// 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/codegen/assembler-inl.h" #include "src/execution/isolate.h" #include "src/heap/heap-inl.h" #include "src/heap/heap-write-barrier-inl.h" #include "src/heap/read-only-heap.h" #include "src/interpreter/interpreter.h" #include "src/logging/log.h" #include "src/objects/api-callbacks.h" #include "src/objects/cell-inl.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/objects-body-descriptors-inl.h" #include "src/objects/slots.h" #include "src/objects/smi.h" #include "src/objects/string.h" #include "src/roots/roots.h" #include "src/snapshot/natives.h" #include "src/snapshot/snapshot.h" #include "src/tracing/trace-event.h" #include "src/tracing/traced-value.h" namespace v8 { namespace internal { template <typename TSlot> TSlot Deserializer::Write(TSlot dest, MaybeObject value) { DCHECK(!allocator()->next_reference_is_weak()); dest.store(value); return dest + 1; } template <typename TSlot> TSlot Deserializer::WriteAddress(TSlot dest, Address value) { DCHECK(!allocator()->next_reference_is_weak()); memcpy(dest.ToVoidPtr(), &value, kSystemPointerSize); STATIC_ASSERT(IsAligned(kSystemPointerSize, TSlot::kSlotDataSize)); return dest + (kSystemPointerSize / TSlot::kSlotDataSize); } void Deserializer::Initialize(Isolate* isolate) { DCHECK_NULL(isolate_); DCHECK_NOT_NULL(isolate); isolate_ = isolate; allocator()->Initialize(isolate->heap()); #ifdef DEBUG // The read-only deserializer is run by read-only heap set-up before the heap // is fully set up. External reference table relies on a few parts of this // set-up (like old-space), so it may be uninitialized at this point. if (isolate->isolate_data()->external_reference_table()->is_initialized()) { // 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::kMagicNumber); } void Deserializer::Rehash() { DCHECK(can_rehash() || deserializing_user_code()); for (HeapObject item : to_rehash_) { item.RehashBasedOnMap(ReadOnlyRoots(isolate_)); } } Deserializer::~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. void Deserializer::VisitRootPointers(Root root, const char* description, FullObjectSlot start, FullObjectSlot end) { // We are reading to a location outside of JS heap, so pass kNew to avoid // triggering write barriers. ReadData(FullMaybeObjectSlot(start), FullMaybeObjectSlot(end), SnapshotSpace::kNew, kNullAddress); } void Deserializer::Synchronize(VisitorSynchronization::SyncTag tag) { static const byte expected = kSynchronize; CHECK_EQ(expected, source_.Get()); } void Deserializer::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: { const int space_number = code & kSpaceMask; DCHECK_LE(space_number, kNumberOfSpaces); DCHECK_EQ(code - space_number, kNewObject); SnapshotSpace space = static_cast<SnapshotSpace>(space_number); HeapObject object = GetBackReferencedObject(space); int size = source_.GetInt() << kTaggedSizeLog2; Address obj_address = object.address(); // Object's map is already initialized, now read the rest. MaybeObjectSlot start(obj_address + kTaggedSize); MaybeObjectSlot end(obj_address + size); bool filled = ReadData(start, end, space, obj_address); CHECK(filled); DCHECK(CanBeDeferred(object)); PostProcessNewObject(object, space); } } } } void Deserializer::LogNewObjectEvents() { { // {new_maps_} and {new_code_objects_} are vectors containing raw // pointers, hence there should be no GC happening. DisallowHeapAllocation no_gc; // Issue code events for newly deserialized code objects. LOG_CODE_EVENT(isolate_, LogCodeObjects()); } LOG_CODE_EVENT(isolate_, LogCompiledFunctions()); LogNewMapEvents(); } void Deserializer::LogNewMapEvents() { DisallowHeapAllocation no_gc; for (Map map : new_maps()) { DCHECK(FLAG_trace_maps); LOG(isolate_, MapCreate(map)); LOG(isolate_, MapDetails(map)); } } void Deserializer::LogScriptEvents(Script script) { DisallowHeapAllocation no_gc; LOG(isolate_, ScriptEvent(Logger::ScriptEventType::kDeserialize, script.id())); LOG(isolate_, ScriptDetails(script)); TRACE_EVENT_OBJECT_CREATED_WITH_ID( TRACE_DISABLED_BY_DEFAULT("v8.compile"), "Script", TRACE_ID_WITH_SCOPE("v8::internal::Script", script.id())); TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID( TRACE_DISABLED_BY_DEFAULT("v8.compile"), "Script", TRACE_ID_WITH_SCOPE("v8::internal::Script", script.id()), script.ToTracedValue()); } StringTableInsertionKey::StringTableInsertionKey(String string) : StringTableKey(ComputeHashField(string), string.length()), string_(string) { DCHECK(string.IsInternalizedString()); } bool StringTableInsertionKey::IsMatch(String string) { // We want to compare the content of two strings here. return string_.SlowEquals(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(); } namespace { String ForwardStringIfExists(Isolate* isolate, StringTableInsertionKey* key) { StringTable table = isolate->heap()->string_table(); int entry = table.FindEntry(isolate, key); if (entry == kNotFound) return String(); String canonical = String::cast(table.KeyAt(entry)); DCHECK_NE(canonical, key->string()); key->string().MakeThin(isolate, canonical); return canonical; } } // namespace HeapObject Deserializer::PostProcessNewObject(HeapObject obj, SnapshotSpace 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); // Rehash strings before read-only space is sealed. Strings outside // read-only space are rehashed lazily. (e.g. when rehashing dictionaries) if (space == SnapshotSpace::kReadOnlyHeap) { to_rehash_.push_back(obj); } } 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 = ForwardStringIfExists(isolate_, &key); if (!canonical.is_null()) 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 if (obj.IsAllocationSite()) { // We should link new allocation sites, but we can't do this immediately // because |AllocationSite::HasWeakNext()| internally accesses // |Heap::roots_| that may not have been initialized yet. So defer this to // |ObjectDeserializer::CommitPostProcessedObjects()|. new_allocation_sites_.push_back(AllocationSite::cast(obj)); } else { DCHECK(CanBeDeferred(obj)); } } if (obj.IsScript()) { LogScriptEvents(Script::cast(obj)); } else if (obj.IsCode()) { // We flush all code pages after deserializing the startup snapshot. // Hence we only remember each individual code object when deserializing // user code. if (deserializing_user_code() || space == SnapshotSpace::kLargeObject) { new_code_objects_.push_back(Code::cast(obj)); } } else if (FLAG_trace_maps && obj.IsMap()) { // Keep track of all seen Maps to log them later since they might be only // partially initialized at this point. new_maps_.push_back(Map::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_uncached()); 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.IsJSDataView()) { JSDataView data_view = JSDataView::cast(obj); JSArrayBuffer buffer = JSArrayBuffer::cast(data_view.buffer()); data_view.set_data_pointer( reinterpret_cast<uint8_t*>(buffer.backing_store()) + data_view.byte_offset()); } else if (obj.IsJSTypedArray()) { JSTypedArray typed_array = JSTypedArray::cast(obj); // Fixup typed array pointers. if (typed_array.is_on_heap()) { typed_array.SetOnHeapDataPtr(HeapObject::cast(typed_array.base_pointer()), typed_array.external_pointer()); } else { // Serializer writes backing store ref as a DataPtr() value. size_t store_index = reinterpret_cast<size_t>(typed_array.DataPtr()); auto backing_store = backing_stores_[store_index]; auto start = backing_store ? reinterpret_cast<byte*>(backing_store->buffer_start()) : nullptr; typed_array.SetOffHeapDataPtr(start, typed_array.byte_offset()); } } else if (obj.IsJSArrayBuffer()) { JSArrayBuffer buffer = JSArrayBuffer::cast(obj); // Only fixup for the off-heap case. if (buffer.backing_store() != nullptr) { // Serializer writes backing store ref in |backing_store| field. size_t store_index = reinterpret_cast<size_t>(buffer.backing_store()); auto backing_store = backing_stores_[store_index]; SharedFlag shared = backing_store && backing_store->is_shared() ? SharedFlag::kShared : SharedFlag::kNotShared; buffer.Setup(shared, 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_osr_loop_nesting_level(0); } #ifdef DEBUG if (obj.IsDescriptorArray()) { DescriptorArray descriptor_array = DescriptorArray::cast(obj); DCHECK_EQ(0, descriptor_array.raw_number_of_marked_descriptors()); } #endif // Check alignment. DCHECK_EQ(0, Heap::GetFillToAlign(obj.address(), HeapObject::RequiredAlignment(obj.map()))); return obj; } HeapObject Deserializer::GetBackReferencedObject(SnapshotSpace space) { HeapObject obj; switch (space) { case SnapshotSpace::kLargeObject: obj = allocator()->GetLargeObject(source_.GetInt()); break; case SnapshotSpace::kMap: obj = allocator()->GetMap(source_.GetInt()); break; case SnapshotSpace::kReadOnlyHeap: { 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(space, chunk_index, chunk_offset); } break; } default: { uint32_t chunk_index = source_.GetInt(); uint32_t chunk_offset = source_.GetInt(); obj = allocator()->GetObject(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; } HeapObject Deserializer::ReadObject() { MaybeObject object; // We are reading to a location outside of JS heap, so pass kNew to avoid // triggering write barriers. bool filled = ReadData(FullMaybeObjectSlot(&object), FullMaybeObjectSlot(&object + 1), SnapshotSpace::kNew, kNullAddress); CHECK(filled); return object.GetHeapObjectAssumeStrong(); } HeapObject Deserializer::ReadObject(SnapshotSpace space) { const int size = source_.GetInt() << kObjectAlignmentBits; Address address = allocator()->Allocate(space, size); HeapObject obj = HeapObject::FromAddress(address); isolate_->heap()->OnAllocationEvent(obj, size); MaybeObjectSlot current(address); MaybeObjectSlot limit(address + size); if (ReadData(current, limit, space, address)) { // Only post process if object content has not been deferred. obj = PostProcessNewObject(obj, space); } #ifdef DEBUG if (obj.IsCode()) { DCHECK_EQ(space, SnapshotSpace::kCode); } else { DCHECK_NE(space, SnapshotSpace::kCode); } #endif // DEBUG return obj; } void Deserializer::ReadCodeObjectBody(SnapshotSpace space, Address code_object_address) { // At this point the code object is already allocated, its map field is // initialized and its raw data fields and code stream are also read. // Now we read the rest of code header's fields. MaybeObjectSlot current(code_object_address + HeapObject::kHeaderSize); MaybeObjectSlot limit(code_object_address + Code::kDataStart); bool filled = ReadData(current, limit, space, code_object_address); CHECK(filled); // Now iterate RelocInfos the same way it was done by the serialzier and // deserialize respective data into RelocInfos. Code code = Code::cast(HeapObject::FromAddress(code_object_address)); RelocIterator it(code, Code::BodyDescriptor::kRelocModeMask); for (; !it.done(); it.next()) { RelocInfo rinfo = *it.rinfo(); rinfo.Visit(this); } } void Deserializer::VisitCodeTarget(Code host, RelocInfo* rinfo) { HeapObject object = ReadObject(); rinfo->set_target_address(Code::cast(object).raw_instruction_start()); } void Deserializer::VisitEmbeddedPointer(Code host, RelocInfo* rinfo) { HeapObject object = ReadObject(); // Embedded object reference must be a strong one. rinfo->set_target_object(isolate_->heap(), object); } void Deserializer::VisitRuntimeEntry(Code host, RelocInfo* rinfo) { // We no longer serialize code that contains runtime entries. UNREACHABLE(); } void Deserializer::VisitExternalReference(Code host, RelocInfo* rinfo) { byte data = source_.Get(); CHECK_EQ(data, kExternalReference); Address address = ReadExternalReferenceCase(); if (rinfo->IsCodedSpecially()) { Address location_of_branch_data = rinfo->pc(); Assembler::deserialization_set_special_target_at(location_of_branch_data, host, address); } else { WriteUnalignedValue(rinfo->target_address_address(), address); } } void Deserializer::VisitInternalReference(Code host, RelocInfo* rinfo) { byte data = source_.Get(); CHECK_EQ(data, kInternalReference); // Internal reference target is encoded as an offset from code entry. int target_offset = source_.GetInt(); DCHECK_LT(static_cast<unsigned>(target_offset), static_cast<unsigned>(host.raw_instruction_size())); Address target = host.entry() + target_offset; Assembler::deserialization_set_target_internal_reference_at( rinfo->pc(), target, rinfo->rmode()); } void Deserializer::VisitOffHeapTarget(Code host, RelocInfo* rinfo) { DCHECK(FLAG_embedded_builtins); byte data = source_.Get(); CHECK_EQ(data, kOffHeapTarget); int builtin_index = source_.GetInt(); DCHECK(Builtins::IsBuiltinId(builtin_index)); CHECK_NOT_NULL(isolate_->embedded_blob()); EmbeddedData d = EmbeddedData::FromBlob(); Address address = d.InstructionStartOfBuiltin(builtin_index); CHECK_NE(kNullAddress, address); // TODO(ishell): implement RelocInfo::set_target_off_heap_target() if (RelocInfo::OffHeapTargetIsCodedSpecially()) { Address location_of_branch_data = rinfo->pc(); Assembler::deserialization_set_special_target_at(location_of_branch_data, host, address); } else { WriteUnalignedValue(rinfo->target_address_address(), address); } } template <typename TSlot> TSlot Deserializer::ReadRepeatedObject(TSlot current, int repeat_count) { CHECK_LE(2, repeat_count); HeapObject heap_object = ReadObject(); DCHECK(!Heap::InYoungGeneration(heap_object)); for (int i = 0; i < repeat_count; i++) { // Repeated values are not subject to the write barrier so we don't need // to trigger it. current = Write(current, MaybeObject::FromObject(heap_object)); } return current; } 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 <typename TSlot> bool Deserializer::ReadData(TSlot current, TSlot limit, SnapshotSpace 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 != SnapshotSpace::kNew && source_space != SnapshotSpace::kCode && !FLAG_disable_write_barriers); while (current < limit) { byte data = source_.Get(); switch (data) { #define CASE_STATEMENT(bytecode, snapshot_space) \ case bytecode + static_cast<int>(snapshot_space): \ STATIC_ASSERT((static_cast<int>(snapshot_space) & ~kSpaceMask) == 0); #define CASE_BODY(bytecode, space_number_if_any) \ current = ReadDataCase<TSlot, bytecode, 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(bytecode) \ CASE_STATEMENT(bytecode, SnapshotSpace::kNew) \ CASE_BODY(bytecode, SnapshotSpace::kNew) \ CASE_STATEMENT(bytecode, SnapshotSpace::kOld) \ V8_FALLTHROUGH; \ CASE_STATEMENT(bytecode, SnapshotSpace::kCode) \ V8_FALLTHROUGH; \ CASE_STATEMENT(bytecode, SnapshotSpace::kMap) \ V8_FALLTHROUGH; \ CASE_STATEMENT(bytecode, SnapshotSpace::kLargeObject) \ V8_FALLTHROUGH; \ CASE_STATEMENT(bytecode, SnapshotSpace::kReadOnlyHeap) \ CASE_BODY(bytecode, 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(bytecode, space) \ CASE_STATEMENT(bytecode, space) \ CASE_BODY(bytecode, space) // Deserialize a new object and write a pointer to it to the current // object. ALL_SPACES(kNewObject) // 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) // Find an object in the roots array and write a pointer to it to the // current object. SINGLE_CASE(kRootArray, SnapshotSpace::kReadOnlyHeap) // Find an object in the partial snapshots cache and write a pointer to it // to the current object. SINGLE_CASE(kPartialSnapshotCache, SnapshotSpace::kReadOnlyHeap) // Find an object in the partial snapshots cache and write a pointer to it // to the current object. SINGLE_CASE(kReadOnlyObjectCache, SnapshotSpace::kReadOnlyHeap) // Find an object in the attached references and write a pointer to it to // the current object. SINGLE_CASE(kAttachedReference, SnapshotSpace::kReadOnlyHeap) #undef CASE_STATEMENT #undef CASE_BODY #undef ALL_SPACES // Find an external reference and write a pointer to it to the current // object. case kExternalReference: { Address address = ReadExternalReferenceCase(); current = WriteAddress(current, address); break; } case kInternalReference: case kOffHeapTarget: { // These bytecodes are expected only during RelocInfo iteration. UNREACHABLE(); break; } case kNop: break; case kNextChunk: { int space = source_.Get(); allocator()->MoveToNextChunk(static_cast<SnapshotSpace>(space)); break; } case kDeferred: { // Deferred can only occur right after the heap object header. DCHECK_EQ(current.address(), current_object_address + kTaggedSize); 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(); DCHECK(IsAligned(size_in_bytes, kTaggedSize)); source_.CopyRaw(current.ToVoidPtr(), size_in_bytes); current = TSlot(current.address() + size_in_bytes); break; } // Deserialize raw code directly into the body of the code object. case kVariableRawCode: { // VariableRawCode can only occur right after the heap object header. DCHECK_EQ(current.address(), current_object_address + kTaggedSize); int size_in_bytes = source_.GetInt(); DCHECK(IsAligned(size_in_bytes, kTaggedSize)); source_.CopyRaw( reinterpret_cast<void*>(current_object_address + Code::kDataStart), size_in_bytes); // Deserialize tagged fields in the code object header and reloc infos. ReadCodeObjectBody(source_space, current_object_address); // Set current to the code object end. current = TSlot(current.address() + Code::kDataStart - HeapObject::kHeaderSize + size_in_bytes); CHECK_EQ(current, limit); break; } case kVariableRepeat: { int repeats = DecodeVariableRepeatCount(source_.GetInt()); current = ReadRepeatedObject(current, repeats); break; } case kOffHeapBackingStore: { int byte_length = source_.GetInt(); std::unique_ptr<BackingStore> backing_store = BackingStore::Allocate(isolate, byte_length, SharedFlag::kNotShared, InitializedFlag::kUninitialized); CHECK_NOT_NULL(backing_store); source_.CopyRaw(backing_store->buffer_start(), byte_length); backing_stores_.push_back(std::move(backing_store)); break; } case kApiReference: { 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); } current = WriteAddress(current, address); break; } case kClearedWeakReference: current = Write(current, HeapObjectReference::ClearedValue(isolate_)); 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; } // First kNumberOfRootArrayConstants roots are guaranteed to be in // the old space. STATIC_ASSERT( static_cast<int>(RootIndex::kFirstImmortalImmovableRoot) == 0); STATIC_ASSERT(kNumberOfRootArrayConstants <= static_cast<int>(RootIndex::kLastImmortalImmovableRoot)); STATIC_ASSERT(kNumberOfRootArrayConstants == 32); SIXTEEN_CASES(kRootArrayConstants) SIXTEEN_CASES(kRootArrayConstants + 16) { int id = data & kRootArrayConstantsMask; RootIndex root_index = static_cast<RootIndex>(id); MaybeObject object = MaybeObject::FromObject(isolate->root(root_index)); DCHECK(!Heap::InYoungGeneration(object)); current = Write(current, object); break; } STATIC_ASSERT(kNumberOfHotObjects == 8); 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); } // Don't update current pointer here as it may be needed for write // barrier. Write(current, hot_maybe_object); if (write_barrier_needed && Heap::InYoungGeneration(hot_object)) { HeapObject current_object = HeapObject::FromAddress(current_object_address); GenerationalBarrier(current_object, MaybeObjectSlot(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) { int size_in_tagged = data - kFixedRawDataStart; source_.CopyRaw(current.ToVoidPtr(), size_in_tagged * kTaggedSize); current += size_in_tagged; break; } STATIC_ASSERT(kNumberOfFixedRepeat == 16); SIXTEEN_CASES(kFixedRepeat) { int repeats = DecodeFixedRepeatCount(data); current = ReadRepeatedObject(current, repeats); 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; } Address Deserializer::ReadExternalReferenceCase() { uint32_t reference_id = static_cast<uint32_t>(source_.GetInt()); return isolate_->external_reference_table()->address(reference_id); } template <typename TSlot, SerializerDeserializer::Bytecode bytecode, SnapshotSpace space_number_if_any> TSlot Deserializer::ReadDataCase(Isolate* isolate, TSlot current, Address current_object_address, byte data, bool write_barrier_needed) { bool emit_write_barrier = false; SnapshotSpace space = static_cast<SnapshotSpace>( space_number_if_any == kAnyOldSpace ? static_cast<SnapshotSpace>(data & kSpaceMask) : space_number_if_any); HeapObject heap_object; HeapObjectReferenceType reference_type = allocator()->GetAndClearNextReferenceIsWeak() ? HeapObjectReferenceType::WEAK : HeapObjectReferenceType::STRONG; if (bytecode == kNewObject) { heap_object = ReadObject(space); emit_write_barrier = (space == SnapshotSpace::kNew); } else if (bytecode == kBackref) { heap_object = GetBackReferencedObject(space); emit_write_barrier = (space == SnapshotSpace::kNew); } else if (bytecode == kRootArray) { int id = source_.GetInt(); RootIndex root_index = static_cast<RootIndex>(id); heap_object = HeapObject::cast(isolate->root(root_index)); emit_write_barrier = Heap::InYoungGeneration(heap_object); hot_objects_.Add(heap_object); } else if (bytecode == kReadOnlyObjectCache) { int cache_index = source_.GetInt(); heap_object = HeapObject::cast( isolate->read_only_heap()->cached_read_only_object(cache_index)); DCHECK(!Heap::InYoungGeneration(heap_object)); emit_write_barrier = false; } else if (bytecode == kPartialSnapshotCache) { int cache_index = source_.GetInt(); heap_object = HeapObject::cast(isolate->partial_snapshot_cache()->at(cache_index)); emit_write_barrier = Heap::InYoungGeneration(heap_object); } else { DCHECK_EQ(bytecode, kAttachedReference); int index = source_.GetInt(); heap_object = *attached_objects_[index]; emit_write_barrier = Heap::InYoungGeneration(heap_object); } HeapObjectReference heap_object_ref = reference_type == HeapObjectReferenceType::STRONG ? HeapObjectReference::Strong(heap_object) : HeapObjectReference::Weak(heap_object); // Don't update current pointer here as it may be needed for write barrier. Write(current, heap_object_ref); if (emit_write_barrier && write_barrier_needed) { DCHECK_IMPLIES(FLAG_disable_write_barriers, !write_barrier_needed); HeapObject host_object = HeapObject::FromAddress(current_object_address); SLOW_DCHECK(isolate->heap()->Contains(host_object)); GenerationalBarrier(host_object, MaybeObjectSlot(current.address()), heap_object_ref); } return current + 1; } } // namespace internal } // namespace v8