bb93c13d5b
HeapObjectPostWriteBarrier adds or removes a store buffer entry for a change in the GC graph entry based on the second and third arguments which are the target of the edge before and after the change. This patch also removes the store buffer entry in nsWrapperCache::ReleaseWrapper which didn't happen before. This should help keep less garbage alive unnecessarily. Differential Revision: https://phabricator.services.mozilla.com/D143736
138 lines
4.5 KiB
C++
138 lines
4.5 KiB
C++
/* -*- 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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#include "nsWrapperCacheInlines.h"
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#include "jsfriendapi.h"
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#include "js/Class.h"
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#include "js/Proxy.h"
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#include "mozilla/CycleCollectedJSRuntime.h"
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#include "mozilla/HoldDropJSObjects.h"
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#include "nsCycleCollectionTraversalCallback.h"
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#include "nsCycleCollector.h"
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using namespace mozilla;
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using namespace mozilla::dom;
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#ifdef DEBUG
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/* static */
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bool nsWrapperCache::HasJSObjectMovedOp(JSObject* aWrapper) {
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return js::HasObjectMovedOp(aWrapper);
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}
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#endif
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void nsWrapperCache::HoldJSObjects(void* aScriptObjectHolder,
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nsScriptObjectTracer* aTracer,
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JS::Zone* aWrapperZone) {
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cyclecollector::HoldJSObjectsImpl(aScriptObjectHolder, aTracer, aWrapperZone);
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if (mWrapper && !JS::ObjectIsTenured(mWrapper)) {
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JS::HeapObjectPostWriteBarrier(&mWrapper, nullptr, mWrapper);
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}
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}
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void nsWrapperCache::SetWrapperJSObject(JSObject* aWrapper) {
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mWrapper = aWrapper;
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UnsetWrapperFlags(kWrapperFlagsMask);
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if (aWrapper && !JS::ObjectIsTenured(aWrapper)) {
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CycleCollectedJSRuntime::Get()->NurseryWrapperAdded(this);
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}
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}
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void nsWrapperCache::ReleaseWrapper(void* aScriptObjectHolder) {
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// If the behavior here changes in a substantive way, you may need
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// to update css::Rule::UnlinkDeclarationWrapper as well.
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if (PreservingWrapper()) {
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SetPreservingWrapper(false);
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cyclecollector::DropJSObjectsImpl(aScriptObjectHolder);
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JS::HeapObjectPostWriteBarrier(&mWrapper, mWrapper, nullptr);
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}
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}
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#ifdef DEBUG
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void nsWrapperCache::AssertUpdatedWrapperZone(const JSObject* aNewObject,
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const JSObject* aOldObject) {
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MOZ_ASSERT(js::GetObjectZoneFromAnyThread(aNewObject) ==
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js::GetObjectZoneFromAnyThread(aOldObject));
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}
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class DebugWrapperTraversalCallback
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: public nsCycleCollectionTraversalCallback {
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public:
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explicit DebugWrapperTraversalCallback(JSObject* aWrapper)
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: mFound(false), mWrapper(JS::GCCellPtr(aWrapper)) {
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mFlags = WANT_ALL_TRACES;
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}
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NS_IMETHOD_(void)
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DescribeRefCountedNode(nsrefcnt aRefCount, const char* aObjName) override {}
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NS_IMETHOD_(void)
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DescribeGCedNode(bool aIsMarked, const char* aObjName,
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uint64_t aCompartmentAddress) override {}
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NS_IMETHOD_(void) NoteJSChild(JS::GCCellPtr aChild) override {
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if (aChild == mWrapper) {
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mFound = true;
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}
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}
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NS_IMETHOD_(void) NoteXPCOMChild(nsISupports* aChild) override {}
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NS_IMETHOD_(void)
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NoteNativeChild(void* aChild,
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nsCycleCollectionParticipant* aHelper) override {}
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NS_IMETHOD_(void) NoteNextEdgeName(const char* aName) override {}
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bool mFound;
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private:
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JS::GCCellPtr mWrapper;
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};
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static void DebugWrapperTraceCallback(JS::GCCellPtr aPtr, const char* aName,
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void* aClosure) {
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DebugWrapperTraversalCallback* callback =
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static_cast<DebugWrapperTraversalCallback*>(aClosure);
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if (aPtr.is<JSObject>()) {
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callback->NoteJSChild(aPtr);
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}
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}
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void nsWrapperCache::CheckCCWrapperTraversal(void* aScriptObjectHolder,
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nsScriptObjectTracer* aTracer) {
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JSObject* wrapper = GetWrapperPreserveColor();
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if (!wrapper) {
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return;
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}
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// Temporarily make this a preserving wrapper so that TraceWrapper() traces
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// it.
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bool wasPreservingWrapper = PreservingWrapper();
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SetPreservingWrapper(true);
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DebugWrapperTraversalCallback callback(wrapper);
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// The CC traversal machinery cannot trigger GC; however, the analysis cannot
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// see through the COM layer, so we use a suppression to help it.
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JS::AutoSuppressGCAnalysis suppress;
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aTracer->TraverseNativeAndJS(aScriptObjectHolder, callback);
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MOZ_ASSERT(callback.mFound,
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"Cycle collection participant didn't traverse to preserved "
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"wrapper! This will probably crash.");
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callback.mFound = false;
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aTracer->Trace(aScriptObjectHolder,
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TraceCallbackFunc(DebugWrapperTraceCallback), &callback);
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MOZ_ASSERT(callback.mFound,
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"Cycle collection participant didn't trace preserved wrapper! "
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"This will probably crash.");
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SetPreservingWrapper(wasPreservingWrapper);
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}
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#endif // DEBUG
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