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 INSTCOMBINE_INSTCOMBINE_H
11 #define INSTCOMBINE_INSTCOMBINE_H
13 #include "InstCombineWorklist.h"
14 #include "llvm/Analysis/TargetFolder.h"
15 #include "llvm/Analysis/ValueTracking.h"
16 #include "llvm/IR/IRBuilder.h"
17 #include "llvm/IR/IntrinsicInst.h"
18 #include "llvm/IR/Operator.h"
19 #include "llvm/InstVisitor.h"
20 #include "llvm/Pass.h"
21 #include "llvm/Transforms/Utils/SimplifyLibCalls.h"
26 class TargetLibraryInfo;
31 /// SelectPatternFlavor - We can match a variety of different patterns for
32 /// select operations.
33 enum SelectPatternFlavor {
40 /// getComplexity: Assign a complexity or rank value to LLVM Values...
41 /// 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
42 static inline unsigned getComplexity(Value *V) {
43 if (isa<Instruction>(V)) {
44 if (BinaryOperator::isNeg(V) ||
45 BinaryOperator::isFNeg(V) ||
46 BinaryOperator::isNot(V))
50 if (isa<Argument>(V)) return 3;
51 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
54 /// AddOne - Add one to a Constant
55 static inline Constant *AddOne(Constant *C) {
56 return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1));
58 /// SubOne - Subtract one from a Constant
59 static inline Constant *SubOne(Constant *C) {
60 return ConstantExpr::getSub(C, ConstantInt::get(C->getType(), 1));
64 /// InstCombineIRInserter - This is an IRBuilder insertion helper that works
65 /// just like the normal insertion helper, but also adds any new instructions
66 /// to the instcombine worklist.
67 class LLVM_LIBRARY_VISIBILITY InstCombineIRInserter
68 : public IRBuilderDefaultInserter<true> {
69 InstCombineWorklist &Worklist;
71 InstCombineIRInserter(InstCombineWorklist &WL) : Worklist(WL) {}
73 void InsertHelper(Instruction *I, const Twine &Name,
74 BasicBlock *BB, BasicBlock::iterator InsertPt) const {
75 IRBuilderDefaultInserter<true>::InsertHelper(I, Name, BB, InsertPt);
80 /// InstCombiner - The -instcombine pass.
81 class LLVM_LIBRARY_VISIBILITY InstCombiner
82 : public FunctionPass,
83 public InstVisitor<InstCombiner, Instruction*> {
85 TargetLibraryInfo *TLI;
87 LibCallSimplifier *Simplifier;
90 /// Worklist - All of the instructions that need to be simplified.
91 InstCombineWorklist Worklist;
93 /// Builder - This is an IRBuilder that automatically inserts new
94 /// instructions into the worklist when they are created.
95 typedef IRBuilder<true, TargetFolder, InstCombineIRInserter> BuilderTy;
98 static char ID; // Pass identification, replacement for typeid
99 InstCombiner() : FunctionPass(ID), DL(0), Builder(0) {
100 MinimizeSize = false;
101 initializeInstCombinerPass(*PassRegistry::getPassRegistry());
105 bool runOnFunction(Function &F) override;
107 bool DoOneIteration(Function &F, unsigned ItNum);
109 void getAnalysisUsage(AnalysisUsage &AU) const override;
111 const DataLayout *getDataLayout() const { return DL; }
113 TargetLibraryInfo *getTargetLibraryInfo() const { return TLI; }
115 // Visitation implementation - Implement instruction combining for different
116 // instruction types. The semantics are as follows:
118 // null - No change was made
119 // I - Change was made, I is still valid, I may be dead though
120 // otherwise - Change was made, replace I with returned instruction
122 Instruction *visitAdd(BinaryOperator &I);
123 Instruction *visitFAdd(BinaryOperator &I);
124 Value *OptimizePointerDifference(Value *LHS, Value *RHS, Type *Ty);
125 Instruction *visitSub(BinaryOperator &I);
126 Instruction *visitFSub(BinaryOperator &I);
127 Instruction *visitMul(BinaryOperator &I);
128 Value *foldFMulConst(Instruction *FMulOrDiv, Constant *C,
129 Instruction *InsertBefore);
130 Instruction *visitFMul(BinaryOperator &I);
131 Instruction *visitURem(BinaryOperator &I);
132 Instruction *visitSRem(BinaryOperator &I);
133 Instruction *visitFRem(BinaryOperator &I);
134 bool SimplifyDivRemOfSelect(BinaryOperator &I);
135 Instruction *commonRemTransforms(BinaryOperator &I);
136 Instruction *commonIRemTransforms(BinaryOperator &I);
137 Instruction *commonDivTransforms(BinaryOperator &I);
138 Instruction *commonIDivTransforms(BinaryOperator &I);
139 Instruction *visitUDiv(BinaryOperator &I);
140 Instruction *visitSDiv(BinaryOperator &I);
141 Instruction *visitFDiv(BinaryOperator &I);
142 Value *FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS);
143 Value *FoldAndOfFCmps(FCmpInst *LHS, FCmpInst *RHS);
144 Instruction *visitAnd(BinaryOperator &I);
145 Value *FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS);
146 Value *FoldOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS);
147 Instruction *FoldOrWithConstants(BinaryOperator &I, Value *Op,
148 Value *A, Value *B, Value *C);
149 Instruction *visitOr (BinaryOperator &I);
150 Instruction *visitXor(BinaryOperator &I);
151 Instruction *visitShl(BinaryOperator &I);
152 Instruction *visitAShr(BinaryOperator &I);
153 Instruction *visitLShr(BinaryOperator &I);
154 Instruction *commonShiftTransforms(BinaryOperator &I);
155 Instruction *FoldFCmp_IntToFP_Cst(FCmpInst &I, Instruction *LHSI,
157 Instruction *FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP,
158 GlobalVariable *GV, CmpInst &ICI,
159 ConstantInt *AndCst = 0);
160 Instruction *visitFCmpInst(FCmpInst &I);
161 Instruction *visitICmpInst(ICmpInst &I);
162 Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI);
163 Instruction *visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
166 Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
167 ConstantInt *DivRHS);
168 Instruction *FoldICmpShrCst(ICmpInst &ICI, BinaryOperator *DivI,
169 ConstantInt *DivRHS);
170 Instruction *FoldICmpAddOpCst(Instruction &ICI, Value *X, ConstantInt *CI,
171 ICmpInst::Predicate Pred);
172 Instruction *FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
173 ICmpInst::Predicate Cond, Instruction &I);
174 Instruction *FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
176 Instruction *commonCastTransforms(CastInst &CI);
177 Instruction *commonPointerCastTransforms(CastInst &CI);
178 Instruction *visitTrunc(TruncInst &CI);
179 Instruction *visitZExt(ZExtInst &CI);
180 Instruction *visitSExt(SExtInst &CI);
181 Instruction *visitFPTrunc(FPTruncInst &CI);
182 Instruction *visitFPExt(CastInst &CI);
183 Instruction *visitFPToUI(FPToUIInst &FI);
184 Instruction *visitFPToSI(FPToSIInst &FI);
185 Instruction *visitUIToFP(CastInst &CI);
186 Instruction *visitSIToFP(CastInst &CI);
187 Instruction *visitPtrToInt(PtrToIntInst &CI);
188 Instruction *visitIntToPtr(IntToPtrInst &CI);
189 Instruction *visitBitCast(BitCastInst &CI);
190 Instruction *visitAddrSpaceCast(AddrSpaceCastInst &CI);
191 Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
193 Instruction *FoldSelectIntoOp(SelectInst &SI, Value*, Value*);
194 Instruction *FoldSPFofSPF(Instruction *Inner, SelectPatternFlavor SPF1,
195 Value *A, Value *B, Instruction &Outer,
196 SelectPatternFlavor SPF2, Value *C);
197 Instruction *visitSelectInst(SelectInst &SI);
198 Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI);
199 Instruction *visitCallInst(CallInst &CI);
200 Instruction *visitInvokeInst(InvokeInst &II);
202 Instruction *SliceUpIllegalIntegerPHI(PHINode &PN);
203 Instruction *visitPHINode(PHINode &PN);
204 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
205 Instruction *visitAllocaInst(AllocaInst &AI);
206 Instruction *visitAllocSite(Instruction &FI);
207 Instruction *visitFree(CallInst &FI);
208 Instruction *visitLoadInst(LoadInst &LI);
209 Instruction *visitStoreInst(StoreInst &SI);
210 Instruction *visitBranchInst(BranchInst &BI);
211 Instruction *visitSwitchInst(SwitchInst &SI);
212 Instruction *visitInsertElementInst(InsertElementInst &IE);
213 Instruction *visitExtractElementInst(ExtractElementInst &EI);
214 Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
215 Instruction *visitExtractValueInst(ExtractValueInst &EV);
216 Instruction *visitLandingPadInst(LandingPadInst &LI);
218 // visitInstruction - Specify what to return for unhandled instructions...
219 Instruction *visitInstruction(Instruction &I) { return 0; }
222 bool ShouldChangeType(Type *From, Type *To) const;
223 Value *dyn_castNegVal(Value *V) const;
224 Value *dyn_castFNegVal(Value *V, bool NoSignedZero=false) const;
225 Type *FindElementAtOffset(Type *PtrTy, int64_t Offset,
226 SmallVectorImpl<Value*> &NewIndices);
227 Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI);
229 /// ShouldOptimizeCast - Return true if the cast from "V to Ty" actually
230 /// results in any code being generated and is interesting to optimize out. If
231 /// the cast can be eliminated by some other simple transformation, we prefer
232 /// to do the simplification first.
233 bool ShouldOptimizeCast(Instruction::CastOps opcode,const Value *V,
236 Instruction *visitCallSite(CallSite CS);
237 Instruction *tryOptimizeCall(CallInst *CI, const DataLayout *DL);
238 bool transformConstExprCastCall(CallSite CS);
239 Instruction *transformCallThroughTrampoline(CallSite CS,
240 IntrinsicInst *Tramp);
241 Instruction *transformZExtICmp(ICmpInst *ICI, Instruction &CI,
242 bool DoXform = true);
243 Instruction *transformSExtICmp(ICmpInst *ICI, Instruction &CI);
244 bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS);
245 Value *EmitGEPOffset(User *GEP);
246 Instruction *scalarizePHI(ExtractElementInst &EI, PHINode *PN);
247 Value *EvaluateInDifferentElementOrder(Value *V, ArrayRef<int> Mask);
250 // InsertNewInstBefore - insert an instruction New before instruction Old
251 // in the program. Add the new instruction to the worklist.
253 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
254 assert(New && New->getParent() == 0 &&
255 "New instruction already inserted into a basic block!");
256 BasicBlock *BB = Old.getParent();
257 BB->getInstList().insert(&Old, New); // Insert inst
262 // InsertNewInstWith - same as InsertNewInstBefore, but also sets the
265 Instruction *InsertNewInstWith(Instruction *New, Instruction &Old) {
266 New->setDebugLoc(Old.getDebugLoc());
267 return InsertNewInstBefore(New, Old);
270 // ReplaceInstUsesWith - This method is to be used when an instruction is
271 // found to be dead, replacable with another preexisting expression. Here
272 // we add all uses of I to the worklist, replace all uses of I with the new
273 // value, then return I, so that the inst combiner will know that I was
276 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
277 Worklist.AddUsersToWorkList(I); // Add all modified instrs to worklist.
279 // If we are replacing the instruction with itself, this must be in a
280 // segment of unreachable code, so just clobber the instruction.
282 V = UndefValue::get(I.getType());
284 DEBUG(dbgs() << "IC: Replacing " << I << "\n"
285 " with " << *V << '\n');
287 I.replaceAllUsesWith(V);
291 // EraseInstFromFunction - When dealing with an instruction that has side
292 // effects or produces a void value, we can't rely on DCE to delete the
293 // instruction. Instead, visit methods should return the value returned by
295 Instruction *EraseInstFromFunction(Instruction &I) {
296 DEBUG(dbgs() << "IC: ERASE " << I << '\n');
298 assert(I.use_empty() && "Cannot erase instruction that is used!");
299 // Make sure that we reprocess all operands now that we reduced their
301 if (I.getNumOperands() < 8) {
302 for (User::op_iterator i = I.op_begin(), e = I.op_end(); i != e; ++i)
303 if (Instruction *Op = dyn_cast<Instruction>(*i))
309 return 0; // Don't do anything with FI
312 void ComputeMaskedBits(Value *V, APInt &KnownZero,
313 APInt &KnownOne, unsigned Depth = 0) const {
314 return llvm::ComputeMaskedBits(V, KnownZero, KnownOne, DL, Depth);
317 bool MaskedValueIsZero(Value *V, const APInt &Mask,
318 unsigned Depth = 0) const {
319 return llvm::MaskedValueIsZero(V, Mask, DL, Depth);
321 unsigned ComputeNumSignBits(Value *Op, unsigned Depth = 0) const {
322 return llvm::ComputeNumSignBits(Op, DL, Depth);
327 /// SimplifyAssociativeOrCommutative - This performs a few simplifications for
328 /// operators which are associative or commutative.
329 bool SimplifyAssociativeOrCommutative(BinaryOperator &I);
331 /// SimplifyUsingDistributiveLaws - This tries to simplify binary operations
332 /// which some other binary operation distributes over either by factorizing
333 /// out common terms (eg "(A*B)+(A*C)" -> "A*(B+C)") or expanding out if this
334 /// results in simplifications (eg: "A & (B | C) -> (A&B) | (A&C)" if this is
335 /// a win). Returns the simplified value, or null if it didn't simplify.
336 Value *SimplifyUsingDistributiveLaws(BinaryOperator &I);
338 /// SimplifyDemandedUseBits - Attempts to replace V with a simpler value
339 /// based on the demanded bits.
340 Value *SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
341 APInt& KnownZero, APInt& KnownOne,
343 bool SimplifyDemandedBits(Use &U, APInt DemandedMask,
344 APInt& KnownZero, APInt& KnownOne,
346 /// Helper routine of SimplifyDemandedUseBits. It tries to simplify demanded
347 /// bit for "r1 = shr x, c1; r2 = shl r1, c2" instruction sequence.
348 Value *SimplifyShrShlDemandedBits(Instruction *Lsr, Instruction *Sftl,
349 APInt DemandedMask, APInt &KnownZero,
352 /// SimplifyDemandedInstructionBits - Inst is an integer instruction that
353 /// SimplifyDemandedBits knows about. See if the instruction has any
354 /// properties that allow us to simplify its operands.
355 bool SimplifyDemandedInstructionBits(Instruction &Inst);
357 Value *SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
358 APInt& UndefElts, unsigned Depth = 0);
360 // FoldOpIntoPhi - Given a binary operator, cast instruction, or select
361 // which has a PHI node as operand #0, see if we can fold the instruction
362 // into the PHI (which is only possible if all operands to the PHI are
365 Instruction *FoldOpIntoPhi(Instruction &I);
367 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
368 // operator and they all are only used by the PHI, PHI together their
369 // inputs, and do the operation once, to the result of the PHI.
370 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
371 Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN);
372 Instruction *FoldPHIArgGEPIntoPHI(PHINode &PN);
373 Instruction *FoldPHIArgLoadIntoPHI(PHINode &PN);
376 Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS,
377 ConstantInt *AndRHS, BinaryOperator &TheAnd);
379 Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask,
380 bool isSub, Instruction &I);
381 Value *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
382 bool isSigned, bool Inside);
383 Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocaInst &AI);
384 Instruction *MatchBSwap(BinaryOperator &I);
385 bool SimplifyStoreAtEndOfBlock(StoreInst &SI);
386 Instruction *SimplifyMemTransfer(MemIntrinsic *MI);
387 Instruction *SimplifyMemSet(MemSetInst *MI);
390 Value *EvaluateInDifferentType(Value *V, Type *Ty, bool isSigned);
392 /// Descale - Return a value X such that Val = X * Scale, or null if none. If
393 /// the multiplication is known not to overflow then NoSignedWrap is set.
394 Value *Descale(Value *Val, APInt Scale, bool &NoSignedWrap);
399 } // end namespace llvm.