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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#include "gc/StoreBuffer-inl.h"
#include "mozilla/Assertions.h"
#include "gc/Statistics.h"
#include "vm/MutexIDs.h"
#include "vm/Runtime.h"
using namespace js;
using namespace js::gc;
#ifdef DEBUG
void StoreBuffer::checkAccess() const {
// The GC runs tasks that may access the storebuffer in parallel and so must
// take a lock. The mutator may only access the storebuffer from the main
// thread.
if (runtime_->heapState() != JS::HeapState::Idle &&
runtime_->heapState() != JS::HeapState::MinorCollecting) {
MOZ_ASSERT(!CurrentThreadIsGCMarking());
runtime_->gc.assertCurrentThreadHasLockedStoreBuffer();
} else {
MOZ_ASSERT(CurrentThreadCanAccessRuntime(runtime_));
}
}
#endif
bool StoreBuffer::WholeCellBuffer::init() {
MOZ_ASSERT(!sweepHead_);
if (!storage_) {
storage_ = MakeUnique<LifoAlloc>(LifoAllocBlockSize, js::MallocArena);
if (!storage_) {
return false;
}
}
// This prevents LifoAlloc::Enum from crashing with a release
// assertion if we ever allocate one entry larger than
// LifoAllocBlockSize.
storage_->disableOversize();
clear();
return true;
}
bool StoreBuffer::GenericBuffer::init() {
if (!storage_) {
storage_ = MakeUnique<LifoAlloc>(LifoAllocBlockSize, js::MallocArena);
}
clear();
return bool(storage_);
}
void StoreBuffer::GenericBuffer::trace(JSTracer* trc, StoreBuffer* owner) {
mozilla::ReentrancyGuard g(*owner);
MOZ_ASSERT(owner->isEnabled());
if (!storage_) {
return;
}
for (LifoAlloc::Enum e(*storage_); !e.empty();) {
unsigned size = *e.read<unsigned>();
BufferableRef* edge = e.read<BufferableRef>(size);
edge->trace(trc);
}
}
StoreBuffer::StoreBuffer(JSRuntime* rt)
: runtime_(rt),
nursery_(rt->gc.nursery()),
aboutToOverflow_(false),
enabled_(false),
mayHavePointersToDeadCells_(false)
#ifdef DEBUG
,
mEntered(false)
#endif
{
}
StoreBuffer::StoreBuffer(StoreBuffer&& other)
: bufferVal(std::move(other.bufferVal)),
bufStrCell(std::move(other.bufStrCell)),
bufBigIntCell(std::move(other.bufBigIntCell)),
bufObjCell(std::move(other.bufObjCell)),
bufferSlot(std::move(other.bufferSlot)),
bufferWasmAnyRef(std::move(other.bufferWasmAnyRef)),
bufferWholeCell(std::move(other.bufferWholeCell)),
bufferGeneric(std::move(other.bufferGeneric)),
runtime_(other.runtime_),
nursery_(other.nursery_),
aboutToOverflow_(other.aboutToOverflow_),
enabled_(other.enabled_),
mayHavePointersToDeadCells_(other.mayHavePointersToDeadCells_)
#ifdef DEBUG
,
mEntered(other.mEntered)
#endif
{
MOZ_ASSERT(enabled_);
MOZ_ASSERT(!mEntered);
other.disable();
}
StoreBuffer& StoreBuffer::operator=(StoreBuffer&& other) {
if (&other != this) {
this->~StoreBuffer();
new (this) StoreBuffer(std::move(other));
}
return *this;
}
void StoreBuffer::checkEmpty() const { MOZ_ASSERT(isEmpty()); }
bool StoreBuffer::isEmpty() const {
return bufferVal.isEmpty() && bufStrCell.isEmpty() &&
bufBigIntCell.isEmpty() && bufObjCell.isEmpty() &&
bufferSlot.isEmpty() && bufferWasmAnyRef.isEmpty() &&
bufferWholeCell.isEmpty() && bufferGeneric.isEmpty();
}
bool StoreBuffer::enable() {
if (enabled_) {
return true;
}
checkEmpty();
if (!bufferWholeCell.init() || !bufferGeneric.init()) {
return false;
}
enabled_ = true;
return true;
}
void StoreBuffer::disable() {
checkEmpty();
if (!enabled_) {
return;
}
aboutToOverflow_ = false;
enabled_ = false;
}
void StoreBuffer::clear() {
if (!enabled_) {
return;
}
aboutToOverflow_ = false;
mayHavePointersToDeadCells_ = false;
bufferVal.clear();
bufStrCell.clear();
bufBigIntCell.clear();
bufObjCell.clear();
bufferSlot.clear();
bufferWasmAnyRef.clear();
bufferWholeCell.clear();
bufferGeneric.clear();
}
void StoreBuffer::setAboutToOverflow(JS::GCReason reason) {
if (!aboutToOverflow_) {
aboutToOverflow_ = true;
runtime_->gc.stats().count(gcstats::COUNT_STOREBUFFER_OVERFLOW);
}
nursery_.requestMinorGC(reason);
}
void StoreBuffer::addSizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf,
JS::GCSizes* sizes) {
sizes->storeBufferVals += bufferVal.sizeOfExcludingThis(mallocSizeOf);
sizes->storeBufferCells += bufStrCell.sizeOfExcludingThis(mallocSizeOf) +
bufBigIntCell.sizeOfExcludingThis(mallocSizeOf) +
bufObjCell.sizeOfExcludingThis(mallocSizeOf);
sizes->storeBufferSlots += bufferSlot.sizeOfExcludingThis(mallocSizeOf);
sizes->storeBufferWasmAnyRefs +=
bufferWasmAnyRef.sizeOfExcludingThis(mallocSizeOf);
sizes->storeBufferWholeCells +=
bufferWholeCell.sizeOfExcludingThis(mallocSizeOf);
sizes->storeBufferGenerics += bufferGeneric.sizeOfExcludingThis(mallocSizeOf);
}
ArenaCellSet ArenaCellSet::Empty;
ArenaCellSet::ArenaCellSet(Arena* arena)
: arena(arena)
#ifdef DEBUG
,
minorGCNumberAtCreation(
arena->zone()->runtimeFromMainThread()->gc.minorGCCount())
#endif
{
MOZ_ASSERT(arena);
MOZ_ASSERT(bits.isAllClear());
}
ArenaCellSet* StoreBuffer::WholeCellBuffer::allocateCellSet(Arena* arena) {
MOZ_ASSERT(arena->bufferedCells() == &ArenaCellSet::Empty);
Zone* zone = arena->zone();
JSRuntime* rt = zone->runtimeFromMainThread();
if (!rt->gc.nursery().isEnabled()) {
return nullptr;
}
AutoEnterOOMUnsafeRegion oomUnsafe;
auto* cells = storage_->new_<ArenaCellSet>(arena);
if (!cells) {
oomUnsafe.crash("Failed to allocate ArenaCellSet");
}
arena->bufferedCells() = cells;
if (isAboutToOverflow()) {
rt->gc.storeBuffer().setAboutToOverflow(
JS::GCReason::FULL_WHOLE_CELL_BUFFER);
}
return cells;
}
void gc::CellHeaderPostWriteBarrier(JSObject** ptr, JSObject* prev,
JSObject* next) {
InternalBarrierMethods<JSObject*>::postBarrier(ptr, prev, next);
}
void StoreBuffer::WholeCellBuffer::clear() {
for (LifoAlloc::Enum e(*storage_); !e.empty();) {
ArenaCellSet* cellSet = e.read<ArenaCellSet>();
cellSet->arena->bufferedCells() = &ArenaCellSet::Empty;
}
sweepHead_ = nullptr;
if (storage_) {
storage_->used() ? storage_->releaseAll() : storage_->freeAll();
}
last_ = nullptr;
}
template struct StoreBuffer::MonoTypeBuffer<StoreBuffer::ValueEdge>;
template struct StoreBuffer::MonoTypeBuffer<StoreBuffer::SlotsEdge>;
template struct StoreBuffer::MonoTypeBuffer<StoreBuffer::WasmAnyRefEdge>;
void js::gc::PostWriteBarrierCell(Cell* cell, Cell* prev, Cell* next) {
if (!next || !cell->isTenured()) {
return;
}
StoreBuffer* buffer = next->storeBuffer();
if (!buffer || (prev && prev->storeBuffer())) {
return;
}
buffer->putWholeCell(cell);
}