if (!ProvedEasily(L1, RAR->getStart()))
11500 return false;
11501 auto *Latch = RLoop->getLoopLatch();
11502 assert(Latch && "Loop with AddRec with no latch?")(static_cast <bool> (Latch && "Loop with AddRec with no latch?"
) ? void (0) : __assert_fail ("Latch && \"Loop with AddRec with no latch?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11502, __extension__
__PRETTY_FUNCTION__));
11503 const SCEV *L2 = getSCEV(LPhi->getIncomingValueForBlock(Latch));
11504 if (!ProvedEasily(L2, RAR->getPostIncExpr(*this)))
11505 return false;
11506 } else {
11507 // In all other cases go over inputs of LHS and compare each of them to RHS,
11508 // the predicate is true for (LHS, RHS) if it is true for all such pairs.
11509 // At this point RHS is either a non-Phi, or it is a Phi from some block
11510 // different from LBB.
11511 for (const BasicBlock *IncBB : predecessors(LBB)) {
11512 // Check that RHS is available in this block.
11513 if (!dominates(RHS, IncBB))
11514 return false;
11515 const SCEV *L = getSCEV(LPhi->getIncomingValueForBlock(IncBB));
11516 // Make sure L does not refer to a value from a potentially previous
11517 // iteration of a loop.
11518 if (!properlyDominates(L, IncBB))
11519 return false;
11520 if (!ProvedEasily(L, RHS))
11521 return false;
11522 }
11523 }
11524 return true;
11525}
11526
11527bool ScalarEvolution::isImpliedCondOperandsViaShift(ICmpInst::Predicate Pred,
11528 const SCEV *LHS,
11529 const SCEV *RHS,
11530 const SCEV *FoundLHS,
11531 const SCEV *FoundRHS) {
11532 // We want to imply LHS < RHS from LHS < (RHS >> shiftvalue). First, make
11533 // sure that we are dealing with same LHS.
11534 if (RHS == FoundRHS) {
11535 std::swap(LHS, RHS);
11536 std::swap(FoundLHS, FoundRHS);
11537 Pred = ICmpInst::getSwappedPredicate(Pred);
11538 }
11539 if (LHS != FoundLHS)
11540 return false;
11541
11542 auto *SUFoundRHS = dyn_cast<SCEVUnknown>(FoundRHS);
11543 if (!SUFoundRHS)
11544 return false;
11545
11546 Value *Shiftee, *ShiftValue;
11547
11548 using namespace PatternMatch;
11549 if (match(SUFoundRHS->getValue(),
11550 m_LShr(m_Value(Shiftee), m_Value(ShiftValue)))) {
11551 auto *ShifteeS = getSCEV(Shiftee);
11552 // Prove one of the following:
11553 // LHS <u (shiftee >> shiftvalue) && shiftee <=u RHS ---> LHS <u RHS
11554 // LHS <=u (shiftee >> shiftvalue) && shiftee <=u RHS ---> LHS <=u RHS
11555 // LHS <s (shiftee >> shiftvalue) && shiftee <=s RHS && shiftee >=s 0
11556 // ---> LHS <s RHS
11557 // LHS <=s (shiftee >> shiftvalue) && shiftee <=s RHS && shiftee >=s 0
11558 // ---> LHS <=s RHS
11559 if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE)
11560 return isKnownPredicate(ICmpInst::ICMP_ULE, ShifteeS, RHS);
11561 if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE)
11562 if (isKnownNonNegative(ShifteeS))
11563 return isKnownPredicate(ICmpInst::ICMP_SLE, ShifteeS, RHS);
11564 }
11565
11566 return false;
11567}
11568
11569bool ScalarEvolution::isImpliedCondOperands(ICmpInst::Predicate Pred,
11570 const SCEV *LHS, const SCEV *RHS,
11571 const SCEV *FoundLHS,
11572 const SCEV *FoundRHS,
11573 const Instruction *CtxI) {
11574 if (isImpliedCondOperandsViaRanges(Pred, LHS, RHS, FoundLHS, FoundRHS))
11575 return true;
11576
11577 if (isImpliedCondOperandsViaNoOverflow(Pred, LHS, RHS, FoundLHS, FoundRHS))
11578 return true;
11579
11580 if (isImpliedCondOperandsViaShift(Pred, LHS, RHS, FoundLHS, FoundRHS))
11581 return true;
11582
11583 if (isImpliedCondOperandsViaAddRecStart(Pred, LHS, RHS, FoundLHS, FoundRHS,
11584 CtxI))
11585 return true;
11586
11587 return isImpliedCondOperandsHelper(Pred, LHS, RHS,
11588 FoundLHS, FoundRHS);
11589}
11590
11591/// Is MaybeMinMaxExpr an (U|S)(Min|Max) of Candidate and some other values?
11592template <typename MinMaxExprType>
11593static bool IsMinMaxConsistingOf(const SCEV *MaybeMinMaxExpr,
11594 const SCEV *Candidate) {
11595 const MinMaxExprType *MinMaxExpr = dyn_cast<MinMaxExprType>(MaybeMinMaxExpr);
11596 if (!MinMaxExpr)
11597 return false;
11598
11599 return is_contained(MinMaxExpr->operands(), Candidate);
11600}
11601
11602static bool IsKnownPredicateViaAddRecStart(ScalarEvolution &SE,
11603 ICmpInst::Predicate Pred,
11604 const SCEV *LHS, const SCEV *RHS) {
11605 // If both sides are affine addrecs for the same loop, with equal
11606 // steps, and we know the recurrences don't wrap, then we only
11607 // need to check the predicate on the starting values.
11608
11609 if (!ICmpInst::isRelational(Pred))
11610 return false;
11611
11612 const SCEVAddRecExpr *LAR = dyn_cast<SCEVAddRecExpr>(LHS);
11613 if (!LAR)
11614 return false;
11615 const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS);
11616 if (!RAR)
11617 return false;
11618 if (LAR->getLoop() != RAR->getLoop())
11619 return false;
11620 if (!LAR->isAffine() || !RAR->isAffine())
11621 return false;
11622
11623 if (LAR->getStepRecurrence(SE) != RAR->getStepRecurrence(SE))
11624 return false;
11625
11626 SCEV::NoWrapFlags NW = ICmpInst::isSigned(Pred) ?
11627 SCEV::FlagNSW : SCEV::FlagNUW;
11628 if (!LAR->getNoWrapFlags(NW) || !RAR->getNoWrapFlags(NW))
11629 return false;
11630
11631 return SE.isKnownPredicate(Pred, LAR->getStart(), RAR->getStart());
11632}
11633
11634/// Is LHS `Pred` RHS true on the virtue of LHS or RHS being a Min or Max
11635/// expression?
11636static bool IsKnownPredicateViaMinOrMax(ScalarEvolution &SE,
11637 ICmpInst::Predicate Pred,
11638 const SCEV *LHS, const SCEV *RHS) {
11639 switch (Pred) {
11640 default:
11641 return false;
11642
11643 case ICmpInst::ICMP_SGE:
11644 std::swap(LHS, RHS);
11645 LLVM_FALLTHROUGH[[gnu::fallthrough]];
11646 case ICmpInst::ICMP_SLE:
11647 return
11648 // min(A, ...) <= A
11649 IsMinMaxConsistingOf<SCEVSMinExpr>(LHS, RHS) ||
11650 // A <= max(A, ...)
11651 IsMinMaxConsistingOf<SCEVSMaxExpr>(RHS, LHS);
11652
11653 case ICmpInst::ICMP_UGE:
11654 std::swap(LHS, RHS);
11655 LLVM_FALLTHROUGH[[gnu::fallthrough]];
11656 case ICmpInst::ICMP_ULE:
11657 return
11658 // min(A, ...) <= A
11659 // FIXME: what about umin_seq?
11660 IsMinMaxConsistingOf<SCEVUMinExpr>(LHS, RHS) ||
11661 // A <= max(A, ...)
11662 IsMinMaxConsistingOf<SCEVUMaxExpr>(RHS, LHS);
11663 }
11664
11665 llvm_unreachable("covered switch fell through?!")::llvm::llvm_unreachable_internal("covered switch fell through?!"
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11665);
11666}
11667
11668bool ScalarEvolution::isImpliedViaOperations(ICmpInst::Predicate Pred,
11669 const SCEV *LHS, const SCEV *RHS,
11670 const SCEV *FoundLHS,
11671 const SCEV *FoundRHS,
11672 unsigned Depth) {
11673 assert(getTypeSizeInBits(LHS->getType()) ==(static_cast <bool> (getTypeSizeInBits(LHS->getType(
)) == getTypeSizeInBits(RHS->getType()) && "LHS and RHS have different sizes?"
) ? void (0) : __assert_fail ("getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS->getType()) && \"LHS and RHS have different sizes?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11675, __extension__
__PRETTY_FUNCTION__))
11674 getTypeSizeInBits(RHS->getType()) &&(static_cast <bool> (getTypeSizeInBits(LHS->getType(
)) == getTypeSizeInBits(RHS->getType()) && "LHS and RHS have different sizes?"
) ? void (0) : __assert_fail ("getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS->getType()) && \"LHS and RHS have different sizes?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11675, __extension__
__PRETTY_FUNCTION__))
11675 "LHS and RHS have different sizes?")(static_cast <bool> (getTypeSizeInBits(LHS->getType(
)) == getTypeSizeInBits(RHS->getType()) && "LHS and RHS have different sizes?"
) ? void (0) : __assert_fail ("getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS->getType()) && \"LHS and RHS have different sizes?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11675, __extension__
__PRETTY_FUNCTION__));
11676 assert(getTypeSizeInBits(FoundLHS->getType()) ==(static_cast <bool> (getTypeSizeInBits(FoundLHS->getType
()) == getTypeSizeInBits(FoundRHS->getType()) && "FoundLHS and FoundRHS have different sizes?"
) ? void (0) : __assert_fail ("getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits(FoundRHS->getType()) && \"FoundLHS and FoundRHS have different sizes?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11678, __extension__
__PRETTY_FUNCTION__))
11677 getTypeSizeInBits(FoundRHS->getType()) &&(static_cast <bool> (getTypeSizeInBits(FoundLHS->getType
()) == getTypeSizeInBits(FoundRHS->getType()) && "FoundLHS and FoundRHS have different sizes?"
) ? void (0) : __assert_fail ("getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits(FoundRHS->getType()) && \"FoundLHS and FoundRHS have different sizes?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11678, __extension__
__PRETTY_FUNCTION__))
11678 "FoundLHS and FoundRHS have different sizes?")(static_cast <bool> (getTypeSizeInBits(FoundLHS->getType
()) == getTypeSizeInBits(FoundRHS->getType()) && "FoundLHS and FoundRHS have different sizes?"
) ? void (0) : __assert_fail ("getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits(FoundRHS->getType()) && \"FoundLHS and FoundRHS have different sizes?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11678, __extension__
__PRETTY_FUNCTION__));
11679 // We want to avoid hurting the compile time with analysis of too big trees.
11680 if (Depth > MaxSCEVOperationsImplicationDepth)
11681 return false;
11682
11683 // We only want to work with GT comparison so far.
11684 if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_SLT) {
11685 Pred = CmpInst::getSwappedPredicate(Pred);
11686 std::swap(LHS, RHS);
11687 std::swap(FoundLHS, FoundRHS);
11688 }
11689
11690 // For unsigned, try to reduce it to corresponding signed comparison.
11691 if (Pred == ICmpInst::ICMP_UGT)
11692 // We can replace unsigned predicate with its signed counterpart if all
11693 // involved values are non-negative.
11694 // TODO: We could have better support for unsigned.
11695 if (isKnownNonNegative(FoundLHS) && isKnownNonNegative(FoundRHS)) {
11696 // Knowing that both FoundLHS and FoundRHS are non-negative, and knowing
11697 // FoundLHS >u FoundRHS, we also know that FoundLHS >s FoundRHS. Let us
11698 // use this fact to prove that LHS and RHS are non-negative.
11699 const SCEV *MinusOne = getMinusOne(LHS->getType());
11700 if (isImpliedCondOperands(ICmpInst::ICMP_SGT, LHS, MinusOne, FoundLHS,
11701 FoundRHS) &&
11702 isImpliedCondOperands(ICmpInst::ICMP_SGT, RHS, MinusOne, FoundLHS,
11703 FoundRHS))
11704 Pred = ICmpInst::ICMP_SGT;
11705 }
11706
11707 if (Pred != ICmpInst::ICMP_SGT)
11708 return false;
11709
11710 auto GetOpFromSExt = [&](const SCEV *S) {
11711 if (auto *Ext = dyn_cast<SCEVSignExtendExpr>(S))
11712 return Ext->getOperand();
11713 // TODO: If S is a SCEVConstant then you can cheaply "strip" the sext off
11714 // the constant in some cases.
11715 return S;
11716 };
11717
11718 // Acquire values from extensions.
11719 auto *OrigLHS = LHS;
11720 auto *OrigFoundLHS = FoundLHS;
11721 LHS = GetOpFromSExt(LHS);
11722 FoundLHS = GetOpFromSExt(FoundLHS);
11723
11724 // Is the SGT predicate can be proved trivially or using the found context.
11725 auto IsSGTViaContext = [&](const SCEV *S1, const SCEV *S2) {
11726 return isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SGT, S1, S2) ||
11727 isImpliedViaOperations(ICmpInst::ICMP_SGT, S1, S2, OrigFoundLHS,
11728 FoundRHS, Depth + 1);
11729 };
11730
11731 if (auto *LHSAddExpr = dyn_cast<SCEVAddExpr>(LHS)) {
11732 // We want to avoid creation of any new non-constant SCEV. Since we are
11733 // going to compare the operands to RHS, we should be certain that we don't
11734 // need any size extensions for this. So let's decline all cases when the
11735 // sizes of types of LHS and RHS do not match.
11736 // TODO: Maybe try to get RHS from sext to catch more cases?
11737 if (getTypeSizeInBits(LHS->getType()) != getTypeSizeInBits(RHS->getType()))
11738 return false;
11739
11740 // Should not overflow.
11741 if (!LHSAddExpr->hasNoSignedWrap())
11742 return false;
11743
11744 auto *LL = LHSAddExpr->getOperand(0);
11745 auto *LR = LHSAddExpr->getOperand(1);
11746 auto *MinusOne = getMinusOne(RHS->getType());
11747
11748 // Checks that S1 >= 0 && S2 > RHS, trivially or using the found context.
11749 auto IsSumGreaterThanRHS = [&](const SCEV *S1, const SCEV *S2) {
11750 return IsSGTViaContext(S1, MinusOne) && IsSGTViaContext(S2, RHS);
11751 };
11752 // Try to prove the following rule:
11753 // (LHS = LL + LR) && (LL >= 0) && (LR > RHS) => (LHS > RHS).
11754 // (LHS = LL + LR) && (LR >= 0) && (LL > RHS) => (LHS > RHS).
11755 if (IsSumGreaterThanRHS(LL, LR) || IsSumGreaterThanRHS(LR, LL))
11756 return true;
11757 } else if (auto *LHSUnknownExpr = dyn_cast<SCEVUnknown>(LHS)) {
11758 Value *LL, *LR;
11759 // FIXME: Once we have SDiv implemented, we can get rid of this matching.
11760
11761 using namespace llvm::PatternMatch;
11762
11763 if (match(LHSUnknownExpr->getValue(), m_SDiv(m_Value(LL), m_Value(LR)))) {
11764 // Rules for division.
11765 // We are going to perform some comparisons with Denominator and its
11766 // derivative expressions. In general case, creating a SCEV for it may
11767 // lead to a complex analysis of the entire graph, and in particular it
11768 // can request trip count recalculation for the same loop. This would
11769 // cache as SCEVCouldNotCompute to avoid the infinite recursion. To avoid
11770 // this, we only want to create SCEVs that are constants in this section.
11771 // So we bail if Denominator is not a constant.
11772 if (!isa<ConstantInt>(LR))
11773 return false;
11774
11775 auto *Denominator = cast<SCEVConstant>(getSCEV(LR));
11776
11777 // We want to make sure that LHS = FoundLHS / Denominator. If it is so,
11778 // then a SCEV for the numerator already exists and matches with FoundLHS.
11779 auto *Numerator = getExistingSCEV(LL);
11780 if (!Numerator || Numerator->getType() != FoundLHS->getType())
11781 return false;
11782
11783 // Make sure that the numerator matches with FoundLHS and the denominator
11784 // is positive.
11785 if (!HasSameValue(Numerator, FoundLHS) || !isKnownPositive(Denominator))
11786 return false;
11787
11788 auto *DTy = Denominator->getType();
11789 auto *FRHSTy = FoundRHS->getType();
11790 if (DTy->isPointerTy() != FRHSTy->isPointerTy())
11791 // One of types is a pointer and another one is not. We cannot extend
11792 // them properly to a wider type, so let us just reject this case.
11793 // TODO: Usage of getEffectiveSCEVType for DTy, FRHSTy etc should help
11794 // to avoid this check.
11795 return false;
11796
11797 // Given that:
11798 // FoundLHS > FoundRHS, LHS = FoundLHS / Denominator, Denominator > 0.
11799 auto *WTy = getWiderType(DTy, FRHSTy);
11800 auto *DenominatorExt = getNoopOrSignExtend(Denominator, WTy);
11801 auto *FoundRHSExt = getNoopOrSignExtend(FoundRHS, WTy);
11802
11803 // Try to prove the following rule:
11804 // (FoundRHS > Denominator - 2) && (RHS <= 0) => (LHS > RHS).
11805 // For example, given that FoundLHS > 2. It means that FoundLHS is at
11806 // least 3. If we divide it by Denominator < 4, we will have at least 1.
11807 auto *DenomMinusTwo = getMinusSCEV(DenominatorExt, getConstant(WTy, 2));
11808 if (isKnownNonPositive(RHS) &&
11809 IsSGTViaContext(FoundRHSExt, DenomMinusTwo))
11810 return true;
11811
11812 // Try to prove the following rule:
11813 // (FoundRHS > -1 - Denominator) && (RHS < 0) => (LHS > RHS).
11814 // For example, given that FoundLHS > -3. Then FoundLHS is at least -2.
11815 // If we divide it by Denominator > 2, then:
11816 // 1. If FoundLHS is negative, then the result is 0.
11817 // 2. If FoundLHS is non-negative, then the result is non-negative.
11818 // Anyways, the result is non-negative.
11819 auto *MinusOne = getMinusOne(WTy);
11820 auto *NegDenomMinusOne = getMinusSCEV(MinusOne, DenominatorExt);
11821 if (isKnownNegative(RHS) &&
11822 IsSGTViaContext(FoundRHSExt, NegDenomMinusOne))
11823 return true;
11824 }
11825 }
11826
11827 // If our expression contained SCEVUnknown Phis, and we split it down and now
11828 // need to prove something for them, try to prove the predicate for every
11829 // possible incoming values of those Phis.
11830 if (isImpliedViaMerge(Pred, OrigLHS, RHS, OrigFoundLHS, FoundRHS, Depth + 1))
11831 return true;
11832
11833 return false;
11834}
11835
11836static bool isKnownPredicateExtendIdiom(ICmpInst::Predicate Pred,
11837 const SCEV *LHS, const SCEV *RHS) {
11838 // zext x u<= sext x, sext x s<= zext x
11839 switch (Pred) {
11840 case ICmpInst::ICMP_SGE:
11841 std::swap(LHS, RHS);
11842 LLVM_FALLTHROUGH[[gnu::fallthrough]];
11843 case ICmpInst::ICMP_SLE: {
11844 // If operand >=s 0 then ZExt == SExt. If operand <s 0 then SExt <s ZExt.
11845 const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(LHS);
11846 const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(RHS);
11847 if (SExt && ZExt && SExt->getOperand() == ZExt->getOperand())
11848 return true;
11849 break;
11850 }
11851 case ICmpInst::ICMP_UGE:
11852 std::swap(LHS, RHS);
11853 LLVM_FALLTHROUGH[[gnu::fallthrough]];
11854 case ICmpInst::ICMP_ULE: {
11855 // If operand >=s 0 then ZExt == SExt. If operand <s 0 then ZExt <u SExt.
11856 const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(LHS);
11857 const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(RHS);
11858 if (SExt && ZExt && SExt->getOperand() == ZExt->getOperand())
11859 return true;
11860 break;
11861 }
11862 default:
11863 break;
11864 };
11865 return false;
11866}
11867
11868bool
11869ScalarEvolution::isKnownViaNonRecursiveReasoning(ICmpInst::Predicate Pred,
11870 const SCEV *LHS, const SCEV *RHS) {
11871 return isKnownPredicateExtendIdiom(Pred, LHS, RHS) ||
11872 isKnownPredicateViaConstantRanges(Pred, LHS, RHS) ||
11873 IsKnownPredicateViaMinOrMax(*this, Pred, LHS, RHS) ||
11874 IsKnownPredicateViaAddRecStart(*this, Pred, LHS, RHS) ||
11875 isKnownPredicateViaNoOverflow(Pred, LHS, RHS);
11876}
11877
11878bool
11879ScalarEvolution::isImpliedCondOperandsHelper(ICmpInst::Predicate Pred,
11880 const SCEV *LHS, const SCEV *RHS,
11881 const SCEV *FoundLHS,
11882 const SCEV *FoundRHS) {
11883 switch (Pred) {
11884 default: llvm_unreachable("Unexpected ICmpInst::Predicate value!")::llvm::llvm_unreachable_internal("Unexpected ICmpInst::Predicate value!"
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11884);
11885 case ICmpInst::ICMP_EQ:
11886 case ICmpInst::ICMP_NE:
11887 if (HasSameValue(LHS, FoundLHS) && HasSameValue(RHS, FoundRHS))
11888 return true;
11889 break;
11890 case ICmpInst::ICMP_SLT:
11891 case ICmpInst::ICMP_SLE:
11892 if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SLE, LHS, FoundLHS) &&
11893 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SGE, RHS, FoundRHS))
11894 return true;
11895 break;
11896 case ICmpInst::ICMP_SGT:
11897 case ICmpInst::ICMP_SGE:
11898 if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SGE, LHS, FoundLHS) &&
11899 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SLE, RHS, FoundRHS))
11900 return true;
11901 break;
11902 case ICmpInst::ICMP_ULT:
11903 case ICmpInst::ICMP_ULE:
11904 if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_ULE, LHS, FoundLHS) &&
11905 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_UGE, RHS, FoundRHS))
11906 return true;
11907 break;
11908 case ICmpInst::ICMP_UGT:
11909 case ICmpInst::ICMP_UGE:
11910 if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_UGE, LHS, FoundLHS) &&
11911 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_ULE, RHS, FoundRHS))
11912 return true;
11913 break;
11914 }
11915
11916 // Maybe it can be proved via operations?
11917 if (isImpliedViaOperations(Pred, LHS, RHS, FoundLHS, FoundRHS))
11918 return true;
11919
11920 return false;
11921}
11922
11923bool ScalarEvolution::isImpliedCondOperandsViaRanges(ICmpInst::Predicate Pred,
11924 const SCEV *LHS,
11925 const SCEV *RHS,
11926 const SCEV *FoundLHS,
11927 const SCEV *FoundRHS) {
11928 if (!isa<SCEVConstant>(RHS) || !isa<SCEVConstant>(FoundRHS))
11929 // The restriction on `FoundRHS` be lifted easily -- it exists only to
11930 // reduce the compile time impact of this optimization.
11931 return false;
11932
11933 Optional<APInt> Addend = computeConstantDifference(LHS, FoundLHS);
11934 if (!Addend)
11935 return false;
11936
11937 const APInt &ConstFoundRHS = cast<SCEVConstant>(FoundRHS)->getAPInt();
11938
11939 // `FoundLHSRange` is the range we know `FoundLHS` to be in by virtue of the
11940 // antecedent "`FoundLHS` `Pred` `FoundRHS`".
11941 ConstantRange FoundLHSRange =
11942 ConstantRange::makeExactICmpRegion(Pred, ConstFoundRHS);
11943
11944 // Since `LHS` is `FoundLHS` + `Addend`, we can compute a range for `LHS`:
11945 ConstantRange LHSRange = FoundLHSRange.add(ConstantRange(*Addend));
11946
11947 // We can also compute the range of values for `LHS` that satisfy the
11948 // consequent, "`LHS` `Pred` `RHS`":
11949 const APInt &ConstRHS = cast<SCEVConstant>(RHS)->getAPInt();
11950 // The antecedent implies the consequent if every value of `LHS` that
11951 // satisfies the antecedent also satisfies the consequent.
11952 return LHSRange.icmp(Pred, ConstRHS);
11953}
11954
11955bool ScalarEvolution::canIVOverflowOnLT(const SCEV *RHS, const SCEV *Stride,
11956 bool IsSigned) {
11957 assert(isKnownPositive(Stride) && "Positive stride expected!")(static_cast <bool> (isKnownPositive(Stride) &&
"Positive stride expected!") ? void (0) : __assert_fail ("isKnownPositive(Stride) && \"Positive stride expected!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 11957, __extension__
__PRETTY_FUNCTION__));
11958
11959 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
11960 const SCEV *One = getOne(Stride->getType());
11961
11962 if (IsSigned) {
11963 APInt MaxRHS = getSignedRangeMax(RHS);
11964 APInt MaxValue = APInt::getSignedMaxValue(BitWidth);
11965 APInt MaxStrideMinusOne = getSignedRangeMax(getMinusSCEV(Stride, One));
11966
11967 // SMaxRHS + SMaxStrideMinusOne > SMaxValue => overflow!
11968 return (std::move(MaxValue) - MaxStrideMinusOne).slt(MaxRHS);
11969 }
11970
11971 APInt MaxRHS = getUnsignedRangeMax(RHS);
11972 APInt MaxValue = APInt::getMaxValue(BitWidth);
11973 APInt MaxStrideMinusOne = getUnsignedRangeMax(getMinusSCEV(Stride, One));
11974
11975 // UMaxRHS + UMaxStrideMinusOne > UMaxValue => overflow!
11976 return (std::move(MaxValue) - MaxStrideMinusOne).ult(MaxRHS);
11977}
11978
11979bool ScalarEvolution::canIVOverflowOnGT(const SCEV *RHS, const SCEV *Stride,
11980 bool IsSigned) {
11981
11982 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
11983 const SCEV *One = getOne(Stride->getType());
11984
11985 if (IsSigned) {
11986 APInt MinRHS = getSignedRangeMin(RHS);
11987 APInt MinValue = APInt::getSignedMinValue(BitWidth);
11988 APInt MaxStrideMinusOne = getSignedRangeMax(getMinusSCEV(Stride, One));
11989
11990 // SMinRHS - SMaxStrideMinusOne < SMinValue => overflow!
11991 return (std::move(MinValue) + MaxStrideMinusOne).sgt(MinRHS);
11992 }
11993
11994 APInt MinRHS = getUnsignedRangeMin(RHS);
11995 APInt MinValue = APInt::getMinValue(BitWidth);
11996 APInt MaxStrideMinusOne = getUnsignedRangeMax(getMinusSCEV(Stride, One));
11997
11998 // UMinRHS - UMaxStrideMinusOne < UMinValue => overflow!
11999 return (std::move(MinValue) + MaxStrideMinusOne).ugt(MinRHS);
12000}
12001
12002const SCEV *ScalarEvolution::getUDivCeilSCEV(const SCEV *N, const SCEV *D) {
12003 // umin(N, 1) + floor((N - umin(N, 1)) / D)
12004 // This is equivalent to "1 + floor((N - 1) / D)" for N != 0. The umin
12005 // expression fixes the case of N=0.
12006 const SCEV *MinNOne = getUMinExpr(N, getOne(N->getType()));
12007 const SCEV *NMinusOne = getMinusSCEV(N, MinNOne);
12008 return getAddExpr(MinNOne, getUDivExpr(NMinusOne, D));
12009}
12010
12011const SCEV *ScalarEvolution::computeMaxBECountForLT(const SCEV *Start,
12012 const SCEV *Stride,
12013 const SCEV *End,
12014 unsigned BitWidth,
12015 bool IsSigned) {
12016 // The logic in this function assumes we can represent a positive stride.
12017 // If we can't, the backedge-taken count must be zero.
12018 if (IsSigned && BitWidth == 1)
12019 return getZero(Stride->getType());
12020
12021 // This code has only been closely audited for negative strides in the
12022 // unsigned comparison case, it may be correct for signed comparison, but
12023 // that needs to be established.
12024 assert((!IsSigned || !isKnownNonPositive(Stride)) &&(static_cast <bool> ((!IsSigned || !isKnownNonPositive(
Stride)) && "Stride is expected strictly positive for signed case!"
) ? void (0) : __assert_fail ("(!IsSigned || !isKnownNonPositive(Stride)) && \"Stride is expected strictly positive for signed case!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12025, __extension__
__PRETTY_FUNCTION__))
12025 "Stride is expected strictly positive for signed case!")(static_cast <bool> ((!IsSigned || !isKnownNonPositive(
Stride)) && "Stride is expected strictly positive for signed case!"
) ? void (0) : __assert_fail ("(!IsSigned || !isKnownNonPositive(Stride)) && \"Stride is expected strictly positive for signed case!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12025, __extension__
__PRETTY_FUNCTION__));
12026
12027 // Calculate the maximum backedge count based on the range of values
12028 // permitted by Start, End, and Stride.
12029 APInt MinStart =
12030 IsSigned ? getSignedRangeMin(Start) : getUnsignedRangeMin(Start);
12031
12032 APInt MinStride =
12033 IsSigned ? getSignedRangeMin(Stride) : getUnsignedRangeMin(Stride);
12034
12035 // We assume either the stride is positive, or the backedge-taken count
12036 // is zero. So force StrideForMaxBECount to be at least one.
12037 APInt One(BitWidth, 1);
12038 APInt StrideForMaxBECount = IsSigned ? APIntOps::smax(One, MinStride)
12039 : APIntOps::umax(One, MinStride);
12040
12041 APInt MaxValue = IsSigned ? APInt::getSignedMaxValue(BitWidth)
12042 : APInt::getMaxValue(BitWidth);
12043 APInt Limit = MaxValue - (StrideForMaxBECount - 1);
12044
12045 // Although End can be a MAX expression we estimate MaxEnd considering only
12046 // the case End = RHS of the loop termination condition. This is safe because
12047 // in the other case (End - Start) is zero, leading to a zero maximum backedge
12048 // taken count.
12049 APInt MaxEnd = IsSigned ? APIntOps::smin(getSignedRangeMax(End), Limit)
12050 : APIntOps::umin(getUnsignedRangeMax(End), Limit);
12051
12052 // MaxBECount = ceil((max(MaxEnd, MinStart) - MinStart) / Stride)
12053 MaxEnd = IsSigned ? APIntOps::smax(MaxEnd, MinStart)
12054 : APIntOps::umax(MaxEnd, MinStart);
12055
12056 return getUDivCeilSCEV(getConstant(MaxEnd - MinStart) /* Delta */,
12057 getConstant(StrideForMaxBECount) /* Step */);
12058}
12059
12060ScalarEvolution::ExitLimit
12061ScalarEvolution::howManyLessThans(const SCEV *LHS, const SCEV *RHS,
12062 const Loop *L, bool IsSigned,
12063 bool ControlsExit, bool AllowPredicates) {
12064 SmallPtrSet<const SCEVPredicate *, 4> Predicates;
12065
12066 const SCEVAddRecExpr *IV = dyn_cast<SCEVAddRecExpr>(LHS);
12067 bool PredicatedIV = false;
12068
12069 auto canAssumeNoSelfWrap = [&](const SCEVAddRecExpr *AR) {
12070 // Can we prove this loop *must* be UB if overflow of IV occurs?
12071 // Reasoning goes as follows:
12072 // * Suppose the IV did self wrap.
12073 // * If Stride evenly divides the iteration space, then once wrap
12074 // occurs, the loop must revisit the same values.
12075 // * We know that RHS is invariant, and that none of those values
12076 // caused this exit to be taken previously. Thus, this exit is
12077 // dynamically dead.
12078 // * If this is the sole exit, then a dead exit implies the loop
12079 // must be infinite if there are no abnormal exits.
12080 // * If the loop were infinite, then it must either not be mustprogress
12081 // or have side effects. Otherwise, it must be UB.
12082 // * It can't (by assumption), be UB so we have contradicted our
12083 // premise and can conclude the IV did not in fact self-wrap.
12084 if (!isLoopInvariant(RHS, L))
12085 return false;
12086
12087 auto *StrideC = dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this));
12088 if (!StrideC || !StrideC->getAPInt().isPowerOf2())
12089 return false;
12090
12091 if (!ControlsExit || !loopHasNoAbnormalExits(L))
12092 return false;
12093
12094 return loopIsFiniteByAssumption(L);
12095 };
12096
12097 if (!IV) {
12098 if (auto *ZExt = dyn_cast<SCEVZeroExtendExpr>(LHS)) {
12099 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(ZExt->getOperand());
12100 if (AR && AR->getLoop() == L && AR->isAffine()) {
12101 auto canProveNUW = [&]() {
12102 if (!isLoopInvariant(RHS, L))
12103 return false;
12104
12105 if (!isKnownNonZero(AR->getStepRecurrence(*this)))
12106 // We need the sequence defined by AR to strictly increase in the
12107 // unsigned integer domain for the logic below to hold.
12108 return false;
12109
12110 const unsigned InnerBitWidth = getTypeSizeInBits(AR->getType());
12111 const unsigned OuterBitWidth = getTypeSizeInBits(RHS->getType());
12112 // If RHS <=u Limit, then there must exist a value V in the sequence
12113 // defined by AR (e.g. {Start,+,Step}) such that V >u RHS, and
12114 // V <=u UINT_MAX. Thus, we must exit the loop before unsigned
12115 // overflow occurs. This limit also implies that a signed comparison
12116 // (in the wide bitwidth) is equivalent to an unsigned comparison as
12117 // the high bits on both sides must be zero.
12118 APInt StrideMax = getUnsignedRangeMax(AR->getStepRecurrence(*this));
12119 APInt Limit = APInt::getMaxValue(InnerBitWidth) - (StrideMax - 1);
12120 Limit = Limit.zext(OuterBitWidth);
12121 return getUnsignedRangeMax(applyLoopGuards(RHS, L)).ule(Limit);
12122 };
12123 auto Flags = AR->getNoWrapFlags();
12124 if (!hasFlags(Flags, SCEV::FlagNUW) && canProveNUW())
12125 Flags = setFlags(Flags, SCEV::FlagNUW);
12126
12127 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), Flags);
12128 if (AR->hasNoUnsignedWrap()) {
12129 // Emulate what getZeroExtendExpr would have done during construction
12130 // if we'd been able to infer the fact just above at that time.
12131 const SCEV *Step = AR->getStepRecurrence(*this);
12132 Type *Ty = ZExt->getType();
12133 auto *S = getAddRecExpr(
12134 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, 0),
12135 getZeroExtendExpr(Step, Ty, 0), L, AR->getNoWrapFlags());
12136 IV = dyn_cast<SCEVAddRecExpr>(S);
12137 }
12138 }
12139 }
12140 }
12141
12142
12143 if (!IV && AllowPredicates) {
12144 // Try to make this an AddRec using runtime tests, in the first X
12145 // iterations of this loop, where X is the SCEV expression found by the
12146 // algorithm below.
12147 IV = convertSCEVToAddRecWithPredicates(LHS, L, Predicates);
12148 PredicatedIV = true;
12149 }
12150
12151 // Avoid weird loops
12152 if (!IV || IV->getLoop() != L || !IV->isAffine())
12153 return getCouldNotCompute();
12154
12155 // A precondition of this method is that the condition being analyzed
12156 // reaches an exiting branch which dominates the latch. Given that, we can
12157 // assume that an increment which violates the nowrap specification and
12158 // produces poison must cause undefined behavior when the resulting poison
12159 // value is branched upon and thus we can conclude that the backedge is
12160 // taken no more often than would be required to produce that poison value.
12161 // Note that a well defined loop can exit on the iteration which violates
12162 // the nowrap specification if there is another exit (either explicit or
12163 // implicit/exceptional) which causes the loop to execute before the
12164 // exiting instruction we're analyzing would trigger UB.
12165 auto WrapType = IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW;
12166 bool NoWrap = ControlsExit && IV->getNoWrapFlags(WrapType);
12167 ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
12168
12169 const SCEV *Stride = IV->getStepRecurrence(*this);
12170
12171 bool PositiveStride = isKnownPositive(Stride);
12172
12173 // Avoid negative or zero stride values.
12174 if (!PositiveStride) {
12175 // We can compute the correct backedge taken count for loops with unknown
12176 // strides if we can prove that the loop is not an infinite loop with side
12177 // effects. Here's the loop structure we are trying to handle -
12178 //
12179 // i = start
12180 // do {
12181 // A[i] = i;
12182 // i += s;
12183 // } while (i < end);
12184 //
12185 // The backedge taken count for such loops is evaluated as -
12186 // (max(end, start + stride) - start - 1) /u stride
12187 //
12188 // The additional preconditions that we need to check to prove correctness
12189 // of the above formula is as follows -
12190 //
12191 // a) IV is either nuw or nsw depending upon signedness (indicated by the
12192 // NoWrap flag).
12193 // b) the loop is guaranteed to be finite (e.g. is mustprogress and has
12194 // no side effects within the loop)
12195 // c) loop has a single static exit (with no abnormal exits)
12196 //
12197 // Precondition a) implies that if the stride is negative, this is a single
12198 // trip loop. The backedge taken count formula reduces to zero in this case.
12199 //
12200 // Precondition b) and c) combine to imply that if rhs is invariant in L,
12201 // then a zero stride means the backedge can't be taken without executing
12202 // undefined behavior.
12203 //
12204 // The positive stride case is the same as isKnownPositive(Stride) returning
12205 // true (original behavior of the function).
12206 //
12207 if (PredicatedIV || !NoWrap || !loopIsFiniteByAssumption(L) ||
12208 !loopHasNoAbnormalExits(L))
12209 return getCouldNotCompute();
12210
12211 // This bailout is protecting the logic in computeMaxBECountForLT which
12212 // has not yet been sufficiently auditted or tested with negative strides.
12213 // We used to filter out all known-non-positive cases here, we're in the
12214 // process of being less restrictive bit by bit.
12215 if (IsSigned && isKnownNonPositive(Stride))
12216 return getCouldNotCompute();
12217
12218 if (!isKnownNonZero(Stride)) {
12219 // If we have a step of zero, and RHS isn't invariant in L, we don't know
12220 // if it might eventually be greater than start and if so, on which
12221 // iteration. We can't even produce a useful upper bound.
12222 if (!isLoopInvariant(RHS, L))
12223 return getCouldNotCompute();
12224
12225 // We allow a potentially zero stride, but we need to divide by stride
12226 // below. Since the loop can't be infinite and this check must control
12227 // the sole exit, we can infer the exit must be taken on the first
12228 // iteration (e.g. backedge count = 0) if the stride is zero. Given that,
12229 // we know the numerator in the divides below must be zero, so we can
12230 // pick an arbitrary non-zero value for the denominator (e.g. stride)
12231 // and produce the right result.
12232 // FIXME: Handle the case where Stride is poison?
12233 auto wouldZeroStrideBeUB = [&]() {
12234 // Proof by contradiction. Suppose the stride were zero. If we can
12235 // prove that the backedge *is* taken on the first iteration, then since
12236 // we know this condition controls the sole exit, we must have an
12237 // infinite loop. We can't have a (well defined) infinite loop per
12238 // check just above.
12239 // Note: The (Start - Stride) term is used to get the start' term from
12240 // (start' + stride,+,stride). Remember that we only care about the
12241 // result of this expression when stride == 0 at runtime.
12242 auto *StartIfZero = getMinusSCEV(IV->getStart(), Stride);
12243 return isLoopEntryGuardedByCond(L, Cond, StartIfZero, RHS);
12244 };
12245 if (!wouldZeroStrideBeUB()) {
12246 Stride = getUMaxExpr(Stride, getOne(Stride->getType()));
12247 }
12248 }
12249 } else if (!Stride->isOne() && !NoWrap) {
12250 auto isUBOnWrap = [&]() {
12251 // From no-self-wrap, we need to then prove no-(un)signed-wrap. This
12252 // follows trivially from the fact that every (un)signed-wrapped, but
12253 // not self-wrapped value must be LT than the last value before
12254 // (un)signed wrap. Since we know that last value didn't exit, nor
12255 // will any smaller one.
12256 return canAssumeNoSelfWrap(IV);
12257 };
12258
12259 // Avoid proven overflow cases: this will ensure that the backedge taken
12260 // count will not generate any unsigned overflow. Relaxed no-overflow
12261 // conditions exploit NoWrapFlags, allowing to optimize in presence of
12262 // undefined behaviors like the case of C language.
12263 if (canIVOverflowOnLT(RHS, Stride, IsSigned) && !isUBOnWrap())
12264 return getCouldNotCompute();
12265 }
12266
12267 // On all paths just preceeding, we established the following invariant:
12268 // IV can be assumed not to overflow up to and including the exiting
12269 // iteration. We proved this in one of two ways:
12270 // 1) We can show overflow doesn't occur before the exiting iteration
12271 // 1a) canIVOverflowOnLT, and b) step of one
12272 // 2) We can show that if overflow occurs, the loop must execute UB
12273 // before any possible exit.
12274 // Note that we have not yet proved RHS invariant (in general).
12275
12276 const SCEV *Start = IV->getStart();
12277
12278 // Preserve pointer-typed Start/RHS to pass to isLoopEntryGuardedByCond.
12279 // If we convert to integers, isLoopEntryGuardedByCond will miss some cases.
12280 // Use integer-typed versions for actual computation; we can't subtract
12281 // pointers in general.
12282 const SCEV *OrigStart = Start;
12283 const SCEV *OrigRHS = RHS;
12284 if (Start->getType()->isPointerTy()) {
12285 Start = getLosslessPtrToIntExpr(Start);
12286 if (isa<SCEVCouldNotCompute>(Start))
12287 return Start;
12288 }
12289 if (RHS->getType()->isPointerTy()) {
12290 RHS = getLosslessPtrToIntExpr(RHS);
12291 if (isa<SCEVCouldNotCompute>(RHS))
12292 return RHS;
12293 }
12294
12295 // When the RHS is not invariant, we do not know the end bound of the loop and
12296 // cannot calculate the ExactBECount needed by ExitLimit. However, we can
12297 // calculate the MaxBECount, given the start, stride and max value for the end
12298 // bound of the loop (RHS), and the fact that IV does not overflow (which is
12299 // checked above).
12300 if (!isLoopInvariant(RHS, L)) {
12301 const SCEV *MaxBECount = computeMaxBECountForLT(
12302 Start, Stride, RHS, getTypeSizeInBits(LHS->getType()), IsSigned);
12303 return ExitLimit(getCouldNotCompute() /* ExactNotTaken */, MaxBECount,
12304 false /*MaxOrZero*/, Predicates);
12305 }
12306
12307 // We use the expression (max(End,Start)-Start)/Stride to describe the
12308 // backedge count, as if the backedge is taken at least once max(End,Start)
12309 // is End and so the result is as above, and if not max(End,Start) is Start
12310 // so we get a backedge count of zero.
12311 const SCEV *BECount = nullptr;
12312 auto *OrigStartMinusStride = getMinusSCEV(OrigStart, Stride);
12313 assert(isAvailableAtLoopEntry(OrigStartMinusStride, L) && "Must be!")(static_cast <bool> (isAvailableAtLoopEntry(OrigStartMinusStride
, L) && "Must be!") ? void (0) : __assert_fail ("isAvailableAtLoopEntry(OrigStartMinusStride, L) && \"Must be!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12313, __extension__
__PRETTY_FUNCTION__));
12314 assert(isAvailableAtLoopEntry(OrigStart, L) && "Must be!")(static_cast <bool> (isAvailableAtLoopEntry(OrigStart, L
) && "Must be!") ? void (0) : __assert_fail ("isAvailableAtLoopEntry(OrigStart, L) && \"Must be!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12314, __extension__
__PRETTY_FUNCTION__));
12315 assert(isAvailableAtLoopEntry(OrigRHS, L) && "Must be!")(static_cast <bool> (isAvailableAtLoopEntry(OrigRHS, L)
&& "Must be!") ? void (0) : __assert_fail ("isAvailableAtLoopEntry(OrigRHS, L) && \"Must be!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12315, __extension__
__PRETTY_FUNCTION__));
12316 // Can we prove (max(RHS,Start) > Start - Stride?
12317 if (isLoopEntryGuardedByCond(L, Cond, OrigStartMinusStride, OrigStart) &&
12318 isLoopEntryGuardedByCond(L, Cond, OrigStartMinusStride, OrigRHS)) {
12319 // In this case, we can use a refined formula for computing backedge taken
12320 // count. The general formula remains:
12321 // "End-Start /uceiling Stride" where "End = max(RHS,Start)"
12322 // We want to use the alternate formula:
12323 // "((End - 1) - (Start - Stride)) /u Stride"
12324 // Let's do a quick case analysis to show these are equivalent under
12325 // our precondition that max(RHS,Start) > Start - Stride.
12326 // * For RHS <= Start, the backedge-taken count must be zero.
12327 // "((End - 1) - (Start - Stride)) /u Stride" reduces to
12328 // "((Start - 1) - (Start - Stride)) /u Stride" which simplies to
12329 // "Stride - 1 /u Stride" which is indeed zero for all non-zero values
12330 // of Stride. For 0 stride, we've use umin(1,Stride) above, reducing
12331 // this to the stride of 1 case.
12332 // * For RHS >= Start, the backedge count must be "RHS-Start /uceil Stride".
12333 // "((End - 1) - (Start - Stride)) /u Stride" reduces to
12334 // "((RHS - 1) - (Start - Stride)) /u Stride" reassociates to
12335 // "((RHS - (Start - Stride) - 1) /u Stride".
12336 // Our preconditions trivially imply no overflow in that form.
12337 const SCEV *MinusOne = getMinusOne(Stride->getType());
12338 const SCEV *Numerator =
12339 getMinusSCEV(getAddExpr(RHS, MinusOne), getMinusSCEV(Start, Stride));
12340 BECount = getUDivExpr(Numerator, Stride);
12341 }
12342
12343 const SCEV *BECountIfBackedgeTaken = nullptr;
12344 if (!BECount) {
12345 auto canProveRHSGreaterThanEqualStart = [&]() {
12346 auto CondGE = IsSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
12347 if (isLoopEntryGuardedByCond(L, CondGE, OrigRHS, OrigStart))
12348 return true;
12349
12350 // (RHS > Start - 1) implies RHS >= Start.
12351 // * "RHS >= Start" is trivially equivalent to "RHS > Start - 1" if
12352 // "Start - 1" doesn't overflow.
12353 // * For signed comparison, if Start - 1 does overflow, it's equal
12354 // to INT_MAX, and "RHS >s INT_MAX" is trivially false.
12355 // * For unsigned comparison, if Start - 1 does overflow, it's equal
12356 // to UINT_MAX, and "RHS >u UINT_MAX" is trivially false.
12357 //
12358 // FIXME: Should isLoopEntryGuardedByCond do this for us?
12359 auto CondGT = IsSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
12360 auto *StartMinusOne = getAddExpr(OrigStart,
12361 getMinusOne(OrigStart->getType()));
12362 return isLoopEntryGuardedByCond(L, CondGT, OrigRHS, StartMinusOne);
12363 };
12364
12365 // If we know that RHS >= Start in the context of loop, then we know that
12366 // max(RHS, Start) = RHS at this point.
12367 const SCEV *End;
12368 if (canProveRHSGreaterThanEqualStart()) {
12369 End = RHS;
12370 } else {
12371 // If RHS < Start, the backedge will be taken zero times. So in
12372 // general, we can write the backedge-taken count as:
12373 //
12374 // RHS >= Start ? ceil(RHS - Start) / Stride : 0
12375 //
12376 // We convert it to the following to make it more convenient for SCEV:
12377 //
12378 // ceil(max(RHS, Start) - Start) / Stride
12379 End = IsSigned ? getSMaxExpr(RHS, Start) : getUMaxExpr(RHS, Start);
12380
12381 // See what would happen if we assume the backedge is taken. This is
12382 // used to compute MaxBECount.
12383 BECountIfBackedgeTaken = getUDivCeilSCEV(getMinusSCEV(RHS, Start), Stride);
12384 }
12385
12386 // At this point, we know:
12387 //
12388 // 1. If IsSigned, Start <=s End; otherwise, Start <=u End
12389 // 2. The index variable doesn't overflow.
12390 //
12391 // Therefore, we know N exists such that
12392 // (Start + Stride * N) >= End, and computing "(Start + Stride * N)"
12393 // doesn't overflow.
12394 //
12395 // Using this information, try to prove whether the addition in
12396 // "(Start - End) + (Stride - 1)" has unsigned overflow.
12397 const SCEV *One = getOne(Stride->getType());
12398 bool MayAddOverflow = [&] {
12399 if (auto *StrideC = dyn_cast<SCEVConstant>(Stride)) {
12400 if (StrideC->getAPInt().isPowerOf2()) {
12401 // Suppose Stride is a power of two, and Start/End are unsigned
12402 // integers. Let UMAX be the largest representable unsigned
12403 // integer.
12404 //
12405 // By the preconditions of this function, we know
12406 // "(Start + Stride * N) >= End", and this doesn't overflow.
12407 // As a formula:
12408 //
12409 // End <= (Start + Stride * N) <= UMAX
12410 //
12411 // Subtracting Start from all the terms:
12412 //
12413 // End - Start <= Stride * N <= UMAX - Start
12414 //
12415 // Since Start is unsigned, UMAX - Start <= UMAX. Therefore:
12416 //
12417 // End - Start <= Stride * N <= UMAX
12418 //
12419 // Stride * N is a multiple of Stride. Therefore,
12420 //
12421 // End - Start <= Stride * N <= UMAX - (UMAX mod Stride)
12422 //
12423 // Since Stride is a power of two, UMAX + 1 is divisible by Stride.
12424 // Therefore, UMAX mod Stride == Stride - 1. So we can write:
12425 //
12426 // End - Start <= Stride * N <= UMAX - Stride - 1
12427 //
12428 // Dropping the middle term:
12429 //
12430 // End - Start <= UMAX - Stride - 1
12431 //
12432 // Adding Stride - 1 to both sides:
12433 //
12434 // (End - Start) + (Stride - 1) <= UMAX
12435 //
12436 // In other words, the addition doesn't have unsigned overflow.
12437 //
12438 // A similar proof works if we treat Start/End as signed values.
12439 // Just rewrite steps before "End - Start <= Stride * N <= UMAX" to
12440 // use signed max instead of unsigned max. Note that we're trying
12441 // to prove a lack of unsigned overflow in either case.
12442 return false;
12443 }
12444 }
12445 if (Start == Stride || Start == getMinusSCEV(Stride, One)) {
12446 // If Start is equal to Stride, (End - Start) + (Stride - 1) == End - 1.
12447 // If !IsSigned, 0 <u Stride == Start <=u End; so 0 <u End - 1 <u End.
12448 // If IsSigned, 0 <s Stride == Start <=s End; so 0 <s End - 1 <s End.
12449 //
12450 // If Start is equal to Stride - 1, (End - Start) + Stride - 1 == End.
12451 return false;
12452 }
12453 return true;
12454 }();
12455
12456 const SCEV *Delta = getMinusSCEV(End, Start);
12457 if (!MayAddOverflow) {
12458 // floor((D + (S - 1)) / S)
12459 // We prefer this formulation if it's legal because it's fewer operations.
12460 BECount =
12461 getUDivExpr(getAddExpr(Delta, getMinusSCEV(Stride, One)), Stride);
12462 } else {
12463 BECount = getUDivCeilSCEV(Delta, Stride);
12464 }
12465 }
12466
12467 const SCEV *MaxBECount;
12468 bool MaxOrZero = false;
12469 if (isa<SCEVConstant>(BECount)) {
12470 MaxBECount = BECount;
12471 } else if (BECountIfBackedgeTaken &&
12472 isa<SCEVConstant>(BECountIfBackedgeTaken)) {
12473 // If we know exactly how many times the backedge will be taken if it's
12474 // taken at least once, then the backedge count will either be that or
12475 // zero.
12476 MaxBECount = BECountIfBackedgeTaken;
12477 MaxOrZero = true;
12478 } else {
12479 MaxBECount = computeMaxBECountForLT(
12480 Start, Stride, RHS, getTypeSizeInBits(LHS->getType()), IsSigned);
12481 }
12482
12483 if (isa<SCEVCouldNotCompute>(MaxBECount) &&
12484 !isa<SCEVCouldNotCompute>(BECount))
12485 MaxBECount = getConstant(getUnsignedRangeMax(BECount));
12486
12487 return ExitLimit(BECount, MaxBECount, MaxOrZero, Predicates);
12488}
12489
12490ScalarEvolution::ExitLimit
12491ScalarEvolution::howManyGreaterThans(const SCEV *LHS, const SCEV *RHS,
12492 const Loop *L, bool IsSigned,
12493 bool ControlsExit, bool AllowPredicates) {
12494 SmallPtrSet<const SCEVPredicate *, 4> Predicates;
12495 // We handle only IV > Invariant
12496 if (!isLoopInvariant(RHS, L))
12497 return getCouldNotCompute();
12498
12499 const SCEVAddRecExpr *IV = dyn_cast<SCEVAddRecExpr>(LHS);
12500 if (!IV && AllowPredicates)
12501 // Try to make this an AddRec using runtime tests, in the first X
12502 // iterations of this loop, where X is the SCEV expression found by the
12503 // algorithm below.
12504 IV = convertSCEVToAddRecWithPredicates(LHS, L, Predicates);
12505
12506 // Avoid weird loops
12507 if (!IV || IV->getLoop() != L || !IV->isAffine())
12508 return getCouldNotCompute();
12509
12510 auto WrapType = IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW;
12511 bool NoWrap = ControlsExit && IV->getNoWrapFlags(WrapType);
12512 ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
12513
12514 const SCEV *Stride = getNegativeSCEV(IV->getStepRecurrence(*this));
12515
12516 // Avoid negative or zero stride values
12517 if (!isKnownPositive(Stride))
12518 return getCouldNotCompute();
12519
12520 // Avoid proven overflow cases: this will ensure that the backedge taken count
12521 // will not generate any unsigned overflow. Relaxed no-overflow conditions
12522 // exploit NoWrapFlags, allowing to optimize in presence of undefined
12523 // behaviors like the case of C language.
12524 if (!Stride->isOne() && !NoWrap)
12525 if (canIVOverflowOnGT(RHS, Stride, IsSigned))
12526 return getCouldNotCompute();
12527
12528 const SCEV *Start = IV->getStart();
12529 const SCEV *End = RHS;
12530 if (!isLoopEntryGuardedByCond(L, Cond, getAddExpr(Start, Stride), RHS)) {
12531 // If we know that Start >= RHS in the context of loop, then we know that
12532 // min(RHS, Start) = RHS at this point.
12533 if (isLoopEntryGuardedByCond(
12534 L, IsSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE, Start, RHS))
12535 End = RHS;
12536 else
12537 End = IsSigned ? getSMinExpr(RHS, Start) : getUMinExpr(RHS, Start);
12538 }
12539
12540 if (Start->getType()->isPointerTy()) {
12541 Start = getLosslessPtrToIntExpr(Start);
12542 if (isa<SCEVCouldNotCompute>(Start))
12543 return Start;
12544 }
12545 if (End->getType()->isPointerTy()) {
12546 End = getLosslessPtrToIntExpr(End);
12547 if (isa<SCEVCouldNotCompute>(End))
12548 return End;
12549 }
12550
12551 // Compute ((Start - End) + (Stride - 1)) / Stride.
12552 // FIXME: This can overflow. Holding off on fixing this for now;
12553 // howManyGreaterThans will hopefully be gone soon.
12554 const SCEV *One = getOne(Stride->getType());
12555 const SCEV *BECount = getUDivExpr(
12556 getAddExpr(getMinusSCEV(Start, End), getMinusSCEV(Stride, One)), Stride);
12557
12558 APInt MaxStart = IsSigned ? getSignedRangeMax(Start)
12559 : getUnsignedRangeMax(Start);
12560
12561 APInt MinStride = IsSigned ? getSignedRangeMin(Stride)
12562 : getUnsignedRangeMin(Stride);
12563
12564 unsigned BitWidth = getTypeSizeInBits(LHS->getType());
12565 APInt Limit = IsSigned ? APInt::getSignedMinValue(BitWidth) + (MinStride - 1)
12566 : APInt::getMinValue(BitWidth) + (MinStride - 1);
12567
12568 // Although End can be a MIN expression we estimate MinEnd considering only
12569 // the case End = RHS. This is safe because in the other case (Start - End)
12570 // is zero, leading to a zero maximum backedge taken count.
12571 APInt MinEnd =
12572 IsSigned ? APIntOps::smax(getSignedRangeMin(RHS), Limit)
12573 : APIntOps::umax(getUnsignedRangeMin(RHS), Limit);
12574
12575 const SCEV *MaxBECount = isa<SCEVConstant>(BECount)
12576 ? BECount
12577 : getUDivCeilSCEV(getConstant(MaxStart - MinEnd),
12578 getConstant(MinStride));
12579
12580 if (isa<SCEVCouldNotCompute>(MaxBECount))
12581 MaxBECount = BECount;
12582
12583 return ExitLimit(BECount, MaxBECount, false, Predicates);
12584}
12585
12586const SCEV *SCEVAddRecExpr::getNumIterationsInRange(const ConstantRange &Range,
12587 ScalarEvolution &SE) const {
12588 if (Range.isFullSet()) // Infinite loop.
12589 return SE.getCouldNotCompute();
12590
12591 // If the start is a non-zero constant, shift the range to simplify things.
12592 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(getStart()))
12593 if (!SC->getValue()->isZero()) {
12594 SmallVector<const SCEV *, 4> Operands(operands());
12595 Operands[0] = SE.getZero(SC->getType());
12596 const SCEV *Shifted = SE.getAddRecExpr(Operands, getLoop(),
12597 getNoWrapFlags(FlagNW));
12598 if (const auto *ShiftedAddRec = dyn_cast<SCEVAddRecExpr>(Shifted))
12599 return ShiftedAddRec->getNumIterationsInRange(
12600 Range.subtract(SC->getAPInt()), SE);
12601 // This is strange and shouldn't happen.
12602 return SE.getCouldNotCompute();
12603 }
12604
12605 // The only time we can solve this is when we have all constant indices.
12606 // Otherwise, we cannot determine the overflow conditions.
12607 if (any_of(operands(), [](const SCEV *Op) { return !isa<SCEVConstant>(Op); }))
12608 return SE.getCouldNotCompute();
12609
12610 // Okay at this point we know that all elements of the chrec are constants and
12611 // that the start element is zero.
12612
12613 // First check to see if the range contains zero. If not, the first
12614 // iteration exits.
12615 unsigned BitWidth = SE.getTypeSizeInBits(getType());
12616 if (!Range.contains(APInt(BitWidth, 0)))
12617 return SE.getZero(getType());
12618
12619 if (isAffine()) {
12620 // If this is an affine expression then we have this situation:
12621 // Solve {0,+,A} in Range === Ax in Range
12622
12623 // We know that zero is in the range. If A is positive then we know that
12624 // the upper value of the range must be the first possible exit value.
12625 // If A is negative then the lower of the range is the last possible loop
12626 // value. Also note that we already checked for a full range.
12627 APInt A = cast<SCEVConstant>(getOperand(1))->getAPInt();
12628 APInt End = A.sge(1) ? (Range.getUpper() - 1) : Range.getLower();
12629
12630 // The exit value should be (End+A)/A.
12631 APInt ExitVal = (End + A).udiv(A);
12632 ConstantInt *ExitValue = ConstantInt::get(SE.getContext(), ExitVal);
12633
12634 // Evaluate at the exit value. If we really did fall out of the valid
12635 // range, then we computed our trip count, otherwise wrap around or other
12636 // things must have happened.
12637 ConstantInt *Val = EvaluateConstantChrecAtConstant(this, ExitValue, SE);
12638 if (Range.contains(Val->getValue()))
12639 return SE.getCouldNotCompute(); // Something strange happened
12640
12641 // Ensure that the previous value is in the range.
12642 assert(Range.contains((static_cast <bool> (Range.contains( EvaluateConstantChrecAtConstant
(this, ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->
getValue()) && "Linear scev computation is off in a bad way!"
) ? void (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && \"Linear scev computation is off in a bad way!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12645, __extension__
__PRETTY_FUNCTION__))
12643 EvaluateConstantChrecAtConstant(this,(static_cast <bool> (Range.contains( EvaluateConstantChrecAtConstant
(this, ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->
getValue()) && "Linear scev computation is off in a bad way!"
) ? void (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && \"Linear scev computation is off in a bad way!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12645, __extension__
__PRETTY_FUNCTION__))
12644 ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->getValue()) &&(static_cast <bool> (Range.contains( EvaluateConstantChrecAtConstant
(this, ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->
getValue()) && "Linear scev computation is off in a bad way!"
) ? void (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && \"Linear scev computation is off in a bad way!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12645, __extension__
__PRETTY_FUNCTION__))
12645 "Linear scev computation is off in a bad way!")(static_cast <bool> (Range.contains( EvaluateConstantChrecAtConstant
(this, ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->
getValue()) && "Linear scev computation is off in a bad way!"
) ? void (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && \"Linear scev computation is off in a bad way!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12645, __extension__
__PRETTY_FUNCTION__));
12646 return SE.getConstant(ExitValue);
12647 }
12648
12649 if (isQuadratic()) {
12650 if (auto S = SolveQuadraticAddRecRange(this, Range, SE))
12651 return SE.getConstant(S.getValue());
12652 }
12653
12654 return SE.getCouldNotCompute();
12655}
12656
12657const SCEVAddRecExpr *
12658SCEVAddRecExpr::getPostIncExpr(ScalarEvolution &SE) const {
12659 assert(getNumOperands() > 1 && "AddRec with zero step?")(static_cast <bool> (getNumOperands() > 1 &&
"AddRec with zero step?") ? void (0) : __assert_fail ("getNumOperands() > 1 && \"AddRec with zero step?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12659, __extension__
__PRETTY_FUNCTION__));
12660 // There is a temptation to just call getAddExpr(this, getStepRecurrence(SE)),
12661 // but in this case we cannot guarantee that the value returned will be an
12662 // AddRec because SCEV does not have a fixed point where it stops
12663 // simplification: it is legal to return ({rec1} + {rec2}). For example, it
12664 // may happen if we reach arithmetic depth limit while simplifying. So we
12665 // construct the returned value explicitly.
12666 SmallVector<const SCEV *, 3> Ops;
12667 // If this is {A,+,B,+,C,...,+,N}, then its step is {B,+,C,+,...,+,N}, and
12668 // (this + Step) is {A+B,+,B+C,+...,+,N}.
12669 for (unsigned i = 0, e = getNumOperands() - 1; i < e; ++i)
12670 Ops.push_back(SE.getAddExpr(getOperand(i), getOperand(i + 1)));
12671 // We know that the last operand is not a constant zero (otherwise it would
12672 // have been popped out earlier). This guarantees us that if the result has
12673 // the same last operand, then it will also not be popped out, meaning that
12674 // the returned value will be an AddRec.
12675 const SCEV *Last = getOperand(getNumOperands() - 1);
12676 assert(!Last->isZero() && "Recurrency with zero step?")(static_cast <bool> (!Last->isZero() && "Recurrency with zero step?"
) ? void (0) : __assert_fail ("!Last->isZero() && \"Recurrency with zero step?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12676, __extension__
__PRETTY_FUNCTION__));
12677 Ops.push_back(Last);
12678 return cast<SCEVAddRecExpr>(SE.getAddRecExpr(Ops, getLoop(),
12679 SCEV::FlagAnyWrap));
12680}
12681
12682// Return true when S contains at least an undef value.
12683bool ScalarEvolution::containsUndefs(const SCEV *S) const {
12684 return SCEVExprContains(S, [](const SCEV *S) {
12685 if (const auto *SU = dyn_cast<SCEVUnknown>(S))
12686 return isa<UndefValue>(SU->getValue());
12687 return false;
12688 });
12689}
12690
12691/// Return the size of an element read or written by Inst.
12692const SCEV *ScalarEvolution::getElementSize(Instruction *Inst) {
12693 Type *Ty;
12694 if (StoreInst *Store = dyn_cast<StoreInst>(Inst))
12695 Ty = Store->getValueOperand()->getType();
12696 else if (LoadInst *Load = dyn_cast<LoadInst>(Inst))
12697 Ty = Load->getType();
12698 else
12699 return nullptr;
12700
12701 Type *ETy = getEffectiveSCEVType(PointerType::getUnqual(Ty));
12702 return getSizeOfExpr(ETy, Ty);
12703}
12704
12705//===----------------------------------------------------------------------===//
12706// SCEVCallbackVH Class Implementation
12707//===----------------------------------------------------------------------===//
12708
12709void ScalarEvolution::SCEVCallbackVH::deleted() {
12710 assert(SE && "SCEVCallbackVH called with a null ScalarEvolution!")(static_cast <bool> (SE && "SCEVCallbackVH called with a null ScalarEvolution!"
) ? void (0) : __assert_fail ("SE && \"SCEVCallbackVH called with a null ScalarEvolution!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12710, __extension__
__PRETTY_FUNCTION__));
12711 if (PHINode *PN = dyn_cast<PHINode>(getValPtr()))
12712 SE->ConstantEvolutionLoopExitValue.erase(PN);
12713 SE->eraseValueFromMap(getValPtr());
12714 // this now dangles!
12715}
12716
12717void ScalarEvolution::SCEVCallbackVH::allUsesReplacedWith(Value *V) {
12718 assert(SE && "SCEVCallbackVH called with a null ScalarEvolution!")(static_cast <bool> (SE && "SCEVCallbackVH called with a null ScalarEvolution!"
) ? void (0) : __assert_fail ("SE && \"SCEVCallbackVH called with a null ScalarEvolution!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12718, __extension__
__PRETTY_FUNCTION__));
12719
12720 // Forget all the expressions associated with users of the old value,
12721 // so that future queries will recompute the expressions using the new
12722 // value.
12723 Value *Old = getValPtr();
12724 SmallVector<User *, 16> Worklist(Old->users());
12725 SmallPtrSet<User *, 8> Visited;
12726 while (!Worklist.empty()) {
12727 User *U = Worklist.pop_back_val();
12728 // Deleting the Old value will cause this to dangle. Postpone
12729 // that until everything else is done.
12730 if (U == Old)
12731 continue;
12732 if (!Visited.insert(U).second)
12733 continue;
12734 if (PHINode *PN = dyn_cast<PHINode>(U))
12735 SE->ConstantEvolutionLoopExitValue.erase(PN);
12736 SE->eraseValueFromMap(U);
12737 llvm::append_range(Worklist, U->users());
12738 }
12739 // Delete the Old value.
12740 if (PHINode *PN = dyn_cast<PHINode>(Old))
12741 SE->ConstantEvolutionLoopExitValue.erase(PN);
12742 SE->eraseValueFromMap(Old);
12743 // this now dangles!
12744}
12745
12746ScalarEvolution::SCEVCallbackVH::SCEVCallbackVH(Value *V, ScalarEvolution *se)
12747 : CallbackVH(V), SE(se) {}
12748
12749//===----------------------------------------------------------------------===//
12750// ScalarEvolution Class Implementation
12751//===----------------------------------------------------------------------===//
12752
12753ScalarEvolution::ScalarEvolution(Function &F, TargetLibraryInfo &TLI,
12754 AssumptionCache &AC, DominatorTree &DT,
12755 LoopInfo &LI)
12756 : F(F), TLI(TLI), AC(AC), DT(DT), LI(LI),
12757 CouldNotCompute(new SCEVCouldNotCompute()), ValuesAtScopes(64),
12758 LoopDispositions(64), BlockDispositions(64) {
12759 // To use guards for proving predicates, we need to scan every instruction in
12760 // relevant basic blocks, and not just terminators. Doing this is a waste of
12761 // time if the IR does not actually contain any calls to
12762 // @llvm.experimental.guard, so do a quick check and remember this beforehand.
12763 //
12764 // This pessimizes the case where a pass that preserves ScalarEvolution wants
12765 // to _add_ guards to the module when there weren't any before, and wants
12766 // ScalarEvolution to optimize based on those guards. For now we prefer to be
12767 // efficient in lieu of being smart in that rather obscure case.
12768
12769 auto *GuardDecl = F.getParent()->getFunction(
12770 Intrinsic::getName(Intrinsic::experimental_guard));
12771 HasGuards = GuardDecl && !GuardDecl->use_empty();
12772}
12773
12774ScalarEvolution::ScalarEvolution(ScalarEvolution &&Arg)
12775 : F(Arg.F), HasGuards(Arg.HasGuards), TLI(Arg.TLI), AC(Arg.AC), DT(Arg.DT),
12776 LI(Arg.LI), CouldNotCompute(std::move(Arg.CouldNotCompute)),
12777 ValueExprMap(std::move(Arg.ValueExprMap)),
12778 PendingLoopPredicates(std::move(Arg.PendingLoopPredicates)),
12779 PendingPhiRanges(std::move(Arg.PendingPhiRanges)),
12780 PendingMerges(std::move(Arg.PendingMerges)),
12781 MinTrailingZerosCache(std::move(Arg.MinTrailingZerosCache)),
12782 BackedgeTakenCounts(std::move(Arg.BackedgeTakenCounts)),
12783 PredicatedBackedgeTakenCounts(
12784 std::move(Arg.PredicatedBackedgeTakenCounts)),
12785 BECountUsers(std::move(Arg.BECountUsers)),
12786 ConstantEvolutionLoopExitValue(
12787 std::move(Arg.ConstantEvolutionLoopExitValue)),
12788 ValuesAtScopes(std::move(Arg.ValuesAtScopes)),
12789 ValuesAtScopesUsers(std::move(Arg.ValuesAtScopesUsers)),
12790 LoopDispositions(std::move(Arg.LoopDispositions)),
12791 LoopPropertiesCache(std::move(Arg.LoopPropertiesCache)),
12792 BlockDispositions(std::move(Arg.BlockDispositions)),
12793 SCEVUsers(std::move(Arg.SCEVUsers)),
12794 UnsignedRanges(std::move(Arg.UnsignedRanges)),
12795 SignedRanges(std::move(Arg.SignedRanges)),
12796 UniqueSCEVs(std::move(Arg.UniqueSCEVs)),
12797 UniquePreds(std::move(Arg.UniquePreds)),
12798 SCEVAllocator(std::move(Arg.SCEVAllocator)),
12799 LoopUsers(std::move(Arg.LoopUsers)),
12800 PredicatedSCEVRewrites(std::move(Arg.PredicatedSCEVRewrites)),
12801 FirstUnknown(Arg.FirstUnknown) {
12802 Arg.FirstUnknown = nullptr;
12803}
12804
12805ScalarEvolution::~ScalarEvolution() {
12806 // Iterate through all the SCEVUnknown instances and call their
12807 // destructors, so that they release their references to their values.
12808 for (SCEVUnknown *U = FirstUnknown; U;) {
12809 SCEVUnknown *Tmp = U;
12810 U = U->Next;
12811 Tmp->~SCEVUnknown();
12812 }
12813 FirstUnknown = nullptr;
12814
12815 ExprValueMap.clear();
12816 ValueExprMap.clear();
12817 HasRecMap.clear();
12818 BackedgeTakenCounts.clear();
12819 PredicatedBackedgeTakenCounts.clear();
12820
12821 assert(PendingLoopPredicates.empty() && "isImpliedCond garbage")(static_cast <bool> (PendingLoopPredicates.empty() &&
"isImpliedCond garbage") ? void (0) : __assert_fail ("PendingLoopPredicates.empty() && \"isImpliedCond garbage\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12821, __extension__
__PRETTY_FUNCTION__));
12822 assert(PendingPhiRanges.empty() && "getRangeRef garbage")(static_cast <bool> (PendingPhiRanges.empty() &&
"getRangeRef garbage") ? void (0) : __assert_fail ("PendingPhiRanges.empty() && \"getRangeRef garbage\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12822, __extension__
__PRETTY_FUNCTION__));
12823 assert(PendingMerges.empty() && "isImpliedViaMerge garbage")(static_cast <bool> (PendingMerges.empty() && "isImpliedViaMerge garbage"
) ? void (0) : __assert_fail ("PendingMerges.empty() && \"isImpliedViaMerge garbage\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12823, __extension__
__PRETTY_FUNCTION__));
12824 assert(!WalkingBEDominatingConds && "isLoopBackedgeGuardedByCond garbage!")(static_cast <bool> (!WalkingBEDominatingConds &&
"isLoopBackedgeGuardedByCond garbage!") ? void (0) : __assert_fail
("!WalkingBEDominatingConds && \"isLoopBackedgeGuardedByCond garbage!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12824, __extension__
__PRETTY_FUNCTION__));
12825 assert(!ProvingSplitPredicate && "ProvingSplitPredicate garbage!")(static_cast <bool> (!ProvingSplitPredicate && "ProvingSplitPredicate garbage!"
) ? void (0) : __assert_fail ("!ProvingSplitPredicate && \"ProvingSplitPredicate garbage!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12825, __extension__
__PRETTY_FUNCTION__));
12826}
12827
12828bool ScalarEvolution::hasLoopInvariantBackedgeTakenCount(const Loop *L) {
12829 return !isa<SCEVCouldNotCompute>(getBackedgeTakenCount(L));
12830}
12831
12832static void PrintLoopInfo(raw_ostream &OS, ScalarEvolution *SE,
12833 const Loop *L) {
12834 // Print all inner loops first
12835 for (Loop *I : *L)
12836 PrintLoopInfo(OS, SE, I);
12837
12838 OS << "Loop ";
12839 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
12840 OS << ": ";
12841
12842 SmallVector<BasicBlock *, 8> ExitingBlocks;
12843 L->getExitingBlocks(ExitingBlocks);
12844 if (ExitingBlocks.size() != 1)
12845 OS << "<multiple exits> ";
12846
12847 if (SE->hasLoopInvariantBackedgeTakenCount(L))
12848 OS << "backedge-taken count is " << *SE->getBackedgeTakenCount(L) << "\n";
12849 else
12850 OS << "Unpredictable backedge-taken count.\n";
12851
12852 if (ExitingBlocks.size() > 1)
12853 for (BasicBlock *ExitingBlock : ExitingBlocks) {
12854 OS << " exit count for " << ExitingBlock->getName() << ": "
12855 << *SE->getExitCount(L, ExitingBlock) << "\n";
12856 }
12857
12858 OS << "Loop ";
12859 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
12860 OS << ": ";
12861
12862 if (!isa<SCEVCouldNotCompute>(SE->getConstantMaxBackedgeTakenCount(L))) {
12863 OS << "max backedge-taken count is " << *SE->getConstantMaxBackedgeTakenCount(L);
12864 if (SE->isBackedgeTakenCountMaxOrZero(L))
12865 OS << ", actual taken count either this or zero.";
12866 } else {
12867 OS << "Unpredictable max backedge-taken count. ";
12868 }
12869
12870 OS << "\n"
12871 "Loop ";
12872 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
12873 OS << ": ";
12874
12875 SmallVector<const SCEVPredicate *, 4> Preds;
12876 auto PBT = SE->getPredicatedBackedgeTakenCount(L, Preds);
12877 if (!isa<SCEVCouldNotCompute>(PBT)) {
12878 OS << "Predicated backedge-taken count is " << *PBT << "\n";
12879 OS << " Predicates:\n";
12880 for (auto *P : Preds)
12881 P->print(OS, 4);
12882 } else {
12883 OS << "Unpredictable predicated backedge-taken count. ";
12884 }
12885 OS << "\n";
12886
12887 if (SE->hasLoopInvariantBackedgeTakenCount(L)) {
12888 OS << "Loop ";
12889 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
12890 OS << ": ";
12891 OS << "Trip multiple is " << SE->getSmallConstantTripMultiple(L) << "\n";
12892 }
12893}
12894
12895static StringRef loopDispositionToStr(ScalarEvolution::LoopDisposition LD) {
12896 switch (LD) {
12897 case ScalarEvolution::LoopVariant:
12898 return "Variant";
12899 case ScalarEvolution::LoopInvariant:
12900 return "Invariant";
12901 case ScalarEvolution::LoopComputable:
12902 return "Computable";
12903 }
12904 llvm_unreachable("Unknown ScalarEvolution::LoopDisposition kind!")::llvm::llvm_unreachable_internal("Unknown ScalarEvolution::LoopDisposition kind!"
, "llvm/lib/Analysis/ScalarEvolution.cpp", 12904);
12905}
12906
12907void ScalarEvolution::print(raw_ostream &OS) const {
12908 // ScalarEvolution's implementation of the print method is to print
12909 // out SCEV values of all instructions that are interesting. Doing
12910 // this potentially causes it to create new SCEV objects though,
12911 // which technically conflicts with the const qualifier. This isn't
12912 // observable from outside the class though, so casting away the
12913 // const isn't dangerous.
12914 ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this);
12915
12916 if (ClassifyExpressions) {
12917 OS << "Classifying expressions for: ";
12918 F.printAsOperand(OS, /*PrintType=*/false);
12919 OS << "\n";
12920 for (Instruction &I : instructions(F))
12921 if (isSCEVable(I.getType()) && !isa<CmpInst>(I)) {
12922 OS << I << '\n';
12923 OS << " --> ";
12924 const SCEV *SV = SE.getSCEV(&I);
12925 SV->print(OS);
12926 if (!isa<SCEVCouldNotCompute>(SV)) {
12927 OS << " U: ";
12928 SE.getUnsignedRange(SV).print(OS);
12929 OS << " S: ";
12930 SE.getSignedRange(SV).print(OS);
12931 }
12932
12933 const Loop *L = LI.getLoopFor(I.getParent());
12934
12935 const SCEV *AtUse = SE.getSCEVAtScope(SV, L);
12936 if (AtUse != SV) {
12937 OS << " --> ";
12938 AtUse->print(OS);
12939 if (!isa<SCEVCouldNotCompute>(AtUse)) {
12940 OS << " U: ";
12941 SE.getUnsignedRange(AtUse).print(OS);
12942 OS << " S: ";
12943 SE.getSignedRange(AtUse).print(OS);
12944 }
12945 }
12946
12947 if (L) {
12948 OS << "\t\t" "Exits: ";
12949 const SCEV *ExitValue = SE.getSCEVAtScope(SV, L->getParentLoop());
12950 if (!SE.isLoopInvariant(ExitValue, L)) {
12951 OS << "<<Unknown>>";
12952 } else {
12953 OS << *ExitValue;
12954 }
12955
12956 bool First = true;
12957 for (auto *Iter = L; Iter; Iter = Iter->getParentLoop()) {
12958 if (First) {
12959 OS << "\t\t" "LoopDispositions: { ";
12960 First = false;
12961 } else {
12962 OS << ", ";
12963 }
12964
12965 Iter->getHeader()->printAsOperand(OS, /*PrintType=*/false);
12966 OS << ": " << loopDispositionToStr(SE.getLoopDisposition(SV, Iter));
12967 }
12968
12969 for (auto *InnerL : depth_first(L)) {
12970 if (InnerL == L)
12971 continue;
12972 if (First) {
12973 OS << "\t\t" "LoopDispositions: { ";
12974 First = false;
12975 } else {
12976 OS << ", ";
12977 }
12978
12979 InnerL->getHeader()->printAsOperand(OS, /*PrintType=*/false);
12980 OS << ": " << loopDispositionToStr(SE.getLoopDisposition(SV, InnerL));
12981 }
12982
12983 OS << " }";
12984 }
12985
12986 OS << "\n";
12987 }
12988 }
12989
12990 OS << "Determining loop execution counts for: ";
12991 F.printAsOperand(OS, /*PrintType=*/false);
12992 OS << "\n";
12993 for (Loop *I : LI)
12994 PrintLoopInfo(OS, &SE, I);
12995}
12996
12997ScalarEvolution::LoopDisposition
12998ScalarEvolution::getLoopDisposition(const SCEV *S, const Loop *L) {
12999 auto &Values = LoopDispositions[S];
13000 for (auto &V : Values) {
13001 if (V.getPointer() == L)
13002 return V.getInt();
13003 }
13004 Values.emplace_back(L, LoopVariant);
13005 LoopDisposition D = computeLoopDisposition(S, L);
13006 auto &Values2 = LoopDispositions[S];
13007 for (auto &V : llvm::reverse(Values2)) {
13008 if (V.getPointer() == L) {
13009 V.setInt(D);
13010 break;
13011 }
13012 }
13013 return D;
13014}
13015
13016ScalarEvolution::LoopDisposition
13017ScalarEvolution::computeLoopDisposition(const SCEV *S, const Loop *L) {
13018 switch (S->getSCEVType()) {
13019 case scConstant:
13020 return LoopInvariant;
13021 case scPtrToInt:
13022 case scTruncate:
13023 case scZeroExtend:
13024 case scSignExtend:
13025 return getLoopDisposition(cast<SCEVCastExpr>(S)->getOperand(), L);
13026 case scAddRecExpr: {
13027 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S);
13028
13029 // If L is the addrec's loop, it's computable.
13030 if (AR->getLoop() == L)
13031 return LoopComputable;
13032
13033 // Add recurrences are never invariant in the function-body (null loop).
13034 if (!L)
13035 return LoopVariant;
13036
13037 // Everything that is not defined at loop entry is variant.
13038 if (DT.dominates(L->getHeader(), AR->getLoop()->getHeader()))
13039 return LoopVariant;
13040 assert(!L->contains(AR->getLoop()) && "Containing loop's header does not"(static_cast <bool> (!L->contains(AR->getLoop()) &&
"Containing loop's header does not" " dominate the contained loop's header?"
) ? void (0) : __assert_fail ("!L->contains(AR->getLoop()) && \"Containing loop's header does not\" \" dominate the contained loop's header?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 13041, __extension__
__PRETTY_FUNCTION__))
13041 " dominate the contained loop's header?")(static_cast <bool> (!L->contains(AR->getLoop()) &&
"Containing loop's header does not" " dominate the contained loop's header?"
) ? void (0) : __assert_fail ("!L->contains(AR->getLoop()) && \"Containing loop's header does not\" \" dominate the contained loop's header?\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 13041, __extension__
__PRETTY_FUNCTION__));
13042
13043 // This recurrence is invariant w.r.t. L if AR's loop contains L.
13044 if (AR->getLoop()->contains(L))
13045 return LoopInvariant;
13046
13047 // This recurrence is variant w.r.t. L if any of its operands
13048 // are variant.
13049 for (auto *Op : AR->operands())
13050 if (!isLoopInvariant(Op, L))
13051 return LoopVariant;
13052
13053 // Otherwise it's loop-invariant.
13054 return LoopInvariant;
13055 }
13056 case scAddExpr:
13057 case scMulExpr:
13058 case scUMaxExpr:
13059 case scSMaxExpr:
13060 case scUMinExpr:
13061 case scSMinExpr:
13062 case scSequentialUMinExpr: {
13063 bool HasVarying = false;
13064 for (auto *Op : cast<SCEVNAryExpr>(S)->operands()) {
13065 LoopDisposition D = getLoopDisposition(Op, L);
13066 if (D == LoopVariant)
13067 return LoopVariant;
13068 if (D == LoopComputable)
13069 HasVarying = true;
13070 }
13071 return HasVarying ? LoopComputable : LoopInvariant;
13072 }
13073 case scUDivExpr: {
13074 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
13075 LoopDisposition LD = getLoopDisposition(UDiv->getLHS(), L);
13076 if (LD == LoopVariant)
13077 return LoopVariant;
13078 LoopDisposition RD = getLoopDisposition(UDiv->getRHS(), L);
13079 if (RD == LoopVariant)
13080 return LoopVariant;
13081 return (LD == LoopInvariant && RD == LoopInvariant) ?
13082 LoopInvariant : LoopComputable;
13083 }
13084 case scUnknown:
13085 // All non-instruction values are loop invariant. All instructions are loop
13086 // invariant if they are not contained in the specified loop.
13087 // Instructions are never considered invariant in the function body
13088 // (null loop) because they are defined within the "loop".
13089 if (auto *I = dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue()))
13090 return (L && !L->contains(I)) ? LoopInvariant : LoopVariant;
13091 return LoopInvariant;
13092 case scCouldNotCompute:
13093 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "llvm/lib/Analysis/ScalarEvolution.cpp", 13093);
13094 }
13095 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 13095);
13096}
13097
13098bool ScalarEvolution::isLoopInvariant(const SCEV *S, const Loop *L) {
13099 return getLoopDisposition(S, L) == LoopInvariant;
13100}
13101
13102bool ScalarEvolution::hasComputableLoopEvolution(const SCEV *S, const Loop *L) {
13103 return getLoopDisposition(S, L) == LoopComputable;
13104}
13105
13106ScalarEvolution::BlockDisposition
13107ScalarEvolution::getBlockDisposition(const SCEV *S, const BasicBlock *BB) {
13108 auto &Values = BlockDispositions[S];
13109 for (auto &V : Values) {
13110 if (V.getPointer() == BB)
13111 return V.getInt();
13112 }
13113 Values.emplace_back(BB, DoesNotDominateBlock);
13114 BlockDisposition D = computeBlockDisposition(S, BB);
13115 auto &Values2 = BlockDispositions[S];
13116 for (auto &V : llvm::reverse(Values2)) {
13117 if (V.getPointer() == BB) {
13118 V.setInt(D);
13119 break;
13120 }
13121 }
13122 return D;
13123}
13124
13125ScalarEvolution::BlockDisposition
13126ScalarEvolution::computeBlockDisposition(const SCEV *S, const BasicBlock *BB) {
13127 switch (S->getSCEVType()) {
13128 case scConstant:
13129 return ProperlyDominatesBlock;
13130 case scPtrToInt:
13131 case scTruncate:
13132 case scZeroExtend:
13133 case scSignExtend:
13134 return getBlockDisposition(cast<SCEVCastExpr>(S)->getOperand(), BB);
13135 case scAddRecExpr: {
13136 // This uses a "dominates" query instead of "properly dominates" query
13137 // to test for proper dominance too, because the instruction which
13138 // produces the addrec's value is a PHI, and a PHI effectively properly
13139 // dominates its entire containing block.
13140 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S);
13141 if (!DT.dominates(AR->getLoop()->getHeader(), BB))
13142 return DoesNotDominateBlock;
13143
13144 // Fall through into SCEVNAryExpr handling.
13145 LLVM_FALLTHROUGH[[gnu::fallthrough]];
13146 }
13147 case scAddExpr:
13148 case scMulExpr:
13149 case scUMaxExpr:
13150 case scSMaxExpr:
13151 case scUMinExpr:
13152 case scSMinExpr:
13153 case scSequentialUMinExpr: {
13154 const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(S);
13155 bool Proper = true;
13156 for (const SCEV *NAryOp : NAry->operands()) {
13157 BlockDisposition D = getBlockDisposition(NAryOp, BB);
13158 if (D == DoesNotDominateBlock)
13159 return DoesNotDominateBlock;
13160 if (D == DominatesBlock)
13161 Proper = false;
13162 }
13163 return Proper ? ProperlyDominatesBlock : DominatesBlock;
13164 }
13165 case scUDivExpr: {
13166 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
13167 const SCEV *LHS = UDiv->getLHS(), *RHS = UDiv->getRHS();
13168 BlockDisposition LD = getBlockDisposition(LHS, BB);
13169 if (LD == DoesNotDominateBlock)
13170 return DoesNotDominateBlock;
13171 BlockDisposition RD = getBlockDisposition(RHS, BB);
13172 if (RD == DoesNotDominateBlock)
13173 return DoesNotDominateBlock;
13174 return (LD == ProperlyDominatesBlock && RD == ProperlyDominatesBlock) ?
13175 ProperlyDominatesBlock : DominatesBlock;
13176 }
13177 case scUnknown:
13178 if (Instruction *I =
13179 dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue())) {
13180 if (I->getParent() == BB)
13181 return DominatesBlock;
13182 if (DT.properlyDominates(I->getParent(), BB))
13183 return ProperlyDominatesBlock;
13184 return DoesNotDominateBlock;
13185 }
13186 return ProperlyDominatesBlock;
13187 case scCouldNotCompute:
13188 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "llvm/lib/Analysis/ScalarEvolution.cpp", 13188);
13189 }
13190 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 13190);
13191}
13192
13193bool ScalarEvolution::dominates(const SCEV *S, const BasicBlock *BB) {
13194 return getBlockDisposition(S, BB) >= DominatesBlock;
13195}
13196
13197bool ScalarEvolution::properlyDominates(const SCEV *S, const BasicBlock *BB) {
13198 return getBlockDisposition(S, BB) == ProperlyDominatesBlock;
13199}
13200
13201bool ScalarEvolution::hasOperand(const SCEV *S, const SCEV *Op) const {
13202 return SCEVExprContains(S, [&](const SCEV *Expr) { return Expr == Op; });
13203}
13204
13205void ScalarEvolution::forgetBackedgeTakenCounts(const Loop *L,
13206 bool Predicated) {
13207 auto &BECounts =
13208 Predicated ? PredicatedBackedgeTakenCounts : BackedgeTakenCounts;
13209 auto It = BECounts.find(L);
13210 if (It != BECounts.end()) {
13211 for (const ExitNotTakenInfo &ENT : It->second.ExitNotTaken) {
13212 if (!isa<SCEVConstant>(ENT.ExactNotTaken)) {
13213 auto UserIt = BECountUsers.find(ENT.ExactNotTaken);
13214 assert(UserIt != BECountUsers.end())(static_cast <bool> (UserIt != BECountUsers.end()) ? void
(0) : __assert_fail ("UserIt != BECountUsers.end()", "llvm/lib/Analysis/ScalarEvolution.cpp"
, 13214, __extension__ __PRETTY_FUNCTION__));
13215 UserIt->second.erase({L, Predicated});
13216 }
13217 }
13218 BECounts.erase(It);
13219 }
13220}
13221
13222void ScalarEvolution::forgetMemoizedResults(ArrayRef<const SCEV *> SCEVs) {
13223 SmallPtrSet<const SCEV *, 8> ToForget(SCEVs.begin(), SCEVs.end());
13224 SmallVector<const SCEV *, 8> Worklist(ToForget.begin(), ToForget.end());
13225
13226 while (!Worklist.empty()) {
13227 const SCEV *Curr = Worklist.pop_back_val();
13228 auto Users = SCEVUsers.find(Curr);
13229 if (Users != SCEVUsers.end())
13230 for (auto *User : Users->second)
13231 if (ToForget.insert(User).second)
13232 Worklist.push_back(User);
13233 }
13234
13235 for (auto *S : ToForget)
13236 forgetMemoizedResultsImpl(S);
13237
13238 for (auto I = PredicatedSCEVRewrites.begin();
13239 I != PredicatedSCEVRewrites.end();) {
13240 std::pair<const SCEV *, const Loop *> Entry = I->first;
13241 if (ToForget.count(Entry.first))
13242 PredicatedSCEVRewrites.erase(I++);
13243 else
13244 ++I;
13245 }
13246}
13247
13248void ScalarEvolution::forgetMemoizedResultsImpl(const SCEV *S) {
13249 LoopDispositions.erase(S);
13250 BlockDispositions.erase(S);
13251 UnsignedRanges.erase(S);
13252 SignedRanges.erase(S);
13253 HasRecMap.erase(S);
13254 MinTrailingZerosCache.erase(S);
13255
13256 auto ExprIt = ExprValueMap.find(S);
13257 if (ExprIt != ExprValueMap.end()) {
13258 for (Value *V : ExprIt->second) {
13259 auto ValueIt = ValueExprMap.find_as(V);
13260 if (ValueIt != ValueExprMap.end())
13261 ValueExprMap.erase(ValueIt);
13262 }
13263 ExprValueMap.erase(ExprIt);
13264 }
13265
13266 auto ScopeIt = ValuesAtScopes.find(S);
13267 if (ScopeIt != ValuesAtScopes.end()) {
13268 for (const auto &Pair : ScopeIt->second)
13269 if (!isa_and_nonnull<SCEVConstant>(Pair.second))
13270 erase_value(ValuesAtScopesUsers[Pair.second],
13271 std::make_pair(Pair.first, S));
13272 ValuesAtScopes.erase(ScopeIt);
13273 }
13274
13275 auto ScopeUserIt = ValuesAtScopesUsers.find(S);
13276 if (ScopeUserIt != ValuesAtScopesUsers.end()) {
13277 for (const auto &Pair : ScopeUserIt->second)
13278 erase_value(ValuesAtScopes[Pair.second], std::make_pair(Pair.first, S));
13279 ValuesAtScopesUsers.erase(ScopeUserIt);
13280 }
13281
13282 auto BEUsersIt = BECountUsers.find(S);
13283 if (BEUsersIt != BECountUsers.end()) {
13284 // Work on a copy, as forgetBackedgeTakenCounts() will modify the original.
13285 auto Copy = BEUsersIt->second;
13286 for (const auto &Pair : Copy)
13287 forgetBackedgeTakenCounts(Pair.getPointer(), Pair.getInt());
13288 BECountUsers.erase(BEUsersIt);
13289 }
13290}
13291
13292void
13293ScalarEvolution::getUsedLoops(const SCEV *S,
13294 SmallPtrSetImpl<const Loop *> &LoopsUsed) {
13295 struct FindUsedLoops {
13296 FindUsedLoops(SmallPtrSetImpl<const Loop *> &LoopsUsed)
13297 : LoopsUsed(LoopsUsed) {}
13298 SmallPtrSetImpl<const Loop *> &LoopsUsed;
13299 bool follow(const SCEV *S) {
13300 if (auto *AR = dyn_cast<SCEVAddRecExpr>(S))
13301 LoopsUsed.insert(AR->getLoop());
13302 return true;
13303 }
13304
13305 bool isDone() const { return false; }
13306 };
13307
13308 FindUsedLoops F(LoopsUsed);
13309 SCEVTraversal<FindUsedLoops>(F).visitAll(S);
13310}
13311
13312void ScalarEvolution::getReachableBlocks(
13313 SmallPtrSetImpl<BasicBlock *> &Reachable, Function &F) {
13314 SmallVector<BasicBlock *> Worklist;
13315 Worklist.push_back(&F.getEntryBlock());
13316 while (!Worklist.empty()) {
13317 BasicBlock *BB = Worklist.pop_back_val();
13318 if (!Reachable.insert(BB).second)
13319 continue;
13320
13321 Value *Cond;
13322 BasicBlock *TrueBB, *FalseBB;
13323 if (match(BB->getTerminator(), m_Br(m_Value(Cond), m_BasicBlock(TrueBB),
13324 m_BasicBlock(FalseBB)))) {
13325 if (auto *C = dyn_cast<ConstantInt>(Cond)) {
13326 Worklist.push_back(C->isOne() ? TrueBB : FalseBB);
13327 continue;
13328 }
13329
13330 if (auto *Cmp = dyn_cast<ICmpInst>(Cond)) {
13331 const SCEV *L = getSCEV(Cmp->getOperand(0));
13332 const SCEV *R = getSCEV(Cmp->getOperand(1));
13333 if (isKnownPredicateViaConstantRanges(Cmp->getPredicate(), L, R)) {
13334 Worklist.push_back(TrueBB);
13335 continue;
13336 }
13337 if (isKnownPredicateViaConstantRanges(Cmp->getInversePredicate(), L,
13338 R)) {
13339 Worklist.push_back(FalseBB);
13340 continue;
13341 }
13342 }
13343 }
13344
13345 append_range(Worklist, successors(BB));
13346 }
13347}
13348
13349void ScalarEvolution::verify() const {
13350 ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this);
13351 ScalarEvolution SE2(F, TLI, AC, DT, LI);
13352
13353 SmallVector<Loop *, 8> LoopStack(LI.begin(), LI.end());
13354
13355 // Map's SCEV expressions from one ScalarEvolution "universe" to another.
13356 struct SCEVMapper : public SCEVRewriteVisitor<SCEVMapper> {
13357 SCEVMapper(ScalarEvolution &SE) : SCEVRewriteVisitor<SCEVMapper>(SE) {}
13358
13359 const SCEV *visitConstant(const SCEVConstant *Constant) {
13360 return SE.getConstant(Constant->getAPInt());
13361 }
13362
13363 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
13364 return SE.getUnknown(Expr->getValue());
13365 }
13366
13367 const SCEV *visitCouldNotCompute(const SCEVCouldNotCompute *Expr) {
13368 return SE.getCouldNotCompute();
13369 }
13370 };
13371
13372 SCEVMapper SCM(SE2);
13373 SmallPtrSet<BasicBlock *, 16> ReachableBlocks;
13374 SE2.getReachableBlocks(ReachableBlocks, F);
13375
13376 auto GetDelta = [&](const SCEV *Old, const SCEV *New) -> const SCEV * {
13377 if (containsUndefs(Old) || containsUndefs(New)) {
14
←
Assuming the condition is false
→
15
←
Assuming the condition is false
→
16
←
Taking false branch
→
13378 // SCEV treats "undef" as an unknown but consistent value (i.e. it does
13379 // not propagate undef aggressively). This means we can (and do) fail
13380 // verification in cases where a transform makes a value go from "undef"
13381 // to "undef+1" (say). The transform is fine, since in both cases the
13382 // result is "undef", but SCEV thinks the value increased by 1.
13383 return nullptr;
13384 }
13385
13386 // Unless VerifySCEVStrict is set, we only compare constant deltas.
13387 const SCEV *Delta = SE2.getMinusSCEV(Old, New);
17
←
Calling 'ScalarEvolution::getMinusSCEV'
→
13388 if (!VerifySCEVStrict && !isa<SCEVConstant>(Delta))
13389 return nullptr;
13390
13391 return Delta;
13392 };
13393
13394 while (!LoopStack.empty()) {
4
←
Loop condition is true. Entering loop body
→
13395 auto *L = LoopStack.pop_back_val();
13396 llvm::append_range(LoopStack, *L);
13397
13398 // Only verify BECounts in reachable loops. For an unreachable loop,
13399 // any BECount is legal.
13400 if (!ReachableBlocks.contains(L->getHeader()))
5
←
Assuming the condition is false
→
6
←
Taking false branch
→
13401 continue;
13402
13403 // Only verify cached BECounts. Computing new BECounts may change the
13404 // results of subsequent SCEV uses.
13405 auto It = BackedgeTakenCounts.find(L);
13406 if (It == BackedgeTakenCounts.end())
7
←
Taking false branch
→
13407 continue;
13408
13409 auto *CurBECount =
13410 SCM.visit(It->second.getExact(L, const_cast<ScalarEvolution *>(this)));
13411 auto *NewBECount = SE2.getBackedgeTakenCount(L);
13412
13413 if (CurBECount == SE2.getCouldNotCompute() ||
8
←
Assuming the condition is false
→
10
←
Taking false branch
→
13414 NewBECount == SE2.getCouldNotCompute()) {
9
←
Assuming the condition is false
→
13415 // NB! This situation is legal, but is very suspicious -- whatever pass
13416 // change the loop to make a trip count go from could not compute to
13417 // computable or vice-versa *should have* invalidated SCEV. However, we
13418 // choose not to assert here (for now) since we don't want false
13419 // positives.
13420 continue;
13421 }
13422
13423 if (SE.getTypeSizeInBits(CurBECount->getType()) >
11
←
Assuming the condition is true
→
12
←
Taking true branch
→
13424 SE.getTypeSizeInBits(NewBECount->getType()))
13425 NewBECount = SE2.getZeroExtendExpr(NewBECount, CurBECount->getType());
13426 else if (SE.getTypeSizeInBits(CurBECount->getType()) <
13427 SE.getTypeSizeInBits(NewBECount->getType()))
13428 CurBECount = SE2.getZeroExtendExpr(CurBECount, NewBECount->getType());
13429
13430 const SCEV *Delta = GetDelta(CurBECount, NewBECount);
13
←
Calling 'operator()'
→
13431 if (Delta && !Delta->isZero()) {
13432 dbgs() << "Trip Count for " << *L << " Changed!\n";
13433 dbgs() << "Old: " << *CurBECount << "\n";
13434 dbgs() << "New: " << *NewBECount << "\n";
13435 dbgs() << "Delta: " << *Delta << "\n";
13436 std::abort();
13437 }
13438 }
13439
13440 // Collect all valid loops currently in LoopInfo.
13441 SmallPtrSet<Loop *, 32> ValidLoops;
13442 SmallVector<Loop *, 32> Worklist(LI.begin(), LI.end());
13443 while (!Worklist.empty()) {
13444 Loop *L = Worklist.pop_back_val();
13445 if (ValidLoops.insert(L).second)
13446 Worklist.append(L->begin(), L->end());
13447 }
13448 for (auto &KV : ValueExprMap) {
13449#ifndef NDEBUG
13450 // Check for SCEV expressions referencing invalid/deleted loops.
13451 if (auto *AR = dyn_cast<SCEVAddRecExpr>(KV.second)) {
13452 assert(ValidLoops.contains(AR->getLoop()) &&(static_cast <bool> (ValidLoops.contains(AR->getLoop
()) && "AddRec references invalid loop") ? void (0) :
__assert_fail ("ValidLoops.contains(AR->getLoop()) && \"AddRec references invalid loop\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 13453, __extension__
__PRETTY_FUNCTION__))
13453 "AddRec references invalid loop")(static_cast <bool> (ValidLoops.contains(AR->getLoop
()) && "AddRec references invalid loop") ? void (0) :
__assert_fail ("ValidLoops.contains(AR->getLoop()) && \"AddRec references invalid loop\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 13453, __extension__
__PRETTY_FUNCTION__));
13454 }
13455#endif
13456
13457 // Check that the value is also part of the reverse map.
13458 auto It = ExprValueMap.find(KV.second);
13459 if (It == ExprValueMap.end() || !It->second.contains(KV.first)) {
13460 dbgs() << "Value " << *KV.first
13461 << " is in ValueExprMap but not in ExprValueMap\n";
13462 std::abort();
13463 }
13464
13465 if (auto *I = dyn_cast<Instruction>(&*KV.first)) {
13466 if (!ReachableBlocks.contains(I->getParent()))
13467 continue;
13468 const SCEV *OldSCEV = SCM.visit(KV.second);
13469 const SCEV *NewSCEV = SE2.getSCEV(I);
13470 const SCEV *Delta = GetDelta(OldSCEV, NewSCEV);
13471 if (Delta && !Delta->isZero()) {
13472 dbgs() << "SCEV for value " << *I << " changed!\n"
13473 << "Old: " << *OldSCEV << "\n"
13474 << "New: " << *NewSCEV << "\n"
13475 << "Delta: " << *Delta << "\n";
13476 std::abort();
13477 }
13478 }
13479 }
13480
13481 for (const auto &KV : ExprValueMap) {
13482 for (Value *V : KV.second) {
13483 auto It = ValueExprMap.find_as(V);
13484 if (It == ValueExprMap.end()) {
13485 dbgs() << "Value " << *V
13486 << " is in ExprValueMap but not in ValueExprMap\n";
13487 std::abort();
13488 }
13489 if (It->second != KV.first) {
13490 dbgs() << "Value " << *V << " mapped to " << *It->second
13491 << " rather than " << *KV.first << "\n";
13492 std::abort();
13493 }
13494 }
13495 }
13496
13497 // Verify integrity of SCEV users.
13498 for (const auto &S : UniqueSCEVs) {
13499 SmallVector<const SCEV *, 4> Ops;
13500 collectUniqueOps(&S, Ops);
13501 for (const auto *Op : Ops) {
13502 // We do not store dependencies of constants.
13503 if (isa<SCEVConstant>(Op))
13504 continue;
13505 auto It = SCEVUsers.find(Op);
13506 if (It != SCEVUsers.end() && It->second.count(&S))
13507 continue;
13508 dbgs() << "Use of operand " << *Op << " by user " << S
13509 << " is not being tracked!\n";
13510 std::abort();
13511 }
13512 }
13513
13514 // Verify integrity of ValuesAtScopes users.
13515 for (const auto &ValueAndVec : ValuesAtScopes) {
13516 const SCEV *Value = ValueAndVec.first;
13517 for (const auto &LoopAndValueAtScope : ValueAndVec.second) {
13518 const Loop *L = LoopAndValueAtScope.first;
13519 const SCEV *ValueAtScope = LoopAndValueAtScope.second;
13520 if (!isa<SCEVConstant>(ValueAtScope)) {
13521 auto It = ValuesAtScopesUsers.find(ValueAtScope);
13522 if (It != ValuesAtScopesUsers.end() &&
13523 is_contained(It->second, std::make_pair(L, Value)))
13524 continue;
13525 dbgs() << "Value: " << *Value << ", Loop: " << *L << ", ValueAtScope: "
13526 << *ValueAtScope << " missing in ValuesAtScopesUsers\n";
13527 std::abort();
13528 }
13529 }
13530 }
13531
13532 for (const auto &ValueAtScopeAndVec : ValuesAtScopesUsers) {
13533 const SCEV *ValueAtScope = ValueAtScopeAndVec.first;
13534 for (const auto &LoopAndValue : ValueAtScopeAndVec.second) {
13535 const Loop *L = LoopAndValue.first;
13536 const SCEV *Value = LoopAndValue.second;
13537 assert(!isa<SCEVConstant>(Value))(static_cast <bool> (!isa<SCEVConstant>(Value)) ?
void (0) : __assert_fail ("!isa<SCEVConstant>(Value)",
"llvm/lib/Analysis/ScalarEvolution.cpp", 13537, __extension__
__PRETTY_FUNCTION__));
13538 auto It = ValuesAtScopes.find(Value);
13539 if (It != ValuesAtScopes.end() &&
13540 is_contained(It->second, std::make_pair(L, ValueAtScope)))
13541 continue;
13542 dbgs() << "Value: " << *Value << ", Loop: " << *L << ", ValueAtScope: "
13543 << *ValueAtScope << " missing in ValuesAtScopes\n";
13544 std::abort();
13545 }
13546 }
13547
13548 // Verify integrity of BECountUsers.
13549 auto VerifyBECountUsers = [&](bool Predicated) {
13550 auto &BECounts =
13551 Predicated ? PredicatedBackedgeTakenCounts : BackedgeTakenCounts;
13552 for (const auto &LoopAndBEInfo : BECounts) {
13553 for (const ExitNotTakenInfo &ENT : LoopAndBEInfo.second.ExitNotTaken) {
13554 if (!isa<SCEVConstant>(ENT.ExactNotTaken)) {
13555 auto UserIt = BECountUsers.find(ENT.ExactNotTaken);
13556 if (UserIt != BECountUsers.end() &&
13557 UserIt->second.contains({ LoopAndBEInfo.first, Predicated }))
13558 continue;
13559 dbgs() << "Value " << *ENT.ExactNotTaken << " for loop "
13560 << *LoopAndBEInfo.first << " missing from BECountUsers\n";
13561 std::abort();
13562 }
13563 }
13564 }
13565 };
13566 VerifyBECountUsers(/* Predicated */ false);
13567 VerifyBECountUsers(/* Predicated */ true);
13568}
13569
13570bool ScalarEvolution::invalidate(
13571 Function &F, const PreservedAnalyses &PA,
13572 FunctionAnalysisManager::Invalidator &Inv) {
13573 // Invalidate the ScalarEvolution object whenever it isn't preserved or one
13574 // of its dependencies is invalidated.
13575 auto PAC = PA.getChecker<ScalarEvolutionAnalysis>();
13576 return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>()) ||
13577 Inv.invalidate<AssumptionAnalysis>(F, PA) ||
13578 Inv.invalidate<DominatorTreeAnalysis>(F, PA) ||
13579 Inv.invalidate<LoopAnalysis>(F, PA);
13580}
13581
13582AnalysisKey ScalarEvolutionAnalysis::Key;
13583
13584ScalarEvolution ScalarEvolutionAnalysis::run(Function &F,
13585 FunctionAnalysisManager &AM) {
13586 return ScalarEvolution(F, AM.getResult<TargetLibraryAnalysis>(F),
13587 AM.getResult<AssumptionAnalysis>(F),
13588 AM.getResult<DominatorTreeAnalysis>(F),
13589 AM.getResult<LoopAnalysis>(F));
13590}
13591
13592PreservedAnalyses
13593ScalarEvolutionVerifierPass::run(Function &F, FunctionAnalysisManager &AM) {
13594 AM.getResult<ScalarEvolutionAnalysis>(F).verify();
13595 return PreservedAnalyses::all();
13596}
13597
13598PreservedAnalyses
13599ScalarEvolutionPrinterPass::run(Function &F, FunctionAnalysisManager &AM) {
13600 // For compatibility with opt's -analyze feature under legacy pass manager
13601 // which was not ported to NPM. This keeps tests using
13602 // update_analyze_test_checks.py working.
13603 OS << "Printing analysis 'Scalar Evolution Analysis' for function '"
13604 << F.getName() << "':\n";
13605 AM.getResult<ScalarEvolutionAnalysis>(F).print(OS);
13606 return PreservedAnalyses::all();
13607}
13608
13609INITIALIZE_PASS_BEGIN(ScalarEvolutionWrapperPass, "scalar-evolution",static void *initializeScalarEvolutionWrapperPassPassOnce(PassRegistry
&Registry) {
13610 "Scalar Evolution Analysis", false, true)static void *initializeScalarEvolutionWrapperPassPassOnce(PassRegistry
&Registry) {
13611INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)initializeAssumptionCacheTrackerPass(Registry);
13612INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)initializeLoopInfoWrapperPassPass(Registry);
13613INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);
13614INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)initializeTargetLibraryInfoWrapperPassPass(Registry);
13615INITIALIZE_PASS_END(ScalarEvolutionWrapperPass, "scalar-evolution",PassInfo *PI = new PassInfo( "Scalar Evolution Analysis", "scalar-evolution"
, &ScalarEvolutionWrapperPass::ID, PassInfo::NormalCtor_t
(callDefaultCtor<ScalarEvolutionWrapperPass>), false, true
); Registry.registerPass(*PI, true); return PI; } static llvm
::once_flag InitializeScalarEvolutionWrapperPassPassFlag; void
llvm::initializeScalarEvolutionWrapperPassPass(PassRegistry &
Registry) { llvm::call_once(InitializeScalarEvolutionWrapperPassPassFlag
, initializeScalarEvolutionWrapperPassPassOnce, std::ref(Registry
)); }
13616 "Scalar Evolution Analysis", false, true)PassInfo *PI = new PassInfo( "Scalar Evolution Analysis", "scalar-evolution"
, &ScalarEvolutionWrapperPass::ID, PassInfo::NormalCtor_t
(callDefaultCtor<ScalarEvolutionWrapperPass>), false, true
); Registry.registerPass(*PI, true); return PI; } static llvm
::once_flag InitializeScalarEvolutionWrapperPassPassFlag; void
llvm::initializeScalarEvolutionWrapperPassPass(PassRegistry &
Registry) { llvm::call_once(InitializeScalarEvolutionWrapperPassPassFlag
, initializeScalarEvolutionWrapperPassPassOnce, std::ref(Registry
)); }
13617
13618char ScalarEvolutionWrapperPass::ID = 0;
13619
13620ScalarEvolutionWrapperPass::ScalarEvolutionWrapperPass() : FunctionPass(ID) {
13621 initializeScalarEvolutionWrapperPassPass(*PassRegistry::getPassRegistry());
13622}
13623
13624bool ScalarEvolutionWrapperPass::runOnFunction(Function &F) {
13625 SE.reset(new ScalarEvolution(
13626 F, getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F),
13627 getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F),
13628 getAnalysis<DominatorTreeWrapperPass>().getDomTree(),
13629 getAnalysis<LoopInfoWrapperPass>().getLoopInfo()));
13630 return false;
13631}
13632
13633void ScalarEvolutionWrapperPass::releaseMemory() { SE.reset(); }
13634
13635void ScalarEvolutionWrapperPass::print(raw_ostream &OS, const Module *) const {
13636 SE->print(OS);
13637}
13638
13639void ScalarEvolutionWrapperPass::verifyAnalysis() const {
13640 if (!VerifySCEV)
1
Assuming 'VerifySCEV' is true
→
2
←
Taking false branch
→
13641 return;
13642
13643 SE->verify();
3
←
Calling 'ScalarEvolution::verify'
→
13644}
13645
13646void ScalarEvolutionWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
13647 AU.setPreservesAll();
13648 AU.addRequiredTransitive<AssumptionCacheTracker>();
13649 AU.addRequiredTransitive<LoopInfoWrapperPass>();
13650 AU.addRequiredTransitive<DominatorTreeWrapperPass>();
13651 AU.addRequiredTransitive<TargetLibraryInfoWrapperPass>();
13652}
13653
13654const SCEVPredicate *ScalarEvolution::getEqualPredicate(const SCEV *LHS,
13655 const SCEV *RHS) {
13656 return getComparePredicate(ICmpInst::ICMP_EQ, LHS, RHS);
13657}
13658
13659const SCEVPredicate *
13660ScalarEvolution::getComparePredicate(const ICmpInst::Predicate Pred,
13661 const SCEV *LHS, const SCEV *RHS) {
13662 FoldingSetNodeID ID;
13663 assert(LHS->getType() == RHS->getType() &&(static_cast <bool> (LHS->getType() == RHS->getType
() && "Type mismatch between LHS and RHS") ? void (0)
: __assert_fail ("LHS->getType() == RHS->getType() && \"Type mismatch between LHS and RHS\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 13664, __extension__
__PRETTY_FUNCTION__))
13664 "Type mismatch between LHS and RHS")(static_cast <bool> (LHS->getType() == RHS->getType
() && "Type mismatch between LHS and RHS") ? void (0)
: __assert_fail ("LHS->getType() == RHS->getType() && \"Type mismatch between LHS and RHS\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 13664, __extension__
__PRETTY_FUNCTION__));
13665 // Unique this node based on the arguments
13666 ID.AddInteger(SCEVPredicate::P_Compare);
13667 ID.AddInteger(Pred);
13668 ID.AddPointer(LHS);
13669 ID.AddPointer(RHS);
13670 void *IP = nullptr;
13671 if (const auto *S = UniquePreds.FindNodeOrInsertPos(ID, IP))
13672 return S;
13673 SCEVComparePredicate *Eq = new (SCEVAllocator)
13674 SCEVComparePredicate(ID.Intern(SCEVAllocator), Pred, LHS, RHS);
13675 UniquePreds.InsertNode(Eq, IP);
13676 return Eq;
13677}
13678
13679const SCEVPredicate *ScalarEvolution::getWrapPredicate(
13680 const SCEVAddRecExpr *AR,
13681 SCEVWrapPredicate::IncrementWrapFlags AddedFlags) {
13682 FoldingSetNodeID ID;
13683 // Unique this node based on the arguments
13684 ID.AddInteger(SCEVPredicate::P_Wrap);
13685 ID.AddPointer(AR);
13686 ID.AddInteger(AddedFlags);
13687 void *IP = nullptr;
13688 if (const auto *S = UniquePreds.FindNodeOrInsertPos(ID, IP))
13689 return S;
13690 auto *OF = new (SCEVAllocator)
13691 SCEVWrapPredicate(ID.Intern(SCEVAllocator), AR, AddedFlags);
13692 UniquePreds.InsertNode(OF, IP);
13693 return OF;
13694}
13695
13696namespace {
13697
13698class SCEVPredicateRewriter : public SCEVRewriteVisitor<SCEVPredicateRewriter> {
13699public:
13700
13701 /// Rewrites \p S in the context of a loop L and the SCEV predication
13702 /// infrastructure.
13703 ///
13704 /// If \p Pred is non-null, the SCEV expression is rewritten to respect the
13705 /// equivalences present in \p Pred.
13706 ///
13707 /// If \p NewPreds is non-null, rewrite is free to add further predicates to
13708 /// \p NewPreds such that the result will be an AddRecExpr.
13709 static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE,
13710 SmallPtrSetImpl<const SCEVPredicate *> *NewPreds,
13711 const SCEVPredicate *Pred) {
13712 SCEVPredicateRewriter Rewriter(L, SE, NewPreds, Pred);
13713 return Rewriter.visit(S);
13714 }
13715
13716 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
13717 if (Pred) {
13718 if (auto *U = dyn_cast<SCEVUnionPredicate>(Pred)) {
13719 for (auto *Pred : U->getPredicates())
13720 if (const auto *IPred = dyn_cast<SCEVComparePredicate>(Pred))
13721 if (IPred->getLHS() == Expr &&
13722 IPred->getPredicate() == ICmpInst::ICMP_EQ)
13723 return IPred->getRHS();
13724 } else if (const auto *IPred = dyn_cast<SCEVComparePredicate>(Pred)) {
13725 if (IPred->getLHS() == Expr &&
13726 IPred->getPredicate() == ICmpInst::ICMP_EQ)
13727 return IPred->getRHS();
13728 }
13729 }
13730 return convertToAddRecWithPreds(Expr);
13731 }
13732
13733 const SCEV *visitZeroExtendExpr(const SCEVZeroExtendExpr *Expr) {
13734 const SCEV *Operand = visit(Expr->getOperand());
13735 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Operand);
13736 if (AR && AR->getLoop() == L && AR->isAffine()) {
13737 // This couldn't be folded because the operand didn't have the nuw
13738 // flag. Add the nusw flag as an assumption that we could make.
13739 const SCEV *Step = AR->getStepRecurrence(SE);
13740 Type *Ty = Expr->getType();
13741 if (addOverflowAssumption(AR, SCEVWrapPredicate::IncrementNUSW))
13742 return SE.getAddRecExpr(SE.getZeroExtendExpr(AR->getStart(), Ty),
13743 SE.getSignExtendExpr(Step, Ty), L,
13744 AR->getNoWrapFlags());
13745 }
13746 return SE.getZeroExtendExpr(Operand, Expr->getType());
13747 }
13748
13749 const SCEV *visitSignExtendExpr(const SCEVSignExtendExpr *Expr) {
13750 const SCEV *Operand = visit(Expr->getOperand());
13751 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Operand);
13752 if (AR && AR->getLoop() == L && AR->isAffine()) {
13753 // This couldn't be folded because the operand didn't have the nsw
13754 // flag. Add the nssw flag as an assumption that we could make.
13755 const SCEV *Step = AR->getStepRecurrence(SE);
13756 Type *Ty = Expr->getType();
13757 if (addOverflowAssumption(AR, SCEVWrapPredicate::IncrementNSSW))
13758 return SE.getAddRecExpr(SE.getSignExtendExpr(AR->getStart(), Ty),
13759 SE.getSignExtendExpr(Step, Ty), L,
13760 AR->getNoWrapFlags());
13761 }
13762 return SE.getSignExtendExpr(Operand, Expr->getType());
13763 }
13764
13765private:
13766 explicit SCEVPredicateRewriter(const Loop *L, ScalarEvolution &SE,
13767 SmallPtrSetImpl<const SCEVPredicate *> *NewPreds,
13768 const SCEVPredicate *Pred)
13769 : SCEVRewriteVisitor(SE), NewPreds(NewPreds), Pred(Pred), L(L) {}
13770
13771 bool addOverflowAssumption(const SCEVPredicate *P) {
13772 if (!NewPreds) {
13773 // Check if we've already made this assumption.
13774 return Pred && Pred->implies(P);
13775 }
13776 NewPreds->insert(P);
13777 return true;
13778 }
13779
13780 bool addOverflowAssumption(const SCEVAddRecExpr *AR,
13781 SCEVWrapPredicate::IncrementWrapFlags AddedFlags) {
13782 auto *A = SE.getWrapPredicate(AR, AddedFlags);
13783 return addOverflowAssumption(A);
13784 }
13785
13786 // If \p Expr represents a PHINode, we try to see if it can be represented
13787 // as an AddRec, possibly under a predicate (PHISCEVPred). If it is possible
13788 // to add this predicate as a runtime overflow check, we return the AddRec.
13789 // If \p Expr does not meet these conditions (is not a PHI node, or we
13790 // couldn't create an AddRec for it, or couldn't add the predicate), we just
13791 // return \p Expr.
13792 const SCEV *convertToAddRecWithPreds(const SCEVUnknown *Expr) {
13793 if (!isa<PHINode>(Expr->getValue()))
13794 return Expr;
13795 Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
13796 PredicatedRewrite = SE.createAddRecFromPHIWithCasts(Expr);
13797 if (!PredicatedRewrite)
13798 return Expr;
13799 for (auto *P : PredicatedRewrite->second){
13800 // Wrap predicates from outer loops are not supported.
13801 if (auto *WP = dyn_cast<const SCEVWrapPredicate>(P)) {
13802 if (L != WP->getExpr()->getLoop())
13803 return Expr;
13804 }
13805 if (!addOverflowAssumption(P))
13806 return Expr;
13807 }
13808 return PredicatedRewrite->first;
13809 }
13810
13811 SmallPtrSetImpl<const SCEVPredicate *> *NewPreds;
13812 const SCEVPredicate *Pred;
13813 const Loop *L;
13814};
13815
13816} // end anonymous namespace
13817
13818const SCEV *
13819ScalarEvolution::rewriteUsingPredicate(const SCEV *S, const Loop *L,
13820 const SCEVPredicate &Preds) {
13821 return SCEVPredicateRewriter::rewrite(S, L, *this, nullptr, &Preds);
13822}
13823
13824const SCEVAddRecExpr *ScalarEvolution::convertSCEVToAddRecWithPredicates(
13825 const SCEV *S, const Loop *L,
13826 SmallPtrSetImpl<const SCEVPredicate *> &Preds) {
13827 SmallPtrSet<const SCEVPredicate *, 4> TransformPreds;
13828 S = SCEVPredicateRewriter::rewrite(S, L, *this, &TransformPreds, nullptr);
13829 auto *AddRec = dyn_cast<SCEVAddRecExpr>(S);
13830
13831 if (!AddRec)
13832 return nullptr;
13833
13834 // Since the transformation was successful, we can now transfer the SCEV
13835 // predicates.
13836 for (auto *P : TransformPreds)
13837 Preds.insert(P);
13838
13839 return AddRec;
13840}
13841
13842/// SCEV predicates
13843SCEVPredicate::SCEVPredicate(const FoldingSetNodeIDRef ID,
13844 SCEVPredicateKind Kind)
13845 : FastID(ID), Kind(Kind) {}
13846
13847SCEVComparePredicate::SCEVComparePredicate(const FoldingSetNodeIDRef ID,
13848 const ICmpInst::Predicate Pred,
13849 const SCEV *LHS, const SCEV *RHS)
13850 : SCEVPredicate(ID, P_Compare), Pred(Pred), LHS(LHS), RHS(RHS) {
13851 assert(LHS->getType() == RHS->getType() && "LHS and RHS types don't match")(static_cast <bool> (LHS->getType() == RHS->getType
() && "LHS and RHS types don't match") ? void (0) : __assert_fail
("LHS->getType() == RHS->getType() && \"LHS and RHS types don't match\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 13851, __extension__
__PRETTY_FUNCTION__));
13852 assert(LHS != RHS && "LHS and RHS are the same SCEV")(static_cast <bool> (LHS != RHS && "LHS and RHS are the same SCEV"
) ? void (0) : __assert_fail ("LHS != RHS && \"LHS and RHS are the same SCEV\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 13852, __extension__
__PRETTY_FUNCTION__));
13853}
13854
13855bool SCEVComparePredicate::implies(const SCEVPredicate *N) const {
13856 const auto *Op = dyn_cast<SCEVComparePredicate>(N);
13857
13858 if (!Op)
13859 return false;
13860
13861 if (Pred != ICmpInst::ICMP_EQ)
13862 return false;
13863
13864 return Op->LHS == LHS && Op->RHS == RHS;
13865}
13866
13867bool SCEVComparePredicate::isAlwaysTrue() const { return false; }
13868
13869void SCEVComparePredicate::print(raw_ostream &OS, unsigned Depth) const {
13870 if (Pred == ICmpInst::ICMP_EQ)
13871 OS.indent(Depth) << "Equal predicate: " << *LHS << " == " << *RHS << "\n";
13872 else
13873 OS.indent(Depth) << "Compare predicate: " << *LHS
13874 << " " << CmpInst::getPredicateName(Pred) << ") "
13875 << *RHS << "\n";
13876
13877}
13878
13879SCEVWrapPredicate::SCEVWrapPredicate(const FoldingSetNodeIDRef ID,
13880 const SCEVAddRecExpr *AR,
13881 IncrementWrapFlags Flags)
13882 : SCEVPredicate(ID, P_Wrap), AR(AR), Flags(Flags) {}
13883
13884const SCEVAddRecExpr *SCEVWrapPredicate::getExpr() const { return AR; }
13885
13886bool SCEVWrapPredicate::implies(const SCEVPredicate *N) const {
13887 const auto *Op = dyn_cast<SCEVWrapPredicate>(N);
13888
13889 return Op && Op->AR == AR && setFlags(Flags, Op->Flags) == Flags;
13890}
13891
13892bool SCEVWrapPredicate::isAlwaysTrue() const {
13893 SCEV::NoWrapFlags ScevFlags = AR->getNoWrapFlags();
13894 IncrementWrapFlags IFlags = Flags;
13895
13896 if (ScalarEvolution::setFlags(ScevFlags, SCEV::FlagNSW) == ScevFlags)
13897 IFlags = clearFlags(IFlags, IncrementNSSW);
13898
13899 return IFlags == IncrementAnyWrap;
13900}
13901
13902void SCEVWrapPredicate::print(raw_ostream &OS, unsigned Depth) const {
13903 OS.indent(Depth) << *getExpr() << " Added Flags: ";
13904 if (SCEVWrapPredicate::IncrementNUSW & getFlags())
13905 OS << "<nusw>";
13906 if (SCEVWrapPredicate::IncrementNSSW & getFlags())
13907 OS << "<nssw>";
13908 OS << "\n";
13909}
13910
13911SCEVWrapPredicate::IncrementWrapFlags
13912SCEVWrapPredicate::getImpliedFlags(const SCEVAddRecExpr *AR,
13913 ScalarEvolution &SE) {
13914 IncrementWrapFlags ImpliedFlags = IncrementAnyWrap;
13915 SCEV::NoWrapFlags StaticFlags = AR->getNoWrapFlags();
13916
13917 // We can safely transfer the NSW flag as NSSW.
13918 if (ScalarEvolution::setFlags(StaticFlags, SCEV::FlagNSW) == StaticFlags)
13919 ImpliedFlags = IncrementNSSW;
13920
13921 if (ScalarEvolution::setFlags(StaticFlags, SCEV::FlagNUW) == StaticFlags) {
13922 // If the increment is positive, the SCEV NUW flag will also imply the
13923 // WrapPredicate NUSW flag.
13924 if (const auto *Step = dyn_cast<SCEVConstant>(AR->getStepRecurrence(SE)))
13925 if (Step->getValue()->getValue().isNonNegative())
13926 ImpliedFlags = setFlags(ImpliedFlags, IncrementNUSW);
13927 }
13928
13929 return ImpliedFlags;
13930}
13931
13932/// Union predicates don't get cached so create a dummy set ID for it.
13933SCEVUnionPredicate::SCEVUnionPredicate(ArrayRef<const SCEVPredicate *> Preds)
13934 : SCEVPredicate(FoldingSetNodeIDRef(nullptr, 0), P_Union) {
13935 for (auto *P : Preds)
13936 add(P);
13937}
13938
13939bool SCEVUnionPredicate::isAlwaysTrue() const {
13940 return all_of(Preds,
13941 [](const SCEVPredicate *I) { return I->isAlwaysTrue(); });
13942}
13943
13944bool SCEVUnionPredicate::implies(const SCEVPredicate *N) const {
13945 if (const auto *Set = dyn_cast<SCEVUnionPredicate>(N))
13946 return all_of(Set->Preds,
13947 [this](const SCEVPredicate *I) { return this->implies(I); });
13948
13949 return any_of(Preds,
13950 [N](const SCEVPredicate *I) { return I->implies(N); });
13951}
13952
13953void SCEVUnionPredicate::print(raw_ostream &OS, unsigned Depth) const {
13954 for (auto Pred : Preds)
13955 Pred->print(OS, Depth);
13956}
13957
13958void SCEVUnionPredicate::add(const SCEVPredicate *N) {
13959 if (const auto *Set = dyn_cast<SCEVUnionPredicate>(N)) {
13960 for (auto Pred : Set->Preds)
13961 add(Pred);
13962 return;
13963 }
13964
13965 Preds.push_back(N);
13966}
13967
13968PredicatedScalarEvolution::PredicatedScalarEvolution(ScalarEvolution &SE,
13969 Loop &L)
13970 : SE(SE), L(L) {
13971 SmallVector<const SCEVPredicate*, 4> Empty;
13972 Preds = std::make_unique<SCEVUnionPredicate>(Empty);
13973}
13974
13975void ScalarEvolution::registerUser(const SCEV *User,
13976 ArrayRef<const SCEV *> Ops) {
13977 for (auto *Op : Ops)
13978 // We do not expect that forgetting cached data for SCEVConstants will ever
13979 // open any prospects for sharpening or introduce any correctness issues,
13980 // so we don't bother storing their dependencies.
13981 if (!isa<SCEVConstant>(Op))
13982 SCEVUsers[Op].insert(User);
13983}
13984
13985const SCEV *PredicatedScalarEvolution::getSCEV(Value *V) {
13986 const SCEV *Expr = SE.getSCEV(V);
13987 RewriteEntry &Entry = RewriteMap[Expr];
13988
13989 // If we already have an entry and the version matches, return it.
13990 if (Entry.second && Generation == Entry.first)
13991 return Entry.second;
13992
13993 // We found an entry but it's stale. Rewrite the stale entry
13994 // according to the current predicate.
13995 if (Entry.second)
13996 Expr = Entry.second;
13997
13998 const SCEV *NewSCEV = SE.rewriteUsingPredicate(Expr, &L, *Preds);
13999 Entry = {Generation, NewSCEV};
14000
14001 return NewSCEV;
14002}
14003
14004const SCEV *PredicatedScalarEvolution::getBackedgeTakenCount() {
14005 if (!BackedgeCount) {
14006 SmallVector<const SCEVPredicate *, 4> Preds;
14007 BackedgeCount = SE.getPredicatedBackedgeTakenCount(&L, Preds);
14008 for (auto *P : Preds)
14009 addPredicate(*P);
14010 }
14011 return BackedgeCount;
14012}
14013
14014void PredicatedScalarEvolution::addPredicate(const SCEVPredicate &Pred) {
14015 if (Preds->implies(&Pred))
14016 return;
14017
14018 auto &OldPreds = Preds->getPredicates();
14019 SmallVector<const SCEVPredicate*, 4> NewPreds(OldPreds.begin(), OldPreds.end());
14020 NewPreds.push_back(&Pred);
14021 Preds = std::make_unique<SCEVUnionPredicate>(NewPreds);
14022 updateGeneration();
14023}
14024
14025const SCEVPredicate &PredicatedScalarEvolution::getPredicate() const {
14026 return *Preds;
14027}
14028
14029void PredicatedScalarEvolution::updateGeneration() {
14030 // If the generation number wrapped recompute everything.
14031 if (++Generation == 0) {
14032 for (auto &II : RewriteMap) {
14033 const SCEV *Rewritten = II.second.second;
14034 II.second = {Generation, SE.rewriteUsingPredicate(Rewritten, &L, *Preds)};
14035 }
14036 }
14037}
14038
14039void PredicatedScalarEvolution::setNoOverflow(
14040 Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags) {
14041 const SCEV *Expr = getSCEV(V);
14042 const auto *AR = cast<SCEVAddRecExpr>(Expr);
14043
14044 auto ImpliedFlags = SCEVWrapPredicate::getImpliedFlags(AR, SE);
14045
14046 // Clear the statically implied flags.
14047 Flags = SCEVWrapPredicate::clearFlags(Flags, ImpliedFlags);
14048 addPredicate(*SE.getWrapPredicate(AR, Flags));
14049
14050 auto II = FlagsMap.insert({V, Flags});
14051 if (!II.second)
14052 II.first->second = SCEVWrapPredicate::setFlags(Flags, II.first->second);
14053}
14054
14055bool PredicatedScalarEvolution::hasNoOverflow(
14056 Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags) {
14057 const SCEV *Expr = getSCEV(V);
14058 const auto *AR = cast<SCEVAddRecExpr>(Expr);
14059
14060 Flags = SCEVWrapPredicate::clearFlags(
14061 Flags, SCEVWrapPredicate::getImpliedFlags(AR, SE));
14062
14063 auto II = FlagsMap.find(V);
14064
14065 if (II != FlagsMap.end())
14066 Flags = SCEVWrapPredicate::clearFlags(Flags, II->second);
14067
14068 return Flags == SCEVWrapPredicate::IncrementAnyWrap;
14069}
14070
14071const SCEVAddRecExpr *PredicatedScalarEvolution::getAsAddRec(Value *V) {
14072 const SCEV *Expr = this->getSCEV(V);
14073 SmallPtrSet<const SCEVPredicate *, 4> NewPreds;
14074 auto *New = SE.convertSCEVToAddRecWithPredicates(Expr, &L, NewPreds);
14075
14076 if (!New)
14077 return nullptr;
14078
14079 for (auto *P : NewPreds)
14080 addPredicate(*P);
14081
14082 RewriteMap[SE.getSCEV(V)] = {Generation, New};
14083 return New;
14084}
14085
14086PredicatedScalarEvolution::PredicatedScalarEvolution(
14087 const PredicatedScalarEvolution &Init)
14088 : RewriteMap(Init.RewriteMap), SE(Init.SE), L(Init.L),
14089 Preds(std::make_unique<SCEVUnionPredicate>(Init.Preds->getPredicates())),
14090 Generation(Init.Generation), BackedgeCount(Init.BackedgeCount) {
14091 for (auto I : Init.FlagsMap)
14092 FlagsMap.insert(I);
14093}
14094
14095void PredicatedScalarEvolution::print(raw_ostream &OS, unsigned Depth) const {
14096 // For each block.
14097 for (auto *BB : L.getBlocks())
14098 for (auto &I : *BB) {
14099 if (!SE.isSCEVable(I.getType()))
14100 continue;
14101
14102 auto *Expr = SE.getSCEV(&I);
14103 auto II = RewriteMap.find(Expr);
14104
14105 if (II == RewriteMap.end())
14106 continue;
14107
14108 // Don't print things that are not interesting.
14109 if (II->second.second == Expr)
14110 continue;
14111
14112 OS.indent(Depth) << "[PSE]" << I << ":\n";
14113 OS.indent(Depth + 2) << *Expr << "\n";
14114 OS.indent(Depth + 2) << "--> " << *II->second.second << "\n";
14115 }
14116}
14117
14118// Match the mathematical pattern A - (A / B) * B, where A and B can be
14119// arbitrary expressions. Also match zext (trunc A to iB) to iY, which is used
14120// for URem with constant power-of-2 second operands.
14121// It's not always easy, as A and B can be folded (imagine A is X / 2, and B is
14122// 4, A / B becomes X / 8).
14123bool ScalarEvolution::matchURem(const SCEV *Expr, const SCEV *&LHS,
14124 const SCEV *&RHS) {
14125 // Try to match 'zext (trunc A to iB) to iY', which is used
14126 // for URem with constant power-of-2 second operands. Make sure the size of
14127 // the operand A matches the size of the whole expressions.
14128 if (const auto *ZExt = dyn_cast<SCEVZeroExtendExpr>(Expr))
14129 if (const auto *Trunc = dyn_cast<SCEVTruncateExpr>(ZExt->getOperand(0))) {
14130 LHS = Trunc->getOperand();
14131 // Bail out if the type of the LHS is larger than the type of the
14132 // expression for now.
14133 if (getTypeSizeInBits(LHS->getType()) >
14134 getTypeSizeInBits(Expr->getType()))
14135 return false;
14136 if (LHS->getType() != Expr->getType())
14137 LHS = getZeroExtendExpr(LHS, Expr->getType());
14138 RHS = getConstant(APInt(getTypeSizeInBits(Expr->getType()), 1)
14139 << getTypeSizeInBits(Trunc->getType()));
14140 return true;
14141 }
14142 const auto *Add = dyn_cast<SCEVAddExpr>(Expr);
14143 if (Add == nullptr || Add->getNumOperands() != 2)
14144 return false;
14145
14146 const SCEV *A = Add->getOperand(1);
14147 const auto *Mul = dyn_cast<SCEVMulExpr>(Add->getOperand(0));
14148
14149 if (Mul == nullptr)
14150 return false;
14151
14152 const auto MatchURemWithDivisor = [&](const SCEV *B) {
14153 // (SomeExpr + (-(SomeExpr / B) * B)).
14154 if (Expr == getURemExpr(A, B)) {
14155 LHS = A;
14156 RHS = B;
14157 return true;
14158 }
14159 return false;
14160 };
14161
14162 // (SomeExpr + (-1 * (SomeExpr / B) * B)).
14163 if (Mul->getNumOperands() == 3 && isa<SCEVConstant>(Mul->getOperand(0)))
14164 return MatchURemWithDivisor(Mul->getOperand(1)) ||
14165 MatchURemWithDivisor(Mul->getOperand(2));
14166
14167 // (SomeExpr + ((-SomeExpr / B) * B)) or (SomeExpr + ((SomeExpr / B) * -B)).
14168 if (Mul->getNumOperands() == 2)
14169 return MatchURemWithDivisor(Mul->getOperand(1)) ||
14170 MatchURemWithDivisor(Mul->getOperand(0)) ||
14171 MatchURemWithDivisor(getNegativeSCEV(Mul->getOperand(1))) ||
14172 MatchURemWithDivisor(getNegativeSCEV(Mul->getOperand(0)));
14173 return false;
14174}
14175
14176const SCEV *
14177ScalarEvolution::computeSymbolicMaxBackedgeTakenCount(const Loop *L) {
14178 SmallVector<BasicBlock*, 16> ExitingBlocks;
14179 L->getExitingBlocks(ExitingBlocks);
14180
14181 // Form an expression for the maximum exit count possible for this loop. We
14182 // merge the max and exact information to approximate a version of
14183 // getConstantMaxBackedgeTakenCount which isn't restricted to just constants.
14184 SmallVector<const SCEV*, 4> ExitCounts;
14185 for (BasicBlock *ExitingBB : ExitingBlocks) {
14186 const SCEV *ExitCount = getExitCount(L, ExitingBB);
14187 if (isa<SCEVCouldNotCompute>(ExitCount))
14188 ExitCount = getExitCount(L, ExitingBB,
14189 ScalarEvolution::ConstantMaximum);
14190 if (!isa<SCEVCouldNotCompute>(ExitCount)) {
14191 assert(DT.dominates(ExitingBB, L->getLoopLatch()) &&(static_cast <bool> (DT.dominates(ExitingBB, L->getLoopLatch
()) && "We should only have known counts for exiting blocks that "
"dominate latch!") ? void (0) : __assert_fail ("DT.dominates(ExitingBB, L->getLoopLatch()) && \"We should only have known counts for exiting blocks that \" \"dominate latch!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 14193, __extension__
__PRETTY_FUNCTION__))
14192 "We should only have known counts for exiting blocks that "(static_cast <bool> (DT.dominates(ExitingBB, L->getLoopLatch
()) && "We should only have known counts for exiting blocks that "
"dominate latch!") ? void (0) : __assert_fail ("DT.dominates(ExitingBB, L->getLoopLatch()) && \"We should only have known counts for exiting blocks that \" \"dominate latch!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 14193, __extension__
__PRETTY_FUNCTION__))
14193 "dominate latch!")(static_cast <bool> (DT.dominates(ExitingBB, L->getLoopLatch
()) && "We should only have known counts for exiting blocks that "
"dominate latch!") ? void (0) : __assert_fail ("DT.dominates(ExitingBB, L->getLoopLatch()) && \"We should only have known counts for exiting blocks that \" \"dominate latch!\""
, "llvm/lib/Analysis/ScalarEvolution.cpp", 14193, __extension__
__PRETTY_FUNCTION__));
14194 ExitCounts.push_back(ExitCount);
14195 }
14196 }
14197 if (ExitCounts.empty())
14198 return getCouldNotCompute();
14199 return getUMinFromMismatchedTypes(ExitCounts);
14200}
14201
14202/// A rewriter to replace SCEV expressions in Map with the corresponding entry
14203/// in the map. It skips AddRecExpr because we cannot guarantee that the
14204/// replacement is loop invariant in the loop of the AddRec.
14205///
14206/// At the moment only rewriting SCEVUnknown and SCEVZeroExtendExpr is
14207/// supported.
14208class SCEVLoopGuardRewriter : public SCEVRewriteVisitor<SCEVLoopGuardRewriter> {
14209 const DenseMap<const SCEV *, const SCEV *> &Map;
14210
14211public:
14212 SCEVLoopGuardRewriter(ScalarEvolution &SE,
14213 DenseMap<const SCEV *, const SCEV *> &M)
14214 : SCEVRewriteVisitor(SE), Map(M) {}
14215
14216 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) { return Expr; }
14217
14218 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
14219 auto I = Map.find(Expr);
14220 if (I == Map.end())
14221 return Expr;
14222 return I->second;
14223 }
14224
14225 const SCEV *visitZeroExtendExpr(const SCEVZeroExtendExpr *Expr) {
14226 auto I = Map.find(Expr);
14227 if (I == Map.end())
14228 return SCEVRewriteVisitor<SCEVLoopGuardRewriter>::visitZeroExtendExpr(
14229 Expr);
14230 return I->second;
14231 }
14232};
14233
14234const SCEV *ScalarEvolution::applyLoopGuards(const SCEV *Expr, const Loop *L) {
14235 SmallVector<const SCEV *> ExprsToRewrite;
14236 auto CollectCondition = [&](ICmpInst::Predicate Predicate, const SCEV *LHS,
14237 const SCEV *RHS,
14238 DenseMap<const SCEV *, const SCEV *>
14239 &RewriteMap) {
14240 // WARNING: It is generally unsound to apply any wrap flags to the proposed
14241 // replacement SCEV which isn't directly implied by the structure of that
14242 // SCEV. In particular, using contextual facts to imply flags is *NOT*
14243 // legal. See the scoping rules for flags in the header to understand why.
14244
14245 // If LHS is a constant, apply information to the other expression.
14246 if (isa<SCEVConstant>(LHS)) {
14247 std::swap(LHS, RHS);
14248 Predicate = CmpInst::getSwappedPredicate(Predicate);
14249 }
14250
14251 // Check for a condition of the form (-C1 + X < C2). InstCombine will
14252 // create this form when combining two checks of the form (X u< C2 + C1) and
14253 // (X >=u C1).
14254 auto MatchRangeCheckIdiom = [this, Predicate, LHS, RHS, &RewriteMap,
14255 &ExprsToRewrite]() {
14256 auto *AddExpr = dyn_cast<SCEVAddExpr>(LHS);
14257 if (!AddExpr || AddExpr->getNumOperands() != 2)
14258 return false;
14259
14260 auto *C1 = dyn_cast<SCEVConstant>(AddExpr->getOperand(0));
14261 auto *LHSUnknown = dyn_cast<SCEVUnknown>(AddExpr->getOperand(1));
14262 auto *C2 = dyn_cast<SCEVConstant>(RHS);
14263 if (!C1 || !C2 || !LHSUnknown)
14264 return false;
14265
14266 auto ExactRegion =
14267 ConstantRange::makeExactICmpRegion(Predicate, C2->getAPInt())
14268 .sub(C1->getAPInt());
14269
14270 // Bail out, unless we have a non-wrapping, monotonic range.
14271 if (ExactRegion.isWrappedSet() || ExactRegion.isFullSet())
14272 return false;
14273 auto I = RewriteMap.find(LHSUnknown);
14274 const SCEV *RewrittenLHS = I != RewriteMap.end() ? I->second : LHSUnknown;
14275 RewriteMap[LHSUnknown] = getUMaxExpr(
14276 getConstant(ExactRegion.getUnsignedMin()),
14277 getUMinExpr(RewrittenLHS, getConstant(ExactRegion.getUnsignedMax())));
14278 ExprsToRewrite.push_back(LHSUnknown);
14279 return true;
14280 };
14281 if (MatchRangeCheckIdiom())
14282 return;
14283
14284 // If we have LHS == 0, check if LHS is computing a property of some unknown
14285 // SCEV %v which we can rewrite %v to express explicitly.
14286 const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS);
14287 if (Predicate == CmpInst::ICMP_EQ && RHSC &&
14288 RHSC->getValue()->isNullValue()) {
14289 // If LHS is A % B, i.e. A % B == 0, rewrite A to (A /u B) * B to
14290 // explicitly express that.
14291 const SCEV *URemLHS = nullptr;
14292 const SCEV *URemRHS = nullptr;
14293 if (matchURem(LHS, URemLHS, URemRHS)) {
14294 if (const SCEVUnknown *LHSUnknown = dyn_cast<SCEVUnknown>(URemLHS)) {
14295 auto Multiple = getMulExpr(getUDivExpr(URemLHS, URemRHS), URemRHS);
14296 RewriteMap[LHSUnknown] = Multiple;
14297 ExprsToRewrite.push_back(LHSUnknown);
14298 return;
14299 }
14300 }
14301 }
14302
14303 // Do not apply information for constants or if RHS contains an AddRec.
14304 if (isa<SCEVConstant>(LHS) || containsAddRecurrence(RHS))
14305 return;
14306
14307 // If RHS is SCEVUnknown, make sure the information is applied to it.
14308 if (!isa<SCEVUnknown>(LHS) && isa<SCEVUnknown>(RHS)) {
14309 std::swap(LHS, RHS);
14310 Predicate = CmpInst::getSwappedPredicate(Predicate);
14311 }
14312
14313 // Limit to expressions that can be rewritten.
14314 if (!isa<SCEVUnknown>(LHS) && !isa<SCEVZeroExtendExpr>(LHS))
14315 return;
14316
14317 // Check whether LHS has already been rewritten. In that case we want to
14318 // chain further rewrites onto the already rewritten value.
14319 auto I = RewriteMap.find(LHS);
14320 const SCEV *RewrittenLHS = I != RewriteMap.end() ? I->second : LHS;
14321
14322 const SCEV *RewrittenRHS = nullptr;
14323 switch (Predicate) {
14324 case CmpInst::ICMP_ULT:
14325 RewrittenRHS =
14326 getUMinExpr(RewrittenLHS, getMinusSCEV(RHS, getOne(RHS->getType())));
14327 break;
14328 case CmpInst::ICMP_SLT:
14329 RewrittenRHS =
14330 getSMinExpr(RewrittenLHS, getMinusSCEV(RHS, getOne(RHS->getType())));
14331 break;
14332 case CmpInst::ICMP_ULE:
14333 RewrittenRHS = getUMinExpr(RewrittenLHS, RHS);
14334 break;
14335 case CmpInst::ICMP_SLE:
14336 RewrittenRHS = getSMinExpr(RewrittenLHS, RHS);
14337 break;
14338 case CmpInst::ICMP_UGT:
14339 RewrittenRHS =
14340 getUMaxExpr(RewrittenLHS, getAddExpr(RHS, getOne(RHS->getType())));
14341 break;
14342 case CmpInst::ICMP_SGT:
14343 RewrittenRHS =
14344 getSMaxExpr(RewrittenLHS, getAddExpr(RHS, getOne(RHS->getType())));
14345 break;
14346 case CmpInst::ICMP_UGE:
14347 RewrittenRHS = getUMaxExpr(RewrittenLHS, RHS);
14348 break;
14349 case CmpInst::ICMP_SGE:
14350 RewrittenRHS = getSMaxExpr(RewrittenLHS, RHS);
14351 break;
14352 case CmpInst::ICMP_EQ:
14353 if (isa<SCEVConstant>(RHS))
14354 RewrittenRHS = RHS;
14355 break;
14356 case CmpInst::ICMP_NE:
14357 if (isa<SCEVConstant>(RHS) &&
14358 cast<SCEVConstant>(RHS)->getValue()->isNullValue())
14359 RewrittenRHS = getUMaxExpr(RewrittenLHS, getOne(RHS->getType()));
14360 break;
14361 default:
14362 break;
14363 }
14364
14365 if (RewrittenRHS) {
14366 RewriteMap[LHS] = RewrittenRHS;
14367 if (LHS == RewrittenLHS)
14368 ExprsToRewrite.push_back(LHS);
14369 }
14370 };
14371 // First, collect conditions from dominating branches. Starting at the loop
14372 // predecessor, climb up the predecessor chain, as long as there are
14373 // predecessors that can be found that have unique successors leading to the
14374 // original header.
14375 // TODO: share this logic with isLoopEntryGuardedByCond.
14376 SmallVector<std::pair<Value *, bool>> Terms;
14377 for (std::pair<const BasicBlock *, const BasicBlock *> Pair(
14378 L->getLoopPredecessor(), L->getHeader());
14379 Pair.first; Pair = getPredecessorWithUniqueSuccessorForBB(Pair.first)) {
14380
14381 const BranchInst *LoopEntryPredicate =
14382 dyn_cast<BranchInst>(Pair.first->getTerminator());
14383 if (!LoopEntryPredicate || LoopEntryPredicate->isUnconditional())
14384 continue;
14385
14386 Terms.emplace_back(LoopEntryPredicate->getCondition(),
14387 LoopEntryPredicate->getSuccessor(0) == Pair.second);
14388 }
14389
14390 // Now apply the information from the collected conditions to RewriteMap.
14391 // Conditions are processed in reverse order, so the earliest conditions is
14392 // processed first. This ensures the SCEVs with the shortest dependency chains
14393 // are constructed first.
14394 DenseMap<const SCEV *, const SCEV *> RewriteMap;
14395 for (auto &E : reverse(Terms)) {
14396 bool EnterIfTrue = E.second;
14397 SmallVector<Value *, 8> Worklist;
14398 SmallPtrSet<Value *, 8> Visited;
14399 Worklist.push_back(E.first);
14400 while (!Worklist.empty()) {
14401 Value *Cond = Worklist.pop_back_val();
14402 if (!Visited.insert(Cond).second)
14403 continue;
14404
14405 if (auto *Cmp = dyn_cast<ICmpInst>(Cond)) {
14406 auto Predicate =
14407 EnterIfTrue ? Cmp->getPredicate() : Cmp->getInversePredicate();
14408 CollectCondition(Predicate, getSCEV(Cmp->getOperand(0)),
14409 getSCEV(Cmp->getOperand(1)), RewriteMap);
14410 continue;
14411 }
14412
14413 Value *L, *R;
14414 if (EnterIfTrue ? match(Cond, m_LogicalAnd(m_Value(L), m_Value(R)))
14415 : match(Cond, m_LogicalOr(m_Value(L), m_Value(R)))) {
14416 Worklist.push_back(L);
14417 Worklist.push_back(R);
14418 }
14419 }
14420 }
14421
14422 // Also collect information from assumptions dominating the loop.
14423 for (auto &AssumeVH : AC.assumptions()) {
14424 if (!AssumeVH)
14425 continue;
14426 auto *AssumeI = cast<CallInst>(AssumeVH);
14427 auto *Cmp = dyn_cast<ICmpInst>(AssumeI->getOperand(0));
14428 if (!Cmp || !DT.dominates(AssumeI, L->getHeader()))
14429 continue;
14430 CollectCondition(Cmp->getPredicate(), getSCEV(Cmp->getOperand(0)),
14431 getSCEV(Cmp->getOperand(1)), RewriteMap);
14432 }
14433
14434 if (RewriteMap.empty())
14435 return Expr;
14436
14437 // Now that all rewrite information is collect, rewrite the collected
14438 // expressions with the information in the map. This applies information to
14439 // sub-expressions.
14440 if (ExprsToRewrite.size() > 1) {
14441 for (const SCEV *Expr : ExprsToRewrite) {
14442 const SCEV *RewriteTo = RewriteMap[Expr];
14443 RewriteMap.erase(Expr);
14444 SCEVLoopGuardRewriter Rewriter(*this, RewriteMap);
14445 RewriteMap.insert({Expr, Rewriter.visit(RewriteTo)});
14446 }
14447 }
14448
14449 SCEVLoopGuardRewriter Rewriter(*this, RewriteMap);
14450 return Rewriter.visit(Expr);
14451}