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// 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.
#ifndef V8_SNAPSHOT_DESERIALIZER_H_
#define V8_SNAPSHOT_DESERIALIZER_H_
#include "src/heap/heap.h"
#include "src/objects.h"
#include "src/snapshot/serializer-common.h"
#include "src/snapshot/snapshot-source-sink.h"
namespace v8 {
namespace internal {
// Used for platforms with embedded constant pools to trigger deserialization
// of objects found in code.
#if defined(V8_TARGET_ARCH_MIPS) || defined(V8_TARGET_ARCH_MIPS64) || \
defined(V8_TARGET_ARCH_PPC) || defined(V8_TARGET_ARCH_S390) || \
V8_EMBEDDED_CONSTANT_POOL
#define V8_CODE_EMBEDS_OBJECT_POINTER 1
#else
#define V8_CODE_EMBEDS_OBJECT_POINTER 0
#endif
class Heap;
// A Deserializer reads a snapshot and reconstructs the Object graph it defines.
class Deserializer : public SerializerDeserializer {
public:
// Create a deserializer from a snapshot byte source.
template <class Data>
explicit Deserializer(Data* data, bool deserializing_user_code = false)
: isolate_(NULL),
source_(data->Payload()),
magic_number_(data->GetMagicNumber()),
num_extra_references_(data->GetExtraReferences()),
next_map_index_(0),
external_reference_table_(NULL),
deserialized_large_objects_(0),
deserializing_user_code_(deserializing_user_code),
next_alignment_(kWordAligned),
can_rehash_(false) {
DecodeReservation(data->Reservations());
}
~Deserializer() override;
// Deserialize the snapshot into an empty heap.
void Deserialize(Isolate* isolate);
// Deserialize a single object and the objects reachable from it.
MaybeHandle<Object> DeserializePartial(
Isolate* isolate, Handle<JSGlobalProxy> global_proxy,
v8::DeserializeEmbedderFieldsCallback embedder_fields_deserializer);
// Deserialize an object graph. Fail gracefully.
MaybeHandle<HeapObject> DeserializeObject(Isolate* isolate);
// Add an object to back an attached reference. The order to add objects must
// mirror the order they are added in the serializer.
void AddAttachedObject(Handle<HeapObject> attached_object) {
attached_objects_.Add(attached_object);
}
void SetRehashability(bool v) { can_rehash_ = v; }
private:
void VisitPointers(Object** start, Object** end) override;
void Synchronize(VisitorSynchronization::SyncTag tag) override;
void VisitRuntimeEntry(RelocInfo* rinfo) override { UNREACHABLE(); }
void Initialize(Isolate* isolate);
bool deserializing_user_code() { return deserializing_user_code_; }
void DecodeReservation(Vector<const SerializedData::Reservation> res);
bool ReserveSpace();
void UnalignedCopy(Object** dest, Object** src) {
memcpy(dest, src, sizeof(*src));
}
void SetAlignment(byte data) {
DCHECK_EQ(kWordAligned, next_alignment_);
int alignment = data - (kAlignmentPrefix - 1);
DCHECK_LE(kWordAligned, alignment);
DCHECK_LE(alignment, kDoubleUnaligned);
next_alignment_ = static_cast<AllocationAlignment>(alignment);
}
void DeserializeDeferredObjects();
void DeserializeEmbedderFields(
v8::DeserializeEmbedderFieldsCallback embedder_fields_deserializer);
void FlushICacheForNewIsolate();
void FlushICacheForNewCodeObjectsAndRecordEmbeddedObjects();
void CommitPostProcessedObjects(Isolate* isolate);
void PrintDisassembledCodeObjects();
// Fills in some heap data in an area from start to end (non-inclusive). The
// space id is used for the write barrier. The object_address is the address
// of the object we are writing into, or NULL if we are not writing into an
// object, i.e. if we are writing a series of tagged values that are not on
// the heap. Return false if the object content has been deferred.
bool ReadData(Object** start, Object** end, int space,
Address object_address);
void ReadObject(int space_number, Object** write_back);
Address Allocate(int space_index, int size);
// Special handling for serialized code like hooking up internalized strings.
HeapObject* PostProcessNewObject(HeapObject* obj, int space);
// This returns the address of an object that has been described in the
// snapshot by chunk index and offset.
HeapObject* GetBackReferencedObject(int space);
// Rehash after deserializing an isolate.
void Rehash();
// Rehash after deserializing a context.
void RehashContext(Context* context);
// Sort descriptors of deserialized maps using new string hashes.
void SortMapDescriptors();
// Cached current isolate.
Isolate* isolate_;
// Objects from the attached object descriptions in the serialized user code.
List<Handle<HeapObject> > attached_objects_;
SnapshotByteSource source_;
uint32_t magic_number_;
uint32_t num_extra_references_;
// The address of the next object that will be allocated in each space.
// Each space has a number of chunks reserved by the GC, with each chunk
// fitting into a page. Deserialized objects are allocated into the
// current chunk of the target space by bumping up high water mark.
Heap::Reservation reservations_[kNumberOfSpaces];
uint32_t current_chunk_[kNumberOfPreallocatedSpaces];
Address high_water_[kNumberOfPreallocatedSpaces];
int next_map_index_;
List<Address> allocated_maps_;
ExternalReferenceTable* external_reference_table_;
List<HeapObject*> deserialized_large_objects_;
List<Code*> new_code_objects_;
List<AccessorInfo*> accessor_infos_;
List<Handle<String> > new_internalized_strings_;
List<Handle<Script> > new_scripts_;
List<TransitionArray*> transition_arrays_;
bool deserializing_user_code_;
AllocationAlignment next_alignment_;
// TODO(6593): generalize rehashing, and remove this flag.
bool can_rehash_;
DISALLOW_COPY_AND_ASSIGN(Deserializer);
};
} // namespace internal
} // namespace v8
#endif // V8_SNAPSHOT_DESERIALIZER_H_
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