Source/JavaScriptCore/bytecode/GetByIdStatus.h

/*
 * Copyright (C) 2012, 2013, 2014 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 * 1. Redistributions of source code must retain the above copyright
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#ifndef GetByIdStatus_h
#define GetByIdStatus_h

#include "CallLinkStatus.h"
#include "CodeOrigin.h"
#include "ConcurrentJITLock.h"
#include "ExitingJITType.h"
#include "GetByIdVariant.h"

namespace JSC {

class CodeBlock;
class StructureStubInfo;

typedef HashMap<CodeOrigin, StructureStubInfo*, CodeOriginApproximateHash> StubInfoMap;

class GetByIdStatus {
public:
    enum State {
        NoInformation,  // It's uncached so we have no information.
        Simple,         // It's cached for a simple access to a known object property with
                        // a possible structure chain and a possible specific value.
        TakesSlowPath,  // It's known to often take slow path.
        MakesCalls      // It's known to take paths that make calls.
    };

    GetByIdStatus()
        : m_state(NoInformation)
    {
    }
    
    explicit GetByIdStatus(State state)
        : m_state(state)
    {
        ASSERT(state == NoInformation || state == TakesSlowPath || state == MakesCalls);
    }
    
    GetByIdStatus(
        State state, bool wasSeenInJIT, const GetByIdVariant& variant = GetByIdVariant())
        : m_state(state)
        , m_wasSeenInJIT(wasSeenInJIT)
    {
        ASSERT((state == Simple) == variant.isSet());
        m_variants.append(variant);
    }
    
    static GetByIdStatus computeFor(CodeBlock*, StubInfoMap&, unsigned bytecodeIndex, UniquedStringImpl* uid);
    static GetByIdStatus computeFor(const StructureSet&, UniquedStringImpl* uid);
    
    static GetByIdStatus computeFor(CodeBlock* baselineBlock, CodeBlock* dfgBlock, StubInfoMap& baselineMap, StubInfoMap& dfgMap, CodeOrigin, UniquedStringImpl* uid);

#if ENABLE(DFG_JIT)
    static GetByIdStatus computeForStubInfo(const ConcurrentJITLocker&, CodeBlock* baselineBlock, StructureStubInfo*, CodeOrigin, UniquedStringImpl* uid);
#endif

    State state() const { return m_state; }
    
    bool isSet() const { return m_state != NoInformation; }
    bool operator!() const { return !isSet(); }
    bool isSimple() const { return m_state == Simple; }

    size_t numVariants() const { return m_variants.size(); }
    const Vector<GetByIdVariant, 1>& variants() const { return m_variants; }
    const GetByIdVariant& at(size_t index) const { return m_variants[index]; }
    const GetByIdVariant& operator[](size_t index) const { return at(index); }

    bool takesSlowPath() const { return m_state == TakesSlowPath || m_state == MakesCalls; }
    bool makesCalls() const;
    
    bool wasSeenInJIT() const { return m_wasSeenInJIT; }
    
    // Attempts to reduce the set of variants to fit the given structure set. This may be approximate.
    void filter(const StructureSet&);
    
    void dump(PrintStream&) const;
    
private:
#if ENABLE(DFG_JIT)
    static bool hasExitSite(const ConcurrentJITLocker&, CodeBlock*, unsigned bytecodeIndex);
#endif
#if ENABLE(JIT)
    static GetByIdStatus computeForStubInfoWithoutExitSiteFeedback(
        const ConcurrentJITLocker&, CodeBlock* profiledBlock, StructureStubInfo*,
        UniquedStringImpl* uid, CallLinkStatus::ExitSiteData);
#endif
    static GetByIdStatus computeFromLLInt(CodeBlock*, unsigned bytecodeIndex, UniquedStringImpl* uid);
    
    bool appendVariant(const GetByIdVariant&);
    
    State m_state;
    Vector<GetByIdVariant, 1> m_variants;
    bool m_wasSeenInJIT;
};

} // namespace JSC

#endif // PropertyAccessStatus_h