Subversion Repositories QNX 8.QNX8 LLVM/Clang compiler suite

//===- PHITransAddr.h - PHI Translation for Addresses -----------*- 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 declares the PHITransAddr class.

//

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

#ifndef LLVM_ANALYSIS_PHITRANSADDR_H

#define LLVM_ANALYSIS_PHITRANSADDR_H

#include "llvm/ADT/SmallVector.h"

#include "llvm/IR/Instruction.h"

namespace llvm {

  class AssumptionCache;

  class DominatorTree;

  class DataLayout;

  class TargetLibraryInfo;

/// PHITransAddr - An address value which tracks and handles phi translation.

/// As we walk "up" the CFG through predecessors, we need to ensure that the

/// address we're tracking is kept up to date.  For example, if we're analyzing

/// an address of "&A[i]" and walk through the definition of 'i' which is a PHI

/// node, we *must* phi translate i to get "&A[j]" or else we will analyze an

/// incorrect pointer in the predecessor block.

///

/// This is designed to be a relatively small object that lives on the stack and

/// is copyable.

///

class PHITransAddr {

  /// Addr - The actual address we're analyzing.

  Value *Addr;

  /// The DataLayout we are playing with.

  const DataLayout &DL;

  /// TLI - The target library info if known, otherwise null.

  const TargetLibraryInfo *TLI = nullptr;

  /// A cache of \@llvm.assume calls used by SimplifyInstruction.

  AssumptionCache *AC;

  /// InstInputs - The inputs for our symbolic address.

  SmallVector<Instruction*, 4> InstInputs;

public:

  PHITransAddr(Value *addr, const DataLayout &DL, AssumptionCache *AC)

      : Addr(addr), DL(DL), AC(AC) {

    // If the address is an instruction, the whole thing is considered an input.

    if (Instruction *I = dyn_cast<Instruction>(Addr))

      InstInputs.push_back(I);

  }

  Value *getAddr() const { return Addr; }

  /// NeedsPHITranslationFromBlock - Return true if moving from the specified

  /// BasicBlock to its predecessors requires PHI translation.

  bool NeedsPHITranslationFromBlock(BasicBlock *BB) const {

    // We do need translation if one of our input instructions is defined in

    // this block.

    for (unsigned i = 0, e = InstInputs.size(); i != e; ++i)

      if (InstInputs[i]->getParent() == BB)

        return true;

    return false;

  }

  /// IsPotentiallyPHITranslatable - If this needs PHI translation, return true

  /// if we have some hope of doing it.  This should be used as a filter to

  /// avoid calling PHITranslateValue in hopeless situations.

  bool IsPotentiallyPHITranslatable() const;

  /// PHITranslateValue - PHI translate the current address up the CFG from

  /// CurBB to Pred, updating our state to reflect any needed changes.  If

  /// 'MustDominate' is true, the translated value must dominate

  /// PredBB.  This returns true on failure and sets Addr to null.

  bool PHITranslateValue(BasicBlock *CurBB, BasicBlock *PredBB,

                         const DominatorTree *DT, bool MustDominate);

  /// PHITranslateWithInsertion - PHI translate this value into the specified

  /// predecessor block, inserting a computation of the value if it is

  /// unavailable.

  ///

  /// All newly created instructions are added to the NewInsts list.  This

  /// returns null on failure.

  ///

  Value *PHITranslateWithInsertion(BasicBlock *CurBB, BasicBlock *PredBB,

                                   const DominatorTree &DT,

                                   SmallVectorImpl<Instruction *> &NewInsts);

  void dump() const;

  /// Verify - Check internal consistency of this data structure.  If the

  /// structure is valid, it returns true.  If invalid, it prints errors and

  /// returns false.

  bool Verify() const;

private:

  Value *PHITranslateSubExpr(Value *V, BasicBlock *CurBB, BasicBlock *PredBB,

                             const DominatorTree *DT);

  /// InsertPHITranslatedSubExpr - Insert a computation of the PHI translated

  /// version of 'V' for the edge PredBB->CurBB into the end of the PredBB

  /// block.  All newly created instructions are added to the NewInsts list.

  /// This returns null on failure.

  ///

  Value *InsertPHITranslatedSubExpr(Value *InVal, BasicBlock *CurBB,

                                    BasicBlock *PredBB, const DominatorTree &DT,

                                    SmallVectorImpl<Instruction *> &NewInsts);

  /// AddAsInput - If the specified value is an instruction, add it as an input.

  Value *AddAsInput(Value *V) {

    // If V is an instruction, it is now an input.

    if (Instruction *VI = dyn_cast<Instruction>(V))

      InstInputs.push_back(VI);

    return V;

  }

};

} // end namespace llvm

#endif