1 //===- InstCombine.h - Main InstCombine pass definition ---------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #ifndef LLVM_LIB_TRANSFORMS_INSTCOMBINE_INSTCOMBINE_H
11 #define LLVM_LIB_TRANSFORMS_INSTCOMBINE_INSTCOMBINE_H
13 #include "InstCombineWorklist.h"
14 #include "llvm/Analysis/AssumptionTracker.h"
15 #include "llvm/Analysis/TargetFolder.h"
16 #include "llvm/Analysis/ValueTracking.h"
17 #include "llvm/IR/Dominators.h"
18 #include "llvm/IR/IRBuilder.h"
19 #include "llvm/IR/InstVisitor.h"
20 #include "llvm/IR/IntrinsicInst.h"
21 #include "llvm/IR/Operator.h"
22 #include "llvm/IR/PatternMatch.h"
23 #include "llvm/Pass.h"
24 #include "llvm/Transforms/Utils/SimplifyLibCalls.h"
26 #define DEBUG_TYPE "instcombine"
32 class TargetLibraryInfo;
37 /// SelectPatternFlavor - We can match a variety of different patterns for
38 /// select operations.
39 enum SelectPatternFlavor {
49 /// getComplexity: Assign a complexity or rank value to LLVM Values...
50 /// 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
51 static inline unsigned getComplexity(Value *V) {
52 if (isa<Instruction>(V)) {
53 if (BinaryOperator::isNeg(V) || BinaryOperator::isFNeg(V) ||
54 BinaryOperator::isNot(V))
60 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
63 /// AddOne - Add one to a Constant
64 static inline Constant *AddOne(Constant *C) {
65 return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1));
67 /// SubOne - Subtract one from a Constant
68 static inline Constant *SubOne(Constant *C) {
69 return ConstantExpr::getSub(C, ConstantInt::get(C->getType(), 1));
72 /// InstCombineIRInserter - This is an IRBuilder insertion helper that works
73 /// just like the normal insertion helper, but also adds any new instructions
74 /// to the instcombine worklist.
75 class LLVM_LIBRARY_VISIBILITY InstCombineIRInserter
76 : public IRBuilderDefaultInserter<true> {
77 InstCombineWorklist &Worklist;
78 AssumptionTracker *AT;
81 InstCombineIRInserter(InstCombineWorklist &WL, AssumptionTracker *AT)
82 : Worklist(WL), AT(AT) {}
84 void InsertHelper(Instruction *I, const Twine &Name, BasicBlock *BB,
85 BasicBlock::iterator InsertPt) const {
86 IRBuilderDefaultInserter<true>::InsertHelper(I, Name, BB, InsertPt);
89 using namespace llvm::PatternMatch;
90 if (match(I, m_Intrinsic<Intrinsic::assume>()))
91 AT->registerAssumption(cast<CallInst>(I));
95 /// InstCombiner - The -instcombine pass.
96 class LLVM_LIBRARY_VISIBILITY InstCombiner
97 : public FunctionPass,
98 public InstVisitor<InstCombiner, Instruction *> {
99 AssumptionTracker *AT;
100 const DataLayout *DL;
101 TargetLibraryInfo *TLI;
104 LibCallSimplifier *Simplifier;
108 /// Worklist - All of the instructions that need to be simplified.
109 InstCombineWorklist Worklist;
111 /// Builder - This is an IRBuilder that automatically inserts new
112 /// instructions into the worklist when they are created.
113 typedef IRBuilder<true, TargetFolder, InstCombineIRInserter> BuilderTy;
116 static char ID; // Pass identification, replacement for typeid
118 : FunctionPass(ID), DL(nullptr), DT(nullptr), Builder(nullptr) {
119 MinimizeSize = false;
120 initializeInstCombinerPass(*PassRegistry::getPassRegistry());
124 bool runOnFunction(Function &F) override;
126 bool DoOneIteration(Function &F, unsigned ItNum);
128 void getAnalysisUsage(AnalysisUsage &AU) const override;
130 AssumptionTracker *getAssumptionTracker() const { return AT; }
132 const DataLayout *getDataLayout() const { return DL; }
134 DominatorTree *getDominatorTree() const { return DT; }
136 TargetLibraryInfo *getTargetLibraryInfo() const { return TLI; }
138 // Visitation implementation - Implement instruction combining for different
139 // instruction types. The semantics are as follows:
141 // null - No change was made
142 // I - Change was made, I is still valid, I may be dead though
143 // otherwise - Change was made, replace I with returned instruction
145 Instruction *visitAdd(BinaryOperator &I);
146 Instruction *visitFAdd(BinaryOperator &I);
147 Value *OptimizePointerDifference(Value *LHS, Value *RHS, Type *Ty);
148 Instruction *visitSub(BinaryOperator &I);
149 Instruction *visitFSub(BinaryOperator &I);
150 Instruction *visitMul(BinaryOperator &I);
151 Value *foldFMulConst(Instruction *FMulOrDiv, Constant *C,
152 Instruction *InsertBefore);
153 Instruction *visitFMul(BinaryOperator &I);
154 Instruction *visitURem(BinaryOperator &I);
155 Instruction *visitSRem(BinaryOperator &I);
156 Instruction *visitFRem(BinaryOperator &I);
157 bool SimplifyDivRemOfSelect(BinaryOperator &I);
158 Instruction *commonRemTransforms(BinaryOperator &I);
159 Instruction *commonIRemTransforms(BinaryOperator &I);
160 Instruction *commonDivTransforms(BinaryOperator &I);
161 Instruction *commonIDivTransforms(BinaryOperator &I);
162 Instruction *visitUDiv(BinaryOperator &I);
163 Instruction *visitSDiv(BinaryOperator &I);
164 Instruction *visitFDiv(BinaryOperator &I);
165 Value *FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS);
166 Value *FoldAndOfFCmps(FCmpInst *LHS, FCmpInst *RHS);
167 Instruction *visitAnd(BinaryOperator &I);
168 Value *FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS, Instruction *CxtI);
169 Value *FoldOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS);
170 Instruction *FoldOrWithConstants(BinaryOperator &I, Value *Op, Value *A,
172 Instruction *FoldXorWithConstants(BinaryOperator &I, Value *Op, Value *A,
174 Instruction *visitOr(BinaryOperator &I);
175 Instruction *visitXor(BinaryOperator &I);
176 Instruction *visitShl(BinaryOperator &I);
177 Instruction *visitAShr(BinaryOperator &I);
178 Instruction *visitLShr(BinaryOperator &I);
179 Instruction *commonShiftTransforms(BinaryOperator &I);
180 Instruction *FoldFCmp_IntToFP_Cst(FCmpInst &I, Instruction *LHSI,
182 Instruction *FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP,
183 GlobalVariable *GV, CmpInst &ICI,
184 ConstantInt *AndCst = nullptr);
185 Instruction *visitFCmpInst(FCmpInst &I);
186 Instruction *visitICmpInst(ICmpInst &I);
187 Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI);
188 Instruction *visitICmpInstWithInstAndIntCst(ICmpInst &ICI, Instruction *LHS,
190 Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
191 ConstantInt *DivRHS);
192 Instruction *FoldICmpShrCst(ICmpInst &ICI, BinaryOperator *DivI,
193 ConstantInt *DivRHS);
194 Instruction *FoldICmpCstShrCst(ICmpInst &I, Value *Op, Value *A,
195 ConstantInt *CI1, ConstantInt *CI2);
196 Instruction *FoldICmpCstShlCst(ICmpInst &I, Value *Op, Value *A,
197 ConstantInt *CI1, ConstantInt *CI2);
198 Instruction *FoldICmpAddOpCst(Instruction &ICI, Value *X, ConstantInt *CI,
199 ICmpInst::Predicate Pred);
200 Instruction *FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
201 ICmpInst::Predicate Cond, Instruction &I);
202 Instruction *FoldShiftByConstant(Value *Op0, Constant *Op1,
204 Instruction *commonCastTransforms(CastInst &CI);
205 Instruction *commonPointerCastTransforms(CastInst &CI);
206 Instruction *visitTrunc(TruncInst &CI);
207 Instruction *visitZExt(ZExtInst &CI);
208 Instruction *visitSExt(SExtInst &CI);
209 Instruction *visitFPTrunc(FPTruncInst &CI);
210 Instruction *visitFPExt(CastInst &CI);
211 Instruction *visitFPToUI(FPToUIInst &FI);
212 Instruction *visitFPToSI(FPToSIInst &FI);
213 Instruction *visitUIToFP(CastInst &CI);
214 Instruction *visitSIToFP(CastInst &CI);
215 Instruction *visitPtrToInt(PtrToIntInst &CI);
216 Instruction *visitIntToPtr(IntToPtrInst &CI);
217 Instruction *visitBitCast(BitCastInst &CI);
218 Instruction *visitAddrSpaceCast(AddrSpaceCastInst &CI);
219 Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI, Instruction *FI);
220 Instruction *FoldSelectIntoOp(SelectInst &SI, Value *, Value *);
221 Instruction *FoldSPFofSPF(Instruction *Inner, SelectPatternFlavor SPF1,
222 Value *A, Value *B, Instruction &Outer,
223 SelectPatternFlavor SPF2, Value *C);
224 Instruction *visitSelectInst(SelectInst &SI);
225 Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI);
226 Instruction *visitCallInst(CallInst &CI);
227 Instruction *visitInvokeInst(InvokeInst &II);
229 Instruction *SliceUpIllegalIntegerPHI(PHINode &PN);
230 Instruction *visitPHINode(PHINode &PN);
231 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
232 Instruction *visitAllocaInst(AllocaInst &AI);
233 Instruction *visitAllocSite(Instruction &FI);
234 Instruction *visitFree(CallInst &FI);
235 Instruction *visitLoadInst(LoadInst &LI);
236 Instruction *visitStoreInst(StoreInst &SI);
237 Instruction *visitBranchInst(BranchInst &BI);
238 Instruction *visitSwitchInst(SwitchInst &SI);
239 Instruction *visitReturnInst(ReturnInst &RI);
240 Instruction *visitInsertValueInst(InsertValueInst &IV);
241 Instruction *visitInsertElementInst(InsertElementInst &IE);
242 Instruction *visitExtractElementInst(ExtractElementInst &EI);
243 Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
244 Instruction *visitExtractValueInst(ExtractValueInst &EV);
245 Instruction *visitLandingPadInst(LandingPadInst &LI);
247 // visitInstruction - Specify what to return for unhandled instructions...
248 Instruction *visitInstruction(Instruction &I) { return nullptr; }
250 // True when DB dominates all uses of DI execpt UI.
251 // UI must be in the same block as DI.
252 // The routine checks that the DI parent and DB are different.
253 bool dominatesAllUses(const Instruction *DI, const Instruction *UI,
254 const BasicBlock *DB) const;
256 // Replace select with select operand SIOpd in SI-ICmp sequence when possible
257 bool replacedSelectWithOperand(SelectInst *SI, const ICmpInst *Icmp,
258 const unsigned SIOpd);
261 bool ShouldChangeType(Type *From, Type *To) const;
262 Value *dyn_castNegVal(Value *V) const;
263 Value *dyn_castFNegVal(Value *V, bool NoSignedZero = false) const;
264 Type *FindElementAtOffset(Type *PtrTy, int64_t Offset,
265 SmallVectorImpl<Value *> &NewIndices);
266 Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI);
268 /// ShouldOptimizeCast - Return true if the cast from "V to Ty" actually
269 /// results in any code being generated and is interesting to optimize out. If
270 /// the cast can be eliminated by some other simple transformation, we prefer
271 /// to do the simplification first.
272 bool ShouldOptimizeCast(Instruction::CastOps opcode, const Value *V,
275 Instruction *visitCallSite(CallSite CS);
276 Instruction *tryOptimizeCall(CallInst *CI, const DataLayout *DL);
277 bool transformConstExprCastCall(CallSite CS);
278 Instruction *transformCallThroughTrampoline(CallSite CS,
279 IntrinsicInst *Tramp);
280 Instruction *transformZExtICmp(ICmpInst *ICI, Instruction &CI,
281 bool DoXform = true);
282 Instruction *transformSExtICmp(ICmpInst *ICI, Instruction &CI);
283 bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS, Instruction *CxtI);
284 bool WillNotOverflowUnsignedAdd(Value *LHS, Value *RHS, Instruction *CxtI);
285 bool WillNotOverflowSignedSub(Value *LHS, Value *RHS, Instruction *CxtI);
286 bool WillNotOverflowUnsignedSub(Value *LHS, Value *RHS, Instruction *CxtI);
287 Value *EmitGEPOffset(User *GEP);
288 Instruction *scalarizePHI(ExtractElementInst &EI, PHINode *PN);
289 Value *EvaluateInDifferentElementOrder(Value *V, ArrayRef<int> Mask);
292 // InsertNewInstBefore - insert an instruction New before instruction Old
293 // in the program. Add the new instruction to the worklist.
295 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
296 assert(New && !New->getParent() &&
297 "New instruction already inserted into a basic block!");
298 BasicBlock *BB = Old.getParent();
299 BB->getInstList().insert(&Old, New); // Insert inst
304 // InsertNewInstWith - same as InsertNewInstBefore, but also sets the
307 Instruction *InsertNewInstWith(Instruction *New, Instruction &Old) {
308 New->setDebugLoc(Old.getDebugLoc());
309 return InsertNewInstBefore(New, Old);
312 // ReplaceInstUsesWith - This method is to be used when an instruction is
313 // found to be dead, replacable with another preexisting expression. Here
314 // we add all uses of I to the worklist, replace all uses of I with the new
315 // value, then return I, so that the inst combiner will know that I was
318 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
319 Worklist.AddUsersToWorkList(I); // Add all modified instrs to worklist.
321 // If we are replacing the instruction with itself, this must be in a
322 // segment of unreachable code, so just clobber the instruction.
324 V = UndefValue::get(I.getType());
326 DEBUG(dbgs() << "IC: Replacing " << I << "\n"
327 " with " << *V << '\n');
329 I.replaceAllUsesWith(V);
333 // EraseInstFromFunction - When dealing with an instruction that has side
334 // effects or produces a void value, we can't rely on DCE to delete the
335 // instruction. Instead, visit methods should return the value returned by
337 Instruction *EraseInstFromFunction(Instruction &I) {
338 DEBUG(dbgs() << "IC: ERASE " << I << '\n');
340 assert(I.use_empty() && "Cannot erase instruction that is used!");
341 // Make sure that we reprocess all operands now that we reduced their
343 if (I.getNumOperands() < 8) {
344 for (User::op_iterator i = I.op_begin(), e = I.op_end(); i != e; ++i)
345 if (Instruction *Op = dyn_cast<Instruction>(*i))
351 return nullptr; // Don't do anything with FI
354 void computeKnownBits(Value *V, APInt &KnownZero, APInt &KnownOne,
355 unsigned Depth = 0, Instruction *CxtI = nullptr) const {
356 return llvm::computeKnownBits(V, KnownZero, KnownOne, DL, Depth,
360 bool MaskedValueIsZero(Value *V, const APInt &Mask,
362 Instruction *CxtI = nullptr) const {
363 return llvm::MaskedValueIsZero(V, Mask, DL, Depth, AT, CxtI, DT);
365 unsigned ComputeNumSignBits(Value *Op, unsigned Depth = 0,
366 Instruction *CxtI = nullptr) const {
367 return llvm::ComputeNumSignBits(Op, DL, Depth, AT, CxtI, DT);
371 /// SimplifyAssociativeOrCommutative - This performs a few simplifications for
372 /// operators which are associative or commutative.
373 bool SimplifyAssociativeOrCommutative(BinaryOperator &I);
375 /// SimplifyUsingDistributiveLaws - This tries to simplify binary operations
376 /// which some other binary operation distributes over either by factorizing
377 /// out common terms (eg "(A*B)+(A*C)" -> "A*(B+C)") or expanding out if this
378 /// results in simplifications (eg: "A & (B | C) -> (A&B) | (A&C)" if this is
379 /// a win). Returns the simplified value, or null if it didn't simplify.
380 Value *SimplifyUsingDistributiveLaws(BinaryOperator &I);
382 /// SimplifyDemandedUseBits - Attempts to replace V with a simpler value
383 /// based on the demanded bits.
384 Value *SimplifyDemandedUseBits(Value *V, APInt DemandedMask, APInt &KnownZero,
385 APInt &KnownOne, unsigned Depth,
386 Instruction *CxtI = nullptr);
387 bool SimplifyDemandedBits(Use &U, APInt DemandedMask, APInt &KnownZero,
388 APInt &KnownOne, unsigned Depth = 0);
389 /// Helper routine of SimplifyDemandedUseBits. It tries to simplify demanded
390 /// bit for "r1 = shr x, c1; r2 = shl r1, c2" instruction sequence.
391 Value *SimplifyShrShlDemandedBits(Instruction *Lsr, Instruction *Sftl,
392 APInt DemandedMask, APInt &KnownZero,
395 /// SimplifyDemandedInstructionBits - Inst is an integer instruction that
396 /// SimplifyDemandedBits knows about. See if the instruction has any
397 /// properties that allow us to simplify its operands.
398 bool SimplifyDemandedInstructionBits(Instruction &Inst);
400 Value *SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
401 APInt &UndefElts, unsigned Depth = 0);
403 Value *SimplifyVectorOp(BinaryOperator &Inst);
405 // FoldOpIntoPhi - Given a binary operator, cast instruction, or select
406 // which has a PHI node as operand #0, see if we can fold the instruction
407 // into the PHI (which is only possible if all operands to the PHI are
410 Instruction *FoldOpIntoPhi(Instruction &I);
412 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
413 // operator and they all are only used by the PHI, PHI together their
414 // inputs, and do the operation once, to the result of the PHI.
415 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
416 Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN);
417 Instruction *FoldPHIArgGEPIntoPHI(PHINode &PN);
418 Instruction *FoldPHIArgLoadIntoPHI(PHINode &PN);
420 Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS,
421 ConstantInt *AndRHS, BinaryOperator &TheAnd);
423 Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask,
424 bool isSub, Instruction &I);
425 Value *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi, bool isSigned,
427 Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocaInst &AI);
428 Instruction *MatchBSwap(BinaryOperator &I);
429 bool SimplifyStoreAtEndOfBlock(StoreInst &SI);
430 Instruction *SimplifyMemTransfer(MemIntrinsic *MI);
431 Instruction *SimplifyMemSet(MemSetInst *MI);
433 Value *EvaluateInDifferentType(Value *V, Type *Ty, bool isSigned);
435 /// Descale - Return a value X such that Val = X * Scale, or null if none. If
436 /// the multiplication is known not to overflow then NoSignedWrap is set.
437 Value *Descale(Value *Val, APInt Scale, bool &NoSignedWrap);
440 } // end namespace llvm.