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