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
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
|
// Copyright 2016 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/snapshot/deserializer.h"
#include "src/assembler-inl.h"
#include "src/heap/heap-write-barrier-inl.h"
#include "src/isolate.h"
#include "src/objects/api-callbacks.h"
#include "src/objects/hash-table.h"
#include "src/objects/js-array-buffer-inl.h"
#include "src/objects/js-array-inl.h"
#include "src/objects/maybe-object.h"
#include "src/objects/string.h"
#include "src/snapshot/builtin-deserializer-allocator.h"
#include "src/snapshot/natives.h"
#include "src/snapshot/snapshot.h"
namespace v8 {
namespace internal {
template <class AllocatorT>
void Deserializer<AllocatorT>::Initialize(Isolate* isolate) {
DCHECK_NULL(isolate_);
DCHECK_NOT_NULL(isolate);
isolate_ = isolate;
DCHECK_NULL(external_reference_table_);
external_reference_table_ = isolate->heap()->external_reference_table();
#ifdef DEBUG
// Count the number of external references registered through the API.
num_api_references_ = 0;
if (isolate_->api_external_references() != nullptr) {
while (isolate_->api_external_references()[num_api_references_] != 0) {
num_api_references_++;
}
}
#endif // DEBUG
CHECK_EQ(magic_number_,
SerializedData::ComputeMagicNumber(external_reference_table_));
}
template <class AllocatorT>
bool Deserializer<AllocatorT>::IsLazyDeserializationEnabled() const {
return FLAG_lazy_deserialization && !isolate()->serializer_enabled();
}
template <class AllocatorT>
void Deserializer<AllocatorT>::Rehash() {
DCHECK(can_rehash() || deserializing_user_code());
for (const auto& item : to_rehash_) item->RehashBasedOnMap(isolate());
}
template <class AllocatorT>
Deserializer<AllocatorT>::~Deserializer() {
#ifdef DEBUG
// Do not perform checks if we aborted deserialization.
if (source_.position() == 0) return;
// Check that we only have padding bytes remaining.
while (source_.HasMore()) DCHECK_EQ(kNop, source_.Get());
// Check that we've fully used all reserved space.
DCHECK(allocator()->ReservationsAreFullyUsed());
#endif // DEBUG
}
// This is called on the roots. It is the driver of the deserialization
// process. It is also called on the body of each function.
template <class AllocatorT>
void Deserializer<AllocatorT>::VisitRootPointers(Root root,
const char* description,
Object** start, Object** end) {
// Builtins and bytecode handlers are deserialized in a separate pass by the
// BuiltinDeserializer.
if (root == Root::kBuiltins || root == Root::kDispatchTable) return;
// The space must be new space. Any other space would cause ReadChunk to try
// to update the remembered using nullptr as the address.
ReadData(reinterpret_cast<MaybeObject**>(start),
reinterpret_cast<MaybeObject**>(end), NEW_SPACE, kNullAddress);
}
template <class AllocatorT>
void Deserializer<AllocatorT>::Synchronize(
VisitorSynchronization::SyncTag tag) {
static const byte expected = kSynchronize;
CHECK_EQ(expected, source_.Get());
}
template <class AllocatorT>
void Deserializer<AllocatorT>::DeserializeDeferredObjects() {
for (int code = source_.Get(); code != kSynchronize; code = source_.Get()) {
switch (code) {
case kAlignmentPrefix:
case kAlignmentPrefix + 1:
case kAlignmentPrefix + 2: {
int alignment = code - (SerializerDeserializer::kAlignmentPrefix - 1);
allocator()->SetAlignment(static_cast<AllocationAlignment>(alignment));
break;
}
default: {
int space = code & kSpaceMask;
DCHECK_LE(space, kNumberOfSpaces);
DCHECK_EQ(code - space, kNewObject);
HeapObject* object = GetBackReferencedObject(space);
int size = source_.GetInt() << kPointerSizeLog2;
Address obj_address = object->address();
MaybeObject** start =
reinterpret_cast<MaybeObject**>(obj_address + kPointerSize);
MaybeObject** end = reinterpret_cast<MaybeObject**>(obj_address + size);
bool filled = ReadData(start, end, space, obj_address);
CHECK(filled);
DCHECK(CanBeDeferred(object));
PostProcessNewObject(object, space);
}
}
}
}
StringTableInsertionKey::StringTableInsertionKey(String* string)
: StringTableKey(ComputeHashField(string)), string_(string) {
DCHECK(string->IsInternalizedString());
}
bool StringTableInsertionKey::IsMatch(Object* string) {
// We know that all entries in a hash table had their hash keys created.
// Use that knowledge to have fast failure.
if (Hash() != String::cast(string)->Hash()) return false;
// We want to compare the content of two internalized strings here.
return string_->SlowEquals(String::cast(string));
}
Handle<String> StringTableInsertionKey::AsHandle(Isolate* isolate) {
return handle(string_, isolate);
}
uint32_t StringTableInsertionKey::ComputeHashField(String* string) {
// Make sure hash_field() is computed.
string->Hash();
return string->hash_field();
}
template <class AllocatorT>
HeapObject* Deserializer<AllocatorT>::PostProcessNewObject(HeapObject* obj,
int space) {
if ((FLAG_rehash_snapshot && can_rehash_) || deserializing_user_code()) {
if (obj->IsString()) {
// Uninitialize hash field as we need to recompute the hash.
String* string = String::cast(obj);
string->set_hash_field(String::kEmptyHashField);
} else if (obj->NeedsRehashing()) {
to_rehash_.push_back(obj);
}
}
if (deserializing_user_code()) {
if (obj->IsString()) {
String* string = String::cast(obj);
if (string->IsInternalizedString()) {
// Canonicalize the internalized string. If it already exists in the
// string table, set it to forward to the existing one.
StringTableInsertionKey key(string);
String* canonical =
StringTable::ForwardStringIfExists(isolate_, &key, string);
if (canonical != nullptr) return canonical;
new_internalized_strings_.push_back(handle(string, isolate_));
return string;
}
} else if (obj->IsScript()) {
new_scripts_.push_back(handle(Script::cast(obj), isolate_));
} else {
DCHECK(CanBeDeferred(obj));
}
} else if (obj->IsScript()) {
LOG(isolate_, ScriptEvent(Logger::ScriptEventType::kDeserialize,
Script::cast(obj)->id()));
LOG(isolate_, ScriptDetails(Script::cast(obj)));
}
if (obj->IsAllocationSite()) {
// Allocation sites are present in the snapshot, and must be linked into
// a list at deserialization time.
AllocationSite* site = AllocationSite::cast(obj);
// TODO(mvstanton): consider treating the heap()->allocation_sites_list()
// as a (weak) root. If this root is relocated correctly, this becomes
// unnecessary.
if (isolate_->heap()->allocation_sites_list() == Smi::kZero) {
site->set_weak_next(ReadOnlyRoots(isolate_).undefined_value());
} else {
site->set_weak_next(isolate_->heap()->allocation_sites_list());
}
isolate_->heap()->set_allocation_sites_list(site);
} else if (obj->IsCode()) {
// We flush all code pages after deserializing the startup snapshot. In that
// case, we only need to remember code objects in the large object space.
// When deserializing user code, remember each individual code object.
if (deserializing_user_code() || space == LO_SPACE) {
new_code_objects_.push_back(Code::cast(obj));
}
} else if (obj->IsAccessorInfo()) {
#ifdef USE_SIMULATOR
accessor_infos_.push_back(AccessorInfo::cast(obj));
#endif
} else if (obj->IsCallHandlerInfo()) {
#ifdef USE_SIMULATOR
call_handler_infos_.push_back(CallHandlerInfo::cast(obj));
#endif
} else if (obj->IsExternalString()) {
if (obj->map() == ReadOnlyRoots(isolate_).native_source_string_map()) {
ExternalOneByteString* string = ExternalOneByteString::cast(obj);
DCHECK(string->is_short());
string->SetResource(
isolate_, NativesExternalStringResource::DecodeForDeserialization(
string->resource()));
} else {
ExternalString* string = ExternalString::cast(obj);
uint32_t index = string->resource_as_uint32();
Address address =
static_cast<Address>(isolate_->api_external_references()[index]);
string->set_address_as_resource(address);
isolate_->heap()->UpdateExternalString(string, 0,
string->ExternalPayloadSize());
}
isolate_->heap()->RegisterExternalString(String::cast(obj));
} else if (obj->IsJSTypedArray()) {
JSTypedArray* typed_array = JSTypedArray::cast(obj);
CHECK(typed_array->byte_offset()->IsSmi());
int32_t byte_offset = NumberToInt32(typed_array->byte_offset());
if (byte_offset > 0) {
FixedTypedArrayBase* elements =
FixedTypedArrayBase::cast(typed_array->elements());
// Must be off-heap layout.
DCHECK(!typed_array->is_on_heap());
void* pointer_with_offset = reinterpret_cast<void*>(
reinterpret_cast<intptr_t>(elements->external_pointer()) +
byte_offset);
elements->set_external_pointer(pointer_with_offset);
}
} else if (obj->IsJSArrayBuffer()) {
JSArrayBuffer* buffer = JSArrayBuffer::cast(obj);
// Only fixup for the off-heap case.
if (buffer->backing_store() != nullptr) {
Smi* store_index = reinterpret_cast<Smi*>(buffer->backing_store());
void* backing_store = off_heap_backing_stores_[store_index->value()];
buffer->set_backing_store(backing_store);
isolate_->heap()->RegisterNewArrayBuffer(buffer);
}
} else if (obj->IsFixedTypedArrayBase()) {
FixedTypedArrayBase* fta = FixedTypedArrayBase::cast(obj);
// Only fixup for the off-heap case.
if (fta->base_pointer() == nullptr) {
Smi* store_index = reinterpret_cast<Smi*>(fta->external_pointer());
void* backing_store = off_heap_backing_stores_[store_index->value()];
fta->set_external_pointer(backing_store);
}
} else if (obj->IsBytecodeArray()) {
// TODO(mythria): Remove these once we store the default values for these
// fields in the serializer.
BytecodeArray* bytecode_array = BytecodeArray::cast(obj);
bytecode_array->set_interrupt_budget(
interpreter::Interpreter::InterruptBudget());
bytecode_array->set_osr_loop_nesting_level(0);
}
// Check alignment.
DCHECK_EQ(0, Heap::GetFillToAlign(obj->address(),
HeapObject::RequiredAlignment(obj->map())));
return obj;
}
template <class AllocatorT>
int Deserializer<AllocatorT>::MaybeReplaceWithDeserializeLazy(int builtin_id) {
DCHECK(Builtins::IsBuiltinId(builtin_id));
return IsLazyDeserializationEnabled() && Builtins::IsLazy(builtin_id)
? Builtins::kDeserializeLazy
: builtin_id;
}
template <class AllocatorT>
HeapObject* Deserializer<AllocatorT>::GetBackReferencedObject(int space) {
HeapObject* obj;
switch (space) {
case LO_SPACE:
obj = allocator()->GetLargeObject(source_.GetInt());
break;
case MAP_SPACE:
obj = allocator()->GetMap(source_.GetInt());
break;
case RO_SPACE: {
uint32_t chunk_index = source_.GetInt();
uint32_t chunk_offset = source_.GetInt();
if (isolate()->heap()->deserialization_complete()) {
PagedSpace* read_only_space = isolate()->heap()->read_only_space();
Page* page = read_only_space->first_page();
for (uint32_t i = 0; i < chunk_index; ++i) {
page = page->next_page();
}
Address address = page->OffsetToAddress(chunk_offset);
obj = HeapObject::FromAddress(address);
} else {
obj = allocator()->GetObject(static_cast<AllocationSpace>(space),
chunk_index, chunk_offset);
}
break;
}
default: {
uint32_t chunk_index = source_.GetInt();
uint32_t chunk_offset = source_.GetInt();
obj = allocator()->GetObject(static_cast<AllocationSpace>(space),
chunk_index, chunk_offset);
break;
}
}
if (deserializing_user_code() && obj->IsThinString()) {
obj = ThinString::cast(obj)->actual();
}
hot_objects_.Add(obj);
DCHECK(!HasWeakHeapObjectTag(obj));
return obj;
}
// This routine writes the new object into the pointer provided.
// The reason for this strange interface is that otherwise the object is
// written very late, which means the FreeSpace map is not set up by the
// time we need to use it to mark the space at the end of a page free.
template <class AllocatorT>
void Deserializer<AllocatorT>::ReadObject(
int space_number, MaybeObject** write_back,
HeapObjectReferenceType reference_type) {
const int size = source_.GetInt() << kObjectAlignmentBits;
Address address =
allocator()->Allocate(static_cast<AllocationSpace>(space_number), size);
HeapObject* obj = HeapObject::FromAddress(address);
isolate_->heap()->OnAllocationEvent(obj, size);
MaybeObject** current = reinterpret_cast<MaybeObject**>(address);
MaybeObject** limit = current + (size >> kPointerSizeLog2);
if (ReadData(current, limit, space_number, address)) {
// Only post process if object content has not been deferred.
obj = PostProcessNewObject(obj, space_number);
}
MaybeObject* write_back_obj =
reference_type == HeapObjectReferenceType::STRONG
? HeapObjectReference::Strong(obj)
: HeapObjectReference::Weak(obj);
UnalignedCopy(write_back, &write_back_obj);
#ifdef DEBUG
if (obj->IsCode()) {
DCHECK(space_number == CODE_SPACE || space_number == LO_SPACE);
} else {
DCHECK(space_number != CODE_SPACE);
}
#endif // DEBUG
}
template <class AllocatorT>
Object* Deserializer<AllocatorT>::ReadDataSingle() {
MaybeObject* o;
MaybeObject** start = &o;
MaybeObject** end = start + 1;
int source_space = NEW_SPACE;
Address current_object = kNullAddress;
CHECK(ReadData(start, end, source_space, current_object));
HeapObject* heap_object;
bool success = o->ToStrongHeapObject(&heap_object);
DCHECK(success);
USE(success);
return heap_object;
}
static void NoExternalReferencesCallback() {
// The following check will trigger if a function or object template
// with references to native functions have been deserialized from
// snapshot, but no actual external references were provided when the
// isolate was created.
CHECK_WITH_MSG(false, "No external references provided via API");
}
template <class AllocatorT>
bool Deserializer<AllocatorT>::ReadData(MaybeObject** current,
MaybeObject** limit, int source_space,
Address current_object_address) {
Isolate* const isolate = isolate_;
// Write barrier support costs around 1% in startup time. In fact there
// are no new space objects in current boot snapshots, so it's not needed,
// but that may change.
bool write_barrier_needed =
(current_object_address != kNullAddress && source_space != NEW_SPACE &&
source_space != CODE_SPACE);
while (current < limit) {
byte data = source_.Get();
switch (data) {
#define CASE_STATEMENT(where, how, within, space_number) \
case where + how + within + space_number: \
STATIC_ASSERT((where & ~kWhereMask) == 0); \
STATIC_ASSERT((how & ~kHowToCodeMask) == 0); \
STATIC_ASSERT((within & ~kWhereToPointMask) == 0); \
STATIC_ASSERT((space_number & ~kSpaceMask) == 0);
#define CASE_BODY(where, how, within, space_number_if_any) \
current = ReadDataCase<where, how, within, space_number_if_any>( \
isolate, current, current_object_address, data, write_barrier_needed); \
break;
// This generates a case and a body for the new space (which has to do extra
// write barrier handling) and handles the other spaces with fall-through cases
// and one body.
#define ALL_SPACES(where, how, within) \
CASE_STATEMENT(where, how, within, NEW_SPACE) \
CASE_BODY(where, how, within, NEW_SPACE) \
CASE_STATEMENT(where, how, within, OLD_SPACE) \
V8_FALLTHROUGH; \
CASE_STATEMENT(where, how, within, CODE_SPACE) \
V8_FALLTHROUGH; \
CASE_STATEMENT(where, how, within, MAP_SPACE) \
V8_FALLTHROUGH; \
CASE_STATEMENT(where, how, within, LO_SPACE) \
V8_FALLTHROUGH; \
CASE_STATEMENT(where, how, within, RO_SPACE) \
CASE_BODY(where, how, within, kAnyOldSpace)
#define FOUR_CASES(byte_code) \
case byte_code: \
case byte_code + 1: \
case byte_code + 2: \
case byte_code + 3:
#define SIXTEEN_CASES(byte_code) \
FOUR_CASES(byte_code) \
FOUR_CASES(byte_code + 4) \
FOUR_CASES(byte_code + 8) \
FOUR_CASES(byte_code + 12)
#define SINGLE_CASE(where, how, within, space) \
CASE_STATEMENT(where, how, within, space) \
CASE_BODY(where, how, within, space)
// Deserialize a new object and write a pointer to it to the current
// object.
ALL_SPACES(kNewObject, kPlain, kStartOfObject)
// Deserialize a new code object and write a pointer to its first
// instruction to the current code object.
ALL_SPACES(kNewObject, kFromCode, kInnerPointer)
// Find a recently deserialized object using its offset from the current
// allocation point and write a pointer to it to the current object.
ALL_SPACES(kBackref, kPlain, kStartOfObject)
ALL_SPACES(kBackrefWithSkip, kPlain, kStartOfObject)
#if V8_CODE_EMBEDS_OBJECT_POINTER
// Deserialize a new object from pointer found in code and write
// a pointer to it to the current object. Required only for MIPS, PPC, ARM
// or S390 with embedded constant pool, and omitted on the other
// architectures because it is fully unrolled and would cause bloat.
ALL_SPACES(kNewObject, kFromCode, kStartOfObject)
// Find a recently deserialized code object using its offset from the
// current allocation point and write a pointer to it to the current
// object. Required only for MIPS, PPC, ARM or S390 with embedded
// constant pool.
ALL_SPACES(kBackref, kFromCode, kStartOfObject)
ALL_SPACES(kBackrefWithSkip, kFromCode, kStartOfObject)
#endif
// Find a recently deserialized code object using its offset from the
// current allocation point and write a pointer to its first instruction
// to the current code object or the instruction pointer in a function
// object.
ALL_SPACES(kBackref, kFromCode, kInnerPointer)
ALL_SPACES(kBackrefWithSkip, kFromCode, kInnerPointer)
// Find an object in the roots array and write a pointer to it to the
// current object.
SINGLE_CASE(kRootArray, kPlain, kStartOfObject, 0)
#if V8_CODE_EMBEDS_OBJECT_POINTER
// Find an object in the roots array and write a pointer to it to in code.
SINGLE_CASE(kRootArray, kFromCode, kStartOfObject, 0)
#endif
// Find an object in the partial snapshots cache and write a pointer to it
// to the current object.
SINGLE_CASE(kPartialSnapshotCache, kPlain, kStartOfObject, 0)
SINGLE_CASE(kPartialSnapshotCache, kFromCode, kStartOfObject, 0)
SINGLE_CASE(kPartialSnapshotCache, kFromCode, kInnerPointer, 0)
// Find an object in the attached references and write a pointer to it to
// the current object.
SINGLE_CASE(kAttachedReference, kPlain, kStartOfObject, 0)
SINGLE_CASE(kAttachedReference, kFromCode, kStartOfObject, 0)
SINGLE_CASE(kAttachedReference, kFromCode, kInnerPointer, 0)
// Find a builtin and write a pointer to it to the current object.
SINGLE_CASE(kBuiltin, kPlain, kStartOfObject, 0)
SINGLE_CASE(kBuiltin, kFromCode, kStartOfObject, 0)
SINGLE_CASE(kBuiltin, kFromCode, kInnerPointer, 0)
#undef CASE_STATEMENT
#undef CASE_BODY
#undef ALL_SPACES
case kSkip: {
int size = source_.GetInt();
current = reinterpret_cast<MaybeObject**>(
reinterpret_cast<Address>(current) + size);
break;
}
// Find an external reference and write a pointer to it to the current
// object.
case kExternalReference + kPlain + kStartOfObject:
current = reinterpret_cast<MaybeObject**>(ReadExternalReferenceCase(
kPlain, reinterpret_cast<void**>(current), current_object_address));
break;
// Find an external reference and write a pointer to it in the current
// code object.
case kExternalReference + kFromCode + kStartOfObject:
current = reinterpret_cast<MaybeObject**>(ReadExternalReferenceCase(
kFromCode, reinterpret_cast<void**>(current),
current_object_address));
break;
case kInternalReferenceEncoded:
case kInternalReference: {
// Internal reference address is not encoded via skip, but by offset
// from code entry.
int pc_offset = source_.GetInt();
int target_offset = source_.GetInt();
Code* code =
Code::cast(HeapObject::FromAddress(current_object_address));
DCHECK(0 <= pc_offset && pc_offset <= code->raw_instruction_size());
DCHECK(0 <= target_offset &&
target_offset <= code->raw_instruction_size());
Address pc = code->entry() + pc_offset;
Address target = code->entry() + target_offset;
Assembler::deserialization_set_target_internal_reference_at(
pc, target,
data == kInternalReference ? RelocInfo::INTERNAL_REFERENCE
: RelocInfo::INTERNAL_REFERENCE_ENCODED);
break;
}
case kOffHeapTarget: {
DCHECK(FLAG_embedded_builtins);
int skip = source_.GetInt();
int builtin_index = source_.GetInt();
DCHECK(Builtins::IsBuiltinId(builtin_index));
current = reinterpret_cast<MaybeObject**>(
reinterpret_cast<Address>(current) + skip);
CHECK_NOT_NULL(isolate->embedded_blob());
EmbeddedData d = EmbeddedData::FromBlob();
Address address = d.InstructionStartOfBuiltin(builtin_index);
CHECK_NE(kNullAddress, address);
if (RelocInfo::OffHeapTargetIsCodedSpecially()) {
Address location_of_branch_data = reinterpret_cast<Address>(current);
int skip = Assembler::deserialization_special_target_size(
location_of_branch_data);
Assembler::deserialization_set_special_target_at(
location_of_branch_data,
Code::cast(HeapObject::FromAddress(current_object_address)),
address);
location_of_branch_data += skip;
current = reinterpret_cast<MaybeObject**>(location_of_branch_data);
} else {
MaybeObject* o = reinterpret_cast<MaybeObject*>(address);
UnalignedCopy(current, &o);
current++;
}
break;
}
case kNop:
break;
case kNextChunk: {
int space = source_.Get();
allocator()->MoveToNextChunk(static_cast<AllocationSpace>(space));
break;
}
case kDeferred: {
// Deferred can only occur right after the heap object header.
DCHECK_EQ(current, reinterpret_cast<MaybeObject**>(
current_object_address + kPointerSize));
HeapObject* obj = HeapObject::FromAddress(current_object_address);
// If the deferred object is a map, its instance type may be used
// during deserialization. Initialize it with a temporary value.
if (obj->IsMap()) Map::cast(obj)->set_instance_type(FILLER_TYPE);
current = limit;
return false;
}
case kSynchronize:
// If we get here then that indicates that you have a mismatch between
// the number of GC roots when serializing and deserializing.
UNREACHABLE();
// Deserialize raw data of variable length.
case kVariableRawData: {
int size_in_bytes = source_.GetInt();
byte* raw_data_out = reinterpret_cast<byte*>(current);
source_.CopyRaw(raw_data_out, size_in_bytes);
current = reinterpret_cast<MaybeObject**>(
reinterpret_cast<intptr_t>(current) + size_in_bytes);
break;
}
// Deserialize raw code directly into the body of the code object.
// Do not move current.
case kVariableRawCode: {
int size_in_bytes = source_.GetInt();
source_.CopyRaw(
reinterpret_cast<byte*>(current_object_address + Code::kDataStart),
size_in_bytes);
break;
}
case kVariableRepeat: {
int repeats = source_.GetInt();
MaybeObject* object = current[-1];
DCHECK(!Heap::InNewSpace(object));
DCHECK(!allocator()->next_reference_is_weak());
for (int i = 0; i < repeats; i++) UnalignedCopy(current++, &object);
break;
}
case kOffHeapBackingStore: {
int byte_length = source_.GetInt();
byte* backing_store = static_cast<byte*>(
isolate->array_buffer_allocator()->AllocateUninitialized(
byte_length));
CHECK_NOT_NULL(backing_store);
source_.CopyRaw(backing_store, byte_length);
off_heap_backing_stores_.push_back(backing_store);
break;
}
case kApiReference: {
int skip = source_.GetInt();
current = reinterpret_cast<MaybeObject**>(
reinterpret_cast<Address>(current) + skip);
uint32_t reference_id = static_cast<uint32_t>(source_.GetInt());
Address address;
if (isolate->api_external_references()) {
DCHECK_WITH_MSG(
reference_id < num_api_references_,
"too few external references provided through the API");
address = static_cast<Address>(
isolate->api_external_references()[reference_id]);
} else {
address = reinterpret_cast<Address>(NoExternalReferencesCallback);
}
memcpy(current, &address, kPointerSize);
current++;
break;
}
case kWeakPrefix:
DCHECK(!allocator()->next_reference_is_weak());
allocator()->set_next_reference_is_weak(true);
break;
case kAlignmentPrefix:
case kAlignmentPrefix + 1:
case kAlignmentPrefix + 2: {
int alignment = data - (SerializerDeserializer::kAlignmentPrefix - 1);
allocator()->SetAlignment(static_cast<AllocationAlignment>(alignment));
break;
}
STATIC_ASSERT(kNumberOfRootArrayConstants == Heap::kOldSpaceRoots);
STATIC_ASSERT(kNumberOfRootArrayConstants == 32);
SIXTEEN_CASES(kRootArrayConstantsWithSkip)
SIXTEEN_CASES(kRootArrayConstantsWithSkip + 16) {
int skip = source_.GetInt();
current = reinterpret_cast<MaybeObject**>(
reinterpret_cast<intptr_t>(current) + skip);
V8_FALLTHROUGH;
}
SIXTEEN_CASES(kRootArrayConstants)
SIXTEEN_CASES(kRootArrayConstants + 16) {
int id = data & kRootArrayConstantsMask;
Heap::RootListIndex root_index = static_cast<Heap::RootListIndex>(id);
MaybeObject* object =
MaybeObject::FromObject(isolate->heap()->root(root_index));
DCHECK(!Heap::InNewSpace(object));
DCHECK(!allocator()->next_reference_is_weak());
UnalignedCopy(current++, &object);
break;
}
STATIC_ASSERT(kNumberOfHotObjects == 8);
FOUR_CASES(kHotObjectWithSkip)
FOUR_CASES(kHotObjectWithSkip + 4) {
int skip = source_.GetInt();
current = reinterpret_cast<MaybeObject**>(
reinterpret_cast<Address>(current) + skip);
V8_FALLTHROUGH;
}
FOUR_CASES(kHotObject)
FOUR_CASES(kHotObject + 4) {
int index = data & kHotObjectMask;
Object* hot_object = hot_objects_.Get(index);
MaybeObject* hot_maybe_object = MaybeObject::FromObject(hot_object);
if (allocator()->GetAndClearNextReferenceIsWeak()) {
hot_maybe_object = MaybeObject::MakeWeak(hot_maybe_object);
}
UnalignedCopy(current, &hot_maybe_object);
if (write_barrier_needed && Heap::InNewSpace(hot_object)) {
Address current_address = reinterpret_cast<Address>(current);
GenerationalBarrier(HeapObject::FromAddress(current_object_address),
reinterpret_cast<MaybeObject**>(current_address),
hot_maybe_object);
}
current++;
break;
}
// Deserialize raw data of fixed length from 1 to 32 words.
STATIC_ASSERT(kNumberOfFixedRawData == 32);
SIXTEEN_CASES(kFixedRawData)
SIXTEEN_CASES(kFixedRawData + 16) {
byte* raw_data_out = reinterpret_cast<byte*>(current);
int size_in_bytes = (data - kFixedRawDataStart) << kPointerSizeLog2;
source_.CopyRaw(raw_data_out, size_in_bytes);
current = reinterpret_cast<MaybeObject**>(raw_data_out + size_in_bytes);
break;
}
STATIC_ASSERT(kNumberOfFixedRepeat == 16);
SIXTEEN_CASES(kFixedRepeat) {
int repeats = data - kFixedRepeatStart;
MaybeObject* object;
DCHECK(!allocator()->next_reference_is_weak());
UnalignedCopy(&object, current - 1);
DCHECK(!Heap::InNewSpace(object));
for (int i = 0; i < repeats; i++) UnalignedCopy(current++, &object);
break;
}
#ifdef DEBUG
#define UNUSED_CASE(byte_code) \
case byte_code: \
UNREACHABLE();
UNUSED_SERIALIZER_BYTE_CODES(UNUSED_CASE)
#endif
#undef UNUSED_CASE
#undef SIXTEEN_CASES
#undef FOUR_CASES
#undef SINGLE_CASE
}
}
CHECK_EQ(limit, current);
return true;
}
template <class AllocatorT>
void** Deserializer<AllocatorT>::ReadExternalReferenceCase(
HowToCode how, void** current, Address current_object_address) {
int skip = source_.GetInt();
current = reinterpret_cast<void**>(reinterpret_cast<Address>(current) + skip);
uint32_t reference_id = static_cast<uint32_t>(source_.GetInt());
Address address = external_reference_table_->address(reference_id);
if (how == kFromCode) {
Address location_of_branch_data = reinterpret_cast<Address>(current);
int skip =
Assembler::deserialization_special_target_size(location_of_branch_data);
Assembler::deserialization_set_special_target_at(
location_of_branch_data,
Code::cast(HeapObject::FromAddress(current_object_address)), address);
location_of_branch_data += skip;
current = reinterpret_cast<void**>(location_of_branch_data);
} else {
void* new_current = reinterpret_cast<void**>(address);
UnalignedCopy(current, &new_current);
++current;
}
return current;
}
template <class AllocatorT>
template <int where, int how, int within, int space_number_if_any>
MaybeObject** Deserializer<AllocatorT>::ReadDataCase(
Isolate* isolate, MaybeObject** current, Address current_object_address,
byte data, bool write_barrier_needed) {
bool emit_write_barrier = false;
bool current_was_incremented = false;
int space_number = space_number_if_any == kAnyOldSpace ? (data & kSpaceMask)
: space_number_if_any;
HeapObjectReferenceType reference_type = HeapObjectReferenceType::STRONG;
if (where == kNewObject && how == kPlain && within == kStartOfObject) {
if (allocator()->GetAndClearNextReferenceIsWeak()) {
reference_type = HeapObjectReferenceType::WEAK;
}
ReadObject(space_number, current, reference_type);
emit_write_barrier = (space_number == NEW_SPACE);
} else {
Object* new_object = nullptr; /* May not be a real Object pointer. */
if (where == kNewObject) {
ReadObject(space_number, reinterpret_cast<MaybeObject**>(&new_object),
HeapObjectReferenceType::STRONG);
} else if (where == kBackref) {
emit_write_barrier = (space_number == NEW_SPACE);
new_object = GetBackReferencedObject(data & kSpaceMask);
} else if (where == kBackrefWithSkip) {
int skip = source_.GetInt();
current = reinterpret_cast<MaybeObject**>(
reinterpret_cast<Address>(current) + skip);
emit_write_barrier = (space_number == NEW_SPACE);
new_object = GetBackReferencedObject(data & kSpaceMask);
} else if (where == kRootArray) {
int id = source_.GetInt();
Heap::RootListIndex root_index = static_cast<Heap::RootListIndex>(id);
new_object = isolate->heap()->root(root_index);
emit_write_barrier = Heap::InNewSpace(new_object);
hot_objects_.Add(HeapObject::cast(new_object));
} else if (where == kPartialSnapshotCache) {
int cache_index = source_.GetInt();
new_object = isolate->partial_snapshot_cache()->at(cache_index);
emit_write_barrier = Heap::InNewSpace(new_object);
} else if (where == kAttachedReference) {
int index = source_.GetInt();
new_object = *attached_objects_[index];
emit_write_barrier = Heap::InNewSpace(new_object);
} else {
DCHECK_EQ(where, kBuiltin);
int builtin_id = MaybeReplaceWithDeserializeLazy(source_.GetInt());
new_object = isolate->builtins()->builtin(builtin_id);
emit_write_barrier = false;
}
if (within == kInnerPointer) {
DCHECK_EQ(how, kFromCode);
if (where == kBuiltin) {
// At this point, new_object may still be uninitialized, thus the
// unchecked Code cast.
new_object = reinterpret_cast<Object*>(
reinterpret_cast<Code*>(new_object)->raw_instruction_start());
} else if (new_object->IsCode()) {
new_object = reinterpret_cast<Object*>(
Code::cast(new_object)->raw_instruction_start());
} else {
Cell* cell = Cell::cast(new_object);
new_object = reinterpret_cast<Object*>(cell->ValueAddress());
}
}
if (how == kFromCode) {
DCHECK(!allocator()->next_reference_is_weak());
Address location_of_branch_data = reinterpret_cast<Address>(current);
int skip = Assembler::deserialization_special_target_size(
location_of_branch_data);
Assembler::deserialization_set_special_target_at(
location_of_branch_data,
Code::cast(HeapObject::FromAddress(current_object_address)),
reinterpret_cast<Address>(new_object));
location_of_branch_data += skip;
current = reinterpret_cast<MaybeObject**>(location_of_branch_data);
current_was_incremented = true;
} else {
MaybeObject* new_maybe_object = MaybeObject::FromObject(new_object);
if (allocator()->GetAndClearNextReferenceIsWeak()) {
new_maybe_object = MaybeObject::MakeWeak(new_maybe_object);
}
UnalignedCopy(current, &new_maybe_object);
}
}
if (emit_write_barrier && write_barrier_needed) {
Address current_address = reinterpret_cast<Address>(current);
SLOW_DCHECK(isolate->heap()->ContainsSlow(current_object_address));
GenerationalBarrier(HeapObject::FromAddress(current_object_address),
reinterpret_cast<MaybeObject**>(current_address),
*reinterpret_cast<MaybeObject**>(current_address));
}
if (!current_was_incremented) {
current++;
}
return current;
}
// Explicit instantiation.
template class Deserializer<BuiltinDeserializerAllocator>;
template class Deserializer<DefaultDeserializerAllocator>;
} // namespace internal
} // namespace v8
|