Bug Summary

File:llvm/lib/Analysis/ScalarEvolution.cpp
Warning:line 10028, column 35
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 -fhalf-no-semantic-interposition -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-13/lib/clang/13.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/build-llvm/lib/Analysis -I /build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis -I /build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/build-llvm/include -I /build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/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-13/lib/clang/13.0.0/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-13~++20210223111116+16ede0956cb1/build-llvm/lib/Analysis -fdebug-prefix-map=/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1=. -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-2021-02-23-121308-24221-1 -x c++ /build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/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;
138using namespace PatternMatch;
139
140#define DEBUG_TYPE"scalar-evolution" "scalar-evolution"
141
142STATISTIC(NumArrayLenItCounts,static llvm::Statistic NumArrayLenItCounts = {"scalar-evolution"
, "NumArrayLenItCounts", "Number of trip counts computed with array length"
}
143 "Number of trip counts computed with array length")static llvm::Statistic NumArrayLenItCounts = {"scalar-evolution"
, "NumArrayLenItCounts", "Number of trip counts computed with array length"
}
;
144STATISTIC(NumTripCountsComputed,static llvm::Statistic NumTripCountsComputed = {"scalar-evolution"
, "NumTripCountsComputed", "Number of loops with predictable loop counts"
}
145 "Number of loops with predictable loop counts")static llvm::Statistic NumTripCountsComputed = {"scalar-evolution"
, "NumTripCountsComputed", "Number of loops with predictable loop counts"
}
;
146STATISTIC(NumTripCountsNotComputed,static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution"
, "NumTripCountsNotComputed", "Number of loops without predictable loop counts"
}
147 "Number of loops without predictable loop counts")static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution"
, "NumTripCountsNotComputed", "Number of loops without predictable loop counts"
}
;
148STATISTIC(NumBruteForceTripCountsComputed,static llvm::Statistic NumBruteForceTripCountsComputed = {"scalar-evolution"
, "NumBruteForceTripCountsComputed", "Number of loops with trip counts computed by force"
}
149 "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"
}
;
150
151static cl::opt<unsigned>
152MaxBruteForceIterations("scalar-evolution-max-iterations", cl::ReallyHidden,
153 cl::ZeroOrMore,
154 cl::desc("Maximum number of iterations SCEV will "
155 "symbolically execute a constant "
156 "derived loop"),
157 cl::init(100));
158
159// FIXME: Enable this with EXPENSIVE_CHECKS when the test suite is clean.
160static cl::opt<bool> VerifySCEV(
161 "verify-scev", cl::Hidden,
162 cl::desc("Verify ScalarEvolution's backedge taken counts (slow)"));
163static cl::opt<bool> VerifySCEVStrict(
164 "verify-scev-strict", cl::Hidden,
165 cl::desc("Enable stricter verification with -verify-scev is passed"));
166static cl::opt<bool>
167 VerifySCEVMap("verify-scev-maps", cl::Hidden,
168 cl::desc("Verify no dangling value in ScalarEvolution's "
169 "ExprValueMap (slow)"));
170
171static cl::opt<bool> VerifyIR(
172 "scev-verify-ir", cl::Hidden,
173 cl::desc("Verify IR correctness when making sensitive SCEV queries (slow)"),
174 cl::init(false));
175
176static cl::opt<unsigned> MulOpsInlineThreshold(
177 "scev-mulops-inline-threshold", cl::Hidden,
178 cl::desc("Threshold for inlining multiplication operands into a SCEV"),
179 cl::init(32));
180
181static cl::opt<unsigned> AddOpsInlineThreshold(
182 "scev-addops-inline-threshold", cl::Hidden,
183 cl::desc("Threshold for inlining addition operands into a SCEV"),
184 cl::init(500));
185
186static cl::opt<unsigned> MaxSCEVCompareDepth(
187 "scalar-evolution-max-scev-compare-depth", cl::Hidden,
188 cl::desc("Maximum depth of recursive SCEV complexity comparisons"),
189 cl::init(32));
190
191static cl::opt<unsigned> MaxSCEVOperationsImplicationDepth(
192 "scalar-evolution-max-scev-operations-implication-depth", cl::Hidden,
193 cl::desc("Maximum depth of recursive SCEV operations implication analysis"),
194 cl::init(2));
195
196static cl::opt<unsigned> MaxValueCompareDepth(
197 "scalar-evolution-max-value-compare-depth", cl::Hidden,
198 cl::desc("Maximum depth of recursive value complexity comparisons"),
199 cl::init(2));
200
201static cl::opt<unsigned>
202 MaxArithDepth("scalar-evolution-max-arith-depth", cl::Hidden,
203 cl::desc("Maximum depth of recursive arithmetics"),
204 cl::init(32));
205
206static cl::opt<unsigned> MaxConstantEvolvingDepth(
207 "scalar-evolution-max-constant-evolving-depth", cl::Hidden,
208 cl::desc("Maximum depth of recursive constant evolving"), cl::init(32));
209
210static cl::opt<unsigned>
211 MaxCastDepth("scalar-evolution-max-cast-depth", cl::Hidden,
212 cl::desc("Maximum depth of recursive SExt/ZExt/Trunc"),
213 cl::init(8));
214
215static cl::opt<unsigned>
216 MaxAddRecSize("scalar-evolution-max-add-rec-size", cl::Hidden,
217 cl::desc("Max coefficients in AddRec during evolving"),
218 cl::init(8));
219
220static cl::opt<unsigned>
221 HugeExprThreshold("scalar-evolution-huge-expr-threshold", cl::Hidden,
222 cl::desc("Size of the expression which is considered huge"),
223 cl::init(4096));
224
225static cl::opt<bool>
226ClassifyExpressions("scalar-evolution-classify-expressions",
227 cl::Hidden, cl::init(true),
228 cl::desc("When printing analysis, include information on every instruction"));
229
230static cl::opt<bool> UseExpensiveRangeSharpening(
231 "scalar-evolution-use-expensive-range-sharpening", cl::Hidden,
232 cl::init(false),
233 cl::desc("Use more powerful methods of sharpening expression ranges. May "
234 "be costly in terms of compile time"));
235
236//===----------------------------------------------------------------------===//
237// SCEV class definitions
238//===----------------------------------------------------------------------===//
239
240//===----------------------------------------------------------------------===//
241// Implementation of the SCEV class.
242//
243
244#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
245LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void SCEV::dump() const {
246 print(dbgs());
247 dbgs() << '\n';
248}
249#endif
250
251void SCEV::print(raw_ostream &OS) const {
252 switch (getSCEVType()) {
253 case scConstant:
254 cast<SCEVConstant>(this)->getValue()->printAsOperand(OS, false);
255 return;
256 case scPtrToInt: {
257 const SCEVPtrToIntExpr *PtrToInt = cast<SCEVPtrToIntExpr>(this);
258 const SCEV *Op = PtrToInt->getOperand();
259 OS << "(ptrtoint " << *Op->getType() << " " << *Op << " to "
260 << *PtrToInt->getType() << ")";
261 return;
262 }
263 case scTruncate: {
264 const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(this);
265 const SCEV *Op = Trunc->getOperand();
266 OS << "(trunc " << *Op->getType() << " " << *Op << " to "
267 << *Trunc->getType() << ")";
268 return;
269 }
270 case scZeroExtend: {
271 const SCEVZeroExtendExpr *ZExt = cast<SCEVZeroExtendExpr>(this);
272 const SCEV *Op = ZExt->getOperand();
273 OS << "(zext " << *Op->getType() << " " << *Op << " to "
274 << *ZExt->getType() << ")";
275 return;
276 }
277 case scSignExtend: {
278 const SCEVSignExtendExpr *SExt = cast<SCEVSignExtendExpr>(this);
279 const SCEV *Op = SExt->getOperand();
280 OS << "(sext " << *Op->getType() << " " << *Op << " to "
281 << *SExt->getType() << ")";
282 return;
283 }
284 case scAddRecExpr: {
285 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(this);
286 OS << "{" << *AR->getOperand(0);
287 for (unsigned i = 1, e = AR->getNumOperands(); i != e; ++i)
288 OS << ",+," << *AR->getOperand(i);
289 OS << "}<";
290 if (AR->hasNoUnsignedWrap())
291 OS << "nuw><";
292 if (AR->hasNoSignedWrap())
293 OS << "nsw><";
294 if (AR->hasNoSelfWrap() &&
295 !AR->getNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW)))
296 OS << "nw><";
297 AR->getLoop()->getHeader()->printAsOperand(OS, /*PrintType=*/false);
298 OS << ">";
299 return;
300 }
301 case scAddExpr:
302 case scMulExpr:
303 case scUMaxExpr:
304 case scSMaxExpr:
305 case scUMinExpr:
306 case scSMinExpr: {
307 const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(this);
308 const char *OpStr = nullptr;
309 switch (NAry->getSCEVType()) {
310 case scAddExpr: OpStr = " + "; break;
311 case scMulExpr: OpStr = " * "; break;
312 case scUMaxExpr: OpStr = " umax "; break;
313 case scSMaxExpr: OpStr = " smax "; break;
314 case scUMinExpr:
315 OpStr = " umin ";
316 break;
317 case scSMinExpr:
318 OpStr = " smin ";
319 break;
320 default:
321 llvm_unreachable("There are no other nary expression types.")::llvm::llvm_unreachable_internal("There are no other nary expression types."
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 321)
;
322 }
323 OS << "(";
324 ListSeparator LS(OpStr);
325 for (const SCEV *Op : NAry->operands())
326 OS << LS << *Op;
327 OS << ")";
328 switch (NAry->getSCEVType()) {
329 case scAddExpr:
330 case scMulExpr:
331 if (NAry->hasNoUnsignedWrap())
332 OS << "<nuw>";
333 if (NAry->hasNoSignedWrap())
334 OS << "<nsw>";
335 break;
336 default:
337 // Nothing to print for other nary expressions.
338 break;
339 }
340 return;
341 }
342 case scUDivExpr: {
343 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(this);
344 OS << "(" << *UDiv->getLHS() << " /u " << *UDiv->getRHS() << ")";
345 return;
346 }
347 case scUnknown: {
348 const SCEVUnknown *U = cast<SCEVUnknown>(this);
349 Type *AllocTy;
350 if (U->isSizeOf(AllocTy)) {
351 OS << "sizeof(" << *AllocTy << ")";
352 return;
353 }
354 if (U->isAlignOf(AllocTy)) {
355 OS << "alignof(" << *AllocTy << ")";
356 return;
357 }
358
359 Type *CTy;
360 Constant *FieldNo;
361 if (U->isOffsetOf(CTy, FieldNo)) {
362 OS << "offsetof(" << *CTy << ", ";
363 FieldNo->printAsOperand(OS, false);
364 OS << ")";
365 return;
366 }
367
368 // Otherwise just print it normally.
369 U->getValue()->printAsOperand(OS, false);
370 return;
371 }
372 case scCouldNotCompute:
373 OS << "***COULDNOTCOMPUTE***";
374 return;
375 }
376 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 376)
;
377}
378
379Type *SCEV::getType() const {
380 switch (getSCEVType()) {
381 case scConstant:
382 return cast<SCEVConstant>(this)->getType();
383 case scPtrToInt:
384 case scTruncate:
385 case scZeroExtend:
386 case scSignExtend:
387 return cast<SCEVCastExpr>(this)->getType();
388 case scAddRecExpr:
389 case scMulExpr:
390 case scUMaxExpr:
391 case scSMaxExpr:
392 case scUMinExpr:
393 case scSMinExpr:
394 return cast<SCEVNAryExpr>(this)->getType();
395 case scAddExpr:
396 return cast<SCEVAddExpr>(this)->getType();
397 case scUDivExpr:
398 return cast<SCEVUDivExpr>(this)->getType();
399 case scUnknown:
400 return cast<SCEVUnknown>(this)->getType();
401 case scCouldNotCompute:
402 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 402)
;
403 }
404 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 404)
;
405}
406
407bool SCEV::isZero() const {
408 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
409 return SC->getValue()->isZero();
410 return false;
411}
412
413bool SCEV::isOne() const {
414 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
415 return SC->getValue()->isOne();
416 return false;
417}
418
419bool SCEV::isAllOnesValue() const {
420 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
421 return SC->getValue()->isMinusOne();
422 return false;
423}
424
425bool SCEV::isNonConstantNegative() const {
426 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(this);
427 if (!Mul) return false;
428
429 // If there is a constant factor, it will be first.
430 const SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0));
431 if (!SC) return false;
432
433 // Return true if the value is negative, this matches things like (-42 * V).
434 return SC->getAPInt().isNegative();
435}
436
437SCEVCouldNotCompute::SCEVCouldNotCompute() :
438 SCEV(FoldingSetNodeIDRef(), scCouldNotCompute, 0) {}
439
440bool SCEVCouldNotCompute::classof(const SCEV *S) {
441 return S->getSCEVType() == scCouldNotCompute;
442}
443
444const SCEV *ScalarEvolution::getConstant(ConstantInt *V) {
445 FoldingSetNodeID ID;
446 ID.AddInteger(scConstant);
447 ID.AddPointer(V);
448 void *IP = nullptr;
449 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
450 SCEV *S = new (SCEVAllocator) SCEVConstant(ID.Intern(SCEVAllocator), V);
451 UniqueSCEVs.InsertNode(S, IP);
452 return S;
453}
454
455const SCEV *ScalarEvolution::getConstant(const APInt &Val) {
456 return getConstant(ConstantInt::get(getContext(), Val));
457}
458
459const SCEV *
460ScalarEvolution::getConstant(Type *Ty, uint64_t V, bool isSigned) {
461 IntegerType *ITy = cast<IntegerType>(getEffectiveSCEVType(Ty));
462 return getConstant(ConstantInt::get(ITy, V, isSigned));
463}
464
465SCEVCastExpr::SCEVCastExpr(const FoldingSetNodeIDRef ID, SCEVTypes SCEVTy,
466 const SCEV *op, Type *ty)
467 : SCEV(ID, SCEVTy, computeExpressionSize(op)), Ty(ty) {
468 Operands[0] = op;
469}
470
471SCEVPtrToIntExpr::SCEVPtrToIntExpr(const FoldingSetNodeIDRef ID, const SCEV *Op,
472 Type *ITy)
473 : SCEVCastExpr(ID, scPtrToInt, Op, ITy) {
474 assert(getOperand()->getType()->isPointerTy() && Ty->isIntegerTy() &&((getOperand()->getType()->isPointerTy() && Ty->
isIntegerTy() && "Must be a non-bit-width-changing pointer-to-integer cast!"
) ? static_cast<void> (0) : __assert_fail ("getOperand()->getType()->isPointerTy() && Ty->isIntegerTy() && \"Must be a non-bit-width-changing pointer-to-integer cast!\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 475, __PRETTY_FUNCTION__))
475 "Must be a non-bit-width-changing pointer-to-integer cast!")((getOperand()->getType()->isPointerTy() && Ty->
isIntegerTy() && "Must be a non-bit-width-changing pointer-to-integer cast!"
) ? static_cast<void> (0) : __assert_fail ("getOperand()->getType()->isPointerTy() && Ty->isIntegerTy() && \"Must be a non-bit-width-changing pointer-to-integer cast!\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 475, __PRETTY_FUNCTION__))
;
476}
477
478SCEVIntegralCastExpr::SCEVIntegralCastExpr(const FoldingSetNodeIDRef ID,
479 SCEVTypes SCEVTy, const SCEV *op,
480 Type *ty)
481 : SCEVCastExpr(ID, SCEVTy, op, ty) {}
482
483SCEVTruncateExpr::SCEVTruncateExpr(const FoldingSetNodeIDRef ID, const SCEV *op,
484 Type *ty)
485 : SCEVIntegralCastExpr(ID, scTruncate, op, ty) {
486 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 487, __PRETTY_FUNCTION__))
487 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 487, __PRETTY_FUNCTION__))
;
488}
489
490SCEVZeroExtendExpr::SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID,
491 const SCEV *op, Type *ty)
492 : SCEVIntegralCastExpr(ID, scZeroExtend, op, ty) {
493 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 494, __PRETTY_FUNCTION__))
494 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 494, __PRETTY_FUNCTION__))
;
495}
496
497SCEVSignExtendExpr::SCEVSignExtendExpr(const FoldingSetNodeIDRef ID,
498 const SCEV *op, Type *ty)
499 : SCEVIntegralCastExpr(ID, scSignExtend, op, ty) {
500 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 501, __PRETTY_FUNCTION__))
501 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 501, __PRETTY_FUNCTION__))
;
502}
503
504void SCEVUnknown::deleted() {
505 // Clear this SCEVUnknown from various maps.
506 SE->forgetMemoizedResults(this);
507
508 // Remove this SCEVUnknown from the uniquing map.
509 SE->UniqueSCEVs.RemoveNode(this);
510
511 // Release the value.
512 setValPtr(nullptr);
513}
514
515void SCEVUnknown::allUsesReplacedWith(Value *New) {
516 // Remove this SCEVUnknown from the uniquing map.
517 SE->UniqueSCEVs.RemoveNode(this);
518
519 // Update this SCEVUnknown to point to the new value. This is needed
520 // because there may still be outstanding SCEVs which still point to
521 // this SCEVUnknown.
522 setValPtr(New);
523}
524
525bool SCEVUnknown::isSizeOf(Type *&AllocTy) const {
526 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
527 if (VCE->getOpcode() == Instruction::PtrToInt)
528 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
529 if (CE->getOpcode() == Instruction::GetElementPtr &&
530 CE->getOperand(0)->isNullValue() &&
531 CE->getNumOperands() == 2)
532 if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(1)))
533 if (CI->isOne()) {
534 AllocTy = cast<PointerType>(CE->getOperand(0)->getType())
535 ->getElementType();
536 return true;
537 }
538
539 return false;
540}
541
542bool SCEVUnknown::isAlignOf(Type *&AllocTy) const {
543 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
544 if (VCE->getOpcode() == Instruction::PtrToInt)
545 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
546 if (CE->getOpcode() == Instruction::GetElementPtr &&
547 CE->getOperand(0)->isNullValue()) {
548 Type *Ty =
549 cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
550 if (StructType *STy = dyn_cast<StructType>(Ty))
551 if (!STy->isPacked() &&
552 CE->getNumOperands() == 3 &&
553 CE->getOperand(1)->isNullValue()) {
554 if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(2)))
555 if (CI->isOne() &&
556 STy->getNumElements() == 2 &&
557 STy->getElementType(0)->isIntegerTy(1)) {
558 AllocTy = STy->getElementType(1);
559 return true;
560 }
561 }
562 }
563
564 return false;
565}
566
567bool SCEVUnknown::isOffsetOf(Type *&CTy, Constant *&FieldNo) const {
568 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
569 if (VCE->getOpcode() == Instruction::PtrToInt)
570 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
571 if (CE->getOpcode() == Instruction::GetElementPtr &&
572 CE->getNumOperands() == 3 &&
573 CE->getOperand(0)->isNullValue() &&
574 CE->getOperand(1)->isNullValue()) {
575 Type *Ty =
576 cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
577 // Ignore vector types here so that ScalarEvolutionExpander doesn't
578 // emit getelementptrs that index into vectors.
579 if (Ty->isStructTy() || Ty->isArrayTy()) {
580 CTy = Ty;
581 FieldNo = CE->getOperand(2);
582 return true;
583 }
584 }
585
586 return false;
587}
588
589//===----------------------------------------------------------------------===//
590// SCEV Utilities
591//===----------------------------------------------------------------------===//
592
593/// Compare the two values \p LV and \p RV in terms of their "complexity" where
594/// "complexity" is a partial (and somewhat ad-hoc) relation used to order
595/// operands in SCEV expressions. \p EqCache is a set of pairs of values that
596/// have been previously deemed to be "equally complex" by this routine. It is
597/// intended to avoid exponential time complexity in cases like:
598///
599/// %a = f(%x, %y)
600/// %b = f(%a, %a)
601/// %c = f(%b, %b)
602///
603/// %d = f(%x, %y)
604/// %e = f(%d, %d)
605/// %f = f(%e, %e)
606///
607/// CompareValueComplexity(%f, %c)
608///
609/// Since we do not continue running this routine on expression trees once we
610/// have seen unequal values, there is no need to track them in the cache.
611static int
612CompareValueComplexity(EquivalenceClasses<const Value *> &EqCacheValue,
613 const LoopInfo *const LI, Value *LV, Value *RV,
614 unsigned Depth) {
615 if (Depth > MaxValueCompareDepth || EqCacheValue.isEquivalent(LV, RV))
616 return 0;
617
618 // Order pointer values after integer values. This helps SCEVExpander form
619 // GEPs.
620 bool LIsPointer = LV->getType()->isPointerTy(),
621 RIsPointer = RV->getType()->isPointerTy();
622 if (LIsPointer != RIsPointer)
623 return (int)LIsPointer - (int)RIsPointer;
624
625 // Compare getValueID values.
626 unsigned LID = LV->getValueID(), RID = RV->getValueID();
627 if (LID != RID)
628 return (int)LID - (int)RID;
629
630 // Sort arguments by their position.
631 if (const auto *LA = dyn_cast<Argument>(LV)) {
632 const auto *RA = cast<Argument>(RV);
633 unsigned LArgNo = LA->getArgNo(), RArgNo = RA->getArgNo();
634 return (int)LArgNo - (int)RArgNo;
635 }
636
637 if (const auto *LGV = dyn_cast<GlobalValue>(LV)) {
638 const auto *RGV = cast<GlobalValue>(RV);
639
640 const auto IsGVNameSemantic = [&](const GlobalValue *GV) {
641 auto LT = GV->getLinkage();
642 return !(GlobalValue::isPrivateLinkage(LT) ||
643 GlobalValue::isInternalLinkage(LT));
644 };
645
646 // Use the names to distinguish the two values, but only if the
647 // names are semantically important.
648 if (IsGVNameSemantic(LGV) && IsGVNameSemantic(RGV))
649 return LGV->getName().compare(RGV->getName());
650 }
651
652 // For instructions, compare their loop depth, and their operand count. This
653 // is pretty loose.
654 if (const auto *LInst = dyn_cast<Instruction>(LV)) {
655 const auto *RInst = cast<Instruction>(RV);
656
657 // Compare loop depths.
658 const BasicBlock *LParent = LInst->getParent(),
659 *RParent = RInst->getParent();
660 if (LParent != RParent) {
661 unsigned LDepth = LI->getLoopDepth(LParent),
662 RDepth = LI->getLoopDepth(RParent);
663 if (LDepth != RDepth)
664 return (int)LDepth - (int)RDepth;
665 }
666
667 // Compare the number of operands.
668 unsigned LNumOps = LInst->getNumOperands(),
669 RNumOps = RInst->getNumOperands();
670 if (LNumOps != RNumOps)
671 return (int)LNumOps - (int)RNumOps;
672
673 for (unsigned Idx : seq(0u, LNumOps)) {
674 int Result =
675 CompareValueComplexity(EqCacheValue, LI, LInst->getOperand(Idx),
676 RInst->getOperand(Idx), Depth + 1);
677 if (Result != 0)
678 return Result;
679 }
680 }
681
682 EqCacheValue.unionSets(LV, RV);
683 return 0;
684}
685
686// Return negative, zero, or positive, if LHS is less than, equal to, or greater
687// than RHS, respectively. A three-way result allows recursive comparisons to be
688// more efficient.
689// If the max analysis depth was reached, return None, assuming we do not know
690// if they are equivalent for sure.
691static Optional<int>
692CompareSCEVComplexity(EquivalenceClasses<const SCEV *> &EqCacheSCEV,
693 EquivalenceClasses<const Value *> &EqCacheValue,
694 const LoopInfo *const LI, const SCEV *LHS,
695 const SCEV *RHS, DominatorTree &DT, unsigned Depth = 0) {
696 // Fast-path: SCEVs are uniqued so we can do a quick equality check.
697 if (LHS == RHS)
698 return 0;
699
700 // Primarily, sort the SCEVs by their getSCEVType().
701 SCEVTypes LType = LHS->getSCEVType(), RType = RHS->getSCEVType();
702 if (LType != RType)
703 return (int)LType - (int)RType;
704
705 if (EqCacheSCEV.isEquivalent(LHS, RHS))
706 return 0;
707
708 if (Depth > MaxSCEVCompareDepth)
709 return None;
710
711 // Aside from the getSCEVType() ordering, the particular ordering
712 // isn't very important except that it's beneficial to be consistent,
713 // so that (a + b) and (b + a) don't end up as different expressions.
714 switch (LType) {
715 case scUnknown: {
716 const SCEVUnknown *LU = cast<SCEVUnknown>(LHS);
717 const SCEVUnknown *RU = cast<SCEVUnknown>(RHS);
718
719 int X = CompareValueComplexity(EqCacheValue, LI, LU->getValue(),
720 RU->getValue(), Depth + 1);
721 if (X == 0)
722 EqCacheSCEV.unionSets(LHS, RHS);
723 return X;
724 }
725
726 case scConstant: {
727 const SCEVConstant *LC = cast<SCEVConstant>(LHS);
728 const SCEVConstant *RC = cast<SCEVConstant>(RHS);
729
730 // Compare constant values.
731 const APInt &LA = LC->getAPInt();
732 const APInt &RA = RC->getAPInt();
733 unsigned LBitWidth = LA.getBitWidth(), RBitWidth = RA.getBitWidth();
734 if (LBitWidth != RBitWidth)
735 return (int)LBitWidth - (int)RBitWidth;
736 return LA.ult(RA) ? -1 : 1;
737 }
738
739 case scAddRecExpr: {
740 const SCEVAddRecExpr *LA = cast<SCEVAddRecExpr>(LHS);
741 const SCEVAddRecExpr *RA = cast<SCEVAddRecExpr>(RHS);
742
743 // There is always a dominance between two recs that are used by one SCEV,
744 // so we can safely sort recs by loop header dominance. We require such
745 // order in getAddExpr.
746 const Loop *LLoop = LA->getLoop(), *RLoop = RA->getLoop();
747 if (LLoop != RLoop) {
748 const BasicBlock *LHead = LLoop->getHeader(), *RHead = RLoop->getHeader();
749 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 749, __PRETTY_FUNCTION__))
;
750 if (DT.dominates(LHead, RHead))
751 return 1;
752 else
753 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 754, __PRETTY_FUNCTION__))
754 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 754, __PRETTY_FUNCTION__))
;
755 return -1;
756 }
757
758 // Addrec complexity grows with operand count.
759 unsigned LNumOps = LA->getNumOperands(), RNumOps = RA->getNumOperands();
760 if (LNumOps != RNumOps)
761 return (int)LNumOps - (int)RNumOps;
762
763 // Lexicographically compare.
764 for (unsigned i = 0; i != LNumOps; ++i) {
765 auto X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
766 LA->getOperand(i), RA->getOperand(i), DT,
767 Depth + 1);
768 if (X != 0)
769 return X;
770 }
771 EqCacheSCEV.unionSets(LHS, RHS);
772 return 0;
773 }
774
775 case scAddExpr:
776 case scMulExpr:
777 case scSMaxExpr:
778 case scUMaxExpr:
779 case scSMinExpr:
780 case scUMinExpr: {
781 const SCEVNAryExpr *LC = cast<SCEVNAryExpr>(LHS);
782 const SCEVNAryExpr *RC = cast<SCEVNAryExpr>(RHS);
783
784 // Lexicographically compare n-ary expressions.
785 unsigned LNumOps = LC->getNumOperands(), RNumOps = RC->getNumOperands();
786 if (LNumOps != RNumOps)
787 return (int)LNumOps - (int)RNumOps;
788
789 for (unsigned i = 0; i != LNumOps; ++i) {
790 auto X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
791 LC->getOperand(i), RC->getOperand(i), DT,
792 Depth + 1);
793 if (X != 0)
794 return X;
795 }
796 EqCacheSCEV.unionSets(LHS, RHS);
797 return 0;
798 }
799
800 case scUDivExpr: {
801 const SCEVUDivExpr *LC = cast<SCEVUDivExpr>(LHS);
802 const SCEVUDivExpr *RC = cast<SCEVUDivExpr>(RHS);
803
804 // Lexicographically compare udiv expressions.
805 auto X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getLHS(),
806 RC->getLHS(), DT, Depth + 1);
807 if (X != 0)
808 return X;
809 X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getRHS(),
810 RC->getRHS(), DT, Depth + 1);
811 if (X == 0)
812 EqCacheSCEV.unionSets(LHS, RHS);
813 return X;
814 }
815
816 case scPtrToInt:
817 case scTruncate:
818 case scZeroExtend:
819 case scSignExtend: {
820 const SCEVCastExpr *LC = cast<SCEVCastExpr>(LHS);
821 const SCEVCastExpr *RC = cast<SCEVCastExpr>(RHS);
822
823 // Compare cast expressions by operand.
824 auto X =
825 CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getOperand(),
826 RC->getOperand(), DT, Depth + 1);
827 if (X == 0)
828 EqCacheSCEV.unionSets(LHS, RHS);
829 return X;
830 }
831
832 case scCouldNotCompute:
833 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 833)
;
834 }
835 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 835)
;
836}
837
838/// Given a list of SCEV objects, order them by their complexity, and group
839/// objects of the same complexity together by value. When this routine is
840/// finished, we know that any duplicates in the vector are consecutive and that
841/// complexity is monotonically increasing.
842///
843/// Note that we go take special precautions to ensure that we get deterministic
844/// results from this routine. In other words, we don't want the results of
845/// this to depend on where the addresses of various SCEV objects happened to
846/// land in memory.
847static void GroupByComplexity(SmallVectorImpl<const SCEV *> &Ops,
848 LoopInfo *LI, DominatorTree &DT) {
849 if (Ops.size() < 2) return; // Noop
850
851 EquivalenceClasses<const SCEV *> EqCacheSCEV;
852 EquivalenceClasses<const Value *> EqCacheValue;
853
854 // Whether LHS has provably less complexity than RHS.
855 auto IsLessComplex = [&](const SCEV *LHS, const SCEV *RHS) {
856 auto Complexity =
857 CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LHS, RHS, DT);
858 return Complexity && *Complexity < 0;
859 };
860 if (Ops.size() == 2) {
861 // This is the common case, which also happens to be trivially simple.
862 // Special case it.
863 const SCEV *&LHS = Ops[0], *&RHS = Ops[1];
864 if (IsLessComplex(RHS, LHS))
865 std::swap(LHS, RHS);
866 return;
867 }
868
869 // Do the rough sort by complexity.
870 llvm::stable_sort(Ops, [&](const SCEV *LHS, const SCEV *RHS) {
871 return IsLessComplex(LHS, RHS);
872 });
873
874 // Now that we are sorted by complexity, group elements of the same
875 // complexity. Note that this is, at worst, N^2, but the vector is likely to
876 // be extremely short in practice. Note that we take this approach because we
877 // do not want to depend on the addresses of the objects we are grouping.
878 for (unsigned i = 0, e = Ops.size(); i != e-2; ++i) {
879 const SCEV *S = Ops[i];
880 unsigned Complexity = S->getSCEVType();
881
882 // If there are any objects of the same complexity and same value as this
883 // one, group them.
884 for (unsigned j = i+1; j != e && Ops[j]->getSCEVType() == Complexity; ++j) {
885 if (Ops[j] == S) { // Found a duplicate.
886 // Move it to immediately after i'th element.
887 std::swap(Ops[i+1], Ops[j]);
888 ++i; // no need to rescan it.
889 if (i == e-2) return; // Done!
890 }
891 }
892 }
893}
894
895/// Returns true if \p Ops contains a huge SCEV (the subtree of S contains at
896/// least HugeExprThreshold nodes).
897static bool hasHugeExpression(ArrayRef<const SCEV *> Ops) {
898 return any_of(Ops, [](const SCEV *S) {
899 return S->getExpressionSize() >= HugeExprThreshold;
900 });
901}
902
903//===----------------------------------------------------------------------===//
904// Simple SCEV method implementations
905//===----------------------------------------------------------------------===//
906
907/// Compute BC(It, K). The result has width W. Assume, K > 0.
908static const SCEV *BinomialCoefficient(const SCEV *It, unsigned K,
909 ScalarEvolution &SE,
910 Type *ResultTy) {
911 // Handle the simplest case efficiently.
912 if (K == 1)
913 return SE.getTruncateOrZeroExtend(It, ResultTy);
914
915 // We are using the following formula for BC(It, K):
916 //
917 // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / K!
918 //
919 // Suppose, W is the bitwidth of the return value. We must be prepared for
920 // overflow. Hence, we must assure that the result of our computation is
921 // equal to the accurate one modulo 2^W. Unfortunately, division isn't
922 // safe in modular arithmetic.
923 //
924 // However, this code doesn't use exactly that formula; the formula it uses
925 // is something like the following, where T is the number of factors of 2 in
926 // K! (i.e. trailing zeros in the binary representation of K!), and ^ is
927 // exponentiation:
928 //
929 // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / 2^T / (K! / 2^T)
930 //
931 // This formula is trivially equivalent to the previous formula. However,
932 // this formula can be implemented much more efficiently. The trick is that
933 // K! / 2^T is odd, and exact division by an odd number *is* safe in modular
934 // arithmetic. To do exact division in modular arithmetic, all we have
935 // to do is multiply by the inverse. Therefore, this step can be done at
936 // width W.
937 //
938 // The next issue is how to safely do the division by 2^T. The way this
939 // is done is by doing the multiplication step at a width of at least W + T
940 // bits. This way, the bottom W+T bits of the product are accurate. Then,
941 // when we perform the division by 2^T (which is equivalent to a right shift
942 // by T), the bottom W bits are accurate. Extra bits are okay; they'll get
943 // truncated out after the division by 2^T.
944 //
945 // In comparison to just directly using the first formula, this technique
946 // is much more efficient; using the first formula requires W * K bits,
947 // but this formula less than W + K bits. Also, the first formula requires
948 // a division step, whereas this formula only requires multiplies and shifts.
949 //
950 // It doesn't matter whether the subtraction step is done in the calculation
951 // width or the input iteration count's width; if the subtraction overflows,
952 // the result must be zero anyway. We prefer here to do it in the width of
953 // the induction variable because it helps a lot for certain cases; CodeGen
954 // isn't smart enough to ignore the overflow, which leads to much less
955 // efficient code if the width of the subtraction is wider than the native
956 // register width.
957 //
958 // (It's possible to not widen at all by pulling out factors of 2 before
959 // the multiplication; for example, K=2 can be calculated as
960 // It/2*(It+(It*INT_MIN/INT_MIN)+-1). However, it requires
961 // extra arithmetic, so it's not an obvious win, and it gets
962 // much more complicated for K > 3.)
963
964 // Protection from insane SCEVs; this bound is conservative,
965 // but it probably doesn't matter.
966 if (K > 1000)
967 return SE.getCouldNotCompute();
968
969 unsigned W = SE.getTypeSizeInBits(ResultTy);
970
971 // Calculate K! / 2^T and T; we divide out the factors of two before
972 // multiplying for calculating K! / 2^T to avoid overflow.
973 // Other overflow doesn't matter because we only care about the bottom
974 // W bits of the result.
975 APInt OddFactorial(W, 1);
976 unsigned T = 1;
977 for (unsigned i = 3; i <= K; ++i) {
978 APInt Mult(W, i);
979 unsigned TwoFactors = Mult.countTrailingZeros();
980 T += TwoFactors;
981 Mult.lshrInPlace(TwoFactors);
982 OddFactorial *= Mult;
983 }
984
985 // We need at least W + T bits for the multiplication step
986 unsigned CalculationBits = W + T;
987
988 // Calculate 2^T, at width T+W.
989 APInt DivFactor = APInt::getOneBitSet(CalculationBits, T);
990
991 // Calculate the multiplicative inverse of K! / 2^T;
992 // this multiplication factor will perform the exact division by
993 // K! / 2^T.
994 APInt Mod = APInt::getSignedMinValue(W+1);
995 APInt MultiplyFactor = OddFactorial.zext(W+1);
996 MultiplyFactor = MultiplyFactor.multiplicativeInverse(Mod);
997 MultiplyFactor = MultiplyFactor.trunc(W);
998
999 // Calculate the product, at width T+W
1000 IntegerType *CalculationTy = IntegerType::get(SE.getContext(),
1001 CalculationBits);
1002 const SCEV *Dividend = SE.getTruncateOrZeroExtend(It, CalculationTy);
1003 for (unsigned i = 1; i != K; ++i) {
1004 const SCEV *S = SE.getMinusSCEV(It, SE.getConstant(It->getType(), i));
1005 Dividend = SE.getMulExpr(Dividend,
1006 SE.getTruncateOrZeroExtend(S, CalculationTy));
1007 }
1008
1009 // Divide by 2^T
1010 const SCEV *DivResult = SE.getUDivExpr(Dividend, SE.getConstant(DivFactor));
1011
1012 // Truncate the result, and divide by K! / 2^T.
1013
1014 return SE.getMulExpr(SE.getConstant(MultiplyFactor),
1015 SE.getTruncateOrZeroExtend(DivResult, ResultTy));
1016}
1017
1018/// Return the value of this chain of recurrences at the specified iteration
1019/// number. We can evaluate this recurrence by multiplying each element in the
1020/// chain by the binomial coefficient corresponding to it. In other words, we
1021/// can evaluate {A,+,B,+,C,+,D} as:
1022///
1023/// A*BC(It, 0) + B*BC(It, 1) + C*BC(It, 2) + D*BC(It, 3)
1024///
1025/// where BC(It, k) stands for binomial coefficient.
1026const SCEV *SCEVAddRecExpr::evaluateAtIteration(const SCEV *It,
1027 ScalarEvolution &SE) const {
1028 const SCEV *Result = getStart();
1029 for (unsigned i = 1, e = getNumOperands(); i != e; ++i) {
1030 // The computation is correct in the face of overflow provided that the
1031 // multiplication is performed _after_ the evaluation of the binomial
1032 // coefficient.
1033 const SCEV *Coeff = BinomialCoefficient(It, i, SE, getType());
1034 if (isa<SCEVCouldNotCompute>(Coeff))
1035 return Coeff;
1036
1037 Result = SE.getAddExpr(Result, SE.getMulExpr(getOperand(i), Coeff));
1038 }
1039 return Result;
1040}
1041
1042//===----------------------------------------------------------------------===//
1043// SCEV Expression folder implementations
1044//===----------------------------------------------------------------------===//
1045
1046const SCEV *ScalarEvolution::getPtrToIntExpr(const SCEV *Op, Type *Ty,
1047 unsigned Depth) {
1048 assert(Ty->isIntegerTy() && "Target type must be an integer type!")((Ty->isIntegerTy() && "Target type must be an integer type!"
) ? static_cast<void> (0) : __assert_fail ("Ty->isIntegerTy() && \"Target type must be an integer type!\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1048, __PRETTY_FUNCTION__))
;
1049 assert(Depth <= 1 && "getPtrToIntExpr() should self-recurse at most once.")((Depth <= 1 && "getPtrToIntExpr() should self-recurse at most once."
) ? static_cast<void> (0) : __assert_fail ("Depth <= 1 && \"getPtrToIntExpr() should self-recurse at most once.\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1049, __PRETTY_FUNCTION__))
;
1050
1051 // We could be called with an integer-typed operands during SCEV rewrites.
1052 // Since the operand is an integer already, just perform zext/trunc/self cast.
1053 if (!Op->getType()->isPointerTy())
1054 return getTruncateOrZeroExtend(Op, Ty);
1055
1056 // What would be an ID for such a SCEV cast expression?
1057 FoldingSetNodeID ID;
1058 ID.AddInteger(scPtrToInt);
1059 ID.AddPointer(Op);
1060
1061 void *IP = nullptr;
1062
1063 // Is there already an expression for such a cast?
1064 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
1065 return getTruncateOrZeroExtend(S, Ty);
1066
1067 // If not, is this expression something we can't reduce any further?
1068 if (isa<SCEVUnknown>(Op)) {
1069 // Create an explicit cast node.
1070 // We can reuse the existing insert position since if we get here,
1071 // we won't have made any changes which would invalidate it.
1072 Type *IntPtrTy = getDataLayout().getIntPtrType(Op->getType());
1073 assert(getDataLayout().getTypeSizeInBits(getEffectiveSCEVType(((getDataLayout().getTypeSizeInBits(getEffectiveSCEVType( Op->
getType())) == getDataLayout().getTypeSizeInBits(IntPtrTy) &&
"We can only model ptrtoint if SCEV's effective (integer) type is "
"sufficiently wide to represent all possible pointer values."
) ? static_cast<void> (0) : __assert_fail ("getDataLayout().getTypeSizeInBits(getEffectiveSCEVType( Op->getType())) == getDataLayout().getTypeSizeInBits(IntPtrTy) && \"We can only model ptrtoint if SCEV's effective (integer) type is \" \"sufficiently wide to represent all possible pointer values.\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1076, __PRETTY_FUNCTION__))
1074 Op->getType())) == getDataLayout().getTypeSizeInBits(IntPtrTy) &&((getDataLayout().getTypeSizeInBits(getEffectiveSCEVType( Op->
getType())) == getDataLayout().getTypeSizeInBits(IntPtrTy) &&
"We can only model ptrtoint if SCEV's effective (integer) type is "
"sufficiently wide to represent all possible pointer values."
) ? static_cast<void> (0) : __assert_fail ("getDataLayout().getTypeSizeInBits(getEffectiveSCEVType( Op->getType())) == getDataLayout().getTypeSizeInBits(IntPtrTy) && \"We can only model ptrtoint if SCEV's effective (integer) type is \" \"sufficiently wide to represent all possible pointer values.\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1076, __PRETTY_FUNCTION__))
1075 "We can only model ptrtoint if SCEV's effective (integer) type is "((getDataLayout().getTypeSizeInBits(getEffectiveSCEVType( Op->
getType())) == getDataLayout().getTypeSizeInBits(IntPtrTy) &&
"We can only model ptrtoint if SCEV's effective (integer) type is "
"sufficiently wide to represent all possible pointer values."
) ? static_cast<void> (0) : __assert_fail ("getDataLayout().getTypeSizeInBits(getEffectiveSCEVType( Op->getType())) == getDataLayout().getTypeSizeInBits(IntPtrTy) && \"We can only model ptrtoint if SCEV's effective (integer) type is \" \"sufficiently wide to represent all possible pointer values.\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1076, __PRETTY_FUNCTION__))
1076 "sufficiently wide to represent all possible pointer values.")((getDataLayout().getTypeSizeInBits(getEffectiveSCEVType( Op->
getType())) == getDataLayout().getTypeSizeInBits(IntPtrTy) &&
"We can only model ptrtoint if SCEV's effective (integer) type is "
"sufficiently wide to represent all possible pointer values."
) ? static_cast<void> (0) : __assert_fail ("getDataLayout().getTypeSizeInBits(getEffectiveSCEVType( Op->getType())) == getDataLayout().getTypeSizeInBits(IntPtrTy) && \"We can only model ptrtoint if SCEV's effective (integer) type is \" \"sufficiently wide to represent all possible pointer values.\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1076, __PRETTY_FUNCTION__))
;
1077 SCEV *S = new (SCEVAllocator)
1078 SCEVPtrToIntExpr(ID.Intern(SCEVAllocator), Op, IntPtrTy);
1079 UniqueSCEVs.InsertNode(S, IP);
1080 addToLoopUseLists(S);
1081 return getTruncateOrZeroExtend(S, Ty);
1082 }
1083
1084 assert(Depth == 0 &&((Depth == 0 && "getPtrToIntExpr() should not self-recurse for non-SCEVUnknown's."
) ? static_cast<void> (0) : __assert_fail ("Depth == 0 && \"getPtrToIntExpr() should not self-recurse for non-SCEVUnknown's.\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1085, __PRETTY_FUNCTION__))
1085 "getPtrToIntExpr() should not self-recurse for non-SCEVUnknown's.")((Depth == 0 && "getPtrToIntExpr() should not self-recurse for non-SCEVUnknown's."
) ? static_cast<void> (0) : __assert_fail ("Depth == 0 && \"getPtrToIntExpr() should not self-recurse for non-SCEVUnknown's.\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1085, __PRETTY_FUNCTION__))
;
1086
1087 // Otherwise, we've got some expression that is more complex than just a
1088 // single SCEVUnknown. But we don't want to have a SCEVPtrToIntExpr of an
1089 // arbitrary expression, we want to have SCEVPtrToIntExpr of an SCEVUnknown
1090 // only, and the expressions must otherwise be integer-typed.
1091 // So sink the cast down to the SCEVUnknown's.
1092
1093 /// The SCEVPtrToIntSinkingRewriter takes a scalar evolution expression,
1094 /// which computes a pointer-typed value, and rewrites the whole expression
1095 /// tree so that *all* the computations are done on integers, and the only
1096 /// pointer-typed operands in the expression are SCEVUnknown.
1097 class SCEVPtrToIntSinkingRewriter
1098 : public SCEVRewriteVisitor<SCEVPtrToIntSinkingRewriter> {
1099 using Base = SCEVRewriteVisitor<SCEVPtrToIntSinkingRewriter>;
1100
1101 public:
1102 SCEVPtrToIntSinkingRewriter(ScalarEvolution &SE) : SCEVRewriteVisitor(SE) {}
1103
1104 static const SCEV *rewrite(const SCEV *Scev, ScalarEvolution &SE) {
1105 SCEVPtrToIntSinkingRewriter Rewriter(SE);
1106 return Rewriter.visit(Scev);
1107 }
1108
1109 const SCEV *visit(const SCEV *S) {
1110 Type *STy = S->getType();
1111 // If the expression is not pointer-typed, just keep it as-is.
1112 if (!STy->isPointerTy())
1113 return S;
1114 // Else, recursively sink the cast down into it.
1115 return Base::visit(S);
1116 }
1117
1118 const SCEV *visitAddExpr(const SCEVAddExpr *Expr) {
1119 SmallVector<const SCEV *, 2> Operands;
1120 bool Changed = false;
1121 for (auto *Op : Expr->operands()) {
1122 Operands.push_back(visit(Op));
1123 Changed |= Op != Operands.back();
1124 }
1125 return !Changed ? Expr : SE.getAddExpr(Operands, Expr->getNoWrapFlags());
1126 }
1127
1128 const SCEV *visitMulExpr(const SCEVMulExpr *Expr) {
1129 SmallVector<const SCEV *, 2> Operands;
1130 bool Changed = false;
1131 for (auto *Op : Expr->operands()) {
1132 Operands.push_back(visit(Op));
1133 Changed |= Op != Operands.back();
1134 }
1135 return !Changed ? Expr : SE.getMulExpr(Operands, Expr->getNoWrapFlags());
1136 }
1137
1138 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
1139 Type *ExprPtrTy = Expr->getType();
1140 assert(ExprPtrTy->isPointerTy() &&((ExprPtrTy->isPointerTy() && "Should only reach pointer-typed SCEVUnknown's."
) ? static_cast<void> (0) : __assert_fail ("ExprPtrTy->isPointerTy() && \"Should only reach pointer-typed SCEVUnknown's.\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1141, __PRETTY_FUNCTION__))
1141 "Should only reach pointer-typed SCEVUnknown's.")((ExprPtrTy->isPointerTy() && "Should only reach pointer-typed SCEVUnknown's."
) ? static_cast<void> (0) : __assert_fail ("ExprPtrTy->isPointerTy() && \"Should only reach pointer-typed SCEVUnknown's.\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1141, __PRETTY_FUNCTION__))
;
1142 Type *ExprIntPtrTy = SE.getDataLayout().getIntPtrType(ExprPtrTy);
1143 return SE.getPtrToIntExpr(Expr, ExprIntPtrTy, /*Depth=*/1);
1144 }
1145 };
1146
1147 // And actually perform the cast sinking.
1148 const SCEV *IntOp = SCEVPtrToIntSinkingRewriter::rewrite(Op, *this);
1149 assert(IntOp->getType()->isIntegerTy() &&((IntOp->getType()->isIntegerTy() && "We must have succeeded in sinking the cast, "
"and ending up with an integer-typed expression!") ? static_cast
<void> (0) : __assert_fail ("IntOp->getType()->isIntegerTy() && \"We must have succeeded in sinking the cast, \" \"and ending up with an integer-typed expression!\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1151, __PRETTY_FUNCTION__))
1150 "We must have succeeded in sinking the cast, "((IntOp->getType()->isIntegerTy() && "We must have succeeded in sinking the cast, "
"and ending up with an integer-typed expression!") ? static_cast
<void> (0) : __assert_fail ("IntOp->getType()->isIntegerTy() && \"We must have succeeded in sinking the cast, \" \"and ending up with an integer-typed expression!\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1151, __PRETTY_FUNCTION__))
1151 "and ending up with an integer-typed expression!")((IntOp->getType()->isIntegerTy() && "We must have succeeded in sinking the cast, "
"and ending up with an integer-typed expression!") ? static_cast
<void> (0) : __assert_fail ("IntOp->getType()->isIntegerTy() && \"We must have succeeded in sinking the cast, \" \"and ending up with an integer-typed expression!\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1151, __PRETTY_FUNCTION__))
;
1152 return getTruncateOrZeroExtend(IntOp, Ty);
1153}
1154
1155const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op, Type *Ty,
1156 unsigned Depth) {
1157 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1158, __PRETTY_FUNCTION__))
1158 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1158, __PRETTY_FUNCTION__))
;
1159 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1160, __PRETTY_FUNCTION__))
1160 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1160, __PRETTY_FUNCTION__))
;
1161 Ty = getEffectiveSCEVType(Ty);
1162
1163 FoldingSetNodeID ID;
1164 ID.AddInteger(scTruncate);
1165 ID.AddPointer(Op);
1166 ID.AddPointer(Ty);
1167 void *IP = nullptr;
1168 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1169
1170 // Fold if the operand is constant.
1171 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1172 return getConstant(
1173 cast<ConstantInt>(ConstantExpr::getTrunc(SC->getValue(), Ty)));
1174
1175 // trunc(trunc(x)) --> trunc(x)
1176 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op))
1177 return getTruncateExpr(ST->getOperand(), Ty, Depth + 1);
1178
1179 // trunc(sext(x)) --> sext(x) if widening or trunc(x) if narrowing
1180 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1181 return getTruncateOrSignExtend(SS->getOperand(), Ty, Depth + 1);
1182
1183 // trunc(zext(x)) --> zext(x) if widening or trunc(x) if narrowing
1184 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1185 return getTruncateOrZeroExtend(SZ->getOperand(), Ty, Depth + 1);
1186
1187 if (Depth > MaxCastDepth) {
1188 SCEV *S =
1189 new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator), Op, Ty);
1190 UniqueSCEVs.InsertNode(S, IP);
1191 addToLoopUseLists(S);
1192 return S;
1193 }
1194
1195 // trunc(x1 + ... + xN) --> trunc(x1) + ... + trunc(xN) and
1196 // trunc(x1 * ... * xN) --> trunc(x1) * ... * trunc(xN),
1197 // if after transforming we have at most one truncate, not counting truncates
1198 // that replace other casts.
1199 if (isa<SCEVAddExpr>(Op) || isa<SCEVMulExpr>(Op)) {
1200 auto *CommOp = cast<SCEVCommutativeExpr>(Op);
1201 SmallVector<const SCEV *, 4> Operands;
1202 unsigned numTruncs = 0;
1203 for (unsigned i = 0, e = CommOp->getNumOperands(); i != e && numTruncs < 2;
1204 ++i) {
1205 const SCEV *S = getTruncateExpr(CommOp->getOperand(i), Ty, Depth + 1);
1206 if (!isa<SCEVIntegralCastExpr>(CommOp->getOperand(i)) &&
1207 isa<SCEVTruncateExpr>(S))
1208 numTruncs++;
1209 Operands.push_back(S);
1210 }
1211 if (numTruncs < 2) {
1212 if (isa<SCEVAddExpr>(Op))
1213 return getAddExpr(Operands);
1214 else if (isa<SCEVMulExpr>(Op))
1215 return getMulExpr(Operands);
1216 else
1217 llvm_unreachable("Unexpected SCEV type for Op.")::llvm::llvm_unreachable_internal("Unexpected SCEV type for Op."
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1217)
;
1218 }
1219 // Although we checked in the beginning that ID is not in the cache, it is
1220 // possible that during recursion and different modification ID was inserted
1221 // into the cache. So if we find it, just return it.
1222 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
1223 return S;
1224 }
1225
1226 // If the input value is a chrec scev, truncate the chrec's operands.
1227 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
1228 SmallVector<const SCEV *, 4> Operands;
1229 for (const SCEV *Op : AddRec->operands())
1230 Operands.push_back(getTruncateExpr(Op, Ty, Depth + 1));
1231 return getAddRecExpr(Operands, AddRec->getLoop(), SCEV::FlagAnyWrap);
1232 }
1233
1234 // Return zero if truncating to known zeros.
1235 uint32_t MinTrailingZeros = GetMinTrailingZeros(Op);
1236 if (MinTrailingZeros >= getTypeSizeInBits(Ty))
1237 return getZero(Ty);
1238
1239 // The cast wasn't folded; create an explicit cast node. We can reuse
1240 // the existing insert position since if we get here, we won't have
1241 // made any changes which would invalidate it.
1242 SCEV *S = new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator),
1243 Op, Ty);
1244 UniqueSCEVs.InsertNode(S, IP);
1245 addToLoopUseLists(S);
1246 return S;
1247}
1248
1249// Get the limit of a recurrence such that incrementing by Step cannot cause
1250// signed overflow as long as the value of the recurrence within the
1251// loop does not exceed this limit before incrementing.
1252static const SCEV *getSignedOverflowLimitForStep(const SCEV *Step,
1253 ICmpInst::Predicate *Pred,
1254 ScalarEvolution *SE) {
1255 unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
1256 if (SE->isKnownPositive(Step)) {
1257 *Pred = ICmpInst::ICMP_SLT;
1258 return SE->getConstant(APInt::getSignedMinValue(BitWidth) -
1259 SE->getSignedRangeMax(Step));
1260 }
1261 if (SE->isKnownNegative(Step)) {
1262 *Pred = ICmpInst::ICMP_SGT;
1263 return SE->getConstant(APInt::getSignedMaxValue(BitWidth) -
1264 SE->getSignedRangeMin(Step));
1265 }
1266 return nullptr;
1267}
1268
1269// Get the limit of a recurrence such that incrementing by Step cannot cause
1270// unsigned overflow as long as the value of the recurrence within the loop does
1271// not exceed this limit before incrementing.
1272static const SCEV *getUnsignedOverflowLimitForStep(const SCEV *Step,
1273 ICmpInst::Predicate *Pred,
1274 ScalarEvolution *SE) {
1275 unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
1276 *Pred = ICmpInst::ICMP_ULT;
1277
1278 return SE->getConstant(APInt::getMinValue(BitWidth) -
1279 SE->getUnsignedRangeMax(Step));
1280}
1281
1282namespace {
1283
1284struct ExtendOpTraitsBase {
1285 typedef const SCEV *(ScalarEvolution::*GetExtendExprTy)(const SCEV *, Type *,
1286 unsigned);
1287};
1288
1289// Used to make code generic over signed and unsigned overflow.
1290template <typename ExtendOp> struct ExtendOpTraits {
1291 // Members present:
1292 //
1293 // static const SCEV::NoWrapFlags WrapType;
1294 //
1295 // static const ExtendOpTraitsBase::GetExtendExprTy GetExtendExpr;
1296 //
1297 // static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1298 // ICmpInst::Predicate *Pred,
1299 // ScalarEvolution *SE);
1300};
1301
1302template <>
1303struct ExtendOpTraits<SCEVSignExtendExpr> : public ExtendOpTraitsBase {
1304 static const SCEV::NoWrapFlags WrapType = SCEV::FlagNSW;
1305
1306 static const GetExtendExprTy GetExtendExpr;
1307
1308 static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1309 ICmpInst::Predicate *Pred,
1310 ScalarEvolution *SE) {
1311 return getSignedOverflowLimitForStep(Step, Pred, SE);
1312 }
1313};
1314
1315const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
1316 SCEVSignExtendExpr>::GetExtendExpr = &ScalarEvolution::getSignExtendExpr;
1317
1318template <>
1319struct ExtendOpTraits<SCEVZeroExtendExpr> : public ExtendOpTraitsBase {
1320 static const SCEV::NoWrapFlags WrapType = SCEV::FlagNUW;
1321
1322 static const GetExtendExprTy GetExtendExpr;
1323
1324 static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1325 ICmpInst::Predicate *Pred,
1326 ScalarEvolution *SE) {
1327 return getUnsignedOverflowLimitForStep(Step, Pred, SE);
1328 }
1329};
1330
1331const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
1332 SCEVZeroExtendExpr>::GetExtendExpr = &ScalarEvolution::getZeroExtendExpr;
1333
1334} // end anonymous namespace
1335
1336// The recurrence AR has been shown to have no signed/unsigned wrap or something
1337// close to it. Typically, if we can prove NSW/NUW for AR, then we can just as
1338// easily prove NSW/NUW for its preincrement or postincrement sibling. This
1339// allows normalizing a sign/zero extended AddRec as such: {sext/zext(Step +
1340// Start),+,Step} => {(Step + sext/zext(Start),+,Step} As a result, the
1341// expression "Step + sext/zext(PreIncAR)" is congruent with
1342// "sext/zext(PostIncAR)"
1343template <typename ExtendOpTy>
1344static const SCEV *getPreStartForExtend(const SCEVAddRecExpr *AR, Type *Ty,
1345 ScalarEvolution *SE, unsigned Depth) {
1346 auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
1347 auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
1348
1349 const Loop *L = AR->getLoop();
1350 const SCEV *Start = AR->getStart();
1351 const SCEV *Step = AR->getStepRecurrence(*SE);
1352
1353 // Check for a simple looking step prior to loop entry.
1354 const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Start);
1355 if (!SA)
1356 return nullptr;
1357
1358 // Create an AddExpr for "PreStart" after subtracting Step. Full SCEV
1359 // subtraction is expensive. For this purpose, perform a quick and dirty
1360 // difference, by checking for Step in the operand list.
1361 SmallVector<const SCEV *, 4> DiffOps;
1362 for (const SCEV *Op : SA->operands())
1363 if (Op != Step)
1364 DiffOps.push_back(Op);
1365
1366 if (DiffOps.size() == SA->getNumOperands())
1367 return nullptr;
1368
1369 // Try to prove `WrapType` (SCEV::FlagNSW or SCEV::FlagNUW) on `PreStart` +
1370 // `Step`:
1371
1372 // 1. NSW/NUW flags on the step increment.
1373 auto PreStartFlags =
1374 ScalarEvolution::maskFlags(SA->getNoWrapFlags(), SCEV::FlagNUW);
1375 const SCEV *PreStart = SE->getAddExpr(DiffOps, PreStartFlags);
1376 const SCEVAddRecExpr *PreAR = dyn_cast<SCEVAddRecExpr>(
1377 SE->getAddRecExpr(PreStart, Step, L, SCEV::FlagAnyWrap));
1378
1379 // "{S,+,X} is <nsw>/<nuw>" and "the backedge is taken at least once" implies
1380 // "S+X does not sign/unsign-overflow".
1381 //
1382
1383 const SCEV *BECount = SE->getBackedgeTakenCount(L);
1384 if (PreAR && PreAR->getNoWrapFlags(WrapType) &&
1385 !isa<SCEVCouldNotCompute>(BECount) && SE->isKnownPositive(BECount))
1386 return PreStart;
1387
1388 // 2. Direct overflow check on the step operation's expression.
1389 unsigned BitWidth = SE->getTypeSizeInBits(AR->getType());
1390 Type *WideTy = IntegerType::get(SE->getContext(), BitWidth * 2);
1391 const SCEV *OperandExtendedStart =
1392 SE->getAddExpr((SE->*GetExtendExpr)(PreStart, WideTy, Depth),
1393 (SE->*GetExtendExpr)(Step, WideTy, Depth));
1394 if ((SE->*GetExtendExpr)(Start, WideTy, Depth) == OperandExtendedStart) {
1395 if (PreAR && AR->getNoWrapFlags(WrapType)) {
1396 // If we know `AR` == {`PreStart`+`Step`,+,`Step`} is `WrapType` (FlagNSW
1397 // or FlagNUW) and that `PreStart` + `Step` is `WrapType` too, then
1398 // `PreAR` == {`PreStart`,+,`Step`} is also `WrapType`. Cache this fact.
1399 SE->setNoWrapFlags(const_cast<SCEVAddRecExpr *>(PreAR), WrapType);
1400 }
1401 return PreStart;
1402 }
1403
1404 // 3. Loop precondition.
1405 ICmpInst::Predicate Pred;
1406 const SCEV *OverflowLimit =
1407 ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(Step, &Pred, SE);
1408
1409 if (OverflowLimit &&
1410 SE->isLoopEntryGuardedByCond(L, Pred, PreStart, OverflowLimit))
1411 return PreStart;
1412
1413 return nullptr;
1414}
1415
1416// Get the normalized zero or sign extended expression for this AddRec's Start.
1417template <typename ExtendOpTy>
1418static const SCEV *getExtendAddRecStart(const SCEVAddRecExpr *AR, Type *Ty,
1419 ScalarEvolution *SE,
1420 unsigned Depth) {
1421 auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
1422
1423 const SCEV *PreStart = getPreStartForExtend<ExtendOpTy>(AR, Ty, SE, Depth);
1424 if (!PreStart)
1425 return (SE->*GetExtendExpr)(AR->getStart(), Ty, Depth);
1426
1427 return SE->getAddExpr((SE->*GetExtendExpr)(AR->getStepRecurrence(*SE), Ty,
1428 Depth),
1429 (SE->*GetExtendExpr)(PreStart, Ty, Depth));
1430}
1431
1432// Try to prove away overflow by looking at "nearby" add recurrences. A
1433// motivating example for this rule: if we know `{0,+,4}` is `ult` `-1` and it
1434// does not itself wrap then we can conclude that `{1,+,4}` is `nuw`.
1435//
1436// Formally:
1437//
1438// {S,+,X} == {S-T,+,X} + T
1439// => Ext({S,+,X}) == Ext({S-T,+,X} + T)
1440//
1441// If ({S-T,+,X} + T) does not overflow ... (1)
1442//
1443// RHS == Ext({S-T,+,X} + T) == Ext({S-T,+,X}) + Ext(T)
1444//
1445// If {S-T,+,X} does not overflow ... (2)
1446//
1447// RHS == Ext({S-T,+,X}) + Ext(T) == {Ext(S-T),+,Ext(X)} + Ext(T)
1448// == {Ext(S-T)+Ext(T),+,Ext(X)}
1449//
1450// If (S-T)+T does not overflow ... (3)
1451//
1452// RHS == {Ext(S-T)+Ext(T),+,Ext(X)} == {Ext(S-T+T),+,Ext(X)}
1453// == {Ext(S),+,Ext(X)} == LHS
1454//
1455// Thus, if (1), (2) and (3) are true for some T, then
1456// Ext({S,+,X}) == {Ext(S),+,Ext(X)}
1457//
1458// (3) is implied by (1) -- "(S-T)+T does not overflow" is simply "({S-T,+,X}+T)
1459// does not overflow" restricted to the 0th iteration. Therefore we only need
1460// to check for (1) and (2).
1461//
1462// In the current context, S is `Start`, X is `Step`, Ext is `ExtendOpTy` and T
1463// is `Delta` (defined below).
1464template <typename ExtendOpTy>
1465bool ScalarEvolution::proveNoWrapByVaryingStart(const SCEV *Start,
1466 const SCEV *Step,
1467 const Loop *L) {
1468 auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
1469
1470 // We restrict `Start` to a constant to prevent SCEV from spending too much
1471 // time here. It is correct (but more expensive) to continue with a
1472 // non-constant `Start` and do a general SCEV subtraction to compute
1473 // `PreStart` below.
1474 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start);
1475 if (!StartC)
1476 return false;
1477
1478 APInt StartAI = StartC->getAPInt();
1479
1480 for (unsigned Delta : {-2, -1, 1, 2}) {
1481 const SCEV *PreStart = getConstant(StartAI - Delta);
1482
1483 FoldingSetNodeID ID;
1484 ID.AddInteger(scAddRecExpr);
1485 ID.AddPointer(PreStart);
1486 ID.AddPointer(Step);
1487 ID.AddPointer(L);
1488 void *IP = nullptr;
1489 const auto *PreAR =
1490 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
1491
1492 // Give up if we don't already have the add recurrence we need because
1493 // actually constructing an add recurrence is relatively expensive.
1494 if (PreAR && PreAR->getNoWrapFlags(WrapType)) { // proves (2)
1495 const SCEV *DeltaS = getConstant(StartC->getType(), Delta);
1496 ICmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE;
1497 const SCEV *Limit = ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(
1498 DeltaS, &Pred, this);
1499 if (Limit && isKnownPredicate(Pred, PreAR, Limit)) // proves (1)
1500 return true;
1501 }
1502 }
1503
1504 return false;
1505}
1506
1507// Finds an integer D for an expression (C + x + y + ...) such that the top
1508// level addition in (D + (C - D + x + y + ...)) would not wrap (signed or
1509// unsigned) and the number of trailing zeros of (C - D + x + y + ...) is
1510// maximized, where C is the \p ConstantTerm, x, y, ... are arbitrary SCEVs, and
1511// the (C + x + y + ...) expression is \p WholeAddExpr.
1512static APInt extractConstantWithoutWrapping(ScalarEvolution &SE,
1513 const SCEVConstant *ConstantTerm,
1514 const SCEVAddExpr *WholeAddExpr) {
1515 const APInt &C = ConstantTerm->getAPInt();
1516 const unsigned BitWidth = C.getBitWidth();
1517 // Find number of trailing zeros of (x + y + ...) w/o the C first:
1518 uint32_t TZ = BitWidth;
1519 for (unsigned I = 1, E = WholeAddExpr->getNumOperands(); I < E && TZ; ++I)
1520 TZ = std::min(TZ, SE.GetMinTrailingZeros(WholeAddExpr->getOperand(I)));
1521 if (TZ) {
1522 // Set D to be as many least significant bits of C as possible while still
1523 // guaranteeing that adding D to (C - D + x + y + ...) won't cause a wrap:
1524 return TZ < BitWidth ? C.trunc(TZ).zext(BitWidth) : C;
1525 }
1526 return APInt(BitWidth, 0);
1527}
1528
1529// Finds an integer D for an affine AddRec expression {C,+,x} such that the top
1530// level addition in (D + {C-D,+,x}) would not wrap (signed or unsigned) and the
1531// number of trailing zeros of (C - D + x * n) is maximized, where C is the \p
1532// ConstantStart, x is an arbitrary \p Step, and n is the loop trip count.
1533static APInt extractConstantWithoutWrapping(ScalarEvolution &SE,
1534 const APInt &ConstantStart,
1535 const SCEV *Step) {
1536 const unsigned BitWidth = ConstantStart.getBitWidth();
1537 const uint32_t TZ = SE.GetMinTrailingZeros(Step);
1538 if (TZ)
1539 return TZ < BitWidth ? ConstantStart.trunc(TZ).zext(BitWidth)
1540 : ConstantStart;
1541 return APInt(BitWidth, 0);
1542}
1543
1544const SCEV *
1545ScalarEvolution::getZeroExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) {
1546 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1547, __PRETTY_FUNCTION__))
1547 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1547, __PRETTY_FUNCTION__))
;
1548 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1549, __PRETTY_FUNCTION__))
1549 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1549, __PRETTY_FUNCTION__))
;
1550 Ty = getEffectiveSCEVType(Ty);
1551
1552 // Fold if the operand is constant.
1553 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1554 return getConstant(
1555 cast<ConstantInt>(ConstantExpr::getZExt(SC->getValue(), Ty)));
1556
1557 // zext(zext(x)) --> zext(x)
1558 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1559 return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1);
1560
1561 // Before doing any expensive analysis, check to see if we've already
1562 // computed a SCEV for this Op and Ty.
1563 FoldingSetNodeID ID;
1564 ID.AddInteger(scZeroExtend);
1565 ID.AddPointer(Op);
1566 ID.AddPointer(Ty);
1567 void *IP = nullptr;
1568 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1569 if (Depth > MaxCastDepth) {
1570 SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
1571 Op, Ty);
1572 UniqueSCEVs.InsertNode(S, IP);
1573 addToLoopUseLists(S);
1574 return S;
1575 }
1576
1577 // zext(trunc(x)) --> zext(x) or x or trunc(x)
1578 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1579 // It's possible the bits taken off by the truncate were all zero bits. If
1580 // so, we should be able to simplify this further.
1581 const SCEV *X = ST->getOperand();
1582 ConstantRange CR = getUnsignedRange(X);
1583 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1584 unsigned NewBits = getTypeSizeInBits(Ty);
1585 if (CR.truncate(TruncBits).zeroExtend(NewBits).contains(
1586 CR.zextOrTrunc(NewBits)))
1587 return getTruncateOrZeroExtend(X, Ty, Depth);
1588 }
1589
1590 // If the input value is a chrec scev, and we can prove that the value
1591 // did not overflow the old, smaller, value, we can zero extend all of the
1592 // operands (often constants). This allows analysis of something like
1593 // this: for (unsigned char X = 0; X < 100; ++X) { int Y = X; }
1594 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
1595 if (AR->isAffine()) {
1596 const SCEV *Start = AR->getStart();
1597 const SCEV *Step = AR->getStepRecurrence(*this);
1598 unsigned BitWidth = getTypeSizeInBits(AR->getType());
1599 const Loop *L = AR->getLoop();
1600
1601 if (!AR->hasNoUnsignedWrap()) {
1602 auto NewFlags = proveNoWrapViaConstantRanges(AR);
1603 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), NewFlags);
1604 }
1605
1606 // If we have special knowledge that this addrec won't overflow,
1607 // we don't need to do any further analysis.
1608 if (AR->hasNoUnsignedWrap())
1609 return getAddRecExpr(
1610 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1),
1611 getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
1612
1613 // Check whether the backedge-taken count is SCEVCouldNotCompute.
1614 // Note that this serves two purposes: It filters out loops that are
1615 // simply not analyzable, and it covers the case where this code is
1616 // being called from within backedge-taken count analysis, such that
1617 // attempting to ask for the backedge-taken count would likely result
1618 // in infinite recursion. In the later case, the analysis code will
1619 // cope with a conservative value, and it will take care to purge
1620 // that value once it has finished.
1621 const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(L);
1622 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
1623 // Manually compute the final value for AR, checking for overflow.
1624
1625 // Check whether the backedge-taken count can be losslessly casted to
1626 // the addrec's type. The count is always unsigned.
1627 const SCEV *CastedMaxBECount =
1628 getTruncateOrZeroExtend(MaxBECount, Start->getType(), Depth);
1629 const SCEV *RecastedMaxBECount = getTruncateOrZeroExtend(
1630 CastedMaxBECount, MaxBECount->getType(), Depth);
1631 if (MaxBECount == RecastedMaxBECount) {
1632 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
1633 // Check whether Start+Step*MaxBECount has no unsigned overflow.
1634 const SCEV *ZMul = getMulExpr(CastedMaxBECount, Step,
1635 SCEV::FlagAnyWrap, Depth + 1);
1636 const SCEV *ZAdd = getZeroExtendExpr(getAddExpr(Start, ZMul,
1637 SCEV::FlagAnyWrap,
1638 Depth + 1),
1639 WideTy, Depth + 1);
1640 const SCEV *WideStart = getZeroExtendExpr(Start, WideTy, Depth + 1);
1641 const SCEV *WideMaxBECount =
1642 getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1);
1643 const SCEV *OperandExtendedAdd =
1644 getAddExpr(WideStart,
1645 getMulExpr(WideMaxBECount,
1646 getZeroExtendExpr(Step, WideTy, Depth + 1),
1647 SCEV::FlagAnyWrap, Depth + 1),
1648 SCEV::FlagAnyWrap, Depth + 1);
1649 if (ZAdd == OperandExtendedAdd) {
1650 // Cache knowledge of AR NUW, which is propagated to this AddRec.
1651 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNUW);
1652 // Return the expression with the addrec on the outside.
1653 return getAddRecExpr(
1654 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1655 Depth + 1),
1656 getZeroExtendExpr(Step, Ty, Depth + 1), L,
1657 AR->getNoWrapFlags());
1658 }
1659 // Similar to above, only this time treat the step value as signed.
1660 // This covers loops that count down.
1661 OperandExtendedAdd =
1662 getAddExpr(WideStart,
1663 getMulExpr(WideMaxBECount,
1664 getSignExtendExpr(Step, WideTy, Depth + 1),
1665 SCEV::FlagAnyWrap, Depth + 1),
1666 SCEV::FlagAnyWrap, Depth + 1);
1667 if (ZAdd == OperandExtendedAdd) {
1668 // Cache knowledge of AR NW, which is propagated to this AddRec.
1669 // Negative step causes unsigned wrap, but it still can't self-wrap.
1670 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNW);
1671 // Return the expression with the addrec on the outside.
1672 return getAddRecExpr(
1673 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1674 Depth + 1),
1675 getSignExtendExpr(Step, Ty, Depth + 1), L,
1676 AR->getNoWrapFlags());
1677 }
1678 }
1679 }
1680
1681 // Normally, in the cases we can prove no-overflow via a
1682 // backedge guarding condition, we can also compute a backedge
1683 // taken count for the loop. The exceptions are assumptions and
1684 // guards present in the loop -- SCEV is not great at exploiting
1685 // these to compute max backedge taken counts, but can still use
1686 // these to prove lack of overflow. Use this fact to avoid
1687 // doing extra work that may not pay off.
1688 if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards ||
1689 !AC.assumptions().empty()) {
1690
1691 auto NewFlags = proveNoUnsignedWrapViaInduction(AR);
1692 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), NewFlags);
1693 if (AR->hasNoUnsignedWrap()) {
1694 // Same as nuw case above - duplicated here to avoid a compile time
1695 // issue. It's not clear that the order of checks does matter, but
1696 // it's one of two issue possible causes for a change which was
1697 // reverted. Be conservative for the moment.
1698 return getAddRecExpr(
1699 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1700 Depth + 1),
1701 getZeroExtendExpr(Step, Ty, Depth + 1), L,
1702 AR->getNoWrapFlags());
1703 }
1704
1705 // For a negative step, we can extend the operands iff doing so only
1706 // traverses values in the range zext([0,UINT_MAX]).
1707 if (isKnownNegative(Step)) {
1708 const SCEV *N = getConstant(APInt::getMaxValue(BitWidth) -
1709 getSignedRangeMin(Step));
1710 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, AR, N) ||
1711 isKnownOnEveryIteration(ICmpInst::ICMP_UGT, AR, N)) {
1712 // Cache knowledge of AR NW, which is propagated to this
1713 // AddRec. Negative step causes unsigned wrap, but it
1714 // still can't self-wrap.
1715 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNW);
1716 // Return the expression with the addrec on the outside.
1717 return getAddRecExpr(
1718 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1719 Depth + 1),
1720 getSignExtendExpr(Step, Ty, Depth + 1), L,
1721 AR->getNoWrapFlags());
1722 }
1723 }
1724 }
1725
1726 // zext({C,+,Step}) --> (zext(D) + zext({C-D,+,Step}))<nuw><nsw>
1727 // if D + (C - D + Step * n) could be proven to not unsigned wrap
1728 // where D maximizes the number of trailing zeros of (C - D + Step * n)
1729 if (const auto *SC = dyn_cast<SCEVConstant>(Start)) {
1730 const APInt &C = SC->getAPInt();
1731 const APInt &D = extractConstantWithoutWrapping(*this, C, Step);
1732 if (D != 0) {
1733 const SCEV *SZExtD = getZeroExtendExpr(getConstant(D), Ty, Depth);
1734 const SCEV *SResidual =
1735 getAddRecExpr(getConstant(C - D), Step, L, AR->getNoWrapFlags());
1736 const SCEV *SZExtR = getZeroExtendExpr(SResidual, Ty, Depth + 1);
1737 return getAddExpr(SZExtD, SZExtR,
1738 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
1739 Depth + 1);
1740 }
1741 }
1742
1743 if (proveNoWrapByVaryingStart<SCEVZeroExtendExpr>(Start, Step, L)) {
1744 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNUW);
1745 return getAddRecExpr(
1746 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1),
1747 getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
1748 }
1749 }
1750
1751 // zext(A % B) --> zext(A) % zext(B)
1752 {
1753 const SCEV *LHS;
1754 const SCEV *RHS;
1755 if (matchURem(Op, LHS, RHS))
1756 return getURemExpr(getZeroExtendExpr(LHS, Ty, Depth + 1),
1757 getZeroExtendExpr(RHS, Ty, Depth + 1));
1758 }
1759
1760 // zext(A / B) --> zext(A) / zext(B).
1761 if (auto *Div = dyn_cast<SCEVUDivExpr>(Op))
1762 return getUDivExpr(getZeroExtendExpr(Div->getLHS(), Ty, Depth + 1),
1763 getZeroExtendExpr(Div->getRHS(), Ty, Depth + 1));
1764
1765 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1766 // zext((A + B + ...)<nuw>) --> (zext(A) + zext(B) + ...)<nuw>
1767 if (SA->hasNoUnsignedWrap()) {
1768 // If the addition does not unsign overflow then we can, by definition,
1769 // commute the zero extension with the addition operation.
1770 SmallVector<const SCEV *, 4> Ops;
1771 for (const auto *Op : SA->operands())
1772 Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1));
1773 return getAddExpr(Ops, SCEV::FlagNUW, Depth + 1);
1774 }
1775
1776 // zext(C + x + y + ...) --> (zext(D) + zext((C - D) + x + y + ...))
1777 // if D + (C - D + x + y + ...) could be proven to not unsigned wrap
1778 // where D maximizes the number of trailing zeros of (C - D + x + y + ...)
1779 //
1780 // Often address arithmetics contain expressions like
1781 // (zext (add (shl X, C1), C2)), for instance, (zext (5 + (4 * X))).
1782 // This transformation is useful while proving that such expressions are
1783 // equal or differ by a small constant amount, see LoadStoreVectorizer pass.
1784 if (const auto *SC = dyn_cast<SCEVConstant>(SA->getOperand(0))) {
1785 const APInt &D = extractConstantWithoutWrapping(*this, SC, SA);
1786 if (D != 0) {
1787 const SCEV *SZExtD = getZeroExtendExpr(getConstant(D), Ty, Depth);
1788 const SCEV *SResidual =
1789 getAddExpr(getConstant(-D), SA, SCEV::FlagAnyWrap, Depth);
1790 const SCEV *SZExtR = getZeroExtendExpr(SResidual, Ty, Depth + 1);
1791 return getAddExpr(SZExtD, SZExtR,
1792 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
1793 Depth + 1);
1794 }
1795 }
1796 }
1797
1798 if (auto *SM = dyn_cast<SCEVMulExpr>(Op)) {
1799 // zext((A * B * ...)<nuw>) --> (zext(A) * zext(B) * ...)<nuw>
1800 if (SM->hasNoUnsignedWrap()) {
1801 // If the multiply does not unsign overflow then we can, by definition,
1802 // commute the zero extension with the multiply operation.
1803 SmallVector<const SCEV *, 4> Ops;
1804 for (const auto *Op : SM->operands())
1805 Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1));
1806 return getMulExpr(Ops, SCEV::FlagNUW, Depth + 1);
1807 }
1808
1809 // zext(2^K * (trunc X to iN)) to iM ->
1810 // 2^K * (zext(trunc X to i{N-K}) to iM)<nuw>
1811 //
1812 // Proof:
1813 //
1814 // zext(2^K * (trunc X to iN)) to iM
1815 // = zext((trunc X to iN) << K) to iM
1816 // = zext((trunc X to i{N-K}) << K)<nuw> to iM
1817 // (because shl removes the top K bits)
1818 // = zext((2^K * (trunc X to i{N-K}))<nuw>) to iM
1819 // = (2^K * (zext(trunc X to i{N-K}) to iM))<nuw>.
1820 //
1821 if (SM->getNumOperands() == 2)
1822 if (auto *MulLHS = dyn_cast<SCEVConstant>(SM->getOperand(0)))
1823 if (MulLHS->getAPInt().isPowerOf2())
1824 if (auto *TruncRHS = dyn_cast<SCEVTruncateExpr>(SM->getOperand(1))) {
1825 int NewTruncBits = getTypeSizeInBits(TruncRHS->getType()) -
1826 MulLHS->getAPInt().logBase2();
1827 Type *NewTruncTy = IntegerType::get(getContext(), NewTruncBits);
1828 return getMulExpr(
1829 getZeroExtendExpr(MulLHS, Ty),
1830 getZeroExtendExpr(
1831 getTruncateExpr(TruncRHS->getOperand(), NewTruncTy), Ty),
1832 SCEV::FlagNUW, Depth + 1);
1833 }
1834 }
1835
1836 // The cast wasn't folded; create an explicit cast node.
1837 // Recompute the insert position, as it may have been invalidated.
1838 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1839 SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
1840 Op, Ty);
1841 UniqueSCEVs.InsertNode(S, IP);
1842 addToLoopUseLists(S);
1843 return S;
1844}
1845
1846const SCEV *
1847ScalarEvolution::getSignExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) {
1848 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1849, __PRETTY_FUNCTION__))
1849 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1849, __PRETTY_FUNCTION__))
;
1850 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1851, __PRETTY_FUNCTION__))
1851 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1851, __PRETTY_FUNCTION__))
;
1852 Ty = getEffectiveSCEVType(Ty);
1853
1854 // Fold if the operand is constant.
1855 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1856 return getConstant(
1857 cast<ConstantInt>(ConstantExpr::getSExt(SC->getValue(), Ty)));
1858
1859 // sext(sext(x)) --> sext(x)
1860 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1861 return getSignExtendExpr(SS->getOperand(), Ty, Depth + 1);
1862
1863 // sext(zext(x)) --> zext(x)
1864 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1865 return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1);
1866
1867 // Before doing any expensive analysis, check to see if we've already
1868 // computed a SCEV for this Op and Ty.
1869 FoldingSetNodeID ID;
1870 ID.AddInteger(scSignExtend);
1871 ID.AddPointer(Op);
1872 ID.AddPointer(Ty);
1873 void *IP = nullptr;
1874 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1875 // Limit recursion depth.
1876 if (Depth > MaxCastDepth) {
1877 SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
1878 Op, Ty);
1879 UniqueSCEVs.InsertNode(S, IP);
1880 addToLoopUseLists(S);
1881 return S;
1882 }
1883
1884 // sext(trunc(x)) --> sext(x) or x or trunc(x)
1885 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1886 // It's possible the bits taken off by the truncate were all sign bits. If
1887 // so, we should be able to simplify this further.
1888 const SCEV *X = ST->getOperand();
1889 ConstantRange CR = getSignedRange(X);
1890 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1891 unsigned NewBits = getTypeSizeInBits(Ty);
1892 if (CR.truncate(TruncBits).signExtend(NewBits).contains(
1893 CR.sextOrTrunc(NewBits)))
1894 return getTruncateOrSignExtend(X, Ty, Depth);
1895 }
1896
1897 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1898 // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw>
1899 if (SA->hasNoSignedWrap()) {
1900 // If the addition does not sign overflow then we can, by definition,
1901 // commute the sign extension with the addition operation.
1902 SmallVector<const SCEV *, 4> Ops;
1903 for (const auto *Op : SA->operands())
1904 Ops.push_back(getSignExtendExpr(Op, Ty, Depth + 1));
1905 return getAddExpr(Ops, SCEV::FlagNSW, Depth + 1);
1906 }
1907
1908 // sext(C + x + y + ...) --> (sext(D) + sext((C - D) + x + y + ...))
1909 // if D + (C - D + x + y + ...) could be proven to not signed wrap
1910 // where D maximizes the number of trailing zeros of (C - D + x + y + ...)
1911 //
1912 // For instance, this will bring two seemingly different expressions:
1913 // 1 + sext(5 + 20 * %x + 24 * %y) and
1914 // sext(6 + 20 * %x + 24 * %y)
1915 // to the same form:
1916 // 2 + sext(4 + 20 * %x + 24 * %y)
1917 if (const auto *SC = dyn_cast<SCEVConstant>(SA->getOperand(0))) {
1918 const APInt &D = extractConstantWithoutWrapping(*this, SC, SA);
1919 if (D != 0) {
1920 const SCEV *SSExtD = getSignExtendExpr(getConstant(D), Ty, Depth);
1921 const SCEV *SResidual =
1922 getAddExpr(getConstant(-D), SA, SCEV::FlagAnyWrap, Depth);
1923 const SCEV *SSExtR = getSignExtendExpr(SResidual, Ty, Depth + 1);
1924 return getAddExpr(SSExtD, SSExtR,
1925 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
1926 Depth + 1);
1927 }
1928 }
1929 }
1930 // If the input value is a chrec scev, and we can prove that the value
1931 // did not overflow the old, smaller, value, we can sign extend all of the
1932 // operands (often constants). This allows analysis of something like
1933 // this: for (signed char X = 0; X < 100; ++X) { int Y = X; }
1934 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
1935 if (AR->isAffine()) {
1936 const SCEV *Start = AR->getStart();
1937 const SCEV *Step = AR->getStepRecurrence(*this);
1938 unsigned BitWidth = getTypeSizeInBits(AR->getType());
1939 const Loop *L = AR->getLoop();
1940
1941 if (!AR->hasNoSignedWrap()) {
1942 auto NewFlags = proveNoWrapViaConstantRanges(AR);
1943 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), NewFlags);
1944 }
1945
1946 // If we have special knowledge that this addrec won't overflow,
1947 // we don't need to do any further analysis.
1948 if (AR->hasNoSignedWrap())
1949 return getAddRecExpr(
1950 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
1951 getSignExtendExpr(Step, Ty, Depth + 1), L, SCEV::FlagNSW);
1952
1953 // Check whether the backedge-taken count is SCEVCouldNotCompute.
1954 // Note that this serves two purposes: It filters out loops that are
1955 // simply not analyzable, and it covers the case where this code is
1956 // being called from within backedge-taken count analysis, such that
1957 // attempting to ask for the backedge-taken count would likely result
1958 // in infinite recursion. In the later case, the analysis code will
1959 // cope with a conservative value, and it will take care to purge
1960 // that value once it has finished.
1961 const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(L);
1962 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
1963 // Manually compute the final value for AR, checking for
1964 // overflow.
1965
1966 // Check whether the backedge-taken count can be losslessly casted to
1967 // the addrec's type. The count is always unsigned.
1968 const SCEV *CastedMaxBECount =
1969 getTruncateOrZeroExtend(MaxBECount, Start->getType(), Depth);
1970 const SCEV *RecastedMaxBECount = getTruncateOrZeroExtend(
1971 CastedMaxBECount, MaxBECount->getType(), Depth);
1972 if (MaxBECount == RecastedMaxBECount) {
1973 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
1974 // Check whether Start+Step*MaxBECount has no signed overflow.
1975 const SCEV *SMul = getMulExpr(CastedMaxBECount, Step,
1976 SCEV::FlagAnyWrap, Depth + 1);
1977 const SCEV *SAdd = getSignExtendExpr(getAddExpr(Start, SMul,
1978 SCEV::FlagAnyWrap,
1979 Depth + 1),
1980 WideTy, Depth + 1);
1981 const SCEV *WideStart = getSignExtendExpr(Start, WideTy, Depth + 1);
1982 const SCEV *WideMaxBECount =
1983 getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1);
1984 const SCEV *OperandExtendedAdd =
1985 getAddExpr(WideStart,
1986 getMulExpr(WideMaxBECount,
1987 getSignExtendExpr(Step, WideTy, Depth + 1),
1988 SCEV::FlagAnyWrap, Depth + 1),
1989 SCEV::FlagAnyWrap, Depth + 1);
1990 if (SAdd == OperandExtendedAdd) {
1991 // Cache knowledge of AR NSW, which is propagated to this AddRec.
1992 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNSW);
1993 // Return the expression with the addrec on the outside.
1994 return getAddRecExpr(
1995 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this,
1996 Depth + 1),
1997 getSignExtendExpr(Step, Ty, Depth + 1), L,
1998 AR->getNoWrapFlags());
1999 }
2000 // Similar to above, only this time treat the step value as unsigned.
2001 // This covers loops that count up with an unsigned step.
2002 OperandExtendedAdd =
2003 getAddExpr(WideStart,
2004 getMulExpr(WideMaxBECount,
2005 getZeroExtendExpr(Step, WideTy, Depth + 1),
2006 SCEV::FlagAnyWrap, Depth + 1),
2007 SCEV::FlagAnyWrap, Depth + 1);
2008 if (SAdd == OperandExtendedAdd) {
2009 // If AR wraps around then
2010 //
2011 // abs(Step) * MaxBECount > unsigned-max(AR->getType())
2012 // => SAdd != OperandExtendedAdd
2013 //
2014 // Thus (AR is not NW => SAdd != OperandExtendedAdd) <=>
2015 // (SAdd == OperandExtendedAdd => AR is NW)
2016
2017 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNW);
2018
2019 // Return the expression with the addrec on the outside.
2020 return getAddRecExpr(
2021 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this,
2022 Depth + 1),
2023 getZeroExtendExpr(Step, Ty, Depth + 1), L,
2024 AR->getNoWrapFlags());
2025 }
2026 }
2027 }
2028
2029 auto NewFlags = proveNoSignedWrapViaInduction(AR);
2030 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), NewFlags);
2031 if (AR->hasNoSignedWrap()) {
2032 // Same as nsw case above - duplicated here to avoid a compile time
2033 // issue. It's not clear that the order of checks does matter, but
2034 // it's one of two issue possible causes for a change which was
2035 // reverted. Be conservative for the moment.
2036 return getAddRecExpr(
2037 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
2038 getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
2039 }
2040
2041 // sext({C,+,Step}) --> (sext(D) + sext({C-D,+,Step}))<nuw><nsw>
2042 // if D + (C - D + Step * n) could be proven to not signed wrap
2043 // where D maximizes the number of trailing zeros of (C - D + Step * n)
2044 if (const auto *SC = dyn_cast<SCEVConstant>(Start)) {
2045 const APInt &C = SC->getAPInt();
2046 const APInt &D = extractConstantWithoutWrapping(*this, C, Step);
2047 if (D != 0) {
2048 const SCEV *SSExtD = getSignExtendExpr(getConstant(D), Ty, Depth);
2049 const SCEV *SResidual =
2050 getAddRecExpr(getConstant(C - D), Step, L, AR->getNoWrapFlags());
2051 const SCEV *SSExtR = getSignExtendExpr(SResidual, Ty, Depth + 1);
2052 return getAddExpr(SSExtD, SSExtR,
2053 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
2054 Depth + 1);
2055 }
2056 }
2057
2058 if (proveNoWrapByVaryingStart<SCEVSignExtendExpr>(Start, Step, L)) {
2059 setNoWrapFlags(const_cast<SCEVAddRecExpr *>(AR), SCEV::FlagNSW);
2060 return getAddRecExpr(
2061 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
2062 getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
2063 }
2064 }
2065
2066 // If the input value is provably positive and we could not simplify
2067 // away the sext build a zext instead.
2068 if (isKnownNonNegative(Op))
2069 return getZeroExtendExpr(Op, Ty, Depth + 1);
2070
2071 // The cast wasn't folded; create an explicit cast node.
2072 // Recompute the insert position, as it may have been invalidated.
2073 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
2074 SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
2075 Op, Ty);
2076 UniqueSCEVs.InsertNode(S, IP);
2077 addToLoopUseLists(S);
2078 return S;
2079}
2080
2081/// getAnyExtendExpr - Return a SCEV for the given operand extended with
2082/// unspecified bits out to the given type.
2083const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op,
2084 Type *Ty) {
2085 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2086, __PRETTY_FUNCTION__))
2086 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2086, __PRETTY_FUNCTION__))
;
2087 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2088, __PRETTY_FUNCTION__))
2088 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2088, __PRETTY_FUNCTION__))
;
2089 Ty = getEffectiveSCEVType(Ty);
2090
2091 // Sign-extend negative constants.
2092 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
2093 if (SC->getAPInt().isNegative())
2094 return getSignExtendExpr(Op, Ty);
2095
2096 // Peel off a truncate cast.
2097 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Op)) {
2098 const SCEV *NewOp = T->getOperand();
2099 if (getTypeSizeInBits(NewOp->getType()) < getTypeSizeInBits(Ty))
2100 return getAnyExtendExpr(NewOp, Ty);
2101 return getTruncateOrNoop(NewOp, Ty);
2102 }
2103
2104 // Next try a zext cast. If the cast is folded, use it.
2105 const SCEV *ZExt = getZeroExtendExpr(Op, Ty);
2106 if (!isa<SCEVZeroExtendExpr>(ZExt))
2107 return ZExt;
2108
2109 // Next try a sext cast. If the cast is folded, use it.
2110 const SCEV *SExt = getSignExtendExpr(Op, Ty);
2111 if (!isa<SCEVSignExtendExpr>(SExt))
2112 return SExt;
2113
2114 // Force the cast to be folded into the operands of an addrec.
2115 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) {
2116 SmallVector<const SCEV *, 4> Ops;
2117 for (const SCEV *Op : AR->operands())
2118 Ops.push_back(getAnyExtendExpr(Op, Ty));
2119 return getAddRecExpr(Ops, AR->getLoop(), SCEV::FlagNW);
2120 }
2121
2122 // If the expression is obviously signed, use the sext cast value.
2123 if (isa<SCEVSMaxExpr>(Op))
2124 return SExt;
2125
2126 // Absent any other information, use the zext cast value.
2127 return ZExt;
2128}
2129
2130/// Process the given Ops list, which is a list of operands to be added under
2131/// the given scale, update the given map. This is a helper function for
2132/// getAddRecExpr. As an example of what it does, given a sequence of operands
2133/// that would form an add expression like this:
2134///
2135/// m + n + 13 + (A * (o + p + (B * (q + m + 29)))) + r + (-1 * r)
2136///
2137/// where A and B are constants, update the map with these values:
2138///
2139/// (m, 1+A*B), (n, 1), (o, A), (p, A), (q, A*B), (r, 0)
2140///
2141/// and add 13 + A*B*29 to AccumulatedConstant.
2142/// This will allow getAddRecExpr to produce this:
2143///
2144/// 13+A*B*29 + n + (m * (1+A*B)) + ((o + p) * A) + (q * A*B)
2145///
2146/// This form often exposes folding opportunities that are hidden in
2147/// the original operand list.
2148///
2149/// Return true iff it appears that any interesting folding opportunities
2150/// may be exposed. This helps getAddRecExpr short-circuit extra work in
2151/// the common case where no interesting opportunities are present, and
2152/// is also used as a check to avoid infinite recursion.
2153static bool
2154CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M,
2155 SmallVectorImpl<const SCEV *> &NewOps,
2156 APInt &AccumulatedConstant,
2157 const SCEV *const *Ops, size_t NumOperands,
2158 const APInt &Scale,
2159 ScalarEvolution &SE) {
2160 bool Interesting = false;
2161
2162 // Iterate over the add operands. They are sorted, with constants first.
2163 unsigned i = 0;
2164 while (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
2165 ++i;
2166 // Pull a buried constant out to the outside.
2167 if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero())
2168 Interesting = true;
2169 AccumulatedConstant += Scale * C->getAPInt();
2170 }
2171
2172 // Next comes everything else. We're especially interested in multiplies
2173 // here, but they're in the middle, so just visit the rest with one loop.
2174 for (; i != NumOperands; ++i) {
2175 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[i]);
2176 if (Mul && isa<SCEVConstant>(Mul->getOperand(0))) {
2177 APInt NewScale =
2178 Scale * cast<SCEVConstant>(Mul->getOperand(0))->getAPInt();
2179 if (Mul->getNumOperands() == 2 && isa<SCEVAddExpr>(Mul->getOperand(1))) {
2180 // A multiplication of a constant with another add; recurse.
2181 const SCEVAddExpr *Add = cast<SCEVAddExpr>(Mul->getOperand(1));
2182 Interesting |=
2183 CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
2184 Add->op_begin(), Add->getNumOperands(),
2185 NewScale, SE);
2186 } else {
2187 // A multiplication of a constant with some other value. Update
2188 // the map.
2189 SmallVector<const SCEV *, 4> MulOps(drop_begin(Mul->operands()));
2190 const SCEV *Key = SE.getMulExpr(MulOps);
2191 auto Pair = M.insert({Key, NewScale});
2192 if (Pair.second) {
2193 NewOps.push_back(Pair.first->first);
2194 } else {
2195 Pair.first->second += NewScale;
2196 // The map already had an entry for this value, which may indicate
2197 // a folding opportunity.
2198 Interesting = true;
2199 }
2200 }
2201 } else {
2202 // An ordinary operand. Update the map.
2203 std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair =
2204 M.insert({Ops[i], Scale});
2205 if (Pair.second) {
2206 NewOps.push_back(Pair.first->first);
2207 } else {
2208 Pair.first->second += Scale;
2209 // The map already had an entry for this value, which may indicate
2210 // a folding opportunity.
2211 Interesting = true;
2212 }
2213 }
2214 }
2215
2216 return Interesting;
2217}
2218
2219// We're trying to construct a SCEV of type `Type' with `Ops' as operands and
2220// `OldFlags' as can't-wrap behavior. Infer a more aggressive set of
2221// can't-overflow flags for the operation if possible.
2222static SCEV::NoWrapFlags
2223StrengthenNoWrapFlags(ScalarEvolution *SE, SCEVTypes Type,
2224 const ArrayRef<const SCEV *> Ops,
2225 SCEV::NoWrapFlags Flags) {
2226 using namespace std::placeholders;
2227
2228 using OBO = OverflowingBinaryOperator;
2229
2230 bool CanAnalyze =
2231 Type == scAddExpr || Type == scAddRecExpr || Type == scMulExpr;
2232 (void)CanAnalyze;
2233 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2233, __PRETTY_FUNCTION__))
;
2234
2235 int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW;
2236 SCEV::NoWrapFlags SignOrUnsignWrap =
2237 ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
2238
2239 // If FlagNSW is true and all the operands are non-negative, infer FlagNUW.
2240 auto IsKnownNonNegative = [&](const SCEV *S) {
2241 return SE->isKnownNonNegative(S);
2242 };
2243
2244 if (SignOrUnsignWrap == SCEV::FlagNSW && all_of(Ops, IsKnownNonNegative))
2245 Flags =
2246 ScalarEvolution::setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask);
2247
2248 SignOrUnsignWrap = ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
2249
2250 if (SignOrUnsignWrap != SignOrUnsignMask &&
2251 (Type == scAddExpr || Type == scMulExpr) && Ops.size() == 2 &&
2252 isa<SCEVConstant>(Ops[0])) {
2253
2254 auto Opcode = [&] {
2255 switch (Type) {
2256 case scAddExpr:
2257 return Instruction::Add;
2258 case scMulExpr:
2259 return Instruction::Mul;
2260 default:
2261 llvm_unreachable("Unexpected SCEV op.")::llvm::llvm_unreachable_internal("Unexpected SCEV op.", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2261)
;
2262 }
2263 }();
2264
2265 const APInt &C = cast<SCEVConstant>(Ops[0])->getAPInt();
2266
2267 // (A <opcode> C) --> (A <opcode> C)<nsw> if the op doesn't sign overflow.
2268 if (!(SignOrUnsignWrap & SCEV::FlagNSW)) {
2269 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
2270 Opcode, C, OBO::NoSignedWrap);
2271 if (NSWRegion.contains(SE->getSignedRange(Ops[1])))
2272 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
2273 }
2274
2275 // (A <opcode> C) --> (A <opcode> C)<nuw> if the op doesn't unsign overflow.
2276 if (!(SignOrUnsignWrap & SCEV::FlagNUW)) {
2277 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
2278 Opcode, C, OBO::NoUnsignedWrap);
2279 if (NUWRegion.contains(SE->getUnsignedRange(Ops[1])))
2280 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
2281 }
2282 }
2283
2284 return Flags;
2285}
2286
2287bool ScalarEvolution::isAvailableAtLoopEntry(const SCEV *S, const Loop *L) {
2288 return isLoopInvariant(S, L) && properlyDominates(S, L->getHeader());
2289}
2290
2291/// Get a canonical add expression, or something simpler if possible.
2292const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
2293 SCEV::NoWrapFlags OrigFlags,
2294 unsigned Depth) {
2295 assert(!(OrigFlags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) &&((!(OrigFlags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) &&
"only nuw or nsw allowed") ? static_cast<void> (0) : __assert_fail
("!(OrigFlags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && \"only nuw or nsw allowed\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2296, __PRETTY_FUNCTION__))
2296 "only nuw or nsw allowed")((!(OrigFlags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) &&
"only nuw or nsw allowed") ? static_cast<void> (0) : __assert_fail
("!(OrigFlags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && \"only nuw or nsw allowed\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2296, __PRETTY_FUNCTION__))
;
2297 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2297, __PRETTY_FUNCTION__))
;
2298 if (Ops.size() == 1) return Ops[0];
2299#ifndef NDEBUG
2300 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2301 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2302 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2303, __PRETTY_FUNCTION__))
2303 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2303, __PRETTY_FUNCTION__))
;
2304#endif
2305
2306 // Sort by complexity, this groups all similar expression types together.
2307 GroupByComplexity(Ops, &LI, DT);
2308
2309 // If there are any constants, fold them together.
2310 unsigned Idx = 0;
2311 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2312 ++Idx;
2313 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2313, __PRETTY_FUNCTION__))
;
2314 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2315 // We found two constants, fold them together!
2316 Ops[0] = getConstant(LHSC->getAPInt() + RHSC->getAPInt());
2317 if (Ops.size() == 2) return Ops[0];
2318 Ops.erase(Ops.begin()+1); // Erase the folded element
2319 LHSC = cast<SCEVConstant>(Ops[0]);
2320 }
2321
2322 // If we are left with a constant zero being added, strip it off.
2323 if (LHSC->getValue()->isZero()) {
2324 Ops.erase(Ops.begin());
2325 --Idx;
2326 }
2327
2328 if (Ops.size() == 1) return Ops[0];
2329 }
2330
2331 // Delay expensive flag strengthening until necessary.
2332 auto ComputeFlags = [this, OrigFlags](const ArrayRef<const SCEV *> Ops) {
2333 return StrengthenNoWrapFlags(this, scAddExpr, Ops, OrigFlags);
2334 };
2335
2336 // Limit recursion calls depth.
2337 if (Depth > MaxArithDepth || hasHugeExpression(Ops))
2338 return getOrCreateAddExpr(Ops, ComputeFlags(Ops));
2339
2340 if (SCEV *S = std::get<0>(findExistingSCEVInCache(scAddExpr, Ops))) {
2341 // Don't strengthen flags if we have no new information.
2342 SCEVAddExpr *Add = static_cast<SCEVAddExpr *>(S);
2343 if (Add->getNoWrapFlags(OrigFlags) != OrigFlags)
2344 Add->setNoWrapFlags(ComputeFlags(Ops));
2345 return S;
2346 }
2347
2348 // Okay, check to see if the same value occurs in the operand list more than
2349 // once. If so, merge them together into an multiply expression. Since we
2350 // sorted the list, these values are required to be adjacent.
2351 Type *Ty = Ops[0]->getType();
2352 bool FoundMatch = false;
2353 for (unsigned i = 0, e = Ops.size(); i != e-1; ++i)
2354 if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2
2355 // Scan ahead to count how many equal operands there are.
2356 unsigned Count = 2;
2357 while (i+Count != e && Ops[i+Count] == Ops[i])
2358 ++Count;
2359 // Merge the values into a multiply.
2360 const SCEV *Scale = getConstant(Ty, Count);
2361 const SCEV *Mul = getMulExpr(Scale, Ops[i], SCEV::FlagAnyWrap, Depth + 1);
2362 if (Ops.size() == Count)
2363 return Mul;
2364 Ops[i] = Mul;
2365 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+Count);
2366 --i; e -= Count - 1;
2367 FoundMatch = true;
2368 }
2369 if (FoundMatch)
2370 return getAddExpr(Ops, OrigFlags, Depth + 1);
2371
2372 // Check for truncates. If all the operands are truncated from the same
2373 // type, see if factoring out the truncate would permit the result to be
2374 // folded. eg., n*trunc(x) + m*trunc(y) --> trunc(trunc(m)*x + trunc(n)*y)
2375 // if the contents of the resulting outer trunc fold to something simple.
2376 auto FindTruncSrcType = [&]() -> Type * {
2377 // We're ultimately looking to fold an addrec of truncs and muls of only
2378 // constants and truncs, so if we find any other types of SCEV
2379 // as operands of the addrec then we bail and return nullptr here.
2380 // Otherwise, we return the type of the operand of a trunc that we find.
2381 if (auto *T = dyn_cast<SCEVTruncateExpr>(Ops[Idx]))
2382 return T->getOperand()->getType();
2383 if (const auto *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
2384 const auto *LastOp = Mul->getOperand(Mul->getNumOperands() - 1);
2385 if (const auto *T = dyn_cast<SCEVTruncateExpr>(LastOp))
2386 return T->getOperand()->getType();
2387 }
2388 return nullptr;
2389 };
2390 if (auto *SrcType = FindTruncSrcType()) {
2391 SmallVector<const SCEV *, 8> LargeOps;
2392 bool Ok = true;
2393 // Check all the operands to see if they can be represented in the
2394 // source type of the truncate.
2395 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
2396 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Ops[i])) {
2397 if (T->getOperand()->getType() != SrcType) {
2398 Ok = false;
2399 break;
2400 }
2401 LargeOps.push_back(T->getOperand());
2402 } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
2403 LargeOps.push_back(getAnyExtendExpr(C, SrcType));
2404 } else if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Ops[i])) {
2405 SmallVector<const SCEV *, 8> LargeMulOps;
2406 for (unsigned j = 0, f = M->getNumOperands(); j != f && Ok; ++j) {
2407 if (const SCEVTruncateExpr *T =
2408 dyn_cast<SCEVTruncateExpr>(M->getOperand(j))) {
2409 if (T->getOperand()->getType() != SrcType) {
2410 Ok = false;
2411 break;
2412 }
2413 LargeMulOps.push_back(T->getOperand());
2414 } else if (const auto *C = dyn_cast<SCEVConstant>(M->getOperand(j))) {
2415 LargeMulOps.push_back(getAnyExtendExpr(C, SrcType));
2416 } else {
2417 Ok = false;
2418 break;
2419 }
2420 }
2421 if (Ok)
2422 LargeOps.push_back(getMulExpr(LargeMulOps, SCEV::FlagAnyWrap, Depth + 1));
2423 } else {
2424 Ok = false;
2425 break;
2426 }
2427 }
2428 if (Ok) {
2429 // Evaluate the expression in the larger type.
2430 const SCEV *Fold = getAddExpr(LargeOps, SCEV::FlagAnyWrap, Depth + 1);
2431 // If it folds to something simple, use it. Otherwise, don't.
2432 if (isa<SCEVConstant>(Fold) || isa<SCEVUnknown>(Fold))
2433 return getTruncateExpr(Fold, Ty);
2434 }
2435 }
2436
2437 // Skip past any other cast SCEVs.
2438 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddExpr)
2439 ++Idx;
2440
2441 // If there are add operands they would be next.
2442 if (Idx < Ops.size()) {
2443 bool DeletedAdd = false;
2444 while (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[Idx])) {
2445 if (Ops.size() > AddOpsInlineThreshold ||
2446 Add->getNumOperands() > AddOpsInlineThreshold)
2447 break;
2448 // If we have an add, expand the add operands onto the end of the operands
2449 // list.
2450 Ops.erase(Ops.begin()+Idx);
2451 Ops.append(Add->op_begin(), Add->op_end());
2452 DeletedAdd = true;
2453 }
2454
2455 // If we deleted at least one add, we added operands to the end of the list,
2456 // and they are not necessarily sorted. Recurse to resort and resimplify
2457 // any operands we just acquired.
2458 if (DeletedAdd)
2459 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2460 }
2461
2462 // Skip over the add expression until we get to a multiply.
2463 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
2464 ++Idx;
2465
2466 // Check to see if there are any folding opportunities present with
2467 // operands multiplied by constant values.
2468 if (Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx])) {
2469 uint64_t BitWidth = getTypeSizeInBits(Ty);
2470 DenseMap<const SCEV *, APInt> M;
2471 SmallVector<const SCEV *, 8> NewOps;
2472 APInt AccumulatedConstant(BitWidth, 0);
2473 if (CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
2474 Ops.data(), Ops.size(),
2475 APInt(BitWidth, 1), *this)) {
2476 struct APIntCompare {
2477 bool operator()(const APInt &LHS, const APInt &RHS) const {
2478 return LHS.ult(RHS);
2479 }
2480 };
2481
2482 // Some interesting folding opportunity is present, so its worthwhile to
2483 // re-generate the operands list. Group the operands by constant scale,
2484 // to avoid multiplying by the same constant scale multiple times.
2485 std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare> MulOpLists;
2486 for (const SCEV *NewOp : NewOps)
2487 MulOpLists[M.find(NewOp)->second].push_back(NewOp);
2488 // Re-generate the operands list.
2489 Ops.clear();
2490 if (AccumulatedConstant != 0)
2491 Ops.push_back(getConstant(AccumulatedConstant));
2492 for (auto &MulOp : MulOpLists)
2493 if (MulOp.first != 0)
2494 Ops.push_back(getMulExpr(
2495 getConstant(MulOp.first),
2496 getAddExpr(MulOp.second, SCEV::FlagAnyWrap, Depth + 1),
2497 SCEV::FlagAnyWrap, Depth + 1));
2498 if (Ops.empty())
2499 return getZero(Ty);
2500 if (Ops.size() == 1)
2501 return Ops[0];
2502 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2503 }
2504 }
2505
2506 // If we are adding something to a multiply expression, make sure the
2507 // something is not already an operand of the multiply. If so, merge it into
2508 // the multiply.
2509 for (; Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx]); ++Idx) {
2510 const SCEVMulExpr *Mul = cast<SCEVMulExpr>(Ops[Idx]);
2511 for (unsigned MulOp = 0, e = Mul->getNumOperands(); MulOp != e; ++MulOp) {
2512 const SCEV *MulOpSCEV = Mul->getOperand(MulOp);
2513 if (isa<SCEVConstant>(MulOpSCEV))
2514 continue;
2515 for (unsigned AddOp = 0, e = Ops.size(); AddOp != e; ++AddOp)
2516 if (MulOpSCEV == Ops[AddOp]) {
2517 // Fold W + X + (X * Y * Z) --> W + (X * ((Y*Z)+1))
2518 const SCEV *InnerMul = Mul->getOperand(MulOp == 0);
2519 if (Mul->getNumOperands() != 2) {
2520 // If the multiply has more than two operands, we must get the
2521 // Y*Z term.
2522 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2523 Mul->op_begin()+MulOp);
2524 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2525 InnerMul = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2526 }
2527 SmallVector<const SCEV *, 2> TwoOps = {getOne(Ty), InnerMul};
2528 const SCEV *AddOne = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2529 const SCEV *OuterMul = getMulExpr(AddOne, MulOpSCEV,
2530 SCEV::FlagAnyWrap, Depth + 1);
2531 if (Ops.size() == 2) return OuterMul;
2532 if (AddOp < Idx) {
2533 Ops.erase(Ops.begin()+AddOp);
2534 Ops.erase(Ops.begin()+Idx-1);
2535 } else {
2536 Ops.erase(Ops.begin()+Idx);
2537 Ops.erase(Ops.begin()+AddOp-1);
2538 }
2539 Ops.push_back(OuterMul);
2540 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2541 }
2542
2543 // Check this multiply against other multiplies being added together.
2544 for (unsigned OtherMulIdx = Idx+1;
2545 OtherMulIdx < Ops.size() && isa<SCEVMulExpr>(Ops[OtherMulIdx]);
2546 ++OtherMulIdx) {
2547 const SCEVMulExpr *OtherMul = cast<SCEVMulExpr>(Ops[OtherMulIdx]);
2548 // If MulOp occurs in OtherMul, we can fold the two multiplies
2549 // together.
2550 for (unsigned OMulOp = 0, e = OtherMul->getNumOperands();
2551 OMulOp != e; ++OMulOp)
2552 if (OtherMul->getOperand(OMulOp) == MulOpSCEV) {
2553 // Fold X + (A*B*C) + (A*D*E) --> X + (A*(B*C+D*E))
2554 const SCEV *InnerMul1 = Mul->getOperand(MulOp == 0);
2555 if (Mul->getNumOperands() != 2) {
2556 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2557 Mul->op_begin()+MulOp);
2558 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2559 InnerMul1 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2560 }
2561 const SCEV *InnerMul2 = OtherMul->getOperand(OMulOp == 0);
2562 if (OtherMul->getNumOperands() != 2) {
2563 SmallVector<const SCEV *, 4> MulOps(OtherMul->op_begin(),
2564 OtherMul->op_begin()+OMulOp);
2565 MulOps.append(OtherMul->op_begin()+OMulOp+1, OtherMul->op_end());
2566 InnerMul2 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2567 }
2568 SmallVector<const SCEV *, 2> TwoOps = {InnerMul1, InnerMul2};
2569 const SCEV *InnerMulSum =
2570 getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2571 const SCEV *OuterMul = getMulExpr(MulOpSCEV, InnerMulSum,
2572 SCEV::FlagAnyWrap, Depth + 1);
2573 if (Ops.size() == 2) return OuterMul;
2574 Ops.erase(Ops.begin()+Idx);
2575 Ops.erase(Ops.begin()+OtherMulIdx-1);
2576 Ops.push_back(OuterMul);
2577 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2578 }
2579 }
2580 }
2581 }
2582
2583 // If there are any add recurrences in the operands list, see if any other
2584 // added values are loop invariant. If so, we can fold them into the
2585 // recurrence.
2586 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
2587 ++Idx;
2588
2589 // Scan over all recurrences, trying to fold loop invariants into them.
2590 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
2591 // Scan all of the other operands to this add and add them to the vector if
2592 // they are loop invariant w.r.t. the recurrence.
2593 SmallVector<const SCEV *, 8> LIOps;
2594 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
2595 const Loop *AddRecLoop = AddRec->getLoop();
2596 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2597 if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) {
2598 LIOps.push_back(Ops[i]);
2599 Ops.erase(Ops.begin()+i);
2600 --i; --e;
2601 }
2602
2603 // If we found some loop invariants, fold them into the recurrence.
2604 if (!LIOps.empty()) {
2605 // Compute nowrap flags for the addition of the loop-invariant ops and
2606 // the addrec. Temporarily push it as an operand for that purpose.
2607 LIOps.push_back(AddRec);
2608 SCEV::NoWrapFlags Flags = ComputeFlags(LIOps);
2609 LIOps.pop_back();
2610
2611 // NLI + LI + {Start,+,Step} --> NLI + {LI+Start,+,Step}
2612 LIOps.push_back(AddRec->getStart());
2613
2614 SmallVector<const SCEV *, 4> AddRecOps(AddRec->operands());
2615 // This follows from the fact that the no-wrap flags on the outer add
2616 // expression are applicable on the 0th iteration, when the add recurrence
2617 // will be equal to its start value.
2618 AddRecOps[0] = getAddExpr(LIOps, Flags, Depth + 1);
2619
2620 // Build the new addrec. Propagate the NUW and NSW flags if both the
2621 // outer add and the inner addrec are guaranteed to have no overflow.
2622 // Always propagate NW.
2623 Flags = AddRec->getNoWrapFlags(setFlags(Flags, SCEV::FlagNW));
2624 const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop, Flags);
2625
2626 // If all of the other operands were loop invariant, we are done.
2627 if (Ops.size() == 1) return NewRec;
2628
2629 // Otherwise, add the folded AddRec by the non-invariant parts.
2630 for (unsigned i = 0;; ++i)
2631 if (Ops[i] == AddRec) {
2632 Ops[i] = NewRec;
2633 break;
2634 }
2635 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2636 }
2637
2638 // Okay, if there weren't any loop invariants to be folded, check to see if
2639 // there are multiple AddRec's with the same loop induction variable being
2640 // added together. If so, we can fold them.
2641 for (unsigned OtherIdx = Idx+1;
2642 OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2643 ++OtherIdx) {
2644 // We expect the AddRecExpr's to be sorted in reverse dominance order,
2645 // so that the 1st found AddRecExpr is dominated by all others.
2646 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2649, __PRETTY_FUNCTION__))
2647 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2649, __PRETTY_FUNCTION__))
2648 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2649, __PRETTY_FUNCTION__))
2649 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2649, __PRETTY_FUNCTION__))
;
2650 if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) {
2651 // Other + {A,+,B}<L> + {C,+,D}<L> --> Other + {A+C,+,B+D}<L>
2652 SmallVector<const SCEV *, 4> AddRecOps(AddRec->operands());
2653 for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2654 ++OtherIdx) {
2655 const auto *OtherAddRec = cast<SCEVAddRecExpr>(Ops[OtherIdx]);
2656 if (OtherAddRec->getLoop() == AddRecLoop) {
2657 for (unsigned i = 0, e = OtherAddRec->getNumOperands();
2658 i != e; ++i) {
2659 if (i >= AddRecOps.size()) {
2660 AddRecOps.append(OtherAddRec->op_begin()+i,
2661 OtherAddRec->op_end());
2662 break;
2663 }
2664 SmallVector<const SCEV *, 2> TwoOps = {
2665 AddRecOps[i], OtherAddRec->getOperand(i)};
2666 AddRecOps[i] = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2667 }
2668 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
2669 }
2670 }
2671 // Step size has changed, so we cannot guarantee no self-wraparound.
2672 Ops[Idx] = getAddRecExpr(AddRecOps, AddRecLoop, SCEV::FlagAnyWrap);
2673 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2674 }
2675 }
2676
2677 // Otherwise couldn't fold anything into this recurrence. Move onto the
2678 // next one.
2679 }
2680
2681 // Okay, it looks like we really DO need an add expr. Check to see if we
2682 // already have one, otherwise create a new one.
2683 return getOrCreateAddExpr(Ops, ComputeFlags(Ops));
2684}
2685
2686const SCEV *
2687ScalarEvolution::getOrCreateAddExpr(ArrayRef<const SCEV *> Ops,
2688 SCEV::NoWrapFlags Flags) {
2689 FoldingSetNodeID ID;
2690 ID.AddInteger(scAddExpr);
2691 for (const SCEV *Op : Ops)
2692 ID.AddPointer(Op);
2693 void *IP = nullptr;
2694 SCEVAddExpr *S =
2695 static_cast<SCEVAddExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2696 if (!S) {
2697 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2698 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2699 S = new (SCEVAllocator)
2700 SCEVAddExpr(ID.Intern(SCEVAllocator), O, Ops.size());
2701 UniqueSCEVs.InsertNode(S, IP);
2702 addToLoopUseLists(S);
2703 }
2704 S->setNoWrapFlags(Flags);
2705 return S;
2706}
2707
2708const SCEV *
2709ScalarEvolution::getOrCreateAddRecExpr(ArrayRef<const SCEV *> Ops,
2710 const Loop *L, SCEV::NoWrapFlags Flags) {
2711 FoldingSetNodeID ID;
2712 ID.AddInteger(scAddRecExpr);
2713 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2714 ID.AddPointer(Ops[i]);
2715 ID.AddPointer(L);
2716 void *IP = nullptr;
2717 SCEVAddRecExpr *S =
2718 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2719 if (!S) {
2720 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2721 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2722 S = new (SCEVAllocator)
2723 SCEVAddRecExpr(ID.Intern(SCEVAllocator), O, Ops.size(), L);
2724 UniqueSCEVs.InsertNode(S, IP);
2725 addToLoopUseLists(S);
2726 }
2727 setNoWrapFlags(S, Flags);
2728 return S;
2729}
2730
2731const SCEV *
2732ScalarEvolution::getOrCreateMulExpr(ArrayRef<const SCEV *> Ops,
2733 SCEV::NoWrapFlags Flags) {
2734 FoldingSetNodeID ID;
2735 ID.AddInteger(scMulExpr);
2736 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2737 ID.AddPointer(Ops[i]);
2738 void *IP = nullptr;
2739 SCEVMulExpr *S =
2740 static_cast<SCEVMulExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2741 if (!S) {
2742 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2743 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2744 S = new (SCEVAllocator) SCEVMulExpr(ID.Intern(SCEVAllocator),
2745 O, Ops.size());
2746 UniqueSCEVs.InsertNode(S, IP);
2747 addToLoopUseLists(S);
2748 }
2749 S->setNoWrapFlags(Flags);
2750 return S;
2751}
2752
2753static uint64_t umul_ov(uint64_t i, uint64_t j, bool &Overflow) {
2754 uint64_t k = i*j;
2755 if (j > 1 && k / j != i) Overflow = true;
2756 return k;
2757}
2758
2759/// Compute the result of "n choose k", the binomial coefficient. If an
2760/// intermediate computation overflows, Overflow will be set and the return will
2761/// be garbage. Overflow is not cleared on absence of overflow.
2762static uint64_t Choose(uint64_t n, uint64_t k, bool &Overflow) {
2763 // We use the multiplicative formula:
2764 // n(n-1)(n-2)...(n-(k-1)) / k(k-1)(k-2)...1 .
2765 // At each iteration, we take the n-th term of the numeral and divide by the
2766 // (k-n)th term of the denominator. This division will always produce an
2767 // integral result, and helps reduce the chance of overflow in the
2768 // intermediate computations. However, we can still overflow even when the
2769 // final result would fit.
2770
2771 if (n == 0 || n == k) return 1;
2772 if (k > n) return 0;
2773
2774 if (k > n/2)
2775 k = n-k;
2776
2777 uint64_t r = 1;
2778 for (uint64_t i = 1; i <= k; ++i) {
2779 r = umul_ov(r, n-(i-1), Overflow);
2780 r /= i;
2781 }
2782 return r;
2783}
2784
2785/// Determine if any of the operands in this SCEV are a constant or if
2786/// any of the add or multiply expressions in this SCEV contain a constant.
2787static bool containsConstantInAddMulChain(const SCEV *StartExpr) {
2788 struct FindConstantInAddMulChain {
2789 bool FoundConstant = false;
2790
2791 bool follow(const SCEV *S) {
2792 FoundConstant |= isa<SCEVConstant>(S);
2793 return isa<SCEVAddExpr>(S) || isa<SCEVMulExpr>(S);
2794 }
2795
2796 bool isDone() const {
2797 return FoundConstant;
2798 }
2799 };
2800
2801 FindConstantInAddMulChain F;
2802 SCEVTraversal<FindConstantInAddMulChain> ST(F);
2803 ST.visitAll(StartExpr);
2804 return F.FoundConstant;
2805}
2806
2807/// Get a canonical multiply expression, or something simpler if possible.
2808const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
2809 SCEV::NoWrapFlags OrigFlags,
2810 unsigned Depth) {
2811 assert(OrigFlags == maskFlags(OrigFlags, SCEV::FlagNUW | SCEV::FlagNSW) &&((OrigFlags == maskFlags(OrigFlags, SCEV::FlagNUW | SCEV::FlagNSW
) && "only nuw or nsw allowed") ? static_cast<void
> (0) : __assert_fail ("OrigFlags == maskFlags(OrigFlags, SCEV::FlagNUW | SCEV::FlagNSW) && \"only nuw or nsw allowed\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2812, __PRETTY_FUNCTION__))
2812 "only nuw or nsw allowed")((OrigFlags == maskFlags(OrigFlags, SCEV::FlagNUW | SCEV::FlagNSW
) && "only nuw or nsw allowed") ? static_cast<void
> (0) : __assert_fail ("OrigFlags == maskFlags(OrigFlags, SCEV::FlagNUW | SCEV::FlagNSW) && \"only nuw or nsw allowed\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2812, __PRETTY_FUNCTION__))
;
2813 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2813, __PRETTY_FUNCTION__))
;
2814 if (Ops.size() == 1) return Ops[0];
2815#ifndef NDEBUG
2816 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2817 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2818 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2819, __PRETTY_FUNCTION__))
2819 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2819, __PRETTY_FUNCTION__))
;
2820#endif
2821
2822 // Sort by complexity, this groups all similar expression types together.
2823 GroupByComplexity(Ops, &LI, DT);
2824
2825 // If there are any constants, fold them together.
2826 unsigned Idx = 0;
2827 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2828 ++Idx;
2829 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2829, __PRETTY_FUNCTION__))
;
2830 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2831 // We found two constants, fold them together!
2832 Ops[0] = getConstant(LHSC->getAPInt() * RHSC->getAPInt());
2833 if (Ops.size() == 2) return Ops[0];
2834 Ops.erase(Ops.begin()+1); // Erase the folded element
2835 LHSC = cast<SCEVConstant>(Ops[0]);
2836 }
2837
2838 // If we have a multiply of zero, it will always be zero.
2839 if (LHSC->getValue()->isZero())
2840 return LHSC;
2841
2842 // If we are left with a constant one being multiplied, strip it off.
2843 if (LHSC->getValue()->isOne()) {
2844 Ops.erase(Ops.begin());
2845 --Idx;
2846 }
2847
2848 if (Ops.size() == 1)
2849 return Ops[0];
2850 }
2851
2852 // Delay expensive flag strengthening until necessary.
2853 auto ComputeFlags = [this, OrigFlags](const ArrayRef<const SCEV *> Ops) {
2854 return StrengthenNoWrapFlags(this, scMulExpr, Ops, OrigFlags);
2855 };
2856
2857 // Limit recursion calls depth.
2858 if (Depth > MaxArithDepth || hasHugeExpression(Ops))
2859 return getOrCreateMulExpr(Ops, ComputeFlags(Ops));
2860
2861 if (SCEV *S = std::get<0>(findExistingSCEVInCache(scMulExpr, Ops))) {
2862 // Don't strengthen flags if we have no new information.
2863 SCEVMulExpr *Mul = static_cast<SCEVMulExpr *>(S);
2864 if (Mul->getNoWrapFlags(OrigFlags) != OrigFlags)
2865 Mul->setNoWrapFlags(ComputeFlags(Ops));
2866 return S;
2867 }
2868
2869 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2870 if (Ops.size() == 2) {
2871 // C1*(C2+V) -> C1*C2 + C1*V
2872 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1]))
2873 // If any of Add's ops are Adds or Muls with a constant, apply this
2874 // transformation as well.
2875 //
2876 // TODO: There are some cases where this transformation is not
2877 // profitable; for example, Add = (C0 + X) * Y + Z. Maybe the scope of
2878 // this transformation should be narrowed down.
2879 if (Add->getNumOperands() == 2 && containsConstantInAddMulChain(Add))
2880 return getAddExpr(getMulExpr(LHSC, Add->getOperand(0),
2881 SCEV::FlagAnyWrap, Depth + 1),
2882 getMulExpr(LHSC, Add->getOperand(1),
2883 SCEV::FlagAnyWrap, Depth + 1),
2884 SCEV::FlagAnyWrap, Depth + 1);
2885
2886 if (Ops[0]->isAllOnesValue()) {
2887 // If we have a mul by -1 of an add, try distributing the -1 among the
2888 // add operands.
2889 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) {
2890 SmallVector<const SCEV *, 4> NewOps;
2891 bool AnyFolded = false;
2892 for (const SCEV *AddOp : Add->operands()) {
2893 const SCEV *Mul = getMulExpr(Ops[0], AddOp, SCEV::FlagAnyWrap,
2894 Depth + 1);
2895 if (!isa<SCEVMulExpr>(Mul)) AnyFolded = true;
2896 NewOps.push_back(Mul);
2897 }
2898 if (AnyFolded)
2899 return getAddExpr(NewOps, SCEV::FlagAnyWrap, Depth + 1);
2900 } else if (const auto *AddRec = dyn_cast<SCEVAddRecExpr>(Ops[1])) {
2901 // Negation preserves a recurrence's no self-wrap property.
2902 SmallVector<const SCEV *, 4> Operands;
2903 for (const SCEV *AddRecOp : AddRec->operands())
2904 Operands.push_back(getMulExpr(Ops[0], AddRecOp, SCEV::FlagAnyWrap,
2905 Depth + 1));
2906
2907 return getAddRecExpr(Operands, AddRec->getLoop(),
2908 AddRec->getNoWrapFlags(SCEV::FlagNW));
2909 }
2910 }
2911 }
2912 }
2913
2914 // Skip over the add expression until we get to a multiply.
2915 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
2916 ++Idx;
2917
2918 // If there are mul operands inline them all into this expression.
2919 if (Idx < Ops.size()) {
2920 bool DeletedMul = false;
2921 while (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
2922 if (Ops.size() > MulOpsInlineThreshold)
2923 break;
2924 // If we have an mul, expand the mul operands onto the end of the
2925 // operands list.
2926 Ops.erase(Ops.begin()+Idx);
2927 Ops.append(Mul->op_begin(), Mul->op_end());
2928 DeletedMul = true;
2929 }
2930
2931 // If we deleted at least one mul, we added operands to the end of the
2932 // list, and they are not necessarily sorted. Recurse to resort and
2933 // resimplify any operands we just acquired.
2934 if (DeletedMul)
2935 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2936 }
2937
2938 // If there are any add recurrences in the operands list, see if any other
2939 // added values are loop invariant. If so, we can fold them into the
2940 // recurrence.
2941 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
2942 ++Idx;
2943
2944 // Scan over all recurrences, trying to fold loop invariants into them.
2945 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
2946 // Scan all of the other operands to this mul and add them to the vector
2947 // if they are loop invariant w.r.t. the recurrence.
2948 SmallVector<const SCEV *, 8> LIOps;
2949 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
2950 const Loop *AddRecLoop = AddRec->getLoop();
2951 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2952 if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) {
2953 LIOps.push_back(Ops[i]);
2954 Ops.erase(Ops.begin()+i);
2955 --i; --e;
2956 }
2957
2958 // If we found some loop invariants, fold them into the recurrence.
2959 if (!LIOps.empty()) {
2960 // NLI * LI * {Start,+,Step} --> NLI * {LI*Start,+,LI*Step}
2961 SmallVector<const SCEV *, 4> NewOps;
2962 NewOps.reserve(AddRec->getNumOperands());
2963 const SCEV *Scale = getMulExpr(LIOps, SCEV::FlagAnyWrap, Depth + 1);
2964 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i)
2965 NewOps.push_back(getMulExpr(Scale, AddRec->getOperand(i),
2966 SCEV::FlagAnyWrap, Depth + 1));
2967
2968 // Build the new addrec. Propagate the NUW and NSW flags if both the
2969 // outer mul and the inner addrec are guaranteed to have no overflow.
2970 //
2971 // No self-wrap cannot be guaranteed after changing the step size, but
2972 // will be inferred if either NUW or NSW is true.
2973 SCEV::NoWrapFlags Flags = ComputeFlags({Scale, AddRec});
2974 const SCEV *NewRec = getAddRecExpr(
2975 NewOps, AddRecLoop, AddRec->getNoWrapFlags(Flags));
2976
2977 // If all of the other operands were loop invariant, we are done.
2978 if (Ops.size() == 1) return NewRec;
2979
2980 // Otherwise, multiply the folded AddRec by the non-invariant parts.
2981 for (unsigned i = 0;; ++i)
2982 if (Ops[i] == AddRec) {
2983 Ops[i] = NewRec;
2984 break;
2985 }
2986 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2987 }
2988
2989 // Okay, if there weren't any loop invariants to be folded, check to see
2990 // if there are multiple AddRec's with the same loop induction variable
2991 // being multiplied together. If so, we can fold them.
2992
2993 // {A1,+,A2,+,...,+,An}<L> * {B1,+,B2,+,...,+,Bn}<L>
2994 // = {x=1 in [ sum y=x..2x [ sum z=max(y-x, y-n)..min(x,n) [
2995 // choose(x, 2x)*choose(2x-y, x-z)*A_{y-z}*B_z
2996 // ]]],+,...up to x=2n}.
2997 // Note that the arguments to choose() are always integers with values
2998 // known at compile time, never SCEV objects.
2999 //
3000 // The implementation avoids pointless extra computations when the two
3001 // addrec's are of different length (mathematically, it's equivalent to
3002 // an infinite stream of zeros on the right).
3003 bool OpsModified = false;
3004 for (unsigned OtherIdx = Idx+1;
3005 OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
3006 ++OtherIdx) {
3007 const SCEVAddRecExpr *OtherAddRec =
3008 dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]);
3009 if (!OtherAddRec || OtherAddRec->getLoop() != AddRecLoop)
3010 continue;
3011
3012 // Limit max number of arguments to avoid creation of unreasonably big
3013 // SCEVAddRecs with very complex operands.
3014 if (AddRec->getNumOperands() + OtherAddRec->getNumOperands() - 1 >
3015 MaxAddRecSize || hasHugeExpression({AddRec, OtherAddRec}))
3016 continue;
3017
3018 bool Overflow = false;
3019 Type *Ty = AddRec->getType();
3020 bool LargerThan64Bits = getTypeSizeInBits(Ty) > 64;
3021 SmallVector<const SCEV*, 7> AddRecOps;
3022 for (int x = 0, xe = AddRec->getNumOperands() +
3023 OtherAddRec->getNumOperands() - 1; x != xe && !Overflow; ++x) {
3024 SmallVector <const SCEV *, 7> SumOps;
3025 for (int y = x, ye = 2*x+1; y != ye && !Overflow; ++y) {
3026 uint64_t Coeff1 = Choose(x, 2*x - y, Overflow);
3027 for (int z = std::max(y-x, y-(int)AddRec->getNumOperands()+1),
3028 ze = std::min(x+1, (int)OtherAddRec->getNumOperands());
3029 z < ze && !Overflow; ++z) {
3030 uint64_t Coeff2 = Choose(2*x - y, x-z, Overflow);
3031 uint64_t Coeff;
3032 if (LargerThan64Bits)
3033 Coeff = umul_ov(Coeff1, Coeff2, Overflow);
3034 else
3035 Coeff = Coeff1*Coeff2;
3036 const SCEV *CoeffTerm = getConstant(Ty, Coeff);
3037 const SCEV *Term1 = AddRec->getOperand(y-z);
3038 const SCEV *Term2 = OtherAddRec->getOperand(z);
3039 SumOps.push_back(getMulExpr(CoeffTerm, Term1, Term2,
3040 SCEV::FlagAnyWrap, Depth + 1));
3041 }
3042 }
3043 if (SumOps.empty())
3044 SumOps.push_back(getZero(Ty));
3045 AddRecOps.push_back(getAddExpr(SumOps, SCEV::FlagAnyWrap, Depth + 1));
3046 }
3047 if (!Overflow) {
3048 const SCEV *NewAddRec = getAddRecExpr(AddRecOps, AddRecLoop,
3049 SCEV::FlagAnyWrap);
3050 if (Ops.size() == 2) return NewAddRec;
3051 Ops[Idx] = NewAddRec;
3052 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
3053 OpsModified = true;
3054 AddRec = dyn_cast<SCEVAddRecExpr>(NewAddRec);
3055 if (!AddRec)
3056 break;
3057 }
3058 }
3059 if (OpsModified)
3060 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
3061
3062 // Otherwise couldn't fold anything into this recurrence. Move onto the
3063 // next one.
3064 }
3065
3066 // Okay, it looks like we really DO need an mul expr. Check to see if we
3067 // already have one, otherwise create a new one.
3068 return getOrCreateMulExpr(Ops, ComputeFlags(Ops));
3069}
3070
3071/// Represents an unsigned remainder expression based on unsigned division.
3072const SCEV *ScalarEvolution::getURemExpr(const SCEV *LHS,
3073 const SCEV *RHS) {
3074 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3076, __PRETTY_FUNCTION__))
3075 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3076, __PRETTY_FUNCTION__))
3076 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3076, __PRETTY_FUNCTION__))
;
3077
3078 // Short-circuit easy cases
3079 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
3080 // If constant is one, the result is trivial
3081 if (RHSC->getValue()->isOne())
3082 return getZero(LHS->getType()); // X urem 1 --> 0
3083
3084 // If constant is a power of two, fold into a zext(trunc(LHS)).
3085 if (RHSC->getAPInt().isPowerOf2()) {
3086 Type *FullTy = LHS->getType();
3087 Type *TruncTy =
3088 IntegerType::get(getContext(), RHSC->getAPInt().logBase2());
3089 return getZeroExtendExpr(getTruncateExpr(LHS, TruncTy), FullTy);
3090 }
3091 }
3092
3093 // Fallback to %a == %x urem %y == %x -<nuw> ((%x udiv %y) *<nuw> %y)
3094 const SCEV *UDiv = getUDivExpr(LHS, RHS);
3095 const SCEV *Mult = getMulExpr(UDiv, RHS, SCEV::FlagNUW);
3096 return getMinusSCEV(LHS, Mult, SCEV::FlagNUW);
3097}
3098
3099/// Get a canonical unsigned division expression, or something simpler if
3100/// possible.
3101const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS,
3102 const SCEV *RHS) {
3103 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3105, __PRETTY_FUNCTION__))
3104 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3105, __PRETTY_FUNCTION__))
3105 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3105, __PRETTY_FUNCTION__))
;
3106
3107 FoldingSetNodeID ID;
3108 ID.AddInteger(scUDivExpr);
3109 ID.AddPointer(LHS);
3110 ID.AddPointer(RHS);
3111 void *IP = nullptr;
3112 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
3113 return S;
3114
3115 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
3116 if (RHSC->getValue()->isOne())
3117 return LHS; // X udiv 1 --> x
3118 // If the denominator is zero, the result of the udiv is undefined. Don't
3119 // try to analyze it, because the resolution chosen here may differ from
3120 // the resolution chosen in other parts of the compiler.
3121 if (!RHSC->getValue()->isZero()) {
3122 // Determine if the division can be folded into the operands of
3123 // its operands.
3124 // TODO: Generalize this to non-constants by using known-bits information.
3125 Type *Ty = LHS->getType();
3126 unsigned LZ = RHSC->getAPInt().countLeadingZeros();
3127 unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ - 1;
3128 // For non-power-of-two values, effectively round the value up to the
3129 // nearest power of two.
3130 if (!RHSC->getAPInt().isPowerOf2())
3131 ++MaxShiftAmt;
3132 IntegerType *ExtTy =
3133 IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt);
3134 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS))
3135 if (const SCEVConstant *Step =
3136 dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this))) {
3137 // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded.
3138 const APInt &StepInt = Step->getAPInt();
3139 const APInt &DivInt = RHSC->getAPInt();
3140 if (!StepInt.urem(DivInt) &&
3141 getZeroExtendExpr(AR, ExtTy) ==
3142 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
3143 getZeroExtendExpr(Step, ExtTy),
3144 AR->getLoop(), SCEV::FlagAnyWrap)) {
3145 SmallVector<const SCEV *, 4> Operands;
3146 for (const SCEV *Op : AR->operands())
3147 Operands.push_back(getUDivExpr(Op, RHS));
3148 return getAddRecExpr(Operands, AR->getLoop(), SCEV::FlagNW);
3149 }
3150 /// Get a canonical UDivExpr for a recurrence.
3151 /// {X,+,N}/C => {Y,+,N}/C where Y=X-(X%N). Safe when C%N=0.
3152 // We can currently only fold X%N if X is constant.
3153 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(AR->getStart());
3154 if (StartC && !DivInt.urem(StepInt) &&
3155 getZeroExtendExpr(AR, ExtTy) ==
3156 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
3157 getZeroExtendExpr(Step, ExtTy),
3158 AR->getLoop(), SCEV::FlagAnyWrap)) {
3159 const APInt &StartInt = StartC->getAPInt();
3160 const APInt &StartRem = StartInt.urem(StepInt);
3161 if (StartRem != 0) {
3162 const SCEV *NewLHS =
3163 getAddRecExpr(getConstant(StartInt - StartRem), Step,
3164 AR->getLoop(), SCEV::FlagNW);
3165 if (LHS != NewLHS) {
3166 LHS = NewLHS;
3167
3168 // Reset the ID to include the new LHS, and check if it is
3169 // already cached.
3170 ID.clear();
3171 ID.AddInteger(scUDivExpr);
3172 ID.AddPointer(LHS);
3173 ID.AddPointer(RHS);
3174 IP = nullptr;
3175 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
3176 return S;
3177 }
3178 }
3179 }
3180 }
3181 // (A*B)/C --> A*(B/C) if safe and B/C can be folded.
3182 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) {
3183 SmallVector<const SCEV *, 4> Operands;
3184 for (const SCEV *Op : M->operands())
3185 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
3186 if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands))
3187 // Find an operand that's safely divisible.
3188 for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) {
3189 const SCEV *Op = M->getOperand(i);
3190 const SCEV *Div = getUDivExpr(Op, RHSC);
3191 if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) {
3192 Operands = SmallVector<const SCEV *, 4>(M->operands());
3193 Operands[i] = Div;
3194 return getMulExpr(Operands);
3195 }
3196 }
3197 }
3198
3199 // (A/B)/C --> A/(B*C) if safe and B*C can be folded.
3200 if (const SCEVUDivExpr *OtherDiv = dyn_cast<SCEVUDivExpr>(LHS)) {
3201 if (auto *DivisorConstant =
3202 dyn_cast<SCEVConstant>(OtherDiv->getRHS())) {
3203 bool Overflow = false;
3204 APInt NewRHS =
3205 DivisorConstant->getAPInt().umul_ov(RHSC->getAPInt(), Overflow);
3206 if (Overflow) {
3207 return getConstant(RHSC->getType(), 0, false);
3208 }
3209 return getUDivExpr(OtherDiv->getLHS(), getConstant(NewRHS));
3210 }
3211 }
3212
3213 // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded.
3214 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(LHS)) {
3215 SmallVector<const SCEV *, 4> Operands;
3216 for (const SCEV *Op : A->operands())
3217 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
3218 if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) {
3219 Operands.clear();
3220 for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) {
3221 const SCEV *Op = getUDivExpr(A->getOperand(i), RHS);
3222 if (isa<SCEVUDivExpr>(Op) ||
3223 getMulExpr(Op, RHS) != A->getOperand(i))
3224 break;
3225 Operands.push_back(Op);
3226 }
3227 if (Operands.size() == A->getNumOperands())
3228 return getAddExpr(Operands);
3229 }
3230 }
3231
3232 // Fold if both operands are constant.
3233 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
3234 Constant *LHSCV = LHSC->getValue();
3235 Constant *RHSCV = RHSC->getValue();
3236 return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV,
3237 RHSCV)));
3238 }
3239 }
3240 }
3241
3242 // The Insertion Point (IP) might be invalid by now (due to UniqueSCEVs
3243 // changes). Make sure we get a new one.
3244 IP = nullptr;
3245 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
3246 SCEV *S = new (SCEVAllocator) SCEVUDivExpr(ID.Intern(SCEVAllocator),
3247 LHS, RHS);
3248 UniqueSCEVs.InsertNode(S, IP);
3249 addToLoopUseLists(S);
3250 return S;
3251}
3252
3253static const APInt gcd(const SCEVConstant *C1, const SCEVConstant *C2) {
3254 APInt A = C1->getAPInt().abs();
3255 APInt B = C2->getAPInt().abs();
3256 uint32_t ABW = A.getBitWidth();
3257 uint32_t BBW = B.getBitWidth();
3258
3259 if (ABW > BBW)
3260 B = B.zext(ABW);
3261 else if (ABW < BBW)
3262 A = A.zext(BBW);
3263
3264 return APIntOps::GreatestCommonDivisor(std::move(A), std::move(B));
3265}
3266
3267/// Get a canonical unsigned division expression, or something simpler if
3268/// possible. There is no representation for an exact udiv in SCEV IR, but we
3269/// can attempt to remove factors from the LHS and RHS. We can't do this when
3270/// it's not exact because the udiv may be clearing bits.
3271const SCEV *ScalarEvolution::getUDivExactExpr(const SCEV *LHS,
3272 const SCEV *RHS) {
3273 // TODO: we could try to find factors in all sorts of things, but for now we
3274 // just deal with u/exact (multiply, constant). See SCEVDivision towards the
3275 // end of this file for inspiration.
3276
3277 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS);
3278 if (!Mul || !Mul->hasNoUnsignedWrap())
3279 return getUDivExpr(LHS, RHS);
3280
3281 if (const SCEVConstant *RHSCst = dyn_cast<SCEVConstant>(RHS)) {
3282 // If the mulexpr multiplies by a constant, then that constant must be the
3283 // first element of the mulexpr.
3284 if (const auto *LHSCst = dyn_cast<SCEVConstant>(Mul->getOperand(0))) {
3285 if (LHSCst == RHSCst) {
3286 SmallVector<const SCEV *, 2> Operands(drop_begin(Mul->operands()));
3287 return getMulExpr(Operands);
3288 }
3289
3290 // We can't just assume that LHSCst divides RHSCst cleanly, it could be
3291 // that there's a factor provided by one of the other terms. We need to
3292 // check.
3293 APInt Factor = gcd(LHSCst, RHSCst);
3294 if (!Factor.isIntN(1)) {
3295 LHSCst =
3296 cast<SCEVConstant>(getConstant(LHSCst->getAPInt().udiv(Factor)));
3297 RHSCst =
3298 cast<SCEVConstant>(getConstant(RHSCst->getAPInt().udiv(Factor)));
3299 SmallVector<const SCEV *, 2> Operands;
3300 Operands.push_back(LHSCst);
3301 Operands.append(Mul->op_begin() + 1, Mul->op_end());
3302 LHS = getMulExpr(Operands);
3303 RHS = RHSCst;
3304 Mul = dyn_cast<SCEVMulExpr>(LHS);
3305 if (!Mul)
3306 return getUDivExactExpr(LHS, RHS);
3307 }
3308 }
3309 }
3310
3311 for (int i = 0, e = Mul->getNumOperands(); i != e; ++i) {
3312 if (Mul->getOperand(i) == RHS) {
3313 SmallVector<const SCEV *, 2> Operands;
3314 Operands.append(Mul->op_begin(), Mul->op_begin() + i);
3315 Operands.append(Mul->op_begin() + i + 1, Mul->op_end());
3316 return getMulExpr(Operands);
3317 }
3318 }
3319
3320 return getUDivExpr(LHS, RHS);
3321}
3322
3323/// Get an add recurrence expression for the specified loop. Simplify the
3324/// expression as much as possible.
3325const SCEV *ScalarEvolution::getAddRecExpr(const SCEV *Start, const SCEV *Step,
3326 const Loop *L,
3327 SCEV::NoWrapFlags Flags) {
3328 SmallVector<const SCEV *, 4> Operands;
3329 Operands.push_back(Start);
3330 if (const SCEVAddRecExpr *StepChrec = dyn_cast<SCEVAddRecExpr>(Step))
3331 if (StepChrec->getLoop() == L) {
3332 Operands.append(StepChrec->op_begin(), StepChrec->op_end());
3333 return getAddRecExpr(Operands, L, maskFlags(Flags, SCEV::FlagNW));
3334 }
3335
3336 Operands.push_back(Step);
3337 return getAddRecExpr(Operands, L, Flags);
3338}
3339
3340/// Get an add recurrence expression for the specified loop. Simplify the
3341/// expression as much as possible.
3342const SCEV *
3343ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
3344 const Loop *L, SCEV::NoWrapFlags Flags) {
3345 if (Operands.size() == 1) return Operands[0];
3346#ifndef NDEBUG
3347 Type *ETy = getEffectiveSCEVType(Operands[0]->getType());
3348 for (unsigned i = 1, e = Operands.size(); i != e; ++i)
3349 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3350, __PRETTY_FUNCTION__))
3350 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3350, __PRETTY_FUNCTION__))
;
3351 for (unsigned i = 0, e = Operands.size(); i != e; ++i)
3352 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3353, __PRETTY_FUNCTION__))
3353 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3353, __PRETTY_FUNCTION__))
;
3354#endif
3355
3356 if (Operands.back()->isZero()) {
3357 Operands.pop_back();
3358 return getAddRecExpr(Operands, L, SCEV::FlagAnyWrap); // {X,+,0} --> X
3359 }
3360
3361 // It's tempting to want to call getConstantMaxBackedgeTakenCount count here and
3362 // use that information to infer NUW and NSW flags. However, computing a
3363 // BE count requires calling getAddRecExpr, so we may not yet have a
3364 // meaningful BE count at this point (and if we don't, we'd be stuck
3365 // with a SCEVCouldNotCompute as the cached BE count).
3366
3367 Flags = StrengthenNoWrapFlags(this, scAddRecExpr, Operands, Flags);
3368
3369 // Canonicalize nested AddRecs in by nesting them in order of loop depth.
3370 if (const SCEVAddRecExpr *NestedAR = dyn_cast<SCEVAddRecExpr>(Operands[0])) {
3371 const Loop *NestedLoop = NestedAR->getLoop();
3372 if (L->contains(NestedLoop)
3373 ? (L->getLoopDepth() < NestedLoop->getLoopDepth())
3374 : (!NestedLoop->contains(L) &&
3375 DT.dominates(L->getHeader(), NestedLoop->getHeader()))) {
3376 SmallVector<const SCEV *, 4> NestedOperands(NestedAR->operands());
3377 Operands[0] = NestedAR->getStart();
3378 // AddRecs require their operands be loop-invariant with respect to their
3379 // loops. Don't perform this transformation if it would break this
3380 // requirement.
3381 bool AllInvariant = all_of(
3382 Operands, [&](const SCEV *Op) { return isLoopInvariant(Op, L); });
3383
3384 if (AllInvariant) {
3385 // Create a recurrence for the outer loop with the same step size.
3386 //
3387 // The outer recurrence keeps its NW flag but only keeps NUW/NSW if the
3388 // inner recurrence has the same property.
3389 SCEV::NoWrapFlags OuterFlags =
3390 maskFlags(Flags, SCEV::FlagNW | NestedAR->getNoWrapFlags());
3391
3392 NestedOperands[0] = getAddRecExpr(Operands, L, OuterFlags);
3393 AllInvariant = all_of(NestedOperands, [&](const SCEV *Op) {
3394 return isLoopInvariant(Op, NestedLoop);
3395 });
3396
3397 if (AllInvariant) {
3398 // Ok, both add recurrences are valid after the transformation.
3399 //
3400 // The inner recurrence keeps its NW flag but only keeps NUW/NSW if
3401 // the outer recurrence has the same property.
3402 SCEV::NoWrapFlags InnerFlags =
3403 maskFlags(NestedAR->getNoWrapFlags(), SCEV::FlagNW | Flags);
3404 return getAddRecExpr(NestedOperands, NestedLoop, InnerFlags);
3405 }
3406 }
3407 // Reset Operands to its original state.
3408 Operands[0] = NestedAR;
3409 }
3410 }
3411
3412 // Okay, it looks like we really DO need an addrec expr. Check to see if we
3413 // already have one, otherwise create a new one.
3414 return getOrCreateAddRecExpr(Operands, L, Flags);
3415}
3416
3417const SCEV *
3418ScalarEvolution::getGEPExpr(GEPOperator *GEP,
3419 const SmallVectorImpl<const SCEV *> &IndexExprs) {
3420 const SCEV *BaseExpr = getSCEV(GEP->getPointerOperand());
3421 // getSCEV(Base)->getType() has the same address space as Base->getType()
3422 // because SCEV::getType() preserves the address space.
3423 Type *IntIdxTy = getEffectiveSCEVType(BaseExpr->getType());
3424 // FIXME(PR23527): Don't blindly transfer the inbounds flag from the GEP
3425 // instruction to its SCEV, because the Instruction may be guarded by control
3426 // flow and the no-overflow bits may not be valid for the expression in any
3427 // context. This can be fixed similarly to how these flags are handled for
3428 // adds.
3429 SCEV::NoWrapFlags OffsetWrap =
3430 GEP->isInBounds() ? SCEV::FlagNSW : SCEV::FlagAnyWrap;
3431
3432 Type *CurTy = GEP->getType();
3433 bool FirstIter = true;
3434 SmallVector<const SCEV *, 4> Offsets;
3435 for (const SCEV *IndexExpr : IndexExprs) {
3436 // Compute the (potentially symbolic) offset in bytes for this index.
3437 if (StructType *STy = dyn_cast<StructType>(CurTy)) {
3438 // For a struct, add the member offset.
3439 ConstantInt *Index = cast<SCEVConstant>(IndexExpr)->getValue();
3440 unsigned FieldNo = Index->getZExtValue();
3441 const SCEV *FieldOffset = getOffsetOfExpr(IntIdxTy, STy, FieldNo);
3442 Offsets.push_back(FieldOffset);
3443
3444 // Update CurTy to the type of the field at Index.
3445 CurTy = STy->getTypeAtIndex(Index);
3446 } else {
3447 // Update CurTy to its element type.
3448 if (FirstIter) {
3449 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3450, __PRETTY_FUNCTION__))
3450 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3450, __PRETTY_FUNCTION__))
;
3451 CurTy = GEP->getSourceElementType();
3452 FirstIter = false;
3453 } else {
3454 CurTy = GetElementPtrInst::getTypeAtIndex(CurTy, (uint64_t)0);
3455 }
3456 // For an array, add the element offset, explicitly scaled.
3457 const SCEV *ElementSize = getSizeOfExpr(IntIdxTy, CurTy);
3458 // Getelementptr indices are signed.
3459 IndexExpr = getTruncateOrSignExtend(IndexExpr, IntIdxTy);
3460
3461 // Multiply the index by the element size to compute the element offset.
3462 const SCEV *LocalOffset = getMulExpr(IndexExpr, ElementSize, OffsetWrap);
3463 Offsets.push_back(LocalOffset);
3464 }
3465 }
3466
3467 // Handle degenerate case of GEP without offsets.
3468 if (Offsets.empty())
3469 return BaseExpr;
3470
3471 // Add the offsets together, assuming nsw if inbounds.
3472 const SCEV *Offset = getAddExpr(Offsets, OffsetWrap);
3473 // Add the base address and the offset. We cannot use the nsw flag, as the
3474 // base address is unsigned. However, if we know that the offset is
3475 // non-negative, we can use nuw.
3476 SCEV::NoWrapFlags BaseWrap = GEP->isInBounds() && isKnownNonNegative(Offset)
3477 ? SCEV::FlagNUW : SCEV::FlagAnyWrap;
3478 return getAddExpr(BaseExpr, Offset, BaseWrap);
3479}
3480
3481std::tuple<SCEV *, FoldingSetNodeID, void *>
3482ScalarEvolution::findExistingSCEVInCache(SCEVTypes SCEVType,
3483 ArrayRef<const SCEV *> Ops) {
3484 FoldingSetNodeID ID;
3485 void *IP = nullptr;
3486 ID.AddInteger(SCEVType);
3487 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3488 ID.AddPointer(Ops[i]);
3489 return std::tuple<SCEV *, FoldingSetNodeID, void *>(
3490 UniqueSCEVs.FindNodeOrInsertPos(ID, IP), std::move(ID), IP);
3491}
3492
3493const SCEV *ScalarEvolution::getAbsExpr(const SCEV *Op, bool IsNSW) {
3494 SCEV::NoWrapFlags Flags = IsNSW ? SCEV::FlagNSW : SCEV::FlagAnyWrap;
3495 return getSMaxExpr(Op, getNegativeSCEV(Op, Flags));
3496}
3497
3498const SCEV *ScalarEvolution::getSignumExpr(const SCEV *Op) {
3499 Type *Ty = Op->getType();
3500 return getSMinExpr(getSMaxExpr(Op, getMinusOne(Ty)), getOne(Ty));
3501}
3502
3503const SCEV *ScalarEvolution::getMinMaxExpr(SCEVTypes Kind,
3504 SmallVectorImpl<const SCEV *> &Ops) {
3505 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3505, __PRETTY_FUNCTION__))
;
3506 if (Ops.size() == 1) return Ops[0];
3507#ifndef NDEBUG
3508 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
3509 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
3510 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3511, __PRETTY_FUNCTION__))
3511 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3511, __PRETTY_FUNCTION__))
;
3512#endif
3513
3514 bool IsSigned = Kind == scSMaxExpr || Kind == scSMinExpr;
3515 bool IsMax = Kind == scSMaxExpr || Kind == scUMaxExpr;
3516
3517 // Sort by complexity, this groups all similar expression types together.
3518 GroupByComplexity(Ops, &LI, DT);
3519
3520 // Check if we have created the same expression before.
3521 if (const SCEV *S = std::get<0>(findExistingSCEVInCache(Kind, Ops))) {
3522 return S;
3523 }
3524
3525 // If there are any constants, fold them together.
3526 unsigned Idx = 0;
3527 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
3528 ++Idx;
3529 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3529, __PRETTY_FUNCTION__))
;
3530 auto FoldOp = [&](const APInt &LHS, const APInt &RHS) {
3531 if (Kind == scSMaxExpr)
3532 return APIntOps::smax(LHS, RHS);
3533 else if (Kind == scSMinExpr)
3534 return APIntOps::smin(LHS, RHS);
3535 else if (Kind == scUMaxExpr)
3536 return APIntOps::umax(LHS, RHS);
3537 else if (Kind == scUMinExpr)
3538 return APIntOps::umin(LHS, RHS);
3539 llvm_unreachable("Unknown SCEV min/max opcode")::llvm::llvm_unreachable_internal("Unknown SCEV min/max opcode"
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3539)
;
3540 };
3541
3542 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
3543 // We found two constants, fold them together!
3544 ConstantInt *Fold = ConstantInt::get(
3545 getContext(), FoldOp(LHSC->getAPInt(), RHSC->getAPInt()));
3546 Ops[0] = getConstant(Fold);
3547 Ops.erase(Ops.begin()+1); // Erase the folded element
3548 if (Ops.size() == 1) return Ops[0];
3549 LHSC = cast<SCEVConstant>(Ops[0]);
3550 }
3551
3552 bool IsMinV = LHSC->getValue()->isMinValue(IsSigned);
3553 bool IsMaxV = LHSC->getValue()->isMaxValue(IsSigned);
3554
3555 if (IsMax ? IsMinV : IsMaxV) {
3556 // If we are left with a constant minimum(/maximum)-int, strip it off.
3557 Ops.erase(Ops.begin());
3558 --Idx;
3559 } else if (IsMax ? IsMaxV : IsMinV) {
3560 // If we have a max(/min) with a constant maximum(/minimum)-int,
3561 // it will always be the extremum.
3562 return LHSC;
3563 }
3564
3565 if (Ops.size() == 1) return Ops[0];
3566 }
3567
3568 // Find the first operation of the same kind
3569 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < Kind)
3570 ++Idx;
3571
3572 // Check to see if one of the operands is of the same kind. If so, expand its
3573 // operands onto our operand list, and recurse to simplify.
3574 if (Idx < Ops.size()) {
3575 bool DeletedAny = false;
3576 while (Ops[Idx]->getSCEVType() == Kind) {
3577 const SCEVMinMaxExpr *SMME = cast<SCEVMinMaxExpr>(Ops[Idx]);
3578 Ops.erase(Ops.begin()+Idx);
3579 Ops.append(SMME->op_begin(), SMME->op_end());
3580 DeletedAny = true;
3581 }
3582
3583 if (DeletedAny)
3584 return getMinMaxExpr(Kind, Ops);
3585 }
3586
3587 // Okay, check to see if the same value occurs in the operand list twice. If
3588 // so, delete one. Since we sorted the list, these values are required to
3589 // be adjacent.
3590 llvm::CmpInst::Predicate GEPred =
3591 IsSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
3592 llvm::CmpInst::Predicate LEPred =
3593 IsSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
3594 llvm::CmpInst::Predicate FirstPred = IsMax ? GEPred : LEPred;
3595 llvm::CmpInst::Predicate SecondPred = IsMax ? LEPred : GEPred;
3596 for (unsigned i = 0, e = Ops.size() - 1; i != e; ++i) {
3597 if (Ops[i] == Ops[i + 1] ||
3598 isKnownViaNonRecursiveReasoning(FirstPred, Ops[i], Ops[i + 1])) {
3599 // X op Y op Y --> X op Y
3600 // X op Y --> X, if we know X, Y are ordered appropriately
3601 Ops.erase(Ops.begin() + i + 1, Ops.begin() + i + 2);
3602 --i;
3603 --e;
3604 } else if (isKnownViaNonRecursiveReasoning(SecondPred, Ops[i],
3605 Ops[i + 1])) {
3606 // X op Y --> Y, if we know X, Y are ordered appropriately
3607 Ops.erase(Ops.begin() + i, Ops.begin() + i + 1);
3608 --i;
3609 --e;
3610 }
3611 }
3612
3613 if (Ops.size() == 1) return Ops[0];
3614
3615 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3615, __PRETTY_FUNCTION__))
;
3616
3617 // Okay, it looks like we really DO need an expr. Check to see if we
3618 // already have one, otherwise create a new one.
3619 const SCEV *ExistingSCEV;
3620 FoldingSetNodeID ID;
3621 void *IP;
3622 std::tie(ExistingSCEV, ID, IP) = findExistingSCEVInCache(Kind, Ops);
3623 if (ExistingSCEV)
3624 return ExistingSCEV;
3625 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
3626 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
3627 SCEV *S = new (SCEVAllocator)
3628 SCEVMinMaxExpr(ID.Intern(SCEVAllocator), Kind, O, Ops.size());
3629
3630 UniqueSCEVs.InsertNode(S, IP);
3631 addToLoopUseLists(S);
3632 return S;
3633}
3634
3635const SCEV *ScalarEvolution::getSMaxExpr(const SCEV *LHS, const SCEV *RHS) {
3636 SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
3637 return getSMaxExpr(Ops);
3638}
3639
3640const SCEV *ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3641 return getMinMaxExpr(scSMaxExpr, Ops);
3642}
3643
3644const SCEV *ScalarEvolution::getUMaxExpr(const SCEV *LHS, const SCEV *RHS) {
3645 SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
3646 return getUMaxExpr(Ops);
3647}
3648
3649const SCEV *ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3650 return getMinMaxExpr(scUMaxExpr, Ops);
3651}
3652
3653const SCEV *ScalarEvolution::getSMinExpr(const SCEV *LHS,
3654 const SCEV *RHS) {
3655 SmallVector<const SCEV *, 2> Ops = { LHS, RHS };
3656 return getSMinExpr(Ops);
3657}
3658
3659const SCEV *ScalarEvolution::getSMinExpr(SmallVectorImpl<const SCEV *> &Ops) {
3660 return getMinMaxExpr(scSMinExpr, Ops);
3661}
3662
3663const SCEV *ScalarEvolution::getUMinExpr(const SCEV *LHS,
3664 const SCEV *RHS) {
3665 SmallVector<const SCEV *, 2> Ops = { LHS, RHS };
3666 return getUMinExpr(Ops);
3667}
3668
3669const SCEV *ScalarEvolution::getUMinExpr(SmallVectorImpl<const SCEV *> &Ops) {
3670 return getMinMaxExpr(scUMinExpr, Ops);
3671}
3672
3673const SCEV *
3674ScalarEvolution::getSizeOfScalableVectorExpr(Type *IntTy,
3675 ScalableVectorType *ScalableTy) {
3676 Constant *NullPtr = Constant::getNullValue(ScalableTy->getPointerTo());
3677 Constant *One = ConstantInt::get(IntTy, 1);
3678 Constant *GEP = ConstantExpr::getGetElementPtr(ScalableTy, NullPtr, One);
3679 // Note that the expression we created is the final expression, we don't
3680 // want to simplify it any further Also, if we call a normal getSCEV(),
3681 // we'll end up in an endless recursion. So just create an SCEVUnknown.
3682 return getUnknown(ConstantExpr::getPtrToInt(GEP, IntTy));
3683}
3684
3685const SCEV *ScalarEvolution::getSizeOfExpr(Type *IntTy, Type *AllocTy) {
3686 if (auto *ScalableAllocTy = dyn_cast<ScalableVectorType>(AllocTy))
3687 return getSizeOfScalableVectorExpr(IntTy, ScalableAllocTy);
3688 // We can bypass creating a target-independent constant expression and then
3689 // folding it back into a ConstantInt. This is just a compile-time
3690 // optimization.
3691 return getConstant(IntTy, getDataLayout().getTypeAllocSize(AllocTy));
3692}
3693
3694const SCEV *ScalarEvolution::getStoreSizeOfExpr(Type *IntTy, Type *StoreTy) {
3695 if (auto *ScalableStoreTy = dyn_cast<ScalableVectorType>(StoreTy))
3696 return getSizeOfScalableVectorExpr(IntTy, ScalableStoreTy);
3697 // We can bypass creating a target-independent constant expression and then
3698 // folding it back into a ConstantInt. This is just a compile-time
3699 // optimization.
3700 return getConstant(IntTy, getDataLayout().getTypeStoreSize(StoreTy));
3701}
3702
3703const SCEV *ScalarEvolution::getOffsetOfExpr(Type *IntTy,
3704 StructType *STy,
3705 unsigned FieldNo) {
3706 // We can bypass creating a target-independent constant expression and then
3707 // folding it back into a ConstantInt. This is just a compile-time
3708 // optimization.
3709 return getConstant(
3710 IntTy, getDataLayout().getStructLayout(STy)->getElementOffset(FieldNo));
3711}
3712
3713const SCEV *ScalarEvolution::getUnknown(Value *V) {
3714 // Don't attempt to do anything other than create a SCEVUnknown object
3715 // here. createSCEV only calls getUnknown after checking for all other
3716 // interesting possibilities, and any other code that calls getUnknown
3717 // is doing so in order to hide a value from SCEV canonicalization.
3718
3719 FoldingSetNodeID ID;
3720 ID.AddInteger(scUnknown);
3721 ID.AddPointer(V);
3722 void *IP = nullptr;
3723 if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) {
3724 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3725, __PRETTY_FUNCTION__))
3725 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3725, __PRETTY_FUNCTION__))
;
3726 return S;
3727 }
3728 SCEV *S = new (SCEVAllocator) SCEVUnknown(ID.Intern(SCEVAllocator), V, this,
3729 FirstUnknown);
3730 FirstUnknown = cast<SCEVUnknown>(S);
3731 UniqueSCEVs.InsertNode(S, IP);
3732 return S;
3733}
3734
3735//===----------------------------------------------------------------------===//
3736// Basic SCEV Analysis and PHI Idiom Recognition Code
3737//
3738
3739/// Test if values of the given type are analyzable within the SCEV
3740/// framework. This primarily includes integer types, and it can optionally
3741/// include pointer types if the ScalarEvolution class has access to
3742/// target-specific information.
3743bool ScalarEvolution::isSCEVable(Type *Ty) const {
3744 // Integers and pointers are always SCEVable.
3745 return Ty->isIntOrPtrTy();
3746}
3747
3748/// Return the size in bits of the specified type, for which isSCEVable must
3749/// return true.
3750uint64_t ScalarEvolution::getTypeSizeInBits(Type *Ty) const {
3751 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3751, __PRETTY_FUNCTION__))
;
3752 if (Ty->isPointerTy())
3753 return getDataLayout().getIndexTypeSizeInBits(Ty);
3754 return getDataLayout().getTypeSizeInBits(Ty);
3755}
3756
3757/// Return a type with the same bitwidth as the given type and which represents
3758/// how SCEV will treat the given type, for which isSCEVable must return
3759/// true. For pointer types, this is the pointer index sized integer type.
3760Type *ScalarEvolution::getEffectiveSCEVType(Type *Ty) const {
3761 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3761, __PRETTY_FUNCTION__))
;
3762
3763 if (Ty->isIntegerTy())
3764 return Ty;
3765
3766 // The only other support type is pointer.
3767 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3767, __PRETTY_FUNCTION__))
;
3768 return getDataLayout().getIndexType(Ty);
3769}
3770
3771Type *ScalarEvolution::getWiderType(Type *T1, Type *T2) const {
3772 return getTypeSizeInBits(T1) >= getTypeSizeInBits(T2) ? T1 : T2;
3773}
3774
3775const SCEV *ScalarEvolution::getCouldNotCompute() {
3776 return CouldNotCompute.get();
3777}
3778
3779bool ScalarEvolution::checkValidity(const SCEV *S) const {
3780 bool ContainsNulls = SCEVExprContains(S, [](const SCEV *S) {
3781 auto *SU = dyn_cast<SCEVUnknown>(S);
3782 return SU && SU->getValue() == nullptr;
3783 });
3784
3785 return !ContainsNulls;
3786}
3787
3788bool ScalarEvolution::containsAddRecurrence(const SCEV *S) {
3789 HasRecMapType::iterator I = HasRecMap.find(S);
3790 if (I != HasRecMap.end())
3791 return I->second;
3792
3793 bool FoundAddRec =
3794 SCEVExprContains(S, [](const SCEV *S) { return isa<SCEVAddRecExpr>(S); });
3795 HasRecMap.insert({S, FoundAddRec});
3796 return FoundAddRec;
3797}
3798
3799/// Try to split a SCEVAddExpr into a pair of {SCEV, ConstantInt}.
3800/// If \p S is a SCEVAddExpr and is composed of a sub SCEV S' and an
3801/// offset I, then return {S', I}, else return {\p S, nullptr}.
3802static std::pair<const SCEV *, ConstantInt *> splitAddExpr(const SCEV *S) {
3803 const auto *Add = dyn_cast<SCEVAddExpr>(S);
3804 if (!Add)
3805 return {S, nullptr};
3806
3807 if (Add->getNumOperands() != 2)
3808 return {S, nullptr};
3809
3810 auto *ConstOp = dyn_cast<SCEVConstant>(Add->getOperand(0));
3811 if (!ConstOp)
3812 return {S, nullptr};
3813
3814 return {Add->getOperand(1), ConstOp->getValue()};
3815}
3816
3817/// Return the ValueOffsetPair set for \p S. \p S can be represented
3818/// by the value and offset from any ValueOffsetPair in the set.
3819SetVector<ScalarEvolution::ValueOffsetPair> *
3820ScalarEvolution::getSCEVValues(const SCEV *S) {
3821 ExprValueMapType::iterator SI = ExprValueMap.find_as(S);
3822 if (SI == ExprValueMap.end())
3823 return nullptr;
3824#ifndef NDEBUG
3825 if (VerifySCEVMap) {
3826 // Check there is no dangling Value in the set returned.
3827 for (const auto &VE : SI->second)
3828 assert(ValueExprMap.count(VE.first))((ValueExprMap.count(VE.first)) ? static_cast<void> (0)
: __assert_fail ("ValueExprMap.count(VE.first)", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3828, __PRETTY_FUNCTION__))
;
3829 }
3830#endif
3831 return &SI->second;
3832}
3833
3834/// Erase Value from ValueExprMap and ExprValueMap. ValueExprMap.erase(V)
3835/// cannot be used separately. eraseValueFromMap should be used to remove
3836/// V from ValueExprMap and ExprValueMap at the same time.
3837void ScalarEvolution::eraseValueFromMap(Value *V) {
3838 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
3839 if (I != ValueExprMap.end()) {
3840 const SCEV *S = I->second;
3841 // Remove {V, 0} from the set of ExprValueMap[S]
3842 if (SetVector<ValueOffsetPair> *SV = getSCEVValues(S))
3843 SV->remove({V, nullptr});
3844
3845 // Remove {V, Offset} from the set of ExprValueMap[Stripped]
3846 const SCEV *Stripped;
3847 ConstantInt *Offset;
3848 std::tie(Stripped, Offset) = splitAddExpr(S);
3849 if (Offset != nullptr) {
3850 if (SetVector<ValueOffsetPair> *SV = getSCEVValues(Stripped))
3851 SV->remove({V, Offset});
3852 }
3853 ValueExprMap.erase(V);
3854 }
3855}
3856
3857/// Check whether value has nuw/nsw/exact set but SCEV does not.
3858/// TODO: In reality it is better to check the poison recursively
3859/// but this is better than nothing.
3860static bool SCEVLostPoisonFlags(const SCEV *S, const Value *V) {
3861 if (auto *I = dyn_cast<Instruction>(V)) {
3862 if (isa<OverflowingBinaryOperator>(I)) {
3863 if (auto *NS = dyn_cast<SCEVNAryExpr>(S)) {
3864 if (I->hasNoSignedWrap() && !NS->hasNoSignedWrap())
3865 return true;
3866 if (I->hasNoUnsignedWrap() && !NS->hasNoUnsignedWrap())
3867 return true;
3868 }
3869 } else if (isa<PossiblyExactOperator>(I) && I->isExact())
3870 return true;
3871 }
3872 return false;
3873}
3874
3875/// Return an existing SCEV if it exists, otherwise analyze the expression and
3876/// create a new one.
3877const SCEV *ScalarEvolution::getSCEV(Value *V) {
3878 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3878, __PRETTY_FUNCTION__))
;
3879
3880 const SCEV *S = getExistingSCEV(V);
3881 if (S == nullptr) {
3882 S = createSCEV(V);
3883 // During PHI resolution, it is possible to create two SCEVs for the same
3884 // V, so it is needed to double check whether V->S is inserted into
3885 // ValueExprMap before insert S->{V, 0} into ExprValueMap.
3886 std::pair<ValueExprMapType::iterator, bool> Pair =
3887 ValueExprMap.insert({SCEVCallbackVH(V, this), S});
3888 if (Pair.second && !SCEVLostPoisonFlags(S, V)) {
3889 ExprValueMap[S].insert({V, nullptr});
3890
3891 // If S == Stripped + Offset, add Stripped -> {V, Offset} into
3892 // ExprValueMap.
3893 const SCEV *Stripped = S;
3894 ConstantInt *Offset = nullptr;
3895 std::tie(Stripped, Offset) = splitAddExpr(S);
3896 // If stripped is SCEVUnknown, don't bother to save
3897 // Stripped -> {V, offset}. It doesn't simplify and sometimes even
3898 // increase the complexity of the expansion code.
3899 // If V is GetElementPtrInst, don't save Stripped -> {V, offset}
3900 // because it may generate add/sub instead of GEP in SCEV expansion.
3901 if (Offset != nullptr && !isa<SCEVUnknown>(Stripped) &&
3902 !isa<GetElementPtrInst>(V))
3903 ExprValueMap[Stripped].insert({V, Offset});
3904 }
3905 }
3906 return S;
3907}
3908
3909const SCEV *ScalarEvolution::getExistingSCEV(Value *V) {
3910 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3910, __PRETTY_FUNCTION__))
;
3911
3912 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
3913 if (I != ValueExprMap.end()) {
3914 const SCEV *S = I->second;
3915 if (checkValidity(S))
3916 return S;
3917 eraseValueFromMap(V);
3918 forgetMemoizedResults(S);
3919 }
3920 return nullptr;
3921}
3922
3923/// Return a SCEV corresponding to -V = -1*V
3924const SCEV *ScalarEvolution::getNegativeSCEV(const SCEV *V,
3925 SCEV::NoWrapFlags Flags) {
3926 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
3927 return getConstant(
3928 cast<ConstantInt>(ConstantExpr::getNeg(VC->getValue())));
3929
3930 Type *Ty = V->getType();
3931 Ty = getEffectiveSCEVType(Ty);
3932 return getMulExpr(V, getMinusOne(Ty), Flags);
3933}
3934
3935/// If Expr computes ~A, return A else return nullptr
3936static const SCEV *MatchNotExpr(const SCEV *Expr) {
3937 const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Expr);
3938 if (!Add || Add->getNumOperands() != 2 ||
3939 !Add->getOperand(0)->isAllOnesValue())
3940 return nullptr;
3941
3942 const SCEVMulExpr *AddRHS = dyn_cast<SCEVMulExpr>(Add->getOperand(1));
3943 if (!AddRHS || AddRHS->getNumOperands() != 2 ||
3944 !AddRHS->getOperand(0)->isAllOnesValue())
3945 return nullptr;
3946
3947 return AddRHS->getOperand(1);
3948}
3949
3950/// Return a SCEV corresponding to ~V = -1-V
3951const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) {
3952 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
3953 return getConstant(
3954 cast<ConstantInt>(ConstantExpr::getNot(VC->getValue())));
3955
3956 // Fold ~(u|s)(min|max)(~x, ~y) to (u|s)(max|min)(x, y)
3957 if (const SCEVMinMaxExpr *MME = dyn_cast<SCEVMinMaxExpr>(V)) {
3958 auto MatchMinMaxNegation = [&](const SCEVMinMaxExpr *MME) {
3959 SmallVector<const SCEV *, 2> MatchedOperands;
3960 for (const SCEV *Operand : MME->operands()) {
3961 const SCEV *Matched = MatchNotExpr(Operand);
3962 if (!Matched)
3963 return (const SCEV *)nullptr;
3964 MatchedOperands.push_back(Matched);
3965 }
3966 return getMinMaxExpr(SCEVMinMaxExpr::negate(MME->getSCEVType()),
3967 MatchedOperands);
3968 };
3969 if (const SCEV *Replaced = MatchMinMaxNegation(MME))
3970 return Replaced;
3971 }
3972
3973 Type *Ty = V->getType();
3974 Ty = getEffectiveSCEVType(Ty);
3975 return getMinusSCEV(getMinusOne(Ty), V);
3976}
3977
3978const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS, const SCEV *RHS,
3979 SCEV::NoWrapFlags Flags,
3980 unsigned Depth) {
3981 // Fast path: X - X --> 0.
3982 if (LHS == RHS)
3983 return getZero(LHS->getType());
3984
3985 // We represent LHS - RHS as LHS + (-1)*RHS. This transformation
3986 // makes it so that we cannot make much use of NUW.
3987 auto AddFlags = SCEV::FlagAnyWrap;
3988 const bool RHSIsNotMinSigned =
3989 !getSignedRangeMin(RHS).isMinSignedValue();
3990 if (maskFlags(Flags, SCEV::FlagNSW) == SCEV::FlagNSW) {
3991 // Let M be the minimum representable signed value. Then (-1)*RHS
3992 // signed-wraps if and only if RHS is M. That can happen even for
3993 // a NSW subtraction because e.g. (-1)*M signed-wraps even though
3994 // -1 - M does not. So to transfer NSW from LHS - RHS to LHS +
3995 // (-1)*RHS, we need to prove that RHS != M.
3996 //
3997 // If LHS is non-negative and we know that LHS - RHS does not
3998 // signed-wrap, then RHS cannot be M. So we can rule out signed-wrap
3999 // either by proving that RHS > M or that LHS >= 0.
4000 if (RHSIsNotMinSigned || isKnownNonNegative(LHS)) {
4001 AddFlags = SCEV::FlagNSW;
4002 }
4003 }
4004
4005 // FIXME: Find a correct way to transfer NSW to (-1)*M when LHS -
4006 // RHS is NSW and LHS >= 0.
4007 //
4008 // The difficulty here is that the NSW flag may have been proven
4009 // relative to a loop that is to be found in a recurrence in LHS and
4010 // not in RHS. Applying NSW to (-1)*M may then let the NSW have a
4011 // larger scope than intended.
4012 auto NegFlags = RHSIsNotMinSigned ? SCEV::FlagNSW : SCEV::FlagAnyWrap;
4013
4014 return getAddExpr(LHS, getNegativeSCEV(RHS, NegFlags), AddFlags, Depth);
4015}
4016
4017const SCEV *ScalarEvolution::getTruncateOrZeroExtend(const SCEV *V, Type *Ty,
4018 unsigned Depth) {
4019 Type *SrcTy = V->getType();
4020 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4021, __PRETTY_FUNCTION__))
4021 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4021, __PRETTY_FUNCTION__))
;
4022 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4023 return V; // No conversion
4024 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
4025 return getTruncateExpr(V, Ty, Depth);
4026 return getZeroExtendExpr(V, Ty, Depth);
4027}
4028
4029const SCEV *ScalarEvolution::getTruncateOrSignExtend(const SCEV *V, Type *Ty,
4030 unsigned Depth) {
4031 Type *SrcTy = V->getType();
4032 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4033, __PRETTY_FUNCTION__))
4033 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4033, __PRETTY_FUNCTION__))
;
4034 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4035 return V; // No conversion
4036 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
4037 return getTruncateExpr(V, Ty, Depth);
4038 return getSignExtendExpr(V, Ty, Depth);
4039}
4040
4041const SCEV *
4042ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, Type *Ty) {
4043 Type *SrcTy = V->getType();
4044 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4045, __PRETTY_FUNCTION__))
4045 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4045, __PRETTY_FUNCTION__))
;
4046 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4047, __PRETTY_FUNCTION__))
4047 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4047, __PRETTY_FUNCTION__))
;
4048 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4049 return V; // No conversion
4050 return getZeroExtendExpr(V, Ty);
4051}
4052
4053const SCEV *
4054ScalarEvolution::getNoopOrSignExtend(const SCEV *V, Type *Ty) {
4055 Type *SrcTy = V->getType();
4056 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4057, __PRETTY_FUNCTION__))
4057 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4057, __PRETTY_FUNCTION__))
;
4058 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4059, __PRETTY_FUNCTION__))
4059 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4059, __PRETTY_FUNCTION__))
;
4060 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4061 return V; // No conversion
4062 return getSignExtendExpr(V, Ty);
4063}
4064
4065const SCEV *
4066ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, Type *Ty) {
4067 Type *SrcTy = V->getType();
4068 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4069, __PRETTY_FUNCTION__))
4069 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4069, __PRETTY_FUNCTION__))
;
4070 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4071, __PRETTY_FUNCTION__))
4071 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4071, __PRETTY_FUNCTION__))
;
4072 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4073 return V; // No conversion
4074 return getAnyExtendExpr(V, Ty);
4075}
4076
4077const SCEV *
4078ScalarEvolution::getTruncateOrNoop(const SCEV *V, Type *Ty) {
4079 Type *SrcTy = V->getType();
4080 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4081, __PRETTY_FUNCTION__))
4081 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4081, __PRETTY_FUNCTION__))
;
4082 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4083, __PRETTY_FUNCTION__))
4083 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4083, __PRETTY_FUNCTION__))
;
4084 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4085 return V; // No conversion
4086 return getTruncateExpr(V, Ty);
4087}
4088
4089const SCEV *ScalarEvolution::getUMaxFromMismatchedTypes(const SCEV *LHS,
4090 const SCEV *RHS) {
4091 const SCEV *PromotedLHS = LHS;
4092 const SCEV *PromotedRHS = RHS;
4093
4094 if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType()))
4095 PromotedRHS = getZeroExtendExpr(RHS, LHS->getType());
4096 else
4097 PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType());
4098
4099 return getUMaxExpr(PromotedLHS, PromotedRHS);
4100}
4101
4102const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(const SCEV *LHS,
4103 const SCEV *RHS) {
4104 SmallVector<const SCEV *, 2> Ops = { LHS, RHS };
4105 return getUMinFromMismatchedTypes(Ops);
4106}
4107
4108const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(
4109 SmallVectorImpl<const SCEV *> &Ops) {
4110 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4110, __PRETTY_FUNCTION__))
;
4111 // Trivial case.
4112 if (Ops.size() == 1)
4113 return Ops[0];
4114
4115 // Find the max type first.
4116 Type *MaxType = nullptr;
4117 for (auto *S : Ops)
4118 if (MaxType)
4119 MaxType = getWiderType(MaxType, S->getType());
4120 else
4121 MaxType = S->getType();
4122 assert(MaxType && "Failed to find maximum type!")((MaxType && "Failed to find maximum type!") ? static_cast
<void> (0) : __assert_fail ("MaxType && \"Failed to find maximum type!\""
, "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4122, __PRETTY_FUNCTION__))
;
4123
4124 // Extend all ops to max type.
4125 SmallVector<const SCEV *, 2> PromotedOps;
4126 for (auto *S : Ops)
4127 PromotedOps.push_back(getNoopOrZeroExtend(S, MaxType));
4128
4129 // Generate umin.
4130 return getUMinExpr(PromotedOps);
4131}
4132
4133const SCEV *ScalarEvolution::getPointerBase(const SCEV *V) {
4134 // A pointer operand may evaluate to a nonpointer expression, such as null.
4135 if (!V->getType()->isPointerTy())
4136 return V;
4137
4138 while (true) {
4139 if (const SCEVIntegralCastExpr *Cast = dyn_cast<SCEVIntegralCastExpr>(V)) {
4140 V = Cast->getOperand();
4141 } else if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(V)) {
4142 const SCEV *PtrOp = nullptr;
4143 for (const SCEV *NAryOp : NAry->operands()) {
4144 if (NAryOp->getType()->isPointerTy()) {
4145 // Cannot find the base of an expression with multiple pointer ops.
4146 if (PtrOp)
4147 return V;
4148 PtrOp = NAryOp;
4149 }
4150 }
4151 if (!PtrOp) // All operands were non-pointer.
4152 return V;
4153 V = PtrOp;
4154 } else // Not something we can look further into.
4155 return V;
4156 }
4157}
4158
4159/// Push users of the given Instruction onto the given Worklist.
4160static void
4161PushDefUseChildren(Instruction *I,
4162 SmallVectorImpl<Instruction *> &Worklist) {
4163 // Push the def-use children onto the Worklist stack.
4164 for (User *U : I->users())
4165 Worklist.push_back(cast<Instruction>(U));
4166}
4167
4168void ScalarEvolution::forgetSymbolicName(Instruction *PN, const SCEV *SymName) {
4169 SmallVector<Instruction *, 16> Worklist;
4170 PushDefUseChildren(PN, Worklist);
4171
4172 SmallPtrSet<Instruction *, 8> Visited;
4173 Visited.insert(PN);
4174 while (!Worklist.empty()) {
4175 Instruction *I = Worklist.pop_back_val();
4176 if (!Visited.insert(I).second)
4177 continue;
4178
4179 auto It = ValueExprMap.find_as(static_cast<Value *>(I));
4180 if (It != ValueExprMap.end()) {
4181 const SCEV *Old = It->second;
4182
4183 // Short-circuit the def-use traversal if the symbolic name
4184 // ceases to appear in expressions.
4185 if (Old != SymName && !hasOperand(Old, SymName))
4186 continue;
4187
4188 // SCEVUnknown for a PHI either means that it has an unrecognized
4189 // structure, it's a PHI that's in the progress of being computed
4190 // by createNodeForPHI, or it's a single-value PHI. In the first case,
4191 // additional loop trip count information isn't going to change anything.
4192 // In the second case, createNodeForPHI will perform the necessary
4193 // updates on its own when it gets to that point. In the third, we do
4194 // want to forget the SCEVUnknown.
4195 if (!isa<PHINode>(I) ||
4196 !isa<SCEVUnknown>(Old) ||
4197 (I != PN && Old == SymName)) {
4198 eraseValueFromMap(It->first);
4199 forgetMemoizedResults(Old);
4200 }
4201 }
4202
4203 PushDefUseChildren(I, Worklist);
4204 }
4205}
4206
4207namespace {
4208
4209/// Takes SCEV S and Loop L. For each AddRec sub-expression, use its start
4210/// expression in case its Loop is L. If it is not L then
4211/// if IgnoreOtherLoops is true then use AddRec itself
4212/// otherwise rewrite cannot be done.
4213/// If SCEV contains non-invariant unknown SCEV rewrite cannot be done.
4214class SCEVInitRewriter : public SCEVRewriteVisitor<SCEVInitRewriter> {
4215public:
4216 static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE,
4217 bool IgnoreOtherLoops = true) {
4218 SCEVInitRewriter Rewriter(L, SE);
4219 const SCEV *Result = Rewriter.visit(S);
4220 if (Rewriter.hasSeenLoopVariantSCEVUnknown())
4221 return SE.getCouldNotCompute();
4222 return Rewriter.hasSeenOtherLoops() && !IgnoreOtherLoops
4223 ? SE.getCouldNotCompute()
4224 : Result;
4225 }
4226
4227 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4228 if (!SE.isLoopInvariant(Expr, L))
4229 SeenLoopVariantSCEVUnknown = true;
4230 return Expr;
4231 }
4232
4233 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4234 // Only re-write AddRecExprs for this loop.
4235 if (Expr->getLoop() == L)
4236 return Expr->getStart();
4237 SeenOtherLoops = true;
4238 return Expr;
4239 }
4240
4241 bool hasSeenLoopVariantSCEVUnknown() { return SeenLoopVariantSCEVUnknown; }
4242
4243 bool hasSeenOtherLoops() { return SeenOtherLoops; }
4244
4245private:
4246 explicit SCEVInitRewriter(const Loop *L, ScalarEvolution &SE)
4247 : SCEVRewriteVisitor(SE), L(L) {}
4248
4249 const Loop *L;
4250 bool SeenLoopVariantSCEVUnknown = false;
4251 bool SeenOtherLoops = false;
4252};
4253
4254/// Takes SCEV S and Loop L. For each AddRec sub-expression, use its post
4255/// increment expression in case its Loop is L. If it is not L then
4256/// use AddRec itself.
4257/// If SCEV contains non-invariant unknown SCEV rewrite cannot be done.
4258class SCEVPostIncRewriter : public SCEVRewriteVisitor<SCEVPostIncRewriter> {
4259public:
4260 static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE) {
4261 SCEVPostIncRewriter Rewriter(L, SE);
4262 const SCEV *Result = Rewriter.visit(S);
4263 return Rewriter.hasSeenLoopVariantSCEVUnknown()
4264 ? SE.getCouldNotCompute()
4265 : Result;
4266 }
4267
4268 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4269 if (!SE.isLoopInvariant(Expr, L))
4270 SeenLoopVariantSCEVUnknown = true;
4271 return Expr;
4272 }
4273
4274 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4275 // Only re-write AddRecExprs for this loop.
4276 if (Expr->getLoop() == L)
4277 return Expr->getPostIncExpr(SE);
4278 SeenOtherLoops = true;
4279 return Expr;
4280 }
4281
4282 bool hasSeenLoopVariantSCEVUnknown() { return SeenLoopVariantSCEVUnknown; }
4283
4284 bool hasSeenOtherLoops() { return SeenOtherLoops; }
4285
4286private:
4287 explicit SCEVPostIncRewriter(const Loop *L, ScalarEvolution &SE)
4288 : SCEVRewriteVisitor(SE), L(L) {}
4289
4290 const Loop *L;
4291 bool SeenLoopVariantSCEVUnknown = false;
4292 bool SeenOtherLoops = false;
4293};
4294
4295/// This class evaluates the compare condition by matching it against the
4296/// condition of loop latch. If there is a match we assume a true value
4297/// for the condition while building SCEV nodes.
4298class SCEVBackedgeConditionFolder
4299 : public SCEVRewriteVisitor<SCEVBackedgeConditionFolder> {
4300public:
4301 static const SCEV *rewrite(const SCEV *S, const Loop *L,
4302 ScalarEvolution &SE) {
4303 bool IsPosBECond = false;
4304 Value *BECond = nullptr;
4305 if (BasicBlock *Latch = L->getLoopLatch()) {
4306 BranchInst *BI = dyn_cast<BranchInst>(Latch->getTerminator());
4307 if (BI && BI->isConditional()) {
4308 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4309, __PRETTY_FUNCTION__))
4309 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4309, __PRETTY_FUNCTION__))
;
4310 BECond = BI->getCondition();
4311 IsPosBECond = BI->getSuccessor(0) == L->getHeader();
4312 } else {
4313 return S;
4314 }
4315 }
4316 SCEVBackedgeConditionFolder Rewriter(L, BECond, IsPosBECond, SE);
4317 return Rewriter.visit(S);
4318 }
4319
4320 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4321 const SCEV *Result = Expr;
4322 bool InvariantF = SE.isLoopInvariant(Expr, L);
4323
4324 if (!InvariantF) {
4325 Instruction *I = cast<Instruction>(Expr->getValue());
4326 switch (I->getOpcode()) {
4327 case Instruction::Select: {
4328 SelectInst *SI = cast<SelectInst>(I);
4329 Optional<const SCEV *> Res =
4330 compareWithBackedgeCondition(SI->getCondition());
4331 if (Res.hasValue()) {
4332 bool IsOne = cast<SCEVConstant>(Res.getValue())->getValue()->isOne();
4333 Result = SE.getSCEV(IsOne ? SI->getTrueValue() : SI->getFalseValue());
4334 }
4335 break;
4336 }
4337 default: {
4338 Optional<const SCEV *> Res = compareWithBackedgeCondition(I);
4339 if (Res.hasValue())
4340 Result = Res.getValue();
4341 break;
4342 }
4343 }
4344 }
4345 return Result;
4346 }
4347
4348private:
4349 explicit SCEVBackedgeConditionFolder(const Loop *L, Value *BECond,
4350 bool IsPosBECond, ScalarEvolution &SE)
4351 : SCEVRewriteVisitor(SE), L(L), BackedgeCond(BECond),
4352 IsPositiveBECond(IsPosBECond) {}
4353
4354 Optional<const SCEV *> compareWithBackedgeCondition(Value *IC);
4355
4356 const Loop *L;
4357 /// Loop back condition.
4358 Value *BackedgeCond = nullptr;
4359 /// Set to true if loop back is on positive branch condition.
4360 bool IsPositiveBECond;
4361};
4362
4363Optional<const SCEV *>
4364SCEVBackedgeConditionFolder::compareWithBackedgeCondition(Value *IC) {
4365
4366 // If value matches the backedge condition for loop latch,
4367 // then return a constant evolution node based on loopback
4368 // branch taken.
4369 if (BackedgeCond == IC)
4370 return IsPositiveBECond ? SE.getOne(Type::getInt1Ty(SE.getContext()))
4371 : SE.getZero(Type::getInt1Ty(SE.getContext()));
4372 return None;
4373}
4374
4375class SCEVShiftRewriter : public SCEVRewriteVisitor<SCEVShiftRewriter> {
4376public:
4377 static const SCEV *rewrite(const SCEV *S, const Loop *L,
4378 ScalarEvolution &SE) {
4379 SCEVShiftRewriter Rewriter(L, SE);
4380 const SCEV *Result = Rewriter.visit(S);
4381 return Rewriter.isValid() ? Result : SE.getCouldNotCompute();
4382 }
4383
4384 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4385 // Only allow AddRecExprs for this loop.
4386 if (!SE.isLoopInvariant(Expr, L))
4387 Valid = false;
4388 return Expr;
4389 }
4390
4391 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4392 if (Expr->getLoop() == L && Expr->isAffine())
4393 return SE.getMinusSCEV(Expr, Expr->getStepRecurrence(SE));
4394 Valid = false;
4395 return Expr;
4396 }
4397
4398 bool isValid() { return Valid; }
4399
4400private:
4401 explicit SCEVShiftRewriter(const Loop *L, ScalarEvolution &SE)
4402 : SCEVRewriteVisitor(SE), L(L) {}
4403
4404 const Loop *L;
4405 bool Valid = true;
4406};
4407
4408} // end anonymous namespace
4409
4410SCEV::NoWrapFlags
4411ScalarEvolution::proveNoWrapViaConstantRanges(const SCEVAddRecExpr *AR) {
4412 if (!AR->isAffine())
4413 return SCEV::FlagAnyWrap;
4414
4415 using OBO = OverflowingBinaryOperator;
4416
4417 SCEV::NoWrapFlags Result = SCEV::FlagAnyWrap;
4418
4419 if (!AR->hasNoSignedWrap()) {
4420 ConstantRange AddRecRange = getSignedRange(AR);
4421 ConstantRange IncRange = getSignedRange(AR->getStepRecurrence(*this));
4422
4423 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
4424 Instruction::Add, IncRange, OBO::NoSignedWrap);
4425 if (NSWRegion.contains(AddRecRange))
4426 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNSW);
4427 }
4428
4429 if (!AR->hasNoUnsignedWrap()) {
4430 ConstantRange AddRecRange = getUnsignedRange(AR);
4431 ConstantRange IncRange = getUnsignedRange(AR->getStepRecurrence(*this));
4432
4433 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
4434 Instruction::Add, IncRange, OBO::NoUnsignedWrap);
4435 if (NUWRegion.contains(AddRecRange))
4436 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNUW);
4437 }
4438
4439 return Result;
4440}
4441
4442SCEV::NoWrapFlags
4443ScalarEvolution::proveNoSignedWrapViaInduction(const SCEVAddRecExpr *AR) {
4444 SCEV::NoWrapFlags Result = AR->getNoWrapFlags();
4445
4446 if (AR->hasNoSignedWrap())
4447 return Result;
4448
4449 if (!AR->isAffine())
4450 return Result;
4451
4452 const SCEV *Step = AR->getStepRecurrence(*this);
4453 const Loop *L = AR->getLoop();
4454
4455 // Check whether the backedge-taken count is SCEVCouldNotCompute.
4456 // Note that this serves two purposes: It filters out loops that are
4457 // simply not analyzable, and it covers the case where this code is
4458 // being called from within backedge-taken count analysis, such that
4459 // attempting to ask for the backedge-taken count would likely result
4460 // in infinite recursion. In the later case, the analysis code will
4461 // cope with a conservative value, and it will take care to purge
4462 // that value once it has finished.
4463 const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(L);
4464
4465 // Normally, in the cases we can prove no-overflow via a
4466 // backedge guarding condition, we can also compute a backedge
4467 // taken count for the loop. The exceptions are assumptions and
4468 // guards present in the loop -- SCEV is not great at exploiting
4469 // these to compute max backedge taken counts, but can still use
4470 // these to prove lack of overflow. Use this fact to avoid
4471 // doing extra work that may not pay off.
4472
4473 if (isa<SCEVCouldNotCompute>(MaxBECount) && !HasGuards &&
4474 AC.assumptions().empty())
4475 return Result;
4476
4477 // If the backedge is guarded by a comparison with the pre-inc value the
4478 // addrec is safe. Also, if the entry is guarded by a comparison with the
4479 // start value and the backedge is guarded by a comparison with the post-inc
4480 // value, the addrec is safe.
4481 ICmpInst::Predicate Pred;
4482 const SCEV *OverflowLimit =
4483 getSignedOverflowLimitForStep(Step, &Pred, this);
4484 if (OverflowLimit &&
4485 (isLoopBackedgeGuardedByCond(L, Pred, AR, OverflowLimit) ||
4486 isKnownOnEveryIteration(Pred, AR, OverflowLimit))) {
4487 Result = setFlags(Result, SCEV::FlagNSW);
4488 }
4489 return Result;
4490}
4491SCEV::NoWrapFlags
4492ScalarEvolution::proveNoUnsignedWrapViaInduction(const SCEVAddRecExpr *AR) {
4493 SCEV::NoWrapFlags Result = AR->getNoWrapFlags();
4494
4495 if (AR->hasNoUnsignedWrap())
1
Taking false branch
4496 return Result;
4497
4498 if (!AR->isAffine())
2
Taking false branch
4499 return Result;
4500
4501 const SCEV *Step = AR->getStepRecurrence(*this);
4502 unsigned BitWidth = getTypeSizeInBits(AR->getType());
4503 const Loop *L = AR->getLoop();
4504
4505 // Check whether the backedge-taken count is SCEVCouldNotCompute.
4506 // Note that this serves two purposes: It filters out loops that are
4507 // simply not analyzable, and it covers the case where this code is
4508 // being called from within backedge-taken count analysis, such that
4509 // attempting to ask for the backedge-taken count would likely result
4510 // in infinite recursion. In the later case, the analysis code will
4511 // cope with a conservative value, and it will take care to purge
4512 // that value once it has finished.
4513 const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(L);
4514
4515 // Normally, in the cases we can prove no-overflow via a
4516 // backedge guarding condition, we can also compute a backedge
4517 // taken count for the loop. The exceptions are assumptions and
4518 // guards present in the loop -- SCEV is not great at exploiting
4519 // these to compute max backedge taken counts, but can still use
4520 // these to prove lack of overflow. Use this fact to avoid
4521 // doing extra work that may not pay off.
4522
4523 if (isa<SCEVCouldNotCompute>(MaxBECount) && !HasGuards &&
3
Assuming 'MaxBECount' is not a 'SCEVCouldNotCompute'
4
Taking false branch
4524 AC.assumptions().empty())
4525 return Result;
4526
4527 // If the backedge is guarded by a comparison with the pre-inc value the
4528 // addrec is safe. Also, if the entry is guarded by a comparison with the
4529 // start value and the backedge is guarded by a comparison with the post-inc
4530 // value, the addrec is safe.
4531 if (isKnownPositive(Step)) {
5
Taking true branch
4532 const SCEV *N = getConstant(APInt::getMinValue(BitWidth) -
4533 getUnsignedRangeMax(Step));
4534 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT, AR, N) ||
6
Calling 'ScalarEvolution::isLoopBackedgeGuardedByCond'
18
Returning from 'ScalarEvolution::isLoopBackedgeGuardedByCond'
4535 isKnownOnEveryIteration(ICmpInst::ICMP_ULT, AR, N)) {
19
Calling 'ScalarEvolution::isKnownOnEveryIteration'
4536 Result = setFlags(Result, SCEV::FlagNUW);
4537 }
4538 }
4539
4540 return Result;
4541}
4542
4543namespace {
4544
4545/// Represents an abstract binary operation. This may exist as a
4546/// normal instruction or constant expression, or may have been
4547/// derived from an expression tree.
4548struct BinaryOp {
4549 unsigned Opcode;
4550 Value *LHS;
4551 Value *RHS;
4552 bool IsNSW = false;
4553 bool IsNUW = false;
4554 bool IsExact = false;
4555
4556 /// Op is set if this BinaryOp corresponds to a concrete LLVM instruction or
4557 /// constant expression.
4558 Operator *Op = nullptr;
4559
4560 explicit BinaryOp(Operator *Op)
4561 : Opcode(Op->getOpcode()), LHS(Op->getOperand(0)), RHS(Op->getOperand(1)),
4562 Op(Op) {
4563 if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(Op)) {
4564 IsNSW = OBO->hasNoSignedWrap();
4565 IsNUW = OBO->hasNoUnsignedWrap();
4566 }
4567 if (auto *PEO = dyn_cast<PossiblyExactOperator>(Op))
4568 IsExact = PEO->isExact();
4569 }
4570
4571 explicit BinaryOp(unsigned Opcode, Value *LHS, Value *RHS, bool IsNSW = false,
4572 bool IsNUW = false, bool IsExact = false)
4573 : Opcode(Opcode), LHS(LHS), RHS(RHS), IsNSW(IsNSW), IsNUW(IsNUW),
4574 IsExact(IsExact) {}
4575};
4576
4577} // end anonymous namespace
4578
4579/// Try to map \p V into a BinaryOp, and return \c None on failure.
4580static Optional<BinaryOp> MatchBinaryOp(Value *V, DominatorTree &DT) {
4581 auto *Op = dyn_cast<Operator>(V);
4582 if (!Op)
4583 return None;
4584
4585 // Implementation detail: all the cleverness here should happen without
4586 // creating new SCEV expressions -- our caller knowns tricks to avoid creating
4587 // SCEV expressions when possible, and we should not break that.
4588
4589 switch (Op->getOpcode()) {
4590 case Instruction::Add:
4591 case Instruction::Sub:
4592 case Instruction::Mul:
4593 case Instruction::UDiv:
4594 case Instruction::URem:
4595 case Instruction::And:
4596 case Instruction::Or:
4597 case Instruction::AShr:
4598 case Instruction::Shl:
4599 return BinaryOp(Op);
4600
4601 case Instruction::Xor:
4602 if (auto *RHSC = dyn_cast<ConstantInt>(Op->getOperand(1)))
4603 // If the RHS of the xor is a signmask, then this is just an add.
4604 // Instcombine turns add of signmask into xor as a strength reduction step.
4605 if (RHSC->getValue().isSignMask())
4606 return BinaryOp(Instruction::Add, Op->getOperand(0), Op->getOperand(1));
4607 return BinaryOp(Op);
4608
4609 case Instruction::LShr:
4610 // Turn logical shift right of a constant into a unsigned divide.
4611 if (ConstantInt *SA = dyn_cast<ConstantInt>(Op->getOperand(1))) {
4612 uint32_t BitWidth = cast<IntegerType>(Op->getType())->getBitWidth();
4613
4614 // If the shift count is not less than the bitwidth, the result of
4615 // the shift is undefined. Don't try to analyze it, because the
4616 // resolution chosen here may differ from the resolution chosen in
4617 // other parts of the compiler.
4618 if (SA->getValue().ult(BitWidth)) {
4619 Constant *X =
4620 ConstantInt::get(SA->getContext(),
4621 APInt::getOneBitSet(BitWidth, SA->getZExtValue()));
4622 return BinaryOp(Instruction::UDiv, Op->getOperand(0), X);
4623 }
4624 }
4625 return BinaryOp(Op);
4626
4627 case Instruction::ExtractValue: {
4628 auto *EVI = cast<ExtractValueInst>(Op);
4629 if (EVI->getNumIndices() != 1 || EVI->getIndices()[0] != 0)
4630 break;
4631
4632 auto *WO = dyn_cast<WithOverflowInst>(EVI->getAggregateOperand());
4633 if (!WO)
4634 break;
4635
4636 Instruction::BinaryOps BinOp = WO->getBinaryOp();
4637 bool Signed = WO->isSigned();
4638 // TODO: Should add nuw/nsw flags for mul as well.
4639 if (BinOp == Instruction::Mul || !isOverflowIntrinsicNoWrap(WO, DT))
4640 return BinaryOp(BinOp, WO->getLHS(), WO->getRHS());
4641
4642 // Now that we know that all uses of the arithmetic-result component of
4643 // CI are guarded by the overflow check, we can go ahead and pretend
4644 // that the arithmetic is non-overflowing.
4645 return BinaryOp(BinOp, WO->getLHS(), WO->getRHS(),
4646 /* IsNSW = */ Signed, /* IsNUW = */ !Signed);
4647 }
4648
4649 default:
4650 break;
4651 }
4652
4653 // Recognise intrinsic loop.decrement.reg, and as this has exactly the same
4654 // semantics as a Sub, return a binary sub expression.
4655 if (auto *II = dyn_cast<IntrinsicInst>(V))
4656 if (II->getIntrinsicID() == Intrinsic::loop_decrement_reg)
4657 return BinaryOp(Instruction::Sub, II->getOperand(0), II->getOperand(1));
4658
4659 return None;
4660}
4661
4662/// Helper function to createAddRecFromPHIWithCasts. We have a phi
4663/// node whose symbolic (unknown) SCEV is \p SymbolicPHI, which is updated via
4664/// the loop backedge by a SCEVAddExpr, possibly also with a few casts on the
4665/// way. This function checks if \p Op, an operand of this SCEVAddExpr,
4666/// follows one of the following patterns:
4667/// Op == (SExt ix (Trunc iy (%SymbolicPHI) to ix) to iy)
4668/// Op == (ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy)
4669/// If the SCEV expression of \p Op conforms with one of the expected patterns
4670/// we return the type of the truncation operation, and indicate whether the
4671/// truncated type should be treated as signed/unsigned by setting
4672/// \p Signed to true/false, respectively.
4673static Type *isSimpleCastedPHI(const SCEV *Op, const SCEVUnknown *SymbolicPHI,
4674 bool &Signed, ScalarEvolution &SE) {
4675 // The case where Op == SymbolicPHI (that is, with no type conversions on
4676 // the way) is handled by the regular add recurrence creating logic and
4677 // would have already been triggered in createAddRecForPHI. Reaching it here
4678 // means that createAddRecFromPHI had failed for this PHI before (e.g.,
4679 // because one of the other operands of the SCEVAddExpr updating this PHI is
4680 // not invariant).
4681 //
4682 // Here we look for the case where Op = (ext(trunc(SymbolicPHI))), and in
4683 // this case predicates that allow us to prove that Op == SymbolicPHI will
4684 // be added.
4685 if (Op == SymbolicPHI)
4686 return nullptr;
4687
4688 unsigned SourceBits = SE.getTypeSizeInBits(SymbolicPHI->getType());
4689 unsigned NewBits = SE.getTypeSizeInBits(Op->getType());
4690 if (SourceBits != NewBits)
4691 return nullptr;
4692
4693 const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(Op);
4694 const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(Op);
4695 if (!SExt && !ZExt)
4696 return nullptr;
4697 const SCEVTruncateExpr *Trunc =
4698 SExt ? dyn_cast<SCEVTruncateExpr>(SExt->getOperand())
4699 : dyn_cast<SCEVTruncateExpr>(ZExt->getOperand());
4700 if (!Trunc)
4701 return nullptr;
4702 const SCEV *X = Trunc->getOperand();
4703 if (X != SymbolicPHI)
4704 return nullptr;
4705 Signed = SExt != nullptr;
4706 return Trunc->getType();
4707}
4708
4709static const Loop *isIntegerLoopHeaderPHI(const PHINode *PN, LoopInfo &LI) {
4710 if (!PN->getType()->isIntegerTy())
4711 return nullptr;
4712 const Loop *L = LI.getLoopFor(PN->getParent());
4713 if (!L || L->getHeader() != PN->getParent())
4714 return nullptr;
4715 return L;
4716}
4717
4718// Analyze \p SymbolicPHI, a SCEV expression of a phi node, and check if the
4719// computation that updates the phi follows the following pattern:
4720// (SExt/ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy) + InvariantAccum
4721// which correspond to a phi->trunc->sext/zext->add->phi update chain.
4722// If so, try to see if it can be rewritten as an AddRecExpr under some
4723// Predicates. If successful, return them as a pair. Also cache the results
4724// of the analysis.
4725//
4726// Example usage scenario:
4727// Say the Rewriter is called for the following SCEV:
4728// 8 * ((sext i32 (trunc i64 %X to i32) to i64) + %Step)
4729// where:
4730// %X = phi i64 (%Start, %BEValue)
4731// It will visitMul->visitAdd->visitSExt->visitTrunc->visitUnknown(%X),
4732// and call this function with %SymbolicPHI = %X.
4733//
4734// The analysis will find that the value coming around the backedge has
4735// the following SCEV:
4736// BEValue = ((sext i32 (trunc i64 %X to i32) to i64) + %Step)
4737// Upon concluding that this matches the desired pattern, the function
4738// will return the pair {NewAddRec, SmallPredsVec} where:
4739// NewAddRec = {%Start,+,%Step}
4740// SmallPredsVec = {P1, P2, P3} as follows:
4741// P1(WrapPred): AR: {trunc(%Start),+,(trunc %Step)}<nsw> Flags: <nssw>
4742// P2(EqualPred): %Start == (sext i32 (trunc i64 %Start to i32) to i64)
4743// P3(EqualPred): %Step == (sext i32 (trunc i64 %Step to i32) to i64)
4744// The returned pair means that SymbolicPHI can be rewritten into NewAddRec
4745// under the predicates {P1,P2,P3}.
4746// This predicated rewrite will be cached in PredicatedSCEVRewrites:
4747// PredicatedSCEVRewrites[{%X,L}] = {NewAddRec, {P1,P2,P3)}
4748//
4749// TODO's:
4750//
4751// 1) Extend the Induction descriptor to also support inductions that involve
4752// casts: When needed (namely, when we are called in the context of the
4753// vectorizer induction analysis), a Set of cast instructions will be
4754// populated by this method, and provided back to isInductionPHI. This is
4755// needed to allow the vectorizer to properly record them to be ignored by
4756// the cost model and to avoid vectorizing them (otherwise these casts,
4757// which are redundant under the runtime overflow checks, will be
4758// vectorized, which can be costly).
4759//
4760// 2) Support additional induction/PHISCEV patterns: We also want to support
4761// inductions where the sext-trunc / zext-trunc operations (partly) occur
4762// after the induction update operation (the induction increment):
4763//
4764// (Trunc iy (SExt/ZExt ix (%SymbolicPHI + InvariantAccum) to iy) to ix)
4765// which correspond to a phi->add->trunc->sext/zext->phi update chain.
4766//
4767// (Trunc iy ((SExt/ZExt ix (%SymbolicPhi) to iy) + InvariantAccum) to ix)
4768// which correspond to a phi->trunc->add->sext/zext->phi update chain.
4769//
4770// 3) Outline common code with createAddRecFromPHI to avoid duplication.
4771Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4772ScalarEvolution::createAddRecFromPHIWithCastsImpl(const SCEVUnknown *SymbolicPHI) {
4773 SmallVector<const SCEVPredicate *, 3> Predicates;
4774
4775 // *** Part1: Analyze if we have a phi-with-cast pattern for which we can
4776 // return an AddRec expression under some predicate.
4777
4778 auto *PN = cast<PHINode>(SymbolicPHI->getValue());
4779 const Loop *L = isIntegerLoopHeaderPHI(PN, LI);
4780 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4780, __PRETTY_FUNCTION__))
;
4781
4782 // The loop may have multiple entrances or multiple exits; we can analyze
4783 // this phi as an addrec if it has a unique entry value and a unique
4784 // backedge value.
4785 Value *BEValueV = nullptr, *StartValueV = nullptr;
4786 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
4787 Value *V = PN->getIncomingValue(i);
4788 if (L->contains(PN->getIncomingBlock(i))) {
4789 if (!BEValueV) {
4790 BEValueV = V;
4791 } else if (BEValueV != V) {
4792 BEValueV = nullptr;
4793 break;
4794 }
4795 } else if (!StartValueV) {
4796 StartValueV = V;
4797 } else if (StartValueV != V) {
4798 StartValueV = nullptr;
4799 break;
4800 }
4801 }
4802 if (!BEValueV || !StartValueV)
4803 return None;
4804
4805 const SCEV *BEValue = getSCEV(BEValueV);
4806
4807 // If the value coming around the backedge is an add with the symbolic
4808 // value we just inserted, possibly with casts that we can ignore under
4809 // an appropriate runtime guard, then we found a simple induction variable!
4810 const auto *Add = dyn_cast<SCEVAddExpr>(BEValue);
4811 if (!Add)
4812 return None;
4813
4814 // If there is a single occurrence of the symbolic value, possibly
4815 // casted, replace it with a recurrence.
4816 unsigned FoundIndex = Add->getNumOperands();
4817 Type *TruncTy = nullptr;
4818 bool Signed;
4819 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4820 if ((TruncTy =
4821 isSimpleCastedPHI(Add->getOperand(i), SymbolicPHI, Signed, *this)))
4822 if (FoundIndex == e) {
4823 FoundIndex = i;
4824 break;
4825 }
4826
4827 if (FoundIndex == Add->getNumOperands())
4828 return None;
4829
4830 // Create an add with everything but the specified operand.
4831 SmallVector<const SCEV *, 8> Ops;
4832 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4833 if (i != FoundIndex)
4834 Ops.push_back(Add->getOperand(i));
4835 const SCEV *Accum = getAddExpr(Ops);
4836
4837 // The runtime checks will not be valid if the step amount is
4838 // varying inside the loop.
4839 if (!isLoopInvariant(Accum, L))
4840 return None;
4841
4842 // *** Part2: Create the predicates
4843
4844 // Analysis was successful: we have a phi-with-cast pattern for which we
4845 // can return an AddRec expression under the following predicates:
4846 //
4847 // P1: A Wrap predicate that guarantees that Trunc(Start) + i*Trunc(Accum)
4848 // fits within the truncated type (does not overflow) for i = 0 to n-1.
4849 // P2: An Equal predicate that guarantees that
4850 // Start = (Ext ix (Trunc iy (Start) to ix) to iy)
4851 // P3: An Equal predicate that guarantees that
4852 // Accum = (Ext ix (Trunc iy (Accum) to ix) to iy)
4853 //
4854 // As we next prove, the above predicates guarantee that:
4855 // Start + i*Accum = (Ext ix (Trunc iy ( Start + i*Accum ) to ix) to iy)
4856 //
4857 //
4858 // More formally, we want to prove that:
4859 // Expr(i+1) = Start + (i+1) * Accum
4860 // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum
4861 //
4862 // Given that:
4863 // 1) Expr(0) = Start
4864 // 2) Expr(1) = Start + Accum
4865 // = (Ext ix (Trunc iy (Start) to ix) to iy) + Accum :: from P2
4866 // 3) Induction hypothesis (step i):
4867 // Expr(i) = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum
4868 //
4869 // Proof:
4870 // Expr(i+1) =
4871 // = Start + (i+1)*Accum
4872 // = (Start + i*Accum) + Accum
4873 // = Expr(i) + Accum
4874 // = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum + Accum
4875 // :: from step i
4876 //
4877 // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy) + Accum + Accum
4878 //
4879 // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy)
4880 // + (Ext ix (Trunc iy (Accum) to ix) to iy)
4881 // + Accum :: from P3
4882 //
4883 // = (Ext ix (Trunc iy ((Start + (i-1)*Accum) + Accum) to ix) to iy)
4884 // + Accum :: from P1: Ext(x)+Ext(y)=>Ext(x+y)
4885 //
4886 // = (Ext ix (Trunc iy (Start + i*Accum) to ix) to iy) + Accum
4887 // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum
4888 //
4889 // By induction, the same applies to all iterations 1<=i<n:
4890 //
4891
4892 // Create a truncated addrec for which we will add a no overflow check (P1).
4893 const SCEV *StartVal = getSCEV(StartValueV);
4894 const SCEV *PHISCEV =
4895 getAddRecExpr(getTruncateExpr(StartVal, TruncTy),
4896 getTruncateExpr(Accum, TruncTy), L, SCEV::FlagAnyWrap);
4897
4898 // PHISCEV can be either a SCEVConstant or a SCEVAddRecExpr.
4899 // ex: If truncated Accum is 0 and StartVal is a constant, then PHISCEV
4900 // will be constant.
4901 //
4902 // If PHISCEV is a constant, then P1 degenerates into P2 or P3, so we don't
4903 // add P1.
4904 if (const auto *AR = dyn_cast<SCEVAddRecExpr>(PHISCEV)) {
4905 SCEVWrapPredicate::IncrementWrapFlags AddedFlags =
4906 Signed ? SCEVWrapPredicate::IncrementNSSW
4907 : SCEVWrapPredicate::IncrementNUSW;
4908 const SCEVPredicate *AddRecPred = getWrapPredicate(AR, AddedFlags);
4909 Predicates.push_back(AddRecPred);
4910 }
4911
4912 // Create the Equal Predicates P2,P3:
4913
4914 // It is possible that the predicates P2 and/or P3 are computable at
4915 // compile time due to StartVal and/or Accum being constants.
4916 // If either one is, then we can check that now and escape if either P2
4917 // or P3 is false.
4918
4919 // Construct the extended SCEV: (Ext ix (Trunc iy (Expr) to ix) to iy)
4920 // for each of StartVal and Accum
4921 auto getExtendedExpr = [&](const SCEV *Expr,
4922 bool CreateSignExtend) -> const SCEV * {
4923 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4923, __PRETTY_FUNCTION__))
;
4924 const SCEV *TruncatedExpr = getTruncateExpr(Expr, TruncTy);
4925 const SCEV *ExtendedExpr =
4926 CreateSignExtend ? getSignExtendExpr(TruncatedExpr, Expr->getType())
4927 : getZeroExtendExpr(TruncatedExpr, Expr->getType());
4928 return ExtendedExpr;
4929 };
4930
4931 // Given:
4932 // ExtendedExpr = (Ext ix (Trunc iy (Expr) to ix) to iy
4933 // = getExtendedExpr(Expr)
4934 // Determine whether the predicate P: Expr == ExtendedExpr
4935 // is known to be false at compile time
4936 auto PredIsKnownFalse = [&](const SCEV *Expr,
4937 const SCEV *ExtendedExpr) -> bool {
4938 return Expr != ExtendedExpr &&
4939 isKnownPredicate(ICmpInst::ICMP_NE, Expr, ExtendedExpr);
4940 };
4941
4942 const SCEV *StartExtended = getExtendedExpr(StartVal, Signed);
4943 if (PredIsKnownFalse(StartVal, StartExtended)) {
4944 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)
;
4945 return None;
4946 }
4947
4948 // The Step is always Signed (because the overflow checks are either
4949 // NSSW or NUSW)
4950 const SCEV *AccumExtended = getExtendedExpr(Accum, /*CreateSignExtend=*/true);
4951 if (PredIsKnownFalse(Accum, AccumExtended)) {
4952 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)
;
4953 return None;
4954 }
4955
4956 auto AppendPredicate = [&](const SCEV *Expr,
4957 const SCEV *ExtendedExpr) -> void {
4958 if (Expr != ExtendedExpr &&
4959 !isKnownPredicate(ICmpInst::ICMP_EQ, Expr, ExtendedExpr)) {
4960 const SCEVPredicate *Pred = getEqualPredicate(Expr, ExtendedExpr);
4961 LLVM_DEBUG(dbgs() << "Added Predicate: " << *Pred)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "Added Predicate: " <<
*Pred; } } while (false)
;
4962 Predicates.push_back(Pred);
4963 }
4964 };
4965
4966 AppendPredicate(StartVal, StartExtended);
4967 AppendPredicate(Accum, AccumExtended);
4968
4969 // *** Part3: Predicates are ready. Now go ahead and create the new addrec in
4970 // which the casts had been folded away. The caller can rewrite SymbolicPHI
4971 // into NewAR if it will also add the runtime overflow checks specified in
4972 // Predicates.
4973 auto *NewAR = getAddRecExpr(StartVal, Accum, L, SCEV::FlagAnyWrap);
4974
4975 std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> PredRewrite =
4976 std::make_pair(NewAR, Predicates);
4977 // Remember the result of the analysis for this SCEV at this locayyytion.
4978 PredicatedSCEVRewrites[{SymbolicPHI, L}] = PredRewrite;
4979 return PredRewrite;
4980}
4981
4982Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4983ScalarEvolution::createAddRecFromPHIWithCasts(const SCEVUnknown *SymbolicPHI) {
4984 auto *PN = cast<PHINode>(SymbolicPHI->getValue());
4985 const Loop *L = isIntegerLoopHeaderPHI(PN, LI);
4986 if (!L)
4987 return None;
4988
4989 // Check to see if we already analyzed this PHI.
4990 auto I = PredicatedSCEVRewrites.find({SymbolicPHI, L});
4991 if (I != PredicatedSCEVRewrites.end()) {
4992 std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> Rewrite =
4993 I->second;
4994 // Analysis was done before and failed to create an AddRec:
4995 if (Rewrite.first == SymbolicPHI)
4996 return None;
4997 // Analysis was done before and succeeded to create an AddRec under
4998 // a predicate:
4999 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4999, __PRETTY_FUNCTION__))
;
5000 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5000, __PRETTY_FUNCTION__))
;
5001 return Rewrite;
5002 }
5003
5004 Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
5005 Rewrite = createAddRecFromPHIWithCastsImpl(SymbolicPHI);
5006
5007 // Record in the cache that the analysis failed
5008 if (!Rewrite) {
5009 SmallVector<const SCEVPredicate *, 3> Predicates;
5010 PredicatedSCEVRewrites[{SymbolicPHI, L}] = {SymbolicPHI, Predicates};
5011 return None;
5012 }
5013
5014 return Rewrite;
5015}
5016
5017// FIXME: This utility is currently required because the Rewriter currently
5018// does not rewrite this expression:
5019// {0, +, (sext ix (trunc iy to ix) to iy)}
5020// into {0, +, %step},
5021// even when the following Equal predicate exists:
5022// "%step == (sext ix (trunc iy to ix) to iy)".
5023bool PredicatedScalarEvolution::areAddRecsEqualWithPreds(
5024 const SCEVAddRecExpr *AR1, const SCEVAddRecExpr *AR2) const {
5025 if (AR1 == AR2)
5026 return true;
5027
5028 auto areExprsEqual = [&](const SCEV *Expr1, const SCEV *Expr2) -> bool {
5029 if (Expr1 != Expr2 && !Preds.implies(SE.getEqualPredicate(Expr1, Expr2)) &&
5030 !Preds.implies(SE.getEqualPredicate(Expr2, Expr1)))
5031 return false;
5032 return true;
5033 };
5034
5035 if (!areExprsEqual(AR1->getStart(), AR2->getStart()) ||
5036 !areExprsEqual(AR1->getStepRecurrence(SE), AR2->getStepRecurrence(SE)))
5037 return false;
5038 return true;
5039}
5040
5041/// A helper function for createAddRecFromPHI to handle simple cases.
5042///
5043/// This function tries to find an AddRec expression for the simplest (yet most
5044/// common) cases: PN = PHI(Start, OP(Self, LoopInvariant)).
5045/// If it fails, createAddRecFromPHI will use a more general, but slow,
5046/// technique for finding the AddRec expression.
5047const SCEV *ScalarEvolution::createSimpleAffineAddRec(PHINode *PN,
5048 Value *BEValueV,
5049 Value *StartValueV) {
5050 const Loop *L = LI.getLoopFor(PN->getParent());
5051 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5051, __PRETTY_FUNCTION__))
;
5052 assert(BEValueV && StartValueV)((BEValueV && StartValueV) ? static_cast<void> (
0) : __assert_fail ("BEValueV && StartValueV", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5052, __PRETTY_FUNCTION__))
;
5053
5054 auto BO = MatchBinaryOp(BEValueV, DT);
5055 if (!BO)
5056 return nullptr;
5057
5058 if (BO->Opcode != Instruction::Add)
5059 return nullptr;
5060
5061 const SCEV *Accum = nullptr;
5062 if (BO->LHS == PN && L->isLoopInvariant(BO->RHS))
5063 Accum = getSCEV(BO->RHS);
5064 else if (BO->RHS == PN && L->isLoopInvariant(BO->LHS))
5065 Accum = getSCEV(BO->LHS);
5066
5067 if (!Accum)
5068 return nullptr;
5069
5070 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
5071 if (BO->IsNUW)
5072 Flags = setFlags(Flags, SCEV::FlagNUW);
5073 if (BO->IsNSW)
5074 Flags = setFlags(Flags, SCEV::FlagNSW);
5075
5076 const SCEV *StartVal = getSCEV(StartValueV);
5077 const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
5078
5079 ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV;
5080
5081 // We can add Flags to the post-inc expression only if we
5082 // know that it is *undefined behavior* for BEValueV to
5083 // overflow.
5084 if (auto *BEInst = dyn_cast<Instruction>(BEValueV))
5085 if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L))
5086 (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
5087
5088 return PHISCEV;
5089}
5090
5091const SCEV *ScalarEvolution::createAddRecFromPHI(PHINode *PN) {
5092 const Loop *L = LI.getLoopFor(PN->getParent());
5093 if (!L || L->getHeader() != PN->getParent())
5094 return nullptr;
5095
5096 // The loop may have multiple entrances or multiple exits; we can analyze
5097 // this phi as an addrec if it has a unique entry value and a unique
5098 // backedge value.
5099 Value *BEValueV = nullptr, *StartValueV = nullptr;
5100 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
5101 Value *V = PN->getIncomingValue(i);
5102 if (L->contains(PN->getIncomingBlock(i))) {
5103 if (!BEValueV) {
5104 BEValueV = V;
5105 } else if (BEValueV != V) {
5106 BEValueV = nullptr;
5107 break;
5108 }
5109 } else if (!StartValueV) {
5110 StartValueV = V;
5111 } else if (StartValueV != V) {
5112 StartValueV = nullptr;
5113 break;
5114 }
5115 }
5116 if (!BEValueV || !StartValueV)
5117 return nullptr;
5118
5119 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5120, __PRETTY_FUNCTION__))
5120 "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5120, __PRETTY_FUNCTION__))
;
5121
5122 // First, try to find AddRec expression without creating a fictituos symbolic
5123 // value for PN.
5124 if (auto *S = createSimpleAffineAddRec(PN, BEValueV, StartValueV))
5125 return S;
5126
5127 // Handle PHI node value symbolically.
5128 const SCEV *SymbolicName = getUnknown(PN);
5129 ValueExprMap.insert({SCEVCallbackVH(PN, this), SymbolicName});
5130
5131 // Using this symbolic name for the PHI, analyze the value coming around
5132 // the back-edge.
5133 const SCEV *BEValue = getSCEV(BEValueV);
5134
5135 // NOTE: If BEValue is loop invariant, we know that the PHI node just
5136 // has a special value for the first iteration of the loop.
5137
5138 // If the value coming around the backedge is an add with the symbolic
5139 // value we just inserted, then we found a simple induction variable!
5140 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(BEValue)) {
5141 // If there is a single occurrence of the symbolic value, replace it
5142 // with a recurrence.
5143 unsigned FoundIndex = Add->getNumOperands();
5144 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
5145 if (Add->getOperand(i) == SymbolicName)
5146 if (FoundIndex == e) {
5147 FoundIndex = i;
5148 break;
5149 }
5150
5151 if (FoundIndex != Add->getNumOperands()) {
5152 // Create an add with everything but the specified operand.
5153 SmallVector<const SCEV *, 8> Ops;
5154 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
5155 if (i != FoundIndex)
5156 Ops.push_back(SCEVBackedgeConditionFolder::rewrite(Add->getOperand(i),
5157 L, *this));
5158 const SCEV *Accum = getAddExpr(Ops);
5159
5160 // This is not a valid addrec if the step amount is varying each
5161 // loop iteration, but is not itself an addrec in this loop.
5162 if (isLoopInvariant(Accum, L) ||
5163 (isa<SCEVAddRecExpr>(Accum) &&
5164 cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) {
5165 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
5166
5167 if (auto BO = MatchBinaryOp(BEValueV, DT)) {
5168 if (BO->Opcode == Instruction::Add && BO->LHS == PN) {
5169 if (BO->IsNUW)
5170 Flags = setFlags(Flags, SCEV::FlagNUW);
5171 if (BO->IsNSW)
5172 Flags = setFlags(Flags, SCEV::FlagNSW);
5173 }
5174 } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(BEValueV)) {
5175 // If the increment is an inbounds GEP, then we know the address
5176 // space cannot be wrapped around. We cannot make any guarantee
5177 // about signed or unsigned overflow because pointers are
5178 // unsigned but we may have a negative index from the base
5179 // pointer. We can guarantee that no unsigned wrap occurs if the
5180 // indices form a positive value.
5181 if (GEP->isInBounds() && GEP->getOperand(0) == PN) {
5182 Flags = setFlags(Flags, SCEV::FlagNW);
5183
5184 const SCEV *Ptr = getSCEV(GEP->getPointerOperand());
5185 if (isKnownPositive(getMinusSCEV(getSCEV(GEP), Ptr)))
5186 Flags = setFlags(Flags, SCEV::FlagNUW);
5187 }
5188
5189 // We cannot transfer nuw and nsw flags from subtraction
5190 // operations -- sub nuw X, Y is not the same as add nuw X, -Y
5191 // for instance.
5192 }
5193
5194 const SCEV *StartVal = getSCEV(StartValueV);
5195 const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
5196
5197 // Okay, for the entire analysis of this edge we assumed the PHI
5198 // to be symbolic. We now need to go back and purge all of the
5199 // entries for the scalars that use the symbolic expression.
5200 forgetSymbolicName(PN, SymbolicName);
5201 ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV;
5202
5203 // We can add Flags to the post-inc expression only if we
5204 // know that it is *undefined behavior* for BEValueV to
5205 // overflow.
5206 if (auto *BEInst = dyn_cast<Instruction>(BEValueV))
5207 if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L))
5208 (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
5209
5210 return PHISCEV;
5211 }
5212 }
5213 } else {
5214 // Otherwise, this could be a loop like this:
5215 // i = 0; for (j = 1; ..; ++j) { .... i = j; }
5216 // In this case, j = {1,+,1} and BEValue is j.
5217 // Because the other in-value of i (0) fits the evolution of BEValue
5218 // i really is an addrec evolution.
5219 //
5220 // We can generalize this saying that i is the shifted value of BEValue
5221 // by one iteration:
5222 // PHI(f(0), f({1,+,1})) --> f({0,+,1})
5223 const SCEV *Shifted = SCEVShiftRewriter::rewrite(BEValue, L, *this);
5224 const SCEV *Start = SCEVInitRewriter::rewrite(Shifted, L, *this, false);
5225 if (Shifted != getCouldNotCompute() &&
5226 Start != getCouldNotCompute()) {
5227 const SCEV *StartVal = getSCEV(StartValueV);
5228 if (Start == StartVal) {
5229 // Okay, for the entire analysis of this edge we assumed the PHI
5230 // to be symbolic. We now need to go back and purge all of the
5231 // entries for the scalars that use the symbolic expression.
5232 forgetSymbolicName(PN, SymbolicName);
5233 ValueExprMap[SCEVCallbackVH(PN, this)] = Shifted;
5234 return Shifted;
5235 }
5236 }
5237 }
5238
5239 // Remove the temporary PHI node SCEV that has been inserted while intending
5240 // to create an AddRecExpr for this PHI node. We can not keep this temporary
5241 // as it will prevent later (possibly simpler) SCEV expressions to be added
5242 // to the ValueExprMap.
5243 eraseValueFromMap(PN);
5244
5245 return nullptr;
5246}
5247
5248// Checks if the SCEV S is available at BB. S is considered available at BB
5249// if S can be materialized at BB without introducing a fault.
5250static bool IsAvailableOnEntry(const Loop *L, DominatorTree &DT, const SCEV *S,
5251 BasicBlock *BB) {
5252 struct CheckAvailable {
5253 bool TraversalDone = false;
5254 bool Available = true;
5255
5256 const Loop *L = nullptr; // The loop BB is in (can be nullptr)
5257 BasicBlock *BB = nullptr;
5258 DominatorTree &DT;
5259
5260 CheckAvailable(const Loop *L, BasicBlock *BB, DominatorTree &DT)
5261 : L(L), BB(BB), DT(DT) {}
5262
5263 bool setUnavailable() {
5264 TraversalDone = true;
5265 Available = false;
5266 return false;
5267 }
5268
5269 bool follow(const SCEV *S) {
5270 switch (S->getSCEVType()) {
5271 case scConstant:
5272 case scPtrToInt:
5273 case scTruncate:
5274 case scZeroExtend:
5275 case scSignExtend:
5276 case scAddExpr:
5277 case scMulExpr:
5278 case scUMaxExpr:
5279 case scSMaxExpr:
5280 case scUMinExpr:
5281 case scSMinExpr:
5282 // These expressions are available if their operand(s) is/are.
5283 return true;
5284
5285 case scAddRecExpr: {
5286 // We allow add recurrences that are on the loop BB is in, or some
5287 // outer loop. This guarantees availability because the value of the
5288 // add recurrence at BB is simply the "current" value of the induction
5289 // variable. We can relax this in the future; for instance an add
5290 // recurrence on a sibling dominating loop is also available at BB.
5291 const auto *ARLoop = cast<SCEVAddRecExpr>(S)->getLoop();
5292 if (L && (ARLoop == L || ARLoop->contains(L)))
5293 return true;
5294
5295 return setUnavailable();
5296 }
5297
5298 case scUnknown: {
5299 // For SCEVUnknown, we check for simple dominance.
5300 const auto *SU = cast<SCEVUnknown>(S);
5301 Value *V = SU->getValue();
5302
5303 if (isa<Argument>(V))
5304 return false;
5305
5306 if (isa<Instruction>(V) && DT.dominates(cast<Instruction>(V), BB))
5307 return false;
5308
5309 return setUnavailable();
5310 }
5311
5312 case scUDivExpr:
5313 case scCouldNotCompute:
5314 // We do not try to smart about these at all.
5315 return setUnavailable();
5316 }
5317 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5317)
;
5318 }
5319
5320 bool isDone() { return TraversalDone; }
5321 };
5322
5323 CheckAvailable CA(L, BB, DT);
5324 SCEVTraversal<CheckAvailable> ST(CA);
5325
5326 ST.visitAll(S);
5327 return CA.Available;
5328}
5329
5330// Try to match a control flow sequence that branches out at BI and merges back
5331// at Merge into a "C ? LHS : RHS" select pattern. Return true on a successful
5332// match.
5333static bool BrPHIToSelect(DominatorTree &DT, BranchInst *BI, PHINode *Merge,
5334 Value *&C, Value *&LHS, Value *&RHS) {
5335 C = BI->getCondition();
5336
5337 BasicBlockEdge LeftEdge(BI->getParent(), BI->getSuccessor(0));
5338 BasicBlockEdge RightEdge(BI->getParent(), BI->getSuccessor(1));
5339
5340 if (!LeftEdge.isSingleEdge())
5341 return false;
5342
5343 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5343, __PRETTY_FUNCTION__))
;
5344
5345 Use &LeftUse = Merge->getOperandUse(0);
5346 Use &RightUse = Merge->getOperandUse(1);
5347
5348 if (DT.dominates(LeftEdge, LeftUse) && DT.dominates(RightEdge, RightUse)) {
5349 LHS = LeftUse;
5350 RHS = RightUse;
5351 return true;
5352 }
5353
5354 if (DT.dominates(LeftEdge, RightUse) && DT.dominates(RightEdge, LeftUse)) {
5355 LHS = RightUse;
5356 RHS = LeftUse;
5357 return true;
5358 }
5359
5360 return false;
5361}
5362
5363const SCEV *ScalarEvolution::createNodeFromSelectLikePHI(PHINode *PN) {
5364 auto IsReachable =
5365 [&](BasicBlock *BB) { return DT.isReachableFromEntry(BB); };
5366 if (PN->getNumIncomingValues() == 2 && all_of(PN->blocks(), IsReachable)) {
5367 const Loop *L = LI.getLoopFor(PN->getParent());
5368
5369 // We don't want to break LCSSA, even in a SCEV expression tree.
5370 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
5371 if (LI.getLoopFor(PN->getIncomingBlock(i)) != L)
5372 return nullptr;
5373
5374 // Try to match
5375 //
5376 // br %cond, label %left, label %right
5377 // left:
5378 // br label %merge
5379 // right:
5380 // br label %merge
5381 // merge:
5382 // V = phi [ %x, %left ], [ %y, %right ]
5383 //
5384 // as "select %cond, %x, %y"
5385
5386 BasicBlock *IDom = DT[PN->getParent()]->getIDom()->getBlock();
5387 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5387, __PRETTY_FUNCTION__))
;
5388
5389 auto *BI = dyn_cast<BranchInst>(IDom->getTerminator());
5390 Value *Cond = nullptr, *LHS = nullptr, *RHS = nullptr;
5391
5392 if (BI && BI->isConditional() &&
5393 BrPHIToSelect(DT, BI, PN, Cond, LHS, RHS) &&
5394 IsAvailableOnEntry(L, DT, getSCEV(LHS), PN->getParent()) &&
5395 IsAvailableOnEntry(L, DT, getSCEV(RHS), PN->getParent()))
5396 return createNodeForSelectOrPHI(PN, Cond, LHS, RHS);
5397 }
5398
5399 return nullptr;
5400}
5401
5402const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) {
5403 if (const SCEV *S = createAddRecFromPHI(PN))
5404 return S;
5405
5406 if (const SCEV *S = createNodeFromSelectLikePHI(PN))
5407 return S;
5408
5409 // If the PHI has a single incoming value, follow that value, unless the
5410 // PHI's incoming blocks are in a different loop, in which case doing so
5411 // risks breaking LCSSA form. Instcombine would normally zap these, but
5412 // it doesn't have DominatorTree information, so it may miss cases.
5413 if (Value *V = SimplifyInstruction(PN, {getDataLayout(), &TLI, &DT, &AC}))
5414 if (LI.replacementPreservesLCSSAForm(PN, V))
5415 return getSCEV(V);
5416
5417 // If it's not a loop phi, we can't handle it yet.
5418 return getUnknown(PN);
5419}
5420
5421const SCEV *ScalarEvolution::createNodeForSelectOrPHI(Instruction *I,
5422 Value *Cond,
5423 Value *TrueVal,
5424 Value *FalseVal) {
5425 // Handle "constant" branch or select. This can occur for instance when a
5426 // loop pass transforms an inner loop and moves on to process the outer loop.
5427 if (auto *CI = dyn_cast<ConstantInt>(Cond))
5428 return getSCEV(CI->isOne() ? TrueVal : FalseVal);
5429
5430 // Try to match some simple smax or umax patterns.
5431 auto *ICI = dyn_cast<ICmpInst>(Cond);
5432 if (!ICI)
5433 return getUnknown(I);
5434
5435 Value *LHS = ICI->getOperand(0);
5436 Value *RHS = ICI->getOperand(1);
5437
5438 switch (ICI->getPredicate()) {
5439 case ICmpInst::ICMP_SLT:
5440 case ICmpInst::ICMP_SLE:
5441 std::swap(LHS, RHS);
5442 LLVM_FALLTHROUGH[[gnu::fallthrough]];
5443 case ICmpInst::ICMP_SGT:
5444 case ICmpInst::ICMP_SGE:
5445 // a >s b ? a+x : b+x -> smax(a, b)+x
5446 // a >s b ? b+x : a+x -> smin(a, b)+x
5447 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
5448 const SCEV *LS = getNoopOrSignExtend(getSCEV(LHS), I->getType());
5449 const SCEV *RS = getNoopOrSignExtend(getSCEV(RHS), I->getType());
5450 const SCEV *LA = getSCEV(TrueVal);
5451 const SCEV *RA = getSCEV(FalseVal);
5452 const SCEV *LDiff = getMinusSCEV(LA, LS);
5453 const SCEV *RDiff = getMinusSCEV(RA, RS);
5454 if (LDiff == RDiff)
5455 return getAddExpr(getSMaxExpr(LS, RS), LDiff);
5456 LDiff = getMinusSCEV(LA, RS);
5457 RDiff = getMinusSCEV(RA, LS);
5458 if (LDiff == RDiff)
5459 return getAddExpr(getSMinExpr(LS, RS), LDiff);
5460 }
5461 break;
5462 case ICmpInst::ICMP_ULT:
5463 case ICmpInst::ICMP_ULE:
5464 std::swap(LHS, RHS);
5465 LLVM_FALLTHROUGH[[gnu::fallthrough]];
5466 case ICmpInst::ICMP_UGT:
5467 case ICmpInst::ICMP_UGE:
5468 // a >u b ? a+x : b+x -> umax(a, b)+x
5469 // a >u b ? b+x : a+x -> umin(a, b)+x
5470 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
5471 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5472 const SCEV *RS = getNoopOrZeroExtend(getSCEV(RHS), I->getType());
5473 const SCEV *LA = getSCEV(TrueVal);
5474 const SCEV *RA = getSCEV(FalseVal);
5475 const SCEV *LDiff = getMinusSCEV(LA, LS);
5476 const SCEV *RDiff = getMinusSCEV(RA, RS);
5477 if (LDiff == RDiff)
5478 return getAddExpr(getUMaxExpr(LS, RS), LDiff);
5479 LDiff = getMinusSCEV(LA, RS);
5480 RDiff = getMinusSCEV(RA, LS);
5481 if (LDiff == RDiff)
5482 return getAddExpr(getUMinExpr(LS, RS), LDiff);
5483 }
5484 break;
5485 case ICmpInst::ICMP_NE:
5486 // n != 0 ? n+x : 1+x -> umax(n, 1)+x
5487 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
5488 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
5489 const SCEV *One = getOne(I->getType());
5490 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5491 const SCEV *LA = getSCEV(TrueVal);
5492 const SCEV *RA = getSCEV(FalseVal);
5493 const SCEV *LDiff = getMinusSCEV(LA, LS);
5494 const SCEV *RDiff = getMinusSCEV(RA, One);
5495 if (LDiff == RDiff)
5496 return getAddExpr(getUMaxExpr(One, LS), LDiff);
5497 }
5498 break;
5499 case ICmpInst::ICMP_EQ:
5500 // n == 0 ? 1+x : n+x -> umax(n, 1)+x
5501 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
5502 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
5503 const SCEV *One = getOne(I->getType());
5504 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5505 const SCEV *LA = getSCEV(TrueVal);
5506 const SCEV *RA = getSCEV(FalseVal);
5507 const SCEV *LDiff = getMinusSCEV(LA, One);
5508 const SCEV *RDiff = getMinusSCEV(RA, LS);
5509 if (LDiff == RDiff)
5510 return getAddExpr(getUMaxExpr(One, LS), LDiff);
5511 }
5512 break;
5513 default:
5514 break;
5515 }
5516
5517 return getUnknown(I);
5518}
5519
5520/// Expand GEP instructions into add and multiply operations. This allows them
5521/// to be analyzed by regular SCEV code.
5522const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) {
5523 // Don't attempt to analyze GEPs over unsized objects.
5524 if (!GEP->getSourceElementType()->isSized())
5525 return getUnknown(GEP);
5526
5527 SmallVector<const SCEV *, 4> IndexExprs;
5528 for (auto Index = GEP->idx_begin(); Index != GEP->idx_end(); ++Index)
5529 IndexExprs.push_back(getSCEV(*Index));
5530 return getGEPExpr(GEP, IndexExprs);
5531}
5532
5533uint32_t ScalarEvolution::GetMinTrailingZerosImpl(const SCEV *S) {
5534 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
5535 return C->getAPInt().countTrailingZeros();
5536
5537 if (const SCEVPtrToIntExpr *I = dyn_cast<SCEVPtrToIntExpr>(S))
5538 return GetMinTrailingZeros(I->getOperand());
5539
5540 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(S))
5541 return std::min(GetMinTrailingZeros(T->getOperand()),
5542 (uint32_t)getTypeSizeInBits(T->getType()));
5543
5544 if (const SCEVZeroExtendExpr *E = dyn_cast<SCEVZeroExtendExpr>(S)) {
5545 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
5546 return OpRes == getTypeSizeInBits(E->getOperand()->getType())
5547 ? getTypeSizeInBits(E->getType())
5548 : OpRes;
5549 }
5550
5551 if (const SCEVSignExtendExpr *E = dyn_cast<SCEVSignExtendExpr>(S)) {
5552 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
5553 return OpRes == getTypeSizeInBits(E->getOperand()->getType())
5554 ? getTypeSizeInBits(E->getType())
5555 : OpRes;
5556 }
5557
5558 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) {
5559 // The result is the min of all operands results.
5560 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
5561 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
5562 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
5563 return MinOpRes;
5564 }
5565
5566 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
5567 // The result is the sum of all operands results.
5568 uint32_t SumOpRes = GetMinTrailingZeros(M->getOperand(0));
5569 uint32_t BitWidth = getTypeSizeInBits(M->getType());
5570 for (unsigned i = 1, e = M->getNumOperands();
5571 SumOpRes != BitWidth && i != e; ++i)
5572 SumOpRes =
5573 std::min(SumOpRes + GetMinTrailingZeros(M->getOperand(i)), BitWidth);
5574 return SumOpRes;
5575 }
5576
5577 if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
5578 // The result is the min of all operands results.
5579 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
5580 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
5581 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
5582 return MinOpRes;
5583 }
5584
5585 if (const SCEVSMaxExpr *M = dyn_cast<SCEVSMaxExpr>(S)) {
5586 // The result is the min of all operands results.
5587 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
5588 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
5589 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
5590 return MinOpRes;
5591 }
5592
5593 if (const SCEVUMaxExpr *M = dyn_cast<SCEVUMaxExpr>(S)) {
5594 // The result is the min of all operands results.
5595 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
5596 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
5597 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
5598 return MinOpRes;
5599 }
5600
5601 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
5602 // For a SCEVUnknown, ask ValueTracking.
5603 KnownBits Known = computeKnownBits(U->getValue(), getDataLayout(), 0, &AC, nullptr, &DT);
5604 return Known.countMinTrailingZeros();
5605 }
5606
5607 // SCEVUDivExpr
5608 return 0;
5609}
5610
5611uint32_t ScalarEvolution::GetMinTrailingZeros(const SCEV *S) {
5612 auto I = MinTrailingZerosCache.find(S);
5613 if (I != MinTrailingZerosCache.end())
5614 return I->second;
5615
5616 uint32_t Result = GetMinTrailingZerosImpl(S);
5617 auto InsertPair = MinTrailingZerosCache.insert({S, Result});
5618 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5618, __PRETTY_FUNCTION__))
;
5619 return InsertPair.first->second;
5620}
5621
5622/// Helper method to assign a range to V from metadata present in the IR.
5623static Optional<ConstantRange> GetRangeFromMetadata(Value *V) {
5624 if (Instruction *I = dyn_cast<Instruction>(V))
5625 if (MDNode *MD = I->getMetadata(LLVMContext::MD_range))
5626 return getConstantRangeFromMetadata(*MD);
5627
5628 return None;
5629}
5630
5631void ScalarEvolution::setNoWrapFlags(SCEVAddRecExpr *AddRec,
5632 SCEV::NoWrapFlags Flags) {
5633 if (AddRec->getNoWrapFlags(Flags) != Flags) {
5634 AddRec->setNoWrapFlags(Flags);
5635 UnsignedRanges.erase(AddRec);
5636 SignedRanges.erase(AddRec);
5637 }
5638}
5639
5640/// Determine the range for a particular SCEV. If SignHint is
5641/// HINT_RANGE_UNSIGNED (resp. HINT_RANGE_SIGNED) then getRange prefers ranges
5642/// with a "cleaner" unsigned (resp. signed) representation.
5643const ConstantRange &
5644ScalarEvolution::getRangeRef(const SCEV *S,
5645 ScalarEvolution::RangeSignHint SignHint) {
5646 DenseMap<const SCEV *, ConstantRange> &Cache =
5647 SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED ? UnsignedRanges
5648 : SignedRanges;
5649 ConstantRange::PreferredRangeType RangeType =
5650 SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED
5651 ? ConstantRange::Unsigned : ConstantRange::Signed;
5652
5653 // See if we've computed this range already.
5654 DenseMap<const SCEV *, ConstantRange>::iterator I = Cache.find(S);
5655 if (I != Cache.end())
5656 return I->second;
5657
5658 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
5659 return setRange(C, SignHint, ConstantRange(C->getAPInt()));