PutByIdStatus.h 4.44 KB
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/*
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 * Copyright (C) 2012, 2013 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
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#ifndef PutByIdStatus_h
#define PutByIdStatus_h

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#include "IntendedStructureChain.h"
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#include "PropertyOffset.h"
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#include "StructureStubInfo.h"
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#include <wtf/text/StringImpl.h>
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namespace JSC {

class CodeBlock;
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class VM;
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class JSGlobalObject;
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class Structure;
class StructureChain;

class PutByIdStatus {
public:
    enum State {
        // It's uncached so we have no information.
        NoInformation,
        // It's cached as a direct store into an object property for cases where the object
        // already has the property.
        SimpleReplace,
        // It's cached as a transition from one structure that lacks the property to one that
        // includes the property, and a direct store to this new property.
        SimpleTransition,
        // It's known to often take slow path.
        TakesSlowPath
    };
    
    PutByIdStatus()
        : m_state(NoInformation)
        , m_oldStructure(0)
        , m_newStructure(0)
        , m_structureChain(0)
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        , m_offset(invalidOffset)
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    {
    }
    
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    explicit PutByIdStatus(State state)
        : m_state(state)
        , m_oldStructure(0)
        , m_newStructure(0)
        , m_structureChain(0)
        , m_offset(invalidOffset)
    {
        ASSERT(m_state == NoInformation || m_state == TakesSlowPath);
    }
    
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    PutByIdStatus(
        State state,
        Structure* oldStructure,
        Structure* newStructure,
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        PassRefPtr<IntendedStructureChain> structureChain,
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        PropertyOffset offset)
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        : m_state(state)
        , m_oldStructure(oldStructure)
        , m_newStructure(newStructure)
        , m_structureChain(structureChain)
        , m_offset(offset)
    {
        ASSERT((m_state == NoInformation || m_state == TakesSlowPath) == !m_oldStructure);
        ASSERT((m_state != SimpleTransition) == !m_newStructure);
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        ASSERT(!((m_state != SimpleTransition) && m_structureChain));
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        ASSERT((m_state == NoInformation || m_state == TakesSlowPath) == (m_offset == invalidOffset));
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    }
    
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    static PutByIdStatus computeFor(CodeBlock*, StubInfoMap&, unsigned bytecodeIndex, StringImpl* uid);
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    static PutByIdStatus computeFor(VM&, JSGlobalObject*, Structure*, StringImpl* uid, bool isDirect);
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    State state() const { return m_state; }
    
    bool isSet() const { return m_state != NoInformation; }
    bool operator!() const { return m_state == NoInformation; }
    bool isSimpleReplace() const { return m_state == SimpleReplace; }
    bool isSimpleTransition() const { return m_state == SimpleTransition; }
    bool takesSlowPath() const { return m_state == TakesSlowPath; }
    
    Structure* oldStructure() const { return m_oldStructure; }
    Structure* newStructure() const { return m_newStructure; }
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    IntendedStructureChain* structureChain() const { return m_structureChain.get(); }
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    PropertyOffset offset() const { return m_offset; }
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private:
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    static PutByIdStatus computeFromLLInt(CodeBlock*, unsigned bytecodeIndex, StringImpl* uid);
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    State m_state;
    Structure* m_oldStructure;
    Structure* m_newStructure;
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    RefPtr<IntendedStructureChain> m_structureChain;
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    PropertyOffset m_offset;
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};

} // namespace JSC

#endif // PutByIdStatus_h