| // 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/heap/mark-compact.h" |
| |
| #include "src/base/atomicops.h" |
| #include "src/base/bits.h" |
| #include "src/code-stubs.h" |
| #include "src/compilation-cache.h" |
| #include "src/cpu-profiler.h" |
| #include "src/deoptimizer.h" |
| #include "src/execution.h" |
| #include "src/frames-inl.h" |
| #include "src/gdb-jit.h" |
| #include "src/global-handles.h" |
| #include "src/heap/gc-tracer.h" |
| #include "src/heap/incremental-marking.h" |
| #include "src/heap/mark-compact-inl.h" |
| #include "src/heap/objects-visiting.h" |
| #include "src/heap/objects-visiting-inl.h" |
| #include "src/heap/spaces-inl.h" |
| #include "src/heap-profiler.h" |
| #include "src/ic/ic.h" |
| #include "src/ic/stub-cache.h" |
| #include "src/v8.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| |
| const char* Marking::kWhiteBitPattern = "00"; |
| const char* Marking::kBlackBitPattern = "10"; |
| const char* Marking::kGreyBitPattern = "11"; |
| const char* Marking::kImpossibleBitPattern = "01"; |
| |
| |
| // ------------------------------------------------------------------------- |
| // MarkCompactCollector |
| |
| MarkCompactCollector::MarkCompactCollector(Heap* heap) |
| : // NOLINT |
| #ifdef DEBUG |
| state_(IDLE), |
| #endif |
| marking_parity_(ODD_MARKING_PARITY), |
| compacting_(false), |
| was_marked_incrementally_(false), |
| sweeping_in_progress_(false), |
| pending_sweeper_jobs_semaphore_(0), |
| evacuation_(false), |
| migration_slots_buffer_(NULL), |
| heap_(heap), |
| marking_deque_memory_(NULL), |
| marking_deque_memory_committed_(0), |
| code_flusher_(NULL), |
| have_code_to_deoptimize_(false) { |
| } |
| |
| #ifdef VERIFY_HEAP |
| class VerifyMarkingVisitor : public ObjectVisitor { |
| public: |
| explicit VerifyMarkingVisitor(Heap* heap) : heap_(heap) {} |
| |
| void VisitPointers(Object** start, Object** end) { |
| for (Object** current = start; current < end; current++) { |
| if ((*current)->IsHeapObject()) { |
| HeapObject* object = HeapObject::cast(*current); |
| CHECK(heap_->mark_compact_collector()->IsMarked(object)); |
| } |
| } |
| } |
| |
| void VisitEmbeddedPointer(RelocInfo* rinfo) { |
| DCHECK(rinfo->rmode() == RelocInfo::EMBEDDED_OBJECT); |
| if (!rinfo->host()->IsWeakObject(rinfo->target_object())) { |
| Object* p = rinfo->target_object(); |
| VisitPointer(&p); |
| } |
| } |
| |
| void VisitCell(RelocInfo* rinfo) { |
| Code* code = rinfo->host(); |
| DCHECK(rinfo->rmode() == RelocInfo::CELL); |
| if (!code->IsWeakObject(rinfo->target_cell())) { |
| ObjectVisitor::VisitCell(rinfo); |
| } |
| } |
| |
| private: |
| Heap* heap_; |
| }; |
| |
| |
| static void VerifyMarking(Heap* heap, Address bottom, Address top) { |
| VerifyMarkingVisitor visitor(heap); |
| HeapObject* object; |
| Address next_object_must_be_here_or_later = bottom; |
| |
| for (Address current = bottom; current < top; current += kPointerSize) { |
| object = HeapObject::FromAddress(current); |
| if (MarkCompactCollector::IsMarked(object)) { |
| CHECK(Marking::IsBlack(Marking::MarkBitFrom(object))); |
| CHECK(current >= next_object_must_be_here_or_later); |
| object->Iterate(&visitor); |
| next_object_must_be_here_or_later = current + object->Size(); |
| } |
| } |
| } |
| |
| |
| static void VerifyMarking(NewSpace* space) { |
| Address end = space->top(); |
| NewSpacePageIterator it(space->bottom(), end); |
| // The bottom position is at the start of its page. Allows us to use |
| // page->area_start() as start of range on all pages. |
| CHECK_EQ(space->bottom(), |
| NewSpacePage::FromAddress(space->bottom())->area_start()); |
| while (it.has_next()) { |
| NewSpacePage* page = it.next(); |
| Address limit = it.has_next() ? page->area_end() : end; |
| CHECK(limit == end || !page->Contains(end)); |
| VerifyMarking(space->heap(), page->area_start(), limit); |
| } |
| } |
| |
| |
| static void VerifyMarking(PagedSpace* space) { |
| PageIterator it(space); |
| |
| while (it.has_next()) { |
| Page* p = it.next(); |
| VerifyMarking(space->heap(), p->area_start(), p->area_end()); |
| } |
| } |
| |
| |
| static void VerifyMarking(Heap* heap) { |
| VerifyMarking(heap->old_space()); |
| VerifyMarking(heap->code_space()); |
| VerifyMarking(heap->map_space()); |
| VerifyMarking(heap->new_space()); |
| |
| VerifyMarkingVisitor visitor(heap); |
| |
| LargeObjectIterator it(heap->lo_space()); |
| for (HeapObject* obj = it.Next(); obj != NULL; obj = it.Next()) { |
| if (MarkCompactCollector::IsMarked(obj)) { |
| obj->Iterate(&visitor); |
| } |
| } |
| |
| heap->IterateStrongRoots(&visitor, VISIT_ONLY_STRONG); |
| } |
| |
| |
| class VerifyEvacuationVisitor : public ObjectVisitor { |
| public: |
| void VisitPointers(Object** start, Object** end) { |
| for (Object** current = start; current < end; current++) { |
| if ((*current)->IsHeapObject()) { |
| HeapObject* object = HeapObject::cast(*current); |
| CHECK(!MarkCompactCollector::IsOnEvacuationCandidate(object)); |
| } |
| } |
| } |
| }; |
| |
| |
| static void VerifyEvacuation(Page* page) { |
| VerifyEvacuationVisitor visitor; |
| HeapObjectIterator iterator(page); |
| for (HeapObject* heap_object = iterator.Next(); heap_object != NULL; |
| heap_object = iterator.Next()) { |
| // We skip free space objects. |
| if (!heap_object->IsFiller()) { |
| heap_object->Iterate(&visitor); |
| } |
| } |
| } |
| |
| |
| static void VerifyEvacuation(NewSpace* space) { |
| NewSpacePageIterator it(space->bottom(), space->top()); |
| VerifyEvacuationVisitor visitor; |
| |
| while (it.has_next()) { |
| NewSpacePage* page = it.next(); |
| Address current = page->area_start(); |
| Address limit = it.has_next() ? page->area_end() : space->top(); |
| CHECK(limit == space->top() || !page->Contains(space->top())); |
| while (current < limit) { |
| HeapObject* object = HeapObject::FromAddress(current); |
| object->Iterate(&visitor); |
| current += object->Size(); |
| } |
| } |
| } |
| |
| |
| static void VerifyEvacuation(Heap* heap, PagedSpace* space) { |
| if (FLAG_use_allocation_folding && (space == heap->old_space())) { |
| return; |
| } |
| PageIterator it(space); |
| |
| while (it.has_next()) { |
| Page* p = it.next(); |
| if (p->IsEvacuationCandidate()) continue; |
| VerifyEvacuation(p); |
| } |
| } |
| |
| |
| static void VerifyEvacuation(Heap* heap) { |
| VerifyEvacuation(heap, heap->old_space()); |
| VerifyEvacuation(heap, heap->code_space()); |
| VerifyEvacuation(heap, heap->map_space()); |
| VerifyEvacuation(heap->new_space()); |
| |
| VerifyEvacuationVisitor visitor; |
| heap->IterateStrongRoots(&visitor, VISIT_ALL); |
| } |
| #endif // VERIFY_HEAP |
| |
| |
| void MarkCompactCollector::SetUp() { |
| free_list_old_space_.Reset(new FreeList(heap_->old_space())); |
| free_list_code_space_.Reset(new FreeList(heap_->code_space())); |
| free_list_map_space_.Reset(new FreeList(heap_->map_space())); |
| EnsureMarkingDequeIsReserved(); |
| EnsureMarkingDequeIsCommitted(kMinMarkingDequeSize); |
| } |
| |
| |
| void MarkCompactCollector::TearDown() { |
| AbortCompaction(); |
| delete marking_deque_memory_; |
| } |
| |
| |
| void MarkCompactCollector::AddEvacuationCandidate(Page* p) { |
| DCHECK(!p->NeverEvacuate()); |
| p->MarkEvacuationCandidate(); |
| evacuation_candidates_.Add(p); |
| } |
| |
| |
| static void TraceFragmentation(PagedSpace* space) { |
| int number_of_pages = space->CountTotalPages(); |
| intptr_t reserved = (number_of_pages * space->AreaSize()); |
| intptr_t free = reserved - space->SizeOfObjects(); |
| PrintF("[%s]: %d pages, %d (%.1f%%) free\n", |
| AllocationSpaceName(space->identity()), number_of_pages, |
| static_cast<int>(free), static_cast<double>(free) * 100 / reserved); |
| } |
| |
| |
| bool MarkCompactCollector::StartCompaction(CompactionMode mode) { |
| if (!compacting_) { |
| DCHECK(evacuation_candidates_.length() == 0); |
| |
| CollectEvacuationCandidates(heap()->old_space()); |
| |
| if (FLAG_compact_code_space) { |
| CollectEvacuationCandidates(heap()->code_space()); |
| } else if (FLAG_trace_fragmentation) { |
| TraceFragmentation(heap()->code_space()); |
| } |
| |
| if (FLAG_trace_fragmentation) { |
| TraceFragmentation(heap()->map_space()); |
| } |
| |
| heap()->old_space()->EvictEvacuationCandidatesFromFreeLists(); |
| heap()->code_space()->EvictEvacuationCandidatesFromFreeLists(); |
| |
| compacting_ = evacuation_candidates_.length() > 0; |
| } |
| |
| return compacting_; |
| } |
| |
| |
| void MarkCompactCollector::ClearInvalidStoreAndSlotsBufferEntries() { |
| heap_->store_buffer()->ClearInvalidStoreBufferEntries(); |
| |
| int number_of_pages = evacuation_candidates_.length(); |
| for (int i = 0; i < number_of_pages; i++) { |
| Page* p = evacuation_candidates_[i]; |
| SlotsBuffer::RemoveInvalidSlots(heap_, p->slots_buffer()); |
| } |
| } |
| |
| |
| #ifdef VERIFY_HEAP |
| static void VerifyValidSlotsBufferEntries(Heap* heap, PagedSpace* space) { |
| PageIterator it(space); |
| while (it.has_next()) { |
| Page* p = it.next(); |
| SlotsBuffer::VerifySlots(heap, p->slots_buffer()); |
| } |
| } |
| |
| |
| static void VerifyValidStoreAndSlotsBufferEntries(Heap* heap) { |
| heap->store_buffer()->VerifyValidStoreBufferEntries(); |
| |
| VerifyValidSlotsBufferEntries(heap, heap->old_space()); |
| VerifyValidSlotsBufferEntries(heap, heap->code_space()); |
| VerifyValidSlotsBufferEntries(heap, heap->map_space()); |
| |
| LargeObjectIterator it(heap->lo_space()); |
| for (HeapObject* object = it.Next(); object != NULL; object = it.Next()) { |
| MemoryChunk* chunk = MemoryChunk::FromAddress(object->address()); |
| SlotsBuffer::VerifySlots(heap, chunk->slots_buffer()); |
| } |
| } |
| #endif |
| |
| |
| void MarkCompactCollector::CollectGarbage() { |
| // Make sure that Prepare() has been called. The individual steps below will |
| // update the state as they proceed. |
| DCHECK(state_ == PREPARE_GC); |
| |
| MarkLiveObjects(); |
| |
| DCHECK(heap_->incremental_marking()->IsStopped()); |
| |
| // ClearNonLiveReferences can deoptimize code in dependent code arrays. |
| // Process weak cells before so that weak cells in dependent code |
| // arrays are cleared or contain only live code objects. |
| ProcessAndClearWeakCells(); |
| |
| ClearNonLiveReferences(); |
| |
| ClearWeakCollections(); |
| |
| heap_->set_encountered_weak_cells(Smi::FromInt(0)); |
| |
| #ifdef VERIFY_HEAP |
| if (FLAG_verify_heap) { |
| VerifyMarking(heap_); |
| } |
| #endif |
| |
| ClearInvalidStoreAndSlotsBufferEntries(); |
| |
| #ifdef VERIFY_HEAP |
| if (FLAG_verify_heap) { |
| VerifyValidStoreAndSlotsBufferEntries(heap_); |
| } |
| #endif |
| |
| SweepSpaces(); |
| |
| Finish(); |
| |
| if (marking_parity_ == EVEN_MARKING_PARITY) { |
| marking_parity_ = ODD_MARKING_PARITY; |
| } else { |
| DCHECK(marking_parity_ == ODD_MARKING_PARITY); |
| marking_parity_ = EVEN_MARKING_PARITY; |
| } |
| } |
| |
| |
| #ifdef VERIFY_HEAP |
| void MarkCompactCollector::VerifyMarkbitsAreClean(PagedSpace* space) { |
| PageIterator it(space); |
| |
| while (it.has_next()) { |
| Page* p = it.next(); |
| CHECK(p->markbits()->IsClean()); |
| CHECK_EQ(0, p->LiveBytes()); |
| } |
| } |
| |
| |
| void MarkCompactCollector::VerifyMarkbitsAreClean(NewSpace* space) { |
| NewSpacePageIterator it(space->bottom(), space->top()); |
| |
| while (it.has_next()) { |
| NewSpacePage* p = it.next(); |
| CHECK(p->markbits()->IsClean()); |
| CHECK_EQ(0, p->LiveBytes()); |
| } |
| } |
| |
| |
| void MarkCompactCollector::VerifyMarkbitsAreClean() { |
| VerifyMarkbitsAreClean(heap_->old_space()); |
| VerifyMarkbitsAreClean(heap_->code_space()); |
| VerifyMarkbitsAreClean(heap_->map_space()); |
| VerifyMarkbitsAreClean(heap_->new_space()); |
| |
| LargeObjectIterator it(heap_->lo_space()); |
| for (HeapObject* obj = it.Next(); obj != NULL; obj = it.Next()) { |
| MarkBit mark_bit = Marking::MarkBitFrom(obj); |
| CHECK(Marking::IsWhite(mark_bit)); |
| CHECK_EQ(0, Page::FromAddress(obj->address())->LiveBytes()); |
| } |
| } |
| |
| |
| void MarkCompactCollector::VerifyWeakEmbeddedObjectsInCode() { |
| HeapObjectIterator code_iterator(heap()->code_space()); |
| for (HeapObject* obj = code_iterator.Next(); obj != NULL; |
| obj = code_iterator.Next()) { |
| Code* code = Code::cast(obj); |
| if (!code->is_optimized_code()) continue; |
| if (WillBeDeoptimized(code)) continue; |
| code->VerifyEmbeddedObjectsDependency(); |
| } |
| } |
| |
| |
| void MarkCompactCollector::VerifyOmittedMapChecks() { |
| HeapObjectIterator iterator(heap()->map_space()); |
| for (HeapObject* obj = iterator.Next(); obj != NULL; obj = iterator.Next()) { |
| Map* map = Map::cast(obj); |
| map->VerifyOmittedMapChecks(); |
| } |
| } |
| #endif // VERIFY_HEAP |
| |
| |
| static void ClearMarkbitsInPagedSpace(PagedSpace* space) { |
| PageIterator it(space); |
| |
| while (it.has_next()) { |
| Bitmap::Clear(it.next()); |
| } |
| } |
| |
| |
| static void ClearMarkbitsInNewSpace(NewSpace* space) { |
| NewSpacePageIterator it(space->ToSpaceStart(), space->ToSpaceEnd()); |
| |
| while (it.has_next()) { |
| Bitmap::Clear(it.next()); |
| } |
| } |
| |
| |
| void MarkCompactCollector::ClearMarkbits() { |
| ClearMarkbitsInPagedSpace(heap_->code_space()); |
| ClearMarkbitsInPagedSpace(heap_->map_space()); |
| ClearMarkbitsInPagedSpace(heap_->old_space()); |
| ClearMarkbitsInNewSpace(heap_->new_space()); |
| |
| LargeObjectIterator it(heap_->lo_space()); |
| for (HeapObject* obj = it.Next(); obj != NULL; obj = it.Next()) { |
| Marking::MarkWhite(Marking::MarkBitFrom(obj)); |
| Page::FromAddress(obj->address())->ResetProgressBar(); |
| Page::FromAddress(obj->address())->ResetLiveBytes(); |
| } |
| } |
| |
| |
| class MarkCompactCollector::SweeperTask : public v8::Task { |
| public: |
| SweeperTask(Heap* heap, PagedSpace* space) : heap_(heap), space_(space) {} |
| |
| virtual ~SweeperTask() {} |
| |
| private: |
| // v8::Task overrides. |
| void Run() override { |
| heap_->mark_compact_collector()->SweepInParallel(space_, 0); |
| heap_->mark_compact_collector()->pending_sweeper_jobs_semaphore_.Signal(); |
| } |
| |
| Heap* heap_; |
| PagedSpace* space_; |
| |
| DISALLOW_COPY_AND_ASSIGN(SweeperTask); |
| }; |
| |
| |
| void MarkCompactCollector::StartSweeperThreads() { |
| DCHECK(free_list_old_space_.get()->IsEmpty()); |
| DCHECK(free_list_code_space_.get()->IsEmpty()); |
| DCHECK(free_list_map_space_.get()->IsEmpty()); |
| V8::GetCurrentPlatform()->CallOnBackgroundThread( |
| new SweeperTask(heap(), heap()->old_space()), |
| v8::Platform::kShortRunningTask); |
| V8::GetCurrentPlatform()->CallOnBackgroundThread( |
| new SweeperTask(heap(), heap()->code_space()), |
| v8::Platform::kShortRunningTask); |
| V8::GetCurrentPlatform()->CallOnBackgroundThread( |
| new SweeperTask(heap(), heap()->map_space()), |
| v8::Platform::kShortRunningTask); |
| } |
| |
| |
| void MarkCompactCollector::SweepOrWaitUntilSweepingCompleted(Page* page) { |
| PagedSpace* owner = reinterpret_cast<PagedSpace*>(page->owner()); |
| if (!page->SweepingCompleted()) { |
| SweepInParallel(page, owner); |
| if (!page->SweepingCompleted()) { |
| // We were not able to sweep that page, i.e., a concurrent |
| // sweeper thread currently owns this page. Wait for the sweeper |
| // thread to be done with this page. |
| page->WaitUntilSweepingCompleted(); |
| } |
| } |
| } |
| |
| |
| void MarkCompactCollector::EnsureSweepingCompleted() { |
| DCHECK(sweeping_in_progress_ == true); |
| |
| // If sweeping is not completed or not running at all, we try to complete it |
| // here. |
| if (!heap()->concurrent_sweeping_enabled() || !IsSweepingCompleted()) { |
| SweepInParallel(heap()->paged_space(OLD_SPACE), 0); |
| SweepInParallel(heap()->paged_space(CODE_SPACE), 0); |
| SweepInParallel(heap()->paged_space(MAP_SPACE), 0); |
| } |
| |
| if (heap()->concurrent_sweeping_enabled()) { |
| pending_sweeper_jobs_semaphore_.Wait(); |
| pending_sweeper_jobs_semaphore_.Wait(); |
| pending_sweeper_jobs_semaphore_.Wait(); |
| } |
| |
| heap()->WaitUntilUnmappingOfFreeChunksCompleted(); |
| |
| ParallelSweepSpacesComplete(); |
| sweeping_in_progress_ = false; |
| RefillFreeList(heap()->paged_space(OLD_SPACE)); |
| RefillFreeList(heap()->paged_space(CODE_SPACE)); |
| RefillFreeList(heap()->paged_space(MAP_SPACE)); |
| heap()->paged_space(OLD_SPACE)->ResetUnsweptFreeBytes(); |
| heap()->paged_space(CODE_SPACE)->ResetUnsweptFreeBytes(); |
| heap()->paged_space(MAP_SPACE)->ResetUnsweptFreeBytes(); |
| |
| #ifdef VERIFY_HEAP |
| if (FLAG_verify_heap && !evacuation()) { |
| VerifyEvacuation(heap_); |
| } |
| #endif |
| } |
| |
| |
| bool MarkCompactCollector::IsSweepingCompleted() { |
| if (!pending_sweeper_jobs_semaphore_.WaitFor( |
| base::TimeDelta::FromSeconds(0))) { |
| return false; |
| } |
| pending_sweeper_jobs_semaphore_.Signal(); |
| return true; |
| } |
| |
| |
| void MarkCompactCollector::RefillFreeList(PagedSpace* space) { |
| FreeList* free_list; |
| |
| if (space == heap()->old_space()) { |
| free_list = free_list_old_space_.get(); |
| } else if (space == heap()->code_space()) { |
| free_list = free_list_code_space_.get(); |
| } else if (space == heap()->map_space()) { |
| free_list = free_list_map_space_.get(); |
| } else { |
| // Any PagedSpace might invoke RefillFreeLists, so we need to make sure |
| // to only refill them for the old space. |
| return; |
| } |
| |
| intptr_t freed_bytes = space->free_list()->Concatenate(free_list); |
| space->AddToAccountingStats(freed_bytes); |
| space->DecrementUnsweptFreeBytes(freed_bytes); |
| } |
| |
| |
| void Marking::TransferMark(Heap* heap, Address old_start, Address new_start) { |
| // This is only used when resizing an object. |
| DCHECK(MemoryChunk::FromAddress(old_start) == |
| MemoryChunk::FromAddress(new_start)); |
| |
| if (!heap->incremental_marking()->IsMarking()) return; |
| |
| // If the mark doesn't move, we don't check the color of the object. |
| // It doesn't matter whether the object is black, since it hasn't changed |
| // size, so the adjustment to the live data count will be zero anyway. |
| if (old_start == new_start) return; |
| |
| MarkBit new_mark_bit = MarkBitFrom(new_start); |
| MarkBit old_mark_bit = MarkBitFrom(old_start); |
| |
| #ifdef DEBUG |
| ObjectColor old_color = Color(old_mark_bit); |
| #endif |
| |
| if (Marking::IsBlack(old_mark_bit)) { |
| Marking::BlackToWhite(old_mark_bit); |
| Marking::MarkBlack(new_mark_bit); |
| return; |
| } else if (Marking::IsGrey(old_mark_bit)) { |
| Marking::GreyToWhite(old_mark_bit); |
| heap->incremental_marking()->WhiteToGreyAndPush( |
| HeapObject::FromAddress(new_start), new_mark_bit); |
| heap->incremental_marking()->RestartIfNotMarking(); |
| } |
| |
| #ifdef DEBUG |
| ObjectColor new_color = Color(new_mark_bit); |
| DCHECK(new_color == old_color); |
| #endif |
| } |
| |
| |
| const char* AllocationSpaceName(AllocationSpace space) { |
| switch (space) { |
| case NEW_SPACE: |
| return "NEW_SPACE"; |
| case OLD_SPACE: |
| return "OLD_SPACE"; |
| case CODE_SPACE: |
| return "CODE_SPACE"; |
| case MAP_SPACE: |
| return "MAP_SPACE"; |
| case LO_SPACE: |
| return "LO_SPACE"; |
| default: |
| UNREACHABLE(); |
| } |
| |
| return NULL; |
| } |
| |
| |
| void MarkCompactCollector::CollectEvacuationCandidates(PagedSpace* space) { |
| DCHECK(space->identity() == OLD_SPACE || space->identity() == CODE_SPACE); |
| |
| int number_of_pages = space->CountTotalPages(); |
| int area_size = space->AreaSize(); |
| |
| // Pairs of (live_bytes_in_page, page). |
| std::vector<std::pair<int, Page*> > pages; |
| pages.reserve(number_of_pages); |
| |
| PageIterator it(space); |
| while (it.has_next()) { |
| Page* p = it.next(); |
| if (p->NeverEvacuate()) continue; |
| if (p->IsFlagSet(Page::POPULAR_PAGE)) { |
| // This page had slots buffer overflow on previous GC, skip it. |
| p->ClearFlag(Page::POPULAR_PAGE); |
| continue; |
| } |
| // Invariant: Evacuation candidates are just created when marking is |
| // started. At the end of a GC all evacuation candidates are cleared and |
| // their slot buffers are released. |
| CHECK(!p->IsEvacuationCandidate()); |
| CHECK(p->slots_buffer() == NULL); |
| DCHECK(p->area_size() == area_size); |
| int live_bytes = |
| p->WasSwept() ? p->LiveBytesFromFreeList() : p->LiveBytes(); |
| pages.push_back(std::make_pair(live_bytes, p)); |
| } |
| |
| int candidate_count = 0; |
| int total_live_bytes = 0; |
| |
| bool reduce_memory = |
| heap()->ShouldReduceMemory() || heap()->HasLowAllocationRate(); |
| if (FLAG_manual_evacuation_candidates_selection) { |
| for (size_t i = 0; i < pages.size(); i++) { |
| Page* p = pages[i].second; |
| if (p->IsFlagSet(MemoryChunk::FORCE_EVACUATION_CANDIDATE_FOR_TESTING)) { |
| candidate_count++; |
| total_live_bytes += pages[i].first; |
| p->ClearFlag(MemoryChunk::FORCE_EVACUATION_CANDIDATE_FOR_TESTING); |
| AddEvacuationCandidate(p); |
| } |
| } |
| } else if (FLAG_stress_compaction) { |
| for (size_t i = 0; i < pages.size(); i++) { |
| Page* p = pages[i].second; |
| if (i % 2 == 0) { |
| candidate_count++; |
| total_live_bytes += pages[i].first; |
| AddEvacuationCandidate(p); |
| } |
| } |
| } else { |
| const int kTargetFragmentationPercent = 50; |
| const int kMaxEvacuatedBytes = 4 * Page::kPageSize; |
| |
| const int kTargetFragmentationPercentForReduceMemory = 20; |
| const int kMaxEvacuatedBytesForReduceMemory = 12 * Page::kPageSize; |
| |
| int max_evacuated_bytes; |
| int target_fragmentation_percent; |
| |
| if (reduce_memory) { |
| target_fragmentation_percent = kTargetFragmentationPercentForReduceMemory; |
| max_evacuated_bytes = kMaxEvacuatedBytesForReduceMemory; |
| } else { |
| target_fragmentation_percent = kTargetFragmentationPercent; |
| max_evacuated_bytes = kMaxEvacuatedBytes; |
| } |
| intptr_t free_bytes_threshold = |
| target_fragmentation_percent * (area_size / 100); |
| |
| // Sort pages from the most free to the least free, then select |
| // the first n pages for evacuation such that: |
| // - the total size of evacuated objects does not exceed the specified |
| // limit. |
| // - fragmentation of (n+1)-th page does not exceed the specified limit. |
| std::sort(pages.begin(), pages.end()); |
| for (size_t i = 0; i < pages.size(); i++) { |
| int live_bytes = pages[i].first; |
| int free_bytes = area_size - live_bytes; |
| if (FLAG_always_compact || |
| (free_bytes >= free_bytes_threshold && |
| total_live_bytes + live_bytes <= max_evacuated_bytes)) { |
| candidate_count++; |
| total_live_bytes += live_bytes; |
| } |
| if (FLAG_trace_fragmentation_verbose) { |
| PrintF( |
| "Page in %s: %d KB free [fragmented if this >= %d KB], " |
| "sum of live bytes in fragmented pages %d KB [max is %d KB]\n", |
| AllocationSpaceName(space->identity()), |
| static_cast<int>(free_bytes / KB), |
| static_cast<int>(free_bytes_threshold / KB), |
| static_cast<int>(total_live_bytes / KB), |
| static_cast<int>(max_evacuated_bytes / KB)); |
| } |
| } |
| // How many pages we will allocated for the evacuated objects |
| // in the worst case: ceil(total_live_bytes / area_size) |
| int estimated_new_pages = (total_live_bytes + area_size - 1) / area_size; |
| DCHECK_LE(estimated_new_pages, candidate_count); |
| int estimated_released_pages = candidate_count - estimated_new_pages; |
| // Avoid (compact -> expand) cycles. |
| if (estimated_released_pages == 0 && !FLAG_always_compact) |
| candidate_count = 0; |
| for (int i = 0; i < candidate_count; i++) { |
| AddEvacuationCandidate(pages[i].second); |
| } |
| } |
| |
| if (FLAG_trace_fragmentation) { |
| PrintF( |
| "Collected %d evacuation candidates [%d KB live] for space %s " |
| "[mode %s]\n", |
| candidate_count, static_cast<int>(total_live_bytes / KB), |
| AllocationSpaceName(space->identity()), |
| (reduce_memory ? "reduce memory footprint" : "normal")); |
| } |
| } |
| |
| |
| void MarkCompactCollector::AbortCompaction() { |
| if (compacting_) { |
| int npages = evacuation_candidates_.length(); |
| for (int i = 0; i < npages; i++) { |
| Page* p = evacuation_candidates_[i]; |
| slots_buffer_allocator_.DeallocateChain(p->slots_buffer_address()); |
| p->ClearEvacuationCandidate(); |
| p->ClearFlag(MemoryChunk::RESCAN_ON_EVACUATION); |
| } |
| compacting_ = false; |
| evacuation_candidates_.Rewind(0); |
| } |
| DCHECK_EQ(0, evacuation_candidates_.length()); |
| } |
| |
| |
| void MarkCompactCollector::Prepare() { |
| was_marked_incrementally_ = heap()->incremental_marking()->IsMarking(); |
| |
| #ifdef DEBUG |
| DCHECK(state_ == IDLE); |
| state_ = PREPARE_GC; |
| #endif |
| |
| DCHECK(!FLAG_never_compact || !FLAG_always_compact); |
| |
| if (sweeping_in_progress()) { |
| // Instead of waiting we could also abort the sweeper threads here. |
| EnsureSweepingCompleted(); |
| } |
| |
| // Clear marking bits if incremental marking is aborted. |
| if (was_marked_incrementally_ && heap_->ShouldAbortIncrementalMarking()) { |
| heap()->incremental_marking()->Stop(); |
| ClearMarkbits(); |
| AbortWeakCollections(); |
| AbortWeakCells(); |
| AbortCompaction(); |
| was_marked_incrementally_ = false; |
| } |
| |
| // Don't start compaction if we are in the middle of incremental |
| // marking cycle. We did not collect any slots. |
| if (!FLAG_never_compact && !was_marked_incrementally_) { |
| StartCompaction(NON_INCREMENTAL_COMPACTION); |
| } |
| |
| PagedSpaces spaces(heap()); |
| for (PagedSpace* space = spaces.next(); space != NULL; |
| space = spaces.next()) { |
| space->PrepareForMarkCompact(); |
| } |
| |
| #ifdef VERIFY_HEAP |
| if (!was_marked_incrementally_ && FLAG_verify_heap) { |
| VerifyMarkbitsAreClean(); |
| } |
| #endif |
| } |
| |
| |
| void MarkCompactCollector::Finish() { |
| #ifdef DEBUG |
| DCHECK(state_ == SWEEP_SPACES || state_ == RELOCATE_OBJECTS); |
| state_ = IDLE; |
| #endif |
| // The stub cache is not traversed during GC; clear the cache to |
| // force lazy re-initialization of it. This must be done after the |
| // GC, because it relies on the new address of certain old space |
| // objects (empty string, illegal builtin). |
| isolate()->stub_cache()->Clear(); |
| |
| if (have_code_to_deoptimize_) { |
| // Some code objects were marked for deoptimization during the GC. |
| Deoptimizer::DeoptimizeMarkedCode(isolate()); |
| have_code_to_deoptimize_ = false; |
| } |
| |
| heap_->incremental_marking()->ClearIdleMarkingDelayCounter(); |
| } |
| |
| |
| // ------------------------------------------------------------------------- |
| // Phase 1: tracing and marking live objects. |
| // before: all objects are in normal state. |
| // after: a live object's map pointer is marked as '00'. |
| |
| // Marking all live objects in the heap as part of mark-sweep or mark-compact |
| // collection. Before marking, all objects are in their normal state. After |
| // marking, live objects' map pointers are marked indicating that the object |
| // has been found reachable. |
| // |
| // The marking algorithm is a (mostly) depth-first (because of possible stack |
| // overflow) traversal of the graph of objects reachable from the roots. It |
| // uses an explicit stack of pointers rather than recursion. The young |
| // generation's inactive ('from') space is used as a marking stack. The |
| // objects in the marking stack are the ones that have been reached and marked |
| // but their children have not yet been visited. |
| // |
| // The marking stack can overflow during traversal. In that case, we set an |
| // overflow flag. When the overflow flag is set, we continue marking objects |
| // reachable from the objects on the marking stack, but no longer push them on |
| // the marking stack. Instead, we mark them as both marked and overflowed. |
| // When the stack is in the overflowed state, objects marked as overflowed |
| // have been reached and marked but their children have not been visited yet. |
| // After emptying the marking stack, we clear the overflow flag and traverse |
| // the heap looking for objects marked as overflowed, push them on the stack, |
| // and continue with marking. This process repeats until all reachable |
| // objects have been marked. |
| |
| void CodeFlusher::ProcessJSFunctionCandidates() { |
| Code* lazy_compile = isolate_->builtins()->builtin(Builtins::kCompileLazy); |
| Object* undefined = isolate_->heap()->undefined_value(); |
| |
| JSFunction* candidate = jsfunction_candidates_head_; |
| JSFunction* next_candidate; |
| while (candidate != NULL) { |
| next_candidate = GetNextCandidate(candidate); |
| ClearNextCandidate(candidate, undefined); |
| |
| SharedFunctionInfo* shared = candidate->shared(); |
| |
| Code* code = shared->code(); |
| MarkBit code_mark = Marking::MarkBitFrom(code); |
| if (Marking::IsWhite(code_mark)) { |
| if (FLAG_trace_code_flushing && shared->is_compiled()) { |
| PrintF("[code-flushing clears: "); |
| shared->ShortPrint(); |
| PrintF(" - age: %d]\n", code->GetAge()); |
| } |
| // Always flush the optimized code map if there is one. |
| if (!shared->optimized_code_map()->IsSmi()) { |
| shared->ClearOptimizedCodeMap(); |
| } |
| shared->set_code(lazy_compile); |
| candidate->set_code(lazy_compile); |
| } else { |
| DCHECK(Marking::IsBlack(code_mark)); |
| candidate->set_code(code); |
| } |
| |
| // We are in the middle of a GC cycle so the write barrier in the code |
| // setter did not record the slot update and we have to do that manually. |
| Address slot = candidate->address() + JSFunction::kCodeEntryOffset; |
| Code* target = Code::cast(Code::GetObjectFromEntryAddress(slot)); |
| isolate_->heap()->mark_compact_collector()->RecordCodeEntrySlot( |
| candidate, slot, target); |
| |
| Object** shared_code_slot = |
| HeapObject::RawField(shared, SharedFunctionInfo::kCodeOffset); |
| isolate_->heap()->mark_compact_collector()->RecordSlot( |
| shared, shared_code_slot, *shared_code_slot); |
| |
| candidate = next_candidate; |
| } |
| |
| jsfunction_candidates_head_ = NULL; |
| } |
| |
| |
| void CodeFlusher::ProcessSharedFunctionInfoCandidates() { |
| Code* lazy_compile = isolate_->builtins()->builtin(Builtins::kCompileLazy); |
| |
| SharedFunctionInfo* candidate = shared_function_info_candidates_head_; |
| SharedFunctionInfo* next_candidate; |
| while (candidate != NULL) { |
| next_candidate = GetNextCandidate(candidate); |
| ClearNextCandidate(candidate); |
| |
| Code* code = candidate->code(); |
| MarkBit code_mark = Marking::MarkBitFrom(code); |
| if (Marking::IsWhite(code_mark)) { |
| if (FLAG_trace_code_flushing && candidate->is_compiled()) { |
| PrintF("[code-flushing clears: "); |
| candidate->ShortPrint(); |
| PrintF(" - age: %d]\n", code->GetAge()); |
| } |
| // Always flush the optimized code map if there is one. |
| if (!candidate->optimized_code_map()->IsSmi()) { |
| candidate->ClearOptimizedCodeMap(); |
| } |
| candidate->set_code(lazy_compile); |
| } |
| |
| Object** code_slot = |
| HeapObject::RawField(candidate, SharedFunctionInfo::kCodeOffset); |
| isolate_->heap()->mark_compact_collector()->RecordSlot(candidate, code_slot, |
| *code_slot); |
| |
| candidate = next_candidate; |
| } |
| |
| shared_function_info_candidates_head_ = NULL; |
| } |
| |
| |
| void CodeFlusher::ProcessOptimizedCodeMaps() { |
| STATIC_ASSERT(SharedFunctionInfo::kEntryLength == 4); |
| |
| SharedFunctionInfo* holder = optimized_code_map_holder_head_; |
| SharedFunctionInfo* next_holder; |
| |
| while (holder != NULL) { |
| next_holder = GetNextCodeMap(holder); |
| ClearNextCodeMap(holder); |
| |
| // Process context-dependent entries in the optimized code map. |
| FixedArray* code_map = FixedArray::cast(holder->optimized_code_map()); |
| int new_length = SharedFunctionInfo::kEntriesStart; |
| int old_length = code_map->length(); |
| for (int i = SharedFunctionInfo::kEntriesStart; i < old_length; |
| i += SharedFunctionInfo::kEntryLength) { |
| // Each entry contains [ context, code, literals, ast-id ] as fields. |
| STATIC_ASSERT(SharedFunctionInfo::kEntryLength == 4); |
| Context* context = |
| Context::cast(code_map->get(i + SharedFunctionInfo::kContextOffset)); |
| Code* code = |
| Code::cast(code_map->get(i + SharedFunctionInfo::kCachedCodeOffset)); |
| FixedArray* literals = FixedArray::cast( |
| code_map->get(i + SharedFunctionInfo::kLiteralsOffset)); |
| Smi* ast_id = |
| Smi::cast(code_map->get(i + SharedFunctionInfo::kOsrAstIdOffset)); |
| if (Marking::IsWhite(Marking::MarkBitFrom(context))) continue; |
| DCHECK(Marking::IsBlack(Marking::MarkBitFrom(context))); |
| if (Marking::IsWhite(Marking::MarkBitFrom(code))) continue; |
| DCHECK(Marking::IsBlack(Marking::MarkBitFrom(code))); |
| if (Marking::IsWhite(Marking::MarkBitFrom(literals))) continue; |
| DCHECK(Marking::IsBlack(Marking::MarkBitFrom(literals))); |
| // Move every slot in the entry and record slots when needed. |
| code_map->set(new_length + SharedFunctionInfo::kCachedCodeOffset, code); |
| code_map->set(new_length + SharedFunctionInfo::kContextOffset, context); |
| code_map->set(new_length + SharedFunctionInfo::kLiteralsOffset, literals); |
| code_map->set(new_length + SharedFunctionInfo::kOsrAstIdOffset, ast_id); |
| Object** code_slot = code_map->RawFieldOfElementAt( |
| new_length + SharedFunctionInfo::kCachedCodeOffset); |
| isolate_->heap()->mark_compact_collector()->RecordSlot( |
| code_map, code_slot, *code_slot); |
| Object** context_slot = code_map->RawFieldOfElementAt( |
| new_length + SharedFunctionInfo::kContextOffset); |
| isolate_->heap()->mark_compact_collector()->RecordSlot( |
| code_map, context_slot, *context_slot); |
| Object** literals_slot = code_map->RawFieldOfElementAt( |
| new_length + SharedFunctionInfo::kLiteralsOffset); |
| isolate_->heap()->mark_compact_collector()->RecordSlot( |
| code_map, literals_slot, *literals_slot); |
| new_length += SharedFunctionInfo::kEntryLength; |
| } |
| |
| // Process context-independent entry in the optimized code map. |
| Object* shared_object = code_map->get(SharedFunctionInfo::kSharedCodeIndex); |
| if (shared_object->IsCode()) { |
| Code* shared_code = Code::cast(shared_object); |
| if (Marking::IsWhite(Marking::MarkBitFrom(shared_code))) { |
| code_map->set_undefined(SharedFunctionInfo::kSharedCodeIndex); |
| } else { |
| DCHECK(Marking::IsBlack(Marking::MarkBitFrom(shared_code))); |
| Object** slot = |
| code_map->RawFieldOfElementAt(SharedFunctionInfo::kSharedCodeIndex); |
| isolate_->heap()->mark_compact_collector()->RecordSlot(code_map, slot, |
| *slot); |
| } |
| } |
| |
| // Trim the optimized code map if entries have been removed. |
| if (new_length < old_length) { |
| holder->TrimOptimizedCodeMap(old_length - new_length); |
| } |
| |
| holder = next_holder; |
| } |
| |
| optimized_code_map_holder_head_ = NULL; |
| } |
| |
| |
| void CodeFlusher::EvictCandidate(SharedFunctionInfo* shared_info) { |
| // Make sure previous flushing decisions are revisited. |
| isolate_->heap()->incremental_marking()->RecordWrites(shared_info); |
| |
| if (FLAG_trace_code_flushing) { |
| PrintF("[code-flushing abandons function-info: "); |
| shared_info->ShortPrint(); |
| PrintF("]\n"); |
| } |
| |
| SharedFunctionInfo* candidate = shared_function_info_candidates_head_; |
| SharedFunctionInfo* next_candidate; |
| if (candidate == shared_info) { |
| next_candidate = GetNextCandidate(shared_info); |
| shared_function_info_candidates_head_ = next_candidate; |
| ClearNextCandidate(shared_info); |
| } else { |
| while (candidate != NULL) { |
| next_candidate = GetNextCandidate(candidate); |
| |
| if (next_candidate == shared_info) { |
| next_candidate = GetNextCandidate(shared_info); |
| SetNextCandidate(candidate, next_candidate); |
| ClearNextCandidate(shared_info); |
| break; |
| } |
| |
| candidate = next_candidate; |
| } |
| } |
| } |
| |
| |
| void CodeFlusher::EvictCandidate(JSFunction* function) { |
| DCHECK(!function->next_function_link()->IsUndefined()); |
| Object* undefined = isolate_->heap()->undefined_value(); |
| |
| // Make sure previous flushing decisions are revisited. |
| isolate_->heap()->incremental_marking()->RecordWrites(function); |
| isolate_->heap()->incremental_marking()->RecordWrites(function->shared()); |
| |
| if (FLAG_trace_code_flushing) { |
| PrintF("[code-flushing abandons closure: "); |
| function->shared()->ShortPrint(); |
| PrintF("]\n"); |
| } |
| |
| JSFunction* candidate = jsfunction_candidates_head_; |
| JSFunction* next_candidate; |
| if (candidate == function) { |
| next_candidate = GetNextCandidate(function); |
| jsfunction_candidates_head_ = next_candidate; |
| ClearNextCandidate(function, undefined); |
| } else { |
| while (candidate != NULL) { |
| next_candidate = GetNextCandidate(candidate); |
| |
| if (next_candidate == function) { |
| next_candidate = GetNextCandidate(function); |
| SetNextCandidate(candidate, next_candidate); |
| ClearNextCandidate(function, undefined); |
| break; |
| } |
| |
| candidate = next_candidate; |
| } |
| } |
| } |
| |
| |
| void CodeFlusher::EvictOptimizedCodeMap(SharedFunctionInfo* code_map_holder) { |
| FixedArray* code_map = |
| FixedArray::cast(code_map_holder->optimized_code_map()); |
| DCHECK(!code_map->get(SharedFunctionInfo::kNextMapIndex)->IsUndefined()); |
| |
| // Make sure previous flushing decisions are revisited. |
| isolate_->heap()->incremental_marking()->RecordWrites(code_map); |
| isolate_->heap()->incremental_marking()->RecordWrites(code_map_holder); |
| |
| if (FLAG_trace_code_flushing) { |
| PrintF("[code-flushing abandons code-map: "); |
| code_map_holder->ShortPrint(); |
| PrintF("]\n"); |
| } |
| |
| SharedFunctionInfo* holder = optimized_code_map_holder_head_; |
| SharedFunctionInfo* next_holder; |
| if (holder == code_map_holder) { |
| next_holder = GetNextCodeMap(code_map_holder); |
| optimized_code_map_holder_head_ = next_holder; |
| ClearNextCodeMap(code_map_holder); |
| } else { |
| while (holder != NULL) { |
| next_holder = GetNextCodeMap(holder); |
| |
| if (next_holder == code_map_holder) { |
| next_holder = GetNextCodeMap(code_map_holder); |
| SetNextCodeMap(holder, next_holder); |
| ClearNextCodeMap(code_map_holder); |
| break; |
| } |
| |
| holder = next_holder; |
| } |
| } |
| } |
| |
| |
| void CodeFlusher::EvictJSFunctionCandidates() { |
| JSFunction* candidate = jsfunction_candidates_head_; |
| JSFunction* next_candidate; |
| while (candidate != NULL) { |
| next_candidate = GetNextCandidate(candidate); |
| EvictCandidate(candidate); |
| candidate = next_candidate; |
| } |
| DCHECK(jsfunction_candidates_head_ == NULL); |
| } |
| |
| |
| void CodeFlusher::EvictSharedFunctionInfoCandidates() { |
| SharedFunctionInfo* candidate = shared_function_info_candidates_head_; |
| SharedFunctionInfo* next_candidate; |
| while (candidate != NULL) { |
| next_candidate = GetNextCandidate(candidate); |
| EvictCandidate(candidate); |
| candidate = next_candidate; |
| } |
| DCHECK(shared_function_info_candidates_head_ == NULL); |
| } |
| |
| |
| void CodeFlusher::EvictOptimizedCodeMaps() { |
| SharedFunctionInfo* holder = optimized_code_map_holder_head_; |
| SharedFunctionInfo* next_holder; |
| while (holder != NULL) { |
| next_holder = GetNextCodeMap(holder); |
| EvictOptimizedCodeMap(holder); |
| holder = next_holder; |
| } |
| DCHECK(optimized_code_map_holder_head_ == NULL); |
| } |
| |
| |
| void CodeFlusher::IteratePointersToFromSpace(ObjectVisitor* v) { |
| Heap* heap = isolate_->heap(); |
| |
| JSFunction** slot = &jsfunction_candidates_head_; |
| JSFunction* candidate = jsfunction_candidates_head_; |
| while (candidate != NULL) { |
| if (heap->InFromSpace(candidate)) { |
| v->VisitPointer(reinterpret_cast<Object**>(slot)); |
| } |
| candidate = GetNextCandidate(*slot); |
| slot = GetNextCandidateSlot(*slot); |
| } |
| } |
| |
| |
| MarkCompactCollector::~MarkCompactCollector() { |
| if (code_flusher_ != NULL) { |
| delete code_flusher_; |
| code_flusher_ = NULL; |
| } |
| } |
| |
| |
| class MarkCompactMarkingVisitor |
| : public StaticMarkingVisitor<MarkCompactMarkingVisitor> { |
| public: |
| static void ObjectStatsVisitBase(StaticVisitorBase::VisitorId id, Map* map, |
| HeapObject* obj); |
| |
| static void ObjectStatsCountFixedArray( |
| FixedArrayBase* fixed_array, FixedArraySubInstanceType fast_type, |
| FixedArraySubInstanceType dictionary_type); |
| |
| template <MarkCompactMarkingVisitor::VisitorId id> |
| class ObjectStatsTracker { |
| public: |
| static inline void Visit(Map* map, HeapObject* obj); |
| }; |
| |
| static void Initialize(); |
| |
| INLINE(static void VisitPointer(Heap* heap, HeapObject* object, Object** p)) { |
| MarkObjectByPointer(heap->mark_compact_collector(), object, p); |
| } |
| |
| INLINE(static void VisitPointers(Heap* heap, HeapObject* object, |
| Object** start, Object** end)) { |
| // Mark all objects pointed to in [start, end). |
| const int kMinRangeForMarkingRecursion = 64; |
| if (end - start >= kMinRangeForMarkingRecursion) { |
| if (VisitUnmarkedObjects(heap, object, start, end)) return; |
| // We are close to a stack overflow, so just mark the objects. |
| } |
| MarkCompactCollector* collector = heap->mark_compact_collector(); |
| for (Object** p = start; p < end; p++) { |
| MarkObjectByPointer(collector, object, p); |
| } |
| } |
| |
| // Marks the object black and pushes it on the marking stack. |
| INLINE(static void MarkObject(Heap* heap, HeapObject* object)) { |
| MarkBit mark = Marking::MarkBitFrom(object); |
| heap->mark_compact_collector()->MarkObject(object, mark); |
| } |
| |
| // 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, HeapObject* object)) { |
| MarkBit mark_bit = Marking::MarkBitFrom(object); |
| if (Marking::IsWhite(mark_bit)) { |
| heap->mark_compact_collector()->SetMark(object, mark_bit); |
| return true; |
| } |
| return false; |
| } |
| |
| // Mark object pointed to by p. |
| INLINE(static void MarkObjectByPointer(MarkCompactCollector* collector, |
| HeapObject* object, Object** p)) { |
| if (!(*p)->IsHeapObject()) return; |
| HeapObject* target_object = HeapObject::cast(*p); |
| collector->RecordSlot(object, p, target_object); |
| MarkBit mark = Marking::MarkBitFrom(target_object); |
| collector->MarkObject(target_object, mark); |
| } |
| |
| |
| // Visit an unmarked object. |
| INLINE(static void VisitUnmarkedObject(MarkCompactCollector* collector, |
| HeapObject* obj)) { |
| #ifdef DEBUG |
| DCHECK(collector->heap()->Contains(obj)); |
| DCHECK(!collector->heap()->mark_compact_collector()->IsMarked(obj)); |
| #endif |
| Map* map = obj->map(); |
| Heap* heap = obj->GetHeap(); |
| MarkBit mark = Marking::MarkBitFrom(obj); |
| heap->mark_compact_collector()->SetMark(obj, mark); |
| // Mark the map pointer and the body. |
| MarkBit map_mark = Marking::MarkBitFrom(map); |
| heap->mark_compact_collector()->MarkObject(map, map_mark); |
| IterateBody(map, obj); |
| } |
| |
| // Visit all unmarked objects pointed to by [start, end). |
| // Returns false if the operation fails (lack of stack space). |
| INLINE(static bool VisitUnmarkedObjects(Heap* heap, HeapObject* object, |
| Object** start, Object** end)) { |
| // Return false is we are close to the stack limit. |
| StackLimitCheck check(heap->isolate()); |
| if (check.HasOverflowed()) return false; |
| |
| MarkCompactCollector* collector = heap->mark_compact_collector(); |
| // Visit the unmarked objects. |
| for (Object** p = start; p < end; p++) { |
| Object* o = *p; |
| if (!o->IsHeapObject()) continue; |
| collector->RecordSlot(object, p, o); |
| HeapObject* obj = HeapObject::cast(o); |
| MarkBit mark = Marking::MarkBitFrom(obj); |
| if (Marking::IsBlackOrGrey(mark)) continue; |
| VisitUnmarkedObject(collector, obj); |
| } |
| return true; |
| } |
| |
| private: |
| template <int id> |
| static inline void TrackObjectStatsAndVisit(Map* map, HeapObject* obj); |
| |
| // Code flushing support. |
| |
| static const int kRegExpCodeThreshold = 5; |
| |
| static void UpdateRegExpCodeAgeAndFlush(Heap* heap, JSRegExp* re, |
| bool is_one_byte) { |
| // Make sure that the fixed array is in fact initialized on the RegExp. |
| // We could potentially trigger a GC when initializing the RegExp. |
| if (HeapObject::cast(re->data())->map()->instance_type() != |
| FIXED_ARRAY_TYPE) |
| return; |
| |
| // Make sure this is a RegExp that actually contains code. |
| if (re->TypeTag() != JSRegExp::IRREGEXP) return; |
| |
| Object* code = re->DataAt(JSRegExp::code_index(is_one_byte)); |
| if (!code->IsSmi() && |
| HeapObject::cast(code)->map()->instance_type() == CODE_TYPE) { |
| // Save a copy that can be reinstated if we need the code again. |
| re->SetDataAt(JSRegExp::saved_code_index(is_one_byte), code); |
| |
| // Saving a copy might create a pointer into compaction candidate |
| // that was not observed by marker. This might happen if JSRegExp data |
| // was marked through the compilation cache before marker reached JSRegExp |
| // object. |
| FixedArray* data = FixedArray::cast(re->data()); |
| Object** slot = |
| data->data_start() + JSRegExp::saved_code_index(is_one_byte); |
| heap->mark_compact_collector()->RecordSlot(data, slot, code); |
| |
| // Set a number in the 0-255 range to guarantee no smi overflow. |
| re->SetDataAt(JSRegExp::code_index(is_one_byte), |
| Smi::FromInt(heap->ms_count() & 0xff)); |
| } else if (code->IsSmi()) { |
| int value = Smi::cast(code)->value(); |
| // The regexp has not been compiled yet or there was a compilation error. |
| if (value == JSRegExp::kUninitializedValue || |
| value == JSRegExp::kCompilationErrorValue) { |
| return; |
| } |
| |
| // Check if we should flush now. |
| if (value == ((heap->ms_count() - kRegExpCodeThreshold) & 0xff)) { |
| re->SetDataAt(JSRegExp::code_index(is_one_byte), |
| Smi::FromInt(JSRegExp::kUninitializedValue)); |
| re->SetDataAt(JSRegExp::saved_code_index(is_one_byte), |
| Smi::FromInt(JSRegExp::kUninitializedValue)); |
| } |
| } |
| } |
| |
| |
| // Works by setting the current sweep_generation (as a smi) in the |
| // code object place in the data array of the RegExp and keeps a copy |
| // around that can be reinstated if we reuse the RegExp before flushing. |
| // If we did not use the code for kRegExpCodeThreshold mark sweep GCs |
| // we flush the code. |
| static void VisitRegExpAndFlushCode(Map* map, HeapObject* object) { |
| Heap* heap = map->GetHeap(); |
| MarkCompactCollector* collector = heap->mark_compact_collector(); |
| if (!collector->is_code_flushing_enabled()) { |
| VisitJSRegExp(map, object); |
| return; |
| } |
| JSRegExp* re = reinterpret_cast<JSRegExp*>(object); |
| // Flush code or set age on both one byte and two byte code. |
| UpdateRegExpCodeAgeAndFlush(heap, re, true); |
| UpdateRegExpCodeAgeAndFlush(heap, re, false); |
| // Visit the fields of the RegExp, including the updated FixedArray. |
| VisitJSRegExp(map, object); |
| } |
| |
| static VisitorDispatchTable<Callback> non_count_table_; |
| }; |
| |
| |
| void MarkCompactMarkingVisitor::ObjectStatsCountFixedArray( |
| FixedArrayBase* fixed_array, FixedArraySubInstanceType fast_type, |
| FixedArraySubInstanceType dictionary_type) { |
| Heap* heap = fixed_array->map()->GetHeap(); |
| if (fixed_array->map() != heap->fixed_cow_array_map() && |
| fixed_array->map() != heap->fixed_double_array_map() && |
| fixed_array != heap->empty_fixed_array()) { |
| if (fixed_array->IsDictionary()) { |
| heap->RecordFixedArraySubTypeStats(dictionary_type, fixed_array->Size()); |
| } else { |
| heap->RecordFixedArraySubTypeStats(fast_type, fixed_array->Size()); |
| } |
| } |
| } |
| |
| |
| void MarkCompactMarkingVisitor::ObjectStatsVisitBase( |
| MarkCompactMarkingVisitor::VisitorId id, Map* map, HeapObject* obj) { |
| Heap* heap = map->GetHeap(); |
| int object_size = obj->Size(); |
| heap->RecordObjectStats(map->instance_type(), object_size); |
| non_count_table_.GetVisitorById(id)(map, obj); |
| if (obj->IsJSObject()) { |
| JSObject* object = JSObject::cast(obj); |
| ObjectStatsCountFixedArray(object->elements(), DICTIONARY_ELEMENTS_SUB_TYPE, |
| FAST_ELEMENTS_SUB_TYPE); |
| ObjectStatsCountFixedArray(object->properties(), |
| DICTIONARY_PROPERTIES_SUB_TYPE, |
| FAST_PROPERTIES_SUB_TYPE); |
| } |
| } |
| |
| |
| template <MarkCompactMarkingVisitor::VisitorId id> |
| void MarkCompactMarkingVisitor::ObjectStatsTracker<id>::Visit(Map* map, |
| HeapObject* obj) { |
| ObjectStatsVisitBase(id, map, obj); |
| } |
| |
| |
| template <> |
| class MarkCompactMarkingVisitor::ObjectStatsTracker< |
| MarkCompactMarkingVisitor::kVisitMap> { |
| public: |
| static inline void Visit(Map* map, HeapObject* obj) { |
| Heap* heap = map->GetHeap(); |
| Map* map_obj = Map::cast(obj); |
| DCHECK(map->instance_type() == MAP_TYPE); |
| DescriptorArray* array = map_obj->instance_descriptors(); |
| if (map_obj->owns_descriptors() && |
| array != heap->empty_descriptor_array()) { |
| int fixed_array_size = array->Size(); |
| heap->RecordFixedArraySubTypeStats(DESCRIPTOR_ARRAY_SUB_TYPE, |
| fixed_array_size); |
| } |
| if (TransitionArray::IsFullTransitionArray(map_obj->raw_transitions())) { |
| int fixed_array_size = |
| TransitionArray::cast(map_obj->raw_transitions())->Size(); |
| heap->RecordFixedArraySubTypeStats(TRANSITION_ARRAY_SUB_TYPE, |
| fixed_array_size); |
| } |
| if (map_obj->has_code_cache()) { |
| CodeCache* cache = CodeCache::cast(map_obj->code_cache()); |
| heap->RecordFixedArraySubTypeStats(MAP_CODE_CACHE_SUB_TYPE, |
| cache->default_cache()->Size()); |
| if (!cache->normal_type_cache()->IsUndefined()) { |
| heap->RecordFixedArraySubTypeStats( |
| MAP_CODE_CACHE_SUB_TYPE, |
| FixedArray::cast(cache->normal_type_cache())->Size()); |
| } |
| } |
| ObjectStatsVisitBase(kVisitMap, map, obj); |
| } |
| }; |
| |
| |
| template <> |
| class MarkCompactMarkingVisitor::ObjectStatsTracker< |
| MarkCompactMarkingVisitor::kVisitCode> { |
| public: |
| static inline void Visit(Map* map, HeapObject* obj) { |
| Heap* heap = map->GetHeap(); |
| int object_size = obj->Size(); |
| DCHECK(map->instance_type() == CODE_TYPE); |
| Code* code_obj = Code::cast(obj); |
| heap->RecordCodeSubTypeStats(code_obj->kind(), code_obj->GetAge(), |
| object_size); |
| ObjectStatsVisitBase(kVisitCode, map, obj); |
| } |
| }; |
| |
| |
| template <> |
| class MarkCompactMarkingVisitor::ObjectStatsTracker< |
| MarkCompactMarkingVisitor::kVisitSharedFunctionInfo> { |
| public: |
| static inline void Visit(Map* map, HeapObject* obj) { |
| Heap* heap = map->GetHeap(); |
| SharedFunctionInfo* sfi = SharedFunctionInfo::cast(obj); |
| if (sfi->scope_info() != heap->empty_fixed_array()) { |
| heap->RecordFixedArraySubTypeStats( |
| SCOPE_INFO_SUB_TYPE, FixedArray::cast(sfi->scope_info())->Size()); |
| } |
| ObjectStatsVisitBase(kVisitSharedFunctionInfo, map, obj); |
| } |
| }; |
| |
| |
| template <> |
| class MarkCompactMarkingVisitor::ObjectStatsTracker< |
| MarkCompactMarkingVisitor::kVisitFixedArray> { |
| public: |
| static inline void Visit(Map* map, HeapObject* obj) { |
| Heap* heap = map->GetHeap(); |
| FixedArray* fixed_array = FixedArray::cast(obj); |
| if (fixed_array == heap->string_table()) { |
| heap->RecordFixedArraySubTypeStats(STRING_TABLE_SUB_TYPE, |
| fixed_array->Size()); |
| } |
| ObjectStatsVisitBase(kVisitFixedArray, map, obj); |
| } |
| }; |
| |
| |
| void MarkCompactMarkingVisitor::Initialize() { |
| StaticMarkingVisitor<MarkCompactMarkingVisitor>::Initialize(); |
| |
| table_.Register(kVisitJSRegExp, &VisitRegExpAndFlushCode); |
| |
| if (FLAG_track_gc_object_stats) { |
| // Copy the visitor table to make call-through possible. |
| non_count_table_.CopyFrom(&table_); |
| #define VISITOR_ID_COUNT_FUNCTION(id) \ |
| table_.Register(kVisit##id, ObjectStatsTracker<kVisit##id>::Visit); |
| VISITOR_ID_LIST(VISITOR_ID_COUNT_FUNCTION) |
| #undef VISITOR_ID_COUNT_FUNCTION |
| } |
| } |
| |
| |
| VisitorDispatchTable<MarkCompactMarkingVisitor::Callback> |
| MarkCompactMarkingVisitor::non_count_table_; |
| |
| |
| class CodeMarkingVisitor : public ThreadVisitor { |
| public: |
| explicit CodeMarkingVisitor(MarkCompactCollector* collector) |
| : collector_(collector) {} |
| |
| void VisitThread(Isolate* isolate, ThreadLocalTop* top) { |
| collector_->PrepareThreadForCodeFlushing(isolate, top); |
| } |
| |
| private: |
| MarkCompactCollector* collector_; |
| }; |
| |
| |
| class SharedFunctionInfoMarkingVisitor : public ObjectVisitor { |
| public: |
| explicit SharedFunctionInfoMarkingVisitor(MarkCompactCollector* collector) |
| : collector_(collector) {} |
| |
| void VisitPointers(Object** start, Object** end) { |
| for (Object** p = start; p < end; p++) VisitPointer(p); |
| } |
| |
| void VisitPointer(Object** slot) { |
| Object* obj = *slot; |
| if (obj->IsSharedFunctionInfo()) { |
| SharedFunctionInfo* shared = reinterpret_cast<SharedFunctionInfo*>(obj); |
| MarkBit shared_mark = Marking::MarkBitFrom(shared); |
| MarkBit code_mark = Marking::MarkBitFrom(shared->code()); |
| collector_->MarkObject(shared->code(), code_mark); |
| collector_->MarkObject(shared, shared_mark); |
| } |
| } |
| |
| private: |
| MarkCompactCollector* collector_; |
| }; |
| |
| |
| void MarkCompactCollector::PrepareThreadForCodeFlushing(Isolate* isolate, |
| ThreadLocalTop* top) { |
| for (StackFrameIterator it(isolate, top); !it.done(); it.Advance()) { |
| // Note: for the frame that has a pending lazy deoptimization |
| // StackFrame::unchecked_code will return a non-optimized code object for |
| // the outermost function and StackFrame::LookupCode will return |
| // actual optimized code object. |
| StackFrame* frame = it.frame(); |
| Code* code = frame->unchecked_code(); |
| MarkBit code_mark = Marking::MarkBitFrom(code); |
| MarkObject(code, code_mark); |
| if (frame->is_optimized()) { |
| MarkCompactMarkingVisitor::MarkInlinedFunctionsCode(heap(), |
| frame->LookupCode()); |
| } |
| } |
| } |
| |
| |
| void MarkCompactCollector::PrepareForCodeFlushing() { |
| // If code flushing is disabled, there is no need to prepare for it. |
| if (!is_code_flushing_enabled()) return; |
| |
| // Ensure that empty descriptor array is marked. Method MarkDescriptorArray |
| // relies on it being marked before any other descriptor array. |
| HeapObject* descriptor_array = heap()->empty_descriptor_array(); |
| MarkBit descriptor_array_mark = Marking::MarkBitFrom(descriptor_array); |
| MarkObject(descriptor_array, descriptor_array_mark); |
| |
| // Make sure we are not referencing the code from the stack. |
| DCHECK(this == heap()->mark_compact_collector()); |
| PrepareThreadForCodeFlushing(heap()->isolate(), |
| heap()->isolate()->thread_local_top()); |
| |
| // Iterate the archived stacks in all threads to check if |
| // the code is referenced. |
| CodeMarkingVisitor code_marking_visitor(this); |
| heap()->isolate()->thread_manager()->IterateArchivedThreads( |
| &code_marking_visitor); |
| |
| SharedFunctionInfoMarkingVisitor visitor(this); |
| heap()->isolate()->compilation_cache()->IterateFunctions(&visitor); |
| heap()->isolate()->handle_scope_implementer()->Iterate(&visitor); |
| |
| ProcessMarkingDeque(); |
| } |
| |
| |
| // Visitor class for marking heap roots. |
| class RootMarkingVisitor : public ObjectVisitor { |
| public: |
| explicit RootMarkingVisitor(Heap* heap) |
| : collector_(heap->mark_compact_collector()) {} |
| |
| void VisitPointer(Object** p) { MarkObjectByPointer(p); } |
| |
| void VisitPointers(Object** start, Object** end) { |
| for (Object** p = start; p < end; p++) MarkObjectByPointer(p); |
| } |
| |
| // Skip the weak next code link in a code object, which is visited in |
| // ProcessTopOptimizedFrame. |
| void VisitNextCodeLink(Object** p) {} |
| |
| private: |
| void MarkObjectByPointer(Object** p) { |
| if (!(*p)->IsHeapObject()) return; |
| |
| // Replace flat cons strings in place. |
| HeapObject* object = HeapObject::cast(*p); |
| MarkBit mark_bit = Marking::MarkBitFrom(object); |
| if (Marking::IsBlackOrGrey(mark_bit)) return; |
| |
| Map* map = object->map(); |
| // Mark the object. |
| collector_->SetMark(object, mark_bit); |
| |
| // Mark the map pointer and body, and push them on the marking stack. |
| MarkBit map_mark = Marking::MarkBitFrom(map); |
| collector_->MarkObject(map, map_mark); |
| MarkCompactMarkingVisitor::IterateBody(map, object); |
| |
| // Mark all the objects reachable from the map and body. May leave |
| // overflowed objects in the heap. |
| collector_->EmptyMarkingDeque(); |
| } |
| |
| MarkCompactCollector* collector_; |
| }; |
| |
| |
| // Helper class for pruning the string table. |
| template <bool finalize_external_strings> |
| class StringTableCleaner : public ObjectVisitor { |
| public: |
| explicit StringTableCleaner(Heap* heap) : heap_(heap), pointers_removed_(0) {} |
| |
| virtual void VisitPointers(Object** start, Object** end) { |
| // Visit all HeapObject pointers in [start, end). |
| for (Object** p = start; p < end; p++) { |
| Object* o = *p; |
| if (o->IsHeapObject() && |
| Marking::IsWhite(Marking::MarkBitFrom(HeapObject::cast(o)))) { |
| if (finalize_external_strings) { |
| DCHECK(o->IsExternalString()); |
| heap_->FinalizeExternalString(String::cast(*p)); |
| } else { |
| pointers_removed_++; |
| } |
| // Set the entry to the_hole_value (as deleted). |
| *p = heap_->the_hole_value(); |
| } |
| } |
| } |
| |
| int PointersRemoved() { |
| DCHECK(!finalize_external_strings); |
| return pointers_removed_; |
| } |
| |
| private: |
| Heap* heap_; |
| int pointers_removed_; |
| }; |
| |
| |
| typedef StringTableCleaner<false> InternalizedStringTableCleaner; |
| typedef StringTableCleaner<true> ExternalStringTableCleaner; |
| |
| |
| // Implementation of WeakObjectRetainer for mark compact GCs. All marked objects |
| // are retained. |
| class MarkCompactWeakObjectRetainer : public WeakObjectRetainer { |
| public: |
| virtual Object* RetainAs(Object* object) { |
| if (Marking::IsBlackOrGrey( |
| Marking::MarkBitFrom(HeapObject::cast(object)))) { |
| return object; |
| } else if (object->IsAllocationSite() && |
| !(AllocationSite::cast(object)->IsZombie())) { |
| // "dead" AllocationSites need to live long enough for a traversal of new |
| // space. These sites get a one-time reprieve. |
| AllocationSite* site = AllocationSite::cast(object); |
| site->MarkZombie(); |
| site->GetHeap()->mark_compact_collector()->MarkAllocationSite(site); |
| return object; |
| } else { |
| return NULL; |
| } |
| } |
| }; |
| |
| |
| // Fill the marking stack with overflowed objects returned by the given |
| // iterator. Stop when the marking stack is filled or the end of the space |
| // is reached, whichever comes first. |
| template <class T> |
| void MarkCompactCollector::DiscoverGreyObjectsWithIterator(T* it) { |
| // The caller should ensure that the marking stack is initially not full, |
| // so that we don't waste effort pointlessly scanning for objects. |
| DCHECK(!marking_deque()->IsFull()); |
| |
| Map* filler_map = heap()->one_pointer_filler_map(); |
| for (HeapObject* object = it->Next(); object != NULL; object = it->Next()) { |
| MarkBit markbit = Marking::MarkBitFrom(object); |
| if ((object->map() != filler_map) && Marking::IsGrey(markbit)) { |
| Marking::GreyToBlack(markbit); |
| PushBlack(object); |
| if (marking_deque()->IsFull()) return; |
| } |
| } |
| } |
| |
| |
| static inline int MarkWordToObjectStarts(uint32_t mark_bits, int* starts); |
| |
| |
| void MarkCompactCollector::DiscoverGreyObjectsOnPage(MemoryChunk* p) { |
| DCHECK(!marking_deque()->IsFull()); |
| DCHECK(strcmp(Marking::kWhiteBitPattern, "00") == 0); |
| DCHECK(strcmp(Marking::kBlackBitPattern, "10") == 0); |
| DCHECK(strcmp(Marking::kGreyBitPattern, "11") == 0); |
| DCHECK(strcmp(Marking::kImpossibleBitPattern, "01") == 0); |
| |
| for (MarkBitCellIterator it(p); !it.Done(); it.Advance()) { |
| Address cell_base = it.CurrentCellBase(); |
| MarkBit::CellType* cell = it.CurrentCell(); |
| |
| const MarkBit::CellType current_cell = *cell; |
| if (current_cell == 0) continue; |
| |
| MarkBit::CellType grey_objects; |
| if (it.HasNext()) { |
| const MarkBit::CellType next_cell = *(cell + 1); |
| grey_objects = current_cell & ((current_cell >> 1) | |
| (next_cell << (Bitmap::kBitsPerCell - 1))); |
| } else { |
| grey_objects = current_cell & (current_cell >> 1); |
| } |
| |
| int offset = 0; |
| while (grey_objects != 0) { |
| int trailing_zeros = base::bits::CountTrailingZeros32(grey_objects); |
| grey_objects >>= trailing_zeros; |
| offset += trailing_zeros; |
| MarkBit markbit(cell, 1 << offset); |
| DCHECK(Marking::IsGrey(markbit)); |
| Marking::GreyToBlack(markbit); |
| Address addr = cell_base + offset * kPointerSize; |
| HeapObject* object = HeapObject::FromAddress(addr); |
| PushBlack(object); |
| if (marking_deque()->IsFull()) return; |
| offset += 2; |
| grey_objects >>= 2; |
| } |
| |
| grey_objects >>= (Bitmap::kBitsPerCell - 1); |
| } |
| } |
| |
| |
| int MarkCompactCollector::DiscoverAndEvacuateBlackObjectsOnPage( |
| NewSpace* new_space, NewSpacePage* p) { |
| DCHECK(strcmp(Marking::kWhiteBitPattern, "00") == 0); |
| DCHECK(strcmp(Marking::kBlackBitPattern, "10") == 0); |
| DCHECK(strcmp(Marking::kGreyBitPattern, "11") == 0); |
| DCHECK(strcmp(Marking::kImpossibleBitPattern, "01") == 0); |
| |
| MarkBit::CellType* cells = p->markbits()->cells(); |
| int survivors_size = 0; |
| |
| for (MarkBitCellIterator it(p); !it.Done(); it.Advance()) { |
| Address cell_base = it.CurrentCellBase(); |
| MarkBit::CellType* cell = it.CurrentCell(); |
| |
| MarkBit::CellType current_cell = *cell; |
| if (current_cell == 0) continue; |
| |
| int offset = 0; |
| while (current_cell != 0) { |
| int trailing_zeros = base::bits::CountTrailingZeros32(current_cell); |
| current_cell >>= trailing_zeros; |
| offset += trailing_zeros; |
| Address address = cell_base + offset * kPointerSize; |
| HeapObject* object = HeapObject::FromAddress(address); |
| DCHECK(Marking::IsBlack(Marking::MarkBitFrom(object))); |
| |
| int size = object->Size(); |
| survivors_size += size; |
| |
| Heap::UpdateAllocationSiteFeedback(object, Heap::RECORD_SCRATCHPAD_SLOT); |
| |
| offset += 2; |
| current_cell >>= 2; |
| |
| // TODO(hpayer): Refactor EvacuateObject and call this function instead. |
| if (heap()->ShouldBePromoted(object->address(), size) && |
| TryPromoteObject(object, size)) { |
| continue; |
| } |
| |
| AllocationAlignment alignment = object->RequiredAlignment(); |
| AllocationResult allocation = new_space->AllocateRaw(size, alignment); |
| if (allocation.IsRetry()) { |
| if (!new_space->AddFreshPage()) { |
| // Shouldn't happen. We are sweeping linearly, and to-space |
| // has the same number of pages as from-space, so there is |
| // always room. |
| UNREACHABLE(); |
| } |
| allocation = new_space->AllocateRaw(size, alignment); |
| DCHECK(!allocation.IsRetry()); |
| } |
| Object* target = allocation.ToObjectChecked(); |
| |
| MigrateObject(HeapObject::cast(target), object, size, NEW_SPACE); |
| heap()->IncrementSemiSpaceCopiedObjectSize(size); |
| } |
| *cells = 0; |
| } |
| return survivors_size; |
| } |
| |
| |
| void MarkCompactCollector::DiscoverGreyObjectsInSpace(PagedSpace* space) { |
| PageIterator it(space); |
| while (it.has_next()) { |
| Page* p = it.next(); |
| DiscoverGreyObjectsOnPage(p); |
| if (marking_deque()->IsFull()) return; |
| } |
| } |
| |
| |
| void MarkCompactCollector::DiscoverGreyObjectsInNewSpace() { |
| NewSpace* space = heap()->new_space(); |
| NewSpacePageIterator it(space->bottom(), space->top()); |
| while (it.has_next()) { |
| NewSpacePage* page = it.next(); |
| DiscoverGreyObjectsOnPage(page); |
| if (marking_deque()->IsFull()) return; |
| } |
| } |
| |
| |
| bool MarkCompactCollector::IsUnmarkedHeapObject(Object** p) { |
| Object* o = *p; |
| if (!o->IsHeapObject()) return false; |
| HeapObject* heap_object = HeapObject::cast(o); |
| MarkBit mark = Marking::MarkBitFrom(heap_object); |
| return Marking::IsWhite(mark); |
| } |
| |
| |
| bool MarkCompactCollector::IsUnmarkedHeapObjectWithHeap(Heap* heap, |
| Object** p) { |
| Object* o = *p; |
| DCHECK(o->IsHeapObject()); |
| HeapObject* heap_object = HeapObject::cast(o); |
| MarkBit mark = Marking::MarkBitFrom(heap_object); |
| return Marking::IsWhite(mark); |
| } |
| |
| |
| void MarkCompactCollector::MarkStringTable(RootMarkingVisitor* visitor) { |
| StringTable* string_table = heap()->string_table(); |
| // Mark the string table itself. |
| MarkBit string_table_mark = Marking::MarkBitFrom(string_table); |
| if (Marking::IsWhite(string_table_mark)) { |
| // String table could have already been marked by visiting the handles list. |
| SetMark(string_table, string_table_mark); |
| } |
| // Explicitly mark the prefix. |
| string_table->IteratePrefix(visitor); |
| ProcessMarkingDeque(); |
| } |
| |
| |
| void MarkCompactCollector::MarkAllocationSite(AllocationSite* site) { |
| MarkBit mark_bit = Marking::MarkBitFrom(site); |
| SetMark(site, mark_bit); |
| } |
| |
| |
| void MarkCompactCollector::MarkRoots(RootMarkingVisitor* visitor) { |
| // Mark the heap roots including global variables, stack variables, |
| // etc., and all objects reachable from them. |
| heap()->IterateStrongRoots(visitor, VISIT_ONLY_STRONG); |
| |
| // Handle the string table specially. |
| MarkStringTable(visitor); |
| |
| // There may be overflowed objects in the heap. Visit them now. |
| while (marking_deque_.overflowed()) { |
| RefillMarkingDeque(); |
| EmptyMarkingDeque(); |
| } |
| } |
| |
| |
| void MarkCompactCollector::MarkImplicitRefGroups( |
| MarkObjectFunction mark_object) { |
| List<ImplicitRefGroup*>* ref_groups = |
| isolate()->global_handles()->implicit_ref_groups(); |
| |
| int last = 0; |
| for (int i = 0; i < ref_groups->length(); i++) { |
| ImplicitRefGroup* entry = ref_groups->at(i); |
| DCHECK(entry != NULL); |
| |
| if (!IsMarked(*entry->parent)) { |
| (*ref_groups)[last++] = entry; |
| continue; |
| } |
| |
| Object*** children = entry->children; |
| // A parent object is marked, so mark all child heap objects. |
| for (size_t j = 0; j < entry->length; ++j) { |
| if ((*children[j])->IsHeapObject()) { |
| mark_object(heap(), HeapObject::cast(*children[j])); |
| } |
| } |
| |
| // Once the entire group has been marked, dispose it because it's |
| // not needed anymore. |
| delete entry; |
| } |
| ref_groups->Rewind(last); |
| } |
| |
| |
| // Mark all objects reachable from the objects on the marking stack. |
| // Before: the marking stack contains zero or more heap object pointers. |
| // After: the marking stack is empty, and all objects reachable from the |
| // marking stack have been marked, or are overflowed in the heap. |
| void MarkCompactCollector::EmptyMarkingDeque() { |
| Map* filler_map = heap_->one_pointer_filler_map(); |
| while (!marking_deque_.IsEmpty()) { |
| HeapObject* object = marking_deque_.Pop(); |
| // Explicitly skip one word fillers. Incremental markbit patterns are |
| // correct only for objects that occupy at least two words. |
| Map* map = object->map(); |
| if (map == filler_map) continue; |
| |
| DCHECK(object->IsHeapObject()); |
| DCHECK(heap()->Contains(object)); |
| DCHECK(!Marking::IsWhite(Marking::MarkBitFrom(object))); |
| |
| MarkBit map_mark = Marking::MarkBitFrom(map); |
| MarkObject(map, map_mark); |
| |
| MarkCompactMarkingVisitor::IterateBody(map, object); |
| } |
| } |
| |
| |
| // Sweep the heap for overflowed objects, clear their overflow bits, and |
| // push them on the marking stack. Stop early if the marking stack fills |
| // before sweeping completes. If sweeping completes, there are no remaining |
| // overflowed objects in the heap so the overflow flag on the markings stack |
| // is cleared. |
| void MarkCompactCollector::RefillMarkingDeque() { |
| isolate()->CountUsage(v8::Isolate::UseCounterFeature::kMarkDequeOverflow); |
| DCHECK(marking_deque_.overflowed()); |
| |
| DiscoverGreyObjectsInNewSpace(); |
| if (marking_deque_.IsFull()) return; |
| |
| DiscoverGreyObjectsInSpace(heap()->old_space()); |
| if (marking_deque_.IsFull()) return; |
| |
| DiscoverGreyObjectsInSpace(heap()->code_space()); |
| if (marking_deque_.IsFull()) return; |
| |
| DiscoverGreyObjectsInSpace(heap()->map_space()); |
| if (marking_deque_.IsFull()) return; |
| |
| LargeObjectIterator lo_it(heap()->lo_space()); |
| DiscoverGreyObjectsWithIterator(&lo_it); |
| if (marking_deque_.IsFull()) return; |
| |
| marking_deque_.ClearOverflowed(); |
| } |
| |
| |
| // Mark all objects reachable (transitively) from objects on the marking |
| // stack. Before: the marking stack contains zero or more heap object |
| // pointers. After: the marking stack is empty and there are no overflowed |
| // objects in the heap. |
| void MarkCompactCollector::ProcessMarkingDeque() { |
| EmptyMarkingDeque(); |
| while (marking_deque_.overflowed()) { |
| RefillMarkingDeque(); |
| EmptyMarkingDeque(); |
| } |
| } |
| |
| |
| // Mark all objects reachable (transitively) from objects on the marking |
| // stack including references only considered in the atomic marking pause. |
| void MarkCompactCollector::ProcessEphemeralMarking( |
| ObjectVisitor* visitor, bool only_process_harmony_weak_collections) { |
| bool work_to_do = true; |
| DCHECK(marking_deque_.IsEmpty() && !marking_deque_.overflowed()); |
| while (work_to_do) { |
| if (!only_process_harmony_weak_collections) { |
| isolate()->global_handles()->IterateObjectGroups( |
| visitor, &IsUnmarkedHeapObjectWithHeap); |
| MarkImplicitRefGroups(&MarkCompactMarkingVisitor::MarkObject); |
| } |
| ProcessWeakCollections(); |
| work_to_do = !marking_deque_.IsEmpty(); |
| ProcessMarkingDeque(); |
| } |
| } |
| |
| |
| void MarkCompactCollector::ProcessTopOptimizedFrame(ObjectVisitor* visitor) { |
| for (StackFrameIterator it(isolate(), isolate()->thread_local_top()); |
| !it.done(); it.Advance()) { |
| if (it.frame()->type() == StackFrame::JAVA_SCRIPT) { |
| return; |
| } |
| if (it.frame()->type() == StackFrame::OPTIMIZED) { |
| Code* code = it.frame()->LookupCode(); |
| if (!code->CanDeoptAt(it.frame()->pc())) { |
| code->CodeIterateBody(visitor); |
| } |
| ProcessMarkingDeque(); |
| return; |
| } |
| } |
| } |
| |
| |
| void MarkCompactCollector::RetainMaps() { |
| if (heap()->ShouldReduceMemory() || heap()->ShouldAbortIncrementalMarking() || |
| FLAG_retain_maps_for_n_gc == 0) { |
| // Do not retain dead maps if flag disables it or there is |
| // - memory pressure (reduce_memory_footprint_), |
| // - GC is requested by tests or dev-tools (abort_incremental_marking_). |
| return; |
| } |
| |
| ArrayList* retained_maps = heap()->retained_maps(); |
| int length = retained_maps->Length(); |
| int new_length = 0; |
| for (int i = 0; i < length; i += 2) { |
| DCHECK(retained_maps->Get(i)->IsWeakCell()); |
| WeakCell* cell = WeakCell::cast(retained_maps->Get(i)); |
| if (cell->cleared()) continue; |
| int age = Smi::cast(retained_maps->Get(i + 1))->value(); |
| int new_age; |
| Map* map = Map::cast(cell->value()); |
| MarkBit map_mark = Marking::MarkBitFrom(map); |
| if (Marking::IsWhite(map_mark)) { |
| if (age == 0) { |
| // The map has aged. Do not retain this map. |
| continue; |
| } |
| Object* constructor = map->GetConstructor(); |
| if (!constructor->IsHeapObject() || Marking::IsWhite(Marking::MarkBitFrom( |
| HeapObject::cast(constructor)))) { |
| // The constructor is dead, no new objects with this map can |
| // be created. Do not retain this map. |
| continue; |
| } |
| Object* prototype = map->prototype(); |
| if (prototype->IsHeapObject() && |
| Marking::IsWhite(Marking::MarkBitFrom(HeapObject::cast(prototype)))) { |
| // The prototype is not marked, age the map. |
| new_age = age - 1; |
| } else { |
| // The prototype and the constructor are marked, this map keeps only |
| // transition tree alive, not JSObjects. Do not age the map. |
| new_age = age; |
| } |
| MarkObject(map, map_mark); |
| } else { |
| new_age = FLAG_retain_maps_for_n_gc; |
| } |
| if (i != new_length) { |
| retained_maps->Set(new_length, cell); |
| Object** slot = retained_maps->Slot(new_length); |
| RecordSlot(retained_maps, slot, cell); |
| retained_maps->Set(new_length + 1, Smi::FromInt(new_age)); |
| } else if (new_age != age) { |
| retained_maps->Set(new_length + 1, Smi::FromInt(new_age)); |
| } |
| new_length += 2; |
| } |
| Object* undefined = heap()->undefined_value(); |
| for (int i = new_length; i < length; i++) { |
| retained_maps->Clear(i, undefined); |
| } |
| if (new_length != length) retained_maps->SetLength(new_length); |
| ProcessMarkingDeque(); |
| } |
| |
| |
| void MarkCompactCollector::EnsureMarkingDequeIsReserved() { |
| DCHECK(!marking_deque_.in_use()); |
| if (marking_deque_memory_ == NULL) { |
| marking_deque_memory_ = new base::VirtualMemory(kMaxMarkingDequeSize); |
| marking_deque_memory_committed_ = 0; |
| } |
| if (marking_deque_memory_ == NULL) { |
| V8::FatalProcessOutOfMemory("EnsureMarkingDequeIsReserved"); |
| } |
| } |
| |
| |
| void MarkCompactCollector::EnsureMarkingDequeIsCommitted(size_t max_size) { |
| // If the marking deque is too small, we try to allocate a bigger one. |
| // If that fails, make do with a smaller one. |
| CHECK(!marking_deque_.in_use()); |
| for (size_t size = max_size; size >= kMinMarkingDequeSize; size >>= 1) { |
| base::VirtualMemory* memory = marking_deque_memory_; |
| size_t currently_committed = marking_deque_memory_committed_; |
| |
| if (currently_committed == size) return; |
| |
| if (currently_committed > size) { |
| bool success = marking_deque_memory_->Uncommit( |
| reinterpret_cast<Address>(marking_deque_memory_->address()) + size, |
| currently_committed - size); |
| if (success) { |
| marking_deque_memory_committed_ = size; |
| return; |
| } |
| UNREACHABLE(); |
| } |
| |
| bool success = memory->Commit( |
| reinterpret_cast<Address>(memory->address()) + currently_committed, |
| size - currently_committed, |
| false); // Not executable. |
| if (success) { |
| marking_deque_memory_committed_ = size; |
| return; |
| } |
| } |
| V8::FatalProcessOutOfMemory("EnsureMarkingDequeIsCommitted"); |
| } |
| |
| |
| void MarkCompactCollector::InitializeMarkingDeque() { |
| DCHECK(!marking_deque_.in_use()); |
| DCHECK(marking_deque_memory_committed_ > 0); |
| Address addr = static_cast<Address>(marking_deque_memory_->address()); |
| size_t size = marking_deque_memory_committed_; |
| if (FLAG_force_marking_deque_overflows) size = 64 * kPointerSize; |
| marking_deque_.Initialize(addr, addr + size); |
| } |
| |
| |
| void MarkingDeque::Initialize(Address low, Address high) { |
| DCHECK(!in_use_); |
| HeapObject** obj_low = reinterpret_cast<HeapObject**>(low); |
| HeapObject** obj_high = reinterpret_cast<HeapObject**>(high); |
| array_ = obj_low; |
| mask_ = base::bits::RoundDownToPowerOfTwo32( |
| static_cast<uint32_t>(obj_high - obj_low)) - |
| 1; |
| top_ = bottom_ = 0; |
| overflowed_ = false; |
| in_use_ = true; |
| } |
| |
| |
| void MarkingDeque::Uninitialize(bool aborting) { |
| if (!aborting) { |
| DCHECK(IsEmpty()); |
| DCHECK(!overflowed_); |
| } |
| DCHECK(in_use_); |
| top_ = bottom_ = 0xdecbad; |
| in_use_ = false; |
| } |
| |
| |
| void MarkCompactCollector::MarkLiveObjects() { |
| GCTracer::Scope gc_scope(heap()->tracer(), GCTracer::Scope::MC_MARK); |
| double start_time = 0.0; |
| if (FLAG_print_cumulative_gc_stat) { |
| start_time = base::OS::TimeCurrentMillis(); |
| } |
| // The recursive GC marker detects when it is nearing stack overflow, |
| // and switches to a different marking system. JS interrupts interfere |
| // with the C stack limit check. |
| PostponeInterruptsScope postpone(isolate()); |
| |
| IncrementalMarking* incremental_marking = heap_->incremental_marking(); |
| if (was_marked_incrementally_) { |
| incremental_marking->Finalize(); |
| } else { |
| // Abort any pending incremental activities e.g. incremental sweeping. |
| incremental_marking->Stop(); |
| if (marking_deque_.in_use()) { |
| marking_deque_.Uninitialize(true); |
| } |
| } |
| |
| #ifdef DEBUG |
| DCHECK(state_ == PREPARE_GC); |
| state_ = MARK_LIVE_OBJECTS; |
| #endif |
| |
| EnsureMarkingDequeIsCommittedAndInitialize( |
| MarkCompactCollector::kMaxMarkingDequeSize); |
| |
| PrepareForCodeFlushing(); |
| |
| RootMarkingVisitor root_visitor(heap()); |
| MarkRoots(&root_visitor); |
| |
| ProcessTopOptimizedFrame(&root_visitor); |
| |
| // Retaining dying maps should happen before or during ephemeral marking |
| // because a map could keep the key of an ephemeron alive. Note that map |
| // aging is imprecise: maps that are kept alive only by ephemerons will age. |
| RetainMaps(); |
| |
| { |
| GCTracer::Scope gc_scope(heap()->tracer(), GCTracer::Scope::MC_WEAKCLOSURE); |
| |
| // The objects reachable from the roots are marked, yet unreachable |
| // objects are unmarked. Mark objects reachable due to host |
| // application specific logic or through Harmony weak maps. |
| ProcessEphemeralMarking(&root_visitor, false); |
| |
| // The objects reachable from the roots, weak maps or object groups |
| // are marked. Objects pointed to only by weak global handles cannot be |
| // immediately reclaimed. Instead, we have to mark them as pending and mark |
| // objects reachable from them. |
| // |
| // First we identify nonlive weak handles and mark them as pending |
| // destruction. |
| heap()->isolate()->global_handles()->IdentifyWeakHandles( |
| &IsUnmarkedHeapObject); |
| // Then we mark the objects. |
| heap()->isolate()->global_handles()->IterateWeakRoots(&root_visitor); |
| ProcessMarkingDeque(); |
| |
| // Repeat Harmony weak maps marking to mark unmarked objects reachable from |
| // the weak roots we just marked as pending destruction. |
| // |
| // We only process harmony collections, as all object groups have been fully |
| // processed and no weakly reachable node can discover new objects groups. |
| ProcessEphemeralMarking(&root_visitor, true); |
| } |
| |
| AfterMarking(); |
| |
| if (FLAG_print_cumulative_gc_stat) { |
| heap_->tracer()->AddMarkingTime(base::OS::TimeCurrentMillis() - start_time); |
| } |
| } |
| |
| |
| void MarkCompactCollector::AfterMarking() { |
| // Prune the string table removing all strings only pointed to by the |
| // string table. Cannot use string_table() here because the string |
| // table is marked. |
| StringTable* string_table = heap()->string_table(); |
| InternalizedStringTableCleaner internalized_visitor(heap()); |
| string_table->IterateElements(&internalized_visitor); |
| string_table->ElementsRemoved(internalized_visitor.PointersRemoved()); |
| |
| ExternalStringTableCleaner external_visitor(heap()); |
| heap()->external_string_table_.Iterate(&external_visitor); |
| heap()->external_string_table_.CleanUp(); |
| |
| // Process the weak references. |
| MarkCompactWeakObjectRetainer mark_compact_object_retainer; |
| heap()->ProcessAllWeakReferences(&mark_compact_object_retainer); |
| |
| // Remove object groups after marking phase. |
| heap()->isolate()->global_handles()->RemoveObjectGroups(); |
| heap()->isolate()->global_handles()->RemoveImplicitRefGroups(); |
| |
| // Flush code from collected candidates. |
| if (is_code_flushing_enabled()) { |
| code_flusher_->ProcessCandidates(); |
| } |
| |
| if (FLAG_track_gc_object_stats) { |
| if (FLAG_trace_gc_object_stats) { |
| heap()->TraceObjectStats(); |
| } |
| heap()->CheckpointObjectStats(); |
| } |
| } |
| |
| |
| void MarkCompactCollector::ClearNonLiveReferences() { |
| // Iterate over the map space, setting map transitions that go from |
| // a marked map to an unmarked map to null transitions. This action |
| // is carried out only on maps of JSObjects and related subtypes. |
| HeapObjectIterator map_iterator(heap()->map_space()); |
| for (HeapObject* obj = map_iterator.Next(); obj != NULL; |
| obj = map_iterator.Next()) { |
| Map* map = Map::cast(obj); |
| |
| if (!map->CanTransition()) continue; |
| |
| MarkBit map_mark = Marking::MarkBitFrom(map); |
| ClearNonLivePrototypeTransitions(map); |
| ClearNonLiveMapTransitions(map, map_mark); |
| |
| if (Marking::IsWhite(map_mark)) { |
| have_code_to_deoptimize_ |= |
| map->dependent_code()->MarkCodeForDeoptimization( |
| isolate(), DependentCode::kWeakCodeGroup); |
| map->set_dependent_code(DependentCode::cast(heap()->empty_fixed_array())); |
| } |
| } |
| |
| WeakHashTable* table = heap_->weak_object_to_code_table(); |
| uint32_t capacity = table->Capacity(); |
| for (uint32_t i = 0; i < capacity; i++) { |
| uint32_t key_index = table->EntryToIndex(i); |
| Object* key = table->get(key_index); |
| if (!table->IsKey(key)) continue; |
| uint32_t value_index = table->EntryToValueIndex(i); |
| Object* value = table->get(value_index); |
| DCHECK(key->IsWeakCell()); |
| if (WeakCell::cast(key)->cleared()) { |
| have_code_to_deoptimize_ |= |
| DependentCode::cast(value)->MarkCodeForDeoptimization( |
| isolate(), DependentCode::kWeakCodeGroup); |
| table->set(key_index, heap_->the_hole_value()); |
| table->set(value_index, heap_->the_hole_value()); |
| table->ElementRemoved(); |
| } |
| } |
| } |
| |
| |
| void MarkCompactCollector::ClearNonLivePrototypeTransitions(Map* map) { |
| FixedArray* prototype_transitions = |
| TransitionArray::GetPrototypeTransitions(map); |
| int number_of_transitions = |
| TransitionArray::NumberOfPrototypeTransitions(prototype_transitions); |
| |
| const int header = TransitionArray::kProtoTransitionHeaderSize; |
| int new_number_of_transitions = 0; |
| for (int i = 0; i < number_of_transitions; i++) { |
| Object* cell = prototype_transitions->get(header + i); |
| if (!WeakCell::cast(cell)->cleared()) { |
| if (new_number_of_transitions != i) { |
| prototype_transitions->set(header + new_number_of_transitions, cell); |
| Object** slot = prototype_transitions->RawFieldOfElementAt( |
| header + new_number_of_transitions); |
| RecordSlot(prototype_transitions, slot, cell); |
| } |
| new_number_of_transitions++; |
| } |
| } |
| |
| if (new_number_of_transitions != number_of_transitions) { |
| TransitionArray::SetNumberOfPrototypeTransitions(prototype_transitions, |
| new_number_of_transitions); |
| } |
| |
| // Fill slots that became free with undefined value. |
| for (int i = new_number_of_transitions; i < number_of_transitions; i++) { |
| prototype_transitions->set_undefined(header + i); |
| } |
| } |
| |
| |
| void MarkCompactCollector::ClearNonLiveMapTransitions(Map* map, |
| MarkBit map_mark) { |
| Object* potential_parent = map->GetBackPointer(); |
| if (!potential_parent->IsMap()) return; |
| Map* parent = Map::cast(potential_parent); |
| |
| // Follow back pointer, check whether we are dealing with a map transition |
| // from a live map to a dead path and in case clear transitions of parent. |
| bool current_is_alive = Marking::IsBlackOrGrey(map_mark); |
| bool parent_is_alive = Marking::IsBlackOrGrey(Marking::MarkBitFrom(parent)); |
| if (!current_is_alive && parent_is_alive) { |
| ClearMapTransitions(parent, map); |
| } |
| } |
| |
| |
| // Clear a possible back pointer in case the transition leads to a dead map. |
| // Return true in case a back pointer has been cleared and false otherwise. |
| bool MarkCompactCollector::ClearMapBackPointer(Map* target) { |
| if (Marking::IsBlackOrGrey(Marking::MarkBitFrom(target))) return false; |
| target->SetBackPointer(heap_->undefined_value(), SKIP_WRITE_BARRIER); |
| return true; |
| } |
| |
| |
| void MarkCompactCollector::ClearMapTransitions(Map* map, Map* dead_transition) { |
| Object* transitions = map->raw_transitions(); |
| int num_transitions = TransitionArray::NumberOfTransitions(transitions); |
| |
| int number_of_own_descriptors = map->NumberOfOwnDescriptors(); |
| DescriptorArray* descriptors = map->instance_descriptors(); |
| |
| // A previously existing simple transition (stored in a WeakCell) may have |
| // been cleared. Clear the useless cell pointer, and take ownership |
| // of the descriptor array. |
| if (transitions->IsWeakCell() && WeakCell::cast(transitions)->cleared()) { |
| map->set_raw_transitions(Smi::FromInt(0)); |
| } |
| if (num_transitions == 0 && |
| descriptors == dead_transition->instance_descriptors() && |
| number_of_own_descriptors > 0) { |
| TrimDescriptorArray(map, descriptors, number_of_own_descriptors); |
| DCHECK(descriptors->number_of_descriptors() == number_of_own_descriptors); |
| map->set_owns_descriptors(true); |
| return; |
| } |
| |
| int transition_index = 0; |
| |
| bool descriptors_owner_died = false; |
| |
| // Compact all live descriptors to the left. |
| for (int i = 0; i < num_transitions; ++i) { |
| Map* target = TransitionArray::GetTarget(transitions, i); |
| if (ClearMapBackPointer(target)) { |
| if (target->instance_descriptors() == descriptors) { |
| descriptors_owner_died = true; |
| } |
| } else { |
| if (i != transition_index) { |
| DCHECK(TransitionArray::IsFullTransitionArray(transitions)); |
| TransitionArray* t = TransitionArray::cast(transitions); |
| Name* key = t->GetKey(i); |
| t->SetKey(transition_index, key); |
| Object** key_slot = t->GetKeySlot(transition_index); |
| RecordSlot(t, key_slot, key); |
| // Target slots do not need to be recorded since maps are not compacted. |
| t->SetTarget(transition_index, t->GetTarget(i)); |
| } |
| transition_index++; |
| } |
| } |
| |
| // If there are no transitions to be cleared, return. |
| // TODO(verwaest) Should be an assert, otherwise back pointers are not |
| // properly cleared. |
| if (transition_index == num_transitions) return; |
| |
| if (descriptors_owner_died) { |
| if (number_of_own_descriptors > 0) { |
| TrimDescriptorArray(map, descriptors, number_of_own_descriptors); |
| DCHECK(descriptors->number_of_descriptors() == number_of_own_descriptors); |
| map->set_owns_descriptors(true); |
| } else { |
| DCHECK(descriptors == heap_->empty_descriptor_array()); |
| } |
| } |
| |
| // Note that we never eliminate a transition array, though we might right-trim |
| // such that number_of_transitions() == 0. If this assumption changes, |
| // TransitionArray::Insert() will need to deal with the case that a transition |
| // array disappeared during GC. |
| int trim = TransitionArray::Capacity(transitions) - transition_index; |
| if (trim > 0) { |
| // Non-full-TransitionArray cases can never reach this point. |
| DCHECK(TransitionArray::IsFullTransitionArray(transitions)); |
| TransitionArray* t = TransitionArray::cast(transitions); |
| heap_->RightTrimFixedArray<Heap::SEQUENTIAL_TO_SWEEPER>( |
| t, trim * TransitionArray::kTransitionSize); |
| t->SetNumberOfTransitions(transition_index); |
| // The map still has a full transition array. |
| DCHECK(TransitionArray::IsFullTransitionArray(map->raw_transitions())); |
| } |
| } |
| |
| |
| void MarkCompactCollector::TrimDescriptorArray(Map* map, |
| DescriptorArray* descriptors, |
| int number_of_own_descriptors) { |
| int number_of_descriptors = descriptors->number_of_descriptors_storage(); |
| int to_trim = number_of_descriptors - number_of_own_descriptors; |
| if (to_trim == 0) return; |
| |
| heap_->RightTrimFixedArray<Heap::SEQUENTIAL_TO_SWEEPER>( |
| descriptors, to_trim * DescriptorArray::kDescriptorSize); |
| descriptors->SetNumberOfDescriptors(number_of_own_descriptors); |
| |
| if (descriptors->HasEnumCache()) TrimEnumCache(map, descriptors); |
| descriptors->Sort(); |
| |
| if (FLAG_unbox_double_fields) { |
| LayoutDescriptor* layout_descriptor = map->layout_descriptor(); |
| layout_descriptor = layout_descriptor->Trim(heap_, map, descriptors, |
| number_of_own_descriptors); |
| SLOW_DCHECK(layout_descriptor->IsConsistentWithMap(map, true)); |
| } |
| } |
| |
| |
| void MarkCompactCollector::TrimEnumCache(Map* map, |
| DescriptorArray* descriptors) { |
| int live_enum = map->EnumLength(); |
| if (live_enum == kInvalidEnumCacheSentinel) { |
| live_enum = map->NumberOfDescribedProperties(OWN_DESCRIPTORS, DONT_ENUM); |
| } |
| if (live_enum == 0) return descriptors->ClearEnumCache(); |
| |
| FixedArray* enum_cache = descriptors->GetEnumCache(); |
| |
| int to_trim = enum_cache->length() - live_enum; |
| if (to_trim <= 0) return; |
| heap_->RightTrimFixedArray<Heap::SEQUENTIAL_TO_SWEEPER>( |
| descriptors->GetEnumCache(), to_trim); |
| |
| if (!descriptors->HasEnumIndicesCache()) return; |
| FixedArray* enum_indices_cache = descriptors->GetEnumIndicesCache(); |
| heap_->RightTrimFixedArray<Heap::SEQUENTIAL_TO_SWEEPER>(enum_indices_cache, |
| to_trim); |
| } |
| |
| |
| void MarkCompactCollector::ProcessWeakCollections() { |
| GCTracer::Scope gc_scope(heap()->tracer(), |
| GCTracer::Scope::MC_WEAKCOLLECTION_PROCESS); |
| Object* weak_collection_obj = heap()->encountered_weak_collections(); |
| while (weak_collection_obj != Smi::FromInt(0)) { |
| JSWeakCollection* weak_collection = |
| reinterpret_cast<JSWeakCollection*>(weak_collection_obj); |
| DCHECK(MarkCompactCollector::IsMarked(weak_collection)); |
| if (weak_collection->table()->IsHashTable()) { |
| ObjectHashTable* table = ObjectHashTable::cast(weak_collection->table()); |
| for (int i = 0; i < table->Capacity(); i++) { |
| if (MarkCompactCollector::IsMarked(HeapObject::cast(table->KeyAt(i)))) { |
| Object** key_slot = |
| table->RawFieldOfElementAt(ObjectHashTable::EntryToIndex(i)); |
| RecordSlot(table, key_slot, *key_slot); |
| Object** value_slot = |
| table->RawFieldOfElementAt(ObjectHashTable::EntryToValueIndex(i)); |
| MarkCompactMarkingVisitor::MarkObjectByPointer(this, table, |
| value_slot); |
| } |
| } |
| } |
| weak_collection_obj = weak_collection->next(); |
| } |
| } |
| |
| |
| void MarkCompactCollector::ClearWeakCollections() { |
| GCTracer::Scope gc_scope(heap()->tracer(), |
| GCTracer::Scope::MC_WEAKCOLLECTION_CLEAR); |
| Object* weak_collection_obj = heap()->encountered_weak_collections(); |
| while (weak_collection_obj != Smi::FromInt(0)) { |
| JSWeakCollection* weak_collection = |
| reinterpret_cast<JSWeakCollection*>(weak_collection_obj); |
| DCHECK(MarkCompactCollector::IsMarked(weak_collection)); |
| if (weak_collection->table()->IsHashTable()) { |
| ObjectHashTable* table = ObjectHashTable::cast(weak_collection->table()); |
| for (int i = 0; i < table->Capacity(); i++) { |
| HeapObject* key = HeapObject::cast(table->KeyAt(i)); |
| if (!MarkCompactCollector::IsMarked(key)) { |
| table->RemoveEntry(i); |
| } |
| } |
| } |
| weak_collection_obj = weak_collection->next(); |
| weak_collection->set_next(heap()->undefined_value()); |
| } |
| heap()->set_encountered_weak_collections(Smi::FromInt(0)); |
| } |
| |
| |
| void MarkCompactCollector::AbortWeakCollections() { |
| GCTracer::Scope gc_scope(heap()->tracer(), |
| GCTracer::Scope::MC_WEAKCOLLECTION_ABORT); |
| Object* weak_collection_obj = heap()->encountered_weak_collections(); |
| while (weak_collection_obj != Smi::FromInt(0)) { |
| JSWeakCollection* weak_collection = |
| reinterpret_cast<JSWeakCollection*>(weak_collection_obj); |
| weak_collection_obj = weak_collection->next(); |
| weak_collection->set_next(heap()->undefined_value()); |
| } |
| heap()->set_encountered_weak_collections(Smi::FromInt(0)); |
| } |
| |
| |
| void MarkCompactCollector::ProcessAndClearWeakCells() { |
| Object* weak_cell_obj = heap()->encountered_weak_cells(); |
| while (weak_cell_obj != Smi::FromInt(0)) { |
| WeakCell* weak_cell = reinterpret_cast<WeakCell*>(weak_cell_obj); |
| // We do not insert cleared weak cells into the list, so the value |
| // cannot be a Smi here. |
| HeapObject* value = HeapObject::cast(weak_cell->value()); |
| if (!MarkCompactCollector::IsMarked(value)) { |
| // Cells for new-space objects embedded in optimized code are wrapped in |
| // WeakCell and put into Heap::weak_object_to_code_table. |
| // Such cells do not have any strong references but we want to keep them |
| // alive as long as the cell value is alive. |
| // TODO(ulan): remove this once we remove Heap::weak_object_to_code_table. |
| if (value->IsCell()) { |
| Object* cell_value = Cell::cast(value)->value(); |
| if (cell_value->IsHeapObject() && |
| MarkCompactCollector::IsMarked(HeapObject::cast(cell_value))) { |
| // Resurrect the cell. |
| MarkBit mark = Marking::MarkBitFrom(value); |
| SetMark(value, mark); |
| Object** slot = HeapObject::RawField(value, Cell::kValueOffset); |
| RecordSlot(value, slot, *slot); |
| slot = HeapObject::RawField(weak_cell, WeakCell::kValueOffset); |
| RecordSlot(weak_cell, slot, *slot); |
| } else { |
| weak_cell->clear(); |
| } |
| } else { |
| weak_cell->clear(); |
| } |
| } else { |
| Object** slot = HeapObject::RawField(weak_cell, WeakCell::kValueOffset); |
| RecordSlot(weak_cell, slot, *slot); |
| } |
| weak_cell_obj = weak_cell->next(); |
| weak_cell->clear_next(heap()); |
| } |
| heap()->set_encountered_weak_cells(Smi::FromInt(0)); |
| } |
| |
| |
| void MarkCompactCollector::AbortWeakCells() { |
| Object* weak_cell_obj = heap()->encountered_weak_cells(); |
| while (weak_cell_obj != Smi::FromInt(0)) { |
| WeakCell* weak_cell = reinterpret_cast<WeakCell*>(weak_cell_obj); |
| weak_cell_obj = weak_cell->next(); |
| weak_cell->clear_next(heap()); |
| } |
| heap()->set_encountered_weak_cells(Smi::FromInt(0)); |
| } |
| |
| |
| void MarkCompactCollector::RecordMigratedSlot(Object* value, Address slot) { |
| if (heap_->InNewSpace(value)) { |
| heap_->store_buffer()->Mark(slot); |
| } else if (value->IsHeapObject() && IsOnEvacuationCandidate(value)) { |
| SlotsBuffer::AddTo(&slots_buffer_allocator_, &migration_slots_buffer_, |
| reinterpret_cast<Object**>(slot), |
| SlotsBuffer::IGNORE_OVERFLOW); |
| } |
| } |
| |
| |
| // We scavenge new space simultaneously with sweeping. This is done in two |
| // passes. |
| // |
| // The first pass migrates all alive objects from one semispace to another or |
| // promotes them to old space. Forwarding address is written directly into |
| // first word of object without any encoding. If object is dead we write |
| // NULL as a forwarding address. |
| // |
| // The second pass updates pointers to new space in all spaces. It is possible |
| // to encounter pointers to dead new space objects during traversal of pointers |
| // to new space. We should clear them to avoid encountering them during next |
| // pointer iteration. This is an issue if the store buffer overflows and we |
| // have to scan the entire old space, including dead objects, looking for |
| // pointers to new space. |
| void MarkCompactCollector::MigrateObject(HeapObject* dst, HeapObject* src, |
| int size, AllocationSpace dest) { |
| Address dst_addr = dst->address(); |
| Address src_addr = src->address(); |
| DCHECK(heap()->AllowedToBeMigrated(src, dest)); |
| DCHECK(dest != LO_SPACE && size <= Page::kMaxRegularHeapObjectSize); |
| if (dest == OLD_SPACE) { |
| DCHECK(IsAligned(size, kPointerSize)); |
| switch (src->ContentType()) { |
| case HeapObjectContents::kTaggedValues: |
| MigrateObjectTagged(dst, src, size); |
| break; |
| |
| case HeapObjectContents::kMixedValues: |
| MigrateObjectMixed(dst, src, size); |
| break; |
| |
| case HeapObjectContents::kRawValues: |
| MigrateObjectRaw(dst, src, size); |
| break; |
| } |
| |
| if (compacting_ && dst->IsJSFunction()) { |
| Address code_entry_slot = dst->address() + JSFunction::kCodeEntryOffset; |
| Address code_entry = Memory::Address_at(code_entry_slot); |
| |
| if (Page::FromAddress(code_entry)->IsEvacuationCandidate()) { |
| SlotsBuffer::AddTo(&slots_buffer_allocator_, &migration_slots_buffer_, |
| SlotsBuffer::CODE_ENTRY_SLOT, code_entry_slot, |
| SlotsBuffer::IGNORE_OVERFLOW); |
| } |
| } |
| } else if (dest == CODE_SPACE) { |
| PROFILE(isolate(), CodeMoveEvent(src_addr, dst_addr)); |
| heap()->MoveBlock(dst_addr, src_addr, size); |
| SlotsBuffer::AddTo(&slots_buffer_allocator_, &migration_slots_buffer_, |
| SlotsBuffer::RELOCATED_CODE_OBJECT, dst_addr, |
| SlotsBuffer::IGNORE_OVERFLOW); |
| Code::cast(dst)->Relocate(dst_addr - src_addr); |
| } else { |
| DCHECK(dest == NEW_SPACE); |
| heap()->MoveBlock(dst_addr, src_addr, size); |
| } |
| heap()->OnMoveEvent(dst, src, size); |
| Memory::Address_at(src_addr) = dst_addr; |
| } |
| |
| |
| void MarkCompactCollector::MigrateObjectTagged(HeapObject* dst, HeapObject* src, |
| int size) { |
| Address src_slot = src->address(); |
| Address dst_slot = dst->address(); |
| for (int remaining = size / kPointerSize; remaining > 0; remaining--) { |
| Object* value = Memory::Object_at(src_slot); |
| Memory::Object_at(dst_slot) = value; |
| RecordMigratedSlot(value, dst_slot); |
| src_slot += kPointerSize; |
| dst_slot += kPointerSize; |
| } |
| } |
| |
| |
| void MarkCompactCollector::MigrateObjectMixed(HeapObject* dst, HeapObject* src, |
| int size) { |
| if (src->IsFixedTypedArrayBase()) { |
| heap()->MoveBlock(dst->address(), src->address(), size); |
| Address base_pointer_slot = |
| dst->address() + FixedTypedArrayBase::kBasePointerOffset; |
| RecordMigratedSlot(Memory::Object_at(base_pointer_slot), base_pointer_slot); |
| } else if (FLAG_unbox_double_fields) { |
| Address dst_addr = dst->address(); |
| Address src_addr = src->address(); |
| Address src_slot = src_addr; |
| Address dst_slot = dst_addr; |
| |
| LayoutDescriptorHelper helper(src->map()); |
| DCHECK(!helper.all_fields_tagged()); |
| for (int remaining = size / kPointerSize; remaining > 0; remaining--) { |
| Object* value = Memory::Object_at(src_slot); |
| |
| Memory::Object_at(dst_slot) = value; |
| |
| if (helper.IsTagged(static_cast<int>(src_slot - src_addr))) { |
| RecordMigratedSlot(value, dst_slot); |
| } |
| |
| src_slot += kPointerSize; |
| dst_slot += kPointerSize; |
| } |
| } else { |
| UNREACHABLE(); |
| } |
| } |
| |
| |
| void MarkCompactCollector::MigrateObjectRaw(HeapObject* dst, HeapObject* src, |
| int size) { |
| heap()->MoveBlock(dst->address(), src->address(), size); |
| } |
| |
| |
| // Visitor for updating pointers from live objects in old spaces to new space. |
| // It does not expect to encounter pointers to dead objects. |
| class PointersUpdatingVisitor : public ObjectVisitor { |
| public: |
| explicit PointersUpdatingVisitor(Heap* heap) : heap_(heap) {} |
| |
| void VisitPointer(Object** p) { UpdatePointer(p); } |
| |
| void VisitPointers(Object** start, Object** end) { |
| for (Object** p = start; p < end; p++) UpdatePointer(p); |
| } |
| |
| void VisitCell(RelocInfo* rinfo) { |
| DCHECK(rinfo->rmode() == RelocInfo::CELL); |
| Object* cell = rinfo->target_cell(); |
| Object* old_cell = cell; |
| VisitPointer(&cell); |
| if (cell != old_cell) { |
| rinfo->set_target_cell(reinterpret_cast<Cell*>(cell)); |
| } |
| } |
| |
| void VisitEmbeddedPointer(RelocInfo* rinfo) { |
| DCHECK(rinfo->rmode() == RelocInfo::EMBEDDED_OBJECT); |
| Object* target = rinfo->target_object(); |
| Object* old_target = target; |
| VisitPointer(&target); |
| // Avoid unnecessary changes that might unnecessary flush the instruction |
| // cache. |
| if (target != old_target) { |
| rinfo->set_target_object(target); |
| } |
| } |
| |
| void VisitCodeTarget(RelocInfo* rinfo) { |
| DCHECK(RelocInfo::IsCodeTarget(rinfo->rmode())); |
| Object* target = Code::GetCodeFromTargetAddress(rinfo->target_address()); |
| Object* old_target = target; |
| VisitPointer(&target); |
| if (target != old_target) { |
| rinfo->set_target_address(Code::cast(target)->instruction_start()); |
| } |
| } |
| |
| void VisitCodeAgeSequence(RelocInfo* rinfo) { |
| DCHECK(RelocInfo::IsCodeAgeSequence(rinfo->rmode())); |
| Object* stub = rinfo->code_age_stub(); |
| DCHECK(stub != NULL); |
| VisitPointer(&stub); |
| if (stub != rinfo->code_age_stub()) { |
| rinfo->set_code_age_stub(Code::cast(stub)); |
| } |
| } |
| |
| void VisitDebugTarget(RelocInfo* rinfo) { |
| DCHECK(RelocInfo::IsDebugBreakSlot(rinfo->rmode()) && |
| rinfo->IsPatchedDebugBreakSlotSequence()); |
| Object* target = |
| Code::GetCodeFromTargetAddress(rinfo->debug_call_address()); |
| VisitPointer(&target); |
| rinfo->set_debug_call_address(Code::cast(target)->instruction_start()); |
| } |
| |
| static inline void UpdateSlot(Heap* heap, Object** slot) { |
| Object* obj = reinterpret_cast<Object*>( |
| base::NoBarrier_Load(reinterpret_cast<base::AtomicWord*>(slot))); |
| |
| if (!obj->IsHeapObject()) return; |
| |
| HeapObject* heap_obj = HeapObject::cast(obj); |
| |
| // TODO(ishell): remove, once crbug/454297 is caught. |
| #if V8_TARGET_ARCH_64_BIT |
| #ifndef V8_OS_AIX // no point checking on AIX as full 64 range is supported |
| const uintptr_t kBoundary = V8_UINT64_C(1) << 48; |
| STATIC_ASSERT(kBoundary > 0); |
| if (reinterpret_cast<uintptr_t>(heap_obj->address()) >= kBoundary) { |
| CheckLayoutDescriptorAndDie(heap, slot); |
| } |
| #endif |
| #endif |
| MapWord map_word = heap_obj->map_word(); |
| if (map_word.IsForwardingAddress()) { |
| DCHECK(heap->InFromSpace(heap_obj) || |
| MarkCompactCollector::IsOnEvacuationCandidate(heap_obj)); |
| HeapObject* target = map_word.ToForwardingAddress(); |
| base::NoBarrier_CompareAndSwap( |
| reinterpret_cast<base::AtomicWord*>(slot), |
| reinterpret_cast<base::AtomicWord>(obj), |
| reinterpret_cast<base::AtomicWord>(target)); |
| DCHECK(!heap->InFromSpace(target) && |
| !MarkCompactCollector::IsOnEvacuationCandidate(target)); |
| } |
| } |
| |
| private: |
| inline void UpdatePointer(Object** p) { UpdateSlot(heap_, p); } |
| |
| static void CheckLayoutDescriptorAndDie(Heap* heap, Object** slot); |
| |
| Heap* heap_; |
| }; |
| |
| |
| #if V8_TARGET_ARCH_64_BIT |
| // TODO(ishell): remove, once crbug/454297 is caught. |
| void PointersUpdatingVisitor::CheckLayoutDescriptorAndDie(Heap* heap, |
| Object** slot) { |
| const int kDataBufferSize = 128; |
| uintptr_t data[kDataBufferSize] = {0}; |
| int index = 0; |
| data[index++] = 0x10aaaaaaaaUL; // begin marker |
| |
| data[index++] = reinterpret_cast<uintptr_t>(slot); |
| data[index++] = 0x15aaaaaaaaUL; |
| |
| Address slot_address = reinterpret_cast<Address>(slot); |
| |
| uintptr_t space_owner_id = 0xb001; |
| if (heap->new_space()->ToSpaceContains(slot_address)) { |
| space_owner_id = 1; |
| } else if (heap->new_space()->FromSpaceContains(slot_address)) { |
| space_owner_id = 2; |
| } else if (heap->old_space()->ContainsSafe(slot_address)) { |
| space_owner_id = 3; |
| } else if (heap->code_space()->ContainsSafe(slot_address)) { |
| space_owner_id = 4; |
| } else if (heap->map_space()->ContainsSafe(slot_address)) { |
| space_owner_id = 5; |
| } else { |
| // Lo space or other. |
| space_owner_id = 6; |
| } |
| data[index++] = space_owner_id; |
| data[index++] = 0x20aaaaaaaaUL; |
| |
| // Find map word lying near before the slot address (usually the map word is |
| // at -3 words from the slot but just in case we look up further. |
| Object** map_slot = slot; |
| bool found = false; |
| const int kMaxDistanceToMap = 64; |
| for (int i = 0; i < kMaxDistanceToMap; i++, map_slot--) { |
| Address map_address = reinterpret_cast<Address>(*map_slot); |
| if (heap->map_space()->ContainsSafe(map_address)) { |
| found = true; |
| break; |
| } |
| } |
| data[index++] = found; |
| data[index++] = 0x30aaaaaaaaUL; |
| data[index++] = reinterpret_cast<uintptr_t>(map_slot); |
| data[index++] = 0x35aaaaaaaaUL; |
| |
| if (found) { |
| Address obj_address = reinterpret_cast<Address>(map_slot); |
| Address end_of_page = |
| reinterpret_cast<Address>(Page::FromAddress(obj_address)) + |
| Page::kPageSize; |
| Address end_address = |
| Min(obj_address + kPointerSize * kMaxDistanceToMap, end_of_page); |
| int size = static_cast<int>(end_address - obj_address); |
| data[index++] = size / kPointerSize; |
| data[index++] = 0x40aaaaaaaaUL; |
| memcpy(&data[index], reinterpret_cast<void*>(map_slot), size); |
| index += size / kPointerSize; |
| data[index++] = 0x50aaaaaaaaUL; |
| |
| HeapObject* object = HeapObject::FromAddress(obj_address); |
| data[index++] = reinterpret_cast<uintptr_t>(object); |
| data[index++] = 0x60aaaaaaaaUL; |
| |
| Map* map = object->map(); |
| data[index++] = reinterpret_cast<uintptr_t>(map); |
| data[index++] = 0x70aaaaaaaaUL; |
| |
| LayoutDescriptor* layout_descriptor = map->layout_descriptor(); |
| data[index++] = reinterpret_cast<uintptr_t>(layout_descriptor); |
| data[index++] = 0x80aaaaaaaaUL; |
| |
| memcpy(&data[index], reinterpret_cast<void*>(map->address()), Map::kSize); |
| index += Map::kSize / kPointerSize; |
| data[index++] = 0x90aaaaaaaaUL; |
| } |
| |
| data[index++] = 0xeeeeeeeeeeUL; |
| DCHECK(index < kDataBufferSize); |
| base::OS::PrintError("Data: %p\n", static_cast<void*>(data)); |
| base::OS::Abort(); |
| } |
| #endif |
| |
| |
| static void UpdatePointer(HeapObject** address, HeapObject* object) { |
| MapWord map_word = object->map_word(); |
| // The store buffer can still contain stale pointers in dead large objects. |
| // Ignore these pointers here. |
| DCHECK(map_word.IsForwardingAddress() || |
| object->GetHeap()->lo_space()->FindPage( |
| reinterpret_cast<Address>(address)) != NULL); |
| if (map_word.IsForwardingAddress()) { |
| // Update the corresponding slot. |
| *address = map_word.ToForwardingAddress(); |
| } |
| } |
| |
| |
| static String* UpdateReferenceInExternalStringTableEntry(Heap* heap, |
| Object** p) { |
| MapWord map_word = HeapObject::cast(*p)->map_word(); |
| |
| if (map_word.IsForwardingAddress()) { |
| return String::cast(map_word.ToForwardingAddress()); |
| } |
| |
| return String::cast(*p); |
| } |
| |
| |
| bool MarkCompactCollector::TryPromoteObject(HeapObject* object, |
| int object_size) { |
| DCHECK(object_size <= Page::kMaxRegularHeapObjectSize); |
| |
| OldSpace* old_space = heap()->old_space(); |
| |
| HeapObject* target; |
| AllocationAlignment alignment = object->RequiredAlignment(); |
| AllocationResult allocation = old_space->AllocateRaw(object_size, alignment); |
| if (allocation.To(&target)) { |
| MigrateObject(target, object, object_size, old_space->identity()); |
| // If we end up needing more special cases, we should factor this out. |
| if (V8_UNLIKELY(target->IsJSArrayBuffer())) { |
| heap()->PromoteArrayBuffer(target); |
| } |
| heap()->IncrementPromotedObjectsSize(object_size); |
| return true; |
| } |
| |
| return false; |
| } |
| |
| |
| bool MarkCompactCollector::IsSlotInBlackObject(Page* p, Address slot, |
| HeapObject** out_object) { |
| Space* owner = p->owner(); |
| if (owner == heap_->lo_space() || owner == NULL) { |
| Object* large_object = heap_->lo_space()->FindObject(slot); |
| // This object has to exist, otherwise we would not have recorded a slot |
| // for it. |
| CHECK(large_object->IsHeapObject()); |
| HeapObject* large_heap_object = HeapObject::cast(large_object); |
| if (IsMarked(large_heap_object)) { |
| *out_object = large_heap_object; |
| return true; |
| } |
| return false; |
| } |
| |
| uint32_t mark_bit_index = p->AddressToMarkbitIndex(slot); |
| unsigned int start_index = mark_bit_index >> Bitmap::kBitsPerCellLog2; |
| MarkBit::CellType index_in_cell = 1U |
| << (mark_bit_index & Bitmap::kBitIndexMask); |
| MarkBit::CellType* cells = p->markbits()->cells(); |
| Address cell_base = p->area_start(); |
| unsigned int cell_base_start_index = Bitmap::IndexToCell( |
| Bitmap::CellAlignIndex(p->AddressToMarkbitIndex(cell_base))); |
| |
| // Check if the slot points to the start of an object. This can happen e.g. |
| // when we left trim a fixed array. Such slots are invalid and we can remove |
| // them. |
| if ((cells[start_index] & index_in_cell) != 0) { |
| return false; |
| } |
| |
| // Check if the object is in the current cell. |
| MarkBit::CellType slot_mask; |
| if ((cells[start_index] == 0) || |
| (base::bits::CountTrailingZeros32(cells[start_index]) > |
| base::bits::CountTrailingZeros32(cells[start_index] | index_in_cell))) { |
| // If we are already in the first cell, there is no live object. |
| if (start_index == cell_base_start_index) return false; |
| |
| // If not, find a cell in a preceding cell slot that has a mark bit set. |
| do { |
| start_index--; |
| } while (start_index > cell_base_start_index && cells[start_index] == 0); |
| |
| // The slot must be in a dead object if there are no preceding cells that |
| // have mark bits set. |
| if (cells[start_index] == 0) { |
| return false; |
| } |
| |
| // The object is in a preceding cell. Set the mask to find any object. |
| slot_mask = 0xffffffff; |
| } else { |
| // The object start is before the the slot index. Hence, in this case the |
| // slot index can not be at the beginning of the cell. |
| CHECK(index_in_cell > 1); |
| // We are interested in object mark bits right before the slot. |
| slot_mask = index_in_cell - 1; |
| } |
| |
| MarkBit::CellType current_cell = cells[start_index]; |
| CHECK(current_cell != 0); |
| |
| // Find the last live object in the cell. |
| unsigned int leading_zeros = |
| base::bits::CountLeadingZeros32(current_cell & slot_mask); |
| CHECK(leading_zeros != 32); |
| unsigned int offset = Bitmap::kBitIndexMask - leading_zeros; |
| |
| cell_base += (start_index - cell_base_start_index) * 32 * kPointerSize; |
| Address address = cell_base + offset * kPointerSize; |
| HeapObject* object = HeapObject::FromAddress(address); |
| CHECK(Marking::IsBlack(Marking::MarkBitFrom(object))); |
| CHECK(object->address() < reinterpret_cast<Address>(slot)); |
| if (object->address() <= slot && |
| (object->address() + object->Size()) > slot) { |
| // If the slot is within the last found object in the cell, the slot is |
| // in a live object. |
| *out_object = object; |
| return true; |
| } |
| return false; |
| } |
| |
| |
| bool MarkCompactCollector::IsSlotInBlackObjectSlow(Page* p, Address slot) { |
| // This function does not support large objects right now. |
| Space* owner = p->owner(); |
| if (owner == heap_->lo_space() || owner == NULL) return true; |
| |
| for (MarkBitCellIterator it(p); !it.Done(); it.Advance()) { |
| Address cell_base = it.CurrentCellBase(); |
| MarkBit::CellType* cell = it.CurrentCell(); |
| |
| MarkBit::CellType current_cell = *cell; |
| if (current_cell == 0) continue; |
| |
| int offset = 0; |
| while (current_cell != 0) { |
| int trailing_zeros = base::bits::CountTrailingZeros32(current_cell); |
| current_cell >>= trailing_zeros; |
| offset += trailing_zeros; |
| Address address = cell_base + offset * kPointerSize; |
| |
| HeapObject* object = HeapObject::FromAddress(address); |
| int size = object->Size(); |
| |
| if (object->address() > slot) return false; |
| if (object->address() <= slot && slot < (object->address() + size)) { |
| return true; |
| } |
| |
| offset++; |
| current_cell >>= 1; |
| } |
| } |
| return false; |
| } |
| |
| |
| bool MarkCompactCollector::IsSlotInLiveObject(Address slot) { |
| HeapObject* object = NULL; |
| // The target object is black but we don't know if the source slot is black. |
| // The source object could have died and the slot could be part of a free |
| // space. Find out based on mark bits if the slot is part of a live object. |
| if (!IsSlotInBlackObject(Page::FromAddress(slot), slot, &object)) { |
| return false; |
| } |
| |
| DCHECK(object != NULL); |
| |
| switch (object->ContentType()) { |
| case HeapObjectContents::kTaggedValues: |
| return true; |
| |
| case HeapObjectContents::kRawValues: { |
| InstanceType type = object->map()->instance_type(); |
| // Slots in maps and code can't be invalid because they are never |
| // shrunk. |
| if (type == MAP_TYPE || type == CODE_TYPE) return true; |
| |
| // Consider slots in objects that contain ONLY raw data as invalid. |
| return false; |
| } |
| |
| case HeapObjectContents::kMixedValues: { |
| if (object->IsFixedTypedArrayBase()) { |
| return static_cast<int>(slot - object->address()) == |
| FixedTypedArrayBase::kBasePointerOffset; |
| } else if (FLAG_unbox_double_fields) { |
| // Filter out slots that happen to point to unboxed double fields. |
| LayoutDescriptorHelper helper(object->map()); |
| DCHECK(!helper.all_fields_tagged()); |
| return helper.IsTagged(static_cast<int>(slot - object->address())); |
| } |
| break; |
| } |
| } |
| UNREACHABLE(); |
| return true; |
| } |
| |
| |
| void MarkCompactCollector::VerifyIsSlotInLiveObject(Address slot, |
| HeapObject* object) { |
| // The target object has to be black. |
| CHECK(Marking::IsBlack(Marking::MarkBitFrom(object))); |
| |
| // The target object is black but we don't know if the source slot is black. |
| // The source object could have died and the slot could be part of a free |
| // space. Use the mark bit iterator to find out about liveness of the slot. |
| CHECK(IsSlotInBlackObjectSlow(Page::FromAddress(slot), slot)); |
| } |
| |
| |
| void MarkCompactCollector::EvacuateNewSpace() { |
| // There are soft limits in the allocation code, designed trigger a mark |
| // sweep collection by failing allocations. But since we are already in |
| // a mark-sweep allocation, there is no sense in trying to trigger one. |
| AlwaysAllocateScope scope(isolate()); |
| |
| NewSpace* new_space = heap()->new_space(); |
| |
| // Store allocation range before flipping semispaces. |
| Address from_bottom = new_space->bottom(); |
| Address from_top = new_space->top(); |
| |
| // Flip the semispaces. After flipping, to space is empty, from space has |
| // live objects. |
| new_space->Flip(); |
| new_space->ResetAllocationInfo(); |
| |
| int survivors_size = 0; |
| |
| // First pass: traverse all objects in inactive semispace, remove marks, |
| // migrate live objects and write forwarding addresses. This stage puts |
| // new entries in the store buffer and may cause some pages to be marked |
| // scan-on-scavenge. |
| NewSpacePageIterator it(from_bottom, from_top); |
| while (it.has_next()) { |
| NewSpacePage* p = it.next(); |
| survivors_size += DiscoverAndEvacuateBlackObjectsOnPage(new_space, p); |
| } |
| |
| heap_->IncrementYoungSurvivorsCounter(survivors_size); |
| new_space->set_age_mark(new_space->top()); |
| } |
| |
| |
| void MarkCompactCollector::EvacuateLiveObjectsFromPage(Page* p) { |
| AlwaysAllocateScope always_allocate(isolate()); |
| PagedSpace* space = static_cast<PagedSpace*>(p->owner()); |
| DCHECK(p->IsEvacuationCandidate() && !p->WasSwept()); |
| p->SetWasSwept(); |
| |
| int offsets[16]; |
| |
| for (MarkBitCellIterator it(p); !it.Done(); it.Advance()) { |
| Address cell_base = it.CurrentCellBase(); |
| MarkBit::CellType* cell = it.CurrentCell(); |
| |
| if (*cell == 0) continue; |
| |
| int live_objects = MarkWordToObjectStarts(*cell, offsets); |
| for (int i = 0; i < live_objects; i++) { |
| Address object_addr = cell_base + offsets[i] * kPointerSize; |
| HeapObject* object = HeapObject::FromAddress(object_addr); |
| DCHECK(Marking::IsBlack(Marking::MarkBitFrom(object))); |
| |
| int size = object->Size(); |
| AllocationAlignment alignment = object->RequiredAlignment(); |
| HeapObject* target_object; |
| AllocationResult allocation = space->AllocateRaw(size, alignment); |
| if (!allocation.To(&target_object)) { |
| // If allocation failed, use emergency memory and re-try allocation. |
| CHECK(space->HasEmergencyMemory()); |
| space->UseEmergencyMemory(); |
| allocation = space->AllocateRaw(size, alignment); |
| } |
| if (!allocation.To(&target_object)) { |
| // OS refused to give us memory. |
| V8::FatalProcessOutOfMemory("Evacuation"); |
| return; |
| } |
| |
| MigrateObject(target_object, object, size, space->identity()); |
| DCHECK(object->map_word().IsForwardingAddress()); |
| } |
| |
| // Clear marking bits for current cell. |
| *cell = 0; |
| } |
| p->ResetLiveBytes(); |
| } |
| |
| |
| void MarkCompactCollector::EvacuatePages() { |
| int npages = evacuation_candidates_.length(); |
| int abandoned_pages = 0; |
| for (int i = 0; i < npages; i++) { |
| Page* p = evacuation_candidates_[i]; |
| DCHECK(p->IsEvacuationCandidate() || |
| p->IsFlagSet(Page::RESCAN_ON_EVACUATION)); |
| DCHECK(static_cast<int>(p->parallel_sweeping()) == |
| MemoryChunk::SWEEPING_DONE); |
| PagedSpace* space = static_cast<PagedSpace*>(p->owner()); |
| // Allocate emergency memory for the case when compaction fails due to out |
| // of memory. |
| if (!space->HasEmergencyMemory()) { |
| space->CreateEmergencyMemory(); // If the OS lets us. |
| } |
| if (p->IsEvacuationCandidate()) { |
| // During compaction we might have to request a new page in order to free |
| // up a page. Check that we actually got an emergency page above so we |
| // can guarantee that this succeeds. |
| if (space->HasEmergencyMemory()) { |
| EvacuateLiveObjectsFromPage(p); |
| // Unlink the page from the list of pages here. We must not iterate |
| // over that page later (e.g. when scan on scavenge pages are |
| // processed). The page itself will be freed later and is still |
| // reachable from the evacuation candidates list. |
| p->Unlink(); |
| } else { |
| // Without room for expansion evacuation is not guaranteed to succeed. |
| // Pessimistically abandon unevacuated pages. |
| for (int j = i; j < npages; j++) { |
| Page* page = evacuation_candidates_[j]; |
| slots_buffer_allocator_.DeallocateChain(page->slots_buffer_address()); |
| page->ClearEvacuationCandidate(); |
| page->SetFlag(Page::RESCAN_ON_EVACUATION); |
| } |
| abandoned_pages = npages - i; |
| break; |
| } |
| } |
| } |
| if (npages > 0) { |
| // Release emergency memory. |
| PagedSpaces spaces(heap()); |
| for (PagedSpace* space = spaces.next(); space != NULL; |
| space = spaces.next()) { |
| if (space->HasEmergencyMemory()) { |
| space->FreeEmergencyMemory(); |
| } |
| } |
| if (FLAG_trace_fragmentation) { |
| if (abandoned_pages != 0) { |
| PrintF( |
| " Abandon %d out of %d page defragmentations due to lack of " |
| "memory\n", |
| abandoned_pages, npages); |
| } else { |
| PrintF(" Defragmented %d pages\n", npages); |
| } |
| } |
| } |
| } |
| |
| |
| class EvacuationWeakObjectRetainer : public WeakObjectRetainer { |
| public: |
| virtual Object* RetainAs(Object* object) { |
| if (object->IsHeapObject()) { |
| HeapObject* heap_object = HeapObject::cast(object); |
| MapWord map_word = heap_object->map_word(); |
| if (map_word.IsForwardingAddress()) { |
| return map_word.ToForwardingAddress(); |
| } |
| } |
| return object; |
| } |
| }; |
| |
| |
| static inline void UpdateSlot(Isolate* isolate, ObjectVisitor* v, |
| SlotsBuffer::SlotType slot_type, Address addr) { |
| switch (slot_type) { |
| case SlotsBuffer::CODE_TARGET_SLOT: { |
| RelocInfo rinfo(addr, RelocInfo::CODE_TARGET, 0, NULL); |
| rinfo.Visit(isolate, v); |
| break; |
| } |
| case SlotsBuffer::CELL_TARGET_SLOT: { |
| RelocInfo rinfo(addr, RelocInfo::CELL, 0, NULL); |
| rinfo.Visit(isolate, v); |
| break; |
| } |
| case SlotsBuffer::CODE_ENTRY_SLOT: { |
| v->VisitCodeEntry(addr); |
| break; |
| } |
| case SlotsBuffer::RELOCATED_CODE_OBJECT: { |
| HeapObject* obj = HeapObject::FromAddress(addr); |
| Code::cast(obj)->CodeIterateBody(v); |
| break; |
| } |
| case SlotsBuffer::DEBUG_TARGET_SLOT: { |
| RelocInfo rinfo(addr, RelocInfo::DEBUG_BREAK_SLOT_AT_POSITION, 0, NULL); |
| if (rinfo.IsPatchedDebugBreakSlotSequence()) rinfo.Visit(isolate, v); |
| break; |
| } |
| case SlotsBuffer::EMBEDDED_OBJECT_SLOT: { |
| RelocInfo rinfo(addr, RelocInfo::EMBEDDED_OBJECT, 0, NULL); |
| rinfo.Visit(isolate, v); |
| break; |
| } |
| case SlotsBuffer::OBJECT_SLOT: { |
| v->VisitPointer(reinterpret_cast<Object**>(addr)); |
| break; |
| } |
| default: |
| UNREACHABLE(); |
| break; |
| } |
| } |
| |
| |
| enum SweepingMode { SWEEP_ONLY, SWEEP_AND_VISIT_LIVE_OBJECTS }; |
| |
| |
| enum SkipListRebuildingMode { REBUILD_SKIP_LIST, IGNORE_SKIP_LIST }; |
| |
| |
| enum FreeSpaceTreatmentMode { IGNORE_FREE_SPACE, ZAP_FREE_SPACE }; |
| |
| |
| template <MarkCompactCollector::SweepingParallelism mode> |
| static intptr_t Free(PagedSpace* space, FreeList* free_list, Address start, |
| int size) { |
| if (mode == MarkCompactCollector::SWEEP_ON_MAIN_THREAD) { |
| DCHECK(free_list == NULL); |
| return space->Free(start, size); |
| } else { |
| // TODO(hpayer): account for wasted bytes in concurrent sweeping too. |
| return size - free_list->Free(start, size); |
| } |
| } |
| |
| |
| // Sweeps a page. After sweeping the page can be iterated. |
| // Slots in live objects pointing into evacuation candidates are updated |
| // if requested. |
| // Returns the size of the biggest continuous freed memory chunk in bytes. |
| template <SweepingMode sweeping_mode, |
| MarkCompactCollector::SweepingParallelism parallelism, |
| SkipListRebuildingMode skip_list_mode, |
| FreeSpaceTreatmentMode free_space_mode> |
| static int Sweep(PagedSpace* space, FreeList* free_list, Page* p, |
| ObjectVisitor* v) { |
| DCHECK(!p->IsEvacuationCandidate() && !p->WasSwept()); |
| DCHECK_EQ(skip_list_mode == REBUILD_SKIP_LIST, |
| space->identity() == CODE_SPACE); |
| DCHECK((p->skip_list() == NULL) || (skip_list_mode == REBUILD_SKIP_LIST)); |
| DCHECK(parallelism == MarkCompactCollector::SWEEP_ON_MAIN_THREAD || |
| sweeping_mode == SWEEP_ONLY); |
| |
| Address free_start = p->area_start(); |
| DCHECK(reinterpret_cast<intptr_t>(free_start) % (32 * kPointerSize) == 0); |
| int offsets[16]; |
| |
| // If we use the skip list for code space pages, we have to lock the skip |
| // list because it could be accessed concurrently by the runtime or the |
| // deoptimizer. |
| SkipList* skip_list = p->skip_list(); |
| if ((skip_list_mode == REBUILD_SKIP_LIST) && skip_list) { |
| skip_list->Clear(); |
| } |
| |
| intptr_t freed_bytes = 0; |
| intptr_t max_freed_bytes = 0; |
| int curr_region = -1; |
| |
| for (MarkBitCellIterator it(p); !it.Done(); it.Advance()) { |
| Address cell_base = it.CurrentCellBase(); |
| MarkBit::CellType* cell = it.CurrentCell(); |
| int live_objects = MarkWordToObjectStarts(*cell, offsets); |
| int live_index = 0; |
| for (; live_objects != 0; live_objects--) { |
| Address free_end = cell_base + offsets[live_index++] * kPointerSize; |
| if (free_end != free_start) { |
| int size = static_cast<int>(free_end - free_start); |
| if (free_space_mode == ZAP_FREE_SPACE) { |
| memset(free_start, 0xcc, size); |
| } |
| freed_bytes = Free<parallelism>(space, free_list, free_start, size); |
| max_freed_bytes = Max(freed_bytes, max_freed_bytes); |
| } |
| HeapObject* live_object = HeapObject::FromAddress(free_end); |
| DCHECK(Marking::IsBlack(Marking::MarkBitFrom(live_object))); |
| Map* map = live_object->synchronized_map(); |
| int size = live_object->SizeFromMap(map); |
| if (sweeping_mode == SWEEP_AND_VISIT_LIVE_OBJECTS) { |
| live_object->IterateBody(map->instance_type(), size, v); |
| } |
| if ((skip_list_mode == REBUILD_SKIP_LIST) && skip_list != NULL) { |
| int new_region_start = SkipList::RegionNumber(free_end); |
| int new_region_end = |
| SkipList::RegionNumber(free_end + size - kPointerSize); |
| if (new_region_start != curr_region || new_region_end != curr_region) { |
| skip_list->AddObject(free_end, size); |
| curr_region = new_region_end; |
| } |
| } |
| free_start = free_end + size; |
| } |
| // Clear marking bits for current cell. |
| *cell = 0; |
| } |
| if (free_start != p->area_end()) { |
| int size = static_cast<int>(p->area_end() - free_start); |
| if (free_space_mode == ZAP_FREE_SPACE) { |
| memset(free_start, 0xcc, size); |
| } |
| freed_bytes = Free<parallelism>(space, free_list, free_start, size); |
| max_freed_bytes = Max(freed_bytes, max_freed_bytes); |
| } |
| p->ResetLiveBytes(); |
| |
| if (parallelism == MarkCompactCollector::SWEEP_IN_PARALLEL) { |
| // When concurrent sweeping is active, the page will be marked after |
| // sweeping by the main thread. |
| p->set_parallel_sweeping(MemoryChunk::SWEEPING_FINALIZE); |
| } else { |
| p->SetWasSwept(); |
| } |
| return FreeList::GuaranteedAllocatable(static_cast<int>(max_freed_bytes)); |
| } |
| |
| |
| static bool IsOnInvalidatedCodeObject(Address addr) { |
| // We did not record any slots in large objects thus |
| // we can safely go to the page from the slot address. |
| Page* p = Page::FromAddress(addr); |
| |
| // First check owner's identity because old space is swept concurrently or |
| // lazily and might still have non-zero mark-bits on some pages. |
| if (p->owner()->identity() != CODE_SPACE) return false; |
| |
| // In code space only bits on evacuation candidates (but we don't record |
| // any slots on them) and under invalidated code objects are non-zero. |
| MarkBit mark_bit = |
| p->markbits()->MarkBitFromIndex(Page::FastAddressToMarkbitIndex(addr)); |
| |
| return Marking::IsBlackOrGrey(mark_bit); |
| } |
| |
| |
| void MarkCompactCollector::InvalidateCode(Code* code) { |
| if (heap_->incremental_marking()->IsCompacting() && |
| !ShouldSkipEvacuationSlotRecording(code)) { |
| DCHECK(compacting_); |
| |
| // If the object is white than no slots were recorded on it yet. |
| MarkBit mark_bit = Marking::MarkBitFrom(code); |
| if (Marking::IsWhite(mark_bit)) return; |
| |
| // Ignore all slots that might have been recorded in the body of the |
| // deoptimized code object. Assumption: no slots will be recorded for |
| // this object after invalidating it. |
| RemoveObjectSlots(code->instruction_start(), |
| code->address() + code->Size()); |
| } |
| } |
| |
| |
| // Return true if the given code is deoptimized or will be deoptimized. |
| bool MarkCompactCollector::WillBeDeoptimized(Code* code) { |
| return code->is_optimized_code() && code->marked_for_deoptimization(); |
| } |
| |
| |
| void MarkCompactCollector::RemoveObjectSlots(Address start_slot, |
| Address end_slot) { |
| // Remove entries by replacing them with an old-space slot containing a smi |
| // that is located in an unmovable page. |
| int npages = evacuation_candidates_.length(); |
| for (int i = 0; i < npages; i++) { |
| Page* p = evacuation_candidates_[i]; |
| DCHECK(p->IsEvacuationCandidate() || |
| p->IsFlagSet(Page::RESCAN_ON_EVACUATION)); |
| if (p->IsEvacuationCandidate()) { |
| SlotsBuffer::RemoveObjectSlots(heap_, p->slots_buffer(), start_slot, |
| end_slot); |
| } |
| } |
| } |
| |
| |
| void MarkCompactCollector::EvacuateNewSpaceAndCandidates() { |
| Heap::RelocationLock relocation_lock(heap()); |
| |
| { |
| GCTracer::Scope gc_scope(heap()->tracer(), |
| GCTracer::Scope::MC_SWEEP_NEWSPACE); |
| EvacuationScope evacuation_scope(this); |
| EvacuateNewSpace(); |
| } |
| |
| { |
| GCTracer::Scope gc_scope(heap()->tracer(), |
| GCTracer::Scope::MC_EVACUATE_PAGES); |
| EvacuationScope evacuation_scope(this); |
| EvacuatePages(); |
| } |
| |
| // Second pass: find pointers to new space and update them. |
| PointersUpdatingVisitor updating_visitor(heap()); |
| |
| { |
| GCTracer::Scope gc_scope(heap()->tracer(), |
| GCTracer::Scope::MC_UPDATE_NEW_TO_NEW_POINTERS); |
| // Update pointers in to space. |
| SemiSpaceIterator to_it(heap()->new_space()); |
| for (HeapObject* object = to_it.Next(); object != NULL; |
| object = to_it.Next()) { |
| Map* map = object->map(); |
| object->IterateBody(map->instance_type(), object->SizeFromMap(map), |
| &updating_visitor); |
| } |
| } |
| |
| { |
| GCTracer::Scope gc_scope(heap()->tracer(), |
| GCTracer::Scope::MC_UPDATE_ROOT_TO_NEW_POINTERS); |
| // Update roots. |
| heap_->IterateRoots(&updating_visitor, VISIT_ALL_IN_SWEEP_NEWSPACE); |
| } |
| |
| { |
| GCTracer::Scope gc_scope(heap()->tracer(), |
| GCTracer::Scope::MC_UPDATE_OLD_TO_NEW_POINTERS); |
| StoreBufferRebuildScope scope(heap_, heap_->store_buffer(), |
| &Heap::ScavengeStoreBufferCallback); |
| heap_->store_buffer()->IteratePointersToNewSpace(&UpdatePointer); |
| } |
| |
| { |
| GCTracer::Scope gc_scope(heap()->tracer(), |
| GCTracer::Scope::MC_UPDATE_POINTERS_TO_EVACUATED); |
| SlotsBuffer::UpdateSlotsRecordedIn(heap_, migration_slots_buffer_); |
| if (FLAG_trace_fragmentation_verbose) { |
| PrintF(" migration slots buffer: %d\n", |
| SlotsBuffer::SizeOfChain(migration_slots_buffer_)); |
| } |
| } |
| |
| int npages = evacuation_candidates_.length(); |
| { |
| GCTracer::Scope gc_scope( |
| heap()->tracer(), |
| GCTracer::Scope::MC_UPDATE_POINTERS_BETWEEN_EVACUATED); |
| for (int i = 0; i < npages; i++) { |
| Page* p = evacuation_candidates_[i]; |
| DCHECK(p->IsEvacuationCandidate() || |
| p->IsFlagSet(Page::RESCAN_ON_EVACUATION)); |
| |
| if (p->IsEvacuationCandidate()) { |
| SlotsBuffer::UpdateSlotsRecordedIn(heap_, p->slots_buffer()); |
| if (FLAG_trace_fragmentation_verbose) { |
| PrintF(" page %p slots buffer: %d\n", reinterpret_cast<void*>(p), |
| SlotsBuffer::SizeOfChain(p->slots_buffer())); |
| } |
| |
| // Important: skip list should be cleared only after roots were updated |
| // because root iteration traverses the stack and might have to find |
| // code objects from non-updated pc pointing into evacuation candidate. |
| SkipList* list = p->skip_list(); |
| if (list != NULL) list->Clear(); |
| } else { |
| if (FLAG_gc_verbose) { |
| PrintF("Sweeping 0x%" V8PRIxPTR " during evacuation.\n", |
| reinterpret_cast<intptr_t>(p)); |
| } |
| PagedSpace* space = static_cast<PagedSpace*>(p->owner()); |
| p->ClearFlag(MemoryChunk::RESCAN_ON_EVACUATION); |
| |
| switch (space->identity()) { |
| case OLD_SPACE: |
| Sweep<SWEEP_AND_VISIT_LIVE_OBJECTS, SWEEP_ON_MAIN_THREAD, |
| IGNORE_SKIP_LIST, IGNORE_FREE_SPACE>(space, NULL, p, |
| &updating_visitor); |
| break; |
| case CODE_SPACE: |
| if (FLAG_zap_code_space) { |
| Sweep<SWEEP_AND_VISIT_LIVE_OBJECTS, SWEEP_ON_MAIN_THREAD, |
| REBUILD_SKIP_LIST, ZAP_FREE_SPACE>(space, NULL, p, |
| &updating_visitor); |
| } else { |
| Sweep<SWEEP_AND_VISIT_LIVE_OBJECTS, SWEEP_ON_MAIN_THREAD, |
| REBUILD_SKIP_LIST, IGNORE_FREE_SPACE>(space, NULL, p, |
| &updating_visitor); |
| } |
| break; |
| default: |
| UNREACHABLE(); |
| break; |
| } |
| } |
| } |
| } |
| |
| GCTracer::Scope gc_scope(heap()->tracer(), |
| GCTracer::Scope::MC_UPDATE_MISC_POINTERS); |
| |
| heap_->string_table()->Iterate(&updating_visitor); |
| |
| // Update pointers from external string table. |
| heap_->UpdateReferencesInExternalStringTable( |
| &UpdateReferenceInExternalStringTableEntry); |
| |
| EvacuationWeakObjectRetainer evacuation_object_retainer; |
| heap()->ProcessAllWeakReferences(&evacuation_object_retainer); |
| |
| heap_->isolate()->inner_pointer_to_code_cache()->Flush(); |
| |
| slots_buffer_allocator_.DeallocateChain(&migration_slots_buffer_); |
| DCHECK(migration_slots_buffer_ == NULL); |
| |
| // The hashing of weak_object_to_code_table is no longer valid. |
| heap()->weak_object_to_code_table()->Rehash( |
| heap()->isolate()->factory()->undefined_value()); |
| } |
| |
| |
| void MarkCompactCollector::MoveEvacuationCandidatesToEndOfPagesList() { |
| int npages = evacuation_candidates_.length(); |
| for (int i = 0; i < npages; i++) { |
| Page* p = evacuation_candidates_[i]; |
| if (!p->IsEvacuationCandidate()) continue; |
| p->Unlink(); |
| PagedSpace* space = static_cast<PagedSpace*>(p->owner()); |
| p->InsertAfter(space->LastPage()); |
| } |
| } |
| |
| |
| void MarkCompactCollector::ReleaseEvacuationCandidates() { |
| int npages = evacuation_candidates_.length(); |
| for (int i = 0; i < npages; i++) { |
| Page* p = evacuation_candidates_[i]; |
| if (!p->IsEvacuationCandidate()) continue; |
| PagedSpace* space = static_cast<PagedSpace*>(p->owner()); |
| space->Free(p->area_start(), p->area_size()); |
| p->set_scan_on_scavenge(false); |
| slots_buffer_allocator_.DeallocateChain(p->slots_buffer_address()); |
| p->ResetLiveBytes(); |
| space->ReleasePage(p); |
| } |
| evacuation_candidates_.Rewind(0); |
| compacting_ = false; |
| heap()->FilterStoreBufferEntriesOnAboutToBeFreedPages(); |
| heap()->FreeQueuedChunks(); |
| } |
| |
| |
| static const int kStartTableEntriesPerLine = 5; |
| static const int kStartTableLines = 171; |
| static const int kStartTableInvalidLine = 127; |
| static const int kStartTableUnusedEntry = 126; |
| |
| #define _ kStartTableUnusedEntry |
| #define X kStartTableInvalidLine |
| // Mark-bit to object start offset table. |
| // |
| // The line is indexed by the mark bits in a byte. The first number on |
| // the line describes the number of live object starts for the line and the |
| // other numbers on the line describe the offsets (in words) of the object |
| // starts. |
| // |
| // Since objects are at least 2 words large we don't have entries for two |
| // consecutive 1 bits. All entries after 170 have at least 2 consecutive bits. |
| char kStartTable[kStartTableLines * kStartTableEntriesPerLine] = { |
| 0, _, _, |
| _, _, // 0 |
| 1, 0, _, |
| _, _, // 1 |
| 1, 1, _, |
| _, _, // 2 |
| X, _, _, |
| _, _, // 3 |
| 1, 2, _, |
| _, _, // 4 |
| 2, 0, 2, |
| _, _, // 5 |
| X, _, _, |
| _, _, // 6 |
| X, _, _, |
| _, _, // 7 |
| 1, 3, _, |
| _, _, // 8 |
| 2, 0, 3, |
| _, _, // 9 |
| 2, 1, 3, |
| _, _, // 10 |
| X, _, _, |
| _, _, // 11 |
| X, _, _, |
| _, _, // 12 |
| X, _, _, |
| _, _, // 13 |
| X, _, _, |
| _, _, // 14 |
| X, _, _, |
| _, _, // 15 |
| 1, 4, _, |
| _, _, // 16 |
| 2, 0, 4, |
| _, _, // 17 |
| 2, 1, 4, |
| _, _, // 18 |
| X, _, _, |
| _, _, // 19 |
| 2, 2, 4, |
| _, _, // 20 |
| 3, 0, 2, |
| 4, _, // 21 |
| X, _, _, |
| _, _, // 22 |
| X, _, _, |
| _, _, // 23 |
| X, _, _, |
| _, _, // 24 |
| X, _, _, |
| _, _, // 25 |
| X, _, _, |
| _, _, // 26 |
| X, _, _, |
| _, _, // 27 |
| X, _, _, |
| _, _, // 28 |
| X, _, _, |
| _, _, // 29 |
| X, _, _, |
| _, _, // 30 |
| X, _, _, |
| _, _, // 31 |
| 1, 5, _, |
| _, _, // 32 |
| 2, 0, 5, |
| _, _, // 33 |
| 2, 1, 5, |
| _, _, // 34 |
| X, _, _, |
| _, _, // 35 |
| 2, 2, 5, |
| _, _, // 36 |
| 3, 0, 2, |
| 5, _, // 37 |
| X, _, _, |
| _, _, // 38 |
| X, _, _, |
| _, _, // 39 |
| 2, 3, 5, |
| _, _, // 40 |
| 3, 0, 3, |
| 5, _, // 41 |
| 3, 1, 3, |
| 5, _, // 42 |
| X, _, _, |
| _, _, // 43 |
| X, _, _, |
| _, _, // 44 |
| X, _, _, |
| _, _, // 45 |
| X, _, _, |
| _, _, // 46 |
| X, _, _, |
| _, _, // 47 |
| X, _, _, |
| _, _, // 48 |
| X, _, _, |
| _, _, // 49 |
| X, _, _, |
| _, _, // 50 |
| X, _, _, |
| _, _, // 51 |
| X, _, _, |
| _, _, // 52 |
| X, _, _, |
| _, _, // 53 |
| X, _, _, |
| _, _, // 54 |
| X, _, _, |
| _, _, // 55 |
| X, _, _, |
| _, _, // 56 |
| X, _, _, |
| _, _, // 57 |
| X, _, _, |
| _, _, // 58 |
| X, _, _, |
| _, _, // 59 |
| X, _, _, |
| _, _, // 60 |
| X, _, _, |
| _, _, // 61 |
| X, _, _, |
| _, _, // 62 |
| X, _, _, |
| _, _, // 63 |
| 1, 6, _, |
| _, _, // 64 |
| 2, 0, 6, |
| _, _, // 65 |
| 2, 1, 6, |
| _, _, // 66 |
| X, _, _, |
| _, _, // 67 |
| 2, 2, 6, |
| _, _, // 68 |
| 3, 0, 2, |
| 6, _, // 69 |
| X, _, _, |
| _, _, // 70 |
| X, _, _, |
| _, _, // 71 |
| 2, 3, 6, |
| _, _, // 72 |
| 3, 0, 3, |
| 6, _, // 73 |
| 3, 1, 3, |
| 6, _, // 74 |
| X, _, _, |
| _, _, // 75 |
| X, _, _, |
| _, _, // 76 |
| X, _, _, |
| _, _, // 77 |
| X, _, _, |
| _, _, // 78 |
| X, _, _, |
| _, _, // 79 |
| 2, 4, 6, |
| _, _, // 80 |
| 3, 0, 4, |
| 6, _, // 81 |
| 3, 1, 4, |
| 6, _, // 82 |
| X, _, _, |
| _, _, // 83 |
| 3, 2, 4, |
| 6, _, // 84 |
| 4, 0, 2, |
| 4, 6, // 85 |
| X, _, _, |
| _, _, // 86 |
| X, _, _, |
| _, _, // 87 |
| X, _, _, |
| _, _, // 88 |
| X, _, _, |
| _, _, // 89 |
| X, _, _, |
| _, _, // 90 |
| X, _, _, |
| _, _, // 91 |
| X, _, _, |
| _, _, // 92 |
| X, _, _, |
| _, _, // 93 |
| X, _, _, |
| _, _, // 94 |
| X, _, _, |
| _, _, // 95 |
| X, _, _, |
| _, _, // 96 |
| X, _, _, |
| _, _, // 97 |
| X, _, _, |
| _, _, // 98 |
| X, _, _, |
| _, _, // 99 |
| X, _, _, |
| _, _, // 100 |
| X, _, _, |
| _, _, // 101 |
| X, _, _, |
| _, _, // 102 |
| X, _, _, |
| _, _, // 103 |
| X, _, _, |
| _, _, // 104 |
| X, _, _, |
| _, _, // 105 |
| X, _, _, |
| _, _, // 106 |
| X, _, _, |
| _, _, // 107 |
| X, _, _, |
| _, _, // 108 |
| X, _, _, |
| _, _, // 109 |
| X, _, _, |
| _, _, // 110 |
| X, _, _, |
| _, _, // 111 |
| X, _, _, |
| _, _, // 112 |
| X, _, _, |
| _, _, // 113 |
| X, _, _, |
| _, _, // 114 |
| X, _, _, |
| _, _, // 115 |
| X, _, _, |
| _, _, // 116 |
| X, _, _, |
| _, _, // 117 |
| X, _, _, |
| _, _, // 118 |
| X, _, _, |
| _, _, // 119 |
| X, _, _, |
| _, _, // 120 |
| X, _, _, |
| _, _, // 121 |
| X, _, _, |
| _, _, // 122 |
| X, _, _, |
| _, _, // 123 |
| X, _, _, |
| _, _, // 124 |
| X, _, _, |
| _, _, // 125 |
| X, _, _, |
| _, _, // 126 |
| X, _, _, |
| _, _, // 127 |
| 1, 7, _, |
| _, _, // 128 |
| 2, 0, 7, |
| _, _, // 129 |
| 2, 1, 7, |
| _, _, // 130 |
| X, _, _, |
| _, _, // 131 |
| 2, 2, 7, |
| _, _, // 132 |
| 3, 0, 2, |
| 7, _, // 133 |
| X, _, _, |
| _, _, // 134 |
| X, _, _, |
| _, _, // 135 |
| 2, 3, 7, |
| _, _, // 136 |
| 3, 0, 3, |
| 7, _, // 137 |
| 3, 1, 3, |
| 7, _, // 138 |
| X, _, _, |
| _, _, // 139 |
| X, _, _, |
| _, _, // 140 |
| X, _, _, |
| _, _, // 141 |
| X, _, _, |
| _, _, // 142 |
| X, _, _, |
| _, _, // 143 |
| 2, 4, 7, |
| _, _, // 144 |
| 3, 0, 4, |
| 7, _, // 145 |
| 3, 1, 4, |
| 7, _, // 146 |
| X, _, _, |
| _, _, // 147 |
| 3, 2, 4, |
| 7, _, // 148 |
| 4, 0, 2, |
| 4, 7, // 149 |
| X, _, _, |
| _, _, // 150 |
| X, _, _, |
| _, _, // 151 |
| X, _, _, |
| _, _, // 152 |
| X, _, _, |
| _, _, // 153 |
| X, _, _, |
| _, _, // 154 |
| X, _, _, |
| _, _, // 155 |
| X, _, _, |
| _, _, // 156 |
| X, _, _, |
| _, _, // 157 |
| X, _, _, |
| _, _, // 158 |
| X, _, _, |
| _, _, // 159 |
| 2, 5, 7, |
| _, _, // 160 |
| 3, 0, 5, |
| 7, _, // 161 |
| 3, 1, 5, |
| 7, _, // 162 |
| X, _, _, |
| _, _, // 163 |
| 3, 2, 5, |
| 7, _, // 164 |
| 4, 0, 2, |
| 5, 7, // 165 |
| X, _, _, |
| _, _, // 166 |
| X, _, _, |
| _, _, // 167 |
| 3, 3, 5, |
| 7, _, // 168 |
| 4, 0, 3, |
| 5, 7, // 169 |
| 4, 1, 3, |
| 5, 7 // 170 |
| }; |
| #undef _ |
| #undef X |
| |
| |
| // Takes a word of mark bits. Returns the number of objects that start in the |
| // range. Puts the offsets of the words in the supplied array. |
| static inline int MarkWordToObjectStarts(uint32_t mark_bits, int* starts) { |
| int objects = 0; |
| int offset = 0; |
| |
| // No consecutive 1 bits. |
| DCHECK((mark_bits & 0x180) != 0x180); |
| DCHECK((mark_bits & 0x18000) != 0x18000); |
| DCHECK((mark_bits & 0x1800000) != 0x1800000); |
| |
| while (mark_bits != 0) { |
| int byte = (mark_bits & 0xff); |
| mark_bits >>= 8; |
| if (byte != 0) { |
| DCHECK(byte < kStartTableLines); // No consecutive 1 bits. |
| char* table = kStartTable + byte * kStartTableEntriesPerLine; |
| int objects_in_these_8_words = table[0]; |
| DCHECK(objects_in_these_8_words != kStartTableInvalidLine); |
| DCHECK(objects_in_these_8_words < kStartTableEntriesPerLine); |
| for (int i = 0; i < objects_in_these_8_words; i++) { |
| starts[objects++] = offset + table[1 + i]; |
| } |
| } |
| offset += 8; |
| } |
| return objects; |
| } |
| |
| |
| int MarkCompactCollector::SweepInParallel(PagedSpace* space, |
| int required_freed_bytes) { |
| int max_freed = 0; |
| int max_freed_overall = 0; |
| PageIterator it(space); |
| while (it.has_next()) { |
| Page* p = it.next(); |
| max_freed = SweepInParallel(p, space); |
| DCHECK(max_freed >= 0); |
| if (required_freed_bytes > 0 && max_freed >= required_freed_bytes) { |
| return max_freed; |
| } |
| max_freed_overall = Max(max_freed, max_freed_overall); |
| if (p == space->end_of_unswept_pages()) break; |
| } |
| return max_freed_overall; |
| } |
| |
| |
| int MarkCompactCollector::SweepInParallel(Page* page, PagedSpace* space) { |
| int max_freed = 0; |
| if (page->TryLock()) { |
| // If this page was already swept in the meantime, we can return here. |
| if (page->parallel_sweeping() != MemoryChunk::SWEEPING_PENDING) { |
| page->mutex()->Unlock(); |
| return 0; |
| } |
| page->set_parallel_sweeping(MemoryChunk::SWEEPING_IN_PROGRESS); |
| FreeList* free_list; |
| FreeList private_free_list(space); |
| if (space->identity() == OLD_SPACE) { |
| free_list = free_list_old_space_.get(); |
| max_freed = |
| Sweep<SWEEP_ONLY, SWEEP_IN_PARALLEL, IGNORE_SKIP_LIST, |
| IGNORE_FREE_SPACE>(space, &private_free_list, page, NULL); |
| } else if (space->identity() == CODE_SPACE) { |
| free_list = free_list_code_space_.get(); |
| max_freed = |
| Sweep<SWEEP_ONLY, SWEEP_IN_PARALLEL, REBUILD_SKIP_LIST, |
| IGNORE_FREE_SPACE>(space, &private_free_list, page, NULL); |
| } else { |
| free_list = free_list_map_space_.get(); |
| max_freed = |
| Sweep<SWEEP_ONLY, SWEEP_IN_PARALLEL, IGNORE_SKIP_LIST, |
| IGNORE_FREE_SPACE>(space, &private_free_list, page, NULL); |
| } |
| free_list->Concatenate(&private_free_list); |
| page->mutex()->Unlock(); |
| } |
| return max_freed; |
| } |
| |
| |
| void MarkCompactCollector::SweepSpace(PagedSpace* space, SweeperType sweeper) { |
| space->ClearStats(); |
| |
| // We defensively initialize end_of_unswept_pages_ here with the first page |
| // of the pages list. |
| space->set_end_of_unswept_pages(space->FirstPage()); |
| |
| PageIterator it(space); |
| |
| int pages_swept = 0; |
| bool unused_page_present = false; |
| bool parallel_sweeping_active = false; |
| |
| while (it.has_next()) { |
| Page* p = it.next(); |
| DCHECK(p->parallel_sweeping() == MemoryChunk::SWEEPING_DONE); |
| |
| // Clear sweeping flags indicating that marking bits are still intact. |
| p->ClearWasSwept(); |
| |
| if (p->IsFlagSet(Page::RESCAN_ON_EVACUATION) || |
| p->IsEvacuationCandidate()) { |
| // Will be processed in EvacuateNewSpaceAndCandidates. |
| DCHECK(evacuation_candidates_.length() > 0); |
| continue; |
| } |
| |
| // One unused page is kept, all further are released before sweeping them. |
| if (p->LiveBytes() == 0) { |
| if (unused_page_present) { |
| if (FLAG_gc_verbose) { |
| PrintF("Sweeping 0x%" V8PRIxPTR " released page.\n", |
| reinterpret_cast<intptr_t>(p)); |
| } |
| // Adjust unswept free bytes because releasing a page expects said |
| // counter to be accurate for unswept pages. |
| space->IncreaseUnsweptFreeBytes(p); |
| space->ReleasePage(p); |
| continue; |
| } |
| unused_page_present = true; |
| } |
| |
| switch (sweeper) { |
| case CONCURRENT_SWEEPING: |
| if (!parallel_sweeping_active) { |
| if (FLAG_gc_verbose) { |
| PrintF("Sweeping 0x%" V8PRIxPTR ".\n", |
| reinterpret_cast<intptr_t>(p)); |
| } |
| if (space->identity() == CODE_SPACE) { |
| if (FLAG_zap_code_space) { |
| Sweep<SWEEP_ONLY, SWEEP_ON_MAIN_THREAD, REBUILD_SKIP_LIST, |
| ZAP_FREE_SPACE>(space, NULL, p, NULL); |
| } else { |
| Sweep<SWEEP_ONLY, SWEEP_ON_MAIN_THREAD, REBUILD_SKIP_LIST, |
| IGNORE_FREE_SPACE>(space, NULL, p, NULL); |
| } |
| } else { |
| Sweep<SWEEP_ONLY, SWEEP_ON_MAIN_THREAD, IGNORE_SKIP_LIST, |
| IGNORE_FREE_SPACE>(space, NULL, p, NULL); |
| } |
| pages_swept++; |
| parallel_sweeping_active = true; |
| } else { |
| if (FLAG_gc_verbose) { |
| PrintF("Sweeping 0x%" V8PRIxPTR " in parallel.\n", |
| reinterpret_cast<intptr_t>(p)); |
| } |
| p->set_parallel_sweeping(MemoryChunk::SWEEPING_PENDING); |
| space->IncreaseUnsweptFreeBytes(p); |
| } |
| space->set_end_of_unswept_pages(p); |
| break; |
| case SEQUENTIAL_SWEEPING: { |
| if (FLAG_gc_verbose) { |
| PrintF("Sweeping 0x%" V8PRIxPTR ".\n", reinterpret_cast<intptr_t>(p)); |
| } |
| if (space->identity() == CODE_SPACE) { |
| if (FLAG_zap_code_space) { |
| Sweep<SWEEP_ONLY, SWEEP_ON_MAIN_THREAD, REBUILD_SKIP_LIST, |
| ZAP_FREE_SPACE>(space, NULL, p, NULL); |
| } else { |
| Sweep<SWEEP_ONLY, SWEEP_ON_MAIN_THREAD, REBUILD_SKIP_LIST, |
| IGNORE_FREE_SPACE>(space, NULL, p, NULL); |
| } |
| } else { |
| Sweep<SWEEP_ONLY, SWEEP_ON_MAIN_THREAD, IGNORE_SKIP_LIST, |
| IGNORE_FREE_SPACE>(space, NULL, p, NULL); |
| } |
| pages_swept++; |
| break; |
| } |
| default: { UNREACHABLE(); } |
| } |
| } |
| |
| if (FLAG_gc_verbose) { |
| PrintF("SweepSpace: %s (%d pages swept)\n", |
| AllocationSpaceName(space->identity()), pages_swept); |
| } |
| } |
| |
| |
| void MarkCompactCollector::SweepSpaces() { |
| GCTracer::Scope gc_scope(heap()->tracer(), GCTracer::Scope::MC_SWEEP); |
| double start_time = 0.0; |
| if (FLAG_print_cumulative_gc_stat) { |
| start_time = base::OS::TimeCurrentMillis(); |
| } |
| |
| #ifdef DEBUG |
| state_ = SWEEP_SPACES; |
| #endif |
| |
| MoveEvacuationCandidatesToEndOfPagesList(); |
| |
| { |
| { |
| GCTracer::Scope sweep_scope(heap()->tracer(), |
| GCTracer::Scope::MC_SWEEP_OLDSPACE); |
| SweepSpace(heap()->old_space(), CONCURRENT_SWEEPING); |
| } |
| { |
| GCTracer::Scope sweep_scope(heap()->tracer(), |
| GCTracer::Scope::MC_SWEEP_CODE); |
| SweepSpace(heap()->code_space(), CONCURRENT_SWEEPING); |
| } |
| { |
| GCTracer::Scope sweep_scope(heap()->tracer(), |
| GCTracer::Scope::MC_SWEEP_MAP); |
| SweepSpace(heap()->map_space(), CONCURRENT_SWEEPING); |
| } |
| sweeping_in_progress_ = true; |
| if (heap()->concurrent_sweeping_enabled()) { |
| StartSweeperThreads(); |
| } |
| } |
| |
| // Deallocate unmarked large objects. |
| heap_->lo_space()->FreeUnmarkedObjects(); |
| |
| // Give pages that are queued to be freed back to the OS. Invalid store |
| // buffer entries are already filter out. We can just release the memory. |
| heap()->FreeQueuedChunks(); |
| |
| heap()->FreeDeadArrayBuffers(false); |
| |
| EvacuateNewSpaceAndCandidates(); |
| |
| // Clear the marking state of live large objects. |
| heap_->lo_space()->ClearMarkingStateOfLiveObjects(); |
| |
| // Deallocate evacuated candidate pages. |
| ReleaseEvacuationCandidates(); |
| CodeRange* code_range = heap()->isolate()->code_range(); |
| if (code_range != NULL && code_range->valid()) { |
| code_range->ReserveEmergencyBlock(); |
| } |
| |
| if (FLAG_print_cumulative_gc_stat) { |
| heap_->tracer()->AddSweepingTime(base::OS::TimeCurrentMillis() - |
| start_time); |
| } |
| |
| #ifdef VERIFY_HEAP |
| if (FLAG_verify_heap && !sweeping_in_progress_) { |
| VerifyEvacuation(heap()); |
| } |
| #endif |
| } |
| |
| |
| void MarkCompactCollector::ParallelSweepSpaceComplete(PagedSpace* space) { |
| PageIterator it(space); |
| while (it.has_next()) { |
| Page* p = it.next(); |
| if (p->parallel_sweeping() == MemoryChunk::SWEEPING_FINALIZE) { |
| p->set_parallel_sweeping(MemoryChunk::SWEEPING_DONE); |
| p->SetWasSwept(); |
| } |
| DCHECK(p->parallel_sweeping() == MemoryChunk::SWEEPING_DONE); |
| } |
| } |
| |
| |
| void MarkCompactCollector::ParallelSweepSpacesComplete() { |
| ParallelSweepSpaceComplete(heap()->old_space()); |
| ParallelSweepSpaceComplete(heap()->code_space()); |
| ParallelSweepSpaceComplete(heap()->map_space()); |
| } |
| |
| |
| void MarkCompactCollector::EnableCodeFlushing(bool enable) { |
| if (isolate()->debug()->is_active()) enable = false; |
| |
| if (enable) { |
| if (code_flusher_ != NULL) return; |
| code_flusher_ = new CodeFlusher(isolate()); |
| } else { |
| if (code_flusher_ == NULL) return; |
| code_flusher_->EvictAllCandidates(); |
| delete code_flusher_; |
| code_flusher_ = NULL; |
| } |
| |
| if (FLAG_trace_code_flushing) { |
| PrintF("[code-flushing is now %s]\n", enable ? "on" : "off"); |
| } |
| } |
| |
| |
| // TODO(1466) ReportDeleteIfNeeded is not called currently. |
| // Our profiling tools do not expect intersections between |
| // code objects. We should either reenable it or change our tools. |
| void MarkCompactCollector::ReportDeleteIfNeeded(HeapObject* obj, |
| Isolate* isolate) { |
| if (obj->IsCode()) { |
| PROFILE(isolate, CodeDeleteEvent(obj->address())); |
| } |
| } |
| |
| |
| Isolate* MarkCompactCollector::isolate() const { return heap_->isolate(); } |
| |
| |
| void MarkCompactCollector::Initialize() { |
| MarkCompactMarkingVisitor::Initialize(); |
| IncrementalMarking::Initialize(); |
| } |
| |
| |
| bool SlotsBuffer::IsTypedSlot(ObjectSlot slot) { |
| return reinterpret_cast<uintptr_t>(slot) < NUMBER_OF_SLOT_TYPES; |
| } |
| |
| |
| bool SlotsBuffer::AddTo(SlotsBufferAllocator* allocator, |
| SlotsBuffer** buffer_address, SlotType type, |
| Address addr, AdditionMode mode) { |
| SlotsBuffer* buffer = *buffer_address; |
| if (buffer == NULL || !buffer->HasSpaceForTypedSlot()) { |
| if (mode == FAIL_ON_OVERFLOW && ChainLengthThresholdReached(buffer)) { |
| allocator->DeallocateChain(buffer_address); |
| return false; |
| } |
| buffer = allocator->AllocateBuffer(buffer); |
| *buffer_address = buffer; |
| } |
| DCHECK(buffer->HasSpaceForTypedSlot()); |
| buffer->Add(reinterpret_cast<ObjectSlot>(type)); |
| buffer->Add(reinterpret_cast<ObjectSlot>(addr)); |
| return true; |
| } |
| |
| |
| void SlotsBuffer::RemoveInvalidSlots(Heap* heap, SlotsBuffer* buffer) { |
| // Remove entries by replacing them with an old-space slot containing a smi |
| // that is located in an unmovable page. |
| const ObjectSlot kRemovedEntry = HeapObject::RawField( |
| heap->empty_fixed_array(), FixedArrayBase::kLengthOffset); |
| DCHECK(Page::FromAddress(reinterpret_cast<Address>(kRemovedEntry)) |
| ->NeverEvacuate()); |
| |
| while (buffer != NULL) { |
| SlotsBuffer::ObjectSlot* slots = buffer->slots_; |
| intptr_t slots_count = buffer->idx_; |
| |
| for (int slot_idx = 0; slot_idx < slots_count; ++slot_idx) { |
| ObjectSlot slot = slots[slot_idx]; |
| if (!IsTypedSlot(slot)) { |
| Object* object = *slot; |
| if ((object->IsHeapObject() && heap->InNewSpace(object)) || |
| !heap->mark_compact_collector()->IsSlotInLiveObject( |
| reinterpret_cast<Address>(slot))) { |
| slots[slot_idx] = kRemovedEntry; |
| } |
| } else { |
| ++slot_idx; |
| DCHECK(slot_idx < slots_count); |
| } |
| } |
| buffer = buffer->next(); |
| } |
| } |
| |
| |
| void SlotsBuffer::RemoveObjectSlots(Heap* heap, SlotsBuffer* buffer, |
| Address start_slot, Address end_slot) { |
| // Remove entries by replacing them with an old-space slot containing a smi |
| // that is located in an unmovable page. |
| const ObjectSlot kRemovedEntry = HeapObject::RawField( |
| heap->empty_fixed_array(), FixedArrayBase::kLengthOffset); |
| DCHECK(Page::FromAddress(reinterpret_cast<Address>(kRemovedEntry)) |
| ->NeverEvacuate()); |
| |
| while (buffer != NULL) { |
| SlotsBuffer::ObjectSlot* slots = buffer->slots_; |
| intptr_t slots_count = buffer->idx_; |
| bool is_typed_slot = false; |
| |
| for (int slot_idx = 0; slot_idx < slots_count; ++slot_idx) { |
| ObjectSlot slot = slots[slot_idx]; |
| if (!IsTypedSlot(slot)) { |
| Address slot_address = reinterpret_cast<Address>(slot); |
| if (slot_address >= start_slot && slot_address < end_slot) { |
| slots[slot_idx] = kRemovedEntry; |
| if (is_typed_slot) { |
| slots[slot_idx - 1] = kRemovedEntry; |
| } |
| } |
| is_typed_slot = false; |
| } else { |
| is_typed_slot = true; |
| DCHECK(slot_idx < slots_count); |
| } |
| } |
| buffer = buffer->next(); |
| } |
| } |
| |
| |
| void SlotsBuffer::VerifySlots(Heap* heap, SlotsBuffer* buffer) { |
| while (buffer != NULL) { |
| SlotsBuffer::ObjectSlot* slots = buffer->slots_; |
| intptr_t slots_count = buffer->idx_; |
| |
| for (int slot_idx = 0; slot_idx < slots_count; ++slot_idx) { |
| ObjectSlot slot = slots[slot_idx]; |
| if (!IsTypedSlot(slot)) { |
| Object* object = *slot; |
| if (object->IsHeapObject()) { |
| HeapObject* heap_object = HeapObject::cast(object); |
| CHECK(!heap->InNewSpace(object)); |
| heap->mark_compact_collector()->VerifyIsSlotInLiveObject( |
| reinterpret_cast<Address>(slot), heap_object); |
| } |
| } else { |
| ++slot_idx; |
| DCHECK(slot_idx < slots_count); |
| } |
| } |
| buffer = buffer->next(); |
| } |
| } |
| |
| |
| static inline SlotsBuffer::SlotType SlotTypeForRMode(RelocInfo::Mode rmode) { |
| if (RelocInfo::IsCodeTarget(rmode)) { |
| return SlotsBuffer::CODE_TARGET_SLOT; |
| } else if (RelocInfo::IsCell(rmode)) { |
| return SlotsBuffer::CELL_TARGET_SLOT; |
| } else if (RelocInfo::IsEmbeddedObject(rmode)) { |
| return SlotsBuffer::EMBEDDED_OBJECT_SLOT; |
| } else if (RelocInfo::IsDebugBreakSlot(rmode)) { |
| return SlotsBuffer::DEBUG_TARGET_SLOT; |
| } |
| UNREACHABLE(); |
| return SlotsBuffer::NUMBER_OF_SLOT_TYPES; |
| } |
| |
| |
| void MarkCompactCollector::RecordRelocSlot(RelocInfo* rinfo, Object* target) { |
| Page* target_page = Page::FromAddress(reinterpret_cast<Address>(target)); |
| RelocInfo::Mode rmode = rinfo->rmode(); |
| if (target_page->IsEvacuationCandidate() && |
| (rinfo->host() == NULL || |
| !ShouldSkipEvacuationSlotRecording(rinfo->host()))) { |
| Address addr = rinfo->pc(); |
| SlotsBuffer::SlotType slot_type = SlotTypeForRMode(rmode); |
| if (rinfo->IsInConstantPool()) { |
| addr = rinfo->constant_pool_entry_address(); |
| if (RelocInfo::IsCodeTarget(rmode)) { |
| slot_type = SlotsBuffer::CODE_ENTRY_SLOT; |
| } else { |
| DCHECK(RelocInfo::IsEmbeddedObject(rmode)); |
| slot_type = SlotsBuffer::OBJECT_SLOT; |
| } |
| } |
| bool success = SlotsBuffer::AddTo( |
| &slots_buffer_allocator_, target_page->slots_buffer_address(), |
| slot_type, addr, SlotsBuffer::FAIL_ON_OVERFLOW); |
| if (!success) { |
| EvictPopularEvacuationCandidate(target_page); |
| } |
| } |
| } |
| |
| |
| void MarkCompactCollector::EvictPopularEvacuationCandidate(Page* page) { |
| if (FLAG_trace_fragmentation) { |
| PrintF("Page %p is too popular. Disabling evacuation.\n", |
| reinterpret_cast<void*>(page)); |
| } |
| |
| isolate()->CountUsage(v8::Isolate::UseCounterFeature::kSlotsBufferOverflow); |
| |
| // TODO(gc) If all evacuation candidates are too popular we |
| // should stop slots recording entirely. |
| page->ClearEvacuationCandidate(); |
| |
| DCHECK(!page->IsFlagSet(Page::POPULAR_PAGE)); |
| page->SetFlag(Page::POPULAR_PAGE); |
| |
| // We were not collecting slots on this page that point |
| // to other evacuation candidates thus we have to |
| // rescan the page after evacuation to discover and update all |
| // pointers to evacuated objects. |
| page->SetFlag(Page::RESCAN_ON_EVACUATION); |
| } |
| |
| |
| void MarkCompactCollector::RecordCodeEntrySlot(HeapObject* object, Address slot, |
| Code* target) { |
| Page* target_page = Page::FromAddress(reinterpret_cast<Address>(target)); |
| if (target_page->IsEvacuationCandidate() && |
| !ShouldSkipEvacuationSlotRecording(object)) { |
| if (!SlotsBuffer::AddTo(&slots_buffer_allocator_, |
| target_page->slots_buffer_address(), |
| SlotsBuffer::CODE_ENTRY_SLOT, slot, |
| SlotsBuffer::FAIL_ON_OVERFLOW)) { |
| EvictPopularEvacuationCandidate(target_page); |
| } |
| } |
| } |
| |
| |
| void MarkCompactCollector::RecordCodeTargetPatch(Address pc, Code* target) { |
| DCHECK(heap()->gc_state() == Heap::MARK_COMPACT); |
| if (is_compacting()) { |
| Code* host = |
| isolate()->inner_pointer_to_code_cache()->GcSafeFindCodeForInnerPointer( |
| pc); |
| MarkBit mark_bit = Marking::MarkBitFrom(host); |
| if (Marking::IsBlack(mark_bit)) { |
| RelocInfo rinfo(pc, RelocInfo::CODE_TARGET, 0, host); |
| RecordRelocSlot(&rinfo, target); |
| } |
| } |
| } |
| |
| |
| static inline SlotsBuffer::SlotType DecodeSlotType( |
| SlotsBuffer::ObjectSlot slot) { |
| return static_cast<SlotsBuffer::SlotType>(reinterpret_cast<intptr_t>(slot)); |
| } |
| |
| |
| void SlotsBuffer::UpdateSlots(Heap* heap) { |
| PointersUpdatingVisitor v(heap); |
| |
| for (int slot_idx = 0; slot_idx < idx_; ++slot_idx) { |
| ObjectSlot slot = slots_[slot_idx]; |
| if (!IsTypedSlot(slot)) { |
| PointersUpdatingVisitor::UpdateSlot(heap, slot); |
| } else { |
| ++slot_idx; |
| DCHECK(slot_idx < idx_); |
| UpdateSlot(heap->isolate(), &v, DecodeSlotType(slot), |
| reinterpret_cast<Address>(slots_[slot_idx])); |
| } |
| } |
| } |
| |
| |
| void SlotsBuffer::UpdateSlotsWithFilter(Heap* heap) { |
| PointersUpdatingVisitor v(heap); |
| |
| for (int slot_idx = 0; slot_idx < idx_; ++slot_idx) { |
| ObjectSlot slot = slots_[slot_idx]; |
| if (!IsTypedSlot(slot)) { |
| if (!IsOnInvalidatedCodeObject(reinterpret_cast<Address>(slot))) { |
| PointersUpdatingVisitor::UpdateSlot(heap, slot); |
| } |
| } else { |
| ++slot_idx; |
| DCHECK(slot_idx < idx_); |
| Address pc = reinterpret_cast<Address>(slots_[slot_idx]); |
| if (!IsOnInvalidatedCodeObject(pc)) { |
| UpdateSlot(heap->isolate(), &v, DecodeSlotType(slot), |
| reinterpret_cast<Address>(slots_[slot_idx])); |
| } |
| } |
| } |
| } |
| |
| |
| SlotsBuffer* SlotsBufferAllocator::AllocateBuffer(SlotsBuffer* next_buffer) { |
| return new SlotsBuffer(next_buffer); |
| } |
| |
| |
| void SlotsBufferAllocator::DeallocateBuffer(SlotsBuffer* buffer) { |
| delete buffer; |
| } |
| |
| |
| void SlotsBufferAllocator::DeallocateChain(SlotsBuffer** buffer_address) { |
| SlotsBuffer* buffer = *buffer_address; |
| while (buffer != NULL) { |
| SlotsBuffer* next_buffer = buffer->next(); |
| DeallocateBuffer(buffer); |
| buffer = next_buffer; |
| } |
| *buffer_address = NULL; |
| } |
| } // namespace internal |
| } // namespace v8 |