ScalarEvolutionExpander.h revision cf5ab820227dedd77fb91d0904b6dc3694a7c196
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/Instructions.h" 18#include "llvm/Type.h" 19#include "llvm/Analysis/ScalarEvolution.h" 20#include "llvm/Analysis/ScalarEvolutionExpressions.h" 21 22namespace llvm { 23 /// SCEVExpander - This class uses information about analyze scalars to 24 /// rewrite expressions in canonical form. 25 /// 26 /// Clients should create an instance of this class when rewriting is needed, 27 /// and destroy it when finished to allow the release of the associated 28 /// memory. 29 struct SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> { 30 ScalarEvolution &SE; 31 LoopInfo &LI; 32 std::map<SCEVHandle, Value*> InsertedExpressions; 33 std::set<Value*> InsertedValues; 34 35 BasicBlock::iterator InsertPt; 36 37 friend struct SCEVVisitor<SCEVExpander, Value*>; 38 public: 39 SCEVExpander(ScalarEvolution &se, LoopInfo &li) 40 : SE(se), LI(li) {} 41 42 LoopInfo &getLoopInfo() const { return LI; } 43 44 /// clear - Erase the contents of the InsertedExpressions map so that users 45 /// trying to expand the same expression into multiple BasicBlocks or 46 /// different places within the same BasicBlock can do so. 47 void clear() { InsertedExpressions.clear(); } 48 49 /// isInsertedInstruction - Return true if the specified instruction was 50 /// inserted by the code rewriter. If so, the client should not modify the 51 /// instruction. 52 bool isInsertedInstruction(Instruction *I) const { 53 return InsertedValues.count(I); 54 } 55 56 /// isInsertedExpression - Return true if the the code rewriter has a 57 /// Value* recorded for the given expression. 58 bool isInsertedExpression(const SCEV *S) const { 59 return InsertedExpressions.count(S); 60 } 61 62 /// getOrInsertCanonicalInductionVariable - This method returns the 63 /// canonical induction variable of the specified type for the specified 64 /// loop (inserting one if there is none). A canonical induction variable 65 /// starts at zero and steps by one on each iteration. 66 Value *getOrInsertCanonicalInductionVariable(const Loop *L, const Type *Ty){ 67 assert(Ty->isInteger() && "Can only insert integer induction variables!"); 68 SCEVHandle H = SE.getAddRecExpr(SE.getIntegerSCEV(0, Ty), 69 SE.getIntegerSCEV(1, Ty), L); 70 return expand(H); 71 } 72 73 /// addInsertedValue - Remember the specified instruction as being the 74 /// canonical form for the specified SCEV. 75 void addInsertedValue(Value *V, const SCEV *S) { 76 InsertedExpressions[S] = V; 77 InsertedValues.insert(V); 78 } 79 80 void setInsertionPoint(BasicBlock::iterator NewIP) { InsertPt = NewIP; } 81 82 BasicBlock::iterator getInsertionPoint() const { return InsertPt; } 83 84 /// expandCodeFor - Insert code to directly compute the specified SCEV 85 /// expression into the program. The inserted code is inserted into the 86 /// SCEVExpander's current insertion point. 87 Value *expandCodeFor(SCEVHandle SH, const Type *Ty); 88 89 /// expandCodeFor - Insert code to directly compute the specified SCEV 90 /// expression into the program. The inserted code is inserted into the 91 /// specified block. 92 Value *expandCodeFor(SCEVHandle SH, const Type *Ty, 93 BasicBlock::iterator IP) { 94 setInsertionPoint(IP); 95 return expandCodeFor(SH, Ty); 96 } 97 98 /// InsertCastOfTo - Insert a cast of V to the specified type, doing what 99 /// we can to share the casts. 100 Value *InsertCastOfTo(Instruction::CastOps opcode, Value *V, 101 const Type *Ty); 102 103 /// InsertNoopCastOfTo - Insert a cast of V to the specified type, 104 /// which must be possible with a noop cast. 105 Value *InsertNoopCastOfTo(Value *V, const Type *Ty); 106 107 /// InsertBinop - Insert the specified binary operator, doing a small amount 108 /// of work to avoid inserting an obviously redundant operation. 109 Value *InsertBinop(Instruction::BinaryOps Opcode, Value *LHS, 110 Value *RHS, BasicBlock::iterator InsertPt); 111 112 private: 113 Value *expand(const SCEV *S); 114 115 Value *visitConstant(const SCEVConstant *S) { 116 return S->getValue(); 117 } 118 119 Value *visitTruncateExpr(const SCEVTruncateExpr *S); 120 121 Value *visitZeroExtendExpr(const SCEVZeroExtendExpr *S); 122 123 Value *visitSignExtendExpr(const SCEVSignExtendExpr *S); 124 125 Value *visitAddExpr(const SCEVAddExpr *S); 126 127 Value *visitMulExpr(const SCEVMulExpr *S); 128 129 Value *visitUDivExpr(const SCEVUDivExpr *S); 130 131 Value *visitAddRecExpr(const SCEVAddRecExpr *S); 132 133 Value *visitSMaxExpr(const SCEVSMaxExpr *S); 134 135 Value *visitUMaxExpr(const SCEVUMaxExpr *S); 136 137 Value *visitUnknown(const SCEVUnknown *S) { 138 return S->getValue(); 139 } 140 }; 141} 142 143#endif 144 145