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72 lines
2.8 KiB
C++
72 lines
2.8 KiB
C++
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//===- PHITransAddr.cpp - PHI Translation for Addresses -------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the PHITransAddr class.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/PHITransAddr.h"
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#include "llvm/Analysis/Dominators.h"
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using namespace llvm;
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/// IsPHITranslatable - If this needs PHI translation, return true if we have
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/// some hope of doing it. This should be used as a filter to avoid calling
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/// GetPHITranslatedValue in hopeless situations.
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bool PHITransAddr::IsPHITranslatable() const {
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return true; // not a good filter.
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}
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/// GetPHITranslatedValue - Given a computation that satisfied the
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/// isPHITranslatable predicate, see if we can translate the computation into
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/// the specified predecessor block. If so, return that value, otherwise
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/// return null.
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Value *PHITransAddr::GetPHITranslatedValue(Value *InVal, BasicBlock *CurBB,
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BasicBlock *Pred,
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const TargetData *TD) const {
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// Not a great implementation.
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return 0;
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}
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/// GetAvailablePHITranslatePointer - Return the value computed by
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/// PHITranslatePointer if it dominates PredBB, otherwise return null.
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Value *PHITransAddr::
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GetAvailablePHITranslatedValue(Value *V,
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BasicBlock *CurBB, BasicBlock *PredBB,
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const TargetData *TD,
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const DominatorTree &DT) const {
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// See if PHI translation succeeds.
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V = GetPHITranslatedValue(V, CurBB, PredBB, TD);
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if (V == 0) return 0;
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// Make sure the value is live in the predecessor.
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if (Instruction *Inst = dyn_cast_or_null<Instruction>(V))
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if (!DT.dominates(Inst->getParent(), PredBB))
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return 0;
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return V;
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}
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/// InsertPHITranslatedPointer - Insert a computation of the PHI translated
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/// version of 'V' for the edge PredBB->CurBB into the end of the PredBB
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/// block. All newly created instructions are added to the NewInsts list.
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/// This returns null on failure.
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///
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Value *PHITransAddr::
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InsertPHITranslatedPointer(Value *InVal, BasicBlock *CurBB,
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BasicBlock *PredBB, const TargetData *TD,
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const DominatorTree &DT,
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SmallVectorImpl<Instruction*> &NewInsts) const {
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// See if we have a version of this value already available and dominating
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// PredBB. If so, there is no need to insert a new copy.
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if (Value *Res = GetAvailablePHITranslatedValue(InVal, CurBB, PredBB, TD, DT))
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return Res;
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// Not a great implementation.
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return 0;
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}
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