mirror of
https://github.com/darlinghq/darling-JavaScriptCore.git
synced 2024-11-23 04:09:40 +00:00
131 lines
4.3 KiB
C++
131 lines
4.3 KiB
C++
/*
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* Copyright (C) 2014-2019 Apple Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#if ENABLE(DFG_JIT)
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#include "DFGValueStrength.h"
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#include "JSCJSValue.h"
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#include "JSCast.h"
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#include "Structure.h"
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namespace JSC { namespace DFG {
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class Graph;
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class FrozenValue {
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public:
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FrozenValue()
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: m_structure(nullptr)
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, m_strength(WeakValue)
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{
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}
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FrozenValue(JSValue value)
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: m_value(value)
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, m_structure(nullptr)
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, m_strength(WeakValue)
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{
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RELEASE_ASSERT(!value || !value.isCell());
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}
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FrozenValue(JSValue value, Structure* structure, ValueStrength strength)
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: m_value(value)
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, m_structure(structure)
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, m_strength(strength)
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{
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ASSERT((!!value && value.isCell()) == !!structure);
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ASSERT(!value || !value.isCell() || value.asCell()->classInfo(value.asCell()->vm()) == structure->classInfo());
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ASSERT(!!structure || (strength == WeakValue));
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}
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static FrozenValue* emptySingleton();
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bool operator!() const { return !m_value; }
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JSValue value() const { return m_value; }
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JSCell* cell() const { return m_value.asCell(); }
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template<typename T>
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T dynamicCast(VM& vm)
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{
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JSValue theValue = value();
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if (!theValue)
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return nullptr;
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return jsDynamicCast<T>(vm, theValue);
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}
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template<typename T>
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T cast()
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{
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return jsCast<T>(value());
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}
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Structure* structure() const { return m_structure; }
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void strengthenTo(ValueStrength strength)
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{
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if (!!m_value && m_value.isCell())
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m_strength = merge(m_strength, strength);
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}
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bool pointsToHeap() const { return !!value() && value().isCell(); }
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// The strength of the value itself. The structure is almost always weak.
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ValueStrength strength() const { return m_strength; }
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String tryGetString(Graph&);
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void dumpInContext(PrintStream& out, DumpContext* context) const;
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void dump(PrintStream& out) const;
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private:
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friend class Graph;
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// This is a utility method for DFG::Graph::freeze(). You should almost always call
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// Graph::freeze() directly. Calling this instead of Graph::freeze() can result in
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// the same constant being viewed as having different structures during the course
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// of compilation, which can sometimes cause bad things to happen. For example, we
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// may observe that one version of the constant has an unwatchable structure but
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// then a later version may start to have a watchable structure due to a transition.
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// The point of freezing is to ensure that we generally only see one version of
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// constants, but that requires freezing through the Graph.
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static FrozenValue freeze(JSValue value)
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{
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return FrozenValue(
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value,
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(!!value && value.isCell()) ? value.asCell()->structure() : nullptr,
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WeakValue);
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}
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JSValue m_value;
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Structure* m_structure;
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ValueStrength m_strength;
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};
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} } // namespace JSC::DFG
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#endif // ENABLE(DFG_JIT)
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