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/*
* Copyright (C) 2016 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.
*/
#pragma once
#include "JSObject.h"
#include "PropertySlot.h"
#include "Structure.h"
#include <wtf/UniqueRef.h>
WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN
namespace JSC {
DECLARE_ALLOCATOR_WITH_HEAP_IDENTIFIER(HasOwnPropertyCache);
class alignas(8) HasOwnPropertyCache {
static const uint32_t size = 2 * 1024;
static_assert(hasOneBitSet(size), "size should be a power of two.");
public:
static const uint32_t mask = size - 1;
struct Entry {
static constexpr ptrdiff_t offsetOfStructureID() { return OBJECT_OFFSETOF(Entry, structureID); }
static constexpr ptrdiff_t offsetOfImpl() { return OBJECT_OFFSETOF(Entry, impl); }
static constexpr ptrdiff_t offsetOfResult() { return OBJECT_OFFSETOF(Entry, result); }
RefPtr<UniquedStringImpl> impl;
StructureID structureID;
bool result { false };
};
HasOwnPropertyCache() = delete;
void operator delete(void* cache)
{
static_cast<HasOwnPropertyCache*>(cache)->clear();
HasOwnPropertyCacheMalloc::free(cache);
}
static UniqueRef<HasOwnPropertyCache> create()
{
size_t allocationSize = sizeof(Entry) * size;
HasOwnPropertyCache* result = static_cast<HasOwnPropertyCache*>(HasOwnPropertyCacheMalloc::malloc(allocationSize));
result->clearBuffer();
return UniqueRef { *result };
}
ALWAYS_INLINE static uint32_t hash(StructureID structureID, UniquedStringImpl* impl)
{
return std::bit_cast<uint32_t>(structureID) + impl->hash();
}
ALWAYS_INLINE std::optional<bool> get(Structure* structure, PropertyName propName)
{
UniquedStringImpl* impl = propName.uid();
StructureID id = structure->id();
uint32_t index = HasOwnPropertyCache::hash(id, impl) & mask;
Entry& entry = std::bit_cast<Entry*>(this)[index];
if (entry.structureID == id && entry.impl.get() == impl)
return entry.result;
return std::nullopt;
}
ALWAYS_INLINE void tryAdd(PropertySlot& slot, JSObject* object, PropertyName propName, bool result)
{
if (parseIndex(propName))
return;
if (!slot.isCacheable() && !slot.isUnset())
return;
if (object->type() == GlobalProxyType)
return;
Structure* structure = object->structure();
if (!structure->typeInfo().prohibitsPropertyCaching()
&& structure->propertyAccessesAreCacheable()
&& (!slot.isUnset() || structure->propertyAccessesAreCacheableForAbsence())) {
if (structure->isDictionary()) {
// FIXME: We should be able to flatten a dictionary object again.
// https://bugs.webkit.org/show_bug.cgi?id=163092
return;
}
ASSERT(!result == slot.isUnset());
UniquedStringImpl* impl = propName.uid();
StructureID id = structure->id();
uint32_t index = HasOwnPropertyCache::hash(id, impl) & mask;
std::bit_cast<Entry*>(this)[index] = Entry { RefPtr<UniquedStringImpl>(impl), id, result };
}
}
void clear()
{
Entry* buffer = std::bit_cast<Entry*>(this);
for (uint32_t i = 0; i < size; ++i)
buffer[i].Entry::~Entry();
clearBuffer();
}
private:
void clearBuffer()
{
Entry* buffer = std::bit_cast<Entry*>(this);
for (uint32_t i = 0; i < size; ++i)
new (&buffer[i]) Entry();
}
};
} // namespace JSC
WTF_ALLOW_UNSAFE_BUFFER_USAGE_END
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