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/Analysis/ValueTracking.h" 15 #include "llvm/IR/IRBuilder.h" 16 #include "llvm/IR/IntrinsicInst.h" 17 #include "llvm/IR/Operator.h" 18 #include "llvm/InstVisitor.h" 19 #include "llvm/Pass.h" 20 #include "llvm/Support/TargetFolder.h" 21 #include "llvm/Transforms/Utils/SimplifyLibCalls.h" 22 23 namespace llvm { 24 class CallSite; 25 class DataLayout; 26 class TargetLibraryInfo; 27 class DbgDeclareInst; 28 class MemIntrinsic; 29 class MemSetInst; 30 31 /// SelectPatternFlavor - We can match a variety of different patterns for 32 /// select operations. 33 enum SelectPatternFlavor { 34 SPF_UNKNOWN = 0, 35 SPF_SMIN, SPF_UMIN, 36 SPF_SMAX, SPF_UMAX 37 //SPF_ABS - TODO. 38 }; 39 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)) 47 return 3; 48 return 4; 49 } 50 if (isa<Argument>(V)) return 3; 51 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2; 52 } 53 54 55 /// InstCombineIRInserter - This is an IRBuilder insertion helper that works 56 /// just like the normal insertion helper, but also adds any new instructions 57 /// to the instcombine worklist. 58 class LLVM_LIBRARY_VISIBILITY InstCombineIRInserter 59 : public IRBuilderDefaultInserter<true> { 60 InstCombineWorklist &Worklist; 61 public: 62 InstCombineIRInserter(InstCombineWorklist &WL) : Worklist(WL) {} 63 64 void InsertHelper(Instruction *I, const Twine &Name, 65 BasicBlock *BB, BasicBlock::iterator InsertPt) const { 66 IRBuilderDefaultInserter<true>::InsertHelper(I, Name, BB, InsertPt); 67 Worklist.Add(I); 68 } 69 }; 70 71 /// InstCombiner - The -instcombine pass. 72 class LLVM_LIBRARY_VISIBILITY InstCombiner 73 : public FunctionPass, 74 public InstVisitor<InstCombiner, Instruction*> { 75 DataLayout *TD; 76 TargetLibraryInfo *TLI; 77 bool MadeIRChange; 78 LibCallSimplifier *Simplifier; 79 bool MinimizeSize; 80 public: 81 /// Worklist - All of the instructions that need to be simplified. 82 InstCombineWorklist Worklist; 83 84 /// Builder - This is an IRBuilder that automatically inserts new 85 /// instructions into the worklist when they are created. 86 typedef IRBuilder<true, TargetFolder, InstCombineIRInserter> BuilderTy; 87 BuilderTy *Builder; 88 89 static char ID; // Pass identification, replacement for typeid 90 InstCombiner() : FunctionPass(ID), TD(0), Builder(0) { 91 MinimizeSize = false; 92 initializeInstCombinerPass(*PassRegistry::getPassRegistry()); 93 } 94 95 public: 96 virtual bool runOnFunction(Function &F); 97 98 bool DoOneIteration(Function &F, unsigned ItNum); 99 100 virtual void getAnalysisUsage(AnalysisUsage &AU) const; 101 102 DataLayout *getDataLayout() const { return TD; } 103 104 TargetLibraryInfo *getTargetLibraryInfo() const { return TLI; } 105 106 // Visitation implementation - Implement instruction combining for different 107 // instruction types. The semantics are as follows: 108 // Return Value: 109 // null - No change was made 110 // I - Change was made, I is still valid, I may be dead though 111 // otherwise - Change was made, replace I with returned instruction 112 // 113 Instruction *visitAdd(BinaryOperator &I); 114 Instruction *visitFAdd(BinaryOperator &I); 115 Value *OptimizePointerDifference(Value *LHS, Value *RHS, Type *Ty); 116 Instruction *visitSub(BinaryOperator &I); 117 Instruction *visitFSub(BinaryOperator &I); 118 Instruction *visitMul(BinaryOperator &I); 119 Value *foldFMulConst(Instruction *FMulOrDiv, ConstantFP *C, 120 Instruction *InsertBefore); 121 Instruction *visitFMul(BinaryOperator &I); 122 Instruction *visitURem(BinaryOperator &I); 123 Instruction *visitSRem(BinaryOperator &I); 124 Instruction *visitFRem(BinaryOperator &I); 125 bool SimplifyDivRemOfSelect(BinaryOperator &I); 126 Instruction *commonRemTransforms(BinaryOperator &I); 127 Instruction *commonIRemTransforms(BinaryOperator &I); 128 Instruction *commonDivTransforms(BinaryOperator &I); 129 Instruction *commonIDivTransforms(BinaryOperator &I); 130 Instruction *visitUDiv(BinaryOperator &I); 131 Instruction *visitSDiv(BinaryOperator &I); 132 Instruction *visitFDiv(BinaryOperator &I); 133 Value *FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS); 134 Value *FoldAndOfFCmps(FCmpInst *LHS, FCmpInst *RHS); 135 Instruction *visitAnd(BinaryOperator &I); 136 Value *FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS); 137 Value *FoldOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS); 138 Instruction *FoldOrWithConstants(BinaryOperator &I, Value *Op, 139 Value *A, Value *B, Value *C); 140 Instruction *visitOr (BinaryOperator &I); 141 Instruction *visitXor(BinaryOperator &I); 142 Instruction *visitShl(BinaryOperator &I); 143 Instruction *visitAShr(BinaryOperator &I); 144 Instruction *visitLShr(BinaryOperator &I); 145 Instruction *commonShiftTransforms(BinaryOperator &I); 146 Instruction *FoldFCmp_IntToFP_Cst(FCmpInst &I, Instruction *LHSI, 147 Constant *RHSC); 148 Instruction *FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, 149 GlobalVariable *GV, CmpInst &ICI, 150 ConstantInt *AndCst = 0); 151 Instruction *visitFCmpInst(FCmpInst &I); 152 Instruction *visitICmpInst(ICmpInst &I); 153 Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI); 154 Instruction *visitICmpInstWithInstAndIntCst(ICmpInst &ICI, 155 Instruction *LHS, 156 ConstantInt *RHS); 157 Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI, 158 ConstantInt *DivRHS); 159 Instruction *FoldICmpShrCst(ICmpInst &ICI, BinaryOperator *DivI, 160 ConstantInt *DivRHS); 161 Instruction *FoldICmpAddOpCst(ICmpInst &ICI, Value *X, ConstantInt *CI, 162 ICmpInst::Predicate Pred, Value *TheAdd); 163 Instruction *FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS, 164 ICmpInst::Predicate Cond, Instruction &I); 165 Instruction *FoldShiftByConstant(Value *Op0, ConstantInt *Op1, 166 BinaryOperator &I); 167 Instruction *commonCastTransforms(CastInst &CI); 168 Instruction *commonPointerCastTransforms(CastInst &CI); 169 Instruction *visitTrunc(TruncInst &CI); 170 Instruction *visitZExt(ZExtInst &CI); 171 Instruction *visitSExt(SExtInst &CI); 172 Instruction *visitFPTrunc(FPTruncInst &CI); 173 Instruction *visitFPExt(CastInst &CI); 174 Instruction *visitFPToUI(FPToUIInst &FI); 175 Instruction *visitFPToSI(FPToSIInst &FI); 176 Instruction *visitUIToFP(CastInst &CI); 177 Instruction *visitSIToFP(CastInst &CI); 178 Instruction *visitPtrToInt(PtrToIntInst &CI); 179 Instruction *visitIntToPtr(IntToPtrInst &CI); 180 Instruction *visitBitCast(BitCastInst &CI); 181 Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI, 182 Instruction *FI); 183 Instruction *FoldSelectIntoOp(SelectInst &SI, Value*, Value*); 184 Instruction *FoldSPFofSPF(Instruction *Inner, SelectPatternFlavor SPF1, 185 Value *A, Value *B, Instruction &Outer, 186 SelectPatternFlavor SPF2, Value *C); 187 Instruction *visitSelectInst(SelectInst &SI); 188 Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI); 189 Instruction *visitCallInst(CallInst &CI); 190 Instruction *visitInvokeInst(InvokeInst &II); 191 192 Instruction *SliceUpIllegalIntegerPHI(PHINode &PN); 193 Instruction *visitPHINode(PHINode &PN); 194 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP); 195 Instruction *visitAllocaInst(AllocaInst &AI); 196 Instruction *visitAllocSite(Instruction &FI); 197 Instruction *visitFree(CallInst &FI); 198 Instruction *visitLoadInst(LoadInst &LI); 199 Instruction *visitStoreInst(StoreInst &SI); 200 Instruction *visitBranchInst(BranchInst &BI); 201 Instruction *visitSwitchInst(SwitchInst &SI); 202 Instruction *visitInsertElementInst(InsertElementInst &IE); 203 Instruction *visitExtractElementInst(ExtractElementInst &EI); 204 Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI); 205 Instruction *visitExtractValueInst(ExtractValueInst &EV); 206 Instruction *visitLandingPadInst(LandingPadInst &LI); 207 208 // visitInstruction - Specify what to return for unhandled instructions... 209 Instruction *visitInstruction(Instruction &I) { return 0; } 210 211 private: 212 bool ShouldChangeType(Type *From, Type *To) const; 213 Value *dyn_castNegVal(Value *V) const; 214 Value *dyn_castFNegVal(Value *V, bool NoSignedZero=false) const; 215 Type *FindElementAtOffset(Type *Ty, int64_t Offset, 216 SmallVectorImpl<Value*> &NewIndices); 217 Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI); 218 219 /// ShouldOptimizeCast - Return true if the cast from "V to Ty" actually 220 /// results in any code being generated and is interesting to optimize out. If 221 /// the cast can be eliminated by some other simple transformation, we prefer 222 /// to do the simplification first. 223 bool ShouldOptimizeCast(Instruction::CastOps opcode,const Value *V, 224 Type *Ty); 225 226 Instruction *visitCallSite(CallSite CS); 227 Instruction *tryOptimizeCall(CallInst *CI, const DataLayout *TD); 228 bool transformConstExprCastCall(CallSite CS); 229 Instruction *transformCallThroughTrampoline(CallSite CS, 230 IntrinsicInst *Tramp); 231 Instruction *transformZExtICmp(ICmpInst *ICI, Instruction &CI, 232 bool DoXform = true); 233 Instruction *transformSExtICmp(ICmpInst *ICI, Instruction &CI); 234 bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS); 235 Value *EmitGEPOffset(User *GEP); 236 237 public: 238 // InsertNewInstBefore - insert an instruction New before instruction Old 239 // in the program. Add the new instruction to the worklist. 240 // 241 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) { 242 assert(New && New->getParent() == 0 && 243 "New instruction already inserted into a basic block!"); 244 BasicBlock *BB = Old.getParent(); 245 BB->getInstList().insert(&Old, New); // Insert inst 246 Worklist.Add(New); 247 return New; 248 } 249 250 // InsertNewInstWith - same as InsertNewInstBefore, but also sets the 251 // debug loc. 252 // 253 Instruction *InsertNewInstWith(Instruction *New, Instruction &Old) { 254 New->setDebugLoc(Old.getDebugLoc()); 255 return InsertNewInstBefore(New, Old); 256 } 257 258 // ReplaceInstUsesWith - This method is to be used when an instruction is 259 // found to be dead, replacable with another preexisting expression. Here 260 // we add all uses of I to the worklist, replace all uses of I with the new 261 // value, then return I, so that the inst combiner will know that I was 262 // modified. 263 // 264 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) { 265 Worklist.AddUsersToWorkList(I); // Add all modified instrs to worklist. 266 267 // If we are replacing the instruction with itself, this must be in a 268 // segment of unreachable code, so just clobber the instruction. 269 if (&I == V) 270 V = UndefValue::get(I.getType()); 271 272 DEBUG(errs() << "IC: Replacing " << I << "\n" 273 " with " << *V << '\n'); 274 275 I.replaceAllUsesWith(V); 276 return &I; 277 } 278 279 // EraseInstFromFunction - When dealing with an instruction that has side 280 // effects or produces a void value, we can't rely on DCE to delete the 281 // instruction. Instead, visit methods should return the value returned by 282 // this function. 283 Instruction *EraseInstFromFunction(Instruction &I) { 284 DEBUG(errs() << "IC: ERASE " << I << '\n'); 285 286 assert(I.use_empty() && "Cannot erase instruction that is used!"); 287 // Make sure that we reprocess all operands now that we reduced their 288 // use counts. 289 if (I.getNumOperands() < 8) { 290 for (User::op_iterator i = I.op_begin(), e = I.op_end(); i != e; ++i) 291 if (Instruction *Op = dyn_cast<Instruction>(*i)) 292 Worklist.Add(Op); 293 } 294 Worklist.Remove(&I); 295 I.eraseFromParent(); 296 MadeIRChange = true; 297 return 0; // Don't do anything with FI 298 } 299 300 void ComputeMaskedBits(Value *V, APInt &KnownZero, 301 APInt &KnownOne, unsigned Depth = 0) const { 302 return llvm::ComputeMaskedBits(V, KnownZero, KnownOne, TD, Depth); 303 } 304 305 bool MaskedValueIsZero(Value *V, const APInt &Mask, 306 unsigned Depth = 0) const { 307 return llvm::MaskedValueIsZero(V, Mask, TD, Depth); 308 } 309 unsigned ComputeNumSignBits(Value *Op, unsigned Depth = 0) const { 310 return llvm::ComputeNumSignBits(Op, TD, Depth); 311 } 312 313 private: 314 315 /// SimplifyAssociativeOrCommutative - This performs a few simplifications for 316 /// operators which are associative or commutative. 317 bool SimplifyAssociativeOrCommutative(BinaryOperator &I); 318 319 /// SimplifyUsingDistributiveLaws - This tries to simplify binary operations 320 /// which some other binary operation distributes over either by factorizing 321 /// out common terms (eg "(A*B)+(A*C)" -> "A*(B+C)") or expanding out if this 322 /// results in simplifications (eg: "A & (B | C) -> (A&B) | (A&C)" if this is 323 /// a win). Returns the simplified value, or null if it didn't simplify. 324 Value *SimplifyUsingDistributiveLaws(BinaryOperator &I); 325 326 /// SimplifyDemandedUseBits - Attempts to replace V with a simpler value 327 /// based on the demanded bits. 328 Value *SimplifyDemandedUseBits(Value *V, APInt DemandedMask, 329 APInt& KnownZero, APInt& KnownOne, 330 unsigned Depth); 331 bool SimplifyDemandedBits(Use &U, APInt DemandedMask, 332 APInt& KnownZero, APInt& KnownOne, 333 unsigned Depth=0); 334 /// Helper routine of SimplifyDemandedUseBits. It tries to simplify demanded 335 /// bit for "r1 = shr x, c1; r2 = shl r1, c2" instruction sequence. 336 Value *SimplifyShrShlDemandedBits(Instruction *Lsr, Instruction *Sftl, 337 APInt DemandedMask, APInt &KnownZero, 338 APInt &KnownOne); 339 340 /// SimplifyDemandedInstructionBits - Inst is an integer instruction that 341 /// SimplifyDemandedBits knows about. See if the instruction has any 342 /// properties that allow us to simplify its operands. 343 bool SimplifyDemandedInstructionBits(Instruction &Inst); 344 345 Value *SimplifyDemandedVectorElts(Value *V, APInt DemandedElts, 346 APInt& UndefElts, unsigned Depth = 0); 347 348 // FoldOpIntoPhi - Given a binary operator, cast instruction, or select 349 // which has a PHI node as operand #0, see if we can fold the instruction 350 // into the PHI (which is only possible if all operands to the PHI are 351 // constants). 352 // 353 Instruction *FoldOpIntoPhi(Instruction &I); 354 355 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary" 356 // operator and they all are only used by the PHI, PHI together their 357 // inputs, and do the operation once, to the result of the PHI. 358 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN); 359 Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN); 360 Instruction *FoldPHIArgGEPIntoPHI(PHINode &PN); 361 Instruction *FoldPHIArgLoadIntoPHI(PHINode &PN); 362 363 364 Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS, 365 ConstantInt *AndRHS, BinaryOperator &TheAnd); 366 367 Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask, 368 bool isSub, Instruction &I); 369 Value *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi, 370 bool isSigned, bool Inside); 371 Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocaInst &AI); 372 Instruction *MatchBSwap(BinaryOperator &I); 373 bool SimplifyStoreAtEndOfBlock(StoreInst &SI); 374 Instruction *SimplifyMemTransfer(MemIntrinsic *MI); 375 Instruction *SimplifyMemSet(MemSetInst *MI); 376 377 378 Value *EvaluateInDifferentType(Value *V, Type *Ty, bool isSigned); 379 380 /// Descale - Return a value X such that Val = X * Scale, or null if none. If 381 /// the multiplication is known not to overflow then NoSignedWrap is set. 382 Value *Descale(Value *Val, APInt Scale, bool &NoSignedWrap); 383 }; 384 385 386 387 } // end namespace llvm. 388 389 #endif 390
