1//===- InstCombineInternal.h - InstCombine pass internals -------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9/// \file
10///
11/// This file provides internal interfaces used to implement the InstCombine.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_LIB_TRANSFORMS_INSTCOMBINE_INSTCOMBINEINTERNAL_H
16#define LLVM_LIB_TRANSFORMS_INSTCOMBINE_INSTCOMBINEINTERNAL_H
17
18#include "llvm/ADT/Statistic.h"
19#include "llvm/ADT/PostOrderIterator.h"
20#include "llvm/Analysis/InstructionSimplify.h"
21#include "llvm/Analysis/TargetFolder.h"
22#include "llvm/Analysis/ValueTracking.h"
23#include "llvm/IR/IRBuilder.h"
24#include "llvm/IR/InstVisitor.h"
25#include "llvm/IR/PatternMatch.h"
26#include "llvm/IR/Value.h"
27#include "llvm/Support/Debug.h"
28#include "llvm/Support/KnownBits.h"
29#include "llvm/Transforms/InstCombine/InstCombiner.h"
30#include "llvm/Transforms/Utils/Local.h"
31#include <cassert>
32
33#define DEBUG_TYPE "instcombine"
34#include "llvm/Transforms/Utils/InstructionWorklist.h"
35
36using namespace llvm::PatternMatch;
37
38// As a default, let's assume that we want to be aggressive,
39// and attempt to traverse with no limits in attempt to sink negation.
40static constexpr unsigned NegatorDefaultMaxDepth = ~0U;
41
42// Let's guesstimate that most often we will end up visiting/producing
43// fairly small number of new instructions.
44static constexpr unsigned NegatorMaxNodesSSO = 16;
45
46namespace llvm {
47
48class AAResults;
49class APInt;
50class AssumptionCache;
51class BlockFrequencyInfo;
52class DataLayout;
53class DominatorTree;
54class GEPOperator;
55class GlobalVariable;
56class LoopInfo;
57class OptimizationRemarkEmitter;
58class ProfileSummaryInfo;
59class TargetLibraryInfo;
60class User;
61
62class LLVM_LIBRARY_VISIBILITY InstCombinerImpl final
63 : public InstCombiner,
64 public InstVisitor<InstCombinerImpl, Instruction *> {
65public:
66 InstCombinerImpl(InstructionWorklist &Worklist, BuilderTy &Builder,
67 bool MinimizeSize, AAResults *AA, AssumptionCache &AC,
68 TargetLibraryInfo &TLI, TargetTransformInfo &TTI,
69 DominatorTree &DT, OptimizationRemarkEmitter &ORE,
70 BlockFrequencyInfo *BFI, BranchProbabilityInfo *BPI,
71 ProfileSummaryInfo *PSI, const DataLayout &DL, LoopInfo *LI)
72 : InstCombiner(Worklist, Builder, MinimizeSize, AA, AC, TLI, TTI, DT, ORE,
73 BFI, BPI, PSI, DL, LI) {}
74
75 virtual ~InstCombinerImpl() = default;
76
77 /// Perform early cleanup and prepare the InstCombine worklist.
78 bool prepareWorklist(Function &F,
79 ReversePostOrderTraversal<BasicBlock *> &RPOT);
80
81 /// Run the combiner over the entire worklist until it is empty.
82 ///
83 /// \returns true if the IR is changed.
84 bool run();
85
86 // Visitation implementation - Implement instruction combining for different
87 // instruction types. The semantics are as follows:
88 // Return Value:
89 // null - No change was made
90 // I - Change was made, I is still valid, I may be dead though
91 // otherwise - Change was made, replace I with returned instruction
92 //
93 Instruction *visitFNeg(UnaryOperator &I);
94 Instruction *visitAdd(BinaryOperator &I);
95 Instruction *visitFAdd(BinaryOperator &I);
96 Value *OptimizePointerDifference(
97 Value *LHS, Value *RHS, Type *Ty, bool isNUW);
98 Instruction *visitSub(BinaryOperator &I);
99 Instruction *visitFSub(BinaryOperator &I);
100 Instruction *visitMul(BinaryOperator &I);
101 Instruction *foldPowiReassoc(BinaryOperator &I);
102 Instruction *foldFMulReassoc(BinaryOperator &I);
103 Instruction *visitFMul(BinaryOperator &I);
104 Instruction *visitURem(BinaryOperator &I);
105 Instruction *visitSRem(BinaryOperator &I);
106 Instruction *visitFRem(BinaryOperator &I);
107 bool simplifyDivRemOfSelectWithZeroOp(BinaryOperator &I);
108 Instruction *commonIRemTransforms(BinaryOperator &I);
109 Instruction *commonIDivTransforms(BinaryOperator &I);
110 Instruction *visitUDiv(BinaryOperator &I);
111 Instruction *visitSDiv(BinaryOperator &I);
112 Instruction *visitFDiv(BinaryOperator &I);
113 Value *simplifyRangeCheck(ICmpInst *Cmp0, ICmpInst *Cmp1, bool Inverted);
114 Instruction *visitAnd(BinaryOperator &I);
115 Instruction *visitOr(BinaryOperator &I);
116 bool sinkNotIntoLogicalOp(Instruction &I);
117 bool sinkNotIntoOtherHandOfLogicalOp(Instruction &I);
118 Instruction *visitXor(BinaryOperator &I);
119 Instruction *visitShl(BinaryOperator &I);
120 Value *reassociateShiftAmtsOfTwoSameDirectionShifts(
121 BinaryOperator *Sh0, const SimplifyQuery &SQ,
122 bool AnalyzeForSignBitExtraction = false);
123 Instruction *canonicalizeCondSignextOfHighBitExtractToSignextHighBitExtract(
124 BinaryOperator &I);
125 Instruction *foldVariableSignZeroExtensionOfVariableHighBitExtract(
126 BinaryOperator &OldAShr);
127 Instruction *visitAShr(BinaryOperator &I);
128 Instruction *visitLShr(BinaryOperator &I);
129 Instruction *commonShiftTransforms(BinaryOperator &I);
130 Instruction *visitFCmpInst(FCmpInst &I);
131 CmpInst *canonicalizeICmpPredicate(CmpInst &I);
132 Instruction *visitICmpInst(ICmpInst &I);
133 Instruction *FoldShiftByConstant(Value *Op0, Constant *Op1,
134 BinaryOperator &I);
135 Instruction *commonCastTransforms(CastInst &CI);
136 Instruction *visitTrunc(TruncInst &CI);
137 Instruction *visitZExt(ZExtInst &Zext);
138 Instruction *visitSExt(SExtInst &Sext);
139 Instruction *visitFPTrunc(FPTruncInst &CI);
140 Instruction *visitFPExt(CastInst &CI);
141 Instruction *visitFPToUI(FPToUIInst &FI);
142 Instruction *visitFPToSI(FPToSIInst &FI);
143 Instruction *visitUIToFP(CastInst &CI);
144 Instruction *visitSIToFP(CastInst &CI);
145 Instruction *visitPtrToInt(PtrToIntInst &CI);
146 Instruction *visitIntToPtr(IntToPtrInst &CI);
147 Instruction *visitBitCast(BitCastInst &CI);
148 Instruction *visitAddrSpaceCast(AddrSpaceCastInst &CI);
149 Instruction *foldItoFPtoI(CastInst &FI);
150 Instruction *visitSelectInst(SelectInst &SI);
151 Instruction *visitCallInst(CallInst &CI);
152 Instruction *visitInvokeInst(InvokeInst &II);
153 Instruction *visitCallBrInst(CallBrInst &CBI);
154
155 Instruction *SliceUpIllegalIntegerPHI(PHINode &PN);
156 Instruction *visitPHINode(PHINode &PN);
157 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
158 Instruction *visitGEPOfGEP(GetElementPtrInst &GEP, GEPOperator *Src);
159 Instruction *visitAllocaInst(AllocaInst &AI);
160 Instruction *visitAllocSite(Instruction &FI);
161 Instruction *visitFree(CallInst &FI, Value *FreedOp);
162 Instruction *visitLoadInst(LoadInst &LI);
163 Instruction *visitStoreInst(StoreInst &SI);
164 Instruction *visitAtomicRMWInst(AtomicRMWInst &SI);
165 Instruction *visitUnconditionalBranchInst(BranchInst &BI);
166 Instruction *visitBranchInst(BranchInst &BI);
167 Instruction *visitFenceInst(FenceInst &FI);
168 Instruction *visitSwitchInst(SwitchInst &SI);
169 Instruction *visitReturnInst(ReturnInst &RI);
170 Instruction *visitUnreachableInst(UnreachableInst &I);
171 Instruction *
172 foldAggregateConstructionIntoAggregateReuse(InsertValueInst &OrigIVI);
173 Instruction *visitInsertValueInst(InsertValueInst &IV);
174 Instruction *visitInsertElementInst(InsertElementInst &IE);
175 Instruction *visitExtractElementInst(ExtractElementInst &EI);
176 Instruction *simplifyBinOpSplats(ShuffleVectorInst &SVI);
177 Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
178 Instruction *visitExtractValueInst(ExtractValueInst &EV);
179 Instruction *visitLandingPadInst(LandingPadInst &LI);
180 Instruction *visitVAEndInst(VAEndInst &I);
181 Value *pushFreezeToPreventPoisonFromPropagating(FreezeInst &FI);
182 bool freezeOtherUses(FreezeInst &FI);
183 Instruction *foldFreezeIntoRecurrence(FreezeInst &I, PHINode *PN);
184 Instruction *visitFreeze(FreezeInst &I);
185
186 /// Specify what to return for unhandled instructions.
187 Instruction *visitInstruction(Instruction &I) { return nullptr; }
188
189 /// True when DB dominates all uses of DI except UI.
190 /// UI must be in the same block as DI.
191 /// The routine checks that the DI parent and DB are different.
192 bool dominatesAllUses(const Instruction *DI, const Instruction *UI,
193 const BasicBlock *DB) const;
194
195 /// Try to replace select with select operand SIOpd in SI-ICmp sequence.
196 bool replacedSelectWithOperand(SelectInst *SI, const ICmpInst *Icmp,
197 const unsigned SIOpd);
198
199 LoadInst *combineLoadToNewType(LoadInst &LI, Type *NewTy,
200 const Twine &Suffix = "");
201
202 KnownFPClass computeKnownFPClass(Value *Val, FastMathFlags FMF,
203 FPClassTest Interested = fcAllFlags,
204 const Instruction *CtxI = nullptr,
205 unsigned Depth = 0) const {
206 return llvm::computeKnownFPClass(
207 V: Val, FMF, InterestedClasses: Interested, Depth,
208 SQ: getSimplifyQuery().getWithInstruction(I: CtxI));
209 }
210
211 KnownFPClass computeKnownFPClass(Value *Val,
212 FPClassTest Interested = fcAllFlags,
213 const Instruction *CtxI = nullptr,
214 unsigned Depth = 0) const {
215 return llvm::computeKnownFPClass(
216 V: Val, InterestedClasses: Interested, Depth, SQ: getSimplifyQuery().getWithInstruction(I: CtxI));
217 }
218
219 /// Check if fmul \p MulVal, +0.0 will yield +0.0 (or signed zero is
220 /// ignorable).
221 bool fmulByZeroIsZero(Value *MulVal, FastMathFlags FMF,
222 const Instruction *CtxI) const;
223
224 Constant *getLosslessTrunc(Constant *C, Type *TruncTy, unsigned ExtOp) {
225 Constant *TruncC = ConstantExpr::getTrunc(C, Ty: TruncTy);
226 Constant *ExtTruncC =
227 ConstantFoldCastOperand(Opcode: ExtOp, C: TruncC, DestTy: C->getType(), DL);
228 if (ExtTruncC && ExtTruncC == C)
229 return TruncC;
230 return nullptr;
231 }
232
233 Constant *getLosslessUnsignedTrunc(Constant *C, Type *TruncTy) {
234 return getLosslessTrunc(C, TruncTy, ExtOp: Instruction::ZExt);
235 }
236
237 Constant *getLosslessSignedTrunc(Constant *C, Type *TruncTy) {
238 return getLosslessTrunc(C, TruncTy, ExtOp: Instruction::SExt);
239 }
240
241 std::optional<std::pair<Intrinsic::ID, SmallVector<Value *, 3>>>
242 convertOrOfShiftsToFunnelShift(Instruction &Or);
243
244private:
245 bool annotateAnyAllocSite(CallBase &Call, const TargetLibraryInfo *TLI);
246 bool isDesirableIntType(unsigned BitWidth) const;
247 bool shouldChangeType(unsigned FromBitWidth, unsigned ToBitWidth) const;
248 bool shouldChangeType(Type *From, Type *To) const;
249 Value *dyn_castNegVal(Value *V) const;
250
251 /// Classify whether a cast is worth optimizing.
252 ///
253 /// This is a helper to decide whether the simplification of
254 /// logic(cast(A), cast(B)) to cast(logic(A, B)) should be performed.
255 ///
256 /// \param CI The cast we are interested in.
257 ///
258 /// \return true if this cast actually results in any code being generated and
259 /// if it cannot already be eliminated by some other transformation.
260 bool shouldOptimizeCast(CastInst *CI);
261
262 /// Try to optimize a sequence of instructions checking if an operation
263 /// on LHS and RHS overflows.
264 ///
265 /// If this overflow check is done via one of the overflow check intrinsics,
266 /// then CtxI has to be the call instruction calling that intrinsic. If this
267 /// overflow check is done by arithmetic followed by a compare, then CtxI has
268 /// to be the arithmetic instruction.
269 ///
270 /// If a simplification is possible, stores the simplified result of the
271 /// operation in OperationResult and result of the overflow check in
272 /// OverflowResult, and return true. If no simplification is possible,
273 /// returns false.
274 bool OptimizeOverflowCheck(Instruction::BinaryOps BinaryOp, bool IsSigned,
275 Value *LHS, Value *RHS,
276 Instruction &CtxI, Value *&OperationResult,
277 Constant *&OverflowResult);
278
279 Instruction *visitCallBase(CallBase &Call);
280 Instruction *tryOptimizeCall(CallInst *CI);
281 bool transformConstExprCastCall(CallBase &Call);
282 Instruction *transformCallThroughTrampoline(CallBase &Call,
283 IntrinsicInst &Tramp);
284
285 // Return (a, b) if (LHS, RHS) is known to be (a, b) or (b, a).
286 // Otherwise, return std::nullopt
287 // Currently it matches:
288 // - LHS = (select c, a, b), RHS = (select c, b, a)
289 // - LHS = (phi [a, BB0], [b, BB1]), RHS = (phi [b, BB0], [a, BB1])
290 // - LHS = min(a, b), RHS = max(a, b)
291 std::optional<std::pair<Value *, Value *>> matchSymmetricPair(Value *LHS,
292 Value *RHS);
293
294 Value *simplifyMaskedLoad(IntrinsicInst &II);
295 Instruction *simplifyMaskedStore(IntrinsicInst &II);
296 Instruction *simplifyMaskedGather(IntrinsicInst &II);
297 Instruction *simplifyMaskedScatter(IntrinsicInst &II);
298
299 /// Transform (zext icmp) to bitwise / integer operations in order to
300 /// eliminate it.
301 ///
302 /// \param ICI The icmp of the (zext icmp) pair we are interested in.
303 /// \parem CI The zext of the (zext icmp) pair we are interested in.
304 ///
305 /// \return null if the transformation cannot be performed. If the
306 /// transformation can be performed the new instruction that replaces the
307 /// (zext icmp) pair will be returned.
308 Instruction *transformZExtICmp(ICmpInst *Cmp, ZExtInst &Zext);
309
310 Instruction *transformSExtICmp(ICmpInst *Cmp, SExtInst &Sext);
311
312 bool willNotOverflowSignedAdd(const WithCache<const Value *> &LHS,
313 const WithCache<const Value *> &RHS,
314 const Instruction &CxtI) const {
315 return computeOverflowForSignedAdd(LHS, RHS, CxtI: &CxtI) ==
316 OverflowResult::NeverOverflows;
317 }
318
319 bool willNotOverflowUnsignedAdd(const WithCache<const Value *> &LHS,
320 const WithCache<const Value *> &RHS,
321 const Instruction &CxtI) const {
322 return computeOverflowForUnsignedAdd(LHS, RHS, CxtI: &CxtI) ==
323 OverflowResult::NeverOverflows;
324 }
325
326 bool willNotOverflowAdd(const Value *LHS, const Value *RHS,
327 const Instruction &CxtI, bool IsSigned) const {
328 return IsSigned ? willNotOverflowSignedAdd(LHS, RHS, CxtI)
329 : willNotOverflowUnsignedAdd(LHS, RHS, CxtI);
330 }
331
332 bool willNotOverflowSignedSub(const Value *LHS, const Value *RHS,
333 const Instruction &CxtI) const {
334 return computeOverflowForSignedSub(LHS, RHS, CxtI: &CxtI) ==
335 OverflowResult::NeverOverflows;
336 }
337
338 bool willNotOverflowUnsignedSub(const Value *LHS, const Value *RHS,
339 const Instruction &CxtI) const {
340 return computeOverflowForUnsignedSub(LHS, RHS, CxtI: &CxtI) ==
341 OverflowResult::NeverOverflows;
342 }
343
344 bool willNotOverflowSub(const Value *LHS, const Value *RHS,
345 const Instruction &CxtI, bool IsSigned) const {
346 return IsSigned ? willNotOverflowSignedSub(LHS, RHS, CxtI)
347 : willNotOverflowUnsignedSub(LHS, RHS, CxtI);
348 }
349
350 bool willNotOverflowSignedMul(const Value *LHS, const Value *RHS,
351 const Instruction &CxtI) const {
352 return computeOverflowForSignedMul(LHS, RHS, CxtI: &CxtI) ==
353 OverflowResult::NeverOverflows;
354 }
355
356 bool willNotOverflowUnsignedMul(const Value *LHS, const Value *RHS,
357 const Instruction &CxtI,
358 bool IsNSW = false) const {
359 return computeOverflowForUnsignedMul(LHS, RHS, CxtI: &CxtI, IsNSW) ==
360 OverflowResult::NeverOverflows;
361 }
362
363 bool willNotOverflowMul(const Value *LHS, const Value *RHS,
364 const Instruction &CxtI, bool IsSigned) const {
365 return IsSigned ? willNotOverflowSignedMul(LHS, RHS, CxtI)
366 : willNotOverflowUnsignedMul(LHS, RHS, CxtI);
367 }
368
369 bool willNotOverflow(BinaryOperator::BinaryOps Opcode, const Value *LHS,
370 const Value *RHS, const Instruction &CxtI,
371 bool IsSigned) const {
372 switch (Opcode) {
373 case Instruction::Add: return willNotOverflowAdd(LHS, RHS, CxtI, IsSigned);
374 case Instruction::Sub: return willNotOverflowSub(LHS, RHS, CxtI, IsSigned);
375 case Instruction::Mul: return willNotOverflowMul(LHS, RHS, CxtI, IsSigned);
376 default: llvm_unreachable("Unexpected opcode for overflow query");
377 }
378 }
379
380 Value *EmitGEPOffset(GEPOperator *GEP, bool RewriteGEP = false);
381 Instruction *scalarizePHI(ExtractElementInst &EI, PHINode *PN);
382 Instruction *foldBitcastExtElt(ExtractElementInst &ExtElt);
383 Instruction *foldCastedBitwiseLogic(BinaryOperator &I);
384 Instruction *foldFBinOpOfIntCasts(BinaryOperator &I);
385 // Should only be called by `foldFBinOpOfIntCasts`.
386 Instruction *foldFBinOpOfIntCastsFromSign(
387 BinaryOperator &BO, bool OpsFromSigned, std::array<Value *, 2> IntOps,
388 Constant *Op1FpC, SmallVectorImpl<WithCache<const Value *>> &OpsKnown);
389 Instruction *foldBinopOfSextBoolToSelect(BinaryOperator &I);
390 Instruction *narrowBinOp(TruncInst &Trunc);
391 Instruction *narrowMaskedBinOp(BinaryOperator &And);
392 Instruction *narrowMathIfNoOverflow(BinaryOperator &I);
393 Instruction *narrowFunnelShift(TruncInst &Trunc);
394 Instruction *optimizeBitCastFromPhi(CastInst &CI, PHINode *PN);
395 Instruction *matchSAddSubSat(IntrinsicInst &MinMax1);
396 Instruction *foldNot(BinaryOperator &I);
397 Instruction *foldBinOpOfDisplacedShifts(BinaryOperator &I);
398
399 /// Determine if a pair of casts can be replaced by a single cast.
400 ///
401 /// \param CI1 The first of a pair of casts.
402 /// \param CI2 The second of a pair of casts.
403 ///
404 /// \return 0 if the cast pair cannot be eliminated, otherwise returns an
405 /// Instruction::CastOps value for a cast that can replace the pair, casting
406 /// CI1->getSrcTy() to CI2->getDstTy().
407 ///
408 /// \see CastInst::isEliminableCastPair
409 Instruction::CastOps isEliminableCastPair(const CastInst *CI1,
410 const CastInst *CI2);
411 Value *simplifyIntToPtrRoundTripCast(Value *Val);
412
413 Value *foldAndOrOfICmps(ICmpInst *LHS, ICmpInst *RHS, Instruction &I,
414 bool IsAnd, bool IsLogical = false);
415 Value *foldXorOfICmps(ICmpInst *LHS, ICmpInst *RHS, BinaryOperator &Xor);
416
417 Value *foldEqOfParts(ICmpInst *Cmp0, ICmpInst *Cmp1, bool IsAnd);
418
419 Value *foldAndOrOfICmpsUsingRanges(ICmpInst *ICmp1, ICmpInst *ICmp2,
420 bool IsAnd);
421
422 /// Optimize (fcmp)&(fcmp) or (fcmp)|(fcmp).
423 /// NOTE: Unlike most of instcombine, this returns a Value which should
424 /// already be inserted into the function.
425 Value *foldLogicOfFCmps(FCmpInst *LHS, FCmpInst *RHS, bool IsAnd,
426 bool IsLogicalSelect = false);
427
428 Instruction *foldLogicOfIsFPClass(BinaryOperator &Operator, Value *LHS,
429 Value *RHS);
430
431 Instruction *
432 canonicalizeConditionalNegationViaMathToSelect(BinaryOperator &i);
433
434 Value *foldAndOrOfICmpsOfAndWithPow2(ICmpInst *LHS, ICmpInst *RHS,
435 Instruction *CxtI, bool IsAnd,
436 bool IsLogical = false);
437 Value *matchSelectFromAndOr(Value *A, Value *B, Value *C, Value *D,
438 bool InvertFalseVal = false);
439 Value *getSelectCondition(Value *A, Value *B, bool ABIsTheSame);
440
441 Instruction *foldLShrOverflowBit(BinaryOperator &I);
442 Instruction *foldExtractOfOverflowIntrinsic(ExtractValueInst &EV);
443 Instruction *foldIntrinsicWithOverflowCommon(IntrinsicInst *II);
444 Instruction *foldIntrinsicIsFPClass(IntrinsicInst &II);
445 Instruction *foldFPSignBitOps(BinaryOperator &I);
446 Instruction *foldFDivConstantDivisor(BinaryOperator &I);
447
448 // Optimize one of these forms:
449 // and i1 Op, SI / select i1 Op, i1 SI, i1 false (if IsAnd = true)
450 // or i1 Op, SI / select i1 Op, i1 true, i1 SI (if IsAnd = false)
451 // into simplier select instruction using isImpliedCondition.
452 Instruction *foldAndOrOfSelectUsingImpliedCond(Value *Op, SelectInst &SI,
453 bool IsAnd);
454
455 Instruction *hoistFNegAboveFMulFDiv(Value *FNegOp, Instruction &FMFSource);
456
457public:
458 /// Create and insert the idiom we use to indicate a block is unreachable
459 /// without having to rewrite the CFG from within InstCombine.
460 void CreateNonTerminatorUnreachable(Instruction *InsertAt) {
461 auto &Ctx = InsertAt->getContext();
462 auto *SI = new StoreInst(ConstantInt::getTrue(Context&: Ctx),
463 PoisonValue::get(T: PointerType::getUnqual(C&: Ctx)),
464 /*isVolatile*/ false, Align(1));
465 InsertNewInstWith(New: SI, Old: InsertAt->getIterator());
466 }
467
468 /// Combiner aware instruction erasure.
469 ///
470 /// When dealing with an instruction that has side effects or produces a void
471 /// value, we can't rely on DCE to delete the instruction. Instead, visit
472 /// methods should return the value returned by this function.
473 Instruction *eraseInstFromFunction(Instruction &I) override {
474 LLVM_DEBUG(dbgs() << "IC: ERASE " << I << '\n');
475 assert(I.use_empty() && "Cannot erase instruction that is used!");
476 salvageDebugInfo(I);
477
478 // Make sure that we reprocess all operands now that we reduced their
479 // use counts.
480 SmallVector<Value *> Ops(I.operands());
481 Worklist.remove(I: &I);
482 DC.removeValue(V: &I);
483 I.eraseFromParent();
484 for (Value *Op : Ops)
485 Worklist.handleUseCountDecrement(V: Op);
486 MadeIRChange = true;
487 return nullptr; // Don't do anything with FI
488 }
489
490 OverflowResult computeOverflow(
491 Instruction::BinaryOps BinaryOp, bool IsSigned,
492 Value *LHS, Value *RHS, Instruction *CxtI) const;
493
494 /// Performs a few simplifications for operators which are associative
495 /// or commutative.
496 bool SimplifyAssociativeOrCommutative(BinaryOperator &I);
497
498 /// Tries to simplify binary operations which some other binary
499 /// operation distributes over.
500 ///
501 /// It does this by either by factorizing out common terms (eg "(A*B)+(A*C)"
502 /// -> "A*(B+C)") or expanding out if this results in simplifications (eg: "A
503 /// & (B | C) -> (A&B) | (A&C)" if this is a win). Returns the simplified
504 /// value, or null if it didn't simplify.
505 Value *foldUsingDistributiveLaws(BinaryOperator &I);
506
507 /// Tries to simplify add operations using the definition of remainder.
508 ///
509 /// The definition of remainder is X % C = X - (X / C ) * C. The add
510 /// expression X % C0 + (( X / C0 ) % C1) * C0 can be simplified to
511 /// X % (C0 * C1)
512 Value *SimplifyAddWithRemainder(BinaryOperator &I);
513
514 // Binary Op helper for select operations where the expression can be
515 // efficiently reorganized.
516 Value *SimplifySelectsFeedingBinaryOp(BinaryOperator &I, Value *LHS,
517 Value *RHS);
518
519 // If `I` has operand `(ctpop (not x))`, fold `I` with `(sub nuw nsw
520 // BitWidth(x), (ctpop x))`.
521 Instruction *tryFoldInstWithCtpopWithNot(Instruction *I);
522
523 // (Binop1 (Binop2 (logic_shift X, C), C1), (logic_shift Y, C))
524 // -> (logic_shift (Binop1 (Binop2 X, inv_logic_shift(C1, C)), Y), C)
525 // (Binop1 (Binop2 (logic_shift X, Amt), Mask), (logic_shift Y, Amt))
526 // -> (BinOp (logic_shift (BinOp X, Y)), Mask)
527 Instruction *foldBinOpShiftWithShift(BinaryOperator &I);
528
529 /// Tries to simplify binops of select and cast of the select condition.
530 ///
531 /// (Binop (cast C), (select C, T, F))
532 /// -> (select C, C0, C1)
533 Instruction *foldBinOpOfSelectAndCastOfSelectCondition(BinaryOperator &I);
534
535 /// This tries to simplify binary operations by factorizing out common terms
536 /// (e. g. "(A*B)+(A*C)" -> "A*(B+C)").
537 Value *tryFactorizationFolds(BinaryOperator &I);
538
539 /// Match a select chain which produces one of three values based on whether
540 /// the LHS is less than, equal to, or greater than RHS respectively.
541 /// Return true if we matched a three way compare idiom. The LHS, RHS, Less,
542 /// Equal and Greater values are saved in the matching process and returned to
543 /// the caller.
544 bool matchThreeWayIntCompare(SelectInst *SI, Value *&LHS, Value *&RHS,
545 ConstantInt *&Less, ConstantInt *&Equal,
546 ConstantInt *&Greater);
547
548 /// Attempts to replace I with a simpler value based on the demanded
549 /// bits.
550 Value *SimplifyDemandedUseBits(Instruction *I, const APInt &DemandedMask,
551 KnownBits &Known, unsigned Depth,
552 const SimplifyQuery &Q);
553 using InstCombiner::SimplifyDemandedBits;
554 bool SimplifyDemandedBits(Instruction *I, unsigned Op,
555 const APInt &DemandedMask, KnownBits &Known,
556 unsigned Depth, const SimplifyQuery &Q) override;
557
558 /// Helper routine of SimplifyDemandedUseBits. It computes KnownZero/KnownOne
559 /// bits. It also tries to handle simplifications that can be done based on
560 /// DemandedMask, but without modifying the Instruction.
561 Value *SimplifyMultipleUseDemandedBits(Instruction *I,
562 const APInt &DemandedMask,
563 KnownBits &Known, unsigned Depth,
564 const SimplifyQuery &Q);
565
566 /// Helper routine of SimplifyDemandedUseBits. It tries to simplify demanded
567 /// bit for "r1 = shr x, c1; r2 = shl r1, c2" instruction sequence.
568 Value *simplifyShrShlDemandedBits(
569 Instruction *Shr, const APInt &ShrOp1, Instruction *Shl,
570 const APInt &ShlOp1, const APInt &DemandedMask, KnownBits &Known);
571
572 /// Tries to simplify operands to an integer instruction based on its
573 /// demanded bits.
574 bool SimplifyDemandedInstructionBits(Instruction &Inst);
575 bool SimplifyDemandedInstructionBits(Instruction &Inst, KnownBits &Known);
576
577 Value *SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
578 APInt &PoisonElts, unsigned Depth = 0,
579 bool AllowMultipleUsers = false) override;
580
581 /// Attempts to replace V with a simpler value based on the demanded
582 /// floating-point classes
583 Value *SimplifyDemandedUseFPClass(Value *V, FPClassTest DemandedMask,
584 KnownFPClass &Known, unsigned Depth,
585 Instruction *CxtI);
586 bool SimplifyDemandedFPClass(Instruction *I, unsigned Op,
587 FPClassTest DemandedMask, KnownFPClass &Known,
588 unsigned Depth = 0);
589
590 /// Canonicalize the position of binops relative to shufflevector.
591 Instruction *foldVectorBinop(BinaryOperator &Inst);
592 Instruction *foldVectorSelect(SelectInst &Sel);
593 Instruction *foldSelectShuffle(ShuffleVectorInst &Shuf);
594
595 /// Given a binary operator, cast instruction, or select which has a PHI node
596 /// as operand #0, see if we can fold the instruction into the PHI (which is
597 /// only possible if all operands to the PHI are constants).
598 Instruction *foldOpIntoPhi(Instruction &I, PHINode *PN);
599
600 /// For a binary operator with 2 phi operands, try to hoist the binary
601 /// operation before the phi. This can result in fewer instructions in
602 /// patterns where at least one set of phi operands simplifies.
603 /// Example:
604 /// BB3: binop (phi [X, BB1], [C1, BB2]), (phi [Y, BB1], [C2, BB2])
605 /// -->
606 /// BB1: BO = binop X, Y
607 /// BB3: phi [BO, BB1], [(binop C1, C2), BB2]
608 Instruction *foldBinopWithPhiOperands(BinaryOperator &BO);
609
610 /// Given an instruction with a select as one operand and a constant as the
611 /// other operand, try to fold the binary operator into the select arguments.
612 /// This also works for Cast instructions, which obviously do not have a
613 /// second operand.
614 Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
615 bool FoldWithMultiUse = false);
616
617 /// This is a convenience wrapper function for the above two functions.
618 Instruction *foldBinOpIntoSelectOrPhi(BinaryOperator &I);
619
620 Instruction *foldAddWithConstant(BinaryOperator &Add);
621
622 Instruction *foldSquareSumInt(BinaryOperator &I);
623 Instruction *foldSquareSumFP(BinaryOperator &I);
624
625 /// Try to rotate an operation below a PHI node, using PHI nodes for
626 /// its operands.
627 Instruction *foldPHIArgOpIntoPHI(PHINode &PN);
628 Instruction *foldPHIArgBinOpIntoPHI(PHINode &PN);
629 Instruction *foldPHIArgInsertValueInstructionIntoPHI(PHINode &PN);
630 Instruction *foldPHIArgExtractValueInstructionIntoPHI(PHINode &PN);
631 Instruction *foldPHIArgGEPIntoPHI(PHINode &PN);
632 Instruction *foldPHIArgLoadIntoPHI(PHINode &PN);
633 Instruction *foldPHIArgZextsIntoPHI(PHINode &PN);
634 Instruction *foldPHIArgIntToPtrToPHI(PHINode &PN);
635
636 /// If an integer typed PHI has only one use which is an IntToPtr operation,
637 /// replace the PHI with an existing pointer typed PHI if it exists. Otherwise
638 /// insert a new pointer typed PHI and replace the original one.
639 bool foldIntegerTypedPHI(PHINode &PN);
640
641 /// Helper function for FoldPHIArgXIntoPHI() to set debug location for the
642 /// folded operation.
643 void PHIArgMergedDebugLoc(Instruction *Inst, PHINode &PN);
644
645 Instruction *foldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
646 ICmpInst::Predicate Cond, Instruction &I);
647 Instruction *foldSelectICmp(ICmpInst::Predicate Pred, SelectInst *SI,
648 Value *RHS, const ICmpInst &I);
649 bool foldAllocaCmp(AllocaInst *Alloca);
650 Instruction *foldCmpLoadFromIndexedGlobal(LoadInst *LI,
651 GetElementPtrInst *GEP,
652 GlobalVariable *GV, CmpInst &ICI,
653 ConstantInt *AndCst = nullptr);
654 Instruction *foldFCmpIntToFPConst(FCmpInst &I, Instruction *LHSI,
655 Constant *RHSC);
656 Instruction *foldICmpAddOpConst(Value *X, const APInt &C,
657 ICmpInst::Predicate Pred);
658 Instruction *foldICmpWithCastOp(ICmpInst &ICmp);
659 Instruction *foldICmpWithZextOrSext(ICmpInst &ICmp);
660
661 Instruction *foldICmpUsingKnownBits(ICmpInst &Cmp);
662 Instruction *foldICmpWithDominatingICmp(ICmpInst &Cmp);
663 Instruction *foldICmpWithConstant(ICmpInst &Cmp);
664 Instruction *foldICmpUsingBoolRange(ICmpInst &I);
665 Instruction *foldICmpInstWithConstant(ICmpInst &Cmp);
666 Instruction *foldICmpInstWithConstantNotInt(ICmpInst &Cmp);
667 Instruction *foldICmpInstWithConstantAllowPoison(ICmpInst &Cmp,
668 const APInt &C);
669 Instruction *foldICmpBinOp(ICmpInst &Cmp, const SimplifyQuery &SQ);
670 Instruction *foldICmpWithMinMax(Instruction &I, MinMaxIntrinsic *MinMax,
671 Value *Z, ICmpInst::Predicate Pred);
672 Instruction *foldICmpEquality(ICmpInst &Cmp);
673 Instruction *foldIRemByPowerOfTwoToBitTest(ICmpInst &I);
674 Instruction *foldSignBitTest(ICmpInst &I);
675 Instruction *foldICmpWithZero(ICmpInst &Cmp);
676
677 Value *foldMultiplicationOverflowCheck(ICmpInst &Cmp);
678
679 Instruction *foldICmpBinOpWithConstant(ICmpInst &Cmp, BinaryOperator *BO,
680 const APInt &C);
681 Instruction *foldICmpSelectConstant(ICmpInst &Cmp, SelectInst *Select,
682 ConstantInt *C);
683 Instruction *foldICmpTruncConstant(ICmpInst &Cmp, TruncInst *Trunc,
684 const APInt &C);
685 Instruction *foldICmpTruncWithTruncOrExt(ICmpInst &Cmp,
686 const SimplifyQuery &Q);
687 Instruction *foldICmpAndConstant(ICmpInst &Cmp, BinaryOperator *And,
688 const APInt &C);
689 Instruction *foldICmpXorConstant(ICmpInst &Cmp, BinaryOperator *Xor,
690 const APInt &C);
691 Instruction *foldICmpOrConstant(ICmpInst &Cmp, BinaryOperator *Or,
692 const APInt &C);
693 Instruction *foldICmpMulConstant(ICmpInst &Cmp, BinaryOperator *Mul,
694 const APInt &C);
695 Instruction *foldICmpShlConstant(ICmpInst &Cmp, BinaryOperator *Shl,
696 const APInt &C);
697 Instruction *foldICmpShrConstant(ICmpInst &Cmp, BinaryOperator *Shr,
698 const APInt &C);
699 Instruction *foldICmpSRemConstant(ICmpInst &Cmp, BinaryOperator *UDiv,
700 const APInt &C);
701 Instruction *foldICmpUDivConstant(ICmpInst &Cmp, BinaryOperator *UDiv,
702 const APInt &C);
703 Instruction *foldICmpDivConstant(ICmpInst &Cmp, BinaryOperator *Div,
704 const APInt &C);
705 Instruction *foldICmpSubConstant(ICmpInst &Cmp, BinaryOperator *Sub,
706 const APInt &C);
707 Instruction *foldICmpAddConstant(ICmpInst &Cmp, BinaryOperator *Add,
708 const APInt &C);
709 Instruction *foldICmpAndConstConst(ICmpInst &Cmp, BinaryOperator *And,
710 const APInt &C1);
711 Instruction *foldICmpAndShift(ICmpInst &Cmp, BinaryOperator *And,
712 const APInt &C1, const APInt &C2);
713 Instruction *foldICmpXorShiftConst(ICmpInst &Cmp, BinaryOperator *Xor,
714 const APInt &C);
715 Instruction *foldICmpShrConstConst(ICmpInst &I, Value *ShAmt, const APInt &C1,
716 const APInt &C2);
717 Instruction *foldICmpShlConstConst(ICmpInst &I, Value *ShAmt, const APInt &C1,
718 const APInt &C2);
719
720 Instruction *foldICmpBinOpEqualityWithConstant(ICmpInst &Cmp,
721 BinaryOperator *BO,
722 const APInt &C);
723 Instruction *foldICmpIntrinsicWithConstant(ICmpInst &ICI, IntrinsicInst *II,
724 const APInt &C);
725 Instruction *foldICmpEqIntrinsicWithConstant(ICmpInst &ICI, IntrinsicInst *II,
726 const APInt &C);
727 Instruction *foldICmpBitCast(ICmpInst &Cmp);
728 Instruction *foldICmpWithTrunc(ICmpInst &Cmp);
729 Instruction *foldICmpCommutative(ICmpInst::Predicate Pred, Value *Op0,
730 Value *Op1, ICmpInst &CxtI);
731
732 // Helpers of visitSelectInst().
733 Instruction *foldSelectOfBools(SelectInst &SI);
734 Instruction *foldSelectExtConst(SelectInst &Sel);
735 Instruction *foldSelectOpOp(SelectInst &SI, Instruction *TI, Instruction *FI);
736 Instruction *foldSelectIntoOp(SelectInst &SI, Value *, Value *);
737 Instruction *foldSPFofSPF(Instruction *Inner, SelectPatternFlavor SPF1,
738 Value *A, Value *B, Instruction &Outer,
739 SelectPatternFlavor SPF2, Value *C);
740 Instruction *foldSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI);
741 Instruction *foldSelectValueEquivalence(SelectInst &SI, ICmpInst &ICI);
742 bool replaceInInstruction(Value *V, Value *Old, Value *New,
743 unsigned Depth = 0);
744
745 Value *insertRangeTest(Value *V, const APInt &Lo, const APInt &Hi,
746 bool isSigned, bool Inside);
747 bool mergeStoreIntoSuccessor(StoreInst &SI);
748
749 /// Given an initial instruction, check to see if it is the root of a
750 /// bswap/bitreverse idiom. If so, return the equivalent bswap/bitreverse
751 /// intrinsic.
752 Instruction *matchBSwapOrBitReverse(Instruction &I, bool MatchBSwaps,
753 bool MatchBitReversals);
754
755 Instruction *SimplifyAnyMemTransfer(AnyMemTransferInst *MI);
756 Instruction *SimplifyAnyMemSet(AnyMemSetInst *MI);
757
758 Value *EvaluateInDifferentType(Value *V, Type *Ty, bool isSigned);
759
760 bool tryToSinkInstruction(Instruction *I, BasicBlock *DestBlock);
761 void tryToSinkInstructionDbgValues(
762 Instruction *I, BasicBlock::iterator InsertPos, BasicBlock *SrcBlock,
763 BasicBlock *DestBlock, SmallVectorImpl<DbgVariableIntrinsic *> &DbgUsers);
764 void tryToSinkInstructionDbgVariableRecords(
765 Instruction *I, BasicBlock::iterator InsertPos, BasicBlock *SrcBlock,
766 BasicBlock *DestBlock, SmallVectorImpl<DbgVariableRecord *> &DPUsers);
767
768 bool removeInstructionsBeforeUnreachable(Instruction &I);
769 void addDeadEdge(BasicBlock *From, BasicBlock *To,
770 SmallVectorImpl<BasicBlock *> &Worklist);
771 void handleUnreachableFrom(Instruction *I,
772 SmallVectorImpl<BasicBlock *> &Worklist);
773 void handlePotentiallyDeadBlocks(SmallVectorImpl<BasicBlock *> &Worklist);
774 void handlePotentiallyDeadSuccessors(BasicBlock *BB, BasicBlock *LiveSucc);
775 void freelyInvertAllUsersOf(Value *V, Value *IgnoredUser = nullptr);
776};
777
778class Negator final {
779 /// Top-to-bottom, def-to-use negated instruction tree we produced.
780 SmallVector<Instruction *, NegatorMaxNodesSSO> NewInstructions;
781
782 using BuilderTy = IRBuilder<TargetFolder, IRBuilderCallbackInserter>;
783 BuilderTy Builder;
784
785 const bool IsTrulyNegation;
786
787 SmallDenseMap<Value *, Value *> NegationsCache;
788
789 Negator(LLVMContext &C, const DataLayout &DL, bool IsTrulyNegation);
790
791#if LLVM_ENABLE_STATS
792 unsigned NumValuesVisitedInThisNegator = 0;
793 ~Negator();
794#endif
795
796 using Result = std::pair<ArrayRef<Instruction *> /*NewInstructions*/,
797 Value * /*NegatedRoot*/>;
798
799 std::array<Value *, 2> getSortedOperandsOfBinOp(Instruction *I);
800
801 [[nodiscard]] Value *visitImpl(Value *V, bool IsNSW, unsigned Depth);
802
803 [[nodiscard]] Value *negate(Value *V, bool IsNSW, unsigned Depth);
804
805 /// Recurse depth-first and attempt to sink the negation.
806 /// FIXME: use worklist?
807 [[nodiscard]] std::optional<Result> run(Value *Root, bool IsNSW);
808
809 Negator(const Negator &) = delete;
810 Negator(Negator &&) = delete;
811 Negator &operator=(const Negator &) = delete;
812 Negator &operator=(Negator &&) = delete;
813
814public:
815 /// Attempt to negate \p Root. Retuns nullptr if negation can't be performed,
816 /// otherwise returns negated value.
817 [[nodiscard]] static Value *Negate(bool LHSIsZero, bool IsNSW, Value *Root,
818 InstCombinerImpl &IC);
819};
820
821} // end namespace llvm
822
823#undef DEBUG_TYPE
824
825#endif // LLVM_LIB_TRANSFORMS_INSTCOMBINE_INSTCOMBINEINTERNAL_H
826