Bug Summary

File:llvm/lib/Analysis/ScalarEvolution.cpp
Warning:line 6225, column 23
Called C++ object pointer is null

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -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 -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -fno-split-dwarf-inlining -debugger-tuning=gdb -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-12/lib/clang/12.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/build-llvm/lib/Analysis -I /build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis -I /build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/build-llvm/include -I /build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-12/lib/clang/12.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/build-llvm/lib/Analysis -fdebug-prefix-map=/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -o /tmp/scan-build-2020-09-17-195756-12974-1 -x c++ /build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp

/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/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/ScalarEvolutionDivision.h"
83#include "llvm/Analysis/ScalarEvolutionExpressions.h"
84#include "llvm/Analysis/TargetLibraryInfo.h"
85#include "llvm/Analysis/ValueTracking.h"
86#include "llvm/Config/llvm-config.h"
87#include "llvm/IR/Argument.h"
88#include "llvm/IR/BasicBlock.h"
89#include "llvm/IR/CFG.h"
90#include "llvm/IR/Constant.h"
91#include "llvm/IR/ConstantRange.h"
92#include "llvm/IR/Constants.h"
93#include "llvm/IR/DataLayout.h"
94#include "llvm/IR/DerivedTypes.h"
95#include "llvm/IR/Dominators.h"
96#include "llvm/IR/Function.h"
97#include "llvm/IR/GlobalAlias.h"
98#include "llvm/IR/GlobalValue.h"
99#include "llvm/IR/GlobalVariable.h"
100#include "llvm/IR/InstIterator.h"
101#include "llvm/IR/InstrTypes.h"
102#include "llvm/IR/Instruction.h"
103#include "llvm/IR/Instructions.h"
104#include "llvm/IR/IntrinsicInst.h"
105#include "llvm/IR/Intrinsics.h"
106#include "llvm/IR/LLVMContext.h"
107#include "llvm/IR/Metadata.h"
108#include "llvm/IR/Operator.h"
109#include "llvm/IR/PatternMatch.h"
110#include "llvm/IR/Type.h"
111#include "llvm/IR/Use.h"
112#include "llvm/IR/User.h"
113#include "llvm/IR/Value.h"
114#include "llvm/IR/Verifier.h"
115#include "llvm/InitializePasses.h"
116#include "llvm/Pass.h"
117#include "llvm/Support/Casting.h"
118#include "llvm/Support/CommandLine.h"
119#include "llvm/Support/Compiler.h"
120#include "llvm/Support/Debug.h"
121#include "llvm/Support/ErrorHandling.h"
122#include "llvm/Support/KnownBits.h"
123#include "llvm/Support/SaveAndRestore.h"
124#include "llvm/Support/raw_ostream.h"
125#include <algorithm>
126#include <cassert>
127#include <climits>
128#include <cstddef>
129#include <cstdint>
130#include <cstdlib>
131#include <map>
132#include <memory>
133#include <tuple>
134#include <utility>
135#include <vector>
136
137using namespace llvm;
138
139#define DEBUG_TYPE"scalar-evolution" "scalar-evolution"
140
141STATISTIC(NumArrayLenItCounts,static llvm::Statistic NumArrayLenItCounts = {"scalar-evolution"
, "NumArrayLenItCounts", "Number of trip counts computed with array length"
}
142 "Number of trip counts computed with array length")static llvm::Statistic NumArrayLenItCounts = {"scalar-evolution"
, "NumArrayLenItCounts", "Number of trip counts computed with array length"
}
;
143STATISTIC(NumTripCountsComputed,static llvm::Statistic NumTripCountsComputed = {"scalar-evolution"
, "NumTripCountsComputed", "Number of loops with predictable loop counts"
}
144 "Number of loops with predictable loop counts")static llvm::Statistic NumTripCountsComputed = {"scalar-evolution"
, "NumTripCountsComputed", "Number of loops with predictable loop counts"
}
;
145STATISTIC(NumTripCountsNotComputed,static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution"
, "NumTripCountsNotComputed", "Number of loops without predictable loop counts"
}
146 "Number of loops without predictable loop counts")static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution"
, "NumTripCountsNotComputed", "Number of loops without predictable loop counts"
}
;
147STATISTIC(NumBruteForceTripCountsComputed,static llvm::Statistic NumBruteForceTripCountsComputed = {"scalar-evolution"
, "NumBruteForceTripCountsComputed", "Number of loops with trip counts computed by force"
}
148 "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"
}
;
149
150static cl::opt<unsigned>
151MaxBruteForceIterations("scalar-evolution-max-iterations", cl::ReallyHidden,
152 cl::ZeroOrMore,
153 cl::desc("Maximum number of iterations SCEV will "
154 "symbolically execute a constant "
155 "derived loop"),
156 cl::init(100));
157
158// FIXME: Enable this with EXPENSIVE_CHECKS when the test suite is clean.
159static cl::opt<bool> VerifySCEV(
160 "verify-scev", cl::Hidden,
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
229
230//===----------------------------------------------------------------------===//
231// SCEV class definitions
232//===----------------------------------------------------------------------===//
233
234//===----------------------------------------------------------------------===//
235// Implementation of the SCEV class.
236//
237
238#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
239LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void SCEV::dump() const {
240 print(dbgs());
241 dbgs() << '\n';
242}
243#endif
244
245void SCEV::print(raw_ostream &OS) const {
246 switch (static_cast<SCEVTypes>(getSCEVType())) {
247 case scConstant:
248 cast<SCEVConstant>(this)->getValue()->printAsOperand(OS, false);
249 return;
250 case scTruncate: {
251 const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(this);
252 const SCEV *Op = Trunc->getOperand();
253 OS << "(trunc " << *Op->getType() << " " << *Op << " to "
254 << *Trunc->getType() << ")";
255 return;
256 }
257 case scZeroExtend: {
258 const SCEVZeroExtendExpr *ZExt = cast<SCEVZeroExtendExpr>(this);
259 const SCEV *Op = ZExt->getOperand();
260 OS << "(zext " << *Op->getType() << " " << *Op << " to "
261 << *ZExt->getType() << ")";
262 return;
263 }
264 case scSignExtend: {
265 const SCEVSignExtendExpr *SExt = cast<SCEVSignExtendExpr>(this);
266 const SCEV *Op = SExt->getOperand();
267 OS << "(sext " << *Op->getType() << " " << *Op << " to "
268 << *SExt->getType() << ")";
269 return;
270 }
271 case scAddRecExpr: {
272 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(this);
273 OS << "{" << *AR->getOperand(0);
274 for (unsigned i = 1, e = AR->getNumOperands(); i != e; ++i)
275 OS << ",+," << *AR->getOperand(i);
276 OS << "}<";
277 if (AR->hasNoUnsignedWrap())
278 OS << "nuw><";
279 if (AR->hasNoSignedWrap())
280 OS << "nsw><";
281 if (AR->hasNoSelfWrap() &&
282 !AR->getNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW)))
283 OS << "nw><";
284 AR->getLoop()->getHeader()->printAsOperand(OS, /*PrintType=*/false);
285 OS << ">";
286 return;
287 }
288 case scAddExpr:
289 case scMulExpr:
290 case scUMaxExpr:
291 case scSMaxExpr:
292 case scUMinExpr:
293 case scSMinExpr: {
294 const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(this);
295 const char *OpStr = nullptr;
296 switch (NAry->getSCEVType()) {
297 case scAddExpr: OpStr = " + "; break;
298 case scMulExpr: OpStr = " * "; break;
299 case scUMaxExpr: OpStr = " umax "; break;
300 case scSMaxExpr: OpStr = " smax "; break;
301 case scUMinExpr:
302 OpStr = " umin ";
303 break;
304 case scSMinExpr:
305 OpStr = " smin ";
306 break;
307 }
308 OS << "(";
309 for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end();
310 I != E; ++I) {
311 OS << **I;
312 if (std::next(I) != E)
313 OS << OpStr;
314 }
315 OS << ")";
316 switch (NAry->getSCEVType()) {
317 case scAddExpr:
318 case scMulExpr:
319 if (NAry->hasNoUnsignedWrap())
320 OS << "<nuw>";
321 if (NAry->hasNoSignedWrap())
322 OS << "<nsw>";
323 }
324 return;
325 }
326 case scUDivExpr: {
327 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(this);
328 OS << "(" << *UDiv->getLHS() << " /u " << *UDiv->getRHS() << ")";
329 return;
330 }
331 case scUnknown: {
332 const SCEVUnknown *U = cast<SCEVUnknown>(this);
333 Type *AllocTy;
334 if (U->isSizeOf(AllocTy)) {
335 OS << "sizeof(" << *AllocTy << ")";
336 return;
337 }
338 if (U->isAlignOf(AllocTy)) {
339 OS << "alignof(" << *AllocTy << ")";
340 return;
341 }
342
343 Type *CTy;
344 Constant *FieldNo;
345 if (U->isOffsetOf(CTy, FieldNo)) {
346 OS << "offsetof(" << *CTy << ", ";
347 FieldNo->printAsOperand(OS, false);
348 OS << ")";
349 return;
350 }
351
352 // Otherwise just print it normally.
353 U->getValue()->printAsOperand(OS, false);
354 return;
355 }
356 case scCouldNotCompute:
357 OS << "***COULDNOTCOMPUTE***";
358 return;
359 }
360 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 360)
;
361}
362
363Type *SCEV::getType() const {
364 switch (static_cast<SCEVTypes>(getSCEVType())) {
365 case scConstant:
366 return cast<SCEVConstant>(this)->getType();
367 case scTruncate:
368 case scZeroExtend:
369 case scSignExtend:
370 return cast<SCEVCastExpr>(this)->getType();
371 case scAddRecExpr:
372 case scMulExpr:
373 case scUMaxExpr:
374 case scSMaxExpr:
375 case scUMinExpr:
376 case scSMinExpr:
377 return cast<SCEVNAryExpr>(this)->getType();
378 case scAddExpr:
379 return cast<SCEVAddExpr>(this)->getType();
380 case scUDivExpr:
381 return cast<SCEVUDivExpr>(this)->getType();
382 case scUnknown:
383 return cast<SCEVUnknown>(this)->getType();
384 case scCouldNotCompute:
385 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 385)
;
386 }
387 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 387)
;
388}
389
390bool SCEV::isZero() const {
391 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
392 return SC->getValue()->isZero();
393 return false;
394}
395
396bool SCEV::isOne() const {
397 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
398 return SC->getValue()->isOne();
399 return false;
400}
401
402bool SCEV::isAllOnesValue() const {
403 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
404 return SC->getValue()->isMinusOne();
405 return false;
406}
407
408bool SCEV::isNonConstantNegative() const {
409 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(this);
410 if (!Mul) return false;
411
412 // If there is a constant factor, it will be first.
413 const SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0));
414 if (!SC) return false;
415
416 // Return true if the value is negative, this matches things like (-42 * V).
417 return SC->getAPInt().isNegative();
418}
419
420SCEVCouldNotCompute::SCEVCouldNotCompute() :
421 SCEV(FoldingSetNodeIDRef(), scCouldNotCompute, 0) {}
422
423bool SCEVCouldNotCompute::classof(const SCEV *S) {
424 return S->getSCEVType() == scCouldNotCompute;
425}
426
427const SCEV *ScalarEvolution::getConstant(ConstantInt *V) {
428 FoldingSetNodeID ID;
429 ID.AddInteger(scConstant);
430 ID.AddPointer(V);
431 void *IP = nullptr;
432 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
433 SCEV *S = new (SCEVAllocator) SCEVConstant(ID.Intern(SCEVAllocator), V);
434 UniqueSCEVs.InsertNode(S, IP);
435 return S;
436}
437
438const SCEV *ScalarEvolution::getConstant(const APInt &Val) {
439 return getConstant(ConstantInt::get(getContext(), Val));
440}
441
442const SCEV *
443ScalarEvolution::getConstant(Type *Ty, uint64_t V, bool isSigned) {
444 IntegerType *ITy = cast<IntegerType>(getEffectiveSCEVType(Ty));
445 return getConstant(ConstantInt::get(ITy, V, isSigned));
446}
447
448SCEVCastExpr::SCEVCastExpr(const FoldingSetNodeIDRef ID,
449 unsigned SCEVTy, const SCEV *op, Type *ty)
450 : SCEV(ID, SCEVTy, computeExpressionSize(op)), Ty(ty) {
451 Operands[0] = op;
452}
453
454SCEVTruncateExpr::SCEVTruncateExpr(const FoldingSetNodeIDRef ID,
455 const SCEV *op, Type *ty)
456 : SCEVCastExpr(ID, scTruncate, op, ty) {
457 assert(getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((getOperand()->getType()->isIntOrPtrTy() && Ty
->isIntOrPtrTy() && "Cannot truncate non-integer value!"
) ? static_cast<void> (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate non-integer value!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 458, __PRETTY_FUNCTION__))
458 "Cannot truncate non-integer value!")((getOperand()->getType()->isIntOrPtrTy() && Ty
->isIntOrPtrTy() && "Cannot truncate non-integer value!"
) ? static_cast<void> (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate non-integer value!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 458, __PRETTY_FUNCTION__))
;
459}
460
461SCEVZeroExtendExpr::SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID,
462 const SCEV *op, Type *ty)
463 : SCEVCastExpr(ID, scZeroExtend, op, ty) {
464 assert(getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((getOperand()->getType()->isIntOrPtrTy() && Ty
->isIntOrPtrTy() && "Cannot zero extend non-integer value!"
) ? static_cast<void> (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot zero extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 465, __PRETTY_FUNCTION__))
465 "Cannot zero extend non-integer value!")((getOperand()->getType()->isIntOrPtrTy() && Ty
->isIntOrPtrTy() && "Cannot zero extend non-integer value!"
) ? static_cast<void> (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot zero extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 465, __PRETTY_FUNCTION__))
;
466}
467
468SCEVSignExtendExpr::SCEVSignExtendExpr(const FoldingSetNodeIDRef ID,
469 const SCEV *op, Type *ty)
470 : SCEVCastExpr(ID, scSignExtend, op, ty) {
471 assert(getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((getOperand()->getType()->isIntOrPtrTy() && Ty
->isIntOrPtrTy() && "Cannot sign extend non-integer value!"
) ? static_cast<void> (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot sign extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 472, __PRETTY_FUNCTION__))
472 "Cannot sign extend non-integer value!")((getOperand()->getType()->isIntOrPtrTy() && Ty
->isIntOrPtrTy() && "Cannot sign extend non-integer value!"
) ? static_cast<void> (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot sign extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 472, __PRETTY_FUNCTION__))
;
473}
474
475void SCEVUnknown::deleted() {
476 // Clear this SCEVUnknown from various maps.
477 SE->forgetMemoizedResults(this);
478
479 // Remove this SCEVUnknown from the uniquing map.
480 SE->UniqueSCEVs.RemoveNode(this);
481
482 // Release the value.
483 setValPtr(nullptr);
484}
485
486void SCEVUnknown::allUsesReplacedWith(Value *New) {
487 // Remove this SCEVUnknown from the uniquing map.
488 SE->UniqueSCEVs.RemoveNode(this);
489
490 // Update this SCEVUnknown to point to the new value. This is needed
491 // because there may still be outstanding SCEVs which still point to
492 // this SCEVUnknown.
493 setValPtr(New);
494}
495
496bool SCEVUnknown::isSizeOf(Type *&AllocTy) const {
497 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
498 if (VCE->getOpcode() == Instruction::PtrToInt)
499 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
500 if (CE->getOpcode() == Instruction::GetElementPtr &&
501 CE->getOperand(0)->isNullValue() &&
502 CE->getNumOperands() == 2)
503 if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(1)))
504 if (CI->isOne()) {
505 AllocTy = cast<PointerType>(CE->getOperand(0)->getType())
506 ->getElementType();
507 return true;
508 }
509
510 return false;
511}
512
513bool SCEVUnknown::isAlignOf(Type *&AllocTy) const {
514 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
515 if (VCE->getOpcode() == Instruction::PtrToInt)
516 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
517 if (CE->getOpcode() == Instruction::GetElementPtr &&
518 CE->getOperand(0)->isNullValue()) {
519 Type *Ty =
520 cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
521 if (StructType *STy = dyn_cast<StructType>(Ty))
522 if (!STy->isPacked() &&
523 CE->getNumOperands() == 3 &&
524 CE->getOperand(1)->isNullValue()) {
525 if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(2)))
526 if (CI->isOne() &&
527 STy->getNumElements() == 2 &&
528 STy->getElementType(0)->isIntegerTy(1)) {
529 AllocTy = STy->getElementType(1);
530 return true;
531 }
532 }
533 }
534
535 return false;
536}
537
538bool SCEVUnknown::isOffsetOf(Type *&CTy, Constant *&FieldNo) const {
539 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
540 if (VCE->getOpcode() == Instruction::PtrToInt)
541 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
542 if (CE->getOpcode() == Instruction::GetElementPtr &&
543 CE->getNumOperands() == 3 &&
544 CE->getOperand(0)->isNullValue() &&
545 CE->getOperand(1)->isNullValue()) {
546 Type *Ty =
547 cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
548 // Ignore vector types here so that ScalarEvolutionExpander doesn't
549 // emit getelementptrs that index into vectors.
550 if (Ty->isStructTy() || Ty->isArrayTy()) {
551 CTy = Ty;
552 FieldNo = CE->getOperand(2);
553 return true;
554 }
555 }
556
557 return false;
558}
559
560//===----------------------------------------------------------------------===//
561// SCEV Utilities
562//===----------------------------------------------------------------------===//
563
564/// Compare the two values \p LV and \p RV in terms of their "complexity" where
565/// "complexity" is a partial (and somewhat ad-hoc) relation used to order
566/// operands in SCEV expressions. \p EqCache is a set of pairs of values that
567/// have been previously deemed to be "equally complex" by this routine. It is
568/// intended to avoid exponential time complexity in cases like:
569///
570/// %a = f(%x, %y)
571/// %b = f(%a, %a)
572/// %c = f(%b, %b)
573///
574/// %d = f(%x, %y)
575/// %e = f(%d, %d)
576/// %f = f(%e, %e)
577///
578/// CompareValueComplexity(%f, %c)
579///
580/// Since we do not continue running this routine on expression trees once we
581/// have seen unequal values, there is no need to track them in the cache.
582static int
583CompareValueComplexity(EquivalenceClasses<const Value *> &EqCacheValue,
584 const LoopInfo *const LI, Value *LV, Value *RV,
585 unsigned Depth) {
586 if (Depth > MaxValueCompareDepth || EqCacheValue.isEquivalent(LV, RV))
587 return 0;
588
589 // Order pointer values after integer values. This helps SCEVExpander form
590 // GEPs.
591 bool LIsPointer = LV->getType()->isPointerTy(),
592 RIsPointer = RV->getType()->isPointerTy();
593 if (LIsPointer != RIsPointer)
594 return (int)LIsPointer - (int)RIsPointer;
595
596 // Compare getValueID values.
597 unsigned LID = LV->getValueID(), RID = RV->getValueID();
598 if (LID != RID)
599 return (int)LID - (int)RID;
600
601 // Sort arguments by their position.
602 if (const auto *LA = dyn_cast<Argument>(LV)) {
603 const auto *RA = cast<Argument>(RV);
604 unsigned LArgNo = LA->getArgNo(), RArgNo = RA->getArgNo();
605 return (int)LArgNo - (int)RArgNo;
606 }
607
608 if (const auto *LGV = dyn_cast<GlobalValue>(LV)) {
609 const auto *RGV = cast<GlobalValue>(RV);
610
611 const auto IsGVNameSemantic = [&](const GlobalValue *GV) {
612 auto LT = GV->getLinkage();
613 return !(GlobalValue::isPrivateLinkage(LT) ||
614 GlobalValue::isInternalLinkage(LT));
615 };
616
617 // Use the names to distinguish the two values, but only if the
618 // names are semantically important.
619 if (IsGVNameSemantic(LGV) && IsGVNameSemantic(RGV))
620 return LGV->getName().compare(RGV->getName());
621 }
622
623 // For instructions, compare their loop depth, and their operand count. This
624 // is pretty loose.
625 if (const auto *LInst = dyn_cast<Instruction>(LV)) {
626 const auto *RInst = cast<Instruction>(RV);
627
628 // Compare loop depths.
629 const BasicBlock *LParent = LInst->getParent(),
630 *RParent = RInst->getParent();
631 if (LParent != RParent) {
632 unsigned LDepth = LI->getLoopDepth(LParent),
633 RDepth = LI->getLoopDepth(RParent);
634 if (LDepth != RDepth)
635 return (int)LDepth - (int)RDepth;
636 }
637
638 // Compare the number of operands.
639 unsigned LNumOps = LInst->getNumOperands(),
640 RNumOps = RInst->getNumOperands();
641 if (LNumOps != RNumOps)
642 return (int)LNumOps - (int)RNumOps;
643
644 for (unsigned Idx : seq(0u, LNumOps)) {
645 int Result =
646 CompareValueComplexity(EqCacheValue, LI, LInst->getOperand(Idx),
647 RInst->getOperand(Idx), Depth + 1);
648 if (Result != 0)
649 return Result;
650 }
651 }
652
653 EqCacheValue.unionSets(LV, RV);
654 return 0;
655}
656
657// Return negative, zero, or positive, if LHS is less than, equal to, or greater
658// than RHS, respectively. A three-way result allows recursive comparisons to be
659// more efficient.
660static int CompareSCEVComplexity(
661 EquivalenceClasses<const SCEV *> &EqCacheSCEV,
662 EquivalenceClasses<const Value *> &EqCacheValue,
663 const LoopInfo *const LI, const SCEV *LHS, const SCEV *RHS,
664 DominatorTree &DT, unsigned Depth = 0) {
665 // Fast-path: SCEVs are uniqued so we can do a quick equality check.
666 if (LHS == RHS)
667 return 0;
668
669 // Primarily, sort the SCEVs by their getSCEVType().
670 unsigned LType = LHS->getSCEVType(), RType = RHS->getSCEVType();
671 if (LType != RType)
672 return (int)LType - (int)RType;
673
674 if (Depth > MaxSCEVCompareDepth || EqCacheSCEV.isEquivalent(LHS, RHS))
675 return 0;
676 // Aside from the getSCEVType() ordering, the particular ordering
677 // isn't very important except that it's beneficial to be consistent,
678 // so that (a + b) and (b + a) don't end up as different expressions.
679 switch (static_cast<SCEVTypes>(LType)) {
680 case scUnknown: {
681 const SCEVUnknown *LU = cast<SCEVUnknown>(LHS);
682 const SCEVUnknown *RU = cast<SCEVUnknown>(RHS);
683
684 int X = CompareValueComplexity(EqCacheValue, LI, LU->getValue(),
685 RU->getValue(), Depth + 1);
686 if (X == 0)
687 EqCacheSCEV.unionSets(LHS, RHS);
688 return X;
689 }
690
691 case scConstant: {
692 const SCEVConstant *LC = cast<SCEVConstant>(LHS);
693 const SCEVConstant *RC = cast<SCEVConstant>(RHS);
694
695 // Compare constant values.
696 const APInt &LA = LC->getAPInt();
697 const APInt &RA = RC->getAPInt();
698 unsigned LBitWidth = LA.getBitWidth(), RBitWidth = RA.getBitWidth();
699 if (LBitWidth != RBitWidth)
700 return (int)LBitWidth - (int)RBitWidth;
701 return LA.ult(RA) ? -1 : 1;
702 }
703
704 case scAddRecExpr: {
705 const SCEVAddRecExpr *LA = cast<SCEVAddRecExpr>(LHS);
706 const SCEVAddRecExpr *RA = cast<SCEVAddRecExpr>(RHS);
707
708 // There is always a dominance between two recs that are used by one SCEV,
709 // so we can safely sort recs by loop header dominance. We require such
710 // order in getAddExpr.
711 const Loop *LLoop = LA->getLoop(), *RLoop = RA->getLoop();
712 if (LLoop != RLoop) {
713 const BasicBlock *LHead = LLoop->getHeader(), *RHead = RLoop->getHeader();
714 assert(LHead != RHead && "Two loops share the same header?")((LHead != RHead && "Two loops share the same header?"
) ? static_cast<void> (0) : __assert_fail ("LHead != RHead && \"Two loops share the same header?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 714, __PRETTY_FUNCTION__))
;
715 if (DT.dominates(LHead, RHead))
716 return 1;
717 else
718 assert(DT.dominates(RHead, LHead) &&((DT.dominates(RHead, LHead) && "No dominance between recurrences used by one SCEV?"
) ? static_cast<void> (0) : __assert_fail ("DT.dominates(RHead, LHead) && \"No dominance between recurrences used by one SCEV?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 719, __PRETTY_FUNCTION__))
719 "No dominance between recurrences used by one SCEV?")((DT.dominates(RHead, LHead) && "No dominance between recurrences used by one SCEV?"
) ? static_cast<void> (0) : __assert_fail ("DT.dominates(RHead, LHead) && \"No dominance between recurrences used by one SCEV?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 719, __PRETTY_FUNCTION__))
;
720 return -1;
721 }
722
723 // Addrec complexity grows with operand count.
724 unsigned LNumOps = LA->getNumOperands(), RNumOps = RA->getNumOperands();
725 if (LNumOps != RNumOps)
726 return (int)LNumOps - (int)RNumOps;
727
728 // Lexicographically compare.
729 for (unsigned i = 0; i != LNumOps; ++i) {
730 int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
731 LA->getOperand(i), RA->getOperand(i), DT,
732 Depth + 1);
733 if (X != 0)
734 return X;
735 }
736 EqCacheSCEV.unionSets(LHS, RHS);
737 return 0;
738 }
739
740 case scAddExpr:
741 case scMulExpr:
742 case scSMaxExpr:
743 case scUMaxExpr:
744 case scSMinExpr:
745 case scUMinExpr: {
746 const SCEVNAryExpr *LC = cast<SCEVNAryExpr>(LHS);
747 const SCEVNAryExpr *RC = cast<SCEVNAryExpr>(RHS);
748
749 // Lexicographically compare n-ary expressions.
750 unsigned LNumOps = LC->getNumOperands(), RNumOps = RC->getNumOperands();
751 if (LNumOps != RNumOps)
752 return (int)LNumOps - (int)RNumOps;
753
754 for (unsigned i = 0; i != LNumOps; ++i) {
755 int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
756 LC->getOperand(i), RC->getOperand(i), DT,
757 Depth + 1);
758 if (X != 0)
759 return X;
760 }
761 EqCacheSCEV.unionSets(LHS, RHS);
762 return 0;
763 }
764
765 case scUDivExpr: {
766 const SCEVUDivExpr *LC = cast<SCEVUDivExpr>(LHS);
767 const SCEVUDivExpr *RC = cast<SCEVUDivExpr>(RHS);
768
769 // Lexicographically compare udiv expressions.
770 int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getLHS(),
771 RC->getLHS(), DT, Depth + 1);
772 if (X != 0)
773 return X;
774 X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getRHS(),
775 RC->getRHS(), DT, Depth + 1);
776 if (X == 0)
777 EqCacheSCEV.unionSets(LHS, RHS);
778 return X;
779 }
780
781 case scTruncate:
782 case scZeroExtend:
783 case scSignExtend: {
784 const SCEVCastExpr *LC = cast<SCEVCastExpr>(LHS);
785 const SCEVCastExpr *RC = cast<SCEVCastExpr>(RHS);
786
787 // Compare cast expressions by operand.
788 int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
789 LC->getOperand(), RC->getOperand(), DT,
790 Depth + 1);
791 if (X == 0)
792 EqCacheSCEV.unionSets(LHS, RHS);
793 return X;
794 }
795
796 case scCouldNotCompute:
797 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 797)
;
798 }
799 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 799)
;
800}
801
802/// Given a list of SCEV objects, order them by their complexity, and group
803/// objects of the same complexity together by value. When this routine is
804/// finished, we know that any duplicates in the vector are consecutive and that
805/// complexity is monotonically increasing.
806///
807/// Note that we go take special precautions to ensure that we get deterministic
808/// results from this routine. In other words, we don't want the results of
809/// this to depend on where the addresses of various SCEV objects happened to
810/// land in memory.
811static void GroupByComplexity(SmallVectorImpl<const SCEV *> &Ops,
812 LoopInfo *LI, DominatorTree &DT) {
813 if (Ops.size() < 2) return; // Noop
814
815 EquivalenceClasses<const SCEV *> EqCacheSCEV;
816 EquivalenceClasses<const Value *> EqCacheValue;
817 if (Ops.size() == 2) {
818 // This is the common case, which also happens to be trivially simple.
819 // Special case it.
820 const SCEV *&LHS = Ops[0], *&RHS = Ops[1];
821 if (CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, RHS, LHS, DT) < 0)
822 std::swap(LHS, RHS);
823 return;
824 }
825
826 // Do the rough sort by complexity.
827 llvm::stable_sort(Ops, [&](const SCEV *LHS, const SCEV *RHS) {
828 return CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LHS, RHS, DT) <
829 0;
830 });
831
832 // Now that we are sorted by complexity, group elements of the same
833 // complexity. Note that this is, at worst, N^2, but the vector is likely to
834 // be extremely short in practice. Note that we take this approach because we
835 // do not want to depend on the addresses of the objects we are grouping.
836 for (unsigned i = 0, e = Ops.size(); i != e-2; ++i) {
837 const SCEV *S = Ops[i];
838 unsigned Complexity = S->getSCEVType();
839
840 // If there are any objects of the same complexity and same value as this
841 // one, group them.
842 for (unsigned j = i+1; j != e && Ops[j]->getSCEVType() == Complexity; ++j) {
843 if (Ops[j] == S) { // Found a duplicate.
844 // Move it to immediately after i'th element.
845 std::swap(Ops[i+1], Ops[j]);
846 ++i; // no need to rescan it.
847 if (i == e-2) return; // Done!
848 }
849 }
850 }
851}
852
853/// Returns true if \p Ops contains a huge SCEV (the subtree of S contains at
854/// least HugeExprThreshold nodes).
855static bool hasHugeExpression(ArrayRef<const SCEV *> Ops) {
856 return any_of(Ops, [](const SCEV *S) {
857 return S->getExpressionSize() >= HugeExprThreshold;
858 });
859}
860
861//===----------------------------------------------------------------------===//
862// Simple SCEV method implementations
863//===----------------------------------------------------------------------===//
864
865/// Compute BC(It, K). The result has width W. Assume, K > 0.
866static const SCEV *BinomialCoefficient(const SCEV *It, unsigned K,
867 ScalarEvolution &SE,
868 Type *ResultTy) {
869 // Handle the simplest case efficiently.
870 if (K == 1)
871 return SE.getTruncateOrZeroExtend(It, ResultTy);
872
873 // We are using the following formula for BC(It, K):
874 //
875 // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / K!
876 //
877 // Suppose, W is the bitwidth of the return value. We must be prepared for
878 // overflow. Hence, we must assure that the result of our computation is
879 // equal to the accurate one modulo 2^W. Unfortunately, division isn't
880 // safe in modular arithmetic.
881 //
882 // However, this code doesn't use exactly that formula; the formula it uses
883 // is something like the following, where T is the number of factors of 2 in
884 // K! (i.e. trailing zeros in the binary representation of K!), and ^ is
885 // exponentiation:
886 //
887 // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / 2^T / (K! / 2^T)
888 //
889 // This formula is trivially equivalent to the previous formula. However,
890 // this formula can be implemented much more efficiently. The trick is that
891 // K! / 2^T is odd, and exact division by an odd number *is* safe in modular
892 // arithmetic. To do exact division in modular arithmetic, all we have
893 // to do is multiply by the inverse. Therefore, this step can be done at
894 // width W.
895 //
896 // The next issue is how to safely do the division by 2^T. The way this
897 // is done is by doing the multiplication step at a width of at least W + T
898 // bits. This way, the bottom W+T bits of the product are accurate. Then,
899 // when we perform the division by 2^T (which is equivalent to a right shift
900 // by T), the bottom W bits are accurate. Extra bits are okay; they'll get
901 // truncated out after the division by 2^T.
902 //
903 // In comparison to just directly using the first formula, this technique
904 // is much more efficient; using the first formula requires W * K bits,
905 // but this formula less than W + K bits. Also, the first formula requires
906 // a division step, whereas this formula only requires multiplies and shifts.
907 //
908 // It doesn't matter whether the subtraction step is done in the calculation
909 // width or the input iteration count's width; if the subtraction overflows,
910 // the result must be zero anyway. We prefer here to do it in the width of
911 // the induction variable because it helps a lot for certain cases; CodeGen
912 // isn't smart enough to ignore the overflow, which leads to much less
913 // efficient code if the width of the subtraction is wider than the native
914 // register width.
915 //
916 // (It's possible to not widen at all by pulling out factors of 2 before
917 // the multiplication; for example, K=2 can be calculated as
918 // It/2*(It+(It*INT_MIN/INT_MIN)+-1). However, it requires
919 // extra arithmetic, so it's not an obvious win, and it gets
920 // much more complicated for K > 3.)
921
922 // Protection from insane SCEVs; this bound is conservative,
923 // but it probably doesn't matter.
924 if (K > 1000)
925 return SE.getCouldNotCompute();
926
927 unsigned W = SE.getTypeSizeInBits(ResultTy);
928
929 // Calculate K! / 2^T and T; we divide out the factors of two before
930 // multiplying for calculating K! / 2^T to avoid overflow.
931 // Other overflow doesn't matter because we only care about the bottom
932 // W bits of the result.
933 APInt OddFactorial(W, 1);
934 unsigned T = 1;
935 for (unsigned i = 3; i <= K; ++i) {
936 APInt Mult(W, i);
937 unsigned TwoFactors = Mult.countTrailingZeros();
938 T += TwoFactors;
939 Mult.lshrInPlace(TwoFactors);
940 OddFactorial *= Mult;
941 }
942
943 // We need at least W + T bits for the multiplication step
944 unsigned CalculationBits = W + T;
945
946 // Calculate 2^T, at width T+W.
947 APInt DivFactor = APInt::getOneBitSet(CalculationBits, T);
948
949 // Calculate the multiplicative inverse of K! / 2^T;
950 // this multiplication factor will perform the exact division by
951 // K! / 2^T.
952 APInt Mod = APInt::getSignedMinValue(W+1);
953 APInt MultiplyFactor = OddFactorial.zext(W+1);
954 MultiplyFactor = MultiplyFactor.multiplicativeInverse(Mod);
955 MultiplyFactor = MultiplyFactor.trunc(W);
956
957 // Calculate the product, at width T+W
958 IntegerType *CalculationTy = IntegerType::get(SE.getContext(),
959 CalculationBits);
960 const SCEV *Dividend = SE.getTruncateOrZeroExtend(It, CalculationTy);
961 for (unsigned i = 1; i != K; ++i) {
962 const SCEV *S = SE.getMinusSCEV(It, SE.getConstant(It->getType(), i));
963 Dividend = SE.getMulExpr(Dividend,
964 SE.getTruncateOrZeroExtend(S, CalculationTy));
965 }
966
967 // Divide by 2^T
968 const SCEV *DivResult = SE.getUDivExpr(Dividend, SE.getConstant(DivFactor));
969
970 // Truncate the result, and divide by K! / 2^T.
971
972 return SE.getMulExpr(SE.getConstant(MultiplyFactor),
973 SE.getTruncateOrZeroExtend(DivResult, ResultTy));
974}
975
976/// Return the value of this chain of recurrences at the specified iteration
977/// number. We can evaluate this recurrence by multiplying each element in the
978/// chain by the binomial coefficient corresponding to it. In other words, we
979/// can evaluate {A,+,B,+,C,+,D} as:
980///
981/// A*BC(It, 0) + B*BC(It, 1) + C*BC(It, 2) + D*BC(It, 3)
982///
983/// where BC(It, k) stands for binomial coefficient.
984const SCEV *SCEVAddRecExpr::evaluateAtIteration(const SCEV *It,
985 ScalarEvolution &SE) const {
986 const SCEV *Result = getStart();
987 for (unsigned i = 1, e = getNumOperands(); i != e; ++i) {
988 // The computation is correct in the face of overflow provided that the
989 // multiplication is performed _after_ the evaluation of the binomial
990 // coefficient.
991 const SCEV *Coeff = BinomialCoefficient(It, i, SE, getType());
992 if (isa<SCEVCouldNotCompute>(Coeff))
993 return Coeff;
994
995 Result = SE.getAddExpr(Result, SE.getMulExpr(getOperand(i), Coeff));
996 }
997 return Result;
998}
999
1000//===----------------------------------------------------------------------===//
1001// SCEV Expression folder implementations
1002//===----------------------------------------------------------------------===//
1003
1004const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op, Type *Ty,
1005 unsigned Depth) {
1006 assert(getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(
Ty) && "This is not a truncating conversion!") ? static_cast
<void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) && \"This is not a truncating conversion!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1007, __PRETTY_FUNCTION__))
1007 "This is not a truncating conversion!")((getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(
Ty) && "This is not a truncating conversion!") ? static_cast
<void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) && \"This is not a truncating conversion!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1007, __PRETTY_FUNCTION__))
;
1008 assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1009, __PRETTY_FUNCTION__))
1009 "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1009, __PRETTY_FUNCTION__))
;
1010 Ty = getEffectiveSCEVType(Ty);
1011
1012 FoldingSetNodeID ID;
1013 ID.AddInteger(scTruncate);
1014 ID.AddPointer(Op);
1015 ID.AddPointer(Ty);
1016 void *IP = nullptr;
1017 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1018
1019 // Fold if the operand is constant.
1020 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1021 return getConstant(
1022 cast<ConstantInt>(ConstantExpr::getTrunc(SC->getValue(), Ty)));
1023
1024 // trunc(trunc(x)) --> trunc(x)
1025 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op))
1026 return getTruncateExpr(ST->getOperand(), Ty, Depth + 1);
1027
1028 // trunc(sext(x)) --> sext(x) if widening or trunc(x) if narrowing
1029 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1030 return getTruncateOrSignExtend(SS->getOperand(), Ty, Depth + 1);
1031
1032 // trunc(zext(x)) --> zext(x) if widening or trunc(x) if narrowing
1033 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1034 return getTruncateOrZeroExtend(SZ->getOperand(), Ty, Depth + 1);
1035
1036 if (Depth > MaxCastDepth) {
1037 SCEV *S =
1038 new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator), Op, Ty);
1039 UniqueSCEVs.InsertNode(S, IP);
1040 addToLoopUseLists(S);
1041 return S;
1042 }
1043
1044 // trunc(x1 + ... + xN) --> trunc(x1) + ... + trunc(xN) and
1045 // trunc(x1 * ... * xN) --> trunc(x1) * ... * trunc(xN),
1046 // if after transforming we have at most one truncate, not counting truncates
1047 // that replace other casts.
1048 if (isa<SCEVAddExpr>(Op) || isa<SCEVMulExpr>(Op)) {
1049 auto *CommOp = cast<SCEVCommutativeExpr>(Op);
1050 SmallVector<const SCEV *, 4> Operands;
1051 unsigned numTruncs = 0;
1052 for (unsigned i = 0, e = CommOp->getNumOperands(); i != e && numTruncs < 2;
1053 ++i) {
1054 const SCEV *S = getTruncateExpr(CommOp->getOperand(i), Ty, Depth + 1);
1055 if (!isa<SCEVCastExpr>(CommOp->getOperand(i)) && isa<SCEVTruncateExpr>(S))
1056 numTruncs++;
1057 Operands.push_back(S);
1058 }
1059 if (numTruncs < 2) {
1060 if (isa<SCEVAddExpr>(Op))
1061 return getAddExpr(Operands);
1062 else if (isa<SCEVMulExpr>(Op))
1063 return getMulExpr(Operands);
1064 else
1065 llvm_unreachable("Unexpected SCEV type for Op.")::llvm::llvm_unreachable_internal("Unexpected SCEV type for Op."
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1065)
;
1066 }
1067 // Although we checked in the beginning that ID is not in the cache, it is
1068 // possible that during recursion and different modification ID was inserted
1069 // into the cache. So if we find it, just return it.
1070 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
1071 return S;
1072 }
1073
1074 // If the input value is a chrec scev, truncate the chrec's operands.
1075 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
1076 SmallVector<const SCEV *, 4> Operands;
1077 for (const SCEV *Op : AddRec->operands())
1078 Operands.push_back(getTruncateExpr(Op, Ty, Depth + 1));
1079 return getAddRecExpr(Operands, AddRec->getLoop(), SCEV::FlagAnyWrap);
1080 }
1081
1082 // The cast wasn't folded; create an explicit cast node. We can reuse
1083 // the existing insert position since if we get here, we won't have
1084 // made any changes which would invalidate it.
1085 SCEV *S = new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator),
1086 Op, Ty);
1087 UniqueSCEVs.InsertNode(S, IP);
1088 addToLoopUseLists(S);
1089 return S;
1090}
1091
1092// Get the limit of a recurrence such that incrementing by Step cannot cause
1093// signed overflow as long as the value of the recurrence within the
1094// loop does not exceed this limit before incrementing.
1095static const SCEV *getSignedOverflowLimitForStep(const SCEV *Step,
1096 ICmpInst::Predicate *Pred,
1097 ScalarEvolution *SE) {
1098 unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
1099 if (SE->isKnownPositive(Step)) {
1100 *Pred = ICmpInst::ICMP_SLT;
1101 return SE->getConstant(APInt::getSignedMinValue(BitWidth) -
1102 SE->getSignedRangeMax(Step));
1103 }
1104 if (SE->isKnownNegative(Step)) {
1105 *Pred = ICmpInst::ICMP_SGT;
1106 return SE->getConstant(APInt::getSignedMaxValue(BitWidth) -
1107 SE->getSignedRangeMin(Step));
1108 }
1109 return nullptr;
1110}
1111
1112// Get the limit of a recurrence such that incrementing by Step cannot cause
1113// unsigned overflow as long as the value of the recurrence within the loop does
1114// not exceed this limit before incrementing.
1115static const SCEV *getUnsignedOverflowLimitForStep(const SCEV *Step,
1116 ICmpInst::Predicate *Pred,
1117 ScalarEvolution *SE) {
1118 unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
1119 *Pred = ICmpInst::ICMP_ULT;
1120
1121 return SE->getConstant(APInt::getMinValue(BitWidth) -
1122 SE->getUnsignedRangeMax(Step));
1123}
1124
1125namespace {
1126
1127struct ExtendOpTraitsBase {
1128 typedef const SCEV *(ScalarEvolution::*GetExtendExprTy)(const SCEV *, Type *,
1129 unsigned);
1130};
1131
1132// Used to make code generic over signed and unsigned overflow.
1133template <typename ExtendOp> struct ExtendOpTraits {
1134 // Members present:
1135 //
1136 // static const SCEV::NoWrapFlags WrapType;
1137 //
1138 // static const ExtendOpTraitsBase::GetExtendExprTy GetExtendExpr;
1139 //
1140 // static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1141 // ICmpInst::Predicate *Pred,
1142 // ScalarEvolution *SE);
1143};
1144
1145template <>
1146struct ExtendOpTraits<SCEVSignExtendExpr> : public ExtendOpTraitsBase {
1147 static const SCEV::NoWrapFlags WrapType = SCEV::FlagNSW;
1148
1149 static const GetExtendExprTy GetExtendExpr;
1150
1151 static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1152 ICmpInst::Predicate *Pred,
1153 ScalarEvolution *SE) {
1154 return getSignedOverflowLimitForStep(Step, Pred, SE);
1155 }
1156};
1157
1158const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
1159 SCEVSignExtendExpr>::GetExtendExpr = &ScalarEvolution::getSignExtendExpr;
1160
1161template <>
1162struct ExtendOpTraits<SCEVZeroExtendExpr> : public ExtendOpTraitsBase {
1163 static const SCEV::NoWrapFlags WrapType = SCEV::FlagNUW;
1164
1165 static const GetExtendExprTy GetExtendExpr;
1166
1167 static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1168 ICmpInst::Predicate *Pred,
1169 ScalarEvolution *SE) {
1170 return getUnsignedOverflowLimitForStep(Step, Pred, SE);
1171 }
1172};
1173
1174const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
1175 SCEVZeroExtendExpr>::GetExtendExpr = &ScalarEvolution::getZeroExtendExpr;
1176
1177} // end anonymous namespace
1178
1179// The recurrence AR has been shown to have no signed/unsigned wrap or something
1180// close to it. Typically, if we can prove NSW/NUW for AR, then we can just as
1181// easily prove NSW/NUW for its preincrement or postincrement sibling. This
1182// allows normalizing a sign/zero extended AddRec as such: {sext/zext(Step +
1183// Start),+,Step} => {(Step + sext/zext(Start),+,Step} As a result, the
1184// expression "Step + sext/zext(PreIncAR)" is congruent with
1185// "sext/zext(PostIncAR)"
1186template <typename ExtendOpTy>
1187static const SCEV *getPreStartForExtend(const SCEVAddRecExpr *AR, Type *Ty,
1188 ScalarEvolution *SE, unsigned Depth) {
1189 auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
1190 auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
1191
1192 const Loop *L = AR->getLoop();
1193 const SCEV *Start = AR->getStart();
1194 const SCEV *Step = AR->getStepRecurrence(*SE);
1195
1196 // Check for a simple looking step prior to loop entry.
1197 const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Start);
1198 if (!SA)
1199 return nullptr;
1200
1201 // Create an AddExpr for "PreStart" after subtracting Step. Full SCEV
1202 // subtraction is expensive. For this purpose, perform a quick and dirty
1203 // difference, by checking for Step in the operand list.
1204 SmallVector<const SCEV *, 4> DiffOps;
1205 for (const SCEV *Op : SA->operands())
1206 if (Op != Step)
1207 DiffOps.push_back(Op);
1208
1209 if (DiffOps.size() == SA->getNumOperands())
1210 return nullptr;
1211
1212 // Try to prove `WrapType` (SCEV::FlagNSW or SCEV::FlagNUW) on `PreStart` +
1213 // `Step`:
1214
1215 // 1. NSW/NUW flags on the step increment.
1216 auto PreStartFlags =
1217 ScalarEvolution::maskFlags(SA->getNoWrapFlags(), SCEV::FlagNUW);
1218 const SCEV *PreStart = SE->getAddExpr(DiffOps, PreStartFlags);
1219 const SCEVAddRecExpr *PreAR = dyn_cast<SCEVAddRecExpr>(
1220 SE->getAddRecExpr(PreStart, Step, L, SCEV::FlagAnyWrap));
1221
1222 // "{S,+,X} is <nsw>/<nuw>" and "the backedge is taken at least once" implies
1223 // "S+X does not sign/unsign-overflow".
1224 //
1225
1226 const SCEV *BECount = SE->getBackedgeTakenCount(L);
1227 if (PreAR && PreAR->getNoWrapFlags(WrapType) &&
1228 !isa<SCEVCouldNotCompute>(BECount) && SE->isKnownPositive(BECount))
1229 return PreStart;
1230
1231 // 2. Direct overflow check on the step operation's expression.
1232 unsigned BitWidth = SE->getTypeSizeInBits(AR->getType());
1233 Type *WideTy = IntegerType::get(SE->getContext(), BitWidth * 2);
1234 const SCEV *OperandExtendedStart =
1235 SE->getAddExpr((SE->*GetExtendExpr)(PreStart, WideTy, Depth),
1236 (SE->*GetExtendExpr)(Step, WideTy, Depth));
1237 if ((SE->*GetExtendExpr)(Start, WideTy, Depth) == OperandExtendedStart) {
1238 if (PreAR && AR->getNoWrapFlags(WrapType)) {
1239 // If we know `AR` == {`PreStart`+`Step`,+,`Step`} is `WrapType` (FlagNSW
1240 // or FlagNUW) and that `PreStart` + `Step` is `WrapType` too, then
1241 // `PreAR` == {`PreStart`,+,`Step`} is also `WrapType`. Cache this fact.
1242 const_cast<SCEVAddRecExpr *>(PreAR)->setNoWrapFlags(WrapType);
1243 }
1244 return PreStart;
1245 }
1246
1247 // 3. Loop precondition.
1248 ICmpInst::Predicate Pred;
1249 const SCEV *OverflowLimit =
1250 ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(Step, &Pred, SE);
1251
1252 if (OverflowLimit &&
1253 SE->isLoopEntryGuardedByCond(L, Pred, PreStart, OverflowLimit))
1254 return PreStart;
1255
1256 return nullptr;
1257}
1258
1259// Get the normalized zero or sign extended expression for this AddRec's Start.
1260template <typename ExtendOpTy>
1261static const SCEV *getExtendAddRecStart(const SCEVAddRecExpr *AR, Type *Ty,
1262 ScalarEvolution *SE,
1263 unsigned Depth) {
1264 auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
1265
1266 const SCEV *PreStart = getPreStartForExtend<ExtendOpTy>(AR, Ty, SE, Depth);
1267 if (!PreStart)
1268 return (SE->*GetExtendExpr)(AR->getStart(), Ty, Depth);
1269
1270 return SE->getAddExpr((SE->*GetExtendExpr)(AR->getStepRecurrence(*SE), Ty,
1271 Depth),
1272 (SE->*GetExtendExpr)(PreStart, Ty, Depth));
1273}
1274
1275// Try to prove away overflow by looking at "nearby" add recurrences. A
1276// motivating example for this rule: if we know `{0,+,4}` is `ult` `-1` and it
1277// does not itself wrap then we can conclude that `{1,+,4}` is `nuw`.
1278//
1279// Formally:
1280//
1281// {S,+,X} == {S-T,+,X} + T
1282// => Ext({S,+,X}) == Ext({S-T,+,X} + T)
1283//
1284// If ({S-T,+,X} + T) does not overflow ... (1)
1285//
1286// RHS == Ext({S-T,+,X} + T) == Ext({S-T,+,X}) + Ext(T)
1287//
1288// If {S-T,+,X} does not overflow ... (2)
1289//
1290// RHS == Ext({S-T,+,X}) + Ext(T) == {Ext(S-T),+,Ext(X)} + Ext(T)
1291// == {Ext(S-T)+Ext(T),+,Ext(X)}
1292//
1293// If (S-T)+T does not overflow ... (3)
1294//
1295// RHS == {Ext(S-T)+Ext(T),+,Ext(X)} == {Ext(S-T+T),+,Ext(X)}
1296// == {Ext(S),+,Ext(X)} == LHS
1297//
1298// Thus, if (1), (2) and (3) are true for some T, then
1299// Ext({S,+,X}) == {Ext(S),+,Ext(X)}
1300//
1301// (3) is implied by (1) -- "(S-T)+T does not overflow" is simply "({S-T,+,X}+T)
1302// does not overflow" restricted to the 0th iteration. Therefore we only need
1303// to check for (1) and (2).
1304//
1305// In the current context, S is `Start`, X is `Step`, Ext is `ExtendOpTy` and T
1306// is `Delta` (defined below).
1307template <typename ExtendOpTy>
1308bool ScalarEvolution::proveNoWrapByVaryingStart(const SCEV *Start,
1309 const SCEV *Step,
1310 const Loop *L) {
1311 auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
1312
1313 // We restrict `Start` to a constant to prevent SCEV from spending too much
1314 // time here. It is correct (but more expensive) to continue with a
1315 // non-constant `Start` and do a general SCEV subtraction to compute
1316 // `PreStart` below.
1317 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start);
1318 if (!StartC)
1319 return false;
1320
1321 APInt StartAI = StartC->getAPInt();
1322
1323 for (unsigned Delta : {-2, -1, 1, 2}) {
1324 const SCEV *PreStart = getConstant(StartAI - Delta);
1325
1326 FoldingSetNodeID ID;
1327 ID.AddInteger(scAddRecExpr);
1328 ID.AddPointer(PreStart);
1329 ID.AddPointer(Step);
1330 ID.AddPointer(L);
1331 void *IP = nullptr;
1332 const auto *PreAR =
1333 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
1334
1335 // Give up if we don't already have the add recurrence we need because
1336 // actually constructing an add recurrence is relatively expensive.
1337 if (PreAR && PreAR->getNoWrapFlags(WrapType)) { // proves (2)
1338 const SCEV *DeltaS = getConstant(StartC->getType(), Delta);
1339 ICmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE;
1340 const SCEV *Limit = ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(
1341 DeltaS, &Pred, this);
1342 if (Limit && isKnownPredicate(Pred, PreAR, Limit)) // proves (1)
1343 return true;
1344 }
1345 }
1346
1347 return false;
1348}
1349
1350// Finds an integer D for an expression (C + x + y + ...) such that the top
1351// level addition in (D + (C - D + x + y + ...)) would not wrap (signed or
1352// unsigned) and the number of trailing zeros of (C - D + x + y + ...) is
1353// maximized, where C is the \p ConstantTerm, x, y, ... are arbitrary SCEVs, and
1354// the (C + x + y + ...) expression is \p WholeAddExpr.
1355static APInt extractConstantWithoutWrapping(ScalarEvolution &SE,
1356 const SCEVConstant *ConstantTerm,
1357 const SCEVAddExpr *WholeAddExpr) {
1358 const APInt &C = ConstantTerm->getAPInt();
1359 const unsigned BitWidth = C.getBitWidth();
1360 // Find number of trailing zeros of (x + y + ...) w/o the C first:
1361 uint32_t TZ = BitWidth;
1362 for (unsigned I = 1, E = WholeAddExpr->getNumOperands(); I < E && TZ; ++I)
1363 TZ = std::min(TZ, SE.GetMinTrailingZeros(WholeAddExpr->getOperand(I)));
1364 if (TZ) {
1365 // Set D to be as many least significant bits of C as possible while still
1366 // guaranteeing that adding D to (C - D + x + y + ...) won't cause a wrap:
1367 return TZ < BitWidth ? C.trunc(TZ).zext(BitWidth) : C;
1368 }
1369 return APInt(BitWidth, 0);
1370}
1371
1372// Finds an integer D for an affine AddRec expression {C,+,x} such that the top
1373// level addition in (D + {C-D,+,x}) would not wrap (signed or unsigned) and the
1374// number of trailing zeros of (C - D + x * n) is maximized, where C is the \p
1375// ConstantStart, x is an arbitrary \p Step, and n is the loop trip count.
1376static APInt extractConstantWithoutWrapping(ScalarEvolution &SE,
1377 const APInt &ConstantStart,
1378 const SCEV *Step) {
1379 const unsigned BitWidth = ConstantStart.getBitWidth();
1380 const uint32_t TZ = SE.GetMinTrailingZeros(Step);
1381 if (TZ)
1382 return TZ < BitWidth ? ConstantStart.trunc(TZ).zext(BitWidth)
1383 : ConstantStart;
1384 return APInt(BitWidth, 0);
1385}
1386
1387const SCEV *
1388ScalarEvolution::getZeroExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) {
1389 assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(
Ty) && "This is not an extending conversion!") ? static_cast
<void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1390, __PRETTY_FUNCTION__))
1390 "This is not an extending conversion!")((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(
Ty) && "This is not an extending conversion!") ? static_cast
<void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1390, __PRETTY_FUNCTION__))
;
1391 assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1392, __PRETTY_FUNCTION__))
1392 "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1392, __PRETTY_FUNCTION__))
;
1393 Ty = getEffectiveSCEVType(Ty);
1394
1395 // Fold if the operand is constant.
1396 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1397 return getConstant(
1398 cast<ConstantInt>(ConstantExpr::getZExt(SC->getValue(), Ty)));
1399
1400 // zext(zext(x)) --> zext(x)
1401 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1402 return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1);
1403
1404 // Before doing any expensive analysis, check to see if we've already
1405 // computed a SCEV for this Op and Ty.
1406 FoldingSetNodeID ID;
1407 ID.AddInteger(scZeroExtend);
1408 ID.AddPointer(Op);
1409 ID.AddPointer(Ty);
1410 void *IP = nullptr;
1411 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1412 if (Depth > MaxCastDepth) {
1413 SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
1414 Op, Ty);
1415 UniqueSCEVs.InsertNode(S, IP);
1416 addToLoopUseLists(S);
1417 return S;
1418 }
1419
1420 // zext(trunc(x)) --> zext(x) or x or trunc(x)
1421 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1422 // It's possible the bits taken off by the truncate were all zero bits. If
1423 // so, we should be able to simplify this further.
1424 const SCEV *X = ST->getOperand();
1425 ConstantRange CR = getUnsignedRange(X);
1426 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1427 unsigned NewBits = getTypeSizeInBits(Ty);
1428 if (CR.truncate(TruncBits).zeroExtend(NewBits).contains(
1429 CR.zextOrTrunc(NewBits)))
1430 return getTruncateOrZeroExtend(X, Ty, Depth);
1431 }
1432
1433 // If the input value is a chrec scev, and we can prove that the value
1434 // did not overflow the old, smaller, value, we can zero extend all of the
1435 // operands (often constants). This allows analysis of something like
1436 // this: for (unsigned char X = 0; X < 100; ++X) { int Y = X; }
1437 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
1438 if (AR->isAffine()) {
1439 const SCEV *Start = AR->getStart();
1440 const SCEV *Step = AR->getStepRecurrence(*this);
1441 unsigned BitWidth = getTypeSizeInBits(AR->getType());
1442 const Loop *L = AR->getLoop();
1443
1444 if (!AR->hasNoUnsignedWrap()) {
1445 auto NewFlags = proveNoWrapViaConstantRanges(AR);
1446 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags);
1447 }
1448
1449 // If we have special knowledge that this addrec won't overflow,
1450 // we don't need to do any further analysis.
1451 if (AR->hasNoUnsignedWrap())
1452 return getAddRecExpr(
1453 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1),
1454 getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
1455
1456 // Check whether the backedge-taken count is SCEVCouldNotCompute.
1457 // Note that this serves two purposes: It filters out loops that are
1458 // simply not analyzable, and it covers the case where this code is
1459 // being called from within backedge-taken count analysis, such that
1460 // attempting to ask for the backedge-taken count would likely result
1461 // in infinite recursion. In the later case, the analysis code will
1462 // cope with a conservative value, and it will take care to purge
1463 // that value once it has finished.
1464 const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(L);
1465 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
1466 // Manually compute the final value for AR, checking for
1467 // overflow.
1468
1469 // Check whether the backedge-taken count can be losslessly casted to
1470 // the addrec's type. The count is always unsigned.
1471 const SCEV *CastedMaxBECount =
1472 getTruncateOrZeroExtend(MaxBECount, Start->getType(), Depth);
1473 const SCEV *RecastedMaxBECount = getTruncateOrZeroExtend(
1474 CastedMaxBECount, MaxBECount->getType(), Depth);
1475 if (MaxBECount == RecastedMaxBECount) {
1476 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
1477 // Check whether Start+Step*MaxBECount has no unsigned overflow.
1478 const SCEV *ZMul = getMulExpr(CastedMaxBECount, Step,
1479 SCEV::FlagAnyWrap, Depth + 1);
1480 const SCEV *ZAdd = getZeroExtendExpr(getAddExpr(Start, ZMul,
1481 SCEV::FlagAnyWrap,
1482 Depth + 1),
1483 WideTy, Depth + 1);
1484 const SCEV *WideStart = getZeroExtendExpr(Start, WideTy, Depth + 1);
1485 const SCEV *WideMaxBECount =
1486 getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1);
1487 const SCEV *OperandExtendedAdd =
1488 getAddExpr(WideStart,
1489 getMulExpr(WideMaxBECount,
1490 getZeroExtendExpr(Step, WideTy, Depth + 1),
1491 SCEV::FlagAnyWrap, Depth + 1),
1492 SCEV::FlagAnyWrap, Depth + 1);
1493 if (ZAdd == OperandExtendedAdd) {
1494 // Cache knowledge of AR NUW, which is propagated to this AddRec.
1495 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1496 // Return the expression with the addrec on the outside.
1497 return getAddRecExpr(
1498 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1499 Depth + 1),
1500 getZeroExtendExpr(Step, Ty, Depth + 1), L,
1501 AR->getNoWrapFlags());
1502 }
1503 // Similar to above, only this time treat the step value as signed.
1504 // This covers loops that count down.
1505 OperandExtendedAdd =
1506 getAddExpr(WideStart,
1507 getMulExpr(WideMaxBECount,
1508 getSignExtendExpr(Step, WideTy, Depth + 1),
1509 SCEV::FlagAnyWrap, Depth + 1),
1510 SCEV::FlagAnyWrap, Depth + 1);
1511 if (ZAdd == OperandExtendedAdd) {
1512 // Cache knowledge of AR NW, which is propagated to this AddRec.
1513 // Negative step causes unsigned wrap, but it still can't self-wrap.
1514 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1515 // Return the expression with the addrec on the outside.
1516 return getAddRecExpr(
1517 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1518 Depth + 1),
1519 getSignExtendExpr(Step, Ty, Depth + 1), L,
1520 AR->getNoWrapFlags());
1521 }
1522 }
1523 }
1524
1525 // Normally, in the cases we can prove no-overflow via a
1526 // backedge guarding condition, we can also compute a backedge
1527 // taken count for the loop. The exceptions are assumptions and
1528 // guards present in the loop -- SCEV is not great at exploiting
1529 // these to compute max backedge taken counts, but can still use
1530 // these to prove lack of overflow. Use this fact to avoid
1531 // doing extra work that may not pay off.
1532 if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards ||
1533 !AC.assumptions().empty()) {
1534 // If the backedge is guarded by a comparison with the pre-inc
1535 // value the addrec is safe. Also, if the entry is guarded by
1536 // a comparison with the start value and the backedge is
1537 // guarded by a comparison with the post-inc value, the addrec
1538 // is safe.
1539 if (isKnownPositive(Step)) {
1540 const SCEV *N = getConstant(APInt::getMinValue(BitWidth) -
1541 getUnsignedRangeMax(Step));
1542 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT, AR, N) ||
1543 isKnownOnEveryIteration(ICmpInst::ICMP_ULT, AR, N)) {
1544 // Cache knowledge of AR NUW, which is propagated to this
1545 // AddRec.
1546 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1547 // Return the expression with the addrec on the outside.
1548 return getAddRecExpr(
1549 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1550 Depth + 1),
1551 getZeroExtendExpr(Step, Ty, Depth + 1), L,
1552 AR->getNoWrapFlags());
1553 }
1554 } else if (isKnownNegative(Step)) {
1555 const SCEV *N = getConstant(APInt::getMaxValue(BitWidth) -
1556 getSignedRangeMin(Step));
1557 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, AR, N) ||
1558 isKnownOnEveryIteration(ICmpInst::ICMP_UGT, AR, N)) {
1559 // Cache knowledge of AR NW, which is propagated to this
1560 // AddRec. Negative step causes unsigned wrap, but it
1561 // still can't self-wrap.
1562 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1563 // Return the expression with the addrec on the outside.
1564 return getAddRecExpr(
1565 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1566 Depth + 1),
1567 getSignExtendExpr(Step, Ty, Depth + 1), L,
1568 AR->getNoWrapFlags());
1569 }
1570 }
1571 }
1572
1573 // zext({C,+,Step}) --> (zext(D) + zext({C-D,+,Step}))<nuw><nsw>
1574 // if D + (C - D + Step * n) could be proven to not unsigned wrap
1575 // where D maximizes the number of trailing zeros of (C - D + Step * n)
1576 if (const auto *SC = dyn_cast<SCEVConstant>(Start)) {
1577 const APInt &C = SC->getAPInt();
1578 const APInt &D = extractConstantWithoutWrapping(*this, C, Step);
1579 if (D != 0) {
1580 const SCEV *SZExtD = getZeroExtendExpr(getConstant(D), Ty, Depth);
1581 const SCEV *SResidual =
1582 getAddRecExpr(getConstant(C - D), Step, L, AR->getNoWrapFlags());
1583 const SCEV *SZExtR = getZeroExtendExpr(SResidual, Ty, Depth + 1);
1584 return getAddExpr(SZExtD, SZExtR,
1585 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
1586 Depth + 1);
1587 }
1588 }
1589
1590 if (proveNoWrapByVaryingStart<SCEVZeroExtendExpr>(Start, Step, L)) {
1591 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1592 return getAddRecExpr(
1593 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1),
1594 getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
1595 }
1596 }
1597
1598 // zext(A % B) --> zext(A) % zext(B)
1599 {
1600 const SCEV *LHS;
1601 const SCEV *RHS;
1602 if (matchURem(Op, LHS, RHS))
1603 return getURemExpr(getZeroExtendExpr(LHS, Ty, Depth + 1),
1604 getZeroExtendExpr(RHS, Ty, Depth + 1));
1605 }
1606
1607 // zext(A / B) --> zext(A) / zext(B).
1608 if (auto *Div = dyn_cast<SCEVUDivExpr>(Op))
1609 return getUDivExpr(getZeroExtendExpr(Div->getLHS(), Ty, Depth + 1),
1610 getZeroExtendExpr(Div->getRHS(), Ty, Depth + 1));
1611
1612 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1613 // zext((A + B + ...)<nuw>) --> (zext(A) + zext(B) + ...)<nuw>
1614 if (SA->hasNoUnsignedWrap()) {
1615 // If the addition does not unsign overflow then we can, by definition,
1616 // commute the zero extension with the addition operation.
1617 SmallVector<const SCEV *, 4> Ops;
1618 for (const auto *Op : SA->operands())
1619 Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1));
1620 return getAddExpr(Ops, SCEV::FlagNUW, Depth + 1);
1621 }
1622
1623 // zext(C + x + y + ...) --> (zext(D) + zext((C - D) + x + y + ...))
1624 // if D + (C - D + x + y + ...) could be proven to not unsigned wrap
1625 // where D maximizes the number of trailing zeros of (C - D + x + y + ...)
1626 //
1627 // Often address arithmetics contain expressions like
1628 // (zext (add (shl X, C1), C2)), for instance, (zext (5 + (4 * X))).
1629 // This transformation is useful while proving that such expressions are
1630 // equal or differ by a small constant amount, see LoadStoreVectorizer pass.
1631 if (const auto *SC = dyn_cast<SCEVConstant>(SA->getOperand(0))) {
1632 const APInt &D = extractConstantWithoutWrapping(*this, SC, SA);
1633 if (D != 0) {
1634 const SCEV *SZExtD = getZeroExtendExpr(getConstant(D), Ty, Depth);
1635 const SCEV *SResidual =
1636 getAddExpr(getConstant(-D), SA, SCEV::FlagAnyWrap, Depth);
1637 const SCEV *SZExtR = getZeroExtendExpr(SResidual, Ty, Depth + 1);
1638 return getAddExpr(SZExtD, SZExtR,
1639 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
1640 Depth + 1);
1641 }
1642 }
1643 }
1644
1645 if (auto *SM = dyn_cast<SCEVMulExpr>(Op)) {
1646 // zext((A * B * ...)<nuw>) --> (zext(A) * zext(B) * ...)<nuw>
1647 if (SM->hasNoUnsignedWrap()) {
1648 // If the multiply does not unsign overflow then we can, by definition,
1649 // commute the zero extension with the multiply operation.
1650 SmallVector<const SCEV *, 4> Ops;
1651 for (const auto *Op : SM->operands())
1652 Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1));
1653 return getMulExpr(Ops, SCEV::FlagNUW, Depth + 1);
1654 }
1655
1656 // zext(2^K * (trunc X to iN)) to iM ->
1657 // 2^K * (zext(trunc X to i{N-K}) to iM)<nuw>
1658 //
1659 // Proof:
1660 //
1661 // zext(2^K * (trunc X to iN)) to iM
1662 // = zext((trunc X to iN) << K) to iM
1663 // = zext((trunc X to i{N-K}) << K)<nuw> to iM
1664 // (because shl removes the top K bits)
1665 // = zext((2^K * (trunc X to i{N-K}))<nuw>) to iM
1666 // = (2^K * (zext(trunc X to i{N-K}) to iM))<nuw>.
1667 //
1668 if (SM->getNumOperands() == 2)
1669 if (auto *MulLHS = dyn_cast<SCEVConstant>(SM->getOperand(0)))
1670 if (MulLHS->getAPInt().isPowerOf2())
1671 if (auto *TruncRHS = dyn_cast<SCEVTruncateExpr>(SM->getOperand(1))) {
1672 int NewTruncBits = getTypeSizeInBits(TruncRHS->getType()) -
1673 MulLHS->getAPInt().logBase2();
1674 Type *NewTruncTy = IntegerType::get(getContext(), NewTruncBits);
1675 return getMulExpr(
1676 getZeroExtendExpr(MulLHS, Ty),
1677 getZeroExtendExpr(
1678 getTruncateExpr(TruncRHS->getOperand(), NewTruncTy), Ty),
1679 SCEV::FlagNUW, Depth + 1);
1680 }
1681 }
1682
1683 // The cast wasn't folded; create an explicit cast node.
1684 // Recompute the insert position, as it may have been invalidated.
1685 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1686 SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
1687 Op, Ty);
1688 UniqueSCEVs.InsertNode(S, IP);
1689 addToLoopUseLists(S);
1690 return S;
1691}
1692
1693const SCEV *
1694ScalarEvolution::getSignExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) {
1695 assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(
Ty) && "This is not an extending conversion!") ? static_cast
<void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1696, __PRETTY_FUNCTION__))
1696 "This is not an extending conversion!")((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(
Ty) && "This is not an extending conversion!") ? static_cast
<void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1696, __PRETTY_FUNCTION__))
;
1697 assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1698, __PRETTY_FUNCTION__))
1698 "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1698, __PRETTY_FUNCTION__))
;
1699 Ty = getEffectiveSCEVType(Ty);
1700
1701 // Fold if the operand is constant.
1702 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1703 return getConstant(
1704 cast<ConstantInt>(ConstantExpr::getSExt(SC->getValue(), Ty)));
1705
1706 // sext(sext(x)) --> sext(x)
1707 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1708 return getSignExtendExpr(SS->getOperand(), Ty, Depth + 1);
1709
1710 // sext(zext(x)) --> zext(x)
1711 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1712 return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1);
1713
1714 // Before doing any expensive analysis, check to see if we've already
1715 // computed a SCEV for this Op and Ty.
1716 FoldingSetNodeID ID;
1717 ID.AddInteger(scSignExtend);
1718 ID.AddPointer(Op);
1719 ID.AddPointer(Ty);
1720 void *IP = nullptr;
1721 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1722 // Limit recursion depth.
1723 if (Depth > MaxCastDepth) {
1724 SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
1725 Op, Ty);
1726 UniqueSCEVs.InsertNode(S, IP);
1727 addToLoopUseLists(S);
1728 return S;
1729 }
1730
1731 // sext(trunc(x)) --> sext(x) or x or trunc(x)
1732 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1733 // It's possible the bits taken off by the truncate were all sign bits. If
1734 // so, we should be able to simplify this further.
1735 const SCEV *X = ST->getOperand();
1736 ConstantRange CR = getSignedRange(X);
1737 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1738 unsigned NewBits = getTypeSizeInBits(Ty);
1739 if (CR.truncate(TruncBits).signExtend(NewBits).contains(
1740 CR.sextOrTrunc(NewBits)))
1741 return getTruncateOrSignExtend(X, Ty, Depth);
1742 }
1743
1744 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1745 // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw>
1746 if (SA->hasNoSignedWrap()) {
1747 // If the addition does not sign overflow then we can, by definition,
1748 // commute the sign extension with the addition operation.
1749 SmallVector<const SCEV *, 4> Ops;
1750 for (const auto *Op : SA->operands())
1751 Ops.push_back(getSignExtendExpr(Op, Ty, Depth + 1));
1752 return getAddExpr(Ops, SCEV::FlagNSW, Depth + 1);
1753 }
1754
1755 // sext(C + x + y + ...) --> (sext(D) + sext((C - D) + x + y + ...))
1756 // if D + (C - D + x + y + ...) could be proven to not signed wrap
1757 // where D maximizes the number of trailing zeros of (C - D + x + y + ...)
1758 //
1759 // For instance, this will bring two seemingly different expressions:
1760 // 1 + sext(5 + 20 * %x + 24 * %y) and
1761 // sext(6 + 20 * %x + 24 * %y)
1762 // to the same form:
1763 // 2 + sext(4 + 20 * %x + 24 * %y)
1764 if (const auto *SC = dyn_cast<SCEVConstant>(SA->getOperand(0))) {
1765 const APInt &D = extractConstantWithoutWrapping(*this, SC, SA);
1766 if (D != 0) {
1767 const SCEV *SSExtD = getSignExtendExpr(getConstant(D), Ty, Depth);
1768 const SCEV *SResidual =
1769 getAddExpr(getConstant(-D), SA, SCEV::FlagAnyWrap, Depth);
1770 const SCEV *SSExtR = getSignExtendExpr(SResidual, Ty, Depth + 1);
1771 return getAddExpr(SSExtD, SSExtR,
1772 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
1773 Depth + 1);
1774 }
1775 }
1776 }
1777 // If the input value is a chrec scev, and we can prove that the value
1778 // did not overflow the old, smaller, value, we can sign extend all of the
1779 // operands (often constants). This allows analysis of something like
1780 // this: for (signed char X = 0; X < 100; ++X) { int Y = X; }
1781 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
1782 if (AR->isAffine()) {
1783 const SCEV *Start = AR->getStart();
1784 const SCEV *Step = AR->getStepRecurrence(*this);
1785 unsigned BitWidth = getTypeSizeInBits(AR->getType());
1786 const Loop *L = AR->getLoop();
1787
1788 if (!AR->hasNoSignedWrap()) {
1789 auto NewFlags = proveNoWrapViaConstantRanges(AR);
1790 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags);
1791 }
1792
1793 // If we have special knowledge that this addrec won't overflow,
1794 // we don't need to do any further analysis.
1795 if (AR->hasNoSignedWrap())
1796 return getAddRecExpr(
1797 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
1798 getSignExtendExpr(Step, Ty, Depth + 1), L, SCEV::FlagNSW);
1799
1800 // Check whether the backedge-taken count is SCEVCouldNotCompute.
1801 // Note that this serves two purposes: It filters out loops that are
1802 // simply not analyzable, and it covers the case where this code is
1803 // being called from within backedge-taken count analysis, such that
1804 // attempting to ask for the backedge-taken count would likely result
1805 // in infinite recursion. In the later case, the analysis code will
1806 // cope with a conservative value, and it will take care to purge
1807 // that value once it has finished.
1808 const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(L);
1809 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
1810 // Manually compute the final value for AR, checking for
1811 // overflow.
1812
1813 // Check whether the backedge-taken count can be losslessly casted to
1814 // the addrec's type. The count is always unsigned.
1815 const SCEV *CastedMaxBECount =
1816 getTruncateOrZeroExtend(MaxBECount, Start->getType(), Depth);
1817 const SCEV *RecastedMaxBECount = getTruncateOrZeroExtend(
1818 CastedMaxBECount, MaxBECount->getType(), Depth);
1819 if (MaxBECount == RecastedMaxBECount) {
1820 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
1821 // Check whether Start+Step*MaxBECount has no signed overflow.
1822 const SCEV *SMul = getMulExpr(CastedMaxBECount, Step,
1823 SCEV::FlagAnyWrap, Depth + 1);
1824 const SCEV *SAdd = getSignExtendExpr(getAddExpr(Start, SMul,
1825 SCEV::FlagAnyWrap,
1826 Depth + 1),
1827 WideTy, Depth + 1);
1828 const SCEV *WideStart = getSignExtendExpr(Start, WideTy, Depth + 1);
1829 const SCEV *WideMaxBECount =
1830 getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1);
1831 const SCEV *OperandExtendedAdd =
1832 getAddExpr(WideStart,
1833 getMulExpr(WideMaxBECount,
1834 getSignExtendExpr(Step, WideTy, Depth + 1),
1835 SCEV::FlagAnyWrap, Depth + 1),
1836 SCEV::FlagAnyWrap, Depth + 1);
1837 if (SAdd == OperandExtendedAdd) {
1838 // Cache knowledge of AR NSW, which is propagated to this AddRec.
1839 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
1840 // Return the expression with the addrec on the outside.
1841 return getAddRecExpr(
1842 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this,
1843 Depth + 1),
1844 getSignExtendExpr(Step, Ty, Depth + 1), L,
1845 AR->getNoWrapFlags());
1846 }
1847 // Similar to above, only this time treat the step value as unsigned.
1848 // This covers loops that count up with an unsigned step.
1849 OperandExtendedAdd =
1850 getAddExpr(WideStart,
1851 getMulExpr(WideMaxBECount,
1852 getZeroExtendExpr(Step, WideTy, Depth + 1),
1853 SCEV::FlagAnyWrap, Depth + 1),
1854 SCEV::FlagAnyWrap, Depth + 1);
1855 if (SAdd == OperandExtendedAdd) {
1856 // If AR wraps around then
1857 //
1858 // abs(Step) * MaxBECount > unsigned-max(AR->getType())
1859 // => SAdd != OperandExtendedAdd
1860 //
1861 // Thus (AR is not NW => SAdd != OperandExtendedAdd) <=>
1862 // (SAdd == OperandExtendedAdd => AR is NW)
1863
1864 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1865
1866 // Return the expression with the addrec on the outside.
1867 return getAddRecExpr(
1868 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this,
1869 Depth + 1),
1870 getZeroExtendExpr(Step, Ty, Depth + 1), L,
1871 AR->getNoWrapFlags());
1872 }
1873 }
1874 }
1875
1876 // Normally, in the cases we can prove no-overflow via a
1877 // backedge guarding condition, we can also compute a backedge
1878 // taken count for the loop. The exceptions are assumptions and
1879 // guards present in the loop -- SCEV is not great at exploiting
1880 // these to compute max backedge taken counts, but can still use
1881 // these to prove lack of overflow. Use this fact to avoid
1882 // doing extra work that may not pay off.
1883
1884 if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards ||
1885 !AC.assumptions().empty()) {
1886 // If the backedge is guarded by a comparison with the pre-inc
1887 // value the addrec is safe. Also, if the entry is guarded by
1888 // a comparison with the start value and the backedge is
1889 // guarded by a comparison with the post-inc value, the addrec
1890 // is safe.
1891 ICmpInst::Predicate Pred;
1892 const SCEV *OverflowLimit =
1893 getSignedOverflowLimitForStep(Step, &Pred, this);
1894 if (OverflowLimit &&
1895 (isLoopBackedgeGuardedByCond(L, Pred, AR, OverflowLimit) ||
1896 isKnownOnEveryIteration(Pred, AR, OverflowLimit))) {
1897 // Cache knowledge of AR NSW, then propagate NSW to the wide AddRec.
1898 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
1899 return getAddRecExpr(
1900 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
1901 getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
1902 }
1903 }
1904
1905 // sext({C,+,Step}) --> (sext(D) + sext({C-D,+,Step}))<nuw><nsw>
1906 // if D + (C - D + Step * n) could be proven to not signed wrap
1907 // where D maximizes the number of trailing zeros of (C - D + Step * n)
1908 if (const auto *SC = dyn_cast<SCEVConstant>(Start)) {
1909 const APInt &C = SC->getAPInt();
1910 const APInt &D = extractConstantWithoutWrapping(*this, C, Step);
1911 if (D != 0) {
1912 const SCEV *SSExtD = getSignExtendExpr(getConstant(D), Ty, Depth);
1913 const SCEV *SResidual =
1914 getAddRecExpr(getConstant(C - D), Step, L, AR->getNoWrapFlags());
1915 const SCEV *SSExtR = getSignExtendExpr(SResidual, Ty, Depth + 1);
1916 return getAddExpr(SSExtD, SSExtR,
1917 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
1918 Depth + 1);
1919 }
1920 }
1921
1922 if (proveNoWrapByVaryingStart<SCEVSignExtendExpr>(Start, Step, L)) {
1923 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
1924 return getAddRecExpr(
1925 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
1926 getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
1927 }
1928 }
1929
1930 // If the input value is provably positive and we could not simplify
1931 // away the sext build a zext instead.
1932 if (isKnownNonNegative(Op))
1933 return getZeroExtendExpr(Op, Ty, Depth + 1);
1934
1935 // The cast wasn't folded; create an explicit cast node.
1936 // Recompute the insert position, as it may have been invalidated.
1937 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1938 SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
1939 Op, Ty);
1940 UniqueSCEVs.InsertNode(S, IP);
1941 addToLoopUseLists(S);
1942 return S;
1943}
1944
1945/// getAnyExtendExpr - Return a SCEV for the given operand extended with
1946/// unspecified bits out to the given type.
1947const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op,
1948 Type *Ty) {
1949 assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(
Ty) && "This is not an extending conversion!") ? static_cast
<void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1950, __PRETTY_FUNCTION__))
1950 "This is not an extending conversion!")((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(
Ty) && "This is not an extending conversion!") ? static_cast
<void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1950, __PRETTY_FUNCTION__))
;
1951 assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1952, __PRETTY_FUNCTION__))
1952 "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1952, __PRETTY_FUNCTION__))
;
1953 Ty = getEffectiveSCEVType(Ty);
1954
1955 // Sign-extend negative constants.
1956 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1957 if (SC->getAPInt().isNegative())
1958 return getSignExtendExpr(Op, Ty);
1959
1960 // Peel off a truncate cast.
1961 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Op)) {
1962 const SCEV *NewOp = T->getOperand();
1963 if (getTypeSizeInBits(NewOp->getType()) < getTypeSizeInBits(Ty))
1964 return getAnyExtendExpr(NewOp, Ty);
1965 return getTruncateOrNoop(NewOp, Ty);
1966 }
1967
1968 // Next try a zext cast. If the cast is folded, use it.
1969 const SCEV *ZExt = getZeroExtendExpr(Op, Ty);
1970 if (!isa<SCEVZeroExtendExpr>(ZExt))
1971 return ZExt;
1972
1973 // Next try a sext cast. If the cast is folded, use it.
1974 const SCEV *SExt = getSignExtendExpr(Op, Ty);
1975 if (!isa<SCEVSignExtendExpr>(SExt))
1976 return SExt;
1977
1978 // Force the cast to be folded into the operands of an addrec.
1979 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) {
1980 SmallVector<const SCEV *, 4> Ops;
1981 for (const SCEV *Op : AR->operands())
1982 Ops.push_back(getAnyExtendExpr(Op, Ty));
1983 return getAddRecExpr(Ops, AR->getLoop(), SCEV::FlagNW);
1984 }
1985
1986 // If the expression is obviously signed, use the sext cast value.
1987 if (isa<SCEVSMaxExpr>(Op))
1988 return SExt;
1989
1990 // Absent any other information, use the zext cast value.
1991 return ZExt;
1992}
1993
1994/// Process the given Ops list, which is a list of operands to be added under
1995/// the given scale, update the given map. This is a helper function for
1996/// getAddRecExpr. As an example of what it does, given a sequence of operands
1997/// that would form an add expression like this:
1998///
1999/// m + n + 13 + (A * (o + p + (B * (q + m + 29)))) + r + (-1 * r)
2000///
2001/// where A and B are constants, update the map with these values:
2002///
2003/// (m, 1+A*B), (n, 1), (o, A), (p, A), (q, A*B), (r, 0)
2004///
2005/// and add 13 + A*B*29 to AccumulatedConstant.
2006/// This will allow getAddRecExpr to produce this:
2007///
2008/// 13+A*B*29 + n + (m * (1+A*B)) + ((o + p) * A) + (q * A*B)
2009///
2010/// This form often exposes folding opportunities that are hidden in
2011/// the original operand list.
2012///
2013/// Return true iff it appears that any interesting folding opportunities
2014/// may be exposed. This helps getAddRecExpr short-circuit extra work in
2015/// the common case where no interesting opportunities are present, and
2016/// is also used as a check to avoid infinite recursion.
2017static bool
2018CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M,
2019 SmallVectorImpl<const SCEV *> &NewOps,
2020 APInt &AccumulatedConstant,
2021 const SCEV *const *Ops, size_t NumOperands,
2022 const APInt &Scale,
2023 ScalarEvolution &SE) {
2024 bool Interesting = false;
2025
2026 // Iterate over the add operands. They are sorted, with constants first.
2027 unsigned i = 0;
2028 while (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
2029 ++i;
2030 // Pull a buried constant out to the outside.
2031 if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero())
2032 Interesting = true;
2033 AccumulatedConstant += Scale * C->getAPInt();
2034 }
2035
2036 // Next comes everything else. We're especially interested in multiplies
2037 // here, but they're in the middle, so just visit the rest with one loop.
2038 for (; i != NumOperands; ++i) {
2039 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[i]);
2040 if (Mul && isa<SCEVConstant>(Mul->getOperand(0))) {
2041 APInt NewScale =
2042 Scale * cast<SCEVConstant>(Mul->getOperand(0))->getAPInt();
2043 if (Mul->getNumOperands() == 2 && isa<SCEVAddExpr>(Mul->getOperand(1))) {
2044 // A multiplication of a constant with another add; recurse.
2045 const SCEVAddExpr *Add = cast<SCEVAddExpr>(Mul->getOperand(1));
2046 Interesting |=
2047 CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
2048 Add->op_begin(), Add->getNumOperands(),
2049 NewScale, SE);
2050 } else {
2051 // A multiplication of a constant with some other value. Update
2052 // the map.
2053 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin()+1, Mul->op_end());
2054 const SCEV *Key = SE.getMulExpr(MulOps);
2055 auto Pair = M.insert({Key, NewScale});
2056 if (Pair.second) {
2057 NewOps.push_back(Pair.first->first);
2058 } else {
2059 Pair.first->second += NewScale;
2060 // The map already had an entry for this value, which may indicate
2061 // a folding opportunity.
2062 Interesting = true;
2063 }
2064 }
2065 } else {
2066 // An ordinary operand. Update the map.
2067 std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair =
2068 M.insert({Ops[i], Scale});
2069 if (Pair.second) {
2070 NewOps.push_back(Pair.first->first);
2071 } else {
2072 Pair.first->second += Scale;
2073 // The map already had an entry for this value, which may indicate
2074 // a folding opportunity.
2075 Interesting = true;
2076 }
2077 }
2078 }
2079
2080 return Interesting;
2081}
2082
2083// We're trying to construct a SCEV of type `Type' with `Ops' as operands and
2084// `OldFlags' as can't-wrap behavior. Infer a more aggressive set of
2085// can't-overflow flags for the operation if possible.
2086static SCEV::NoWrapFlags
2087StrengthenNoWrapFlags(ScalarEvolution *SE, SCEVTypes Type,
2088 const ArrayRef<const SCEV *> Ops,
2089 SCEV::NoWrapFlags Flags) {
2090 using namespace std::placeholders;
2091
2092 using OBO = OverflowingBinaryOperator;
2093
2094 bool CanAnalyze =
2095 Type == scAddExpr || Type == scAddRecExpr || Type == scMulExpr;
2096 (void)CanAnalyze;
2097 assert(CanAnalyze && "don't call from other places!")((CanAnalyze && "don't call from other places!") ? static_cast
<void> (0) : __assert_fail ("CanAnalyze && \"don't call from other places!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2097, __PRETTY_FUNCTION__))
;
2098
2099 int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW;
2100 SCEV::NoWrapFlags SignOrUnsignWrap =
2101 ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
2102
2103 // If FlagNSW is true and all the operands are non-negative, infer FlagNUW.
2104 auto IsKnownNonNegative = [&](const SCEV *S) {
2105 return SE->isKnownNonNegative(S);
2106 };
2107
2108 if (SignOrUnsignWrap == SCEV::FlagNSW && all_of(Ops, IsKnownNonNegative))
2109 Flags =
2110 ScalarEvolution::setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask);
2111
2112 SignOrUnsignWrap = ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
2113
2114 if (SignOrUnsignWrap != SignOrUnsignMask &&
2115 (Type == scAddExpr || Type == scMulExpr) && Ops.size() == 2 &&
2116 isa<SCEVConstant>(Ops[0])) {
2117
2118 auto Opcode = [&] {
2119 switch (Type) {
2120 case scAddExpr:
2121 return Instruction::Add;
2122 case scMulExpr:
2123 return Instruction::Mul;
2124 default:
2125 llvm_unreachable("Unexpected SCEV op.")::llvm::llvm_unreachable_internal("Unexpected SCEV op.", "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2125)
;
2126 }
2127 }();
2128
2129 const APInt &C = cast<SCEVConstant>(Ops[0])->getAPInt();
2130
2131 // (A <opcode> C) --> (A <opcode> C)<nsw> if the op doesn't sign overflow.
2132 if (!(SignOrUnsignWrap & SCEV::FlagNSW)) {
2133 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
2134 Opcode, C, OBO::NoSignedWrap);
2135 if (NSWRegion.contains(SE->getSignedRange(Ops[1])))
2136 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
2137 }
2138
2139 // (A <opcode> C) --> (A <opcode> C)<nuw> if the op doesn't unsign overflow.
2140 if (!(SignOrUnsignWrap & SCEV::FlagNUW)) {
2141 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
2142 Opcode, C, OBO::NoUnsignedWrap);
2143 if (NUWRegion.contains(SE->getUnsignedRange(Ops[1])))
2144 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
2145 }
2146 }
2147
2148 return Flags;
2149}
2150
2151bool ScalarEvolution::isAvailableAtLoopEntry(const SCEV *S, const Loop *L) {
2152 return isLoopInvariant(S, L) && properlyDominates(S, L->getHeader());
2153}
2154
2155/// Get a canonical add expression, or something simpler if possible.
2156const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
2157 SCEV::NoWrapFlags Flags,
2158 unsigned Depth) {
2159 assert(!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) &&((!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && "only nuw or nsw allowed"
) ? static_cast<void> (0) : __assert_fail ("!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && \"only nuw or nsw allowed\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2160, __PRETTY_FUNCTION__))
2160 "only nuw or nsw allowed")((!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && "only nuw or nsw allowed"
) ? static_cast<void> (0) : __assert_fail ("!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && \"only nuw or nsw allowed\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2160, __PRETTY_FUNCTION__))
;
2161 assert(!Ops.empty() && "Cannot get empty add!")((!Ops.empty() && "Cannot get empty add!") ? static_cast
<void> (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty add!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2161, __PRETTY_FUNCTION__))
;
2162 if (Ops.size() == 1) return Ops[0];
2163#ifndef NDEBUG
2164 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2165 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2166 assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&((getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
"SCEVAddExpr operand types don't match!") ? static_cast<void
> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVAddExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2167, __PRETTY_FUNCTION__))
2167 "SCEVAddExpr operand types don't match!")((getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
"SCEVAddExpr operand types don't match!") ? static_cast<void
> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVAddExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2167, __PRETTY_FUNCTION__))
;
2168#endif
2169
2170 // Sort by complexity, this groups all similar expression types together.
2171 GroupByComplexity(Ops, &LI, DT);
2172
2173 Flags = StrengthenNoWrapFlags(this, scAddExpr, Ops, Flags);
2174
2175 // If there are any constants, fold them together.
2176 unsigned Idx = 0;
2177 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2178 ++Idx;
2179 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2179, __PRETTY_FUNCTION__))
;
2180 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2181 // We found two constants, fold them together!
2182 Ops[0] = getConstant(LHSC->getAPInt() + RHSC->getAPInt());
2183 if (Ops.size() == 2) return Ops[0];
2184 Ops.erase(Ops.begin()+1); // Erase the folded element
2185 LHSC = cast<SCEVConstant>(Ops[0]);
2186 }
2187
2188 // If we are left with a constant zero being added, strip it off.
2189 if (LHSC->getValue()->isZero()) {
2190 Ops.erase(Ops.begin());
2191 --Idx;
2192 }
2193
2194 if (Ops.size() == 1) return Ops[0];
2195 }
2196
2197 // Limit recursion calls depth.
2198 if (Depth > MaxArithDepth || hasHugeExpression(Ops))
2199 return getOrCreateAddExpr(Ops, Flags);
2200
2201 if (SCEV *S = std::get<0>(findExistingSCEVInCache(scAddExpr, Ops))) {
2202 static_cast<SCEVAddExpr *>(S)->setNoWrapFlags(Flags);
2203 return S;
2204 }
2205
2206 // Okay, check to see if the same value occurs in the operand list more than
2207 // once. If so, merge them together into an multiply expression. Since we
2208 // sorted the list, these values are required to be adjacent.
2209 Type *Ty = Ops[0]->getType();
2210 bool FoundMatch = false;
2211 for (unsigned i = 0, e = Ops.size(); i != e-1; ++i)
2212 if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2
2213 // Scan ahead to count how many equal operands there are.
2214 unsigned Count = 2;
2215 while (i+Count != e && Ops[i+Count] == Ops[i])
2216 ++Count;
2217 // Merge the values into a multiply.
2218 const SCEV *Scale = getConstant(Ty, Count);
2219 const SCEV *Mul = getMulExpr(Scale, Ops[i], SCEV::FlagAnyWrap, Depth + 1);
2220 if (Ops.size() == Count)
2221 return Mul;
2222 Ops[i] = Mul;
2223 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+Count);
2224 --i; e -= Count - 1;
2225 FoundMatch = true;
2226 }
2227 if (FoundMatch)
2228 return getAddExpr(Ops, Flags, Depth + 1);
2229
2230 // Check for truncates. If all the operands are truncated from the same
2231 // type, see if factoring out the truncate would permit the result to be
2232 // folded. eg., n*trunc(x) + m*trunc(y) --> trunc(trunc(m)*x + trunc(n)*y)
2233 // if the contents of the resulting outer trunc fold to something simple.
2234 auto FindTruncSrcType = [&]() -> Type * {
2235 // We're ultimately looking to fold an addrec of truncs and muls of only
2236 // constants and truncs, so if we find any other types of SCEV
2237 // as operands of the addrec then we bail and return nullptr here.
2238 // Otherwise, we return the type of the operand of a trunc that we find.
2239 if (auto *T = dyn_cast<SCEVTruncateExpr>(Ops[Idx]))
2240 return T->getOperand()->getType();
2241 if (const auto *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
2242 const auto *LastOp = Mul->getOperand(Mul->getNumOperands() - 1);
2243 if (const auto *T = dyn_cast<SCEVTruncateExpr>(LastOp))
2244 return T->getOperand()->getType();
2245 }
2246 return nullptr;
2247 };
2248 if (auto *SrcType = FindTruncSrcType()) {
2249 SmallVector<const SCEV *, 8> LargeOps;
2250 bool Ok = true;
2251 // Check all the operands to see if they can be represented in the
2252 // source type of the truncate.
2253 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
2254 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Ops[i])) {
2255 if (T->getOperand()->getType() != SrcType) {
2256 Ok = false;
2257 break;
2258 }
2259 LargeOps.push_back(T->getOperand());
2260 } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
2261 LargeOps.push_back(getAnyExtendExpr(C, SrcType));
2262 } else if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Ops[i])) {
2263 SmallVector<const SCEV *, 8> LargeMulOps;
2264 for (unsigned j = 0, f = M->getNumOperands(); j != f && Ok; ++j) {
2265 if (const SCEVTruncateExpr *T =
2266 dyn_cast<SCEVTruncateExpr>(M->getOperand(j))) {
2267 if (T->getOperand()->getType() != SrcType) {
2268 Ok = false;
2269 break;
2270 }
2271 LargeMulOps.push_back(T->getOperand());
2272 } else if (const auto *C = dyn_cast<SCEVConstant>(M->getOperand(j))) {
2273 LargeMulOps.push_back(getAnyExtendExpr(C, SrcType));
2274 } else {
2275 Ok = false;
2276 break;
2277 }
2278 }
2279 if (Ok)
2280 LargeOps.push_back(getMulExpr(LargeMulOps, SCEV::FlagAnyWrap, Depth + 1));
2281 } else {
2282 Ok = false;
2283 break;
2284 }
2285 }
2286 if (Ok) {
2287 // Evaluate the expression in the larger type.
2288 const SCEV *Fold = getAddExpr(LargeOps, SCEV::FlagAnyWrap, Depth + 1);
2289 // If it folds to something simple, use it. Otherwise, don't.
2290 if (isa<SCEVConstant>(Fold) || isa<SCEVUnknown>(Fold))
2291 return getTruncateExpr(Fold, Ty);
2292 }
2293 }
2294
2295 // Skip past any other cast SCEVs.
2296 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddExpr)
2297 ++Idx;
2298
2299 // If there are add operands they would be next.
2300 if (Idx < Ops.size()) {
2301 bool DeletedAdd = false;
2302 while (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[Idx])) {
2303 if (Ops.size() > AddOpsInlineThreshold ||
2304 Add->getNumOperands() > AddOpsInlineThreshold)
2305 break;
2306 // If we have an add, expand the add operands onto the end of the operands
2307 // list.
2308 Ops.erase(Ops.begin()+Idx);
2309 Ops.append(Add->op_begin(), Add->op_end());
2310 DeletedAdd = true;
2311 }
2312
2313 // If we deleted at least one add, we added operands to the end of the list,
2314 // and they are not necessarily sorted. Recurse to resort and resimplify
2315 // any operands we just acquired.
2316 if (DeletedAdd)
2317 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2318 }
2319
2320 // Skip over the add expression until we get to a multiply.
2321 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
2322 ++Idx;
2323
2324 // Check to see if there are any folding opportunities present with
2325 // operands multiplied by constant values.
2326 if (Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx])) {
2327 uint64_t BitWidth = getTypeSizeInBits(Ty);
2328 DenseMap<const SCEV *, APInt> M;
2329 SmallVector<const SCEV *, 8> NewOps;
2330 APInt AccumulatedConstant(BitWidth, 0);
2331 if (CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
2332 Ops.data(), Ops.size(),
2333 APInt(BitWidth, 1), *this)) {
2334 struct APIntCompare {
2335 bool operator()(const APInt &LHS, const APInt &RHS) const {
2336 return LHS.ult(RHS);
2337 }
2338 };
2339
2340 // Some interesting folding opportunity is present, so its worthwhile to
2341 // re-generate the operands list. Group the operands by constant scale,
2342 // to avoid multiplying by the same constant scale multiple times.
2343 std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare> MulOpLists;
2344 for (const SCEV *NewOp : NewOps)
2345 MulOpLists[M.find(NewOp)->second].push_back(NewOp);
2346 // Re-generate the operands list.
2347 Ops.clear();
2348 if (AccumulatedConstant != 0)
2349 Ops.push_back(getConstant(AccumulatedConstant));
2350 for (auto &MulOp : MulOpLists)
2351 if (MulOp.first != 0)
2352 Ops.push_back(getMulExpr(
2353 getConstant(MulOp.first),
2354 getAddExpr(MulOp.second, SCEV::FlagAnyWrap, Depth + 1),
2355 SCEV::FlagAnyWrap, Depth + 1));
2356 if (Ops.empty())
2357 return getZero(Ty);
2358 if (Ops.size() == 1)
2359 return Ops[0];
2360 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2361 }
2362 }
2363
2364 // If we are adding something to a multiply expression, make sure the
2365 // something is not already an operand of the multiply. If so, merge it into
2366 // the multiply.
2367 for (; Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx]); ++Idx) {
2368 const SCEVMulExpr *Mul = cast<SCEVMulExpr>(Ops[Idx]);
2369 for (unsigned MulOp = 0, e = Mul->getNumOperands(); MulOp != e; ++MulOp) {
2370 const SCEV *MulOpSCEV = Mul->getOperand(MulOp);
2371 if (isa<SCEVConstant>(MulOpSCEV))
2372 continue;
2373 for (unsigned AddOp = 0, e = Ops.size(); AddOp != e; ++AddOp)
2374 if (MulOpSCEV == Ops[AddOp]) {
2375 // Fold W + X + (X * Y * Z) --> W + (X * ((Y*Z)+1))
2376 const SCEV *InnerMul = Mul->getOperand(MulOp == 0);
2377 if (Mul->getNumOperands() != 2) {
2378 // If the multiply has more than two operands, we must get the
2379 // Y*Z term.
2380 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2381 Mul->op_begin()+MulOp);
2382 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2383 InnerMul = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2384 }
2385 SmallVector<const SCEV *, 2> TwoOps = {getOne(Ty), InnerMul};
2386 const SCEV *AddOne = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2387 const SCEV *OuterMul = getMulExpr(AddOne, MulOpSCEV,
2388 SCEV::FlagAnyWrap, Depth + 1);
2389 if (Ops.size() == 2) return OuterMul;
2390 if (AddOp < Idx) {
2391 Ops.erase(Ops.begin()+AddOp);
2392 Ops.erase(Ops.begin()+Idx-1);
2393 } else {
2394 Ops.erase(Ops.begin()+Idx);
2395 Ops.erase(Ops.begin()+AddOp-1);
2396 }
2397 Ops.push_back(OuterMul);
2398 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2399 }
2400
2401 // Check this multiply against other multiplies being added together.
2402 for (unsigned OtherMulIdx = Idx+1;
2403 OtherMulIdx < Ops.size() && isa<SCEVMulExpr>(Ops[OtherMulIdx]);
2404 ++OtherMulIdx) {
2405 const SCEVMulExpr *OtherMul = cast<SCEVMulExpr>(Ops[OtherMulIdx]);
2406 // If MulOp occurs in OtherMul, we can fold the two multiplies
2407 // together.
2408 for (unsigned OMulOp = 0, e = OtherMul->getNumOperands();
2409 OMulOp != e; ++OMulOp)
2410 if (OtherMul->getOperand(OMulOp) == MulOpSCEV) {
2411 // Fold X + (A*B*C) + (A*D*E) --> X + (A*(B*C+D*E))
2412 const SCEV *InnerMul1 = Mul->getOperand(MulOp == 0);
2413 if (Mul->getNumOperands() != 2) {
2414 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2415 Mul->op_begin()+MulOp);
2416 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2417 InnerMul1 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2418 }
2419 const SCEV *InnerMul2 = OtherMul->getOperand(OMulOp == 0);
2420 if (OtherMul->getNumOperands() != 2) {
2421 SmallVector<const SCEV *, 4> MulOps(OtherMul->op_begin(),
2422 OtherMul->op_begin()+OMulOp);
2423 MulOps.append(OtherMul->op_begin()+OMulOp+1, OtherMul->op_end());
2424 InnerMul2 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2425 }
2426 SmallVector<const SCEV *, 2> TwoOps = {InnerMul1, InnerMul2};
2427 const SCEV *InnerMulSum =
2428 getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2429 const SCEV *OuterMul = getMulExpr(MulOpSCEV, InnerMulSum,
2430 SCEV::FlagAnyWrap, Depth + 1);
2431 if (Ops.size() == 2) return OuterMul;
2432 Ops.erase(Ops.begin()+Idx);
2433 Ops.erase(Ops.begin()+OtherMulIdx-1);
2434 Ops.push_back(OuterMul);
2435 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2436 }
2437 }
2438 }
2439 }
2440
2441 // If there are any add recurrences in the operands list, see if any other
2442 // added values are loop invariant. If so, we can fold them into the
2443 // recurrence.
2444 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
2445 ++Idx;
2446
2447 // Scan over all recurrences, trying to fold loop invariants into them.
2448 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
2449 // Scan all of the other operands to this add and add them to the vector if
2450 // they are loop invariant w.r.t. the recurrence.
2451 SmallVector<const SCEV *, 8> LIOps;
2452 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
2453 const Loop *AddRecLoop = AddRec->getLoop();
2454 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2455 if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) {
2456 LIOps.push_back(Ops[i]);
2457 Ops.erase(Ops.begin()+i);
2458 --i; --e;
2459 }
2460
2461 // If we found some loop invariants, fold them into the recurrence.
2462 if (!LIOps.empty()) {
2463 // NLI + LI + {Start,+,Step} --> NLI + {LI+Start,+,Step}
2464 LIOps.push_back(AddRec->getStart());
2465
2466 SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(),
2467 AddRec->op_end());
2468 // This follows from the fact that the no-wrap flags on the outer add
2469 // expression are applicable on the 0th iteration, when the add recurrence
2470 // will be equal to its start value.
2471 AddRecOps[0] = getAddExpr(LIOps, Flags, Depth + 1);
2472
2473 // Build the new addrec. Propagate the NUW and NSW flags if both the
2474 // outer add and the inner addrec are guaranteed to have no overflow.
2475 // Always propagate NW.
2476 Flags = AddRec->getNoWrapFlags(setFlags(Flags, SCEV::FlagNW));
2477 const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop, Flags);
2478
2479 // If all of the other operands were loop invariant, we are done.
2480 if (Ops.size() == 1) return NewRec;
2481
2482 // Otherwise, add the folded AddRec by the non-invariant parts.
2483 for (unsigned i = 0;; ++i)
2484 if (Ops[i] == AddRec) {
2485 Ops[i] = NewRec;
2486 break;
2487 }
2488 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2489 }
2490
2491 // Okay, if there weren't any loop invariants to be folded, check to see if
2492 // there are multiple AddRec's with the same loop induction variable being
2493 // added together. If so, we can fold them.
2494 for (unsigned OtherIdx = Idx+1;
2495 OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2496 ++OtherIdx) {
2497 // We expect the AddRecExpr's to be sorted in reverse dominance order,
2498 // so that the 1st found AddRecExpr is dominated by all others.
2499 assert(DT.dominates(((DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->
getLoop()->getHeader(), AddRec->getLoop()->getHeader
()) && "AddRecExprs are not sorted in reverse dominance order?"
) ? static_cast<void> (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2502, __PRETTY_FUNCTION__))
2500 cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(),((DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->
getLoop()->getHeader(), AddRec->getLoop()->getHeader
()) && "AddRecExprs are not sorted in reverse dominance order?"
) ? static_cast<void> (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2502, __PRETTY_FUNCTION__))
2501 AddRec->getLoop()->getHeader()) &&((DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->
getLoop()->getHeader(), AddRec->getLoop()->getHeader
()) && "AddRecExprs are not sorted in reverse dominance order?"
) ? static_cast<void> (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2502, __PRETTY_FUNCTION__))
2502 "AddRecExprs are not sorted in reverse dominance order?")((DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->
getLoop()->getHeader(), AddRec->getLoop()->getHeader
()) && "AddRecExprs are not sorted in reverse dominance order?"
) ? static_cast<void> (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2502, __PRETTY_FUNCTION__))
;
2503 if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) {
2504 // Other + {A,+,B}<L> + {C,+,D}<L> --> Other + {A+C,+,B+D}<L>
2505 SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(),
2506 AddRec->op_end());
2507 for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2508 ++OtherIdx) {
2509 const auto *OtherAddRec = cast<SCEVAddRecExpr>(Ops[OtherIdx]);
2510 if (OtherAddRec->getLoop() == AddRecLoop) {
2511 for (unsigned i = 0, e = OtherAddRec->getNumOperands();
2512 i != e; ++i) {
2513 if (i >= AddRecOps.size()) {
2514 AddRecOps.append(OtherAddRec->op_begin()+i,
2515 OtherAddRec->op_end());
2516 break;
2517 }
2518 SmallVector<const SCEV *, 2> TwoOps = {
2519 AddRecOps[i], OtherAddRec->getOperand(i)};
2520 AddRecOps[i] = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2521 }
2522 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
2523 }
2524 }
2525 // Step size has changed, so we cannot guarantee no self-wraparound.
2526 Ops[Idx] = getAddRecExpr(AddRecOps, AddRecLoop, SCEV::FlagAnyWrap);
2527 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2528 }
2529 }
2530
2531 // Otherwise couldn't fold anything into this recurrence. Move onto the
2532 // next one.
2533 }
2534
2535 // Okay, it looks like we really DO need an add expr. Check to see if we
2536 // already have one, otherwise create a new one.
2537 return getOrCreateAddExpr(Ops, Flags);
2538}
2539
2540const SCEV *
2541ScalarEvolution::getOrCreateAddExpr(ArrayRef<const SCEV *> Ops,
2542 SCEV::NoWrapFlags Flags) {
2543 FoldingSetNodeID ID;
2544 ID.AddInteger(scAddExpr);
2545 for (const SCEV *Op : Ops)
2546 ID.AddPointer(Op);
2547 void *IP = nullptr;
2548 SCEVAddExpr *S =
2549 static_cast<SCEVAddExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2550 if (!S) {
2551 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2552 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2553 S = new (SCEVAllocator)
2554 SCEVAddExpr(ID.Intern(SCEVAllocator), O, Ops.size());
2555 UniqueSCEVs.InsertNode(S, IP);
2556 addToLoopUseLists(S);
2557 }
2558 S->setNoWrapFlags(Flags);
2559 return S;
2560}
2561
2562const SCEV *
2563ScalarEvolution::getOrCreateAddRecExpr(ArrayRef<const SCEV *> Ops,
2564 const Loop *L, SCEV::NoWrapFlags Flags) {
2565 FoldingSetNodeID ID;
2566 ID.AddInteger(scAddRecExpr);
2567 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2568 ID.AddPointer(Ops[i]);
2569 ID.AddPointer(L);
2570 void *IP = nullptr;
2571 SCEVAddRecExpr *S =
2572 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2573 if (!S) {
2574 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2575 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2576 S = new (SCEVAllocator)
2577 SCEVAddRecExpr(ID.Intern(SCEVAllocator), O, Ops.size(), L);
2578 UniqueSCEVs.InsertNode(S, IP);
2579 addToLoopUseLists(S);
2580 }
2581 S->setNoWrapFlags(Flags);
2582 return S;
2583}
2584
2585const SCEV *
2586ScalarEvolution::getOrCreateMulExpr(ArrayRef<const SCEV *> Ops,
2587 SCEV::NoWrapFlags Flags) {
2588 FoldingSetNodeID ID;
2589 ID.AddInteger(scMulExpr);
2590 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2591 ID.AddPointer(Ops[i]);
2592 void *IP = nullptr;
2593 SCEVMulExpr *S =
2594 static_cast<SCEVMulExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2595 if (!S) {
2596 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2597 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2598 S = new (SCEVAllocator) SCEVMulExpr(ID.Intern(SCEVAllocator),
2599 O, Ops.size());
2600 UniqueSCEVs.InsertNode(S, IP);
2601 addToLoopUseLists(S);
2602 }
2603 S->setNoWrapFlags(Flags);
2604 return S;
2605}
2606
2607static uint64_t umul_ov(uint64_t i, uint64_t j, bool &Overflow) {
2608 uint64_t k = i*j;
2609 if (j > 1 && k / j != i) Overflow = true;
2610 return k;
2611}
2612
2613/// Compute the result of "n choose k", the binomial coefficient. If an
2614/// intermediate computation overflows, Overflow will be set and the return will
2615/// be garbage. Overflow is not cleared on absence of overflow.
2616static uint64_t Choose(uint64_t n, uint64_t k, bool &Overflow) {
2617 // We use the multiplicative formula:
2618 // n(n-1)(n-2)...(n-(k-1)) / k(k-1)(k-2)...1 .
2619 // At each iteration, we take the n-th term of the numeral and divide by the
2620 // (k-n)th term of the denominator. This division will always produce an
2621 // integral result, and helps reduce the chance of overflow in the
2622 // intermediate computations. However, we can still overflow even when the
2623 // final result would fit.
2624
2625 if (n == 0 || n == k) return 1;
2626 if (k > n) return 0;
2627
2628 if (k > n/2)
2629 k = n-k;
2630
2631 uint64_t r = 1;
2632 for (uint64_t i = 1; i <= k; ++i) {
2633 r = umul_ov(r, n-(i-1), Overflow);
2634 r /= i;
2635 }
2636 return r;
2637}
2638
2639/// Determine if any of the operands in this SCEV are a constant or if
2640/// any of the add or multiply expressions in this SCEV contain a constant.
2641static bool containsConstantInAddMulChain(const SCEV *StartExpr) {
2642 struct FindConstantInAddMulChain {
2643 bool FoundConstant = false;
2644
2645 bool follow(const SCEV *S) {
2646 FoundConstant |= isa<SCEVConstant>(S);
2647 return isa<SCEVAddExpr>(S) || isa<SCEVMulExpr>(S);
2648 }
2649
2650 bool isDone() const {
2651 return FoundConstant;
2652 }
2653 };
2654
2655 FindConstantInAddMulChain F;
2656 SCEVTraversal<FindConstantInAddMulChain> ST(F);
2657 ST.visitAll(StartExpr);
2658 return F.FoundConstant;
2659}
2660
2661/// Get a canonical multiply expression, or something simpler if possible.
2662const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
2663 SCEV::NoWrapFlags Flags,
2664 unsigned Depth) {
2665 assert(Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) &&((Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) &&
"only nuw or nsw allowed") ? static_cast<void> (0) : __assert_fail
("Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) && \"only nuw or nsw allowed\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2666, __PRETTY_FUNCTION__))
2666 "only nuw or nsw allowed")((Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) &&
"only nuw or nsw allowed") ? static_cast<void> (0) : __assert_fail
("Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) && \"only nuw or nsw allowed\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2666, __PRETTY_FUNCTION__))
;
2667 assert(!Ops.empty() && "Cannot get empty mul!")((!Ops.empty() && "Cannot get empty mul!") ? static_cast
<void> (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty mul!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2667, __PRETTY_FUNCTION__))
;
2668 if (Ops.size() == 1) return Ops[0];
2669#ifndef NDEBUG
2670 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2671 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2672 assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&((getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
"SCEVMulExpr operand types don't match!") ? static_cast<void
> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVMulExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2673, __PRETTY_FUNCTION__))
2673 "SCEVMulExpr operand types don't match!")((getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
"SCEVMulExpr operand types don't match!") ? static_cast<void
> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVMulExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2673, __PRETTY_FUNCTION__))
;
2674#endif
2675
2676 // Sort by complexity, this groups all similar expression types together.
2677 GroupByComplexity(Ops, &LI, DT);
2678
2679 Flags = StrengthenNoWrapFlags(this, scMulExpr, Ops, Flags);
2680
2681 // Limit recursion calls depth, but fold all-constant expressions.
2682 // `Ops` is sorted, so it's enough to check just last one.
2683 if ((Depth > MaxArithDepth || hasHugeExpression(Ops)) &&
2684 !isa<SCEVConstant>(Ops.back()))
2685 return getOrCreateMulExpr(Ops, Flags);
2686
2687 if (SCEV *S = std::get<0>(findExistingSCEVInCache(scMulExpr, Ops))) {
2688 static_cast<SCEVMulExpr *>(S)->setNoWrapFlags(Flags);
2689 return S;
2690 }
2691
2692 // If there are any constants, fold them together.
2693 unsigned Idx = 0;
2694 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2695
2696 if (Ops.size() == 2)
2697 // C1*(C2+V) -> C1*C2 + C1*V
2698 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1]))
2699 // If any of Add's ops are Adds or Muls with a constant, apply this
2700 // transformation as well.
2701 //
2702 // TODO: There are some cases where this transformation is not
2703 // profitable; for example, Add = (C0 + X) * Y + Z. Maybe the scope of
2704 // this transformation should be narrowed down.
2705 if (Add->getNumOperands() == 2 && containsConstantInAddMulChain(Add))
2706 return getAddExpr(getMulExpr(LHSC, Add->getOperand(0),
2707 SCEV::FlagAnyWrap, Depth + 1),
2708 getMulExpr(LHSC, Add->getOperand(1),
2709 SCEV::FlagAnyWrap, Depth + 1),
2710 SCEV::FlagAnyWrap, Depth + 1);
2711
2712 ++Idx;
2713 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2714 // We found two constants, fold them together!
2715 ConstantInt *Fold =
2716 ConstantInt::get(getContext(), LHSC->getAPInt() * RHSC->getAPInt());
2717 Ops[0] = getConstant(Fold);
2718 Ops.erase(Ops.begin()+1); // Erase the folded element
2719 if (Ops.size() == 1) return Ops[0];
2720 LHSC = cast<SCEVConstant>(Ops[0]);
2721 }
2722
2723 // If we are left with a constant one being multiplied, strip it off.
2724 if (cast<SCEVConstant>(Ops[0])->getValue()->isOne()) {
2725 Ops.erase(Ops.begin());
2726 --Idx;
2727 } else if (cast<SCEVConstant>(Ops[0])->getValue()->isZero()) {
2728 // If we have a multiply of zero, it will always be zero.
2729 return Ops[0];
2730 } else if (Ops[0]->isAllOnesValue()) {
2731 // If we have a mul by -1 of an add, try distributing the -1 among the
2732 // add operands.
2733 if (Ops.size() == 2) {
2734 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) {
2735 SmallVector<const SCEV *, 4> NewOps;
2736 bool AnyFolded = false;
2737 for (const SCEV *AddOp : Add->operands()) {
2738 const SCEV *Mul = getMulExpr(Ops[0], AddOp, SCEV::FlagAnyWrap,
2739 Depth + 1);
2740 if (!isa<SCEVMulExpr>(Mul)) AnyFolded = true;
2741 NewOps.push_back(Mul);
2742 }
2743 if (AnyFolded)
2744 return getAddExpr(NewOps, SCEV::FlagAnyWrap, Depth + 1);
2745 } else if (const auto *AddRec = dyn_cast<SCEVAddRecExpr>(Ops[1])) {
2746 // Negation preserves a recurrence's no self-wrap property.
2747 SmallVector<const SCEV *, 4> Operands;
2748 for (const SCEV *AddRecOp : AddRec->operands())
2749 Operands.push_back(getMulExpr(Ops[0], AddRecOp, SCEV::FlagAnyWrap,
2750 Depth + 1));
2751
2752 return getAddRecExpr(Operands, AddRec->getLoop(),
2753 AddRec->getNoWrapFlags(SCEV::FlagNW));
2754 }
2755 }
2756 }
2757
2758 if (Ops.size() == 1)
2759 return Ops[0];
2760 }
2761
2762 // Skip over the add expression until we get to a multiply.
2763 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
2764 ++Idx;
2765
2766 // If there are mul operands inline them all into this expression.
2767 if (Idx < Ops.size()) {
2768 bool DeletedMul = false;
2769 while (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
2770 if (Ops.size() > MulOpsInlineThreshold)
2771 break;
2772 // If we have an mul, expand the mul operands onto the end of the
2773 // operands list.
2774 Ops.erase(Ops.begin()+Idx);
2775 Ops.append(Mul->op_begin(), Mul->op_end());
2776 DeletedMul = true;
2777 }
2778
2779 // If we deleted at least one mul, we added operands to the end of the
2780 // list, and they are not necessarily sorted. Recurse to resort and
2781 // resimplify any operands we just acquired.
2782 if (DeletedMul)
2783 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2784 }
2785
2786 // If there are any add recurrences in the operands list, see if any other
2787 // added values are loop invariant. If so, we can fold them into the
2788 // recurrence.
2789 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
2790 ++Idx;
2791
2792 // Scan over all recurrences, trying to fold loop invariants into them.
2793 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
2794 // Scan all of the other operands to this mul and add them to the vector
2795 // if they are loop invariant w.r.t. the recurrence.
2796 SmallVector<const SCEV *, 8> LIOps;
2797 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
2798 const Loop *AddRecLoop = AddRec->getLoop();
2799 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2800 if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) {
2801 LIOps.push_back(Ops[i]);
2802 Ops.erase(Ops.begin()+i);
2803 --i; --e;
2804 }
2805
2806 // If we found some loop invariants, fold them into the recurrence.
2807 if (!LIOps.empty()) {
2808 // NLI * LI * {Start,+,Step} --> NLI * {LI*Start,+,LI*Step}
2809 SmallVector<const SCEV *, 4> NewOps;
2810 NewOps.reserve(AddRec->getNumOperands());
2811 const SCEV *Scale = getMulExpr(LIOps, SCEV::FlagAnyWrap, Depth + 1);
2812 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i)
2813 NewOps.push_back(getMulExpr(Scale, AddRec->getOperand(i),
2814 SCEV::FlagAnyWrap, Depth + 1));
2815
2816 // Build the new addrec. Propagate the NUW and NSW flags if both the
2817 // outer mul and the inner addrec are guaranteed to have no overflow.
2818 //
2819 // No self-wrap cannot be guaranteed after changing the step size, but
2820 // will be inferred if either NUW or NSW is true.
2821 Flags = AddRec->getNoWrapFlags(clearFlags(Flags, SCEV::FlagNW));
2822 const SCEV *NewRec = getAddRecExpr(NewOps, AddRecLoop, Flags);
2823
2824 // If all of the other operands were loop invariant, we are done.
2825 if (Ops.size() == 1) return NewRec;
2826
2827 // Otherwise, multiply the folded AddRec by the non-invariant parts.
2828 for (unsigned i = 0;; ++i)
2829 if (Ops[i] == AddRec) {
2830 Ops[i] = NewRec;
2831 break;
2832 }
2833 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2834 }
2835
2836 // Okay, if there weren't any loop invariants to be folded, check to see
2837 // if there are multiple AddRec's with the same loop induction variable
2838 // being multiplied together. If so, we can fold them.
2839
2840 // {A1,+,A2,+,...,+,An}<L> * {B1,+,B2,+,...,+,Bn}<L>
2841 // = {x=1 in [ sum y=x..2x [ sum z=max(y-x, y-n)..min(x,n) [
2842 // choose(x, 2x)*choose(2x-y, x-z)*A_{y-z}*B_z
2843 // ]]],+,...up to x=2n}.
2844 // Note that the arguments to choose() are always integers with values
2845 // known at compile time, never SCEV objects.
2846 //
2847 // The implementation avoids pointless extra computations when the two
2848 // addrec's are of different length (mathematically, it's equivalent to
2849 // an infinite stream of zeros on the right).
2850 bool OpsModified = false;
2851 for (unsigned OtherIdx = Idx+1;
2852 OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2853 ++OtherIdx) {
2854 const SCEVAddRecExpr *OtherAddRec =
2855 dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]);
2856 if (!OtherAddRec || OtherAddRec->getLoop() != AddRecLoop)
2857 continue;
2858
2859 // Limit max number of arguments to avoid creation of unreasonably big
2860 // SCEVAddRecs with very complex operands.
2861 if (AddRec->getNumOperands() + OtherAddRec->getNumOperands() - 1 >
2862 MaxAddRecSize || hasHugeExpression({AddRec, OtherAddRec}))
2863 continue;
2864
2865 bool Overflow = false;
2866 Type *Ty = AddRec->getType();
2867 bool LargerThan64Bits = getTypeSizeInBits(Ty) > 64;
2868 SmallVector<const SCEV*, 7> AddRecOps;
2869 for (int x = 0, xe = AddRec->getNumOperands() +
2870 OtherAddRec->getNumOperands() - 1; x != xe && !Overflow; ++x) {
2871 SmallVector <const SCEV *, 7> SumOps;
2872 for (int y = x, ye = 2*x+1; y != ye && !Overflow; ++y) {
2873 uint64_t Coeff1 = Choose(x, 2*x - y, Overflow);
2874 for (int z = std::max(y-x, y-(int)AddRec->getNumOperands()+1),
2875 ze = std::min(x+1, (int)OtherAddRec->getNumOperands());
2876 z < ze && !Overflow; ++z) {
2877 uint64_t Coeff2 = Choose(2*x - y, x-z, Overflow);
2878 uint64_t Coeff;
2879 if (LargerThan64Bits)
2880 Coeff = umul_ov(Coeff1, Coeff2, Overflow);
2881 else
2882 Coeff = Coeff1*Coeff2;
2883 const SCEV *CoeffTerm = getConstant(Ty, Coeff);
2884 const SCEV *Term1 = AddRec->getOperand(y-z);
2885 const SCEV *Term2 = OtherAddRec->getOperand(z);
2886 SumOps.push_back(getMulExpr(CoeffTerm, Term1, Term2,
2887 SCEV::FlagAnyWrap, Depth + 1));
2888 }
2889 }
2890 if (SumOps.empty())
2891 SumOps.push_back(getZero(Ty));
2892 AddRecOps.push_back(getAddExpr(SumOps, SCEV::FlagAnyWrap, Depth + 1));
2893 }
2894 if (!Overflow) {
2895 const SCEV *NewAddRec = getAddRecExpr(AddRecOps, AddRecLoop,
2896 SCEV::FlagAnyWrap);
2897 if (Ops.size() == 2) return NewAddRec;
2898 Ops[Idx] = NewAddRec;
2899 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
2900 OpsModified = true;
2901 AddRec = dyn_cast<SCEVAddRecExpr>(NewAddRec);
2902 if (!AddRec)
2903 break;
2904 }
2905 }
2906 if (OpsModified)
2907 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2908
2909 // Otherwise couldn't fold anything into this recurrence. Move onto the
2910 // next one.
2911 }
2912
2913 // Okay, it looks like we really DO need an mul expr. Check to see if we
2914 // already have one, otherwise create a new one.
2915 return getOrCreateMulExpr(Ops, Flags);
2916}
2917
2918/// Represents an unsigned remainder expression based on unsigned division.
2919const SCEV *ScalarEvolution::getURemExpr(const SCEV *LHS,
2920 const SCEV *RHS) {
2921 assert(getEffectiveSCEVType(LHS->getType()) ==((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType
(RHS->getType()) && "SCEVURemExpr operand types don't match!"
) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2923, __PRETTY_FUNCTION__))
2922 getEffectiveSCEVType(RHS->getType()) &&((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType
(RHS->getType()) && "SCEVURemExpr operand types don't match!"
) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2923, __PRETTY_FUNCTION__))
2923 "SCEVURemExpr operand types don't match!")((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType
(RHS->getType()) && "SCEVURemExpr operand types don't match!"
) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2923, __PRETTY_FUNCTION__))
;
2924
2925 // Short-circuit easy cases
2926 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
2927 // If constant is one, the result is trivial
2928 if (RHSC->getValue()->isOne())
2929 return getZero(LHS->getType()); // X urem 1 --> 0
2930
2931 // If constant is a power of two, fold into a zext(trunc(LHS)).
2932 if (RHSC->getAPInt().isPowerOf2()) {
2933 Type *FullTy = LHS->getType();
2934 Type *TruncTy =
2935 IntegerType::get(getContext(), RHSC->getAPInt().logBase2());
2936 return getZeroExtendExpr(getTruncateExpr(LHS, TruncTy), FullTy);
2937 }
2938 }
2939
2940 // Fallback to %a == %x urem %y == %x -<nuw> ((%x udiv %y) *<nuw> %y)
2941 const SCEV *UDiv = getUDivExpr(LHS, RHS);
2942 const SCEV *Mult = getMulExpr(UDiv, RHS, SCEV::FlagNUW);
2943 return getMinusSCEV(LHS, Mult, SCEV::FlagNUW);
2944}
2945
2946/// Get a canonical unsigned division expression, or something simpler if
2947/// possible.
2948const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS,
2949 const SCEV *RHS) {
2950 assert(getEffectiveSCEVType(LHS->getType()) ==((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType
(RHS->getType()) && "SCEVUDivExpr operand types don't match!"
) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2952, __PRETTY_FUNCTION__))
2951 getEffectiveSCEVType(RHS->getType()) &&((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType
(RHS->getType()) && "SCEVUDivExpr operand types don't match!"
) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2952, __PRETTY_FUNCTION__))
2952 "SCEVUDivExpr operand types don't match!")((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType
(RHS->getType()) && "SCEVUDivExpr operand types don't match!"
) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2952, __PRETTY_FUNCTION__))
;
2953
2954 FoldingSetNodeID ID;
2955 ID.AddInteger(scUDivExpr);
2956 ID.AddPointer(LHS);
2957 ID.AddPointer(RHS);
2958 void *IP = nullptr;
2959 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
2960 return S;
2961
2962 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
2963 if (RHSC->getValue()->isOne())
2964 return LHS; // X udiv 1 --> x
2965 // If the denominator is zero, the result of the udiv is undefined. Don't
2966 // try to analyze it, because the resolution chosen here may differ from
2967 // the resolution chosen in other parts of the compiler.
2968 if (!RHSC->getValue()->isZero()) {
2969 // Determine if the division can be folded into the operands of
2970 // its operands.
2971 // TODO: Generalize this to non-constants by using known-bits information.
2972 Type *Ty = LHS->getType();
2973 unsigned LZ = RHSC->getAPInt().countLeadingZeros();
2974 unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ - 1;
2975 // For non-power-of-two values, effectively round the value up to the
2976 // nearest power of two.
2977 if (!RHSC->getAPInt().isPowerOf2())
2978 ++MaxShiftAmt;
2979 IntegerType *ExtTy =
2980 IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt);
2981 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS))
2982 if (const SCEVConstant *Step =
2983 dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this))) {
2984 // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded.
2985 const APInt &StepInt = Step->getAPInt();
2986 const APInt &DivInt = RHSC->getAPInt();
2987 if (!StepInt.urem(DivInt) &&
2988 getZeroExtendExpr(AR, ExtTy) ==
2989 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
2990 getZeroExtendExpr(Step, ExtTy),
2991 AR->getLoop(), SCEV::FlagAnyWrap)) {
2992 SmallVector<const SCEV *, 4> Operands;
2993 for (const SCEV *Op : AR->operands())
2994 Operands.push_back(getUDivExpr(Op, RHS));
2995 return getAddRecExpr(Operands, AR->getLoop(), SCEV::FlagNW);
2996 }
2997 /// Get a canonical UDivExpr for a recurrence.
2998 /// {X,+,N}/C => {Y,+,N}/C where Y=X-(X%N). Safe when C%N=0.
2999 // We can currently only fold X%N if X is constant.
3000 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(AR->getStart());
3001 if (StartC && !DivInt.urem(StepInt) &&
3002 getZeroExtendExpr(AR, ExtTy) ==
3003 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
3004 getZeroExtendExpr(Step, ExtTy),
3005 AR->getLoop(), SCEV::FlagAnyWrap)) {
3006 const APInt &StartInt = StartC->getAPInt();
3007 const APInt &StartRem = StartInt.urem(StepInt);
3008 if (StartRem != 0) {
3009 const SCEV *NewLHS =
3010 getAddRecExpr(getConstant(StartInt - StartRem), Step,
3011 AR->getLoop(), SCEV::FlagNW);
3012 if (LHS != NewLHS) {
3013 LHS = NewLHS;
3014
3015 // Reset the ID to include the new LHS, and check if it is
3016 // already cached.
3017 ID.clear();
3018 ID.AddInteger(scUDivExpr);
3019 ID.AddPointer(LHS);
3020 ID.AddPointer(RHS);
3021 IP = nullptr;
3022 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
3023 return S;
3024 }
3025 }
3026 }
3027 }
3028 // (A*B)/C --> A*(B/C) if safe and B/C can be folded.
3029 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) {
3030 SmallVector<const SCEV *, 4> Operands;
3031 for (const SCEV *Op : M->operands())
3032 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
3033 if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands))
3034 // Find an operand that's safely divisible.
3035 for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) {
3036 const SCEV *Op = M->getOperand(i);
3037 const SCEV *Div = getUDivExpr(Op, RHSC);
3038 if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) {
3039 Operands = SmallVector<const SCEV *, 4>(M->op_begin(),
3040 M->op_end());
3041 Operands[i] = Div;
3042 return getMulExpr(Operands);
3043 }
3044 }
3045 }
3046
3047 // (A/B)/C --> A/(B*C) if safe and B*C can be folded.
3048 if (const SCEVUDivExpr *OtherDiv = dyn_cast<SCEVUDivExpr>(LHS)) {
3049 if (auto *DivisorConstant =
3050 dyn_cast<SCEVConstant>(OtherDiv->getRHS())) {
3051 bool Overflow = false;
3052 APInt NewRHS =
3053 DivisorConstant->getAPInt().umul_ov(RHSC->getAPInt(), Overflow);
3054 if (Overflow) {
3055 return getConstant(RHSC->getType(), 0, false);
3056 }
3057 return getUDivExpr(OtherDiv->getLHS(), getConstant(NewRHS));
3058 }
3059 }
3060
3061 // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded.
3062 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(LHS)) {
3063 SmallVector<const SCEV *, 4> Operands;
3064 for (const SCEV *Op : A->operands())
3065 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
3066 if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) {
3067 Operands.clear();
3068 for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) {
3069 const SCEV *Op = getUDivExpr(A->getOperand(i), RHS);
3070 if (isa<SCEVUDivExpr>(Op) ||
3071 getMulExpr(Op, RHS) != A->getOperand(i))
3072 break;
3073 Operands.push_back(Op);
3074 }
3075 if (Operands.size() == A->getNumOperands())
3076 return getAddExpr(Operands);
3077 }
3078 }
3079
3080 // Fold if both operands are constant.
3081 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
3082 Constant *LHSCV = LHSC->getValue();
3083 Constant *RHSCV = RHSC->getValue();
3084 return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV,
3085 RHSCV)));
3086 }
3087 }
3088 }
3089
3090 // The Insertion Point (IP) might be invalid by now (due to UniqueSCEVs
3091 // changes). Make sure we get a new one.
3092 IP = nullptr;
3093 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
3094 SCEV *S = new (SCEVAllocator) SCEVUDivExpr(ID.Intern(SCEVAllocator),
3095 LHS, RHS);
3096 UniqueSCEVs.InsertNode(S, IP);
3097 addToLoopUseLists(S);
3098 return S;
3099}
3100
3101static const APInt gcd(const SCEVConstant *C1, const SCEVConstant *C2) {
3102 APInt A = C1->getAPInt().abs();
3103 APInt B = C2->getAPInt().abs();
3104 uint32_t ABW = A.getBitWidth();
3105 uint32_t BBW = B.getBitWidth();
3106
3107 if (ABW > BBW)
3108 B = B.zext(ABW);
3109 else if (ABW < BBW)
3110 A = A.zext(BBW);
3111
3112 return APIntOps::GreatestCommonDivisor(std::move(A), std::move(B));
3113}
3114
3115/// Get a canonical unsigned division expression, or something simpler if
3116/// possible. There is no representation for an exact udiv in SCEV IR, but we
3117/// can attempt to remove factors from the LHS and RHS. We can't do this when
3118/// it's not exact because the udiv may be clearing bits.
3119const SCEV *ScalarEvolution::getUDivExactExpr(const SCEV *LHS,
3120 const SCEV *RHS) {
3121 // TODO: we could try to find factors in all sorts of things, but for now we
3122 // just deal with u/exact (multiply, constant). See SCEVDivision towards the
3123 // end of this file for inspiration.
3124
3125 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS);
3126 if (!Mul || !Mul->hasNoUnsignedWrap())
3127 return getUDivExpr(LHS, RHS);
3128
3129 if (const SCEVConstant *RHSCst = dyn_cast<SCEVConstant>(RHS)) {
3130 // If the mulexpr multiplies by a constant, then that constant must be the
3131 // first element of the mulexpr.
3132 if (const auto *LHSCst = dyn_cast<SCEVConstant>(Mul->getOperand(0))) {
3133 if (LHSCst == RHSCst) {
3134 SmallVector<const SCEV *, 2> Operands;
3135 Operands.append(Mul->op_begin() + 1, Mul->op_end());
3136 return getMulExpr(Operands);
3137 }
3138
3139 // We can't just assume that LHSCst divides RHSCst cleanly, it could be
3140 // that there's a factor provided by one of the other terms. We need to
3141 // check.
3142 APInt Factor = gcd(LHSCst, RHSCst);
3143 if (!Factor.isIntN(1)) {
3144 LHSCst =
3145 cast<SCEVConstant>(getConstant(LHSCst->getAPInt().udiv(Factor)));
3146 RHSCst =
3147 cast<SCEVConstant>(getConstant(RHSCst->getAPInt().udiv(Factor)));
3148 SmallVector<const SCEV *, 2> Operands;
3149 Operands.push_back(LHSCst);
3150 Operands.append(Mul->op_begin() + 1, Mul->op_end());
3151 LHS = getMulExpr(Operands);
3152 RHS = RHSCst;
3153 Mul = dyn_cast<SCEVMulExpr>(LHS);
3154 if (!Mul)
3155 return getUDivExactExpr(LHS, RHS);
3156 }
3157 }
3158 }
3159
3160 for (int i = 0, e = Mul->getNumOperands(); i != e; ++i) {
3161 if (Mul->getOperand(i) == RHS) {
3162 SmallVector<const SCEV *, 2> Operands;
3163 Operands.append(Mul->op_begin(), Mul->op_begin() + i);
3164 Operands.append(Mul->op_begin() + i + 1, Mul->op_end());
3165 return getMulExpr(Operands);
3166 }
3167 }
3168
3169 return getUDivExpr(LHS, RHS);
3170}
3171
3172/// Get an add recurrence expression for the specified loop. Simplify the
3173/// expression as much as possible.
3174const SCEV *ScalarEvolution::getAddRecExpr(const SCEV *Start, const SCEV *Step,
3175 const Loop *L,
3176 SCEV::NoWrapFlags Flags) {
3177 SmallVector<const SCEV *, 4> Operands;
3178 Operands.push_back(Start);
3179 if (const SCEVAddRecExpr *StepChrec = dyn_cast<SCEVAddRecExpr>(Step))
3180 if (StepChrec->getLoop() == L) {
3181 Operands.append(StepChrec->op_begin(), StepChrec->op_end());
3182 return getAddRecExpr(Operands, L, maskFlags(Flags, SCEV::FlagNW));
3183 }
3184
3185 Operands.push_back(Step);
3186 return getAddRecExpr(Operands, L, Flags);
3187}
3188
3189/// Get an add recurrence expression for the specified loop. Simplify the
3190/// expression as much as possible.
3191const SCEV *
3192ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
3193 const Loop *L, SCEV::NoWrapFlags Flags) {
3194 if (Operands.size() == 1) return Operands[0];
3195#ifndef NDEBUG
3196 Type *ETy = getEffectiveSCEVType(Operands[0]->getType());
3197 for (unsigned i = 1, e = Operands.size(); i != e; ++i)
3198 assert(getEffectiveSCEVType(Operands[i]->getType()) == ETy &&((getEffectiveSCEVType(Operands[i]->getType()) == ETy &&
"SCEVAddRecExpr operand types don't match!") ? static_cast<
void> (0) : __assert_fail ("getEffectiveSCEVType(Operands[i]->getType()) == ETy && \"SCEVAddRecExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3199, __PRETTY_FUNCTION__))
3199 "SCEVAddRecExpr operand types don't match!")((getEffectiveSCEVType(Operands[i]->getType()) == ETy &&
"SCEVAddRecExpr operand types don't match!") ? static_cast<
void> (0) : __assert_fail ("getEffectiveSCEVType(Operands[i]->getType()) == ETy && \"SCEVAddRecExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3199, __PRETTY_FUNCTION__))
;
3200 for (unsigned i = 0, e = Operands.size(); i != e; ++i)
3201 assert(isLoopInvariant(Operands[i], L) &&((isLoopInvariant(Operands[i], L) && "SCEVAddRecExpr operand is not loop-invariant!"
) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Operands[i], L) && \"SCEVAddRecExpr operand is not loop-invariant!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3202, __PRETTY_FUNCTION__))
3202 "SCEVAddRecExpr operand is not loop-invariant!")((isLoopInvariant(Operands[i], L) && "SCEVAddRecExpr operand is not loop-invariant!"
) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Operands[i], L) && \"SCEVAddRecExpr operand is not loop-invariant!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3202, __PRETTY_FUNCTION__))
;
3203#endif
3204
3205 if (Operands.back()->isZero()) {
3206 Operands.pop_back();
3207 return getAddRecExpr(Operands, L, SCEV::FlagAnyWrap); // {X,+,0} --> X
3208 }
3209
3210 // It's tempting to want to call getConstantMaxBackedgeTakenCount count here and
3211 // use that information to infer NUW and NSW flags. However, computing a
3212 // BE count requires calling getAddRecExpr, so we may not yet have a
3213 // meaningful BE count at this point (and if we don't, we'd be stuck
3214 // with a SCEVCouldNotCompute as the cached BE count).
3215
3216 Flags = StrengthenNoWrapFlags(this, scAddRecExpr, Operands, Flags);
3217
3218 // Canonicalize nested AddRecs in by nesting them in order of loop depth.
3219 if (const SCEVAddRecExpr *NestedAR = dyn_cast<SCEVAddRecExpr>(Operands[0])) {
3220 const Loop *NestedLoop = NestedAR->getLoop();
3221 if (L->contains(NestedLoop)
3222 ? (L->getLoopDepth() < NestedLoop->getLoopDepth())
3223 : (!NestedLoop->contains(L) &&
3224 DT.dominates(L->getHeader(), NestedLoop->getHeader()))) {
3225 SmallVector<const SCEV *, 4> NestedOperands(NestedAR->op_begin(),
3226 NestedAR->op_end());
3227 Operands[0] = NestedAR->getStart();
3228 // AddRecs require their operands be loop-invariant with respect to their
3229 // loops. Don't perform this transformation if it would break this
3230 // requirement.
3231 bool AllInvariant = all_of(
3232 Operands, [&](const SCEV *Op) { return isLoopInvariant(Op, L); });
3233
3234 if (AllInvariant) {
3235 // Create a recurrence for the outer loop with the same step size.
3236 //
3237 // The outer recurrence keeps its NW flag but only keeps NUW/NSW if the
3238 // inner recurrence has the same property.
3239 SCEV::NoWrapFlags OuterFlags =
3240 maskFlags(Flags, SCEV::FlagNW | NestedAR->getNoWrapFlags());
3241
3242 NestedOperands[0] = getAddRecExpr(Operands, L, OuterFlags);
3243 AllInvariant = all_of(NestedOperands, [&](const SCEV *Op) {
3244 return isLoopInvariant(Op, NestedLoop);
3245 });
3246
3247 if (AllInvariant) {
3248 // Ok, both add recurrences are valid after the transformation.
3249 //
3250 // The inner recurrence keeps its NW flag but only keeps NUW/NSW if
3251 // the outer recurrence has the same property.
3252 SCEV::NoWrapFlags InnerFlags =
3253 maskFlags(NestedAR->getNoWrapFlags(), SCEV::FlagNW | Flags);
3254 return getAddRecExpr(NestedOperands, NestedLoop, InnerFlags);
3255 }
3256 }
3257 // Reset Operands to its original state.
3258 Operands[0] = NestedAR;
3259 }
3260 }
3261
3262 // Okay, it looks like we really DO need an addrec expr. Check to see if we
3263 // already have one, otherwise create a new one.
3264 return getOrCreateAddRecExpr(Operands, L, Flags);
3265}
3266
3267const SCEV *
3268ScalarEvolution::getGEPExpr(GEPOperator *GEP,
3269 const SmallVectorImpl<const SCEV *> &IndexExprs) {
3270 const SCEV *BaseExpr = getSCEV(GEP->getPointerOperand());
3271 // getSCEV(Base)->getType() has the same address space as Base->getType()
3272 // because SCEV::getType() preserves the address space.
3273 Type *IntIdxTy = getEffectiveSCEVType(BaseExpr->getType());
3274 // FIXME(PR23527): Don't blindly transfer the inbounds flag from the GEP
3275 // instruction to its SCEV, because the Instruction may be guarded by control
3276 // flow and the no-overflow bits may not be valid for the expression in any
3277 // context. This can be fixed similarly to how these flags are handled for
3278 // adds.
3279 SCEV::NoWrapFlags Wrap = GEP->isInBounds() ? SCEV::FlagNSW
3280 : SCEV::FlagAnyWrap;
3281
3282 const SCEV *TotalOffset = getZero(IntIdxTy);
3283 Type *CurTy = GEP->getType();
3284 bool FirstIter = true;
3285 for (const SCEV *IndexExpr : IndexExprs) {
3286 // Compute the (potentially symbolic) offset in bytes for this index.
3287 if (StructType *STy = dyn_cast<StructType>(CurTy)) {
3288 // For a struct, add the member offset.
3289 ConstantInt *Index = cast<SCEVConstant>(IndexExpr)->getValue();
3290 unsigned FieldNo = Index->getZExtValue();
3291 const SCEV *FieldOffset = getOffsetOfExpr(IntIdxTy, STy, FieldNo);
3292
3293 // Add the field offset to the running total offset.
3294 TotalOffset = getAddExpr(TotalOffset, FieldOffset);
3295
3296 // Update CurTy to the type of the field at Index.
3297 CurTy = STy->getTypeAtIndex(Index);
3298 } else {
3299 // Update CurTy to its element type.
3300 if (FirstIter) {
3301 assert(isa<PointerType>(CurTy) &&((isa<PointerType>(CurTy) && "The first index of a GEP indexes a pointer"
) ? static_cast<void> (0) : __assert_fail ("isa<PointerType>(CurTy) && \"The first index of a GEP indexes a pointer\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3302, __PRETTY_FUNCTION__))
3302 "The first index of a GEP indexes a pointer")((isa<PointerType>(CurTy) && "The first index of a GEP indexes a pointer"
) ? static_cast<void> (0) : __assert_fail ("isa<PointerType>(CurTy) && \"The first index of a GEP indexes a pointer\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3302, __PRETTY_FUNCTION__))
;
3303 CurTy = GEP->getSourceElementType();
3304 FirstIter = false;
3305 } else {
3306 CurTy = GetElementPtrInst::getTypeAtIndex(CurTy, (uint64_t)0);
3307 }
3308 // For an array, add the element offset, explicitly scaled.
3309 const SCEV *ElementSize = getSizeOfExpr(IntIdxTy, CurTy);
3310 // Getelementptr indices are signed.
3311 IndexExpr = getTruncateOrSignExtend(IndexExpr, IntIdxTy);
3312
3313 // Multiply the index by the element size to compute the element offset.
3314 const SCEV *LocalOffset = getMulExpr(IndexExpr, ElementSize, Wrap);
3315
3316 // Add the element offset to the running total offset.
3317 TotalOffset = getAddExpr(TotalOffset, LocalOffset);
3318 }
3319 }
3320
3321 // Add the total offset from all the GEP indices to the base.
3322 return getAddExpr(BaseExpr, TotalOffset, Wrap);
3323}
3324
3325std::tuple<SCEV *, FoldingSetNodeID, void *>
3326ScalarEvolution::findExistingSCEVInCache(int SCEVType,
3327 ArrayRef<const SCEV *> Ops) {
3328 FoldingSetNodeID ID;
3329 void *IP = nullptr;
3330 ID.AddInteger(SCEVType);
3331 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3332 ID.AddPointer(Ops[i]);
3333 return std::tuple<SCEV *, FoldingSetNodeID, void *>(
3334 UniqueSCEVs.FindNodeOrInsertPos(ID, IP), std::move(ID), IP);
3335}
3336
3337const SCEV *ScalarEvolution::getMinMaxExpr(unsigned Kind,
3338 SmallVectorImpl<const SCEV *> &Ops) {
3339 assert(!Ops.empty() && "Cannot get empty (u|s)(min|max)!")((!Ops.empty() && "Cannot get empty (u|s)(min|max)!")
? static_cast<void> (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty (u|s)(min|max)!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3339, __PRETTY_FUNCTION__))
;
3340 if (Ops.size() == 1) return Ops[0];
3341#ifndef NDEBUG
3342 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
3343 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
3344 assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&((getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
"Operand types don't match!") ? static_cast<void> (0) :
__assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"Operand types don't match!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3345, __PRETTY_FUNCTION__))
3345 "Operand types don't match!")((getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
"Operand types don't match!") ? static_cast<void> (0) :
__assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"Operand types don't match!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3345, __PRETTY_FUNCTION__))
;
3346#endif
3347
3348 bool IsSigned = Kind == scSMaxExpr || Kind == scSMinExpr;
3349 bool IsMax = Kind == scSMaxExpr || Kind == scUMaxExpr;
3350
3351 // Sort by complexity, this groups all similar expression types together.
3352 GroupByComplexity(Ops, &LI, DT);
3353
3354 // Check if we have created the same expression before.
3355 if (const SCEV *S = std::get<0>(findExistingSCEVInCache(Kind, Ops))) {
3356 return S;
3357 }
3358
3359 // If there are any constants, fold them together.
3360 unsigned Idx = 0;
3361 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
3362 ++Idx;
3363 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3363, __PRETTY_FUNCTION__))
;
3364 auto FoldOp = [&](const APInt &LHS, const APInt &RHS) {
3365 if (Kind == scSMaxExpr)
3366 return APIntOps::smax(LHS, RHS);
3367 else if (Kind == scSMinExpr)
3368 return APIntOps::smin(LHS, RHS);
3369 else if (Kind == scUMaxExpr)
3370 return APIntOps::umax(LHS, RHS);
3371 else if (Kind == scUMinExpr)
3372 return APIntOps::umin(LHS, RHS);
3373 llvm_unreachable("Unknown SCEV min/max opcode")::llvm::llvm_unreachable_internal("Unknown SCEV min/max opcode"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3373)
;
3374 };
3375
3376 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
3377 // We found two constants, fold them together!
3378 ConstantInt *Fold = ConstantInt::get(
3379 getContext(), FoldOp(LHSC->getAPInt(), RHSC->getAPInt()));
3380 Ops[0] = getConstant(Fold);
3381 Ops.erase(Ops.begin()+1); // Erase the folded element
3382 if (Ops.size() == 1) return Ops[0];
3383 LHSC = cast<SCEVConstant>(Ops[0]);
3384 }
3385
3386 bool IsMinV = LHSC->getValue()->isMinValue(IsSigned);
3387 bool IsMaxV = LHSC->getValue()->isMaxValue(IsSigned);
3388
3389 if (IsMax ? IsMinV : IsMaxV) {
3390 // If we are left with a constant minimum(/maximum)-int, strip it off.
3391 Ops.erase(Ops.begin());
3392 --Idx;
3393 } else if (IsMax ? IsMaxV : IsMinV) {
3394 // If we have a max(/min) with a constant maximum(/minimum)-int,
3395 // it will always be the extremum.
3396 return LHSC;
3397 }
3398
3399 if (Ops.size() == 1) return Ops[0];
3400 }
3401
3402 // Find the first operation of the same kind
3403 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < Kind)
3404 ++Idx;
3405
3406 // Check to see if one of the operands is of the same kind. If so, expand its
3407 // operands onto our operand list, and recurse to simplify.
3408 if (Idx < Ops.size()) {
3409 bool DeletedAny = false;
3410 while (Ops[Idx]->getSCEVType() == Kind) {
3411 const SCEVMinMaxExpr *SMME = cast<SCEVMinMaxExpr>(Ops[Idx]);
3412 Ops.erase(Ops.begin()+Idx);
3413 Ops.append(SMME->op_begin(), SMME->op_end());
3414 DeletedAny = true;
3415 }
3416
3417 if (DeletedAny)
3418 return getMinMaxExpr(Kind, Ops);
3419 }
3420
3421 // Okay, check to see if the same value occurs in the operand list twice. If
3422 // so, delete one. Since we sorted the list, these values are required to
3423 // be adjacent.
3424 llvm::CmpInst::Predicate GEPred =
3425 IsSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
3426 llvm::CmpInst::Predicate LEPred =
3427 IsSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
3428 llvm::CmpInst::Predicate FirstPred = IsMax ? GEPred : LEPred;
3429 llvm::CmpInst::Predicate SecondPred = IsMax ? LEPred : GEPred;
3430 for (unsigned i = 0, e = Ops.size() - 1; i != e; ++i) {
3431 if (Ops[i] == Ops[i + 1] ||
3432 isKnownViaNonRecursiveReasoning(FirstPred, Ops[i], Ops[i + 1])) {
3433 // X op Y op Y --> X op Y
3434 // X op Y --> X, if we know X, Y are ordered appropriately
3435 Ops.erase(Ops.begin() + i + 1, Ops.begin() + i + 2);
3436 --i;
3437 --e;
3438 } else if (isKnownViaNonRecursiveReasoning(SecondPred, Ops[i],
3439 Ops[i + 1])) {
3440 // X op Y --> Y, if we know X, Y are ordered appropriately
3441 Ops.erase(Ops.begin() + i, Ops.begin() + i + 1);
3442 --i;
3443 --e;
3444 }
3445 }
3446
3447 if (Ops.size() == 1) return Ops[0];
3448
3449 assert(!Ops.empty() && "Reduced smax down to nothing!")((!Ops.empty() && "Reduced smax down to nothing!") ? static_cast
<void> (0) : __assert_fail ("!Ops.empty() && \"Reduced smax down to nothing!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3449, __PRETTY_FUNCTION__))
;
3450
3451 // Okay, it looks like we really DO need an expr. Check to see if we
3452 // already have one, otherwise create a new one.
3453 const SCEV *ExistingSCEV;
3454 FoldingSetNodeID ID;
3455 void *IP;
3456 std::tie(ExistingSCEV, ID, IP) = findExistingSCEVInCache(Kind, Ops);
3457 if (ExistingSCEV)
3458 return ExistingSCEV;
3459 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
3460 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
3461 SCEV *S = new (SCEVAllocator) SCEVMinMaxExpr(
3462 ID.Intern(SCEVAllocator), static_cast<SCEVTypes>(Kind), O, Ops.size());
3463
3464 UniqueSCEVs.InsertNode(S, IP);
3465 addToLoopUseLists(S);
3466 return S;
3467}
3468
3469const SCEV *ScalarEvolution::getSMaxExpr(const SCEV *LHS, const SCEV *RHS) {
3470 SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
3471 return getSMaxExpr(Ops);
3472}
3473
3474const SCEV *ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3475 return getMinMaxExpr(scSMaxExpr, Ops);
3476}
3477
3478const SCEV *ScalarEvolution::getUMaxExpr(const SCEV *LHS, const SCEV *RHS) {
3479 SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
3480 return getUMaxExpr(Ops);
3481}
3482
3483const SCEV *ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3484 return getMinMaxExpr(scUMaxExpr, Ops);
3485}
3486
3487const SCEV *ScalarEvolution::getSMinExpr(const SCEV *LHS,
3488 const SCEV *RHS) {
3489 SmallVector<const SCEV *, 2> Ops = { LHS, RHS };
3490 return getSMinExpr(Ops);
3491}
3492
3493const SCEV *ScalarEvolution::getSMinExpr(SmallVectorImpl<const SCEV *> &Ops) {
3494 return getMinMaxExpr(scSMinExpr, Ops);
3495}
3496
3497const SCEV *ScalarEvolution::getUMinExpr(const SCEV *LHS,
3498 const SCEV *RHS) {
3499 SmallVector<const SCEV *, 2> Ops = { LHS, RHS };
3500 return getUMinExpr(Ops);
3501}
3502
3503const SCEV *ScalarEvolution::getUMinExpr(SmallVectorImpl<const SCEV *> &Ops) {
3504 return getMinMaxExpr(scUMinExpr, Ops);
3505}
3506
3507const SCEV *ScalarEvolution::getSizeOfExpr(Type *IntTy, Type *AllocTy) {
3508 // We can bypass creating a target-independent
3509 // constant expression and then folding it back into a ConstantInt.
3510 // This is just a compile-time optimization.
3511 if (isa<ScalableVectorType>(AllocTy)) {
3512 Constant *NullPtr = Constant::getNullValue(AllocTy->getPointerTo());
3513 Constant *One = ConstantInt::get(IntTy, 1);
3514 Constant *GEP = ConstantExpr::getGetElementPtr(AllocTy, NullPtr, One);
3515 return getSCEV(ConstantExpr::getPtrToInt(GEP, IntTy));
3516 }
3517 return getConstant(IntTy, getDataLayout().getTypeAllocSize(AllocTy));
3518}
3519
3520const SCEV *ScalarEvolution::getOffsetOfExpr(Type *IntTy,
3521 StructType *STy,
3522 unsigned FieldNo) {
3523 // We can bypass creating a target-independent
3524 // constant expression and then folding it back into a ConstantInt.
3525 // This is just a compile-time optimization.
3526 return getConstant(
3527 IntTy, getDataLayout().getStructLayout(STy)->getElementOffset(FieldNo));
3528}
3529
3530const SCEV *ScalarEvolution::getUnknown(Value *V) {
3531 // Don't attempt to do anything other than create a SCEVUnknown object
3532 // here. createSCEV only calls getUnknown after checking for all other
3533 // interesting possibilities, and any other code that calls getUnknown
3534 // is doing so in order to hide a value from SCEV canonicalization.
3535
3536 FoldingSetNodeID ID;
3537 ID.AddInteger(scUnknown);
3538 ID.AddPointer(V);
3539 void *IP = nullptr;
3540 if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) {
3541 assert(cast<SCEVUnknown>(S)->getValue() == V &&((cast<SCEVUnknown>(S)->getValue() == V && "Stale SCEVUnknown in uniquing map!"
) ? static_cast<void> (0) : __assert_fail ("cast<SCEVUnknown>(S)->getValue() == V && \"Stale SCEVUnknown in uniquing map!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3542, __PRETTY_FUNCTION__))
3542 "Stale SCEVUnknown in uniquing map!")((cast<SCEVUnknown>(S)->getValue() == V && "Stale SCEVUnknown in uniquing map!"
) ? static_cast<void> (0) : __assert_fail ("cast<SCEVUnknown>(S)->getValue() == V && \"Stale SCEVUnknown in uniquing map!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3542, __PRETTY_FUNCTION__))
;
3543 return S;
3544 }
3545 SCEV *S = new (SCEVAllocator) SCEVUnknown(ID.Intern(SCEVAllocator), V, this,
3546 FirstUnknown);
3547 FirstUnknown = cast<SCEVUnknown>(S);
3548 UniqueSCEVs.InsertNode(S, IP);
3549 return S;
3550}
3551
3552//===----------------------------------------------------------------------===//
3553// Basic SCEV Analysis and PHI Idiom Recognition Code
3554//
3555
3556/// Test if values of the given type are analyzable within the SCEV
3557/// framework. This primarily includes integer types, and it can optionally
3558/// include pointer types if the ScalarEvolution class has access to
3559/// target-specific information.
3560bool ScalarEvolution::isSCEVable(Type *Ty) const {
3561 // Integers and pointers are always SCEVable.
3562 return Ty->isIntOrPtrTy();
2
Calling 'Type::isIntOrPtrTy'
4
Returning from 'Type::isIntOrPtrTy'
5
Returning the value 1, which participates in a condition later
3563}
3564
3565/// Return the size in bits of the specified type, for which isSCEVable must
3566/// return true.
3567uint64_t ScalarEvolution::getTypeSizeInBits(Type *Ty) const {
3568 assert(isSCEVable(Ty) && "Type is not SCEVable!")((isSCEVable(Ty) && "Type is not SCEVable!") ? static_cast
<void> (0) : __assert_fail ("isSCEVable(Ty) && \"Type is not SCEVable!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3568, __PRETTY_FUNCTION__))
;
3569 if (Ty->isPointerTy())
3570 return getDataLayout().getIndexTypeSizeInBits(Ty);
3571 return getDataLayout().getTypeSizeInBits(Ty);
3572}
3573
3574/// Return a type with the same bitwidth as the given type and which represents
3575/// how SCEV will treat the given type, for which isSCEVable must return
3576/// true. For pointer types, this is the pointer index sized integer type.
3577Type *ScalarEvolution::getEffectiveSCEVType(Type *Ty) const {
3578 assert(isSCEVable(Ty) && "Type is not SCEVable!")((isSCEVable(Ty) && "Type is not SCEVable!") ? static_cast
<void> (0) : __assert_fail ("isSCEVable(Ty) && \"Type is not SCEVable!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3578, __PRETTY_FUNCTION__))
;
3579
3580 if (Ty->isIntegerTy())
3581 return Ty;
3582
3583 // The only other support type is pointer.
3584 assert(Ty->isPointerTy() && "Unexpected non-pointer non-integer type!")((Ty->isPointerTy() && "Unexpected non-pointer non-integer type!"
) ? static_cast<void> (0) : __assert_fail ("Ty->isPointerTy() && \"Unexpected non-pointer non-integer type!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3584, __PRETTY_FUNCTION__))
;
3585 return getDataLayout().getIndexType(Ty);
3586}
3587
3588Type *ScalarEvolution::getWiderType(Type *T1, Type *T2) const {
3589 return getTypeSizeInBits(T1) >= getTypeSizeInBits(T2) ? T1 : T2;
3590}
3591
3592const SCEV *ScalarEvolution::getCouldNotCompute() {
3593 return CouldNotCompute.get();
3594}
3595
3596bool ScalarEvolution::checkValidity(const SCEV *S) const {
3597 bool ContainsNulls = SCEVExprContains(S, [](const SCEV *S) {
3598 auto *SU = dyn_cast<SCEVUnknown>(S);
3599 return SU && SU->getValue() == nullptr;
3600 });
3601
3602 return !ContainsNulls;
3603}
3604
3605bool ScalarEvolution::containsAddRecurrence(const SCEV *S) {
3606 HasRecMapType::iterator I = HasRecMap.find(S);
3607 if (I != HasRecMap.end())
3608 return I->second;
3609
3610 bool FoundAddRec =
3611 SCEVExprContains(S, [](const SCEV *S) { return isa<SCEVAddRecExpr>(S); });
3612 HasRecMap.insert({S, FoundAddRec});
3613 return FoundAddRec;
3614}
3615
3616/// Try to split a SCEVAddExpr into a pair of {SCEV, ConstantInt}.
3617/// If \p S is a SCEVAddExpr and is composed of a sub SCEV S' and an
3618/// offset I, then return {S', I}, else return {\p S, nullptr}.
3619static std::pair<const SCEV *, ConstantInt *> splitAddExpr(const SCEV *S) {
3620 const auto *Add = dyn_cast<SCEVAddExpr>(S);
3621 if (!Add)
3622 return {S, nullptr};
3623
3624 if (Add->getNumOperands() != 2)
3625 return {S, nullptr};
3626
3627 auto *ConstOp = dyn_cast<SCEVConstant>(Add->getOperand(0));
3628 if (!ConstOp)
3629 return {S, nullptr};
3630
3631 return {Add->getOperand(1), ConstOp->getValue()};
3632}
3633
3634/// Return the ValueOffsetPair set for \p S. \p S can be represented
3635/// by the value and offset from any ValueOffsetPair in the set.
3636SetVector<ScalarEvolution::ValueOffsetPair> *
3637ScalarEvolution::getSCEVValues(const SCEV *S) {
3638 ExprValueMapType::iterator SI = ExprValueMap.find_as(S);
3639 if (SI == ExprValueMap.end())
3640 return nullptr;
3641#ifndef NDEBUG
3642 if (VerifySCEVMap) {
3643 // Check there is no dangling Value in the set returned.
3644 for (const auto &VE : SI->second)
3645 assert(ValueExprMap.count(VE.first))((ValueExprMap.count(VE.first)) ? static_cast<void> (0)
: __assert_fail ("ValueExprMap.count(VE.first)", "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3645, __PRETTY_FUNCTION__))
;
3646 }
3647#endif
3648 return &SI->second;
3649}
3650
3651/// Erase Value from ValueExprMap and ExprValueMap. ValueExprMap.erase(V)
3652/// cannot be used separately. eraseValueFromMap should be used to remove
3653/// V from ValueExprMap and ExprValueMap at the same time.
3654void ScalarEvolution::eraseValueFromMap(Value *V) {
3655 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
3656 if (I != ValueExprMap.end()) {
3657 const SCEV *S = I->second;
3658 // Remove {V, 0} from the set of ExprValueMap[S]
3659 if (SetVector<ValueOffsetPair> *SV = getSCEVValues(S))
3660 SV->remove({V, nullptr});
3661
3662 // Remove {V, Offset} from the set of ExprValueMap[Stripped]
3663 const SCEV *Stripped;
3664 ConstantInt *Offset;
3665 std::tie(Stripped, Offset) = splitAddExpr(S);
3666 if (Offset != nullptr) {
3667 if (SetVector<ValueOffsetPair> *SV = getSCEVValues(Stripped))
3668 SV->remove({V, Offset});
3669 }
3670 ValueExprMap.erase(V);
3671 }
3672}
3673
3674/// Check whether value has nuw/nsw/exact set but SCEV does not.
3675/// TODO: In reality it is better to check the poison recursively
3676/// but this is better than nothing.
3677static bool SCEVLostPoisonFlags(const SCEV *S, const Value *V) {
3678 if (auto *I = dyn_cast<Instruction>(V)) {
3679 if (isa<OverflowingBinaryOperator>(I)) {
3680 if (auto *NS = dyn_cast<SCEVNAryExpr>(S)) {
3681 if (I->hasNoSignedWrap() && !NS->hasNoSignedWrap())
3682 return true;
3683 if (I->hasNoUnsignedWrap() && !NS->hasNoUnsignedWrap())
3684 return true;
3685 }
3686 } else if (isa<PossiblyExactOperator>(I) && I->isExact())
3687 return true;
3688 }
3689 return false;
3690}
3691
3692/// Return an existing SCEV if it exists, otherwise analyze the expression and
3693/// create a new one.
3694const SCEV *ScalarEvolution::getSCEV(Value *V) {
3695 assert(isSCEVable(V->getType()) && "Value is not SCEVable!")((isSCEVable(V->getType()) && "Value is not SCEVable!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(V->getType()) && \"Value is not SCEVable!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3695, __PRETTY_FUNCTION__))
;
3696
3697 const SCEV *S = getExistingSCEV(V);
3698 if (S == nullptr) {
3699 S = createSCEV(V);
3700 // During PHI resolution, it is possible to create two SCEVs for the same
3701 // V, so it is needed to double check whether V->S is inserted into
3702 // ValueExprMap before insert S->{V, 0} into ExprValueMap.
3703 std::pair<ValueExprMapType::iterator, bool> Pair =
3704 ValueExprMap.insert({SCEVCallbackVH(V, this), S});
3705 if (Pair.second && !SCEVLostPoisonFlags(S, V)) {
3706 ExprValueMap[S].insert({V, nullptr});
3707
3708 // If S == Stripped + Offset, add Stripped -> {V, Offset} into
3709 // ExprValueMap.
3710 const SCEV *Stripped = S;
3711 ConstantInt *Offset = nullptr;
3712 std::tie(Stripped, Offset) = splitAddExpr(S);
3713 // If stripped is SCEVUnknown, don't bother to save
3714 // Stripped -> {V, offset}. It doesn't simplify and sometimes even
3715 // increase the complexity of the expansion code.
3716 // If V is GetElementPtrInst, don't save Stripped -> {V, offset}
3717 // because it may generate add/sub instead of GEP in SCEV expansion.
3718 if (Offset != nullptr && !isa<SCEVUnknown>(Stripped) &&
3719 !isa<GetElementPtrInst>(V))
3720 ExprValueMap[Stripped].insert({V, Offset});
3721 }
3722 }
3723 return S;
3724}
3725
3726const SCEV *ScalarEvolution::getExistingSCEV(Value *V) {
3727 assert(isSCEVable(V->getType()) && "Value is not SCEVable!")((isSCEVable(V->getType()) && "Value is not SCEVable!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(V->getType()) && \"Value is not SCEVable!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3727, __PRETTY_FUNCTION__))
;
3728
3729 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
3730 if (I != ValueExprMap.end()) {
3731 const SCEV *S = I->second;
3732 if (checkValidity(S))
3733 return S;
3734 eraseValueFromMap(V);
3735 forgetMemoizedResults(S);
3736 }
3737 return nullptr;
3738}
3739
3740/// Return a SCEV corresponding to -V = -1*V
3741const SCEV *ScalarEvolution::getNegativeSCEV(const SCEV *V,
3742 SCEV::NoWrapFlags Flags) {
3743 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
3744 return getConstant(
3745 cast<ConstantInt>(ConstantExpr::getNeg(VC->getValue())));
3746
3747 Type *Ty = V->getType();
3748 Ty = getEffectiveSCEVType(Ty);
3749 return getMulExpr(
3750 V, getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty))), Flags);
3751}
3752
3753/// If Expr computes ~A, return A else return nullptr
3754static const SCEV *MatchNotExpr(const SCEV *Expr) {
3755 const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Expr);
3756 if (!Add || Add->getNumOperands() != 2 ||
3757 !Add->getOperand(0)->isAllOnesValue())
3758 return nullptr;
3759
3760 const SCEVMulExpr *AddRHS = dyn_cast<SCEVMulExpr>(Add->getOperand(1));
3761 if (!AddRHS || AddRHS->getNumOperands() != 2 ||
3762 !AddRHS->getOperand(0)->isAllOnesValue())
3763 return nullptr;
3764
3765 return AddRHS->getOperand(1);
3766}
3767
3768/// Return a SCEV corresponding to ~V = -1-V
3769const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) {
3770 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
3771 return getConstant(
3772 cast<ConstantInt>(ConstantExpr::getNot(VC->getValue())));
3773
3774 // Fold ~(u|s)(min|max)(~x, ~y) to (u|s)(max|min)(x, y)
3775 if (const SCEVMinMaxExpr *MME = dyn_cast<SCEVMinMaxExpr>(V)) {
3776 auto MatchMinMaxNegation = [&](const SCEVMinMaxExpr *MME) {
3777 SmallVector<const SCEV *, 2> MatchedOperands;
3778 for (const SCEV *Operand : MME->operands()) {
3779 const SCEV *Matched = MatchNotExpr(Operand);
3780 if (!Matched)
3781 return (const SCEV *)nullptr;
3782 MatchedOperands.push_back(Matched);
3783 }
3784 return getMinMaxExpr(
3785 SCEVMinMaxExpr::negate(static_cast<SCEVTypes>(MME->getSCEVType())),
3786 MatchedOperands);
3787 };
3788 if (const SCEV *Replaced = MatchMinMaxNegation(MME))
3789 return Replaced;
3790 }
3791
3792 Type *Ty = V->getType();
3793 Ty = getEffectiveSCEVType(Ty);
3794 const SCEV *AllOnes =
3795 getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty)));
3796 return getMinusSCEV(AllOnes, V);
3797}
3798
3799const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS, const SCEV *RHS,
3800 SCEV::NoWrapFlags Flags,
3801 unsigned Depth) {
3802 // Fast path: X - X --> 0.
3803 if (LHS == RHS)
3804 return getZero(LHS->getType());
3805
3806 // We represent LHS - RHS as LHS + (-1)*RHS. This transformation
3807 // makes it so that we cannot make much use of NUW.
3808 auto AddFlags = SCEV::FlagAnyWrap;
3809 const bool RHSIsNotMinSigned =
3810 !getSignedRangeMin(RHS).isMinSignedValue();
3811 if (maskFlags(Flags, SCEV::FlagNSW) == SCEV::FlagNSW) {
3812 // Let M be the minimum representable signed value. Then (-1)*RHS
3813 // signed-wraps if and only if RHS is M. That can happen even for
3814 // a NSW subtraction because e.g. (-1)*M signed-wraps even though
3815 // -1 - M does not. So to transfer NSW from LHS - RHS to LHS +
3816 // (-1)*RHS, we need to prove that RHS != M.
3817 //
3818 // If LHS is non-negative and we know that LHS - RHS does not
3819 // signed-wrap, then RHS cannot be M. So we can rule out signed-wrap
3820 // either by proving that RHS > M or that LHS >= 0.
3821 if (RHSIsNotMinSigned || isKnownNonNegative(LHS)) {
3822 AddFlags = SCEV::FlagNSW;
3823 }
3824 }
3825
3826 // FIXME: Find a correct way to transfer NSW to (-1)*M when LHS -
3827 // RHS is NSW and LHS >= 0.
3828 //
3829 // The difficulty here is that the NSW flag may have been proven
3830 // relative to a loop that is to be found in a recurrence in LHS and
3831 // not in RHS. Applying NSW to (-1)*M may then let the NSW have a
3832 // larger scope than intended.
3833 auto NegFlags = RHSIsNotMinSigned ? SCEV::FlagNSW : SCEV::FlagAnyWrap;
3834
3835 return getAddExpr(LHS, getNegativeSCEV(RHS, NegFlags), AddFlags, Depth);
3836}
3837
3838const SCEV *ScalarEvolution::getTruncateOrZeroExtend(const SCEV *V, Type *Ty,
3839 unsigned Depth) {
3840 Type *SrcTy = V->getType();
3841 assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&
"Cannot truncate or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3842, __PRETTY_FUNCTION__))
3842 "Cannot truncate or zero extend with non-integer arguments!")((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&
"Cannot truncate or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3842, __PRETTY_FUNCTION__))
;
3843 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3844 return V; // No conversion
3845 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
3846 return getTruncateExpr(V, Ty, Depth);
3847 return getZeroExtendExpr(V, Ty, Depth);
3848}
3849
3850const SCEV *ScalarEvolution::getTruncateOrSignExtend(const SCEV *V, Type *Ty,
3851 unsigned Depth) {
3852 Type *SrcTy = V->getType();
3853 assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&
"Cannot truncate or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3854, __PRETTY_FUNCTION__))
3854 "Cannot truncate or zero extend with non-integer arguments!")((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&
"Cannot truncate or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3854, __PRETTY_FUNCTION__))
;
3855 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3856 return V; // No conversion
3857 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
3858 return getTruncateExpr(V, Ty, Depth);
3859 return getSignExtendExpr(V, Ty, Depth);
3860}
3861
3862const SCEV *
3863ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, Type *Ty) {
3864 Type *SrcTy = V->getType();
3865 assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&
"Cannot noop or zero extend with non-integer arguments!") ? static_cast
<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or zero extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3866, __PRETTY_FUNCTION__))
3866 "Cannot noop or zero extend with non-integer arguments!")((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&
"Cannot noop or zero extend with non-integer arguments!") ? static_cast
<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or zero extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3866, __PRETTY_FUNCTION__))
;
3867 assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
"getNoopOrZeroExtend cannot truncate!") ? static_cast<void
> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrZeroExtend cannot truncate!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3868, __PRETTY_FUNCTION__))
3868 "getNoopOrZeroExtend cannot truncate!")((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
"getNoopOrZeroExtend cannot truncate!") ? static_cast<void
> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrZeroExtend cannot truncate!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3868, __PRETTY_FUNCTION__))
;
3869 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3870 return V; // No conversion
3871 return getZeroExtendExpr(V, Ty);
3872}
3873
3874const SCEV *
3875ScalarEvolution::getNoopOrSignExtend(const SCEV *V, Type *Ty) {
3876 Type *SrcTy = V->getType();
3877 assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&
"Cannot noop or sign extend with non-integer arguments!") ? static_cast
<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or sign extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3878, __PRETTY_FUNCTION__))
3878 "Cannot noop or sign extend with non-integer arguments!")((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&
"Cannot noop or sign extend with non-integer arguments!") ? static_cast
<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or sign extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3878, __PRETTY_FUNCTION__))
;
3879 assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
"getNoopOrSignExtend cannot truncate!") ? static_cast<void
> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrSignExtend cannot truncate!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3880, __PRETTY_FUNCTION__))
3880 "getNoopOrSignExtend cannot truncate!")((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
"getNoopOrSignExtend cannot truncate!") ? static_cast<void
> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrSignExtend cannot truncate!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3880, __PRETTY_FUNCTION__))
;
3881 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3882 return V; // No conversion
3883 return getSignExtendExpr(V, Ty);
3884}
3885
3886const SCEV *
3887ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, Type *Ty) {
3888 Type *SrcTy = V->getType();
3889 assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&
"Cannot noop or any extend with non-integer arguments!") ? static_cast
<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or any extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3890, __PRETTY_FUNCTION__))
3890 "Cannot noop or any extend with non-integer arguments!")((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&
"Cannot noop or any extend with non-integer arguments!") ? static_cast
<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or any extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3890, __PRETTY_FUNCTION__))
;
3891 assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
"getNoopOrAnyExtend cannot truncate!") ? static_cast<void
> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrAnyExtend cannot truncate!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3892, __PRETTY_FUNCTION__))
3892 "getNoopOrAnyExtend cannot truncate!")((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
"getNoopOrAnyExtend cannot truncate!") ? static_cast<void
> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrAnyExtend cannot truncate!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3892, __PRETTY_FUNCTION__))
;
3893 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3894 return V; // No conversion
3895 return getAnyExtendExpr(V, Ty);
3896}
3897
3898const SCEV *
3899ScalarEvolution::getTruncateOrNoop(const SCEV *V, Type *Ty) {
3900 Type *SrcTy = V->getType();
3901 assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&
"Cannot truncate or noop with non-integer arguments!") ? static_cast
<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or noop with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3902, __PRETTY_FUNCTION__))
3902 "Cannot truncate or noop with non-integer arguments!")((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&
"Cannot truncate or noop with non-integer arguments!") ? static_cast
<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or noop with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3902, __PRETTY_FUNCTION__))
;
3903 assert(getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) &&
"getTruncateOrNoop cannot extend!") ? static_cast<void>
(0) : __assert_fail ("getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && \"getTruncateOrNoop cannot extend!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3904, __PRETTY_FUNCTION__))
3904 "getTruncateOrNoop cannot extend!")((getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) &&
"getTruncateOrNoop cannot extend!") ? static_cast<void>
(0) : __assert_fail ("getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && \"getTruncateOrNoop cannot extend!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3904, __PRETTY_FUNCTION__))
;
3905 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3906 return V; // No conversion
3907 return getTruncateExpr(V, Ty);
3908}
3909
3910const SCEV *ScalarEvolution::getUMaxFromMismatchedTypes(const SCEV *LHS,
3911 const SCEV *RHS) {
3912 const SCEV *PromotedLHS = LHS;
3913 const SCEV *PromotedRHS = RHS;
3914
3915 if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType()))
3916 PromotedRHS = getZeroExtendExpr(RHS, LHS->getType());
3917 else
3918 PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType());
3919
3920 return getUMaxExpr(PromotedLHS, PromotedRHS);
3921}
3922
3923const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(const SCEV *LHS,
3924 const SCEV *RHS) {
3925 SmallVector<const SCEV *, 2> Ops = { LHS, RHS };
3926 return getUMinFromMismatchedTypes(Ops);
3927}
3928
3929const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(
3930 SmallVectorImpl<const SCEV *> &Ops) {
3931 assert(!Ops.empty() && "At least one operand must be!")((!Ops.empty() && "At least one operand must be!") ? static_cast
<void> (0) : __assert_fail ("!Ops.empty() && \"At least one operand must be!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3931, __PRETTY_FUNCTION__))
;
3932 // Trivial case.
3933 if (Ops.size() == 1)
3934 return Ops[0];
3935
3936 // Find the max type first.
3937 Type *MaxType = nullptr;
3938 for (auto *S : Ops)
3939 if (MaxType)
3940 MaxType = getWiderType(MaxType, S->getType());
3941 else
3942 MaxType = S->getType();
3943
3944 // Extend all ops to max type.
3945 SmallVector<const SCEV *, 2> PromotedOps;
3946 for (auto *S : Ops)
3947 PromotedOps.push_back(getNoopOrZeroExtend(S, MaxType));
3948
3949 // Generate umin.
3950 return getUMinExpr(PromotedOps);
3951}
3952
3953const SCEV *ScalarEvolution::getPointerBase(const SCEV *V) {
3954 // A pointer operand may evaluate to a nonpointer expression, such as null.
3955 if (!V->getType()->isPointerTy())
3956 return V;
3957
3958 while (true) {
3959 if (const SCEVCastExpr *Cast = dyn_cast<SCEVCastExpr>(V)) {
3960 V = Cast->getOperand();
3961 } else if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(V)) {
3962 const SCEV *PtrOp = nullptr;
3963 for (const SCEV *NAryOp : NAry->operands()) {
3964 if (NAryOp->getType()->isPointerTy()) {
3965 // Cannot find the base of an expression with multiple pointer ops.
3966 if (PtrOp)
3967 return V;
3968 PtrOp = NAryOp;
3969 }
3970 }
3971 if (!PtrOp) // All operands were non-pointer.
3972 return V;
3973 V = PtrOp;
3974 } else // Not something we can look further into.
3975 return V;
3976 }
3977}
3978
3979/// Push users of the given Instruction onto the given Worklist.
3980static void
3981PushDefUseChildren(Instruction *I,
3982 SmallVectorImpl<Instruction *> &Worklist) {
3983 // Push the def-use children onto the Worklist stack.
3984 for (User *U : I->users())
3985 Worklist.push_back(cast<Instruction>(U));
3986}
3987
3988void ScalarEvolution::forgetSymbolicName(Instruction *PN, const SCEV *SymName) {
3989 SmallVector<Instruction *, 16> Worklist;
3990 PushDefUseChildren(PN, Worklist);
3991
3992 SmallPtrSet<Instruction *, 8> Visited;
3993 Visited.insert(PN);
3994 while (!Worklist.empty()) {
3995 Instruction *I = Worklist.pop_back_val();
3996 if (!Visited.insert(I).second)
3997 continue;
3998
3999 auto It = ValueExprMap.find_as(static_cast<Value *>(I));
4000 if (It != ValueExprMap.end()) {
4001 const SCEV *Old = It->second;
4002
4003 // Short-circuit the def-use traversal if the symbolic name
4004 // ceases to appear in expressions.
4005 if (Old != SymName && !hasOperand(Old, SymName))
4006 continue;
4007
4008 // SCEVUnknown for a PHI either means that it has an unrecognized
4009 // structure, it's a PHI that's in the progress of being computed
4010 // by createNodeForPHI, or it's a single-value PHI. In the first case,
4011 // additional loop trip count information isn't going to change anything.
4012 // In the second case, createNodeForPHI will perform the necessary
4013 // updates on its own when it gets to that point. In the third, we do
4014 // want to forget the SCEVUnknown.
4015 if (!isa<PHINode>(I) ||
4016 !isa<SCEVUnknown>(Old) ||
4017 (I != PN && Old == SymName)) {
4018 eraseValueFromMap(It->first);
4019 forgetMemoizedResults(Old);
4020 }
4021 }
4022
4023 PushDefUseChildren(I, Worklist);
4024 }
4025}
4026
4027namespace {
4028
4029/// Takes SCEV S and Loop L. For each AddRec sub-expression, use its start
4030/// expression in case its Loop is L. If it is not L then
4031/// if IgnoreOtherLoops is true then use AddRec itself
4032/// otherwise rewrite cannot be done.
4033/// If SCEV contains non-invariant unknown SCEV rewrite cannot be done.
4034class SCEVInitRewriter : public SCEVRewriteVisitor<SCEVInitRewriter> {
4035public:
4036 static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE,
4037 bool IgnoreOtherLoops = true) {
4038 SCEVInitRewriter Rewriter(L, SE);
4039 const SCEV *Result = Rewriter.visit(S);
4040 if (Rewriter.hasSeenLoopVariantSCEVUnknown())
4041 return SE.getCouldNotCompute();
4042 return Rewriter.hasSeenOtherLoops() && !IgnoreOtherLoops
4043 ? SE.getCouldNotCompute()
4044 : Result;
4045 }
4046
4047 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4048 if (!SE.isLoopInvariant(Expr, L))
4049 SeenLoopVariantSCEVUnknown = true;
4050 return Expr;
4051 }
4052
4053 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4054 // Only re-write AddRecExprs for this loop.
4055 if (Expr->getLoop() == L)
4056 return Expr->getStart();
4057 SeenOtherLoops = true;
4058 return Expr;
4059 }
4060
4061 bool hasSeenLoopVariantSCEVUnknown() { return SeenLoopVariantSCEVUnknown; }
4062
4063 bool hasSeenOtherLoops() { return SeenOtherLoops; }
4064
4065private:
4066 explicit SCEVInitRewriter(const Loop *L, ScalarEvolution &SE)
4067 : SCEVRewriteVisitor(SE), L(L) {}
4068
4069 const Loop *L;
4070 bool SeenLoopVariantSCEVUnknown = false;
4071 bool SeenOtherLoops = false;
4072};
4073
4074/// Takes SCEV S and Loop L. For each AddRec sub-expression, use its post
4075/// increment expression in case its Loop is L. If it is not L then
4076/// use AddRec itself.
4077/// If SCEV contains non-invariant unknown SCEV rewrite cannot be done.
4078class SCEVPostIncRewriter : public SCEVRewriteVisitor<SCEVPostIncRewriter> {
4079public:
4080 static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE) {
4081 SCEVPostIncRewriter Rewriter(L, SE);
4082 const SCEV *Result = Rewriter.visit(S);
4083 return Rewriter.hasSeenLoopVariantSCEVUnknown()
4084 ? SE.getCouldNotCompute()
4085 : Result;
4086 }
4087
4088 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4089 if (!SE.isLoopInvariant(Expr, L))
4090 SeenLoopVariantSCEVUnknown = true;
4091 return Expr;
4092 }
4093
4094 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4095 // Only re-write AddRecExprs for this loop.
4096 if (Expr->getLoop() == L)
4097 return Expr->getPostIncExpr(SE);
4098 SeenOtherLoops = true;
4099 return Expr;
4100 }
4101
4102 bool hasSeenLoopVariantSCEVUnknown() { return SeenLoopVariantSCEVUnknown; }
4103
4104 bool hasSeenOtherLoops() { return SeenOtherLoops; }
4105
4106private:
4107 explicit SCEVPostIncRewriter(const Loop *L, ScalarEvolution &SE)
4108 : SCEVRewriteVisitor(SE), L(L) {}
4109
4110 const Loop *L;
4111 bool SeenLoopVariantSCEVUnknown = false;
4112 bool SeenOtherLoops = false;
4113};
4114
4115/// This class evaluates the compare condition by matching it against the
4116/// condition of loop latch. If there is a match we assume a true value
4117/// for the condition while building SCEV nodes.
4118class SCEVBackedgeConditionFolder
4119 : public SCEVRewriteVisitor<SCEVBackedgeConditionFolder> {
4120public:
4121 static const SCEV *rewrite(const SCEV *S, const Loop *L,
4122 ScalarEvolution &SE) {
4123 bool IsPosBECond = false;
4124 Value *BECond = nullptr;
4125 if (BasicBlock *Latch = L->getLoopLatch()) {
4126 BranchInst *BI = dyn_cast<BranchInst>(Latch->getTerminator());
4127 if (BI && BI->isConditional()) {
4128 assert(BI->getSuccessor(0) != BI->getSuccessor(1) &&((BI->getSuccessor(0) != BI->getSuccessor(1) &&
"Both outgoing branches should not target same header!") ? static_cast
<void> (0) : __assert_fail ("BI->getSuccessor(0) != BI->getSuccessor(1) && \"Both outgoing branches should not target same header!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4129, __PRETTY_FUNCTION__))
4129 "Both outgoing branches should not target same header!")((BI->getSuccessor(0) != BI->getSuccessor(1) &&
"Both outgoing branches should not target same header!") ? static_cast
<void> (0) : __assert_fail ("BI->getSuccessor(0) != BI->getSuccessor(1) && \"Both outgoing branches should not target same header!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4129, __PRETTY_FUNCTION__))
;
4130 BECond = BI->getCondition();
4131 IsPosBECond = BI->getSuccessor(0) == L->getHeader();
4132 } else {
4133 return S;
4134 }
4135 }
4136 SCEVBackedgeConditionFolder Rewriter(L, BECond, IsPosBECond, SE);
4137 return Rewriter.visit(S);
4138 }
4139
4140 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4141 const SCEV *Result = Expr;
4142 bool InvariantF = SE.isLoopInvariant(Expr, L);
4143
4144 if (!InvariantF) {
4145 Instruction *I = cast<Instruction>(Expr->getValue());
4146 switch (I->getOpcode()) {
4147 case Instruction::Select: {
4148 SelectInst *SI = cast<SelectInst>(I);
4149 Optional<const SCEV *> Res =
4150 compareWithBackedgeCondition(SI->getCondition());
4151 if (Res.hasValue()) {
4152 bool IsOne = cast<SCEVConstant>(Res.getValue())->getValue()->isOne();
4153 Result = SE.getSCEV(IsOne ? SI->getTrueValue() : SI->getFalseValue());
4154 }
4155 break;
4156 }
4157 default: {
4158 Optional<const SCEV *> Res = compareWithBackedgeCondition(I);
4159 if (Res.hasValue())
4160 Result = Res.getValue();
4161 break;
4162 }
4163 }
4164 }
4165 return Result;
4166 }
4167
4168private:
4169 explicit SCEVBackedgeConditionFolder(const Loop *L, Value *BECond,
4170 bool IsPosBECond, ScalarEvolution &SE)
4171 : SCEVRewriteVisitor(SE), L(L), BackedgeCond(BECond),
4172 IsPositiveBECond(IsPosBECond) {}
4173
4174 Optional<const SCEV *> compareWithBackedgeCondition(Value *IC);
4175
4176 const Loop *L;
4177 /// Loop back condition.
4178 Value *BackedgeCond = nullptr;
4179 /// Set to true if loop back is on positive branch condition.
4180 bool IsPositiveBECond;
4181};
4182
4183Optional<const SCEV *>
4184SCEVBackedgeConditionFolder::compareWithBackedgeCondition(Value *IC) {
4185
4186 // If value matches the backedge condition for loop latch,
4187 // then return a constant evolution node based on loopback
4188 // branch taken.
4189 if (BackedgeCond == IC)
4190 return IsPositiveBECond ? SE.getOne(Type::getInt1Ty(SE.getContext()))
4191 : SE.getZero(Type::getInt1Ty(SE.getContext()));
4192 return None;
4193}
4194
4195class SCEVShiftRewriter : public SCEVRewriteVisitor<SCEVShiftRewriter> {
4196public:
4197 static const SCEV *rewrite(const SCEV *S, const Loop *L,
4198 ScalarEvolution &SE) {
4199 SCEVShiftRewriter Rewriter(L, SE);
4200 const SCEV *Result = Rewriter.visit(S);
4201 return Rewriter.isValid() ? Result : SE.getCouldNotCompute();
4202 }
4203
4204 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4205 // Only allow AddRecExprs for this loop.
4206 if (!SE.isLoopInvariant(Expr, L))
4207 Valid = false;
4208 return Expr;
4209 }
4210
4211 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4212 if (Expr->getLoop() == L && Expr->isAffine())
4213 return SE.getMinusSCEV(Expr, Expr->getStepRecurrence(SE));
4214 Valid = false;
4215 return Expr;
4216 }
4217
4218 bool isValid() { return Valid; }
4219
4220private:
4221 explicit SCEVShiftRewriter(const Loop *L, ScalarEvolution &SE)
4222 : SCEVRewriteVisitor(SE), L(L) {}
4223
4224 const Loop *L;
4225 bool Valid = true;
4226};
4227
4228} // end anonymous namespace
4229
4230SCEV::NoWrapFlags
4231ScalarEvolution::proveNoWrapViaConstantRanges(const SCEVAddRecExpr *AR) {
4232 if (!AR->isAffine())
4233 return SCEV::FlagAnyWrap;
4234
4235 using OBO = OverflowingBinaryOperator;
4236
4237 SCEV::NoWrapFlags Result = SCEV::FlagAnyWrap;
4238
4239 if (!AR->hasNoSignedWrap()) {
4240 ConstantRange AddRecRange = getSignedRange(AR);
4241 ConstantRange IncRange = getSignedRange(AR->getStepRecurrence(*this));
4242
4243 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
4244 Instruction::Add, IncRange, OBO::NoSignedWrap);
4245 if (NSWRegion.contains(AddRecRange))
4246 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNSW);
4247 }
4248
4249 if (!AR->hasNoUnsignedWrap()) {
4250 ConstantRange AddRecRange = getUnsignedRange(AR);
4251 ConstantRange IncRange = getUnsignedRange(AR->getStepRecurrence(*this));
4252
4253 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
4254 Instruction::Add, IncRange, OBO::NoUnsignedWrap);
4255 if (NUWRegion.contains(AddRecRange))
4256 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNUW);
4257 }
4258
4259 return Result;
4260}
4261
4262namespace {
4263
4264/// Represents an abstract binary operation. This may exist as a
4265/// normal instruction or constant expression, or may have been
4266/// derived from an expression tree.
4267struct BinaryOp {
4268 unsigned Opcode;
4269 Value *LHS;
4270 Value *RHS;
4271 bool IsNSW = false;
4272 bool IsNUW = false;
4273
4274 /// Op is set if this BinaryOp corresponds to a concrete LLVM instruction or
4275 /// constant expression.
4276 Operator *Op = nullptr;
4277
4278 explicit BinaryOp(Operator *Op)
4279 : Opcode(Op->getOpcode()), LHS(Op->getOperand(0)), RHS(Op->getOperand(1)),
4280 Op(Op) {
4281 if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(Op)) {
4282 IsNSW = OBO->hasNoSignedWrap();
4283 IsNUW = OBO->hasNoUnsignedWrap();
4284 }
4285 }
4286
4287 explicit BinaryOp(unsigned Opcode, Value *LHS, Value *RHS, bool IsNSW = false,
4288 bool IsNUW = false)
4289 : Opcode(Opcode), LHS(LHS), RHS(RHS), IsNSW(IsNSW), IsNUW(IsNUW) {}
4290};
4291
4292} // end anonymous namespace
4293
4294/// Try to map \p V into a BinaryOp, and return \c None on failure.
4295static Optional<BinaryOp> MatchBinaryOp(Value *V, DominatorTree &DT) {
4296 auto *Op = dyn_cast<Operator>(V);
20
Assuming 'V' is a 'Operator'
4297 if (!Op
20.1
'Op' is non-null
20.1
'Op' is non-null
20.1
'Op' is non-null
)
21
Taking false branch
4298 return None;
4299
4300 // Implementation detail: all the cleverness here should happen without
4301 // creating new SCEV expressions -- our caller knowns tricks to avoid creating
4302 // SCEV expressions when possible, and we should not break that.
4303
4304 switch (Op->getOpcode()) {
22
Control jumps to 'case ExtractValue:' at line 4342
4305 case Instruction::Add:
4306 case Instruction::Sub:
4307 case Instruction::Mul:
4308 case Instruction::UDiv:
4309 case Instruction::URem:
4310 case Instruction::And:
4311 case Instruction::Or:
4312 case Instruction::AShr:
4313 case Instruction::Shl:
4314 return BinaryOp(Op);
4315
4316 case Instruction::Xor:
4317 if (auto *RHSC = dyn_cast<ConstantInt>(Op->getOperand(1)))
4318 // If the RHS of the xor is a signmask, then this is just an add.
4319 // Instcombine turns add of signmask into xor as a strength reduction step.
4320 if (RHSC->getValue().isSignMask())
4321 return BinaryOp(Instruction::Add, Op->getOperand(0), Op->getOperand(1));
4322 return BinaryOp(Op);
4323
4324 case Instruction::LShr:
4325 // Turn logical shift right of a constant into a unsigned divide.
4326 if (ConstantInt *SA = dyn_cast<ConstantInt>(Op->getOperand(1))) {
4327 uint32_t BitWidth = cast<IntegerType>(Op->getType())->getBitWidth();
4328
4329 // If the shift count is not less than the bitwidth, the result of
4330 // the shift is undefined. Don't try to analyze it, because the
4331 // resolution chosen here may differ from the resolution chosen in
4332 // other parts of the compiler.
4333 if (SA->getValue().ult(BitWidth)) {
4334 Constant *X =
4335 ConstantInt::get(SA->getContext(),
4336 APInt::getOneBitSet(BitWidth, SA->getZExtValue()));
4337 return BinaryOp(Instruction::UDiv, Op->getOperand(0), X);
4338 }
4339 }
4340 return BinaryOp(Op);
4341
4342 case Instruction::ExtractValue: {
4343 auto *EVI = cast<ExtractValueInst>(Op);
23
'Op' is a 'ExtractValueInst'
4344 if (EVI->getNumIndices() != 1 || EVI->getIndices()[0] != 0)
24
Assuming the condition is false
25
Assuming the condition is false
26
Taking false branch
4345 break;
4346
4347 auto *WO = dyn_cast<WithOverflowInst>(EVI->getAggregateOperand());
4348 if (!WO)
27
Assuming 'WO' is non-null
28
Taking false branch
4349 break;
4350
4351 Instruction::BinaryOps BinOp = WO->getBinaryOp();
4352 bool Signed = WO->isSigned();
4353 // TODO: Should add nuw/nsw flags for mul as well.
4354 if (BinOp == Instruction::Mul || !isOverflowIntrinsicNoWrap(WO, DT))
29
Assuming 'BinOp' is not equal to Mul, which participates in a condition later
30
Assuming the condition is false
31
Taking false branch
4355 return BinaryOp(BinOp, WO->getLHS(), WO->getRHS());
4356
4357 // Now that we know that all uses of the arithmetic-result component of
4358 // CI are guarded by the overflow check, we can go ahead and pretend
4359 // that the arithmetic is non-overflowing.
4360 return BinaryOp(BinOp, WO->getLHS(), WO->getRHS(),
33
Calling constructor for 'Optional<(anonymous namespace)::BinaryOp>'
38
Returning from constructor for 'Optional<(anonymous namespace)::BinaryOp>'
4361 /* IsNSW = */ Signed, /* IsNUW = */ !Signed);
32
Assuming 'Signed' is true
4362 }
4363
4364 default:
4365 break;
4366 }
4367
4368 // Recognise intrinsic loop.decrement.reg, and as this has exactly the same
4369 // semantics as a Sub, return a binary sub expression.
4370 if (auto *II = dyn_cast<IntrinsicInst>(V))
4371 if (II->getIntrinsicID() == Intrinsic::loop_decrement_reg)
4372 return BinaryOp(Instruction::Sub, II->getOperand(0), II->getOperand(1));
4373
4374 return None;
4375}
4376
4377/// Helper function to createAddRecFromPHIWithCasts. We have a phi
4378/// node whose symbolic (unknown) SCEV is \p SymbolicPHI, which is updated via
4379/// the loop backedge by a SCEVAddExpr, possibly also with a few casts on the
4380/// way. This function checks if \p Op, an operand of this SCEVAddExpr,
4381/// follows one of the following patterns:
4382/// Op == (SExt ix (Trunc iy (%SymbolicPHI) to ix) to iy)
4383/// Op == (ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy)
4384/// If the SCEV expression of \p Op conforms with one of the expected patterns
4385/// we return the type of the truncation operation, and indicate whether the
4386/// truncated type should be treated as signed/unsigned by setting
4387/// \p Signed to true/false, respectively.
4388static Type *isSimpleCastedPHI(const SCEV *Op, const SCEVUnknown *SymbolicPHI,
4389 bool &Signed, ScalarEvolution &SE) {
4390 // The case where Op == SymbolicPHI (that is, with no type conversions on
4391 // the way) is handled by the regular add recurrence creating logic and
4392 // would have already been triggered in createAddRecForPHI. Reaching it here
4393 // means that createAddRecFromPHI had failed for this PHI before (e.g.,
4394 // because one of the other operands of the SCEVAddExpr updating this PHI is
4395 // not invariant).
4396 //
4397 // Here we look for the case where Op = (ext(trunc(SymbolicPHI))), and in
4398 // this case predicates that allow us to prove that Op == SymbolicPHI will
4399 // be added.
4400 if (Op == SymbolicPHI)
4401 return nullptr;
4402
4403 unsigned SourceBits = SE.getTypeSizeInBits(SymbolicPHI->getType());
4404 unsigned NewBits = SE.getTypeSizeInBits(Op->getType());
4405 if (SourceBits != NewBits)
4406 return nullptr;
4407
4408 const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(Op);
4409 const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(Op);
4410 if (!SExt && !ZExt)
4411 return nullptr;
4412 const SCEVTruncateExpr *Trunc =
4413 SExt ? dyn_cast<SCEVTruncateExpr>(SExt->getOperand())
4414 : dyn_cast<SCEVTruncateExpr>(ZExt->getOperand());
4415 if (!Trunc)
4416 return nullptr;
4417 const SCEV *X = Trunc->getOperand();
4418 if (X != SymbolicPHI)
4419 return nullptr;
4420 Signed = SExt != nullptr;
4421 return Trunc->getType();
4422}
4423
4424static const Loop *isIntegerLoopHeaderPHI(const PHINode *PN, LoopInfo &LI) {
4425 if (!PN->getType()->isIntegerTy())
4426 return nullptr;
4427 const Loop *L = LI.getLoopFor(PN->getParent());
4428 if (!L || L->getHeader() != PN->getParent())
4429 return nullptr;
4430 return L;
4431}
4432
4433// Analyze \p SymbolicPHI, a SCEV expression of a phi node, and check if the
4434// computation that updates the phi follows the following pattern:
4435// (SExt/ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy) + InvariantAccum
4436// which correspond to a phi->trunc->sext/zext->add->phi update chain.
4437// If so, try to see if it can be rewritten as an AddRecExpr under some
4438// Predicates. If successful, return them as a pair. Also cache the results
4439// of the analysis.
4440//
4441// Example usage scenario:
4442// Say the Rewriter is called for the following SCEV:
4443// 8 * ((sext i32 (trunc i64 %X to i32) to i64) + %Step)
4444// where:
4445// %X = phi i64 (%Start, %BEValue)
4446// It will visitMul->visitAdd->visitSExt->visitTrunc->visitUnknown(%X),
4447// and call this function with %SymbolicPHI = %X.
4448//
4449// The analysis will find that the value coming around the backedge has
4450// the following SCEV:
4451// BEValue = ((sext i32 (trunc i64 %X to i32) to i64) + %Step)
4452// Upon concluding that this matches the desired pattern, the function
4453// will return the pair {NewAddRec, SmallPredsVec} where:
4454// NewAddRec = {%Start,+,%Step}
4455// SmallPredsVec = {P1, P2, P3} as follows:
4456// P1(WrapPred): AR: {trunc(%Start),+,(trunc %Step)}<nsw> Flags: <nssw>
4457// P2(EqualPred): %Start == (sext i32 (trunc i64 %Start to i32) to i64)
4458// P3(EqualPred): %Step == (sext i32 (trunc i64 %Step to i32) to i64)
4459// The returned pair means that SymbolicPHI can be rewritten into NewAddRec
4460// under the predicates {P1,P2,P3}.
4461// This predicated rewrite will be cached in PredicatedSCEVRewrites:
4462// PredicatedSCEVRewrites[{%X,L}] = {NewAddRec, {P1,P2,P3)}
4463//
4464// TODO's:
4465//
4466// 1) Extend the Induction descriptor to also support inductions that involve
4467// casts: When needed (namely, when we are called in the context of the
4468// vectorizer induction analysis), a Set of cast instructions will be
4469// populated by this method, and provided back to isInductionPHI. This is
4470// needed to allow the vectorizer to properly record them to be ignored by
4471// the cost model and to avoid vectorizing them (otherwise these casts,
4472// which are redundant under the runtime overflow checks, will be
4473// vectorized, which can be costly).
4474//
4475// 2) Support additional induction/PHISCEV patterns: We also want to support
4476// inductions where the sext-trunc / zext-trunc operations (partly) occur
4477// after the induction update operation (the induction increment):
4478//
4479// (Trunc iy (SExt/ZExt ix (%SymbolicPHI + InvariantAccum) to iy) to ix)
4480// which correspond to a phi->add->trunc->sext/zext->phi update chain.
4481//
4482// (Trunc iy ((SExt/ZExt ix (%SymbolicPhi) to iy) + InvariantAccum) to ix)
4483// which correspond to a phi->trunc->add->sext/zext->phi update chain.
4484//
4485// 3) Outline common code with createAddRecFromPHI to avoid duplication.
4486Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4487ScalarEvolution::createAddRecFromPHIWithCastsImpl(const SCEVUnknown *SymbolicPHI) {
4488 SmallVector<const SCEVPredicate *, 3> Predicates;
4489
4490 // *** Part1: Analyze if we have a phi-with-cast pattern for which we can
4491 // return an AddRec expression under some predicate.
4492
4493 auto *PN = cast<PHINode>(SymbolicPHI->getValue());
4494 const Loop *L = isIntegerLoopHeaderPHI(PN, LI);
4495 assert(L && "Expecting an integer loop header phi")((L && "Expecting an integer loop header phi") ? static_cast
<void> (0) : __assert_fail ("L && \"Expecting an integer loop header phi\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4495, __PRETTY_FUNCTION__))
;
4496
4497 // The loop may have multiple entrances or multiple exits; we can analyze
4498 // this phi as an addrec if it has a unique entry value and a unique
4499 // backedge value.
4500 Value *BEValueV = nullptr, *StartValueV = nullptr;
4501 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
4502 Value *V = PN->getIncomingValue(i);
4503 if (L->contains(PN->getIncomingBlock(i))) {
4504 if (!BEValueV) {
4505 BEValueV = V;
4506 } else if (BEValueV != V) {
4507 BEValueV = nullptr;
4508 break;
4509 }
4510 } else if (!StartValueV) {
4511 StartValueV = V;
4512 } else if (StartValueV != V) {
4513 StartValueV = nullptr;
4514 break;
4515 }
4516 }
4517 if (!BEValueV || !StartValueV)
4518 return None;
4519
4520 const SCEV *BEValue = getSCEV(BEValueV);
4521
4522 // If the value coming around the backedge is an add with the symbolic
4523 // value we just inserted, possibly with casts that we can ignore under
4524 // an appropriate runtime guard, then we found a simple induction variable!
4525 const auto *Add = dyn_cast<SCEVAddExpr>(BEValue);
4526 if (!Add)
4527 return None;
4528
4529 // If there is a single occurrence of the symbolic value, possibly
4530 // casted, replace it with a recurrence.
4531 unsigned FoundIndex = Add->getNumOperands();
4532 Type *TruncTy = nullptr;
4533 bool Signed;
4534 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4535 if ((TruncTy =
4536 isSimpleCastedPHI(Add->getOperand(i), SymbolicPHI, Signed, *this)))
4537 if (FoundIndex == e) {
4538 FoundIndex = i;
4539 break;
4540 }
4541
4542 if (FoundIndex == Add->getNumOperands())
4543 return None;
4544
4545 // Create an add with everything but the specified operand.
4546 SmallVector<const SCEV *, 8> Ops;
4547 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4548 if (i != FoundIndex)
4549 Ops.push_back(Add->getOperand(i));
4550 const SCEV *Accum = getAddExpr(Ops);
4551
4552 // The runtime checks will not be valid if the step amount is
4553 // varying inside the loop.
4554 if (!isLoopInvariant(Accum, L))
4555 return None;
4556
4557 // *** Part2: Create the predicates
4558
4559 // Analysis was successful: we have a phi-with-cast pattern for which we
4560 // can return an AddRec expression under the following predicates:
4561 //
4562 // P1: A Wrap predicate that guarantees that Trunc(Start) + i*Trunc(Accum)
4563 // fits within the truncated type (does not overflow) for i = 0 to n-1.
4564 // P2: An Equal predicate that guarantees that
4565 // Start = (Ext ix (Trunc iy (Start) to ix) to iy)
4566 // P3: An Equal predicate that guarantees that
4567 // Accum = (Ext ix (Trunc iy (Accum) to ix) to iy)
4568 //
4569 // As we next prove, the above predicates guarantee that:
4570 // Start + i*Accum = (Ext ix (Trunc iy ( Start + i*Accum ) to ix) to iy)
4571 //
4572 //
4573 // More formally, we want to prove that:
4574 // Expr(i+1) = Start + (i+1) * Accum
4575 // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum
4576 //
4577 // Given that:
4578 // 1) Expr(0) = Start
4579 // 2) Expr(1) = Start + Accum
4580 // = (Ext ix (Trunc iy (Start) to ix) to iy) + Accum :: from P2
4581 // 3) Induction hypothesis (step i):
4582 // Expr(i) = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum
4583 //
4584 // Proof:
4585 // Expr(i+1) =
4586 // = Start + (i+1)*Accum
4587 // = (Start + i*Accum) + Accum
4588 // = Expr(i) + Accum
4589 // = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum + Accum
4590 // :: from step i
4591 //
4592 // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy) + Accum + Accum
4593 //
4594 // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy)
4595 // + (Ext ix (Trunc iy (Accum) to ix) to iy)
4596 // + Accum :: from P3
4597 //
4598 // = (Ext ix (Trunc iy ((Start + (i-1)*Accum) + Accum) to ix) to iy)
4599 // + Accum :: from P1: Ext(x)+Ext(y)=>Ext(x+y)
4600 //
4601 // = (Ext ix (Trunc iy (Start + i*Accum) to ix) to iy) + Accum
4602 // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum
4603 //
4604 // By induction, the same applies to all iterations 1<=i<n:
4605 //
4606
4607 // Create a truncated addrec for which we will add a no overflow check (P1).
4608 const SCEV *StartVal = getSCEV(StartValueV);
4609 const SCEV *PHISCEV =
4610 getAddRecExpr(getTruncateExpr(StartVal, TruncTy),
4611 getTruncateExpr(Accum, TruncTy), L, SCEV::FlagAnyWrap);
4612
4613 // PHISCEV can be either a SCEVConstant or a SCEVAddRecExpr.
4614 // ex: If truncated Accum is 0 and StartVal is a constant, then PHISCEV
4615 // will be constant.
4616 //
4617 // If PHISCEV is a constant, then P1 degenerates into P2 or P3, so we don't
4618 // add P1.
4619 if (const auto *AR = dyn_cast<SCEVAddRecExpr>(PHISCEV)) {
4620 SCEVWrapPredicate::IncrementWrapFlags AddedFlags =
4621 Signed ? SCEVWrapPredicate::IncrementNSSW
4622 : SCEVWrapPredicate::IncrementNUSW;
4623 const SCEVPredicate *AddRecPred = getWrapPredicate(AR, AddedFlags);
4624 Predicates.push_back(AddRecPred);
4625 }
4626
4627 // Create the Equal Predicates P2,P3:
4628
4629 // It is possible that the predicates P2 and/or P3 are computable at
4630 // compile time due to StartVal and/or Accum being constants.
4631 // If either one is, then we can check that now and escape if either P2
4632 // or P3 is false.
4633
4634 // Construct the extended SCEV: (Ext ix (Trunc iy (Expr) to ix) to iy)
4635 // for each of StartVal and Accum
4636 auto getExtendedExpr = [&](const SCEV *Expr,
4637 bool CreateSignExtend) -> const SCEV * {
4638 assert(isLoopInvariant(Expr, L) && "Expr is expected to be invariant")((isLoopInvariant(Expr, L) && "Expr is expected to be invariant"
) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Expr, L) && \"Expr is expected to be invariant\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4638, __PRETTY_FUNCTION__))
;
4639 const SCEV *TruncatedExpr = getTruncateExpr(Expr, TruncTy);
4640 const SCEV *ExtendedExpr =
4641 CreateSignExtend ? getSignExtendExpr(TruncatedExpr, Expr->getType())
4642 : getZeroExtendExpr(TruncatedExpr, Expr->getType());
4643 return ExtendedExpr;
4644 };
4645
4646 // Given:
4647 // ExtendedExpr = (Ext ix (Trunc iy (Expr) to ix) to iy
4648 // = getExtendedExpr(Expr)
4649 // Determine whether the predicate P: Expr == ExtendedExpr
4650 // is known to be false at compile time
4651 auto PredIsKnownFalse = [&](const SCEV *Expr,
4652 const SCEV *ExtendedExpr) -> bool {
4653 return Expr != ExtendedExpr &&
4654 isKnownPredicate(ICmpInst::ICMP_NE, Expr, ExtendedExpr);
4655 };
4656
4657 const SCEV *StartExtended = getExtendedExpr(StartVal, Signed);
4658 if (PredIsKnownFalse(StartVal, StartExtended)) {
4659 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)
;
4660 return None;
4661 }
4662
4663 // The Step is always Signed (because the overflow checks are either
4664 // NSSW or NUSW)
4665 const SCEV *AccumExtended = getExtendedExpr(Accum, /*CreateSignExtend=*/true);
4666 if (PredIsKnownFalse(Accum, AccumExtended)) {
4667 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)
;
4668 return None;
4669 }
4670
4671 auto AppendPredicate = [&](const SCEV *Expr,
4672 const SCEV *ExtendedExpr) -> void {
4673 if (Expr != ExtendedExpr &&
4674 !isKnownPredicate(ICmpInst::ICMP_EQ, Expr, ExtendedExpr)) {
4675 const SCEVPredicate *Pred = getEqualPredicate(Expr, ExtendedExpr);
4676 LLVM_DEBUG(dbgs() << "Added Predicate: " << *Pred)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "Added Predicate: " <<
*Pred; } } while (false)
;
4677 Predicates.push_back(Pred);
4678 }
4679 };
4680
4681 AppendPredicate(StartVal, StartExtended);
4682 AppendPredicate(Accum, AccumExtended);
4683
4684 // *** Part3: Predicates are ready. Now go ahead and create the new addrec in
4685 // which the casts had been folded away. The caller can rewrite SymbolicPHI
4686 // into NewAR if it will also add the runtime overflow checks specified in
4687 // Predicates.
4688 auto *NewAR = getAddRecExpr(StartVal, Accum, L, SCEV::FlagAnyWrap);
4689
4690 std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> PredRewrite =
4691 std::make_pair(NewAR, Predicates);
4692 // Remember the result of the analysis for this SCEV at this locayyytion.
4693 PredicatedSCEVRewrites[{SymbolicPHI, L}] = PredRewrite;
4694 return PredRewrite;
4695}
4696
4697Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4698ScalarEvolution::createAddRecFromPHIWithCasts(const SCEVUnknown *SymbolicPHI) {
4699 auto *PN = cast<PHINode>(SymbolicPHI->getValue());
4700 const Loop *L = isIntegerLoopHeaderPHI(PN, LI);
4701 if (!L)
4702 return None;
4703
4704 // Check to see if we already analyzed this PHI.
4705 auto I = PredicatedSCEVRewrites.find({SymbolicPHI, L});
4706 if (I != PredicatedSCEVRewrites.end()) {
4707 std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> Rewrite =
4708 I->second;
4709 // Analysis was done before and failed to create an AddRec:
4710 if (Rewrite.first == SymbolicPHI)
4711 return None;
4712 // Analysis was done before and succeeded to create an AddRec under
4713 // a predicate:
4714 assert(isa<SCEVAddRecExpr>(Rewrite.first) && "Expected an AddRec")((isa<SCEVAddRecExpr>(Rewrite.first) && "Expected an AddRec"
) ? static_cast<void> (0) : __assert_fail ("isa<SCEVAddRecExpr>(Rewrite.first) && \"Expected an AddRec\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4714, __PRETTY_FUNCTION__))
;
4715 assert(!(Rewrite.second).empty() && "Expected to find Predicates")((!(Rewrite.second).empty() && "Expected to find Predicates"
) ? static_cast<void> (0) : __assert_fail ("!(Rewrite.second).empty() && \"Expected to find Predicates\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4715, __PRETTY_FUNCTION__))
;
4716 return Rewrite;
4717 }
4718
4719 Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4720 Rewrite = createAddRecFromPHIWithCastsImpl(SymbolicPHI);
4721
4722 // Record in the cache that the analysis failed
4723 if (!Rewrite) {
4724 SmallVector<const SCEVPredicate *, 3> Predicates;
4725 PredicatedSCEVRewrites[{SymbolicPHI, L}] = {SymbolicPHI, Predicates};
4726 return None;
4727 }
4728
4729 return Rewrite;
4730}
4731
4732// FIXME: This utility is currently required because the Rewriter currently
4733// does not rewrite this expression:
4734// {0, +, (sext ix (trunc iy to ix) to iy)}
4735// into {0, +, %step},
4736// even when the following Equal predicate exists:
4737// "%step == (sext ix (trunc iy to ix) to iy)".
4738bool PredicatedScalarEvolution::areAddRecsEqualWithPreds(
4739 const SCEVAddRecExpr *AR1, const SCEVAddRecExpr *AR2) const {
4740 if (AR1 == AR2)
4741 return true;
4742
4743 auto areExprsEqual = [&](const SCEV *Expr1, const SCEV *Expr2) -> bool {
4744 if (Expr1 != Expr2 && !Preds.implies(SE.getEqualPredicate(Expr1, Expr2)) &&
4745 !Preds.implies(SE.getEqualPredicate(Expr2, Expr1)))
4746 return false;
4747 return true;
4748 };
4749
4750 if (!areExprsEqual(AR1->getStart(), AR2->getStart()) ||
4751 !areExprsEqual(AR1->getStepRecurrence(SE), AR2->getStepRecurrence(SE)))
4752 return false;
4753 return true;
4754}
4755
4756/// A helper function for createAddRecFromPHI to handle simple cases.
4757///
4758/// This function tries to find an AddRec expression for the simplest (yet most
4759/// common) cases: PN = PHI(Start, OP(Self, LoopInvariant)).
4760/// If it fails, createAddRecFromPHI will use a more general, but slow,
4761/// technique for finding the AddRec expression.
4762const SCEV *ScalarEvolution::createSimpleAffineAddRec(PHINode *PN,
4763 Value *BEValueV,
4764 Value *StartValueV) {
4765 const Loop *L = LI.getLoopFor(PN->getParent());
4766 assert(L && L->getHeader() == PN->getParent())((L && L->getHeader() == PN->getParent()) ? static_cast
<void> (0) : __assert_fail ("L && L->getHeader() == PN->getParent()"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4766, __PRETTY_FUNCTION__))
;
4767 assert(BEValueV && StartValueV)((BEValueV && StartValueV) ? static_cast<void> (
0) : __assert_fail ("BEValueV && StartValueV", "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4767, __PRETTY_FUNCTION__))
;
4768
4769 auto BO = MatchBinaryOp(BEValueV, DT);
4770 if (!BO)
4771 return nullptr;
4772
4773 if (BO->Opcode != Instruction::Add)
4774 return nullptr;
4775
4776 const SCEV *Accum = nullptr;
4777 if (BO->LHS == PN && L->isLoopInvariant(BO->RHS))
4778 Accum = getSCEV(BO->RHS);
4779 else if (BO->RHS == PN && L->isLoopInvariant(BO->LHS))
4780 Accum = getSCEV(BO->LHS);
4781
4782 if (!Accum)
4783 return nullptr;
4784
4785 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
4786 if (BO->IsNUW)
4787 Flags = setFlags(Flags, SCEV::FlagNUW);
4788 if (BO->IsNSW)
4789 Flags = setFlags(Flags, SCEV::FlagNSW);
4790
4791 const SCEV *StartVal = getSCEV(StartValueV);
4792 const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
4793
4794 ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV;
4795
4796 // We can add Flags to the post-inc expression only if we
4797 // know that it is *undefined behavior* for BEValueV to
4798 // overflow.
4799 if (auto *BEInst = dyn_cast<Instruction>(BEValueV))
4800 if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L))
4801 (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
4802
4803 return PHISCEV;
4804}
4805
4806const SCEV *ScalarEvolution::createAddRecFromPHI(PHINode *PN) {
4807 const Loop *L = LI.getLoopFor(PN->getParent());
4808 if (!L || L->getHeader() != PN->getParent())
4809 return nullptr;
4810
4811 // The loop may have multiple entrances or multiple exits; we can analyze
4812 // this phi as an addrec if it has a unique entry value and a unique
4813 // backedge value.
4814 Value *BEValueV = nullptr, *StartValueV = nullptr;
4815 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
4816 Value *V = PN->getIncomingValue(i);
4817 if (L->contains(PN->getIncomingBlock(i))) {
4818 if (!BEValueV) {
4819 BEValueV = V;
4820 } else if (BEValueV != V) {
4821 BEValueV = nullptr;
4822 break;
4823 }
4824 } else if (!StartValueV) {
4825 StartValueV = V;
4826 } else if (StartValueV != V) {
4827 StartValueV = nullptr;
4828 break;
4829 }
4830 }
4831 if (!BEValueV || !StartValueV)
4832 return nullptr;
4833
4834 assert(ValueExprMap.find_as(PN) == ValueExprMap.end() &&((ValueExprMap.find_as(PN) == ValueExprMap.end() && "PHI node already processed?"
) ? static_cast<void> (0) : __assert_fail ("ValueExprMap.find_as(PN) == ValueExprMap.end() && \"PHI node already processed?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4835, __PRETTY_FUNCTION__))
4835 "PHI node already processed?")((ValueExprMap.find_as(PN) == ValueExprMap.end() && "PHI node already processed?"
) ? static_cast<void> (0) : __assert_fail ("ValueExprMap.find_as(PN) == ValueExprMap.end() && \"PHI node already processed?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4835, __PRETTY_FUNCTION__))
;
4836
4837 // First, try to find AddRec expression without creating a fictituos symbolic
4838 // value for PN.
4839 if (auto *S = createSimpleAffineAddRec(PN, BEValueV, StartValueV))
4840 return S;
4841
4842 // Handle PHI node value symbolically.
4843 const SCEV *SymbolicName = getUnknown(PN);
4844 ValueExprMap.insert({SCEVCallbackVH(PN, this), SymbolicName});
4845
4846 // Using this symbolic name for the PHI, analyze the value coming around
4847 // the back-edge.
4848 const SCEV *BEValue = getSCEV(BEValueV);
4849
4850 // NOTE: If BEValue is loop invariant, we know that the PHI node just
4851 // has a special value for the first iteration of the loop.
4852
4853 // If the value coming around the backedge is an add with the symbolic
4854 // value we just inserted, then we found a simple induction variable!
4855 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(BEValue)) {
4856 // If there is a single occurrence of the symbolic value, replace it
4857 // with a recurrence.
4858 unsigned FoundIndex = Add->getNumOperands();
4859 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4860 if (Add->getOperand(i) == SymbolicName)
4861 if (FoundIndex == e) {
4862 FoundIndex = i;
4863 break;
4864 }
4865
4866 if (FoundIndex != Add->getNumOperands()) {
4867 // Create an add with everything but the specified operand.
4868 SmallVector<const SCEV *, 8> Ops;
4869 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4870 if (i != FoundIndex)
4871 Ops.push_back(SCEVBackedgeConditionFolder::rewrite(Add->getOperand(i),
4872 L, *this));
4873 const SCEV *Accum = getAddExpr(Ops);
4874
4875 // This is not a valid addrec if the step amount is varying each
4876 // loop iteration, but is not itself an addrec in this loop.
4877 if (isLoopInvariant(Accum, L) ||
4878 (isa<SCEVAddRecExpr>(Accum) &&
4879 cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) {
4880 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
4881
4882 if (auto BO = MatchBinaryOp(BEValueV, DT)) {
4883 if (BO->Opcode == Instruction::Add && BO->LHS == PN) {
4884 if (BO->IsNUW)
4885 Flags = setFlags(Flags, SCEV::FlagNUW);
4886 if (BO->IsNSW)
4887 Flags = setFlags(Flags, SCEV::FlagNSW);
4888 }
4889 } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(BEValueV)) {
4890 // If the increment is an inbounds GEP, then we know the address
4891 // space cannot be wrapped around. We cannot make any guarantee
4892 // about signed or unsigned overflow because pointers are
4893 // unsigned but we may have a negative index from the base
4894 // pointer. We can guarantee that no unsigned wrap occurs if the
4895 // indices form a positive value.
4896 if (GEP->isInBounds() && GEP->getOperand(0) == PN) {
4897 Flags = setFlags(Flags, SCEV::FlagNW);
4898
4899 const SCEV *Ptr = getSCEV(GEP->getPointerOperand());
4900 if (isKnownPositive(getMinusSCEV(getSCEV(GEP), Ptr)))
4901 Flags = setFlags(Flags, SCEV::FlagNUW);
4902 }
4903
4904 // We cannot transfer nuw and nsw flags from subtraction
4905 // operations -- sub nuw X, Y is not the same as add nuw X, -Y
4906 // for instance.
4907 }
4908
4909 const SCEV *StartVal = getSCEV(StartValueV);
4910 const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
4911
4912 // Okay, for the entire analysis of this edge we assumed the PHI
4913 // to be symbolic. We now need to go back and purge all of the
4914 // entries for the scalars that use the symbolic expression.
4915 forgetSymbolicName(PN, SymbolicName);
4916 ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV;
4917
4918 // We can add Flags to the post-inc expression only if we
4919 // know that it is *undefined behavior* for BEValueV to
4920 // overflow.
4921 if (auto *BEInst = dyn_cast<Instruction>(BEValueV))
4922 if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L))
4923 (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
4924
4925 return PHISCEV;
4926 }
4927 }
4928 } else {
4929 // Otherwise, this could be a loop like this:
4930 // i = 0; for (j = 1; ..; ++j) { .... i = j; }
4931 // In this case, j = {1,+,1} and BEValue is j.
4932 // Because the other in-value of i (0) fits the evolution of BEValue
4933 // i really is an addrec evolution.
4934 //
4935 // We can generalize this saying that i is the shifted value of BEValue
4936 // by one iteration:
4937 // PHI(f(0), f({1,+,1})) --> f({0,+,1})
4938 const SCEV *Shifted = SCEVShiftRewriter::rewrite(BEValue, L, *this);
4939 const SCEV *Start = SCEVInitRewriter::rewrite(Shifted, L, *this, false);
4940 if (Shifted != getCouldNotCompute() &&
4941 Start != getCouldNotCompute()) {
4942 const SCEV *StartVal = getSCEV(StartValueV);
4943 if (Start == StartVal) {
4944 // Okay, for the entire analysis of this edge we assumed the PHI
4945 // to be symbolic. We now need to go back and purge all of the
4946 // entries for the scalars that use the symbolic expression.
4947 forgetSymbolicName(PN, SymbolicName);
4948 ValueExprMap[SCEVCallbackVH(PN, this)] = Shifted;
4949 return Shifted;
4950 }
4951 }
4952 }
4953
4954 // Remove the temporary PHI node SCEV that has been inserted while intending
4955 // to create an AddRecExpr for this PHI node. We can not keep this temporary
4956 // as it will prevent later (possibly simpler) SCEV expressions to be added
4957 // to the ValueExprMap.
4958 eraseValueFromMap(PN);
4959
4960 return nullptr;
4961}
4962
4963// Checks if the SCEV S is available at BB. S is considered available at BB
4964// if S can be materialized at BB without introducing a fault.
4965static bool IsAvailableOnEntry(const Loop *L, DominatorTree &DT, const SCEV *S,
4966 BasicBlock *BB) {
4967 struct CheckAvailable {
4968 bool TraversalDone = false;
4969 bool Available = true;
4970
4971 const Loop *L = nullptr; // The loop BB is in (can be nullptr)
4972 BasicBlock *BB = nullptr;
4973 DominatorTree &DT;
4974
4975 CheckAvailable(const Loop *L, BasicBlock *BB, DominatorTree &DT)
4976 : L(L), BB(BB), DT(DT) {}
4977
4978 bool setUnavailable() {
4979 TraversalDone = true;
4980 Available = false;
4981 return false;
4982 }
4983
4984 bool follow(const SCEV *S) {
4985 switch (S->getSCEVType()) {
4986 case scConstant: case scTruncate: case scZeroExtend: case scSignExtend:
4987 case scAddExpr: case scMulExpr: case scUMaxExpr: case scSMaxExpr:
4988 case scUMinExpr:
4989 case scSMinExpr:
4990 // These expressions are available if their operand(s) is/are.
4991 return true;
4992
4993 case scAddRecExpr: {
4994 // We allow add recurrences that are on the loop BB is in, or some
4995 // outer loop. This guarantees availability because the value of the
4996 // add recurrence at BB is simply the "current" value of the induction
4997 // variable. We can relax this in the future; for instance an add
4998 // recurrence on a sibling dominating loop is also available at BB.
4999 const auto *ARLoop = cast<SCEVAddRecExpr>(S)->getLoop();
5000 if (L && (ARLoop == L || ARLoop->contains(L)))
5001 return true;
5002
5003 return setUnavailable();
5004 }
5005
5006 case scUnknown: {
5007 // For SCEVUnknown, we check for simple dominance.
5008 const auto *SU = cast<SCEVUnknown>(S);
5009 Value *V = SU->getValue();
5010
5011 if (isa<Argument>(V))
5012 return false;
5013
5014 if (isa<Instruction>(V) && DT.dominates(cast<Instruction>(V), BB))
5015 return false;
5016
5017 return setUnavailable();
5018 }
5019
5020 case scUDivExpr:
5021 case scCouldNotCompute:
5022 // We do not try to smart about these at all.
5023 return setUnavailable();
5024 }
5025 llvm_unreachable("switch should be fully covered!")::llvm::llvm_unreachable_internal("switch should be fully covered!"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5025)
;
5026 }
5027
5028 bool isDone() { return TraversalDone; }
5029 };
5030
5031 CheckAvailable CA(L, BB, DT);
5032 SCEVTraversal<CheckAvailable> ST(CA);
5033
5034 ST.visitAll(S);
5035 return CA.Available;
5036}
5037
5038// Try to match a control flow sequence that branches out at BI and merges back
5039// at Merge into a "C ? LHS : RHS" select pattern. Return true on a successful
5040// match.
5041static bool BrPHIToSelect(DominatorTree &DT, BranchInst *BI, PHINode *Merge,
5042 Value *&C, Value *&LHS, Value *&RHS) {
5043 C = BI->getCondition();
5044
5045 BasicBlockEdge LeftEdge(BI->getParent(), BI->getSuccessor(0));
5046 BasicBlockEdge RightEdge(BI->getParent(), BI->getSuccessor(1));
5047
5048 if (!LeftEdge.isSingleEdge())
5049 return false;
5050
5051 assert(RightEdge.isSingleEdge() && "Follows from LeftEdge.isSingleEdge()")((RightEdge.isSingleEdge() && "Follows from LeftEdge.isSingleEdge()"
) ? static_cast<void> (0) : __assert_fail ("RightEdge.isSingleEdge() && \"Follows from LeftEdge.isSingleEdge()\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5051, __PRETTY_FUNCTION__))
;
5052
5053 Use &LeftUse = Merge->getOperandUse(0);
5054 Use &RightUse = Merge->getOperandUse(1);
5055
5056 if (DT.dominates(LeftEdge, LeftUse) && DT.dominates(RightEdge, RightUse)) {
5057 LHS = LeftUse;
5058 RHS = RightUse;
5059 return true;
5060 }
5061
5062 if (DT.dominates(LeftEdge, RightUse) && DT.dominates(RightEdge, LeftUse)) {
5063 LHS = RightUse;
5064 RHS = LeftUse;
5065 return true;
5066 }
5067
5068 return false;
5069}
5070
5071const SCEV *ScalarEvolution::createNodeFromSelectLikePHI(PHINode *PN) {
5072 auto IsReachable =
5073 [&](BasicBlock *BB) { return DT.isReachableFromEntry(BB); };
5074 if (PN->getNumIncomingValues() == 2 && all_of(PN->blocks(), IsReachable)) {
5075 const Loop *L = LI.getLoopFor(PN->getParent());
5076
5077 // We don't want to break LCSSA, even in a SCEV expression tree.
5078 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
5079 if (LI.getLoopFor(PN->getIncomingBlock(i)) != L)
5080 return nullptr;
5081
5082 // Try to match
5083 //
5084 // br %cond, label %left, label %right
5085 // left:
5086 // br label %merge
5087 // right:
5088 // br label %merge
5089 // merge:
5090 // V = phi [ %x, %left ], [ %y, %right ]
5091 //
5092 // as "select %cond, %x, %y"
5093
5094 BasicBlock *IDom = DT[PN->getParent()]->getIDom()->getBlock();
5095 assert(IDom && "At least the entry block should dominate PN")((IDom && "At least the entry block should dominate PN"
) ? static_cast<void> (0) : __assert_fail ("IDom && \"At least the entry block should dominate PN\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5095, __PRETTY_FUNCTION__))
;
5096
5097 auto *BI = dyn_cast<BranchInst>(IDom->getTerminator());
5098 Value *Cond = nullptr, *LHS = nullptr, *RHS = nullptr;
5099
5100 if (BI && BI->isConditional() &&
5101 BrPHIToSelect(DT, BI, PN, Cond, LHS, RHS) &&
5102 IsAvailableOnEntry(L, DT, getSCEV(LHS), PN->getParent()) &&
5103 IsAvailableOnEntry(L, DT, getSCEV(RHS), PN->getParent()))
5104 return createNodeForSelectOrPHI(PN, Cond, LHS, RHS);
5105 }
5106
5107 return nullptr;
5108}
5109
5110const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) {
5111 if (const SCEV *S = createAddRecFromPHI(PN))
5112 return S;
5113
5114 if (const SCEV *S = createNodeFromSelectLikePHI(PN))
5115 return S;
5116
5117 // If the PHI has a single incoming value, follow that value, unless the
5118 // PHI's incoming blocks are in a different loop, in which case doing so
5119 // risks breaking LCSSA form. Instcombine would normally zap these, but
5120 // it doesn't have DominatorTree information, so it may miss cases.
5121 if (Value *V = SimplifyInstruction(PN, {getDataLayout(), &TLI, &DT, &AC}))
5122 if (LI.replacementPreservesLCSSAForm(PN, V))
5123 return getSCEV(V);
5124
5125 // If it's not a loop phi, we can't handle it yet.
5126 return getUnknown(PN);
5127}
5128
5129const SCEV *ScalarEvolution::createNodeForSelectOrPHI(Instruction *I,
5130 Value *Cond,
5131 Value *TrueVal,
5132 Value *FalseVal) {
5133 // Handle "constant" branch or select. This can occur for instance when a
5134 // loop pass transforms an inner loop and moves on to process the outer loop.
5135 if (auto *CI = dyn_cast<ConstantInt>(Cond))
5136 return getSCEV(CI->isOne() ? TrueVal : FalseVal);
5137
5138 // Try to match some simple smax or umax patterns.
5139 auto *ICI = dyn_cast<ICmpInst>(Cond);
5140 if (!ICI)
5141 return getUnknown(I);
5142
5143 Value *LHS = ICI->getOperand(0);
5144 Value *RHS = ICI->getOperand(1);
5145
5146 switch (ICI->getPredicate()) {
5147 case ICmpInst::ICMP_SLT:
5148 case ICmpInst::ICMP_SLE:
5149 std::swap(LHS, RHS);
5150 LLVM_FALLTHROUGH[[gnu::fallthrough]];
5151 case ICmpInst::ICMP_SGT:
5152 case ICmpInst::ICMP_SGE:
5153 // a >s b ? a+x : b+x -> smax(a, b)+x
5154 // a >s b ? b+x : a+x -> smin(a, b)+x
5155 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
5156 const SCEV *LS = getNoopOrSignExtend(getSCEV(LHS), I->getType());
5157 const SCEV *RS = getNoopOrSignExtend(getSCEV(RHS), I->getType());
5158 const SCEV *LA = getSCEV(TrueVal);
5159 const SCEV *RA = getSCEV(FalseVal);
5160 const SCEV *LDiff = getMinusSCEV(LA, LS);
5161 const SCEV *RDiff = getMinusSCEV(RA, RS);
5162 if (LDiff == RDiff)
5163 return getAddExpr(getSMaxExpr(LS, RS), LDiff);
5164 LDiff = getMinusSCEV(LA, RS);
5165 RDiff = getMinusSCEV(RA, LS);
5166 if (LDiff == RDiff)
5167 return getAddExpr(getSMinExpr(LS, RS), LDiff);
5168 }
5169 break;
5170 case ICmpInst::ICMP_ULT:
5171 case ICmpInst::ICMP_ULE:
5172 std::swap(LHS, RHS);
5173 LLVM_FALLTHROUGH[[gnu::fallthrough]];
5174 case ICmpInst::ICMP_UGT:
5175 case ICmpInst::ICMP_UGE:
5176 // a >u b ? a+x : b+x -> umax(a, b)+x
5177 // a >u b ? b+x : a+x -> umin(a, b)+x
5178 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
5179 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5180 const SCEV *RS = getNoopOrZeroExtend(getSCEV(RHS), I->getType());
5181 const SCEV *LA = getSCEV(TrueVal);
5182 const SCEV *RA = getSCEV(FalseVal);
5183 const SCEV *LDiff = getMinusSCEV(LA, LS);
5184 const SCEV *RDiff = getMinusSCEV(RA, RS);
5185 if (LDiff == RDiff)
5186 return getAddExpr(getUMaxExpr(LS, RS), LDiff);
5187 LDiff = getMinusSCEV(LA, RS);
5188 RDiff = getMinusSCEV(RA, LS);
5189 if (LDiff == RDiff)
5190 return getAddExpr(getUMinExpr(LS, RS), LDiff);
5191 }
5192 break;
5193 case ICmpInst::ICMP_NE:
5194 // n != 0 ? n+x : 1+x -> umax(n, 1)+x
5195 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
5196 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
5197 const SCEV *One = getOne(I->getType());
5198 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5199 const SCEV *LA = getSCEV(TrueVal);
5200 const SCEV *RA = getSCEV(FalseVal);
5201 const SCEV *LDiff = getMinusSCEV(LA, LS);
5202 const SCEV *RDiff = getMinusSCEV(RA, One);
5203 if (LDiff == RDiff)
5204 return getAddExpr(getUMaxExpr(One, LS), LDiff);
5205 }
5206 break;
5207 case ICmpInst::ICMP_EQ:
5208 // n == 0 ? 1+x : n+x -> umax(n, 1)+x
5209 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
5210 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
5211 const SCEV *One = getOne(I->getType());
5212 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5213 const SCEV *LA = getSCEV(TrueVal);
5214 const SCEV *RA = getSCEV(FalseVal);
5215 const SCEV *LDiff = getMinusSCEV(LA, One);
5216 const SCEV *RDiff = getMinusSCEV(RA, LS);
5217 if (LDiff == RDiff)
5218 return getAddExpr(getUMaxExpr(One, LS), LDiff);
5219 }
5220 break;
5221 default:
5222 break;
5223 }
5224
5225 return getUnknown(I);
5226}
5227
5228/// Expand GEP instructions into add and multiply operations. This allows them
5229/// to be analyzed by regular SCEV code.
5230const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) {
5231 // Don't attempt to analyze GEPs over unsized objects.
5232 if (!GEP->getSourceElementType()->isSized())
5233 return getUnknown(GEP);
5234
5235 SmallVector<const SCEV *, 4> IndexExprs;
5236 for (auto Index = GEP->idx_begin(); Index != GEP->idx_end(); ++Index)
5237 IndexExprs.push_back(getSCEV(*Index));
5238 return getGEPExpr(GEP, IndexExprs);
5239}
5240
5241uint32_t ScalarEvolution::GetMinTrailingZerosImpl(const SCEV *S) {
5242 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
5243 return C->getAPInt().countTrailingZeros();
5244
5245 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(S))
5246 return std::min(GetMinTrailingZeros(T->getOperand()),
5247 (uint32_t)getTypeSizeInBits(T->getType()));
5248
5249 if (const SCEVZeroExtendExpr *E = dyn_cast<SCEVZeroExtendExpr>(S)) {
5250 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
5251 return OpRes == getTypeSizeInBits(E->getOperand()->getType())
5252 ? getTypeSizeInBits(E->getType())
5253 : OpRes;
5254 }
5255
5256 if (const SCEVSignExtendExpr *E = dyn_cast<SCEVSignExtendExpr>(S)) {
5257 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
5258 return OpRes == getTypeSizeInBits(E->getOperand()->getType())
5259 ? getTypeSizeInBits(E->getType())
5260 : OpRes;
5261 }
5262
5263 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) {
5264 // The result is the min of all operands results.
5265 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
5266 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
5267 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
5268 return MinOpRes;
5269 }
5270
5271 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
5272 // The result is the sum of all operands results.
5273 uint32_t SumOpRes = GetMinTrailingZeros(M->getOperand(0));
5274 uint32_t BitWidth = getTypeSizeInBits(M->getType());
5275 for (unsigned i = 1, e = M->getNumOperands();
5276 SumOpRes != BitWidth && i != e; ++i)
5277 SumOpRes =
5278 std::min(SumOpRes + GetMinTrailingZeros(M->getOperand(i)), BitWidth);
5279 return SumOpRes;
5280 }
5281
5282 if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
5283 // The result is the min of all operands results.
5284 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
5285 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
5286 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
5287 return MinOpRes;
5288 }
5289
5290 if (const SCEVSMaxExpr *M = dyn_cast<SCEVSMaxExpr>(S)) {
5291 // The result is the min of all operands results.
5292 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
5293 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
5294 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
5295 return MinOpRes;
5296 }
5297
5298 if (const SCEVUMaxExpr *M = dyn_cast<SCEVUMaxExpr>(S)) {
5299 // The result is the min of all operands results.
5300 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
5301 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
5302 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
5303 return MinOpRes;
5304 }
5305
5306 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
5307 // For a SCEVUnknown, ask ValueTracking.
5308 KnownBits Known = computeKnownBits(U->getValue(), getDataLayout(), 0, &AC, nullptr, &DT);
5309 return Known.countMinTrailingZeros();
5310 }
5311
5312 // SCEVUDivExpr
5313 return 0;
5314}
5315
5316uint32_t ScalarEvolution::GetMinTrailingZeros(const SCEV *S) {
5317 auto I = MinTrailingZerosCache.find(S);
5318 if (I != MinTrailingZerosCache.end())
5319 return I->second;
5320
5321 uint32_t Result = GetMinTrailingZerosImpl(S);
5322 auto InsertPair = MinTrailingZerosCache.insert({S, Result});
5323 assert(InsertPair.second && "Should insert a new key")((InsertPair.second && "Should insert a new key") ? static_cast
<void> (0) : __assert_fail ("InsertPair.second && \"Should insert a new key\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5323, __PRETTY_FUNCTION__))
;
5324 return InsertPair.first->second;
5325}
5326
5327/// Helper method to assign a range to V from metadata present in the IR.
5328static Optional<ConstantRange> GetRangeFromMetadata(Value *V) {
5329 if (Instruction *I = dyn_cast<Instruction>(V))
5330 if (MDNode *MD = I->getMetadata(LLVMContext::MD_range))
5331 return getConstantRangeFromMetadata(*MD);
5332
5333 return None;
5334}
5335
5336/// Determine the range for a particular SCEV. If SignHint is
5337/// HINT_RANGE_UNSIGNED (resp. HINT_RANGE_SIGNED) then getRange prefers ranges
5338/// with a "cleaner" unsigned (resp. signed) representation.
5339const ConstantRange &
5340ScalarEvolution::getRangeRef(const SCEV *S,
5341 ScalarEvolution::RangeSignHint SignHint) {
5342 DenseMap<const SCEV *, ConstantRange> &Cache =
5343 SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED ? UnsignedRanges
5344 : SignedRanges;
5345 ConstantRange::PreferredRangeType RangeType =
5346 SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED
5347 ? ConstantRange::Unsigned : ConstantRange::Signed;
5348
5349 // See if we've computed this range already.
5350 DenseMap<const SCEV *, ConstantRange>::iterator I = Cache.find(S);
5351 if (I != Cache.end())
5352 return I->second;
5353
5354 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
5355 return setRange(C, SignHint, ConstantRange(C->getAPInt()));
5356
5357 unsigned BitWidth = getTypeSizeInBits(S->getType());
5358 ConstantRange ConservativeResult(BitWidth, /*isFullSet=*/true);
5359 using OBO = OverflowingBinaryOperator;
5360
5361 // If the value has known zeros, the maximum value will have those known zeros
5362 // as well.
5363 uint32_t TZ = GetMinTrailingZeros(S);
5364 if (TZ != 0) {
5365 if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED)
5366 ConservativeResult =
5367 ConstantRange(APInt::getMinValue(BitWidth),
5368 APInt::getMaxValue(BitWidth).lshr(TZ).shl(TZ) + 1);
5369 else
5370 ConservativeResult = ConstantRange(
5371 APInt::getSignedMinValue(BitWidth),
5372 APInt::getSignedMaxValue(BitWidth).ashr(TZ).shl(TZ) + 1);
5373 }
5374
5375 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
5376 ConstantRange X = getRangeRef(Add->getOperand(0), SignHint);
5377 unsigned WrapType = OBO::AnyWrap;
5378 if (Add->hasNoSignedWrap())
5379 WrapType |= OBO::NoSignedWrap;
5380 if (Add->hasNoUnsignedWrap())
5381 WrapType |= OBO::NoUnsignedWrap;
5382 for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i)
5383 X = X.addWithNoWrap(getRangeRef(Add->getOperand(i), SignHint),
5384 WrapType, RangeType);
5385 return setRange(Add, SignHint,
5386 ConservativeResult.intersectWith(X, RangeType));
5387 }
5388
5389 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
5390 ConstantRange X = getRangeRef(Mul->getOperand(0), SignHint);
5391 for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i)
5392 X = X.multiply(getRangeRef(Mul->getOperand(i), SignHint));
5393 return setRange(Mul, SignHint,
5394 ConservativeResult.intersectWith(X, RangeType));
5395 }
5396
5397 if (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(S)) {
5398 ConstantRange X = getRangeRef(SMax->getOperand(0), SignHint);
5399 for (unsigned i = 1, e = SMax->getNumOperands(); i != e; ++i)
5400 X = X.smax(getRangeRef(SMax->getOperand(i), SignHint));
5401 return setRange(SMax, SignHint,
5402 ConservativeResult.intersectWith(X, RangeType));
5403 }
5404
5405 if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) {
5406 ConstantRange X = getRangeRef(UMax->getOperand(0), SignHint);
5407 for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i)
5408 X = X.umax(getRangeRef(UMax->getOperand(i), SignHint));
5409 return setRange(UMax, SignHint,
5410 ConservativeResult.intersectWith(X, RangeType));
5411 }
5412
5413 if (const SCEVSMinExpr *SMin = dyn_cast<SCEVSMinExpr>(S)) {
5414 ConstantRange X = getRangeRef(SMin->getOperand(0), SignHint);
5415 for (unsigned i = 1, e = SMin->getNumOperands(); i != e; ++i)
5416 X = X.smin(getRangeRef(SMin->getOperand(i), SignHint));
5417 return setRange(SMin, SignHint,
5418 ConservativeResult.intersectWith(X, RangeType));
5419 }
5420
5421 if (const SCEVUMinExpr *UMin = dyn_cast<SCEVUMinExpr>(S)) {
5422 ConstantRange X = getRangeRef(UMin->getOperand(0), SignHint);
5423 for (unsigned i = 1, e = UMin->getNumOperands(); i != e; ++i)
5424 X = X.umin(getRangeRef(UMin->getOperand(i), SignHint));
5425 return setRange(UMin, SignHint,
5426 ConservativeResult.intersectWith(X, RangeType));
5427 }
5428
5429 if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) {
5430 ConstantRange X = getRangeRef(UDiv->getLHS(), SignHint);
5431 ConstantRange Y = getRangeRef(UDiv->getRHS(), SignHint);
5432 return setRange(UDiv, SignHint,
5433 ConservativeResult.intersectWith(X.udiv(Y), RangeType));
5434 }
5435
5436 if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) {
5437 ConstantRange X = getRangeRef(ZExt->getOperand(), SignHint);
5438 return setRange(ZExt, SignHint,
5439 ConservativeResult.intersectWith(X.zeroExtend(BitWidth),
5440 RangeType));
5441 }
5442
5443 if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) {
5444 ConstantRange X = getRangeRef(SExt->getOperand(), SignHint);
5445 return setRange(SExt, SignHint,
5446 ConservativeResult.intersectWith(X.signExtend(BitWidth),
5447 RangeType));
5448 }
5449
5450 if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) {
5451 ConstantRange X = getRangeRef(Trunc->getOperand(), SignHint);
5452 return setRange(Trunc, SignHint,
5453 ConservativeResult.intersectWith(X.truncate(BitWidth),
5454 RangeType));
5455 }
5456
5457 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) {
5458 // If there's no unsigned wrap, the value will never be less than its
5459 // initial value.
5460 if (AddRec->hasNoUnsignedWrap()) {
5461 APInt UnsignedMinValue = getUnsignedRangeMin(AddRec->getStart());
5462 if (!UnsignedMinValue.isNullValue())
5463 ConservativeResult = ConservativeResult.intersectWith(
5464 ConstantRange(UnsignedMinValue, APInt(BitWidth, 0)), RangeType);
5465 }
5466
5467 // If there's no signed wrap, and all the operands except initial value have
5468 // the same sign or zero, the value won't ever be:
5469 // 1: smaller than initial value if operands are non negative,
5470 // 2: bigger than initial value if operands are non positive.
5471 // For both cases, value can not cross signed min/max boundary.
5472 if (AddRec->hasNoSignedWrap()) {
5473 bool AllNonNeg = true;
5474 bool AllNonPos = true;
5475 for (unsigned i = 1, e = AddRec->getNumOperands(); i != e; ++i) {
5476 if (!isKnownNonNegative(AddRec->getOperand(i)))
5477 AllNonNeg = false;
5478 if (!isKnownNonPositive(AddRec->getOperand(i)))
5479 AllNonPos = false;
5480 }
5481 if (AllNonNeg)
5482 ConservativeResult = ConservativeResult.intersectWith(
5483 ConstantRange::getNonEmpty(getSignedRangeMin(AddRec->getStart()),
5484 APInt::getSignedMinValue(BitWidth)),
5485 RangeType);
5486 else if (AllNonPos)
5487 ConservativeResult = ConservativeResult.intersectWith(
5488 ConstantRange::getNonEmpty(
5489 APInt::getSignedMinValue(BitWidth),
5490 getSignedRangeMax(AddRec->getStart()) + 1),
5491 RangeType);
5492 }
5493
5494 // TODO: non-affine addrec
5495 if (AddRec->isAffine()) {
5496 const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(AddRec->getLoop());
5497 if (!isa<SCEVCouldNotCompute>(MaxBECount) &&
5498 getTypeSizeInBits(MaxBECount->getType()) <= BitWidth) {
5499 auto RangeFromAffine = getRangeForAffineAR(
5500 AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount,
5501 BitWidth);
5502 if (!RangeFromAffine.isFullSet())
5503 ConservativeResult =
5504 ConservativeResult.intersectWith(RangeFromAffine, RangeType);
5505
5506 auto RangeFromFactoring = getRangeViaFactoring(
5507 AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount,
5508 BitWidth);
5509 if (!RangeFromFactoring.isFullSet())
5510 ConservativeResult =
5511 ConservativeResult.intersectWith(RangeFromFactoring, RangeType);
5512 }
5513 }
5514
5515 return setRange(AddRec, SignHint, std::move(ConservativeResult));
5516 }
5517
5518 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
5519 // Check if the IR explicitly contains !range metadata.
5520 Optional<ConstantRange> MDRange = GetRangeFromMetadata(U->getValue());
5521 if (MDRange.hasValue())
5522 ConservativeResult = ConservativeResult.intersectWith(MDRange.getValue(),
5523 RangeType);
5524
5525 // Split here to avoid paying the compile-time cost of calling both
5526 // computeKnownBits and ComputeNumSignBits. This restriction can be lifted
5527 // if needed.
5528 const DataLayout &DL = getDataLayout();
5529 if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED) {
5530 // For a SCEVUnknown, ask ValueTracking.
5531 KnownBits Known = computeKnownBits(U->getValue(), DL, 0, &AC, nullptr, &DT);
5532 if (Known.getBitWidth() != BitWidth)
5533 Known = Known.zextOrTrunc(BitWidth);
5534 // If Known does not result in full-set, intersect with it.
5535 if (Known.getMinValue() != Known.getMaxValue() + 1)
5536 ConservativeResult = ConservativeResult.intersectWith(
5537 ConstantRange(Known.getMinValue(), Known.getMaxValue() + 1),
5538 RangeType);
5539 } else {
5540 assert(SignHint == ScalarEvolution::HINT_RANGE_SIGNED &&((SignHint == ScalarEvolution::HINT_RANGE_SIGNED && "generalize as needed!"
) ? static_cast<void> (0) : __assert_fail ("SignHint == ScalarEvolution::HINT_RANGE_SIGNED && \"generalize as needed!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5541, __PRETTY_FUNCTION__))
5541 "generalize as needed!")((SignHint == ScalarEvolution::HINT_RANGE_SIGNED && "generalize as needed!"
) ? static_cast<void> (0) : __assert_fail ("SignHint == ScalarEvolution::HINT_RANGE_SIGNED && \"generalize as needed!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5541, __PRETTY_FUNCTION__))
;
5542 unsigned NS = ComputeNumSignBits(U->getValue(), DL, 0, &AC, nullptr, &DT);
5543 // If the pointer size is larger than the index size type, this can cause
5544 // NS to be larger than BitWidth. So compensate for this.
5545 if (U->getType()->isPointerTy()) {
5546 unsigned ptrSize = DL.getPointerTypeSizeInBits(U->getType());
5547 int ptrIdxDiff = ptrSize - BitWidth;
5548 if (ptrIdxDiff > 0 && ptrSize > BitWidth && NS > (unsigned)ptrIdxDiff)
5549 NS -= ptrIdxDiff;
5550 }
5551
5552 if (NS > 1)
5553 ConservativeResult = ConservativeResult.intersectWith(
5554 ConstantRange(APInt::getSignedMinValue(BitWidth).ashr(NS - 1),
5555 APInt::getSignedMaxValue(BitWidth).ashr(NS - 1) + 1),
5556 RangeType);
5557 }
5558
5559 // A range of Phi is a subset of union of all ranges of its input.
5560 if (const PHINode *Phi = dyn_cast<PHINode>(U->getValue())) {
5561 // Make sure that we do not run over cycled Phis.
5562 if (PendingPhiRanges.insert(Phi).second) {
5563 ConstantRange RangeFromOps(BitWidth, /*isFullSet=*/false);
5564 for (auto &Op : Phi->operands()) {
5565 auto OpRange = getRangeRef(getSCEV(Op), SignHint);
5566 RangeFromOps = RangeFromOps.unionWith(OpRange);
5567 // No point to continue if we already have a full set.
5568 if (RangeFromOps.isFullSet())
5569 break;
5570 }
5571 ConservativeResult =
5572 ConservativeResult.intersectWith(RangeFromOps, RangeType);
5573 bool Erased = PendingPhiRanges.erase(Phi);
5574 assert(Erased && "Failed to erase Phi properly?")((Erased && "Failed to erase Phi properly?") ? static_cast
<void> (0) : __assert_fail ("Erased && \"Failed to erase Phi properly?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5574, __PRETTY_FUNCTION__))
;
5575 (void) Erased;
5576 }
5577 }
5578
5579 return setRange(U, SignHint, std::move(ConservativeResult));
5580 }
5581
5582 return setRange(S, SignHint, std::move(ConservativeResult));
5583}
5584
5585// Given a StartRange, Step and MaxBECount for an expression compute a range of
5586// values that the expression can take. Initially, the expression has a value
5587// from StartRange and then is changed by Step up to MaxBECount times. Signed
5588// argument defines if we treat Step as signed or unsigned.
5589static ConstantRange getRangeForAffineARHelper(APInt Step,
5590 const ConstantRange &StartRange,
5591 const APInt &MaxBECount,
5592 unsigned BitWidth, bool Signed) {
5593 // If either Step or MaxBECount is 0, then the expression won't change, and we
5594 // just need to return the initial range.
5595 if (Step == 0 || MaxBECount == 0)
5596 return StartRange;
5597
5598 // If we don't know anything about the initial value (i.e. StartRange is
5599 // FullRange), then we don't know anything about the final range either.
5600 // Return FullRange.
5601 if (StartRange.isFullSet())
5602 return ConstantRange::getFull(BitWidth);
5603
5604 // If Step is signed and negative, then we use its absolute value, but we also
5605 // note that we're moving in the opposite direction.
5606 bool Descending = Signed && Step.isNegative();
5607
5608 if (Signed)
5609 // This is correct even for INT_SMIN. Let's look at i8 to illustrate this:
5610 // abs(INT_SMIN) = abs(-128) = abs(0x80) = -0x80 = 0x80 = 128.
5611 // This equations hold true due to the well-defined wrap-around behavior of
5612 // APInt.
5613 Step = Step.abs();
5614
5615 // Check if Offset is more than full span of BitWidth. If it is, the
5616 // expression is guaranteed to overflow.
5617 if (APInt::getMaxValue(StartRange.getBitWidth()).udiv(Step).ult(MaxBECount))
5618 return ConstantRange::getFull(BitWidth);
5619
5620 // Offset is by how much the expression can change. Checks above guarantee no
5621 // overflow here.
5622 APInt Offset = Step * MaxBECount;
5623
5624 // Minimum value of the final range will match the minimal value of StartRange
5625 // if the expression is increasing and will be decreased by Offset otherwise.
5626 // Maximum value of the final range will match the maximal value of StartRange
5627 // if the expression is decreasing and will be increased by Offset otherwise.
5628 APInt StartLower = StartRange.getLower();
5629 APInt StartUpper = StartRange.getUpper() - 1;
5630 APInt MovedBoundary = Descending ? (StartLower - std::move(Offset))
5631 : (StartUpper + std::move(Offset));
5632
5633 // It's possible that the new minimum/maximum value will fall into the initial
5634 // range (due to wrap around). This means that the expression can take any
5635 // value in this bitwidth, and we have to return full range.
5636 if (StartRange.contains(MovedBoundary))
5637 return ConstantRange::getFull(BitWidth);
5638
5639 APInt NewLower =
5640 Descending ? std::move(MovedBoundary) : std::move(StartLower);
5641 APInt NewUpper =
5642 Descending ? std::move(StartUpper) : std::move(MovedBoundary);
5643 NewUpper += 1;
5644
5645 // No overflow detected, return [StartLower, StartUpper + Offset + 1) range.
5646 return ConstantRange::getNonEmpty(std::move(NewLower), std::move(NewUpper));
5647}
5648
5649ConstantRange ScalarEvolution::getRangeForAffineAR(const SCEV *Start,
5650 const SCEV *Step,
5651 const SCEV *MaxBECount,
5652 unsigned BitWidth) {
5653 assert(!isa<SCEVCouldNotCompute>(MaxBECount) &&((!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits
(MaxBECount->getType()) <= BitWidth && "Precondition!"
) ? static_cast<void> (0) : __assert_fail ("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5655, __PRETTY_FUNCTION__))
5654 getTypeSizeInBits(MaxBECount->getType()) <= BitWidth &&((!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits
(MaxBECount->getType()) <= BitWidth && "Precondition!"
) ? static_cast<void> (0) : __assert_fail ("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5655, __PRETTY_FUNCTION__))
5655 "Precondition!")((!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits
(MaxBECount->getType()) <= BitWidth && "Precondition!"
) ? static_cast<void> (0) : __assert_fail ("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5655, __PRETTY_FUNCTION__))
;
5656
5657 MaxBECount = getNoopOrZeroExtend(MaxBECount, Start->getType());
5658 APInt MaxBECountValue = getUnsignedRangeMax(MaxBECount);
5659
5660 // First, consider step signed.
5661 ConstantRange StartSRange = getSignedRange(Start);
5662 ConstantRange StepSRange = getSignedRange(Step);
5663
5664 // If Step can be both positive and negative, we need to find ranges for the
5665 // maximum absolute step values in both directions and union them.
5666 ConstantRange SR =
5667 getRangeForAffineARHelper(StepSRange.getSignedMin(), StartSRange,
5668 MaxBECountValue, BitWidth, /* Signed = */ true);
5669 SR = SR.unionWith(getRangeForAffineARHelper(StepSRange.getSignedMax(),
5670 StartSRange, MaxBECountValue,
5671 BitWidth, /* Signed = */ true));
5672
5673 // Next, consider step unsigned.
5674 ConstantRange UR = getRangeForAffineARHelper(
5675 getUnsignedRangeMax(Step), getUnsignedRange(Start),
5676 MaxBECountValue, BitWidth, /* Signed = */ false);
5677
5678 // Finally, intersect signed and unsigned ranges.
5679 return SR.intersectWith(UR, ConstantRange::Smallest);
5680}
5681
5682ConstantRange ScalarEvolution::getRangeViaFactoring(const SCEV *Start,
5683 const SCEV *Step,
5684 const SCEV *MaxBECount,
5685 unsigned BitWidth) {
5686 // RangeOf({C?A:B,+,C?P:Q}) == RangeOf(C?{A,+,P}:{B,+,Q})
5687 // == RangeOf({A,+,P}) union RangeOf({B,+,Q})
5688
5689 struct SelectPattern {
5690 Value *Condition = nullptr;
5691 APInt TrueValue;
5692 APInt FalseValue;
5693
5694 explicit SelectPattern(ScalarEvolution &SE, unsigned BitWidth,
5695 const SCEV *S) {
5696 Optional<unsigned> CastOp;
5697 APInt Offset(BitWidth, 0);
5698
5699 assert(SE.getTypeSizeInBits(S->getType()) == BitWidth &&((SE.getTypeSizeInBits(S->getType()) == BitWidth &&
"Should be!") ? static_cast<void> (0) : __assert_fail (
"SE.getTypeSizeInBits(S->getType()) == BitWidth && \"Should be!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5700, __PRETTY_FUNCTION__))
5700 "Should be!")((SE.getTypeSizeInBits(S->getType()) == BitWidth &&
"Should be!") ? static_cast<void> (0) : __assert_fail (
"SE.getTypeSizeInBits(S->getType()) == BitWidth && \"Should be!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5700, __PRETTY_FUNCTION__))
;
5701
5702 // Peel off a constant offset:
5703 if (auto *SA = dyn_cast<SCEVAddExpr>(S)) {
5704 // In the future we could consider being smarter here and handle
5705 // {Start+Step,+,Step} too.
5706 if (SA->getNumOperands() != 2 || !isa<SCEVConstant>(SA->getOperand(0)))
5707 return;
5708
5709 Offset = cast<SCEVConstant>(SA->getOperand(0))->getAPInt();
5710 S = SA->getOperand(1);
5711 }
5712
5713 // Peel off a cast operation
5714 if (auto *SCast = dyn_cast<SCEVCastExpr>(S)) {
5715 CastOp = SCast->getSCEVType();
5716 S = SCast->getOperand();
5717 }
5718
5719 using namespace llvm::PatternMatch;
5720
5721 auto *SU = dyn_cast<SCEVUnknown>(S);
5722 const APInt *TrueVal, *FalseVal;
5723 if (!SU ||
5724 !match(SU->getValue(), m_Select(m_Value(Condition), m_APInt(TrueVal),
5725 m_APInt(FalseVal)))) {
5726 Condition = nullptr;
5727 return;
5728 }
5729
5730 TrueValue = *TrueVal;
5731 FalseValue = *FalseVal;
5732
5733 // Re-apply the cast we peeled off earlier
5734 if (CastOp.hasValue())
5735 switch (*CastOp) {
5736 default:
5737 llvm_unreachable("Unknown SCEV cast type!")::llvm::llvm_unreachable_internal("Unknown SCEV cast type!", "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5737)
;
5738
5739 case scTruncate:
5740 TrueValue = TrueValue.trunc(BitWidth);
5741 FalseValue = FalseValue.trunc(BitWidth);
5742 break;
5743 case scZeroExtend:
5744 TrueValue = TrueValue.zext(BitWidth);
5745 FalseValue = FalseValue.zext(BitWidth);
5746 break;
5747 case scSignExtend:
5748 TrueValue = TrueValue.sext(BitWidth);
5749 FalseValue = FalseValue.sext(BitWidth);
5750 break;
5751 }
5752
5753 // Re-apply the constant offset we peeled off earlier
5754 TrueValue += Offset;
5755 FalseValue += Offset;
5756 }
5757
5758 bool isRecognized() { return Condition != nullptr; }
5759 };
5760
5761 SelectPattern StartPattern(*this, BitWidth, Start);
5762 if (!StartPattern.isRecognized())
5763 return ConstantRange::getFull(BitWidth);
5764
5765 SelectPattern StepPattern(*this, BitWidth, Step);
5766 if (!StepPattern.isRecognized())
5767 return ConstantRange::getFull(BitWidth);
5768
5769 if (StartPattern.Condition != StepPattern.Condition) {
5770 // We don't handle this case today; but we could, by considering four
5771 // possibilities below instead of two. I'm not sure if there are cases where
5772 // that will help over what getRange already does, though.
5773 return ConstantRange::getFull(BitWidth);
5774 }
5775
5776 // NB! Calling ScalarEvolution::getConstant is fine, but we should not try to
5777 // construct arbitrary general SCEV expressions here. This function is called
5778 // from deep in the call stack, and calling getSCEV (on a sext instruction,
5779 // say) can end up caching a suboptimal value.
5780
5781 // FIXME: without the explicit `this` receiver below, MSVC errors out with
5782 // C2352 and C2512 (otherwise it isn't needed).
5783
5784 const SCEV *TrueStart = this->getConstant(StartPattern.TrueValue);
5785 const SCEV *TrueStep = this->getConstant(StepPattern.TrueValue);
5786 const SCEV *FalseStart = this->getConstant(StartPattern.FalseValue);
5787 const SCEV *FalseStep = this->getConstant(StepPattern.FalseValue);
5788
5789 ConstantRange TrueRange =
5790 this->getRangeForAffineAR(TrueStart, TrueStep, MaxBECount, BitWidth);
5791 ConstantRange FalseRange =
5792 this->getRangeForAffineAR(FalseStart, FalseStep, MaxBECount, BitWidth);
5793
5794 return TrueRange.unionWith(FalseRange);
5795}
5796
5797SCEV::NoWrapFlags ScalarEvolution::getNoWrapFlagsFromUB(const Value *V) {
5798 if (isa<ConstantExpr>(V)) return SCEV::FlagAnyWrap;
5799 const BinaryOperator *BinOp = cast<BinaryOperator>(V);
5800
5801 // Return early if there are no flags to propagate to the SCEV.
5802 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
5803 if (BinOp->hasNoUnsignedWrap())
5804 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
5805 if (BinOp->hasNoSignedWrap())
5806 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
5807 if (Flags == SCEV::FlagAnyWrap)
5808 return SCEV::FlagAnyWrap;
5809
5810 return isSCEVExprNeverPoison(BinOp) ? Flags : SCEV::FlagAnyWrap;
5811}
5812
5813bool ScalarEvolution::isSCEVExprNeverPoison(const Instruction *I) {
5814 // Here we check that I is in the header of the innermost loop containing I,
5815 // since we only deal with instructions in the loop header. The actual loop we
5816 // need to check later will come from an add recurrence, but getting that
5817 // requires computing the SCEV of the operands, which can be expensive. This
5818 // check we can do cheaply to rule out some cases early.
5819 Loop *InnermostContainingLoop = LI.getLoopFor(I->getParent());
5820 if (InnermostContainingLoop == nullptr ||
5821 InnermostContainingLoop->getHeader() != I->getParent())
5822 return false;
5823
5824 // Only proceed if we can prove that I does not yield poison.
5825 if (!programUndefinedIfPoison(I))
5826 return false;
5827
5828 // At this point we know that if I is executed, then it does not wrap
5829 // according to at least one of NSW or NUW. If I is not executed, then we do
5830 // not know if the calculation that I represents would wrap. Multiple
5831 // instructions can map to the same SCEV. If we apply NSW or NUW from I to
5832 // the SCEV, we must guarantee no wrapping for that SCEV also when it is
5833 // derived from other instructions that map to the same SCEV. We cannot make
5834 // that guarantee for cases where I is not executed. So we need to find the
5835 // loop that I is considered in relation to and prove that I is executed for
5836 // every iteration of that loop. That implies that the value that I
5837 // calculates does not wrap anywhere in the loop, so then we can apply the
5838 // flags to the SCEV.
5839 //
5840 // We check isLoopInvariant to disambiguate in case we are adding recurrences
5841 // from different loops, so that we know which loop to prove that I is
5842 // executed in.
5843 for (unsigned OpIndex = 0; OpIndex < I->getNumOperands(); ++OpIndex) {
5844 // I could be an extractvalue from a call to an overflow intrinsic.
5845 // TODO: We can do better here in some cases.
5846 if (!isSCEVable(I->getOperand(OpIndex)->getType()))
5847 return false;
5848 const SCEV *Op = getSCEV(I->getOperand(OpIndex));
5849 if (auto *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
5850 bool AllOtherOpsLoopInvariant = true;
5851 for (unsigned OtherOpIndex = 0; OtherOpIndex < I->getNumOperands();
5852 ++OtherOpIndex) {
5853 if (OtherOpIndex != OpIndex) {
5854 const SCEV *OtherOp = getSCEV(I->getOperand(OtherOpIndex));
5855 if (!isLoopInvariant(OtherOp, AddRec->getLoop())) {
5856 AllOtherOpsLoopInvariant = false;
5857 break;
5858 }
5859 }
5860 }
5861 if (AllOtherOpsLoopInvariant &&
5862 isGuaranteedToExecuteForEveryIteration(I, AddRec->getLoop()))
5863 return true;
5864 }
5865 }
5866 return false;
5867}
5868
5869bool ScalarEvolution::isAddRecNeverPoison(const Instruction *I, const Loop *L) {
5870 // If we know that \c I can never be poison period, then that's enough.
5871 if (isSCEVExprNeverPoison(I))
5872 return true;
5873
5874 // For an add recurrence specifically, we assume that infinite loops without
5875 // side effects are undefined behavior, and then reason as follows:
5876 //
5877 // If the add recurrence is poison in any iteration, it is poison on all
5878 // future iterations (since incrementing poison yields poison). If the result
5879 // of the add recurrence is fed into the loop latch condition and the loop
5880 // does not contain any throws or exiting blocks other than the latch, we now
5881 // have the ability to "choose" whether the backedge is taken or not (by
5882 // choosing a sufficiently evil value for the poison feeding into the branch)
5883 // for every iteration including and after the one in which \p I first became
5884 // poison. There are two possibilities (let's call the iteration in which \p
5885 // I first became poison as K):
5886 //
5887 // 1. In the set of iterations including and after K, the loop body executes
5888 // no side effects. In this case executing the backege an infinte number
5889 // of times will yield undefined behavior.
5890 //
5891 // 2. In the set of iterations including and after K, the loop body executes
5892 // at least one side effect. In this case, that specific instance of side
5893 // effect is control dependent on poison, which also yields undefined
5894 // behavior.
5895
5896 auto *ExitingBB = L->getExitingBlock();
5897 auto *LatchBB = L->getLoopLatch();
5898 if (!ExitingBB || !LatchBB || ExitingBB != LatchBB)
5899 return false;
5900
5901 SmallPtrSet<const Instruction *, 16> Pushed;
5902 SmallVector<const Instruction *, 8> PoisonStack;
5903
5904 // We start by assuming \c I, the post-inc add recurrence, is poison. Only
5905 // things that are known to be poison under that assumption go on the
5906 // PoisonStack.
5907 Pushed.insert(I);
5908 PoisonStack.push_back(I);
5909
5910 bool LatchControlDependentOnPoison = false;
5911 while (!PoisonStack.empty() && !LatchControlDependentOnPoison) {
5912 const Instruction *Poison = PoisonStack.pop_back_val();
5913
5914 for (auto *PoisonUser : Poison->users()) {
5915 if (propagatesPoison(cast<Operator>(PoisonUser))) {
5916 if (Pushed.insert(cast<Instruction>(PoisonUser)).second)
5917 PoisonStack.push_back(cast<Instruction>(PoisonUser));
5918 } else if (auto *BI = dyn_cast<BranchInst>(PoisonUser)) {
5919 assert(BI->isConditional() && "Only possibility!")((BI->isConditional() && "Only possibility!") ? static_cast
<void> (0) : __assert_fail ("BI->isConditional() && \"Only possibility!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5919, __PRETTY_FUNCTION__))
;
5920 if (BI->getParent() == LatchBB) {
5921 LatchControlDependentOnPoison = true;
5922 break;
5923 }
5924 }
5925 }
5926 }
5927
5928 return LatchControlDependentOnPoison && loopHasNoAbnormalExits(L);
5929}
5930
5931ScalarEvolution::LoopProperties
5932ScalarEvolution::getLoopProperties(const Loop *L) {
5933 using LoopProperties = ScalarEvolution::LoopProperties;
5934
5935 auto Itr = LoopPropertiesCache.find(L);
5936 if (Itr == LoopPropertiesCache.end()) {
5937 auto HasSideEffects = [](Instruction *I) {
5938 if (auto *SI = dyn_cast<StoreInst>(I))
5939 return !SI->isSimple();
5940
5941 return I->mayHaveSideEffects();
5942 };
5943
5944 LoopProperties LP = {/* HasNoAbnormalExits */ true,
5945 /*HasNoSideEffects*/ true};
5946
5947 for (auto *BB : L->getBlocks())
5948 for (auto &I : *BB) {
5949 if (!isGuaranteedToTransferExecutionToSuccessor(&I))
5950 LP.HasNoAbnormalExits = false;
5951 if (HasSideEffects(&I))
5952 LP.HasNoSideEffects = false;
5953 if (!LP.HasNoAbnormalExits && !LP.HasNoSideEffects)
5954 break; // We're already as pessimistic as we can get.
5955 }
5956
5957 auto InsertPair = LoopPropertiesCache.insert({L, LP});
5958 assert(InsertPair.second && "We just checked!")((InsertPair.second && "We just checked!") ? static_cast
<void> (0) : __assert_fail ("InsertPair.second && \"We just checked!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5958, __PRETTY_FUNCTION__))
;
5959 Itr = InsertPair.first;
5960 }
5961
5962 return Itr->second;
5963}
5964
5965const SCEV *ScalarEvolution::createSCEV(Value *V) {
5966 if (!isSCEVable(V->getType()))
1
Calling 'ScalarEvolution::isSCEVable'
6
Returning from 'ScalarEvolution::isSCEVable'
7
Taking false branch
5967 return getUnknown(V);
5968
5969 if (Instruction *I
8.1
'I' is null
8.1
'I' is null
8.1
'I' is null
= dyn_cast<Instruction>(V)) {
8
Assuming 'V' is not a 'Instruction'
9
Taking false branch
5970 // Don't attempt to analyze instructions in blocks that aren't
5971 // reachable. Such instructions don't matter, and they aren't required
5972 // to obey basic rules for definitions dominating uses which this
5973 // analysis depends on.
5974 if (!DT.isReachableFromEntry(I->getParent()))
5975 return getUnknown(UndefValue::get(V->getType()));
5976 } else if (ConstantInt *CI
10.1
'CI' is null
10.1
'CI' is null
10.1
'CI' is null
= dyn_cast<ConstantInt>(V))
10
Assuming 'V' is not a 'ConstantInt'
11
Taking false branch
5977 return getConstant(CI);
5978 else if (isa<ConstantPointerNull>(V))
12
Assuming 'V' is not a 'ConstantPointerNull'
13
Taking false branch
5979 return getZero(V->getType());
5980 else if (GlobalAlias *GA
14.1
'GA' is null
14.1
'GA' is null
14.1
'GA' is null
= dyn_cast<GlobalAlias>(V))
14
Assuming 'V' is not a 'GlobalAlias'
15
Taking false branch
5981 return GA->isInterposable() ? getUnknown(V) : getSCEV(GA->getAliasee());
5982 else if (!isa<ConstantExpr>(V))
16
Assuming 'V' is a 'ConstantExpr'
17
Taking false branch
5983 return getUnknown(V);
5984
5985 Operator *U = cast<Operator>(V);
18
'V' is a 'Operator'
5986 if (auto BO = MatchBinaryOp(U, DT)) {
19
Calling 'MatchBinaryOp'
39
Returning from 'MatchBinaryOp'
40
Calling 'Optional::operator bool'
48
Returning from 'Optional::operator bool'
49
Taking true branch
5987 switch (BO->Opcode) {
50
Control jumps to 'case AShr:' at line 6219
5988 case Instruction::Add: {
5989 // The simple thing to do would be to just call getSCEV on both operands
5990 // and call getAddExpr with the result. However if we're looking at a
5991 // bunch of things all added together, this can be quite inefficient,
5992 // because it leads to N-1 getAddExpr calls for N ultimate operands.
5993 // Instead, gather up all the operands and make a single getAddExpr call.
5994 // LLVM IR canonical form means we need only traverse the left operands.
5995 SmallVector<const SCEV *, 4> AddOps;
5996 do {
5997 if (BO->Op) {
5998 if (auto *OpSCEV = getExistingSCEV(BO->Op)) {
5999 AddOps.push_back(OpSCEV);
6000 break;
6001 }
6002
6003 // If a NUW or NSW flag can be applied to the SCEV for this
6004 // addition, then compute the SCEV for this addition by itself
6005 // with a separate call to getAddExpr. We need to do that
6006 // instead of pushing the operands of the addition onto AddOps,
6007 // since the flags are only known to apply to this particular
6008 // addition - they may not apply to other additions that can be
6009 // formed with operands from AddOps.
6010 const SCEV *RHS = getSCEV(BO->RHS);
6011 SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op);
6012 if (Flags != SCEV::FlagAnyWrap) {
6013 const SCEV *LHS = getSCEV(BO->LHS);
6014 if (BO->Opcode == Instruction::Sub)
6015 AddOps.push_back(getMinusSCEV(LHS, RHS, Flags));
6016 else
6017 AddOps.push_back(getAddExpr(LHS, RHS, Flags));
6018 break;
6019 }
6020 }
6021
6022 if (BO->Opcode == Instruction::Sub)
6023 AddOps.push_back(getNegativeSCEV(getSCEV(BO->RHS)));
6024 else
6025 AddOps.push_back(getSCEV(BO->RHS));
6026
6027 auto NewBO = MatchBinaryOp(BO->LHS, DT);
6028 if (!NewBO || (NewBO->Opcode != Instruction::Add &&
6029 NewBO->Opcode != Instruction::Sub)) {
6030 AddOps.push_back(getSCEV(BO->LHS));
6031 break;
6032 }
6033 BO = NewBO;
6034 } while (true);
6035
6036 return getAddExpr(AddOps);
6037 }
6038
6039 case Instruction::Mul: {
6040 SmallVector<const SCEV *, 4> MulOps;
6041 do {
6042 if (BO->Op) {
6043 if (auto *OpSCEV = getExistingSCEV(BO->Op)) {
6044 MulOps.push_back(OpSCEV);
6045 break;
6046 }
6047
6048 SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op);
6049 if (Flags != SCEV::FlagAnyWrap) {
6050 MulOps.push_back(
6051 getMulExpr(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags));
6052 break;
6053 }
6054 }
6055
6056 MulOps.push_back(getSCEV(BO->RHS));
6057 auto NewBO = MatchBinaryOp(BO->LHS, DT);
6058 if (!NewBO || NewBO->Opcode != Instruction::Mul) {
6059 MulOps.push_back(getSCEV(BO->LHS));
6060 break;
6061 }
6062 BO = NewBO;
6063 } while (true);
6064
6065 return getMulExpr(MulOps);
6066 }
6067 case Instruction::UDiv:
6068 return getUDivExpr(getSCEV(BO->LHS), getSCEV(BO->RHS));
6069 case Instruction::URem:
6070 return getURemExpr(getSCEV(BO->LHS), getSCEV(BO->RHS));
6071 case Instruction::Sub: {
6072 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
6073 if (BO->Op)
6074 Flags = getNoWrapFlagsFromUB(BO->Op);
6075 return getMinusSCEV(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags);
6076 }
6077 case Instruction::And:
6078 // For an expression like x&255 that merely masks off the high bits,
6079 // use zext(trunc(x)) as the SCEV expression.
6080 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
6081 if (CI->isZero())
6082 return getSCEV(BO->RHS);
6083 if (CI->isMinusOne())
6084 return getSCEV(BO->LHS);
6085 const APInt &A = CI->getValue();
6086
6087 // Instcombine's ShrinkDemandedConstant may strip bits out of
6088 // constants, obscuring what would otherwise be a low-bits mask.
6089 // Use computeKnownBits to compute what ShrinkDemandedConstant
6090 // knew about to reconstruct a low-bits mask value.
6091 unsigned LZ = A.countLeadingZeros();
6092 unsigned TZ = A.countTrailingZeros();
6093 unsigned BitWidth = A.getBitWidth();
6094 KnownBits Known(BitWidth);
6095 computeKnownBits(BO->LHS, Known, getDataLayout(),
6096 0, &AC, nullptr, &DT);
6097
6098 APInt EffectiveMask =
6099 APInt::getLowBitsSet(BitWidth, BitWidth - LZ - TZ).shl(TZ);
6100 if ((LZ != 0 || TZ != 0) && !((~A & ~Known.Zero) & EffectiveMask)) {
6101 const SCEV *MulCount = getConstant(APInt::getOneBitSet(BitWidth, TZ));
6102 const SCEV *LHS = getSCEV(BO->LHS);
6103 const SCEV *ShiftedLHS = nullptr;
6104 if (auto *LHSMul = dyn_cast<SCEVMulExpr>(LHS)) {
6105 if (auto *OpC = dyn_cast<SCEVConstant>(LHSMul->getOperand(0))) {
6106 // For an expression like (x * 8) & 8, simplify the multiply.
6107 unsigned MulZeros = OpC->getAPInt().countTrailingZeros();
6108 unsigned GCD = std::min(MulZeros, TZ);
6109 APInt DivAmt = APInt::getOneBitSet(BitWidth, TZ - GCD);
6110 SmallVector<const SCEV*, 4> MulOps;
6111 MulOps.push_back(getConstant(OpC->getAPInt().lshr(GCD)));
6112 MulOps.append(LHSMul->op_begin() + 1, LHSMul->op_end());
6113 auto *NewMul = getMulExpr(MulOps, LHSMul->getNoWrapFlags());
6114 ShiftedLHS = getUDivExpr(NewMul, getConstant(DivAmt));
6115 }
6116 }
6117 if (!ShiftedLHS)
6118 ShiftedLHS = getUDivExpr(LHS, MulCount);
6119 return getMulExpr(
6120 getZeroExtendExpr(
6121 getTruncateExpr(ShiftedLHS,
6122 IntegerType::get(getContext(), BitWidth - LZ - TZ)),
6123 BO->LHS->getType()),
6124 MulCount);
6125 }
6126 }
6127 break;
6128
6129 case Instruction::Or:
6130 // If the RHS of the Or is a constant, we may have something like:
6131 // X*4+1 which got turned into X*4|1. Handle this as an Add so loop
6132 // optimizations will transparently handle this case.
6133 //
6134 // In order for this transformation to be safe, the LHS must be of the
6135 // form X*(2^n) and the Or constant must be less than 2^n.
6136 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
6137 const SCEV *LHS = getSCEV(BO->LHS);
6138 const APInt &CIVal = CI->getValue();
6139 if (GetMinTrailingZeros(LHS) >=
6140 (CIVal.getBitWidth() - CIVal.countLeadingZeros())) {
6141 // Build a plain add SCEV.
6142 return getAddExpr(LHS, getSCEV(CI),
6143 (SCEV::NoWrapFlags)(SCEV::FlagNUW | SCEV::FlagNSW));
6144 }
6145 }
6146 break;
6147
6148 case Instruction::Xor:
6149 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
6150 // If the RHS of xor is -1, then this is a not operation.
6151 if (CI->isMinusOne())
6152 return getNotSCEV(getSCEV(BO->LHS));
6153
6154 // Model xor(and(x, C), C) as and(~x, C), if C is a low-bits mask.
6155 // This is a variant of the check for xor with -1, and it handles
6156 // the case where instcombine has trimmed non-demanded bits out
6157 // of an xor with -1.
6158 if (auto *LBO = dyn_cast<BinaryOperator>(BO->LHS))
6159 if (ConstantInt *LCI = dyn_cast<ConstantInt>(LBO->getOperand(1)))
6160 if (LBO->getOpcode() == Instruction::And &&
6161 LCI->getValue() == CI->getValue())
6162 if (const SCEVZeroExtendExpr *Z =
6163 dyn_cast<SCEVZeroExtendExpr>(getSCEV(BO->LHS))) {
6164 Type *UTy = BO->LHS->getType();
6165 const SCEV *Z0 = Z->getOperand();
6166 Type *Z0Ty = Z0->getType();
6167 unsigned Z0TySize = getTypeSizeInBits(Z0Ty);
6168
6169 // If C is a low-bits mask, the zero extend is serving to
6170 // mask off the high bits. Complement the operand and
6171 // re-apply the zext.
6172 if (CI->getValue().isMask(Z0TySize))
6173 return getZeroExtendExpr(getNotSCEV(Z0), UTy);
6174
6175 // If C is a single bit, it may be in the sign-bit position
6176 // before the zero-extend. In this case, represent the xor
6177 // using an add, which is equivalent, and re-apply the zext.
6178 APInt Trunc = CI->getValue().trunc(Z0TySize);
6179 if (Trunc.zext(getTypeSizeInBits(UTy)) == CI->getValue() &&
6180 Trunc.isSignMask())
6181 return getZeroExtendExpr(getAddExpr(Z0, getConstant(Trunc)),
6182 UTy);
6183 }
6184 }
6185 break;
6186
6187 case Instruction::Shl:
6188 // Turn shift left of a constant amount into a multiply.
6189 if (ConstantInt *SA = dyn_cast<ConstantInt>(BO->RHS)) {
6190 uint32_t BitWidth = cast<IntegerType>(SA->getType())->getBitWidth();
6191
6192 // If the shift count is not less than the bitwidth, the result of
6193 // the shift is undefined. Don't try to analyze it, because the
6194 // resolution chosen here may differ from the resolution chosen in
6195 // other parts of the compiler.
6196 if (SA->getValue().uge(BitWidth))
6197 break;
6198
6199 // We can safely preserve the nuw flag in all cases. It's also safe to
6200 // turn a nuw nsw shl into a nuw nsw mul. However, nsw in isolation
6201 // requires special handling. It can be preserved as long as we're not
6202 // left shifting by bitwidth - 1.
6203 auto Flags = SCEV::FlagAnyWrap;
6204 if (BO->Op) {
6205 auto MulFlags = getNoWrapFlagsFromUB(BO->Op);
6206 if ((MulFlags & SCEV::FlagNSW) &&
6207 ((MulFlags & SCEV::FlagNUW) || SA->getValue().ult(BitWidth - 1)))
6208 Flags = (SCEV::NoWrapFlags)(Flags | SCEV::FlagNSW);
6209 if (MulFlags & SCEV::FlagNUW)
6210 Flags = (SCEV::NoWrapFlags)(Flags | SCEV::FlagNUW);
6211 }
6212
6213 Constant *X = ConstantInt::get(
6214 getContext(), APInt::getOneBitSet(BitWidth, SA->getZExtValue()));
6215 return getMulExpr(getSCEV(BO->LHS), getSCEV(X), Flags);
6216 }
6217 break;
6218
6219 case Instruction::AShr: {
6220 // AShr X, C, where C is a constant.
6221 ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS);
6222 if (!CI)
51
Assuming 'CI' is non-null
52
Taking false branch
6223 break;
6224
6225 Type *OuterTy = BO->LHS->getType();
53
Called C++ object pointer is null
6226 uint64_t BitWidth = getTypeSizeInBits(OuterTy);
6227 // If the shift count is not less than the bitwidth, the result of
6228 // the shift is undefined. Don't try to analyze it, because the
6229 // resolution chosen here may differ from the resolution chosen in
6230 // other parts of the compiler.
6231 if (CI->getValue().uge(BitWidth))
6232 break;
6233
6234 if (CI->isZero())
6235 return getSCEV(BO->LHS); // shift by zero --> noop
6236
6237 uint64_t AShrAmt = CI->getZExtValue();
6238 Type *TruncTy = IntegerType::get(getContext(), BitWidth - AShrAmt);
6239
6240 Operator *L = dyn_cast<Operator>(BO->LHS);
6241 if (L && L->getOpcode() == Instruction::Shl) {
6242 // X = Shl A, n
6243 // Y = AShr X, m
6244 // Both n and m are constant.
6245
6246 const SCEV *ShlOp0SCEV = getSCEV(L->getOperand(0));
6247 if (L->getOperand(1) == BO->RHS)
6248 // For a two-shift sext-inreg, i.e. n = m,
6249 // use sext(trunc(x)) as the SCEV expression.
6250 return getSignExtendExpr(
6251 getTruncateExpr(ShlOp0SCEV, TruncTy), OuterTy);
6252
6253 ConstantInt *ShlAmtCI = dyn_cast<ConstantInt>(L->getOperand(1));
6254 if (ShlAmtCI && ShlAmtCI->getValue().ult(BitWidth)) {
6255 uint64_t ShlAmt = ShlAmtCI->getZExtValue();
6256 if (ShlAmt > AShrAmt) {
6257 // When n > m, use sext(mul(trunc(x), 2^(n-m)))) as the SCEV
6258 // expression. We already checked that ShlAmt < BitWidth, so
6259 // the multiplier, 1 << (ShlAmt - AShrAmt), fits into TruncTy as
6260 // ShlAmt - AShrAmt < Amt.
6261 APInt Mul = APInt::getOneBitSet(BitWidth - AShrAmt,
6262 ShlAmt - AShrAmt);
6263 return getSignExtendExpr(
6264 getMulExpr(getTruncateExpr(ShlOp0SCEV, TruncTy),
6265 getConstant(Mul)), OuterTy);
6266 }
6267 }
6268 }
6269 break;
6270 }
6271 }
6272 }
6273
6274 switch (U->getOpcode()) {
6275 case Instruction::Trunc:
6276 return getTruncateExpr(getSCEV(U->getOperand(0)), U->getType());
6277
6278 case Instruction::ZExt:
6279 return getZeroExtendExpr(getSCEV(U->getOperand(0)), U->getType());
6280
6281 case Instruction::SExt:
6282 if (auto BO = MatchBinaryOp(U->getOperand(0), DT)) {
6283 // The NSW flag of a subtract does not always survive the conversion to
6284 // A + (-1)*B. By pushing sign extension onto its operands we are much
6285 // more likely to preserve NSW and allow later AddRec optimisations.
6286 //
6287 // NOTE: This is effectively duplicating this logic from getSignExtend:
6288 // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw>
6289 // but by that point the NSW information has potentially been lost.
6290 if (BO->Opcode == Instruction::Sub && BO->IsNSW) {
6291 Type *Ty = U->getType();
6292 auto *V1 = getSignExtendExpr(getSCEV(BO->LHS), Ty);
6293 auto *V2 = getSignExtendExpr(getSCEV(BO->RHS), Ty);
6294 return getMinusSCEV(V1, V2, SCEV::FlagNSW);
6295 }
6296 }
6297 return getSignExtendExpr(getSCEV(U->getOperand(0)), U->getType());
6298
6299 case Instruction::BitCast:
6300 // BitCasts are no-op casts so we just eliminate the cast.
6301 if (isSCEVable(U->getType()) && isSCEVable(U->getOperand(0)->getType()))
6302 return getSCEV(U->getOperand(0));
6303 break;
6304
6305 case Instruction::SDiv:
6306 // If both operands are non-negative, this is just an udiv.
6307 if (isKnownNonNegative(getSCEV(U->getOperand(0))) &&
6308 isKnownNonNegative(getSCEV(U->getOperand(1))))
6309 return getUDivExpr(getSCEV(U->getOperand(0)), getSCEV(U->getOperand(1)));
6310 break;
6311
6312 case Instruction::SRem:
6313 // If both operands are non-negative, this is just an urem.
6314 if (isKnownNonNegative(getSCEV(U->getOperand(0))) &&
6315 isKnownNonNegative(getSCEV(U->getOperand(1))))
6316 return getURemExpr(getSCEV(U->getOperand(0)), getSCEV(U->getOperand(1)));
6317 break;
6318
6319 // It's tempting to handle inttoptr and ptrtoint as no-ops, however this can
6320 // lead to pointer expressions which cannot safely be expanded to GEPs,
6321 // because ScalarEvolution doesn't respect the GEP aliasing rules when
6322 // simplifying integer expressions.
6323
6324 case Instruction::GetElementPtr:
6325 return createNodeForGEP(cast<GEPOperator>(U));
6326
6327 case Instruction::PHI:
6328 return createNodeForPHI(cast<PHINode>(U));
6329
6330 case Instruction::Select:
6331 // U can also be a select constant expr, which let fall through. Since
6332 // createNodeForSelect only works for a condition that is an `ICmpInst`, and
6333 // constant expressions cannot have instructions as operands, we'd have
6334 // returned getUnknown for a select constant expressions anyway.
6335 if (isa<Instruction>(U))
6336 return createNodeForSelectOrPHI(cast<Instruction>(U), U->getOperand(0),
6337 U->getOperand(1), U->getOperand(2));
6338 break;
6339
6340 case Instruction::Call:
6341 case Instruction::Invoke:
6342 if (Value *RV = cast<CallBase>(U)->getReturnedArgOperand())
6343 return getSCEV(RV);
6344
6345 if (auto *II = dyn_cast<IntrinsicInst>(U)) {
6346 switch (II->getIntrinsicID()) {
6347 case Intrinsic::umax:
6348 return getUMaxExpr(getSCEV(II->getArgOperand(0)),
6349 getSCEV(II->getArgOperand(1)));
6350 case Intrinsic::umin:
6351 return getUMinExpr(getSCEV(II->getArgOperand(0)),
6352 getSCEV(II->getArgOperand(1)));
6353 case Intrinsic::smax:
6354 return getSMaxExpr(getSCEV(II->getArgOperand(0)),
6355 getSCEV(II->getArgOperand(1)));
6356 case Intrinsic::smin:
6357 return getSMinExpr(getSCEV(II->getArgOperand(0)),
6358 getSCEV(II->getArgOperand(1)));
6359 default:
6360 break;
6361 }
6362 }
6363 break;
6364 }
6365
6366 return getUnknown(V);
6367}
6368
6369//===----------------------------------------------------------------------===//
6370// Iteration Count Computation Code
6371//
6372
6373static unsigned getConstantTripCount(const SCEVConstant *ExitCount) {
6374 if (!ExitCount)
6375 return 0;
6376
6377 ConstantInt *ExitConst = ExitCount->getValue();
6378
6379 // Guard against huge trip counts.
6380 if (ExitConst->getValue().getActiveBits() > 32)
6381 return 0;
6382
6383 // In case of integer overflow, this returns 0, which is correct.
6384 return ((unsigned)ExitConst->getZExtValue()) + 1;
6385}
6386
6387unsigned ScalarEvolution::getSmallConstantTripCount(const Loop *L) {
6388 if (BasicBlock *ExitingBB = L->getExitingBlock())
6389 return getSmallConstantTripCount(L, ExitingBB);
6390
6391 // No trip count information for multiple exits.
6392 return 0;
6393}
6394
6395unsigned
6396ScalarEvolution::getSmallConstantTripCount(const Loop *L,
6397 const BasicBlock *ExitingBlock) {
6398 assert(ExitingBlock && "Must pass a non-null exiting block!")((ExitingBlock && "Must pass a non-null exiting block!"
) ? static_cast<void> (0) : __assert_fail ("ExitingBlock && \"Must pass a non-null exiting block!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6398, __PRETTY_FUNCTION__))
;
6399 assert(L->isLoopExiting(ExitingBlock) &&((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!"
) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6400, __PRETTY_FUNCTION__))
6400 "Exiting block must actually branch out of the loop!")((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!"
) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6400, __PRETTY_FUNCTION__))
;
6401 const SCEVConstant *ExitCount =
6402 dyn_cast<SCEVConstant>(getExitCount(L, ExitingBlock));
6403 return getConstantTripCount(ExitCount);
6404}
6405
6406unsigned ScalarEvolution::getSmallConstantMaxTripCount(const Loop *L) {
6407 const auto *MaxExitCount =
6408 dyn_cast<SCEVConstant>(getConstantMaxBackedgeTakenCount(L));
6409 return getConstantTripCount(MaxExitCount);
6410}
6411
6412unsigned ScalarEvolution::getSmallConstantTripMultiple(const Loop *L) {
6413 if (BasicBlock *ExitingBB = L->getExitingBlock())
6414 return getSmallConstantTripMultiple(L, ExitingBB);
6415
6416 // No trip multiple information for multiple exits.
6417 return 0;
6418}
6419
6420/// Returns the largest constant divisor of the trip count of this loop as a
6421/// normal unsigned value, if possible. This means that the actual trip count is
6422/// always a multiple of the returned value (don't forget the trip count could
6423/// very well be zero as well!).
6424///
6425/// Returns 1 if the trip count is unknown or not guaranteed to be the
6426/// multiple of a constant (which is also the case if the trip count is simply
6427/// constant, use getSmallConstantTripCount for that case), Will also return 1
6428/// if the trip count is very large (>= 2^32).
6429///
6430/// As explained in the comments for getSmallConstantTripCount, this assumes
6431/// that control exits the loop via ExitingBlock.
6432unsigned
6433ScalarEvolution::getSmallConstantTripMultiple(const Loop *L,
6434 const BasicBlock *ExitingBlock) {
6435 assert(ExitingBlock && "Must pass a non-null exiting block!")((ExitingBlock && "Must pass a non-null exiting block!"
) ? static_cast<void> (0) : __assert_fail ("ExitingBlock && \"Must pass a non-null exiting block!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6435, __PRETTY_FUNCTION__))
;
6436 assert(L->isLoopExiting(ExitingBlock) &&((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!"
) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6437, __PRETTY_FUNCTION__))
6437 "Exiting block must actually branch out of the loop!")((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!"
) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6437, __PRETTY_FUNCTION__))
;
6438 const SCEV *ExitCount = getExitCount(L, ExitingBlock);
6439 if (ExitCount == getCouldNotCompute())
6440 return 1;
6441
6442 // Get the trip count from the BE count by adding 1.
6443 const SCEV *TCExpr = getAddExpr(ExitCount, getOne(ExitCount->getType()));
6444
6445 const SCEVConstant *TC = dyn_cast<SCEVConstant>(TCExpr);
6446 if (!TC)
6447 // Attempt to factor more general cases. Returns the greatest power of
6448 // two divisor. If overflow happens, the trip count expression is still
6449 // divisible by the greatest power of 2 divisor returned.
6450 return 1U << std::min((uint32_t)31, GetMinTrailingZeros(TCExpr));
6451
6452 ConstantInt *Result = TC->getValue();
6453
6454 // Guard against huge trip counts (this requires checking
6455 // for zero to handle the case where the trip count == -1 and the
6456 // addition wraps).
6457 if (!Result || Result->getValue().getActiveBits() > 32 ||
6458 Result->getValue().getActiveBits() == 0)
6459 return 1;
6460
6461 return (unsigned)Result->getZExtValue();
6462}
6463
6464const SCEV *ScalarEvolution::getExitCount(const Loop *L,
6465 const BasicBlock *ExitingBlock,
6466 ExitCountKind Kind) {
6467 switch (Kind) {
6468 case Exact:
6469 return getBackedgeTakenInfo(L).getExact(ExitingBlock, this);
6470 case ConstantMaximum:
6471 return getBackedgeTakenInfo(L).getMax(ExitingBlock, this);
6472 };
6473 llvm_unreachable("Invalid ExitCountKind!")::llvm::llvm_unreachable_internal("Invalid ExitCountKind!", "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6473)
;
6474}
6475
6476const SCEV *
6477ScalarEvolution::getPredicatedBackedgeTakenCount(const Loop *L,
6478 SCEVUnionPredicate &Preds) {
6479 return getPredicatedBackedgeTakenInfo(L).getExact(L, this, &Preds);
6480}
6481
6482const SCEV *ScalarEvolution::getBackedgeTakenCount(const Loop *L,
6483 ExitCountKind Kind) {
6484 switch (Kind) {
6485 case Exact:
6486 return getBackedgeTakenInfo(L).getExact(L, this);
6487 case ConstantMaximum:
6488 return getBackedgeTakenInfo(L).getMax(this);
6489 };
6490 llvm_unreachable("Invalid ExitCountKind!")::llvm::llvm_unreachable_internal("Invalid ExitCountKind!", "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6490)
;
6491}
6492
6493bool ScalarEvolution::isBackedgeTakenCountMaxOrZero(const Loop *L) {
6494 return getBackedgeTakenInfo(L).isMaxOrZero(this);
6495}
6496
6497/// Push PHI nodes in the header of the given loop onto the given Worklist.
6498static void
6499PushLoopPHIs(const Loop *L, SmallVectorImpl<Instruction *> &Worklist) {
6500 BasicBlock *Header = L->getHeader();
6501
6502 // Push all Loop-header PHIs onto the Worklist stack.
6503 for (PHINode &PN : Header->phis())
6504 Worklist.push_back(&PN);
6505}
6506
6507const ScalarEvolution::BackedgeTakenInfo &
6508ScalarEvolution::getPredicatedBackedgeTakenInfo(const Loop *L) {
6509 auto &BTI = getBackedgeTakenInfo(L);
6510 if (BTI.hasFullInfo())
6511 return BTI;
6512
6513 auto Pair = PredicatedBackedgeTakenCounts.insert({L, BackedgeTakenInfo()});
6514
6515 if (!Pair.second)
6516 return Pair.first->second;
6517
6518 BackedgeTakenInfo Result =
6519 computeBackedgeTakenCount(L, /*AllowPredicates=*/true);
6520
6521 return PredicatedBackedgeTakenCounts.find(L)->second = std::move(Result);
6522}
6523
6524const ScalarEvolution::BackedgeTakenInfo &
6525ScalarEvolution::getBackedgeTakenInfo(const Loop *L) {
6526 // Initially insert an invalid entry for this loop. If the insertion
6527 // succeeds, proceed to actually compute a backedge-taken count and
6528 // update the value. The temporary CouldNotCompute value tells SCEV
6529 // code elsewhere that it shouldn't attempt to request a new
6530 // backedge-taken count, which could result in infinite recursion.
6531 std::pair<DenseMap<const Loop *, BackedgeTakenInfo>::iterator, bool> Pair =
6532 BackedgeTakenCounts.insert({L, BackedgeTakenInfo()});
6533 if (!Pair.second)
6534 return Pair.first->second;
6535
6536 // computeBackedgeTakenCount may allocate memory for its result. Inserting it
6537 // into the BackedgeTakenCounts map transfers ownership. Otherwise, the result
6538 // must be cleared in this scope.
6539 BackedgeTakenInfo Result = computeBackedgeTakenCount(L);
6540
6541 // In product build, there are no usage of statistic.
6542 (void)NumTripCountsComputed;
6543 (void)NumTripCountsNotComputed;
6544#if LLVM_ENABLE_STATS1 || !defined(NDEBUG)
6545 const SCEV *BEExact = Result.getExact(L, this);
6546 if (BEExact != getCouldNotCompute()) {
6547 assert(isLoopInvariant(BEExact, L) &&((isLoopInvariant(BEExact, L) && isLoopInvariant(Result
.getMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!"
) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(BEExact, L) && isLoopInvariant(Result.getMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6549, __PRETTY_FUNCTION__))
6548 isLoopInvariant(Result.getMax(this), L) &&((isLoopInvariant(BEExact, L) && isLoopInvariant(Result
.getMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!"
) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(BEExact, L) && isLoopInvariant(Result.getMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6549, __PRETTY_FUNCTION__))
6549 "Computed backedge-taken count isn't loop invariant for loop!")((isLoopInvariant(BEExact, L) && isLoopInvariant(Result
.getMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!"
) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(BEExact, L) && isLoopInvariant(Result.getMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6549, __PRETTY_FUNCTION__))
;
6550 ++NumTripCountsComputed;
6551 }
6552 else if (Result.getMax(this) == getCouldNotCompute() &&
6553 isa<PHINode>(L->getHeader()->begin())) {
6554 // Only count loops that have phi nodes as not being computable.
6555 ++NumTripCountsNotComputed;
6556 }
6557#endif // LLVM_ENABLE_STATS || !defined(NDEBUG)
6558
6559 // Now that we know more about the trip count for this loop, forget any
6560 // existing SCEV values for PHI nodes in this loop since they are only
6561 // conservative estimates made without the benefit of trip count
6562 // information. This is similar to the code in forgetLoop, except that
6563 // it handles SCEVUnknown PHI nodes specially.
6564 if (Result.hasAnyInfo()) {
6565 SmallVector<Instruction *, 16> Worklist;
6566 PushLoopPHIs(L, Worklist);
6567
6568 SmallPtrSet<Instruction *, 8> Discovered;
6569 while (!Worklist.empty()) {
6570 Instruction *I = Worklist.pop_back_val();
6571
6572 ValueExprMapType::iterator It =
6573 ValueExprMap.find_as(static_cast<Value *>(I));
6574 if (It != ValueExprMap.end()) {
6575 const SCEV *Old = It->second;
6576
6577 // SCEVUnknown for a PHI either means that it has an unrecognized
6578 // structure, or it's a PHI that's in the progress of being computed
6579 // by createNodeForPHI. In the former case, additional loop trip
6580 // count information isn't going to change anything. In the later
6581 // case, createNodeForPHI will perform the necessary updates on its
6582 // own when it gets to that point.
6583 if (!isa<PHINode>(I) || !isa<SCEVUnknown>(Old)) {
6584 eraseValueFromMap(It->first);
6585 forgetMemoizedResults(Old);
6586 }
6587 if (PHINode *PN = dyn_cast<PHINode>(I))
6588 ConstantEvolutionLoopExitValue.erase(PN);
6589 }
6590
6591 // Since we don't need to invalidate anything for correctness and we're
6592 // only invalidating to make SCEV's results more precise, we get to stop
6593 // early to avoid invalidating too much. This is especially important in
6594 // cases like:
6595 //
6596 // %v = f(pn0, pn1) // pn0 and pn1 used through some other phi node
6597 // loop0:
6598 // %pn0 = phi
6599 // ...
6600 // loop1:
6601 // %pn1 = phi
6602 // ...
6603 //
6604 // where both loop0 and loop1's backedge taken count uses the SCEV
6605 // expression for %v. If we don't have the early stop below then in cases
6606 // like the above, getBackedgeTakenInfo(loop1) will clear out the trip
6607 // count for loop0 and getBackedgeTakenInfo(loop0) will clear out the trip
6608 // count for loop1, effectively nullifying SCEV's trip count cache.
6609 for (auto *U : I->users())
6610 if (auto *I = dyn_cast<Instruction>(U)) {
6611 auto *LoopForUser = LI.getLoopFor(I->getParent());
6612 if (LoopForUser && L->contains(LoopForUser) &&
6613 Discovered.insert(I).second)
6614 Worklist.push_back(I);
6615 }
6616 }
6617 }
6618
6619 // Re-lookup the insert position, since the call to
6620 // computeBackedgeTakenCount above could result in a
6621 // recusive call to getBackedgeTakenInfo (on a different
6622 // loop), which would invalidate the iterator computed
6623 // earlier.
6624 return BackedgeTakenCounts.find(L)->second = std::move(Result);
6625}
6626
6627void ScalarEvolution::forgetAllLoops() {
6628 // This method is intended to forget all info about loops. It should
6629 // invalidate caches as if the following happened:
6630 // - The trip counts of all loops have changed arbitrarily
6631 // - Every llvm::Value has been updated in place to produce a different
6632 // result.
6633 BackedgeTakenCounts.clear();
6634 PredicatedBackedgeTakenCounts.clear();
6635 LoopPropertiesCache.clear();
6636 ConstantEvolutionLoopExitValue.clear();
6637 ValueExprMap.clear();
6638 ValuesAtScopes.clear();
6639 LoopDispositions.clear();
6640 BlockDispositions.clear();
6641 UnsignedRanges.clear();
6642 SignedRanges.clear();
6643 ExprValueMap.clear();
6644 HasRecMap.clear();
6645 MinTrailingZerosCache.clear();
6646 PredicatedSCEVRewrites.clear();
6647}
6648
6649void ScalarEvolution::forgetLoop(const Loop *L) {
6650 // Drop any stored trip count value.
6651 auto RemoveLoopFromBackedgeMap =
6652 [](DenseMap<const Loop *, BackedgeTakenInfo> &Map, const Loop *L) {
6653 auto BTCPos = Map.find(L);
6654 if (BTCPos != Map.end()) {
6655 BTCPos->second.clear();
6656 Map.erase(BTCPos);
6657 }
6658 };
6659
6660 SmallVector<const Loop *, 16> LoopWorklist(1, L);
6661 SmallVector<Instruction *, 32> Worklist;
6662 SmallPtrSet<Instruction *, 16> Visited;
6663
6664 // Iterate over all the loops and sub-loops to drop SCEV information.
6665 while (!LoopWorklist.empty()) {
6666 auto *CurrL = LoopWorklist.pop_back_val();
6667
6668 RemoveLoopFromBackedgeMap(BackedgeTakenCounts, CurrL);
6669 RemoveLoopFromBackedgeMap(PredicatedBackedgeTakenCounts, CurrL);
6670
6671 // Drop information about predicated SCEV rewrites for this loop.
6672 for (auto I = PredicatedSCEVRewrites.begin();
6673 I != PredicatedSCEVRewrites.end();) {
6674 std::pair<const SCEV *, const Loop *> Entry = I->first;
6675 if (Entry.second == CurrL)
6676 PredicatedSCEVRewrites.erase(I++);
6677 else
6678 ++I;
6679 }
6680
6681 auto LoopUsersItr = LoopUsers.find(CurrL);
6682 if (LoopUsersItr != LoopUsers.end()) {
6683 for (auto *S : LoopUsersItr->second)
6684 forgetMemoizedResults(S);
6685 LoopUsers.erase(LoopUsersItr);
6686 }
6687
6688 // Drop information about expressions based on loop-header PHIs.
6689 PushLoopPHIs(CurrL, Worklist);
6690
6691 while (!Worklist.empty()) {
6692 Instruction *I = Worklist.pop_back_val();
6693 if (!Visited.insert(I).second)
6694 continue;
6695
6696 ValueExprMapType::iterator It =
6697 ValueExprMap.find_as(static_cast<Value *>(I));
6698 if (It != ValueExprMap.end()) {
6699 eraseValueFromMap(It->first);
6700 forgetMemoizedResults(It->second);
6701 if (PHINode *PN = dyn_cast<PHINode>(I))
6702 ConstantEvolutionLoopExitValue.erase(PN);
6703 }
6704
6705 PushDefUseChildren(I, Worklist);
6706 }
6707
6708 LoopPropertiesCache.erase(CurrL);
6709 // Forget all contained loops too, to avoid dangling entries in the
6710 // ValuesAtScopes map.
6711 LoopWorklist.append(CurrL->begin(), CurrL->end());
6712 }
6713}
6714
6715void ScalarEvolution::forgetTopmostLoop(const Loop *L) {
6716 while (Loop *Parent = L->getParentLoop())
6717 L = Parent;
6718 forgetLoop(L);
6719}
6720
6721void ScalarEvolution::forgetValue(Value *V) {
6722 Instruction *I = dyn_cast<Instruction>(V);
6723 if (!I) return;
6724
6725 // Drop information about expressions based on loop-header PHIs.
6726 SmallVector<Instruction *, 16> Worklist;
6727 Worklist.push_back(I);
6728
6729 SmallPtrSet<Instruction *, 8> Visited;
6730 while (!Worklist.empty()) {
6731 I = Worklist.pop_back_val();
6732 if (!Visited.insert(I).second)
6733 continue;
6734
6735 ValueExprMapType::iterator It =
6736 ValueExprMap.find_as(static_cast<Value *>(I));
6737 if (It != ValueExprMap.end()) {
6738 eraseValueFromMap(It->first);
6739 forgetMemoizedResults(It->second);
6740 if (PHINode *PN = dyn_cast<PHINode>(I))
6741 ConstantEvolutionLoopExitValue.erase(PN);
6742 }
6743
6744 PushDefUseChildren(I, Worklist);
6745 }
6746}
6747
6748void ScalarEvolution::forgetLoopDispositions(const Loop *L) {
6749 LoopDispositions.clear();
6750}
6751
6752/// Get the exact loop backedge taken count considering all loop exits. A
6753/// computable result can only be returned for loops with all exiting blocks
6754/// dominating the latch. howFarToZero assumes that the limit of each loop test
6755/// is never skipped. This is a valid assumption as long as the loop exits via
6756/// that test. For precise results, it is the caller's responsibility to specify
6757/// the relevant loop exiting block using getExact(ExitingBlock, SE).
6758const SCEV *
6759ScalarEvolution::BackedgeTakenInfo::getExact(const Loop *L, ScalarEvolution *SE,
6760 SCEVUnionPredicate *Preds) const {
6761 // If any exits were not computable, the loop is not computable.
6762 if (!isComplete() || ExitNotTaken.empty())
6763 return SE->getCouldNotCompute();
6764
6765 const BasicBlock *Latch = L->getLoopLatch();
6766 // All exiting blocks we have collected must dominate the only backedge.
6767 if (!Latch)
6768 return SE->getCouldNotCompute();
6769
6770 // All exiting blocks we have gathered dominate loop's latch, so exact trip
6771 // count is simply a minimum out of all these calculated exit counts.
6772 SmallVector<const SCEV *, 2> Ops;
6773 for (auto &ENT : ExitNotTaken) {
6774 const SCEV *BECount = ENT.ExactNotTaken;
6775 assert(BECount != SE->getCouldNotCompute() && "Bad exit SCEV!")((BECount != SE->getCouldNotCompute() && "Bad exit SCEV!"
) ? static_cast<void> (0) : __assert_fail ("BECount != SE->getCouldNotCompute() && \"Bad exit SCEV!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6775, __PRETTY_FUNCTION__))
;
6776 assert(SE->DT.dominates(ENT.ExitingBlock, Latch) &&((SE->DT.dominates(ENT.ExitingBlock, Latch) && "We should only have known counts for exiting blocks that dominate "
"latch!") ? static_cast<void> (0) : __assert_fail ("SE->DT.dominates(ENT.ExitingBlock, Latch) && \"We should only have known counts for exiting blocks that dominate \" \"latch!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6778, __PRETTY_FUNCTION__))
6777 "We should only have known counts for exiting blocks that dominate "((SE->DT.dominates(ENT.ExitingBlock, Latch) && "We should only have known counts for exiting blocks that dominate "
"latch!") ? static_cast<void> (0) : __assert_fail ("SE->DT.dominates(ENT.ExitingBlock, Latch) && \"We should only have known counts for exiting blocks that dominate \" \"latch!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6778, __PRETTY_FUNCTION__))
6778 "latch!")((SE->DT.dominates(ENT.ExitingBlock, Latch) && "We should only have known counts for exiting blocks that dominate "
"latch!") ? static_cast<void> (0) : __assert_fail ("SE->DT.dominates(ENT.ExitingBlock, Latch) && \"We should only have known counts for exiting blocks that dominate \" \"latch!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6778, __PRETTY_FUNCTION__))
;
6779
6780 Ops.push_back(BECount);
6781
6782 if (Preds && !ENT.hasAlwaysTruePredicate())
6783 Preds->add(ENT.Predicate.get());
6784
6785 assert((Preds || ENT.hasAlwaysTruePredicate()) &&(((Preds || ENT.hasAlwaysTruePredicate()) && "Predicate should be always true!"
) ? static_cast<void> (0) : __assert_fail ("(Preds || ENT.hasAlwaysTruePredicate()) && \"Predicate should be always true!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6786, __PRETTY_FUNCTION__))
6786 "Predicate should be always true!")(((Preds || ENT.hasAlwaysTruePredicate()) && "Predicate should be always true!"
) ? static_cast<void> (0) : __assert_fail ("(Preds || ENT.hasAlwaysTruePredicate()) && \"Predicate should be always true!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6786, __PRETTY_FUNCTION__))
;
6787 }
6788
6789 return SE->getUMinFromMismatchedTypes(Ops);
6790}
6791
6792/// Get the exact not taken count for this loop exit.
6793const SCEV *
6794ScalarEvolution::BackedgeTakenInfo::getExact(const BasicBlock *ExitingBlock,
6795 ScalarEvolution *SE) const {
6796 for (auto &ENT : ExitNotTaken)
6797 if (ENT.ExitingBlock == ExitingBlock && ENT.hasAlwaysTruePredicate())
6798 return ENT.ExactNotTaken;
6799
6800 return SE->getCouldNotCompute();
6801}
6802
6803const SCEV *
6804ScalarEvolution::BackedgeTakenInfo::getMax(const BasicBlock *ExitingBlock,
6805 ScalarEvolution *SE) const {
6806 for (auto &ENT : ExitNotTaken)
6807 if (ENT.ExitingBlock == ExitingBlock && ENT.hasAlwaysTruePredicate())
6808 return ENT.MaxNotTaken;
6809
6810 return SE->getCouldNotCompute();
6811}
6812
6813/// getMax - Get the max backedge taken count for the loop.
6814const SCEV *
6815ScalarEvolution::BackedgeTakenInfo::getMax(ScalarEvolution *SE) const {
6816 auto PredicateNotAlwaysTrue = [](const ExitNotTakenInfo &ENT) {
6817 return !ENT.hasAlwaysTruePredicate();
6818 };
6819
6820 if (any_of(ExitNotTaken, PredicateNotAlwaysTrue) || !getMax())
6821 return SE->getCouldNotCompute();
6822
6823 assert((isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant>(getMax())) &&(((isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant
>(getMax())) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant>(getMax())) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6824, __PRETTY_FUNCTION__))
6824 "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant
>(getMax())) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant>(getMax())) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6824, __PRETTY_FUNCTION__))
;
6825 return getMax();
6826}
6827
6828bool ScalarEvolution::BackedgeTakenInfo::isMaxOrZero(ScalarEvolution *SE) const {
6829 auto PredicateNotAlwaysTrue = [](const ExitNotTakenInfo &ENT) {
6830 return !ENT.hasAlwaysTruePredicate();
6831 };
6832 return MaxOrZero && !any_of(ExitNotTaken, PredicateNotAlwaysTrue);
6833}
6834
6835bool ScalarEvolution::BackedgeTakenInfo::hasOperand(const SCEV *S,
6836 ScalarEvolution *SE) const {
6837 if (getMax() && getMax() != SE->getCouldNotCompute() &&
6838 SE->hasOperand(getMax(), S))
6839 return true;
6840
6841 for (auto &ENT : ExitNotTaken)
6842 if (ENT.ExactNotTaken != SE->getCouldNotCompute() &&
6843 SE->hasOperand(ENT.ExactNotTaken, S))
6844 return true;
6845
6846 return false;
6847}
6848
6849ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E)
6850 : ExactNotTaken(E), MaxNotTaken(E) {
6851 assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6853, __PRETTY_FUNCTION__))
6852 isa<SCEVConstant>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6853, __PRETTY_FUNCTION__))
6853 "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6853, __PRETTY_FUNCTION__))
;
6854}
6855
6856ScalarEvolution::ExitLimit::ExitLimit(
6857 const SCEV *E, const SCEV *M, bool MaxOrZero,
6858 ArrayRef<const SmallPtrSetImpl<const SCEVPredicate *> *> PredSetList)
6859 : ExactNotTaken(E), MaxNotTaken(M), MaxOrZero(MaxOrZero) {
6860 assert((isa<SCEVCouldNotCompute>(ExactNotTaken) ||(((isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute
>(MaxNotTaken)) && "Exact is not allowed to be less precise than Max"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute>(MaxNotTaken)) && \"Exact is not allowed to be less precise than Max\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6862, __PRETTY_FUNCTION__))
6861 !isa<SCEVCouldNotCompute>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute
>(MaxNotTaken)) && "Exact is not allowed to be less precise than Max"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute>(MaxNotTaken)) && \"Exact is not allowed to be less precise than Max\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6862, __PRETTY_FUNCTION__))
6862 "Exact is not allowed to be less precise than Max")(((isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute
>(MaxNotTaken)) && "Exact is not allowed to be less precise than Max"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute>(MaxNotTaken)) && \"Exact is not allowed to be less precise than Max\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6862, __PRETTY_FUNCTION__))
;
6863 assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6865, __PRETTY_FUNCTION__))
6864 isa<SCEVConstant>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6865, __PRETTY_FUNCTION__))
6865 "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6865, __PRETTY_FUNCTION__))
;
6866 for (auto *PredSet : PredSetList)
6867 for (auto *P : *PredSet)
6868 addPredicate(P);
6869}
6870
6871ScalarEvolution::ExitLimit::ExitLimit(
6872 const SCEV *E, const SCEV *M, bool MaxOrZero,
6873 const SmallPtrSetImpl<const SCEVPredicate *> &PredSet)
6874 : ExitLimit(E, M, MaxOrZero, {&PredSet}) {
6875 assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6877, __PRETTY_FUNCTION__))
6876 isa<SCEVConstant>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6877, __PRETTY_FUNCTION__))
6877 "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6877, __PRETTY_FUNCTION__))
;
6878}
6879
6880ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E, const SCEV *M,
6881 bool MaxOrZero)
6882 : ExitLimit(E, M, MaxOrZero, None) {
6883 assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6885, __PRETTY_FUNCTION__))
6884 isa<SCEVConstant>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6885, __PRETTY_FUNCTION__))
6885 "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6885, __PRETTY_FUNCTION__))
;
6886}
6887
6888/// Allocate memory for BackedgeTakenInfo and copy the not-taken count of each
6889/// computable exit into a persistent ExitNotTakenInfo array.
6890ScalarEvolution::BackedgeTakenInfo::BackedgeTakenInfo(
6891 ArrayRef<ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo>
6892 ExitCounts,
6893 bool Complete, const SCEV *MaxCount, bool MaxOrZero)
6894 : MaxAndComplete(MaxCount, Complete), MaxOrZero(MaxOrZero) {
6895 using EdgeExitInfo = ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo;
6896
6897 ExitNotTaken.reserve(ExitCounts.size());
6898 std::transform(
6899 ExitCounts.begin(), ExitCounts.end(), std::back_inserter(ExitNotTaken),
6900 [&](const EdgeExitInfo &EEI) {
6901 BasicBlock *ExitBB = EEI.first;
6902 const ExitLimit &EL = EEI.second;
6903 if (EL.Predicates.empty())
6904 return ExitNotTakenInfo(ExitBB, EL.ExactNotTaken, EL.MaxNotTaken,
6905 nullptr);
6906
6907 std::unique_ptr<SCEVUnionPredicate> Predicate(new SCEVUnionPredicate);
6908 for (auto *Pred : EL.Predicates)
6909 Predicate->add(Pred);
6910
6911 return ExitNotTakenInfo(ExitBB, EL.ExactNotTaken, EL.MaxNotTaken,
6912 std::move(Predicate));
6913 });
6914 assert((isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant>(MaxCount)) &&(((isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant
>(MaxCount)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant>(MaxCount)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6915, __PRETTY_FUNCTION__))
6915 "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant
>(MaxCount)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant>(MaxCount)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6915, __PRETTY_FUNCTION__))
;
6916}
6917
6918/// Invalidate this result and free the ExitNotTakenInfo array.
6919void ScalarEvolution::BackedgeTakenInfo::clear() {
6920 ExitNotTaken.clear();
6921}
6922
6923/// Compute the number of times the backedge of the specified loop will execute.
6924ScalarEvolution::BackedgeTakenInfo
6925ScalarEvolution::computeBackedgeTakenCount(const Loop *L,
6926 bool AllowPredicates) {
6927 SmallVector<BasicBlock *, 8> ExitingBlocks;
6928 L->getExitingBlocks(ExitingBlocks);
6929
6930 using EdgeExitInfo = ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo;
6931
6932 SmallVector<EdgeExitInfo, 4> ExitCounts;
6933 bool CouldComputeBECount = true;
6934 BasicBlock *Latch = L->getLoopLatch(); // may be NULL.
6935 const SCEV *MustExitMaxBECount = nullptr;
6936 const SCEV *MayExitMaxBECount = nullptr;
6937 bool MustExitMaxOrZero = false;
6938
6939 // Compute the ExitLimit for each loop exit. Use this to populate ExitCounts
6940 // and compute maxBECount.
6941 // Do a union of all the predicates here.
6942 for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) {
6943 BasicBlock *ExitBB = ExitingBlocks[i];
6944
6945 // We canonicalize untaken exits to br (constant), ignore them so that
6946 // proving an exit untaken doesn't negatively impact our ability to reason
6947 // about the loop as whole.
6948 if (auto *BI = dyn_cast<BranchInst>(ExitBB->getTerminator()))
6949 if (auto *CI = dyn_cast<ConstantInt>(BI->getCondition())) {
6950 bool ExitIfTrue = !L->contains(BI->getSuccessor(0));
6951 if ((ExitIfTrue && CI->isZero()) || (!ExitIfTrue && CI->isOne()))
6952 continue;
6953 }
6954
6955 ExitLimit EL = computeExitLimit(L, ExitBB, AllowPredicates);
6956
6957 assert((AllowPredicates || EL.Predicates.empty()) &&(((AllowPredicates || EL.Predicates.empty()) && "Predicated exit limit when predicates are not allowed!"
) ? static_cast<void> (0) : __assert_fail ("(AllowPredicates || EL.Predicates.empty()) && \"Predicated exit limit when predicates are not allowed!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6958, __PRETTY_FUNCTION__))
6958 "Predicated exit limit when predicates are not allowed!")(((AllowPredicates || EL.Predicates.empty()) && "Predicated exit limit when predicates are not allowed!"
) ? static_cast<void> (0) : __assert_fail ("(AllowPredicates || EL.Predicates.empty()) && \"Predicated exit limit when predicates are not allowed!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6958, __PRETTY_FUNCTION__))
;
6959
6960 // 1. For each exit that can be computed, add an entry to ExitCounts.
6961 // CouldComputeBECount is true only if all exits can be computed.
6962 if (EL.ExactNotTaken == getCouldNotCompute())
6963 // We couldn't compute an exact value for this exit, so
6964 // we won't be able to compute an exact value for the loop.
6965 CouldComputeBECount = false;
6966 else
6967 ExitCounts.emplace_back(ExitBB, EL);
6968
6969 // 2. Derive the loop's MaxBECount from each exit's max number of
6970 // non-exiting iterations. Partition the loop exits into two kinds:
6971 // LoopMustExits and LoopMayExits.
6972 //
6973 // If the exit dominates the loop latch, it is a LoopMustExit otherwise it
6974 // is a LoopMayExit. If any computable LoopMustExit is found, then
6975 // MaxBECount is the minimum EL.MaxNotTaken of computable
6976 // LoopMustExits. Otherwise, MaxBECount is conservatively the maximum
6977 // EL.MaxNotTaken, where CouldNotCompute is considered greater than any
6978 // computable EL.MaxNotTaken.
6979 if (EL.MaxNotTaken != getCouldNotCompute() && Latch &&
6980 DT.dominates(ExitBB, Latch)) {
6981 if (!MustExitMaxBECount) {
6982 MustExitMaxBECount = EL.MaxNotTaken;
6983 MustExitMaxOrZero = EL.MaxOrZero;
6984 } else {
6985 MustExitMaxBECount =
6986 getUMinFromMismatchedTypes(MustExitMaxBECount, EL.MaxNotTaken);
6987 }
6988 } else if (MayExitMaxBECount != getCouldNotCompute()) {
6989 if (!MayExitMaxBECount || EL.MaxNotTaken == getCouldNotCompute())
6990 MayExitMaxBECount = EL.MaxNotTaken;
6991 else {
6992 MayExitMaxBECount =
6993 getUMaxFromMismatchedTypes(MayExitMaxBECount, EL.MaxNotTaken);
6994 }
6995 }
6996 }
6997 const SCEV *MaxBECount = MustExitMaxBECount ? MustExitMaxBECount :
6998 (MayExitMaxBECount ? MayExitMaxBECount : getCouldNotCompute());
6999 // The loop backedge will be taken the maximum or zero times if there's
7000 // a single exit that must be taken the maximum or zero times.
7001 bool MaxOrZero = (MustExitMaxOrZero && ExitingBlocks.size() == 1);
7002 return BackedgeTakenInfo(std::move(ExitCounts), CouldComputeBECount,
7003 MaxBECount, MaxOrZero);
7004}
7005
7006ScalarEvolution::ExitLimit
7007ScalarEvolution::computeExitLimit(const Loop *L, BasicBlock *ExitingBlock,
7008 bool AllowPredicates) {
7009 assert(L->contains(ExitingBlock) && "Exit count for non-loop block?")((L->contains(ExitingBlock) && "Exit count for non-loop block?"
) ? static_cast<void> (0) : __assert_fail ("L->contains(ExitingBlock) && \"Exit count for non-loop block?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7009, __PRETTY_FUNCTION__))
;
7010 // If our exiting block does not dominate the latch, then its connection with
7011 // loop's exit limit may be far from trivial.
7012 const BasicBlock *Latch = L->getLoopLatch();
7013 if (!Latch || !DT.dominates(ExitingBlock, Latch))
7014 return getCouldNotCompute();
7015
7016 bool IsOnlyExit = (L->getExitingBlock() != nullptr);
7017 Instruction *Term = ExitingBlock->getTerminator();
7018 if (BranchInst *BI = dyn_cast<BranchInst>(Term)) {
7019 assert(BI->isConditional() && "If unconditional, it can't be in loop!")((BI->isConditional() && "If unconditional, it can't be in loop!"
) ? static_cast<void> (0) : __assert_fail ("BI->isConditional() && \"If unconditional, it can't be in loop!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7019, __PRETTY_FUNCTION__))
;
7020 bool ExitIfTrue = !L->contains(BI->getSuccessor(0));
7021 assert(ExitIfTrue == L->contains(BI->getSuccessor(1)) &&((ExitIfTrue == L->contains(BI->getSuccessor(1)) &&
"It should have one successor in loop and one exit block!") ?
static_cast<void> (0) : __assert_fail ("ExitIfTrue == L->contains(BI->getSuccessor(1)) && \"It should have one successor in loop and one exit block!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7022, __PRETTY_FUNCTION__))
7022 "It should have one successor in loop and one exit block!")((ExitIfTrue == L->contains(BI->getSuccessor(1)) &&
"It should have one successor in loop and one exit block!") ?
static_cast<void> (0) : __assert_fail ("ExitIfTrue == L->contains(BI->getSuccessor(1)) && \"It should have one successor in loop and one exit block!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7022, __PRETTY_FUNCTION__))
;
7023 // Proceed to the next level to examine the exit condition expression.
7024 return computeExitLimitFromCond(
7025 L, BI->getCondition(), ExitIfTrue,
7026 /*ControlsExit=*/IsOnlyExit, AllowPredicates);
7027 }
7028
7029 if (SwitchInst *SI = dyn_cast<SwitchInst>(Term)) {
7030 // For switch, make sure that there is a single exit from the loop.
7031 BasicBlock *Exit = nullptr;
7032 for (auto *SBB : successors(ExitingBlock))
7033 if (!L->contains(SBB)) {
7034 if (Exit) // Multiple exit successors.
7035 return getCouldNotCompute();
7036 Exit = SBB;
7037 }
7038 assert(Exit && "Exiting block must have at least one exit")((Exit && "Exiting block must have at least one exit"
) ? static_cast<void> (0) : __assert_fail ("Exit && \"Exiting block must have at least one exit\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7038, __PRETTY_FUNCTION__))
;
7039 return computeExitLimitFromSingleExitSwitch(L, SI, Exit,
7040 /*ControlsExit=*/IsOnlyExit);
7041 }
7042
7043 return getCouldNotCompute();
7044}
7045
7046ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCond(
7047 const Loop *L, Value *ExitCond, bool ExitIfTrue,
7048 bool ControlsExit, bool AllowPredicates) {
7049 ScalarEvolution::ExitLimitCacheTy Cache(L, ExitIfTrue, AllowPredicates);
7050 return computeExitLimitFromCondCached(Cache, L, ExitCond, ExitIfTrue,
7051 ControlsExit, AllowPredicates);
7052}
7053
7054Optional<ScalarEvolution::ExitLimit>
7055ScalarEvolution::ExitLimitCache::find(const Loop *L, Value *ExitCond,
7056 bool ExitIfTrue, bool ControlsExit,
7057 bool AllowPredicates) {
7058 (void)this->L;
7059 (void)this->ExitIfTrue;
7060 (void)this->AllowPredicates;
7061
7062 assert(this->L == L && this->ExitIfTrue == ExitIfTrue &&((this->L == L && this->ExitIfTrue == ExitIfTrue
&& this->AllowPredicates == AllowPredicates &&
"Variance in assumed invariant key components!") ? static_cast
<void> (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7064, __PRETTY_FUNCTION__))
7063 this->AllowPredicates == AllowPredicates &&((this->L == L && this->ExitIfTrue == ExitIfTrue
&& this->AllowPredicates == AllowPredicates &&
"Variance in assumed invariant key components!") ? static_cast
<void> (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7064, __PRETTY_FUNCTION__))
7064 "Variance in assumed invariant key components!")((this->L == L && this->ExitIfTrue == ExitIfTrue
&& this->AllowPredicates == AllowPredicates &&
"Variance in assumed invariant key components!") ? static_cast
<void> (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7064, __PRETTY_FUNCTION__))
;
7065 auto Itr = TripCountMap.find({ExitCond, ControlsExit});
7066 if (Itr == TripCountMap.end())
7067 return None;
7068 return Itr->second;
7069}
7070
7071void ScalarEvolution::ExitLimitCache::insert(const Loop *L, Value *ExitCond,
7072 bool ExitIfTrue,
7073 bool ControlsExit,
7074 bool AllowPredicates,
7075 const ExitLimit &EL) {
7076 assert(this->L == L && this->ExitIfTrue == ExitIfTrue &&((this->L == L && this->ExitIfTrue == ExitIfTrue
&& this->AllowPredicates == AllowPredicates &&
"Variance in assumed invariant key components!") ? static_cast
<void> (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7078, __PRETTY_FUNCTION__))
7077 this->AllowPredicates == AllowPredicates &&((this->L == L && this->ExitIfTrue == ExitIfTrue
&& this->AllowPredicates == AllowPredicates &&
"Variance in assumed invariant key components!") ? static_cast
<void> (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7078, __PRETTY_FUNCTION__))
7078 "Variance in assumed invariant key components!")((this->L == L && this->ExitIfTrue == ExitIfTrue
&& this->AllowPredicates == AllowPredicates &&
"Variance in assumed invariant key components!") ? static_cast
<void> (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7078, __PRETTY_FUNCTION__))
;
7079
7080 auto InsertResult = TripCountMap.insert({{ExitCond, ControlsExit}, EL});
7081 assert(InsertResult.second && "Expected successful insertion!")((InsertResult.second && "Expected successful insertion!"
) ? static_cast<void> (0) : __assert_fail ("InsertResult.second && \"Expected successful insertion!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7081, __PRETTY_FUNCTION__))
;
7082 (void)InsertResult;
7083 (void)ExitIfTrue;
7084}
7085
7086ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondCached(
7087 ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, bool ExitIfTrue,
7088 bool ControlsExit, bool AllowPredicates) {
7089
7090 if (auto MaybeEL =
7091 Cache.find(L, ExitCond, ExitIfTrue, ControlsExit, AllowPredicates))
7092 return *MaybeEL;
7093
7094 ExitLimit EL = computeExitLimitFromCondImpl(Cache, L, ExitCond, ExitIfTrue,
7095 ControlsExit, AllowPredicates);
7096 Cache.insert(L, ExitCond, ExitIfTrue, ControlsExit, AllowPredicates, EL);
7097 return EL;
7098}
7099
7100ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondImpl(
7101 ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, bool ExitIfTrue,
7102 bool ControlsExit, bool AllowPredicates) {
7103 // Check if the controlling expression for this loop is an And or Or.
7104 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(ExitCond)) {
7105 if (BO->getOpcode() == Instruction::And) {
7106 // Recurse on the operands of the and.
7107 bool EitherMayExit = !ExitIfTrue;
7108 ExitLimit EL0 = computeExitLimitFromCondCached(
7109 Cache, L, BO->getOperand(0), ExitIfTrue,
7110 ControlsExit && !EitherMayExit, AllowPredicates);
7111 ExitLimit EL1 = computeExitLimitFromCondCached(
7112 Cache, L, BO->getOperand(1), ExitIfTrue,
7113 ControlsExit && !EitherMayExit, AllowPredicates);
7114 // Be robust against unsimplified IR for the form "and i1 X, true"
7115 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1)))
7116 return CI->isOne() ? EL0 : EL1;
7117 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(0)))
7118 return CI->isOne() ? EL1 : EL0;
7119 const SCEV *BECount = getCouldNotCompute();
7120 const SCEV *MaxBECount = getCouldNotCompute();
7121 if (EitherMayExit) {
7122 // Both conditions must be true for the loop to continue executing.
7123 // Choose the less conservative count.
7124 if (EL0.ExactNotTaken == getCouldNotCompute() ||
7125 EL1.ExactNotTaken == getCouldNotCompute())
7126 BECount = getCouldNotCompute();
7127 else
7128 BECount =
7129 getUMinFromMismatchedTypes(EL0.ExactNotTaken, EL1.ExactNotTaken);
7130 if (EL0.MaxNotTaken == getCouldNotCompute())
7131 MaxBECount = EL1.MaxNotTaken;
7132 else if (EL1.MaxNotTaken == getCouldNotCompute())
7133 MaxBECount = EL0.MaxNotTaken;
7134 else
7135 MaxBECount =
7136 getUMinFromMismatchedTypes(EL0.MaxNotTaken, EL1.MaxNotTaken);
7137 } else {
7138 // Both conditions must be true at the same time for the loop to exit.
7139 // For now, be conservative.
7140 if (EL0.MaxNotTaken == EL1.MaxNotTaken)
7141 MaxBECount = EL0.MaxNotTaken;
7142 if (EL0.ExactNotTaken == EL1.ExactNotTaken)
7143 BECount = EL0.ExactNotTaken;
7144 }
7145
7146 // There are cases (e.g. PR26207) where computeExitLimitFromCond is able
7147 // to be more aggressive when computing BECount than when computing
7148 // MaxBECount. In these cases it is possible for EL0.ExactNotTaken and
7149 // EL1.ExactNotTaken to match, but for EL0.MaxNotTaken and EL1.MaxNotTaken
7150 // to not.
7151 if (isa<SCEVCouldNotCompute>(MaxBECount) &&
7152 !isa<SCEVCouldNotCompute>(BECount))
7153 MaxBECount = getConstant(getUnsignedRangeMax(BECount));
7154
7155 return ExitLimit(BECount, MaxBECount, false,
7156 {&EL0.Predicates, &EL1.Predicates});
7157 }
7158 if (BO->getOpcode() == Instruction::Or) {
7159 // Recurse on the operands of the or.
7160 bool EitherMayExit = ExitIfTrue;
7161 ExitLimit EL0 = computeExitLimitFromCondCached(
7162 Cache, L, BO->getOperand(0), ExitIfTrue,
7163 ControlsExit && !EitherMayExit, AllowPredicates);
7164 ExitLimit EL1 = computeExitLimitFromCondCached(
7165 Cache, L, BO->getOperand(1), ExitIfTrue,
7166 ControlsExit && !EitherMayExit, AllowPredicates);
7167 // Be robust against unsimplified IR for the form "or i1 X, true"
7168 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1)))
7169 return CI->isZero() ? EL0 : EL1;
7170 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(0)))
7171 return CI->isZero() ? EL1 : EL0;
7172 const SCEV *BECount = getCouldNotCompute();
7173 const SCEV *MaxBECount = getCouldNotCompute();
7174 if (EitherMayExit) {
7175 // Both conditions must be false for the loop to continue executing.
7176 // Choose the less conservative count.
7177 if (EL0.ExactNotTaken == getCouldNotCompute() ||
7178 EL1.ExactNotTaken == getCouldNotCompute())
7179 BECount = getCouldNotCompute();
7180 else
7181 BECount =
7182 getUMinFromMismatchedTypes(EL0.ExactNotTaken, EL1.ExactNotTaken);
7183 if (EL0.MaxNotTaken == getCouldNotCompute())
7184 MaxBECount = EL1.MaxNotTaken;
7185 else if (EL1.MaxNotTaken == getCouldNotCompute())
7186 MaxBECount = EL0.MaxNotTaken;
7187 else
7188 MaxBECount =
7189 getUMinFromMismatchedTypes(EL0.MaxNotTaken, EL1.MaxNotTaken);
7190 } else {
7191 // Both conditions must be false at the same time for the loop to exit.
7192 // For now, be conservative.
7193 if (EL0.MaxNotTaken == EL1.MaxNotTaken)
7194 MaxBECount = EL0.MaxNotTaken;
7195 if (EL0.ExactNotTaken == EL1.ExactNotTaken)
7196 BECount = EL0.ExactNotTaken;
7197 }
7198 // There are cases (e.g. PR26207) where computeExitLimitFromCond is able
7199 // to be more aggressive when computing BECount than when computing
7200 // MaxBECount. In these cases it is possible for EL0.ExactNotTaken and
7201 // EL1.ExactNotTaken to match, but for EL0.MaxNotTaken and EL1.MaxNotTaken
7202 // to not.
7203 if (isa<SCEVCouldNotCompute>(MaxBECount) &&
7204 !isa<SCEVCouldNotCompute>(BECount))
7205 MaxBECount = getConstant(getUnsignedRangeMax(BECount));
7206
7207 return ExitLimit(BECount, MaxBECount, false,
7208 {&EL0.Predicates, &EL1.Predicates});
7209 }
7210 }
7211
7212 // With an icmp, it may be feasible to compute an exact backedge-taken count.
7213 // Proceed to the next level to examine the icmp.
7214 if (ICmpInst *ExitCondICmp = dyn_cast<ICmpInst>(ExitCond)) {
7215 ExitLimit EL =
7216 computeExitLimitFromICmp(L, ExitCondICmp, ExitIfTrue, ControlsExit);
7217 if (EL.hasFullInfo() || !AllowPredicates)
7218 return EL;
7219
7220 // Try again, but use SCEV predicates this time.
7221 return computeExitLimitFromICmp(L, ExitCondICmp, ExitIfTrue, ControlsExit,
7222 /*AllowPredicates=*/true);
7223 }
7224
7225 // Check for a constant condition. These are normally stripped out by
7226 // SimplifyCFG, but ScalarEvolution may be used by a pass which wishes to
7227 // preserve the CFG and is temporarily leaving constant conditions
7228 // in place.
7229 if (ConstantInt *CI = dyn_cast<ConstantInt>(ExitCond)) {
7230 if (ExitIfTrue == !CI->getZExtValue())
7231 // The backedge is always taken.
7232 return getCouldNotCompute();
7233 else
7234 // The backedge is never taken.
7235 return getZero(CI->getType());
7236 }
7237
7238 // If it's not an integer or pointer comparison then compute it the hard way.
7239 return computeExitCountExhaustively(L, ExitCond, ExitIfTrue);
7240}
7241
7242ScalarEvolution::ExitLimit
7243ScalarEvolution::computeExitLimitFromICmp(const Loop *L,
7244 ICmpInst *ExitCond,
7245 bool ExitIfTrue,
7246 bool ControlsExit,
7247 bool AllowPredicates) {
7248 // If the condition was exit on true, convert the condition to exit on false
7249 ICmpInst::Predicate Pred;
7250 if (!ExitIfTrue)
7251 Pred = ExitCond->getPredicate();
7252 else
7253 Pred = ExitCond->getInversePredicate();
7254 const ICmpInst::Predicate OriginalPred = Pred;
7255
7256 // Handle common loops like: for (X = "string"; *X; ++X)
7257 if (LoadInst *LI = dyn_cast<LoadInst>(ExitCond->getOperand(0)))
7258 if (Constant *RHS = dyn_cast<Constant>(ExitCond->getOperand(1))) {
7259 ExitLimit ItCnt =
7260 computeLoadConstantCompareExitLimit(LI, RHS, L, Pred);
7261 if (ItCnt.hasAnyInfo())
7262 return ItCnt;
7263 }
7264
7265 const SCEV *LHS = getSCEV(ExitCond->getOperand(0));
7266 const SCEV *RHS = getSCEV(ExitCond->getOperand(1));
7267
7268 // Try to evaluate any dependencies out of the loop.
7269 LHS = getSCEVAtScope(LHS, L);
7270 RHS = getSCEVAtScope(RHS, L);
7271
7272 // At this point, we would like to compute how many iterations of the
7273 // loop the predicate will return true for these inputs.
7274 if (isLoopInvariant(LHS, L) && !isLoopInvariant(RHS, L)) {
7275 // If there is a loop-invariant, force it into the RHS.
7276 std::swap(LHS, RHS);
7277 Pred = ICmpInst::getSwappedPredicate(Pred);
7278 }
7279
7280 // Simplify the operands before analyzing them.
7281 (void)SimplifyICmpOperands(Pred, LHS, RHS);
7282
7283 // If we have a comparison of a chrec against a constant, try to use value
7284 // ranges to answer this query.
7285 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS))
7286 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(LHS))
7287 if (AddRec->getLoop() == L) {
7288 // Form the constant range.
7289 ConstantRange CompRange =
7290 ConstantRange::makeExactICmpRegion(Pred, RHSC->getAPInt());
7291
7292 const SCEV *Ret = AddRec->getNumIterationsInRange(CompRange, *this);
7293 if (!isa<SCEVCouldNotCompute>(Ret)) return Ret;
7294 }
7295
7296 switch (Pred) {
7297 case ICmpInst::ICMP_NE: { // while (X != Y)
7298 // Convert to: while (X-Y != 0)
7299 ExitLimit EL = howFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit,
7300 AllowPredicates);
7301 if (EL.hasAnyInfo()) return EL;
7302 break;
7303 }
7304 case ICmpInst::ICMP_EQ: { // while (X == Y)
7305 // Convert to: while (X-Y == 0)
7306 ExitLimit EL = howFarToNonZero(getMinusSCEV(LHS, RHS), L);
7307 if (EL.hasAnyInfo()) return EL;
7308 break;
7309 }
7310 case ICmpInst::ICMP_SLT:
7311 case ICmpInst::ICMP_ULT: { // while (X < Y)
7312 bool IsSigned = Pred == ICmpInst::ICMP_SLT;
7313 ExitLimit EL = howManyLessThans(LHS, RHS, L, IsSigned, ControlsExit,
7314 AllowPredicates);
7315 if (EL.hasAnyInfo()) return EL;
7316 break;
7317 }
7318 case ICmpInst::ICMP_SGT:
7319 case ICmpInst::ICMP_UGT: { // while (X > Y)
7320 bool IsSigned = Pred == ICmpInst::ICMP_SGT;
7321 ExitLimit EL =
7322 howManyGreaterThans(LHS, RHS, L, IsSigned, ControlsExit,
7323 AllowPredicates);
7324 if (EL.hasAnyInfo()) return EL;
7325 break;
7326 }
7327 default:
7328 break;
7329 }
7330
7331 auto *ExhaustiveCount =
7332 computeExitCountExhaustively(L, ExitCond, ExitIfTrue);
7333
7334 if (!isa<SCEVCouldNotCompute>(ExhaustiveCount))
7335 return ExhaustiveCount;
7336
7337 return computeShiftCompareExitLimit(ExitCond->getOperand(0),
7338 ExitCond->getOperand(1), L, OriginalPred);
7339}
7340
7341ScalarEvolution::ExitLimit
7342ScalarEvolution::computeExitLimitFromSingleExitSwitch(const Loop *L,
7343 SwitchInst *Switch,
7344 BasicBlock *ExitingBlock,
7345 bool ControlsExit) {
7346 assert(!L->contains(ExitingBlock) && "Not an exiting block!")((!L->contains(ExitingBlock) && "Not an exiting block!"
) ? static_cast<void> (0) : __assert_fail ("!L->contains(ExitingBlock) && \"Not an exiting block!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7346, __PRETTY_FUNCTION__))
;
7347
7348 // Give up if the exit is the default dest of a switch.
7349 if (Switch->getDefaultDest() == ExitingBlock)
7350 return getCouldNotCompute();
7351
7352 assert(L->contains(Switch->getDefaultDest()) &&((L->contains(Switch->getDefaultDest()) && "Default case must not exit the loop!"
) ? static_cast<void> (0) : __assert_fail ("L->contains(Switch->getDefaultDest()) && \"Default case must not exit the loop!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7353, __PRETTY_FUNCTION__))
7353 "Default case must not exit the loop!")((L->contains(Switch->getDefaultDest()) && "Default case must not exit the loop!"
) ? static_cast<void> (0) : __assert_fail ("L->contains(Switch->getDefaultDest()) && \"Default case must not exit the loop!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7353, __PRETTY_FUNCTION__))
;
7354 const SCEV *LHS = getSCEVAtScope(Switch->getCondition(), L);
7355 const SCEV *RHS = getConstant(Switch->findCaseDest(ExitingBlock));
7356
7357 // while (X != Y) --> while (X-Y != 0)
7358 ExitLimit EL = howFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit);
7359 if (EL.hasAnyInfo())
7360 return EL;
7361
7362 return getCouldNotCompute();
7363}
7364
7365static ConstantInt *
7366EvaluateConstantChrecAtConstant(const SCEVAddRecExpr *AddRec, ConstantInt *C,
7367 ScalarEvolution &SE) {
7368 const SCEV *InVal = SE.getConstant(C);
7369 const SCEV *Val = AddRec->evaluateAtIteration(InVal, SE);
7370 assert(isa<SCEVConstant>(Val) &&((isa<SCEVConstant>(Val) && "Evaluation of SCEV at constant didn't fold correctly?"
) ? static_cast<void> (0) : __assert_fail ("isa<SCEVConstant>(Val) && \"Evaluation of SCEV at constant didn't fold correctly?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7371, __PRETTY_FUNCTION__))
7371 "Evaluation of SCEV at constant didn't fold correctly?")((isa<SCEVConstant>(Val) && "Evaluation of SCEV at constant didn't fold correctly?"
) ? static_cast<void> (0) : __assert_fail ("isa<SCEVConstant>(Val) && \"Evaluation of SCEV at constant didn't fold correctly?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7371, __PRETTY_FUNCTION__))
;
7372 return cast<SCEVConstant>(Val)->getValue();
7373}
7374
7375/// Given an exit condition of 'icmp op load X, cst', try to see if we can
7376/// compute the backedge execution count.
7377ScalarEvolution::ExitLimit
7378ScalarEvolution::computeLoadConstantCompareExitLimit(
7379 LoadInst *LI,
7380 Constant *RHS,
7381 const Loop *L,
7382 ICmpInst::Predicate predicate) {
7383 if (LI->isVolatile()) return getCouldNotCompute();
7384
7385 // Check to see if the loaded pointer is a getelementptr of a global.
7386 // TODO: Use SCEV instead of manually grubbing with GEPs.
7387 GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0));
7388 if (!GEP) return getCouldNotCompute();
7389
7390 // Make sure that it is really a constant global we are gepping, with an
7391 // initializer, and make sure the first IDX is really 0.
7392 GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
7393 if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer() ||
7394 GEP->getNumOperands() < 3 || !isa<Constant>(GEP->getOperand(1)) ||
7395 !cast<Constant>(GEP->getOperand(1))->isNullValue())
7396 return getCouldNotCompute();
7397
7398 // Okay, we allow one non-constant index into the GEP instruction.
7399 Value *VarIdx = nullptr;
7400 std::vector<Constant*> Indexes;
7401 unsigned VarIdxNum = 0;
7402 for (unsigned i = 2, e = GEP->getNumOperands(); i != e; ++i)
7403 if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
7404 Indexes.push_back(CI);
7405 } else if (!isa<ConstantInt>(GEP->getOperand(i))) {
7406 if (VarIdx) return getCouldNotCompute(); // Multiple non-constant idx's.
7407 VarIdx = GEP->getOperand(i);
7408 VarIdxNum = i-2;
7409 Indexes.push_back(nullptr);
7410 }
7411
7412 // Loop-invariant loads may be a byproduct of loop optimization. Skip them.
7413 if (!VarIdx)
7414 return getCouldNotCompute();
7415
7416 // Okay, we know we have a (load (gep GV, 0, X)) comparison with a constant.
7417 // Check to see if X is a loop variant variable value now.
7418 const SCEV *Idx = getSCEV(VarIdx);
7419 Idx = getSCEVAtScope(Idx, L);
7420
7421 // We can only recognize very limited forms of loop index expressions, in
7422 // particular, only affine AddRec's like {C1,+,C2}.
7423 const SCEVAddRecExpr *IdxExpr = dyn_cast<SCEVAddRecExpr>(Idx);
7424 if (!IdxExpr || !IdxExpr->isAffine() || isLoopInvariant(IdxExpr, L) ||
7425 !isa<SCEVConstant>(IdxExpr->getOperand(0)) ||
7426 !isa<SCEVConstant>(IdxExpr->getOperand(1)))
7427 return getCouldNotCompute();
7428
7429 unsigned MaxSteps = MaxBruteForceIterations;
7430 for (unsigned IterationNum = 0; IterationNum != MaxSteps; ++IterationNum) {
7431 ConstantInt *ItCst = ConstantInt::get(
7432 cast<IntegerType>(IdxExpr->getType()), IterationNum);
7433 ConstantInt *Val = EvaluateConstantChrecAtConstant(IdxExpr, ItCst, *this);
7434
7435 // Form the GEP offset.
7436 Indexes[VarIdxNum] = Val;
7437
7438 Constant *Result = ConstantFoldLoadThroughGEPIndices(GV->getInitializer(),
7439 Indexes);
7440 if (!Result) break; // Cannot compute!
7441
7442 // Evaluate the condition for this iteration.
7443 Result = ConstantExpr::getICmp(predicate, Result, RHS);
7444 if (!isa<ConstantInt>(Result)) break; // Couldn't decide for sure
7445 if (cast<ConstantInt>(Result)->getValue().isMinValue()) {
7446 ++NumArrayLenItCounts;
7447 return getConstant(ItCst); // Found terminating iteration!
7448 }
7449 }
7450 return getCouldNotCompute();
7451}
7452
7453ScalarEvolution::ExitLimit ScalarEvolution::computeShiftCompareExitLimit(
7454 Value *LHS, Value *RHSV, const Loop *L, ICmpInst::Predicate Pred) {
7455 ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV);
7456 if (!RHS)
7457 return getCouldNotCompute();
7458
7459 const BasicBlock *Latch = L->getLoopLatch();
7460 if (!Latch)
7461 return getCouldNotCompute();
7462
7463 const BasicBlock *Predecessor = L->getLoopPredecessor();
7464 if (!Predecessor)
7465 return getCouldNotCompute();
7466
7467 // Return true if V is of the form "LHS `shift_op` <positive constant>".
7468 // Return LHS in OutLHS and shift_opt in OutOpCode.
7469 auto MatchPositiveShift =
7470 [](Value *V, Value *&OutLHS, Instruction::BinaryOps &OutOpCode) {
7471
7472 using namespace PatternMatch;
7473
7474 ConstantInt *ShiftAmt;
7475 if (match(V, m_LShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
7476 OutOpCode = Instruction::LShr;
7477 else if (match(V, m_AShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
7478 OutOpCode = Instruction::AShr;
7479 else if (match(V, m_Shl(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
7480 OutOpCode = Instruction::Shl;
7481 else
7482 return false;
7483
7484 return ShiftAmt->getValue().isStrictlyPositive();
7485 };
7486
7487 // Recognize a "shift recurrence" either of the form %iv or of %iv.shifted in
7488 //
7489 // loop:
7490 // %iv = phi i32 [ %iv.shifted, %loop ], [ %val, %preheader ]
7491 // %iv.shifted = lshr i32 %iv, <positive constant>
7492 //
7493 // Return true on a successful match. Return the corresponding PHI node (%iv
7494 // above) in PNOut and the opcode of the shift operation in OpCodeOut.
7495 auto MatchShiftRecurrence =
7496 [&](Value *V, PHINode *&PNOut, Instruction::BinaryOps &OpCodeOut) {
7497 Optional<Instruction::BinaryOps> PostShiftOpCode;
7498
7499 {
7500 Instruction::BinaryOps OpC;
7501 Value *V;
7502
7503 // If we encounter a shift instruction, "peel off" the shift operation,
7504 // and remember that we did so. Later when we inspect %iv's backedge
7505 // value, we will make sure that the backedge value uses the same
7506 // operation.
7507 //
7508 // Note: the peeled shift operation does not have to be the same
7509 // instruction as the one feeding into the PHI's backedge value. We only
7510 // really care about it being the same *kind* of shift instruction --
7511 // that's all that is required for our later inferences to hold.
7512 if (MatchPositiveShift(LHS, V, OpC)) {
7513 PostShiftOpCode = OpC;
7514 LHS = V;
7515 }
7516 }
7517
7518 PNOut = dyn_cast<PHINode>(LHS);
7519 if (!PNOut || PNOut->getParent() != L->getHeader())
7520 return false;
7521
7522 Value *BEValue = PNOut->getIncomingValueForBlock(Latch);
7523 Value *OpLHS;
7524
7525 return
7526 // The backedge value for the PHI node must be a shift by a positive
7527 // amount
7528 MatchPositiveShift(BEValue, OpLHS, OpCodeOut) &&
7529
7530 // of the PHI node itself
7531 OpLHS == PNOut &&
7532
7533 // and the kind of shift should be match the kind of shift we peeled
7534 // off, if any.
7535 (!PostShiftOpCode.hasValue() || *PostShiftOpCode == OpCodeOut);
7536 };
7537
7538 PHINode *PN;
7539 Instruction::BinaryOps OpCode;
7540 if (!MatchShiftRecurrence(LHS, PN, OpCode))
7541 return getCouldNotCompute();
7542
7543 const DataLayout &DL = getDataLayout();
7544
7545 // The key rationale for this optimization is that for some kinds of shift
7546 // recurrences, the value of the recurrence "stabilizes" to either 0 or -1
7547 // within a finite number of iterations. If the condition guarding the
7548 // backedge (in the sense that the backedge is taken if the condition is true)
7549 // is false for the value the shift recurrence stabilizes to, then we know
7550 // that the backedge is taken only a finite number of times.
7551
7552 ConstantInt *StableValue = nullptr;
7553 switch (OpCode) {
7554 default:
7555 llvm_unreachable("Impossible case!")::llvm::llvm_unreachable_internal("Impossible case!", "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7555)
;
7556
7557 case Instruction::AShr: {
7558 // {K,ashr,<positive-constant>} stabilizes to signum(K) in at most
7559 // bitwidth(K) iterations.
7560 Value *FirstValue = PN->getIncomingValueForBlock(Predecessor);
7561 KnownBits Known = computeKnownBits(FirstValue, DL, 0, nullptr,
7562 Predecessor->getTerminator(), &DT);
7563 auto *Ty = cast<IntegerType>(RHS->getType());
7564 if (Known.isNonNegative())
7565 StableValue = ConstantInt::get(Ty, 0);
7566 else if (Known.isNegative())
7567 StableValue = ConstantInt::get(Ty, -1, true);
7568 else
7569 return getCouldNotCompute();
7570
7571 break;
7572 }
7573 case Instruction::LShr:
7574 case Instruction::Shl:
7575 // Both {K,lshr,<positive-constant>} and {K,shl,<positive-constant>}
7576 // stabilize to 0 in at most bitwidth(K) iterations.
7577 StableValue = ConstantInt::get(cast<IntegerType>(RHS->getType()), 0);
7578 break;
7579 }
7580
7581 auto *Result =
7582 ConstantFoldCompareInstOperands(Pred, StableValue, RHS, DL, &TLI);
7583 assert(Result->getType()->isIntegerTy(1) &&((Result->getType()->isIntegerTy(1) && "Otherwise cannot be an operand to a branch instruction"
) ? static_cast<void> (0) : __assert_fail ("Result->getType()->isIntegerTy(1) && \"Otherwise cannot be an operand to a branch instruction\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7584, __PRETTY_FUNCTION__))
7584 "Otherwise cannot be an operand to a branch instruction")((Result->getType()->isIntegerTy(1) && "Otherwise cannot be an operand to a branch instruction"
) ? static_cast<void> (0) : __assert_fail ("Result->getType()->isIntegerTy(1) && \"Otherwise cannot be an operand to a branch instruction\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7584, __PRETTY_FUNCTION__))
;
7585
7586 if (Result->isZeroValue()) {
7587 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
7588 const SCEV *UpperBound =
7589 getConstant(getEffectiveSCEVType(RHS->getType()), BitWidth);
7590 return ExitLimit(getCouldNotCompute(), UpperBound, false);
7591 }
7592
7593 return getCouldNotCompute();
7594}
7595
7596/// Return true if we can constant fold an instruction of the specified type,
7597/// assuming that all operands were constants.
7598static bool CanConstantFold(const Instruction *I) {
7599 if (isa<BinaryOperator>(I) || isa<CmpInst>(I) ||
7600 isa<SelectInst>(I) || isa<CastInst>(I) || isa<GetElementPtrInst>(I) ||
7601 isa<LoadInst>(I) || isa<ExtractValueInst>(I))
7602 return true;
7603
7604 if (const CallInst *CI = dyn_cast<CallInst>(I))
7605 if (const Function *F = CI->getCalledFunction())
7606 return canConstantFoldCallTo(CI, F);
7607 return false;
7608}
7609
7610/// Determine whether this instruction can constant evolve within this loop
7611/// assuming its operands can all constant evolve.
7612static bool canConstantEvolve(Instruction *I, const Loop *L) {
7613 // An instruction outside of the loop can't be derived from a loop PHI.
7614 if (!L->contains(I)) return false;
7615
7616 if (isa<PHINode>(I)) {
7617 // We don't currently keep track of the control flow needed to evaluate
7618 // PHIs, so we cannot handle PHIs inside of loops.
7619 return L->getHeader() == I->getParent();
7620 }
7621
7622 // If we won't be able to constant fold this expression even if the operands
7623 // are constants, bail early.
7624 return CanConstantFold(I);
7625}
7626
7627/// getConstantEvolvingPHIOperands - Implement getConstantEvolvingPHI by
7628/// recursing through each instruction operand until reaching a loop header phi.
7629static PHINode *
7630getConstantEvolvingPHIOperands(Instruction *UseInst, const Loop *L,
7631 DenseMap<Instruction *, PHINode *> &PHIMap,
7632 unsigned Depth) {
7633 if (Depth > MaxConstantEvolvingDepth)
7634 return nullptr;
7635
7636 // Otherwise, we can evaluate this instruction if all of its operands are
7637 // constant or derived from a PHI node themselves.
7638 PHINode *PHI = nullptr;
7639 for (Value *Op : UseInst->operands()) {
7640 if (isa<Constant>(Op)) continue;
7641
7642 Instruction *OpInst = dyn_cast<Instruction>(Op);
7643 if (!OpInst || !canConstantEvolve(OpInst, L)) return nullptr;
7644
7645 PHINode *P = dyn_cast<PHINode>(OpInst);
7646 if (!P)
7647 // If this operand is already visited, reuse the prior result.
7648 // We may have P != PHI if this is the deepest point at which the
7649 // inconsistent paths meet.
7650 P = PHIMap.lookup(OpInst);
7651 if (!P) {
7652 // Recurse and memoize the results, whether a phi is found or not.
7653 // This recursive call invalidates pointers into PHIMap.
7654 P = getConstantEvolvingPHIOperands(OpInst, L, PHIMap, Depth + 1);
7655 PHIMap[OpInst] = P;
7656 }
7657 if (!P)
7658 return nullptr; // Not evolving from PHI
7659 if (PHI && PHI != P)
7660 return nullptr; // Evolving from multiple different PHIs.
7661 PHI = P;
7662 }
7663 // This is a expression evolving from a constant PHI!
7664 return PHI;
7665}
7666
7667/// getConstantEvolvingPHI - Given an LLVM value and a loop, return a PHI node
7668/// in the loop that V is derived from. We allow arbitrary operations along the
7669/// way, but the operands of an operation must either be constants or a value
7670/// derived from a constant PHI. If this expression does not fit with these
7671/// constraints, return null.
7672static PHINode *getConstantEvolvingPHI(Value *V, const Loop *L) {
7673 Instruction *I = dyn_cast<Instruction>(V);
7674 if (!I || !canConstantEvolve(I, L)) return nullptr;
7675
7676 if (PHINode *PN = dyn_cast<PHINode>(I))
7677 return PN;
7678
7679 // Record non-constant instructions contained by the loop.
7680 DenseMap<Instruction *, PHINode *> PHIMap;
7681 return getConstantEvolvingPHIOperands(I, L, PHIMap, 0);
7682}
7683
7684/// EvaluateExpression - Given an expression that passes the
7685/// getConstantEvolvingPHI predicate, evaluate its value assuming the PHI node
7686/// in the loop has the value PHIVal. If we can't fold this expression for some
7687/// reason, return null.
7688static Constant *EvaluateExpression(Value *V, const Loop *L,
7689 DenseMap<Instruction *, Constant *> &Vals,
7690 const DataLayout &DL,
7691 const TargetLibraryInfo *TLI) {
7692 // Convenient constant check, but redundant for recursive calls.
7693 if (Constant *C = dyn_cast<Constant>(V)) return C;
7694 Instruction *I = dyn_cast<Instruction>(V);
7695 if (!I) return nullptr;
7696
7697 if (Constant *C = Vals.lookup(I)) return C;
7698
7699 // An instruction inside the loop depends on a value outside the loop that we
7700 // weren't given a mapping for, or a value such as a call inside the loop.
7701 if (!canConstantEvolve(I, L)) return nullptr;
7702
7703 // An unmapped PHI can be due to a branch or another loop inside this loop,
7704 // or due to this not being the initial iteration through a loop where we
7705 // couldn't compute the evolution of this particular PHI last time.
7706 if (isa<PHINode>(I)) return nullptr;
7707
7708 std::vector<Constant*> Operands(I->getNumOperands());
7709
7710 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
7711 Instruction *Operand = dyn_cast<Instruction>(I->getOperand(i));
7712 if (!Operand) {
7713 Operands[i] = dyn_cast<Constant>(I->getOperand(i));
7714 if (!Operands[i]) return nullptr;
7715 continue;
7716 }
7717 Constant *C = EvaluateExpression(Operand, L, Vals, DL, TLI);
7718 Vals[Operand] = C;
7719 if (!C) return nullptr;
7720 Operands[i] = C;
7721 }
7722
7723 if (CmpInst *CI = dyn_cast<CmpInst>(I))
7724 return ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0],
7725 Operands[1], DL, TLI);
7726 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
7727 if (!LI->isVolatile())
7728 return ConstantFoldLoadFromConstPtr(Operands[0], LI->getType(), DL);
7729 }
7730 return ConstantFoldInstOperands(I, Operands, DL, TLI);
7731}
7732
7733
7734// If every incoming value to PN except the one for BB is a specific Constant,
7735// return that, else return nullptr.
7736static Constant *getOtherIncomingValue(PHINode *PN, BasicBlock *BB) {
7737 Constant *IncomingVal = nullptr;
7738
7739 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
7740 if (PN->getIncomingBlock(i) == BB)
7741 continue;
7742
7743 auto *CurrentVal = dyn_cast<Constant>(PN->getIncomingValue(i));
7744 if (!CurrentVal)
7745 return nullptr;
7746
7747 if (IncomingVal != CurrentVal) {
7748 if (IncomingVal)
7749 return nullptr;
7750 IncomingVal = CurrentVal;
7751 }
7752 }
7753
7754 return IncomingVal;
7755}
7756
7757/// getConstantEvolutionLoopExitValue - If we know that the specified Phi is
7758/// in the header of its containing loop, we know the loop executes a
7759/// constant number of times, and the PHI node is just a recurrence
7760/// involving constants, fold it.
7761Constant *
7762ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN,
7763 const APInt &BEs,
7764 const Loop *L) {
7765 auto I = ConstantEvolutionLoopExitValue.find(PN);
7766 if (I != ConstantEvolutionLoopExitValue.end())
7767 return I->second;
7768
7769 if (BEs.ugt(MaxBruteForceIterations))
7770 return ConstantEvolutionLoopExitValue[PN] = nullptr; // Not going to evaluate it.
7771
7772 Constant *&RetVal = ConstantEvolutionLoopExitValue[PN];
7773
7774 DenseMap<Instruction *, Constant *> CurrentIterVals;
7775 BasicBlock *Header = L->getHeader();
7776 assert(PN->getParent() == Header && "Can't evaluate PHI not in loop header!")((PN->getParent() == Header && "Can't evaluate PHI not in loop header!"
) ? static_cast<void> (0) : __assert_fail ("PN->getParent() == Header && \"Can't evaluate PHI not in loop header!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7776, __PRETTY_FUNCTION__))
;
7777
7778 BasicBlock *Latch = L->getLoopLatch();
7779 if (!Latch)
7780 return nullptr;
7781
7782 for (PHINode &PHI : Header->phis()) {
7783 if (auto *StartCST = getOtherIncomingValue(&PHI, Latch))
7784 CurrentIterVals[&PHI] = StartCST;
7785 }
7786 if (!CurrentIterVals.count(PN))
7787 return RetVal = nullptr;
7788
7789 Value *BEValue = PN->getIncomingValueForBlock(Latch);
7790
7791 // Execute the loop symbolically to determine the exit value.
7792 assert(BEs.getActiveBits() < CHAR_BIT * sizeof(unsigned) &&((BEs.getActiveBits() < 8 * sizeof(unsigned) && "BEs is <= MaxBruteForceIterations which is an 'unsigned'!"
) ? static_cast<void> (0) : __assert_fail ("BEs.getActiveBits() < CHAR_BIT * sizeof(unsigned) && \"BEs is <= MaxBruteForceIterations which is an 'unsigned'!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7793, __PRETTY_FUNCTION__))
7793 "BEs is <= MaxBruteForceIterations which is an 'unsigned'!")((BEs.getActiveBits() < 8 * sizeof(unsigned) && "BEs is <= MaxBruteForceIterations which is an 'unsigned'!"
) ? static_cast<void> (0) : __assert_fail ("BEs.getActiveBits() < CHAR_BIT * sizeof(unsigned) && \"BEs is <= MaxBruteForceIterations which is an 'unsigned'!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7793, __PRETTY_FUNCTION__))
;
7794
7795 unsigned NumIterations = BEs.getZExtValue(); // must be in range
7796 unsigned IterationNum = 0;
7797 const DataLayout &DL = getDataLayout();
7798 for (; ; ++IterationNum) {
7799 if (IterationNum == NumIterations)
7800 return RetVal = CurrentIterVals[PN]; // Got exit value!
7801
7802 // Compute the value of the PHIs for the next iteration.
7803 // EvaluateExpression adds non-phi values to the CurrentIterVals map.
7804 DenseMap<Instruction *, Constant *> NextIterVals;
7805 Constant *NextPHI =
7806 EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
7807 if (!NextPHI)
7808 return nullptr; // Couldn't evaluate!
7809 NextIterVals[PN] = NextPHI;
7810
7811 bool StoppedEvolving = NextPHI == CurrentIterVals[PN];
7812
7813 // Also evaluate the other PHI nodes. However, we don't get to stop if we
7814 // cease to be able to evaluate one of them or if they stop evolving,
7815 // because that doesn't necessarily prevent us from computing PN.
7816 SmallVector<std::pair<PHINode *, Constant *>, 8> PHIsToCompute;
7817 for (const auto &I : CurrentIterVals) {
7818 PHINode *PHI = dyn_cast<PHINode>(I.first);
7819 if (!PHI || PHI == PN || PHI->getParent() != Header) continue;
7820 PHIsToCompute.emplace_back(PHI, I.second);
7821 }
7822 // We use two distinct loops because EvaluateExpression may invalidate any
7823 // iterators into CurrentIterVals.
7824 for (const auto &I : PHIsToCompute) {
7825 PHINode *PHI = I.first;
7826 Constant *&NextPHI = NextIterVals[PHI];
7827 if (!NextPHI) { // Not already computed.
7828 Value *BEValue = PHI->getIncomingValueForBlock(Latch);
7829 NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
7830 }
7831 if (NextPHI != I.second)
7832 StoppedEvolving = false;
7833 }
7834
7835 // If all entries in CurrentIterVals == NextIterVals then we can stop
7836 // iterating, the loop can't continue to change.
7837 if (StoppedEvolving)
7838 return RetVal = CurrentIterVals[PN];
7839
7840 CurrentIterVals.swap(NextIterVals);
7841 }
7842}
7843
7844const SCEV *ScalarEvolution::computeExitCountExhaustively(const Loop *L,
7845 Value *Cond,
7846 bool ExitWhen) {
7847 PHINode *PN = getConstantEvolvingPHI(Cond, L);
7848 if (!PN) return getCouldNotCompute();
7849
7850 // If the loop is canonicalized, the PHI will have exactly two entries.
7851 // That's the only form we support here.
7852 if (PN->getNumIncomingValues() != 2) return getCouldNotCompute();
7853
7854 DenseMap<Instruction *, Constant *> CurrentIterVals;
7855 BasicBlock *Header = L->getHeader();
7856 assert(PN->getParent() == Header && "Can't evaluate PHI not in loop header!")((PN->getParent() == Header && "Can't evaluate PHI not in loop header!"
) ? static_cast<void> (0) : __assert_fail ("PN->getParent() == Header && \"Can't evaluate PHI not in loop header!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7856, __PRETTY_FUNCTION__))
;
7857
7858 BasicBlock *Latch = L->getLoopLatch();
7859 assert(Latch && "Should follow from NumIncomingValues == 2!")((Latch && "Should follow from NumIncomingValues == 2!"
) ? static_cast<void> (0) : __assert_fail ("Latch && \"Should follow from NumIncomingValues == 2!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7859, __PRETTY_FUNCTION__))
;
7860
7861 for (PHINode &PHI : Header->phis()) {
7862 if (auto *StartCST = getOtherIncomingValue(&PHI, Latch))
7863 CurrentIterVals[&PHI] = StartCST;
7864 }
7865 if (!CurrentIterVals.count(PN))
7866 return getCouldNotCompute();
7867
7868 // Okay, we find a PHI node that defines the trip count of this loop. Execute
7869 // the loop symbolically to determine when the condition gets a value of
7870 // "ExitWhen".
7871 unsigned MaxIterations = MaxBruteForceIterations; // Limit analysis.
7872 const DataLayout &DL = getDataLayout();
7873 for (unsigned IterationNum = 0; IterationNum != MaxIterations;++IterationNum){
7874 auto *CondVal = dyn_cast_or_null<ConstantInt>(
7875 EvaluateExpression(Cond, L, CurrentIterVals, DL, &TLI));
7876
7877 // Couldn't symbolically evaluate.
7878 if (!CondVal) return getCouldNotCompute();
7879
7880 if (CondVal->getValue() == uint64_t(ExitWhen)) {
7881 ++NumBruteForceTripCountsComputed;
7882 return getConstant(Type::getInt32Ty(getContext()), IterationNum);
7883 }
7884
7885 // Update all the PHI nodes for the next iteration.
7886 DenseMap<Instruction *, Constant *> NextIterVals;
7887
7888 // Create a list of which PHIs we need to compute. We want to do this before
7889 // calling EvaluateExpression on them because that may invalidate iterators
7890 // into CurrentIterVals.
7891 SmallVector<PHINode *, 8> PHIsToCompute;
7892 for (const auto &I : CurrentIterVals) {
7893 PHINode *PHI = dyn_cast<PHINode>(I.first);
7894 if (!PHI || PHI->getParent() != Header) continue;
7895 PHIsToCompute.push_back(PHI);
7896 }
7897 for (PHINode *PHI : PHIsToCompute) {
7898 Constant *&NextPHI = NextIterVals[PHI];
7899 if (NextPHI) continue; // Already computed!
7900
7901 Value *BEValue = PHI->getIncomingValueForBlock(Latch);
7902 NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
7903 }
7904 CurrentIterVals.swap(NextIterVals);
7905 }
7906
7907 // Too many iterations were needed to evaluate.
7908 return getCouldNotCompute();
7909}
7910
7911const SCEV *ScalarEvolution::getSCEVAtScope(const SCEV *V, const Loop *L) {
7912 SmallVector<std::pair<const Loop *, const SCEV *>, 2> &Values =
7913 ValuesAtScopes[V];
7914 // Check to see if we've folded this expression at this loop before.
7915 for (auto &LS : Values)
7916 if (LS.first == L)
7917 return LS.second ? LS.second : V;
7918
7919 Values.emplace_back(L, nullptr);
7920
7921 // Otherwise compute it.
7922 const SCEV *C = computeSCEVAtScope(V, L);
7923 for (auto &LS : reverse(ValuesAtScopes[V]))
7924 if (LS.first == L) {
7925 LS.second = C;
7926 break;
7927 }
7928 return C;
7929}
7930
7931/// This builds up a Constant using the ConstantExpr interface. That way, we
7932/// will return Constants for objects which aren't represented by a
7933/// SCEVConstant, because SCEVConstant is restricted to ConstantInt.
7934/// Returns NULL if the SCEV isn't representable as a Constant.
7935static Constant *BuildConstantFromSCEV(const SCEV *V) {
7936 switch (static_cast<SCEVTypes>(V->getSCEVType())) {
7937 case scCouldNotCompute:
7938 case scAddRecExpr:
7939 break;
7940 case scConstant:
7941 return cast<SCEVConstant>(V)->getValue();
7942 case scUnknown:
7943 return dyn_cast<Constant>(cast<SCEVUnknown>(V)->getValue());
7944 case scSignExtend: {
7945 const SCEVSignExtendExpr *SS = cast<SCEVSignExtendExpr>(V);
7946 if (Constant *CastOp = BuildConstantFromSCEV(SS->getOperand()))
7947 return ConstantExpr::getSExt(CastOp, SS->getType());
7948 break;
7949 }
7950 case scZeroExtend: {
7951 const SCEVZeroExtendExpr *SZ = cast<SCEVZeroExtendExpr>(V);
7952 if (Constant *CastOp = BuildConstantFromSCEV(SZ->getOperand()))
7953 return ConstantExpr::getZExt(CastOp, SZ->getType());
7954 break;
7955 }
7956 case scTruncate: {
7957 const SCEVTruncateExpr *ST = cast<SCEVTruncateExpr>(V);
7958 if (Constant *CastOp = BuildConstantFromSCEV(ST->getOperand()))
7959 return ConstantExpr::getTrunc(CastOp, ST->getType());
7960 break;
7961 }
7962 case scAddExpr: {
7963 const SCEVAddExpr *SA = cast<SCEVAddExpr>(V);
7964 if (Constant *C = BuildConstantFromSCEV(SA->getOperand(0))) {
7965 if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) {
7966 unsigned AS = PTy->getAddressSpace();
7967 Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS);
7968 C = ConstantExpr::getBitCast(C, DestPtrTy);
7969 }
7970 for (unsigned i = 1, e = SA->getNumOperands(); i != e; ++i) {
7971 Constant *C2 = BuildConstantFromSCEV(SA->getOperand(i));
7972 if (!C2) return nullptr;
7973
7974 // First pointer!
7975 if (!C->getType()->isPointerTy() && C2->getType()->isPointerTy()) {
7976 unsigned AS = C2->getType()->getPointerAddressSpace();
7977 std::swap(C, C2);
7978 Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS);
7979 // The offsets have been converted to bytes. We can add bytes to an
7980 // i8* by GEP with the byte count in the first index.
7981 C = ConstantExpr::getBitCast(C, DestPtrTy);
7982 }
7983
7984 // Don't bother trying to sum two pointers. We probably can't
7985 // statically compute a load that results from it anyway.
7986 if (C2->getType()->isPointerTy())
7987 return nullptr;
7988
7989 if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) {
7990 if (PTy->getElementType()->isStructTy())
7991 C2 = ConstantExpr::getIntegerCast(
7992 C2, Type::getInt32Ty(C->getContext()), true);
7993 C = ConstantExpr::getGetElementPtr(PTy->getElementType(), C, C2);
7994 } else
7995 C = ConstantExpr::getAdd(C, C2);
7996 }
7997 return C;
7998 }
7999 break;
8000 }
8001 case scMulExpr: {
8002 const SCEVMulExpr *SM = cast<SCEVMulExpr>(V);
8003 if (Constant *C = BuildConstantFromSCEV(SM->getOperand(0))) {
8004 // Don't bother with pointers at all.
8005 if (C->getType()->isPointerTy()) return nullptr;
8006 for (unsigned i = 1, e = SM->getNumOperands(); i != e; ++i) {
8007 Constant *C2 = BuildConstantFromSCEV(SM->getOperand(i));
8008 if (!C2 || C2->getType()->isPointerTy()) return nullptr;
8009 C = ConstantExpr::getMul(C, C2);
8010 }
8011 return C;
8012 }
8013 break;
8014 }
8015 case scUDivExpr: {
8016 const SCEVUDivExpr *SU = cast<SCEVUDivExpr>(V);
8017 if (Constant *LHS = BuildConstantFromSCEV(SU->getLHS()))
8018 if (Constant *RHS = BuildConstantFromSCEV(SU->getRHS()))
8019 if (LHS->getType() == RHS->getType())
8020 return ConstantExpr::getUDiv(LHS, RHS);
8021 break;
8022 }
8023 case scSMaxExpr:
8024 case scUMaxExpr:
8025 case scSMinExpr:
8026 case scUMinExpr:
8027 break; // TODO: smax, umax, smin, umax.
8028 }
8029 return nullptr;
8030}
8031
8032const SCEV *ScalarEvolution::computeSCEVAtScope(const SCEV *V, const Loop *L) {
8033 if (isa<SCEVConstant>(V)) return V;
8034
8035 // If this instruction is evolved from a constant-evolving PHI, compute the
8036 // exit value from the loop without using SCEVs.
8037 if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(V)) {
8038 if (Instruction *I = dyn_cast<Instruction>(SU->getValue())) {
8039 if (PHINode *PN = dyn_cast<PHINode>(I)) {
8040 const Loop *CurrLoop = this->LI[I->getParent()];
8041 // Looking for loop exit value.
8042 if (CurrLoop && CurrLoop->getParentLoop() == L &&
8043 PN->getParent() == CurrLoop->getHeader()) {
8044 // Okay, there is no closed form solution for the PHI node. Check
8045 // to see if the loop that contains it has a known backedge-taken
8046 // count. If so, we may be able to force computation of the exit
8047 // value.
8048 const SCEV *BackedgeTakenCount = getBackedgeTakenCount(CurrLoop);
8049 // This trivial case can show up in some degenerate cases where
8050 // the incoming IR has not yet been fully simplified.
8051 if (BackedgeTakenCount->isZero()) {
8052 Value *InitValue = nullptr;
8053 bool MultipleInitValues = false;
8054 for (unsigned i = 0; i < PN->getNumIncomingValues(); i++) {
8055 if (!CurrLoop->contains(PN->getIncomingBlock(i))) {
8056 if (!InitValue)
8057 InitValue = PN->getIncomingValue(i);
8058 else if (InitValue != PN->getIncomingValue(i)) {
8059 MultipleInitValues = true;
8060 break;
8061 }
8062 }
8063 }
8064 if (!MultipleInitValues && InitValue)
8065 return getSCEV(InitValue);
8066 }
8067 // Do we have a loop invariant value flowing around the backedge
8068 // for a loop which must execute the backedge?
8069 if (!isa<SCEVCouldNotCompute>(BackedgeTakenCount) &&
8070 isKnownPositive(BackedgeTakenCount) &&
8071 PN->getNumIncomingValues() == 2) {
8072
8073 unsigned InLoopPred =
8074 CurrLoop->contains(PN->getIncomingBlock(0)) ? 0 : 1;
8075 Value *BackedgeVal = PN->getIncomingValue(InLoopPred);
8076 if (CurrLoop->isLoopInvariant(BackedgeVal))
8077 return getSCEV(BackedgeVal);
8078 }
8079 if (auto *BTCC = dyn_cast<SCEVConstant>(BackedgeTakenCount)) {
8080 // Okay, we know how many times the containing loop executes. If
8081 // this is a constant evolving PHI node, get the final value at
8082 // the specified iteration number.
8083 Constant *RV = getConstantEvolutionLoopExitValue(
8084 PN, BTCC->getAPInt(), CurrLoop);
8085 if (RV) return getSCEV(RV);
8086 }
8087 }
8088
8089 // If there is a single-input Phi, evaluate it at our scope. If we can
8090 // prove that this replacement does not break LCSSA form, use new value.
8091 if (PN->getNumOperands() == 1) {
8092 const SCEV *Input = getSCEV(PN->getOperand(0));
8093 const SCEV *InputAtScope = getSCEVAtScope(Input, L);
8094 // TODO: We can generalize it using LI.replacementPreservesLCSSAForm,
8095 // for the simplest case just support constants.
8096 if (isa<SCEVConstant>(InputAtScope)) return InputAtScope;
8097 }
8098 }
8099
8100 // Okay, this is an expression that we cannot symbolically evaluate
8101 // into a SCEV. Check to see if it's possible to symbolically evaluate
8102 // the arguments into constants, and if so, try to constant propagate the
8103 // result. This is particularly useful for computing loop exit values.
8104 if (CanConstantFold(I)) {
8105 SmallVector<Constant *, 4> Operands;
8106 bool MadeImprovement = false;
8107 for (Value *Op : I->operands()) {
8108 if (Constant *C = dyn_cast<Constant>(Op)) {
8109 Operands.push_back(C);
8110 continue;
8111 }
8112
8113 // If any of the operands is non-constant and if they are
8114 // non-integer and non-pointer, don't even try to analyze them
8115 // with scev techniques.
8116 if (!isSCEVable(Op->getType()))
8117 return V;
8118
8119 const SCEV *OrigV = getSCEV(Op);
8120 const SCEV *OpV = getSCEVAtScope(OrigV, L);
8121 MadeImprovement |= OrigV != OpV;
8122
8123 Constant *C = BuildConstantFromSCEV(OpV);
8124 if (!C) return V;
8125 if (C->getType() != Op->getType())
8126 C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
8127 Op->getType(),
8128 false),
8129 C, Op->getType());
8130 Operands.push_back(C);
8131 }
8132
8133 // Check to see if getSCEVAtScope actually made an improvement.
8134 if (MadeImprovement) {
8135 Constant *C = nullptr;
8136 const DataLayout &DL = getDataLayout();
8137 if (const CmpInst *CI = dyn_cast<CmpInst>(I))
8138 C = ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0],
8139 Operands[1], DL, &TLI);
8140 else if (const LoadInst *Load = dyn_cast<LoadInst>(I)) {
8141 if (!Load->isVolatile())
8142 C = ConstantFoldLoadFromConstPtr(Operands[0], Load->getType(),
8143 DL);
8144 } else
8145 C = ConstantFoldInstOperands(I, Operands, DL, &TLI);
8146 if (!C) return V;
8147 return getSCEV(C);
8148 }
8149 }
8150 }
8151
8152 // This is some other type of SCEVUnknown, just return it.
8153 return V;
8154 }
8155
8156 if (const SCEVCommutativeExpr *Comm = dyn_cast<SCEVCommutativeExpr>(V)) {
8157 // Avoid performing the look-up in the common case where the specified
8158 // expression has no loop-variant portions.
8159 for (unsigned i = 0, e = Comm->getNumOperands(); i != e; ++i) {
8160 const SCEV *OpAtScope = getSCEVAtScope(Comm->getOperand(i), L);
8161 if (OpAtScope != Comm->getOperand(i)) {
8162 // Okay, at least one of these operands is loop variant but might be
8163 // foldable. Build a new instance of the folded commutative expression.
8164 SmallVector<const SCEV *, 8> NewOps(Comm->op_begin(),
8165 Comm->op_begin()+i);
8166 NewOps.push_back(OpAtScope);
8167
8168 for (++i; i != e; ++i) {
8169 OpAtScope = getSCEVAtScope(Comm->getOperand(i), L);
8170 NewOps.push_back(OpAtScope);
8171 }
8172 if (isa<SCEVAddExpr>(Comm))
8173 return getAddExpr(NewOps, Comm->getNoWrapFlags());
8174 if (isa<SCEVMulExpr>(Comm))
8175 return getMulExpr(NewOps, Comm->getNoWrapFlags());
8176 if (isa<SCEVMinMaxExpr>(Comm))
8177 return getMinMaxExpr(Comm->getSCEVType(), NewOps);
8178 llvm_unreachable("Unknown commutative SCEV type!")::llvm::llvm_unreachable_internal("Unknown commutative SCEV type!"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8178)
;
8179 }
8180 }
8181 // If we got here, all operands are loop invariant.
8182 return Comm;
8183 }
8184
8185 if (const SCEVUDivExpr *Div = dyn_cast<SCEVUDivExpr>(V)) {
8186 const SCEV *LHS = getSCEVAtScope(Div->getLHS(), L);
8187 const SCEV *RHS = getSCEVAtScope(Div->getRHS(), L);
8188 if (LHS == Div->getLHS() && RHS == Div->getRHS())
8189 return Div; // must be loop invariant
8190 return getUDivExpr(LHS, RHS);
8191 }
8192
8193 // If this is a loop recurrence for a loop that does not contain L, then we
8194 // are dealing with the final value computed by the loop.
8195 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(V)) {
8196 // First, attempt to evaluate each operand.
8197 // Avoid performing the look-up in the common case where the specified
8198 // expression has no loop-variant portions.
8199 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
8200 const SCEV *OpAtScope = getSCEVAtScope(AddRec->getOperand(i), L);
8201 if (OpAtScope == AddRec->getOperand(i))
8202 continue;
8203
8204 // Okay, at least one of these operands is loop variant but might be
8205 // foldable. Build a new instance of the folded commutative expression.
8206 SmallVector<const SCEV *, 8> NewOps(AddRec->op_begin(),
8207 AddRec->op_begin()+i);
8208 NewOps.push_back(OpAtScope);
8209 for (++i; i != e; ++i)
8210 NewOps.push_back(getSCEVAtScope(AddRec->getOperand(i), L));
8211
8212 const SCEV *FoldedRec =
8213 getAddRecExpr(NewOps, AddRec->getLoop(),
8214 AddRec->getNoWrapFlags(SCEV::FlagNW));
8215 AddRec = dyn_cast<SCEVAddRecExpr>(FoldedRec);
8216 // The addrec may be folded to a nonrecurrence, for example, if the
8217 // induction variable is multiplied by zero after constant folding. Go
8218 // ahead and return the folded value.
8219 if (!AddRec)
8220 return FoldedRec;
8221 break;
8222 }
8223
8224 // If the scope is outside the addrec's loop, evaluate it by using the
8225 // loop exit value of the addrec.
8226 if (!AddRec->getLoop()->contains(L)) {
8227 // To evaluate this recurrence, we need to know how many times the AddRec
8228 // loop iterates. Compute this now.
8229 const SCEV *BackedgeTakenCount = getBackedgeTakenCount(AddRec->getLoop());
8230 if (BackedgeTakenCount == getCouldNotCompute()) return AddRec;
8231
8232 // Then, evaluate the AddRec.
8233 return AddRec->evaluateAtIteration(BackedgeTakenCount, *this);
8234 }
8235
8236 return AddRec;
8237 }
8238
8239 if (const SCEVZeroExtendExpr *Cast = dyn_cast<SCEVZeroExtendExpr>(V)) {
8240 const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
8241 if (Op == Cast->getOperand())
8242 return Cast; // must be loop invariant
8243 return getZeroExtendExpr(Op, Cast->getType());
8244 }
8245
8246 if (const SCEVSignExtendExpr *Cast = dyn_cast<SCEVSignExtendExpr>(V)) {
8247 const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
8248 if (Op == Cast->getOperand())
8249 return Cast; // must be loop invariant
8250 return getSignExtendExpr(Op, Cast->getType());
8251 }
8252
8253 if (const SCEVTruncateExpr *Cast = dyn_cast<SCEVTruncateExpr>(V)) {
8254 const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
8255 if (Op == Cast->getOperand())
8256 return Cast; // must be loop invariant
8257 return getTruncateExpr(Op, Cast->getType());
8258 }
8259
8260 llvm_unreachable("Unknown SCEV type!")::llvm::llvm_unreachable_internal("Unknown SCEV type!", "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8260)
;
8261}
8262
8263const SCEV *ScalarEvolution::getSCEVAtScope(Value *V, const Loop *L) {
8264 return getSCEVAtScope(getSCEV(V), L);
8265}
8266
8267const SCEV *ScalarEvolution::stripInjectiveFunctions(const SCEV *S) const {
8268 if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S))
8269 return stripInjectiveFunctions(ZExt->getOperand());
8270 if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S))
8271 return stripInjectiveFunctions(SExt->getOperand());
8272 return S;
8273}
8274
8275/// Finds the minimum unsigned root of the following equation:
8276///
8277/// A * X = B (mod N)
8278///
8279/// where N = 2^BW and BW is the common bit width of A and B. The signedness of
8280/// A and B isn't important.
8281///
8282/// If the equation does not have a solution, SCEVCouldNotCompute is returned.
8283static const SCEV *SolveLinEquationWithOverflow(const APInt &A, const SCEV *B,
8284 ScalarEvolution &SE) {
8285 uint32_t BW = A.getBitWidth();
8286 assert(BW == SE.getTypeSizeInBits(B->getType()))((BW == SE.getTypeSizeInBits(B->getType())) ? static_cast<
void> (0) : __assert_fail ("BW == SE.getTypeSizeInBits(B->getType())"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8286, __PRETTY_FUNCTION__))
;
8287 assert(A != 0 && "A must be non-zero.")((A != 0 && "A must be non-zero.") ? static_cast<void
> (0) : __assert_fail ("A != 0 && \"A must be non-zero.\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8287, __PRETTY_FUNCTION__))
;
8288
8289 // 1. D = gcd(A, N)
8290 //
8291 // The gcd of A and N may have only one prime factor: 2. The number of
8292 // trailing zeros in A is its multiplicity
8293 uint32_t Mult2 = A.countTrailingZeros();
8294 // D = 2^Mult2
8295
8296 // 2. Check if B is divisible by D.
8297 //
8298 // B is divisible by D if and only if the multiplicity of prime factor 2 for B
8299 // is not less than multiplicity of this prime factor for D.
8300 if (SE.GetMinTrailingZeros(B) < Mult2)
8301 return SE.getCouldNotCompute();
8302
8303 // 3. Compute I: the multiplicative inverse of (A / D) in arithmetic
8304 // modulo (N / D).
8305 //
8306 // If D == 1, (N / D) == N == 2^BW, so we need one extra bit to represent
8307 // (N / D) in general. The inverse itself always fits into BW bits, though,
8308 // so we immediately truncate it.
8309 APInt AD = A.lshr(Mult2).zext(BW + 1); // AD = A / D
8310 APInt Mod(BW + 1, 0);
8311 Mod.setBit(BW - Mult2); // Mod = N / D
8312 APInt I = AD.multiplicativeInverse(Mod).trunc(BW);
8313
8314 // 4. Compute the minimum unsigned root of the equation:
8315 // I * (B / D) mod (N / D)
8316 // To simplify the computation, we factor out the divide by D:
8317 // (I * B mod N) / D
8318 const SCEV *D = SE.getConstant(APInt::getOneBitSet(BW, Mult2));
8319 return SE.getUDivExactExpr(SE.getMulExpr(B, SE.getConstant(I)), D);
8320}
8321
8322/// For a given quadratic addrec, generate coefficients of the corresponding
8323/// quadratic equation, multiplied by a common value to ensure that they are
8324/// integers.
8325/// The returned value is a tuple { A, B, C, M, BitWidth }, where
8326/// Ax^2 + Bx + C is the quadratic function, M is the value that A, B and C
8327/// were multiplied by, and BitWidth is the bit width of the original addrec
8328/// coefficients.
8329/// This function returns None if the addrec coefficients are not compile-
8330/// time constants.
8331static Optional<std::tuple<APInt, APInt, APInt, APInt, unsigned>>
8332GetQuadraticEquation(const SCEVAddRecExpr *AddRec) {
8333 assert(AddRec->getNumOperands() == 3 && "This is not a quadratic chrec!")((AddRec->getNumOperands() == 3 && "This is not a quadratic chrec!"
) ? static_cast<void> (0) : __assert_fail ("AddRec->getNumOperands() == 3 && \"This is not a quadratic chrec!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8333, __PRETTY_FUNCTION__))
;
8334 const SCEVConstant *LC = dyn_cast<SCEVConstant>(AddRec->getOperand(0));
8335 const SCEVConstant *MC = dyn_cast<SCEVConstant>(AddRec->getOperand(1));
8336 const SCEVConstant *NC = dyn_cast<SCEVConstant>(AddRec->getOperand(2));
8337 LLVM_DEBUG(dbgs() << __func__ << ": analyzing quadratic addrec: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": analyzing quadratic addrec: "
<< *AddRec << '\n'; } } while (false)
8338 << *AddRec << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": analyzing quadratic addrec: "
<< *AddRec << '\n'; } } while (false)
;
8339
8340 // We currently can only solve this if the coefficients are constants.
8341 if (!LC || !MC || !NC) {
8342 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)
;
8343 return None;
8344 }
8345
8346 APInt L = LC->getAPInt();
8347 APInt M = MC->getAPInt();
8348 APInt N = NC->getAPInt();
8349 assert(!N.isNullValue() && "This is not a quadratic addrec")((!N.isNullValue() && "This is not a quadratic addrec"
) ? static_cast<void> (0) : __assert_fail ("!N.isNullValue() && \"This is not a quadratic addrec\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8349, __PRETTY_FUNCTION__))
;
8350
8351 unsigned BitWidth = LC->getAPInt().getBitWidth();
8352 unsigned NewWidth = BitWidth + 1;
8353 LLVM_DEBUG(dbgs() << __func__ << ": addrec coeff bw: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": addrec coeff bw: "
<< BitWidth << '\n'; } } while (false)
8354 << BitWidth << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": addrec coeff bw: "
<< BitWidth << '\n'; } } while (false)
;
8355 // The sign-extension (as opposed to a zero-extension) here matches the
8356 // extension used in SolveQuadraticEquationWrap (with the same motivation).
8357 N = N.sext(NewWidth);
8358 M = M.sext(NewWidth);
8359 L = L.sext(NewWidth);
8360
8361 // The increments are M, M+N, M+2N, ..., so the accumulated values are
8362 // L+M, (L+M)+(M+N), (L+M)+(M+N)+(M+2N), ..., that is,
8363 // L+M, L+2M+N, L+3M+3N, ...
8364 // After n iterations the accumulated value Acc is L + nM + n(n-1)/2 N.
8365 //
8366 // The equation Acc = 0 is then
8367 // L + nM + n(n-1)/2 N = 0, or 2L + 2M n + n(n-1) N = 0.
8368 // In a quadratic form it becomes:
8369 // N n^2 + (2M-N) n + 2L = 0.
8370
8371 APInt A = N;
8372 APInt B = 2 * M - A;
8373 APInt C = 2 * L;
8374 APInt T = APInt(NewWidth, 2);
8375 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)
8376 << "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)
8377 << ", 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)
;
8378 return std::make_tuple(A, B, C, T, BitWidth);
8379}
8380
8381/// Helper function to compare optional APInts:
8382/// (a) if X and Y both exist, return min(X, Y),
8383/// (b) if neither X nor Y exist, return None,
8384/// (c) if exactly one of X and Y exists, return that value.
8385static Optional<APInt> MinOptional(Optional<APInt> X, Optional<APInt> Y) {
8386 if (X.hasValue() && Y.hasValue()) {
8387 unsigned W = std::max(X->getBitWidth(), Y->getBitWidth());
8388 APInt XW = X->sextOrSelf(W);
8389 APInt YW = Y->sextOrSelf(W);
8390 return XW.slt(YW) ? *X : *Y;
8391 }
8392 if (!X.hasValue() && !Y.hasValue())
8393 return None;
8394 return X.hasValue() ? *X : *Y;
8395}
8396
8397/// Helper function to truncate an optional APInt to a given BitWidth.
8398/// When solving addrec-related equations, it is preferable to return a value
8399/// that has the same bit width as the original addrec's coefficients. If the
8400/// solution fits in the original bit width, truncate it (except for i1).
8401/// Returning a value of a different bit width may inhibit some optimizations.
8402///
8403/// In general, a solution to a quadratic equation generated from an addrec
8404/// may require BW+1 bits, where BW is the bit width of the addrec's
8405/// coefficients. The reason is that the coefficients of the quadratic
8406/// equation are BW+1 bits wide (to avoid truncation when converting from
8407/// the addrec to the equation).
8408static Optional<APInt> TruncIfPossible(Optional<APInt> X, unsigned BitWidth) {
8409 if (!X.hasValue())
8410 return None;
8411 unsigned W = X->getBitWidth();
8412 if (BitWidth > 1 && BitWidth < W && X->isIntN(BitWidth))
8413 return X->trunc(BitWidth);
8414 return X;
8415}
8416
8417/// Let c(n) be the value of the quadratic chrec {L,+,M,+,N} after n
8418/// iterations. The values L, M, N are assumed to be signed, and they
8419/// should all have the same bit widths.
8420/// Find the least n >= 0 such that c(n) = 0 in the arithmetic modulo 2^BW,
8421/// where BW is the bit width of the addrec's coefficients.
8422/// If the calculated value is a BW-bit integer (for BW > 1), it will be
8423/// returned as such, otherwise the bit width of the returned value may
8424/// be greater than BW.
8425///
8426/// This function returns None if
8427/// (a) the addrec coefficients are not constant, or
8428/// (b) SolveQuadraticEquationWrap was unable to find a solution. For cases
8429/// like x^2 = 5, no integer solutions exist, in other cases an integer
8430/// solution may exist, but SolveQuadraticEquationWrap may fail to find it.
8431static Optional<APInt>
8432SolveQuadraticAddRecExact(const SCEVAddRecExpr *AddRec, ScalarEvolution &SE) {
8433 APInt A, B, C, M;
8434 unsigned BitWidth;
8435 auto T = GetQuadraticEquation(AddRec);
8436 if (!T.hasValue())
8437 return None;
8438
8439 std::tie(A, B, C, M, BitWidth) = *T;
8440 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)
;
8441 Optional<APInt> X = APIntOps::SolveQuadraticEquationWrap(A, B, C, BitWidth+1);
8442 if (!X.hasValue())
8443 return None;
8444
8445 ConstantInt *CX = ConstantInt::get(SE.getContext(), *X);
8446 ConstantInt *V = EvaluateConstantChrecAtConstant(AddRec, CX, SE);
8447 if (!V->isZero())
8448 return None;
8449
8450 return TruncIfPossible(X, BitWidth);
8451}
8452
8453/// Let c(n) be the value of the quadratic chrec {0,+,M,+,N} after n
8454/// iterations. The values M, N are assumed to be signed, and they
8455/// should all have the same bit widths.
8456/// Find the least n such that c(n) does not belong to the given range,
8457/// while c(n-1) does.
8458///
8459/// This function returns None if
8460/// (a) the addrec coefficients are not constant, or
8461/// (b) SolveQuadraticEquationWrap was unable to find a solution for the
8462/// bounds of the range.
8463static Optional<APInt>
8464SolveQuadraticAddRecRange(const SCEVAddRecExpr *AddRec,
8465 const ConstantRange &Range, ScalarEvolution &SE) {
8466 assert(AddRec->getOperand(0)->isZero() &&((AddRec->getOperand(0)->isZero() && "Starting value of addrec should be 0"
) ? static_cast<void> (0) : __assert_fail ("AddRec->getOperand(0)->isZero() && \"Starting value of addrec should be 0\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8467, __PRETTY_FUNCTION__))
8467 "Starting value of addrec should be 0")((AddRec->getOperand(0)->isZero() && "Starting value of addrec should be 0"
) ? static_cast<void> (0) : __assert_fail ("AddRec->getOperand(0)->isZero() && \"Starting value of addrec should be 0\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8467, __PRETTY_FUNCTION__))
;
8468 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)
8469 << 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)
;
8470 // This case is handled in getNumIterationsInRange. Here we can assume that
8471 // we start in the range.
8472 assert(Range.contains(APInt(SE.getTypeSizeInBits(AddRec->getType()), 0)) &&((Range.contains(APInt(SE.getTypeSizeInBits(AddRec->getType
()), 0)) && "Addrec's initial value should be in range"
) ? static_cast<void> (0) : __assert_fail ("Range.contains(APInt(SE.getTypeSizeInBits(AddRec->getType()), 0)) && \"Addrec's initial value should be in range\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8473, __PRETTY_FUNCTION__))
8473 "Addrec's initial value should be in range")((Range.contains(APInt(SE.getTypeSizeInBits(AddRec->getType
()), 0)) && "Addrec's initial value should be in range"
) ? static_cast<void> (0) : __assert_fail ("Range.contains(APInt(SE.getTypeSizeInBits(AddRec->getType()), 0)) && \"Addrec's initial value should be in range\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8473, __PRETTY_FUNCTION__))
;
8474
8475 APInt A, B, C, M;
8476 unsigned BitWidth;
8477 auto T = GetQuadraticEquation(AddRec);
8478 if (!T.hasValue())
8479 return None;
8480
8481 // Be careful about the return value: there can be two reasons for not
8482 // returning an actual number. First, if no solutions to the equations
8483 // were found, and second, if the solutions don't leave the given range.
8484 // The first case means that the actual solution is "unknown", the second
8485 // means that it's known, but not valid. If the solution is unknown, we
8486 // cannot make any conclusions.
8487 // Return a pair: the optional solution and a flag indicating if the
8488 // solution was found.
8489 auto SolveForBoundary = [&](APInt Bound) -> std::pair<Optional<APInt>,bool> {
8490 // Solve for signed overflow and unsigned overflow, pick the lower
8491 // solution.
8492 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)
8493 << 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)
;
8494 Bound *= M; // The quadratic equation multiplier.
8495
8496 Optional<APInt> SO = None;
8497 if (BitWidth > 1) {
8498 LLVM_DEBUG(dbgs() << "SolveQuadraticAddRecRange: solving for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for "
"signed overflow\n"; } } while (false)
8499 "signed overflow\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for "
"signed overflow\n"; } } while (false)
;
8500 SO = APIntOps::SolveQuadraticEquationWrap(A, B, -Bound, BitWidth);
8501 }
8502 LLVM_DEBUG(dbgs() << "SolveQuadraticAddRecRange: solving for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for "
"unsigned overflow\n"; } } while (false)
8503 "unsigned overflow\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for "
"unsigned overflow\n"; } } while (false)
;
8504 Optional<APInt> UO = APIntOps::SolveQuadraticEquationWrap(A, B, -Bound,
8505 BitWidth+1);
8506
8507 auto LeavesRange = [&] (const APInt &X) {
8508 ConstantInt *C0 = ConstantInt::get(SE.getContext(), X);
8509 ConstantInt *V0 = EvaluateConstantChrecAtConstant(AddRec, C0, SE);
8510 if (Range.contains(V0->getValue()))
8511 return false;
8512 // X should be at least 1, so X-1 is non-negative.
8513 ConstantInt *C1 = ConstantInt::get(SE.getContext(), X-1);
8514 ConstantInt *V1 = EvaluateConstantChrecAtConstant(AddRec, C1, SE);
8515 if (Range.contains(V1->getValue()))
8516 return true;
8517 return false;
8518 };
8519
8520 // If SolveQuadraticEquationWrap returns None, it means that there can
8521 // be a solution, but the function failed to find it. We cannot treat it
8522 // as "no solution".
8523 if (!SO.hasValue() || !UO.hasValue())
8524 return { None, false };
8525
8526 // Check the smaller value first to see if it leaves the range.
8527 // At this point, both SO and UO must have values.
8528 Optional<APInt> Min = MinOptional(SO, UO);
8529 if (LeavesRange(*Min))
8530 return { Min, true };
8531 Optional<APInt> Max = Min == SO ? UO : SO;
8532 if (LeavesRange(*Max))
8533 return { Max, true };
8534
8535 // Solutions were found, but were eliminated, hence the "true".
8536 return { None, true };
8537 };
8538
8539 std::tie(A, B, C, M, BitWidth) = *T;
8540 // Lower bound is inclusive, subtract 1 to represent the exiting value.
8541 APInt Lower = Range.getLower().sextOrSelf(A.getBitWidth()) - 1;
8542 APInt Upper = Range.getUpper().sextOrSelf(A.getBitWidth());
8543 auto SL = SolveForBoundary(Lower);
8544 auto SU = SolveForBoundary(Upper);
8545 // If any of the solutions was unknown, no meaninigful conclusions can
8546 // be made.
8547 if (!SL.second || !SU.second)
8548 return None;
8549
8550 // Claim: The correct solution is not some value between Min and Max.
8551 //
8552 // Justification: Assuming that Min and Max are different values, one of
8553 // them is when the first signed overflow happens, the other is when the
8554 // first unsigned overflow happens. Crossing the range boundary is only
8555 // possible via an overflow (treating 0 as a special case of it, modeling
8556 // an overflow as crossing k*2^W for some k).
8557 //
8558 // The interesting case here is when Min was eliminated as an invalid
8559 // solution, but Max was not. The argument is that if there was another
8560 // overflow between Min and Max, it would also have been eliminated if
8561 // it was considered.
8562 //
8563 // For a given boundary, it is possible to have two overflows of the same
8564 // type (signed/unsigned) without having the other type in between: this
8565 // can happen when the vertex of the parabola is between the iterations
8566 // corresponding to the overflows. This is only possible when the two
8567 // overflows cross k*2^W for the same k. In such case, if the second one
8568 // left the range (and was the first one to do so), the first overflow
8569 // would have to enter the range, which would mean that either we had left
8570 // the range before or that we started outside of it. Both of these cases
8571 // are contradictions.
8572 //
8573 // Claim: In the case where SolveForBoundary returns None, the correct
8574 // solution is not some value between the Max for this boundary and the
8575 // Min of the other boundary.
8576 //
8577 // Justification: Assume that we had such Max_A and Min_B corresponding
8578 // to range boundaries A and B and such that Max_A < Min_B. If there was
8579 // a solution between Max_A and Min_B, it would have to be caused by an
8580 // overflow corresponding to either A or B. It cannot correspond to B,
8581 // since Min_B is the first occurrence of such an overflow. If it
8582 // corresponded to A, it would have to be either a signed or an unsigned
8583 // overflow that is larger than both eliminated overflows for A. But
8584 // between the eliminated overflows and this overflow, the values would
8585 // cover the entire value space, thus crossing the other boundary, which
8586 // is a contradiction.
8587
8588 return TruncIfPossible(MinOptional(SL.first, SU.first), BitWidth);
8589}
8590
8591ScalarEvolution::ExitLimit
8592ScalarEvolution::howFarToZero(const SCEV *V, const Loop *L, bool ControlsExit,
8593 bool AllowPredicates) {
8594
8595 // This is only used for loops with a "x != y" exit test. The exit condition
8596 // is now expressed as a single expression, V = x-y. So the exit test is
8597 // effectively V != 0. We know and take advantage of the fact that this
8598 // expression only being used in a comparison by zero context.
8599
8600 SmallPtrSet<const SCEVPredicate *, 4> Predicates;
8601 // If the value is a constant
8602 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
8603 // If the value is already zero, the branch will execute zero times.
8604 if (C->getValue()->isZero()) return C;
8605 return getCouldNotCompute(); // Otherwise it will loop infinitely.
8606 }
8607
8608 const SCEVAddRecExpr *AddRec =
8609 dyn_cast<SCEVAddRecExpr>(stripInjectiveFunctions(V));
8610
8611 if (!AddRec && AllowPredicates)
8612 // Try to make this an AddRec using runtime tests, in the first X
8613 // iterations of this loop, where X is the SCEV expression found by the
8614 // algorithm below.
8615 AddRec = convertSCEVToAddRecWithPredicates(V, L, Predicates);
8616
8617 if (!AddRec || AddRec->getLoop() != L)
8618 return getCouldNotCompute();
8619
8620 // If this is a quadratic (3-term) AddRec {L,+,M,+,N}, find the roots of
8621 // the quadratic equation to solve it.
8622 if (AddRec->isQuadratic() && AddRec->getType()->isIntegerTy()) {
8623 // We can only use this value if the chrec ends up with an exact zero
8624 // value at this index. When solving for "X*X != 5", for example, we
8625 // should not accept a root of 2.
8626 if (auto S = SolveQuadraticAddRecExact(AddRec, *this)) {
8627 const auto *R = cast<SCEVConstant>(getConstant(S.getValue()));
8628 return ExitLimit(R, R, false, Predicates);
8629 }
8630 return getCouldNotCompute();
8631 }
8632
8633 // Otherwise we can only handle this if it is affine.
8634 if (!AddRec->isAffine())
8635 return getCouldNotCompute();
8636
8637 // If this is an affine expression, the execution count of this branch is
8638 // the minimum unsigned root of the following equation:
8639 //
8640 // Start + Step*N = 0 (mod 2^BW)
8641 //
8642 // equivalent to:
8643 //
8644 // Step*N = -Start (mod 2^BW)
8645 //
8646 // where BW is the common bit width of Start and Step.
8647
8648 // Get the initial value for the loop.
8649 const SCEV *Start = getSCEVAtScope(AddRec->getStart(), L->getParentLoop());
8650 const SCEV *Step = getSCEVAtScope(AddRec->getOperand(1), L->getParentLoop());
8651
8652 // For now we handle only constant steps.
8653 //
8654 // TODO: Handle a nonconstant Step given AddRec<NUW>. If the
8655 // AddRec is NUW, then (in an unsigned sense) it cannot be counting up to wrap
8656 // to 0, it must be counting down to equal 0. Consequently, N = Start / -Step.
8657 // We have not yet seen any such cases.
8658 const SCEVConstant *StepC = dyn_cast<SCEVConstant>(Step);
8659 if (!StepC || StepC->getValue()->isZero())
8660 return getCouldNotCompute();
8661
8662 // For positive steps (counting up until unsigned overflow):
8663 // N = -Start/Step (as unsigned)
8664 // For negative steps (counting down to zero):
8665 // N = Start/-Step
8666 // First compute the unsigned distance from zero in the direction of Step.
8667 bool CountDown = StepC->getAPInt().isNegative();
8668 const SCEV *Distance = CountDown ? Start : getNegativeSCEV(Start);
8669
8670 // Handle unitary steps, which cannot wraparound.
8671 // 1*N = -Start; -1*N = Start (mod 2^BW), so:
8672 // N = Distance (as unsigned)
8673 if (StepC->getValue()->isOne() || StepC->getValue()->isMinusOne()) {
8674 APInt MaxBECount = getUnsignedRangeMax(Distance);
8675
8676 // When a loop like "for (int i = 0; i != n; ++i) { /* body */ }" is rotated,
8677 // we end up with a loop whose backedge-taken count is n - 1. Detect this
8678 // case, and see if we can improve the bound.
8679 //
8680 // Explicitly handling this here is necessary because getUnsignedRange
8681 // isn't context-sensitive; it doesn't know that we only care about the
8682 // range inside the loop.
8683 const SCEV *Zero = getZero(Distance->getType());
8684 const SCEV *One = getOne(Distance->getType());
8685 const SCEV *DistancePlusOne = getAddExpr(Distance, One);
8686 if (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_NE, DistancePlusOne, Zero)) {
8687 // If Distance + 1 doesn't overflow, we can compute the maximum distance
8688 // as "unsigned_max(Distance + 1) - 1".
8689 ConstantRange CR = getUnsignedRange(DistancePlusOne);
8690 MaxBECount = APIntOps::umin(MaxBECount, CR.getUnsignedMax() - 1);
8691 }
8692 return ExitLimit(Distance, getConstant(MaxBECount), false, Predicates);
8693 }
8694
8695 // If the condition controls loop exit (the loop exits only if the expression
8696 // is true) and the addition is no-wrap we can use unsigned divide to
8697 // compute the backedge count. In this case, the step may not divide the
8698 // distance, but we don't care because if the condition is "missed" the loop
8699 // will have undefined behavior due to wrapping.
8700 if (ControlsExit && AddRec->hasNoSelfWrap() &&
8701 loopHasNoAbnormalExits(AddRec->getLoop())) {
8702 const SCEV *Exact =
8703 getUDivExpr(Distance, CountDown ? getNegativeSCEV(Step) : Step);
8704 const SCEV *Max =
8705 Exact == getCouldNotCompute()
8706 ? Exact
8707 : getConstant(getUnsignedRangeMax(Exact));
8708 return ExitLimit(Exact, Max, false, Predicates);
8709 }
8710
8711 // Solve the general equation.
8712 const SCEV *E = SolveLinEquationWithOverflow(StepC->getAPInt(),
8713 getNegativeSCEV(Start), *this);
8714 const SCEV *M = E == getCouldNotCompute()
8715 ? E
8716 : getConstant(getUnsignedRangeMax(E));
8717 return ExitLimit(E, M, false, Predicates);
8718}
8719
8720ScalarEvolution::ExitLimit
8721ScalarEvolution::howFarToNonZero(const SCEV *V, const Loop *L) {
8722 // Loops that look like: while (X == 0) are very strange indeed. We don't
8723 // handle them yet except for the trivial case. This could be expanded in the
8724 // future as needed.
8725
8726 // If the value is a constant, check to see if it is known to be non-zero
8727 // already. If so, the backedge will execute zero times.
8728 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
8729 if (!C->getValue()->isZero())
8730 return getZero(C->getType());
8731 return getCouldNotCompute(); // Otherwise it will loop infinitely.
8732 }
8733
8734 // We could implement others, but I really doubt anyone writes loops like
8735 // this, and if they did, they would already be constant folded.
8736 return getCouldNotCompute();
8737}
8738
8739std::pair<const BasicBlock *, const BasicBlock *>
8740ScalarEvolution::getPredecessorWithUniqueSuccessorForBB(const BasicBlock *BB)
8741 const {
8742 // If the block has a unique predecessor, then there is no path from the
8743 // predecessor to the block that does not go through the direct edge
8744 // from the predecessor to the block.
8745 if (const BasicBlock *Pred = BB->getSinglePredecessor())
8746 return {Pred, BB};
8747
8748 // A loop's header is defined to be a block that dominates the loop.
8749 // If the header has a unique predecessor outside the loop, it must be
8750 // a block that has exactly one successor that can reach the loop.
8751 if (const Loop *L = LI.getLoopFor(BB))
8752 return {L->getLoopPredecessor(), L->getHeader()};
8753
8754 return {nullptr, nullptr};
8755}
8756
8757/// SCEV structural equivalence is usually sufficient for testing whether two
8758/// expressions are equal, however for the purposes of looking for a condition
8759/// guarding a loop, it can be useful to be a little more general, since a
8760/// front-end may have replicated the controlling expression.
8761static bool HasSameValue(const SCEV *A, const SCEV *B) {
8762 // Quick check to see if they are the same SCEV.
8763 if (A == B) return true;
8764
8765 auto ComputesEqualValues = [](const Instruction *A, const Instruction *B) {
8766 // Not all instructions that are "identical" compute the same value. For
8767 // instance, two distinct alloca instructions allocating the same type are
8768 // identical and do not read memory; but compute distinct values.
8769 return A->isIdenticalTo(B) && (isa<BinaryOperator>(A) || isa<GetElementPtrInst>(A));
8770 };
8771
8772 // Otherwise, if they're both SCEVUnknown, it's possible that they hold
8773 // two different instructions with the same value. Check for this case.
8774 if (const SCEVUnknown *AU = dyn_cast<SCEVUnknown>(A))
8775 if (const SCEVUnknown *BU = dyn_cast<SCEVUnknown>(B))
8776 if (const Instruction *AI = dyn_cast<Instruction>(AU->getValue()))
8777 if (const Instruction *BI = dyn_cast<Instruction>(BU->getValue()))
8778 if (ComputesEqualValues(AI, BI))
8779 return true;
8780
8781 // Otherwise assume they may have a different value.
8782 return false;
8783}
8784
8785bool ScalarEvolution::SimplifyICmpOperands(ICmpInst::Predicate &Pred,
8786 const SCEV *&LHS, const SCEV *&RHS,
8787 unsigned Depth) {
8788 bool Changed = false;
8789 // Simplifies ICMP to trivial true or false by turning it into '0 == 0' or
8790 // '0 != 0'.
8791 auto TrivialCase = [&](bool TriviallyTrue) {
8792 LHS = RHS = getConstant(ConstantInt::getFalse(getContext()));
8793 Pred = TriviallyTrue ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE;
8794 return true;
8795 };
8796 // If we hit the max recursion limit bail out.
8797 if (Depth >= 3)
8798 return false;
8799
8800 // Canonicalize a constant to the right side.
8801 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
8802 // Check for both operands constant.
8803 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
8804 if (ConstantExpr::getICmp(Pred,
8805 LHSC->getValue(),
8806 RHSC->getValue())->isNullValue())
8807 return TrivialCase(false);
8808 else
8809 return TrivialCase(true);
8810 }
8811 // Otherwise swap the operands to put the constant on the right.
8812 std::swap(LHS, RHS);
8813 Pred = ICmpInst::getSwappedPredicate(Pred);
8814 Changed = true;
8815 }
8816
8817 // If we're comparing an addrec with a value which is loop-invariant in the
8818 // addrec's loop, put the addrec on the left. Also make a dominance check,
8819 // as both operands could be addrecs loop-invariant in each other's loop.
8820 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(RHS)) {
8821 const Loop *L = AR->getLoop();
8822 if (isLoopInvariant(LHS, L) && properlyDominates(LHS, L->getHeader())) {
8823 std::swap(LHS, RHS);
8824 Pred = ICmpInst::getSwappedPredicate(Pred);
8825 Changed = true;
8826 }
8827 }
8828
8829 // If there's a constant operand, canonicalize comparisons with boundary
8830 // cases, and canonicalize *-or-equal comparisons to regular comparisons.
8831 if (const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS)) {
8832 const APInt &RA = RC->getAPInt();
8833
8834 bool SimplifiedByConstantRange = false;
8835
8836 if (!ICmpInst::isEquality(Pred)) {
8837 ConstantRange ExactCR = ConstantRange::makeExactICmpRegion(Pred, RA);
8838 if (ExactCR.isFullSet())
8839 return TrivialCase(true);
8840 else if (ExactCR.isEmptySet())
8841 return TrivialCase(false);
8842
8843 APInt NewRHS;
8844 CmpInst::Predicate NewPred;
8845 if (ExactCR.getEquivalentICmp(NewPred, NewRHS) &&
8846 ICmpInst::isEquality(NewPred)) {
8847 // We were able to convert an inequality to an equality.
8848 Pred = NewPred;
8849 RHS = getConstant(NewRHS);
8850 Changed = SimplifiedByConstantRange = true;
8851 }
8852 }
8853
8854 if (!SimplifiedByConstantRange) {
8855 switch (Pred) {
8856 default:
8857 break;
8858 case ICmpInst::ICMP_EQ:
8859 case ICmpInst::ICMP_NE:
8860 // Fold ((-1) * %a) + %b == 0 (equivalent to %b-%a == 0) into %a == %b.
8861 if (!RA)
8862 if (const SCEVAddExpr *AE = dyn_cast<SCEVAddExpr>(LHS))
8863 if (const SCEVMulExpr *ME =
8864 dyn_cast<SCEVMulExpr>(AE->getOperand(0)))
8865 if (AE->getNumOperands() == 2 && ME->getNumOperands() == 2 &&
8866 ME->getOperand(0)->isAllOnesValue()) {
8867 RHS = AE->getOperand(1);
8868 LHS = ME->getOperand(1);
8869 Changed = true;
8870 }
8871 break;
8872
8873
8874 // The "Should have been caught earlier!" messages refer to the fact
8875 // that the ExactCR.isFullSet() or ExactCR.isEmptySet() check above
8876 // should have fired on the corresponding cases, and canonicalized the
8877 // check to trivial case.
8878
8879 case ICmpInst::ICMP_UGE:
8880 assert(!RA.isMinValue() && "Should have been caught earlier!")((!RA.isMinValue() && "Should have been caught earlier!"
) ? static_cast<void> (0) : __assert_fail ("!RA.isMinValue() && \"Should have been caught earlier!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8880, __PRETTY_FUNCTION__))
;
8881 Pred = ICmpInst::ICMP_UGT;
8882 RHS = getConstant(RA - 1);
8883 Changed = true;
8884 break;
8885 case ICmpInst::ICMP_ULE:
8886 assert(!RA.isMaxValue() && "Should have been caught earlier!")((!RA.isMaxValue() && "Should have been caught earlier!"
) ? static_cast<void> (0) : __assert_fail ("!RA.isMaxValue() && \"Should have been caught earlier!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8886, __PRETTY_FUNCTION__))
;
8887 Pred = ICmpInst::ICMP_ULT;
8888 RHS = getConstant(RA + 1);
8889 Changed = true;
8890 break;
8891 case ICmpInst::ICMP_SGE:
8892 assert(!RA.isMinSignedValue() && "Should have been caught earlier!")((!RA.isMinSignedValue() && "Should have been caught earlier!"
) ? static_cast<void> (0) : __assert_fail ("!RA.isMinSignedValue() && \"Should have been caught earlier!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8892, __PRETTY_FUNCTION__))
;
8893 Pred = ICmpInst::ICMP_SGT;
8894 RHS = getConstant(RA - 1);
8895 Changed = true;
8896 break;
8897 case ICmpInst::ICMP_SLE:
8898 assert(!RA.isMaxSignedValue() && "Should have been caught earlier!")((!RA.isMaxSignedValue() && "Should have been caught earlier!"
) ? static_cast<void> (0) : __assert_fail ("!RA.isMaxSignedValue() && \"Should have been caught earlier!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8898, __PRETTY_FUNCTION__))
;
8899 Pred = ICmpInst::ICMP_SLT;
8900 RHS = getConstant(RA + 1);
8901 Changed = true;
8902 break;
8903 }
8904 }
8905 }
8906
8907 // Check for obvious equality.
8908 if (HasSameValue(LHS, RHS)) {
8909 if (ICmpInst::isTrueWhenEqual(Pred))
8910 return TrivialCase(true);
8911 if (ICmpInst::isFalseWhenEqual(Pred))
8912 return TrivialCase(false);
8913 }
8914
8915 // If possible, canonicalize GE/LE comparisons to GT/LT comparisons, by
8916 // adding or subtracting 1 from one of the operands.
8917 switch (Pred) {
8918 case ICmpInst::ICMP_SLE:
8919 if (!getSignedRangeMax(RHS).isMaxSignedValue()) {
8920 RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
8921 SCEV::FlagNSW);
8922 Pred = ICmpInst::ICMP_SLT;
8923 Changed = true;
8924 } else if (!getSignedRangeMin(LHS).isMinSignedValue()) {
8925 LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS,
8926 SCEV::FlagNSW);
8927 Pred = ICmpInst::ICMP_SLT;
8928 Changed = true;
8929 }
8930 break;
8931 case ICmpInst::ICMP_SGE:
8932 if (!getSignedRangeMin(RHS).isMinSignedValue()) {
8933 RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS,
8934 SCEV::FlagNSW);
8935 Pred = ICmpInst::ICMP_SGT;
8936 Changed = true;
8937 } else if (!getSignedRangeMax(LHS).isMaxSignedValue()) {
8938 LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
8939 SCEV::FlagNSW);
8940 Pred = ICmpInst::ICMP_SGT;
8941 Changed = true;
8942 }
8943 break;
8944 case ICmpInst::ICMP_ULE:
8945 if (!getUnsignedRangeMax(RHS).isMaxValue()) {
8946 RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
8947 SCEV::FlagNUW);
8948 Pred = ICmpInst::ICMP_ULT;
8949 Changed = true;
8950 } else if (!getUnsignedRangeMin(LHS).isMinValue()) {
8951 LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS);
8952 Pred = ICmpInst::ICMP_ULT;
8953 Changed = true;
8954 }
8955 break;
8956 case ICmpInst::ICMP_UGE:
8957 if (!getUnsignedRangeMin(RHS).isMinValue()) {
8958 RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS);
8959 Pred = ICmpInst::ICMP_UGT;
8960 Changed = true;
8961 } else if (!getUnsignedRangeMax(LHS).isMaxValue()) {
8962 LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
8963 SCEV::FlagNUW);
8964 Pred = ICmpInst::ICMP_UGT;
8965 Changed = true;
8966 }
8967 break;
8968 default:
8969 break;
8970 }
8971
8972 // TODO: More simplifications are possible here.
8973
8974 // Recursively simplify until we either hit a recursion limit or nothing
8975 // changes.
8976 if (Changed)
8977 return SimplifyICmpOperands(Pred, LHS, RHS, Depth+1);
8978
8979 return Changed;
8980}
8981
8982bool ScalarEvolution::isKnownNegative(const SCEV *S) {
8983 return getSignedRangeMax(S).isNegative();
8984}
8985
8986bool ScalarEvolution::isKnownPositive(const SCEV *S) {
8987 return getSignedRangeMin(S).isStrictlyPositive();
8988}
8989
8990bool ScalarEvolution::isKnownNonNegative(const SCEV *S) {
8991 return !getSignedRangeMin(S).isNegative();
8992}
8993
8994bool ScalarEvolution::isKnownNonPositive(const SCEV *S) {
8995 return !getSignedRangeMax(S).isStrictlyPositive();
8996}
8997
8998bool ScalarEvolution::isKnownNonZero(const SCEV *S) {
8999 return isKnownNegative(S) || isKnownPositive(S);
9000}
9001
9002std::pair<const SCEV *, const SCEV *>
9003ScalarEvolution::SplitIntoInitAndPostInc(const Loop *L, const SCEV *S) {
9004 // Compute SCEV on entry of loop L.
9005 const SCEV *Start = SCEVInitRewriter::rewrite(S, L, *this);
9006 if (Start == getCouldNotCompute())
9007 return { Start, Start };
9008 // Compute post increment SCEV for loop L.
9009 const SCEV *PostInc = SCEVPostIncRewriter::rewrite(S, L, *this);
9010 assert(PostInc != getCouldNotCompute() && "Unexpected could not compute")((PostInc != getCouldNotCompute() && "Unexpected could not compute"
) ? static_cast<void> (0) : __assert_fail ("PostInc != getCouldNotCompute() && \"Unexpected could not compute\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9010, __PRETTY_FUNCTION__))
;
9011 return { Start, PostInc };
9012}
9013
9014bool ScalarEvolution::isKnownViaInduction(ICmpInst::Predicate Pred,
9015 const SCEV *LHS, const SCEV *RHS) {
9016 // First collect all loops.
9017 SmallPtrSet<const Loop *, 8> LoopsUsed;
9018 getUsedLoops(LHS, LoopsUsed);
9019 getUsedLoops(RHS, LoopsUsed);
9020
9021 if (LoopsUsed.empty())
9022 return false;
9023
9024 // Domination relationship must be a linear order on collected loops.
9025#ifndef NDEBUG
9026 for (auto *L1 : LoopsUsed)
9027 for (auto *L2 : LoopsUsed)
9028 assert((DT.dominates(L1->getHeader(), L2->getHeader()) ||(((DT.dominates(L1->getHeader(), L2->getHeader()) || DT
.dominates(L2->getHeader(), L1->getHeader())) &&
"Domination relationship is not a linear order") ? static_cast
<void> (0) : __assert_fail ("(DT.dominates(L1->getHeader(), L2->getHeader()) || DT.dominates(L2->getHeader(), L1->getHeader())) && \"Domination relationship is not a linear order\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9030, __PRETTY_FUNCTION__))
9029 DT.dominates(L2->getHeader(), L1->getHeader())) &&(((DT.dominates(L1->getHeader(), L2->getHeader()) || DT
.dominates(L2->getHeader(), L1->getHeader())) &&
"Domination relationship is not a linear order") ? static_cast
<void> (0) : __assert_fail ("(DT.dominates(L1->getHeader(), L2->getHeader()) || DT.dominates(L2->getHeader(), L1->getHeader())) && \"Domination relationship is not a linear order\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9030, __PRETTY_FUNCTION__))
9030 "Domination relationship is not a linear order")(((DT.dominates(L1->getHeader(), L2->getHeader()) || DT
.dominates(L2->getHeader(), L1->getHeader())) &&
"Domination relationship is not a linear order") ? static_cast
<void> (0) : __assert_fail ("(DT.dominates(L1->getHeader(), L2->getHeader()) || DT.dominates(L2->getHeader(), L1->getHeader())) && \"Domination relationship is not a linear order\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9030, __PRETTY_FUNCTION__))
;
9031#endif
9032
9033 const Loop *MDL =
9034 *std::max_element(LoopsUsed.begin(), LoopsUsed.end(),
9035 [&](const Loop *L1, const Loop *L2) {
9036 return DT.properlyDominates(L1->getHeader(), L2->getHeader());
9037 });
9038
9039 // Get init and post increment value for LHS.
9040 auto SplitLHS = SplitIntoInitAndPostInc(MDL, LHS);
9041 // if LHS contains unknown non-invariant SCEV then bail out.
9042 if (SplitLHS.first == getCouldNotCompute())
9043 return false;
9044 assert (SplitLHS.second != getCouldNotCompute() && "Unexpected CNC")((SplitLHS.second != getCouldNotCompute() && "Unexpected CNC"
) ? static_cast<void> (0) : __assert_fail ("SplitLHS.second != getCouldNotCompute() && \"Unexpected CNC\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9044, __PRETTY_FUNCTION__))
;
9045 // Get init and post increment value for RHS.
9046 auto SplitRHS = SplitIntoInitAndPostInc(MDL, RHS);
9047 // if RHS contains unknown non-invariant SCEV then bail out.
9048 if (SplitRHS.first == getCouldNotCompute())
9049 return false;
9050 assert (SplitRHS.second != getCouldNotCompute() && "Unexpected CNC")((SplitRHS.second != getCouldNotCompute() && "Unexpected CNC"
) ? static_cast<void> (0) : __assert_fail ("SplitRHS.second != getCouldNotCompute() && \"Unexpected CNC\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9050, __PRETTY_FUNCTION__))
;
9051 // It is possible that init SCEV contains an invariant load but it does
9052 // not dominate MDL and is not available at MDL loop entry, so we should
9053 // check it here.
9054 if (!isAvailableAtLoopEntry(SplitLHS.first, MDL) ||
9055 !isAvailableAtLoopEntry(SplitRHS.first, MDL))
9056 return false;
9057
9058 // It seems backedge guard check is faster than entry one so in some cases
9059 // it can speed up whole estimation by short circuit
9060 return isLoopBackedgeGuardedByCond(MDL, Pred, SplitLHS.second,
9061 SplitRHS.second) &&
9062 isLoopEntryGuardedByCond(MDL, Pred, SplitLHS.first, SplitRHS.first);
9063}
9064
9065bool ScalarEvolution::isKnownPredicate(ICmpInst::Predicate Pred,
9066 const SCEV *LHS, const SCEV *RHS) {
9067 // Canonicalize the inputs first.
9068 (void)SimplifyICmpOperands(Pred, LHS, RHS);
9069
9070 if (isKnownViaInduction(Pred, LHS, RHS))
9071 return true;
9072
9073 if (isKnownPredicateViaSplitting(Pred, LHS, RHS))
9074 return true;
9075
9076 // Otherwise see what can be done with some simple reasoning.
9077 return isKnownViaNonRecursiveReasoning(Pred, LHS, RHS);
9078}
9079
9080bool ScalarEvolution::isKnownOnEveryIteration(ICmpInst::Predicate Pred,
9081 const SCEVAddRecExpr *LHS,
9082 const SCEV *RHS) {
9083 const Loop *L = LHS->getLoop();
9084 return isLoopEntryGuardedByCond(L, Pred, LHS->getStart(), RHS) &&
9085 isLoopBackedgeGuardedByCond(L, Pred, LHS->getPostIncExpr(*this), RHS);
9086}
9087
9088bool ScalarEvolution::isMonotonicPredicate(const SCEVAddRecExpr *LHS,
9089 ICmpInst::Predicate Pred,
9090 bool &Increasing) {
9091 bool Result = isMonotonicPredicateImpl(LHS, Pred, Increasing);
9092
9093#ifndef NDEBUG
9094 // Verify an invariant: inverting the predicate should turn a monotonically
9095 // increasing change to a monotonically decreasing one, and vice versa.
9096 bool IncreasingSwapped;
9097 bool ResultSwapped = isMonotonicPredicateImpl(
9098 LHS, ICmpInst::getSwappedPredicate(Pred), IncreasingSwapped);
9099
9100 assert(Result == ResultSwapped && "should be able to analyze both!")((Result == ResultSwapped && "should be able to analyze both!"
) ? static_cast<void> (0) : __assert_fail ("Result == ResultSwapped && \"should be able to analyze both!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9100, __PRETTY_FUNCTION__))
;
9101 if (ResultSwapped)
9102 assert(Increasing == !IncreasingSwapped &&((Increasing == !IncreasingSwapped && "monotonicity should flip as we flip the predicate"
) ? static_cast<void> (0) : __assert_fail ("Increasing == !IncreasingSwapped && \"monotonicity should flip as we flip the predicate\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9103, __PRETTY_FUNCTION__))
9103 "monotonicity should flip as we flip the predicate")((Increasing == !IncreasingSwapped && "monotonicity should flip as we flip the predicate"
) ? static_cast<void> (0) : __assert_fail ("Increasing == !IncreasingSwapped && \"monotonicity should flip as we flip the predicate\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9103, __PRETTY_FUNCTION__))
;
9104#endif
9105
9106 return Result;
9107}
9108
9109bool ScalarEvolution::isMonotonicPredicateImpl(const SCEVAddRecExpr *LHS,
9110 ICmpInst::Predicate Pred,
9111 bool &Increasing) {
9112
9113 // A zero step value for LHS means the induction variable is essentially a
9114 // loop invariant value. We don't really depend on the predicate actually
9115 // flipping from false to true (for increasing predicates, and the other way
9116 // around for decreasing predicates), all we care about is that *if* the
9117 // predicate changes then it only changes from false to true.
9118 //
9119 // A zero step value in itself is not very useful, but there may be places
9120 // where SCEV can prove X >= 0 but not prove X > 0, so it is helpful to be
9121 // as general as possible.
9122
9123 switch (Pred) {
9124 default:
9125 return false; // Conservative answer
9126
9127 case ICmpInst::ICMP_UGT:
9128 case ICmpInst::ICMP_UGE:
9129 case ICmpInst::ICMP_ULT:
9130 case ICmpInst::ICMP_ULE:
9131 if (!LHS->hasNoUnsignedWrap())
9132 return false;
9133
9134 Increasing = Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE;
9135 return true;
9136
9137 case ICmpInst::ICMP_SGT:
9138 case ICmpInst::ICMP_SGE:
9139 case ICmpInst::ICMP_SLT:
9140 case ICmpInst::ICMP_SLE: {
9141 if (!LHS->hasNoSignedWrap())
9142 return false;
9143
9144 const SCEV *Step = LHS->getStepRecurrence(*this);
9145
9146 if (isKnownNonNegative(Step)) {
9147 Increasing = Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE;
9148 return true;
9149 }
9150
9151 if (isKnownNonPositive(Step)) {
9152 Increasing = Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE;
9153 return true;
9154 }
9155
9156 return false;
9157 }
9158
9159 }
9160
9161 llvm_unreachable("switch has default clause!")::llvm::llvm_unreachable_internal("switch has default clause!"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9161)
;
9162}
9163
9164bool ScalarEvolution::isLoopInvariantPredicate(
9165 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS, const Loop *L,
9166 ICmpInst::Predicate &InvariantPred, const SCEV *&InvariantLHS,
9167 const SCEV *&InvariantRHS) {
9168
9169 // If there is a loop-invariant, force it into the RHS, otherwise bail out.
9170 if (!isLoopInvariant(RHS, L)) {
9171 if (!isLoopInvariant(LHS, L))
9172 return false;
9173
9174 std::swap(LHS, RHS);
9175 Pred = ICmpInst::getSwappedPredicate(Pred);
9176 }
9177
9178 const SCEVAddRecExpr *ArLHS = dyn_cast<SCEVAddRecExpr>(LHS);
9179 if (!ArLHS || ArLHS->getLoop() != L)
9180 return false;
9181
9182 bool Increasing;
9183 if (!isMonotonicPredicate(ArLHS, Pred, Increasing))
9184 return false;
9185
9186 // If the predicate "ArLHS `Pred` RHS" monotonically increases from false to
9187 // true as the loop iterates, and the backedge is control dependent on
9188 // "ArLHS `Pred` RHS" == true then we can reason as follows:
9189 //
9190 // * if the predicate was false in the first iteration then the predicate
9191 // is never evaluated again, since the loop exits without taking the
9192 // backedge.
9193 // * if the predicate was true in the first iteration then it will
9194 // continue to be true for all future iterations since it is
9195 // monotonically increasing.
9196 //
9197 // For both the above possibilities, we can replace the loop varying
9198 // predicate with its value on the first iteration of the loop (which is
9199 // loop invariant).
9200 //
9201 // A similar reasoning applies for a monotonically decreasing predicate, by
9202 // replacing true with false and false with true in the above two bullets.
9203
9204 auto P = Increasing ? Pred : ICmpInst::getInversePredicate(Pred);
9205
9206 if (!isLoopBackedgeGuardedByCond(L, P, LHS, RHS))
9207 return false;
9208
9209 InvariantPred = Pred;
9210 InvariantLHS = ArLHS->getStart();
9211 InvariantRHS = RHS;
9212 return true;
9213}
9214
9215bool ScalarEvolution::isKnownPredicateViaConstantRanges(
9216 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS) {
9217 if (HasSameValue(LHS, RHS))
9218 return ICmpInst::isTrueWhenEqual(Pred);
9219
9220 // This code is split out from isKnownPredicate because it is called from
9221 // within isLoopEntryGuardedByCond.
9222
9223 auto CheckRanges =
9224 [&](const ConstantRange &RangeLHS, const ConstantRange &RangeRHS) {
9225 return ConstantRange::makeSatisfyingICmpRegion(Pred, RangeRHS)
9226 .contains(RangeLHS);
9227 };
9228
9229 // The check at the top of the function catches the case where the values are
9230 // known to be equal.
9231 if (Pred == CmpInst::ICMP_EQ)
9232 return false;
9233
9234 if (Pred == CmpInst::ICMP_NE)
9235 return CheckRanges(getSignedRange(LHS), getSignedRange(RHS)) ||
9236 CheckRanges(getUnsignedRange(LHS), getUnsignedRange(RHS)) ||
9237 isKnownNonZero(getMinusSCEV(LHS, RHS));
9238
9239 if (CmpInst::isSigned(Pred))
9240 return CheckRanges(getSignedRange(LHS), getSignedRange(RHS));
9241
9242 return CheckRanges(getUnsignedRange(LHS), getUnsignedRange(RHS));
9243}
9244
9245bool ScalarEvolution::isKnownPredicateViaNoOverflow(ICmpInst::Predicate Pred,
9246 const SCEV *LHS,
9247 const SCEV *RHS) {
9248 // Match Result to (X + Y)<ExpectedFlags> where Y is a constant integer.
9249 // Return Y via OutY.
9250 auto MatchBinaryAddToConst =
9251 [this](const SCEV *Result, const SCEV *X, APInt &OutY,
9252 SCEV::NoWrapFlags ExpectedFlags) {
9253 const SCEV *NonConstOp, *ConstOp;
9254 SCEV::NoWrapFlags FlagsPresent;
9255
9256 if (!splitBinaryAdd(Result, ConstOp, NonConstOp, FlagsPresent) ||
9257 !isa<SCEVConstant>(ConstOp) || NonConstOp != X)
9258 return false;
9259
9260 OutY = cast<SCEVConstant>(ConstOp)->getAPInt();
9261 return (FlagsPresent & ExpectedFlags) == ExpectedFlags;
9262 };
9263
9264 APInt C;
9265
9266 switch (Pred) {
9267 default:
9268 break;
9269
9270 case ICmpInst::ICMP_SGE:
9271 std::swap(LHS, RHS);
9272 LLVM_FALLTHROUGH[[gnu::fallthrough]];
9273 case ICmpInst::ICMP_SLE:
9274 // X s<= (X + C)<nsw> if C >= 0
9275 if (MatchBinaryAddToConst(RHS, LHS, C, SCEV::FlagNSW) && C.isNonNegative())
9276 return true;
9277
9278 // (X + C)<nsw> s<= X if C <= 0
9279 if (MatchBinaryAddToConst(LHS, RHS, C, SCEV::FlagNSW) &&
9280 !C.isStrictlyPositive())
9281 return true;
9282 break;
9283
9284 case ICmpInst::ICMP_SGT:
9285 std::swap(LHS, RHS);
9286 LLVM_FALLTHROUGH[[gnu::fallthrough]];
9287 case ICmpInst::ICMP_SLT:
9288 // X s< (X + C)<nsw> if C > 0
9289 if (MatchBinaryAddToConst(RHS, LHS, C, SCEV::FlagNSW) &&
9290 C.isStrictlyPositive())
9291 return true;
9292
9293 // (X + C)<nsw> s< X if C < 0
9294 if (MatchBinaryAddToConst(LHS, RHS, C, SCEV::FlagNSW) && C.isNegative())
9295 return true;
9296 break;
9297 }
9298
9299 return false;
9300}
9301
9302bool ScalarEvolution::isKnownPredicateViaSplitting(ICmpInst::Predicate Pred,
9303 const SCEV *LHS,
9304 const SCEV *RHS) {
9305 if (Pred != ICmpInst::ICMP_ULT || ProvingSplitPredicate)
9306 return false;
9307
9308 // Allowing arbitrary number of activations of isKnownPredicateViaSplitting on
9309 // the stack can result in exponential time complexity.
9310 SaveAndRestore<bool> Restore(ProvingSplitPredicate, true);
9311
9312 // If L >= 0 then I `ult` L <=> I >= 0 && I `slt` L
9313 //
9314 // To prove L >= 0 we use isKnownNonNegative whereas to prove I >= 0 we use
9315 // isKnownPredicate. isKnownPredicate is more powerful, but also more
9316 // expensive; and using isKnownNonNegative(RHS) is sufficient for most of the
9317 // interesting cases seen in practice. We can consider "upgrading" L >= 0 to
9318 // use isKnownPredicate later if needed.
9319 return isKnownNonNegative(RHS) &&
9320 isKnownPredicate(CmpInst::ICMP_SGE, LHS, getZero(LHS->getType())) &&
9321 isKnownPredicate(CmpInst::ICMP_SLT, LHS, RHS);
9322}
9323
9324bool ScalarEvolution::isImpliedViaGuard(const BasicBlock *BB,
9325 ICmpInst::Predicate Pred,
9326 const SCEV *LHS, const SCEV *RHS) {
9327 // No need to even try if we know the module has no guards.
9328 if (!HasGuards)
9329 return false;
9330
9331 return any_of(*BB, [&](const Instruction &I) {
9332 using namespace llvm::PatternMatch;
9333
9334 Value *Condition;
9335 return match(&I, m_Intrinsic<Intrinsic::experimental_guard>(
9336 m_Value(Condition))) &&
9337 isImpliedCond(Pred, LHS, RHS, Condition, false);
9338 });
9339}
9340
9341/// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is
9342/// protected by a conditional between LHS and RHS. This is used to
9343/// to eliminate casts.
9344bool
9345ScalarEvolution::isLoopBackedgeGuardedByCond(const Loop *L,
9346 ICmpInst::Predicate Pred,
9347 const SCEV *LHS, const SCEV *RHS) {
9348 // Interpret a null as meaning no loop, where there is obviously no guard
9349 // (interprocedural conditions notwithstanding).
9350 if (!L) return true;
9351
9352 if (VerifyIR)
9353 assert(!verifyFunction(*L->getHeader()->getParent(), &dbgs()) &&((!verifyFunction(*L->getHeader()->getParent(), &dbgs
()) && "This cannot be done on broken IR!") ? static_cast
<void> (0) : __assert_fail ("!verifyFunction(*L->getHeader()->getParent(), &dbgs()) && \"This cannot be done on broken IR!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9354, __PRETTY_FUNCTION__))
9354 "This cannot be done on broken IR!")((!verifyFunction(*L->getHeader()->getParent(), &dbgs
()) && "This cannot be done on broken IR!") ? static_cast
<void> (0) : __assert_fail ("!verifyFunction(*L->getHeader()->getParent(), &dbgs()) && \"This cannot be done on broken IR!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9354, __PRETTY_FUNCTION__))
;
9355
9356
9357 if (isKnownViaNonRecursiveReasoning(Pred, LHS, RHS))
9358 return true;
9359
9360 BasicBlock *Latch = L->getLoopLatch();
9361 if (!Latch)
9362 return false;
9363
9364 BranchInst *LoopContinuePredicate =
9365 dyn_cast<BranchInst>(Latch->getTerminator());
9366 if (LoopContinuePredicate && LoopContinuePredicate->isConditional() &&
9367 isImpliedCond(Pred, LHS, RHS,
9368 LoopContinuePredicate->getCondition(),
9369 LoopContinuePredicate->getSuccessor(0) != L->getHeader()))
9370 return true;
9371
9372 // We don't want more than one activation of the following loops on the stack
9373 // -- that can lead to O(n!) time complexity.
9374 if (WalkingBEDominatingConds)
9375 return false;
9376
9377 SaveAndRestore<bool> ClearOnExit(WalkingBEDominatingConds, true);
9378
9379 // See if we can exploit a trip count to prove the predicate.
9380 const auto &BETakenInfo = getBackedgeTakenInfo(L);
9381 const SCEV *LatchBECount = BETakenInfo.getExact(Latch, this);
9382 if (LatchBECount != getCouldNotCompute()) {
9383 // We know that Latch branches back to the loop header exactly
9384 // LatchBECount times. This means the backdege condition at Latch is
9385 // equivalent to "{0,+,1} u< LatchBECount".
9386 Type *Ty = LatchBECount->getType();
9387 auto NoWrapFlags = SCEV::NoWrapFlags(SCEV::FlagNUW | SCEV::FlagNW);
9388 const SCEV *LoopCounter =
9389 getAddRecExpr(getZero(Ty), getOne(Ty), L, NoWrapFlags);
9390 if (isImpliedCond(Pred, LHS, RHS, ICmpInst::ICMP_ULT, LoopCounter,
9391 LatchBECount))
9392 return true;
9393 }
9394
9395 // Check conditions due to any @llvm.assume intrinsics.
9396 for (auto &AssumeVH : AC.assumptions()) {
9397 if (!AssumeVH)
9398 continue;
9399 auto *CI = cast<CallInst>(AssumeVH);
9400 if (!DT.dominates(CI, Latch->getTerminator()))
9401 continue;
9402
9403 if (isImpliedCond(Pred, LHS, RHS, CI->getArgOperand(0), false))
9404 return true;
9405 }
9406
9407 // If the loop is not reachable from the entry block, we risk running into an
9408 // infinite loop as we walk up into the dom tree. These loops do not matter
9409 // anyway, so we just return a conservative answer when we see them.
9410 if (!DT.isReachableFromEntry(L->getHeader()))
9411 return false;
9412
9413 if (isImpliedViaGuard(Latch, Pred, LHS, RHS))
9414 return true;
9415
9416 for (DomTreeNode *DTN = DT[Latch], *HeaderDTN = DT[L->getHeader()];
9417 DTN != HeaderDTN; DTN = DTN->getIDom()) {
9418 assert(DTN && "should reach the loop header before reaching the root!")((DTN && "should reach the loop header before reaching the root!"
) ? static_cast<void> (0) : __assert_fail ("DTN && \"should reach the loop header before reaching the root!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9418, __PRETTY_FUNCTION__))
;
9419
9420 BasicBlock *BB = DTN->getBlock();
9421 if (isImpliedViaGuard(BB, Pred, LHS, RHS))
9422 return true;
9423
9424 BasicBlock *PBB = BB->getSinglePredecessor();
9425 if (!PBB)
9426 continue;
9427
9428 BranchInst *ContinuePredicate = dyn_cast<BranchInst>(PBB->getTerminator());
9429 if (!ContinuePredicate || !ContinuePredicate->isConditional())
9430 continue;
9431
9432 Value *Condition = ContinuePredicate->getCondition();
9433
9434 // If we have an edge `E` within the loop body that dominates the only
9435 // latch, the condition guarding `E` also guards the backedge. This
9436 // reasoning works only for loops with a single latch.
9437
9438 BasicBlockEdge DominatingEdge(PBB, BB);
9439 if (DominatingEdge.isSingleEdge()) {
9440 // We're constructively (and conservatively) enumerating edges within the
9441 // loop body that dominate the latch. The dominator tree better agree
9442 // with us on this:
9443 assert(DT.dominates(DominatingEdge, Latch) && "should be!")((DT.dominates(DominatingEdge, Latch) && "should be!"
) ? static_cast<void> (0) : __assert_fail ("DT.dominates(DominatingEdge, Latch) && \"should be!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9443, __PRETTY_FUNCTION__))
;
9444
9445 if (isImpliedCond(Pred, LHS, RHS, Condition,
9446 BB != ContinuePredicate->getSuccessor(0)))
9447 return true;
9448 }
9449 }
9450
9451 return false;
9452}
9453
9454bool
9455ScalarEvolution::isLoopEntryGuardedByCond(const Loop *L,
9456 ICmpInst::Predicate Pred,
9457 const SCEV *LHS, const SCEV *RHS) {
9458 // Interpret a null as meaning no loop, where there is obviously no guard
9459 // (interprocedural conditions notwithstanding).
9460 if (!L) return false;
9461
9462 if (VerifyIR)
9463 assert(!verifyFunction(*L->getHeader()->getParent(), &dbgs()) &&((!verifyFunction(*L->getHeader()->getParent(), &dbgs
()) && "This cannot be done on broken IR!") ? static_cast
<void> (0) : __assert_fail ("!verifyFunction(*L->getHeader()->getParent(), &dbgs()) && \"This cannot be done on broken IR!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9464, __PRETTY_FUNCTION__))
9464 "This cannot be done on broken IR!")((!verifyFunction(*L->getHeader()->getParent(), &dbgs
()) && "This cannot be done on broken IR!") ? static_cast
<void> (0) : __assert_fail ("!verifyFunction(*L->getHeader()->getParent(), &dbgs()) && \"This cannot be done on broken IR!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9464, __PRETTY_FUNCTION__))
;
9465
9466 // Both LHS and RHS must be available at loop entry.
9467 assert(isAvailableAtLoopEntry(LHS, L) &&((isAvailableAtLoopEntry(LHS, L) && "LHS is not available at Loop Entry"
) ? static_cast<void> (0) : __assert_fail ("isAvailableAtLoopEntry(LHS, L) && \"LHS is not available at Loop Entry\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9468, __PRETTY_FUNCTION__))
9468 "LHS is not available at Loop Entry")((isAvailableAtLoopEntry(LHS, L) && "LHS is not available at Loop Entry"
) ? static_cast<void> (0) : __assert_fail ("isAvailableAtLoopEntry(LHS, L) && \"LHS is not available at Loop Entry\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9468, __PRETTY_FUNCTION__))
;
9469 assert(isAvailableAtLoopEntry(RHS, L) &&((isAvailableAtLoopEntry(RHS, L) && "RHS is not available at Loop Entry"
) ? static_cast<void> (0) : __assert_fail ("isAvailableAtLoopEntry(RHS, L) && \"RHS is not available at Loop Entry\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9470, __PRETTY_FUNCTION__))
9470 "RHS is not available at Loop Entry")((isAvailableAtLoopEntry(RHS, L) && "RHS is not available at Loop Entry"
) ? static_cast<void> (0) : __assert_fail ("isAvailableAtLoopEntry(RHS, L) && \"RHS is not available at Loop Entry\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9470, __PRETTY_FUNCTION__))
;
9471
9472 if (isKnownViaNonRecursiveReasoning(Pred, LHS, RHS))
9473 return true;
9474
9475 // If we cannot prove strict comparison (e.g. a > b), maybe we can prove
9476 // the facts (a >= b && a != b) separately. A typical situation is when the
9477 // non-strict comparison is known from ranges and non-equality is known from
9478 // dominating predicates. If we are proving strict comparison, we always try
9479 // to prove non-equality and non-strict comparison separately.
9480 auto NonStrictPredicate = ICmpInst::getNonStrictPredicate(Pred);
9481 const bool ProvingStrictComparison = (Pred != NonStrictPredicate);
9482 bool ProvedNonStrictComparison = false;
9483 bool ProvedNonEquality = false;
9484
9485 if (ProvingStrictComparison) {
9486 ProvedNonStrictComparison =
9487 isKnownViaNonRecursiveReasoning(NonStrictPredicate, LHS, RHS);
9488 ProvedNonEquality =
9489 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_NE, LHS, RHS);
9490 if (ProvedNonStrictComparison && ProvedNonEquality)
9491 return true;
9492 }
9493
9494 // Try to prove (Pred, LHS, RHS) using isImpliedViaGuard.
9495 auto ProveViaGuard = [&](const BasicBlock *Block) {
9496 if (isImpliedViaGuard(Block, Pred, LHS, RHS))
9497 return true;
9498 if (ProvingStrictComparison) {
9499 if (!ProvedNonStrictComparison)
9500 ProvedNonStrictComparison =
9501 isImpliedViaGuard(Block, NonStrictPredicate, LHS, RHS);
9502 if (!ProvedNonEquality)
9503 ProvedNonEquality =
9504 isImpliedViaGuard(Block, ICmpInst::ICMP_NE, LHS, RHS);
9505 if (ProvedNonStrictComparison && ProvedNonEquality)
9506 return true;
9507 }
9508 return false;
9509 };
9510
9511 // Try to prove (Pred, LHS, RHS) using isImpliedCond.
9512 auto ProveViaCond = [&](const Value *Condition, bool Inverse) {
9513 if (isImpliedCond(Pred, LHS, RHS, Condition, Inverse))
9514 return true;
9515 if (ProvingStrictComparison) {
9516 if (!ProvedNonStrictComparison)
9517 ProvedNonStrictComparison =
9518 isImpliedCond(NonStrictPredicate, LHS, RHS, Condition, Inverse);
9519 if (!ProvedNonEquality)
9520 ProvedNonEquality =
9521 isImpliedCond(ICmpInst::ICMP_NE, LHS, RHS, Condition, Inverse);
9522 if (ProvedNonStrictComparison && ProvedNonEquality)
9523 return true;
9524 }
9525 return false;
9526 };
9527
9528 // Starting at the loop predecessor, climb up the predecessor chain, as long
9529 // as there are predecessors that can be found that have unique successors
9530 // leading to the original header.
9531 for (std::pair<const BasicBlock *, const BasicBlock *> Pair(
9532 L->getLoopPredecessor(), L->getHeader());
9533 Pair.first; Pair = getPredecessorWithUniqueSuccessorForBB(Pair.first)) {
9534
9535 if (ProveViaGuard(Pair.first))
9536 return true;
9537
9538 const BranchInst *LoopEntryPredicate =
9539 dyn_cast<BranchInst>(Pair.first->getTerminator());
9540 if (!LoopEntryPredicate ||
9541 LoopEntryPredicate->isUnconditional())
9542 continue;
9543
9544 if (ProveViaCond(LoopEntryPredicate->getCondition(),
9545 LoopEntryPredicate->getSuccessor(0) != Pair.second))
9546 return true;
9547 }
9548
9549 // Check conditions due to any @llvm.assume intrinsics.
9550 for (auto &AssumeVH : AC.assumptions()) {
9551 if (!AssumeVH)
9552 continue;
9553 auto *CI = cast<CallInst>(AssumeVH);
9554 if (!DT.dominates(CI, L->getHeader()))
9555 continue;
9556
9557 if (ProveViaCond(CI->getArgOperand(0), false))
9558 return true;
9559 }
9560
9561 return false;
9562}
9563
9564bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, const SCEV *LHS,
9565 const SCEV *RHS,
9566 const Value *FoundCondValue, bool Inverse) {
9567 if (!PendingLoopPredicates.insert(FoundCondValue).second)
9568 return false;
9569
9570 auto ClearOnExit =
9571 make_scope_exit([&]() { PendingLoopPredicates.erase(FoundCondValue); });
9572
9573 // Recursively handle And and Or conditions.
9574 if (const BinaryOperator *BO = dyn_cast<BinaryOperator>(FoundCondValue)) {
9575 if (BO->getOpcode() == Instruction::And) {
9576 if (!Inverse)
9577 return isImpliedCond(Pred, LHS, RHS, BO->getOperand(0), Inverse) ||
9578 isImpliedCond(Pred, LHS, RHS, BO->getOperand(1), Inverse);
9579 } else if (BO->getOpcode() == Instruction::Or) {
9580 if (Inverse)
9581 return isImpliedCond(Pred, LHS, RHS, BO->getOperand(0), Inverse) ||
9582 isImpliedCond(Pred, LHS, RHS, BO->getOperand(1), Inverse);
9583 }
9584 }
9585
9586 const ICmpInst *ICI = dyn_cast<ICmpInst>(FoundCondValue);
9587 if (!ICI) return false;
9588
9589 // Now that we found a conditional branch that dominates the loop or controls
9590 // the loop latch. Check to see if it is the comparison we are looking for.
9591 ICmpInst::Predicate FoundPred;
9592 if (Inverse)
9593 FoundPred = ICI->getInversePredicate();
9594 else
9595 FoundPred = ICI->getPredicate();
9596
9597 const SCEV *FoundLHS = getSCEV(ICI->getOperand(0));
9598 const SCEV *FoundRHS = getSCEV(ICI->getOperand(1));
9599
9600 return isImpliedCond(Pred, LHS, RHS, FoundPred, FoundLHS, FoundRHS);
9601}
9602
9603bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, const SCEV *LHS,
9604 const SCEV *RHS,
9605 ICmpInst::Predicate FoundPred,
9606 const SCEV *FoundLHS,
9607 const SCEV *FoundRHS) {
9608 // Balance the types.
9609 if (getTypeSizeInBits(LHS->getType()) <
9610 getTypeSizeInBits(FoundLHS->getType())) {
9611 if (CmpInst::isSigned(Pred)) {
9612 LHS = getSignExtendExpr(LHS, FoundLHS->getType());
9613 RHS = getSignExtendExpr(RHS, FoundLHS->getType());
9614 } else {
9615 LHS = getZeroExtendExpr(LHS, FoundLHS->getType());
9616 RHS = getZeroExtendExpr(RHS, FoundLHS->getType());
9617 }
9618 } else if (getTypeSizeInBits(LHS->getType()) >
9619 getTypeSizeInBits(FoundLHS->getType())) {
9620 if (CmpInst::isSigned(FoundPred)) {
9621 FoundLHS = getSignExtendExpr(FoundLHS, LHS->getType());
9622 FoundRHS = getSignExtendExpr(FoundRHS, LHS->getType());
9623 } else {
9624 FoundLHS = getZeroExtendExpr(FoundLHS, LHS->getType());
9625 FoundRHS = getZeroExtendExpr(FoundRHS, LHS->getType());
9626 }
9627 }
9628
9629 // Canonicalize the query to match the way instcombine will have
9630 // canonicalized the comparison.
9631 if (SimplifyICmpOperands(Pred, LHS, RHS))
9632 if (LHS == RHS)
9633 return CmpInst::isTrueWhenEqual(Pred);
9634 if (SimplifyICmpOperands(FoundPred, FoundLHS, FoundRHS))
9635 if (FoundLHS == FoundRHS)
9636 return CmpInst::isFalseWhenEqual(FoundPred);
9637
9638 // Check to see if we can make the LHS or RHS match.
9639 if (LHS == FoundRHS || RHS == FoundLHS) {
9640 if (isa<SCEVConstant>(RHS)) {
9641 std::swap(FoundLHS, FoundRHS);
9642 FoundPred = ICmpInst::getSwappedPredicate(FoundPred);
9643 } else {
9644 std::swap(LHS, RHS);
9645 Pred = ICmpInst::getSwappedPredicate(Pred);
9646 }
9647 }
9648
9649 // Check whether the found predicate is the same as the desired predicate.
9650 if (FoundPred == Pred)
9651 return isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS);
9652
9653 // Check whether swapping the found predicate makes it the same as the
9654 // desired predicate.
9655 if (ICmpInst::getSwappedPredicate(FoundPred) == Pred) {
9656 if (isa<SCEVConstant>(RHS))
9657 return isImpliedCondOperands(Pred, LHS, RHS, FoundRHS, FoundLHS);
9658 else
9659 return isImpliedCondOperands(ICmpInst::getSwappedPredicate(Pred),
9660 RHS, LHS, FoundLHS, FoundRHS);
9661 }
9662
9663 // Unsigned comparison is the same as signed comparison when both the operands
9664 // are non-negative.
9665 if (CmpInst::isUnsigned(FoundPred) &&
9666 CmpInst::getSignedPredicate(FoundPred) == Pred &&
9667 isKnownNonNegative(FoundLHS) && isKnownNonNegative(FoundRHS))
9668 return isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS);
9669
9670 // Check if we can make progress by sharpening ranges.
9671 if (FoundPred == ICmpInst::ICMP_NE &&
9672 (isa<SCEVConstant>(FoundLHS) || isa<SCEVConstant>(FoundRHS))) {
9673
9674 const SCEVConstant *C = nullptr;
9675 const SCEV *V = nullptr;
9676
9677 if (isa<SCEVConstant>(FoundLHS)) {
9678 C = cast<SCEVConstant>(FoundLHS);
9679 V = FoundRHS;
9680 } else {
9681 C = cast<SCEVConstant>(FoundRHS);
9682 V = FoundLHS;
9683 }
9684
9685 // The guarding predicate tells us that C != V. If the known range
9686 // of V is [C, t), we can sharpen the range to [C + 1, t). The
9687 // range we consider has to correspond to same signedness as the
9688 // predicate we're interested in folding.
9689
9690 APInt Min = ICmpInst::isSigned(Pred) ?
9691 getSignedRangeMin(V) : getUnsignedRangeMin(V);
9692
9693 if (Min == C->getAPInt()) {
9694 // Given (V >= Min && V != Min) we conclude V >= (Min + 1).
9695 // This is true even if (Min + 1) wraps around -- in case of
9696 // wraparound, (Min + 1) < Min, so (V >= Min => V >= (Min + 1)).
9697
9698 APInt SharperMin = Min + 1;
9699
9700 switch (Pred) {
9701 case ICmpInst::ICMP_SGE:
9702 case ICmpInst::ICMP_UGE:
9703 // We know V `Pred` SharperMin. If this implies LHS `Pred`
9704 // RHS, we're done.
9705 if (isImpliedCondOperands(Pred, LHS, RHS, V,
9706 getConstant(SharperMin)))
9707 return true;
9708 LLVM_FALLTHROUGH[[gnu::fallthrough]];
9709
9710 case ICmpInst::ICMP_SGT:
9711 case ICmpInst::ICMP_UGT:
9712 // We know from the range information that (V `Pred` Min ||
9713 // V == Min). We know from the guarding condition that !(V
9714 // == Min). This gives us
9715 //
9716 // V `Pred` Min || V == Min && !(V == Min)
9717 // => V `Pred` Min
9718 //
9719 // If V `Pred` Min implies LHS `Pred` RHS, we're done.
9720
9721 if (isImpliedCondOperands(Pred, LHS, RHS, V, getConstant(Min)))
9722 return true;
9723 LLVM_FALLTHROUGH[[gnu::fallthrough]];
9724
9725 default:
9726 // No change
9727 break;
9728 }
9729 }
9730 }
9731
9732 // Check whether the actual condition is beyond sufficient.
9733 if (FoundPred == ICmpInst::ICMP_EQ)
9734 if (ICmpInst::isTrueWhenEqual(Pred))
9735 if (isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS))
9736 return true;
9737 if (Pred == ICmpInst::ICMP_NE)
9738 if (!ICmpInst::isTrueWhenEqual(FoundPred))
9739 if (isImpliedCondOperands(FoundPred, LHS, RHS, FoundLHS, FoundRHS))
9740 return true;
9741
9742 // Otherwise assume the worst.
9743 return false;
9744}
9745
9746bool ScalarEvolution::splitBinaryAdd(const SCEV *Expr,
9747 const SCEV *&L, const SCEV *&R,
9748 SCEV::NoWrapFlags &Flags) {
9749 const auto *AE = dyn_cast<SCEVAddExpr>(Expr);
9750 if (!AE || AE->getNumOperands() != 2)
9751 return false;
9752
9753 L = AE->getOperand(0);
9754 R = AE->getOperand(1);
9755 Flags = AE->getNoWrapFlags();
9756 return true;
9757}
9758
9759Optional<APInt> ScalarEvolution::computeConstantDifference(const SCEV *More,
9760 const SCEV *Less) {
9761 // We avoid subtracting expressions here because this function is usually
9762 // fairly deep in the call stack (i.e. is called many times).
9763
9764 // X - X = 0.
9765 if (More == Less)
9766 return APInt(getTypeSizeInBits(More->getType()), 0);
9767
9768 if (isa<SCEVAddRecExpr>(Less) && isa<SCEVAddRecExpr>(More)) {
9769 const auto *LAR = cast<SCEVAddRecExpr>(Less);
9770 const auto *MAR = cast<SCEVAddRecExpr>(More);
9771
9772 if (LAR->getLoop() != MAR->getLoop())
9773 return None;
9774
9775 // We look at affine expressions only; not for correctness but to keep
9776 // getStepRecurrence cheap.
9777 if (!LAR->isAffine() || !MAR->isAffine())
9778 return None;
9779
9780 if (LAR->getStepRecurrence(*this) != MAR->getStepRecurrence(*this))
9781 return None;
9782
9783 Less = LAR->getStart();
9784 More = MAR->getStart();
9785
9786 // fall through
9787 }
9788
9789 if (isa<SCEVConstant>(Less) && isa<SCEVConstant>(More)) {
9790 const auto &M = cast<SCEVConstant>(More)->getAPInt();
9791 const auto &L = cast<SCEVConstant>(Less)->getAPInt();
9792 return M - L;
9793 }
9794
9795 SCEV::NoWrapFlags Flags;
9796 const SCEV *LLess = nullptr, *RLess = nullptr;
9797 const SCEV *LMore = nullptr, *RMore = nullptr;
9798 const SCEVConstant *C1 = nullptr, *C2 = nullptr;
9799 // Compare (X + C1) vs X.
9800 if (splitBinaryAdd(Less, LLess, RLess, Flags))
9801 if ((C1 = dyn_cast<SCEVConstant>(LLess)))
9802 if (RLess == More)
9803 return -(C1->getAPInt());
9804
9805 // Compare X vs (X + C2).
9806 if (splitBinaryAdd(More, LMore, RMore, Flags))
9807 if ((C2 = dyn_cast<SCEVConstant>(LMore)))
9808 if (RMore == Less)
9809 return C2->getAPInt();
9810
9811 // Compare (X + C1) vs (X + C2).
9812 if (C1 && C2 && RLess == RMore)
9813 return C2->getAPInt() - C1->getAPInt();
9814
9815 return None;
9816}
9817
9818bool ScalarEvolution::isImpliedCondOperandsViaNoOverflow(
9819 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS,
9820 const SCEV *FoundLHS, const SCEV *FoundRHS) {
9821 if (Pred != CmpInst::ICMP_SLT && Pred != CmpInst::ICMP_ULT)
9822 return false;
9823
9824 const auto *AddRecLHS = dyn_cast<SCEVAddRecExpr>(LHS);
9825 if (!AddRecLHS)
9826 return false;
9827
9828 const auto *AddRecFoundLHS = dyn_cast<SCEVAddRecExpr>(FoundLHS);
9829 if (!AddRecFoundLHS)
9830 return false;
9831
9832 // We'd like to let SCEV reason about control dependencies, so we constrain
9833 // both the inequalities to be about add recurrences on the same loop. This
9834 // way we can use isLoopEntryGuardedByCond later.
9835
9836 const Loop *L = AddRecFoundLHS->getLoop();
9837 if (L != AddRecLHS->getLoop())
9838 return false;
9839
9840 // FoundLHS u< FoundRHS u< -C => (FoundLHS + C) u< (FoundRHS + C) ... (1)
9841 //
9842 // FoundLHS s< FoundRHS s< INT_MIN - C => (FoundLHS + C) s< (FoundRHS + C)
9843 // ... (2)
9844 //
9845 // Informal proof for (2), assuming (1) [*]:
9846 //
9847 // We'll also assume (A s< B) <=> ((A + INT_MIN) u< (B + INT_MIN)) ... (3)[**]
9848 //
9849 // Then
9850 //
9851 // FoundLHS s< FoundRHS s< INT_MIN - C
9852 // <=> (FoundLHS + INT_MIN) u< (FoundRHS + INT_MIN) u< -C [ using (3) ]
9853 // <=> (FoundLHS + INT_MIN + C) u< (FoundRHS + INT_MIN + C) [ using (1) ]
9854 // <=> (FoundLHS + INT_MIN + C + INT_MIN) s<
9855 // (FoundRHS + INT_MIN + C + INT_MIN) [ using (3) ]
9856 // <=> FoundLHS + C s< FoundRHS + C
9857 //
9858 // [*]: (1) can be proved by ruling out overflow.
9859 //
9860 // [**]: This can be proved by analyzing all the four possibilities:
9861 // (A s< 0, B s< 0), (A s< 0, B s>= 0), (A s>= 0, B s< 0) and
9862 // (A s>= 0, B s>= 0).
9863 //
9864 // Note:
9865 // Despite (2), "FoundRHS s< INT_MIN - C" does not mean that "FoundRHS + C"
9866 // will not sign underflow. For instance, say FoundLHS = (i8 -128), FoundRHS
9867 // = (i8 -127) and C = (i8 -100). Then INT_MIN - C = (i8 -28), and FoundRHS
9868 // s< (INT_MIN - C). Lack of sign overflow / underflow in "FoundRHS + C" is
9869 // neither necessary nor sufficient to prove "(FoundLHS + C) s< (FoundRHS +
9870 // C)".
9871
9872 Optional<APInt> LDiff = computeConstantDifference(LHS, FoundLHS);
9873 Optional<APInt> RDiff = computeConstantDifference(RHS, FoundRHS);
9874 if (!LDiff || !RDiff || *LDiff != *RDiff)
9875 return false;
9876
9877 if (LDiff->isMinValue())
9878 return true;
9879
9880 APInt FoundRHSLimit;
9881
9882 if (Pred == CmpInst::ICMP_ULT) {
9883 FoundRHSLimit = -(*RDiff);
9884 } else {
9885 assert(Pred == CmpInst::ICMP_SLT && "Checked above!")((Pred == CmpInst::ICMP_SLT && "Checked above!") ? static_cast
<void> (0) : __assert_fail ("Pred == CmpInst::ICMP_SLT && \"Checked above!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9885, __PRETTY_FUNCTION__))
;
9886 FoundRHSLimit = APInt::getSignedMinValue(getTypeSizeInBits(RHS->getType())) - *RDiff;
9887 }
9888
9889 // Try to prove (1) or (2), as needed.
9890 return isAvailableAtLoopEntry(FoundRHS, L) &&
9891 isLoopEntryGuardedByCond(L, Pred, FoundRHS,
9892 getConstant(FoundRHSLimit));
9893}
9894
9895bool ScalarEvolution::isImpliedViaMerge(ICmpInst::Predicate Pred,
9896 const SCEV *LHS, const SCEV *RHS,
9897 const SCEV *FoundLHS,
9898 const SCEV *FoundRHS, unsigned Depth) {
9899 const PHINode *LPhi = nullptr, *RPhi = nullptr;
9900
9901 auto ClearOnExit = make_scope_exit([&]() {
9902 if (LPhi) {
9903 bool Erased = PendingMerges.erase(LPhi);
9904 assert(Erased && "Failed to erase LPhi!")((Erased && "Failed to erase LPhi!") ? static_cast<
void> (0) : __assert_fail ("Erased && \"Failed to erase LPhi!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9904, __PRETTY_FUNCTION__))
;
9905 (void)Erased;
9906 }
9907 if (RPhi) {
9908 bool Erased = PendingMerges.erase(RPhi);
9909 assert(Erased && "Failed to erase RPhi!")((Erased && "Failed to erase RPhi!") ? static_cast<
void> (0) : __assert_fail ("Erased && \"Failed to erase RPhi!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9909, __PRETTY_FUNCTION__))
;
9910 (void)Erased;
9911 }
9912 });
9913
9914 // Find respective Phis and check that they are not being pending.
9915 if (const SCEVUnknown *LU = dyn_cast<SCEVUnknown>(LHS))
9916 if (auto *Phi = dyn_cast<PHINode>(LU->getValue())) {
9917 if (!PendingMerges.insert(Phi).second)
9918 return false;
9919 LPhi = Phi;
9920 }
9921 if (const SCEVUnknown *RU = dyn_cast<SCEVUnknown>(RHS))
9922 if (auto *Phi = dyn_cast<PHINode>(RU->getValue())) {
9923 // If we detect a loop of Phi nodes being processed by this method, for
9924 // example:
9925 //
9926 // %a = phi i32 [ %some1, %preheader ], [ %b, %latch ]
9927 // %b = phi i32 [ %some2, %preheader ], [ %a, %latch ]
9928 //
9929 // we don't want to deal with a case that complex, so return conservative
9930 // answer false.
9931 if (!PendingMerges.insert(Phi).second)
9932 return false;
9933 RPhi = Phi;
9934 }
9935
9936 // If none of LHS, RHS is a Phi, nothing to do here.
9937 if (!LPhi && !RPhi)
9938 return false;
9939
9940 // If there is a SCEVUnknown Phi we are interested in, make it left.
9941 if (!LPhi) {
9942 std::swap(LHS, RHS);
9943 std::swap(FoundLHS, FoundRHS);
9944 std::swap(LPhi, RPhi);
9945 Pred = ICmpInst::getSwappedPredicate(Pred);
9946 }
9947
9948 assert(LPhi && "LPhi should definitely be a SCEVUnknown Phi!")((LPhi && "LPhi should definitely be a SCEVUnknown Phi!"
) ? static_cast<void> (0) : __assert_fail ("LPhi && \"LPhi should definitely be a SCEVUnknown Phi!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9948, __PRETTY_FUNCTION__))
;
9949 const BasicBlock *LBB = LPhi->getParent();
9950 const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS);
9951
9952 auto ProvedEasily = [&](const SCEV *S1, const SCEV *S2) {
9953 return isKnownViaNonRecursiveReasoning(Pred, S1, S2) ||
9954 isImpliedCondOperandsViaRanges(Pred, S1, S2, FoundLHS, FoundRHS) ||
9955 isImpliedViaOperations(Pred, S1, S2, FoundLHS, FoundRHS, Depth);
9956 };
9957
9958 if (RPhi && RPhi->getParent() == LBB) {
9959 // Case one: RHS is also a SCEVUnknown Phi from the same basic block.
9960 // If we compare two Phis from the same block, and for each entry block
9961 // the predicate is true for incoming values from this block, then the
9962 // predicate is also true for the Phis.
9963 for (const BasicBlock *IncBB : predecessors(LBB)) {
9964 const SCEV *L = getSCEV(LPhi->getIncomingValueForBlock(IncBB));
9965 const SCEV *R = getSCEV(RPhi->getIncomingValueForBlock(IncBB));
9966 if (!ProvedEasily(L, R))
9967 return false;
9968 }
9969 } else if (RAR && RAR->getLoop()->getHeader() == LBB) {
9970 // Case two: RHS is also a Phi from the same basic block, and it is an
9971 // AddRec. It means that there is a loop which has both AddRec and Unknown
9972 // PHIs, for it we can compare incoming values of AddRec from above the loop
9973 // and latch with their respective incoming values of LPhi.
9974 // TODO: Generalize to handle loops with many inputs in a header.
9975 if (LPhi->getNumIncomingValues() != 2) return false;
9976
9977 auto *RLoop = RAR->getLoop();
9978 auto *Predecessor = RLoop->getLoopPredecessor();
9979 assert(Predecessor && "Loop with AddRec with no predecessor?")((Predecessor && "Loop with AddRec with no predecessor?"
) ? static_cast<void> (0) : __assert_fail ("Predecessor && \"Loop with AddRec with no predecessor?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9979, __PRETTY_FUNCTION__))
;
9980 const SCEV *L1 = getSCEV(LPhi->getIncomingValueForBlock(Predecessor));
9981 if (!ProvedEasily(L1, RAR->getStart()))
9982 return false;
9983 auto *Latch = RLoop->getLoopLatch();
9984 assert(Latch && "Loop with AddRec with no latch?")((Latch && "Loop with AddRec with no latch?") ? static_cast
<void> (0) : __assert_fail ("Latch && \"Loop with AddRec with no latch?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9984, __PRETTY_FUNCTION__))
;
9985 const SCEV *L2 = getSCEV(LPhi->getIncomingValueForBlock(Latch));
9986 if (!ProvedEasily(L2, RAR->getPostIncExpr(*this)))
9987 return false;
9988 } else {
9989 // In all other cases go over inputs of LHS and compare each of them to RHS,
9990 // the predicate is true for (LHS, RHS) if it is true for all such pairs.
9991 // At this point RHS is either a non-Phi, or it is a Phi from some block
9992 // different from LBB.
9993 for (const BasicBlock *IncBB : predecessors(LBB)) {
9994 // Check that RHS is available in this block.
9995 if (!dominates(RHS, IncBB))
9996 return false;
9997 const SCEV *L = getSCEV(LPhi->getIncomingValueForBlock(IncBB));
9998 if (!ProvedEasily(L, RHS))
9999 return false;
10000 }
10001 }
10002 return true;
10003}
10004
10005bool ScalarEvolution::isImpliedCondOperands(ICmpInst::Predicate Pred,
10006 const SCEV *LHS, const SCEV *RHS,
10007 const SCEV *FoundLHS,
10008 const SCEV *FoundRHS) {
10009 if (isImpliedCondOperandsViaRanges(Pred, LHS, RHS, FoundLHS, FoundRHS))
10010 return true;
10011
10012 if (isImpliedCondOperandsViaNoOverflow(Pred, LHS, RHS, FoundLHS, FoundRHS))
10013 return true;
10014
10015 return isImpliedCondOperandsHelper(Pred, LHS, RHS,
10016 FoundLHS, FoundRHS) ||
10017 // ~x < ~y --> x > y
10018 isImpliedCondOperandsHelper(Pred, LHS, RHS,
10019 getNotSCEV(FoundRHS),
10020 getNotSCEV(FoundLHS));
10021}
10022
10023/// Is MaybeMinMaxExpr an (U|S)(Min|Max) of Candidate and some other values?
10024template <typename MinMaxExprType>
10025static bool IsMinMaxConsistingOf(const SCEV *MaybeMinMaxExpr,
10026 const SCEV *Candidate) {
10027 const MinMaxExprType *MinMaxExpr = dyn_cast<MinMaxExprType>(MaybeMinMaxExpr);
10028 if (!MinMaxExpr)
10029 return false;
10030
10031 return find(MinMaxExpr->operands(), Candidate) != MinMaxExpr->op_end();
10032}
10033
10034static bool IsKnownPredicateViaAddRecStart(ScalarEvolution &SE,
10035 ICmpInst::Predicate Pred,
10036 const SCEV *LHS, const SCEV *RHS) {
10037 // If both sides are affine addrecs for the same loop, with equal
10038 // steps, and we know the recurrences don't wrap, then we only
10039 // need to check the predicate on the starting values.
10040
10041 if (!ICmpInst::isRelational(Pred))
10042 return false;
10043
10044 const SCEVAddRecExpr *LAR = dyn_cast<SCEVAddRecExpr>(LHS);
10045 if (!LAR)
10046 return false;
10047 const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS);
10048 if (!RAR)
10049 return false;
10050 if (LAR->getLoop() != RAR->getLoop())
10051 return false;
10052 if (!LAR->isAffine() || !RAR->isAffine())
10053 return false;
10054
10055 if (LAR->getStepRecurrence(SE) != RAR->getStepRecurrence(SE))
10056 return false;
10057
10058 SCEV::NoWrapFlags NW = ICmpInst::isSigned(Pred) ?
10059 SCEV::FlagNSW : SCEV::FlagNUW;
10060 if (!LAR->getNoWrapFlags(NW) || !RAR->getNoWrapFlags(NW))
10061 return false;
10062
10063 return SE.isKnownPredicate(Pred, LAR->getStart(), RAR->getStart());
10064}
10065
10066/// Is LHS `Pred` RHS true on the virtue of LHS or RHS being a Min or Max
10067/// expression?
10068static bool IsKnownPredicateViaMinOrMax(ScalarEvolution &SE,
10069 ICmpInst::Predicate Pred,
10070 const SCEV *LHS, const SCEV *RHS) {
10071 switch (Pred) {
10072 default:
10073 return false;
10074
10075 case ICmpInst::ICMP_SGE:
10076 std::swap(LHS, RHS);
10077 LLVM_FALLTHROUGH[[gnu::fallthrough]];
10078 case ICmpInst::ICMP_SLE:
10079 return
10080 // min(A, ...) <= A
10081 IsMinMaxConsistingOf<SCEVSMinExpr>(LHS, RHS) ||
10082 // A <= max(A, ...)
10083 IsMinMaxConsistingOf<SCEVSMaxExpr>(RHS, LHS);
10084
10085 case ICmpInst::ICMP_UGE:
10086 std::swap(LHS, RHS);
10087 LLVM_FALLTHROUGH[[gnu::fallthrough]];
10088 case ICmpInst::ICMP_ULE:
10089 return
10090 // min(A, ...) <= A
10091 IsMinMaxConsistingOf<SCEVUMinExpr>(LHS, RHS) ||
10092 // A <= max(A, ...)
10093 IsMinMaxConsistingOf<SCEVUMaxExpr>(RHS, LHS);
10094 }
10095
10096 llvm_unreachable("covered switch fell through?!")::llvm::llvm_unreachable_internal("covered switch fell through?!"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10096)
;
10097}
10098
10099bool ScalarEvolution::isImpliedViaOperations(ICmpInst::Predicate Pred,
10100 const SCEV *LHS, const SCEV *RHS,
10101 const SCEV *FoundLHS,
10102 const SCEV *FoundRHS,
10103 unsigned Depth) {
10104 assert(getTypeSizeInBits(LHS->getType()) ==((getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS
->getType()) && "LHS and RHS have different sizes?"
) ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS->getType()) && \"LHS and RHS have different sizes?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10106, __PRETTY_FUNCTION__))
10105 getTypeSizeInBits(RHS->getType()) &&((getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS
->getType()) && "LHS and RHS have different sizes?"
) ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS->getType()) && \"LHS and RHS have different sizes?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10106, __PRETTY_FUNCTION__))
10106 "LHS and RHS have different sizes?")((getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS
->getType()) && "LHS and RHS have different sizes?"
) ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS->getType()) && \"LHS and RHS have different sizes?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10106, __PRETTY_FUNCTION__))
;
10107 assert(getTypeSizeInBits(FoundLHS->getType()) ==((getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits
(FoundRHS->getType()) && "FoundLHS and FoundRHS have different sizes?"
) ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits(FoundRHS->getType()) && \"FoundLHS and FoundRHS have different sizes?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10109, __PRETTY_FUNCTION__))
10108 getTypeSizeInBits(FoundRHS->getType()) &&((getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits
(FoundRHS->getType()) && "FoundLHS and FoundRHS have different sizes?"
) ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits(FoundRHS->getType()) && \"FoundLHS and FoundRHS have different sizes?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10109, __PRETTY_FUNCTION__))
10109 "FoundLHS and FoundRHS have different sizes?")((getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits
(FoundRHS->getType()) && "FoundLHS and FoundRHS have different sizes?"
) ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits(FoundRHS->getType()) && \"FoundLHS and FoundRHS have different sizes?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10109, __PRETTY_FUNCTION__))
;
10110 // We want to avoid hurting the compile time with analysis of too big trees.
10111 if (Depth > MaxSCEVOperationsImplicationDepth)
10112 return false;
10113 // We only want to work with ICMP_SGT comparison so far.
10114 // TODO: Extend to ICMP_UGT?
10115 if (Pred == ICmpInst::ICMP_SLT) {
10116 Pred = ICmpInst::ICMP_SGT;
10117 std::swap(LHS, RHS);
10118 std::swap(FoundLHS, FoundRHS);
10119 }
10120 if (Pred != ICmpInst::ICMP_SGT)
10121 return false;
10122
10123 auto GetOpFromSExt = [&](const SCEV *S) {
10124 if (auto *Ext = dyn_cast<SCEVSignExtendExpr>(S))
10125 return Ext->getOperand();
10126 // TODO: If S is a SCEVConstant then you can cheaply "strip" the sext off
10127 // the constant in some cases.
10128 return S;
10129 };
10130
10131 // Acquire values from extensions.
10132 auto *OrigLHS = LHS;
10133 auto *OrigFoundLHS = FoundLHS;
10134 LHS = GetOpFromSExt(LHS);
10135 FoundLHS = GetOpFromSExt(FoundLHS);
10136
10137 // Is the SGT predicate can be proved trivially or using the found context.
10138 auto IsSGTViaContext = [&](const SCEV *S1, const SCEV *S2) {
10139 return isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SGT, S1, S2) ||
10140 isImpliedViaOperations(ICmpInst::ICMP_SGT, S1, S2, OrigFoundLHS,
10141 FoundRHS, Depth + 1);
10142 };
10143
10144 if (auto *LHSAddExpr = dyn_cast<SCEVAddExpr>(LHS)) {
10145 // We want to avoid creation of any new non-constant SCEV. Since we are
10146 // going to compare the operands to RHS, we should be certain that we don't
10147 // need any size extensions for this. So let's decline all cases when the
10148 // sizes of types of LHS and RHS do not match.
10149 // TODO: Maybe try to get RHS from sext to catch more cases?
10150 if (getTypeSizeInBits(LHS->getType()) != getTypeSizeInBits(RHS->getType()))
10151 return false;
10152
10153 // Should not overflow.
10154 if (!LHSAddExpr->hasNoSignedWrap())
10155 return false;
10156
10157 auto *LL = LHSAddExpr->getOperand(0);
10158 auto *LR = LHSAddExpr->getOperand(1);
10159 auto *MinusOne = getNegativeSCEV(getOne(RHS->getType()));
10160
10161 // Checks that S1 >= 0 && S2 > RHS, trivially or using the found context.
10162 auto IsSumGreaterThanRHS = [&](const SCEV *S1, const SCEV *S2) {
10163 return IsSGTViaContext(S1, MinusOne) && IsSGTViaContext(S2, RHS);
10164 };
10165 // Try to prove the following rule:
10166 // (LHS = LL + LR) && (LL >= 0) && (LR > RHS) => (LHS > RHS).
10167 // (LHS = LL + LR) && (LR >= 0) && (LL > RHS) => (LHS > RHS).
10168 if (IsSumGreaterThanRHS(LL, LR) || IsSumGreaterThanRHS(LR, LL))
10169 return true;
10170 } else if (auto *LHSUnknownExpr = dyn_cast<SCEVUnknown>(LHS)) {
10171 Value *LL, *LR;
10172 // FIXME: Once we have SDiv implemented, we can get rid of this matching.
10173
10174 using namespace llvm::PatternMatch;
10175
10176 if (match(LHSUnknownExpr->getValue(), m_SDiv(m_Value(LL), m_Value(LR)))) {
10177 // Rules for division.
10178 // We are going to perform some comparisons with Denominator and its
10179 // derivative expressions. In general case, creating a SCEV for it may
10180 // lead to a complex analysis of the entire graph, and in particular it
10181 // can request trip count recalculation for the same loop. This would
10182 // cache as SCEVCouldNotCompute to avoid the infinite recursion. To avoid
10183 // this, we only want to create SCEVs that are constants in this section.
10184 // So we bail if Denominator is not a constant.
10185 if (!isa<ConstantInt>(LR))
10186 return false;
10187
10188 auto *Denominator = cast<SCEVConstant>(getSCEV(LR));
10189
10190 // We want to make sure that LHS = FoundLHS / Denominator. If it is so,
10191 // then a SCEV for the numerator already exists and matches with FoundLHS.
10192 auto *Numerator = getExistingSCEV(LL);
10193 if (!Numerator || Numerator->getType() != FoundLHS->getType())
10194 return false;
10195
10196 // Make sure that the numerator matches with FoundLHS and the denominator
10197 // is positive.
10198 if (!HasSameValue(Numerator, FoundLHS) || !isKnownPositive(Denominator))
10199 return false;
10200
10201 auto *DTy = Denominator->getType();
10202 auto *FRHSTy = FoundRHS->getType();
10203 if (DTy->isPointerTy() != FRHSTy->isPointerTy())
10204 // One of types is a pointer and another one is not. We cannot extend
10205 // them properly to a wider type, so let us just reject this case.
10206 // TODO: Usage of getEffectiveSCEVType for DTy, FRHSTy etc should help
10207 // to avoid this check.
10208 return false;
10209
10210 // Given that:
10211 // FoundLHS > FoundRHS, LHS = FoundLHS / Denominator, Denominator > 0.
10212 auto *WTy = getWiderType(DTy, FRHSTy);
10213 auto *DenominatorExt = getNoopOrSignExtend(Denominator, WTy);
10214 auto *FoundRHSExt = getNoopOrSignExtend(FoundRHS, WTy);
10215
10216 // Try to prove the following rule:
10217 // (FoundRHS > Denominator - 2) && (RHS <= 0) => (LHS > RHS).
10218 // For example, given that FoundLHS > 2. It means that FoundLHS is at
10219 // least 3. If we divide it by Denominator < 4, we will have at least 1.
10220 auto *DenomMinusTwo = getMinusSCEV(DenominatorExt, getConstant(WTy, 2));
10221 if (isKnownNonPositive(RHS) &&
10222 IsSGTViaContext(FoundRHSExt, DenomMinusTwo))
10223 return true;
10224
10225 // Try to prove the following rule:
10226 // (FoundRHS > -1 - Denominator) && (RHS < 0) => (LHS > RHS).
10227 // For example, given that FoundLHS > -3. Then FoundLHS is at least -2.
10228 // If we divide it by Denominator > 2, then:
10229 // 1. If FoundLHS is negative, then the result is 0.
10230 // 2. If FoundLHS is non-negative, then the result is non-negative.
10231 // Anyways, the result is non-negative.
10232 auto *MinusOne = getNegativeSCEV(getOne(WTy));
10233 auto *NegDenomMinusOne = getMinusSCEV(MinusOne, DenominatorExt);
10234 if (isKnownNegative(RHS) &&
10235 IsSGTViaContext(FoundRHSExt, NegDenomMinusOne))
10236 return true;
10237 }
10238 }
10239
10240 // If our expression contained SCEVUnknown Phis, and we split it down and now
10241 // need to prove something for them, try to prove the predicate for every
10242 // possible incoming values of those Phis.
10243 if (isImpliedViaMerge(Pred, OrigLHS, RHS, OrigFoundLHS, FoundRHS, Depth + 1))
10244 return true;
10245
10246 return false;
10247}
10248
10249static bool isKnownPredicateExtendIdiom(ICmpInst::Predicate Pred,
10250 const SCEV *LHS, const SCEV *RHS) {
10251 // zext x u<= sext x, sext x s<= zext x
10252 switch (Pred) {
10253 case ICmpInst::ICMP_SGE:
10254 std::swap(LHS, RHS);
10255 LLVM_FALLTHROUGH[[gnu::fallthrough]];
10256 case ICmpInst::ICMP_SLE: {
10257 // If operand >=s 0 then ZExt == SExt. If operand <s 0 then SExt <s ZExt.
10258 const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(LHS);
10259 const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(RHS);
10260 if (SExt && ZExt && SExt->getOperand() == ZExt->getOperand())
10261 return true;
10262 break;
10263 }
10264 case ICmpInst::ICMP_UGE:
10265 std::swap(LHS, RHS);
10266 LLVM_FALLTHROUGH[[gnu::fallthrough]];
10267 case ICmpInst::ICMP_ULE: {
10268 // If operand >=s 0 then ZExt == SExt. If operand <s 0 then ZExt <u SExt.
10269 const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(LHS);
10270 const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(RHS);
10271 if (SExt && ZExt && SExt->getOperand() == ZExt->getOperand())
10272 return true;
10273 break;
10274 }
10275 default:
10276 break;
10277 };
10278 return false;
10279}
10280
10281bool
10282ScalarEvolution::isKnownViaNonRecursiveReasoning(ICmpInst::Predicate Pred,
10283 const SCEV *LHS, const SCEV *RHS) {
10284 return isKnownPredicateExtendIdiom(Pred, LHS, RHS) ||
10285 isKnownPredicateViaConstantRanges(Pred, LHS, RHS) ||
10286 IsKnownPredicateViaMinOrMax(*this, Pred, LHS, RHS) ||
10287 IsKnownPredicateViaAddRecStart(*this, Pred, LHS, RHS) ||
10288 isKnownPredicateViaNoOverflow(Pred, LHS, RHS);
10289}
10290
10291bool
10292ScalarEvolution::isImpliedCondOperandsHelper(ICmpInst::Predicate Pred,
10293 const SCEV *LHS, const SCEV *RHS,
10294 const SCEV *FoundLHS,
10295 const SCEV *FoundRHS) {
10296 switch (Pred) {
10297 default: llvm_unreachable("Unexpected ICmpInst::Predicate value!")::llvm::llvm_unreachable_internal("Unexpected ICmpInst::Predicate value!"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10297)
;
10298 case ICmpInst::ICMP_EQ:
10299 case ICmpInst::ICMP_NE:
10300 if (HasSameValue(LHS, FoundLHS) && HasSameValue(RHS, FoundRHS))
10301 return true;
10302 break;
10303 case ICmpInst::ICMP_SLT:
10304 case ICmpInst::ICMP_SLE:
10305 if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SLE, LHS, FoundLHS) &&
10306 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SGE, RHS, FoundRHS))
10307 return true;
10308 break;
10309 case ICmpInst::ICMP_SGT:
10310 case ICmpInst::ICMP_SGE:
10311 if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SGE, LHS, FoundLHS) &&
10312 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SLE, RHS, FoundRHS))
10313 return true;
10314 break;
10315 case ICmpInst::ICMP_ULT:
10316 case ICmpInst::ICMP_ULE:
10317 if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_ULE, LHS, FoundLHS) &&
10318 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_UGE, RHS, FoundRHS))
10319 return true;
10320 break;
10321 case ICmpInst::ICMP_UGT:
10322 case ICmpInst::ICMP_UGE:
10323 if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_UGE, LHS, FoundLHS) &&
10324 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_ULE, RHS, FoundRHS))
10325 return true;
10326 break;
10327 }
10328
10329 // Maybe it can be proved via operations?
10330 if (isImpliedViaOperations(Pred, LHS, RHS, FoundLHS, FoundRHS))
10331 return true;
10332
10333 return false;
10334}
10335
10336bool ScalarEvolution::isImpliedCondOperandsViaRanges(ICmpInst::Predicate Pred,
10337 const SCEV *LHS,
10338 const SCEV *RHS,
10339 const SCEV *FoundLHS,
10340 const SCEV *FoundRHS) {
10341 if (!isa<SCEVConstant>(RHS) || !isa<SCEVConstant>(FoundRHS))
10342 // The restriction on `FoundRHS` be lifted easily -- it exists only to
10343 // reduce the compile time impact of this optimization.
10344 return false;
10345
10346 Optional<APInt> Addend = computeConstantDifference(LHS, FoundLHS);
10347 if (!Addend)
10348 return false;
10349
10350 const APInt &ConstFoundRHS = cast<SCEVConstant>(FoundRHS)->getAPInt();
10351
10352 // `FoundLHSRange` is the range we know `FoundLHS` to be in by virtue of the
10353 // antecedent "`FoundLHS` `Pred` `FoundRHS`".
10354 ConstantRange FoundLHSRange =
10355 ConstantRange::makeAllowedICmpRegion(Pred, ConstFoundRHS);
10356
10357 // Since `LHS` is `FoundLHS` + `Addend`, we can compute a range for `LHS`:
10358 ConstantRange LHSRange = FoundLHSRange.add(ConstantRange(*Addend));
10359
10360 // We can also compute the range of values for `LHS` that satisfy the
10361 // consequent, "`LHS` `Pred` `RHS`":
10362 const APInt &ConstRHS = cast<SCEVConstant>(RHS)->getAPInt();
10363 ConstantRange SatisfyingLHSRange =
10364 ConstantRange::makeSatisfyingICmpRegion(Pred, ConstRHS);
10365
10366 // The antecedent implies the consequent if every value of `LHS` that
10367 // satisfies the antecedent also satisfies the consequent.
10368 return SatisfyingLHSRange.contains(LHSRange);
10369}
10370
10371bool ScalarEvolution::doesIVOverflowOnLT(const SCEV *RHS, const SCEV *Stride,
10372 bool IsSigned, bool NoWrap) {
10373 assert(isKnownPositive(Stride) && "Positive stride expected!")((isKnownPositive(Stride) && "Positive stride expected!"
) ? static_cast<void> (0) : __assert_fail ("isKnownPositive(Stride) && \"Positive stride expected!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10373, __PRETTY_FUNCTION__))
;
10374
10375 if (NoWrap) return false;
10376
10377 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
10378 const SCEV *One = getOne(Stride->getType());
10379
10380 if (IsSigned) {
10381 APInt MaxRHS = getSignedRangeMax(RHS);
10382 APInt MaxValue = APInt::getSignedMaxValue(BitWidth);
10383 APInt MaxStrideMinusOne = getSignedRangeMax(getMinusSCEV(Stride, One));
10384
10385 // SMaxRHS + SMaxStrideMinusOne > SMaxValue => overflow!
10386 return (std::move(MaxValue) - MaxStrideMinusOne).slt(MaxRHS);
10387 }
10388
10389 APInt MaxRHS = getUnsignedRangeMax(RHS);
10390 APInt MaxValue = APInt::getMaxValue(BitWidth);
10391 APInt MaxStrideMinusOne = getUnsignedRangeMax(getMinusSCEV(Stride, One));
10392
10393 // UMaxRHS + UMaxStrideMinusOne > UMaxValue => overflow!
10394 return (std::move(MaxValue) - MaxStrideMinusOne).ult(MaxRHS);
10395}
10396
10397bool ScalarEvolution::doesIVOverflowOnGT(const SCEV *RHS, const SCEV *Stride,
10398 bool IsSigned, bool NoWrap) {
10399 if (NoWrap) return false;
10400
10401 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
10402 const SCEV *One = getOne(Stride->getType());
10403
10404 if (IsSigned) {
10405 APInt MinRHS = getSignedRangeMin(RHS);
10406 APInt MinValue = APInt::getSignedMinValue(BitWidth);
10407 APInt MaxStrideMinusOne = getSignedRangeMax(getMinusSCEV(Stride, One));
10408
10409 // SMinRHS - SMaxStrideMinusOne < SMinValue => overflow!
10410 return (std::move(MinValue) + MaxStrideMinusOne).sgt(MinRHS);
10411 }
10412
10413 APInt MinRHS = getUnsignedRangeMin(RHS);
10414 APInt MinValue = APInt::getMinValue(BitWidth);
10415 APInt MaxStrideMinusOne = getUnsignedRangeMax(getMinusSCEV(Stride, One));
10416
10417 // UMinRHS - UMaxStrideMinusOne < UMinValue => overflow!
10418 return (std::move(MinValue) + MaxStrideMinusOne).ugt(MinRHS);
10419}
10420
10421const SCEV *ScalarEvolution::computeBECount(const SCEV *Delta, const SCEV *Step,
10422 bool Equality) {
10423 const SCEV *One = getOne(Step->getType());
10424 Delta = Equality ? getAddExpr(Delta, Step)
10425 : getAddExpr(Delta, getMinusSCEV(Step, One));
10426 return getUDivExpr(Delta, Step);
10427}
10428
10429const SCEV *ScalarEvolution::computeMaxBECountForLT(const SCEV *Start,
10430 const SCEV *Stride,
10431 const SCEV *End,
10432 unsigned BitWidth,
10433 bool IsSigned) {
10434
10435 assert(!isKnownNonPositive(Stride) &&((!isKnownNonPositive(Stride) && "Stride is expected strictly positive!"
) ? static_cast<void> (0) : __assert_fail ("!isKnownNonPositive(Stride) && \"Stride is expected strictly positive!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10436, __PRETTY_FUNCTION__))
10436 "Stride is expected strictly positive!")((!isKnownNonPositive(Stride) && "Stride is expected strictly positive!"
) ? static_cast<void> (0) : __assert_fail ("!isKnownNonPositive(Stride) && \"Stride is expected strictly positive!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10436, __PRETTY_FUNCTION__))
;
10437 // Calculate the maximum backedge count based on the range of values
10438 // permitted by Start, End, and Stride.
10439 const SCEV *MaxBECount;
10440 APInt MinStart =
10441 IsSigned ? getSignedRangeMin(Start) : getUnsignedRangeMin(Start);
10442
10443 APInt StrideForMaxBECount =
10444 IsSigned ? getSignedRangeMin(Stride) : getUnsignedRangeMin(Stride);
10445
10446 // We already know that the stride is positive, so we paper over conservatism
10447 // in our range computation by forcing StrideForMaxBECount to be at least one.
10448 // In theory this is unnecessary, but we expect MaxBECount to be a
10449 // SCEVConstant, and (udiv <constant> 0) is not constant folded by SCEV (there
10450 // is nothing to constant fold it to).
10451 APInt One(BitWidth, 1, IsSigned);
10452 StrideForMaxBECount = APIntOps::smax(One, StrideForMaxBECount);
10453
10454 APInt MaxValue = IsSigned ? APInt::getSignedMaxValue(BitWidth)
10455 : APInt::getMaxValue(BitWidth);
10456 APInt Limit = MaxValue - (StrideForMaxBECount - 1);
10457
10458 // Although End can be a MAX expression we estimate MaxEnd considering only
10459 // the case End = RHS of the loop termination condition. This is safe because
10460 // in the other case (End - Start) is zero, leading to a zero maximum backedge
10461 // taken count.
10462 APInt MaxEnd = IsSigned ? APIntOps::smin(getSignedRangeMax(End), Limit)
10463 : APIntOps::umin(getUnsignedRangeMax(End), Limit);
10464
10465 MaxBECount = computeBECount(getConstant(MaxEnd - MinStart) /* Delta */,
10466 getConstant(StrideForMaxBECount) /* Step */,
10467 false /* Equality */);
10468
10469 return MaxBECount;
10470}
10471
10472ScalarEvolution::ExitLimit
10473ScalarEvolution::howManyLessThans(const SCEV *LHS, const SCEV *RHS,
10474 const Loop *L, bool IsSigned,
10475 bool ControlsExit, bool AllowPredicates) {
10476 SmallPtrSet<const SCEVPredicate *, 4> Predicates;
10477
10478 const SCEVAddRecExpr *IV = dyn_cast<SCEVAddRecExpr>(LHS);
10479 bool PredicatedIV = false;
10480
10481 if (!IV && AllowPredicates) {
10482 // Try to make this an AddRec using runtime tests, in the first X
10483 // iterations of this loop, where X is the SCEV expression found by the
10484 // algorithm below.
10485 IV = convertSCEVToAddRecWithPredicates(LHS, L, Predicates);
10486 PredicatedIV = true;
10487 }
10488
10489 // Avoid weird loops
10490 if (!IV || IV->getLoop() != L || !IV->isAffine())
10491 return getCouldNotCompute();
10492
10493 bool NoWrap = ControlsExit &&
10494 IV->getNoWrapFlags(IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW);
10495
10496 const SCEV *Stride = IV->getStepRecurrence(*this);
10497
10498 bool PositiveStride = isKnownPositive(Stride);
10499
10500 // Avoid negative or zero stride values.
10501 if (!PositiveStride) {
10502 // We can compute the correct backedge taken count for loops with unknown
10503 // strides if we can prove that the loop is not an infinite loop with side
10504 // effects. Here's the loop structure we are trying to handle -
10505 //
10506 // i = start
10507 // do {
10508 // A[i] = i;
10509 // i += s;
10510 // } while (i < end);
10511 //
10512 // The backedge taken count for such loops is evaluated as -
10513 // (max(end, start + stride) - start - 1) /u stride
10514 //
10515 // The additional preconditions that we need to check to prove correctness
10516 // of the above formula is as follows -
10517 //
10518 // a) IV is either nuw or nsw depending upon signedness (indicated by the
10519 // NoWrap flag).
10520 // b) loop is single exit with no side effects.
10521 //
10522 //
10523 // Precondition a) implies that if the stride is negative, this is a single
10524 // trip loop. The backedge taken count formula reduces to zero in this case.
10525 //
10526 // Precondition b) implies that the unknown stride cannot be zero otherwise
10527 // we have UB.
10528 //
10529 // The positive stride case is the same as isKnownPositive(Stride) returning
10530 // true (original behavior of the function).
10531 //
10532 // We want to make sure that the stride is truly unknown as there are edge
10533 // cases where ScalarEvolution propagates no wrap flags to the
10534 // post-increment/decrement IV even though the increment/decrement operation
10535 // itself is wrapping. The computed backedge taken count may be wrong in
10536 // such cases. This is prevented by checking that the stride is not known to
10537 // be either positive or non-positive. For example, no wrap flags are
10538 // propagated to the post-increment IV of this loop with a trip count of 2 -
10539 //
10540 // unsigned char i;
10541 // for(i=127; i<128; i+=129)
10542 // A[i] = i;
10543 //
10544 if (PredicatedIV || !NoWrap || isKnownNonPositive(Stride) ||
10545 !loopHasNoSideEffects(L))
10546 return getCouldNotCompute();
10547 } else if (!Stride->isOne() &&
10548 doesIVOverflowOnLT(RHS, Stride, IsSigned, NoWrap))
10549 // Avoid proven overflow cases: this will ensure that the backedge taken
10550 // count will not generate any unsigned overflow. Relaxed no-overflow
10551 // conditions exploit NoWrapFlags, allowing to optimize in presence of
10552 // undefined behaviors like the case of C language.
10553 return getCouldNotCompute();
10554
10555 ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SLT
10556 : ICmpInst::ICMP_ULT;
10557 const SCEV *Start = IV->getStart();
10558 const SCEV *End = RHS;
10559 // When the RHS is not invariant, we do not know the end bound of the loop and
10560 // cannot calculate the ExactBECount needed by ExitLimit. However, we can
10561 // calculate the MaxBECount, given the start, stride and max value for the end
10562 // bound of the loop (RHS), and the fact that IV does not overflow (which is
10563 // checked above).
10564 if (!isLoopInvariant(RHS, L)) {
10565 const SCEV *MaxBECount = computeMaxBECountForLT(
10566 Start, Stride, RHS, getTypeSizeInBits(LHS->getType()), IsSigned);
10567 return ExitLimit(getCouldNotCompute() /* ExactNotTaken */, MaxBECount,
10568 false /*MaxOrZero*/, Predicates);
10569 }
10570 // If the backedge is taken at least once, then it will be taken
10571 // (End-Start)/Stride times (rounded up to a multiple of Stride), where Start
10572 // is the LHS value of the less-than comparison the first time it is evaluated
10573 // and End is the RHS.
10574 const SCEV *BECountIfBackedgeTaken =
10575 computeBECount(getMinusSCEV(End, Start), Stride, false);
10576 // If the loop entry is guarded by the result of the backedge test of the
10577 // first loop iteration, then we know the backedge will be taken at least
10578 // once and so the backedge taken count is as above. If not then we use the
10579 // expression (max(End,Start)-Start)/Stride to describe the backedge count,
10580 // as if the backedge is taken at least once max(End,Start) is End and so the
10581 // result is as above, and if not max(End,Start) is Start so we get a backedge
10582 // count of zero.
10583 const SCEV *BECount;
10584 if (isLoopEntryGuardedByCond(L, Cond, getMinusSCEV(Start, Stride), RHS))
10585 BECount = BECountIfBackedgeTaken;
10586 else {
10587 // If we know that RHS >= Start in the context of loop, then we know that
10588 // max(RHS, Start) = RHS at this point.
10589 if (isLoopEntryGuardedByCond(
10590 L, IsSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE, RHS, Start))
10591 End = RHS;
10592 else
10593 End = IsSigned ? getSMaxExpr(RHS, Start) : getUMaxExpr(RHS, Start);
10594 BECount = computeBECount(getMinusSCEV(End, Start), Stride, false);
10595 }
10596
10597 const SCEV *MaxBECount;
10598 bool MaxOrZero = false;
10599 if (isa<SCEVConstant>(BECount))
10600 MaxBECount = BECount;
10601 else if (isa<SCEVConstant>(BECountIfBackedgeTaken)) {
10602 // If we know exactly how many times the backedge will be taken if it's
10603 // taken at least once, then the backedge count will either be that or
10604 // zero.
10605 MaxBECount = BECountIfBackedgeTaken;
10606 MaxOrZero = true;
10607 } else {
10608 MaxBECount = computeMaxBECountForLT(
10609 Start, Stride, RHS, getTypeSizeInBits(LHS->getType()), IsSigned);
10610 }
10611
10612 if (isa<SCEVCouldNotCompute>(MaxBECount) &&
10613 !isa<SCEVCouldNotCompute>(BECount))
10614 MaxBECount = getConstant(getUnsignedRangeMax(BECount));
10615
10616 return ExitLimit(BECount, MaxBECount, MaxOrZero, Predicates);
10617}
10618
10619ScalarEvolution::ExitLimit
10620ScalarEvolution::howManyGreaterThans(const SCEV *LHS, const SCEV *RHS,
10621 const Loop *L, bool IsSigned,
10622 bool ControlsExit, bool AllowPredicates) {
10623 SmallPtrSet<const SCEVPredicate *, 4> Predicates;
10624 // We handle only IV > Invariant
10625 if (!isLoopInvariant(RHS, L))
10626 return getCouldNotCompute();
10627
10628 const SCEVAddRecExpr *IV = dyn_cast<SCEVAddRecExpr>(LHS);
10629 if (!IV && AllowPredicates)
10630 // Try to make this an AddRec using runtime tests, in the first X
10631 // iterations of this loop, where X is the SCEV expression found by the
10632 // algorithm below.
10633 IV = convertSCEVToAddRecWithPredicates(LHS, L, Predicates);
10634
10635 // Avoid weird loops
10636 if (!IV || IV->getLoop() != L || !IV->isAffine())
10637 return getCouldNotCompute();
10638
10639 bool NoWrap = ControlsExit &&
10640 IV->getNoWrapFlags(IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW);
10641
10642 const SCEV *Stride = getNegativeSCEV(IV->getStepRecurrence(*this));
10643
10644 // Avoid negative or zero stride values
10645 if (!isKnownPositive(Stride))
10646 return getCouldNotCompute();
10647
10648 // Avoid proven overflow cases: this will ensure that the backedge taken count
10649 // will not generate any unsigned overflow. Relaxed no-overflow conditions
10650 // exploit NoWrapFlags, allowing to optimize in presence of undefined
10651 // behaviors like the case of C language.
10652 if (!Stride->isOne() && doesIVOverflowOnGT(RHS, Stride, IsSigned, NoWrap))
10653 return getCouldNotCompute();
10654
10655 ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SGT
10656 : ICmpInst::ICMP_UGT;
10657
10658 const SCEV *Start = IV->getStart();
10659 const SCEV *End = RHS;
10660 if (!isLoopEntryGuardedByCond(L, Cond, getAddExpr(Start, Stride), RHS)) {
10661 // If we know that Start >= RHS in the context of loop, then we know that
10662 // min(RHS, Start) = RHS at this point.
10663 if (isLoopEntryGuardedByCond(
10664 L, IsSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE, Start, RHS))
10665 End = RHS;
10666 else
10667 End = IsSigned ? getSMinExpr(RHS, Start) : getUMinExpr(RHS, Start);
10668 }
10669
10670 const SCEV *BECount = computeBECount(getMinusSCEV(Start, End), Stride, false);
10671
10672 APInt MaxStart = IsSigned ? getSignedRangeMax(Start)
10673 : getUnsignedRangeMax(Start);
10674
10675 APInt MinStride = IsSigned ? getSignedRangeMin(Stride)
10676 : getUnsignedRangeMin(Stride);
10677
10678 unsigned BitWidth = getTypeSizeInBits(LHS->getType());
10679 APInt Limit = IsSigned ? APInt::getSignedMinValue(BitWidth) + (MinStride - 1)
10680 : APInt::getMinValue(BitWidth) + (MinStride - 1);
10681
10682 // Although End can be a MIN expression we estimate MinEnd considering only
10683 // the case End = RHS. This is safe because in the other case (Start - End)
10684 // is zero, leading to a zero maximum backedge taken count.
10685 APInt MinEnd =
10686 IsSigned ? APIntOps::smax(getSignedRangeMin(RHS), Limit)
10687 : APIntOps::umax(getUnsignedRangeMin(RHS), Limit);
10688
10689 const SCEV *MaxBECount = isa<SCEVConstant>(BECount)
10690 ? BECount
10691 : computeBECount(getConstant(MaxStart - MinEnd),
10692 getConstant(MinStride), false);
10693
10694 if (isa<SCEVCouldNotCompute>(MaxBECount))
10695 MaxBECount = BECount;
10696
10697 return ExitLimit(BECount, MaxBECount, false, Predicates);
10698}
10699
10700const SCEV *SCEVAddRecExpr::getNumIterationsInRange(const ConstantRange &Range,
10701 ScalarEvolution &SE) const {
10702 if (Range.isFullSet()) // Infinite loop.
10703 return SE.getCouldNotCompute();
10704
10705 // If the start is a non-zero constant, shift the range to simplify things.
10706 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(getStart()))
10707 if (!SC->getValue()->isZero()) {
10708 SmallVector<const SCEV *, 4> Operands(op_begin(), op_end());
10709 Operands[0] = SE.getZero(SC->getType());
10710 const SCEV *Shifted = SE.getAddRecExpr(Operands, getLoop(),
10711 getNoWrapFlags(FlagNW));
10712 if (const auto *ShiftedAddRec = dyn_cast<SCEVAddRecExpr>(Shifted))
10713 return ShiftedAddRec->getNumIterationsInRange(
10714 Range.subtract(SC->getAPInt()), SE);
10715 // This is strange and shouldn't happen.
10716 return SE.getCouldNotCompute();
10717 }
10718
10719 // The only time we can solve this is when we have all constant indices.
10720 // Otherwise, we cannot determine the overflow conditions.
10721 if (any_of(operands(), [](const SCEV *Op) { return !isa<SCEVConstant>(Op); }))
10722 return SE.getCouldNotCompute();
10723
10724 // Okay at this point we know that all elements of the chrec are constants and
10725 // that the start element is zero.
10726
10727 // First check to see if the range contains zero. If not, the first
10728 // iteration exits.
10729 unsigned BitWidth = SE.getTypeSizeInBits(getType());
10730 if (!Range.contains(APInt(BitWidth, 0)))
10731 return SE.getZero(getType());
10732
10733 if (isAffine()) {
10734 // If this is an affine expression then we have this situation:
10735 // Solve {0,+,A} in Range === Ax in Range
10736
10737 // We know that zero is in the range. If A is positive then we know that
10738 // the upper value of the range must be the first possible exit value.
10739 // If A is negative then the lower of the range is the last possible loop
10740 // value. Also note that we already checked for a full range.
10741 APInt A = cast<SCEVConstant>(getOperand(1))->getAPInt();
10742 APInt End = A.sge(1) ? (Range.getUpper() - 1) : Range.getLower();
10743
10744 // The exit value should be (End+A)/A.
10745 APInt ExitVal = (End + A).udiv(A);
10746 ConstantInt *ExitValue = ConstantInt::get(SE.getContext(), ExitVal);
10747
10748 // Evaluate at the exit value. If we really did fall out of the valid
10749 // range, then we computed our trip count, otherwise wrap around or other
10750 // things must have happened.
10751 ConstantInt *Val = EvaluateConstantChrecAtConstant(this, ExitValue, SE);
10752 if (Range.contains(Val->getValue()))
10753 return SE.getCouldNotCompute(); // Something strange happened
10754
10755 // Ensure that the previous value is in the range. This is a sanity check.
10756 assert(Range.contains(((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt
::get(SE.getContext(), ExitVal - 1), SE)->getValue()) &&
"Linear scev computation is off in a bad way!") ? static_cast
<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!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10759, __PRETTY_FUNCTION__))
10757 EvaluateConstantChrecAtConstant(this,((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt
::get(SE.getContext(), ExitVal - 1), SE)->getValue()) &&
"Linear scev computation is off in a bad way!") ? static_cast
<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!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10759, __PRETTY_FUNCTION__))
10758 ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->getValue()) &&((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt
::get(SE.getContext(), ExitVal - 1), SE)->getValue()) &&
"Linear scev computation is off in a bad way!") ? static_cast
<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!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10759, __PRETTY_FUNCTION__))
10759 "Linear scev computation is off in a bad way!")((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt
::get(SE.getContext(), ExitVal - 1), SE)->getValue()) &&
"Linear scev computation is off in a bad way!") ? static_cast
<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!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10759, __PRETTY_FUNCTION__))
;
10760 return SE.getConstant(ExitValue);
10761 }
10762
10763 if (isQuadratic()) {
10764 if (auto S = SolveQuadraticAddRecRange(this, Range, SE))
10765 return SE.getConstant(S.getValue());
10766 }
10767
10768 return SE.getCouldNotCompute();
10769}
10770
10771const SCEVAddRecExpr *
10772SCEVAddRecExpr::getPostIncExpr(ScalarEvolution &SE) const {
10773 assert(getNumOperands() > 1 && "AddRec with zero step?")((getNumOperands() > 1 && "AddRec with zero step?"
) ? static_cast<void> (0) : __assert_fail ("getNumOperands() > 1 && \"AddRec with zero step?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10773, __PRETTY_FUNCTION__))
;
10774 // There is a temptation to just call getAddExpr(this, getStepRecurrence(SE)),
10775 // but in this case we cannot guarantee that the value returned will be an
10776 // AddRec because SCEV does not have a fixed point where it stops
10777 // simplification: it is legal to return ({rec1} + {rec2}). For example, it
10778 // may happen if we reach arithmetic depth limit while simplifying. So we
10779 // construct the returned value explicitly.
10780 SmallVector<const SCEV *, 3> Ops;
10781 // If this is {A,+,B,+,C,...,+,N}, then its step is {B,+,C,+,...,+,N}, and
10782 // (this + Step) is {A+B,+,B+C,+...,+,N}.
10783 for (unsigned i = 0, e = getNumOperands() - 1; i < e; ++i)
10784 Ops.push_back(SE.getAddExpr(getOperand(i), getOperand(i + 1)));
10785 // We know that the last operand is not a constant zero (otherwise it would
10786 // have been popped out earlier). This guarantees us that if the result has
10787 // the same last operand, then it will also not be popped out, meaning that
10788 // the returned value will be an AddRec.
10789 const SCEV *Last = getOperand(getNumOperands() - 1);
10790 assert(!Last->isZero() && "Recurrency with zero step?")((!Last->isZero() && "Recurrency with zero step?")
? static_cast<void> (0) : __assert_fail ("!Last->isZero() && \"Recurrency with zero step?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10790, __PRETTY_FUNCTION__))
;
10791 Ops.push_back(Last);
10792 return cast<SCEVAddRecExpr>(SE.getAddRecExpr(Ops, getLoop(),
10793 SCEV::FlagAnyWrap));
10794}
10795
10796// Return true when S contains at least an undef value.
10797static inline bool containsUndefs(const SCEV *S) {
10798 return SCEVExprContains(S, [](const SCEV *S) {
10799 if (const auto *SU = dyn_cast<SCEVUnknown>(S))
10800 return isa<UndefValue>(SU->getValue());
10801 return false;
10802 });
10803}
10804
10805namespace {
10806
10807// Collect all steps of SCEV expressions.
10808struct SCEVCollectStrides {
10809 ScalarEvolution &SE;
10810 SmallVectorImpl<const SCEV *> &Strides;
10811
10812 SCEVCollectStrides(ScalarEvolution &SE, SmallVectorImpl<const SCEV *> &S)
10813 : SE(SE), Strides(S) {}
10814
10815 bool follow(const SCEV *S) {
10816 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S))
10817 Strides.push_back(AR->getStepRecurrence(SE));
10818 return true;
10819 }
10820
10821 bool isDone() const { return false; }
10822};
10823
10824// Collect all SCEVUnknown and SCEVMulExpr expressions.
10825struct SCEVCollectTerms {
10826 SmallVectorImpl<const SCEV *> &Terms;
10827
10828 SCEVCollectTerms(SmallVectorImpl<const SCEV *> &T) : Terms(T) {}
10829
10830 bool follow(const SCEV *S) {
10831 if (isa<SCEVUnknown>(S) || isa<SCEVMulExpr>(S) ||
10832 isa<SCEVSignExtendExpr>(S)) {
10833 if (!containsUndefs(S))
10834 Terms.push_back(S);
10835
10836 // Stop recursion: once we collected a term, do not walk its operands.
10837 return false;
10838 }
10839
10840 // Keep looking.
10841 return true;
10842 }
10843
10844 bool isDone() const { return false; }
10845};
10846
10847// Check if a SCEV contains an AddRecExpr.
10848struct SCEVHasAddRec {
10849 bool &ContainsAddRec;
10850
10851 SCEVHasAddRec(bool &ContainsAddRec) : ContainsAddRec(ContainsAddRec) {
10852 ContainsAddRec = false;
10853 }
10854
10855 bool follow(const SCEV *S) {
10856 if (isa<SCEVAddRecExpr>(S)) {
10857 ContainsAddRec = true;
10858
10859 // Stop recursion: once we collected a term, do not walk its operands.
10860 return false;
10861 }
10862
10863 // Keep looking.
10864 return true;
10865 }
10866
10867 bool isDone() const { return false; }
10868};
10869
10870// Find factors that are multiplied with an expression that (possibly as a
10871// subexpression) contains an AddRecExpr. In the expression:
10872//
10873// 8 * (100 + %p * %q * (%a + {0, +, 1}_loop))
10874//
10875// "%p * %q" are factors multiplied by the expression "(%a + {0, +, 1}_loop)"
10876// that contains the AddRec {0, +, 1}_loop. %p * %q are likely to be array size
10877// parameters as they form a product with an induction variable.
10878//
10879// This collector expects all array size parameters to be in the same MulExpr.
10880// It might be necessary to later add support for collecting parameters that are
10881// spread over different nested MulExpr.
10882struct SCEVCollectAddRecMultiplies {
10883 SmallVectorImpl<const SCEV *> &Terms;
10884 ScalarEvolution &SE;
10885
10886 SCEVCollectAddRecMultiplies(SmallVectorImpl<const SCEV *> &T, ScalarEvolution &SE)
10887 : Terms(T), SE(SE) {}
10888
10889 bool follow(const SCEV *S) {
10890 if (auto *Mul = dyn_cast<SCEVMulExpr>(S)) {
10891 bool HasAddRec = false;
10892 SmallVector<const SCEV *, 0> Operands;
10893 for (auto Op : Mul->operands()) {
10894 const SCEVUnknown *Unknown = dyn_cast<SCEVUnknown>(Op);
10895 if (Unknown && !isa<CallInst>(Unknown->getValue())) {
10896 Operands.push_back(Op);
10897 } else if (Unknown) {
10898 HasAddRec = true;
10899 } else {
10900 bool ContainsAddRec = false;
10901 SCEVHasAddRec ContiansAddRec(ContainsAddRec);
10902 visitAll(Op, ContiansAddRec);
10903 HasAddRec |= ContainsAddRec;
10904 }
10905 }
10906 if (Operands.size() == 0)
10907 return true;
10908
10909 if (!HasAddRec)
10910 return false;
10911
10912 Terms.push_back(SE.getMulExpr(Operands));
10913 // Stop recursion: once we collected a term, do not walk its operands.
10914 return false;
10915 }
10916
10917 // Keep looking.
10918 return true;
10919 }
10920
10921 bool isDone() const { return false; }
10922};
10923
10924} // end anonymous namespace
10925
10926/// Find parametric terms in this SCEVAddRecExpr. We first for parameters in
10927/// two places:
10928/// 1) The strides of AddRec expressions.
10929/// 2) Unknowns that are multiplied with AddRec expressions.
10930void ScalarEvolution::collectParametricTerms(const SCEV *Expr,
10931 SmallVectorImpl<const SCEV *> &Terms) {
10932 SmallVector<const SCEV *, 4> Strides;
10933 SCEVCollectStrides StrideCollector(*this, Strides);
10934 visitAll(Expr, StrideCollector);
10935
10936 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (false)
10937 dbgs() << "Strides:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (false)
10938 for (const SCEV *S : Strides)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (false)
10939 dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (false)
10940 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (false)
;
10941
10942 for (const SCEV *S : Strides) {
10943 SCEVCollectTerms TermCollector(Terms);
10944 visitAll(S, TermCollector);
10945 }
10946
10947 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
10948 dbgs() << "Terms:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
10949 for (const SCEV *T : Terms)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
10950 dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
10951 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
;
10952
10953 SCEVCollectAddRecMultiplies MulCollector(Terms, *this);
10954 visitAll(Expr, MulCollector);
10955}
10956
10957static bool findArrayDimensionsRec(ScalarEvolution &SE,
10958 SmallVectorImpl<const SCEV *> &Terms,
10959 SmallVectorImpl<const SCEV *> &Sizes) {
10960 int Last = Terms.size() - 1;
10961 const SCEV *Step = Terms[Last];
10962
10963 // End of recursion.
10964 if (Last == 0) {
10965 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Step)) {
10966 SmallVector<const SCEV *, 2> Qs;
10967 for (const SCEV *Op : M->operands())
10968 if (!isa<SCEVConstant>(Op))
10969 Qs.push_back(Op);
10970
10971 Step = SE.getMulExpr(Qs);
10972 }
10973
10974 Sizes.push_back(Step);
10975 return true;
10976 }
10977
10978 for (const SCEV *&Term : Terms) {
10979 // Normalize the terms before the next call to findArrayDimensionsRec.
10980 const SCEV *Q, *R;
10981 SCEVDivision::divide(SE, Term, Step, &Q, &R);
10982
10983 // Bail out when GCD does not evenly divide one of the terms.
10984 if (!R->isZero())
10985 return false;
10986
10987 Term = Q;
10988 }
10989
10990 // Remove all SCEVConstants.
10991 Terms.erase(
10992 remove_if(Terms, [](const SCEV *E) { return isa<SCEVConstant>(E); }),
10993 Terms.end());
10994
10995 if (Terms.size() > 0)
10996 if (!findArrayDimensionsRec(SE, Terms, Sizes))
10997 return false;
10998
10999 Sizes.push_back(Step);
11000 return true;
11001}
11002
11003// Returns true when one of the SCEVs of Terms contains a SCEVUnknown parameter.
11004static inline bool containsParameters(SmallVectorImpl<const SCEV *> &Terms) {
11005 for (const SCEV *T : Terms)
11006 if (SCEVExprContains(T, [](const SCEV *S) { return isa<SCEVUnknown>(S); }))
11007 return true;
11008
11009 return false;
11010}
11011
11012// Return the number of product terms in S.
11013static inline int numberOfTerms(const SCEV *S) {
11014 if (const SCEVMulExpr *Expr = dyn_cast<SCEVMulExpr>(S))
11015 return Expr->getNumOperands();
11016 return 1;
11017}
11018
11019static const SCEV *removeConstantFactors(ScalarEvolution &SE, const SCEV *T) {
11020 if (isa<SCEVConstant>(T))
11021 return nullptr;
11022
11023 if (isa<SCEVUnknown>(T))
11024 return T;
11025
11026 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(T)) {
11027 SmallVector<const SCEV *, 2> Factors;
11028 for (const SCEV *Op : M->operands())
11029 if (!isa<SCEVConstant>(Op))
11030 Factors.push_back(Op);
11031
11032 return SE.getMulExpr(Factors);
11033 }
11034
11035 return T;
11036}
11037
11038/// Return the size of an element read or written by Inst.
11039const SCEV *ScalarEvolution::getElementSize(Instruction *Inst) {
11040 Type *Ty;
11041 if (StoreInst *Store = dyn_cast<StoreInst>(Inst))
11042 Ty = Store->getValueOperand()->getType();
11043 else if (LoadInst *Load = dyn_cast<LoadInst>(Inst))
11044 Ty = Load->getType();
11045 else
11046 return nullptr;
11047
11048 Type *ETy = getEffectiveSCEVType(PointerType::getUnqual(Ty));
11049 return getSizeOfExpr(ETy, Ty);
11050}
11051
11052void ScalarEvolution::findArrayDimensions(SmallVectorImpl<const SCEV *> &Terms,
11053 SmallVectorImpl<const SCEV *> &Sizes,
11054 const SCEV *ElementSize) {
11055 if (Terms.size() < 1 || !ElementSize)
11056 return;
11057
11058 // Early return when Terms do not contain parameters: we do not delinearize
11059 // non parametric SCEVs.
11060 if (!containsParameters(Terms))
11061 return;
11062
11063 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
11064 dbgs() << "Terms:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
11065 for (const SCEV *T : Terms)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
11066 dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
11067 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
;
11068
11069 // Remove duplicates.
11070 array_pod_sort(Terms.begin(), Terms.end());
11071 Terms.erase(std::unique(Terms.begin(), Terms.end()), Terms.end());
11072
11073 // Put larger terms first.
11074 llvm::sort(Terms, [](const SCEV *LHS, const SCEV *RHS) {
11075 return numberOfTerms(LHS) > numberOfTerms(RHS);
11076 });
11077
11078 // Try to divide all terms by the element size. If term is not divisible by
11079 // element size, proceed with the original term.
11080 for (const SCEV *&Term : Terms) {
11081 const SCEV *Q, *R;
11082 SCEVDivision::divide(*this, Term, ElementSize, &Q, &R);
11083 if (!Q->isZero())
11084 Term = Q;
11085 }
11086
11087 SmallVector<const SCEV *, 4> NewTerms;
11088
11089 // Remove constant factors.
11090 for (const SCEV *T : Terms)
11091 if (const SCEV *NewT = removeConstantFactors(*this, T))
11092 NewTerms.push_back(NewT);
11093
11094 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms after sorting:\n"
; for (const SCEV *T : NewTerms) dbgs() << *T << "\n"
; }; } } while (false)
11095 dbgs() << "Terms after sorting:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms after sorting:\n"
; for (const SCEV *T : NewTerms) dbgs() << *T << "\n"
; }; } } while (false)
11096 for (const SCEV *T : NewTerms)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms after sorting:\n"
; for (const SCEV *T : NewTerms) dbgs() << *T << "\n"
; }; } } while (false)
11097 dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms after sorting:\n"
; for (const SCEV *T : NewTerms) dbgs() << *T << "\n"
; }; } } while (false)
11098 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms after sorting:\n"
; for (const SCEV *T : NewTerms) dbgs() << *T << "\n"
; }; } } while (false)
;
11099
11100 if (NewTerms.empty() || !findArrayDimensionsRec(*this, NewTerms, Sizes)) {
11101 Sizes.clear();
11102 return;
11103 }
11104
11105 // The last element to be pushed into Sizes is the size of an element.
11106 Sizes.push_back(ElementSize);
11107
11108 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(false)
11109 dbgs() << "Sizes:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(false)
11110 for (const SCEV *S : Sizes)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(false)
11111 dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(false)
11112 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(false)
;
11113}
11114
11115void ScalarEvolution::computeAccessFunctions(
11116 const SCEV *Expr, SmallVectorImpl<const SCEV *> &Subscripts,
11117 SmallVectorImpl<const SCEV *> &Sizes) {
11118 // Early exit in case this SCEV is not an affine multivariate function.
11119 if (Sizes.empty())
11120 return;
11121
11122 if (auto *AR = dyn_cast<SCEVAddRecExpr>(Expr))
11123 if (!AR->isAffine())
11124 return;
11125
11126 const SCEV *Res = Expr;
11127 int Last = Sizes.size() - 1;
11128 for (int i = Last; i >= 0; i--) {
11129 const SCEV *Q, *R;
11130 SCEVDivision::divide(*this, Res, Sizes[i], &Q, &R);
11131
11132 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Res: " << *Res
<< "\n"; dbgs() << "Sizes[i]: " << *Sizes[
i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n"
; dbgs() << "Quotient: " << *Q << "\n"; dbgs
() << "Remainder: " << *R << "\n"; }; } } while
(false)
11133 dbgs() << "Res: " << *Res << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Res: " << *Res
<< "\n"; dbgs() << "Sizes[i]: " << *Sizes[
i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n"
; dbgs() << "Quotient: " << *Q << "\n"; dbgs
() << "Remainder: " << *R << "\n"; }; } } while
(false)
11134 dbgs() << "Sizes[i]: " << *Sizes[i] << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Res: " << *Res
<< "\n"; dbgs() << "Sizes[i]: " << *Sizes[
i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n"
; dbgs() << "Quotient: " << *Q << "\n"; dbgs
() << "Remainder: " << *R << "\n"; }; } } while
(false)
11135 dbgs() << "Res divided by Sizes[i]:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Res: " << *Res
<< "\n"; dbgs() << "Sizes[i]: " << *Sizes[
i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n"
; dbgs() << "Quotient: " << *Q << "\n"; dbgs
() << "Remainder: " << *R << "\n"; }; } } while
(false)
11136 dbgs() << "Quotient: " << *Q << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Res: " << *Res
<< "\n"; dbgs() << "Sizes[i]: " << *Sizes[
i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n"
; dbgs() << "Quotient: " << *Q << "\n"; dbgs
() << "Remainder: " << *R << "\n"; }; } } while
(false)
11137 dbgs() << "Remainder: " << *R << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Res: " << *Res
<< "\n"; dbgs() << "Sizes[i]: " << *Sizes[
i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n"
; dbgs() << "Quotient: " << *Q << "\n"; dbgs
() << "Remainder: " << *R << "\n"; }; } } while
(false)
11138 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Res: " << *Res
<< "\n"; dbgs() << "Sizes[i]: " << *Sizes[
i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n"
; dbgs() << "Quotient: " << *Q << "\n"; dbgs
() << "Remainder: " << *R << "\n"; }; } } while
(false)
;
11139
11140 Res = Q;
11141
11142 // Do not record the last subscript corresponding to the size of elements in
11143 // the array.
11144 if (i == Last) {
11145
11146 // Bail out if the remainder is too complex.
11147 if (isa<SCEVAddRecExpr>(R)) {
11148 Subscripts.clear();
11149 Sizes.clear();
11150 return;
11151 }
11152
11153 continue;
11154 }
11155
11156 // Record the access function for the current subscript.
11157 Subscripts.push_back(R);
11158 }
11159
11160 // Also push in last position the remainder of the last division: it will be
11161 // the access function of the innermost dimension.
11162 Subscripts.push_back(Res);
11163
11164 std::reverse(Subscripts.begin(), Subscripts.end());
11165
11166 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (false)
11167 dbgs() << "Subscripts:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (false)
11168 for (const SCEV *S : Subscripts)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (false)
11169 dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (false)
11170 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (false)
;
11171}
11172
11173/// Splits the SCEV into two vectors of SCEVs representing the subscripts and
11174/// sizes of an array access. Returns the remainder of the delinearization that
11175/// is the offset start of the array. The SCEV->delinearize algorithm computes
11176/// the multiples of SCEV coefficients: that is a pattern matching of sub
11177/// expressions in the stride and base of a SCEV corresponding to the
11178/// computation of a GCD (greatest common divisor) of base and stride. When
11179/// SCEV->delinearize fails, it returns the SCEV unchanged.
11180///
11181/// For example: when analyzing the memory access A[i][j][k] in this loop nest
11182///
11183/// void foo(long n, long m, long o, double A[n][m][o]) {
11184///
11185/// for (long i = 0; i < n; i++)
11186/// for (long j = 0; j < m; j++)
11187/// for (long k = 0; k < o; k++)
11188/// A[i][j][k] = 1.0;
11189/// }
11190///
11191/// the delinearization input is the following AddRec SCEV:
11192///
11193/// AddRec: {{{%A,+,(8 * %m * %o)}<%for.i>,+,(8 * %o)}<%for.j>,+,8}<%for.k>
11194///
11195/// From this SCEV, we are able to say that the base offset of the access is %A
11196/// because it appears as an offset that does not divide any of the strides in
11197/// the loops:
11198///
11199/// CHECK: Base offset: %A
11200///
11201/// and then SCEV->delinearize determines the size of some of the dimensions of
11202/// the array as these are the multiples by which the strides are happening:
11203///
11204/// CHECK: ArrayDecl[UnknownSize][%m][%o] with elements of sizeof(double) bytes.
11205///
11206/// Note that the outermost dimension remains of UnknownSize because there are
11207/// no strides that would help identifying the size of the last dimension: when
11208/// the array has been statically allocated, one could compute the size of that
11209/// dimension by dividing the overall size of the array by the size of the known
11210/// dimensions: %m * %o * 8.
11211///
11212/// Finally delinearize provides the access functions for the array reference
11213/// that does correspond to A[i][j][k] of the above C testcase:
11214///
11215/// CHECK: ArrayRef[{0,+,1}<%for.i>][{0,+,1}<%for.j>][{0,+,1}<%for.k>]
11216///
11217/// The testcases are checking the output of a function pass:
11218/// DelinearizationPass that walks through all loads and stores of a function
11219/// asking for the SCEV of the memory access with respect to all enclosing
11220/// loops, calling SCEV->delinearize on that and printing the results.
11221void ScalarEvolution::delinearize(const SCEV *Expr,
11222 SmallVectorImpl<const SCEV *> &Subscripts,
11223 SmallVectorImpl<const SCEV *> &Sizes,
11224 const SCEV *ElementSize) {
11225 // First step: collect parametric terms.
11226 SmallVector<const SCEV *, 4> Terms;
11227 collectParametricTerms(Expr, Terms);
11228
11229 if (Terms.empty())
11230 return;
11231
11232 // Second step: find subscript sizes.
11233 findArrayDimensions(Terms, Sizes, ElementSize);
11234
11235 if (Sizes.empty())
11236 return;
11237
11238 // Third step: compute the access functions for each subscript.
11239 computeAccessFunctions(Expr, Subscripts, Sizes);
11240
11241 if (Subscripts.empty())
11242 return;
11243
11244 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (false)
11245 dbgs() << "succeeded to delinearize " << *Expr << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (false)
11246 dbgs() << "ArrayDecl[UnknownSize]";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (false)
11247 for (const SCEV *S : Sizes)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (false)
11248 dbgs() << "[" << *S << "]";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (false)
11249
11250 dbgs() << "\nArrayRef";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (false)
11251 for (const SCEV *S : Subscripts)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (false)
11252 dbgs() << "[" << *S << "]";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (false)
11253 dbgs() << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (false)
11254 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (false)
;
11255}
11256
11257bool ScalarEvolution::getIndexExpressionsFromGEP(
11258 const GetElementPtrInst *GEP, SmallVectorImpl<const SCEV *> &Subscripts,
11259 SmallVectorImpl<int> &Sizes) {
11260 assert(Subscripts.empty() && Sizes.empty() &&((Subscripts.empty() && Sizes.empty() && "Expected output lists to be empty on entry to this function."
) ? static_cast<void> (0) : __assert_fail ("Subscripts.empty() && Sizes.empty() && \"Expected output lists to be empty on entry to this function.\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11261, __PRETTY_FUNCTION__))
11261 "Expected output lists to be empty on entry to this function.")((Subscripts.empty() && Sizes.empty() && "Expected output lists to be empty on entry to this function."
) ? static_cast<void> (0) : __assert_fail ("Subscripts.empty() && Sizes.empty() && \"Expected output lists to be empty on entry to this function.\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11261, __PRETTY_FUNCTION__))
;
11262 assert(GEP && "getIndexExpressionsFromGEP called with a null GEP")((GEP && "getIndexExpressionsFromGEP called with a null GEP"
) ? static_cast<void> (0) : __assert_fail ("GEP && \"getIndexExpressionsFromGEP called with a null GEP\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11262, __PRETTY_FUNCTION__))
;
11263 Type *Ty = GEP->getPointerOperandType();
11264 bool DroppedFirstDim = false;
11265 for (unsigned i = 1; i < GEP->getNumOperands(); i++) {
11266 const SCEV *Expr = getSCEV(GEP->getOperand(i));
11267 if (i == 1) {
11268 if (auto *PtrTy = dyn_cast<PointerType>(Ty)) {
11269 Ty = PtrTy->getElementType();
11270 } else if (auto *ArrayTy = dyn_cast<ArrayType>(Ty)) {
11271 Ty = ArrayTy->getElementType();
11272 } else {
11273 Subscripts.clear();
11274 Sizes.clear();
11275 return false;
11276 }
11277 if (auto *Const = dyn_cast<SCEVConstant>(Expr))
11278 if (Const->getValue()->isZero()) {
11279 DroppedFirstDim = true;
11280 continue;
11281 }
11282 Subscripts.push_back(Expr);
11283 continue;
11284 }
11285
11286 auto *ArrayTy = dyn_cast<ArrayType>(Ty);
11287 if (!ArrayTy) {
11288 Subscripts.clear();
11289 Sizes.clear();
11290 return false;
11291 }
11292
11293 Subscripts.push_back(Expr);
11294 if (!(DroppedFirstDim && i == 2))
11295 Sizes.push_back(ArrayTy->getNumElements());
11296
11297 Ty = ArrayTy->getElementType();
11298 }
11299 return !Subscripts.empty();
11300}
11301
11302//===----------------------------------------------------------------------===//
11303// SCEVCallbackVH Class Implementation
11304//===----------------------------------------------------------------------===//
11305
11306void ScalarEvolution::SCEVCallbackVH::deleted() {
11307 assert(SE && "SCEVCallbackVH called with a null ScalarEvolution!")((SE && "SCEVCallbackVH called with a null ScalarEvolution!"
) ? static_cast<void> (0) : __assert_fail ("SE && \"SCEVCallbackVH called with a null ScalarEvolution!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11307, __PRETTY_FUNCTION__))
;
11308 if (PHINode *PN = dyn_cast<PHINode>(getValPtr()))
11309 SE->ConstantEvolutionLoopExitValue.erase(PN);
11310 SE->eraseValueFromMap(getValPtr());
11311 // this now dangles!
11312}
11313
11314void ScalarEvolution::SCEVCallbackVH::allUsesReplacedWith(Value *V) {
11315 assert(SE && "SCEVCallbackVH called with a null ScalarEvolution!")((SE && "SCEVCallbackVH called with a null ScalarEvolution!"
) ? static_cast<void> (0) : __assert_fail ("SE && \"SCEVCallbackVH called with a null ScalarEvolution!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11315, __PRETTY_FUNCTION__))
;
11316
11317 // Forget all the expressions associated with users of the old value,
11318 // so that future queries will recompute the expressions using the new
11319 // value.
11320 Value *Old = getValPtr();
11321 SmallVector<User *, 16> Worklist(Old->user_begin(), Old->user_end());
11322 SmallPtrSet<User *, 8> Visited;
11323 while (!Worklist.empty()) {
11324 User *U = Worklist.pop_back_val();
11325 // Deleting the Old value will cause this to dangle. Postpone
11326 // that until everything else is done.
11327 if (U == Old)
11328 continue;
11329 if (!Visited.insert(U).second)
11330 continue;
11331 if (PHINode *PN = dyn_cast<PHINode>(U))
11332 SE->ConstantEvolutionLoopExitValue.erase(PN);
11333 SE->eraseValueFromMap(U);
11334 Worklist.insert(Worklist.end(), U->user_begin(), U->user_end());
11335 }
11336 // Delete the Old value.
11337 if (PHINode *PN = dyn_cast<PHINode>(Old))
11338 SE->ConstantEvolutionLoopExitValue.erase(PN);
11339 SE->eraseValueFromMap(Old);
11340 // this now dangles!
11341}
11342
11343ScalarEvolution::SCEVCallbackVH::SCEVCallbackVH(Value *V, ScalarEvolution *se)
11344 : CallbackVH(V), SE(se) {}
11345
11346//===----------------------------------------------------------------------===//
11347// ScalarEvolution Class Implementation
11348//===----------------------------------------------------------------------===//
11349
11350ScalarEvolution::ScalarEvolution(Function &F, TargetLibraryInfo &TLI,
11351 AssumptionCache &AC, DominatorTree &DT,
11352 LoopInfo &LI)
11353 : F(F), TLI(TLI), AC(AC), DT(DT), LI(LI),
11354 CouldNotCompute(new SCEVCouldNotCompute()), ValuesAtScopes(64),
11355 LoopDispositions(64), BlockDispositions(64) {
11356 // To use guards for proving predicates, we need to scan every instruction in
11357 // relevant basic blocks, and not just terminators. Doing this is a waste of
11358 // time if the IR does not actually contain any calls to
11359 // @llvm.experimental.guard, so do a quick check and remember this beforehand.
11360 //
11361 // This pessimizes the case where a pass that preserves ScalarEvolution wants
11362 // to _add_ guards to the module when there weren't any before, and wants
11363 // ScalarEvolution to optimize based on those guards. For now we prefer to be
11364 // efficient in lieu of being smart in that rather obscure case.
11365
11366 auto *GuardDecl = F.getParent()->getFunction(
11367 Intrinsic::getName(Intrinsic::experimental_guard));
11368 HasGuards = GuardDecl && !GuardDecl->use_empty();
11369}
11370
11371ScalarEvolution::ScalarEvolution(ScalarEvolution &&Arg)
11372 : F(Arg.F), HasGuards(Arg.HasGuards), TLI(Arg.TLI), AC(Arg.AC), DT(Arg.DT),
11373 LI(Arg.LI), CouldNotCompute(std::move(Arg.CouldNotCompute)),
11374 ValueExprMap(std::move(Arg.ValueExprMap)),
11375 PendingLoopPredicates(std::move(Arg.PendingLoopPredicates)),
11376 PendingPhiRanges(std::move(Arg.PendingPhiRanges)),
11377 PendingMerges(std::move(Arg.PendingMerges)),
11378 MinTrailingZerosCache(std::move(Arg.MinTrailingZerosCache)),
11379 BackedgeTakenCounts(std::move(Arg.BackedgeTakenCounts)),
11380 PredicatedBackedgeTakenCounts(
11381 std::move(Arg.PredicatedBackedgeTakenCounts)),
11382 ConstantEvolutionLoopExitValue(
11383 std::move(Arg.ConstantEvolutionLoopExitValue)),
11384 ValuesAtScopes(std::move(Arg.ValuesAtScopes)),
11385 LoopDispositions(std::move(Arg.LoopDispositions)),
11386 LoopPropertiesCache(std::move(Arg.LoopPropertiesCache)),
11387 BlockDispositions(std::move(Arg.BlockDispositions)),
11388 UnsignedRanges(std::move(Arg.UnsignedRanges)),
11389 SignedRanges(std::move(Arg.SignedRanges)),
11390 UniqueSCEVs(std::move(Arg.UniqueSCEVs)),
11391 UniquePreds(std::move(Arg.UniquePreds)),
11392 SCEVAllocator(std::move(Arg.SCEVAllocator)),
11393 LoopUsers(std::move(Arg.LoopUsers)),
11394 PredicatedSCEVRewrites(std::move(Arg.PredicatedSCEVRewrites)),
11395 FirstUnknown(Arg.FirstUnknown) {
11396 Arg.FirstUnknown = nullptr;
11397}
11398
11399ScalarEvolution::~ScalarEvolution() {
11400 // Iterate through all the SCEVUnknown instances and call their
11401 // destructors, so that they release their references to their values.
11402 for (SCEVUnknown *U = FirstUnknown; U;) {
11403 SCEVUnknown *Tmp = U;
11404 U = U->Next;
11405 Tmp->~SCEVUnknown();
11406 }
11407 FirstUnknown = nullptr;
11408
11409 ExprValueMap.clear();
11410 ValueExprMap.clear();
11411 HasRecMap.clear();
11412
11413 // Free any extra memory created for ExitNotTakenInfo in the unlikely event
11414 // that a loop had multiple computable exits.
11415 for (auto &BTCI : BackedgeTakenCounts)
11416 BTCI.second.clear();
11417 for (auto &BTCI : PredicatedBackedgeTakenCounts)
11418 BTCI.second.clear();
11419
11420 assert(PendingLoopPredicates.empty() && "isImpliedCond garbage")((PendingLoopPredicates.empty() && "isImpliedCond garbage"
) ? static_cast<void> (0) : __assert_fail ("PendingLoopPredicates.empty() && \"isImpliedCond garbage\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11420, __PRETTY_FUNCTION__))
;
11421 assert(PendingPhiRanges.empty() && "getRangeRef garbage")((PendingPhiRanges.empty() && "getRangeRef garbage") ?
static_cast<void> (0) : __assert_fail ("PendingPhiRanges.empty() && \"getRangeRef garbage\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11421, __PRETTY_FUNCTION__))
;
11422 assert(PendingMerges.empty() && "isImpliedViaMerge garbage")((PendingMerges.empty() && "isImpliedViaMerge garbage"
) ? static_cast<void> (0) : __assert_fail ("PendingMerges.empty() && \"isImpliedViaMerge garbage\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11422, __PRETTY_FUNCTION__))
;
11423 assert(!WalkingBEDominatingConds && "isLoopBackedgeGuardedByCond garbage!")((!WalkingBEDominatingConds && "isLoopBackedgeGuardedByCond garbage!"
) ? static_cast<void> (0) : __assert_fail ("!WalkingBEDominatingConds && \"isLoopBackedgeGuardedByCond garbage!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11423, __PRETTY_FUNCTION__))
;
11424 assert(!ProvingSplitPredicate && "ProvingSplitPredicate garbage!")((!ProvingSplitPredicate && "ProvingSplitPredicate garbage!"
) ? static_cast<void> (0) : __assert_fail ("!ProvingSplitPredicate && \"ProvingSplitPredicate garbage!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11424, __PRETTY_FUNCTION__))
;
11425}
11426
11427bool ScalarEvolution::hasLoopInvariantBackedgeTakenCount(const Loop *L) {
11428 return !isa<SCEVCouldNotCompute>(getBackedgeTakenCount(L));
11429}
11430
11431static void PrintLoopInfo(raw_ostream &OS, ScalarEvolution *SE,
11432 const Loop *L) {
11433 // Print all inner loops first
11434 for (Loop *I : *L)
11435 PrintLoopInfo(OS, SE, I);
11436
11437 OS << "Loop ";
11438 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
11439 OS << ": ";
11440
11441 SmallVector<BasicBlock *, 8> ExitingBlocks;
11442 L->getExitingBlocks(ExitingBlocks);
11443 if (ExitingBlocks.size() != 1)
11444 OS << "<multiple exits> ";
11445
11446 if (SE->hasLoopInvariantBackedgeTakenCount(L))
11447 OS << "backedge-taken count is " << *SE->getBackedgeTakenCount(L) << "\n";
11448 else
11449 OS << "Unpredictable backedge-taken count.\n";
11450
11451 if (ExitingBlocks.size() > 1)
11452 for (BasicBlock *ExitingBlock : ExitingBlocks) {
11453 OS << " exit count for " << ExitingBlock->getName() << ": "
11454 << *SE->getExitCount(L, ExitingBlock) << "\n";
11455 }
11456
11457 OS << "Loop ";
11458 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
11459 OS << ": ";
11460
11461 if (!isa<SCEVCouldNotCompute>(SE->getConstantMaxBackedgeTakenCount(L))) {
11462 OS << "max backedge-taken count is " << *SE->getConstantMaxBackedgeTakenCount(L);
11463 if (SE->isBackedgeTakenCountMaxOrZero(L))
11464 OS << ", actual taken count either this or zero.";
11465 } else {
11466 OS << "Unpredictable max backedge-taken count. ";
11467 }
11468
11469 OS << "\n"
11470 "Loop ";
11471 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
11472 OS << ": ";
11473
11474 SCEVUnionPredicate Pred;
11475 auto PBT = SE->getPredicatedBackedgeTakenCount(L, Pred);
11476 if (!isa<SCEVCouldNotCompute>(PBT)) {
11477 OS << "Predicated backedge-taken count is " << *PBT << "\n";
11478 OS << " Predicates:\n";
11479 Pred.print(OS, 4);
11480 } else {
11481 OS << "Unpredictable predicated backedge-taken count. ";
11482 }
11483 OS << "\n";
11484
11485 if (SE->hasLoopInvariantBackedgeTakenCount(L)) {
11486 OS << "Loop ";
11487 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
11488 OS << ": ";
11489 OS << "Trip multiple is " << SE->getSmallConstantTripMultiple(L) << "\n";
11490 }
11491}
11492
11493static StringRef loopDispositionToStr(ScalarEvolution::LoopDisposition LD) {
11494 switch (LD) {
11495 case ScalarEvolution::LoopVariant:
11496 return "Variant";
11497 case ScalarEvolution::LoopInvariant:
11498 return "Invariant";
11499 case ScalarEvolution::LoopComputable:
11500 return "Computable";
11501 }
11502 llvm_unreachable("Unknown ScalarEvolution::LoopDisposition kind!")::llvm::llvm_unreachable_internal("Unknown ScalarEvolution::LoopDisposition kind!"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11502)
;
11503}
11504
11505void ScalarEvolution::print(raw_ostream &OS) const {
11506 // ScalarEvolution's implementation of the print method is to print
11507 // out SCEV values of all instructions that are interesting. Doing
11508 // this potentially causes it to create new SCEV objects though,
11509 // which technically conflicts with the const qualifier. This isn't
11510 // observable from outside the class though, so casting away the
11511 // const isn't dangerous.
11512 ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this);
11513
11514 if (ClassifyExpressions) {
11515 OS << "Classifying expressions for: ";
11516 F.printAsOperand(OS, /*PrintType=*/false);
11517 OS << "\n";
11518 for (Instruction &I : instructions(F))
11519 if (isSCEVable(I.getType()) && !isa<CmpInst>(I)) {
11520 OS << I << '\n';
11521 OS << " --> ";
11522 const SCEV *SV = SE.getSCEV(&I);
11523 SV->print(OS);
11524 if (!isa<SCEVCouldNotCompute>(SV)) {
11525 OS << " U: ";
11526 SE.getUnsignedRange(SV).print(OS);
11527 OS << " S: ";
11528 SE.getSignedRange(SV).print(OS);
11529 }
11530
11531 const Loop *L = LI.getLoopFor(I.getParent());
11532
11533 const SCEV *AtUse = SE.getSCEVAtScope(SV, L);
11534 if (AtUse != SV) {
11535 OS << " --> ";
11536 AtUse->print(OS);
11537 if (!isa<SCEVCouldNotCompute>(AtUse)) {
11538 OS << " U: ";
11539 SE.getUnsignedRange(AtUse).print(OS);
11540 OS << " S: ";
11541 SE.getSignedRange(AtUse).print(OS);
11542 }
11543 }
11544
11545 if (L) {
11546 OS << "\t\t" "Exits: ";
11547 const SCEV *ExitValue = SE.getSCEVAtScope(SV, L->getParentLoop());
11548 if (!SE.isLoopInvariant(ExitValue, L)) {
11549 OS << "<<Unknown>>";
11550 } else {
11551 OS << *ExitValue;
11552 }
11553
11554 bool First = true;
11555 for (auto *Iter = L; Iter; Iter = Iter->getParentLoop()) {
11556 if (First) {
11557 OS << "\t\t" "LoopDispositions: { ";
11558 First = false;
11559 } else {
11560 OS << ", ";
11561 }
11562
11563 Iter->getHeader()->printAsOperand(OS, /*PrintType=*/false);
11564 OS << ": " << loopDispositionToStr(SE.getLoopDisposition(SV, Iter));
11565 }
11566
11567 for (auto *InnerL : depth_first(L)) {
11568 if (InnerL == L)
11569 continue;
11570 if (First) {
11571 OS << "\t\t" "LoopDispositions: { ";
11572 First = false;
11573 } else {
11574 OS << ", ";
11575 }
11576
11577 InnerL->getHeader()->printAsOperand(OS, /*PrintType=*/false);
11578 OS << ": " << loopDispositionToStr(SE.getLoopDisposition(SV, InnerL));
11579 }
11580
11581 OS << " }";
11582 }
11583
11584 OS << "\n";
11585 }
11586 }
11587
11588 OS << "Determining loop execution counts for: ";
11589 F.printAsOperand(OS, /*PrintType=*/false);
11590 OS << "\n";
11591 for (Loop *I : LI)
11592 PrintLoopInfo(OS, &SE, I);
11593}
11594
11595ScalarEvolution::LoopDisposition
11596ScalarEvolution::getLoopDisposition(const SCEV *S, const Loop *L) {
11597 auto &Values = LoopDispositions[S];
11598 for (auto &V : Values) {
11599 if (V.getPointer() == L)
11600 return V.getInt();
11601 }
11602 Values.emplace_back(L, LoopVariant);
11603 LoopDisposition D = computeLoopDisposition(S, L);
11604 auto &Values2 = LoopDispositions[S];
11605 for (auto &V : make_range(Values2.rbegin(), Values2.rend())) {
11606 if (V.getPointer() == L) {
11607 V.setInt(D);
11608 break;
11609 }
11610 }
11611 return D;
11612}
11613
11614ScalarEvolution::LoopDisposition
11615ScalarEvolution::computeLoopDisposition(const SCEV *S, const Loop *L) {
11616 switch (static_cast<SCEVTypes>(S->getSCEVType())) {
11617 case scConstant:
11618 return LoopInvariant;
11619 case scTruncate:
11620 case scZeroExtend:
11621 case scSignExtend:
11622 return getLoopDisposition(cast<SCEVCastExpr>(S)->getOperand(), L);
11623 case scAddRecExpr: {
11624 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S);
11625
11626 // If L is the addrec's loop, it's computable.
11627 if (AR->getLoop() == L)
11628 return LoopComputable;
11629
11630 // Add recurrences are never invariant in the function-body (null loop).
11631 if (!L)
11632 return LoopVariant;
11633
11634 // Everything that is not defined at loop entry is variant.
11635 if (DT.dominates(L->getHeader(), AR->getLoop()->getHeader()))
11636 return LoopVariant;
11637 assert(!L->contains(AR->getLoop()) && "Containing loop's header does not"((!L->contains(AR->getLoop()) && "Containing loop's header does not"
" dominate the contained loop's header?") ? static_cast<void
> (0) : __assert_fail ("!L->contains(AR->getLoop()) && \"Containing loop's header does not\" \" dominate the contained loop's header?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11638, __PRETTY_FUNCTION__))
11638 " dominate the contained loop's header?")((!L->contains(AR->getLoop()) && "Containing loop's header does not"
" dominate the contained loop's header?") ? static_cast<void
> (0) : __assert_fail ("!L->contains(AR->getLoop()) && \"Containing loop's header does not\" \" dominate the contained loop's header?\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11638, __PRETTY_FUNCTION__))
;
11639
11640 // This recurrence is invariant w.r.t. L if AR's loop contains L.
11641 if (AR->getLoop()->contains(L))
11642 return LoopInvariant;
11643
11644 // This recurrence is variant w.r.t. L if any of its operands
11645 // are variant.
11646 for (auto *Op : AR->operands())
11647 if (!isLoopInvariant(Op, L))
11648 return LoopVariant;
11649
11650 // Otherwise it's loop-invariant.
11651 return LoopInvariant;
11652 }
11653 case scAddExpr:
11654 case scMulExpr:
11655 case scUMaxExpr:
11656 case scSMaxExpr:
11657 case scUMinExpr:
11658 case scSMinExpr: {
11659 bool HasVarying = false;
11660 for (auto *Op : cast<SCEVNAryExpr>(S)->operands()) {
11661 LoopDisposition D = getLoopDisposition(Op, L);
11662 if (D == LoopVariant)
11663 return LoopVariant;
11664 if (D == LoopComputable)
11665 HasVarying = true;
11666 }
11667 return HasVarying ? LoopComputable : LoopInvariant;
11668 }
11669 case scUDivExpr: {
11670 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
11671 LoopDisposition LD = getLoopDisposition(UDiv->getLHS(), L);
11672 if (LD == LoopVariant)
11673 return LoopVariant;
11674 LoopDisposition RD = getLoopDisposition(UDiv->getRHS(), L);
11675 if (RD == LoopVariant)
11676 return LoopVariant;
11677 return (LD == LoopInvariant && RD == LoopInvariant) ?
11678 LoopInvariant : LoopComputable;
11679 }
11680 case scUnknown:
11681 // All non-instruction values are loop invariant. All instructions are loop
11682 // invariant if they are not contained in the specified loop.
11683 // Instructions are never considered invariant in the function body
11684 // (null loop) because they are defined within the "loop".
11685 if (auto *I = dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue()))
11686 return (L && !L->contains(I)) ? LoopInvariant : LoopVariant;
11687 return LoopInvariant;
11688 case scCouldNotCompute:
11689 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11689)
;
11690 }
11691 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11691)
;
11692}
11693
11694bool ScalarEvolution::isLoopInvariant(const SCEV *S, const Loop *L) {
11695 return getLoopDisposition(S, L) == LoopInvariant;
11696}
11697
11698bool ScalarEvolution::hasComputableLoopEvolution(const SCEV *S, const Loop *L) {
11699 return getLoopDisposition(S, L) == LoopComputable;
11700}
11701
11702ScalarEvolution::BlockDisposition
11703ScalarEvolution::getBlockDisposition(const SCEV *S, const BasicBlock *BB) {
11704 auto &Values = BlockDispositions[S];
11705 for (auto &V : Values) {
11706 if (V.getPointer() == BB)
11707 return V.getInt();
11708 }
11709 Values.emplace_back(BB, DoesNotDominateBlock);
11710 BlockDisposition D = computeBlockDisposition(S, BB);
11711 auto &Values2 = BlockDispositions[S];
11712 for (auto &V : make_range(Values2.rbegin(), Values2.rend())) {
11713 if (V.getPointer() == BB) {
11714 V.setInt(D);
11715 break;
11716 }
11717 }
11718 return D;
11719}
11720
11721ScalarEvolution::BlockDisposition
11722ScalarEvolution::computeBlockDisposition(const SCEV *S, const BasicBlock *BB) {
11723 switch (static_cast<SCEVTypes>(S->getSCEVType())) {
11724 case scConstant:
11725 return ProperlyDominatesBlock;
11726 case scTruncate:
11727 case scZeroExtend:
11728 case scSignExtend:
11729 return getBlockDisposition(cast<SCEVCastExpr>(S)->getOperand(), BB);
11730 case scAddRecExpr: {
11731 // This uses a "dominates" query instead of "properly dominates" query
11732 // to test for proper dominance too, because the instruction which
11733 // produces the addrec's value is a PHI, and a PHI effectively properly
11734 // dominates its entire containing block.
11735 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S);
11736 if (!DT.dominates(AR->getLoop()->getHeader(), BB))
11737 return DoesNotDominateBlock;
11738
11739 // Fall through into SCEVNAryExpr handling.
11740 LLVM_FALLTHROUGH[[gnu::fallthrough]];
11741 }
11742 case scAddExpr:
11743 case scMulExpr:
11744 case scUMaxExpr:
11745 case scSMaxExpr:
11746 case scUMinExpr:
11747 case scSMinExpr: {
11748 const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(S);
11749 bool Proper = true;
11750 for (const SCEV *NAryOp : NAry->operands()) {
11751 BlockDisposition D = getBlockDisposition(NAryOp, BB);
11752 if (D == DoesNotDominateBlock)
11753 return DoesNotDominateBlock;
11754 if (D == DominatesBlock)
11755 Proper = false;
11756 }
11757 return Proper ? ProperlyDominatesBlock : DominatesBlock;
11758 }
11759 case scUDivExpr: {
11760 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
11761 const SCEV *LHS = UDiv->getLHS(), *RHS = UDiv->getRHS();
11762 BlockDisposition LD = getBlockDisposition(LHS, BB);
11763 if (LD == DoesNotDominateBlock)
11764 return DoesNotDominateBlock;
11765 BlockDisposition RD = getBlockDisposition(RHS, BB);
11766 if (RD == DoesNotDominateBlock)
11767 return DoesNotDominateBlock;
11768 return (LD == ProperlyDominatesBlock && RD == ProperlyDominatesBlock) ?
11769 ProperlyDominatesBlock : DominatesBlock;
11770 }
11771 case scUnknown:
11772 if (Instruction *I =
11773 dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue())) {
11774 if (I->getParent() == BB)
11775 return DominatesBlock;
11776 if (DT.properlyDominates(I->getParent(), BB))
11777 return ProperlyDominatesBlock;
11778 return DoesNotDominateBlock;
11779 }
11780 return ProperlyDominatesBlock;
11781 case scCouldNotCompute:
11782 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11782)
;
11783 }
11784 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11784)
;
11785}
11786
11787bool ScalarEvolution::dominates(const SCEV *S, const BasicBlock *BB) {
11788 return getBlockDisposition(S, BB) >= DominatesBlock;
11789}
11790
11791bool ScalarEvolution::properlyDominates(const SCEV *S, const BasicBlock *BB) {
11792 return getBlockDisposition(S, BB) == ProperlyDominatesBlock;
11793}
11794
11795bool ScalarEvolution::hasOperand(const SCEV *S, const SCEV *Op) const {
11796 return SCEVExprContains(S, [&](const SCEV *Expr) { return Expr == Op; });
11797}
11798
11799bool ScalarEvolution::ExitLimit::hasOperand(const SCEV *S) const {
11800 auto IsS = [&](const SCEV *X) { return S == X; };
11801 auto ContainsS = [&](const SCEV *X) {
11802 return !isa<SCEVCouldNotCompute>(X) && SCEVExprContains(X, IsS);
11803 };
11804 return ContainsS(ExactNotTaken) || ContainsS(MaxNotTaken);
11805}
11806
11807void
11808ScalarEvolution::forgetMemoizedResults(const SCEV *S) {
11809 ValuesAtScopes.erase(S);
11810 LoopDispositions.erase(S);
11811 BlockDispositions.erase(S);
11812 UnsignedRanges.erase(S);
11813 SignedRanges.erase(S);
11814 ExprValueMap.erase(S);
11815 HasRecMap.erase(S);
11816 MinTrailingZerosCache.erase(S);
11817
11818 for (auto I = PredicatedSCEVRewrites.begin();
11819 I != PredicatedSCEVRewrites.end();) {
11820 std::pair<const SCEV *, const Loop *> Entry = I->first;
11821 if (Entry.first == S)
11822 PredicatedSCEVRewrites.erase(I++);
11823 else
11824 ++I;
11825 }
11826
11827 auto RemoveSCEVFromBackedgeMap =
11828 [S, this](DenseMap<const Loop *, BackedgeTakenInfo> &Map) {
11829 for (auto I = Map.begin(), E = Map.end(); I != E;) {
11830 BackedgeTakenInfo &BEInfo = I->second;
11831 if (BEInfo.hasOperand(S, this)) {
11832 BEInfo.clear();
11833 Map.erase(I++);
11834 } else
11835 ++I;
11836 }
11837 };
11838
11839 RemoveSCEVFromBackedgeMap(BackedgeTakenCounts);
11840 RemoveSCEVFromBackedgeMap(PredicatedBackedgeTakenCounts);
11841}
11842
11843void
11844ScalarEvolution::getUsedLoops(const SCEV *S,
11845 SmallPtrSetImpl<const Loop *> &LoopsUsed) {
11846 struct FindUsedLoops {
11847 FindUsedLoops(SmallPtrSetImpl<const Loop *> &LoopsUsed)
11848 : LoopsUsed(LoopsUsed) {}
11849 SmallPtrSetImpl<const Loop *> &LoopsUsed;
11850 bool follow(const SCEV *S) {
11851 if (auto *AR = dyn_cast<SCEVAddRecExpr>(S))
11852 LoopsUsed.insert(AR->getLoop());
11853 return true;
11854 }
11855
11856 bool isDone() const { return false; }
11857 };
11858
11859 FindUsedLoops F(LoopsUsed);
11860 SCEVTraversal<FindUsedLoops>(F).visitAll(S);
11861}
11862
11863void ScalarEvolution::addToLoopUseLists(const SCEV *S) {
11864 SmallPtrSet<const Loop *, 8> LoopsUsed;
11865 getUsedLoops(S, LoopsUsed);
11866 for (auto *L : LoopsUsed)
11867 LoopUsers[L].push_back(S);
11868}
11869
11870void ScalarEvolution::verify() const {
11871 ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this);
11872 ScalarEvolution SE2(F, TLI, AC, DT, LI);
11873
11874 SmallVector<Loop *, 8> LoopStack(LI.begin(), LI.end());
11875
11876 // Map's SCEV expressions from one ScalarEvolution "universe" to another.
11877 struct SCEVMapper : public SCEVRewriteVisitor<SCEVMapper> {
11878 SCEVMapper(ScalarEvolution &SE) : SCEVRewriteVisitor<SCEVMapper>(SE) {}
11879
11880 const SCEV *visitConstant(const SCEVConstant *Constant) {
11881 return SE.getConstant(Constant->getAPInt());
11882 }
11883
11884 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
11885 return SE.getUnknown(Expr->getValue());
11886 }
11887
11888 const SCEV *visitCouldNotCompute(const SCEVCouldNotCompute *Expr) {
11889 return SE.getCouldNotCompute();
11890 }
11891 };
11892
11893 SCEVMapper SCM(SE2);
11894
11895 while (!LoopStack.empty()) {
11896 auto *L = LoopStack.pop_back_val();
11897 LoopStack.insert(LoopStack.end(), L->begin(), L->end());
11898
11899 auto *CurBECount = SCM.visit(
11900 const_cast<ScalarEvolution *>(this)->getBackedgeTakenCount(L));
11901 auto *NewBECount = SE2.getBackedgeTakenCount(L);
11902
11903 if (CurBECount == SE2.getCouldNotCompute() ||
11904 NewBECount == SE2.getCouldNotCompute()) {
11905 // NB! This situation is legal, but is very suspicious -- whatever pass
11906 // change the loop to make a trip count go from could not compute to
11907 // computable or vice-versa *should have* invalidated SCEV. However, we
11908 // choose not to assert here (for now) since we don't want false
11909 // positives.
11910 continue;
11911 }
11912
11913 if (containsUndefs(CurBECount) || containsUndefs(NewBECount)) {
11914 // SCEV treats "undef" as an unknown but consistent value (i.e. it does
11915 // not propagate undef aggressively). This means we can (and do) fail
11916 // verification in cases where a transform makes the trip count of a loop
11917 // go from "undef" to "undef+1" (say). The transform is fine, since in
11918 // both cases the loop iterates "undef" times, but SCEV thinks we
11919 // increased the trip count of the loop by 1 incorrectly.
11920 continue;
11921 }
11922
11923 if (SE.getTypeSizeInBits(CurBECount->getType()) >
11924 SE.getTypeSizeInBits(NewBECount->getType()))
11925 NewBECount = SE2.getZeroExtendExpr(NewBECount, CurBECount->getType());
11926 else if (SE.getTypeSizeInBits(CurBECount->getType()) <
11927 SE.getTypeSizeInBits(NewBECount->getType()))
11928 CurBECount = SE2.getZeroExtendExpr(CurBECount, NewBECount->getType());
11929
11930 const SCEV *Delta = SE2.getMinusSCEV(CurBECount, NewBECount);
11931
11932 // Unless VerifySCEVStrict is set, we only compare constant deltas.
11933 if ((VerifySCEVStrict || isa<SCEVConstant>(Delta)) && !Delta->isZero()) {
11934 dbgs() << "Trip Count for " << *L << " Changed!\n";
11935 dbgs() << "Old: " << *CurBECount << "\n";
11936 dbgs() << "New: " << *NewBECount << "\n";
11937 dbgs() << "Delta: " << *Delta << "\n";
11938 std::abort();
11939 }
11940 }
11941}
11942
11943bool ScalarEvolution::invalidate(
11944 Function &F, const PreservedAnalyses &PA,
11945 FunctionAnalysisManager::Invalidator &Inv) {
11946 // Invalidate the ScalarEvolution object whenever it isn't preserved or one
11947 // of its dependencies is invalidated.
11948 auto PAC = PA.getChecker<ScalarEvolutionAnalysis>();
11949 return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>()) ||
11950 Inv.invalidate<AssumptionAnalysis>(F, PA) ||
11951 Inv.invalidate<DominatorTreeAnalysis>(F, PA) ||
11952 Inv.invalidate<LoopAnalysis>(F, PA);
11953}
11954
11955AnalysisKey ScalarEvolutionAnalysis::Key;
11956
11957ScalarEvolution ScalarEvolutionAnalysis::run(Function &F,
11958 FunctionAnalysisManager &AM) {
11959 return ScalarEvolution(F, AM.getResult<TargetLibraryAnalysis>(F),
11960 AM.getResult<AssumptionAnalysis>(F),
11961 AM.getResult<DominatorTreeAnalysis>(F),
11962 AM.getResult<LoopAnalysis>(F));
11963}
11964
11965PreservedAnalyses
11966ScalarEvolutionVerifierPass::run(Function &F, FunctionAnalysisManager &AM) {
11967 AM.getResult<ScalarEvolutionAnalysis>(F).verify();
11968 return PreservedAnalyses::all();
11969}
11970
11971PreservedAnalyses
11972ScalarEvolutionPrinterPass::run(Function &F, FunctionAnalysisManager &AM) {
11973 // For compatibility with opt's -analyze feature under legacy pass manager
11974 // which was not ported to NPM. This keeps tests using
11975 // update_analyze_test_checks.py working.
11976 OS << "Printing analysis 'Scalar Evolution Analysis' for function '"
11977 << F.getName() << "':\n";
11978 AM.getResult<ScalarEvolutionAnalysis>(F).print(OS);
11979 return PreservedAnalyses::all();
11980}
11981
11982INITIALIZE_PASS_BEGIN(ScalarEvolutionWrapperPass, "scalar-evolution",static void *initializeScalarEvolutionWrapperPassPassOnce(PassRegistry
&Registry) {
11983 "Scalar Evolution Analysis", false, true)static void *initializeScalarEvolutionWrapperPassPassOnce(PassRegistry
&Registry) {
11984INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)initializeAssumptionCacheTrackerPass(Registry);
11985INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)initializeLoopInfoWrapperPassPass(Registry);
11986INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);
11987INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)initializeTargetLibraryInfoWrapperPassPass(Registry);
11988INITIALIZE_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
)); }
11989 "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
)); }
11990
11991char ScalarEvolutionWrapperPass::ID = 0;
11992
11993ScalarEvolutionWrapperPass::ScalarEvolutionWrapperPass() : FunctionPass(ID) {
11994 initializeScalarEvolutionWrapperPassPass(*PassRegistry::getPassRegistry());
11995}
11996
11997bool ScalarEvolutionWrapperPass::runOnFunction(Function &F) {
11998 SE.reset(new ScalarEvolution(
11999 F, getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F),
12000 getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F),
12001 getAnalysis<DominatorTreeWrapperPass>().getDomTree(),
12002 getAnalysis<LoopInfoWrapperPass>().getLoopInfo()));
12003 return false;
12004}
12005
12006void ScalarEvolutionWrapperPass::releaseMemory() { SE.reset(); }
12007
12008void ScalarEvolutionWrapperPass::print(raw_ostream &OS, const Module *) const {
12009 SE->print(OS);
12010}
12011
12012void ScalarEvolutionWrapperPass::verifyAnalysis() const {
12013 if (!VerifySCEV)
12014 return;
12015
12016 SE->verify();
12017}
12018
12019void ScalarEvolutionWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
12020 AU.setPreservesAll();
12021 AU.addRequiredTransitive<AssumptionCacheTracker>();
12022 AU.addRequiredTransitive<LoopInfoWrapperPass>();
12023 AU.addRequiredTransitive<DominatorTreeWrapperPass>();
12024 AU.addRequiredTransitive<TargetLibraryInfoWrapperPass>();
12025}
12026
12027const SCEVPredicate *ScalarEvolution::getEqualPredicate(const SCEV *LHS,
12028 const SCEV *RHS) {
12029 FoldingSetNodeID ID;
12030 assert(LHS->getType() == RHS->getType() &&((LHS->getType() == RHS->getType() && "Type mismatch between LHS and RHS"
) ? static_cast<void> (0) : __assert_fail ("LHS->getType() == RHS->getType() && \"Type mismatch between LHS and RHS\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 12031, __PRETTY_FUNCTION__))
12031 "Type mismatch between LHS and RHS")((LHS->getType() == RHS->getType() && "Type mismatch between LHS and RHS"
) ? static_cast<void> (0) : __assert_fail ("LHS->getType() == RHS->getType() && \"Type mismatch between LHS and RHS\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 12031, __PRETTY_FUNCTION__))
;
12032 // Unique this node based on the arguments
12033 ID.AddInteger(SCEVPredicate::P_Equal);
12034 ID.AddPointer(LHS);
12035 ID.AddPointer(RHS);
12036 void *IP = nullptr;
12037 if (const auto *S = UniquePreds.FindNodeOrInsertPos(ID, IP))
12038 return S;
12039 SCEVEqualPredicate *Eq = new (SCEVAllocator)
12040 SCEVEqualPredicate(ID.Intern(SCEVAllocator), LHS, RHS);
12041 UniquePreds.InsertNode(Eq, IP);
12042 return Eq;
12043}
12044
12045const SCEVPredicate *ScalarEvolution::getWrapPredicate(
12046 const SCEVAddRecExpr *AR,
12047 SCEVWrapPredicate::IncrementWrapFlags AddedFlags) {
12048 FoldingSetNodeID ID;
12049 // Unique this node based on the arguments
12050 ID.AddInteger(SCEVPredicate::P_Wrap);
12051 ID.AddPointer(AR);
12052 ID.AddInteger(AddedFlags);
12053 void *IP = nullptr;
12054 if (const auto *S = UniquePreds.FindNodeOrInsertPos(ID, IP))
12055 return S;
12056 auto *OF = new (SCEVAllocator)
12057 SCEVWrapPredicate(ID.Intern(SCEVAllocator), AR, AddedFlags);
12058 UniquePreds.InsertNode(OF, IP);
12059 return OF;
12060}
12061
12062namespace {
12063
12064class SCEVPredicateRewriter : public SCEVRewriteVisitor<SCEVPredicateRewriter> {
12065public:
12066
12067 /// Rewrites \p S in the context of a loop L and the SCEV predication
12068 /// infrastructure.
12069 ///
12070 /// If \p Pred is non-null, the SCEV expression is rewritten to respect the
12071 /// equivalences present in \p Pred.
12072 ///
12073 /// If \p NewPreds is non-null, rewrite is free to add further predicates to
12074 /// \p NewPreds such that the result will be an AddRecExpr.
12075 static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE,
12076 SmallPtrSetImpl<const SCEVPredicate *> *NewPreds,
12077 SCEVUnionPredicate *Pred) {
12078 SCEVPredicateRewriter Rewriter(L, SE, NewPreds, Pred);
12079 return Rewriter.visit(S);
12080 }
12081
12082 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
12083 if (Pred) {
12084 auto ExprPreds = Pred->getPredicatesForExpr(Expr);
12085 for (auto *Pred : ExprPreds)
12086 if (const auto *IPred = dyn_cast<SCEVEqualPredicate>(Pred))
12087 if (IPred->getLHS() == Expr)
12088 return IPred->getRHS();
12089 }
12090 return convertToAddRecWithPreds(Expr);
12091 }
12092
12093 const SCEV *visitZeroExtendExpr(const SCEVZeroExtendExpr *Expr) {
12094 const SCEV *Operand = visit(Expr->getOperand());
12095 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Operand);
12096 if (AR && AR->getLoop() == L && AR->isAffine()) {
12097 // This couldn't be folded because the operand didn't have the nuw
12098 // flag. Add the nusw flag as an assumption that we could make.
12099 const SCEV *Step = AR->getStepRecurrence(SE);
12100 Type *Ty = Expr->getType();
12101 if (addOverflowAssumption(AR, SCEVWrapPredicate::IncrementNUSW))
12102 return SE.getAddRecExpr(SE.getZeroExtendExpr(AR->getStart(), Ty),
12103 SE.getSignExtendExpr(Step, Ty), L,
12104 AR->getNoWrapFlags());
12105 }
12106 return SE.getZeroExtendExpr(Operand, Expr->getType());
12107 }
12108
12109 const SCEV *visitSignExtendExpr(const SCEVSignExtendExpr *Expr) {
12110 const SCEV *Operand = visit(Expr->getOperand());
12111 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Operand);
12112 if (AR && AR->getLoop() == L && AR->isAffine()) {
12113 // This couldn't be folded because the operand didn't have the nsw
12114 // flag. Add the nssw flag as an assumption that we could make.
12115 const SCEV *Step = AR->getStepRecurrence(SE);
12116 Type *Ty = Expr->getType();
12117 if (addOverflowAssumption(AR, SCEVWrapPredicate::IncrementNSSW))
12118 return SE.getAddRecExpr(SE.getSignExtendExpr(AR->getStart(), Ty),
12119 SE.getSignExtendExpr(Step, Ty), L,
12120 AR->getNoWrapFlags());
12121 }
12122 return SE.getSignExtendExpr(Operand, Expr->getType());
12123 }
12124
12125private:
12126 explicit SCEVPredicateRewriter(const Loop *L, ScalarEvolution &SE,
12127 SmallPtrSetImpl<const SCEVPredicate *> *NewPreds,
12128 SCEVUnionPredicate *Pred)
12129 : SCEVRewriteVisitor(SE), NewPreds(NewPreds), Pred(Pred), L(L) {}
12130
12131 bool addOverflowAssumption(const SCEVPredicate *P) {
12132 if (!NewPreds) {
12133 // Check if we've already made this assumption.
12134 return Pred && Pred->implies(P);
12135 }
12136 NewPreds->insert(P);
12137 return true;
12138 }
12139
12140 bool addOverflowAssumption(const SCEVAddRecExpr *AR,
12141 SCEVWrapPredicate::IncrementWrapFlags AddedFlags) {
12142 auto *A = SE.getWrapPredicate(AR, AddedFlags);
12143 return addOverflowAssumption(A);
12144 }
12145
12146 // If \p Expr represents a PHINode, we try to see if it can be represented
12147 // as an AddRec, possibly under a predicate (PHISCEVPred). If it is possible
12148 // to add this predicate as a runtime overflow check, we return the AddRec.
12149 // If \p Expr does not meet these conditions (is not a PHI node, or we
12150 // couldn't create an AddRec for it, or couldn't add the predicate), we just
12151 // return \p Expr.
12152 const SCEV *convertToAddRecWithPreds(const SCEVUnknown *Expr) {
12153 if (!isa<PHINode>(Expr->getValue()))
12154 return Expr;
12155 Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
12156 PredicatedRewrite = SE.createAddRecFromPHIWithCasts(Expr);
12157 if (!PredicatedRewrite)
12158 return Expr;
12159 for (auto *P : PredicatedRewrite->second){
12160 // Wrap predicates from outer loops are not supported.
12161 if (auto *WP = dyn_cast<const SCEVWrapPredicate>(P)) {
12162 auto *AR = cast<const SCEVAddRecExpr>(WP->getExpr());
12163 if (L != AR->getLoop())
12164 return Expr;
12165 }
12166 if (!addOverflowAssumption(P))
12167 return Expr;
12168 }
12169 return PredicatedRewrite->first;
12170 }
12171
12172 SmallPtrSetImpl<const SCEVPredicate *> *NewPreds;
12173 SCEVUnionPredicate *Pred;
12174 const Loop *L;
12175};
12176
12177} // end anonymous namespace
12178
12179const SCEV *ScalarEvolution::rewriteUsingPredicate(const SCEV *S, const Loop *L,
12180 SCEVUnionPredicate &Preds) {
12181 return SCEVPredicateRewriter::rewrite(S, L, *this, nullptr, &Preds);
12182}
12183
12184const SCEVAddRecExpr *ScalarEvolution::convertSCEVToAddRecWithPredicates(
12185 const SCEV *S, const Loop *L,
12186 SmallPtrSetImpl<const SCEVPredicate *> &Preds) {
12187 SmallPtrSet<const SCEVPredicate *, 4> TransformPreds;
12188 S = SCEVPredicateRewriter::rewrite(S, L, *this, &TransformPreds, nullptr);
12189 auto *AddRec = dyn_cast<SCEVAddRecExpr>(S);
12190
12191 if (!AddRec)
12192 return nullptr;
12193
12194 // Since the transformation was successful, we can now transfer the SCEV
12195 // predicates.
12196 for (auto *P : TransformPreds)
12197 Preds.insert(P);
12198
12199 return AddRec;
12200}
12201
12202/// SCEV predicates
12203SCEVPredicate::SCEVPredicate(const FoldingSetNodeIDRef ID,
12204 SCEVPredicateKind Kind)
12205 : FastID(ID), Kind(Kind) {}
12206
12207SCEVEqualPredicate::SCEVEqualPredicate(const FoldingSetNodeIDRef ID,
12208 const SCEV *LHS, const SCEV *RHS)
12209 : SCEVPredicate(ID, P_Equal), LHS(LHS), RHS(RHS) {
12210 assert(LHS->getType() == RHS->getType() && "LHS and RHS types don't match")((LHS->getType() == RHS->getType() && "LHS and RHS types don't match"
) ? static_cast<void> (0) : __assert_fail ("LHS->getType() == RHS->getType() && \"LHS and RHS types don't match\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 12210, __PRETTY_FUNCTION__))
;
12211 assert(LHS != RHS && "LHS and RHS are the same SCEV")((LHS != RHS && "LHS and RHS are the same SCEV") ? static_cast
<void> (0) : __assert_fail ("LHS != RHS && \"LHS and RHS are the same SCEV\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 12211, __PRETTY_FUNCTION__))
;
12212}
12213
12214bool SCEVEqualPredicate::implies(const SCEVPredicate *N) const {
12215 const auto *Op = dyn_cast<SCEVEqualPredicate>(N);
12216
12217 if (!Op)
12218 return false;
12219
12220 return Op->LHS == LHS && Op->RHS == RHS;
12221}
12222
12223bool SCEVEqualPredicate::isAlwaysTrue() const { return false; }
12224
12225const SCEV *SCEVEqualPredicate::getExpr() const { return LHS; }
12226
12227void SCEVEqualPredicate::print(raw_ostream &OS, unsigned Depth) const {
12228 OS.indent(Depth) << "Equal predicate: " << *LHS << " == " << *RHS << "\n";
12229}
12230
12231SCEVWrapPredicate::SCEVWrapPredicate(const FoldingSetNodeIDRef ID,
12232 const SCEVAddRecExpr *AR,
12233 IncrementWrapFlags Flags)
12234 : SCEVPredicate(ID, P_Wrap), AR(AR), Flags(Flags) {}
12235
12236const SCEV *SCEVWrapPredicate::getExpr() const { return AR; }
12237
12238bool SCEVWrapPredicate::implies(const SCEVPredicate *N) const {
12239 const auto *Op = dyn_cast<SCEVWrapPredicate>(N);
12240
12241 return Op && Op->AR == AR && setFlags(Flags, Op->Flags) == Flags;
12242}
12243
12244bool SCEVWrapPredicate::isAlwaysTrue() const {
12245 SCEV::NoWrapFlags ScevFlags = AR->getNoWrapFlags();
12246 IncrementWrapFlags IFlags = Flags;
12247
12248 if (ScalarEvolution::setFlags(ScevFlags, SCEV::FlagNSW) == ScevFlags)
12249 IFlags = clearFlags(IFlags, IncrementNSSW);
12250
12251 return IFlags == IncrementAnyWrap;
12252}
12253
12254void SCEVWrapPredicate::print(raw_ostream &OS, unsigned Depth) const {
12255 OS.indent(Depth) << *getExpr() << " Added Flags: ";
12256 if (SCEVWrapPredicate::IncrementNUSW & getFlags())
12257 OS << "<nusw>";
12258 if (SCEVWrapPredicate::IncrementNSSW & getFlags())
12259 OS << "<nssw>";
12260 OS << "\n";
12261}
12262
12263SCEVWrapPredicate::IncrementWrapFlags
12264SCEVWrapPredicate::getImpliedFlags(const SCEVAddRecExpr *AR,
12265 ScalarEvolution &SE) {
12266 IncrementWrapFlags ImpliedFlags = IncrementAnyWrap;
12267 SCEV::NoWrapFlags StaticFlags = AR->getNoWrapFlags();
12268
12269 // We can safely transfer the NSW flag as NSSW.
12270 if (ScalarEvolution::setFlags(StaticFlags, SCEV::FlagNSW) == StaticFlags)
12271 ImpliedFlags = IncrementNSSW;
12272
12273 if (ScalarEvolution::setFlags(StaticFlags, SCEV::FlagNUW) == StaticFlags) {
12274 // If the increment is positive, the SCEV NUW flag will also imply the
12275 // WrapPredicate NUSW flag.
12276 if (const auto *Step = dyn_cast<SCEVConstant>(AR->getStepRecurrence(SE)))
12277 if (Step->getValue()->getValue().isNonNegative())
12278 ImpliedFlags = setFlags(ImpliedFlags, IncrementNUSW);
12279 }
12280
12281 return ImpliedFlags;
12282}
12283
12284/// Union predicates don't get cached so create a dummy set ID for it.
12285SCEVUnionPredicate::SCEVUnionPredicate()
12286 : SCEVPredicate(FoldingSetNodeIDRef(nullptr, 0), P_Union) {}
12287
12288bool SCEVUnionPredicate::isAlwaysTrue() const {
12289 return all_of(Preds,
12290 [](const SCEVPredicate *I) { return I->isAlwaysTrue(); });
12291}
12292
12293ArrayRef<const SCEVPredicate *>
12294SCEVUnionPredicate::getPredicatesForExpr(const SCEV *Expr) {
12295 auto I = SCEVToPreds.find(Expr);
12296 if (I == SCEVToPreds.end())
12297 return ArrayRef<const SCEVPredicate *>();
12298 return I->second;
12299}
12300
12301bool SCEVUnionPredicate::implies(const SCEVPredicate *N) const {
12302 if (const auto *Set = dyn_cast<SCEVUnionPredicate>(N))
12303 return all_of(Set->Preds,
12304 [this](const SCEVPredicate *I) { return this->implies(I); });
12305
12306 auto ScevPredsIt = SCEVToPreds.find(N->getExpr());
12307 if (ScevPredsIt == SCEVToPreds.end())
12308 return false;
12309 auto &SCEVPreds = ScevPredsIt->second;
12310
12311 return any_of(SCEVPreds,
12312 [N](const SCEVPredicate *I) { return I->implies(N); });
12313}
12314
12315const SCEV *SCEVUnionPredicate::getExpr() const { return nullptr; }
12316
12317void SCEVUnionPredicate::print(raw_ostream &OS, unsigned Depth) const {
12318 for (auto Pred : Preds)
12319 Pred->print(OS, Depth);
12320}
12321
12322void SCEVUnionPredicate::add(const SCEVPredicate *N) {
12323 if (const auto *Set = dyn_cast<SCEVUnionPredicate>(N)) {
12324 for (auto Pred : Set->Preds)
12325 add(Pred);
12326 return;
12327 }
12328
12329 if (implies(N))
12330 return;
12331
12332 const SCEV *Key = N->getExpr();
12333 assert(Key && "Only SCEVUnionPredicate doesn't have an "((Key && "Only SCEVUnionPredicate doesn't have an " " associated expression!"
) ? static_cast<void> (0) : __assert_fail ("Key && \"Only SCEVUnionPredicate doesn't have an \" \" associated expression!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 12334, __PRETTY_FUNCTION__))
12334 " associated expression!")((Key && "Only SCEVUnionPredicate doesn't have an " " associated expression!"
) ? static_cast<void> (0) : __assert_fail ("Key && \"Only SCEVUnionPredicate doesn't have an \" \" associated expression!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 12334, __PRETTY_FUNCTION__))
;
12335
12336 SCEVToPreds[Key].push_back(N);
12337 Preds.push_back(N);
12338}
12339
12340PredicatedScalarEvolution::PredicatedScalarEvolution(ScalarEvolution &SE,
12341 Loop &L)
12342 : SE(SE), L(L) {}
12343
12344const SCEV *PredicatedScalarEvolution::getSCEV(Value *V) {
12345 const SCEV *Expr = SE.getSCEV(V);
12346 RewriteEntry &Entry = RewriteMap[Expr];
12347
12348 // If we already have an entry and the version matches, return it.
12349 if (Entry.second && Generation == Entry.first)
12350 return Entry.second;
12351
12352 // We found an entry but it's stale. Rewrite the stale entry
12353 // according to the current predicate.
12354 if (Entry.second)
12355 Expr = Entry.second;
12356
12357 const SCEV *NewSCEV = SE.rewriteUsingPredicate(Expr, &L, Preds);
12358 Entry = {Generation, NewSCEV};
12359
12360 return NewSCEV;
12361}
12362
12363const SCEV *PredicatedScalarEvolution::getBackedgeTakenCount() {
12364 if (!BackedgeCount) {
12365 SCEVUnionPredicate BackedgePred;
12366 BackedgeCount = SE.getPredicatedBackedgeTakenCount(&L, BackedgePred);
12367 addPredicate(BackedgePred);
12368 }
12369 return BackedgeCount;
12370}
12371
12372void PredicatedScalarEvolution::addPredicate(const SCEVPredicate &Pred) {
12373 if (Preds.implies(&Pred))
12374 return;
12375 Preds.add(&Pred);
12376 updateGeneration();
12377}
12378
12379const SCEVUnionPredicate &PredicatedScalarEvolution::getUnionPredicate() const {
12380 return Preds;
12381}
12382
12383void PredicatedScalarEvolution::updateGeneration() {
12384 // If the generation number wrapped recompute everything.
12385 if (++Generation == 0) {
12386 for (auto &II : RewriteMap) {
12387 const SCEV *Rewritten = II.second.second;
12388 II.second = {Generation, SE.rewriteUsingPredicate(Rewritten, &L, Preds)};
12389 }
12390 }
12391}
12392
12393void PredicatedScalarEvolution::setNoOverflow(
12394 Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags) {
12395 const SCEV *Expr = getSCEV(V);
12396 const auto *AR = cast<SCEVAddRecExpr>(Expr);
12397
12398 auto ImpliedFlags = SCEVWrapPredicate::getImpliedFlags(AR, SE);
12399
12400 // Clear the statically implied flags.
12401 Flags = SCEVWrapPredicate::clearFlags(Flags, ImpliedFlags);
12402 addPredicate(*SE.getWrapPredicate(AR, Flags));
12403
12404 auto II = FlagsMap.insert({V, Flags});
12405 if (!II.second)
12406 II.first->second = SCEVWrapPredicate::setFlags(Flags, II.first->second);
12407}
12408
12409bool PredicatedScalarEvolution::hasNoOverflow(
12410 Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags) {
12411 const SCEV *Expr = getSCEV(V);
12412 const auto *AR = cast<SCEVAddRecExpr>(Expr);
12413
12414 Flags = SCEVWrapPredicate::clearFlags(
12415 Flags, SCEVWrapPredicate::getImpliedFlags(AR, SE));
12416
12417 auto II = FlagsMap.find(V);
12418
12419 if (II != FlagsMap.end())
12420 Flags = SCEVWrapPredicate::clearFlags(Flags, II->second);
12421
12422 return Flags == SCEVWrapPredicate::IncrementAnyWrap;
12423}
12424
12425const SCEVAddRecExpr *PredicatedScalarEvolution::getAsAddRec(Value *V) {
12426 const SCEV *Expr = this->getSCEV(V);
12427 SmallPtrSet<const SCEVPredicate *, 4> NewPreds;
12428 auto *New = SE.convertSCEVToAddRecWithPredicates(Expr, &L, NewPreds);
12429
12430 if (!New)
12431 return nullptr;
12432
12433 for (auto *P : NewPreds)
12434 Preds.add(P);
12435
12436 updateGeneration();
12437 RewriteMap[SE.getSCEV(V)] = {Generation, New};
12438 return New;
12439}
12440
12441PredicatedScalarEvolution::PredicatedScalarEvolution(
12442 const PredicatedScalarEvolution &Init)
12443 : RewriteMap(Init.RewriteMap), SE(Init.SE), L(Init.L), Preds(Init.Preds),
12444 Generation(Init.Generation), BackedgeCount(Init.BackedgeCount) {
12445 for (auto I : Init.FlagsMap)
12446 FlagsMap.insert(I);
12447}
12448
12449void PredicatedScalarEvolution::print(raw_ostream &OS, unsigned Depth) const {
12450 // For each block.
12451 for (auto *BB : L.getBlocks())
12452 for (auto &I : *BB) {
12453 if (!SE.isSCEVable(I.getType()))
12454 continue;
12455
12456 auto *Expr = SE.getSCEV(&I);
12457 auto II = RewriteMap.find(Expr);
12458
12459 if (II == RewriteMap.end())
12460 continue;
12461
12462 // Don't print things that are not interesting.
12463 if (II->second.second == Expr)
12464 continue;
12465
12466 OS.indent(Depth) << "[PSE]" << I << ":\n";
12467 OS.indent(Depth + 2) << *Expr << "\n";
12468 OS.indent(Depth + 2) << "--> " << *II->second.second << "\n";
12469 }
12470}
12471
12472// Match the mathematical pattern A - (A / B) * B, where A and B can be
12473// arbitrary expressions.
12474// It's not always easy, as A and B can be folded (imagine A is X / 2, and B is
12475// 4, A / B becomes X / 8).
12476bool ScalarEvolution::matchURem(const SCEV *Expr, const SCEV *&LHS,
12477 const SCEV *&RHS) {
12478 const auto *Add = dyn_cast<SCEVAddExpr>(Expr);
12479 if (Add == nullptr || Add->getNumOperands() != 2)
12480 return false;
12481
12482 const SCEV *A = Add->getOperand(1);
12483 const auto *Mul = dyn_cast<SCEVMulExpr>(Add->getOperand(0));
12484
12485 if (Mul == nullptr)
12486 return false;
12487
12488 const auto MatchURemWithDivisor = [&](const SCEV *B) {
12489 // (SomeExpr + (-(SomeExpr / B) * B)).
12490 if (Expr == getURemExpr(A, B)) {
12491 LHS = A;
12492 RHS = B;
12493 return true;
12494 }
12495 return false;
12496 };
12497
12498 // (SomeExpr + (-1 * (SomeExpr / B) * B)).
12499 if (Mul->getNumOperands() == 3 && isa<SCEVConstant>(Mul->getOperand(0)))
12500 return MatchURemWithDivisor(Mul->getOperand(1)) ||
12501 MatchURemWithDivisor(Mul->getOperand(2));
12502
12503 // (SomeExpr + ((-SomeExpr / B) * B)) or (SomeExpr + ((SomeExpr / B) * -B)).
12504 if (Mul->getNumOperands() == 2)
12505 return MatchURemWithDivisor(Mul->getOperand(1)) ||
12506 MatchURemWithDivisor(Mul->getOperand(0)) ||
12507 MatchURemWithDivisor(getNegativeSCEV(Mul->getOperand(1))) ||
12508 MatchURemWithDivisor(getNegativeSCEV(Mul->getOperand(0)));
12509 return false;
12510}
12511
12512const SCEV* ScalarEvolution::computeMaxBackedgeTakenCount(const Loop *L) {
12513 SmallVector<BasicBlock*, 16> ExitingBlocks;
12514 L->getExitingBlocks(ExitingBlocks);
12515
12516 // Form an expression for the maximum exit count possible for this loop. We
12517 // merge the max and exact information to approximate a version of
12518 // getConstantMaxBackedgeTakenCount which isn't restricted to just constants.
12519 SmallVector<const SCEV*, 4> ExitCounts;
12520 for (BasicBlock *ExitingBB : ExitingBlocks) {
12521 const SCEV *ExitCount = getExitCount(L, ExitingBB);
12522 if (isa<SCEVCouldNotCompute>(ExitCount))
12523 ExitCount = getExitCount(L, ExitingBB,
12524 ScalarEvolution::ConstantMaximum);
12525 if (!isa<SCEVCouldNotCompute>(ExitCount)) {
12526 assert(DT.dominates(ExitingBB, L->getLoopLatch()) &&((DT.dominates(ExitingBB, L->getLoopLatch()) && "We should only have known counts for exiting blocks that "
"dominate latch!") ? static_cast<void> (0) : __assert_fail
("DT.dominates(ExitingBB, L->getLoopLatch()) && \"We should only have known counts for exiting blocks that \" \"dominate latch!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 12528, __PRETTY_FUNCTION__))
12527 "We should only have known counts for exiting blocks that "((DT.dominates(ExitingBB, L->getLoopLatch()) && "We should only have known counts for exiting blocks that "
"dominate latch!") ? static_cast<void> (0) : __assert_fail
("DT.dominates(ExitingBB, L->getLoopLatch()) && \"We should only have known counts for exiting blocks that \" \"dominate latch!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 12528, __PRETTY_FUNCTION__))
12528 "dominate latch!")((DT.dominates(ExitingBB, L->getLoopLatch()) && "We should only have known counts for exiting blocks that "
"dominate latch!") ? static_cast<void> (0) : __assert_fail
("DT.dominates(ExitingBB, L->getLoopLatch()) && \"We should only have known counts for exiting blocks that \" \"dominate latch!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/lib/Analysis/ScalarEvolution.cpp"
, 12528, __PRETTY_FUNCTION__))
;
12529 ExitCounts.push_back(ExitCount);
12530 }
12531 }
12532 if (ExitCounts.empty())
12533 return getCouldNotCompute();
12534 return getUMinFromMismatchedTypes(ExitCounts);
12535}

/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/include/llvm/IR/Type.h

1//===- llvm/Type.h - Classes for handling data types ------------*- C++ -*-===//
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 declaration of the Type class. For more "Type"
10// stuff, look in DerivedTypes.h.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_IR_TYPE_H
15#define LLVM_IR_TYPE_H
16
17#include "llvm/ADT/APFloat.h"
18#include "llvm/ADT/ArrayRef.h"
19#include "llvm/ADT/SmallPtrSet.h"
20#include "llvm/Support/CBindingWrapping.h"
21#include "llvm/Support/Casting.h"
22#include "llvm/Support/Compiler.h"
23#include "llvm/Support/ErrorHandling.h"
24#include "llvm/Support/TypeSize.h"
25#include <cassert>
26#include <cstdint>
27#include <iterator>
28
29namespace llvm {
30
31template<class GraphType> struct GraphTraits;
32class IntegerType;
33class LLVMContext;
34class PointerType;
35class raw_ostream;
36class StringRef;
37
38/// The instances of the Type class are immutable: once they are created,
39/// they are never changed. Also note that only one instance of a particular
40/// type is ever created. Thus seeing if two types are equal is a matter of
41/// doing a trivial pointer comparison. To enforce that no two equal instances
42/// are created, Type instances can only be created via static factory methods
43/// in class Type and in derived classes. Once allocated, Types are never
44/// free'd.
45///
46class Type {
47public:
48 //===--------------------------------------------------------------------===//
49 /// Definitions of all of the base types for the Type system. Based on this
50 /// value, you can cast to a class defined in DerivedTypes.h.
51 /// Note: If you add an element to this, you need to add an element to the
52 /// Type::getPrimitiveType function, or else things will break!
53 /// Also update LLVMTypeKind and LLVMGetTypeKind () in the C binding.
54 ///
55 enum TypeID {
56 // PrimitiveTypes
57 HalfTyID = 0, ///< 16-bit floating point type
58 BFloatTyID, ///< 16-bit floating point type (7-bit significand)
59 FloatTyID, ///< 32-bit floating point type
60 DoubleTyID, ///< 64-bit floating point type
61 X86_FP80TyID, ///< 80-bit floating point type (X87)
62 FP128TyID, ///< 128-bit floating point type (112-bit significand)
63 PPC_FP128TyID, ///< 128-bit floating point type (two 64-bits, PowerPC)
64 VoidTyID, ///< type with no size
65 LabelTyID, ///< Labels
66 MetadataTyID, ///< Metadata
67 X86_MMXTyID, ///< MMX vectors (64 bits, X86 specific)
68 TokenTyID, ///< Tokens
69
70 // Derived types... see DerivedTypes.h file.
71 IntegerTyID, ///< Arbitrary bit width integers
72 FunctionTyID, ///< Functions
73 PointerTyID, ///< Pointers
74 StructTyID, ///< Structures
75 ArrayTyID, ///< Arrays
76 FixedVectorTyID, ///< Fixed width SIMD vector type
77 ScalableVectorTyID ///< Scalable SIMD vector type
78 };
79
80private:
81 /// This refers to the LLVMContext in which this type was uniqued.
82 LLVMContext &Context;
83
84 TypeID ID : 8; // The current base type of this type.
85 unsigned SubclassData : 24; // Space for subclasses to store data.
86 // Note that this should be synchronized with
87 // MAX_INT_BITS value in IntegerType class.
88
89protected:
90 friend class LLVMContextImpl;
91
92 explicit Type(LLVMContext &C, TypeID tid)
93 : Context(C), ID(tid), SubclassData(0) {}
94 ~Type() = default;
95
96 unsigned getSubclassData() const { return SubclassData; }
97
98 void setSubclassData(unsigned val) {
99 SubclassData = val;
100 // Ensure we don't have any accidental truncation.
101 assert(getSubclassData() == val && "Subclass data too large for field")((getSubclassData() == val && "Subclass data too large for field"
) ? static_cast<void> (0) : __assert_fail ("getSubclassData() == val && \"Subclass data too large for field\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/include/llvm/IR/Type.h"
, 101, __PRETTY_FUNCTION__))
;
102 }
103
104 /// Keeps track of how many Type*'s there are in the ContainedTys list.
105 unsigned NumContainedTys = 0;
106
107 /// A pointer to the array of Types contained by this Type. For example, this
108 /// includes the arguments of a function type, the elements of a structure,
109 /// the pointee of a pointer, the element type of an array, etc. This pointer
110 /// may be 0 for types that don't contain other types (Integer, Double,
111 /// Float).
112 Type * const *ContainedTys = nullptr;
113
114public:
115 /// Print the current type.
116 /// Omit the type details if \p NoDetails == true.
117 /// E.g., let %st = type { i32, i16 }
118 /// When \p NoDetails is true, we only print %st.
119 /// Put differently, \p NoDetails prints the type as if
120 /// inlined with the operands when printing an instruction.
121 void print(raw_ostream &O, bool IsForDebug = false,
122 bool NoDetails = false) const;
123
124 void dump() const;
125
126 /// Return the LLVMContext in which this type was uniqued.
127 LLVMContext &getContext() const { return Context; }
128
129 //===--------------------------------------------------------------------===//
130 // Accessors for working with types.
131 //
132
133 /// Return the type id for the type. This will return one of the TypeID enum
134 /// elements defined above.
135 TypeID getTypeID() const { return ID; }
136
137 /// Return true if this is 'void'.
138 bool isVoidTy() const { return getTypeID() == VoidTyID; }
139
140 /// Return true if this is 'half', a 16-bit IEEE fp type.
141 bool isHalfTy() const { return getTypeID() == HalfTyID; }
142
143 /// Return true if this is 'bfloat', a 16-bit bfloat type.
144 bool isBFloatTy() const { return getTypeID() == BFloatTyID; }
145
146 /// Return true if this is 'float', a 32-bit IEEE fp type.
147 bool isFloatTy() const { return getTypeID() == FloatTyID; }
148
149 /// Return true if this is 'double', a 64-bit IEEE fp type.
150 bool isDoubleTy() const { return getTypeID() == DoubleTyID; }
151
152 /// Return true if this is x86 long double.
153 bool isX86_FP80Ty() const { return getTypeID() == X86_FP80TyID; }
154
155 /// Return true if this is 'fp128'.
156 bool isFP128Ty() const { return getTypeID() == FP128TyID; }
157
158 /// Return true if this is powerpc long double.
159 bool isPPC_FP128Ty() const { return getTypeID() == PPC_FP128TyID; }
160
161 /// Return true if this is one of the six floating-point types
162 bool isFloatingPointTy() const {
163 return getTypeID() == HalfTyID || getTypeID() == BFloatTyID ||
164 getTypeID() == FloatTyID || getTypeID() == DoubleTyID ||
165 getTypeID() == X86_FP80TyID || getTypeID() == FP128TyID ||
166 getTypeID() == PPC_FP128TyID;
167 }
168
169 const fltSemantics &getFltSemantics() const {
170 switch (getTypeID()) {
171 case HalfTyID: return APFloat::IEEEhalf();
172 case BFloatTyID: return APFloat::BFloat();
173 case FloatTyID: return APFloat::IEEEsingle();
174 case DoubleTyID: return APFloat::IEEEdouble();
175 case X86_FP80TyID: return APFloat::x87DoubleExtended();
176 case FP128TyID: return APFloat::IEEEquad();
177 case PPC_FP128TyID: return APFloat::PPCDoubleDouble();
178 default: llvm_unreachable("Invalid floating type")::llvm::llvm_unreachable_internal("Invalid floating type", "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/include/llvm/IR/Type.h"
, 178)
;
179 }
180 }
181
182 /// Return true if this is X86 MMX.
183 bool isX86_MMXTy() const { return getTypeID() == X86_MMXTyID; }
184
185 /// Return true if this is a FP type or a vector of FP.
186 bool isFPOrFPVectorTy() const { return getScalarType()->isFloatingPointTy(); }
187
188 /// Return true if this is 'label'.
189 bool isLabelTy() const { return getTypeID() == LabelTyID; }
190
191 /// Return true if this is 'metadata'.
192 bool isMetadataTy() const { return getTypeID() == MetadataTyID; }
193
194 /// Return true if this is 'token'.
195 bool isTokenTy() const { return getTypeID() == TokenTyID; }
196
197 /// True if this is an instance of IntegerType.
198 bool isIntegerTy() const { return getTypeID() == IntegerTyID; }
199
200 /// Return true if this is an IntegerType of the given width.
201 bool isIntegerTy(unsigned Bitwidth) const;
202
203 /// Return true if this is an integer type or a vector of integer types.
204 bool isIntOrIntVectorTy() const { return getScalarType()->isIntegerTy(); }
205
206 /// Return true if this is an integer type or a vector of integer types of
207 /// the given width.
208 bool isIntOrIntVectorTy(unsigned BitWidth) const {
209 return getScalarType()->isIntegerTy(BitWidth);
210 }
211
212 /// Return true if this is an integer type or a pointer type.
213 bool isIntOrPtrTy() const { return isIntegerTy() || isPointerTy(); }
3
Returning the value 1, which participates in a condition later
214
215 /// True if this is an instance of FunctionType.
216 bool isFunctionTy() const { return getTypeID() == FunctionTyID; }
217
218 /// True if this is an instance of StructType.
219 bool isStructTy() const { return getTypeID() == StructTyID; }
220
221 /// True if this is an instance of ArrayType.
222 bool isArrayTy() const { return getTypeID() == ArrayTyID; }
223
224 /// True if this is an instance of PointerType.
225 bool isPointerTy() const { return getTypeID() == PointerTyID; }
226
227 /// Return true if this is a pointer type or a vector of pointer types.
228 bool isPtrOrPtrVectorTy() const { return getScalarType()->isPointerTy(); }
229
230 /// True if this is an instance of VectorType.
231 inline bool isVectorTy() const {
232 return getTypeID() == ScalableVectorTyID || getTypeID() == FixedVectorTyID;
233 }
234
235 /// Return true if this type could be converted with a lossless BitCast to
236 /// type 'Ty'. For example, i8* to i32*. BitCasts are valid for types of the
237 /// same size only where no re-interpretation of the bits is done.
238 /// Determine if this type could be losslessly bitcast to Ty
239 bool canLosslesslyBitCastTo(Type *Ty) const;
240
241 /// Return true if this type is empty, that is, it has no elements or all of
242 /// its elements are empty.
243 bool isEmptyTy() const;
244
245 /// Return true if the type is "first class", meaning it is a valid type for a
246 /// Value.
247 bool isFirstClassType() const {
248 return getTypeID() != FunctionTyID && getTypeID() != VoidTyID;
249 }
250
251 /// Return true if the type is a valid type for a register in codegen. This
252 /// includes all first-class types except struct and array types.
253 bool isSingleValueType() const {
254 return isFloatingPointTy() || isX86_MMXTy() || isIntegerTy() ||
255 isPointerTy() || isVectorTy();
256 }
257
258 /// Return true if the type is an aggregate type. This means it is valid as
259 /// the first operand of an insertvalue or extractvalue instruction. This
260 /// includes struct and array types, but does not include vector types.
261 bool isAggregateType() const {
262 return getTypeID() == StructTyID || getTypeID() == ArrayTyID;
263 }
264
265 /// Return true if it makes sense to take the size of this type. To get the
266 /// actual size for a particular target, it is reasonable to use the
267 /// DataLayout subsystem to do this.
268 bool isSized(SmallPtrSetImpl<Type*> *Visited = nullptr) const {
269 // If it's a primitive, it is always sized.
270 if (getTypeID() == IntegerTyID || isFloatingPointTy() ||
271 getTypeID() == PointerTyID ||
272 getTypeID() == X86_MMXTyID)
273 return true;
274 // If it is not something that can have a size (e.g. a function or label),
275 // it doesn't have a size.
276 if (getTypeID() != StructTyID && getTypeID() != ArrayTyID && !isVectorTy())
277 return false;
278 // Otherwise we have to try harder to decide.
279 return isSizedDerivedType(Visited);
280 }
281
282 /// Return the basic size of this type if it is a primitive type. These are
283 /// fixed by LLVM and are not target-dependent.
284 /// This will return zero if the type does not have a size or is not a
285 /// primitive type.
286 ///
287 /// If this is a scalable vector type, the scalable property will be set and
288 /// the runtime size will be a positive integer multiple of the base size.
289 ///
290 /// Note that this may not reflect the size of memory allocated for an
291 /// instance of the type or the number of bytes that are written when an
292 /// instance of the type is stored to memory. The DataLayout class provides
293 /// additional query functions to provide this information.
294 ///
295 TypeSize getPrimitiveSizeInBits() const LLVM_READONLY__attribute__((__pure__));
296
297 /// If this is a vector type, return the getPrimitiveSizeInBits value for the
298 /// element type. Otherwise return the getPrimitiveSizeInBits value for this
299 /// type.
300 unsigned getScalarSizeInBits() const LLVM_READONLY__attribute__((__pure__));
301
302 /// Return the width of the mantissa of this type. This is only valid on
303 /// floating-point types. If the FP type does not have a stable mantissa (e.g.
304 /// ppc long double), this method returns -1.
305 int getFPMantissaWidth() const;
306
307 /// If this is a vector type, return the element type, otherwise return
308 /// 'this'.
309 inline Type *getScalarType() const {
310 if (isVectorTy())
311 return getContainedType(0);
312 return const_cast<Type *>(this);
313 }
314
315 //===--------------------------------------------------------------------===//
316 // Type Iteration support.
317 //
318 using subtype_iterator = Type * const *;
319
320 subtype_iterator subtype_begin() const { return ContainedTys; }
321 subtype_iterator subtype_end() const { return &ContainedTys[NumContainedTys];}
322 ArrayRef<Type*> subtypes() const {
323 return makeArrayRef(subtype_begin(), subtype_end());
324 }
325
326 using subtype_reverse_iterator = std::reverse_iterator<subtype_iterator>;
327
328 subtype_reverse_iterator subtype_rbegin() const {
329 return subtype_reverse_iterator(subtype_end());
330 }
331 subtype_reverse_iterator subtype_rend() const {
332 return subtype_reverse_iterator(subtype_begin());
333 }
334
335 /// This method is used to implement the type iterator (defined at the end of
336 /// the file). For derived types, this returns the types 'contained' in the
337 /// derived type.
338 Type *getContainedType(unsigned i) const {
339 assert(i < NumContainedTys && "Index out of range!")((i < NumContainedTys && "Index out of range!") ? static_cast
<void> (0) : __assert_fail ("i < NumContainedTys && \"Index out of range!\""
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/include/llvm/IR/Type.h"
, 339, __PRETTY_FUNCTION__))
;
340 return ContainedTys[i];
341 }
342
343 /// Return the number of types in the derived type.
344 unsigned getNumContainedTypes() const { return NumContainedTys; }
345
346 //===--------------------------------------------------------------------===//
347 // Helper methods corresponding to subclass methods. This forces a cast to
348 // the specified subclass and calls its accessor. "getArrayNumElements" (for
349 // example) is shorthand for cast<ArrayType>(Ty)->getNumElements(). This is
350 // only intended to cover the core methods that are frequently used, helper
351 // methods should not be added here.
352
353 inline unsigned getIntegerBitWidth() const;
354
355 inline Type *getFunctionParamType(unsigned i) const;
356 inline unsigned getFunctionNumParams() const;
357 inline bool isFunctionVarArg() const;
358
359 inline StringRef getStructName() const;
360 inline unsigned getStructNumElements() const;
361 inline Type *getStructElementType(unsigned N) const;
362
363 inline uint64_t getArrayNumElements() const;
364
365 Type *getArrayElementType() const {
366 assert(getTypeID() == ArrayTyID)((getTypeID() == ArrayTyID) ? static_cast<void> (0) : __assert_fail
("getTypeID() == ArrayTyID", "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/include/llvm/IR/Type.h"
, 366, __PRETTY_FUNCTION__))
;
367 return ContainedTys[0];
368 }
369
370 Type *getPointerElementType() const {
371 assert(getTypeID() == PointerTyID)((getTypeID() == PointerTyID) ? static_cast<void> (0) :
__assert_fail ("getTypeID() == PointerTyID", "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/include/llvm/IR/Type.h"
, 371, __PRETTY_FUNCTION__))
;
372 return ContainedTys[0];
373 }
374
375 /// Given an integer or vector type, change the lane bitwidth to NewBitwidth,
376 /// whilst keeping the old number of lanes.
377 inline Type *getWithNewBitWidth(unsigned NewBitWidth) const;
378
379 /// Given scalar/vector integer type, returns a type with elements twice as
380 /// wide as in the original type. For vectors, preserves element count.
381 inline Type *getExtendedType() const;
382
383 /// Get the address space of this pointer or pointer vector type.
384 inline unsigned getPointerAddressSpace() const;
385
386 //===--------------------------------------------------------------------===//
387 // Static members exported by the Type class itself. Useful for getting
388 // instances of Type.
389 //
390
391 /// Return a type based on an identifier.
392 static Type *getPrimitiveType(LLVMContext &C, TypeID IDNumber);
393
394 //===--------------------------------------------------------------------===//
395 // These are the builtin types that are always available.
396 //
397 static Type *getVoidTy(LLVMContext &C);
398 static Type *getLabelTy(LLVMContext &C);
399 static Type *getHalfTy(LLVMContext &C);
400 static Type *getBFloatTy(LLVMContext &C);
401 static Type *getFloatTy(LLVMContext &C);
402 static Type *getDoubleTy(LLVMContext &C);
403 static Type *getMetadataTy(LLVMContext &C);
404 static Type *getX86_FP80Ty(LLVMContext &C);
405 static Type *getFP128Ty(LLVMContext &C);
406 static Type *getPPC_FP128Ty(LLVMContext &C);
407 static Type *getX86_MMXTy(LLVMContext &C);
408 static Type *getTokenTy(LLVMContext &C);
409 static IntegerType *getIntNTy(LLVMContext &C, unsigned N);
410 static IntegerType *getInt1Ty(LLVMContext &C);
411 static IntegerType *getInt8Ty(LLVMContext &C);
412 static IntegerType *getInt16Ty(LLVMContext &C);
413 static IntegerType *getInt32Ty(LLVMContext &C);
414 static IntegerType *getInt64Ty(LLVMContext &C);
415 static IntegerType *getInt128Ty(LLVMContext &C);
416 template <typename ScalarTy> static Type *getScalarTy(LLVMContext &C) {
417 int noOfBits = sizeof(ScalarTy) * CHAR_BIT8;
418 if (std::is_integral<ScalarTy>::value) {
419 return (Type*) Type::getIntNTy(C, noOfBits);
420 } else if (std::is_floating_point<ScalarTy>::value) {
421 switch (noOfBits) {
422 case 32:
423 return Type::getFloatTy(C);
424 case 64:
425 return Type::getDoubleTy(C);
426 }
427 }
428 llvm_unreachable("Unsupported type in Type::getScalarTy")::llvm::llvm_unreachable_internal("Unsupported type in Type::getScalarTy"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/include/llvm/IR/Type.h"
, 428)
;
429 }
430
431 //===--------------------------------------------------------------------===//
432 // Convenience methods for getting pointer types with one of the above builtin
433 // types as pointee.
434 //
435 static PointerType *getHalfPtrTy(LLVMContext &C, unsigned AS = 0);
436 static PointerType *getBFloatPtrTy(LLVMContext &C, unsigned AS = 0);
437 static PointerType *getFloatPtrTy(LLVMContext &C, unsigned AS = 0);
438 static PointerType *getDoublePtrTy(LLVMContext &C, unsigned AS = 0);
439 static PointerType *getX86_FP80PtrTy(LLVMContext &C, unsigned AS = 0);
440 static PointerType *getFP128PtrTy(LLVMContext &C, unsigned AS = 0);
441 static PointerType *getPPC_FP128PtrTy(LLVMContext &C, unsigned AS = 0);
442 static PointerType *getX86_MMXPtrTy(LLVMContext &C, unsigned AS = 0);
443 static PointerType *getIntNPtrTy(LLVMContext &C, unsigned N, unsigned AS = 0);
444 static PointerType *getInt1PtrTy(LLVMContext &C, unsigned AS = 0);
445 static PointerType *getInt8PtrTy(LLVMContext &C, unsigned AS = 0);
446 static PointerType *getInt16PtrTy(LLVMContext &C, unsigned AS = 0);
447 static PointerType *getInt32PtrTy(LLVMContext &C, unsigned AS = 0);
448 static PointerType *getInt64PtrTy(LLVMContext &C, unsigned AS = 0);
449
450 /// Return a pointer to the current type. This is equivalent to
451 /// PointerType::get(Foo, AddrSpace).
452 PointerType *getPointerTo(unsigned AddrSpace = 0) const;
453
454private:
455 /// Derived types like structures and arrays are sized iff all of the members
456 /// of the type are sized as well. Since asking for their size is relatively
457 /// uncommon, move this operation out-of-line.
458 bool isSizedDerivedType(SmallPtrSetImpl<Type*> *Visited = nullptr) const;
459};
460
461// Printing of types.
462inline raw_ostream &operator<<(raw_ostream &OS, const Type &T) {
463 T.print(OS);
464 return OS;
465}
466
467// allow isa<PointerType>(x) to work without DerivedTypes.h included.
468template <> struct isa_impl<PointerType, Type> {
469 static inline bool doit(const Type &Ty) {
470 return Ty.getTypeID() == Type::PointerTyID;
471 }
472};
473
474// Create wrappers for C Binding types (see CBindingWrapping.h).
475DEFINE_ISA_CONVERSION_FUNCTIONS(Type, LLVMTypeRef)inline Type *unwrap(LLVMTypeRef P) { return reinterpret_cast<
Type*>(P); } inline LLVMTypeRef wrap(const Type *P) { return
reinterpret_cast<LLVMTypeRef>(const_cast<Type*>(
P)); } template<typename T> inline T *unwrap(LLVMTypeRef
P) { return cast<T>(unwrap(P)); }
476
477/* Specialized opaque type conversions.
478 */
479inline Type **unwrap(LLVMTypeRef* Tys) {
480 return reinterpret_cast<Type**>(Tys);
481}
482
483inline LLVMTypeRef *wrap(Type **Tys) {
484 return reinterpret_cast<LLVMTypeRef*>(const_cast<Type**>(Tys));
485}
486
487} // end namespace llvm
488
489#endif // LLVM_IR_TYPE_H

/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/include/llvm/ADT/Optional.h

1//===- Optional.h - Simple variant for passing optional values --*- C++ -*-===//
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 provides Optional, a template class modeled in the spirit of
10// OCaml's 'opt' variant. The idea is to strongly type whether or not
11// a value can be optional.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_ADT_OPTIONAL_H
16#define LLVM_ADT_OPTIONAL_H
17
18#include "llvm/ADT/None.h"
19#include "llvm/Support/Compiler.h"
20#include "llvm/Support/type_traits.h"
21#include <cassert>
22#include <memory>
23#include <new>
24#include <utility>
25
26namespace llvm {
27
28class raw_ostream;
29
30namespace optional_detail {
31
32struct in_place_t {};
33
34/// Storage for any type.
35template <typename T, bool = is_trivially_copyable<T>::value>
36class OptionalStorage {
37 union {
38 char empty;
39 T value;
40 };
41 bool hasVal;
42
43public:
44 ~OptionalStorage() { reset(); }
45
46 constexpr OptionalStorage() noexcept : empty(), hasVal(false) {}
47
48 constexpr OptionalStorage(OptionalStorage const &other) : OptionalStorage() {
49 if (other.hasValue()) {
50 emplace(other.value);
51 }
52 }
53 constexpr OptionalStorage(OptionalStorage &&other) : OptionalStorage() {
54 if (other.hasValue()) {
55 emplace(std::move(other.value));
56 }
57 }
58
59 template <class... Args>
60 constexpr explicit OptionalStorage(in_place_t, Args &&... args)
61 : value(std::forward<Args>(args)...), hasVal(true) {}
62
63 void reset() noexcept {
64 if (hasVal) {
65 value.~T();
66 hasVal = false;
67 }
68 }
69
70 constexpr bool hasValue() const noexcept { return hasVal; }
71
72 T &getValue() LLVM_LVALUE_FUNCTION& noexcept {
73 assert(hasVal)((hasVal) ? static_cast<void> (0) : __assert_fail ("hasVal"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/include/llvm/ADT/Optional.h"
, 73, __PRETTY_FUNCTION__))
;
74 return value;
75 }
76 constexpr T const &getValue() const LLVM_LVALUE_FUNCTION& noexcept {
77 assert(hasVal)((hasVal) ? static_cast<void> (0) : __assert_fail ("hasVal"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/include/llvm/ADT/Optional.h"
, 77, __PRETTY_FUNCTION__))
;
78 return value;
79 }
80#if LLVM_HAS_RVALUE_REFERENCE_THIS1
81 T &&getValue() && noexcept {
82 assert(hasVal)((hasVal) ? static_cast<void> (0) : __assert_fail ("hasVal"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/include/llvm/ADT/Optional.h"
, 82, __PRETTY_FUNCTION__))
;
83 return std::move(value);
84 }
85#endif
86
87 template <class... Args> void emplace(Args &&... args) {
88 reset();
89 ::new ((void *)std::addressof(value)) T(std::forward<Args>(args)...);
90 hasVal = true;
91 }
92
93 OptionalStorage &operator=(T const &y) {
94 if (hasValue()) {
95 value = y;
96 } else {
97 ::new ((void *)std::addressof(value)) T(y);
98 hasVal = true;
99 }
100 return *this;
101 }
102 OptionalStorage &operator=(T &&y) {
103 if (hasValue()) {
104 value = std::move(y);
105 } else {
106 ::new ((void *)std::addressof(value)) T(std::move(y));
107 hasVal = true;
108 }
109 return *this;
110 }
111
112 OptionalStorage &operator=(OptionalStorage const &other) {
113 if (other.hasValue()) {
114 if (hasValue()) {
115 value = other.value;
116 } else {
117 ::new ((void *)std::addressof(value)) T(other.value);
118 hasVal = true;
119 }
120 } else {
121 reset();
122 }
123 return *this;
124 }
125
126 OptionalStorage &operator=(OptionalStorage &&other) {
127 if (other.hasValue()) {
128 if (hasValue()) {
129 value = std::move(other.value);
130 } else {
131 ::new ((void *)std::addressof(value)) T(std::move(other.value));
132 hasVal = true;
133 }
134 } else {
135 reset();
136 }
137 return *this;
138 }
139};
140
141template <typename T> class OptionalStorage<T, true> {
142 union {
143 char empty;
144 T value;
145 };
146 bool hasVal = false;
147
148public:
149 ~OptionalStorage() = default;
150
151 constexpr OptionalStorage() noexcept : empty{} {}
152
153 constexpr OptionalStorage(OptionalStorage const &other) = default;
154 constexpr OptionalStorage(OptionalStorage &&other) = default;
155
156 OptionalStorage &operator=(OptionalStorage const &other) = default;
157 OptionalStorage &operator=(OptionalStorage &&other) = default;
158
159 template <class... Args>
160 constexpr explicit OptionalStorage(in_place_t, Args &&... args)
161 : value(std::forward<Args>(args)...), hasVal(true) {}
35
Value assigned to 'BO.Storage..value.Opcode', which participates in a condition later
36
Null pointer value stored to 'BO.Storage..value.LHS'
162
163 void reset() noexcept {
164 if (hasVal) {
165 value.~T();
166 hasVal = false;
167 }
168 }
169
170 constexpr bool hasValue() const noexcept { return hasVal; }
43
Returning the value 1, which participates in a condition later
171
172 T &getValue() LLVM_LVALUE_FUNCTION& noexcept {
173 assert(hasVal)((hasVal) ? static_cast<void> (0) : __assert_fail ("hasVal"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/include/llvm/ADT/Optional.h"
, 173, __PRETTY_FUNCTION__))
;
174 return value;
175 }
176 constexpr T const &getValue() const LLVM_LVALUE_FUNCTION& noexcept {
177 assert(hasVal)((hasVal) ? static_cast<void> (0) : __assert_fail ("hasVal"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/include/llvm/ADT/Optional.h"
, 177, __PRETTY_FUNCTION__))
;
178 return value;
179 }
180#if LLVM_HAS_RVALUE_REFERENCE_THIS1
181 T &&getValue() && noexcept {
182 assert(hasVal)((hasVal) ? static_cast<void> (0) : __assert_fail ("hasVal"
, "/build/llvm-toolchain-snapshot-12~++20200917111122+b03c2b8395b/llvm/include/llvm/ADT/Optional.h"
, 182, __PRETTY_FUNCTION__))
;
183 return std::move(value);
184 }
185#endif
186
187 template <class... Args> void emplace(Args &&... args) {
188 reset();
189 ::new ((void *)std::addressof(value)) T(std::forward<Args>(args)...);
190 hasVal = true;
191 }
192
193 OptionalStorage &operator=(T const &y) {
194 if (hasValue()) {
195 value = y;
196 } else {
197 ::new ((void *)std::addressof(value)) T(y);
198 hasVal = true;
199 }
200 return *this;
201 }
202 OptionalStorage &operator=(T &&y) {
203 if (hasValue()) {
204 value = std::move(y);
205 } else {
206 ::new ((void *)std::addressof(value)) T(std::move(y));
207 hasVal = true;
208 }
209 return *this;
210 }
211};
212
213} // namespace optional_detail
214
215template <typename T> class Optional {
216 optional_detail::OptionalStorage<T> Storage;
217
218public:
219 using value_type = T;
220
221 constexpr Optional() {}
222 constexpr Optional(NoneType) {}
223
224 constexpr Optional(const T &y) : Storage(optional_detail::in_place_t{}, y) {}
225 constexpr Optional(const Optional &O) = default;
226
227 constexpr Optional(T &&y)
228 : Storage(optional_detail::in_place_t{}, std::move(y)) {}
34
Calling constructor for 'OptionalStorage<(anonymous namespace)::BinaryOp, true>'
37
Returning from constructor for 'OptionalStorage<(anonymous namespace)::BinaryOp, true>'
229 constexpr Optional(Optional &&O) = default;
230
231 Optional &operator=(T &&y) {
232 Storage = std::move(y);
233 return *this;
234 }
235 Optional &operator=(Optional &&O) = default;
236
237 /// Create a new object by constructing it in place with the given arguments.
238 template <typename... ArgTypes> void emplace(ArgTypes &&... Args) {
239 Storage.emplace(std::forward<ArgTypes>(Args)...);
240 }
241
242 static constexpr Optional create(const T *y) {
243 return y ? Optional(*y) : Optional();
244 }
245
246 Optional &operator=(const T &y) {
247 Storage = y;
248 return *this;
249 }
250 Optional &operator=(const Optional &O) = default;
251
252 void reset() { Storage.reset(); }
253
254 constexpr const T *getPointer() const { return &Storage.getValue(); }
255 T *getPointer() { return &Storage.getValue(); }
256 constexpr const T &getValue() const LLVM_LVALUE_FUNCTION& {
257 return Storage.getValue();
258 }
259 T &getValue() LLVM_LVALUE_FUNCTION& { return Storage.getValue(); }
260
261 constexpr explicit operator bool() const { return hasValue(); }
41
Calling 'Optional::hasValue'
46
Returning from 'Optional::hasValue'
47
Returning the value 1, which participates in a condition later
262 constexpr bool hasValue() const { return Storage.hasValue(); }
42
Calling 'OptionalStorage::hasValue'
44
Returning from 'OptionalStorage::hasValue'
45
Returning the value 1, which participates in a condition later
263 constexpr const T *operator->() const { return getPointer(); }
264 T *operator->() { return getPointer(); }
265 constexpr const T &operator*() const LLVM_LVALUE_FUNCTION& {
266 return getValue();
267 }
268 T &operator*() LLVM_LVALUE_FUNCTION& { return getValue(); }
269
270 template <typename U>
271 constexpr T getValueOr(U &&value) const LLVM_LVALUE_FUNCTION& {
272 return hasValue() ? getValue() : std::forward<U>(value);
273 }
274
275 /// Apply a function to the value if present; otherwise return None.
276 template <class Function>
277 auto map(const Function &F) const LLVM_LVALUE_FUNCTION&
278 -> Optional<decltype(F(getValue()))> {
279 if (*this) return F(getValue());
280 return None;
281 }
282
283#if LLVM_HAS_RVALUE_REFERENCE_THIS1
284 T &&getValue() && { return std::move(Storage.getValue()); }
285 T &&operator*() && { return std::move(Storage.getValue()); }
286
287 template <typename U>
288 T getValueOr(U &&value) && {
289 return hasValue() ? std::move(getValue()) : std::forward<U>(value);
290 }
291
292 /// Apply a function to the value if present; otherwise return None.
293 template <class Function>
294 auto map(const Function &F) &&
295 -> Optional<decltype(F(std::move(*this).getValue()))> {
296 if (*this) return F(std::move(*this).getValue());
297 return None;
298 }
299#endif
300};
301
302template <typename T, typename U>
303constexpr bool operator==(const Optional<T> &X, const Optional<U> &Y) {
304 if (X && Y)
305 return *X == *Y;
306 return X.hasValue() == Y.hasValue();
307}
308
309template <typename T, typename U>
310constexpr bool operator!=(const Optional<T> &X, const Optional<U> &Y) {
311 return !(X == Y);
312}
313
314template <typename T, typename U>
315constexpr bool operator<(const Optional<T> &X, const Optional<U> &Y) {
316 if (X && Y)
317 return *X < *Y;
318 return X.hasValue() < Y.hasValue();
319}
320
321template <typename T, typename U>
322constexpr bool operator<=(const Optional<T> &X, const Optional<U> &Y) {
323 return !(Y < X);
324}
325
326template <typename T, typename U>
327constexpr bool operator>(const Optional<T> &X, const Optional<U> &Y) {
328 return Y < X;
329}
330
331template <typename T, typename U>
332constexpr bool operator>=(const Optional<T> &X, const Optional<U> &Y) {
333 return !(X < Y);
334}
335
336template <typename T>
337constexpr bool operator==(const Optional<T> &X, NoneType) {
338 return !X;
339}
340
341template <typename T>
342constexpr bool operator==(NoneType, const Optional<T> &X) {
343 return X == None;
344}
345
346template <typename T>
347constexpr bool operator!=(const Optional<T> &X, NoneType) {
348 return !(X == None);
349}
350
351template <typename T>
352constexpr bool operator!=(NoneType, const Optional<T> &X) {
353 return X != None;
354}
355
356template <typename T> constexpr bool operator<(const Optional<T> &X, NoneType) {
357 return false;
358}
359
360template <typename T> constexpr bool operator<(NoneType, const Optional<T> &X) {
361 return X.hasValue();
362}
363
364template <typename T>
365constexpr bool operator<=(const Optional<T> &X, NoneType) {
366 return !(None < X);
367}
368
369template <typename T>
370constexpr bool operator<=(NoneType, const Optional<T> &X) {
371 return !(X < None);
372}
373
374template <typename T> constexpr bool operator>(const Optional<T> &X, NoneType) {
375 return None < X;
376}
377
378template <typename T> constexpr bool operator>(NoneType, const Optional<T> &X) {
379 return X < None;
380}
381
382template <typename T>
383constexpr bool operator>=(const Optional<T> &X, NoneType) {
384 return None <= X;
385}
386
387template <typename T>
388constexpr bool operator>=(NoneType, const Optional<T> &X) {
389 return X <= None;
390}
391
392template <typename T>
393constexpr bool operator==(const Optional<T> &X, const T &Y) {
394 return X && *X == Y;
395}
396
397template <typename T>
398constexpr bool operator==(const T &X, const Optional<T> &Y) {
399 return Y && X == *Y;
400}
401
402template <typename T>
403constexpr bool operator!=(const Optional<T> &X, const T &Y) {
404 return !(X == Y);
405}
406
407template <typename T>
408constexpr bool operator!=(const T &X, const Optional<T> &Y) {
409 return !(X == Y);
410}
411
412template <typename T>
413constexpr bool operator<(const Optional<T> &X, const T &Y) {
414 return !X || *X < Y;
415}
416
417template <typename T>
418constexpr bool operator<(const T &X, const Optional<T> &Y) {
419 return Y && X < *Y;
420}
421
422template <typename T>
423constexpr bool operator<=(const Optional<T> &X, const T &Y) {
424 return !(Y < X);
425}
426
427template <typename T>
428constexpr bool operator<=(const T &X, const Optional<T> &Y) {
429 return !(Y < X);
430}
431
432template <typename T>
433constexpr bool operator>(const Optional<T> &X, const T &Y) {
434 return Y < X;
435}
436
437template <typename T>
438constexpr bool operator>(const T &X, const Optional<T> &Y) {
439 return Y < X;
440}
441
442template <typename T>
443constexpr bool operator>=(const Optional<T> &X, const T &Y) {
444 return !(X < Y);
445}
446
447template <typename T>
448constexpr bool operator>=(const T &X, const Optional<T> &Y) {
449 return !(X < Y);
450}
451
452raw_ostream &operator<<(raw_ostream &OS, NoneType);
453
454template <typename T, typename = decltype(std::declval<raw_ostream &>()
455 << std::declval<const T &>())>
456raw_ostream &operator<<(raw_ostream &OS, const Optional<T> &O) {
457 if (O)
458 OS << *O;
459 else
460 OS << None;
461 return OS;
462}
463
464} // end namespace llvm
465
466#endif // LLVM_ADT_OPTIONAL_H