ScalarEvolutionExpander.h revision 0bba49cebc50c7bd4662a4807bcb3ee7f42cb470
1//===---- llvm/Analysis/ScalarEvolutionExpander.h - SCEV Exprs --*- C++ -*-===// 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// This file defines the classes used to generate code from scalar expressions. 11// 12//===----------------------------------------------------------------------===// 13 14#ifndef LLVM_ANALYSIS_SCALAREVOLUTION_EXPANDER_H 15#define LLVM_ANALYSIS_SCALAREVOLUTION_EXPANDER_H 16 17#include "llvm/Analysis/ScalarEvolutionExpressions.h" 18#include "llvm/Support/IRBuilder.h" 19#include "llvm/Support/TargetFolder.h" 20 21namespace llvm { 22 /// SCEVExpander - This class uses information about analyze scalars to 23 /// rewrite expressions in canonical form. 24 /// 25 /// Clients should create an instance of this class when rewriting is needed, 26 /// and destroy it when finished to allow the release of the associated 27 /// memory. 28 struct SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> { 29 ScalarEvolution &SE; 30 std::map<std::pair<const SCEV *, Instruction *>, AssertingVH<Value> > 31 InsertedExpressions; 32 std::set<Value*> InsertedValues; 33 34 typedef IRBuilder<true, TargetFolder> BuilderType; 35 BuilderType Builder; 36 37 friend struct SCEVVisitor<SCEVExpander, Value*>; 38 public: 39 explicit SCEVExpander(ScalarEvolution &se) 40 : SE(se), Builder(TargetFolder(se.TD, se.getContext())) {} 41 42 /// clear - Erase the contents of the InsertedExpressions map so that users 43 /// trying to expand the same expression into multiple BasicBlocks or 44 /// different places within the same BasicBlock can do so. 45 void clear() { InsertedExpressions.clear(); } 46 47 /// getOrInsertCanonicalInductionVariable - This method returns the 48 /// canonical induction variable of the specified type for the specified 49 /// loop (inserting one if there is none). A canonical induction variable 50 /// starts at zero and steps by one on each iteration. 51 Value *getOrInsertCanonicalInductionVariable(const Loop *L, const Type *Ty); 52 53 /// expandCodeFor - Insert code to directly compute the specified SCEV 54 /// expression into the program. The inserted code is inserted into the 55 /// specified block. 56 Value *expandCodeFor(const SCEV *SH, const Type *Ty, Instruction *IP) { 57 Builder.SetInsertPoint(IP->getParent(), IP); 58 return expandCodeFor(SH, Ty); 59 } 60 61 private: 62 LLVMContext *getContext() const { return SE.getContext(); } 63 64 /// InsertBinop - Insert the specified binary operator, doing a small amount 65 /// of work to avoid inserting an obviously redundant operation. 66 Value *InsertBinop(Instruction::BinaryOps Opcode, Value *LHS, Value *RHS); 67 68 /// InsertNoopCastOfTo - Insert a cast of V to the specified type, 69 /// which must be possible with a noop cast, doing what we can to 70 /// share the casts. 71 Value *InsertNoopCastOfTo(Value *V, const Type *Ty); 72 73 /// expandAddToGEP - Expand a SCEVAddExpr with a pointer type into a GEP 74 /// instead of using ptrtoint+arithmetic+inttoptr. 75 Value *expandAddToGEP(const SCEV *const *op_begin, 76 const SCEV *const *op_end, 77 const PointerType *PTy, const Type *Ty, Value *V); 78 79 Value *expand(const SCEV *S); 80 81 /// expandCodeFor - Insert code to directly compute the specified SCEV 82 /// expression into the program. The inserted code is inserted into the 83 /// SCEVExpander's current insertion point. If a type is specified, the 84 /// result will be expanded to have that type, with a cast if necessary. 85 Value *expandCodeFor(const SCEV *SH, const Type *Ty = 0); 86 87 /// isInsertedInstruction - Return true if the specified instruction was 88 /// inserted by the code rewriter. If so, the client should not modify the 89 /// instruction. 90 bool isInsertedInstruction(Instruction *I) const { 91 return InsertedValues.count(I); 92 } 93 94 Value *visitConstant(const SCEVConstant *S) { 95 return S->getValue(); 96 } 97 98 Value *visitTruncateExpr(const SCEVTruncateExpr *S); 99 100 Value *visitZeroExtendExpr(const SCEVZeroExtendExpr *S); 101 102 Value *visitSignExtendExpr(const SCEVSignExtendExpr *S); 103 104 Value *visitAddExpr(const SCEVAddExpr *S); 105 106 Value *visitMulExpr(const SCEVMulExpr *S); 107 108 Value *visitUDivExpr(const SCEVUDivExpr *S); 109 110 Value *visitAddRecExpr(const SCEVAddRecExpr *S); 111 112 Value *visitSMaxExpr(const SCEVSMaxExpr *S); 113 114 Value *visitUMaxExpr(const SCEVUMaxExpr *S); 115 116 Value *visitUnknown(const SCEVUnknown *S) { 117 return S->getValue(); 118 } 119 }; 120} 121 122#endif 123 124