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/*
* Copyright (C) 2021 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. 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 INC. 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; 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.
*/
#pragma once
#include "ObjectConstructor.h"
namespace JSC {
ALWAYS_INLINE bool canPerformFastPropertyEnumerationForObjectAssign(Structure* structure)
{
if (structure->typeInfo().overridesGetOwnPropertySlot())
return false;
if (structure->typeInfo().overridesAnyFormOfGetOwnPropertyNames())
return false;
// FIXME: Indexed properties can be handled.
// https://bugs.webkit.org/show_bug.cgi?id=185358
if (hasIndexedProperties(structure->indexingType()))
return false;
if (structure->hasGetterSetterProperties())
return false;
if (structure->hasReadOnlyOrGetterSetterPropertiesExcludingProto())
return false;
if (structure->hasCustomGetterSetterProperties())
return false;
if (structure->isUncacheableDictionary())
return false;
// Cannot perform fast [[Put]] to |target| if the property names of the |source| contain "__proto__".
if (structure->hasUnderscoreProtoPropertyExcludingOriginalProto())
return false;
return true;
}
ALWAYS_INLINE bool canPerformFastPropertyEnumerationForJSONStringify(Structure* structure)
{
return canPerformFastPropertyEnumerationForObjectAssign(structure);
}
ALWAYS_INLINE void objectAssignFast(VM& vm, JSObject* target, JSObject* source, Vector<RefPtr<UniquedStringImpl>, 8>& properties, MarkedArgumentBuffer& values)
{
// |source| Structure does not have any getters. And target can perform fast put.
// So enumerating properties and putting properties are non observable.
// FIXME: It doesn't seem like we should have to do this in two phases, but
// we're running into crashes where it appears that source is transitioning
// under us, and even ends up in a state where it has a null butterfly. My
// leading hypothesis here is that we fire some value replacement watchpoint
// that ends up transitioning the structure underneath us.
// https://bugs.webkit.org/show_bug.cgi?id=187837
// FIXME: This fast path is very similar to ObjectConstructor' one. But extracting it to a function caused performance
// regression in object-assign-replace. Since the code is small and fast path, we keep both.
// Do not clear since Vector::clear shrinks the backing store.
properties.resize(0);
values.clear();
source->structure()->forEachProperty(vm, [&] (const PropertyTableEntry& entry) -> bool {
if (entry.attributes() & PropertyAttribute::DontEnum)
return true;
PropertyName propertyName(entry.key());
if (propertyName.isPrivateName())
return true;
properties.append(entry.key());
values.appendWithCrashOnOverflow(source->getDirect(entry.offset()));
return true;
});
for (size_t i = 0; i < properties.size(); ++i) {
// FIXME: We could put properties in a batching manner to accelerate Object.assign more.
// https://bugs.webkit.org/show_bug.cgi?id=185358
PutPropertySlot putPropertySlot(target, true);
target->putOwnDataProperty(vm, properties[i].get(), values.at(i), putPropertySlot);
}
}
} // namespace JSC
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