1 //===- llvm/Analysis/IVUsers.h - Induction Variable Users -------*- 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 implements bookkeeping for "interesting" users of expressions
11 // computed from induction variables.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_ANALYSIS_IVUSERS_H
16 #define LLVM_ANALYSIS_IVUSERS_H
18 #include "llvm/Analysis/LoopPass.h"
19 #include "llvm/Analysis/ScalarEvolutionNormalization.h"
20 #include "llvm/Support/ValueHandle.h"
28 class ScalarEvolution;
32 /// IVStrideUse - Keep track of one use of a strided induction variable.
33 /// The Expr member keeps track of the expression, User is the actual user
34 /// instruction of the operand, and 'OperandValToReplace' is the operand of
35 /// the User that is the use.
36 class IVStrideUse : public CallbackVH, public ilist_node<IVStrideUse> {
39 IVStrideUse(IVUsers *P, const SCEV *E,
40 Instruction* U, Value *O)
41 : CallbackVH(U), Parent(P), Expr(E), OperandValToReplace(O) {
44 /// getUser - Return the user instruction for this use.
45 Instruction *getUser() const {
46 return cast<Instruction>(getValPtr());
49 /// setUser - Assign a new user instruction for this use.
50 void setUser(Instruction *NewUser) {
54 /// getParent - Return a pointer to the IVUsers that owns
56 IVUsers *getParent() const { return Parent; }
58 /// getExpr - Return the expression for the use.
59 const SCEV *getExpr() const { return Expr; }
61 /// setExpr - Assign a new expression to this use.
62 void setExpr(const SCEV *Val) {
66 const SCEV *getStride(const Loop *L) const;
68 /// getOperandValToReplace - Return the Value of the operand in the user
69 /// instruction that this IVStrideUse is representing.
70 Value *getOperandValToReplace() const {
71 return OperandValToReplace;
74 /// setOperandValToReplace - Assign a new Value as the operand value
76 void setOperandValToReplace(Value *Op) {
77 OperandValToReplace = Op;
80 /// getPostIncLoops - Return the set of loops for which the expression has
81 /// been adjusted to use post-inc mode.
82 const PostIncLoopSet &getPostIncLoops() const {
86 /// transformToPostInc - Transform the expression to post-inc form for the
88 void transformToPostInc(const Loop *L);
91 /// Parent - a pointer to the IVUsers that owns this IVStrideUse.
94 /// Expr - The expression for this use.
97 /// OperandValToReplace - The Value of the operand in the user instruction
98 /// that this IVStrideUse is representing.
99 WeakVH OperandValToReplace;
101 /// PostIncLoops - The set of loops for which Expr has been adjusted to
102 /// use post-inc mode. This corresponds with SCEVExpander's post-inc concept.
103 PostIncLoopSet PostIncLoops;
105 /// Deleted - Implementation of CallbackVH virtual function to
106 /// receive notification when the User is deleted.
107 virtual void deleted();
110 template<> struct ilist_traits<IVStrideUse>
111 : public ilist_default_traits<IVStrideUse> {
112 // createSentinel is used to get hold of a node that marks the end of
114 // The sentinel is relative to this instance, so we use a non-static
116 IVStrideUse *createSentinel() const {
117 // since i(p)lists always publicly derive from the corresponding
118 // traits, placing a data member in this class will augment i(p)list.
119 // But since the NodeTy is expected to publicly derive from
120 // ilist_node<NodeTy>, there is a legal viable downcast from it
121 // to NodeTy. We use this trick to superpose i(p)list with a "ghostly"
122 // NodeTy, which becomes the sentinel. Dereferencing the sentinel is
123 // forbidden (save the ilist_node<NodeTy>) so no one will ever notice
124 // the superposition.
125 return static_cast<IVStrideUse*>(&Sentinel);
127 static void destroySentinel(IVStrideUse*) {}
129 IVStrideUse *provideInitialHead() const { return createSentinel(); }
130 IVStrideUse *ensureHead(IVStrideUse*) const { return createSentinel(); }
131 static void noteHead(IVStrideUse*, IVStrideUse*) {}
134 mutable ilist_node<IVStrideUse> Sentinel;
137 class IVUsers : public LoopPass {
138 friend class IVStrideUse;
143 SmallPtrSet<Instruction*,16> Processed;
145 /// IVUses - A list of all tracked IV uses of induction variable expressions
146 /// we are interested in.
147 ilist<IVStrideUse> IVUses;
149 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
151 virtual bool runOnLoop(Loop *L, LPPassManager &LPM);
153 virtual void releaseMemory();
156 static char ID; // Pass ID, replacement for typeid
159 /// AddUsersIfInteresting - Inspect the specified Instruction. If it is a
160 /// reducible SCEV, recursively add its users to the IVUsesByStride set and
161 /// return true. Otherwise, return false.
162 bool AddUsersIfInteresting(Instruction *I);
164 IVStrideUse &AddUser(const SCEV *Expr,
165 Instruction *User, Value *Operand);
167 /// getReplacementExpr - Return a SCEV expression which computes the
168 /// value of the OperandValToReplace of the given IVStrideUse.
169 const SCEV *getReplacementExpr(const IVStrideUse &U) const;
171 typedef ilist<IVStrideUse>::iterator iterator;
172 typedef ilist<IVStrideUse>::const_iterator const_iterator;
173 iterator begin() { return IVUses.begin(); }
174 iterator end() { return IVUses.end(); }
175 const_iterator begin() const { return IVUses.begin(); }
176 const_iterator end() const { return IVUses.end(); }
177 bool empty() const { return IVUses.empty(); }
179 void print(raw_ostream &OS, const Module* = 0) const;
181 /// dump - This method is used for debugging.
185 Pass *createIVUsersPass();