| // 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/serializer.h" |
| |
| #include "src/codegen/assembler-inl.h" |
| #include "src/heap/heap-inl.h" // For Space::identity(). |
| #include "src/heap/read-only-heap.h" |
| #include "src/interpreter/interpreter.h" |
| #include "src/objects/code.h" |
| #include "src/objects/js-array-buffer-inl.h" |
| #include "src/objects/js-array-inl.h" |
| #include "src/objects/map.h" |
| #include "src/objects/slots-inl.h" |
| #include "src/objects/smi.h" |
| #include "src/snapshot/natives.h" |
| #include "src/snapshot/snapshot.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| Serializer::Serializer(Isolate* isolate) |
| : isolate_(isolate), |
| external_reference_encoder_(isolate), |
| root_index_map_(isolate), |
| allocator_(this) { |
| #ifdef OBJECT_PRINT |
| if (FLAG_serialization_statistics) { |
| for (int space = 0; space < kNumberOfSpaces; ++space) { |
| instance_type_count_[space] = NewArray<int>(kInstanceTypes); |
| instance_type_size_[space] = NewArray<size_t>(kInstanceTypes); |
| for (int i = 0; i < kInstanceTypes; i++) { |
| instance_type_count_[space][i] = 0; |
| instance_type_size_[space][i] = 0; |
| } |
| } |
| } else { |
| for (int space = 0; space < kNumberOfSpaces; ++space) { |
| instance_type_count_[space] = nullptr; |
| instance_type_size_[space] = nullptr; |
| } |
| } |
| #endif // OBJECT_PRINT |
| } |
| |
| Serializer::~Serializer() { |
| if (code_address_map_ != nullptr) delete code_address_map_; |
| #ifdef OBJECT_PRINT |
| for (int space = 0; space < kNumberOfSpaces; ++space) { |
| if (instance_type_count_[space] != nullptr) { |
| DeleteArray(instance_type_count_[space]); |
| DeleteArray(instance_type_size_[space]); |
| } |
| } |
| #endif // OBJECT_PRINT |
| } |
| |
| #ifdef OBJECT_PRINT |
| void Serializer::CountInstanceType(Map map, int size, SnapshotSpace space) { |
| const int space_number = static_cast<int>(space); |
| int instance_type = map.instance_type(); |
| instance_type_count_[space_number][instance_type]++; |
| instance_type_size_[space_number][instance_type] += size; |
| } |
| #endif // OBJECT_PRINT |
| |
| void Serializer::OutputStatistics(const char* name) { |
| if (!FLAG_serialization_statistics) return; |
| |
| PrintF("%s:\n", name); |
| allocator()->OutputStatistics(); |
| |
| #ifdef OBJECT_PRINT |
| PrintF(" Instance types (count and bytes):\n"); |
| #define PRINT_INSTANCE_TYPE(Name) \ |
| for (int space = 0; space < kNumberOfSpaces; ++space) { \ |
| if (instance_type_count_[space][Name]) { \ |
| PrintF("%10d %10zu %-10s %s\n", instance_type_count_[space][Name], \ |
| instance_type_size_[space][Name], \ |
| Heap::GetSpaceName(static_cast<AllocationSpace>(space)), #Name); \ |
| } \ |
| } |
| INSTANCE_TYPE_LIST(PRINT_INSTANCE_TYPE) |
| #undef PRINT_INSTANCE_TYPE |
| |
| PrintF("\n"); |
| #endif // OBJECT_PRINT |
| } |
| |
| void Serializer::SerializeDeferredObjects() { |
| while (!deferred_objects_.empty()) { |
| HeapObject obj = deferred_objects_.back(); |
| deferred_objects_.pop_back(); |
| ObjectSerializer obj_serializer(this, obj, &sink_); |
| obj_serializer.SerializeDeferred(); |
| } |
| sink_.Put(kSynchronize, "Finished with deferred objects"); |
| } |
| |
| bool Serializer::MustBeDeferred(HeapObject object) { return false; } |
| |
| void Serializer::VisitRootPointers(Root root, const char* description, |
| FullObjectSlot start, FullObjectSlot end) { |
| for (FullObjectSlot current = start; current < end; ++current) { |
| SerializeRootObject(*current); |
| } |
| } |
| |
| void Serializer::SerializeRootObject(Object object) { |
| if (object.IsSmi()) { |
| PutSmi(Smi::cast(object)); |
| } else { |
| SerializeObject(HeapObject::cast(object)); |
| } |
| } |
| |
| #ifdef DEBUG |
| void Serializer::PrintStack() { PrintStack(std::cout); } |
| |
| void Serializer::PrintStack(std::ostream& out) { |
| for (const auto o : stack_) { |
| o.Print(out); |
| out << "\n"; |
| } |
| } |
| #endif // DEBUG |
| |
| bool Serializer::SerializeRoot(HeapObject obj) { |
| RootIndex root_index; |
| // Derived serializers are responsible for determining if the root has |
| // actually been serialized before calling this. |
| if (root_index_map()->Lookup(obj, &root_index)) { |
| PutRoot(root_index, obj); |
| return true; |
| } |
| return false; |
| } |
| |
| bool Serializer::SerializeHotObject(HeapObject obj) { |
| // Encode a reference to a hot object by its index in the working set. |
| int index = hot_objects_.Find(obj); |
| if (index == HotObjectsList::kNotFound) return false; |
| DCHECK(index >= 0 && index < kNumberOfHotObjects); |
| if (FLAG_trace_serializer) { |
| PrintF(" Encoding hot object %d:", index); |
| obj.ShortPrint(); |
| PrintF("\n"); |
| } |
| sink_.Put(kHotObject + index, "HotObject"); |
| return true; |
| } |
| |
| bool Serializer::SerializeBackReference(HeapObject obj) { |
| SerializerReference reference = |
| reference_map_.LookupReference(reinterpret_cast<void*>(obj.ptr())); |
| if (!reference.is_valid()) return false; |
| // Encode the location of an already deserialized object in order to write |
| // its location into a later object. We can encode the location as an |
| // offset fromthe start of the deserialized objects or as an offset |
| // backwards from thecurrent allocation pointer. |
| if (reference.is_attached_reference()) { |
| if (FLAG_trace_serializer) { |
| PrintF(" Encoding attached reference %d\n", |
| reference.attached_reference_index()); |
| } |
| PutAttachedReference(reference); |
| } else { |
| DCHECK(reference.is_back_reference()); |
| if (FLAG_trace_serializer) { |
| PrintF(" Encoding back reference to: "); |
| obj.ShortPrint(); |
| PrintF("\n"); |
| } |
| |
| PutAlignmentPrefix(obj); |
| SnapshotSpace space = reference.space(); |
| sink_.Put(kBackref + static_cast<int>(space), "BackRef"); |
| PutBackReference(obj, reference); |
| } |
| return true; |
| } |
| |
| bool Serializer::ObjectIsBytecodeHandler(HeapObject obj) const { |
| if (!obj.IsCode()) return false; |
| return (Code::cast(obj).kind() == Code::BYTECODE_HANDLER); |
| } |
| |
| void Serializer::PutRoot(RootIndex root, HeapObject object) { |
| int root_index = static_cast<int>(root); |
| if (FLAG_trace_serializer) { |
| PrintF(" Encoding root %d:", root_index); |
| object.ShortPrint(); |
| PrintF("\n"); |
| } |
| |
| // Assert that the first 32 root array items are a conscious choice. They are |
| // chosen so that the most common ones can be encoded more efficiently. |
| STATIC_ASSERT(static_cast<int>(RootIndex::kArgumentsMarker) == |
| kNumberOfRootArrayConstants - 1); |
| |
| // TODO(ulan): Check that it works with young large objects. |
| if (root_index < kNumberOfRootArrayConstants && |
| !Heap::InYoungGeneration(object)) { |
| sink_.Put(kRootArrayConstants + root_index, "RootConstant"); |
| } else { |
| sink_.Put(kRootArray, "RootSerialization"); |
| sink_.PutInt(root_index, "root_index"); |
| hot_objects_.Add(object); |
| } |
| } |
| |
| void Serializer::PutSmi(Smi smi) { |
| sink_.Put(kOnePointerRawData, "Smi"); |
| Tagged_t raw_value = static_cast<Tagged_t>(smi.ptr()); |
| byte bytes[kTaggedSize]; |
| memcpy(bytes, &raw_value, kTaggedSize); |
| for (int i = 0; i < kTaggedSize; i++) sink_.Put(bytes[i], "Byte"); |
| } |
| |
| void Serializer::PutBackReference(HeapObject object, |
| SerializerReference reference) { |
| DCHECK(allocator()->BackReferenceIsAlreadyAllocated(reference)); |
| switch (reference.space()) { |
| case SnapshotSpace::kMap: |
| sink_.PutInt(reference.map_index(), "BackRefMapIndex"); |
| break; |
| |
| case SnapshotSpace::kLargeObject: |
| sink_.PutInt(reference.large_object_index(), "BackRefLargeObjectIndex"); |
| break; |
| |
| default: |
| sink_.PutInt(reference.chunk_index(), "BackRefChunkIndex"); |
| sink_.PutInt(reference.chunk_offset(), "BackRefChunkOffset"); |
| break; |
| } |
| |
| hot_objects_.Add(object); |
| } |
| |
| void Serializer::PutAttachedReference(SerializerReference reference) { |
| DCHECK(reference.is_attached_reference()); |
| sink_.Put(kAttachedReference, "AttachedRef"); |
| sink_.PutInt(reference.attached_reference_index(), "AttachedRefIndex"); |
| } |
| |
| int Serializer::PutAlignmentPrefix(HeapObject object) { |
| AllocationAlignment alignment = HeapObject::RequiredAlignment(object.map()); |
| if (alignment != kWordAligned) { |
| DCHECK(1 <= alignment && alignment <= 3); |
| byte prefix = (kAlignmentPrefix - 1) + alignment; |
| sink_.Put(prefix, "Alignment"); |
| return Heap::GetMaximumFillToAlign(alignment); |
| } |
| return 0; |
| } |
| |
| void Serializer::PutNextChunk(SnapshotSpace space) { |
| sink_.Put(kNextChunk, "NextChunk"); |
| sink_.Put(static_cast<int>(space), "NextChunkSpace"); |
| } |
| |
| void Serializer::PutRepeat(int repeat_count) { |
| if (repeat_count <= kLastEncodableFixedRepeatCount) { |
| sink_.Put(EncodeFixedRepeat(repeat_count), "FixedRepeat"); |
| } else { |
| sink_.Put(kVariableRepeat, "VariableRepeat"); |
| sink_.PutInt(EncodeVariableRepeatCount(repeat_count), "repeat count"); |
| } |
| } |
| |
| void Serializer::Pad(int padding_offset) { |
| // The non-branching GetInt will read up to 3 bytes too far, so we need |
| // to pad the snapshot to make sure we don't read over the end. |
| for (unsigned i = 0; i < sizeof(int32_t) - 1; i++) { |
| sink_.Put(kNop, "Padding"); |
| } |
| // Pad up to pointer size for checksum. |
| while (!IsAligned(sink_.Position() + padding_offset, kPointerAlignment)) { |
| sink_.Put(kNop, "Padding"); |
| } |
| } |
| |
| void Serializer::InitializeCodeAddressMap() { |
| isolate_->InitializeLoggingAndCounters(); |
| code_address_map_ = new CodeAddressMap(isolate_); |
| } |
| |
| Code Serializer::CopyCode(Code code) { |
| code_buffer_.clear(); // Clear buffer without deleting backing store. |
| int size = code.CodeSize(); |
| code_buffer_.insert(code_buffer_.end(), |
| reinterpret_cast<byte*>(code.address()), |
| reinterpret_cast<byte*>(code.address() + size)); |
| // When pointer compression is enabled the checked cast will try to |
| // decompress map field of off-heap Code object. |
| return Code::unchecked_cast(HeapObject::FromAddress( |
| reinterpret_cast<Address>(&code_buffer_.front()))); |
| } |
| |
| void Serializer::ObjectSerializer::SerializePrologue(SnapshotSpace space, |
| int size, Map map) { |
| if (serializer_->code_address_map_) { |
| const char* code_name = |
| serializer_->code_address_map_->Lookup(object_.address()); |
| LOG(serializer_->isolate_, |
| CodeNameEvent(object_.address(), sink_->Position(), code_name)); |
| } |
| |
| const int space_number = static_cast<int>(space); |
| SerializerReference back_reference; |
| if (space == SnapshotSpace::kLargeObject) { |
| sink_->Put(kNewObject + space_number, "NewLargeObject"); |
| sink_->PutInt(size >> kObjectAlignmentBits, "ObjectSizeInWords"); |
| CHECK(!object_.IsCode()); |
| back_reference = serializer_->allocator()->AllocateLargeObject(size); |
| } else if (space == SnapshotSpace::kMap) { |
| DCHECK_EQ(Map::kSize, size); |
| back_reference = serializer_->allocator()->AllocateMap(); |
| sink_->Put(kNewObject + space_number, "NewMap"); |
| // This is redundant, but we include it anyways. |
| sink_->PutInt(size >> kObjectAlignmentBits, "ObjectSizeInWords"); |
| } else { |
| int fill = serializer_->PutAlignmentPrefix(object_); |
| back_reference = serializer_->allocator()->Allocate(space, size + fill); |
| sink_->Put(kNewObject + space_number, "NewObject"); |
| sink_->PutInt(size >> kObjectAlignmentBits, "ObjectSizeInWords"); |
| } |
| |
| #ifdef OBJECT_PRINT |
| if (FLAG_serialization_statistics) { |
| serializer_->CountInstanceType(map, size, space); |
| } |
| #endif // OBJECT_PRINT |
| |
| // Mark this object as already serialized. |
| serializer_->reference_map()->Add(reinterpret_cast<void*>(object_.ptr()), |
| back_reference); |
| |
| // Serialize the map (first word of the object). |
| serializer_->SerializeObject(map); |
| } |
| |
| int32_t Serializer::ObjectSerializer::SerializeBackingStore( |
| void* backing_store, int32_t byte_length) { |
| SerializerReference reference = |
| serializer_->reference_map()->LookupReference(backing_store); |
| |
| // Serialize the off-heap backing store. |
| if (!reference.is_valid()) { |
| sink_->Put(kOffHeapBackingStore, "Off-heap backing store"); |
| sink_->PutInt(byte_length, "length"); |
| sink_->PutRaw(static_cast<byte*>(backing_store), byte_length, |
| "BackingStore"); |
| reference = serializer_->allocator()->AllocateOffHeapBackingStore(); |
| // Mark this backing store as already serialized. |
| serializer_->reference_map()->Add(backing_store, reference); |
| } |
| |
| return static_cast<int32_t>(reference.off_heap_backing_store_index()); |
| } |
| |
| void Serializer::ObjectSerializer::SerializeJSTypedArray() { |
| JSTypedArray typed_array = JSTypedArray::cast(object_); |
| if (!typed_array.WasDetached()) { |
| if (!typed_array.is_on_heap()) { |
| // Explicitly serialize the backing store now. |
| JSArrayBuffer buffer = JSArrayBuffer::cast(typed_array.buffer()); |
| CHECK_LE(buffer.byte_length(), Smi::kMaxValue); |
| CHECK_LE(typed_array.byte_offset(), Smi::kMaxValue); |
| int32_t byte_length = static_cast<int32_t>(buffer.byte_length()); |
| int32_t byte_offset = static_cast<int32_t>(typed_array.byte_offset()); |
| |
| // We need to calculate the backing store from the external pointer |
| // because the ArrayBuffer may already have been serialized. |
| void* backing_store = reinterpret_cast<void*>( |
| reinterpret_cast<intptr_t>(typed_array.external_pointer()) - |
| byte_offset); |
| int32_t ref = SerializeBackingStore(backing_store, byte_length); |
| |
| // The external_pointer is the backing_store + typed_array->byte_offset. |
| // To properly share the buffer, we set the backing store ref here. On |
| // deserialization we re-add the byte_offset to external_pointer. |
| typed_array.set_external_pointer( |
| reinterpret_cast<void*>(Smi::FromInt(ref).ptr())); |
| } |
| } else { |
| typed_array.set_external_pointer(nullptr); |
| } |
| SerializeObject(); |
| } |
| |
| void Serializer::ObjectSerializer::SerializeJSArrayBuffer() { |
| JSArrayBuffer buffer = JSArrayBuffer::cast(object_); |
| void* backing_store = buffer.backing_store(); |
| // We cannot store byte_length larger than Smi range in the snapshot. |
| CHECK_LE(buffer.byte_length(), Smi::kMaxValue); |
| int32_t byte_length = static_cast<int32_t>(buffer.byte_length()); |
| |
| // The embedder-allocated backing store only exists for the off-heap case. |
| if (backing_store != nullptr) { |
| int32_t ref = SerializeBackingStore(backing_store, byte_length); |
| buffer.set_backing_store(reinterpret_cast<void*>(Smi::FromInt(ref).ptr())); |
| } |
| SerializeObject(); |
| buffer.set_backing_store(backing_store); |
| } |
| |
| void Serializer::ObjectSerializer::SerializeExternalString() { |
| Heap* heap = serializer_->isolate()->heap(); |
| // For external strings with known resources, we replace the resource field |
| // with the encoded external reference, which we restore upon deserialize. |
| // for native native source code strings, we replace the resource field |
| // with the native source id. |
| // For the rest we serialize them to look like ordinary sequential strings. |
| if (object_.map() != ReadOnlyRoots(heap).native_source_string_map()) { |
| ExternalString string = ExternalString::cast(object_); |
| Address resource = string.resource_as_address(); |
| ExternalReferenceEncoder::Value reference; |
| if (serializer_->external_reference_encoder_.TryEncode(resource).To( |
| &reference)) { |
| DCHECK(reference.is_from_api()); |
| string.set_uint32_as_resource(reference.index()); |
| SerializeObject(); |
| string.set_address_as_resource(resource); |
| } else { |
| SerializeExternalStringAsSequentialString(); |
| } |
| } else { |
| ExternalOneByteString string = ExternalOneByteString::cast(object_); |
| DCHECK(string.is_uncached()); |
| const NativesExternalStringResource* resource = |
| reinterpret_cast<const NativesExternalStringResource*>( |
| string.resource()); |
| // Replace the resource field with the type and index of the native source. |
| string.set_resource(resource->EncodeForSerialization()); |
| SerializeObject(); |
| // Restore the resource field. |
| string.set_resource(resource); |
| } |
| } |
| |
| void Serializer::ObjectSerializer::SerializeExternalStringAsSequentialString() { |
| // Instead of serializing this as an external string, we serialize |
| // an imaginary sequential string with the same content. |
| ReadOnlyRoots roots(serializer_->isolate()); |
| DCHECK(object_.IsExternalString()); |
| DCHECK(object_.map() != roots.native_source_string_map()); |
| ExternalString string = ExternalString::cast(object_); |
| int length = string.length(); |
| Map map; |
| int content_size; |
| int allocation_size; |
| const byte* resource; |
| // Find the map and size for the imaginary sequential string. |
| bool internalized = object_.IsInternalizedString(); |
| if (object_.IsExternalOneByteString()) { |
| map = internalized ? roots.one_byte_internalized_string_map() |
| : roots.one_byte_string_map(); |
| allocation_size = SeqOneByteString::SizeFor(length); |
| content_size = length * kCharSize; |
| resource = reinterpret_cast<const byte*>( |
| ExternalOneByteString::cast(string).resource()->data()); |
| } else { |
| map = internalized ? roots.internalized_string_map() : roots.string_map(); |
| allocation_size = SeqTwoByteString::SizeFor(length); |
| content_size = length * kShortSize; |
| resource = reinterpret_cast<const byte*>( |
| ExternalTwoByteString::cast(string).resource()->data()); |
| } |
| |
| SnapshotSpace space = (allocation_size > kMaxRegularHeapObjectSize) |
| ? SnapshotSpace::kLargeObject |
| : SnapshotSpace::kOld; |
| SerializePrologue(space, allocation_size, map); |
| |
| // Output the rest of the imaginary string. |
| int bytes_to_output = allocation_size - HeapObject::kHeaderSize; |
| DCHECK(IsAligned(bytes_to_output, kTaggedSize)); |
| |
| // Output raw data header. Do not bother with common raw length cases here. |
| sink_->Put(kVariableRawData, "RawDataForString"); |
| sink_->PutInt(bytes_to_output, "length"); |
| |
| // Serialize string header (except for map). |
| uint8_t* string_start = reinterpret_cast<uint8_t*>(string.address()); |
| for (int i = HeapObject::kHeaderSize; i < SeqString::kHeaderSize; i++) { |
| sink_->PutSection(string_start[i], "StringHeader"); |
| } |
| |
| // Serialize string content. |
| sink_->PutRaw(resource, content_size, "StringContent"); |
| |
| // Since the allocation size is rounded up to object alignment, there |
| // maybe left-over bytes that need to be padded. |
| int padding_size = allocation_size - SeqString::kHeaderSize - content_size; |
| DCHECK(0 <= padding_size && padding_size < kObjectAlignment); |
| for (int i = 0; i < padding_size; i++) sink_->PutSection(0, "StringPadding"); |
| } |
| |
| // Clear and later restore the next link in the weak cell or allocation site. |
| // TODO(all): replace this with proper iteration of weak slots in serializer. |
| class UnlinkWeakNextScope { |
| public: |
| explicit UnlinkWeakNextScope(Heap* heap, HeapObject object) { |
| if (object.IsAllocationSite() && |
| AllocationSite::cast(object).HasWeakNext()) { |
| object_ = object; |
| next_ = AllocationSite::cast(object).weak_next(); |
| AllocationSite::cast(object).set_weak_next( |
| ReadOnlyRoots(heap).undefined_value()); |
| } |
| } |
| |
| ~UnlinkWeakNextScope() { |
| if (!object_.is_null()) { |
| AllocationSite::cast(object_).set_weak_next(next_, |
| UPDATE_WEAK_WRITE_BARRIER); |
| } |
| } |
| |
| private: |
| HeapObject object_; |
| Object next_; |
| DISALLOW_HEAP_ALLOCATION(no_gc_) |
| }; |
| |
| void Serializer::ObjectSerializer::Serialize() { |
| if (FLAG_trace_serializer) { |
| PrintF(" Encoding heap object: "); |
| object_.ShortPrint(); |
| PrintF("\n"); |
| } |
| |
| if (object_.IsExternalString()) { |
| SerializeExternalString(); |
| return; |
| } else if (!ReadOnlyHeap::Contains(object_)) { |
| // Only clear padding for strings outside the read-only heap. Read-only heap |
| // should have been cleared elsewhere. |
| if (object_.IsSeqOneByteString()) { |
| // Clear padding bytes at the end. Done here to avoid having to do this |
| // at allocation sites in generated code. |
| SeqOneByteString::cast(object_).clear_padding(); |
| } else if (object_.IsSeqTwoByteString()) { |
| SeqTwoByteString::cast(object_).clear_padding(); |
| } |
| } |
| if (object_.IsJSTypedArray()) { |
| SerializeJSTypedArray(); |
| return; |
| } |
| if (object_.IsJSArrayBuffer()) { |
| SerializeJSArrayBuffer(); |
| return; |
| } |
| |
| // We don't expect fillers. |
| DCHECK(!object_.IsFiller()); |
| |
| if (object_.IsScript()) { |
| // Clear cached line ends. |
| Object undefined = ReadOnlyRoots(serializer_->isolate()).undefined_value(); |
| Script::cast(object_).set_line_ends(undefined); |
| } |
| |
| SerializeObject(); |
| } |
| |
| void Serializer::ObjectSerializer::SerializeObject() { |
| int size = object_.Size(); |
| Map map = object_.map(); |
| SnapshotSpace space; |
| if (ReadOnlyHeap::Contains(object_)) { |
| space = SnapshotSpace::kReadOnlyHeap; |
| } else { |
| AllocationSpace heap_space = |
| MemoryChunk::FromHeapObject(object_)->owner_identity(); |
| // Large code objects are not supported and cannot be expressed by |
| // SnapshotSpace. |
| DCHECK_NE(heap_space, CODE_LO_SPACE); |
| // Young generation large objects are tenured. |
| if (heap_space == NEW_LO_SPACE) { |
| space = SnapshotSpace::kLargeObject; |
| } else { |
| space = static_cast<SnapshotSpace>(heap_space); |
| } |
| } |
| SerializePrologue(space, size, map); |
| |
| // Serialize the rest of the object. |
| CHECK_EQ(0, bytes_processed_so_far_); |
| bytes_processed_so_far_ = kTaggedSize; |
| |
| RecursionScope recursion(serializer_); |
| // Objects that are immediately post processed during deserialization |
| // cannot be deferred, since post processing requires the object content. |
| if ((recursion.ExceedsMaximum() && CanBeDeferred(object_)) || |
| serializer_->MustBeDeferred(object_)) { |
| serializer_->QueueDeferredObject(object_); |
| sink_->Put(kDeferred, "Deferring object content"); |
| return; |
| } |
| |
| SerializeContent(map, size); |
| } |
| |
| void Serializer::ObjectSerializer::SerializeDeferred() { |
| if (FLAG_trace_serializer) { |
| PrintF(" Encoding deferred heap object: "); |
| object_.ShortPrint(); |
| PrintF("\n"); |
| } |
| |
| int size = object_.Size(); |
| Map map = object_.map(); |
| SerializerReference back_reference = |
| serializer_->reference_map()->LookupReference( |
| reinterpret_cast<void*>(object_.ptr())); |
| DCHECK(back_reference.is_back_reference()); |
| |
| // Serialize the rest of the object. |
| CHECK_EQ(0, bytes_processed_so_far_); |
| bytes_processed_so_far_ = kTaggedSize; |
| |
| serializer_->PutAlignmentPrefix(object_); |
| sink_->Put(kNewObject + static_cast<int>(back_reference.space()), |
| "deferred object"); |
| serializer_->PutBackReference(object_, back_reference); |
| sink_->PutInt(size >> kTaggedSizeLog2, "deferred object size"); |
| |
| SerializeContent(map, size); |
| } |
| |
| void Serializer::ObjectSerializer::SerializeContent(Map map, int size) { |
| UnlinkWeakNextScope unlink_weak_next(serializer_->isolate()->heap(), object_); |
| if (object_.IsCode()) { |
| // For code objects, output raw bytes first. |
| OutputCode(size); |
| // Then iterate references via reloc info. |
| object_.IterateBody(map, size, this); |
| } else { |
| // For other objects, iterate references first. |
| object_.IterateBody(map, size, this); |
| // Then output data payload, if any. |
| OutputRawData(object_.address() + size); |
| } |
| } |
| |
| void Serializer::ObjectSerializer::VisitPointers(HeapObject host, |
| ObjectSlot start, |
| ObjectSlot end) { |
| VisitPointers(host, MaybeObjectSlot(start), MaybeObjectSlot(end)); |
| } |
| |
| void Serializer::ObjectSerializer::VisitPointers(HeapObject host, |
| MaybeObjectSlot start, |
| MaybeObjectSlot end) { |
| MaybeObjectSlot current = start; |
| while (current < end) { |
| while (current < end && (*current)->IsSmi()) { |
| ++current; |
| } |
| if (current < end) { |
| OutputRawData(current.address()); |
| } |
| // TODO(ishell): Revisit this change once we stick to 32-bit compressed |
| // tagged values. |
| while (current < end && (*current)->IsCleared()) { |
| sink_->Put(kClearedWeakReference, "ClearedWeakReference"); |
| bytes_processed_so_far_ += kTaggedSize; |
| ++current; |
| } |
| HeapObject current_contents; |
| HeapObjectReferenceType reference_type; |
| while (current < end && |
| (*current)->GetHeapObject(¤t_contents, &reference_type)) { |
| RootIndex root_index; |
| // Compute repeat count and write repeat prefix if applicable. |
| // Repeats are not subject to the write barrier so we can only use |
| // immortal immovable root members. They are never in new space. |
| MaybeObjectSlot repeat_end = current + 1; |
| if (repeat_end < end && |
| serializer_->root_index_map()->Lookup(current_contents, |
| &root_index) && |
| RootsTable::IsImmortalImmovable(root_index) && |
| *current == *repeat_end) { |
| DCHECK_EQ(reference_type, HeapObjectReferenceType::STRONG); |
| DCHECK(!Heap::InYoungGeneration(current_contents)); |
| while (repeat_end < end && *repeat_end == *current) { |
| repeat_end++; |
| } |
| int repeat_count = static_cast<int>(repeat_end - current); |
| current = repeat_end; |
| bytes_processed_so_far_ += repeat_count * kTaggedSize; |
| serializer_->PutRepeat(repeat_count); |
| } else { |
| bytes_processed_so_far_ += kTaggedSize; |
| ++current; |
| } |
| // Now write the object itself. |
| if (reference_type == HeapObjectReferenceType::WEAK) { |
| sink_->Put(kWeakPrefix, "WeakReference"); |
| } |
| serializer_->SerializeObject(current_contents); |
| } |
| } |
| } |
| |
| void Serializer::ObjectSerializer::VisitEmbeddedPointer(Code host, |
| RelocInfo* rinfo) { |
| Object object = rinfo->target_object(); |
| serializer_->SerializeObject(HeapObject::cast(object)); |
| bytes_processed_so_far_ += rinfo->target_address_size(); |
| } |
| |
| void Serializer::ObjectSerializer::VisitExternalReference(Foreign host, |
| Address* p) { |
| auto encoded_reference = |
| serializer_->EncodeExternalReference(host.foreign_address()); |
| if (encoded_reference.is_from_api()) { |
| sink_->Put(kApiReference, "ApiRef"); |
| } else { |
| sink_->Put(kExternalReference, "ExternalRef"); |
| } |
| sink_->PutInt(encoded_reference.index(), "reference index"); |
| bytes_processed_so_far_ += kSystemPointerSize; |
| } |
| |
| void Serializer::ObjectSerializer::VisitExternalReference(Code host, |
| RelocInfo* rinfo) { |
| Address target = rinfo->target_external_reference(); |
| auto encoded_reference = serializer_->EncodeExternalReference(target); |
| if (encoded_reference.is_from_api()) { |
| DCHECK(!rinfo->IsCodedSpecially()); |
| sink_->Put(kApiReference, "ApiRef"); |
| } else { |
| sink_->Put(kExternalReference, "ExternalRef"); |
| } |
| DCHECK_NE(target, kNullAddress); // Code does not reference null. |
| sink_->PutInt(encoded_reference.index(), "reference index"); |
| bytes_processed_so_far_ += rinfo->target_address_size(); |
| } |
| |
| void Serializer::ObjectSerializer::VisitInternalReference(Code host, |
| RelocInfo* rinfo) { |
| Address entry = Code::cast(object_).entry(); |
| DCHECK_GE(rinfo->target_internal_reference(), entry); |
| uintptr_t target_offset = rinfo->target_internal_reference() - entry; |
| DCHECK_LE(target_offset, Code::cast(object_).raw_instruction_size()); |
| sink_->Put(kInternalReference, "InternalRef"); |
| sink_->PutInt(target_offset, "internal ref value"); |
| } |
| |
| void Serializer::ObjectSerializer::VisitRuntimeEntry(Code host, |
| RelocInfo* rinfo) { |
| // We no longer serialize code that contains runtime entries. |
| UNREACHABLE(); |
| } |
| |
| void Serializer::ObjectSerializer::VisitOffHeapTarget(Code host, |
| RelocInfo* rinfo) { |
| DCHECK(FLAG_embedded_builtins); |
| STATIC_ASSERT(EmbeddedData::kTableSize == Builtins::builtin_count); |
| |
| Address addr = rinfo->target_off_heap_target(); |
| CHECK_NE(kNullAddress, addr); |
| |
| Code target = InstructionStream::TryLookupCode(serializer_->isolate(), addr); |
| CHECK(Builtins::IsIsolateIndependentBuiltin(target)); |
| |
| sink_->Put(kOffHeapTarget, "OffHeapTarget"); |
| sink_->PutInt(target.builtin_index(), "builtin index"); |
| bytes_processed_so_far_ += rinfo->target_address_size(); |
| } |
| |
| void Serializer::ObjectSerializer::VisitCodeTarget(Code host, |
| RelocInfo* rinfo) { |
| #ifdef V8_TARGET_ARCH_ARM |
| DCHECK(!RelocInfo::IsRelativeCodeTarget(rinfo->rmode())); |
| #endif |
| Code object = Code::GetCodeFromTargetAddress(rinfo->target_address()); |
| serializer_->SerializeObject(object); |
| bytes_processed_so_far_ += rinfo->target_address_size(); |
| } |
| |
| namespace { |
| |
| // Similar to OutputRawData, but substitutes the given field with the given |
| // value instead of reading it from the object. |
| void OutputRawWithCustomField(SnapshotByteSink* sink, Address object_start, |
| int written_so_far, int bytes_to_write, |
| int field_offset, int field_size, |
| const byte* field_value) { |
| int offset = field_offset - written_so_far; |
| if (0 <= offset && offset < bytes_to_write) { |
| DCHECK_GE(bytes_to_write, offset + field_size); |
| sink->PutRaw(reinterpret_cast<byte*>(object_start + written_so_far), offset, |
| "Bytes"); |
| sink->PutRaw(field_value, field_size, "Bytes"); |
| written_so_far += offset + field_size; |
| bytes_to_write -= offset + field_size; |
| sink->PutRaw(reinterpret_cast<byte*>(object_start + written_so_far), |
| bytes_to_write, "Bytes"); |
| } else { |
| sink->PutRaw(reinterpret_cast<byte*>(object_start + written_so_far), |
| bytes_to_write, "Bytes"); |
| } |
| } |
| } // anonymous namespace |
| |
| void Serializer::ObjectSerializer::OutputRawData(Address up_to) { |
| Address object_start = object_.address(); |
| int base = bytes_processed_so_far_; |
| int up_to_offset = static_cast<int>(up_to - object_start); |
| int to_skip = up_to_offset - bytes_processed_so_far_; |
| int bytes_to_output = to_skip; |
| bytes_processed_so_far_ += to_skip; |
| DCHECK_GE(to_skip, 0); |
| if (bytes_to_output != 0) { |
| DCHECK(to_skip == bytes_to_output); |
| if (IsAligned(bytes_to_output, kObjectAlignment) && |
| bytes_to_output <= kNumberOfFixedRawData * kTaggedSize) { |
| int size_in_words = bytes_to_output >> kTaggedSizeLog2; |
| sink_->PutSection(kFixedRawDataStart + size_in_words, "FixedRawData"); |
| } else { |
| sink_->Put(kVariableRawData, "VariableRawData"); |
| sink_->PutInt(bytes_to_output, "length"); |
| } |
| #ifdef MEMORY_SANITIZER |
| // Check that we do not serialize uninitialized memory. |
| __msan_check_mem_is_initialized( |
| reinterpret_cast<void*>(object_start + base), bytes_to_output); |
| #endif // MEMORY_SANITIZER |
| if (object_.IsBytecodeArray()) { |
| // The bytecode age field can be changed by GC concurrently. |
| byte field_value = BytecodeArray::kNoAgeBytecodeAge; |
| OutputRawWithCustomField(sink_, object_start, base, bytes_to_output, |
| BytecodeArray::kBytecodeAgeOffset, |
| sizeof(field_value), &field_value); |
| } else if (object_.IsDescriptorArray()) { |
| // The number of marked descriptors field can be changed by GC |
| // concurrently. |
| byte field_value[2]; |
| field_value[0] = 0; |
| field_value[1] = 0; |
| OutputRawWithCustomField( |
| sink_, object_start, base, bytes_to_output, |
| DescriptorArray::kRawNumberOfMarkedDescriptorsOffset, |
| sizeof(field_value), field_value); |
| } else { |
| sink_->PutRaw(reinterpret_cast<byte*>(object_start + base), |
| bytes_to_output, "Bytes"); |
| } |
| } |
| } |
| |
| void Serializer::ObjectSerializer::OutputCode(int size) { |
| DCHECK_EQ(kTaggedSize, bytes_processed_so_far_); |
| Code on_heap_code = Code::cast(object_); |
| // To make snapshots reproducible, we make a copy of the code object |
| // and wipe all pointers in the copy, which we then serialize. |
| Code off_heap_code = serializer_->CopyCode(on_heap_code); |
| int mode_mask = RelocInfo::ModeMask(RelocInfo::CODE_TARGET) | |
| RelocInfo::ModeMask(RelocInfo::FULL_EMBEDDED_OBJECT) | |
| RelocInfo::ModeMask(RelocInfo::COMPRESSED_EMBEDDED_OBJECT) | |
| RelocInfo::ModeMask(RelocInfo::EXTERNAL_REFERENCE) | |
| RelocInfo::ModeMask(RelocInfo::INTERNAL_REFERENCE) | |
| RelocInfo::ModeMask(RelocInfo::INTERNAL_REFERENCE_ENCODED) | |
| RelocInfo::ModeMask(RelocInfo::OFF_HEAP_TARGET) | |
| RelocInfo::ModeMask(RelocInfo::RUNTIME_ENTRY); |
| // With enabled pointer compression normal accessors no longer work for |
| // off-heap objects, so we have to get the relocation info data via the |
| // on-heap code object. |
| ByteArray relocation_info = on_heap_code.unchecked_relocation_info(); |
| for (RelocIterator it(off_heap_code, relocation_info, mode_mask); !it.done(); |
| it.next()) { |
| RelocInfo* rinfo = it.rinfo(); |
| rinfo->WipeOut(); |
| } |
| // We need to wipe out the header fields *after* wiping out the |
| // relocations, because some of these fields are needed for the latter. |
| off_heap_code.WipeOutHeader(); |
| |
| Address start = off_heap_code.address() + Code::kDataStart; |
| int bytes_to_output = size - Code::kDataStart; |
| DCHECK(IsAligned(bytes_to_output, kTaggedSize)); |
| |
| sink_->Put(kVariableRawCode, "VariableRawCode"); |
| sink_->PutInt(bytes_to_output, "length"); |
| |
| #ifdef MEMORY_SANITIZER |
| // Check that we do not serialize uninitialized memory. |
| __msan_check_mem_is_initialized(reinterpret_cast<void*>(start), |
| bytes_to_output); |
| #endif // MEMORY_SANITIZER |
| sink_->PutRaw(reinterpret_cast<byte*>(start), bytes_to_output, "Code"); |
| } |
| |
| } // namespace internal |
| } // namespace v8 |
