include/llvm/Analysis/IVUsers.h

   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:
  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.
  45   Instruction *getUser() const {
  46     return cast<Instruction>(getValPtr());
  47   }
  48
  49   /// setUser - Assign a new user instruction for this use.
  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.
  56   Value *getOperandValToReplace() const {
  57     return OperandValToReplace;
  58   }
  59
  60   /// setOperandValToReplace - Assign a new Value as the operand value
  61   /// to replace.
  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.
  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
 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
 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;
 144   iterator begin() { return IVUses.begin(); }
 145   iterator end()   { return IVUses.end(); }
 146   const_iterator begin() const { return IVUses.begin(); }
 147   const_iterator end() const   { return IVUses.end(); }
 148   bool empty() const { return IVUses.empty(); }
 149
 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
 175   IVUsers &getIU() { return *IU; }
 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