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 /// PostIncLoops - Addrecs referring to any of the given loops are expanded
39 /// in post-inc mode. For example, expanding {1,+,1}<L> in post-inc mode
40 /// returns the add instruction that adds one to the phi for {0,+,1}<L>,
41 /// as opposed to a new phi starting at 1. This is only supported in
42 /// non-canonical mode.
43 PostIncLoopSet PostIncLoops;
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.
60 typedef IRBuilder<true, TargetFolder> BuilderType;
63 friend struct SCEVVisitor<SCEVExpander, Value*>;
66 /// SCEVExpander - Construct a SCEVExpander in "canonical" mode.
67 explicit SCEVExpander(ScalarEvolution &se)
68 : SE(se), 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.
75 InsertedExpressions.clear();
76 InsertedValues.clear();
77 InsertedPostIncValues.clear();
80 /// getOrInsertCanonicalInductionVariable - This method returns the
81 /// canonical induction variable of the specified type for the specified
82 /// loop (inserting one if there is none). A canonical induction variable
83 /// starts at zero and steps by one on each iteration.
84 PHINode *getOrInsertCanonicalInductionVariable(const Loop *L,
87 /// expandCodeFor - Insert code to directly compute the specified SCEV
88 /// expression into the program. The inserted code is inserted into the
90 Value *expandCodeFor(const SCEV *SH, const Type *Ty, Instruction *I);
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 - Enable post-inc expansion for addrecs referring to the
101 /// given loops. Post-inc expansion is only supported in non-canonical
103 void setPostInc(const PostIncLoopSet &L) {
104 assert(!CanonicalMode &&
105 "Post-inc expansion is not supported in CanonicalMode");
109 /// clearPostInc - Disable all post-inc expansion.
110 void clearPostInc() {
111 PostIncLoops.clear();
113 // When we change the post-inc loop set, cached expansions may no
115 InsertedPostIncValues.clear();
118 /// disableCanonicalMode - Disable the behavior of expanding expressions in
119 /// canonical form rather than in a more literal form. Non-canonical mode
120 /// is useful for late optimization passes.
121 void disableCanonicalMode() { CanonicalMode = false; }
123 /// clearInsertPoint - Clear the current insertion point. This is useful
124 /// if the instruction that had been serving as the insertion point may
125 /// have been deleted.
126 void clearInsertPoint() {
127 Builder.ClearInsertionPoint();
131 LLVMContext &getContext() const { return SE.getContext(); }
133 /// InsertBinop - Insert the specified binary operator, doing a small amount
134 /// of work to avoid inserting an obviously redundant operation.
135 Value *InsertBinop(Instruction::BinaryOps Opcode, Value *LHS, Value *RHS);
137 /// ReuseOrCreateCast - Arange for there to be a cast of V to Ty at IP,
138 /// reusing an existing cast if a suitable one exists, moving an existing
139 /// cast if a suitable one exists but isn't in the right place, or
140 /// or creating a new one.
141 Value *ReuseOrCreateCast(Value *V, const Type *Ty,
142 Instruction::CastOps Op,
143 BasicBlock::iterator IP);
145 /// InsertNoopCastOfTo - Insert a cast of V to the specified type,
146 /// which must be possible with a noop cast, doing what we can to
148 Value *InsertNoopCastOfTo(Value *V, const Type *Ty);
150 /// expandAddToGEP - Expand a SCEVAddExpr with a pointer type into a GEP
151 /// instead of using ptrtoint+arithmetic+inttoptr.
152 Value *expandAddToGEP(const SCEV *const *op_begin,
153 const SCEV *const *op_end,
154 const PointerType *PTy, const Type *Ty, Value *V);
156 Value *expand(const SCEV *S);
158 /// expandCodeFor - Insert code to directly compute the specified SCEV
159 /// expression into the program. The inserted code is inserted into the
160 /// SCEVExpander's current insertion point. If a type is specified, the
161 /// result will be expanded to have that type, with a cast if necessary.
162 Value *expandCodeFor(const SCEV *SH, const Type *Ty = 0);
164 /// isInsertedInstruction - Return true if the specified instruction was
165 /// inserted by the code rewriter. If so, the client should not modify the
167 bool isInsertedInstruction(Instruction *I) const {
168 return InsertedValues.count(I) || InsertedPostIncValues.count(I);
171 Value *visitConstant(const SCEVConstant *S) {
172 return S->getValue();
175 Value *visitTruncateExpr(const SCEVTruncateExpr *S);
177 Value *visitZeroExtendExpr(const SCEVZeroExtendExpr *S);
179 Value *visitSignExtendExpr(const SCEVSignExtendExpr *S);
181 Value *visitAddExpr(const SCEVAddExpr *S);
183 Value *visitMulExpr(const SCEVMulExpr *S);
185 Value *visitUDivExpr(const SCEVUDivExpr *S);
187 Value *visitAddRecExpr(const SCEVAddRecExpr *S);
189 Value *visitSMaxExpr(const SCEVSMaxExpr *S);
191 Value *visitUMaxExpr(const SCEVUMaxExpr *S);
193 Value *visitUnknown(const SCEVUnknown *S) {
194 return S->getValue();
197 void rememberInstruction(Value *I);
199 void restoreInsertPoint(BasicBlock *BB, BasicBlock::iterator I);
201 Value *expandAddRecExprLiterally(const SCEVAddRecExpr *);
202 PHINode *getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
204 const Type *ExpandTy,