Subversion Repositories QNX 8.QNX8 LLVM/Clang compiler suite

//===- llvm/Analysis/IVUsers.h - Induction Variable Users -------*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

// This file implements bookkeeping for "interesting" users of expressions

// computed from induction variables.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_ANALYSIS_IVUSERS_H

#define LLVM_ANALYSIS_IVUSERS_H

#include "llvm/Analysis/LoopAnalysisManager.h"

#include "llvm/Analysis/LoopPass.h"

#include "llvm/Analysis/ScalarEvolutionNormalization.h"

#include "llvm/IR/ValueHandle.h"

namespace llvm {

class AssumptionCache;

class DominatorTree;

class ScalarEvolution;

class SCEV;

class IVUsers;

/// IVStrideUse - Keep track of one use of a strided induction variable.

/// The Expr member keeps track of the expression, User is the actual user

/// instruction of the operand, and 'OperandValToReplace' is the operand of

/// the User that is the use.

class IVStrideUse final : public CallbackVH, public ilist_node<IVStrideUse> {

  friend class IVUsers;

public:

  IVStrideUse(IVUsers *P, Instruction* U, Value *O)

    : CallbackVH(U), Parent(P), OperandValToReplace(O) {

  }

  /// getUser - Return the user instruction for this use.

  Instruction *getUser() const {

    return cast<Instruction>(getValPtr());

  }

  /// setUser - Assign a new user instruction for this use.

  void setUser(Instruction *NewUser) {

    setValPtr(NewUser);

  }

  /// getOperandValToReplace - Return the Value of the operand in the user

  /// instruction that this IVStrideUse is representing.

  Value *getOperandValToReplace() const {

    return OperandValToReplace;

  }

  /// setOperandValToReplace - Assign a new Value as the operand value

  /// to replace.

  void setOperandValToReplace(Value *Op) {

    OperandValToReplace = Op;

  }

  /// getPostIncLoops - Return the set of loops for which the expression has

  /// been adjusted to use post-inc mode.

  const PostIncLoopSet &getPostIncLoops() const {

    return PostIncLoops;

  }

  /// transformToPostInc - Transform the expression to post-inc form for the

  /// given loop.

  void transformToPostInc(const Loop *L);

private:

  /// Parent - a pointer to the IVUsers that owns this IVStrideUse.

  IVUsers *Parent;

  /// OperandValToReplace - The Value of the operand in the user instruction

  /// that this IVStrideUse is representing.

  WeakTrackingVH OperandValToReplace;

  /// PostIncLoops - The set of loops for which Expr has been adjusted to

  /// use post-inc mode. This corresponds with SCEVExpander's post-inc concept.

  PostIncLoopSet PostIncLoops;

  /// Deleted - Implementation of CallbackVH virtual function to

  /// receive notification when the User is deleted.

  void deleted() override;

};

class IVUsers {

  friend class IVStrideUse;

  Loop *L;

  AssumptionCache *AC;

  LoopInfo *LI;

  DominatorTree *DT;

  ScalarEvolution *SE;

  SmallPtrSet<Instruction*, 16> Processed;

  /// IVUses - A list of all tracked IV uses of induction variable expressions

  /// we are interested in.

  ilist<IVStrideUse> IVUses;

  // Ephemeral values used by @llvm.assume in this function.

  SmallPtrSet<const Value *, 32> EphValues;

public:

  IVUsers(Loop *L, AssumptionCache *AC, LoopInfo *LI, DominatorTree *DT,

          ScalarEvolution *SE);

  IVUsers(IVUsers &&X)

      : L(std::move(X.L)), AC(std::move(X.AC)), DT(std::move(X.DT)),

        SE(std::move(X.SE)), Processed(std::move(X.Processed)),

        IVUses(std::move(X.IVUses)), EphValues(std::move(X.EphValues)) {

    for (IVStrideUse &U : IVUses)

      U.Parent = this;

  }

  IVUsers(const IVUsers &) = delete;

  IVUsers &operator=(IVUsers &&) = delete;

  IVUsers &operator=(const IVUsers &) = delete;

  Loop *getLoop() const { return L; }

  /// AddUsersIfInteresting - Inspect the specified Instruction.  If it is a

  /// reducible SCEV, recursively add its users to the IVUsesByStride set and

  /// return true.  Otherwise, return false.

  bool AddUsersIfInteresting(Instruction *I);

  IVStrideUse &AddUser(Instruction *User, Value *Operand);

  /// getReplacementExpr - Return a SCEV expression which computes the

  /// value of the OperandValToReplace of the given IVStrideUse.

  const SCEV *getReplacementExpr(const IVStrideUse &IU) const;

  /// getExpr - Return the expression for the use.

  const SCEV *getExpr(const IVStrideUse &IU) const;

  const SCEV *getStride(const IVStrideUse &IU, const Loop *L) const;

  typedef ilist<IVStrideUse>::iterator iterator;

  typedef ilist<IVStrideUse>::const_iterator const_iterator;

  iterator begin() { return IVUses.begin(); }

  iterator end()   { return IVUses.end(); }

  const_iterator begin() const { return IVUses.begin(); }

  const_iterator end() const   { return IVUses.end(); }

  bool empty() const { return IVUses.empty(); }

  bool isIVUserOrOperand(Instruction *Inst) const {

    return Processed.count(Inst);

  }

  void releaseMemory();

  void print(raw_ostream &OS, const Module * = nullptr) const;

  /// dump - This method is used for debugging.

  void dump() const;

};

Pass *createIVUsersPass();

class IVUsersWrapperPass : public LoopPass {

  std::unique_ptr<IVUsers> IU;

public:

  static char ID;

  IVUsersWrapperPass();

  IVUsers &getIU() { return *IU; }

  const IVUsers &getIU() const { return *IU; }

  void getAnalysisUsage(AnalysisUsage &AU) const override;

  bool runOnLoop(Loop *L, LPPassManager &LPM) override;

  void releaseMemory() override;

  void print(raw_ostream &OS, const Module * = nullptr) const override;

};

/// Analysis pass that exposes the \c IVUsers for a loop.

class IVUsersAnalysis : public AnalysisInfoMixin<IVUsersAnalysis> {

  friend AnalysisInfoMixin<IVUsersAnalysis>;

  static AnalysisKey Key;

public:

  typedef IVUsers Result;

  IVUsers run(Loop &L, LoopAnalysisManager &AM,

              LoopStandardAnalysisResults &AR);

};

}

#endif