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//===- PHITransAddr.h - PHI Translation for Addresses -----------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares the PHITransAddr class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_PHITRANSADDR_H
#define LLVM_ANALYSIS_PHITRANSADDR_H
#include "llvm/Instruction.h"
#include "llvm/ADT/SmallVector.h"
namespace llvm {
class DominatorTree;
class TargetData;
/// 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;
/// InstInputs - The inputs for our symbolic address.
SmallVector<Instruction*, 4> InstInputs;
public:
PHITransAddr(Value *addr) : Addr(addr) {
// If the address is an instruction, the whole thing is considered an input.
if (Instruction *I = dyn_cast<Instruction>(Addr))
InstInputs.push_back(I);
}
/// 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;
}
/// IsPHITranslatable - 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
/// GetPHITranslatedValue in hopeless situations.
bool IsPHITranslatable() const;
/// GetPHITranslatedValue - Given a computation that satisfied the
/// isPHITranslatable predicate, see if we can translate the computation into
/// the specified predecessor block. If so, return that value, otherwise
/// return null.
Value *GetPHITranslatedValue(Value *InVal, BasicBlock *CurBB,
BasicBlock *Pred, const TargetData *TD) const;
/// GetAvailablePHITranslatePointer - Return the value computed by
/// PHITranslatePointer if it dominates PredBB, otherwise return null.
Value *GetAvailablePHITranslatedValue(Value *V,
BasicBlock *CurBB, BasicBlock *PredBB,
const TargetData *TD,
const DominatorTree &DT) const;
/// InsertPHITranslatedPointer - 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 *InsertPHITranslatedPointer(Value *InVal, BasicBlock *CurBB,
BasicBlock *PredBB, const TargetData *TD,
const DominatorTree &DT,
SmallVectorImpl<Instruction*> &NewInsts) const;
};
} // end namespace llvm
#endif
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