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/IR/ValueHandle.h"
27 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, Instruction* U, Value *O)
40 : CallbackVH(U), Parent(P), OperandValToReplace(O) {
43 /// getUser - Return the user instruction for this use.
44 Instruction *getUser() const {
45 return cast<Instruction>(getValPtr());
48 /// setUser - Assign a new user instruction for this use.
49 void setUser(Instruction *NewUser) {
53 /// getOperandValToReplace - Return the Value of the operand in the user
54 /// instruction that this IVStrideUse is representing.
55 Value *getOperandValToReplace() const {
56 return OperandValToReplace;
59 /// setOperandValToReplace - Assign a new Value as the operand value
61 void setOperandValToReplace(Value *Op) {
62 OperandValToReplace = Op;
65 /// getPostIncLoops - Return the set of loops for which the expression has
66 /// been adjusted to use post-inc mode.
67 const PostIncLoopSet &getPostIncLoops() const {
71 /// transformToPostInc - Transform the expression to post-inc form for the
73 void transformToPostInc(const Loop *L);
76 /// Parent - a pointer to the IVUsers that owns this IVStrideUse.
79 /// OperandValToReplace - The Value of the operand in the user instruction
80 /// that this IVStrideUse is representing.
81 WeakVH OperandValToReplace;
83 /// PostIncLoops - The set of loops for which Expr has been adjusted to
84 /// use post-inc mode. This corresponds with SCEVExpander's post-inc concept.
85 PostIncLoopSet PostIncLoops;
87 /// Deleted - Implementation of CallbackVH virtual function to
88 /// receive notification when the User is deleted.
89 void deleted() override;
92 template<> struct ilist_traits<IVStrideUse>
93 : public ilist_default_traits<IVStrideUse> {
94 // createSentinel is used to get hold of a node that marks the end of
96 // The sentinel is relative to this instance, so we use a non-static
98 IVStrideUse *createSentinel() const {
99 // since i(p)lists always publicly derive from the corresponding
100 // traits, placing a data member in this class will augment i(p)list.
101 // But since the NodeTy is expected to publicly derive from
102 // ilist_node<NodeTy>, there is a legal viable downcast from it
103 // to NodeTy. We use this trick to superpose i(p)list with a "ghostly"
104 // NodeTy, which becomes the sentinel. Dereferencing the sentinel is
105 // forbidden (save the ilist_node<NodeTy>) so no one will ever notice
106 // the superposition.
107 return static_cast<IVStrideUse*>(&Sentinel);
109 static void destroySentinel(IVStrideUse*) {}
111 IVStrideUse *provideInitialHead() const { return createSentinel(); }
112 IVStrideUse *ensureHead(IVStrideUse*) const { return createSentinel(); }
113 static void noteHead(IVStrideUse*, IVStrideUse*) {}
116 mutable ilist_node<IVStrideUse> Sentinel;
119 class IVUsers : public LoopPass {
120 friend class IVStrideUse;
125 const DataLayout *DL;
126 SmallPtrSet<Instruction*,16> Processed;
128 /// IVUses - A list of all tracked IV uses of induction variable expressions
129 /// we are interested in.
130 ilist<IVStrideUse> IVUses;
132 void getAnalysisUsage(AnalysisUsage &AU) const override;
134 bool runOnLoop(Loop *L, LPPassManager &LPM) override;
136 void releaseMemory() override;
139 static char ID; // Pass ID, replacement for typeid
142 Loop *getLoop() const { return L; }
144 /// AddUsersIfInteresting - Inspect the specified Instruction. If it is a
145 /// reducible SCEV, recursively add its users to the IVUsesByStride set and
146 /// return true. Otherwise, return false.
147 bool AddUsersIfInteresting(Instruction *I);
149 IVStrideUse &AddUser(Instruction *User, Value *Operand);
151 /// getReplacementExpr - Return a SCEV expression which computes the
152 /// value of the OperandValToReplace of the given IVStrideUse.
153 const SCEV *getReplacementExpr(const IVStrideUse &IU) const;
155 /// getExpr - Return the expression for the use.
156 const SCEV *getExpr(const IVStrideUse &IU) const;
158 const SCEV *getStride(const IVStrideUse &IU, const Loop *L) const;
160 typedef ilist<IVStrideUse>::iterator iterator;
161 typedef ilist<IVStrideUse>::const_iterator const_iterator;
162 iterator begin() { return IVUses.begin(); }
163 iterator end() { return IVUses.end(); }
164 const_iterator begin() const { return IVUses.begin(); }
165 const_iterator end() const { return IVUses.end(); }
166 bool empty() const { return IVUses.empty(); }
168 bool isIVUserOrOperand(Instruction *Inst) const {
169 return Processed.count(Inst);
172 void print(raw_ostream &OS, const Module* = 0) const override;
174 /// dump - This method is used for debugging.
177 bool AddUsersImpl(Instruction *I, SmallPtrSet<Loop*,16> &SimpleLoopNests);
180 Pass *createIVUsersPass();