mirror of
https://github.com/classilla/tenfourfox.git
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154 lines
4.6 KiB
C
154 lines
4.6 KiB
C
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef nsXBLMaybeCompiled_h__
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#define nsXBLMaybeCompiled_h__
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#include "js/GCAPI.h"
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/*
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* A union containing either a pointer representing uncompiled source or a
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* JSObject* representing the compiled result. The class is templated on the
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* source object type.
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*
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* The purpose of abstracting this as a separate class is to allow it to be
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* wrapped in a JS::Heap<T> to correctly handle post-barriering of the JSObject
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* pointer, when present.
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*
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* No implementation of rootKind() is provided, which prevents
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* Root<nsXBLMaybeCompiled<UncompiledT>> from being used.
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*/
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template <class UncompiledT>
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class nsXBLMaybeCompiled
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{
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public:
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nsXBLMaybeCompiled() : mUncompiled(BIT_UNCOMPILED) {}
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explicit nsXBLMaybeCompiled(UncompiledT* uncompiled)
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: mUncompiled(reinterpret_cast<uintptr_t>(uncompiled) | BIT_UNCOMPILED) {}
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explicit nsXBLMaybeCompiled(JSObject* compiled) : mCompiled(compiled) {}
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bool IsCompiled() const
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{
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return !(mUncompiled & BIT_UNCOMPILED);
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}
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UncompiledT* GetUncompiled() const
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{
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MOZ_ASSERT(!IsCompiled(), "Attempt to get compiled function as uncompiled");
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uintptr_t unmasked = mUncompiled & ~BIT_UNCOMPILED;
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return reinterpret_cast<UncompiledT*>(unmasked);
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}
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JSObject* GetJSFunction() const
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{
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MOZ_ASSERT(IsCompiled(), "Attempt to get uncompiled function as compiled");
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if (mCompiled) {
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JS::ExposeObjectToActiveJS(mCompiled);
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}
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return mCompiled;
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}
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// This is appropriate for use in tracing methods, etc.
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JSObject* GetJSFunctionPreserveColor() const
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{
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MOZ_ASSERT(IsCompiled(), "Attempt to get uncompiled function as compiled");
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return mCompiled;
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}
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private:
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JSObject*& UnsafeGetJSFunction()
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{
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MOZ_ASSERT(IsCompiled(), "Attempt to get uncompiled function as compiled");
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return mCompiled;
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}
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enum { BIT_UNCOMPILED = 1 << 0 };
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union
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{
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// An pointer that represents the function before being compiled, with
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// BIT_UNCOMPILED set.
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uintptr_t mUncompiled;
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// The JS object for the compiled result.
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JSObject* mCompiled;
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};
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friend struct js::GCMethods<nsXBLMaybeCompiled<UncompiledT>>;
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};
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/* Add support for JS::Heap<nsXBLMaybeCompiled>. */
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namespace js {
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template <class UncompiledT>
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struct GCMethods<nsXBLMaybeCompiled<UncompiledT> >
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{
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typedef struct GCMethods<JSObject *> Base;
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static nsXBLMaybeCompiled<UncompiledT> initial() { return nsXBLMaybeCompiled<UncompiledT>(); }
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static void postBarrier(nsXBLMaybeCompiled<UncompiledT>* functionp,
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nsXBLMaybeCompiled<UncompiledT> prev,
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nsXBLMaybeCompiled<UncompiledT> next)
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{
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if (next.IsCompiled()) {
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Base::postBarrier(&functionp->UnsafeGetJSFunction(),
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prev.IsCompiled() ? prev.UnsafeGetJSFunction() : nullptr,
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next.UnsafeGetJSFunction());
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} else if (prev.IsCompiled()) {
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Base::postBarrier(&prev.UnsafeGetJSFunction(),
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prev.UnsafeGetJSFunction(),
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nullptr);
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}
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}
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};
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template <class UncompiledT>
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class HeapBase<nsXBLMaybeCompiled<UncompiledT> >
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{
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const JS::Heap<nsXBLMaybeCompiled<UncompiledT> >& wrapper() const {
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return *static_cast<const JS::Heap<nsXBLMaybeCompiled<UncompiledT> >*>(this);
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}
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JS::Heap<nsXBLMaybeCompiled<UncompiledT> >& wrapper() {
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return *static_cast<JS::Heap<nsXBLMaybeCompiled<UncompiledT> >*>(this);
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}
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const nsXBLMaybeCompiled<UncompiledT>* extract() const {
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return wrapper().address();
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}
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nsXBLMaybeCompiled<UncompiledT>* extract() {
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return wrapper().unsafeGet();
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}
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public:
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bool IsCompiled() const { return extract()->IsCompiled(); }
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UncompiledT* GetUncompiled() const { return extract()->GetUncompiled(); }
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JSObject* GetJSFunction() const { return extract()->GetJSFunction(); }
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JSObject* GetJSFunctionPreserveColor() const { return extract()->GetJSFunctionPreserveColor(); }
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void SetUncompiled(UncompiledT* source) {
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wrapper() = nsXBLMaybeCompiled<UncompiledT>(source);
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}
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void SetJSFunction(JSObject* function) {
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wrapper() = nsXBLMaybeCompiled<UncompiledT>(function);
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}
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JS::Heap<JSObject*>& AsHeapObject()
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{
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MOZ_ASSERT(extract()->IsCompiled());
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return *reinterpret_cast<JS::Heap<JSObject*>*>(this);
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}
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};
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} /* namespace js */
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#endif // nsXBLMaybeCompiled_h__
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