1// Copyright 2020 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef V8_HEAP_MARKING_BARRIER_INL_H_
6#define V8_HEAP_MARKING_BARRIER_INL_H_
7
8#include "src/heap/incremental-marking-inl.h"
9#include "src/heap/incremental-marking.h"
10#include "src/heap/marking-barrier.h"
11
12namespace v8 {
13namespace internal {
14
15bool MarkingBarrier::MarkValue(HeapObject host, HeapObject value) {
16  DCHECK(IsCurrentMarkingBarrier());
17  DCHECK(is_activated_);
18  DCHECK(!marking_state_.IsImpossible(value));
19  // Host may have an impossible markbit pattern if manual allocation folding
20  // is performed and host happens to be the last word of an allocated region.
21  // In that case host has only one markbit and the second markbit belongs to
22  // another object. We can detect that case by checking if value is a one word
23  // filler map.
24  DCHECK(!marking_state_.IsImpossible(host) ||
25         value == ReadOnlyRoots(heap_->isolate()).one_pointer_filler_map());
26  if (!V8_CONCURRENT_MARKING_BOOL && !marking_state_.IsBlack(host)) {
27    // The value will be marked and the slot will be recorded when the marker
28    // visits the host object.
29    return false;
30  }
31  BasicMemoryChunk* target_page = BasicMemoryChunk::FromHeapObject(value);
32  if (is_shared_heap_ != target_page->InSharedHeap()) return false;
33  if (WhiteToGreyAndPush(value)) {
34    if (is_main_thread_barrier_) {
35      incremental_marking_->RestartIfNotMarking();
36    }
37
38    if (V8_UNLIKELY(FLAG_track_retaining_path)) {
39      heap_->AddRetainingRoot(Root::kWriteBarrier, value);
40    }
41  }
42  return true;
43}
44
45template <typename TSlot>
46inline void MarkingBarrier::MarkRange(HeapObject host, TSlot start, TSlot end) {
47  auto* isolate = heap_->isolate();
48  for (TSlot slot = start; slot < end; ++slot) {
49    typename TSlot::TObject object = slot.Relaxed_Load();
50    HeapObject heap_object;
51    // Mark both, weak and strong edges.
52    if (object.GetHeapObject(isolate, &heap_object)) {
53      if (MarkValue(host, heap_object) && is_compacting_) {
54        collector_->RecordSlot(host, HeapObjectSlot(slot), heap_object);
55      }
56    }
57  }
58}
59
60bool MarkingBarrier::WhiteToGreyAndPush(HeapObject obj) {
61  if (marking_state_.WhiteToGrey(obj)) {
62    worklist_.Push(obj);
63    return true;
64  }
65  return false;
66}
67
68}  // namespace internal
69}  // namespace v8
70
71#endif  // V8_HEAP_MARKING_BARRIER_INL_H_
72