Source/JavaScriptCore/bytecode/GetByIdVariant.cpp

/*
 * Copyright (C) 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
 * 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. 
 */

#include "config.h"
#include "GetByIdVariant.h"

#include "CallLinkStatus.h"
#include "JSCInlines.h"
#include <wtf/ListDump.h>

namespace JSC {

GetByIdVariant::GetByIdVariant(
    const StructureSet& structureSet, PropertyOffset offset,
    const IntendedStructureChain* chain, std::unique_ptr<CallLinkStatus> callLinkStatus)
    : m_structureSet(structureSet)
    , m_alternateBase(nullptr)
    , m_offset(offset)
    , m_callLinkStatus(WTF::move(callLinkStatus))
{
    if (!structureSet.size()) {
        ASSERT(offset == invalidOffset);
        ASSERT(!chain);
    }
    
    if (chain && chain->size()) {
        m_alternateBase = chain->terminalPrototype();
        chain->gatherChecks(m_constantChecks);
    }
}

GetByIdVariant::~GetByIdVariant() { }

GetByIdVariant::GetByIdVariant(const GetByIdVariant& other)
    : GetByIdVariant()
{
    *this = other;
}

GetByIdVariant& GetByIdVariant::operator=(const GetByIdVariant& other)
{
    m_structureSet = other.m_structureSet;
    m_constantChecks = other.m_constantChecks;
    m_alternateBase = other.m_alternateBase;
    m_offset = other.m_offset;
    if (other.m_callLinkStatus)
        m_callLinkStatus = std::make_unique<CallLinkStatus>(*other.m_callLinkStatus);
    else
        m_callLinkStatus = nullptr;
    return *this;
}

StructureSet GetByIdVariant::baseStructure() const
{
    if (!m_alternateBase)
        return structureSet();
    
    Structure* structure = structureFor(m_constantChecks, m_alternateBase);
    RELEASE_ASSERT(structure);
    return structure;
}

bool GetByIdVariant::attemptToMerge(const GetByIdVariant& other)
{
    if (m_alternateBase != other.m_alternateBase)
        return false;
    if (m_offset != other.m_offset)
        return false;
    if (m_callLinkStatus || other.m_callLinkStatus)
        return false;
    if (!areCompatible(m_constantChecks, other.m_constantChecks))
        return false;
    
    mergeInto(other.m_constantChecks, m_constantChecks);
    m_structureSet.merge(other.m_structureSet);
    
    return true;
}

void GetByIdVariant::dump(PrintStream& out) const
{
    dumpInContext(out, 0);
}

void GetByIdVariant::dumpInContext(PrintStream& out, DumpContext* context) const
{
    if (!isSet()) {
        out.print("<empty>");
        return;
    }
    
    out.print(
        "<", inContext(structureSet(), context), ", ",
        "[", listDumpInContext(m_constantChecks, context), "]");
    if (m_alternateBase)
        out.print(", alternateBase = ", inContext(JSValue(m_alternateBase), context));
    out.print(", offset = ", offset());
    if (m_callLinkStatus)
        out.print(", call = ", *m_callLinkStatus);
    out.print(">");
}

} // namespace JSC