1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
|
// 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::IncrementLiveBytes(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::IncrementLiveBytes(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::IncrementLiveBytes(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();
}
Map* map = nullptr;
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);
map = base::NoBarrierAtomicValue<Map*>::FromAddress(addr)->Value();
Address end = addr + black_object->SizeFromMap(map) - 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)) {
map = base::NoBarrierAtomicValue<Map*>::FromAddress(addr)->Value();
object = HeapObject::FromAddress(addr);
}
// We found a live object.
if (object != nullptr) {
if (map == heap()->one_pointer_filler_map()) {
// Black areas together with slack tracking may result in black one
// word 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_
|
