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// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_HEAP_MARK_COMPACT_INL_H_
#define V8_HEAP_MARK_COMPACT_INL_H_
#include "src/heap/mark-compact.h"
#include "src/heap/remembered-set.h"
#include "src/isolate.h"
namespace v8 {
namespace internal {
void MarkCompactCollector::PushBlack(HeapObject* obj) {
DCHECK(Marking::IsBlack(ObjectMarking::MarkBitFrom(obj)));
if (marking_deque_.Push(obj)) {
MemoryChunk::IncrementLiveBytesFromGC(obj, obj->Size());
} else {
MarkBit mark_bit = ObjectMarking::MarkBitFrom(obj);
Marking::BlackToGrey(mark_bit);
}
}
void MarkCompactCollector::UnshiftBlack(HeapObject* obj) {
DCHECK(Marking::IsBlack(ObjectMarking::MarkBitFrom(obj)));
if (!marking_deque_.Unshift(obj)) {
MemoryChunk::IncrementLiveBytesFromGC(obj, -obj->Size());
MarkBit mark_bit = ObjectMarking::MarkBitFrom(obj);
Marking::BlackToGrey(mark_bit);
}
}
void MarkCompactCollector::MarkObject(HeapObject* obj, MarkBit mark_bit) {
DCHECK(ObjectMarking::MarkBitFrom(obj) == mark_bit);
if (Marking::IsWhite(mark_bit)) {
Marking::WhiteToBlack(mark_bit);
DCHECK(obj->GetIsolate()->heap()->Contains(obj));
PushBlack(obj);
}
}
void MarkCompactCollector::SetMark(HeapObject* obj, MarkBit mark_bit) {
DCHECK(Marking::IsWhite(mark_bit));
DCHECK(ObjectMarking::MarkBitFrom(obj) == mark_bit);
Marking::WhiteToBlack(mark_bit);
MemoryChunk::IncrementLiveBytesFromGC(obj, obj->Size());
}
bool MarkCompactCollector::IsMarked(Object* obj) {
DCHECK(obj->IsHeapObject());
HeapObject* heap_object = HeapObject::cast(obj);
return Marking::IsBlackOrGrey(ObjectMarking::MarkBitFrom(heap_object));
}
void MarkCompactCollector::RecordSlot(HeapObject* object, Object** slot,
Object* target) {
Page* target_page = Page::FromAddress(reinterpret_cast<Address>(target));
Page* source_page = Page::FromAddress(reinterpret_cast<Address>(object));
if (target_page->IsEvacuationCandidate() &&
!ShouldSkipEvacuationSlotRecording(object)) {
DCHECK(Marking::IsBlackOrGrey(ObjectMarking::MarkBitFrom(object)));
RememberedSet<OLD_TO_OLD>::Insert(source_page,
reinterpret_cast<Address>(slot));
}
}
void CodeFlusher::AddCandidate(SharedFunctionInfo* shared_info) {
if (GetNextCandidate(shared_info) == nullptr) {
SetNextCandidate(shared_info, shared_function_info_candidates_head_);
shared_function_info_candidates_head_ = shared_info;
}
}
void CodeFlusher::AddCandidate(JSFunction* function) {
DCHECK(function->code() == function->shared()->code());
if (function->next_function_link()->IsUndefined(isolate_)) {
SetNextCandidate(function, jsfunction_candidates_head_);
jsfunction_candidates_head_ = function;
}
}
JSFunction** CodeFlusher::GetNextCandidateSlot(JSFunction* candidate) {
return reinterpret_cast<JSFunction**>(
HeapObject::RawField(candidate, JSFunction::kNextFunctionLinkOffset));
}
JSFunction* CodeFlusher::GetNextCandidate(JSFunction* candidate) {
Object* next_candidate = candidate->next_function_link();
return reinterpret_cast<JSFunction*>(next_candidate);
}
void CodeFlusher::SetNextCandidate(JSFunction* candidate,
JSFunction* next_candidate) {
candidate->set_next_function_link(next_candidate, UPDATE_WEAK_WRITE_BARRIER);
}
void CodeFlusher::ClearNextCandidate(JSFunction* candidate, Object* undefined) {
DCHECK(undefined->IsUndefined(candidate->GetIsolate()));
candidate->set_next_function_link(undefined, SKIP_WRITE_BARRIER);
}
SharedFunctionInfo* CodeFlusher::GetNextCandidate(
SharedFunctionInfo* candidate) {
Object* next_candidate = candidate->code()->gc_metadata();
return reinterpret_cast<SharedFunctionInfo*>(next_candidate);
}
void CodeFlusher::SetNextCandidate(SharedFunctionInfo* candidate,
SharedFunctionInfo* next_candidate) {
candidate->code()->set_gc_metadata(next_candidate);
}
void CodeFlusher::ClearNextCandidate(SharedFunctionInfo* candidate) {
candidate->code()->set_gc_metadata(NULL, SKIP_WRITE_BARRIER);
}
template <LiveObjectIterationMode T>
HeapObject* LiveObjectIterator<T>::Next() {
while (!it_.Done()) {
HeapObject* object = nullptr;
while (current_cell_ != 0) {
uint32_t trailing_zeros = base::bits::CountTrailingZeros32(current_cell_);
Address addr = cell_base_ + trailing_zeros * kPointerSize;
// Clear the first bit of the found object..
current_cell_ &= ~(1u << trailing_zeros);
uint32_t second_bit_index = 0;
if (trailing_zeros < Bitmap::kBitIndexMask) {
second_bit_index = 1u << (trailing_zeros + 1);
} else {
second_bit_index = 0x1;
// The overlapping case; there has to exist a cell after the current
// cell.
// However, if there is a black area at the end of the page, and the
// last word is a one word filler, we are not allowed to advance. In
// that case we can return immediately.
if (it_.Done()) {
DCHECK(HeapObject::FromAddress(addr)->map() ==
HeapObject::FromAddress(addr)
->GetHeap()
->one_pointer_filler_map());
return nullptr;
}
it_.Advance();
cell_base_ = it_.CurrentCellBase();
current_cell_ = *it_.CurrentCell();
}
if (current_cell_ & second_bit_index) {
// We found a black object. If the black object is within a black area,
// make sure that we skip all set bits in the black area until the
// object ends.
HeapObject* black_object = HeapObject::FromAddress(addr);
Address end = addr + black_object->Size() - kPointerSize;
// One word filler objects do not borrow the second mark bit. We have
// to jump over the advancing and clearing part.
// Note that we know that we are at a one word filler when
// object_start + object_size - kPointerSize == object_start.
if (addr != end) {
DCHECK_EQ(chunk_, MemoryChunk::FromAddress(end));
uint32_t end_mark_bit_index = chunk_->AddressToMarkbitIndex(end);
unsigned int end_cell_index =
end_mark_bit_index >> Bitmap::kBitsPerCellLog2;
MarkBit::CellType end_index_mask =
1u << Bitmap::IndexInCell(end_mark_bit_index);
if (it_.Advance(end_cell_index)) {
cell_base_ = it_.CurrentCellBase();
current_cell_ = *it_.CurrentCell();
}
// Clear all bits in current_cell, including the end index.
current_cell_ &= ~(end_index_mask + end_index_mask - 1);
}
if (T == kBlackObjects || T == kAllLiveObjects) {
object = black_object;
}
} else if ((T == kGreyObjects || T == kAllLiveObjects)) {
object = HeapObject::FromAddress(addr);
}
// We found a live object.
if (object != nullptr) {
if (object->IsFiller()) {
// Black areas together with slack tracking may result in black filler
// objects. We filter these objects out in the iterator.
object = nullptr;
} else {
break;
}
}
}
if (current_cell_ == 0) {
if (!it_.Done()) {
it_.Advance();
cell_base_ = it_.CurrentCellBase();
current_cell_ = *it_.CurrentCell();
}
}
if (object != nullptr) return object;
}
return nullptr;
}
} // namespace internal
} // namespace v8
#endif // V8_HEAP_MARK_COMPACT_INL_H_
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