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/*
* Copyright (C) 2013-2021 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.
*/
#include "config.h"
#include "DFGDesiredWeakReferences.h"
#if ENABLE(DFG_JIT)
#include "CodeBlock.h"
#include "DFGCommonData.h"
#include "JSCJSValueInlines.h"
#include "WriteBarrier.h"
namespace JSC { namespace DFG {
DesiredWeakReferences::DesiredWeakReferences() = default;
DesiredWeakReferences::~DesiredWeakReferences() = default;
void DesiredWeakReferences::addLazily(JSCell* cell)
{
if (cell) {
if (Structure* structure = jsDynamicCast<Structure*>(cell))
m_structures.add(structure->id());
else {
// There are weird relationships in how optimized CodeBlocks
// point to other CodeBlocks. We don't want to have them be
// part of the weak pointer set. For example, an optimized CodeBlock
// having a weak pointer to itself will cause it to get collected.
RELEASE_ASSERT(!jsDynamicCast<CodeBlock*>(cell));
m_cells.add(cell);
}
}
}
void DesiredWeakReferences::addLazily(JSValue value)
{
if (value.isCell())
addLazily(value.asCell());
}
bool DesiredWeakReferences::contains(JSCell* cell)
{
if (Structure* structure = jsDynamicCast<Structure*>(cell))
return m_structures.contains(structure->id());
return m_cells.contains(cell);
}
void DesiredWeakReferences::finalize()
{
m_finalizedCells = FixedVector<WriteBarrier<JSCell>>(m_cells.size());
{
unsigned index = 0;
for (JSCell* target : m_cells)
m_finalizedCells[index++].setWithoutWriteBarrier(target);
}
m_finalizedStructures = FixedVector<StructureID>(m_structures.size());
{
unsigned index = 0;
for (StructureID structureID : m_structures)
m_finalizedStructures[index++] = structureID;
}
}
void DesiredWeakReferences::reallyAdd(VM& vm, CommonData* common)
{
// We do not emit WriteBarrier here since (1) GC is deferred and (2) we emit write-barrier on CodeBlock when finishing DFG::Plan::reallyAdd.
ASSERT_UNUSED(vm, vm.heap.isDeferred());
if (!m_finalizedCells.isEmpty() || !m_finalizedStructures.isEmpty()) {
ASSERT(common->m_weakStructureReferences.isEmpty());
ASSERT(common->m_weakReferences.isEmpty());
// This is just moving a pointer. And we already synchronized with Lock etc. with compiler threads.
// So at this point, these vectors are fully constructed and baked by the compiler threads.
// We can just move these pointers to CommonData, and that's enough.
static_assert(sizeof(m_finalizedStructures) == sizeof(void*));
static_assert(sizeof(m_finalizedCells) == sizeof(void*));
common->m_weakStructureReferences = WTFMove(m_finalizedStructures);
common->m_weakReferences = WTFMove(m_finalizedCells);
}
}
template<typename Visitor>
void DesiredWeakReferences::visitChildren(Visitor& visitor)
{
for (JSCell* target : m_cells)
visitor.appendUnbarriered(target);
for (StructureID structureID : m_structures)
visitor.appendUnbarriered(structureID.decode());
}
template void DesiredWeakReferences::visitChildren(AbstractSlotVisitor&);
template void DesiredWeakReferences::visitChildren(SlotVisitor&);
} } // namespace JSC::DFG
#endif // ENABLE(DFG_JIT)
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