1//===- llvm/Analysis/IVUsers.h - Induction Variable Users -------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements bookkeeping for "interesting" users of expressions
10// computed from induction variables.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_ANALYSIS_IVUSERS_H
15#define LLVM_ANALYSIS_IVUSERS_H
16
17#include "llvm/Analysis/LoopAnalysisManager.h"
18#include "llvm/Analysis/LoopPass.h"
19#include "llvm/Analysis/ScalarEvolutionNormalization.h"
20#include "llvm/IR/ValueHandle.h"
21
22namespace llvm {
23
24class AssumptionCache;
25class DominatorTree;
26class ScalarEvolution;
27class SCEV;
28class IVUsers;
29
30/// IVStrideUse - Keep track of one use of a strided induction variable.
31/// The Expr member keeps track of the expression, User is the actual user
32/// instruction of the operand, and 'OperandValToReplace' is the operand of
33/// the User that is the use.
34class IVStrideUse final : public CallbackVH, public ilist_node<IVStrideUse> {
35 friend class IVUsers;
36public:
37 IVStrideUse(IVUsers *P, Instruction* U, Value *O)
38 : CallbackVH(U), Parent(P), OperandValToReplace(O) {
39 }
40
41 /// getUser - Return the user instruction for this use.
42 Instruction *getUser() const {
43 return cast<Instruction>(Val: getValPtr());
44 }
45
46 /// setUser - Assign a new user instruction for this use.
47 void setUser(Instruction *NewUser) {
48 setValPtr(NewUser);
49 }
50
51 /// getOperandValToReplace - Return the Value of the operand in the user
52 /// instruction that this IVStrideUse is representing.
53 Value *getOperandValToReplace() const {
54 return OperandValToReplace;
55 }
56
57 /// setOperandValToReplace - Assign a new Value as the operand value
58 /// to replace.
59 void setOperandValToReplace(Value *Op) {
60 OperandValToReplace = Op;
61 }
62
63 /// getPostIncLoops - Return the set of loops for which the expression has
64 /// been adjusted to use post-inc mode.
65 const PostIncLoopSet &getPostIncLoops() const {
66 return PostIncLoops;
67 }
68
69 /// transformToPostInc - Transform the expression to post-inc form for the
70 /// given loop.
71 void transformToPostInc(const Loop *L);
72
73private:
74 /// Parent - a pointer to the IVUsers that owns this IVStrideUse.
75 IVUsers *Parent;
76
77 /// OperandValToReplace - The Value of the operand in the user instruction
78 /// that this IVStrideUse is representing.
79 WeakTrackingVH OperandValToReplace;
80
81 /// PostIncLoops - The set of loops for which Expr has been adjusted to
82 /// use post-inc mode. This corresponds with SCEVExpander's post-inc concept.
83 PostIncLoopSet PostIncLoops;
84
85 /// Deleted - Implementation of CallbackVH virtual function to
86 /// receive notification when the User is deleted.
87 void deleted() override;
88};
89
90class IVUsers {
91 friend class IVStrideUse;
92 Loop *L;
93 AssumptionCache *AC;
94 LoopInfo *LI;
95 DominatorTree *DT;
96 ScalarEvolution *SE;
97 SmallPtrSet<Instruction*, 16> Processed;
98
99 /// IVUses - A list of all tracked IV uses of induction variable expressions
100 /// we are interested in.
101 ilist<IVStrideUse> IVUses;
102
103 // Ephemeral values used by @llvm.assume in this function.
104 SmallPtrSet<const Value *, 32> EphValues;
105
106public:
107 IVUsers(Loop *L, AssumptionCache *AC, LoopInfo *LI, DominatorTree *DT,
108 ScalarEvolution *SE);
109
110 IVUsers(IVUsers &&X)
111 : L(std::move(X.L)), AC(std::move(X.AC)), DT(std::move(X.DT)),
112 SE(std::move(X.SE)), Processed(std::move(X.Processed)),
113 IVUses(std::move(X.IVUses)), EphValues(std::move(X.EphValues)) {
114 for (IVStrideUse &U : IVUses)
115 U.Parent = this;
116 }
117 IVUsers(const IVUsers &) = delete;
118 IVUsers &operator=(IVUsers &&) = delete;
119 IVUsers &operator=(const IVUsers &) = delete;
120
121 Loop *getLoop() const { return L; }
122
123 /// AddUsersIfInteresting - Inspect the specified Instruction. If it is a
124 /// reducible SCEV, recursively add its users to the IVUsesByStride set and
125 /// return true. Otherwise, return false.
126 bool AddUsersIfInteresting(Instruction *I);
127
128 IVStrideUse &AddUser(Instruction *User, Value *Operand);
129
130 /// getReplacementExpr - Return a SCEV expression which computes the
131 /// value of the OperandValToReplace of the given IVStrideUse.
132 const SCEV *getReplacementExpr(const IVStrideUse &IU) const;
133
134 /// getExpr - Return the expression for the use. Returns nullptr if the result
135 /// is not invertible.
136 const SCEV *getExpr(const IVStrideUse &IU) const;
137
138 const SCEV *getStride(const IVStrideUse &IU, const Loop *L) const;
139
140 typedef ilist<IVStrideUse>::iterator iterator;
141 typedef ilist<IVStrideUse>::const_iterator const_iterator;
142 iterator begin() { return IVUses.begin(); }
143 iterator end() { return IVUses.end(); }
144 const_iterator begin() const { return IVUses.begin(); }
145 const_iterator end() const { return IVUses.end(); }
146 bool empty() const { return IVUses.empty(); }
147
148 bool isIVUserOrOperand(Instruction *Inst) const {
149 return Processed.count(Ptr: Inst);
150 }
151
152 void releaseMemory();
153
154 void print(raw_ostream &OS, const Module * = nullptr) const;
155
156 /// dump - This method is used for debugging.
157 void dump() const;
158};
159
160Pass *createIVUsersPass();
161
162class IVUsersWrapperPass : public LoopPass {
163 std::unique_ptr<IVUsers> IU;
164
165public:
166 static char ID;
167
168 IVUsersWrapperPass();
169
170 IVUsers &getIU() { return *IU; }
171 const IVUsers &getIU() const { return *IU; }
172
173 void getAnalysisUsage(AnalysisUsage &AU) const override;
174
175 bool runOnLoop(Loop *L, LPPassManager &LPM) override;
176
177 void releaseMemory() override;
178
179 void print(raw_ostream &OS, const Module * = nullptr) const override;
180};
181
182/// Analysis pass that exposes the \c IVUsers for a loop.
183class IVUsersAnalysis : public AnalysisInfoMixin<IVUsersAnalysis> {
184 friend AnalysisInfoMixin<IVUsersAnalysis>;
185 static AnalysisKey Key;
186
187public:
188 typedef IVUsers Result;
189
190 IVUsers run(Loop &L, LoopAnalysisManager &AM,
191 LoopStandardAnalysisResults &AR);
192};
193
194}
195
196#endif
197

source code of llvm/include/llvm/Analysis/IVUsers.h