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/*
* Copyright (C) 2016-2017 Apple Inc. All rights reserved.
* Copyright (C) 2017 Yusuke Suzuki <utatane.tea@gmail.com>.
*
* 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 "ExceptionHelpers.h"
#include "HashMapImpl.h"
#include "JSObject.h"
#include <wtf/JSValueMalloc.h>
#include <wtf/MallocPtr.h>
namespace JSC {
struct WeakMapBucketDataKey {
static const HashTableType Type = HashTableType::Key;
WriteBarrier<JSObject> key;
};
static_assert(sizeof(WeakMapBucketDataKey) == sizeof(void*), "");
struct WeakMapBucketDataKeyValue {
static const HashTableType Type = HashTableType::KeyValue;
WriteBarrier<JSObject> key;
#if USE(JSVALUE32_64)
uint32_t padding;
#endif
WriteBarrier<Unknown> value;
};
static_assert(sizeof(WeakMapBucketDataKeyValue) == 16, "");
ALWAYS_INLINE uint32_t jsWeakMapHash(JSObject* key)
{
return wangsInt64Hash(JSValue::encode(key));
}
ALWAYS_INLINE uint32_t nextCapacityAfterBatchRemoval(uint32_t capacity, uint32_t keyCount)
{
while (shouldShrink(capacity, keyCount))
capacity = nextCapacity(capacity, keyCount);
return capacity;
}
template <typename Data>
class WeakMapBucket {
public:
ALWAYS_INLINE void setKey(VM& vm, JSCell* owner, JSObject* key)
{
m_data.key.set(vm, owner, key);
}
template <typename T = Data>
ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucketDataKeyValue>::value>::type setValue(VM& vm, JSCell* owner, JSValue value)
{
m_data.value.set(vm, owner, value);
}
template <typename T = Data>
ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucketDataKey>::value>::type setValue(VM&, JSCell*, JSValue) { }
ALWAYS_INLINE JSObject* key() const { return m_data.key.get(); }
template <typename T = Data>
ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucketDataKeyValue>::value, JSValue>::type value() const
{
return m_data.value.get();
}
template <typename T = Data>
ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucketDataKey>::value, JSValue>::type value() const { return JSValue(); }
template <typename T = Data>
ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucketDataKeyValue>::value>::type copyFrom(const WeakMapBucket& from)
{
m_data.key.copyFrom(from.m_data.key);
m_data.value.setWithoutWriteBarrier(from.m_data.value.get());
}
template <typename T = Data>
ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucketDataKey>::value>::type copyFrom(const WeakMapBucket& from)
{
m_data.key.copyFrom(from.m_data.key);
}
static ptrdiff_t offsetOfKey()
{
return OBJECT_OFFSETOF(WeakMapBucket, m_data) + OBJECT_OFFSETOF(Data, key);
}
template <typename T = Data>
static typename std::enable_if<std::is_same<T, WeakMapBucketDataKeyValue>::value, ptrdiff_t>::type offsetOfValue()
{
return OBJECT_OFFSETOF(WeakMapBucket, m_data) + OBJECT_OFFSETOF(Data, value);
}
template <typename T = Data>
ALWAYS_INLINE static typename std::enable_if<std::is_same<T, WeakMapBucketDataKeyValue>::value, JSValue>::type extractValue(const WeakMapBucket& bucket)
{
return bucket.value();
}
template <typename T = Data>
ALWAYS_INLINE static typename std::enable_if<std::is_same<T, WeakMapBucketDataKey>::value, JSValue>::type extractValue(const WeakMapBucket&)
{
return JSValue();
}
bool isEmpty()
{
return !m_data.key.unvalidatedGet();
}
static JSObject* deletedKey()
{
return bitwise_cast<JSObject*>(static_cast<uintptr_t>(-3));
}
bool isDeleted()
{
return m_data.key.unvalidatedGet() == deletedKey();
}
void makeDeleted()
{
m_data.key.setWithoutWriteBarrier(deletedKey());
clearValue();
}
template <typename T = Data>
ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucketDataKeyValue>::value>::type visitAggregate(SlotVisitor& visitor)
{
visitor.append(m_data.value);
}
private:
template <typename T = Data>
ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucketDataKeyValue>::value>::type clearValue()
{
m_data.value.clear();
}
template <typename T = Data>
ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucketDataKey>::value>::type clearValue() { }
Data m_data;
};
template <typename BucketType>
class WeakMapBuffer {
public:
WeakMapBuffer() = delete;
static size_t allocationSize(Checked<size_t> capacity)
{
return (capacity * sizeof(BucketType)).unsafeGet();
}
ALWAYS_INLINE BucketType* buffer() const
{
return bitwise_cast<BucketType*>(this);
}
static MallocPtr<WeakMapBuffer, JSValueMalloc> create(uint32_t capacity)
{
size_t allocationSize = WeakMapBuffer::allocationSize(capacity);
auto buffer = MallocPtr<WeakMapBuffer, JSValueMalloc>::malloc(allocationSize);
buffer->reset(capacity);
return buffer;
}
ALWAYS_INLINE void reset(uint32_t capacity)
{
memset(this, 0, allocationSize(capacity));
}
};
template <typename WeakMapBucketType>
class WeakMapImpl : public JSNonFinalObject {
using Base = JSNonFinalObject;
using WeakMapBufferType = WeakMapBuffer<WeakMapBucketType>;
public:
using BucketType = WeakMapBucketType;
static constexpr bool needsDestruction = true;
static void destroy(JSCell*);
static void visitChildren(JSCell*, SlotVisitor&);
static size_t estimatedSize(JSCell*, VM&);
WeakMapImpl(VM& vm, Structure* structure)
: Base(vm, structure)
{
}
static constexpr uint32_t initialCapacity = 4;
void finishCreation(VM& vm)
{
ASSERT_WITH_MESSAGE(WeakMapBucket<WeakMapBucketDataKey>::offsetOfKey() == WeakMapBucket<WeakMapBucketDataKeyValue>::offsetOfKey(), "We assume this to be true in the DFG and FTL JIT.");
Base::finishCreation(vm);
auto locker = holdLock(cellLock());
makeAndSetNewBuffer(locker, initialCapacity);
}
// WeakMap operations must not cause GC. We model operations in DFG based on this guarantee.
// This guarantee is ensured by DisallowGC.
template <typename T = WeakMapBucketType>
ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucket<WeakMapBucketDataKeyValue>>::value, JSValue>::type get(JSObject* key)
{
DisallowGC disallowGC;
if (WeakMapBucketType* bucket = findBucket(key))
return bucket->value();
return jsUndefined();
}
ALWAYS_INLINE bool has(JSObject* key)
{
DisallowGC disallowGC;
return !!findBucket(key);
}
ALWAYS_INLINE void add(VM& vm, JSObject* key, JSValue value = JSValue())
{
DisallowGC disallowGC;
add(vm, key, value, jsWeakMapHash(key));
}
ALWAYS_INLINE void add(VM& vm, JSObject* key, JSValue value, uint32_t hash)
{
DisallowGC disallowGC;
ASSERT_WITH_MESSAGE(jsWeakMapHash(key) == hash, "We expect hash value is what we expect.");
addInternal(vm, key, value, hash);
if (shouldRehashAfterAdd())
rehash();
}
ALWAYS_INLINE bool remove(JSObject* key)
{
DisallowGC disallowGC;
WeakMapBucketType* bucket = findBucket(key);
if (!bucket)
return false;
bucket->makeDeleted();
++m_deleteCount;
RELEASE_ASSERT(m_keyCount > 0);
--m_keyCount;
if (shouldShrink())
rehash();
return true;
}
ALWAYS_INLINE uint32_t size() const
{
return m_keyCount;
}
void takeSnapshot(MarkedArgumentBuffer&, unsigned limit = 0);
static ptrdiff_t offsetOfBuffer()
{
return OBJECT_OFFSETOF(WeakMapImpl<WeakMapBucketType>, m_buffer);
}
static ptrdiff_t offsetOfCapacity()
{
return OBJECT_OFFSETOF(WeakMapImpl<WeakMapBucketType>, m_capacity);
}
static constexpr bool isWeakMap()
{
return std::is_same<WeakMapBucketType, JSC::WeakMapBucket<WeakMapBucketDataKeyValue>>::value;
}
static constexpr bool isWeakSet()
{
return std::is_same<WeakMapBucketType, JSC::WeakMapBucket<WeakMapBucketDataKey>>::value;
}
template<typename CellType, SubspaceAccess mode>
static IsoSubspace* subspaceFor(VM& vm)
{
if (isWeakMap())
return vm.weakMapSpace<mode>();
return vm.weakSetSpace<mode>();
}
static void visitOutputConstraints(JSCell*, SlotVisitor&);
void finalizeUnconditionally(VM&);
private:
ALWAYS_INLINE WeakMapBucketType* findBucket(JSObject* key)
{
return findBucket(key, jsWeakMapHash(key));
}
ALWAYS_INLINE WeakMapBucketType* findBucket(JSObject* key, uint32_t hash)
{
return findBucketAlreadyHashed(key, hash);
}
ALWAYS_INLINE WeakMapBucketType* buffer() const
{
return m_buffer->buffer();
}
enum class IterationState { Continue, Stop };
template<typename Functor>
void forEach(Functor functor)
{
auto* buffer = this->buffer();
for (uint32_t index = 0; index < m_capacity; ++index) {
auto* bucket = buffer + index;
if (bucket->isEmpty() || bucket->isDeleted())
continue;
if (functor(bucket->key(), bucket->value()) == IterationState::Stop)
return;
}
}
ALWAYS_INLINE uint32_t shouldRehashAfterAdd() const
{
return JSC::shouldRehashAfterAdd(m_capacity, m_keyCount, m_deleteCount);
}
ALWAYS_INLINE uint32_t shouldShrink() const
{
return JSC::shouldShrink(m_capacity, m_keyCount);
}
ALWAYS_INLINE static bool canUseBucket(WeakMapBucketType* bucket, JSObject* key)
{
return !bucket->isDeleted() && key == bucket->key();
}
ALWAYS_INLINE void addInternal(VM& vm, JSObject* key, JSValue value, uint32_t hash)
{
const uint32_t mask = m_capacity - 1;
uint32_t index = hash & mask;
WeakMapBucketType* buffer = this->buffer();
WeakMapBucketType* bucket = buffer + index;
while (!bucket->isEmpty()) {
if (canUseBucket(bucket, key)) {
ASSERT(!bucket->isDeleted());
bucket->setValue(vm, this, value);
return;
}
index = (index + 1) & mask;
bucket = buffer + index;
}
auto* newEntry = buffer + index;
newEntry->setKey(vm, this, key);
newEntry->setValue(vm, this, value);
++m_keyCount;
}
ALWAYS_INLINE WeakMapBucketType* findBucketAlreadyHashed(JSObject* key, uint32_t hash)
{
const uint32_t mask = m_capacity - 1;
uint32_t index = hash & mask;
WeakMapBucketType* buffer = this->buffer();
WeakMapBucketType* bucket = buffer + index;
while (!bucket->isEmpty()) {
if (canUseBucket(bucket, key)) {
ASSERT(!bucket->isDeleted());
return buffer + index;
}
index = (index + 1) & mask;
bucket = buffer + index;
}
return nullptr;
}
enum class RehashMode { Normal, RemoveBatching };
void rehash(RehashMode mode = RehashMode::Normal)
{
// Since shrinking is done just after GC runs (finalizeUnconditionally), WeakMapImpl::rehash()
// function must not touch any GC related features. This is why we do not allocate WeakMapBuffer
// in auxiliary buffer.
// This rehash modifies m_buffer which is not GC-managed buffer. But m_buffer can be touched in
// visitOutputConstraints. Thus, we should guard it with cellLock.
auto locker = holdLock(cellLock());
uint32_t oldCapacity = m_capacity;
MallocPtr<WeakMapBufferType, JSValueMalloc> oldBuffer = WTFMove(m_buffer);
uint32_t capacity = m_capacity;
if (mode == RehashMode::RemoveBatching) {
ASSERT(shouldShrink());
capacity = nextCapacityAfterBatchRemoval(capacity, m_keyCount);
} else
capacity = nextCapacity(capacity, m_keyCount);
makeAndSetNewBuffer(locker, capacity);
auto* buffer = this->buffer();
const uint32_t mask = m_capacity - 1;
for (uint32_t oldIndex = 0; oldIndex < oldCapacity; ++oldIndex) {
auto* entry = oldBuffer->buffer() + oldIndex;
if (entry->isEmpty() || entry->isDeleted())
continue;
uint32_t index = jsWeakMapHash(entry->key()) & mask;
WeakMapBucketType* bucket = buffer + index;
while (!bucket->isEmpty()) {
index = (index + 1) & mask;
bucket = buffer + index;
}
bucket->copyFrom(*entry);
}
m_deleteCount = 0;
checkConsistency();
}
ALWAYS_INLINE void checkConsistency() const
{
if (!ASSERT_DISABLED) {
uint32_t size = 0;
auto* buffer = this->buffer();
for (uint32_t index = 0; index < m_capacity; ++index) {
auto* bucket = buffer + index;
if (bucket->isEmpty() || bucket->isDeleted())
continue;
++size;
}
ASSERT(size == m_keyCount);
}
}
void makeAndSetNewBuffer(const AbstractLocker&, uint32_t capacity)
{
ASSERT(!(capacity & (capacity - 1)));
m_buffer = WeakMapBufferType::create(capacity);
m_capacity = capacity;
ASSERT(m_buffer);
assertBufferIsEmpty();
}
ALWAYS_INLINE void assertBufferIsEmpty() const
{
if (!ASSERT_DISABLED) {
for (unsigned i = 0; i < m_capacity; i++)
ASSERT((buffer() + i)->isEmpty());
}
}
template<typename Appender>
void takeSnapshotInternal(unsigned limit, Appender);
MallocPtr<WeakMapBufferType, JSValueMalloc> m_buffer;
uint32_t m_capacity { 0 };
uint32_t m_keyCount { 0 };
uint32_t m_deleteCount { 0 };
};
} // namespace JSC