InstCombine.h revision 27ceaa13f820e33c44e29adc2095dd3e1e69d09f
1//===- InstCombine.h - Main InstCombine pass definition -------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9 10#ifndef INSTCOMBINE_INSTCOMBINE_H 11#define INSTCOMBINE_INSTCOMBINE_H 12 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" 19 20namespace llvm { 21 class CallSite; 22 class TargetData; 23 class DbgDeclareInst; 24 class MemIntrinsic; 25 class MemSetInst; 26 27/// SelectPatternFlavor - We can match a variety of different patterns for 28/// select operations. 29enum SelectPatternFlavor { 30 SPF_UNKNOWN = 0, 31 SPF_SMIN, SPF_UMIN, 32 SPF_SMAX, SPF_UMAX 33 //SPF_ABS - TODO. 34}; 35 36/// getComplexity: Assign a complexity or rank value to LLVM Values... 37/// 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst 38static inline unsigned getComplexity(Value *V) { 39 if (isa<Instruction>(V)) { 40 if (BinaryOperator::isNeg(V) || 41 BinaryOperator::isFNeg(V) || 42 BinaryOperator::isNot(V)) 43 return 3; 44 return 4; 45 } 46 if (isa<Argument>(V)) return 3; 47 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2; 48} 49 50 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. 54class VISIBILITY_HIDDEN InstCombineIRInserter 55 : public IRBuilderDefaultInserter<true> { 56 InstCombineWorklist &Worklist; 57public: 58 InstCombineIRInserter(InstCombineWorklist &WL) : Worklist(WL) {} 59 60 void InsertHelper(Instruction *I, const Twine &Name, 61 BasicBlock *BB, BasicBlock::iterator InsertPt) const { 62 IRBuilderDefaultInserter<true>::InsertHelper(I, Name, BB, InsertPt); 63 Worklist.Add(I); 64 } 65}; 66 67/// InstCombiner - The -instcombine pass. 68class VISIBILITY_HIDDEN InstCombiner 69 : public FunctionPass, 70 public InstVisitor<InstCombiner, Instruction*> { 71 TargetData *TD; 72 bool MustPreserveLCSSA; 73 bool MadeIRChange; 74public: 75 /// Worklist - All of the instructions that need to be simplified. 76 InstCombineWorklist Worklist; 77 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; 81 BuilderTy *Builder; 82 83 static char ID; // Pass identification, replacement for typeid 84 InstCombiner() : FunctionPass(&ID), TD(0), Builder(0) {} 85 86public: 87 virtual bool runOnFunction(Function &F); 88 89 bool DoOneIteration(Function &F, unsigned ItNum); 90 91 virtual void getAnalysisUsage(AnalysisUsage &AU) const; 92 93 TargetData *getTargetData() const { return TD; } 94 95 // Visitation implementation - Implement instruction combining for different 96 // instruction types. The semantics are as follows: 97 // Return Value: 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 101 // 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, 134 Constant *RHSC); 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, 142 Instruction *LHS, 143 ConstantInt *RHS); 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, 151 BinaryOperator &I); 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, 167 Instruction *FI); 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); 176 177 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); 190 191 // visitInstruction - Specify what to return for unhandled instructions... 192 Instruction *visitInstruction(Instruction &I) { return 0; } 193 194private: 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); 201 202 /// 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, 207 const Type *Ty); 208 209 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); 218 219public: 220 // InsertNewInstBefore - insert an instruction New before instruction Old 221 // in the program. Add the new instruction to the worklist. 222 // 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 228 Worklist.Add(New); 229 return New; 230 } 231 232 // 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 236 // modified. 237 // 238 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) { 239 Worklist.AddUsersToWorkList(I); // Add all modified instrs to worklist. 240 241 // If we are replacing the instruction with itself, this must be in a 242 // segment of unreachable code, so just clobber the instruction. 243 if (&I == V) 244 V = UndefValue::get(I.getType()); 245 246 I.replaceAllUsesWith(V); 247 return &I; 248 } 249 250 // 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 253 // this function. 254 Instruction *EraseInstFromFunction(Instruction &I) { 255 DEBUG(errs() << "IC: ERASE " << I << '\n'); 256 257 assert(I.use_empty() && "Cannot erase instruction that is used!"); 258 // Make sure that we reprocess all operands now that we reduced their 259 // use counts. 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)) 263 Worklist.Add(Op); 264 } 265 Worklist.Remove(&I); 266 I.eraseFromParent(); 267 MadeIRChange = true; 268 return 0; // Don't do anything with FI 269 } 270 271 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); 274 } 275 276 bool MaskedValueIsZero(Value *V, const APInt &Mask, 277 unsigned Depth = 0) const { 278 return llvm::MaskedValueIsZero(V, Mask, TD, Depth); 279 } 280 unsigned ComputeNumSignBits(Value *Op, unsigned Depth = 0) const { 281 return llvm::ComputeNumSignBits(Op, TD, Depth); 282 } 283 284private: 285 286 /// SimplifyCommutative - This performs a few simplifications for 287 /// commutative operators. 288 bool SimplifyCommutative(BinaryOperator &I); 289 290 /// 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, 294 unsigned Depth); 295 bool SimplifyDemandedBits(Use &U, APInt DemandedMask, 296 APInt& KnownZero, APInt& KnownOne, 297 unsigned Depth=0); 298 299 /// 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); 303 304 Value *SimplifyDemandedVectorElts(Value *V, APInt DemandedElts, 305 APInt& UndefElts, unsigned Depth = 0); 306 307 // 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 310 // constants). 311 // 312 // If AllowAggressive is true, FoldOpIntoPhi will allow certain transforms 313 // that would normally be unprofitable because they strongly encourage jump 314 // threading. 315 Instruction *FoldOpIntoPhi(Instruction &I, bool AllowAggressive = false); 316 317 // 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); 324 325 326 Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS, 327 ConstantInt *AndRHS, BinaryOperator &TheAnd); 328 329 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); 338 339 340 Value *EvaluateInDifferentType(Value *V, const Type *Ty, bool isSigned); 341 342 unsigned GetOrEnforceKnownAlignment(Value *V, 343 unsigned PrefAlign = 0); 344 345}; 346 347 348 349} // end namespace llvm. 350 351#endif 352