Source/JavaScriptCore/bytecode/BytecodeLivenessAnalysis.h

/*
 * Copyright (C) 2013, 2015 Apple Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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#pragma once

#include "BytecodeBasicBlock.h"
#include "BytecodeGraph.h"
#include "CodeBlock.h"
#include <wtf/FastBitVector.h>

namespace JSC {

class BytecodeKills;
class FullBytecodeLiveness;

class BytecodeLivenessPropagation {
protected:
    template<typename CodeBlockType, typename UseFunctor, typename DefFunctor> void stepOverInstruction(CodeBlockType*, const InstructionStream&, BytecodeGraph&, InstructionStream::Offset bytecodeOffset, const UseFunctor&, const DefFunctor&);

    template<typename CodeBlockType> void stepOverInstruction(CodeBlockType*, const InstructionStream&, BytecodeGraph&, InstructionStream::Offset bytecodeOffset, FastBitVector& out);

    template<typename CodeBlockType, typename Instructions> bool computeLocalLivenessForBytecodeOffset(CodeBlockType*, const Instructions&, BytecodeGraph&, BytecodeBasicBlock*, unsigned targetOffset, FastBitVector& result);

    template<typename CodeBlockType, typename Instructions> bool computeLocalLivenessForBlock(CodeBlockType*, const Instructions&, BytecodeGraph&, BytecodeBasicBlock*);

    template<typename CodeBlockType, typename Instructions> FastBitVector getLivenessInfoAtBytecodeOffset(CodeBlockType*, const Instructions&, BytecodeGraph&, unsigned bytecodeOffset);

    template<typename CodeBlockType, typename Instructions> void runLivenessFixpoint(CodeBlockType*, const Instructions&, BytecodeGraph&);
};

class BytecodeLivenessAnalysis : private BytecodeLivenessPropagation {
    WTF_MAKE_FAST_ALLOCATED;
    WTF_MAKE_NONCOPYABLE(BytecodeLivenessAnalysis);
public:
    friend class BytecodeLivenessPropagation;
    BytecodeLivenessAnalysis(CodeBlock*);
    
    FastBitVector getLivenessInfoAtBytecodeOffset(CodeBlock*, unsigned bytecodeOffset);
    
    void computeFullLiveness(CodeBlock*, FullBytecodeLiveness& result);
    void computeKills(CodeBlock*, BytecodeKills& result);

private:
    void dumpResults(CodeBlock*);

    void getLivenessInfoAtBytecodeOffset(CodeBlock*, unsigned bytecodeOffset, FastBitVector&);

    BytecodeGraph m_graph;
};

inline bool operandIsAlwaysLive(int operand);
inline bool operandThatIsNotAlwaysLiveIsLive(const FastBitVector& out, int operand);
inline bool operandIsLive(const FastBitVector& out, int operand);
inline bool isValidRegisterForLiveness(int operand);

} // namespace JSC