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//===- PHITransAddr.cpp - PHI Translation for Addresses -------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the PHITransAddr class.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/PHITransAddr.h"
#include "llvm/Analysis/Dominators.h"
using namespace llvm;
/// 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 PHITransAddr::IsPHITranslatable() const {
return true; // not a good filter.
}
/// 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 *PHITransAddr::GetPHITranslatedValue(Value *InVal, BasicBlock *CurBB,
BasicBlock *Pred,
const TargetData *TD) const {
// Not a great implementation.
return 0;
}
/// GetAvailablePHITranslatePointer - Return the value computed by
/// PHITranslatePointer if it dominates PredBB, otherwise return null.
Value *PHITransAddr::
GetAvailablePHITranslatedValue(Value *V,
BasicBlock *CurBB, BasicBlock *PredBB,
const TargetData *TD,
const DominatorTree &DT) const {
// See if PHI translation succeeds.
V = GetPHITranslatedValue(V, CurBB, PredBB, TD);
if (V == 0) return 0;
// Make sure the value is live in the predecessor.
if (Instruction *Inst = dyn_cast_or_null<Instruction>(V))
if (!DT.dominates(Inst->getParent(), PredBB))
return 0;
return V;
}
/// 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 *PHITransAddr::
InsertPHITranslatedPointer(Value *InVal, BasicBlock *CurBB,
BasicBlock *PredBB, const TargetData *TD,
const DominatorTree &DT,
SmallVectorImpl<Instruction*> &NewInsts) const {
// See if we have a version of this value already available and dominating
// PredBB. If so, there is no need to insert a new copy.
if (Value *Res = GetAvailablePHITranslatedValue(InVal, CurBB, PredBB, TD, DT))
return Res;
// Not a great implementation.
return 0;
}
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