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;
33 /// IVStrideUse - Keep track of one use of a strided induction variable.
34 /// The Expr member keeps track of the expression, User is the actual user
35 /// instruction of the operand, and 'OperandValToReplace' is the operand of
36 /// the User that is the use.
37 class IVStrideUse : public CallbackVH, public ilist_node<IVStrideUse> {
40 IVStrideUse(IVUsers *P, Instruction* U, Value *O, Value *PN)
41 : CallbackVH(U), Parent(P), OperandValToReplace(O), Phi(PN) {
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 /// getPhi - Return the phi node that represents this IV.
55 PHINode *getPhi() const {
56 return cast<PHINode>(Phi);
59 /// getOperandValToReplace - Return the Value of the operand in the user
60 /// instruction that this IVStrideUse is representing.
61 Value *getOperandValToReplace() const {
62 return OperandValToReplace;
65 /// setOperandValToReplace - Assign a new Value as the operand value
67 void setOperandValToReplace(Value *Op) {
68 OperandValToReplace = Op;
71 /// getPostIncLoops - Return the set of loops for which the expression has
72 /// been adjusted to use post-inc mode.
73 const PostIncLoopSet &getPostIncLoops() const {
77 /// transformToPostInc - Transform the expression to post-inc form for the
79 void transformToPostInc(const Loop *L);
82 /// Parent - a pointer to the IVUsers that owns this IVStrideUse.
85 /// OperandValToReplace - The Value of the operand in the user instruction
86 /// that this IVStrideUse is representing.
87 WeakVH OperandValToReplace;
89 /// Phi - The loop header phi that represents this IV.
92 /// PostIncLoops - The set of loops for which Expr has been adjusted to
93 /// use post-inc mode. This corresponds with SCEVExpander's post-inc concept.
94 PostIncLoopSet PostIncLoops;
96 /// Deleted - Implementation of CallbackVH virtual function to
97 /// receive notification when the User is deleted.
98 virtual void deleted();
101 template<> struct ilist_traits<IVStrideUse>
102 : public ilist_default_traits<IVStrideUse> {
103 // createSentinel is used to get hold of a node that marks the end of
105 // The sentinel is relative to this instance, so we use a non-static
107 IVStrideUse *createSentinel() const {
108 // since i(p)lists always publicly derive from the corresponding
109 // traits, placing a data member in this class will augment i(p)list.
110 // But since the NodeTy is expected to publicly derive from
111 // ilist_node<NodeTy>, there is a legal viable downcast from it
112 // to NodeTy. We use this trick to superpose i(p)list with a "ghostly"
113 // NodeTy, which becomes the sentinel. Dereferencing the sentinel is
114 // forbidden (save the ilist_node<NodeTy>) so no one will ever notice
115 // the superposition.
116 return static_cast<IVStrideUse*>(&Sentinel);
118 static void destroySentinel(IVStrideUse*) {}
120 IVStrideUse *provideInitialHead() const { return createSentinel(); }
121 IVStrideUse *ensureHead(IVStrideUse*) const { return createSentinel(); }
122 static void noteHead(IVStrideUse*, IVStrideUse*) {}
125 mutable ilist_node<IVStrideUse> Sentinel;
128 class IVUsers : public LoopPass {
129 friend class IVStrideUse;
135 SmallPtrSet<Instruction*,16> Processed;
137 /// IVUses - A list of all tracked IV uses of induction variable expressions
138 /// we are interested in.
139 ilist<IVStrideUse> IVUses;
141 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
143 virtual bool runOnLoop(Loop *L, LPPassManager &LPM);
145 virtual void releaseMemory();
148 static char ID; // Pass ID, replacement for typeid
151 /// AddUsersIfInteresting - Inspect the specified Instruction. If it is a
152 /// reducible SCEV, recursively add its users to the IVUsesByStride set and
153 /// return true. Otherwise, return false.
154 bool AddUsersIfInteresting(Instruction *I, PHINode *Phi);
156 IVStrideUse &AddUser(Instruction *User, Value *Operand, PHINode *Phi);
158 /// getReplacementExpr - Return a SCEV expression which computes the
159 /// value of the OperandValToReplace of the given IVStrideUse.
160 const SCEV *getReplacementExpr(const IVStrideUse &IU) const;
162 /// getExpr - Return the expression for the use.
163 const SCEV *getExpr(const IVStrideUse &IU) const;
165 const SCEV *getStride(const IVStrideUse &IU, const Loop *L) const;
167 typedef ilist<IVStrideUse>::iterator iterator;
168 typedef ilist<IVStrideUse>::const_iterator const_iterator;
169 iterator begin() { return IVUses.begin(); }
170 iterator end() { return IVUses.end(); }
171 const_iterator begin() const { return IVUses.begin(); }
172 const_iterator end() const { return IVUses.end(); }
173 bool empty() const { return IVUses.empty(); }
175 void print(raw_ostream &OS, const Module* = 0) const;
177 /// dump - This method is used for debugging.
181 Pass *createIVUsersPass();