// Copyright 2011 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "v8.h"
#include "incremental-marking.h"
#include "code-stubs.h"
#include "compilation-cache.h"
#include "v8conversions.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),
steps_took_(0),
longest_step_(0.0),
old_generation_space_available_at_start_of_incremental_(0),
old_generation_space_used_at_start_of_incremental_(0),
steps_count_since_last_gc_(0),
steps_took_since_last_gc_(0),
should_hurry_(false),
allocation_marking_factor_(0),
allocated_(0),
no_marking_scope_depth_(0) {
}
void IncrementalMarking::TearDown() {
delete marking_deque_memory_;
}
void IncrementalMarking::RecordWriteSlow(HeapObject* obj,
Object** slot,
Object* value) {
if (BaseRecordWrite(obj, slot, value) && is_compacting_ && 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* value,
Isolate* isolate) {
ASSERT(obj->IsHeapObject());
// Fast cases should already be covered by RecordWriteStub.
ASSERT(value->IsHeapObject());
ASSERT(!value->IsHeapNumber());
ASSERT(!value->IsString() ||
value->IsConsString() ||
value->IsSlicedString());
ASSERT(Marking::IsWhite(Marking::MarkBitFrom(HeapObject::cast(value))));
IncrementalMarking* marking = isolate->heap()->incremental_marking();
ASSERT(!marking->is_compacting_);
marking->RecordWrite(obj, NULL, value);
}
void IncrementalMarking::RecordWriteForEvacuationFromCode(HeapObject* obj,
Object** slot,
Isolate* isolate) {
IncrementalMarking* marking = isolate->heap()->incremental_marking();
ASSERT(marking->is_compacting_);
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) && is_compacting_) {
ASSERT(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));
}
}
}
class IncrementalMarkingMarkingVisitor : public ObjectVisitor {
public:
IncrementalMarkingMarkingVisitor(Heap* heap,
IncrementalMarking* incremental_marking)
: heap_(heap),
incremental_marking_(incremental_marking) {
}
void VisitEmbeddedPointer(RelocInfo* rinfo) {
ASSERT(rinfo->rmode() == RelocInfo::EMBEDDED_OBJECT);
Object* target = rinfo->target_object();
if (target->NonFailureIsHeapObject()) {
heap_->mark_compact_collector()->RecordRelocSlot(rinfo, target);
MarkObject(target);
}
}
void VisitCodeTarget(RelocInfo* rinfo) {
ASSERT(RelocInfo::IsCodeTarget(rinfo->rmode()));
Code* target = Code::GetCodeFromTargetAddress(rinfo->target_address());
if (FLAG_cleanup_code_caches_at_gc && target->is_inline_cache_stub()
&& (target->ic_age() != heap_->global_ic_age())) {
IC::Clear(rinfo->pc());
target = Code::GetCodeFromTargetAddress(rinfo->target_address());
}
heap_->mark_compact_collector()->RecordRelocSlot(rinfo, Code::cast(target));
MarkObject(target);
}
void VisitDebugTarget(RelocInfo* rinfo) {
ASSERT((RelocInfo::IsJSReturn(rinfo->rmode()) &&
rinfo->IsPatchedReturnSequence()) ||
(RelocInfo::IsDebugBreakSlot(rinfo->rmode()) &&
rinfo->IsPatchedDebugBreakSlotSequence()));
Object* target = Code::GetCodeFromTargetAddress(rinfo->call_address());
heap_->mark_compact_collector()->RecordRelocSlot(rinfo, Code::cast(target));
MarkObject(target);
}
void VisitCodeEntry(Address entry_address) {
Object* target = Code::GetObjectFromEntryAddress(entry_address);
heap_->mark_compact_collector()->
RecordCodeEntrySlot(entry_address, Code::cast(target));
MarkObject(target);
}
void VisitSharedFunctionInfo(SharedFunctionInfo* shared) {
if (shared->ic_age() != heap_->global_ic_age()) {
shared->ResetForNewContext(heap_->global_ic_age());
}
}
void VisitPointer(Object** p) {
Object* obj = *p;
if (obj->NonFailureIsHeapObject()) {
heap_->mark_compact_collector()->RecordSlot(p, p, obj);
MarkObject(obj);
}
}
void VisitPointers(Object** start, Object** end) {
for (Object** p = start; p < end; p++) {
Object* obj = *p;
if (obj->NonFailureIsHeapObject()) {
heap_->mark_compact_collector()->RecordSlot(start, p, obj);
MarkObject(obj);
}
}
}
private:
// Mark object pointed to by p.
INLINE(void MarkObject(Object* obj)) {
HeapObject* heap_object = HeapObject::cast(obj);
MarkBit mark_bit = Marking::MarkBitFrom(heap_object);
if (mark_bit.data_only()) {
if (incremental_marking_->MarkBlackOrKeepGrey(mark_bit)) {
MemoryChunk::IncrementLiveBytesFromGC(heap_object->address(),
heap_object->Size());
}
} else if (Marking::IsWhite(mark_bit)) {
incremental_marking_->WhiteToGreyAndPush(heap_object, mark_bit);
}
}
Heap* heap_;
IncrementalMarking* incremental_marking_;
};
class IncrementalMarkingRootMarkingVisitor : public ObjectVisitor {
public:
IncrementalMarkingRootMarkingVisitor(Heap* heap,
IncrementalMarking* incremental_marking)
: heap_(heap),
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()) {
if (incremental_marking_->MarkBlackOrKeepGrey(mark_bit)) {
MemoryChunk::IncrementLiveBytesFromGC(heap_object->address(),
heap_object->Size());
}
} else {
if (Marking::IsWhite(mark_bit)) {
incremental_marking_->WhiteToGreyAndPush(heap_object, mark_bit);
}
}
}
Heap* heap_;
IncrementalMarking* incremental_marking_;
};
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->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_->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_->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
return !FLAG_expose_gc &&
FLAG_incremental_marking &&
!Serializer::enabled() &&
heap_->PromotedSpaceSizeOfObjects() > kActivationThreshold;
}
void IncrementalMarking::ActivateGeneratedStub(Code* stub) {
ASSERT(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 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() {
if (FLAG_trace_incremental_marking) {
PrintF("[IncrementalMarking] Start\n");
}
ASSERT(FLAG_incremental_marking);
ASSERT(state_ == STOPPED);
ResetStepCounters();
if (heap_->old_pointer_space()->IsSweepingComplete() &&
heap_->old_data_space()->IsSweepingComplete()) {
StartMarking(ALLOW_COMPACTION);
} else {
if (FLAG_trace_incremental_marking) {
PrintF("[IncrementalMarking] Start sweeping.\n");
}
state_ = SWEEPING;
}
heap_->new_space()->LowerInlineAllocationLimit(kAllocatedThreshold);
}
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);
}
}
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();
#ifdef DEBUG
// Marking bits are cleared by the sweeper.
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(heap_, this);
heap_->IterateStrongRoots(&visitor, VISIT_ONLY_STRONG);
// 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];
ASSERT(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);
ASSERT(new_top != marking_deque_.bottom());
#ifdef DEBUG
MarkBit mark_bit = Marking::MarkBitFrom(obj);
ASSERT(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);
ASSERT(new_top != marking_deque_.bottom());
#ifdef DEBUG
MarkBit mark_bit = Marking::MarkBitFrom(obj);
ASSERT(Marking::IsGrey(mark_bit) ||
(obj->IsFiller() && Marking::IsWhite(mark_bit)));
#endif
}
}
marking_deque_.set_top(new_top);
steps_took_since_last_gc_ = 0;
steps_count_since_last_gc_ = 0;
longest_step_ = 0.0;
}
void IncrementalMarking::VisitGlobalContext(Context* ctx, ObjectVisitor* v) {
v->VisitPointers(
HeapObject::RawField(
ctx, Context::MarkCompactBodyDescriptor::kStartOffset),
HeapObject::RawField(
ctx, Context::MarkCompactBodyDescriptor::kEndOffset));
MarkCompactCollector* collector = heap_->mark_compact_collector();
for (int idx = Context::FIRST_WEAK_SLOT;
idx < Context::GLOBAL_CONTEXT_SLOTS;
++idx) {
Object** slot =
HeapObject::RawField(ctx, FixedArray::OffsetOfElementAt(idx));
collector->RecordSlot(slot, slot, *slot);
}
}
void IncrementalMarking::Hurry() {
if (state() == MARKING) {
double start = 0.0;
if (FLAG_trace_incremental_marking) {
PrintF("[IncrementalMarking] Hurry\n");
start = OS::TimeCurrentMillis();
}
// TODO(gc) hurry can mark objects it encounters black as mutator
// was stopped.
Map* filler_map = heap_->one_pointer_filler_map();
Map* global_context_map = heap_->global_context_map();
IncrementalMarkingMarkingVisitor marking_visitor(heap_, this);
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;
} else if (map == global_context_map) {
// Global contexts have weak fields.
VisitGlobalContext(Context::cast(obj), &marking_visitor);
} else {
obj->Iterate(&marking_visitor);
}
MarkBit mark_bit = Marking::MarkBitFrom(obj);
ASSERT(!Marking::IsBlack(mark_bit));
Marking::MarkBlack(mark_bit);
MemoryChunk::IncrementLiveBytesFromGC(obj->address(), obj->Size());
}
state_ = COMPLETE;
if (FLAG_trace_incremental_marking) {
double end = OS::TimeCurrentMillis();
PrintF("[IncrementalMarking] Complete (hurry), spent %d ms.\n",
static_cast<int>(end - start));
}
}
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_->global_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()->Continue(GC_REQUEST);
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();
ASSERT(marking_deque_.IsEmpty());
heap_->isolate()->stack_guard()->Continue(GC_REQUEST);
}
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::Step(intptr_t allocated_bytes,
CompletionAction action) {
if (heap_->gc_state() != Heap::NOT_IN_GC ||
!FLAG_incremental_marking ||
!FLAG_incremental_marking_steps ||
(state_ != SWEEPING && state_ != MARKING)) {
return;
}
allocated_ += allocated_bytes;
if (allocated_ < kAllocatedThreshold) return;
if (state_ == MARKING && no_marking_scope_depth_ > 0) return;
intptr_t bytes_to_process = allocated_ * allocation_marking_factor_;
bytes_scanned_ += bytes_to_process;
double start = 0;
if (FLAG_trace_incremental_marking || FLAG_trace_gc) {
start = OS::TimeCurrentMillis();
}
if (state_ == SWEEPING) {
if (heap_->AdvanceSweepers(static_cast<int>(bytes_to_process))) {
bytes_scanned_ = 0;
StartMarking(PREVENT_COMPACTION);
}
} else if (state_ == MARKING) {
Map* filler_map = heap_->one_pointer_filler_map();
Map* global_context_map = heap_->global_context_map();
IncrementalMarkingMarkingVisitor marking_visitor(heap_, this);
while (!marking_deque_.IsEmpty() && bytes_to_process > 0) {
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;
if (obj->IsMap()) {
Map* map = Map::cast(obj);
heap_->ClearCacheOnMap(map);
}
int size = obj->SizeFromMap(map);
bytes_to_process -= size;
MarkBit map_mark_bit = Marking::MarkBitFrom(map);
if (Marking::IsWhite(map_mark_bit)) {
WhiteToGreyAndPush(map, map_mark_bit);
}
// TODO(gc) switch to static visitor instead of normal visitor.
if (map == global_context_map) {
// Global contexts have weak fields.
Context* ctx = Context::cast(obj);
// We will mark cache black with a separate pass
// when we finish marking.
MarkObjectGreyDoNotEnqueue(ctx->normalized_map_cache());
VisitGlobalContext(ctx, &marking_visitor);
} else {
obj->IterateBody(map->instance_type(), size, &marking_visitor);
}
MarkBit obj_mark_bit = Marking::MarkBitFrom(obj);
SLOW_ASSERT(Marking::IsGrey(obj_mark_bit) ||
(obj->IsFiller() && Marking::IsWhite(obj_mark_bit)));
Marking::MarkBlack(obj_mark_bit);
MemoryChunk::IncrementLiveBytesFromGC(obj->address(), size);
}
if (marking_deque_.IsEmpty()) MarkingComplete(action);
}
allocated_ = 0;
steps_count_++;
steps_count_since_last_gc_++;
bool speed_up = false;
if ((steps_count_ % kAllocationMarkingFactorSpeedupInterval) == 0) {
if (FLAG_trace_gc) {
PrintF("Speed up marking after %d steps\n",
static_cast<int>(kAllocationMarkingFactorSpeedupInterval));
}
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() * (allocation_marking_factor_ + 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) PrintF("Speed up marking because of low space left\n");
speed_up = true;
}
bool size_of_old_space_multiplied_by_n_during_marking =
(heap_->PromotedTotalSize() >
(allocation_marking_factor_ + 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) {
PrintF("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 = allocation_marking_factor_ * 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) {
PrintF("Speed up marking because marker was not keeping up\n");
}
speed_up = true;
}
if (speed_up) {
if (state_ != MARKING) {
if (FLAG_trace_gc) {
PrintF("Postponing speeding up marking until marking starts\n");
}
} else {
allocation_marking_factor_ += kAllocationMarkingFactorSpeedup;
allocation_marking_factor_ = static_cast<int>(
Min(kMaxAllocationMarkingFactor,
static_cast<intptr_t>(allocation_marking_factor_ * 1.3)));
if (FLAG_trace_gc) {
PrintF("Marking speed increased to %d\n", allocation_marking_factor_);
}
}
}
if (FLAG_trace_incremental_marking || FLAG_trace_gc) {
double end = OS::TimeCurrentMillis();
double delta = (end - start);
longest_step_ = Max(longest_step_, delta);
steps_took_ += delta;
steps_took_since_last_gc_ += delta;
}
}
void IncrementalMarking::ResetStepCounters() {
steps_count_ = 0;
steps_took_ = 0;
longest_step_ = 0.0;
old_generation_space_available_at_start_of_incremental_ =
SpaceLeftInOldSpace();
old_generation_space_used_at_start_of_incremental_ =
heap_->PromotedTotalSize();
steps_count_since_last_gc_ = 0;
steps_took_since_last_gc_ = 0;
bytes_rescanned_ = 0;
allocation_marking_factor_ = kInitialAllocationMarkingFactor;
bytes_scanned_ = 0;
}
int64_t IncrementalMarking::SpaceLeftInOldSpace() {
return heap_->MaxOldGenerationSize() - heap_->PromotedSpaceSize();
}
} } // namespace v8::internal