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/Instruction.h"
21#include "llvm/IR/ValueHandle.h"
22
23namespace llvm {
24
25class AssumptionCache;
26class DominatorTree;
27class ScalarEvolution;
28class SCEV;
29class IVUsers;
30
31/// IVStrideUse - Keep track of one use of a strided induction variable.
32/// The Expr member keeps track of the expression, User is the actual user
33/// instruction of the operand, and 'OperandValToReplace' is the operand of
34/// the User that is the use.
35class IVStrideUse final : public CallbackVH, public ilist_node<IVStrideUse> {
36 friend class IVUsers;
37public:
38 IVStrideUse(IVUsers *P, Instruction* U, Value *O)
39 : CallbackVH(U), Parent(P), OperandValToReplace(O) {
40 }
41
42 /// getUser - Return the user instruction for this use.
43 Instruction *getUser() const {
44 return cast<Instruction>(Val: getValPtr());
45 }
46
47 /// setUser - Assign a new user instruction for this use.
48 void setUser(Instruction *NewUser) {
49 setValPtr(NewUser);
50 }
51
52 /// getOperandValToReplace - Return the Value of the operand in the user
53 /// instruction that this IVStrideUse is representing.
54 Value *getOperandValToReplace() const {
55 return OperandValToReplace;
56 }
57
58 /// setOperandValToReplace - Assign a new Value as the operand value
59 /// to replace.
60 void setOperandValToReplace(Value *Op) {
61 OperandValToReplace = Op;
62 }
63
64 /// getPostIncLoops - Return the set of loops for which the expression has
65 /// been adjusted to use post-inc mode.
66 const PostIncLoopSet &getPostIncLoops() const {
67 return PostIncLoops;
68 }
69
70 /// transformToPostInc - Transform the expression to post-inc form for the
71 /// given loop.
72 void transformToPostInc(const Loop *L);
73
74private:
75 /// Parent - a pointer to the IVUsers that owns this IVStrideUse.
76 IVUsers *Parent;
77
78 /// OperandValToReplace - The Value of the operand in the user instruction
79 /// that this IVStrideUse is representing.
80 WeakTrackingVH OperandValToReplace;
81
82 /// PostIncLoops - The set of loops for which Expr has been adjusted to
83 /// use post-inc mode. This corresponds with SCEVExpander's post-inc concept.
84 PostIncLoopSet PostIncLoops;
85
86 /// Deleted - Implementation of CallbackVH virtual function to
87 /// receive notification when the User is deleted.
88 void deleted() override;
89};
90
91class IVUsers {
92 friend class IVStrideUse;
93 Loop *L;
94 AssumptionCache *AC;
95 LoopInfo *LI;
96 DominatorTree *DT;
97 ScalarEvolution *SE;
98 SmallPtrSet<Instruction*, 16> Processed;
99
100 /// IVUses - A list of all tracked IV uses of induction variable expressions
101 /// we are interested in.
102 ilist<IVStrideUse> IVUses;
103
104 // Ephemeral values used by @llvm.assume in this function.
105 SmallPtrSet<const Value *, 32> EphValues;
106
107public:
108 IVUsers(Loop *L, AssumptionCache *AC, LoopInfo *LI, DominatorTree *DT,
109 ScalarEvolution *SE);
110
111 IVUsers(IVUsers &&X)
112 : L(std::move(X.L)), AC(std::move(X.AC)), DT(std::move(X.DT)),
113 SE(std::move(X.SE)), Processed(std::move(X.Processed)),
114 IVUses(std::move(X.IVUses)), EphValues(std::move(X.EphValues)) {
115 for (IVStrideUse &U : IVUses)
116 U.Parent = this;
117 }
118 IVUsers(const IVUsers &) = delete;
119 IVUsers &operator=(IVUsers &&) = delete;
120 IVUsers &operator=(const IVUsers &) = delete;
121
122 Loop *getLoop() const { return L; }
123
124 /// AddUsersIfInteresting - Inspect the specified Instruction. If it is a
125 /// reducible SCEV, recursively add its users to the IVUsesByStride set and
126 /// return true. Otherwise, return false.
127 bool AddUsersIfInteresting(Instruction *I);
128
129 IVStrideUse &AddUser(Instruction *User, Value *Operand);
130
131 /// getReplacementExpr - Return a SCEV expression which computes the
132 /// value of the OperandValToReplace of the given IVStrideUse.
133 const SCEV *getReplacementExpr(const IVStrideUse &IU) const;
134
135 /// getExpr - Return the expression for the use. Returns nullptr if the result
136 /// is not invertible.
137 const SCEV *getExpr(const IVStrideUse &IU) const;
138
139 const SCEV *getStride(const IVStrideUse &IU, const Loop *L) const;
140
141 typedef ilist<IVStrideUse>::iterator iterator;
142 typedef ilist<IVStrideUse>::const_iterator const_iterator;
143 iterator begin() { return IVUses.begin(); }
144 iterator end() { return IVUses.end(); }
145 const_iterator begin() const { return IVUses.begin(); }
146 const_iterator end() const { return IVUses.end(); }
147 bool empty() const { return IVUses.empty(); }
148
149 bool isIVUserOrOperand(Instruction *Inst) const {
150 return Processed.count(Ptr: Inst);
151 }
152
153 void releaseMemory();
154
155 void print(raw_ostream &OS, const Module * = nullptr) const;
156
157 /// dump - This method is used for debugging.
158 void dump() const;
159};
160
161Pass *createIVUsersPass();
162
163class IVUsersWrapperPass : public LoopPass {
164 std::unique_ptr<IVUsers> IU;
165
166public:
167 static char ID;
168
169 IVUsersWrapperPass();
170
171 IVUsers &getIU() { return *IU; }
172 const IVUsers &getIU() const { return *IU; }
173
174 void getAnalysisUsage(AnalysisUsage &AU) const override;
175
176 bool runOnLoop(Loop *L, LPPassManager &LPM) override;
177
178 void releaseMemory() override;
179
180 void print(raw_ostream &OS, const Module * = nullptr) const override;
181};
182
183/// Analysis pass that exposes the \c IVUsers for a loop.
184class IVUsersAnalysis : public AnalysisInfoMixin<IVUsersAnalysis> {
185 friend AnalysisInfoMixin<IVUsersAnalysis>;
186 static AnalysisKey Key;
187
188public:
189 typedef IVUsers Result;
190
191 IVUsers run(Loop &L, LoopAnalysisManager &AM,
192 LoopStandardAnalysisResults &AR);
193};
194
195}
196
197#endif
198