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1 : //===- llvm/Analysis/IVUsers.h - Induction Variable Users -------*- C++ -*-===//
2 : //
3 : // The LLVM Compiler Infrastructure
4 : //
5 : // This file is distributed under the University of Illinois Open Source
6 : // License. See LICENSE.TXT for details.
7 : //
8 : //===----------------------------------------------------------------------===//
9 : //
10 : // This file implements bookkeeping for "interesting" users of expressions
11 : // computed from induction variables.
12 : //
13 : //===----------------------------------------------------------------------===//
14 :
15 : #ifndef LLVM_ANALYSIS_IVUSERS_H
16 : #define LLVM_ANALYSIS_IVUSERS_H
17 :
18 : #include "llvm/Analysis/LoopAnalysisManager.h"
19 : #include "llvm/Analysis/LoopPass.h"
20 : #include "llvm/Analysis/ScalarEvolutionNormalization.h"
21 : #include "llvm/IR/ValueHandle.h"
22 :
23 : namespace llvm {
24 :
25 : class AssumptionCache;
26 : class DominatorTree;
27 : class Instruction;
28 : class Value;
29 : class ScalarEvolution;
30 : class SCEV;
31 : class IVUsers;
32 : class DataLayout;
33 :
34 : /// IVStrideUse - Keep track of one use of a strided induction variable.
35 : /// The Expr member keeps track of the expression, User is the actual user
36 : /// instruction of the operand, and 'OperandValToReplace' is the operand of
37 : /// the User that is the use.
38 : class IVStrideUse final : public CallbackVH, public ilist_node<IVStrideUse> {
39 : friend class IVUsers;
40 : public:
41 19471 : IVStrideUse(IVUsers *P, Instruction* U, Value *O)
42 38942 : : CallbackVH(U), Parent(P), OperandValToReplace(O) {
43 19471 : }
44 :
45 : /// getUser - Return the user instruction for this use.
46 : Instruction *getUser() const {
47 72574 : return cast<Instruction>(getValPtr());
48 : }
49 :
50 : /// setUser - Assign a new user instruction for this use.
51 : void setUser(Instruction *NewUser) {
52 : setValPtr(NewUser);
53 : }
54 :
55 : /// getOperandValToReplace - Return the Value of the operand in the user
56 : /// instruction that this IVStrideUse is representing.
57 : Value *getOperandValToReplace() const {
58 : return OperandValToReplace;
59 : }
60 :
61 : /// setOperandValToReplace - Assign a new Value as the operand value
62 : /// to replace.
63 : void setOperandValToReplace(Value *Op) {
64 : OperandValToReplace = Op;
65 : }
66 :
67 : /// getPostIncLoops - Return the set of loops for which the expression has
68 : /// been adjusted to use post-inc mode.
69 : const PostIncLoopSet &getPostIncLoops() const {
70 33594 : return PostIncLoops;
71 : }
72 :
73 : /// transformToPostInc - Transform the expression to post-inc form for the
74 : /// given loop.
75 : void transformToPostInc(const Loop *L);
76 :
77 : private:
78 : /// Parent - a pointer to the IVUsers that owns this IVStrideUse.
79 : IVUsers *Parent;
80 :
81 : /// OperandValToReplace - The Value of the operand in the user instruction
82 : /// that this IVStrideUse is representing.
83 : WeakTrackingVH OperandValToReplace;
84 :
85 : /// PostIncLoops - The set of loops for which Expr has been adjusted to
86 : /// use post-inc mode. This corresponds with SCEVExpander's post-inc concept.
87 : PostIncLoopSet PostIncLoops;
88 :
89 : /// Deleted - Implementation of CallbackVH virtual function to
90 : /// receive notification when the User is deleted.
91 : void deleted() override;
92 : };
93 :
94 : class IVUsers {
95 : friend class IVStrideUse;
96 : Loop *L;
97 : AssumptionCache *AC;
98 : LoopInfo *LI;
99 : DominatorTree *DT;
100 : ScalarEvolution *SE;
101 : SmallPtrSet<Instruction*, 16> Processed;
102 :
103 : /// IVUses - A list of all tracked IV uses of induction variable expressions
104 : /// we are interested in.
105 : ilist<IVStrideUse> IVUses;
106 :
107 : // Ephemeral values used by @llvm.assume in this function.
108 : SmallPtrSet<const Value *, 32> EphValues;
109 :
110 : public:
111 : IVUsers(Loop *L, AssumptionCache *AC, LoopInfo *LI, DominatorTree *DT,
112 : ScalarEvolution *SE);
113 :
114 24 : IVUsers(IVUsers &&X)
115 72 : : L(std::move(X.L)), AC(std::move(X.AC)), DT(std::move(X.DT)),
116 24 : SE(std::move(X.SE)), Processed(std::move(X.Processed)),
117 24 : IVUses(std::move(X.IVUses)), EphValues(std::move(X.EphValues)) {
118 40 : for (IVStrideUse &U : IVUses)
119 16 : U.Parent = this;
120 24 : }
121 : IVUsers(const IVUsers &) = delete;
122 : IVUsers &operator=(IVUsers &&) = delete;
123 : IVUsers &operator=(const IVUsers &) = delete;
124 :
125 : Loop *getLoop() const { return L; }
126 :
127 : /// AddUsersIfInteresting - Inspect the specified Instruction. If it is a
128 : /// reducible SCEV, recursively add its users to the IVUsesByStride set and
129 : /// return true. Otherwise, return false.
130 : bool AddUsersIfInteresting(Instruction *I);
131 :
132 : IVStrideUse &AddUser(Instruction *User, Value *Operand);
133 :
134 : /// getReplacementExpr - Return a SCEV expression which computes the
135 : /// value of the OperandValToReplace of the given IVStrideUse.
136 : const SCEV *getReplacementExpr(const IVStrideUse &IU) const;
137 :
138 : /// getExpr - Return the expression for the use.
139 : const SCEV *getExpr(const IVStrideUse &IU) const;
140 :
141 : const SCEV *getStride(const IVStrideUse &IU, const Loop *L) const;
142 :
143 : typedef ilist<IVStrideUse>::iterator iterator;
144 : typedef ilist<IVStrideUse>::const_iterator const_iterator;
145 : iterator begin() { return IVUses.begin(); }
146 : iterator end() { return IVUses.end(); }
147 : const_iterator begin() const { return IVUses.begin(); }
148 : const_iterator end() const { return IVUses.end(); }
149 : bool empty() const { return IVUses.empty(); }
150 :
151 : bool isIVUserOrOperand(Instruction *Inst) const {
152 118133 : return Processed.count(Inst);
153 : }
154 :
155 : void releaseMemory();
156 :
157 : void print(raw_ostream &OS, const Module * = nullptr) const;
158 :
159 : /// dump - This method is used for debugging.
160 : void dump() const;
161 :
162 : protected:
163 : bool AddUsersImpl(Instruction *I, SmallPtrSetImpl<Loop*> &SimpleLoopNests);
164 : };
165 :
166 : Pass *createIVUsersPass();
167 :
168 : class IVUsersWrapperPass : public LoopPass {
169 : std::unique_ptr<IVUsers> IU;
170 :
171 : public:
172 : static char ID;
173 :
174 : IVUsersWrapperPass();
175 :
176 : IVUsers &getIU() { return *IU; }
177 : const IVUsers &getIU() const { return *IU; }
178 :
179 : void getAnalysisUsage(AnalysisUsage &AU) const override;
180 :
181 : bool runOnLoop(Loop *L, LPPassManager &LPM) override;
182 :
183 : void releaseMemory() override;
184 :
185 : void print(raw_ostream &OS, const Module * = nullptr) const override;
186 : };
187 :
188 : /// Analysis pass that exposes the \c IVUsers for a loop.
189 : class IVUsersAnalysis : public AnalysisInfoMixin<IVUsersAnalysis> {
190 : friend AnalysisInfoMixin<IVUsersAnalysis>;
191 : static AnalysisKey Key;
192 :
193 : public:
194 : typedef IVUsers Result;
195 :
196 : IVUsers run(Loop &L, LoopAnalysisManager &AM,
197 : LoopStandardAnalysisResults &AR);
198 : };
199 :
200 : }
201 :
202 : #endif
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