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/*
* Copyright (C) 2016-2022 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 "DeferTermination.h"
#include "Heap.h"
#include "VMTraps.h"
#include <wtf/StdLibExtras.h>
namespace JSC {
template<typename OwnerType, typename ElementType>
void LazyProperty<OwnerType, ElementType>::Initializer::set(ElementType* value) const
{
property.set(vm, owner, value);
}
template<typename OwnerType, typename ElementType>
template<typename Func>
void LazyProperty<OwnerType, ElementType>::initLater(const Func&)
{
RELEASE_ASSERT(isStatelessLambda<Func>());
// Logically we just want to stuff the function pointer into m_pointer, but then we'd be sad
// because a function pointer is not guaranteed to be a multiple of anything. The tag bits
// may be used for things. We address this problem by indirecting through a global const
// variable. The "theFunc" variable is guaranteed to be native-aligned, i.e. at least a
// multiple of 4.
static const FuncType theFunc = &callFunc<Func>;
m_pointer = lazyTag | bitwise_cast<uintptr_t>(&theFunc);
}
template<typename OwnerType, typename ElementType>
void LazyProperty<OwnerType, ElementType>::setMayBeNull(VM& vm, const OwnerType* owner, ElementType* value)
{
m_pointer = bitwise_cast<uintptr_t>(value);
RELEASE_ASSERT(!(m_pointer & lazyTag));
vm.writeBarrier(owner, value);
}
template<typename OwnerType, typename ElementType>
void LazyProperty<OwnerType, ElementType>::set(VM& vm, const OwnerType* owner, ElementType* value)
{
RELEASE_ASSERT(value);
setMayBeNull(vm, owner, value);
}
template<typename OwnerType, typename ElementType>
template<typename Visitor>
void LazyProperty<OwnerType, ElementType>::visit(Visitor& visitor)
{
if (m_pointer && !(m_pointer & lazyTag))
visitor.appendUnbarriered(bitwise_cast<ElementType*>(m_pointer));
}
template<typename OwnerType, typename ElementType>
void LazyProperty<OwnerType, ElementType>::dump(PrintStream& out) const
{
if (!m_pointer) {
out.print("<null>");
return;
}
if (m_pointer & lazyTag) {
out.print("Lazy:", RawHex(m_pointer & ~lazyTag));
if (m_pointer & initializingTag)
out.print("(Initializing)");
return;
}
out.print(RawHex(m_pointer));
}
template<typename OwnerType, typename ElementType>
template<typename Func>
ElementType* LazyProperty<OwnerType, ElementType>::callFunc(const Initializer& initializer)
{
if (initializer.property.m_pointer & initializingTag)
return nullptr;
DeferTerminationForAWhile deferTerminationForAWhile { initializer.vm };
initializer.property.m_pointer |= initializingTag;
callStatelessLambda<void, Func>(initializer);
RELEASE_ASSERT(!(initializer.property.m_pointer & lazyTag));
RELEASE_ASSERT(!(initializer.property.m_pointer & initializingTag));
return bitwise_cast<ElementType*>(initializer.property.m_pointer);
}
} // namespace JSC