deps/v8/src/heap/incremental-marking.cc
// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/v8.h"
#include "src/heap/incremental-marking.h"
#include "src/code-stubs.h"
#include "src/compilation-cache.h"
#include "src/conversions.h"
#include "src/heap/objects-visiting.h"
#include "src/heap/objects-visiting-inl.h"
namespace v8 {
namespace internal {
IncrementalMarking::IncrementalMarking(Heap* heap)
: heap_(heap),
state_(STOPPED),
marking_deque_memory_(NULL),
marking_deque_memory_committed_(false),
steps_count_(0),
old_generation_space_available_at_start_of_incremental_(0),
old_generation_space_used_at_start_of_incremental_(0),
should_hurry_(false),
marking_speed_(0),
allocated_(0),
no_marking_scope_depth_(0),
unscanned_bytes_of_large_object_(0) {}
void IncrementalMarking::TearDown() { delete marking_deque_memory_; }
void IncrementalMarking::RecordWriteSlow(HeapObject* obj, Object** slot,
Object* value) {
if (BaseRecordWrite(obj, slot, value) && slot != NULL) {
MarkBit obj_bit = Marking::MarkBitFrom(obj);
if (Marking::IsBlack(obj_bit)) {
// Object is not going to be rescanned we need to record the slot.
heap_->mark_compact_collector()->RecordSlot(HeapObject::RawField(obj, 0),
slot, value);
}
}
}
void IncrementalMarking::RecordWriteFromCode(HeapObject* obj, Object** slot,
Isolate* isolate) {
DCHECK(obj->IsHeapObject());
IncrementalMarking* marking = isolate->heap()->incremental_marking();
MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address());
int counter = chunk->write_barrier_counter();
if (counter < (MemoryChunk::kWriteBarrierCounterGranularity / 2)) {
marking->write_barriers_invoked_since_last_step_ +=
MemoryChunk::kWriteBarrierCounterGranularity -
chunk->write_barrier_counter();
chunk->set_write_barrier_counter(
MemoryChunk::kWriteBarrierCounterGranularity);
}
marking->RecordWrite(obj, slot, *slot);
}
void IncrementalMarking::RecordCodeTargetPatch(Code* host, Address pc,
HeapObject* value) {
if (IsMarking()) {
RelocInfo rinfo(pc, RelocInfo::CODE_TARGET, 0, host);
RecordWriteIntoCode(host, &rinfo, value);
}
}
void IncrementalMarking::RecordCodeTargetPatch(Address pc, HeapObject* value) {
if (IsMarking()) {
Code* host = heap_->isolate()
->inner_pointer_to_code_cache()
->GcSafeFindCodeForInnerPointer(pc);
RelocInfo rinfo(pc, RelocInfo::CODE_TARGET, 0, host);
RecordWriteIntoCode(host, &rinfo, value);
}
}
void IncrementalMarking::RecordWriteOfCodeEntrySlow(JSFunction* host,
Object** slot,
Code* value) {
if (BaseRecordWrite(host, slot, value)) {
DCHECK(slot != NULL);
heap_->mark_compact_collector()->RecordCodeEntrySlot(
reinterpret_cast<Address>(slot), value);
}
}
void IncrementalMarking::RecordWriteIntoCodeSlow(HeapObject* obj,
RelocInfo* rinfo,
Object* value) {
MarkBit value_bit = Marking::MarkBitFrom(HeapObject::cast(value));
if (Marking::IsWhite(value_bit)) {
MarkBit obj_bit = Marking::MarkBitFrom(obj);
if (Marking::IsBlack(obj_bit)) {
BlackToGreyAndUnshift(obj, obj_bit);
RestartIfNotMarking();
}
// Object is either grey or white. It will be scanned if survives.
return;
}
if (is_compacting_) {
MarkBit obj_bit = Marking::MarkBitFrom(obj);
if (Marking::IsBlack(obj_bit)) {
// Object is not going to be rescanned. We need to record the slot.
heap_->mark_compact_collector()->RecordRelocSlot(rinfo,
Code::cast(value));
}
}
}
static void MarkObjectGreyDoNotEnqueue(Object* obj) {
if (obj->IsHeapObject()) {
HeapObject* heap_obj = HeapObject::cast(obj);
MarkBit mark_bit = Marking::MarkBitFrom(HeapObject::cast(obj));
if (Marking::IsBlack(mark_bit)) {
MemoryChunk::IncrementLiveBytesFromGC(heap_obj->address(),
-heap_obj->Size());
}
Marking::AnyToGrey(mark_bit);
}
}
static inline void MarkBlackOrKeepGrey(HeapObject* heap_object,
MarkBit mark_bit, int size) {
DCHECK(!Marking::IsImpossible(mark_bit));
if (mark_bit.Get()) return;
mark_bit.Set();
MemoryChunk::IncrementLiveBytesFromGC(heap_object->address(), size);
DCHECK(Marking::IsBlack(mark_bit));
}
static inline void MarkBlackOrKeepBlack(HeapObject* heap_object,
MarkBit mark_bit, int size) {
DCHECK(!Marking::IsImpossible(mark_bit));
if (Marking::IsBlack(mark_bit)) return;
Marking::MarkBlack(mark_bit);
MemoryChunk::IncrementLiveBytesFromGC(heap_object->address(), size);
DCHECK(Marking::IsBlack(mark_bit));
}
class IncrementalMarkingMarkingVisitor
: public StaticMarkingVisitor<IncrementalMarkingMarkingVisitor> {
public:
static void Initialize() {
StaticMarkingVisitor<IncrementalMarkingMarkingVisitor>::Initialize();
table_.Register(kVisitFixedArray, &VisitFixedArrayIncremental);
table_.Register(kVisitNativeContext, &VisitNativeContextIncremental);
table_.Register(kVisitJSRegExp, &VisitJSRegExp);
}
static const int kProgressBarScanningChunk = 32 * 1024;
static void VisitFixedArrayIncremental(Map* map, HeapObject* object) {
MemoryChunk* chunk = MemoryChunk::FromAddress(object->address());
// TODO(mstarzinger): Move setting of the flag to the allocation site of
// the array. The visitor should just check the flag.
if (FLAG_use_marking_progress_bar &&
chunk->owner()->identity() == LO_SPACE) {
chunk->SetFlag(MemoryChunk::HAS_PROGRESS_BAR);
}
if (chunk->IsFlagSet(MemoryChunk::HAS_PROGRESS_BAR)) {
Heap* heap = map->GetHeap();
// When using a progress bar for large fixed arrays, scan only a chunk of
// the array and try to push it onto the marking deque again until it is
// fully scanned. Fall back to scanning it through to the end in case this
// fails because of a full deque.
int object_size = FixedArray::BodyDescriptor::SizeOf(map, object);
int start_offset =
Max(FixedArray::BodyDescriptor::kStartOffset, chunk->progress_bar());
int end_offset =
Min(object_size, start_offset + kProgressBarScanningChunk);
int already_scanned_offset = start_offset;
bool scan_until_end = false;
do {
VisitPointersWithAnchor(heap, HeapObject::RawField(object, 0),
HeapObject::RawField(object, start_offset),
HeapObject::RawField(object, end_offset));
start_offset = end_offset;
end_offset = Min(object_size, end_offset + kProgressBarScanningChunk);
scan_until_end = heap->incremental_marking()->marking_deque()->IsFull();
} while (scan_until_end && start_offset < object_size);
chunk->set_progress_bar(start_offset);
if (start_offset < object_size) {
heap->incremental_marking()->marking_deque()->UnshiftGrey(object);
heap->incremental_marking()->NotifyIncompleteScanOfObject(
object_size - (start_offset - already_scanned_offset));
}
} else {
FixedArrayVisitor::Visit(map, object);
}
}
static void VisitNativeContextIncremental(Map* map, HeapObject* object) {
Context* context = Context::cast(object);
// We will mark cache black with a separate pass when we finish marking.
// Note that GC can happen when the context is not fully initialized,
// so the cache can be undefined.
Object* cache = context->get(Context::NORMALIZED_MAP_CACHE_INDEX);
if (!cache->IsUndefined()) {
MarkObjectGreyDoNotEnqueue(cache);
}
VisitNativeContext(map, context);
}
INLINE(static void VisitPointer(Heap* heap, Object** p)) {
Object* obj = *p;
if (obj->IsHeapObject()) {
heap->mark_compact_collector()->RecordSlot(p, p, obj);
MarkObject(heap, obj);
}
}
INLINE(static void VisitPointers(Heap* heap, Object** start, Object** end)) {
for (Object** p = start; p < end; p++) {
Object* obj = *p;
if (obj->IsHeapObject()) {
heap->mark_compact_collector()->RecordSlot(start, p, obj);
MarkObject(heap, obj);
}
}
}
INLINE(static void VisitPointersWithAnchor(Heap* heap, Object** anchor,
Object** start, Object** end)) {
for (Object** p = start; p < end; p++) {
Object* obj = *p;
if (obj->IsHeapObject()) {
heap->mark_compact_collector()->RecordSlot(anchor, p, obj);
MarkObject(heap, obj);
}
}
}
// Marks the object grey and pushes it on the marking stack.
INLINE(static void MarkObject(Heap* heap, Object* obj)) {
HeapObject* heap_object = HeapObject::cast(obj);
MarkBit mark_bit = Marking::MarkBitFrom(heap_object);
if (mark_bit.data_only()) {
MarkBlackOrKeepGrey(heap_object, mark_bit, heap_object->Size());
} else if (Marking::IsWhite(mark_bit)) {
heap->incremental_marking()->WhiteToGreyAndPush(heap_object, mark_bit);
}
}
// Marks the object black without pushing it on the marking stack.
// Returns true if object needed marking and false otherwise.
INLINE(static bool MarkObjectWithoutPush(Heap* heap, Object* obj)) {
HeapObject* heap_object = HeapObject::cast(obj);
MarkBit mark_bit = Marking::MarkBitFrom(heap_object);
if (Marking::IsWhite(mark_bit)) {
mark_bit.Set();
MemoryChunk::IncrementLiveBytesFromGC(heap_object->address(),
heap_object->Size());
return true;
}
return false;
}
};
class IncrementalMarkingRootMarkingVisitor : public ObjectVisitor {
public:
explicit IncrementalMarkingRootMarkingVisitor(
IncrementalMarking* incremental_marking)
: incremental_marking_(incremental_marking) {}
void VisitPointer(Object** p) { MarkObjectByPointer(p); }
void VisitPointers(Object** start, Object** end) {
for (Object** p = start; p < end; p++) MarkObjectByPointer(p);
}
private:
void MarkObjectByPointer(Object** p) {
Object* obj = *p;
if (!obj->IsHeapObject()) return;
HeapObject* heap_object = HeapObject::cast(obj);
MarkBit mark_bit = Marking::MarkBitFrom(heap_object);
if (mark_bit.data_only()) {
MarkBlackOrKeepGrey(heap_object, mark_bit, heap_object->Size());
} else {
if (Marking::IsWhite(mark_bit)) {
incremental_marking_->WhiteToGreyAndPush(heap_object, mark_bit);
}
}
}
IncrementalMarking* incremental_marking_;
};
void IncrementalMarking::Initialize() {
IncrementalMarkingMarkingVisitor::Initialize();
}
void IncrementalMarking::SetOldSpacePageFlags(MemoryChunk* chunk,
bool is_marking,
bool is_compacting) {
if (is_marking) {
chunk->SetFlag(MemoryChunk::POINTERS_TO_HERE_ARE_INTERESTING);
chunk->SetFlag(MemoryChunk::POINTERS_FROM_HERE_ARE_INTERESTING);
// It's difficult to filter out slots recorded for large objects.
if (chunk->owner()->identity() == LO_SPACE &&
chunk->size() > static_cast<size_t>(Page::kPageSize) && is_compacting) {
chunk->SetFlag(MemoryChunk::RESCAN_ON_EVACUATION);
}
} else if (chunk->owner()->identity() == CELL_SPACE ||
chunk->owner()->identity() == PROPERTY_CELL_SPACE ||
chunk->scan_on_scavenge()) {
chunk->ClearFlag(MemoryChunk::POINTERS_TO_HERE_ARE_INTERESTING);
chunk->ClearFlag(MemoryChunk::POINTERS_FROM_HERE_ARE_INTERESTING);
} else {
chunk->ClearFlag(MemoryChunk::POINTERS_TO_HERE_ARE_INTERESTING);
chunk->SetFlag(MemoryChunk::POINTERS_FROM_HERE_ARE_INTERESTING);
}
}
void IncrementalMarking::SetNewSpacePageFlags(NewSpacePage* chunk,
bool is_marking) {
chunk->SetFlag(MemoryChunk::POINTERS_TO_HERE_ARE_INTERESTING);
if (is_marking) {
chunk->SetFlag(MemoryChunk::POINTERS_FROM_HERE_ARE_INTERESTING);
} else {
chunk->ClearFlag(MemoryChunk::POINTERS_FROM_HERE_ARE_INTERESTING);
}
chunk->SetFlag(MemoryChunk::SCAN_ON_SCAVENGE);
}
void IncrementalMarking::DeactivateIncrementalWriteBarrierForSpace(
PagedSpace* space) {
PageIterator it(space);
while (it.has_next()) {
Page* p = it.next();
SetOldSpacePageFlags(p, false, false);
}
}
void IncrementalMarking::DeactivateIncrementalWriteBarrierForSpace(
NewSpace* space) {
NewSpacePageIterator it(space);
while (it.has_next()) {
NewSpacePage* p = it.next();
SetNewSpacePageFlags(p, false);
}
}
void IncrementalMarking::DeactivateIncrementalWriteBarrier() {
DeactivateIncrementalWriteBarrierForSpace(heap_->old_pointer_space());
DeactivateIncrementalWriteBarrierForSpace(heap_->old_data_space());
DeactivateIncrementalWriteBarrierForSpace(heap_->cell_space());
DeactivateIncrementalWriteBarrierForSpace(heap_->property_cell_space());
DeactivateIncrementalWriteBarrierForSpace(heap_->map_space());
DeactivateIncrementalWriteBarrierForSpace(heap_->code_space());
DeactivateIncrementalWriteBarrierForSpace(heap_->new_space());
LargePage* lop = heap_->lo_space()->first_page();
while (lop->is_valid()) {
SetOldSpacePageFlags(lop, false, false);
lop = lop->next_page();
}
}
void IncrementalMarking::ActivateIncrementalWriteBarrier(PagedSpace* space) {
PageIterator it(space);
while (it.has_next()) {
Page* p = it.next();
SetOldSpacePageFlags(p, true, is_compacting_);
}
}
void IncrementalMarking::ActivateIncrementalWriteBarrier(NewSpace* space) {
NewSpacePageIterator it(space->ToSpaceStart(), space->ToSpaceEnd());
while (it.has_next()) {
NewSpacePage* p = it.next();
SetNewSpacePageFlags(p, true);
}
}
void IncrementalMarking::ActivateIncrementalWriteBarrier() {
ActivateIncrementalWriteBarrier(heap_->old_pointer_space());
ActivateIncrementalWriteBarrier(heap_->old_data_space());
ActivateIncrementalWriteBarrier(heap_->cell_space());
ActivateIncrementalWriteBarrier(heap_->property_cell_space());
ActivateIncrementalWriteBarrier(heap_->map_space());
ActivateIncrementalWriteBarrier(heap_->code_space());
ActivateIncrementalWriteBarrier(heap_->new_space());
LargePage* lop = heap_->lo_space()->first_page();
while (lop->is_valid()) {
SetOldSpacePageFlags(lop, true, is_compacting_);
lop = lop->next_page();
}
}
bool IncrementalMarking::WorthActivating() {
#ifndef DEBUG
static const intptr_t kActivationThreshold = 8 * MB;
#else
// TODO(gc) consider setting this to some low level so that some
// debug tests run with incremental marking and some without.
static const intptr_t kActivationThreshold = 0;
#endif
// Only start incremental marking in a safe state: 1) when incremental
// marking is turned on, 2) when we are currently not in a GC, and
// 3) when we are currently not serializing or deserializing the heap.
return FLAG_incremental_marking && FLAG_incremental_marking_steps &&
heap_->gc_state() == Heap::NOT_IN_GC &&
!heap_->isolate()->serializer_enabled() &&
heap_->isolate()->IsInitialized() &&
heap_->PromotedSpaceSizeOfObjects() > kActivationThreshold;
}
void IncrementalMarking::ActivateGeneratedStub(Code* stub) {
DCHECK(RecordWriteStub::GetMode(stub) == RecordWriteStub::STORE_BUFFER_ONLY);
if (!IsMarking()) {
// Initially stub is generated in STORE_BUFFER_ONLY mode thus
// we don't need to do anything if incremental marking is
// not active.
} else if (IsCompacting()) {
RecordWriteStub::Patch(stub, RecordWriteStub::INCREMENTAL_COMPACTION);
} else {
RecordWriteStub::Patch(stub, RecordWriteStub::INCREMENTAL);
}
}
static void PatchIncrementalMarkingRecordWriteStubs(
Heap* heap, RecordWriteStub::Mode mode) {
UnseededNumberDictionary* stubs = heap->code_stubs();
int capacity = stubs->Capacity();
for (int i = 0; i < capacity; i++) {
Object* k = stubs->KeyAt(i);
if (stubs->IsKey(k)) {
uint32_t key = NumberToUint32(k);
if (CodeStub::MajorKeyFromKey(key) == CodeStub::RecordWrite) {
Object* e = stubs->ValueAt(i);
if (e->IsCode()) {
RecordWriteStub::Patch(Code::cast(e), mode);
}
}
}
}
}
void IncrementalMarking::EnsureMarkingDequeIsCommitted() {
if (marking_deque_memory_ == NULL) {
marking_deque_memory_ = new base::VirtualMemory(4 * MB);
}
if (!marking_deque_memory_committed_) {
bool success = marking_deque_memory_->Commit(
reinterpret_cast<Address>(marking_deque_memory_->address()),
marking_deque_memory_->size(),
false); // Not executable.
CHECK(success);
marking_deque_memory_committed_ = true;
}
}
void IncrementalMarking::UncommitMarkingDeque() {
if (state_ == STOPPED && marking_deque_memory_committed_) {
bool success = marking_deque_memory_->Uncommit(
reinterpret_cast<Address>(marking_deque_memory_->address()),
marking_deque_memory_->size());
CHECK(success);
marking_deque_memory_committed_ = false;
}
}
void IncrementalMarking::Start(CompactionFlag flag) {
if (FLAG_trace_incremental_marking) {
PrintF("[IncrementalMarking] Start\n");
}
DCHECK(FLAG_incremental_marking);
DCHECK(FLAG_incremental_marking_steps);
DCHECK(state_ == STOPPED);
DCHECK(heap_->gc_state() == Heap::NOT_IN_GC);
DCHECK(!heap_->isolate()->serializer_enabled());
DCHECK(heap_->isolate()->IsInitialized());
ResetStepCounters();
if (!heap_->mark_compact_collector()->sweeping_in_progress()) {
StartMarking(flag);
} else {
if (FLAG_trace_incremental_marking) {
PrintF("[IncrementalMarking] Start sweeping.\n");
}
state_ = SWEEPING;
}
heap_->new_space()->LowerInlineAllocationLimit(kAllocatedThreshold);
}
void IncrementalMarking::StartMarking(CompactionFlag flag) {
if (FLAG_trace_incremental_marking) {
PrintF("[IncrementalMarking] Start marking\n");
}
is_compacting_ = !FLAG_never_compact && (flag == ALLOW_COMPACTION) &&
heap_->mark_compact_collector()->StartCompaction(
MarkCompactCollector::INCREMENTAL_COMPACTION);
state_ = MARKING;
RecordWriteStub::Mode mode = is_compacting_
? RecordWriteStub::INCREMENTAL_COMPACTION
: RecordWriteStub::INCREMENTAL;
PatchIncrementalMarkingRecordWriteStubs(heap_, mode);
EnsureMarkingDequeIsCommitted();
// Initialize marking stack.
Address addr = static_cast<Address>(marking_deque_memory_->address());
size_t size = marking_deque_memory_->size();
if (FLAG_force_marking_deque_overflows) size = 64 * kPointerSize;
marking_deque_.Initialize(addr, addr + size);
ActivateIncrementalWriteBarrier();
// Marking bits are cleared by the sweeper.
#ifdef VERIFY_HEAP
if (FLAG_verify_heap) {
heap_->mark_compact_collector()->VerifyMarkbitsAreClean();
}
#endif
heap_->CompletelyClearInstanceofCache();
heap_->isolate()->compilation_cache()->MarkCompactPrologue();
if (FLAG_cleanup_code_caches_at_gc) {
// We will mark cache black with a separate pass
// when we finish marking.
MarkObjectGreyDoNotEnqueue(heap_->polymorphic_code_cache());
}
// Mark strong roots grey.
IncrementalMarkingRootMarkingVisitor visitor(this);
heap_->IterateStrongRoots(&visitor, VISIT_ONLY_STRONG);
heap_->mark_compact_collector()->MarkWeakObjectToCodeTable();
// Ready to start incremental marking.
if (FLAG_trace_incremental_marking) {
PrintF("[IncrementalMarking] Running\n");
}
}
void IncrementalMarking::PrepareForScavenge() {
if (!IsMarking()) return;
NewSpacePageIterator it(heap_->new_space()->FromSpaceStart(),
heap_->new_space()->FromSpaceEnd());
while (it.has_next()) {
Bitmap::Clear(it.next());
}
}
void IncrementalMarking::UpdateMarkingDequeAfterScavenge() {
if (!IsMarking()) return;
int current = marking_deque_.bottom();
int mask = marking_deque_.mask();
int limit = marking_deque_.top();
HeapObject** array = marking_deque_.array();
int new_top = current;
Map* filler_map = heap_->one_pointer_filler_map();
while (current != limit) {
HeapObject* obj = array[current];
DCHECK(obj->IsHeapObject());
current = ((current + 1) & mask);
if (heap_->InNewSpace(obj)) {
MapWord map_word = obj->map_word();
if (map_word.IsForwardingAddress()) {
HeapObject* dest = map_word.ToForwardingAddress();
array[new_top] = dest;
new_top = ((new_top + 1) & mask);
DCHECK(new_top != marking_deque_.bottom());
#ifdef DEBUG
MarkBit mark_bit = Marking::MarkBitFrom(obj);
DCHECK(Marking::IsGrey(mark_bit) ||
(obj->IsFiller() && Marking::IsWhite(mark_bit)));
#endif
}
} else if (obj->map() != filler_map) {
// Skip one word filler objects that appear on the
// stack when we perform in place array shift.
array[new_top] = obj;
new_top = ((new_top + 1) & mask);
DCHECK(new_top != marking_deque_.bottom());
#ifdef DEBUG
MarkBit mark_bit = Marking::MarkBitFrom(obj);
MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address());
DCHECK(Marking::IsGrey(mark_bit) ||
(obj->IsFiller() && Marking::IsWhite(mark_bit)) ||
(chunk->IsFlagSet(MemoryChunk::HAS_PROGRESS_BAR) &&
Marking::IsBlack(mark_bit)));
#endif
}
}
marking_deque_.set_top(new_top);
}
void IncrementalMarking::VisitObject(Map* map, HeapObject* obj, int size) {
MarkBit map_mark_bit = Marking::MarkBitFrom(map);
if (Marking::IsWhite(map_mark_bit)) {
WhiteToGreyAndPush(map, map_mark_bit);
}
IncrementalMarkingMarkingVisitor::IterateBody(map, obj);
MarkBit mark_bit = Marking::MarkBitFrom(obj);
#if ENABLE_SLOW_DCHECKS
MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address());
SLOW_DCHECK(Marking::IsGrey(mark_bit) ||
(obj->IsFiller() && Marking::IsWhite(mark_bit)) ||
(chunk->IsFlagSet(MemoryChunk::HAS_PROGRESS_BAR) &&
Marking::IsBlack(mark_bit)));
#endif
MarkBlackOrKeepBlack(obj, mark_bit, size);
}
intptr_t IncrementalMarking::ProcessMarkingDeque(intptr_t bytes_to_process) {
intptr_t bytes_processed = 0;
Map* filler_map = heap_->one_pointer_filler_map();
while (!marking_deque_.IsEmpty() && bytes_processed < bytes_to_process) {
HeapObject* obj = marking_deque_.Pop();
// Explicitly skip one word fillers. Incremental markbit patterns are
// correct only for objects that occupy at least two words.
Map* map = obj->map();
if (map == filler_map) continue;
int size = obj->SizeFromMap(map);
unscanned_bytes_of_large_object_ = 0;
VisitObject(map, obj, size);
int delta = (size - unscanned_bytes_of_large_object_);
// TODO(jochen): remove after http://crbug.com/381820 is resolved.
CHECK_LT(0, delta);
bytes_processed += delta;
}
return bytes_processed;
}
void IncrementalMarking::ProcessMarkingDeque() {
Map* filler_map = heap_->one_pointer_filler_map();
while (!marking_deque_.IsEmpty()) {
HeapObject* obj = marking_deque_.Pop();
// Explicitly skip one word fillers. Incremental markbit patterns are
// correct only for objects that occupy at least two words.
Map* map = obj->map();
if (map == filler_map) continue;
VisitObject(map, obj, obj->SizeFromMap(map));
}
}
void IncrementalMarking::Hurry() {
if (state() == MARKING) {
double start = 0.0;
if (FLAG_trace_incremental_marking || FLAG_print_cumulative_gc_stat) {
start = base::OS::TimeCurrentMillis();
if (FLAG_trace_incremental_marking) {
PrintF("[IncrementalMarking] Hurry\n");
}
}
// TODO(gc) hurry can mark objects it encounters black as mutator
// was stopped.
ProcessMarkingDeque();
state_ = COMPLETE;
if (FLAG_trace_incremental_marking || FLAG_print_cumulative_gc_stat) {
double end = base::OS::TimeCurrentMillis();
double delta = end - start;
heap_->tracer()->AddMarkingTime(delta);
if (FLAG_trace_incremental_marking) {
PrintF("[IncrementalMarking] Complete (hurry), spent %d ms.\n",
static_cast<int>(delta));
}
}
}
if (FLAG_cleanup_code_caches_at_gc) {
PolymorphicCodeCache* poly_cache = heap_->polymorphic_code_cache();
Marking::GreyToBlack(Marking::MarkBitFrom(poly_cache));
MemoryChunk::IncrementLiveBytesFromGC(poly_cache->address(),
PolymorphicCodeCache::kSize);
}
Object* context = heap_->native_contexts_list();
while (!context->IsUndefined()) {
// GC can happen when the context is not fully initialized,
// so the cache can be undefined.
HeapObject* cache = HeapObject::cast(
Context::cast(context)->get(Context::NORMALIZED_MAP_CACHE_INDEX));
if (!cache->IsUndefined()) {
MarkBit mark_bit = Marking::MarkBitFrom(cache);
if (Marking::IsGrey(mark_bit)) {
Marking::GreyToBlack(mark_bit);
MemoryChunk::IncrementLiveBytesFromGC(cache->address(), cache->Size());
}
}
context = Context::cast(context)->get(Context::NEXT_CONTEXT_LINK);
}
}
void IncrementalMarking::Abort() {
if (IsStopped()) return;
if (FLAG_trace_incremental_marking) {
PrintF("[IncrementalMarking] Aborting.\n");
}
heap_->new_space()->LowerInlineAllocationLimit(0);
IncrementalMarking::set_should_hurry(false);
ResetStepCounters();
if (IsMarking()) {
PatchIncrementalMarkingRecordWriteStubs(heap_,
RecordWriteStub::STORE_BUFFER_ONLY);
DeactivateIncrementalWriteBarrier();
if (is_compacting_) {
LargeObjectIterator it(heap_->lo_space());
for (HeapObject* obj = it.Next(); obj != NULL; obj = it.Next()) {
Page* p = Page::FromAddress(obj->address());
if (p->IsFlagSet(Page::RESCAN_ON_EVACUATION)) {
p->ClearFlag(Page::RESCAN_ON_EVACUATION);
}
}
}
}
heap_->isolate()->stack_guard()->ClearGC();
state_ = STOPPED;
is_compacting_ = false;
}
void IncrementalMarking::Finalize() {
Hurry();
state_ = STOPPED;
is_compacting_ = false;
heap_->new_space()->LowerInlineAllocationLimit(0);
IncrementalMarking::set_should_hurry(false);
ResetStepCounters();
PatchIncrementalMarkingRecordWriteStubs(heap_,
RecordWriteStub::STORE_BUFFER_ONLY);
DeactivateIncrementalWriteBarrier();
DCHECK(marking_deque_.IsEmpty());
heap_->isolate()->stack_guard()->ClearGC();
}
void IncrementalMarking::MarkingComplete(CompletionAction action) {
state_ = COMPLETE;
// We will set the stack guard to request a GC now. This will mean the rest
// of the GC gets performed as soon as possible (we can't do a GC here in a
// record-write context). If a few things get allocated between now and then
// that shouldn't make us do a scavenge and keep being incremental, so we set
// the should-hurry flag to indicate that there can't be much work left to do.
set_should_hurry(true);
if (FLAG_trace_incremental_marking) {
PrintF("[IncrementalMarking] Complete (normal).\n");
}
if (action == GC_VIA_STACK_GUARD) {
heap_->isolate()->stack_guard()->RequestGC();
}
}
void IncrementalMarking::OldSpaceStep(intptr_t allocated) {
if (IsStopped() && WorthActivating() && heap_->NextGCIsLikelyToBeFull()) {
// TODO(hpayer): Let's play safe for now, but compaction should be
// in principle possible.
Start(PREVENT_COMPACTION);
} else {
Step(allocated * kFastMarking / kInitialMarkingSpeed, GC_VIA_STACK_GUARD);
}
}
void IncrementalMarking::Step(intptr_t allocated_bytes, CompletionAction action,
bool force_marking) {
if (heap_->gc_state() != Heap::NOT_IN_GC || !FLAG_incremental_marking ||
!FLAG_incremental_marking_steps ||
(state_ != SWEEPING && state_ != MARKING)) {
return;
}
allocated_ += allocated_bytes;
if (!force_marking && allocated_ < kAllocatedThreshold &&
write_barriers_invoked_since_last_step_ <
kWriteBarriersInvokedThreshold) {
return;
}
if (state_ == MARKING && no_marking_scope_depth_ > 0) return;
{
HistogramTimerScope incremental_marking_scope(
heap_->isolate()->counters()->gc_incremental_marking());
double start = base::OS::TimeCurrentMillis();
// The marking speed is driven either by the allocation rate or by the rate
// at which we are having to check the color of objects in the write
// barrier.
// It is possible for a tight non-allocating loop to run a lot of write
// barriers before we get here and check them (marking can only take place
// on
// allocation), so to reduce the lumpiness we don't use the write barriers
// invoked since last step directly to determine the amount of work to do.
intptr_t bytes_to_process =
marking_speed_ *
Max(allocated_, write_barriers_invoked_since_last_step_);
allocated_ = 0;
write_barriers_invoked_since_last_step_ = 0;
bytes_scanned_ += bytes_to_process;
intptr_t bytes_processed = 0;
if (state_ == SWEEPING) {
if (heap_->mark_compact_collector()->sweeping_in_progress() &&
heap_->mark_compact_collector()->IsSweepingCompleted()) {
heap_->mark_compact_collector()->EnsureSweepingCompleted();
}
if (!heap_->mark_compact_collector()->sweeping_in_progress()) {
bytes_scanned_ = 0;
StartMarking(PREVENT_COMPACTION);
}
} else if (state_ == MARKING) {
bytes_processed = ProcessMarkingDeque(bytes_to_process);
if (marking_deque_.IsEmpty()) MarkingComplete(action);
}
steps_count_++;
bool speed_up = false;
if ((steps_count_ % kMarkingSpeedAccellerationInterval) == 0) {
if (FLAG_trace_gc) {
PrintPID("Speed up marking after %d steps\n",
static_cast<int>(kMarkingSpeedAccellerationInterval));
}
speed_up = true;
}
bool space_left_is_very_small =
(old_generation_space_available_at_start_of_incremental_ < 10 * MB);
bool only_1_nth_of_space_that_was_available_still_left =
(SpaceLeftInOldSpace() * (marking_speed_ + 1) <
old_generation_space_available_at_start_of_incremental_);
if (space_left_is_very_small ||
only_1_nth_of_space_that_was_available_still_left) {
if (FLAG_trace_gc)
PrintPID("Speed up marking because of low space left\n");
speed_up = true;
}
bool size_of_old_space_multiplied_by_n_during_marking =
(heap_->PromotedTotalSize() >
(marking_speed_ + 1) *
old_generation_space_used_at_start_of_incremental_);
if (size_of_old_space_multiplied_by_n_during_marking) {
speed_up = true;
if (FLAG_trace_gc) {
PrintPID("Speed up marking because of heap size increase\n");
}
}
int64_t promoted_during_marking =
heap_->PromotedTotalSize() -
old_generation_space_used_at_start_of_incremental_;
intptr_t delay = marking_speed_ * MB;
intptr_t scavenge_slack = heap_->MaxSemiSpaceSize();
// We try to scan at at least twice the speed that we are allocating.
if (promoted_during_marking > bytes_scanned_ / 2 + scavenge_slack + delay) {
if (FLAG_trace_gc) {
PrintPID("Speed up marking because marker was not keeping up\n");
}
speed_up = true;
}
if (speed_up) {
if (state_ != MARKING) {
if (FLAG_trace_gc) {
PrintPID("Postponing speeding up marking until marking starts\n");
}
} else {
marking_speed_ += kMarkingSpeedAccelleration;
marking_speed_ = static_cast<int>(
Min(kMaxMarkingSpeed, static_cast<intptr_t>(marking_speed_ * 1.3)));
if (FLAG_trace_gc) {
PrintPID("Marking speed increased to %d\n", marking_speed_);
}
}
}
double end = base::OS::TimeCurrentMillis();
double duration = (end - start);
// Note that we report zero bytes here when sweeping was in progress or
// when we just started incremental marking. In these cases we did not
// process the marking deque.
heap_->tracer()->AddIncrementalMarkingStep(duration, bytes_processed);
}
}
void IncrementalMarking::ResetStepCounters() {
steps_count_ = 0;
old_generation_space_available_at_start_of_incremental_ =
SpaceLeftInOldSpace();
old_generation_space_used_at_start_of_incremental_ =
heap_->PromotedTotalSize();
bytes_rescanned_ = 0;
marking_speed_ = kInitialMarkingSpeed;
bytes_scanned_ = 0;
write_barriers_invoked_since_last_step_ = 0;
}
int64_t IncrementalMarking::SpaceLeftInOldSpace() {
return heap_->MaxOldGenerationSize() - heap_->PromotedSpaceSizeOfObjects();
}
}
} // namespace v8::internal