Imported WebKit commit 2ea9d364d0f6efa8fa64acf19f451504c59be0e4 (http://svn.webkit.org/repository/webkit/trunk@104285)

1 files changed, 851 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/runtime/Structure.cpp b/Source/JavaScriptCore/runtime/Structure.cpp
new file mode 100644
index 000000000..dda8c73e9
--- /dev/null
+++ b/Source/JavaScriptCore/runtime/Structure.cpp
@@ -0,0 +1,851 @@
+/*
+ * Copyright (C) 2008, 2009 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 COMPUTER, 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 COMPUTER, 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 "Structure.h"
+
+#include "Identifier.h"
+#include "JSObject.h"
+#include "JSPropertyNameIterator.h"
+#include "Lookup.h"
+#include "PropertyNameArray.h"
+#include "StructureChain.h"
+#include <wtf/RefCountedLeakCounter.h>
+#include <wtf/RefPtr.h>
+#include <wtf/Threading.h>
+
+#define DUMP_STRUCTURE_ID_STATISTICS 0
+
+#ifndef NDEBUG
+#define DO_PROPERTYMAP_CONSTENCY_CHECK 0
+#else
+#define DO_PROPERTYMAP_CONSTENCY_CHECK 0
+#endif
+
+using namespace std;
+using namespace WTF;
+
+#if DUMP_PROPERTYMAP_STATS
+
+int numProbes;
+int numCollisions;
+int numRehashes;
+int numRemoves;
+
+#endif
+
+namespace JSC {
+
+#if DUMP_STRUCTURE_ID_STATISTICS
+static HashSet<Structure*>& liveStructureSet = *(new HashSet<Structure*>);
+#endif
+
+bool StructureTransitionTable::contains(StringImpl* rep, unsigned attributes) const
+{
+    if (isUsingSingleSlot()) {
+        Structure* transition = singleTransition();
+        return transition && transition->m_nameInPrevious == rep && transition->m_attributesInPrevious == attributes;
+    }
+    return map()->contains(make_pair(rep, attributes));
+}
+
+inline Structure* StructureTransitionTable::get(StringImpl* rep, unsigned attributes) const
+{
+    if (isUsingSingleSlot()) {
+        Structure* transition = singleTransition();
+        return (transition && transition->m_nameInPrevious == rep && transition->m_attributesInPrevious == attributes) ? transition : 0;
+    }
+    return map()->get(make_pair(rep, attributes));
+}
+
+inline void StructureTransitionTable::add(JSGlobalData& globalData, Structure* structure)
+{
+    if (isUsingSingleSlot()) {
+        Structure* existingTransition = singleTransition();
+
+        // This handles the first transition being added.
+        if (!existingTransition) {
+            setSingleTransition(globalData, structure);
+            return;
+        }
+
+        // This handles the second transition being added
+        // (or the first transition being despecified!)
+        setMap(new TransitionMap());
+        add(globalData, existingTransition);
+    }
+
+    // Add the structure to the map.
+
+    // Newer versions of the STL have an std::make_pair function that takes rvalue references.
+    // When either of the parameters are bitfields, the C++ compiler will try to bind them as lvalues, which is invalid. To work around this, use unary "+" to make the parameter an rvalue.
+    // See https://bugs.webkit.org/show_bug.cgi?id=59261 for more details
+    std::pair<TransitionMap::iterator, bool> result = map()->add(globalData, make_pair(structure->m_nameInPrevious, +structure->m_attributesInPrevious), structure);
+    if (!result.second) {
+        // There already is an entry! - we should only hit this when despecifying.
+        ASSERT(result.first.get().second->m_specificValueInPrevious);
+        ASSERT(!structure->m_specificValueInPrevious);
+        map()->set(result.first, structure);
+    }
+}
+
+void Structure::dumpStatistics()
+{
+#if DUMP_STRUCTURE_ID_STATISTICS
+    unsigned numberLeaf = 0;
+    unsigned numberUsingSingleSlot = 0;
+    unsigned numberSingletons = 0;
+    unsigned numberWithPropertyMaps = 0;
+    unsigned totalPropertyMapsSize = 0;
+
+    HashSet<Structure*>::const_iterator end = liveStructureSet.end();
+    for (HashSet<Structure*>::const_iterator it = liveStructureSet.begin(); it != end; ++it) {
+        Structure* structure = *it;
+
+        switch (structure->m_transitionTable.size()) {
+            case 0:
+                ++numberLeaf;
+               if (!structure->m_previous)
+                    ++numberSingletons;
+                break;
+
+            case 1:
+                ++numberUsingSingleSlot;
+                break;
+        }
+
+        if (structure->m_propertyTable) {
+            ++numberWithPropertyMaps;
+            totalPropertyMapsSize += structure->m_propertyTable->sizeInMemory();
+        }
+    }
+
+    printf("Number of live Structures: %d\n", liveStructureSet.size());
+    printf("Number of Structures using the single item optimization for transition map: %d\n", numberUsingSingleSlot);
+    printf("Number of Structures that are leaf nodes: %d\n", numberLeaf);
+    printf("Number of Structures that singletons: %d\n", numberSingletons);
+    printf("Number of Structures with PropertyMaps: %d\n", numberWithPropertyMaps);
+
+    printf("Size of a single Structures: %d\n", static_cast<unsigned>(sizeof(Structure)));
+    printf("Size of sum of all property maps: %d\n", totalPropertyMapsSize);
+    printf("Size of average of all property maps: %f\n", static_cast<double>(totalPropertyMapsSize) / static_cast<double>(liveStructureSet.size()));
+#else
+    printf("Dumping Structure statistics is not enabled.\n");
+#endif
+}
+
+Structure::Structure(JSGlobalData& globalData, JSGlobalObject* globalObject, JSValue prototype, const TypeInfo& typeInfo, const ClassInfo* classInfo)
+    : JSCell(globalData, globalData.structureStructure.get())
+    , m_typeInfo(typeInfo)
+    , m_globalObject(globalData, this, globalObject, WriteBarrier<JSGlobalObject>::MayBeNull)
+    , m_prototype(globalData, this, prototype)
+    , m_classInfo(classInfo)
+    , m_propertyStorageCapacity(typeInfo.isFinalObject() ? JSFinalObject_inlineStorageCapacity : JSNonFinalObject_inlineStorageCapacity)
+    , m_offset(noOffset)
+    , m_dictionaryKind(NoneDictionaryKind)
+    , m_isPinnedPropertyTable(false)
+    , m_hasGetterSetterProperties(false)
+    , m_hasNonEnumerableProperties(false)
+    , m_attributesInPrevious(0)
+    , m_specificFunctionThrashCount(0)
+    , m_preventExtensions(false)
+    , m_didTransition(false)
+    , m_staticFunctionReified(false)
+{
+}
+
+const ClassInfo Structure::s_info = { "Structure", 0, 0, 0, CREATE_METHOD_TABLE(Structure) };
+
+Structure::Structure(JSGlobalData& globalData)
+    : JSCell(CreatingEarlyCell)
+    , m_typeInfo(CompoundType, OverridesVisitChildren)
+    , m_prototype(globalData, this, jsNull())
+    , m_classInfo(&s_info)
+    , m_propertyStorageCapacity(0)
+    , m_offset(noOffset)
+    , m_dictionaryKind(NoneDictionaryKind)
+    , m_isPinnedPropertyTable(false)
+    , m_hasGetterSetterProperties(false)
+    , m_hasNonEnumerableProperties(false)
+    , m_attributesInPrevious(0)
+    , m_specificFunctionThrashCount(0)
+    , m_preventExtensions(false)
+    , m_didTransition(false)
+    , m_staticFunctionReified(false)
+{
+}
+
+Structure::Structure(JSGlobalData& globalData, const Structure* previous)
+    : JSCell(globalData, globalData.structureStructure.get())
+    , m_typeInfo(previous->typeInfo())
+    , m_prototype(globalData, this, previous->storedPrototype())
+    , m_classInfo(previous->m_classInfo)
+    , m_propertyStorageCapacity(previous->m_propertyStorageCapacity)
+    , m_offset(noOffset)
+    , m_dictionaryKind(previous->m_dictionaryKind)
+    , m_isPinnedPropertyTable(false)
+    , m_hasGetterSetterProperties(previous->m_hasGetterSetterProperties)
+    , m_hasNonEnumerableProperties(previous->m_hasNonEnumerableProperties)
+    , m_attributesInPrevious(0)
+    , m_specificFunctionThrashCount(previous->m_specificFunctionThrashCount)
+    , m_preventExtensions(previous->m_preventExtensions)
+    , m_didTransition(true)
+    , m_staticFunctionReified(previous->m_staticFunctionReified)
+{
+    if (previous->m_globalObject)
+        m_globalObject.set(globalData, this, previous->m_globalObject.get());
+}
+
+void Structure::destroy(JSCell* cell)
+{
+    jsCast<Structure*>(cell)->Structure::~Structure();
+}
+
+void Structure::materializePropertyMap(JSGlobalData& globalData)
+{
+    ASSERT(structure()->classInfo() == &s_info);
+    ASSERT(!m_propertyTable);
+
+    Vector<Structure*, 8> structures;
+    structures.append(this);
+
+    Structure* structure = this;
+
+    // Search for the last Structure with a property table.
+    while ((structure = structure->previousID())) {
+        if (structure->m_isPinnedPropertyTable) {
+            ASSERT(structure->m_propertyTable);
+            ASSERT(!structure->m_previous);
+
+            m_propertyTable = structure->m_propertyTable->copy(globalData, 0, m_offset + 1);
+            break;
+        }
+
+        structures.append(structure);
+    }
+
+    if (!m_propertyTable)
+        createPropertyMap(m_offset + 1);
+
+    for (ptrdiff_t i = structures.size() - 2; i >= 0; --i) {
+        structure = structures[i];
+        PropertyMapEntry entry(globalData, this, structure->m_nameInPrevious.get(), structure->m_offset, structure->m_attributesInPrevious, structure->m_specificValueInPrevious.get());
+        m_propertyTable->add(entry);
+    }
+}
+
+void Structure::growPropertyStorageCapacity()
+{
+    if (isUsingInlineStorage())
+        m_propertyStorageCapacity = JSObject::baseExternalStorageCapacity;
+    else
+        m_propertyStorageCapacity *= 2;
+}
+
+void Structure::despecifyDictionaryFunction(JSGlobalData& globalData, const Identifier& propertyName)
+{
+    StringImpl* rep = propertyName.impl();
+
+    materializePropertyMapIfNecessary(globalData);
+
+    ASSERT(isDictionary());
+    ASSERT(m_propertyTable);
+
+    PropertyMapEntry* entry = m_propertyTable->find(rep).first;
+    ASSERT(entry);
+    entry->specificValue.clear();
+}
+
+Structure* Structure::addPropertyTransitionToExistingStructure(Structure* structure, const Identifier& propertyName, unsigned attributes, JSCell* specificValue, size_t& offset)
+{
+    ASSERT(!structure->isDictionary());
+    ASSERT(structure->isObject());
+
+    if (Structure* existingTransition = structure->m_transitionTable.get(propertyName.impl(), attributes)) {
+        JSCell* specificValueInPrevious = existingTransition->m_specificValueInPrevious.get();
+        if (specificValueInPrevious && specificValueInPrevious != specificValue)
+            return 0;
+        ASSERT(existingTransition->m_offset != noOffset);
+        offset = existingTransition->m_offset;
+        return existingTransition;
+    }
+
+    return 0;
+}
+
+Structure* Structure::addPropertyTransition(JSGlobalData& globalData, Structure* structure, const Identifier& propertyName, unsigned attributes, JSCell* specificValue, size_t& offset)
+{
+    // If we have a specific function, we may have got to this point if there is
+    // already a transition with the correct property name and attributes, but
+    // specialized to a different function.  In this case we just want to give up
+    // and despecialize the transition.
+    // In this case we clear the value of specificFunction which will result
+    // in us adding a non-specific transition, and any subsequent lookup in
+    // Structure::addPropertyTransitionToExistingStructure will just use that.
+    if (specificValue && structure->m_transitionTable.contains(propertyName.impl(), attributes))
+        specificValue = 0;
+
+    ASSERT(!structure->isDictionary());
+    ASSERT(structure->isObject());
+    ASSERT(!Structure::addPropertyTransitionToExistingStructure(structure, propertyName, attributes, specificValue, offset));
+    
+    if (structure->m_specificFunctionThrashCount == maxSpecificFunctionThrashCount)
+        specificValue = 0;
+
+    if (structure->transitionCount() > s_maxTransitionLength) {
+        Structure* transition = toCacheableDictionaryTransition(globalData, structure);
+        ASSERT(structure != transition);
+        offset = transition->putSpecificValue(globalData, propertyName, attributes, specificValue);
+        if (transition->propertyStorageSize() > transition->propertyStorageCapacity())
+            transition->growPropertyStorageCapacity();
+        return transition;
+    }
+
+    Structure* transition = create(globalData, structure);
+
+    transition->m_cachedPrototypeChain.setMayBeNull(globalData, transition, structure->m_cachedPrototypeChain.get());
+    transition->m_previous.set(globalData, transition, structure);
+    transition->m_nameInPrevious = propertyName.impl();
+    transition->m_attributesInPrevious = attributes;
+    transition->m_specificValueInPrevious.setMayBeNull(globalData, transition, specificValue);
+
+    if (structure->m_propertyTable) {
+        if (structure->m_isPinnedPropertyTable)
+            transition->m_propertyTable = structure->m_propertyTable->copy(globalData, transition, structure->m_propertyTable->size() + 1);
+        else
+            transition->m_propertyTable = structure->m_propertyTable.release();
+    } else {
+        if (structure->m_previous)
+            transition->materializePropertyMap(globalData);
+        else
+            transition->createPropertyMap();
+    }
+
+    offset = transition->putSpecificValue(globalData, propertyName, attributes, specificValue);
+    if (transition->propertyStorageSize() > transition->propertyStorageCapacity())
+        transition->growPropertyStorageCapacity();
+
+    transition->m_offset = offset;
+    structure->m_transitionTable.add(globalData, transition);
+    return transition;
+}
+
+Structure* Structure::removePropertyTransition(JSGlobalData& globalData, Structure* structure, const Identifier& propertyName, size_t& offset)
+{
+    ASSERT(!structure->isUncacheableDictionary());
+
+    Structure* transition = toUncacheableDictionaryTransition(globalData, structure);
+
+    offset = transition->remove(propertyName);
+
+    return transition;
+}
+
+Structure* Structure::changePrototypeTransition(JSGlobalData& globalData, Structure* structure, JSValue prototype)
+{
+    Structure* transition = create(globalData, structure);
+
+    transition->m_prototype.set(globalData, transition, prototype);
+
+    // Don't set m_offset, as one can not transition to this.
+
+    structure->materializePropertyMapIfNecessary(globalData);
+    transition->m_propertyTable = structure->copyPropertyTableForPinning(globalData, transition);
+    transition->pin();
+
+    return transition;
+}
+
+Structure* Structure::despecifyFunctionTransition(JSGlobalData& globalData, Structure* structure, const Identifier& replaceFunction)
+{
+    ASSERT(structure->m_specificFunctionThrashCount < maxSpecificFunctionThrashCount);
+    Structure* transition = create(globalData, structure);
+
+    ++transition->m_specificFunctionThrashCount;
+
+    // Don't set m_offset, as one can not transition to this.
+
+    structure->materializePropertyMapIfNecessary(globalData);
+    transition->m_propertyTable = structure->copyPropertyTableForPinning(globalData, transition);
+    transition->pin();
+
+    if (transition->m_specificFunctionThrashCount == maxSpecificFunctionThrashCount)
+        transition->despecifyAllFunctions(globalData);
+    else {
+        bool removed = transition->despecifyFunction(globalData, replaceFunction);
+        ASSERT_UNUSED(removed, removed);
+    }
+
+    return transition;
+}
+
+Structure* Structure::getterSetterTransition(JSGlobalData& globalData, Structure* structure)
+{
+    Structure* transition = create(globalData, structure);
+
+    // Don't set m_offset, as one can not transition to this.
+
+    structure->materializePropertyMapIfNecessary(globalData);
+    transition->m_propertyTable = structure->copyPropertyTableForPinning(globalData, transition);
+    transition->pin();
+
+    return transition;
+}
+
+Structure* Structure::toDictionaryTransition(JSGlobalData& globalData, Structure* structure, DictionaryKind kind)
+{
+    ASSERT(!structure->isUncacheableDictionary());
+    
+    Structure* transition = create(globalData, structure);
+
+    structure->materializePropertyMapIfNecessary(globalData);
+    transition->m_propertyTable = structure->copyPropertyTableForPinning(globalData, transition);
+    transition->m_dictionaryKind = kind;
+    transition->pin();
+
+    return transition;
+}
+
+Structure* Structure::toCacheableDictionaryTransition(JSGlobalData& globalData, Structure* structure)
+{
+    return toDictionaryTransition(globalData, structure, CachedDictionaryKind);
+}
+
+Structure* Structure::toUncacheableDictionaryTransition(JSGlobalData& globalData, Structure* structure)
+{
+    return toDictionaryTransition(globalData, structure, UncachedDictionaryKind);
+}
+
+// In future we may want to cache this transition.
+Structure* Structure::sealTransition(JSGlobalData& globalData, Structure* structure)
+{
+    Structure* transition = preventExtensionsTransition(globalData, structure);
+
+    if (transition->m_propertyTable) {
+        PropertyTable::iterator end = transition->m_propertyTable->end();
+        for (PropertyTable::iterator iter = transition->m_propertyTable->begin(); iter != end; ++iter)
+            iter->attributes |= DontDelete;
+    }
+
+    return transition;
+}
+
+// In future we may want to cache this transition.
+Structure* Structure::freezeTransition(JSGlobalData& globalData, Structure* structure)
+{
+    Structure* transition = preventExtensionsTransition(globalData, structure);
+
+    if (transition->m_propertyTable) {
+        PropertyTable::iterator end = transition->m_propertyTable->end();
+        for (PropertyTable::iterator iter = transition->m_propertyTable->begin(); iter != end; ++iter)
+            iter->attributes |= (DontDelete | ReadOnly);
+    }
+
+    return transition;
+}
+
+// In future we may want to cache this transition.
+Structure* Structure::preventExtensionsTransition(JSGlobalData& globalData, Structure* structure)
+{
+    Structure* transition = create(globalData, structure);
+
+    // Don't set m_offset, as one can not transition to this.
+
+    structure->materializePropertyMapIfNecessary(globalData);
+    transition->m_propertyTable = structure->copyPropertyTableForPinning(globalData, transition);
+    transition->m_preventExtensions = true;
+    transition->pin();
+
+    return transition;
+}
+
+// In future we may want to cache this property.
+bool Structure::isSealed(JSGlobalData& globalData)
+{
+    if (isExtensible())
+        return false;
+
+    materializePropertyMapIfNecessary(globalData);
+    if (!m_propertyTable)
+        return true;
+
+    PropertyTable::iterator end = m_propertyTable->end();
+    for (PropertyTable::iterator iter = m_propertyTable->begin(); iter != end; ++iter) {
+        if ((iter->attributes & DontDelete) != DontDelete)
+            return false;
+    }
+    return true;
+}
+
+// In future we may want to cache this property.
+bool Structure::isFrozen(JSGlobalData& globalData)
+{
+    if (isExtensible())
+        return false;
+
+    materializePropertyMapIfNecessary(globalData);
+    if (!m_propertyTable)
+        return true;
+
+    PropertyTable::iterator end = m_propertyTable->end();
+    for (PropertyTable::iterator iter = m_propertyTable->begin(); iter != end; ++iter) {
+        if ((iter->attributes & (DontDelete | ReadOnly)) != (DontDelete | ReadOnly))
+            return false;
+    }
+    return true;
+}
+
+Structure* Structure::flattenDictionaryStructure(JSGlobalData& globalData, JSObject* object)
+{
+    ASSERT(isDictionary());
+    if (isUncacheableDictionary()) {
+        ASSERT(m_propertyTable);
+
+        size_t propertyCount = m_propertyTable->size();
+        Vector<JSValue> values(propertyCount);
+
+        unsigned i = 0;
+        PropertyTable::iterator end = m_propertyTable->end();
+        for (PropertyTable::iterator iter = m_propertyTable->begin(); iter != end; ++iter, ++i) {
+            values[i] = object->getDirectOffset(iter->offset);
+            // Update property table to have the new property offsets
+            iter->offset = i;
+        }
+        
+        // Copy the original property values into their final locations
+        for (unsigned i = 0; i < propertyCount; i++)
+            object->putDirectOffset(globalData, i, values[i]);
+
+        m_propertyTable->clearDeletedOffsets();
+    }
+
+    m_dictionaryKind = NoneDictionaryKind;
+    return this;
+}
+
+size_t Structure::addPropertyWithoutTransition(JSGlobalData& globalData, const Identifier& propertyName, unsigned attributes, JSCell* specificValue)
+{
+    ASSERT(!m_enumerationCache);
+
+    if (m_specificFunctionThrashCount == maxSpecificFunctionThrashCount)
+        specificValue = 0;
+
+    materializePropertyMapIfNecessaryForPinning(globalData);
+    
+    pin();
+
+    size_t offset = putSpecificValue(globalData, propertyName, attributes, specificValue);
+    if (propertyStorageSize() > propertyStorageCapacity())
+        growPropertyStorageCapacity();
+    return offset;
+}
+
+size_t Structure::removePropertyWithoutTransition(JSGlobalData& globalData, const Identifier& propertyName)
+{
+    ASSERT(isUncacheableDictionary());
+    ASSERT(!m_enumerationCache);
+
+    materializePropertyMapIfNecessaryForPinning(globalData);
+
+    pin();
+    size_t offset = remove(propertyName);
+    return offset;
+}
+
+void Structure::pin()
+{
+    ASSERT(m_propertyTable);
+    m_isPinnedPropertyTable = true;
+    m_previous.clear();
+    m_nameInPrevious.clear();
+}
+
+#if DUMP_PROPERTYMAP_STATS
+
+struct PropertyMapStatisticsExitLogger {
+    ~PropertyMapStatisticsExitLogger();
+};
+
+static PropertyMapStatisticsExitLogger logger;
+
+PropertyMapStatisticsExitLogger::~PropertyMapStatisticsExitLogger()
+{
+    printf("\nJSC::PropertyMap statistics\n\n");
+    printf("%d probes\n", numProbes);
+    printf("%d collisions (%.1f%%)\n", numCollisions, 100.0 * numCollisions / numProbes);
+    printf("%d rehashes\n", numRehashes);
+    printf("%d removes\n", numRemoves);
+}
+
+#endif
+
+#if !DO_PROPERTYMAP_CONSTENCY_CHECK
+
+inline void Structure::checkConsistency()
+{
+}
+
+#endif
+
+PassOwnPtr<PropertyTable> Structure::copyPropertyTable(JSGlobalData& globalData, Structure* owner)
+{
+    return adoptPtr(m_propertyTable ? new PropertyTable(globalData, owner, *m_propertyTable) : 0);
+}
+
+PassOwnPtr<PropertyTable> Structure::copyPropertyTableForPinning(JSGlobalData& globalData, Structure* owner)
+{
+    return adoptPtr(m_propertyTable ? new PropertyTable(globalData, owner, *m_propertyTable) : new PropertyTable(m_offset == noOffset ? 0 : m_offset));
+}
+
+size_t Structure::get(JSGlobalData& globalData, StringImpl* propertyName, unsigned& attributes, JSCell*& specificValue)
+{
+    materializePropertyMapIfNecessary(globalData);
+    if (!m_propertyTable)
+        return WTF::notFound;
+
+    PropertyMapEntry* entry = m_propertyTable->find(propertyName).first;
+    if (!entry)
+        return WTF::notFound;
+
+    attributes = entry->attributes;
+    specificValue = entry->specificValue.get();
+    return entry->offset;
+}
+
+bool Structure::despecifyFunction(JSGlobalData& globalData, const Identifier& propertyName)
+{
+    materializePropertyMapIfNecessary(globalData);
+    if (!m_propertyTable)
+        return false;
+
+    ASSERT(!propertyName.isNull());
+    PropertyMapEntry* entry = m_propertyTable->find(propertyName.impl()).first;
+    if (!entry)
+        return false;
+
+    ASSERT(entry->specificValue);
+    entry->specificValue.clear();
+    return true;
+}
+
+void Structure::despecifyAllFunctions(JSGlobalData& globalData)
+{
+    materializePropertyMapIfNecessary(globalData);
+    if (!m_propertyTable)
+        return;
+
+    PropertyTable::iterator end = m_propertyTable->end();
+    for (PropertyTable::iterator iter = m_propertyTable->begin(); iter != end; ++iter)
+        iter->specificValue.clear();
+}
+
+size_t Structure::putSpecificValue(JSGlobalData& globalData, const Identifier& propertyName, unsigned attributes, JSCell* specificValue)
+{
+    ASSERT(!propertyName.isNull());
+    ASSERT(get(globalData, propertyName) == notFound);
+
+    checkConsistency();
+    if (attributes & DontEnum)
+        m_hasNonEnumerableProperties = true;
+
+    StringImpl* rep = propertyName.impl();
+
+    if (!m_propertyTable)
+        createPropertyMap();
+
+    unsigned newOffset;
+
+    if (m_propertyTable->hasDeletedOffset())
+        newOffset = m_propertyTable->getDeletedOffset();
+    else
+        newOffset = m_propertyTable->size();
+
+    m_propertyTable->add(PropertyMapEntry(globalData, this, rep, newOffset, attributes, specificValue));
+
+    checkConsistency();
+    return newOffset;
+}
+
+size_t Structure::remove(const Identifier& propertyName)
+{
+    ASSERT(!propertyName.isNull());
+
+    checkConsistency();
+
+    StringImpl* rep = propertyName.impl();
+
+    if (!m_propertyTable)
+        return notFound;
+
+    PropertyTable::find_iterator position = m_propertyTable->find(rep);
+    if (!position.first)
+        return notFound;
+
+    size_t offset = position.first->offset;
+
+    m_propertyTable->remove(position);
+    m_propertyTable->addDeletedOffset(offset);
+
+    checkConsistency();
+    return offset;
+}
+
+void Structure::createPropertyMap(unsigned capacity)
+{
+    ASSERT(!m_propertyTable);
+
+    checkConsistency();
+    m_propertyTable = adoptPtr(new PropertyTable(capacity));
+    checkConsistency();
+}
+
+void Structure::getPropertyNamesFromStructure(JSGlobalData& globalData, PropertyNameArray& propertyNames, EnumerationMode mode)
+{
+    materializePropertyMapIfNecessary(globalData);
+    if (!m_propertyTable)
+        return;
+
+    bool knownUnique = !propertyNames.size();
+
+    PropertyTable::iterator end = m_propertyTable->end();
+    for (PropertyTable::iterator iter = m_propertyTable->begin(); iter != end; ++iter) {
+        ASSERT(m_hasNonEnumerableProperties || !(iter->attributes & DontEnum));
+        if (!(iter->attributes & DontEnum) || (mode == IncludeDontEnumProperties)) {
+            if (knownUnique)
+                propertyNames.addKnownUnique(iter->key);
+            else
+                propertyNames.add(iter->key);
+        }
+    }
+}
+
+void Structure::visitChildren(JSCell* cell, SlotVisitor& visitor)
+{
+    Structure* thisObject = jsCast<Structure*>(cell);
+    ASSERT_GC_OBJECT_INHERITS(thisObject, &s_info);
+    ASSERT(thisObject->structure()->typeInfo().overridesVisitChildren());
+    JSCell::visitChildren(thisObject, visitor);
+    if (thisObject->m_globalObject)
+        visitor.append(&thisObject->m_globalObject);
+    if (!thisObject->isObject())
+        thisObject->m_cachedPrototypeChain.clear();
+    else {
+        if (thisObject->m_prototype)
+            visitor.append(&thisObject->m_prototype);
+        if (thisObject->m_cachedPrototypeChain)
+            visitor.append(&thisObject->m_cachedPrototypeChain);
+    }
+    if (thisObject->m_previous)
+        visitor.append(&thisObject->m_previous);
+    if (thisObject->m_specificValueInPrevious)
+        visitor.append(&thisObject->m_specificValueInPrevious);
+    if (thisObject->m_enumerationCache)
+        visitor.append(&thisObject->m_enumerationCache);
+    if (thisObject->m_propertyTable) {
+        PropertyTable::iterator end = thisObject->m_propertyTable->end();
+        for (PropertyTable::iterator ptr = thisObject->m_propertyTable->begin(); ptr != end; ++ptr) {
+            if (ptr->specificValue)
+                visitor.append(&ptr->specificValue);
+        }
+    }
+}
+
+#if DO_PROPERTYMAP_CONSTENCY_CHECK
+
+void PropertyTable::checkConsistency()
+{
+    ASSERT(m_indexSize >= PropertyTable::MinimumTableSize);
+    ASSERT(m_indexMask);
+    ASSERT(m_indexSize == m_indexMask + 1);
+    ASSERT(!(m_indexSize & m_indexMask));
+
+    ASSERT(m_keyCount <= m_indexSize / 2);
+    ASSERT(m_keyCount + m_deletedCount <= m_indexSize / 2);
+    ASSERT(m_deletedCount <= m_indexSize / 4);
+
+    unsigned indexCount = 0;
+    unsigned deletedIndexCount = 0;
+    for (unsigned a = 0; a != m_indexSize; ++a) {
+        unsigned entryIndex = m_index[a];
+        if (entryIndex == PropertyTable::EmptyEntryIndex)
+            continue;
+        if (entryIndex == deletedEntryIndex()) {
+            ++deletedIndexCount;
+            continue;
+        }
+        ASSERT(entryIndex < deletedEntryIndex());
+        ASSERT(entryIndex - 1 <= usedCount());
+        ++indexCount;
+
+        for (unsigned b = a + 1; b != m_indexSize; ++b)
+            ASSERT(m_index[b] != entryIndex);
+    }
+    ASSERT(indexCount == m_keyCount);
+    ASSERT(deletedIndexCount == m_deletedCount);
+
+    ASSERT(!table()[deletedEntryIndex() - 1].key);
+
+    unsigned nonEmptyEntryCount = 0;
+    for (unsigned c = 0; c < usedCount(); ++c) {
+        StringImpl* rep = table()[c].key;
+        if (rep == PROPERTY_MAP_DELETED_ENTRY_KEY)
+            continue;
+        ++nonEmptyEntryCount;
+        unsigned i = rep->existingHash();
+        unsigned k = 0;
+        unsigned entryIndex;
+        while (1) {
+            entryIndex = m_index[i & m_indexMask];
+            ASSERT(entryIndex != PropertyTable::EmptyEntryIndex);
+            if (rep == table()[entryIndex - 1].key)
+                break;
+            if (k == 0)
+                k = 1 | doubleHash(rep->existingHash());
+            i += k;
+        }
+        ASSERT(entryIndex == c + 1);
+    }
+
+    ASSERT(nonEmptyEntryCount == m_keyCount);
+}
+
+void Structure::checkConsistency()
+{
+    if (!m_propertyTable)
+        return;
+
+    if (!m_hasNonEnumerableProperties) {
+        PropertyTable::iterator end = m_propertyTable->end();
+        for (PropertyTable::iterator iter = m_propertyTable->begin(); iter != end; ++iter) {
+            ASSERT(!(iter->attributes & DontEnum));
+        }
+    }
+
+    m_propertyTable->checkConsistency();
+}
+
+#endif // DO_PROPERTYMAP_CONSTENCY_CHECK
+
+} // namespace JSC