1 //===---- llvm/Analysis/ScalarEvolutionExpander.h - SCEV Exprs --*- C++ -*-===//
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 // This file defines the classes used to generate code from scalar expressions.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_ANALYSIS_SCALAREVOLUTION_EXPANDER_H
15 #define LLVM_ANALYSIS_SCALAREVOLUTION_EXPANDER_H
17 #include "llvm/Analysis/ScalarEvolutionExpressions.h"
18 #include "llvm/Support/IRBuilder.h"
19 #include "llvm/Support/TargetFolder.h"
23 /// SCEVExpander - This class uses information about analyze scalars to
24 /// rewrite expressions in canonical form.
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
29 class SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> {
34 std::map<std::pair<const SCEV *, Instruction *>, AssertingVH<Value> >
36 std::set<Value*> InsertedValues;
38 /// PostIncLoop - When non-null, expanded addrecs referring to the given
39 /// loop expanded in post-inc mode. For example, expanding {1,+,1}<L> in
40 /// post-inc mode returns the add instruction that adds one to the phi
41 /// for {0,+,1}<L>, as opposed to a new phi starting at 1. This is only
42 /// supported in non-canonical mode.
43 const Loop *PostIncLoop;
45 /// IVIncInsertPos - When this is non-null, addrecs expanded in the
46 /// loop it indicates should be inserted with increments at
48 const Loop *IVIncInsertLoop;
50 /// IVIncInsertPos - When expanding addrecs in the IVIncInsertLoop loop,
51 /// insert the IV increment at this position.
52 Instruction *IVIncInsertPos;
54 /// CanonicalMode - When true, expressions are expanded in "canonical"
55 /// form. In particular, addrecs are expanded as arithmetic based on
56 /// a canonical induction variable. When false, expression are expanded
57 /// in a more literal form.
61 typedef IRBuilder<true, TargetFolder> BuilderType;
64 friend struct SCEVVisitor<SCEVExpander, Value*>;
66 /// SCEVExpander - Construct a SCEVExpander in "canonical" mode.
67 explicit SCEVExpander(ScalarEvolution &se)
68 : SE(se), PostIncLoop(0), IVIncInsertLoop(0), CanonicalMode(true),
69 Builder(se.getContext(), TargetFolder(se.TD)) {}
71 /// clear - Erase the contents of the InsertedExpressions map so that users
72 /// trying to expand the same expression into multiple BasicBlocks or
73 /// different places within the same BasicBlock can do so.
74 void clear() { InsertedExpressions.clear(); }
76 /// getOrInsertCanonicalInductionVariable - This method returns the
77 /// canonical induction variable of the specified type for the specified
78 /// loop (inserting one if there is none). A canonical induction variable
79 /// starts at zero and steps by one on each iteration.
80 Value *getOrInsertCanonicalInductionVariable(const Loop *L, const Type *Ty);
82 /// expandCodeFor - Insert code to directly compute the specified SCEV
83 /// expression into the program. The inserted code is inserted into the
85 Value *expandCodeFor(const SCEV *SH, const Type *Ty, Instruction *I) {
86 BasicBlock::iterator IP = I;
87 while (isInsertedInstruction(IP)) ++IP;
88 Builder.SetInsertPoint(IP->getParent(), IP);
89 return expandCodeFor(SH, Ty);
92 /// setIVIncInsertPos - Set the current IV increment loop and position.
93 void setIVIncInsertPos(const Loop *L, Instruction *Pos) {
94 assert(!CanonicalMode &&
95 "IV increment positions are not supported in CanonicalMode");
100 /// setPostInc - If L is non-null, enable post-inc expansion for addrecs
101 /// referring to the given loop. If L is null, disable post-inc expansion
102 /// completely. Post-inc expansion is only supported in non-canonical
104 void setPostInc(const Loop *L) {
105 assert(!CanonicalMode &&
106 "Post-inc expansion is not supported in CanonicalMode");
110 /// disableCanonicalMode - Disable the behavior of expanding expressions in
111 /// canonical form rather than in a more literal form. Non-canonical mode
112 /// is useful for late optimization passes.
113 void disableCanonicalMode() { CanonicalMode = false; }
116 LLVMContext &getContext() const { return SE.getContext(); }
118 /// InsertBinop - Insert the specified binary operator, doing a small amount
119 /// of work to avoid inserting an obviously redundant operation.
120 Value *InsertBinop(Instruction::BinaryOps Opcode, Value *LHS, Value *RHS);
122 /// InsertNoopCastOfTo - Insert a cast of V to the specified type,
123 /// which must be possible with a noop cast, doing what we can to
125 Value *InsertNoopCastOfTo(Value *V, const Type *Ty);
127 /// expandAddToGEP - Expand a SCEVAddExpr with a pointer type into a GEP
128 /// instead of using ptrtoint+arithmetic+inttoptr.
129 Value *expandAddToGEP(const SCEV *const *op_begin,
130 const SCEV *const *op_end,
131 const PointerType *PTy, const Type *Ty, Value *V);
133 Value *expand(const SCEV *S);
135 /// expandCodeFor - Insert code to directly compute the specified SCEV
136 /// expression into the program. The inserted code is inserted into the
137 /// SCEVExpander's current insertion point. If a type is specified, the
138 /// result will be expanded to have that type, with a cast if necessary.
139 Value *expandCodeFor(const SCEV *SH, const Type *Ty = 0);
141 /// isInsertedInstruction - Return true if the specified instruction was
142 /// inserted by the code rewriter. If so, the client should not modify the
144 bool isInsertedInstruction(Instruction *I) const {
145 return InsertedValues.count(I);
148 Value *visitConstant(const SCEVConstant *S) {
149 return S->getValue();
152 Value *visitTruncateExpr(const SCEVTruncateExpr *S);
154 Value *visitZeroExtendExpr(const SCEVZeroExtendExpr *S);
156 Value *visitSignExtendExpr(const SCEVSignExtendExpr *S);
158 Value *visitAddExpr(const SCEVAddExpr *S);
160 Value *visitMulExpr(const SCEVMulExpr *S);
162 Value *visitUDivExpr(const SCEVUDivExpr *S);
164 Value *visitAddRecExpr(const SCEVAddRecExpr *S);
166 Value *visitSMaxExpr(const SCEVSMaxExpr *S);
168 Value *visitUMaxExpr(const SCEVUMaxExpr *S);
170 Value *visitFieldOffsetExpr(const SCEVFieldOffsetExpr *S);
172 Value *visitAllocSizeExpr(const SCEVAllocSizeExpr *S);
174 Value *visitUnknown(const SCEVUnknown *S) {
175 return S->getValue();
178 void rememberInstruction(Value *I) {
179 if (!PostIncLoop) InsertedValues.insert(I);
182 Value *expandAddRecExprLiterally(const SCEVAddRecExpr *);
183 PHINode *getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
185 const Type *ExpandTy,