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100 lines
3.0 KiB
C++
100 lines
3.0 KiB
C++
//===- LiveValues.h - Liveness information for LLVM IR Values. ------------===//
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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 defines the interface for the LLVM IR Value liveness
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// analysis pass.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_LIVEVALUES_H
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#define LLVM_ANALYSIS_LIVEVALUES_H
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#include "llvm/Pass.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/SmallPtrSet.h"
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namespace llvm {
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class DominatorTree;
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class LoopInfo;
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class Value;
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/// LiveValues - Analysis that provides liveness information for
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/// LLVM IR Values.
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///
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class LiveValues : public FunctionPass {
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DominatorTree *DT;
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LoopInfo *LI;
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/// Memo - A bunch of state to be associated with a value.
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///
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struct Memo {
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/// Used - The set of blocks which contain a use of the value.
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///
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SmallPtrSet<const BasicBlock *, 4> Used;
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/// LiveThrough - A conservative approximation of the set of blocks in
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/// which the value is live-through, meaning blocks properly dominated
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/// by the definition, and from which blocks containing uses of the
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/// value are reachable.
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///
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SmallPtrSet<const BasicBlock *, 4> LiveThrough;
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/// Killed - A conservative approximation of the set of blocks in which
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/// the value is used and not live-out.
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///
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SmallPtrSet<const BasicBlock *, 4> Killed;
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};
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/// Memos - Remembers the Memo for each Value. This is populated on
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/// demand.
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///
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DenseMap<const Value *, Memo> Memos;
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/// getMemo - Retrieve an existing Memo for the given value if one
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/// is available, otherwise compute a new one.
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///
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Memo &getMemo(const Value *V);
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/// compute - Compute a new Memo for the given value.
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///
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Memo &compute(const Value *V);
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public:
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static char ID;
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LiveValues();
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virtual void getAnalysisUsage(AnalysisUsage &AU) const;
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virtual bool runOnFunction(Function &F);
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virtual void releaseMemory();
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/// isUsedInBlock - Test if the given value is used in the given block.
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///
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bool isUsedInBlock(const Value *V, const BasicBlock *BB);
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/// isLiveThroughBlock - Test if the given value is known to be
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/// live-through the given block, meaning that the block is properly
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/// dominated by the value's definition, and there exists a block
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/// reachable from it that contains a use. This uses a conservative
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/// approximation that errs on the side of returning false.
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///
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bool isLiveThroughBlock(const Value *V, const BasicBlock *BB);
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/// isKilledInBlock - Test if the given value is known to be killed in
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/// the given block, meaning that the block contains a use of the value,
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/// and no blocks reachable from the block contain a use. This uses a
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/// conservative approximation that errs on the side of returning false.
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///
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bool isKilledInBlock(const Value *V, const BasicBlock *BB);
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};
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} // end namespace llvm
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#endif
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