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// 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/execution.h"
#include "src/mark-compact.h"
#include "src/objects.h"
namespace v8 {
namespace internal {
class IncrementalMarking {
enum State {
enum CompletionAction {
explicit IncrementalMarking(Heap* heap);
static void Initialize();
void TearDown();
State state() {
ASSERT(state_ == STOPPED || FLAG_incremental_marking);
return state_;
bool should_hurry() { return should_hurry_; }
void set_should_hurry(bool val) { should_hurry_ = val; }
inline bool IsStopped() { return state() == STOPPED; }
INLINE(bool IsMarking()) { return state() >= MARKING; }
inline bool IsMarkingIncomplete() { return state() == MARKING; }
inline bool IsComplete() { return state() == COMPLETE; }
bool WorthActivating();
void Start(CompactionFlag flag = ALLOW_COMPACTION);
void Stop();
void PrepareForScavenge();
void UpdateMarkingDequeAfterScavenge();
void Hurry();
void Finalize();
void Abort();
void MarkingComplete(CompletionAction action);
// It's hard to know how much work the incremental marker should do to make
// progress in the face of the mutator creating new work for it. We start
// of at a moderate rate of work and gradually increase the speed of the
// incremental marker until it completes.
// Do some marking every time this much memory has been allocated or that many
// heavy (color-checking) write barriers have been invoked.
static const intptr_t kAllocatedThreshold = 65536;
static const intptr_t kWriteBarriersInvokedThreshold = 32768;
// Start off by marking this many times more memory than has been allocated.
static const intptr_t kInitialMarkingSpeed = 1;
// But if we are promoting a lot of data we need to mark faster to keep up
// with the data that is entering the old space through promotion.
static const intptr_t kFastMarking = 3;
// After this many steps we increase the marking/allocating factor.
static const intptr_t kMarkingSpeedAccellerationInterval = 1024;
// This is how much we increase the marking/allocating factor by.
static const intptr_t kMarkingSpeedAccelleration = 2;
static const intptr_t kMaxMarkingSpeed = 1000;
void OldSpaceStep(intptr_t allocated);
void Step(intptr_t allocated, CompletionAction action);
inline void RestartIfNotMarking() {
if (state_ == COMPLETE) {
state_ = MARKING;
if (FLAG_trace_incremental_marking) {
PrintF("[IncrementalMarking] Restarting (new grey objects)\n");
static void RecordWriteFromCode(HeapObject* obj,
Object** slot,
Isolate* isolate);
// Record a slot for compaction. Returns false for objects that are
// guaranteed to be rescanned or not guaranteed to survive.
// No slots in white objects should be recorded, as some slots are typed and
// cannot be interpreted correctly if the underlying object does not survive
// the incremental cycle (stays white).
INLINE(bool BaseRecordWrite(HeapObject* obj, Object** slot, Object* value));
INLINE(void RecordWrite(HeapObject* obj, Object** slot, Object* value));
INLINE(void RecordWriteIntoCode(HeapObject* obj,
RelocInfo* rinfo,
Object* value));
INLINE(void RecordWriteOfCodeEntry(JSFunction* host,
Object** slot,
Code* value));
void RecordWriteSlow(HeapObject* obj, Object** slot, Object* value);
void RecordWriteIntoCodeSlow(HeapObject* obj,
RelocInfo* rinfo,
Object* value);
void RecordWriteOfCodeEntrySlow(JSFunction* host, Object** slot, Code* value);
void RecordCodeTargetPatch(Code* host, Address pc, HeapObject* value);
void RecordCodeTargetPatch(Address pc, HeapObject* value);
inline void RecordWrites(HeapObject* obj);
inline void BlackToGreyAndUnshift(HeapObject* obj, MarkBit mark_bit);
inline void WhiteToGreyAndPush(HeapObject* obj, MarkBit mark_bit);
inline int steps_count() {
return steps_count_;
inline double steps_took() {
return steps_took_;
inline double longest_step() {
return longest_step_;
inline int steps_count_since_last_gc() {
return steps_count_since_last_gc_;
inline double steps_took_since_last_gc() {
return steps_took_since_last_gc_;
inline void SetOldSpacePageFlags(MemoryChunk* chunk) {
SetOldSpacePageFlags(chunk, IsMarking(), IsCompacting());
inline void SetNewSpacePageFlags(NewSpacePage* chunk) {
SetNewSpacePageFlags(chunk, IsMarking());
MarkingDeque* marking_deque() { return &marking_deque_; }
bool IsCompacting() { return IsMarking() && is_compacting_; }
void ActivateGeneratedStub(Code* stub);
void NotifyOfHighPromotionRate() {
if (IsMarking()) {
if (marking_speed_ < kFastMarking) {
if (FLAG_trace_gc) {
PrintPID("Increasing marking speed to %d "
"due to high promotion rate\n",
marking_speed_ = kFastMarking;
void EnterNoMarkingScope() {
void LeaveNoMarkingScope() {
void UncommitMarkingDeque();
void NotifyIncompleteScanOfObject(int unscanned_bytes) {
unscanned_bytes_of_large_object_ = unscanned_bytes;
int64_t SpaceLeftInOldSpace();
void ResetStepCounters();
void StartMarking(CompactionFlag flag);
void ActivateIncrementalWriteBarrier(PagedSpace* space);
static void ActivateIncrementalWriteBarrier(NewSpace* space);
void ActivateIncrementalWriteBarrier();
static void DeactivateIncrementalWriteBarrierForSpace(PagedSpace* space);
static void DeactivateIncrementalWriteBarrierForSpace(NewSpace* space);
void DeactivateIncrementalWriteBarrier();
static void SetOldSpacePageFlags(MemoryChunk* chunk,
bool is_marking,
bool is_compacting);
static void SetNewSpacePageFlags(NewSpacePage* chunk, bool is_marking);
void EnsureMarkingDequeIsCommitted();
INLINE(void ProcessMarkingDeque());
INLINE(void ProcessMarkingDeque(intptr_t bytes_to_process));
INLINE(void VisitObject(Map* map, HeapObject* obj, int size));
Heap* heap_;
State state_;
bool is_compacting_;
VirtualMemory* marking_deque_memory_;
bool marking_deque_memory_committed_;
MarkingDeque marking_deque_;
int steps_count_;
double steps_took_;
double longest_step_;
int64_t old_generation_space_available_at_start_of_incremental_;
int64_t old_generation_space_used_at_start_of_incremental_;
int steps_count_since_last_gc_;
double steps_took_since_last_gc_;
int64_t bytes_rescanned_;
bool should_hurry_;
int marking_speed_;
intptr_t bytes_scanned_;
intptr_t allocated_;
intptr_t write_barriers_invoked_since_last_step_;
int no_marking_scope_depth_;
int unscanned_bytes_of_large_object_;
} } // namespace v8::internal