Source/JavaScriptCore/runtime/SymbolTable.cpp

/*
 * Copyright (C) 2012 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.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "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 OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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 */

#include "config.h"
#include "SymbolTable.h"

#include "JSDestructibleObject.h"
#include "Operations.h"
#include "SlotVisitorInlines.h"

namespace JSC {

const ClassInfo SymbolTable::s_info = { "SymbolTable", 0, 0, 0, CREATE_METHOD_TABLE(SymbolTable) };

SymbolTableEntry& SymbolTableEntry::copySlow(const SymbolTableEntry& other)
{
    ASSERT(other.isFat());
    FatEntry* newFatEntry = new FatEntry(*other.fatEntry());
    freeFatEntry();
    m_bits = bitwise_cast<intptr_t>(newFatEntry);
    return *this;
}

void SymbolTable::destroy(JSCell* cell)
{
    SymbolTable* thisObject = jsCast<SymbolTable*>(cell);
    thisObject->SymbolTable::~SymbolTable();
}

void SymbolTableEntry::freeFatEntrySlow()
{
    ASSERT(isFat());
    delete fatEntry();
}

JSValue SymbolTableEntry::inferredValue()
{
    if (!isFat())
        return JSValue();
    return fatEntry()->m_watchpoints->inferredValue();
}

void SymbolTableEntry::prepareToWatch()
{
    FatEntry* entry = inflate();
    if (entry->m_watchpoints)
        return;
    entry->m_watchpoints = adoptRef(new VariableWatchpointSet());
}

void SymbolTableEntry::addWatchpoint(Watchpoint* watchpoint)
{
    fatEntry()->m_watchpoints->add(watchpoint);
}

void SymbolTableEntry::notifyWriteSlow(JSValue value)
{
    VariableWatchpointSet* watchpoints = fatEntry()->m_watchpoints.get();
    if (!watchpoints)
        return;
    
    watchpoints->notifyWrite(value);
}

SymbolTableEntry::FatEntry* SymbolTableEntry::inflateSlow()
{
    FatEntry* entry = new FatEntry(m_bits);
    m_bits = bitwise_cast<intptr_t>(entry);
    return entry;
}

SymbolTable::SymbolTable(VM& vm)
    : JSCell(vm, vm.symbolTableStructure.get())
    , m_parameterCountIncludingThis(0)
    , m_usesNonStrictEval(false)
    , m_captureStart(0)
    , m_captureEnd(0)
    , m_functionEnteredOnce(ClearWatchpoint)
{
}

SymbolTable::~SymbolTable() { }

void SymbolTable::visitChildren(JSCell* thisCell, SlotVisitor& visitor)
{
    SymbolTable* thisSymbolTable = jsCast<SymbolTable*>(thisCell);
    if (!thisSymbolTable->m_watchpointCleanup) {
        thisSymbolTable->m_watchpointCleanup =
            std::make_unique<WatchpointCleanup>(thisSymbolTable);
    }
    
    visitor.addUnconditionalFinalizer(thisSymbolTable->m_watchpointCleanup.get());
}

SymbolTable::WatchpointCleanup::WatchpointCleanup(SymbolTable* symbolTable)
    : m_symbolTable(symbolTable)
{
}

SymbolTable::WatchpointCleanup::~WatchpointCleanup() { }

void SymbolTable::WatchpointCleanup::finalizeUnconditionally()
{
    Map::iterator iter = m_symbolTable->m_map.begin();
    Map::iterator end = m_symbolTable->m_map.end();
    for (; iter != end; ++iter) {
        if (VariableWatchpointSet* set = iter->value.watchpointSet())
            set->finalizeUnconditionally();
    }
}

SymbolTable* SymbolTable::cloneCapturedNames(VM& vm)
{
    SymbolTable* result = SymbolTable::create(vm);
    
    result->m_parameterCountIncludingThis = m_parameterCountIncludingThis;
    result->m_usesNonStrictEval = m_usesNonStrictEval;
    result->m_captureStart = m_captureStart;
    result->m_captureEnd = m_captureEnd;

    for (auto iter = m_map.begin(), end = m_map.end(); iter != end; ++iter) {
        if (!isCaptured(iter->value.getIndex()))
            continue;
        result->m_map.add(
            iter->key,
            SymbolTableEntry(iter->value.getIndex(), iter->value.getAttributes()));
    }
    
    if (m_slowArguments) {
        result->m_slowArguments = std::make_unique<SlowArgument[]>(parameterCount());
        for (unsigned i = parameterCount(); i--;)
            result->m_slowArguments[i] = m_slowArguments[i];
    }
    
    return result;
}

} // namespace JSC