objects-inl.h.svn-base

Google浏览器V8内核代码

Failure* Failure::InternalError() {
  return Construct(INTERNAL_ERROR);
}


Failure* Failure::Exception() {
  return Construct(EXCEPTION);
}

Failure* Failure::OutOfMemoryException() {
  return Construct(OUT_OF_MEMORY_EXCEPTION);
}


int Failure::value() const {
  return reinterpret_cast<int>(this) >> kFailureTagSize;
}


Failure* Failure::Construct(Type type, int value) {
  int info = (value << kFailureTypeTagSize) | type;
  ASSERT(Smi::IsValid(info));  // Same validation check as in Smi
  return reinterpret_cast<Failure*>((info << kFailureTagSize) | kFailureTag);
}


bool Smi::IsValid(int value) {
#ifdef DEBUG
  bool in_range = (value >= kMinValue) && (value <= kMaxValue);
#endif
  // To be representable as an tagged small integer, the two
  // most-significant bits of 'value' must be either 00 or 11 due to
  // sign-extension. To check this we add 01 to the two
  // most-significant bits, and check if the most-significant bit is 0
  //
  // CAUTION: The original code below:
  // bool result = ((value + 0x40000000) & 0x80000000) == 0;
  // may lead to incorrect results according to the C language spec, and
  // in fact doesn't work correctly with gcc4.1.1 in some cases: The
  // compiler may produce undefined results in case of signed integer
  // overflow. The computation must be done w/ unsigned ints.
  bool result =
      ((static_cast<unsigned int>(value) + 0x40000000U) & 0x80000000U) == 0;
  ASSERT(result == in_range);
  return result;
}


MapWord MapWord::FromMap(Map* map) {
  return MapWord(reinterpret_cast<uintptr_t>(map));
}


Map* MapWord::ToMap() {
  return reinterpret_cast<Map*>(value_);
}


bool MapWord::IsForwardingAddress() {
  // This function only works for map words that are heap object pointers.
  // Since it is a heap object, it has a map.  We use that map's instance
  // type to detect if this map word is not actually a map (ie, it is a
  // forwarding address during a scavenge collection).
  return reinterpret_cast<HeapObject*>(value_)->map()->instance_type() !=
      MAP_TYPE;
}


MapWord MapWord::FromForwardingAddress(HeapObject* object) {
  return MapWord(reinterpret_cast<uintptr_t>(object));
}


HeapObject* MapWord::ToForwardingAddress() {
  ASSERT(IsForwardingAddress());
  return reinterpret_cast<HeapObject*>(value_);
}


bool MapWord::IsMarked() {
  return (value_ & kMarkingMask) == 0;
}


void MapWord::SetMark() {
  value_ &= ~kMarkingMask;
}


void MapWord::ClearMark() {
  value_ |= kMarkingMask;
}


bool MapWord::IsOverflowed() {
  return (value_ & kOverflowMask) != 0;
}


void MapWord::SetOverflow() {
  value_ |= kOverflowMask;
}


void MapWord::ClearOverflow() {
  value_ &= ~kOverflowMask;
}


MapWord MapWord::EncodeAddress(Address map_address, int offset) {
  // Offset is the distance in live bytes from the first live object in the
  // same page. The offset between two objects in the same page should not
  // exceed the object area size of a page.
  ASSERT(0 <= offset && offset < Page::kObjectAreaSize);

  int compact_offset = offset >> kObjectAlignmentBits;
  ASSERT(compact_offset < (1 << kForwardingOffsetBits));

  Page* map_page = Page::FromAddress(map_address);
  ASSERT_MAP_PAGE_INDEX(map_page->mc_page_index);

  int map_page_offset =
      map_page->Offset(map_address) >> kObjectAlignmentBits;

  uintptr_t encoding =
      (compact_offset << kForwardingOffsetShift) |
      (map_page_offset << kMapPageOffsetShift) |
      (map_page->mc_page_index << kMapPageIndexShift);
  return MapWord(encoding);
}


Address MapWord::DecodeMapAddress(MapSpace* map_space) {
  int map_page_index = (value_ & kMapPageIndexMask) >> kMapPageIndexShift;
  ASSERT_MAP_PAGE_INDEX(map_page_index);

  int map_page_offset =
      ((value_ & kMapPageOffsetMask) >> kMapPageOffsetShift)
      << kObjectAlignmentBits;

  return (map_space->PageAddress(map_page_index) + map_page_offset);
}


int MapWord::DecodeOffset() {
  // The offset field is represented in the kForwardingOffsetBits
  // most-significant bits.
  int offset = (value_ >> kForwardingOffsetShift) << kObjectAlignmentBits;
  ASSERT(0 <= offset && offset < Page::kObjectAreaSize);
  return offset;
}


MapWord MapWord::FromEncodedAddress(Address address) {
  return MapWord(reinterpret_cast<uintptr_t>(address));
}


Address MapWord::ToEncodedAddress() {
  return reinterpret_cast<Address>(value_);
}


#ifdef DEBUG
void HeapObject::VerifyObjectField(int offset) {
  VerifyPointer(READ_FIELD(this, offset));
}
#endif


Map* HeapObject::map() {
  return map_word().ToMap();
}


void HeapObject::set_map(Map* value) {
  set_map_word(MapWord::FromMap(value));
}


MapWord HeapObject::map_word() {
  return MapWord(reinterpret_cast<uintptr_t>(READ_FIELD(this, kMapOffset)));
}


void HeapObject::set_map_word(MapWord map_word) {
  // WRITE_FIELD does not update the remembered set, but there is no need
  // here.
  WRITE_FIELD(this, kMapOffset, reinterpret_cast<Object*>(map_word.value_));
}


HeapObject* HeapObject::FromAddress(Address address) {
  ASSERT_TAG_ALIGNED(address);
  return reinterpret_cast<HeapObject*>(address + kHeapObjectTag);
}


Address HeapObject::address() {
  return reinterpret_cast<Address>(this) - kHeapObjectTag;
}


int HeapObject::Size() {
  return SizeFromMap(map());
}


void HeapObject::IteratePointers(ObjectVisitor* v, int start, int end) {
  v->VisitPointers(reinterpret_cast<Object**>(FIELD_ADDR(this, start)),
                   reinterpret_cast<Object**>(FIELD_ADDR(this, end)));
}


void HeapObject::IteratePointer(ObjectVisitor* v, int offset) {
  v->VisitPointer(reinterpret_cast<Object**>(FIELD_ADDR(this, offset)));
}


void HeapObject::CopyBody(JSObject* from) {
  ASSERT(map() == from->map());
  ASSERT(Size() == from->Size());
  int object_size = Size();
  for (int offset = kHeaderSize;
       offset < object_size;
       offset += kPointerSize) {
    Object* value = READ_FIELD(from, offset);
    // Note: WRITE_FIELD does not update the write barrier.
    WRITE_FIELD(this, offset, value);
    WRITE_BARRIER(this, offset);
  }
}


bool HeapObject::IsMarked() {
  return map_word().IsMarked();
}


void HeapObject::SetMark() {
  ASSERT(!IsMarked());
  MapWord first_word = map_word();
  first_word.SetMark();
  set_map_word(first_word);
}


void HeapObject::ClearMark() {
  ASSERT(IsMarked());
  MapWord first_word = map_word();
  first_word.ClearMark();
  set_map_word(first_word);
}


bool HeapObject::IsOverflowed() {
  return map_word().IsOverflowed();
}


void HeapObject::SetOverflow() {
  MapWord first_word = map_word();
  first_word.SetOverflow();
  set_map_word(first_word);
}


void HeapObject::ClearOverflow() {
  ASSERT(IsOverflowed());
  MapWord first_word = map_word();
  first_word.ClearOverflow();
  set_map_word(first_word);
}


double HeapNumber::value() {
  return READ_DOUBLE_FIELD(this, kValueOffset);
}


void HeapNumber::set_value(double value) {
  WRITE_DOUBLE_FIELD(this, kValueOffset, value);
}


ACCESSORS(JSObject, properties, FixedArray, kPropertiesOffset)
ACCESSORS(JSObject, elements, HeapObject, kElementsOffset)


void JSObject::initialize_properties() {
  ASSERT(!Heap::InNewSpace(Heap::empty_fixed_array()));
  WRITE_FIELD(this, kPropertiesOffset, Heap::empty_fixed_array());
}


void JSObject::initialize_elements() {
  ASSERT(!Heap::InNewSpace(Heap::empty_fixed_array()));
  WRITE_FIELD(this, kElementsOffset, Heap::empty_fixed_array());
}


ACCESSORS(Oddball, to_string, String, kToStringOffset)
ACCESSORS(Oddball, to_number, Object, kToNumberOffset)


int JSObject::GetHeaderSize() {
  switch (map()->instance_type()) {
    case JS_GLOBAL_OBJECT_TYPE:
      return JSGlobalObject::kSize;
    case JS_BUILTINS_OBJECT_TYPE:
      return JSBuiltinsObject::kSize;
    case JS_FUNCTION_TYPE:
      return JSFunction::kSize;
    case JS_VALUE_TYPE:
      return JSValue::kSize;
    case JS_ARRAY_TYPE:
      return JSValue::kSize;
    case JS_REGEXP_TYPE:
      return JSValue::kSize;
    case JS_OBJECT_TYPE:
      return JSObject::kHeaderSize;
    default:
      UNREACHABLE();
      return 0;
  }
}


int JSObject::GetInternalFieldCount() {
  ASSERT(1 << kPointerSizeLog2 == kPointerSize);
  return (Size() - GetHeaderSize()) >> kPointerSizeLog2;
}


Object* JSObject::GetInternalField(int index) {
  ASSERT(index < GetInternalFieldCount() && index >= 0);
  return READ_FIELD(this, GetHeaderSize() + (kPointerSize * index));
}


void JSObject::SetInternalField(int index, Object* value) {
  ASSERT(index < GetInternalFieldCount() && index >= 0);
  int offset = GetHeaderSize() + (kPointerSize * index);
  WRITE_FIELD(this, offset, value);
  WRITE_BARRIER(this, offset);
}


void JSObject::InitializeBody(int object_size) {
  for (int offset = kHeaderSize; offset < object_size; offset += kPointerSize) {
    WRITE_FIELD(this, offset, Heap::undefined_value());
  }
}


void Struct::InitializeBody(int object_size) {
  for (int offset = kHeaderSize; offset < object_size; offset += kPointerSize) {
    WRITE_FIELD(this, offset, Heap::undefined_value());
  }
}


bool JSObject::HasFastProperties() {
  return !properties()->IsDictionary();
}


bool Array::IndexFromObject(Object* object, uint32_t* index) {
  if (object->IsSmi()) {
    int value = Smi::cast(object)->value();
    if (value < 0) return false;
    *index = value;
    return true;
  }
  if (object->IsHeapNumber()) {
    double value = HeapNumber::cast(object)->value();
    uint32_t uint_value = static_cast<uint32_t>(value);
    if (value == static_cast<double>(uint_value)) {
      *index = uint_value;
      return true;
    }
  }
  return false;
}


bool Object::IsStringObjectWithCharacterAt(uint32_t index) {
  if (!this->IsJSValue()) return false;

  JSValue* js_value = JSValue::cast(this);
  if (!js_value->value()->IsString()) return false;

  String* str = String::cast(js_value->value());
  if (index >= (uint32_t)str->length()) return false;

  return true;
}


Object* FixedArray::get(int index) {
  ASSERT(index >= 0 && index < this->length());
  return READ_FIELD(this, kHeaderSize + index * kPointerSize);
}


void FixedArray::set(int index, Object* value) {
  ASSERT(index >= 0 && index < this->length());
  int offset = kHeaderSize + index * kPointerSize;
  WRITE_FIELD(this, offset, value);
  WRITE_BARRIER(this, offset);
}


FixedArray::WriteBarrierMode FixedArray::GetWriteBarrierMode() {
  if (Heap::InNewSpace(this)) return SKIP_WRITE_BARRIER;
  return UPDATE_WRITE_BARRIER;
}


void FixedArray::set(int index,
                     Object* value,
                     FixedArray::WriteBarrierMode mode) {
  ASSERT(index >= 0 && index < this->length());
  int offset = kHeaderSize + index * kPointerSize;
  WRITE_FIELD(this, offset, value);
  if (mode == UPDATE_WRITE_BARRIER) {
    WRITE_BARRIER(this, offset);
  } else {
    ASSERT(mode == SKIP_WRITE_BARRIER);
    ASSERT(Heap::InNewSpace(this) || !Heap::InNewSpace(value));
  }
}


void FixedArray::fast_set(FixedArray* array, int index, Object* value) {
  ASSERT(index >= 0 && index < array->length());
  WRITE_FIELD(array, kHeaderSize + index * kPointerSize, value);
}


void FixedArray::set_undefined(int index) {
  ASSERT(index >= 0 && index < this->length());
  ASSERT(!Heap::InNewSpace(Heap::undefined_value()));
  WRITE_FIELD(this, kHeaderSize + index * kPointerSize,
              Heap::undefined_value());
}


void FixedArray::set_null(int index) {
  ASSERT(index >= 0 && index < this->length());
  ASSERT(!Heap::InNewSpace(Heap::null_value()));
  WRITE_FIELD(this, kHeaderSize + index * kPointerSize, Heap::null_value());
}


void FixedArray::set_the_hole(int index) {
  ASSERT(index >= 0 && index < this->length());
  ASSERT(!Heap::InNewSpace(Heap::the_hole_value()));
  WRITE_FIELD(this, kHeaderSize + index * kPointerSize, Heap::the_hole_value());
}


bool DescriptorArray::IsEmpty() {
  ASSERT(this == Heap::empty_descriptor_array() ||
         this->length() > 2);
  return this == Heap::empty_descriptor_array();
}


void DescriptorArray::fast_swap(FixedArray* array, int first, int second) {
  Object* tmp = array->get(first);
  fast_set(array, first, array->get(second));
  fast_set(array, second, tmp);
}


int DescriptorArray::Search(String* name) {
  SLOW_ASSERT(IsSortedNoDuplicates());

  // Check for empty descriptor array.
  int nof = number_of_descriptors();
  if (nof == 0) return kNotFound;

  // Fast case: do linear search for small arrays.
  const int kMaxElementsForLinearSearch = 8;
  if (name->IsSymbol() && nof < kMaxElementsForLinearSearch) {
    for (int number = 0; number < nof; number++) {
      if (name == GetKey(number)) return number;
    }
    return kNotFound;
  }

  // Slow case: perform binary search.
  return BinarySearch(name, 0, nof - 1);
}



String* DescriptorArray::GetKey(int descriptor_number) {
  ASSERT(descriptor_number < number_of_descriptors());
  return String::cast(get(ToKeyIndex(descriptor_number)));
}


Object* DescriptorArray::GetValue(int descriptor_number) {
  ASSERT(descriptor_number < number_of_descriptors());
  return GetContentArray()->get(ToValueIndex(descriptor_number));
}


Smi* DescriptorArray::GetDetails(int descriptor_number) {
  ASSERT(descriptor_number < number_of_descriptors());
  return Smi::cast(GetContentArray()->get(ToDetailsIndex(descriptor_number)));
}


void DescriptorArray::Get(int descriptor_number, Descriptor* desc) {
  desc->Init(GetKey(descriptor_number),
             GetValue(descriptor_number),
             GetDetails(descriptor_number));
}


void DescriptorArray::Set(int descriptor_number, Descriptor* desc) {
  // Range check.
  ASSERT(descriptor_number < number_of_descriptors());

  // Make sure non of the elements in desc are in new space.
  ASSERT(!Heap::InNewSpace(desc->GetKey()));
  ASSERT(!Heap::InNewSpace(desc->GetValue()));

  fast_set(this, ToKeyIndex(descriptor_number), desc->GetKey());
  FixedArray* content_array = GetContentArray();
  fast_set(content_array, ToValueIndex(descriptor_number), desc->GetValue());
  fast_set(content_array, ToDetailsIndex(descriptor_number),
           desc->GetDetails().AsSmi());
}


void DescriptorArray::Swap(int first, int second) {
  fast_swap(this, ToKeyIndex(first), ToKeyIndex(second));
  FixedArray* content_array = GetContentArray();
  fast_swap(content_array, ToValueIndex(first), ToValueIndex(second));
  fast_swap(content_array, ToDetailsIndex(first),  ToDetailsIndex(second));