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"
21 #include "llvm/Support/ValueHandle.h"
25 /// SCEVExpander - This class uses information about analyze scalars to
26 /// rewrite expressions in canonical form.
28 /// Clients should create an instance of this class when rewriting is needed,
29 /// and destroy it when finished to allow the release of the associated
31 class SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> {
33 std::map<std::pair<const SCEV *, Instruction *>, AssertingVH<Value> >
35 std::set<AssertingVH<Value> > InsertedValues;
36 std::set<AssertingVH<Value> > InsertedPostIncValues;
38 /// RelevantLoops - A memoization of the "relevant" loop for a given SCEV.
39 DenseMap<const SCEV *, const Loop *> RelevantLoops;
41 /// PostIncLoops - Addrecs referring to any of the given loops are expanded
42 /// in post-inc mode. For example, expanding {1,+,1}<L> in post-inc mode
43 /// returns the add instruction that adds one to the phi for {0,+,1}<L>,
44 /// as opposed to a new phi starting at 1. This is only supported in
45 /// non-canonical mode.
46 PostIncLoopSet PostIncLoops;
48 /// IVIncInsertPos - When this is non-null, addrecs expanded in the
49 /// loop it indicates should be inserted with increments at
51 const Loop *IVIncInsertLoop;
53 /// IVIncInsertPos - When expanding addrecs in the IVIncInsertLoop loop,
54 /// insert the IV increment at this position.
55 Instruction *IVIncInsertPos;
57 /// CanonicalMode - When true, expressions are expanded in "canonical"
58 /// form. In particular, addrecs are expanded as arithmetic based on
59 /// a canonical induction variable. When false, expression are expanded
60 /// in a more literal form.
63 typedef IRBuilder<true, TargetFolder> BuilderType;
66 friend struct SCEVVisitor<SCEVExpander, Value*>;
69 /// SCEVExpander - Construct a SCEVExpander in "canonical" mode.
70 explicit SCEVExpander(ScalarEvolution &se)
71 : SE(se), IVIncInsertLoop(0), CanonicalMode(true),
72 Builder(se.getContext(), TargetFolder(se.TD)) {}
74 /// clear - Erase the contents of the InsertedExpressions map so that users
75 /// trying to expand the same expression into multiple BasicBlocks or
76 /// different places within the same BasicBlock can do so.
78 InsertedExpressions.clear();
79 InsertedValues.clear();
80 InsertedPostIncValues.clear();
83 /// getOrInsertCanonicalInductionVariable - This method returns the
84 /// canonical induction variable of the specified type for the specified
85 /// loop (inserting one if there is none). A canonical induction variable
86 /// starts at zero and steps by one on each iteration.
87 PHINode *getOrInsertCanonicalInductionVariable(const Loop *L,
90 /// expandCodeFor - Insert code to directly compute the specified SCEV
91 /// expression into the program. The inserted code is inserted into the
93 Value *expandCodeFor(const SCEV *SH, const Type *Ty, Instruction *I);
95 /// setIVIncInsertPos - Set the current IV increment loop and position.
96 void setIVIncInsertPos(const Loop *L, Instruction *Pos) {
97 assert(!CanonicalMode &&
98 "IV increment positions are not supported in CanonicalMode");
100 IVIncInsertPos = Pos;
103 /// setPostInc - Enable post-inc expansion for addrecs referring to the
104 /// given loops. Post-inc expansion is only supported in non-canonical
106 void setPostInc(const PostIncLoopSet &L) {
107 assert(!CanonicalMode &&
108 "Post-inc expansion is not supported in CanonicalMode");
112 /// clearPostInc - Disable all post-inc expansion.
113 void clearPostInc() {
114 PostIncLoops.clear();
116 // When we change the post-inc loop set, cached expansions may no
118 InsertedPostIncValues.clear();
121 /// disableCanonicalMode - Disable the behavior of expanding expressions in
122 /// canonical form rather than in a more literal form. Non-canonical mode
123 /// is useful for late optimization passes.
124 void disableCanonicalMode() { CanonicalMode = false; }
126 /// clearInsertPoint - Clear the current insertion point. This is useful
127 /// if the instruction that had been serving as the insertion point may
128 /// have been deleted.
129 void clearInsertPoint() {
130 Builder.ClearInsertionPoint();
134 LLVMContext &getContext() const { return SE.getContext(); }
136 /// InsertBinop - Insert the specified binary operator, doing a small amount
137 /// of work to avoid inserting an obviously redundant operation.
138 Value *InsertBinop(Instruction::BinaryOps Opcode, Value *LHS, Value *RHS);
140 /// ReuseOrCreateCast - Arange for there to be a cast of V to Ty at IP,
141 /// reusing an existing cast if a suitable one exists, moving an existing
142 /// cast if a suitable one exists but isn't in the right place, or
143 /// or creating a new one.
144 Value *ReuseOrCreateCast(Value *V, const Type *Ty,
145 Instruction::CastOps Op,
146 BasicBlock::iterator IP);
148 /// InsertNoopCastOfTo - Insert a cast of V to the specified type,
149 /// which must be possible with a noop cast, doing what we can to
151 Value *InsertNoopCastOfTo(Value *V, const Type *Ty);
153 /// expandAddToGEP - Expand a SCEVAddExpr with a pointer type into a GEP
154 /// instead of using ptrtoint+arithmetic+inttoptr.
155 Value *expandAddToGEP(const SCEV *const *op_begin,
156 const SCEV *const *op_end,
157 const PointerType *PTy, const Type *Ty, Value *V);
159 Value *expand(const SCEV *S);
161 /// expandCodeFor - Insert code to directly compute the specified SCEV
162 /// expression into the program. The inserted code is inserted into the
163 /// SCEVExpander's current insertion point. If a type is specified, the
164 /// result will be expanded to have that type, with a cast if necessary.
165 Value *expandCodeFor(const SCEV *SH, const Type *Ty = 0);
167 /// isInsertedInstruction - Return true if the specified instruction was
168 /// inserted by the code rewriter. If so, the client should not modify the
170 bool isInsertedInstruction(Instruction *I) const {
171 return InsertedValues.count(I) || InsertedPostIncValues.count(I);
174 /// getRelevantLoop - Determine the most "relevant" loop for the given SCEV.
175 const Loop *getRelevantLoop(const SCEV *);
177 Value *visitConstant(const SCEVConstant *S) {
178 return S->getValue();
181 Value *visitTruncateExpr(const SCEVTruncateExpr *S);
183 Value *visitZeroExtendExpr(const SCEVZeroExtendExpr *S);
185 Value *visitSignExtendExpr(const SCEVSignExtendExpr *S);
187 Value *visitAddExpr(const SCEVAddExpr *S);
189 Value *visitMulExpr(const SCEVMulExpr *S);
191 Value *visitUDivExpr(const SCEVUDivExpr *S);
193 Value *visitAddRecExpr(const SCEVAddRecExpr *S);
195 Value *visitSMaxExpr(const SCEVSMaxExpr *S);
197 Value *visitUMaxExpr(const SCEVUMaxExpr *S);
199 Value *visitUnknown(const SCEVUnknown *S) {
200 return S->getValue();
203 void rememberInstruction(Value *I);
205 void restoreInsertPoint(BasicBlock *BB, BasicBlock::iterator I);
207 Value *expandAddRecExprLiterally(const SCEVAddRecExpr *);
208 PHINode *getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
210 const Type *ExpandTy,