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// Copyright 2006-2009 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef V8_SERIALIZE_H_
#define V8_SERIALIZE_H_
#include "hashmap.h"
namespace v8 {
namespace internal {
// A TypeCode is used to distinguish different kinds of external reference.
// It is a single bit to make testing for types easy.
enum TypeCode {
UNCLASSIFIED, // One-of-a-kind references.
BUILTIN,
RUNTIME_FUNCTION,
IC_UTILITY,
DEBUG_ADDRESS,
STATS_COUNTER,
TOP_ADDRESS,
C_BUILTIN,
EXTENSION,
ACCESSOR,
RUNTIME_ENTRY,
STUB_CACHE_TABLE
};
const int kTypeCodeCount = STUB_CACHE_TABLE + 1;
const int kFirstTypeCode = UNCLASSIFIED;
const int kReferenceIdBits = 16;
const int kReferenceIdMask = (1 << kReferenceIdBits) - 1;
const int kReferenceTypeShift = kReferenceIdBits;
const int kDebugRegisterBits = 4;
const int kDebugIdShift = kDebugRegisterBits;
class ExternalReferenceEncoder {
public:
ExternalReferenceEncoder();
uint32_t Encode(Address key) const;
const char* NameOfAddress(Address key) const;
private:
HashMap encodings_;
static uint32_t Hash(Address key) {
return static_cast<uint32_t>(reinterpret_cast<uintptr_t>(key) >> 2);
}
int IndexOf(Address key) const;
static bool Match(void* key1, void* key2) { return key1 == key2; }
void Put(Address key, int index);
};
class ExternalReferenceDecoder {
public:
ExternalReferenceDecoder();
~ExternalReferenceDecoder();
Address Decode(uint32_t key) const {
if (key == 0) return NULL;
return *Lookup(key);
}
private:
Address** encodings_;
Address* Lookup(uint32_t key) const {
int type = key >> kReferenceTypeShift;
ASSERT(kFirstTypeCode <= type && type < kTypeCodeCount);
int id = key & kReferenceIdMask;
return &encodings_[type][id];
}
void Put(uint32_t key, Address value) {
*Lookup(key) = value;
}
};
class SnapshotByteSource {
public:
SnapshotByteSource(const byte* array, int length)
: data_(array), length_(length), position_(0) { }
bool HasMore() { return position_ < length_; }
int Get() {
ASSERT(position_ < length_);
return data_[position_++];
}
inline void CopyRaw(byte* to, int number_of_bytes);
inline int GetInt();
bool AtEOF() {
return position_ == length_;
}
int position() { return position_; }
private:
const byte* data_;
int length_;
int position_;
};
// It is very common to have a reference to objects at certain offsets in the
// heap. These offsets have been determined experimentally. We code
// references to such objects in a single byte that encodes the way the pointer
// is written (only plain pointers allowed), the space number and the offset.
// This only works for objects in the first page of a space. Don't use this for
// things in newspace since it bypasses the write barrier.
static const int k64 = (sizeof(uintptr_t) - 4) / 4;
#define COMMON_REFERENCE_PATTERNS(f) \
f(kNumberOfSpaces, 2, (11 - k64)) \
f((kNumberOfSpaces + 1), 2, 0) \
f((kNumberOfSpaces + 2), 2, (142 - 16 * k64)) \
f((kNumberOfSpaces + 3), 2, (74 - 15 * k64)) \
f((kNumberOfSpaces + 4), 2, 5) \
f((kNumberOfSpaces + 5), 1, 135) \
f((kNumberOfSpaces + 6), 2, (228 - 39 * k64))
#define COMMON_RAW_LENGTHS(f) \
f(1, 1) \
f(2, 2) \
f(3, 3) \
f(4, 4) \
f(5, 5) \
f(6, 6) \
f(7, 7) \
f(8, 8) \
f(9, 12) \
f(10, 16) \
f(11, 20) \
f(12, 24) \
f(13, 28) \
f(14, 32) \
f(15, 36)
// The Serializer/Deserializer class is a common superclass for Serializer and
// Deserializer which is used to store common constants and methods used by
// both.
class SerializerDeserializer: public ObjectVisitor {
public:
static void Iterate(ObjectVisitor* visitor);
static void SetSnapshotCacheSize(int size);
protected:
// Where the pointed-to object can be found:
enum Where {
kNewObject = 0, // Object is next in snapshot.
// 1-8 One per space.
kRootArray = 0x9, // Object is found in root array.
kPartialSnapshotCache = 0xa, // Object is in the cache.
kExternalReference = 0xb, // Pointer to an external reference.
// 0xc-0xf Free.
kBackref = 0x10, // Object is described relative to end.
// 0x11-0x18 One per space.
// 0x19-0x1f Common backref offsets.
kFromStart = 0x20, // Object is described relative to start.
// 0x21-0x28 One per space.
// 0x29-0x2f Free.
// 0x30-0x3f Used by misc tags below.
kPointedToMask = 0x3f
};
// How to code the pointer to the object.
enum HowToCode {
kPlain = 0, // Straight pointer.
// What this means depends on the architecture:
kFromCode = 0x40, // A pointer inlined in code.
kHowToCodeMask = 0x40
};
// Where to point within the object.
enum WhereToPoint {
kStartOfObject = 0,
kFirstInstruction = 0x80,
kWhereToPointMask = 0x80
};
// Misc.
// Raw data to be copied from the snapshot.
static const int kRawData = 0x30;
// Some common raw lengths: 0x31-0x3f
// A tag emitted at strategic points in the snapshot to delineate sections.
// If the deserializer does not find these at the expected moments then it
// is an indication that the snapshot and the VM do not fit together.
// Examine the build process for architecture, version or configuration
// mismatches.
static const int kSynchronize = 0x70;
// Used for the source code of the natives, which is in the executable, but
// is referred to from external strings in the snapshot.
static const int kNativesStringResource = 0x71;
static const int kNewPage = 0x72;
// 0x73-0x7f Free.
// 0xb0-0xbf Free.
// 0xf0-0xff Free.
static const int kLargeData = LAST_SPACE;
static const int kLargeCode = kLargeData + 1;
static const int kLargeFixedArray = kLargeCode + 1;
static const int kNumberOfSpaces = kLargeFixedArray + 1;
static const int kAnyOldSpace = -1;
// A bitmask for getting the space out of an instruction.
static const int kSpaceMask = 15;
static inline bool SpaceIsLarge(int space) { return space >= kLargeData; }
static inline bool SpaceIsPaged(int space) {
return space >= FIRST_PAGED_SPACE && space <= LAST_PAGED_SPACE;
}
static int partial_snapshot_cache_length_;
static const int kPartialSnapshotCacheCapacity = 1400;
static Object* partial_snapshot_cache_[];
};
int SnapshotByteSource::GetInt() {
// A little unwind to catch the really small ints.
int snapshot_byte = Get();
if ((snapshot_byte & 0x80) == 0) {
return snapshot_byte;
}
int accumulator = (snapshot_byte & 0x7f) << 7;
while (true) {
snapshot_byte = Get();
if ((snapshot_byte & 0x80) == 0) {
return accumulator | snapshot_byte;
}
accumulator = (accumulator | (snapshot_byte & 0x7f)) << 7;
}
UNREACHABLE();
return accumulator;
}
void SnapshotByteSource::CopyRaw(byte* to, int number_of_bytes) {
memcpy(to, data_ + position_, number_of_bytes);
position_ += number_of_bytes;
}
// 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.
explicit Deserializer(SnapshotByteSource* source);
virtual ~Deserializer();
// Deserialize the snapshot into an empty heap.
void Deserialize();
// Deserialize a single object and the objects reachable from it.
void DeserializePartial(Object** root);
#ifdef DEBUG
virtual void Synchronize(const char* tag);
#endif
private:
virtual void VisitPointers(Object** start, Object** end);
virtual void VisitExternalReferences(Address* start, Address* end) {
UNREACHABLE();
}
virtual void VisitRuntimeEntry(RelocInfo* rinfo) {
UNREACHABLE();
}
void ReadChunk(Object** start, Object** end, int space, Address address);
HeapObject* GetAddressFromStart(int space);
inline HeapObject* GetAddressFromEnd(int space);
Address Allocate(int space_number, Space* space, int size);
void ReadObject(int space_number, Space* space, Object** write_back);
// Keep track of the pages in the paged spaces.
// (In large object space we are keeping track of individual objects
// rather than pages.) In new space we just need the address of the
// first object and the others will flow from that.
List<Address> pages_[SerializerDeserializer::kNumberOfSpaces];
SnapshotByteSource* source_;
static ExternalReferenceDecoder* external_reference_decoder_;
// This is the address of the next object that will be allocated in each
// space. It is used to calculate the addresses of back-references.
Address high_water_[LAST_SPACE + 1];
// This is the address of the most recent object that was allocated. It
// is used to set the location of the new page when we encounter a
// START_NEW_PAGE_SERIALIZATION tag.
Address last_object_address_;
DISALLOW_COPY_AND_ASSIGN(Deserializer);
};
class SnapshotByteSink {
public:
virtual ~SnapshotByteSink() { }
virtual void Put(int byte, const char* description) = 0;
virtual void PutSection(int byte, const char* description) {
Put(byte, description);
}
void PutInt(uintptr_t integer, const char* description);
virtual int Position() = 0;
};
// Mapping objects to their location after deserialization.
// This is used during building, but not at runtime by V8.
class SerializationAddressMapper {
public:
SerializationAddressMapper()
: serialization_map_(new HashMap(&SerializationMatchFun)),
no_allocation_(new AssertNoAllocation()) { }
~SerializationAddressMapper() {
delete serialization_map_;
delete no_allocation_;
}
bool IsMapped(HeapObject* obj) {
return serialization_map_->Lookup(Key(obj), Hash(obj), false) != NULL;
}
int MappedTo(HeapObject* obj) {
ASSERT(IsMapped(obj));
return static_cast<int>(reinterpret_cast<intptr_t>(
serialization_map_->Lookup(Key(obj), Hash(obj), false)->value));
}
void AddMapping(HeapObject* obj, int to) {
ASSERT(!IsMapped(obj));
HashMap::Entry* entry =
serialization_map_->Lookup(Key(obj), Hash(obj), true);
entry->value = Value(to);
}
private:
static bool SerializationMatchFun(void* key1, void* key2) {
return key1 == key2;
}
static uint32_t Hash(HeapObject* obj) {
return static_cast<int32_t>(reinterpret_cast<intptr_t>(obj->address()));
}
static void* Key(HeapObject* obj) {
return reinterpret_cast<void*>(obj->address());
}
static void* Value(int v) {
return reinterpret_cast<void*>(v);
}
HashMap* serialization_map_;
AssertNoAllocation* no_allocation_;
DISALLOW_COPY_AND_ASSIGN(SerializationAddressMapper);
};
class Serializer : public SerializerDeserializer {
public:
explicit Serializer(SnapshotByteSink* sink);
~Serializer();
void VisitPointers(Object** start, Object** end);
// You can call this after serialization to find out how much space was used
// in each space.
int CurrentAllocationAddress(int space) {
if (SpaceIsLarge(space)) return large_object_total_;
return fullness_[space];
}
static void Enable() {
if (!serialization_enabled_) {
ASSERT(!too_late_to_enable_now_);
}
serialization_enabled_ = true;
}
static void Disable() { serialization_enabled_ = false; }
// Call this when you have made use of the fact that there is no serialization
// going on.
static void TooLateToEnableNow() { too_late_to_enable_now_ = true; }
static bool enabled() { return serialization_enabled_; }
SerializationAddressMapper* address_mapper() { return &address_mapper_; }
#ifdef DEBUG
virtual void Synchronize(const char* tag);
#endif
protected:
static const int kInvalidRootIndex = -1;
virtual int RootIndex(HeapObject* heap_object) = 0;
virtual bool ShouldBeInThePartialSnapshotCache(HeapObject* o) = 0;
class ObjectSerializer : public ObjectVisitor {
public:
ObjectSerializer(Serializer* serializer,
Object* o,
SnapshotByteSink* sink,
HowToCode how_to_code,
WhereToPoint where_to_point)
: serializer_(serializer),
object_(HeapObject::cast(o)),
sink_(sink),
reference_representation_(how_to_code + where_to_point),
bytes_processed_so_far_(0) { }
void Serialize();
void VisitPointers(Object** start, Object** end);
void VisitExternalReferences(Address* start, Address* end);
void VisitCodeTarget(RelocInfo* target);
void VisitRuntimeEntry(RelocInfo* reloc);
// Used for seralizing the external strings that hold the natives source.
void VisitExternalAsciiString(
v8::String::ExternalAsciiStringResource** resource);
// We can't serialize a heap with external two byte strings.
void VisitExternalTwoByteString(
v8::String::ExternalStringResource** resource) {
UNREACHABLE();
}
private:
void OutputRawData(Address up_to);
Serializer* serializer_;
HeapObject* object_;
SnapshotByteSink* sink_;
int reference_representation_;
int bytes_processed_so_far_;
};
virtual void SerializeObject(Object* o,
HowToCode how_to_code,
WhereToPoint where_to_point) = 0;
void SerializeReferenceToPreviousObject(
int space,
int address,
HowToCode how_to_code,
WhereToPoint where_to_point);
void InitializeAllocators();
// This will return the space for an object. If the object is in large
// object space it may return kLargeCode or kLargeFixedArray in order
// to indicate to the deserializer what kind of large object allocation
// to make.
static int SpaceOfObject(HeapObject* object);
// This just returns the space of the object. It will return LO_SPACE
// for all large objects since you can't check the type of the object
// once the map has been used for the serialization address.
static int SpaceOfAlreadySerializedObject(HeapObject* object);
int Allocate(int space, int size, bool* new_page_started);
int EncodeExternalReference(Address addr) {
return external_reference_encoder_->Encode(addr);
}
// Keep track of the fullness of each space in order to generate
// relative addresses for back references. Large objects are
// just numbered sequentially since relative addresses make no
// sense in large object space.
int fullness_[LAST_SPACE + 1];
SnapshotByteSink* sink_;
int current_root_index_;
ExternalReferenceEncoder* external_reference_encoder_;
static bool serialization_enabled_;
// Did we already make use of the fact that serialization was not enabled?
static bool too_late_to_enable_now_;
int large_object_total_;
SerializationAddressMapper address_mapper_;
friend class ObjectSerializer;
friend class Deserializer;
DISALLOW_COPY_AND_ASSIGN(Serializer);
};
class PartialSerializer : public Serializer {
public:
PartialSerializer(Serializer* startup_snapshot_serializer,
SnapshotByteSink* sink)
: Serializer(sink),
startup_serializer_(startup_snapshot_serializer) {
}
// Serialize the objects reachable from a single object pointer.
virtual void Serialize(Object** o);
virtual void SerializeObject(Object* o,
HowToCode how_to_code,
WhereToPoint where_to_point);
protected:
virtual int RootIndex(HeapObject* o);
virtual int PartialSnapshotCacheIndex(HeapObject* o);
virtual bool ShouldBeInThePartialSnapshotCache(HeapObject* o) {
// Scripts should be referred only through shared function infos. We can't
// allow them to be part of the partial snapshot because they contain a
// unique ID, and deserializing several partial snapshots containing script
// would cause dupes.
ASSERT(!o->IsScript());
return o->IsString() || o->IsSharedFunctionInfo() ||
o->IsHeapNumber() || o->IsCode() ||
o->map() == Heap::fixed_cow_array_map();
}
private:
Serializer* startup_serializer_;
DISALLOW_COPY_AND_ASSIGN(PartialSerializer);
};
class StartupSerializer : public Serializer {
public:
explicit StartupSerializer(SnapshotByteSink* sink) : Serializer(sink) {
// Clear the cache of objects used by the partial snapshot. After the
// strong roots have been serialized we can create a partial snapshot
// which will repopulate the cache with objects neede by that partial
// snapshot.
partial_snapshot_cache_length_ = 0;
}
// Serialize the current state of the heap. The order is:
// 1) Strong references.
// 2) Partial snapshot cache.
// 3) Weak references (eg the symbol table).
virtual void SerializeStrongReferences();
virtual void SerializeObject(Object* o,
HowToCode how_to_code,
WhereToPoint where_to_point);
void SerializeWeakReferences();
void Serialize() {
SerializeStrongReferences();
SerializeWeakReferences();
}
private:
virtual int RootIndex(HeapObject* o) { return kInvalidRootIndex; }
virtual bool ShouldBeInThePartialSnapshotCache(HeapObject* o) {
return false;
}
};
} } // namespace v8::internal
#endif // V8_SERIALIZE_H_