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 {
37 /// InstCombineIRInserter - This is an IRBuilder insertion helper that works
38 /// just like the normal insertion helper, but also adds any new instructions
39 /// to the instcombine worklist.
40 class VISIBILITY_HIDDEN InstCombineIRInserter
41 : public IRBuilderDefaultInserter<true> {
42 InstCombineWorklist &Worklist;
44 InstCombineIRInserter(InstCombineWorklist &WL) : Worklist(WL) {}
46 void InsertHelper(Instruction *I, const Twine &Name,
47 BasicBlock *BB, BasicBlock::iterator InsertPt) const {
48 IRBuilderDefaultInserter<true>::InsertHelper(I, Name, BB, InsertPt);
53 /// InstCombiner - The -instcombine pass.
54 class VISIBILITY_HIDDEN InstCombiner
55 : public FunctionPass,
56 public InstVisitor<InstCombiner, Instruction*> {
58 bool MustPreserveLCSSA;
61 /// Worklist - All of the instructions that need to be simplified.
62 InstCombineWorklist Worklist;
64 /// Builder - This is an IRBuilder that automatically inserts new
65 /// instructions into the worklist when they are created.
66 typedef IRBuilder<true, TargetFolder, InstCombineIRInserter> BuilderTy;
69 static char ID; // Pass identification, replacement for typeid
70 InstCombiner() : FunctionPass(&ID), TD(0), Builder(0) {}
73 virtual bool runOnFunction(Function &F);
75 bool DoOneIteration(Function &F, unsigned ItNum);
77 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
78 AU.addPreservedID(LCSSAID);
82 TargetData *getTargetData() const { return TD; }
84 // Visitation implementation - Implement instruction combining for different
85 // instruction types. The semantics are as follows:
87 // null - No change was made
88 // I - Change was made, I is still valid, I may be dead though
89 // otherwise - Change was made, replace I with returned instruction
91 Instruction *visitAdd(BinaryOperator &I);
92 Instruction *visitFAdd(BinaryOperator &I);
93 Value *OptimizePointerDifference(Value *LHS, Value *RHS, const Type *Ty);
94 Instruction *visitSub(BinaryOperator &I);
95 Instruction *visitFSub(BinaryOperator &I);
96 Instruction *visitMul(BinaryOperator &I);
97 Instruction *visitFMul(BinaryOperator &I);
98 Instruction *visitURem(BinaryOperator &I);
99 Instruction *visitSRem(BinaryOperator &I);
100 Instruction *visitFRem(BinaryOperator &I);
101 bool SimplifyDivRemOfSelect(BinaryOperator &I);
102 Instruction *commonRemTransforms(BinaryOperator &I);
103 Instruction *commonIRemTransforms(BinaryOperator &I);
104 Instruction *commonDivTransforms(BinaryOperator &I);
105 Instruction *commonIDivTransforms(BinaryOperator &I);
106 Instruction *visitUDiv(BinaryOperator &I);
107 Instruction *visitSDiv(BinaryOperator &I);
108 Instruction *visitFDiv(BinaryOperator &I);
109 Instruction *FoldAndOfICmps(Instruction &I, ICmpInst *LHS, ICmpInst *RHS);
110 Instruction *FoldAndOfFCmps(Instruction &I, FCmpInst *LHS, FCmpInst *RHS);
111 Instruction *visitAnd(BinaryOperator &I);
112 Instruction *FoldOrOfICmps(Instruction &I, ICmpInst *LHS, ICmpInst *RHS);
113 Instruction *FoldOrOfFCmps(Instruction &I, FCmpInst *LHS, FCmpInst *RHS);
114 Instruction *FoldOrWithConstants(BinaryOperator &I, Value *Op,
115 Value *A, Value *B, Value *C);
116 Instruction *visitOr (BinaryOperator &I);
117 Instruction *visitXor(BinaryOperator &I);
118 Instruction *visitShl(BinaryOperator &I);
119 Instruction *visitAShr(BinaryOperator &I);
120 Instruction *visitLShr(BinaryOperator &I);
121 Instruction *commonShiftTransforms(BinaryOperator &I);
122 Instruction *FoldFCmp_IntToFP_Cst(FCmpInst &I, Instruction *LHSI,
124 Instruction *FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP,
125 GlobalVariable *GV, CmpInst &ICI,
126 ConstantInt *AndCst = 0);
127 Instruction *visitFCmpInst(FCmpInst &I);
128 Instruction *visitICmpInst(ICmpInst &I);
129 Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI);
130 Instruction *visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
133 Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
134 ConstantInt *DivRHS);
135 Instruction *FoldICmpAddOpCst(ICmpInst &ICI, Value *X, ConstantInt *CI,
136 ICmpInst::Predicate Pred, Value *TheAdd);
137 Instruction *FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
138 ICmpInst::Predicate Cond, Instruction &I);
139 Instruction *FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
141 Instruction *commonCastTransforms(CastInst &CI);
142 Instruction *commonIntCastTransforms(CastInst &CI);
143 Instruction *commonPointerCastTransforms(CastInst &CI);
144 Instruction *visitTrunc(TruncInst &CI);
145 Instruction *visitZExt(ZExtInst &CI);
146 Instruction *visitSExt(SExtInst &CI);
147 Instruction *visitFPTrunc(FPTruncInst &CI);
148 Instruction *visitFPExt(CastInst &CI);
149 Instruction *visitFPToUI(FPToUIInst &FI);
150 Instruction *visitFPToSI(FPToSIInst &FI);
151 Instruction *visitUIToFP(CastInst &CI);
152 Instruction *visitSIToFP(CastInst &CI);
153 Instruction *visitPtrToInt(PtrToIntInst &CI);
154 Instruction *visitIntToPtr(IntToPtrInst &CI);
155 Instruction *visitBitCast(BitCastInst &CI);
156 Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
158 Instruction *FoldSelectIntoOp(SelectInst &SI, Value*, Value*);
159 Instruction *FoldSPFofSPF(Instruction *Inner, SelectPatternFlavor SPF1,
160 Value *A, Value *B, Instruction &Outer,
161 SelectPatternFlavor SPF2, Value *C);
162 Instruction *visitSelectInst(SelectInst &SI);
163 Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI);
164 Instruction *visitCallInst(CallInst &CI);
165 Instruction *visitInvokeInst(InvokeInst &II);
167 Instruction *SliceUpIllegalIntegerPHI(PHINode &PN);
168 Instruction *visitPHINode(PHINode &PN);
169 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
170 Instruction *visitAllocaInst(AllocaInst &AI);
171 Instruction *visitFree(Instruction &FI);
172 Instruction *visitLoadInst(LoadInst &LI);
173 Instruction *visitStoreInst(StoreInst &SI);
174 Instruction *visitBranchInst(BranchInst &BI);
175 Instruction *visitSwitchInst(SwitchInst &SI);
176 Instruction *visitInsertElementInst(InsertElementInst &IE);
177 Instruction *visitExtractElementInst(ExtractElementInst &EI);
178 Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
179 Instruction *visitExtractValueInst(ExtractValueInst &EV);
181 // visitInstruction - Specify what to return for unhandled instructions...
182 Instruction *visitInstruction(Instruction &I) { return 0; }
185 Instruction *visitCallSite(CallSite CS);
186 bool transformConstExprCastCall(CallSite CS);
187 Instruction *transformCallThroughTrampoline(CallSite CS);
188 Instruction *transformZExtICmp(ICmpInst *ICI, Instruction &CI,
189 bool DoXform = true);
190 bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS);
191 DbgDeclareInst *hasOneUsePlusDeclare(Value *V);
195 // InsertNewInstBefore - insert an instruction New before instruction Old
196 // in the program. Add the new instruction to the worklist.
198 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
199 assert(New && New->getParent() == 0 &&
200 "New instruction already inserted into a basic block!");
201 BasicBlock *BB = Old.getParent();
202 BB->getInstList().insert(&Old, New); // Insert inst
207 // ReplaceInstUsesWith - This method is to be used when an instruction is
208 // found to be dead, replacable with another preexisting expression. Here
209 // we add all uses of I to the worklist, replace all uses of I with the new
210 // value, then return I, so that the inst combiner will know that I was
213 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
214 Worklist.AddUsersToWorkList(I); // Add all modified instrs to worklist.
216 // If we are replacing the instruction with itself, this must be in a
217 // segment of unreachable code, so just clobber the instruction.
219 V = UndefValue::get(I.getType());
221 I.replaceAllUsesWith(V);
225 // EraseInstFromFunction - When dealing with an instruction that has side
226 // effects or produces a void value, we can't rely on DCE to delete the
227 // instruction. Instead, visit methods should return the value returned by
229 Instruction *EraseInstFromFunction(Instruction &I) {
230 DEBUG(errs() << "IC: ERASE " << I << '\n');
232 assert(I.use_empty() && "Cannot erase instruction that is used!");
233 // Make sure that we reprocess all operands now that we reduced their
235 if (I.getNumOperands() < 8) {
236 for (User::op_iterator i = I.op_begin(), e = I.op_end(); i != e; ++i)
237 if (Instruction *Op = dyn_cast<Instruction>(*i))
243 return 0; // Don't do anything with FI
246 void ComputeMaskedBits(Value *V, const APInt &Mask, APInt &KnownZero,
247 APInt &KnownOne, unsigned Depth = 0) const {
248 return llvm::ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD, Depth);
251 bool MaskedValueIsZero(Value *V, const APInt &Mask,
252 unsigned Depth = 0) const {
253 return llvm::MaskedValueIsZero(V, Mask, TD, Depth);
255 unsigned ComputeNumSignBits(Value *Op, unsigned Depth = 0) const {
256 return llvm::ComputeNumSignBits(Op, TD, Depth);
261 /// SimplifyCommutative - This performs a few simplifications for
262 /// commutative operators.
263 bool SimplifyCommutative(BinaryOperator &I);
265 /// SimplifyDemandedUseBits - Attempts to replace V with a simpler value
266 /// based on the demanded bits.
267 Value *SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
268 APInt& KnownZero, APInt& KnownOne,
270 bool SimplifyDemandedBits(Use &U, APInt DemandedMask,
271 APInt& KnownZero, APInt& KnownOne,
274 /// SimplifyDemandedInstructionBits - Inst is an integer instruction that
275 /// SimplifyDemandedBits knows about. See if the instruction has any
276 /// properties that allow us to simplify its operands.
277 bool SimplifyDemandedInstructionBits(Instruction &Inst);
279 Value *SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
280 APInt& UndefElts, unsigned Depth = 0);
282 // FoldOpIntoPhi - Given a binary operator, cast instruction, or select
283 // which has a PHI node as operand #0, see if we can fold the instruction
284 // into the PHI (which is only possible if all operands to the PHI are
287 // If AllowAggressive is true, FoldOpIntoPhi will allow certain transforms
288 // that would normally be unprofitable because they strongly encourage jump
290 Instruction *FoldOpIntoPhi(Instruction &I, bool AllowAggressive = false);
292 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
293 // operator and they all are only used by the PHI, PHI together their
294 // inputs, and do the operation once, to the result of the PHI.
295 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
296 Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN);
297 Instruction *FoldPHIArgGEPIntoPHI(PHINode &PN);
298 Instruction *FoldPHIArgLoadIntoPHI(PHINode &PN);
301 Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS,
302 ConstantInt *AndRHS, BinaryOperator &TheAnd);
304 Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask,
305 bool isSub, Instruction &I);
306 Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
307 bool isSigned, bool Inside, Instruction &IB);
308 Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocaInst &AI);
309 Instruction *MatchBSwap(BinaryOperator &I);
310 bool SimplifyStoreAtEndOfBlock(StoreInst &SI);
311 Instruction *SimplifyMemTransfer(MemIntrinsic *MI);
312 Instruction *SimplifyMemSet(MemSetInst *MI);
315 Value *EvaluateInDifferentType(Value *V, const Type *Ty, bool isSigned);
317 bool CanEvaluateInDifferentType(Value *V, const Type *Ty,
318 unsigned CastOpc, int &NumCastsRemoved);
319 unsigned GetOrEnforceKnownAlignment(Value *V,
320 unsigned PrefAlign = 0);
326 } // end namespace llvm.