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/*
* Copyright (C) 2017-2019 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.
*/
#include "config.h"
#include "PolyProtoAccessChain.h"
#include "CacheableIdentifierInlines.h"
#include "JSCInlines.h"
namespace JSC {
RefPtr<PolyProtoAccessChain> PolyProtoAccessChain::tryCreate(JSGlobalObject* globalObject, JSCell* base, CacheableIdentifier propertyName, const PropertySlot& slot)
{
JSObject* target = slot.isUnset() ? nullptr : slot.slotBase();
return tryCreate(globalObject, base, propertyName, target);
}
RefPtr<PolyProtoAccessChain> PolyProtoAccessChain::tryCreate(JSGlobalObject* globalObject, JSCell* base, CacheableIdentifier propertyName, JSObject* target)
{
JSCell* current = base;
bool found = false;
Vector<StructureID> chain;
for (unsigned iterationNumber = 0; true; ++iterationNumber) {
Structure* structure = current->structure();
if (structure->isDictionary())
return nullptr;
if (!structure->propertyAccessesAreCacheable())
return nullptr;
if (structure->isProxy())
return nullptr;
// To save memory, we don't include the base in the chain. We let
// AccessCase provide the base to us as needed.
if (iterationNumber)
chain.append(structure->id());
else
RELEASE_ASSERT(current == base);
if (current == target) {
found = true;
break;
}
// TypedArray has an ability to stop [[Prototype]] traversing for numeric index string (e.g. "0.1").
// If we found it, then traverse should stop for Unset case.
// https://262.ecma-international.org/9.0/#_ref_2826
if (!target && isTypedArrayType(structure->typeInfo().type()) && isCanonicalNumericIndexString(propertyName.uid())) {
found = true;
break;
}
JSValue prototype = structure->prototypeForLookup(globalObject, current);
if (prototype.isNull())
break;
current = asObject(prototype);
}
if (!found && !!target)
return nullptr;
return adoptRef(*new PolyProtoAccessChain(WTFMove(chain)));
}
bool PolyProtoAccessChain::needImpurePropertyWatchpoint(VM&) const
{
for (StructureID structureID : m_chain) {
if (structureID.decode()->needImpurePropertyWatchpoint())
return true;
}
return false;
}
bool PolyProtoAccessChain::operator==(const PolyProtoAccessChain& other) const
{
return m_chain == other.m_chain;
}
void PolyProtoAccessChain::dump(Structure* baseStructure, PrintStream& out) const
{
out.print("PolyPolyProtoAccessChain: [\n");
forEach(baseStructure->vm(), baseStructure, [&] (Structure* structure, bool) {
out.print("\t");
structure->dump(out);
out.print("\n");
});
}
}
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