// 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/assembler-inl.h"
#include "src/heap/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/snapshot/builtin-serializer-allocator.h"
#include "src/snapshot/natives.h"
#include "src/snapshot/snapshot.h"
namespace v8 {
namespace internal {
template <class AllocatorT>
Serializer<AllocatorT>::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 < LAST_SPACE; ++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 < LAST_SPACE; ++space) {
instance_type_count_[space] = nullptr;
instance_type_size_[space] = nullptr;
}
}
#endif // OBJECT_PRINT
}
template <class AllocatorT>
Serializer<AllocatorT>::~Serializer() {
if (code_address_map_ != nullptr) delete code_address_map_;
#ifdef OBJECT_PRINT
for (int space = 0; space < LAST_SPACE; ++space) {
if (instance_type_count_[space] != nullptr) {
DeleteArray(instance_type_count_[space]);
DeleteArray(instance_type_size_[space]);
}
}
#endif // OBJECT_PRINT
}
#ifdef OBJECT_PRINT
template <class AllocatorT>
void Serializer<AllocatorT>::CountInstanceType(Map* map, int size,
AllocationSpace space) {
int instance_type = map->instance_type();
instance_type_count_[space][instance_type]++;
instance_type_size_[space][instance_type] += size;
}
#endif // OBJECT_PRINT
template <class AllocatorT>
void Serializer<AllocatorT>::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 < LAST_SPACE; ++space) { \
if (instance_type_count_[space][Name]) { \
PrintF("%10d %10" PRIuS " %-10s %s\n", \
instance_type_count_[space][Name], \
instance_type_size_[space][Name], \
AllocationSpaceName(static_cast<AllocationSpace>(space)), #Name); \
} \
}
INSTANCE_TYPE_LIST(PRINT_INSTANCE_TYPE)
#undef PRINT_INSTANCE_TYPE
PrintF("\n");
#endif // OBJECT_PRINT
}
template <class AllocatorT>
void Serializer<AllocatorT>::SerializeDeferredObjects() {
while (!deferred_objects_.empty()) {
HeapObject* obj = deferred_objects_.back();
deferred_objects_.pop_back();
ObjectSerializer obj_serializer(this, obj, &sink_, kPlain, kStartOfObject);
obj_serializer.SerializeDeferred();
}
sink_.Put(kSynchronize, "Finished with deferred objects");
}
template <class AllocatorT>
bool Serializer<AllocatorT>::MustBeDeferred(HeapObject* object) {
return false;
}
template <class AllocatorT>
void Serializer<AllocatorT>::VisitRootPointers(Root root,
const char* description,
Object** start, Object** end) {
// Builtins and bytecode handlers are serialized in a separate pass by the
// BuiltinSerializer.
if (root == Root::kBuiltins || root == Root::kDispatchTable) return;
for (Object** current = start; current < end; current++) {
SerializeRootObject(*current);
}
}
template <class AllocatorT>
void Serializer<AllocatorT>::SerializeRootObject(Object* object) {
if (object->IsSmi()) {
PutSmi(Smi::cast(object));
} else {
SerializeObject(HeapObject::cast(object), kPlain, kStartOfObject, 0);
}
}
#ifdef DEBUG
template <class AllocatorT>
void Serializer<AllocatorT>::PrintStack() {
for (const auto o : stack_) {
o->Print();
PrintF("\n");
}
}
#endif // DEBUG
template <class AllocatorT>
bool Serializer<AllocatorT>::SerializeHotObject(HeapObject* obj,
HowToCode how_to_code,
WhereToPoint where_to_point,
int skip) {
if (how_to_code != kPlain || where_to_point != kStartOfObject) return false;
// 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");
}
if (skip != 0) {
sink_.Put(kHotObjectWithSkip + index, "HotObjectWithSkip");
sink_.PutInt(skip, "HotObjectSkipDistance");
} else {
sink_.Put(kHotObject + index, "HotObject");
}
return true;
}
template <class AllocatorT>
bool Serializer<AllocatorT>::SerializeBackReference(HeapObject* obj,
HowToCode how_to_code,
WhereToPoint where_to_point,
int skip) {
SerializerReference reference = reference_map_.LookupReference(obj);
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()) {
FlushSkip(skip);
if (FLAG_trace_serializer) {
PrintF(" Encoding attached reference %d\n",
reference.attached_reference_index());
}
PutAttachedReference(reference, how_to_code, where_to_point);
} else {
DCHECK(reference.is_back_reference());
if (FLAG_trace_serializer) {
PrintF(" Encoding back reference to: ");
obj->ShortPrint();
PrintF("\n");
}
PutAlignmentPrefix(obj);
AllocationSpace space = reference.space();
if (skip == 0) {
sink_.Put(kBackref + how_to_code + where_to_point + space, "BackRef");
} else {
sink_.Put(kBackrefWithSkip + how_to_code + where_to_point + space,
"BackRefWithSkip");
sink_.PutInt(skip, "BackRefSkipDistance");
}
PutBackReference(obj, reference);
}
return true;
}
template <class AllocatorT>
bool Serializer<AllocatorT>::SerializeBuiltinReference(
HeapObject* obj, HowToCode how_to_code, WhereToPoint where_to_point,
int skip) {
if (!obj->IsCode()) return false;
Code* code = Code::cast(obj);
int builtin_index = code->builtin_index();
if (builtin_index < 0) return false;
DCHECK((how_to_code == kPlain && where_to_point == kStartOfObject) ||
(how_to_code == kFromCode));
DCHECK_LT(builtin_index, Builtins::builtin_count);
DCHECK_LE(0, builtin_index);
if (FLAG_trace_serializer) {
PrintF(" Encoding builtin reference: %s\n",
isolate()->builtins()->name(builtin_index));
}
FlushSkip(skip);
sink_.Put(kBuiltin + how_to_code + where_to_point, "Builtin");
sink_.PutInt(builtin_index, "builtin_index");
return true;
}
template <class AllocatorT>
bool Serializer<AllocatorT>::ObjectIsBytecodeHandler(HeapObject* obj) const {
if (!obj->IsCode()) return false;
Code* code = Code::cast(obj);
if (isolate()->heap()->IsDeserializeLazyHandler(code)) return false;
return (code->kind() == Code::BYTECODE_HANDLER);
}
template <class AllocatorT>
void Serializer<AllocatorT>::PutRoot(
int root_index, HeapObject* object,
SerializerDeserializer::HowToCode how_to_code,
SerializerDeserializer::WhereToPoint where_to_point, int skip) {
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(Heap::kArgumentsMarkerRootIndex ==
kNumberOfRootArrayConstants - 1);
if (how_to_code == kPlain && where_to_point == kStartOfObject &&
root_index < kNumberOfRootArrayConstants && !Heap::InNewSpace(object)) {
if (skip == 0) {
sink_.Put(kRootArrayConstants + root_index, "RootConstant");
} else {
sink_.Put(kRootArrayConstantsWithSkip + root_index, "RootConstant");
sink_.PutInt(skip, "SkipInPutRoot");
}
} else {
FlushSkip(skip);
sink_.Put(kRootArray + how_to_code + where_to_point, "RootSerialization");
sink_.PutInt(root_index, "root_index");
hot_objects_.Add(object);
}
}
template <class AllocatorT>
void Serializer<AllocatorT>::PutSmi(Smi* smi) {
sink_.Put(kOnePointerRawData, "Smi");
byte* bytes = reinterpret_cast<byte*>(&smi);
for (int i = 0; i < kPointerSize; i++) sink_.Put(bytes[i], "Byte");
}
template <class AllocatorT>
void Serializer<AllocatorT>::PutBackReference(HeapObject* object,
SerializerReference reference) {
DCHECK(allocator()->BackReferenceIsAlreadyAllocated(reference));
switch (reference.space()) {
case MAP_SPACE:
sink_.PutInt(reference.map_index(), "BackRefMapIndex");
break;
case LO_SPACE:
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);
}
template <class AllocatorT>
void Serializer<AllocatorT>::PutAttachedReference(SerializerReference reference,
HowToCode how_to_code,
WhereToPoint where_to_point) {
DCHECK(reference.is_attached_reference());
DCHECK((how_to_code == kPlain && where_to_point == kStartOfObject) ||
(how_to_code == kFromCode && where_to_point == kStartOfObject) ||
(how_to_code == kFromCode && where_to_point == kInnerPointer));
sink_.Put(kAttachedReference + how_to_code + where_to_point, "AttachedRef");
sink_.PutInt(reference.attached_reference_index(), "AttachedRefIndex");
}
template <class AllocatorT>
int Serializer<AllocatorT>::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;
}
template <class AllocatorT>
void Serializer<AllocatorT>::PutNextChunk(int space) {
sink_.Put(kNextChunk, "NextChunk");
sink_.Put(space, "NextChunkSpace");
}
template <class AllocatorT>
void Serializer<AllocatorT>::Pad() {
// 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(), kPointerAlignment)) {
sink_.Put(kNop, "Padding");
}
}
template <class AllocatorT>
void Serializer<AllocatorT>::InitializeCodeAddressMap() {
isolate_->InitializeLoggingAndCounters();
code_address_map_ = new CodeAddressMap(isolate_);
}
template <class AllocatorT>
Code* Serializer<AllocatorT>::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));
return Code::cast(HeapObject::FromAddress(
reinterpret_cast<Address>(&code_buffer_.front())));
}
template <class AllocatorT>
void Serializer<AllocatorT>::ObjectSerializer::SerializePrologue(
AllocationSpace 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));
}
SerializerReference back_reference;
if (space == LO_SPACE) {
sink_->Put(kNewObject + reference_representation_ + space,
"NewLargeObject");
sink_->PutInt(size >> kObjectAlignmentBits, "ObjectSizeInWords");
if (object_->IsCode()) {
sink_->Put(EXECUTABLE, "executable large object");
} else {
sink_->Put(NOT_EXECUTABLE, "not executable large object");
}
back_reference = serializer_->allocator()->AllocateLargeObject(size);
} else if (space == MAP_SPACE) {
DCHECK_EQ(Map::kSize, size);
back_reference = serializer_->allocator()->AllocateMap();
sink_->Put(kNewObject + reference_representation_ + space, "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 + reference_representation_ + space, "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(object_, back_reference);
// Serialize the map (first word of the object).
serializer_->SerializeObject(map, kPlain, kStartOfObject, 0);
}
template <class AllocatorT>
int32_t Serializer<AllocatorT>::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());
}
template <class AllocatorT>
void Serializer<AllocatorT>::ObjectSerializer::SerializeJSTypedArray() {
JSTypedArray* typed_array = JSTypedArray::cast(object_);
FixedTypedArrayBase* elements =
FixedTypedArrayBase::cast(typed_array->elements());
if (!typed_array->WasNeutered()) {
if (!typed_array->is_on_heap()) {
// Explicitly serialize the backing store now.
JSArrayBuffer* buffer = JSArrayBuffer::cast(typed_array->buffer());
CHECK(buffer->byte_length()->IsSmi());
CHECK(typed_array->byte_offset()->IsSmi());
int32_t byte_length = NumberToInt32(buffer->byte_length());
int32_t byte_offset = NumberToInt32(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>(elements->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.
elements->set_external_pointer(Smi::FromInt(ref));
}
} else {
// When a JSArrayBuffer is neutered, the FixedTypedArray that points to the
// same backing store does not know anything about it. This fixup step finds
// neutered TypedArrays and clears the values in the FixedTypedArray so that
// we don't try to serialize the now invalid backing store.
elements->set_external_pointer(Smi::kZero);
elements->set_length(0);
}
SerializeObject();
}
template <class AllocatorT>
void Serializer<AllocatorT>::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.
// Attempt to make sure that NumberToInt32 produces something sensible.
CHECK(buffer->byte_length()->IsSmi());
int32_t byte_length = NumberToInt32(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(Smi::FromInt(ref));
}
SerializeObject();
buffer->set_backing_store(backing_store);
}
template <class AllocatorT>
void Serializer<AllocatorT>::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_short());
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);
}
}
template <class AllocatorT>
void Serializer<
AllocatorT>::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());
}
AllocationSpace space =
(allocation_size > kMaxRegularHeapObjectSize) ? LO_SPACE : OLD_SPACE;
SerializePrologue(space, allocation_size, map);
// Output the rest of the imaginary string.
int bytes_to_output = allocation_size - HeapObject::kHeaderSize;
// 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)
: object_(nullptr) {
if (object->IsAllocationSite()) {
object_ = object;
next_ = AllocationSite::cast(object)->weak_next();
AllocationSite::cast(object)->set_weak_next(
ReadOnlyRoots(heap).undefined_value());
}
}
~UnlinkWeakNextScope() {
if (object_ != nullptr) {
AllocationSite::cast(object_)->set_weak_next(next_,
UPDATE_WEAK_WRITE_BARRIER);
}
}
private:
HeapObject* object_;
Object* next_;
DisallowHeapAllocation no_gc_;
};
template <class AllocatorT>
void Serializer<AllocatorT>::ObjectSerializer::Serialize() {
if (FLAG_trace_serializer) {
PrintF(" Encoding heap object: ");
object_->ShortPrint();
PrintF("\n");
}
if (object_->IsExternalString()) {
SerializeExternalString();
return;
} else if (!serializer_->isolate()->heap()->InReadOnlySpace(object_)) {
// Only clear padding for strings outside RO_SPACE. RO_SPACE 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();
}
template <class AllocatorT>
void Serializer<AllocatorT>::ObjectSerializer::SerializeObject() {
int size = object_->Size();
Map* map = object_->map();
AllocationSpace space =
MemoryChunk::FromAddress(object_->address())->owner()->identity();
DCHECK(space != NEW_LO_SPACE);
SerializePrologue(space, size, map);
// Serialize the rest of the object.
CHECK_EQ(0, bytes_processed_so_far_);
bytes_processed_so_far_ = kPointerSize;
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);
}
template <class AllocatorT>
void Serializer<AllocatorT>::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(object_);
DCHECK(back_reference.is_back_reference());
// Serialize the rest of the object.
CHECK_EQ(0, bytes_processed_so_far_);
bytes_processed_so_far_ = kPointerSize;
serializer_->PutAlignmentPrefix(object_);
sink_->Put(kNewObject + back_reference.space(), "deferred object");
serializer_->PutBackReference(object_, back_reference);
sink_->PutInt(size >> kPointerSizeLog2, "deferred object size");
SerializeContent(map, size);
}
template <class AllocatorT>
void Serializer<AllocatorT>::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);
// Finally skip to the end.
serializer_->FlushSkip(SkipTo(object_->address() + size));
} else {
// For other objects, iterate references first.
object_->IterateBody(map, size, this);
// Then output data payload, if any.
OutputRawData(object_->address() + size);
}
}
template <class AllocatorT>
void Serializer<AllocatorT>::ObjectSerializer::VisitPointers(HeapObject* host,
Object** start,
Object** end) {
VisitPointers(host, reinterpret_cast<MaybeObject**>(start),
reinterpret_cast<MaybeObject**>(end));
}
template <class AllocatorT>
void Serializer<AllocatorT>::ObjectSerializer::VisitPointers(
HeapObject* host, MaybeObject** start, MaybeObject** end) {
MaybeObject** current = start;
while (current < end) {
while (current < end &&
((*current)->IsSmi() || (*current)->IsClearedWeakHeapObject())) {
current++;
}
if (current < end) {
OutputRawData(reinterpret_cast<Address>(current));
}
HeapObject* current_contents;
HeapObjectReferenceType reference_type;
while (current < end && (*current)->ToStrongOrWeakHeapObject(
¤t_contents, &reference_type)) {
int root_index = serializer_->root_index_map()->Lookup(current_contents);
// Repeats are not subject to the write barrier so we can only use
// immortal immovable root members. They are never in new space.
if (current != start && root_index != RootIndexMap::kInvalidRootIndex &&
Heap::RootIsImmortalImmovable(root_index) &&
*current == current[-1]) {
DCHECK_EQ(reference_type, HeapObjectReferenceType::STRONG);
DCHECK(!Heap::InNewSpace(current_contents));
int repeat_count = 1;
while (¤t[repeat_count] < end - 1 &&
current[repeat_count] == *current) {
repeat_count++;
}
current += repeat_count;
bytes_processed_so_far_ += repeat_count * kPointerSize;
if (repeat_count > kNumberOfFixedRepeat) {
sink_->Put(kVariableRepeat, "VariableRepeat");
sink_->PutInt(repeat_count, "repeat count");
} else {
sink_->Put(kFixedRepeatStart + repeat_count, "FixedRepeat");
}
} else {
if (reference_type == HeapObjectReferenceType::WEAK) {
sink_->Put(kWeakPrefix, "WeakReference");
}
serializer_->SerializeObject(current_contents, kPlain, kStartOfObject,
0);
bytes_processed_so_far_ += kPointerSize;
current++;
}
}
}
}
template <class AllocatorT>
void Serializer<AllocatorT>::ObjectSerializer::VisitEmbeddedPointer(
Code* host, RelocInfo* rinfo) {
int skip = SkipTo(rinfo->target_address_address());
HowToCode how_to_code = rinfo->IsCodedSpecially() ? kFromCode : kPlain;
Object* object = rinfo->target_object();
serializer_->SerializeObject(HeapObject::cast(object), how_to_code,
kStartOfObject, skip);
bytes_processed_so_far_ += rinfo->target_address_size();
}
template <class AllocatorT>
void Serializer<AllocatorT>::ObjectSerializer::VisitExternalReference(
Foreign* host, Address* p) {
int skip = SkipTo(reinterpret_cast<Address>(p));
Address target = *p;
auto encoded_reference = serializer_->EncodeExternalReference(target);
if (encoded_reference.is_from_api()) {
sink_->Put(kApiReference, "ApiRef");
} else {
sink_->Put(kExternalReference + kPlain + kStartOfObject, "ExternalRef");
}
sink_->PutInt(skip, "SkipB4ExternalRef");
sink_->PutInt(encoded_reference.index(), "reference index");
bytes_processed_so_far_ += kPointerSize;
}
template <class AllocatorT>
void Serializer<AllocatorT>::ObjectSerializer::VisitExternalReference(
Code* host, RelocInfo* rinfo) {
int skip = SkipTo(rinfo->target_address_address());
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 {
HowToCode how_to_code = rinfo->IsCodedSpecially() ? kFromCode : kPlain;
sink_->Put(kExternalReference + how_to_code + kStartOfObject,
"ExternalRef");
}
sink_->PutInt(skip, "SkipB4ExternalRef");
DCHECK_NE(target, kNullAddress); // Code does not reference null.
sink_->PutInt(encoded_reference.index(), "reference index");
bytes_processed_so_far_ += rinfo->target_address_size();
}
template <class AllocatorT>
void Serializer<AllocatorT>::ObjectSerializer::VisitInternalReference(
Code* host, RelocInfo* rinfo) {
// We do not use skip from last patched pc to find the pc to patch, since
// target_address_address may not return addresses in ascending order when
// used for internal references. External references may be stored at the
// end of the code in the constant pool, whereas internal references are
// inline. That would cause the skip to be negative. Instead, we store the
// offset from code entry.
Address entry = Code::cast(object_)->entry();
DCHECK_GE(rinfo->target_internal_reference_address(), entry);
uintptr_t pc_offset = rinfo->target_internal_reference_address() - entry;
DCHECK_LE(pc_offset, Code::cast(object_)->raw_instruction_size());
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(rinfo->rmode() == RelocInfo::INTERNAL_REFERENCE
? kInternalReference
: kInternalReferenceEncoded,
"InternalRef");
sink_->PutInt(pc_offset, "internal ref address");
sink_->PutInt(target_offset, "internal ref value");
}
template <class AllocatorT>
void Serializer<AllocatorT>::ObjectSerializer::VisitRuntimeEntry(
Code* host, RelocInfo* rinfo) {
int skip = SkipTo(rinfo->target_address_address());
HowToCode how_to_code = rinfo->IsCodedSpecially() ? kFromCode : kPlain;
Address target = rinfo->target_address();
auto encoded_reference = serializer_->EncodeExternalReference(target);
DCHECK(!encoded_reference.is_from_api());
sink_->Put(kExternalReference + how_to_code + kStartOfObject, "ExternalRef");
sink_->PutInt(skip, "SkipB4ExternalRef");
sink_->PutInt(encoded_reference.index(), "reference index");
bytes_processed_so_far_ += rinfo->target_address_size();
}
template <class AllocatorT>
void Serializer<AllocatorT>::ObjectSerializer::VisitOffHeapTarget(
Code* host, RelocInfo* rinfo) {
DCHECK(FLAG_embedded_builtins);
{
STATIC_ASSERT(EmbeddedData::kTableSize == Builtins::builtin_count);
CHECK(Builtins::IsIsolateIndependentBuiltin(host));
Address addr = rinfo->target_off_heap_target();
CHECK_NE(kNullAddress, addr);
CHECK_NOT_NULL(
InstructionStream::TryLookupCode(serializer_->isolate(), addr));
}
int skip = SkipTo(rinfo->target_address_address());
sink_->Put(kOffHeapTarget, "OffHeapTarget");
sink_->PutInt(skip, "SkipB4OffHeapTarget");
sink_->PutInt(host->builtin_index(), "builtin index");
bytes_processed_so_far_ += rinfo->target_address_size();
}
namespace {
class CompareRelocInfo {
public:
bool operator()(RelocInfo x, RelocInfo y) {
// Everything that does not use target_address_address will compare equal.
Address x_num = 0;
Address y_num = 0;
if (HasTargetAddressAddress(x.rmode())) {
x_num = x.target_address_address();
}
if (HasTargetAddressAddress(y.rmode())) {
y_num = y.target_address_address();
}
return x_num > y_num;
}
private:
static bool HasTargetAddressAddress(RelocInfo::Mode mode) {
return RelocInfo::IsEmbeddedObject(mode) || RelocInfo::IsCodeTarget(mode) ||
RelocInfo::IsExternalReference(mode) ||
RelocInfo::IsRuntimeEntry(mode);
}
};
} // namespace
template <class AllocatorT>
void Serializer<AllocatorT>::ObjectSerializer::VisitRelocInfo(
RelocIterator* it) {
std::priority_queue<RelocInfo, std::vector<RelocInfo>, CompareRelocInfo>
reloc_queue;
for (; !it->done(); it->next()) {
reloc_queue.push(*it->rinfo());
}
while (!reloc_queue.empty()) {
RelocInfo rinfo = reloc_queue.top();
reloc_queue.pop();
rinfo.Visit(this);
}
}
template <class AllocatorT>
void Serializer<AllocatorT>::ObjectSerializer::VisitCodeTarget(
Code* host, RelocInfo* rinfo) {
int skip = SkipTo(rinfo->target_address_address());
Code* object = Code::GetCodeFromTargetAddress(rinfo->target_address());
serializer_->SerializeObject(object, kFromCode, kInnerPointer, skip);
bytes_processed_so_far_ += rinfo->target_address_size();
}
template <class AllocatorT>
void Serializer<AllocatorT>::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, kPointerAlignment) &&
bytes_to_output <= kNumberOfFixedRawData * kPointerSize) {
int size_in_words = bytes_to_output >> kPointerSizeLog2;
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 code age byte can be changed concurrently by GC.
const int bytes_to_age_byte = BytecodeArray::kBytecodeAgeOffset - base;
if (0 <= bytes_to_age_byte && bytes_to_age_byte < bytes_to_output) {
sink_->PutRaw(reinterpret_cast<byte*>(object_start + base),
bytes_to_age_byte, "Bytes");
byte bytecode_age = BytecodeArray::kNoAgeBytecodeAge;
sink_->PutRaw(&bytecode_age, 1, "Bytes");
const int bytes_written = bytes_to_age_byte + 1;
sink_->PutRaw(
reinterpret_cast<byte*>(object_start + base + bytes_written),
bytes_to_output - bytes_written, "Bytes");
} else {
sink_->PutRaw(reinterpret_cast<byte*>(object_start + base),
bytes_to_output, "Bytes");
}
} else {
sink_->PutRaw(reinterpret_cast<byte*>(object_start + base),
bytes_to_output, "Bytes");
}
}
}
template <class AllocatorT>
int Serializer<AllocatorT>::ObjectSerializer::SkipTo(Address to) {
Address object_start = object_->address();
int up_to_offset = static_cast<int>(to - object_start);
int to_skip = up_to_offset - bytes_processed_so_far_;
bytes_processed_so_far_ += to_skip;
// This assert will fail if the reloc info gives us the target_address_address
// locations in a non-ascending order. We make sure this doesn't happen by
// sorting the relocation info.
DCHECK_GE(to_skip, 0);
return to_skip;
}
template <class AllocatorT>
void Serializer<AllocatorT>::ObjectSerializer::OutputCode(int size) {
DCHECK_EQ(kPointerSize, bytes_processed_so_far_);
Code* 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 = serializer_->CopyCode(code);
int mode_mask = RelocInfo::ModeMask(RelocInfo::CODE_TARGET) |
RelocInfo::ModeMask(RelocInfo::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);
for (RelocIterator it(code, 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.
code->WipeOutHeader();
Address start = code->address() + Code::kDataStart;
int bytes_to_output = size - Code::kDataStart;
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");
}
// Explicit instantiation.
template class Serializer<BuiltinSerializerAllocator>;
template class Serializer<DefaultSerializerAllocator>;
} // namespace internal
} // namespace v8