1 //===- InstCombine.h - Main InstCombine pass definition -------------------===//
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/Pass.h"
15 #include "llvm/Analysis/ValueTracking.h"
16 #include "llvm/Support/IRBuilder.h"
17 #include "llvm/Support/InstVisitor.h"
18 #include "llvm/Support/TargetFolder.h"
27 /// SelectPatternFlavor - We can match a variety of different patterns for
28 /// select operations.
29 enum SelectPatternFlavor {
36 /// getComplexity: Assign a complexity or rank value to LLVM Values...
37 /// 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
38 static inline unsigned getComplexity(Value *V) {
39 if (isa<Instruction>(V)) {
40 if (BinaryOperator::isNeg(V) ||
41 BinaryOperator::isFNeg(V) ||
42 BinaryOperator::isNot(V))
46 if (isa<Argument>(V)) return 3;
47 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
51 /// InstCombineIRInserter - This is an IRBuilder insertion helper that works
52 /// just like the normal insertion helper, but also adds any new instructions
53 /// to the instcombine worklist.
54 class VISIBILITY_HIDDEN InstCombineIRInserter
55 : public IRBuilderDefaultInserter<true> {
56 InstCombineWorklist &Worklist;
58 InstCombineIRInserter(InstCombineWorklist &WL) : Worklist(WL) {}
60 void InsertHelper(Instruction *I, const Twine &Name,
61 BasicBlock *BB, BasicBlock::iterator InsertPt) const {
62 IRBuilderDefaultInserter<true>::InsertHelper(I, Name, BB, InsertPt);
67 /// InstCombiner - The -instcombine pass.
68 class VISIBILITY_HIDDEN InstCombiner
69 : public FunctionPass,
70 public InstVisitor<InstCombiner, Instruction*> {
72 bool MustPreserveLCSSA;
75 /// Worklist - All of the instructions that need to be simplified.
76 InstCombineWorklist Worklist;
78 /// Builder - This is an IRBuilder that automatically inserts new
79 /// instructions into the worklist when they are created.
80 typedef IRBuilder<true, TargetFolder, InstCombineIRInserter> BuilderTy;
83 static char ID; // Pass identification, replacement for typeid
84 InstCombiner() : FunctionPass(&ID), TD(0), Builder(0) {}
87 virtual bool runOnFunction(Function &F);
89 bool DoOneIteration(Function &F, unsigned ItNum);
91 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
93 TargetData *getTargetData() const { return TD; }
95 // Visitation implementation - Implement instruction combining for different
96 // instruction types. The semantics are as follows:
98 // null - No change was made
99 // I - Change was made, I is still valid, I may be dead though
100 // otherwise - Change was made, replace I with returned instruction
102 Instruction *visitAdd(BinaryOperator &I);
103 Instruction *visitFAdd(BinaryOperator &I);
104 Value *OptimizePointerDifference(Value *LHS, Value *RHS, const Type *Ty);
105 Instruction *visitSub(BinaryOperator &I);
106 Instruction *visitFSub(BinaryOperator &I);
107 Instruction *visitMul(BinaryOperator &I);
108 Instruction *visitFMul(BinaryOperator &I);
109 Instruction *visitURem(BinaryOperator &I);
110 Instruction *visitSRem(BinaryOperator &I);
111 Instruction *visitFRem(BinaryOperator &I);
112 bool SimplifyDivRemOfSelect(BinaryOperator &I);
113 Instruction *commonRemTransforms(BinaryOperator &I);
114 Instruction *commonIRemTransforms(BinaryOperator &I);
115 Instruction *commonDivTransforms(BinaryOperator &I);
116 Instruction *commonIDivTransforms(BinaryOperator &I);
117 Instruction *visitUDiv(BinaryOperator &I);
118 Instruction *visitSDiv(BinaryOperator &I);
119 Instruction *visitFDiv(BinaryOperator &I);
120 Value *FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS);
121 Value *FoldAndOfFCmps(FCmpInst *LHS, FCmpInst *RHS);
122 Instruction *visitAnd(BinaryOperator &I);
123 Value *FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS);
124 Value *FoldOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS);
125 Instruction *FoldOrWithConstants(BinaryOperator &I, Value *Op,
126 Value *A, Value *B, Value *C);
127 Instruction *visitOr (BinaryOperator &I);
128 Instruction *visitXor(BinaryOperator &I);
129 Instruction *visitShl(BinaryOperator &I);
130 Instruction *visitAShr(BinaryOperator &I);
131 Instruction *visitLShr(BinaryOperator &I);
132 Instruction *commonShiftTransforms(BinaryOperator &I);
133 Instruction *FoldFCmp_IntToFP_Cst(FCmpInst &I, Instruction *LHSI,
135 Instruction *FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP,
136 GlobalVariable *GV, CmpInst &ICI,
137 ConstantInt *AndCst = 0);
138 Instruction *visitFCmpInst(FCmpInst &I);
139 Instruction *visitICmpInst(ICmpInst &I);
140 Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI);
141 Instruction *visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
144 Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
145 ConstantInt *DivRHS);
146 Instruction *FoldICmpAddOpCst(ICmpInst &ICI, Value *X, ConstantInt *CI,
147 ICmpInst::Predicate Pred, Value *TheAdd);
148 Instruction *FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
149 ICmpInst::Predicate Cond, Instruction &I);
150 Instruction *FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
152 Instruction *commonCastTransforms(CastInst &CI);
153 Instruction *commonPointerCastTransforms(CastInst &CI);
154 Instruction *visitTrunc(TruncInst &CI);
155 Instruction *visitZExt(ZExtInst &CI);
156 Instruction *visitSExt(SExtInst &CI);
157 Instruction *visitFPTrunc(FPTruncInst &CI);
158 Instruction *visitFPExt(CastInst &CI);
159 Instruction *visitFPToUI(FPToUIInst &FI);
160 Instruction *visitFPToSI(FPToSIInst &FI);
161 Instruction *visitUIToFP(CastInst &CI);
162 Instruction *visitSIToFP(CastInst &CI);
163 Instruction *visitPtrToInt(PtrToIntInst &CI);
164 Instruction *visitIntToPtr(IntToPtrInst &CI);
165 Instruction *visitBitCast(BitCastInst &CI);
166 Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
168 Instruction *FoldSelectIntoOp(SelectInst &SI, Value*, Value*);
169 Instruction *FoldSPFofSPF(Instruction *Inner, SelectPatternFlavor SPF1,
170 Value *A, Value *B, Instruction &Outer,
171 SelectPatternFlavor SPF2, Value *C);
172 Instruction *visitSelectInst(SelectInst &SI);
173 Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI);
174 Instruction *visitCallInst(CallInst &CI);
175 Instruction *visitInvokeInst(InvokeInst &II);
177 Instruction *SliceUpIllegalIntegerPHI(PHINode &PN);
178 Instruction *visitPHINode(PHINode &PN);
179 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
180 Instruction *visitAllocaInst(AllocaInst &AI);
181 Instruction *visitFree(Instruction &FI);
182 Instruction *visitLoadInst(LoadInst &LI);
183 Instruction *visitStoreInst(StoreInst &SI);
184 Instruction *visitBranchInst(BranchInst &BI);
185 Instruction *visitSwitchInst(SwitchInst &SI);
186 Instruction *visitInsertElementInst(InsertElementInst &IE);
187 Instruction *visitExtractElementInst(ExtractElementInst &EI);
188 Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
189 Instruction *visitExtractValueInst(ExtractValueInst &EV);
191 // visitInstruction - Specify what to return for unhandled instructions...
192 Instruction *visitInstruction(Instruction &I) { return 0; }
195 bool ShouldChangeType(const Type *From, const Type *To) const;
196 Value *dyn_castNegVal(Value *V) const;
197 Value *dyn_castFNegVal(Value *V) const;
198 const Type *FindElementAtOffset(const Type *Ty, int64_t Offset,
199 SmallVectorImpl<Value*> &NewIndices);
200 Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI);
202 /// ShouldOptimizeCast - Return true if the cast from "V to Ty" actually
203 /// results in any code being generated and is interesting to optimize out. If
204 /// the cast can be eliminated by some other simple transformation, we prefer
205 /// to do the simplification first.
206 bool ShouldOptimizeCast(Instruction::CastOps opcode,const Value *V,
209 Instruction *visitCallSite(CallSite CS);
210 Instruction *tryOptimizeCall(CallInst *CI, const TargetData *TD);
211 bool transformConstExprCastCall(CallSite CS);
212 Instruction *transformCallThroughTrampoline(CallSite CS);
213 Instruction *transformZExtICmp(ICmpInst *ICI, Instruction &CI,
214 bool DoXform = true);
215 bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS);
216 DbgDeclareInst *hasOneUsePlusDeclare(Value *V);
217 Value *EmitGEPOffset(User *GEP);
220 // InsertNewInstBefore - insert an instruction New before instruction Old
221 // in the program. Add the new instruction to the worklist.
223 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
224 assert(New && New->getParent() == 0 &&
225 "New instruction already inserted into a basic block!");
226 BasicBlock *BB = Old.getParent();
227 BB->getInstList().insert(&Old, New); // Insert inst
232 // ReplaceInstUsesWith - This method is to be used when an instruction is
233 // found to be dead, replacable with another preexisting expression. Here
234 // we add all uses of I to the worklist, replace all uses of I with the new
235 // value, then return I, so that the inst combiner will know that I was
238 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
239 Worklist.AddUsersToWorkList(I); // Add all modified instrs to worklist.
241 // If we are replacing the instruction with itself, this must be in a
242 // segment of unreachable code, so just clobber the instruction.
244 V = UndefValue::get(I.getType());
246 I.replaceAllUsesWith(V);
250 // EraseInstFromFunction - When dealing with an instruction that has side
251 // effects or produces a void value, we can't rely on DCE to delete the
252 // instruction. Instead, visit methods should return the value returned by
254 Instruction *EraseInstFromFunction(Instruction &I) {
255 DEBUG(errs() << "IC: ERASE " << I << '\n');
257 assert(I.use_empty() && "Cannot erase instruction that is used!");
258 // Make sure that we reprocess all operands now that we reduced their
260 if (I.getNumOperands() < 8) {
261 for (User::op_iterator i = I.op_begin(), e = I.op_end(); i != e; ++i)
262 if (Instruction *Op = dyn_cast<Instruction>(*i))
268 return 0; // Don't do anything with FI
271 void ComputeMaskedBits(Value *V, const APInt &Mask, APInt &KnownZero,
272 APInt &KnownOne, unsigned Depth = 0) const {
273 return llvm::ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD, Depth);
276 bool MaskedValueIsZero(Value *V, const APInt &Mask,
277 unsigned Depth = 0) const {
278 return llvm::MaskedValueIsZero(V, Mask, TD, Depth);
280 unsigned ComputeNumSignBits(Value *Op, unsigned Depth = 0) const {
281 return llvm::ComputeNumSignBits(Op, TD, Depth);
286 /// SimplifyCommutative - This performs a few simplifications for
287 /// commutative operators.
288 bool SimplifyCommutative(BinaryOperator &I);
290 /// SimplifyDemandedUseBits - Attempts to replace V with a simpler value
291 /// based on the demanded bits.
292 Value *SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
293 APInt& KnownZero, APInt& KnownOne,
295 bool SimplifyDemandedBits(Use &U, APInt DemandedMask,
296 APInt& KnownZero, APInt& KnownOne,
299 /// SimplifyDemandedInstructionBits - Inst is an integer instruction that
300 /// SimplifyDemandedBits knows about. See if the instruction has any
301 /// properties that allow us to simplify its operands.
302 bool SimplifyDemandedInstructionBits(Instruction &Inst);
304 Value *SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
305 APInt& UndefElts, unsigned Depth = 0);
307 // FoldOpIntoPhi - Given a binary operator, cast instruction, or select
308 // which has a PHI node as operand #0, see if we can fold the instruction
309 // into the PHI (which is only possible if all operands to the PHI are
312 // If AllowAggressive is true, FoldOpIntoPhi will allow certain transforms
313 // that would normally be unprofitable because they strongly encourage jump
315 Instruction *FoldOpIntoPhi(Instruction &I, bool AllowAggressive = false);
317 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
318 // operator and they all are only used by the PHI, PHI together their
319 // inputs, and do the operation once, to the result of the PHI.
320 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
321 Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN);
322 Instruction *FoldPHIArgGEPIntoPHI(PHINode &PN);
323 Instruction *FoldPHIArgLoadIntoPHI(PHINode &PN);
326 Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS,
327 ConstantInt *AndRHS, BinaryOperator &TheAnd);
329 Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask,
330 bool isSub, Instruction &I);
331 Value *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
332 bool isSigned, bool Inside);
333 Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocaInst &AI);
334 Instruction *MatchBSwap(BinaryOperator &I);
335 bool SimplifyStoreAtEndOfBlock(StoreInst &SI);
336 Instruction *SimplifyMemTransfer(MemIntrinsic *MI);
337 Instruction *SimplifyMemSet(MemSetInst *MI);
340 Value *EvaluateInDifferentType(Value *V, const Type *Ty, bool isSigned);
342 unsigned GetOrEnforceKnownAlignment(Value *V,
343 unsigned PrefAlign = 0);
349 } // end namespace llvm.