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/Analysis/ScalarEvolutionNormalization.h"
19 #include "llvm/Support/IRBuilder.h"
20 #include "llvm/Support/TargetFolder.h"
24 /// SCEVExpander - This class uses information about analyze scalars to
25 /// rewrite expressions in canonical form.
27 /// Clients should create an instance of this class when rewriting is needed,
28 /// and destroy it when finished to allow the release of the associated
30 class SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> {
32 std::map<std::pair<const SCEV *, Instruction *>, AssertingVH<Value> >
34 std::set<Value*> InsertedValues;
35 std::set<Value*> InsertedPostIncValues;
37 /// PostIncLoops - Addrecs referring to any of the given loops are expanded
38 /// in post-inc mode. For example, expanding {1,+,1}<L> in post-inc mode
39 /// returns the add instruction that adds one to the phi for {0,+,1}<L>,
40 /// as opposed to a new phi starting at 1. This is only supported in
41 /// non-canonical mode.
42 PostIncLoopSet PostIncLoops;
44 /// IVIncInsertPos - When this is non-null, addrecs expanded in the
45 /// loop it indicates should be inserted with increments at
47 const Loop *IVIncInsertLoop;
49 /// IVIncInsertPos - When expanding addrecs in the IVIncInsertLoop loop,
50 /// insert the IV increment at this position.
51 Instruction *IVIncInsertPos;
53 /// CanonicalMode - When true, expressions are expanded in "canonical"
54 /// form. In particular, addrecs are expanded as arithmetic based on
55 /// a canonical induction variable. When false, expression are expanded
56 /// in a more literal form.
59 typedef IRBuilder<true, TargetFolder> BuilderType;
62 friend struct SCEVVisitor<SCEVExpander, Value*>;
65 /// SCEVExpander - Construct a SCEVExpander in "canonical" mode.
66 explicit SCEVExpander(ScalarEvolution &se)
67 : SE(se), IVIncInsertLoop(0), CanonicalMode(true),
68 Builder(se.getContext(), TargetFolder(se.TD)) {}
70 /// clear - Erase the contents of the InsertedExpressions map so that users
71 /// trying to expand the same expression into multiple BasicBlocks or
72 /// different places within the same BasicBlock can do so.
73 void clear() { InsertedExpressions.clear(); }
75 /// getOrInsertCanonicalInductionVariable - This method returns the
76 /// canonical induction variable of the specified type for the specified
77 /// loop (inserting one if there is none). A canonical induction variable
78 /// starts at zero and steps by one on each iteration.
79 Value *getOrInsertCanonicalInductionVariable(const Loop *L, const Type *Ty);
81 /// expandCodeFor - Insert code to directly compute the specified SCEV
82 /// expression into the program. The inserted code is inserted into the
84 Value *expandCodeFor(const SCEV *SH, const Type *Ty, Instruction *I);
86 /// setIVIncInsertPos - Set the current IV increment loop and position.
87 void setIVIncInsertPos(const Loop *L, Instruction *Pos) {
88 assert(!CanonicalMode &&
89 "IV increment positions are not supported in CanonicalMode");
94 /// setPostInc - Enable post-inc expansion for addrecs referring to the
95 /// given loops. Post-inc expansion is only supported in non-canonical
97 void setPostInc(const PostIncLoopSet &L) {
98 assert(!CanonicalMode &&
99 "Post-inc expansion is not supported in CanonicalMode");
103 /// clearPostInc - Disable all post-inc expansion.
104 void clearPostInc() {
105 PostIncLoops.clear();
107 // When we change the post-inc loop set, cached expansions may no
109 InsertedPostIncValues.clear();
112 /// disableCanonicalMode - Disable the behavior of expanding expressions in
113 /// canonical form rather than in a more literal form. Non-canonical mode
114 /// is useful for late optimization passes.
115 void disableCanonicalMode() { CanonicalMode = false; }
117 /// clearInsertPoint - Clear the current insertion point. This is useful
118 /// if the instruction that had been serving as the insertion point may
119 /// have been deleted.
120 void clearInsertPoint() {
121 Builder.ClearInsertionPoint();
125 LLVMContext &getContext() const { return SE.getContext(); }
127 /// InsertBinop - Insert the specified binary operator, doing a small amount
128 /// of work to avoid inserting an obviously redundant operation.
129 Value *InsertBinop(Instruction::BinaryOps Opcode, Value *LHS, Value *RHS);
131 /// ReuseOrCreateCast - Arange for there to be a cast of V to Ty at IP,
132 /// reusing an existing cast if a suitable one exists, moving an existing
133 /// cast if a suitable one exists but isn't in the right place, or
134 /// or creating a new one.
135 Value *ReuseOrCreateCast(Value *V, const Type *Ty,
136 Instruction::CastOps Op,
137 BasicBlock::iterator IP);
139 /// InsertNoopCastOfTo - Insert a cast of V to the specified type,
140 /// which must be possible with a noop cast, doing what we can to
142 Value *InsertNoopCastOfTo(Value *V, const Type *Ty);
144 /// expandAddToGEP - Expand a SCEVAddExpr with a pointer type into a GEP
145 /// instead of using ptrtoint+arithmetic+inttoptr.
146 Value *expandAddToGEP(const SCEV *const *op_begin,
147 const SCEV *const *op_end,
148 const PointerType *PTy, const Type *Ty, Value *V);
150 Value *expand(const SCEV *S);
152 /// expandCodeFor - Insert code to directly compute the specified SCEV
153 /// expression into the program. The inserted code is inserted into the
154 /// SCEVExpander's current insertion point. If a type is specified, the
155 /// result will be expanded to have that type, with a cast if necessary.
156 Value *expandCodeFor(const SCEV *SH, const Type *Ty = 0);
158 /// isInsertedInstruction - Return true if the specified instruction was
159 /// inserted by the code rewriter. If so, the client should not modify the
161 bool isInsertedInstruction(Instruction *I) const {
162 return InsertedValues.count(I) || InsertedPostIncValues.count(I);
165 Value *visitConstant(const SCEVConstant *S) {
166 return S->getValue();
169 Value *visitTruncateExpr(const SCEVTruncateExpr *S);
171 Value *visitZeroExtendExpr(const SCEVZeroExtendExpr *S);
173 Value *visitSignExtendExpr(const SCEVSignExtendExpr *S);
175 Value *visitAddExpr(const SCEVAddExpr *S);
177 Value *visitMulExpr(const SCEVMulExpr *S);
179 Value *visitUDivExpr(const SCEVUDivExpr *S);
181 Value *visitAddRecExpr(const SCEVAddRecExpr *S);
183 Value *visitSMaxExpr(const SCEVSMaxExpr *S);
185 Value *visitUMaxExpr(const SCEVUMaxExpr *S);
187 Value *visitUnknown(const SCEVUnknown *S) {
188 return S->getValue();
191 void rememberInstruction(Value *I);
193 void restoreInsertPoint(BasicBlock *BB, BasicBlock::iterator I);
195 Value *expandAddRecExprLiterally(const SCEVAddRecExpr *);
196 PHINode *getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
198 const Type *ExpandTy,