objects-inl.h

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// Copyright 2012 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.
//
// Review notes:
//
// - The use of macros in these inline functions may seem superfluous
// but it is absolutely needed to make sure gcc generates optimal
// code. gcc is not happy when attempting to inline too deep.
//
 
#ifndef V8_OBJECTS_INL_H_
#define V8_OBJECTS_INL_H_
 
#include "src/base/atomicops.h"
#include "src/base/bits.h"
#include "src/contexts.h"
#include "src/conversions-inl.h"
#include "src/elements.h"
#include "src/factory.h"
#include "src/field-index-inl.h"
#include "src/heap/heap-inl.h"
#include "src/heap/heap.h"
#include "src/heap/incremental-marking.h"
#include "src/heap/objects-visiting.h"
#include "src/heap/spaces.h"
#include "src/heap/store-buffer.h"
#include "src/isolate.h"
#include "src/lookup.h"
#include "src/objects.h"
#include "src/property.h"
#include "src/prototype.h"
#include "src/transitions-inl.h"
#include "src/type-feedback-vector-inl.h"
#include "src/v8memory.h"
 
namespace v8 {
namespace internal {
 
PropertyDetails::PropertyDetails(Smi* smi) {
  value_ = smi->value();
}
 
 
Smi* PropertyDetails::AsSmi() const {
  // Ensure the upper 2 bits have the same value by sign extending it. This is
  // necessary to be able to use the 31st bit of the property details.
  int value = value_ << 1;
  return Smi::FromInt(value >> 1);
}
 
 
PropertyDetails PropertyDetails::AsDeleted() const {
  Smi* smi = Smi::FromInt(value_ | DeletedField::encode(1));
  return PropertyDetails(smi);
}
 
 
#define TYPE_CHECKER(type, instancetype)                                \
  bool Object::Is##type() const {                                       \
  return Object::IsHeapObject() &&                                      \
      HeapObject::cast(this)->map()->instance_type() == instancetype;   \
  }
 
 
#define CAST_ACCESSOR(type)                       \
  type* type::cast(Object* object) {              \
    SLOW_DCHECK(object->Is##type());              \
    return reinterpret_cast<type*>(object);       \
  }                                               \
  const type* type::cast(const Object* object) {  \
    SLOW_DCHECK(object->Is##type());              \
    return reinterpret_cast<const type*>(object); \
  }
 
 
#define INT_ACCESSORS(holder, name, offset)                                   \
  int holder::name() const { return READ_INT_FIELD(this, offset); }           \
  void holder::set_##name(int value) { WRITE_INT_FIELD(this, offset, value); }
 
 
#define ACCESSORS(holder, name, type, offset)                                 \
  type* holder::name() const { return type::cast(READ_FIELD(this, offset)); } \
  void holder::set_##name(type* value, WriteBarrierMode mode) {               \
    WRITE_FIELD(this, offset, value);                                         \
    CONDITIONAL_WRITE_BARRIER(GetHeap(), this, offset, value, mode);          \
  }
 
 
// Getter that returns a tagged Smi and setter that writes a tagged Smi.
#define ACCESSORS_TO_SMI(holder, name, offset)                              \
  Smi* holder::name() const { return Smi::cast(READ_FIELD(this, offset)); } \
  void holder::set_##name(Smi* value, WriteBarrierMode mode) {              \
    WRITE_FIELD(this, offset, value);                                       \
  }
 
 
// Getter that returns a Smi as an int and writes an int as a Smi.
#define SMI_ACCESSORS(holder, name, offset)             \
  int holder::name() const {                            \
    Object* value = READ_FIELD(this, offset);           \
    return Smi::cast(value)->value();                   \
  }                                                     \
  void holder::set_##name(int value) {                  \
    WRITE_FIELD(this, offset, Smi::FromInt(value));     \
  }
 
#define SYNCHRONIZED_SMI_ACCESSORS(holder, name, offset)    \
  int holder::synchronized_##name() const {                 \
    Object* value = ACQUIRE_READ_FIELD(this, offset);       \
    return Smi::cast(value)->value();                       \
  }                                                         \
  void holder::synchronized_set_##name(int value) {         \
    RELEASE_WRITE_FIELD(this, offset, Smi::FromInt(value)); \
  }
 
#define NOBARRIER_SMI_ACCESSORS(holder, name, offset)          \
  int holder::nobarrier_##name() const {                       \
    Object* value = NOBARRIER_READ_FIELD(this, offset);        \
    return Smi::cast(value)->value();                          \
  }                                                            \
  void holder::nobarrier_set_##name(int value) {               \
    NOBARRIER_WRITE_FIELD(this, offset, Smi::FromInt(value));  \
  }
 
#define BOOL_GETTER(holder, field, name, offset)           \
  bool holder::name() const {                              \
    return BooleanBit::get(field(), offset);               \
  }                                                        \
 
 
#define BOOL_ACCESSORS(holder, field, name, offset)        \
  bool holder::name() const {                              \
    return BooleanBit::get(field(), offset);               \
  }                                                        \
  void holder::set_##name(bool value) {                    \
    set_##field(BooleanBit::set(field(), offset, value));  \
  }
 
 
bool Object::IsFixedArrayBase() const {
  return IsFixedArray() || IsFixedDoubleArray() || IsConstantPoolArray() ||
         IsFixedTypedArrayBase() || IsExternalArray();
}
 
 
// External objects are not extensible, so the map check is enough.
bool Object::IsExternal() const {
  return Object::IsHeapObject() &&
      HeapObject::cast(this)->map() ==
      HeapObject::cast(this)->GetHeap()->external_map();
}
 
 
bool Object::IsAccessorInfo() const {
  return IsExecutableAccessorInfo() || IsDeclaredAccessorInfo();
}
 
 
bool Object::IsSmi() const {
  return HAS_SMI_TAG(this);
}
 
 
bool Object::IsHeapObject() const {
  return Internals::HasHeapObjectTag(this);
}
 
 
TYPE_CHECKER(HeapNumber, HEAP_NUMBER_TYPE)
TYPE_CHECKER(MutableHeapNumber, MUTABLE_HEAP_NUMBER_TYPE)
TYPE_CHECKER(Symbol, SYMBOL_TYPE)
 
 
bool Object::IsString() const {
  return Object::IsHeapObject()
    && HeapObject::cast(this)->map()->instance_type() < FIRST_NONSTRING_TYPE;
}
 
 
bool Object::IsName() const {
  return IsString() || IsSymbol();
}
 
 
bool Object::IsUniqueName() const {
  return IsInternalizedString() || IsSymbol();
}
 
 
bool Object::IsSpecObject() const {
  return Object::IsHeapObject()
    && HeapObject::cast(this)->map()->instance_type() >= FIRST_SPEC_OBJECT_TYPE;
}
 
 
bool Object::IsSpecFunction() const {
  if (!Object::IsHeapObject()) return false;
  InstanceType type = HeapObject::cast(this)->map()->instance_type();
  return type == JS_FUNCTION_TYPE || type == JS_FUNCTION_PROXY_TYPE;
}
 
 
bool Object::IsTemplateInfo() const {
  return IsObjectTemplateInfo() || IsFunctionTemplateInfo();
}
 
 
bool Object::IsInternalizedString() const {
  if (!this->IsHeapObject()) return false;
  uint32_t type = HeapObject::cast(this)->map()->instance_type();
  STATIC_ASSERT(kNotInternalizedTag != 0);
  return (type & (kIsNotStringMask | kIsNotInternalizedMask)) ==
      (kStringTag | kInternalizedTag);
}
 
 
bool Object::IsConsString() const {
  if (!IsString()) return false;
  return StringShape(String::cast(this)).IsCons();
}
 
 
bool Object::IsSlicedString() const {
  if (!IsString()) return false;
  return StringShape(String::cast(this)).IsSliced();
}
 
 
bool Object::IsSeqString() const {
  if (!IsString()) return false;
  return StringShape(String::cast(this)).IsSequential();
}
 
 
bool Object::IsSeqOneByteString() const {
  if (!IsString()) return false;
  return StringShape(String::cast(this)).IsSequential() &&
         String::cast(this)->IsOneByteRepresentation();
}
 
 
bool Object::IsSeqTwoByteString() const {
  if (!IsString()) return false;
  return StringShape(String::cast(this)).IsSequential() &&
         String::cast(this)->IsTwoByteRepresentation();
}
 
 
bool Object::IsExternalString() const {
  if (!IsString()) return false;
  return StringShape(String::cast(this)).IsExternal();
}
 
 
bool Object::IsExternalOneByteString() const {
  if (!IsString()) return false;
  return StringShape(String::cast(this)).IsExternal() &&
         String::cast(this)->IsOneByteRepresentation();
}
 
 
bool Object::IsExternalTwoByteString() const {
  if (!IsString()) return false;
  return StringShape(String::cast(this)).IsExternal() &&
         String::cast(this)->IsTwoByteRepresentation();
}
 
 
bool Object::HasValidElements() {
  // Dictionary is covered under FixedArray.
  return IsFixedArray() || IsFixedDoubleArray() || IsExternalArray() ||
         IsFixedTypedArrayBase();
}
 
 
Handle<Object> Object::NewStorageFor(Isolate* isolate,
                                     Handle<Object> object,
                                     Representation representation) {
  if (representation.IsSmi() && object->IsUninitialized()) {
    return handle(Smi::FromInt(0), isolate);
  }
  if (!representation.IsDouble()) return object;
  double value;
  if (object->IsUninitialized()) {
    value = 0;
  } else if (object->IsMutableHeapNumber()) {
    value = HeapNumber::cast(*object)->value();
  } else {
    value = object->Number();
  }
  return isolate->factory()->NewHeapNumber(value, MUTABLE);
}
 
 
Handle<Object> Object::WrapForRead(Isolate* isolate,
                                   Handle<Object> object,
                                   Representation representation) {
  DCHECK(!object->IsUninitialized());
  if (!representation.IsDouble()) {
    DCHECK(object->FitsRepresentation(representation));
    return object;
  }
  return isolate->factory()->NewHeapNumber(HeapNumber::cast(*object)->value());
}
 
 
StringShape::StringShape(const String* str)
  : type_(str->map()->instance_type()) {
  set_valid();
  DCHECK((type_ & kIsNotStringMask) == kStringTag);
}
 
 
StringShape::StringShape(Map* map)
  : type_(map->instance_type()) {
  set_valid();
  DCHECK((type_ & kIsNotStringMask) == kStringTag);
}
 
 
StringShape::StringShape(InstanceType t)
  : type_(static_cast<uint32_t>(t)) {
  set_valid();
  DCHECK((type_ & kIsNotStringMask) == kStringTag);
}
 
 
bool StringShape::IsInternalized() {
  DCHECK(valid());
  STATIC_ASSERT(kNotInternalizedTag != 0);
  return (type_ & (kIsNotStringMask | kIsNotInternalizedMask)) ==
      (kStringTag | kInternalizedTag);
}
 
 
bool String::IsOneByteRepresentation() const {
  uint32_t type = map()->instance_type();
  return (type & kStringEncodingMask) == kOneByteStringTag;
}
 
 
bool String::IsTwoByteRepresentation() const {
  uint32_t type = map()->instance_type();
  return (type & kStringEncodingMask) == kTwoByteStringTag;
}
 
 
bool String::IsOneByteRepresentationUnderneath() {
  uint32_t type = map()->instance_type();
  STATIC_ASSERT(kIsIndirectStringTag != 0);
  STATIC_ASSERT((kIsIndirectStringMask & kStringEncodingMask) == 0);
  DCHECK(IsFlat());
  switch (type & (kIsIndirectStringMask | kStringEncodingMask)) {
    case kOneByteStringTag:
      return true;
    case kTwoByteStringTag:
      return false;
    default:  // Cons or sliced string.  Need to go deeper.
      return GetUnderlying()->IsOneByteRepresentation();
  }
}
 
 
bool String::IsTwoByteRepresentationUnderneath() {
  uint32_t type = map()->instance_type();
  STATIC_ASSERT(kIsIndirectStringTag != 0);
  STATIC_ASSERT((kIsIndirectStringMask & kStringEncodingMask) == 0);
  DCHECK(IsFlat());
  switch (type & (kIsIndirectStringMask | kStringEncodingMask)) {
    case kOneByteStringTag:
      return false;
    case kTwoByteStringTag:
      return true;
    default:  // Cons or sliced string.  Need to go deeper.
      return GetUnderlying()->IsTwoByteRepresentation();
  }
}
 
 
bool String::HasOnlyOneByteChars() {
  uint32_t type = map()->instance_type();
  return (type & kOneByteDataHintMask) == kOneByteDataHintTag ||
         IsOneByteRepresentation();
}
 
 
bool StringShape::IsCons() {
  return (type_ & kStringRepresentationMask) == kConsStringTag;
}
 
 
bool StringShape::IsSliced() {
  return (type_ & kStringRepresentationMask) == kSlicedStringTag;
}
 
 
bool StringShape::IsIndirect() {
  return (type_ & kIsIndirectStringMask) == kIsIndirectStringTag;
}
 
 
bool StringShape::IsExternal() {
  return (type_ & kStringRepresentationMask) == kExternalStringTag;
}
 
 
bool StringShape::IsSequential() {
  return (type_ & kStringRepresentationMask) == kSeqStringTag;
}
 
 
StringRepresentationTag StringShape::representation_tag() {
  uint32_t tag = (type_ & kStringRepresentationMask);
  return static_cast<StringRepresentationTag>(tag);
}
 
 
uint32_t StringShape::encoding_tag() {
  return type_ & kStringEncodingMask;
}
 
 
uint32_t StringShape::full_representation_tag() {
  return (type_ & (kStringRepresentationMask | kStringEncodingMask));
}
 
 
STATIC_ASSERT((kStringRepresentationMask | kStringEncodingMask) ==
             Internals::kFullStringRepresentationMask);
 
STATIC_ASSERT(static_cast<uint32_t>(kStringEncodingMask) ==
             Internals::kStringEncodingMask);
 
 
bool StringShape::IsSequentialOneByte() {
  return full_representation_tag() == (kSeqStringTag | kOneByteStringTag);
}
 
 
bool StringShape::IsSequentialTwoByte() {
  return full_representation_tag() == (kSeqStringTag | kTwoByteStringTag);
}
 
 
bool StringShape::IsExternalOneByte() {
  return full_representation_tag() == (kExternalStringTag | kOneByteStringTag);
}
 
 
STATIC_ASSERT((kExternalStringTag | kOneByteStringTag) ==
              Internals::kExternalOneByteRepresentationTag);
 
STATIC_ASSERT(v8::String::ONE_BYTE_ENCODING == kOneByteStringTag);
 
 
bool StringShape::IsExternalTwoByte() {
  return full_representation_tag() == (kExternalStringTag | kTwoByteStringTag);
}
 
 
STATIC_ASSERT((kExternalStringTag | kTwoByteStringTag) ==
             Internals::kExternalTwoByteRepresentationTag);
 
STATIC_ASSERT(v8::String::TWO_BYTE_ENCODING == kTwoByteStringTag);
 
uc32 FlatStringReader::Get(int index) {
  DCHECK(0 <= index && index <= length_);
  if (is_one_byte_) {
    return static_cast<const byte*>(start_)[index];
  } else {
    return static_cast<const uc16*>(start_)[index];
  }
}
 
 
Handle<Object> StringTableShape::AsHandle(Isolate* isolate, HashTableKey* key) {
  return key->AsHandle(isolate);
}
 
 
Handle<Object> MapCacheShape::AsHandle(Isolate* isolate, HashTableKey* key) {
  return key->AsHandle(isolate);
}
 
 
Handle<Object> CompilationCacheShape::AsHandle(Isolate* isolate,
                                               HashTableKey* key) {
  return key->AsHandle(isolate);
}
 
 
Handle<Object> CodeCacheHashTableShape::AsHandle(Isolate* isolate,
                                                 HashTableKey* key) {
  return key->AsHandle(isolate);
}
 
template <typename Char>
class SequentialStringKey : public HashTableKey {
 public:
  explicit SequentialStringKey(Vector<const Char> string, uint32_t seed)
      : string_(string), hash_field_(0), seed_(seed) { }
 
  virtual uint32_t Hash() OVERRIDE {
    hash_field_ = StringHasher::HashSequentialString<Char>(string_.start(),
                                                           string_.length(),
                                                           seed_);
 
    uint32_t result = hash_field_ >> String::kHashShift;
    DCHECK(result != 0);  // Ensure that the hash value of 0 is never computed.
    return result;
  }
 
 
  virtual uint32_t HashForObject(Object* other) OVERRIDE {
    return String::cast(other)->Hash();
  }
 
  Vector<const Char> string_;
  uint32_t hash_field_;
  uint32_t seed_;
};
 
 
class OneByteStringKey : public SequentialStringKey<uint8_t> {
 public:
  OneByteStringKey(Vector<const uint8_t> str, uint32_t seed)
      : SequentialStringKey<uint8_t>(str, seed) { }
 
  virtual bool IsMatch(Object* string) OVERRIDE {
    return String::cast(string)->IsOneByteEqualTo(string_);
  }
 
  virtual Handle<Object> AsHandle(Isolate* isolate) OVERRIDE;
};
 
 
class SeqOneByteSubStringKey : public HashTableKey {
 public:
  SeqOneByteSubStringKey(Handle<SeqOneByteString> string, int from, int length)
      : string_(string), from_(from), length_(length) {
    DCHECK(string_->IsSeqOneByteString());
  }
 
  virtual uint32_t Hash() OVERRIDE {
    DCHECK(length_ >= 0);
    DCHECK(from_ + length_ <= string_->length());
    const uint8_t* chars = string_->GetChars() + from_;
    hash_field_ = StringHasher::HashSequentialString(
        chars, length_, string_->GetHeap()->HashSeed());
    uint32_t result = hash_field_ >> String::kHashShift;
    DCHECK(result != 0);  // Ensure that the hash value of 0 is never computed.
    return result;
  }
 
  virtual uint32_t HashForObject(Object* other) OVERRIDE {
    return String::cast(other)->Hash();
  }
 
  virtual bool IsMatch(Object* string) OVERRIDE;
  virtual Handle<Object> AsHandle(Isolate* isolate) OVERRIDE;
 
 private:
  Handle<SeqOneByteString> string_;
  int from_;
  int length_;
  uint32_t hash_field_;
};
 
 
class TwoByteStringKey : public SequentialStringKey<uc16> {
 public:
  explicit TwoByteStringKey(Vector<const uc16> str, uint32_t seed)
      : SequentialStringKey<uc16>(str, seed) { }
 
  virtual bool IsMatch(Object* string) OVERRIDE {
    return String::cast(string)->IsTwoByteEqualTo(string_);
  }
 
  virtual Handle<Object> AsHandle(Isolate* isolate) OVERRIDE;
};
 
 
// Utf8StringKey carries a vector of chars as key.
class Utf8StringKey : public HashTableKey {
 public:
  explicit Utf8StringKey(Vector<const char> string, uint32_t seed)
      : string_(string), hash_field_(0), seed_(seed) { }
 
  virtual bool IsMatch(Object* string) OVERRIDE {
    return String::cast(string)->IsUtf8EqualTo(string_);
  }
 
  virtual uint32_t Hash() OVERRIDE {
    if (hash_field_ != 0) return hash_field_ >> String::kHashShift;
    hash_field_ = StringHasher::ComputeUtf8Hash(string_, seed_, &chars_);
    uint32_t result = hash_field_ >> String::kHashShift;
    DCHECK(result != 0);  // Ensure that the hash value of 0 is never computed.
    return result;
  }
 
  virtual uint32_t HashForObject(Object* other) OVERRIDE {
    return String::cast(other)->Hash();
  }
 
  virtual Handle<Object> AsHandle(Isolate* isolate) OVERRIDE {
    if (hash_field_ == 0) Hash();
    return isolate->factory()->NewInternalizedStringFromUtf8(
        string_, chars_, hash_field_);
  }
 
  Vector<const char> string_;
  uint32_t hash_field_;
  int chars_;  // Caches the number of characters when computing the hash code.
  uint32_t seed_;
};
 
 
bool Object::IsNumber() const {
  return IsSmi() || IsHeapNumber();
}
 
 
TYPE_CHECKER(ByteArray, BYTE_ARRAY_TYPE)
TYPE_CHECKER(FreeSpace, FREE_SPACE_TYPE)
 
 
bool Object::IsFiller() const {
  if (!Object::IsHeapObject()) return false;
  InstanceType instance_type = HeapObject::cast(this)->map()->instance_type();
  return instance_type == FREE_SPACE_TYPE || instance_type == FILLER_TYPE;
}
 
 
bool Object::IsExternalArray() const {
  if (!Object::IsHeapObject())
    return false;
  InstanceType instance_type =
      HeapObject::cast(this)->map()->instance_type();
  return (instance_type >= FIRST_EXTERNAL_ARRAY_TYPE &&
          instance_type <= LAST_EXTERNAL_ARRAY_TYPE);
}
 
 
#define TYPED_ARRAY_TYPE_CHECKER(Type, type, TYPE, ctype, size)               \
  TYPE_CHECKER(External##Type##Array, EXTERNAL_##TYPE##_ARRAY_TYPE)           \
  TYPE_CHECKER(Fixed##Type##Array, FIXED_##TYPE##_ARRAY_TYPE)
 
TYPED_ARRAYS(TYPED_ARRAY_TYPE_CHECKER)
#undef TYPED_ARRAY_TYPE_CHECKER
 
 
bool Object::IsFixedTypedArrayBase() const {
  if (!Object::IsHeapObject()) return false;
 
  InstanceType instance_type =
      HeapObject::cast(this)->map()->instance_type();
  return (instance_type >= FIRST_FIXED_TYPED_ARRAY_TYPE &&
          instance_type <= LAST_FIXED_TYPED_ARRAY_TYPE);
}
 
 
bool Object::IsJSReceiver() const {
  STATIC_ASSERT(LAST_JS_RECEIVER_TYPE == LAST_TYPE);
  return IsHeapObject() &&
      HeapObject::cast(this)->map()->instance_type() >= FIRST_JS_RECEIVER_TYPE;
}
 
 
bool Object::IsJSObject() const {
  STATIC_ASSERT(LAST_JS_OBJECT_TYPE == LAST_TYPE);
  return IsHeapObject() &&
      HeapObject::cast(this)->map()->instance_type() >= FIRST_JS_OBJECT_TYPE;
}
 
 
bool Object::IsJSProxy() const {
  if (!Object::IsHeapObject()) return false;
  return  HeapObject::cast(this)->map()->IsJSProxyMap();
}
 
 
TYPE_CHECKER(JSFunctionProxy, JS_FUNCTION_PROXY_TYPE)
TYPE_CHECKER(JSSet, JS_SET_TYPE)
TYPE_CHECKER(JSMap, JS_MAP_TYPE)
TYPE_CHECKER(JSSetIterator, JS_SET_ITERATOR_TYPE)
TYPE_CHECKER(JSMapIterator, JS_MAP_ITERATOR_TYPE)
TYPE_CHECKER(JSWeakMap, JS_WEAK_MAP_TYPE)
TYPE_CHECKER(JSWeakSet, JS_WEAK_SET_TYPE)
TYPE_CHECKER(JSContextExtensionObject, JS_CONTEXT_EXTENSION_OBJECT_TYPE)
TYPE_CHECKER(Map, MAP_TYPE)
TYPE_CHECKER(FixedArray, FIXED_ARRAY_TYPE)
TYPE_CHECKER(FixedDoubleArray, FIXED_DOUBLE_ARRAY_TYPE)
TYPE_CHECKER(ConstantPoolArray, CONSTANT_POOL_ARRAY_TYPE)
 
 
bool Object::IsJSWeakCollection() const {
  return IsJSWeakMap() || IsJSWeakSet();
}
 
 
bool Object::IsDescriptorArray() const {
  return IsFixedArray();
}
 
 
bool Object::IsTransitionArray() const {
  return IsFixedArray();
}
 
 
bool Object::IsTypeFeedbackVector() const { return IsFixedArray(); }
 
 
bool Object::IsDeoptimizationInputData() const {
  // Must be a fixed array.
  if (!IsFixedArray()) return false;
 
  // There's no sure way to detect the difference between a fixed array and
  // a deoptimization data array.  Since this is used for asserts we can
  // check that the length is zero or else the fixed size plus a multiple of
  // the entry size.
  int length = FixedArray::cast(this)->length();
  if (length == 0) return true;
 
  length -= DeoptimizationInputData::kFirstDeoptEntryIndex;
  return length >= 0 && length % DeoptimizationInputData::kDeoptEntrySize == 0;
}
 
 
bool Object::IsDeoptimizationOutputData() const {
  if (!IsFixedArray()) return false;
  // There's actually no way to see the difference between a fixed array and
  // a deoptimization data array.  Since this is used for asserts we can check
  // that the length is plausible though.
  if (FixedArray::cast(this)->length() % 2 != 0) return false;
  return true;
}
 
 
bool Object::IsDependentCode() const {
  if (!IsFixedArray()) return false;
  // There's actually no way to see the difference between a fixed array and
  // a dependent codes array.
  return true;
}
 
 
bool Object::IsContext() const {
  if (!Object::IsHeapObject()) return false;
  Map* map = HeapObject::cast(this)->map();
  Heap* heap = map->GetHeap();
  return (map == heap->function_context_map() ||
      map == heap->catch_context_map() ||
      map == heap->with_context_map() ||
      map == heap->native_context_map() ||
      map == heap->block_context_map() ||
      map == heap->module_context_map() ||
      map == heap->global_context_map());
}
 
 
bool Object::IsNativeContext() const {
  return Object::IsHeapObject() &&
      HeapObject::cast(this)->map() ==
      HeapObject::cast(this)->GetHeap()->native_context_map();
}
 
 
bool Object::IsScopeInfo() const {
  return Object::IsHeapObject() &&
      HeapObject::cast(this)->map() ==
      HeapObject::cast(this)->GetHeap()->scope_info_map();
}
 
 
TYPE_CHECKER(JSFunction, JS_FUNCTION_TYPE)
 
 
template <> inline bool Is<JSFunction>(Object* obj) {
  return obj->IsJSFunction();
}
 
 
TYPE_CHECKER(Code, CODE_TYPE)
TYPE_CHECKER(Oddball, ODDBALL_TYPE)
TYPE_CHECKER(Cell, CELL_TYPE)
TYPE_CHECKER(PropertyCell, PROPERTY_CELL_TYPE)
TYPE_CHECKER(SharedFunctionInfo, SHARED_FUNCTION_INFO_TYPE)
TYPE_CHECKER(JSGeneratorObject, JS_GENERATOR_OBJECT_TYPE)
TYPE_CHECKER(JSModule, JS_MODULE_TYPE)
TYPE_CHECKER(JSValue, JS_VALUE_TYPE)
TYPE_CHECKER(JSDate, JS_DATE_TYPE)
TYPE_CHECKER(JSMessageObject, JS_MESSAGE_OBJECT_TYPE)
 
 
bool Object::IsStringWrapper() const {
  return IsJSValue() && JSValue::cast(this)->value()->IsString();
}
 
 
TYPE_CHECKER(Foreign, FOREIGN_TYPE)
 
 
bool Object::IsBoolean() const {
  return IsOddball() &&
      ((Oddball::cast(this)->kind() & Oddball::kNotBooleanMask) == 0);
}
 
 
TYPE_CHECKER(JSArray, JS_ARRAY_TYPE)
TYPE_CHECKER(JSArrayBuffer, JS_ARRAY_BUFFER_TYPE)
TYPE_CHECKER(JSTypedArray, JS_TYPED_ARRAY_TYPE)
TYPE_CHECKER(JSDataView, JS_DATA_VIEW_TYPE)
 
 
bool Object::IsJSArrayBufferView() const {
  return IsJSDataView() || IsJSTypedArray();
}
 
 
TYPE_CHECKER(JSRegExp, JS_REGEXP_TYPE)
 
 
template <> inline bool Is<JSArray>(Object* obj) {
  return obj->IsJSArray();
}
 
 
bool Object::IsHashTable() const {
  return Object::IsHeapObject() &&
      HeapObject::cast(this)->map() ==
      HeapObject::cast(this)->GetHeap()->hash_table_map();
}
 
 
bool Object::IsWeakHashTable() const {
  return IsHashTable();
}
 
 
bool Object::IsDictionary() const {
  return IsHashTable() &&
      this != HeapObject::cast(this)->GetHeap()->string_table();
}
 
 
bool Object::IsNameDictionary() const {
  return IsDictionary();
}
 
 
bool Object::IsSeededNumberDictionary() const {
  return IsDictionary();
}
 
 
bool Object::IsUnseededNumberDictionary() const {
  return IsDictionary();
}
 
 
bool Object::IsStringTable() const {
  return IsHashTable();
}
 
 
bool Object::IsJSFunctionResultCache() const {
  if (!IsFixedArray()) return false;
  const FixedArray* self = FixedArray::cast(this);
  int length = self->length();
  if (length < JSFunctionResultCache::kEntriesIndex) return false;
  if ((length - JSFunctionResultCache::kEntriesIndex)
      % JSFunctionResultCache::kEntrySize != 0) {
    return false;
  }
#ifdef VERIFY_HEAP
  if (FLAG_verify_heap) {
    // TODO(svenpanne) We use const_cast here and below to break our dependency
    // cycle between the predicates and the verifiers. This can be removed when
    // the verifiers are const-correct, too.
    reinterpret_cast<JSFunctionResultCache*>(const_cast<Object*>(this))->
        JSFunctionResultCacheVerify();
  }
#endif
  return true;
}
 
 
bool Object::IsNormalizedMapCache() const {
  return NormalizedMapCache::IsNormalizedMapCache(this);
}
 
 
int NormalizedMapCache::GetIndex(Handle<Map> map) {
  return map->Hash() % NormalizedMapCache::kEntries;
}
 
 
bool NormalizedMapCache::IsNormalizedMapCache(const Object* obj) {
  if (!obj->IsFixedArray()) return false;
  if (FixedArray::cast(obj)->length() != NormalizedMapCache::kEntries) {
    return false;
  }
#ifdef VERIFY_HEAP
  if (FLAG_verify_heap) {
    reinterpret_cast<NormalizedMapCache*>(const_cast<Object*>(obj))->
        NormalizedMapCacheVerify();
  }
#endif
  return true;
}
 
 
bool Object::IsCompilationCacheTable() const {
  return IsHashTable();
}
 
 
bool Object::IsCodeCacheHashTable() const {
  return IsHashTable();
}
 
 
bool Object::IsPolymorphicCodeCacheHashTable() const {
  return IsHashTable();
}
 
 
bool Object::IsMapCache() const {
  return IsHashTable();
}
 
 
bool Object::IsObjectHashTable() const {
  return IsHashTable();
}
 
 
bool Object::IsOrderedHashTable() const {
  return IsHeapObject() &&
      HeapObject::cast(this)->map() ==
      HeapObject::cast(this)->GetHeap()->ordered_hash_table_map();
}
 
 
bool Object::IsOrderedHashSet() const {
  return IsOrderedHashTable();
}
 
 
bool Object::IsOrderedHashMap() const {
  return IsOrderedHashTable();
}
 
 
bool Object::IsPrimitive() const {
  return IsOddball() || IsNumber() || IsString();
}
 
 
bool Object::IsJSGlobalProxy() const {
  bool result = IsHeapObject() &&
                (HeapObject::cast(this)->map()->instance_type() ==
                 JS_GLOBAL_PROXY_TYPE);
  DCHECK(!result ||
         HeapObject::cast(this)->map()->is_access_check_needed());
  return result;
}
 
 
bool Object::IsGlobalObject() const {
  if (!IsHeapObject()) return false;
 
  InstanceType type = HeapObject::cast(this)->map()->instance_type();
  return type == JS_GLOBAL_OBJECT_TYPE ||
         type == JS_BUILTINS_OBJECT_TYPE;
}
 
 
TYPE_CHECKER(JSGlobalObject, JS_GLOBAL_OBJECT_TYPE)
TYPE_CHECKER(JSBuiltinsObject, JS_BUILTINS_OBJECT_TYPE)
 
 
bool Object::IsUndetectableObject() const {
  return IsHeapObject()
    && HeapObject::cast(this)->map()->is_undetectable();
}
 
 
bool Object::IsAccessCheckNeeded() const {
  if (!IsHeapObject()) return false;
  if (IsJSGlobalProxy()) {
    const JSGlobalProxy* proxy = JSGlobalProxy::cast(this);
    GlobalObject* global = proxy->GetIsolate()->context()->global_object();
    return proxy->IsDetachedFrom(global);
  }
  return HeapObject::cast(this)->map()->is_access_check_needed();
}
 
 
bool Object::IsStruct() const {
  if (!IsHeapObject()) return false;
  switch (HeapObject::cast(this)->map()->instance_type()) {
#define MAKE_STRUCT_CASE(NAME, Name, name) case NAME##_TYPE: return true;
  STRUCT_LIST(MAKE_STRUCT_CASE)
#undef MAKE_STRUCT_CASE
    default: return false;
  }
}
 
 
#define MAKE_STRUCT_PREDICATE(NAME, Name, name)                         \
  bool Object::Is##Name() const {                                       \
    return Object::IsHeapObject()                                       \
      && HeapObject::cast(this)->map()->instance_type() == NAME##_TYPE; \
  }
  STRUCT_LIST(MAKE_STRUCT_PREDICATE)
#undef MAKE_STRUCT_PREDICATE
 
 
bool Object::IsUndefined() const {
  return IsOddball() && Oddball::cast(this)->kind() == Oddball::kUndefined;
}
 
 
bool Object::IsNull() const {
  return IsOddball() && Oddball::cast(this)->kind() == Oddball::kNull;
}
 
 
bool Object::IsTheHole() const {
  return IsOddball() && Oddball::cast(this)->kind() == Oddball::kTheHole;
}
 
 
bool Object::IsException() const {
  return IsOddball() && Oddball::cast(this)->kind() == Oddball::kException;
}
 
 
bool Object::IsUninitialized() const {
  return IsOddball() && Oddball::cast(this)->kind() == Oddball::kUninitialized;
}
 
 
bool Object::IsTrue() const {
  return IsOddball() && Oddball::cast(this)->kind() == Oddball::kTrue;
}
 
 
bool Object::IsFalse() const {
  return IsOddball() && Oddball::cast(this)->kind() == Oddball::kFalse;
}
 
 
bool Object::IsArgumentsMarker() const {
  return IsOddball() && Oddball::cast(this)->kind() == Oddball::kArgumentMarker;
}
 
 
double Object::Number() {
  DCHECK(IsNumber());
  return IsSmi()
    ? static_cast<double>(reinterpret_cast<Smi*>(this)->value())
    : reinterpret_cast<HeapNumber*>(this)->value();
}
 
 
bool Object::IsNaN() const {
  return this->IsHeapNumber() && std::isnan(HeapNumber::cast(this)->value());
}
 
 
bool Object::IsMinusZero() const {
  return this->IsHeapNumber() &&
         i::IsMinusZero(HeapNumber::cast(this)->value());
}
 
 
MaybeHandle<Smi> Object::ToSmi(Isolate* isolate, Handle<Object> object) {
  if (object->IsSmi()) return Handle<Smi>::cast(object);
  if (object->IsHeapNumber()) {
    double value = Handle<HeapNumber>::cast(object)->value();
    int int_value = FastD2I(value);
    if (value == FastI2D(int_value) && Smi::IsValid(int_value)) {
      return handle(Smi::FromInt(int_value), isolate);
    }
  }
  return Handle<Smi>();
}
 
 
MaybeHandle<JSReceiver> Object::ToObject(Isolate* isolate,
                                         Handle<Object> object) {
  return ToObject(
      isolate, object, handle(isolate->context()->native_context(), isolate));
}
 
 
bool Object::HasSpecificClassOf(String* name) {
  return this->IsJSObject() && (JSObject::cast(this)->class_name() == name);
}
 
 
MaybeHandle<Object> Object::GetProperty(Handle<Object> object,
                                        Handle<Name> name) {
  LookupIterator it(object, name);
  return GetProperty(&it);
}
 
 
MaybeHandle<Object> Object::GetElement(Isolate* isolate,
                                       Handle<Object> object,
                                       uint32_t index) {
  // GetElement can trigger a getter which can cause allocation.
  // This was not always the case. This DCHECK is here to catch
  // leftover incorrect uses.
  DCHECK(AllowHeapAllocation::IsAllowed());
  return Object::GetElementWithReceiver(isolate, object, object, index);
}
 
 
MaybeHandle<Object> Object::GetPropertyOrElement(Handle<Object> object,
                                                 Handle<Name> name) {
  uint32_t index;
  Isolate* isolate = name->GetIsolate();
  if (name->AsArrayIndex(&index)) return GetElement(isolate, object, index);
  return GetProperty(object, name);
}
 
 
MaybeHandle<Object> Object::GetProperty(Isolate* isolate,
                                        Handle<Object> object,
                                        const char* name) {
  Handle<String> str = isolate->factory()->InternalizeUtf8String(name);
  DCHECK(!str.is_null());
#ifdef DEBUG
  uint32_t index;  // Assert that the name is not an array index.
  DCHECK(!str->AsArrayIndex(&index));
#endif  // DEBUG
  return GetProperty(object, str);
}
 
 
MaybeHandle<Object> JSProxy::GetElementWithHandler(Handle<JSProxy> proxy,
                                                   Handle<Object> receiver,
                                                   uint32_t index) {
  return GetPropertyWithHandler(
      proxy, receiver, proxy->GetIsolate()->factory()->Uint32ToString(index));
}
 
 
MaybeHandle<Object> JSProxy::SetElementWithHandler(Handle<JSProxy> proxy,
                                                   Handle<JSReceiver> receiver,
                                                   uint32_t index,
                                                   Handle<Object> value,
                                                   StrictMode strict_mode) {
  Isolate* isolate = proxy->GetIsolate();
  Handle<String> name = isolate->factory()->Uint32ToString(index);
  return SetPropertyWithHandler(proxy, receiver, name, value, strict_mode);
}
 
 
Maybe<bool> JSProxy::HasElementWithHandler(Handle<JSProxy> proxy,
                                           uint32_t index) {
  Isolate* isolate = proxy->GetIsolate();
  Handle<String> name = isolate->factory()->Uint32ToString(index);
  return HasPropertyWithHandler(proxy, name);
}
 
 
#define FIELD_ADDR(p, offset) \
  (reinterpret_cast<byte*>(p) + offset - kHeapObjectTag)
 
#define FIELD_ADDR_CONST(p, offset) \
  (reinterpret_cast<const byte*>(p) + offset - kHeapObjectTag)
 
#define READ_FIELD(p, offset) \
  (*reinterpret_cast<Object* const*>(FIELD_ADDR_CONST(p, offset)))
 
#define ACQUIRE_READ_FIELD(p, offset)           \
  reinterpret_cast<Object*>(base::Acquire_Load( \
      reinterpret_cast<const base::AtomicWord*>(FIELD_ADDR_CONST(p, offset))))
 
#define NOBARRIER_READ_FIELD(p, offset)           \
  reinterpret_cast<Object*>(base::NoBarrier_Load( \
      reinterpret_cast<const base::AtomicWord*>(FIELD_ADDR_CONST(p, offset))))
 
#define WRITE_FIELD(p, offset, value) \
  (*reinterpret_cast<Object**>(FIELD_ADDR(p, offset)) = value)
 
#define RELEASE_WRITE_FIELD(p, offset, value)                     \
  base::Release_Store(                                            \
      reinterpret_cast<base::AtomicWord*>(FIELD_ADDR(p, offset)), \
      reinterpret_cast<base::AtomicWord>(value));
 
#define NOBARRIER_WRITE_FIELD(p, offset, value)                   \
  base::NoBarrier_Store(                                          \
      reinterpret_cast<base::AtomicWord*>(FIELD_ADDR(p, offset)), \
      reinterpret_cast<base::AtomicWord>(value));
 
#define WRITE_BARRIER(heap, object, offset, value)                      \
  heap->incremental_marking()->RecordWrite(                             \
      object, HeapObject::RawField(object, offset), value);             \
  if (heap->InNewSpace(value)) {                                        \
    heap->RecordWrite(object->address(), offset);                       \
  }
 
#define CONDITIONAL_WRITE_BARRIER(heap, object, offset, value, mode)    \
  if (mode == UPDATE_WRITE_BARRIER) {                                   \
    heap->incremental_marking()->RecordWrite(                           \
      object, HeapObject::RawField(object, offset), value);             \
    if (heap->InNewSpace(value)) {                                      \
      heap->RecordWrite(object->address(), offset);                     \
    }                                                                   \
  }
 
#ifndef V8_TARGET_ARCH_MIPS
  #define READ_DOUBLE_FIELD(p, offset) \
    (*reinterpret_cast<const double*>(FIELD_ADDR_CONST(p, offset)))
#else  // V8_TARGET_ARCH_MIPS
  // Prevent gcc from using load-double (mips ldc1) on (possibly)
  // non-64-bit aligned HeapNumber::value.
  static inline double read_double_field(const void* p, int offset) {
    union conversion {
      double d;
      uint32_t u[2];
    } c;
    c.u[0] = (*reinterpret_cast<const uint32_t*>(
        FIELD_ADDR_CONST(p, offset)));
    c.u[1] = (*reinterpret_cast<const uint32_t*>(
        FIELD_ADDR_CONST(p, offset + 4)));
    return c.d;
  }
  #define READ_DOUBLE_FIELD(p, offset) read_double_field(p, offset)
#endif  // V8_TARGET_ARCH_MIPS
 
#ifndef V8_TARGET_ARCH_MIPS
  #define WRITE_DOUBLE_FIELD(p, offset, value) \
    (*reinterpret_cast<double*>(FIELD_ADDR(p, offset)) = value)
#else  // V8_TARGET_ARCH_MIPS
  // Prevent gcc from using store-double (mips sdc1) on (possibly)
  // non-64-bit aligned HeapNumber::value.
  static inline void write_double_field(void* p, int offset,
                                        double value) {
    union conversion {
      double d;
      uint32_t u[2];
    } c;
    c.d = value;
    (*reinterpret_cast<uint32_t*>(FIELD_ADDR(p, offset))) = c.u[0];
    (*reinterpret_cast<uint32_t*>(FIELD_ADDR(p, offset + 4))) = c.u[1];
  }
  #define WRITE_DOUBLE_FIELD(p, offset, value) \
    write_double_field(p, offset, value)
#endif  // V8_TARGET_ARCH_MIPS
 
 
#define READ_INT_FIELD(p, offset) \
  (*reinterpret_cast<const int*>(FIELD_ADDR_CONST(p, offset)))
 
#define WRITE_INT_FIELD(p, offset, value) \
  (*reinterpret_cast<int*>(FIELD_ADDR(p, offset)) = value)
 
#define READ_INTPTR_FIELD(p, offset) \
  (*reinterpret_cast<const intptr_t*>(FIELD_ADDR_CONST(p, offset)))
 
#define WRITE_INTPTR_FIELD(p, offset, value) \
  (*reinterpret_cast<intptr_t*>(FIELD_ADDR(p, offset)) = value)
 
#define READ_UINT32_FIELD(p, offset) \
  (*reinterpret_cast<const uint32_t*>(FIELD_ADDR_CONST(p, offset)))
 
#define WRITE_UINT32_FIELD(p, offset, value) \
  (*reinterpret_cast<uint32_t*>(FIELD_ADDR(p, offset)) = value)
 
#define READ_INT32_FIELD(p, offset) \
  (*reinterpret_cast<const int32_t*>(FIELD_ADDR_CONST(p, offset)))
 
#define WRITE_INT32_FIELD(p, offset, value) \
  (*reinterpret_cast<int32_t*>(FIELD_ADDR(p, offset)) = value)
 
#define READ_INT64_FIELD(p, offset) \
  (*reinterpret_cast<const int64_t*>(FIELD_ADDR_CONST(p, offset)))
 
#define WRITE_INT64_FIELD(p, offset, value) \
  (*reinterpret_cast<int64_t*>(FIELD_ADDR(p, offset)) = value)
 
#define READ_SHORT_FIELD(p, offset) \
  (*reinterpret_cast<const uint16_t*>(FIELD_ADDR_CONST(p, offset)))
 
#define WRITE_SHORT_FIELD(p, offset, value) \
  (*reinterpret_cast<uint16_t*>(FIELD_ADDR(p, offset)) = value)
 
#define READ_BYTE_FIELD(p, offset) \
  (*reinterpret_cast<const byte*>(FIELD_ADDR_CONST(p, offset)))
 
#define NOBARRIER_READ_BYTE_FIELD(p, offset) \
  static_cast<byte>(base::NoBarrier_Load(    \
      reinterpret_cast<base::Atomic8*>(FIELD_ADDR(p, offset))))
 
#define WRITE_BYTE_FIELD(p, offset, value) \
  (*reinterpret_cast<byte*>(FIELD_ADDR(p, offset)) = value)
 
#define NOBARRIER_WRITE_BYTE_FIELD(p, offset, value)           \
  base::NoBarrier_Store(                                       \
      reinterpret_cast<base::Atomic8*>(FIELD_ADDR(p, offset)), \
      static_cast<base::Atomic8>(value));
 
Object** HeapObject::RawField(HeapObject* obj, int byte_offset) {
  return reinterpret_cast<Object**>(FIELD_ADDR(obj, byte_offset));
}
 
 
int Smi::value() const {
  return Internals::SmiValue(this);
}
 
 
Smi* Smi::FromInt(int value) {
  DCHECK(Smi::IsValid(value));
  return reinterpret_cast<Smi*>(Internals::IntToSmi(value));
}
 
 
Smi* Smi::FromIntptr(intptr_t value) {
  DCHECK(Smi::IsValid(value));
  int smi_shift_bits = kSmiTagSize + kSmiShiftSize;
  return reinterpret_cast<Smi*>((value << smi_shift_bits) | kSmiTag);
}
 
 
bool Smi::IsValid(intptr_t value) {
  bool result = Internals::IsValidSmi(value);
  DCHECK_EQ(result, value >= kMinValue && value <= kMaxValue);
  return result;
}
 
 
MapWord MapWord::FromMap(const Map* map) {
  return MapWord(reinterpret_cast<uintptr_t>(map));
}
 
 
Map* MapWord::ToMap() {
  return reinterpret_cast<Map*>(value_);
}
 
 
bool MapWord::IsForwardingAddress() {
  return HAS_SMI_TAG(reinterpret_cast<Object*>(value_));
}
 
 
MapWord MapWord::FromForwardingAddress(HeapObject* object) {
  Address raw = reinterpret_cast<Address>(object) - kHeapObjectTag;
  return MapWord(reinterpret_cast<uintptr_t>(raw));
}
 
 
HeapObject* MapWord::ToForwardingAddress() {
  DCHECK(IsForwardingAddress());
  return HeapObject::FromAddress(reinterpret_cast<Address>(value_));
}
 
 
#ifdef VERIFY_HEAP
void HeapObject::VerifyObjectField(int offset) {
  VerifyPointer(READ_FIELD(this, offset));
}
 
void HeapObject::VerifySmiField(int offset) {
  CHECK(READ_FIELD(this, offset)->IsSmi());
}
#endif
 
 
Heap* HeapObject::GetHeap() const {
  Heap* heap =
      MemoryChunk::FromAddress(reinterpret_cast<const byte*>(this))->heap();
  SLOW_DCHECK(heap != NULL);
  return heap;
}
 
 
Isolate* HeapObject::GetIsolate() const {
  return GetHeap()->isolate();
}
 
 
Map* HeapObject::map() const {
#ifdef DEBUG
  // Clear mark potentially added by PathTracer.
  uintptr_t raw_value =
      map_word().ToRawValue() & ~static_cast<uintptr_t>(PathTracer::kMarkTag);
  return MapWord::FromRawValue(raw_value).ToMap();
#else
  return map_word().ToMap();
#endif
}
 
 
void HeapObject::set_map(Map* value) {
  set_map_word(MapWord::FromMap(value));
  if (value != NULL) {
    // TODO(1600) We are passing NULL as a slot because maps can never be on
    // evacuation candidate.
    value->GetHeap()->incremental_marking()->RecordWrite(this, NULL, value);
  }
}
 
 
Map* HeapObject::synchronized_map() {
  return synchronized_map_word().ToMap();
}
 
 
void HeapObject::synchronized_set_map(Map* value) {
  synchronized_set_map_word(MapWord::FromMap(value));
  if (value != NULL) {
    // TODO(1600) We are passing NULL as a slot because maps can never be on
    // evacuation candidate.
    value->GetHeap()->incremental_marking()->RecordWrite(this, NULL, value);
  }
}
 
 
void HeapObject::synchronized_set_map_no_write_barrier(Map* value) {
  synchronized_set_map_word(MapWord::FromMap(value));
}
 
 
// Unsafe accessor omitting write barrier.
void HeapObject::set_map_no_write_barrier(Map* value) {
  set_map_word(MapWord::FromMap(value));
}
 
 
MapWord HeapObject::map_word() const {
  return MapWord(
      reinterpret_cast<uintptr_t>(NOBARRIER_READ_FIELD(this, kMapOffset)));
}
 
 
void HeapObject::set_map_word(MapWord map_word) {
  NOBARRIER_WRITE_FIELD(
      this, kMapOffset, reinterpret_cast<Object*>(map_word.value_));
}
 
 
MapWord HeapObject::synchronized_map_word() const {
  return MapWord(
      reinterpret_cast<uintptr_t>(ACQUIRE_READ_FIELD(this, kMapOffset)));
}
 
 
void HeapObject::synchronized_set_map_word(MapWord map_word) {
  RELEASE_WRITE_FIELD(
      this, kMapOffset, reinterpret_cast<Object*>(map_word.value_));
}
 
 
HeapObject* HeapObject::FromAddress(Address address) {
  DCHECK_TAG_ALIGNED(address);
  return reinterpret_cast<HeapObject*>(address + kHeapObjectTag);
}
 
 
Address HeapObject::address() {
  return reinterpret_cast<Address>(this) - kHeapObjectTag;
}
 
 
int HeapObject::Size() {
  return SizeFromMap(map());
}
 
 
bool HeapObject::MayContainRawValues() {
  InstanceType type = map()->instance_type();
  if (type <= LAST_NAME_TYPE) {
    if (type == SYMBOL_TYPE) {
      return false;
    }
    DCHECK(type < FIRST_NONSTRING_TYPE);
    // There are four string representations: sequential strings, external
    // strings, cons strings, and sliced strings.
    // Only the former two contain raw values and no heap pointers (besides the
    // map-word).
    return ((type & kIsIndirectStringMask) != kIsIndirectStringTag);
  }
  // The ConstantPoolArray contains heap pointers, but also raw values.
  if (type == CONSTANT_POOL_ARRAY_TYPE) return true;
  return (type <= LAST_DATA_TYPE);
}
 
 
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::IterateNextCodeLink(ObjectVisitor* v, int offset) {
  v->VisitNextCodeLink(reinterpret_cast<Object**>(FIELD_ADDR(this, offset)));
}
 
 
double HeapNumber::value() const {
  return READ_DOUBLE_FIELD(this, kValueOffset);
}
 
 
void HeapNumber::set_value(double value) {
  WRITE_DOUBLE_FIELD(this, kValueOffset, value);
}
 
 
int HeapNumber::get_exponent() {
  return ((READ_INT_FIELD(this, kExponentOffset) & kExponentMask) >>
          kExponentShift) - kExponentBias;
}
 
 
int HeapNumber::get_sign() {
  return READ_INT_FIELD(this, kExponentOffset) & kSignMask;
}
 
 
ACCESSORS(JSObject, properties, FixedArray, kPropertiesOffset)
 
 
Object** FixedArray::GetFirstElementAddress() {
  return reinterpret_cast<Object**>(FIELD_ADDR(this, OffsetOfElementAt(0)));
}
 
 
bool FixedArray::ContainsOnlySmisOrHoles() {
  Object* the_hole = GetHeap()->the_hole_value();
  Object** current = GetFirstElementAddress();
  for (int i = 0; i < length(); ++i) {
    Object* candidate = *current++;
    if (!candidate->IsSmi() && candidate != the_hole) return false;
  }
  return true;
}
 
 
FixedArrayBase* JSObject::elements() const {
  Object* array = READ_FIELD(this, kElementsOffset);
  return static_cast<FixedArrayBase*>(array);
}
 
 
void JSObject::ValidateElements(Handle<JSObject> object) {
#ifdef ENABLE_SLOW_DCHECKS
  if (FLAG_enable_slow_asserts) {
    ElementsAccessor* accessor = object->GetElementsAccessor();
    accessor->Validate(object);
  }
#endif
}
 
 
void AllocationSite::Initialize() {
  set_transition_info(Smi::FromInt(0));
  SetElementsKind(GetInitialFastElementsKind());
  set_nested_site(Smi::FromInt(0));
  set_pretenure_data(Smi::FromInt(0));
  set_pretenure_create_count(Smi::FromInt(0));
  set_dependent_code(DependentCode::cast(GetHeap()->empty_fixed_array()),
                     SKIP_WRITE_BARRIER);
}
 
 
void AllocationSite::MarkZombie() {
  DCHECK(!IsZombie());
  Initialize();
  set_pretenure_decision(kZombie);
}
 
 
// Heuristic: We only need to create allocation site info if the boilerplate
// elements kind is the initial elements kind.
AllocationSiteMode AllocationSite::GetMode(
    ElementsKind boilerplate_elements_kind) {
  if (FLAG_pretenuring_call_new ||
      IsFastSmiElementsKind(boilerplate_elements_kind)) {
    return TRACK_ALLOCATION_SITE;
  }
 
  return DONT_TRACK_ALLOCATION_SITE;
}
 
 
AllocationSiteMode AllocationSite::GetMode(ElementsKind from,
                                           ElementsKind to) {
  if (FLAG_pretenuring_call_new ||
      (IsFastSmiElementsKind(from) &&
       IsMoreGeneralElementsKindTransition(from, to))) {
    return TRACK_ALLOCATION_SITE;
  }
 
  return DONT_TRACK_ALLOCATION_SITE;
}
 
 
inline bool AllocationSite::CanTrack(InstanceType type) {
  if (FLAG_allocation_site_pretenuring) {
    return type == JS_ARRAY_TYPE ||
        type == JS_OBJECT_TYPE ||
        type < FIRST_NONSTRING_TYPE;
  }
  return type == JS_ARRAY_TYPE;
}
 
 
inline DependentCode::DependencyGroup AllocationSite::ToDependencyGroup(
    Reason reason) {
  switch (reason) {
    case TENURING:
      return DependentCode::kAllocationSiteTenuringChangedGroup;
      break;
    case TRANSITIONS:
      return DependentCode::kAllocationSiteTransitionChangedGroup;
      break;
  }
  UNREACHABLE();
  return DependentCode::kAllocationSiteTransitionChangedGroup;
}
 
 
inline void AllocationSite::set_memento_found_count(int count) {
  int value = pretenure_data()->value();
  // Verify that we can count more mementos than we can possibly find in one
  // new space collection.
  DCHECK((GetHeap()->MaxSemiSpaceSize() /
          (StaticVisitorBase::kMinObjectSizeInWords * kPointerSize +
           AllocationMemento::kSize)) < MementoFoundCountBits::kMax);
  DCHECK(count < MementoFoundCountBits::kMax);
  set_pretenure_data(
      Smi::FromInt(MementoFoundCountBits::update(value, count)),
      SKIP_WRITE_BARRIER);
}
 
inline bool AllocationSite::IncrementMementoFoundCount() {
  if (IsZombie()) return false;
 
  int value = memento_found_count();
  set_memento_found_count(value + 1);
  return memento_found_count() == kPretenureMinimumCreated;
}
 
 
inline void AllocationSite::IncrementMementoCreateCount() {
  DCHECK(FLAG_allocation_site_pretenuring);
  int value = memento_create_count();
  set_memento_create_count(value + 1);
}
 
 
inline bool AllocationSite::MakePretenureDecision(
    PretenureDecision current_decision,
    double ratio,
    bool maximum_size_scavenge) {
  // Here we just allow state transitions from undecided or maybe tenure
  // to don't tenure, maybe tenure, or tenure.
  if ((current_decision == kUndecided || current_decision == kMaybeTenure)) {
    if (ratio >= kPretenureRatio) {
      // We just transition into tenure state when the semi-space was at
      // maximum capacity.
      if (maximum_size_scavenge) {
        set_deopt_dependent_code(true);
        set_pretenure_decision(kTenure);
        // Currently we just need to deopt when we make a state transition to
        // tenure.
        return true;
      }
      set_pretenure_decision(kMaybeTenure);
    } else {
      set_pretenure_decision(kDontTenure);
    }
  }
  return false;
}
 
 
inline bool AllocationSite::DigestPretenuringFeedback(
    bool maximum_size_scavenge) {
  bool deopt = false;
  int create_count = memento_create_count();
  int found_count = memento_found_count();
  bool minimum_mementos_created = create_count >= kPretenureMinimumCreated;
  double ratio =
      minimum_mementos_created || FLAG_trace_pretenuring_statistics ?
          static_cast<double>(found_count) / create_count : 0.0;
  PretenureDecision current_decision = pretenure_decision();
 
  if (minimum_mementos_created) {
    deopt = MakePretenureDecision(
        current_decision, ratio, maximum_size_scavenge);
  }
 
  if (FLAG_trace_pretenuring_statistics) {
    PrintF(
        "AllocationSite(%p): (created, found, ratio) (%d, %d, %f) %s => %s\n",
         static_cast<void*>(this), create_count, found_count, ratio,
         PretenureDecisionName(current_decision),
         PretenureDecisionName(pretenure_decision()));
  }
 
  // Clear feedback calculation fields until the next gc.
  set_memento_found_count(0);
  set_memento_create_count(0);
  return deopt;
}
 
 
void JSObject::EnsureCanContainHeapObjectElements(Handle<JSObject> object) {
  JSObject::ValidateElements(object);
  ElementsKind elements_kind = object->map()->elements_kind();
  if (!IsFastObjectElementsKind(elements_kind)) {
    if (IsFastHoleyElementsKind(elements_kind)) {
      TransitionElementsKind(object, FAST_HOLEY_ELEMENTS);
    } else {
      TransitionElementsKind(object, FAST_ELEMENTS);
    }
  }
}
 
 
void JSObject::EnsureCanContainElements(Handle<JSObject> object,
                                        Object** objects,
                                        uint32_t count,
                                        EnsureElementsMode mode) {
  ElementsKind current_kind = object->map()->elements_kind();
  ElementsKind target_kind = current_kind;
  {
    DisallowHeapAllocation no_allocation;
    DCHECK(mode != ALLOW_COPIED_DOUBLE_ELEMENTS);
    bool is_holey = IsFastHoleyElementsKind(current_kind);
    if (current_kind == FAST_HOLEY_ELEMENTS) return;
    Heap* heap = object->GetHeap();
    Object* the_hole = heap->the_hole_value();
    for (uint32_t i = 0; i < count; ++i) {
      Object* current = *objects++;
      if (current == the_hole) {
        is_holey = true;
        target_kind = GetHoleyElementsKind(target_kind);
      } else if (!current->IsSmi()) {
        if (mode == ALLOW_CONVERTED_DOUBLE_ELEMENTS && current->IsNumber()) {
          if (IsFastSmiElementsKind(target_kind)) {
            if (is_holey) {
              target_kind = FAST_HOLEY_DOUBLE_ELEMENTS;
            } else {
              target_kind = FAST_DOUBLE_ELEMENTS;
            }
          }
        } else if (is_holey) {
          target_kind = FAST_HOLEY_ELEMENTS;
          break;
        } else {
          target_kind = FAST_ELEMENTS;
        }
      }
    }
  }
  if (target_kind != current_kind) {
    TransitionElementsKind(object, target_kind);
  }
}
 
 
void JSObject::EnsureCanContainElements(Handle<JSObject> object,
                                        Handle<FixedArrayBase> elements,
                                        uint32_t length,
                                        EnsureElementsMode mode) {
  Heap* heap = object->GetHeap();
  if (elements->map() != heap->fixed_double_array_map()) {
    DCHECK(elements->map() == heap->fixed_array_map() ||
           elements->map() == heap->fixed_cow_array_map());
    if (mode == ALLOW_COPIED_DOUBLE_ELEMENTS) {
      mode = DONT_ALLOW_DOUBLE_ELEMENTS;
    }
    Object** objects =
        Handle<FixedArray>::cast(elements)->GetFirstElementAddress();
    EnsureCanContainElements(object, objects, length, mode);
    return;
  }
 
  DCHECK(mode == ALLOW_COPIED_DOUBLE_ELEMENTS);
  if (object->GetElementsKind() == FAST_HOLEY_SMI_ELEMENTS) {
    TransitionElementsKind(object, FAST_HOLEY_DOUBLE_ELEMENTS);
  } else if (object->GetElementsKind() == FAST_SMI_ELEMENTS) {
    Handle<FixedDoubleArray> double_array =
        Handle<FixedDoubleArray>::cast(elements);
    for (uint32_t i = 0; i < length; ++i) {
      if (double_array->is_the_hole(i)) {
        TransitionElementsKind(object, FAST_HOLEY_DOUBLE_ELEMENTS);
        return;
      }
    }
    TransitionElementsKind(object, FAST_DOUBLE_ELEMENTS);
  }
}
 
 
void JSObject::SetMapAndElements(Handle<JSObject> object,
                                 Handle<Map> new_map,
                                 Handle<FixedArrayBase> value) {
  JSObject::MigrateToMap(object, new_map);
  DCHECK((object->map()->has_fast_smi_or_object_elements() ||
          (*value == object->GetHeap()->empty_fixed_array())) ==
         (value->map() == object->GetHeap()->fixed_array_map() ||
          value->map() == object->GetHeap()->fixed_cow_array_map()));
  DCHECK((*value == object->GetHeap()->empty_fixed_array()) ||
         (object->map()->has_fast_double_elements() ==
          value->IsFixedDoubleArray()));
  object->set_elements(*value);
}
 
 
void JSObject::set_elements(FixedArrayBase* value, WriteBarrierMode mode) {
  WRITE_FIELD(this, kElementsOffset, value);
  CONDITIONAL_WRITE_BARRIER(GetHeap(), this, kElementsOffset, value, mode);
}
 
 
void JSObject::initialize_properties() {
  DCHECK(!GetHeap()->InNewSpace(GetHeap()->empty_fixed_array()));
  WRITE_FIELD(this, kPropertiesOffset, GetHeap()->empty_fixed_array());
}
 
 
void JSObject::initialize_elements() {
  FixedArrayBase* elements = map()->GetInitialElements();
  WRITE_FIELD(this, kElementsOffset, elements);
}
 
 
Handle<String> Map::ExpectedTransitionKey(Handle<Map> map) {
  DisallowHeapAllocation no_gc;
  if (!map->HasTransitionArray()) return Handle<String>::null();
  TransitionArray* transitions = map->transitions();
  if (!transitions->IsSimpleTransition()) return Handle<String>::null();
  int transition = TransitionArray::kSimpleTransitionIndex;
  PropertyDetails details = transitions->GetTargetDetails(transition);
  Name* name = transitions->GetKey(transition);
  if (details.type() != FIELD) return Handle<String>::null();
  if (details.attributes() != NONE) return Handle<String>::null();
  if (!name->IsString()) return Handle<String>::null();
  return Handle<String>(String::cast(name));
}
 
 
Handle<Map> Map::ExpectedTransitionTarget(Handle<Map> map) {
  DCHECK(!ExpectedTransitionKey(map).is_null());
  return Handle<Map>(map->transitions()->GetTarget(
      TransitionArray::kSimpleTransitionIndex));
}
 
 
Handle<Map> Map::FindTransitionToField(Handle<Map> map, Handle<Name> key) {
  DisallowHeapAllocation no_allocation;
  if (!map->HasTransitionArray()) return Handle<Map>::null();
  TransitionArray* transitions = map->transitions();
  int transition = transitions->Search(*key);
  if (transition == TransitionArray::kNotFound) return Handle<Map>::null();
  PropertyDetails target_details = transitions->GetTargetDetails(transition);
  if (target_details.type() != FIELD) return Handle<Map>::null();
  if (target_details.attributes() != NONE) return Handle<Map>::null();
  return Handle<Map>(transitions->GetTarget(transition));
}
 
 
ACCESSORS(Oddball, to_string, String, kToStringOffset)
ACCESSORS(Oddball, to_number, Object, kToNumberOffset)
 
 
byte Oddball::kind() const {
  return Smi::cast(READ_FIELD(this, kKindOffset))->value();
}
 
 
void Oddball::set_kind(byte value) {
  WRITE_FIELD(this, kKindOffset, Smi::FromInt(value));
}
 
 
Object* Cell::value() const {
  return READ_FIELD(this, kValueOffset);
}
 
 
void Cell::set_value(Object* val, WriteBarrierMode ignored) {
  // The write barrier is not used for global property cells.
  DCHECK(!val->IsPropertyCell() && !val->IsCell());
  WRITE_FIELD(this, kValueOffset, val);
}
 
ACCESSORS(PropertyCell, dependent_code, DependentCode, kDependentCodeOffset)
 
Object* PropertyCell::type_raw() const {
  return READ_FIELD(this, kTypeOffset);
}
 
 
void PropertyCell::set_type_raw(Object* val, WriteBarrierMode ignored) {
  WRITE_FIELD(this, kTypeOffset, val);
}
 
 
int JSObject::GetHeaderSize() {
  InstanceType type = map()->instance_type();
  // Check for the most common kind of JavaScript object before
  // falling into the generic switch. This speeds up the internal
  // field operations considerably on average.
  if (type == JS_OBJECT_TYPE) return JSObject::kHeaderSize;
  switch (type) {
    case JS_GENERATOR_OBJECT_TYPE:
      return JSGeneratorObject::kSize;
    case JS_MODULE_TYPE:
      return JSModule::kSize;
    case JS_GLOBAL_PROXY_TYPE:
      return JSGlobalProxy::kSize;
    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_DATE_TYPE:
      return JSDate::kSize;
    case JS_ARRAY_TYPE:
      return JSArray::kSize;
    case JS_ARRAY_BUFFER_TYPE:
      return JSArrayBuffer::kSize;
    case JS_TYPED_ARRAY_TYPE:
      return JSTypedArray::kSize;
    case JS_DATA_VIEW_TYPE:
      return JSDataView::kSize;
    case JS_SET_TYPE:
      return JSSet::kSize;
    case JS_MAP_TYPE:
      return JSMap::kSize;
    case JS_SET_ITERATOR_TYPE:
      return JSSetIterator::kSize;
    case JS_MAP_ITERATOR_TYPE:
      return JSMapIterator::kSize;
    case JS_WEAK_MAP_TYPE:
      return JSWeakMap::kSize;
    case JS_WEAK_SET_TYPE:
      return JSWeakSet::kSize;
    case JS_REGEXP_TYPE:
      return JSRegExp::kSize;
    case JS_CONTEXT_EXTENSION_OBJECT_TYPE:
      return JSObject::kHeaderSize;
    case JS_MESSAGE_OBJECT_TYPE:
      return JSMessageObject::kSize;
    default:
      // TODO(jkummerow): Re-enable this. Blink currently hits this
      // from its CustomElementConstructorBuilder.
      // UNREACHABLE();
      return 0;
  }
}
 
 
int JSObject::GetInternalFieldCount() {
  DCHECK(1 << kPointerSizeLog2 == kPointerSize);
  // Make sure to adjust for the number of in-object properties. These
  // properties do contribute to the size, but are not internal fields.
  return ((Size() - GetHeaderSize()) >> kPointerSizeLog2) -
         map()->inobject_properties();
}
 
 
int JSObject::GetInternalFieldOffset(int index) {
  DCHECK(index < GetInternalFieldCount() && index >= 0);
  return GetHeaderSize() + (kPointerSize * index);
}
 
 
Object* JSObject::GetInternalField(int index) {
  DCHECK(index < GetInternalFieldCount() && index >= 0);
  // Internal objects do follow immediately after the header, whereas in-object
  // properties are at the end of the object. Therefore there is no need
  // to adjust the index here.
  return READ_FIELD(this, GetHeaderSize() + (kPointerSize * index));
}
 
 
void JSObject::SetInternalField(int index, Object* value) {
  DCHECK(index < GetInternalFieldCount() && index >= 0);
  // Internal objects do follow immediately after the header, whereas in-object
  // properties are at the end of the object. Therefore there is no need
  // to adjust the index here.
  int offset = GetHeaderSize() + (kPointerSize * index);
  WRITE_FIELD(this, offset, value);
  WRITE_BARRIER(GetHeap(), this, offset, value);
}
 
 
void JSObject::SetInternalField(int index, Smi* value) {
  DCHECK(index < GetInternalFieldCount() && index >= 0);
  // Internal objects do follow immediately after the header, whereas in-object
  // properties are at the end of the object. Therefore there is no need
  // to adjust the index here.
  int offset = GetHeaderSize() + (kPointerSize * index);
  WRITE_FIELD(this, offset, value);
}
 
 
// Access fast-case object properties at index. The use of these routines
// is needed to correctly distinguish between properties stored in-object and
// properties stored in the properties array.
Object* JSObject::RawFastPropertyAt(FieldIndex index) {
  if (index.is_inobject()) {
    return READ_FIELD(this, index.offset());
  } else {
    return properties()->get(index.outobject_array_index());
  }
}
 
 
void JSObject::FastPropertyAtPut(FieldIndex index, Object* value) {
  if (index.is_inobject()) {
    int offset = index.offset();
    WRITE_FIELD(this, offset, value);
    WRITE_BARRIER(GetHeap(), this, offset, value);
  } else {
    properties()->set(index.outobject_array_index(), value);
  }
}
 
 
int JSObject::GetInObjectPropertyOffset(int index) {
  return map()->GetInObjectPropertyOffset(index);
}
 
 
Object* JSObject::InObjectPropertyAt(int index) {
  int offset = GetInObjectPropertyOffset(index);
  return READ_FIELD(this, offset);
}
 
 
Object* JSObject::InObjectPropertyAtPut(int index,
                                        Object* value,
                                        WriteBarrierMode mode) {
  // Adjust for the number of properties stored in the object.
  int offset = GetInObjectPropertyOffset(index);
  WRITE_FIELD(this, offset, value);
  CONDITIONAL_WRITE_BARRIER(GetHeap(), this, offset, value, mode);
  return value;
}
 
 
 
void JSObject::InitializeBody(Map* map,
                              Object* pre_allocated_value,
                              Object* filler_value) {
  DCHECK(!filler_value->IsHeapObject() ||
         !GetHeap()->InNewSpace(filler_value));
  DCHECK(!pre_allocated_value->IsHeapObject() ||
         !GetHeap()->InNewSpace(pre_allocated_value));
  int size = map->instance_size();
  int offset = kHeaderSize;
  if (filler_value != pre_allocated_value) {
    int pre_allocated = map->pre_allocated_property_fields();
    DCHECK(pre_allocated * kPointerSize + kHeaderSize <= size);
    for (int i = 0; i < pre_allocated; i++) {
      WRITE_FIELD(this, offset, pre_allocated_value);
      offset += kPointerSize;
    }
  }
  while (offset < size) {
    WRITE_FIELD(this, offset, filler_value);
    offset += kPointerSize;
  }
}
 
 
bool JSObject::HasFastProperties() {
  DCHECK(properties()->IsDictionary() == map()->is_dictionary_map());
  return !properties()->IsDictionary();
}
 
 
bool Map::TooManyFastProperties(StoreFromKeyed store_mode) {
  if (unused_property_fields() != 0) return false;
  if (is_prototype_map()) return false;
  int minimum = store_mode == CERTAINLY_NOT_STORE_FROM_KEYED ? 128 : 12;
  int limit = Max(minimum, inobject_properties());
  int external = NumberOfFields() - inobject_properties();
  return external > limit;
}
 
 
void Struct::InitializeBody(int object_size) {
  Object* value = GetHeap()->undefined_value();
  for (int offset = kHeaderSize; offset < object_size; offset += kPointerSize) {
    WRITE_FIELD(this, offset, value);
  }
}
 
 
bool Object::ToArrayIndex(uint32_t* index) {
  if (IsSmi()) {
    int value = Smi::cast(this)->value();
    if (value < 0) return false;
    *index = value;
    return true;
  }
  if (IsHeapNumber()) {
    double value = HeapNumber::cast(this)->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 >= static_cast<uint32_t>(str->length())) return false;
 
  return true;
}
 
 
void Object::VerifyApiCallResultType() {
#if ENABLE_EXTRA_CHECKS
  if (!(IsSmi() ||
        IsString() ||
        IsSymbol() ||
        IsSpecObject() ||
        IsHeapNumber() ||
        IsUndefined() ||
        IsTrue() ||
        IsFalse() ||
        IsNull())) {
    FATAL("API call returned invalid object");
  }
#endif  // ENABLE_EXTRA_CHECKS
}
 
 
Object* FixedArray::get(int index) {
  SLOW_DCHECK(index >= 0 && index < this->length());
  return READ_FIELD(this, kHeaderSize + index * kPointerSize);
}
 
 
Handle<Object> FixedArray::get(Handle<FixedArray> array, int index) {
  return handle(array->get(index), array->GetIsolate());
}
 
 
bool FixedArray::is_the_hole(int index) {
  return get(index) == GetHeap()->the_hole_value();
}
 
 
void FixedArray::set(int index, Smi* value) {
  DCHECK(map() != GetHeap()->fixed_cow_array_map());
  DCHECK(index >= 0 && index < this->length());
  DCHECK(reinterpret_cast<Object*>(value)->IsSmi());
  int offset = kHeaderSize + index * kPointerSize;
  WRITE_FIELD(this, offset, value);
}
 
 
void FixedArray::set(int index, Object* value) {
  DCHECK_NE(GetHeap()->fixed_cow_array_map(), map());
  DCHECK_EQ(FIXED_ARRAY_TYPE, map()->instance_type());
  DCHECK(index >= 0 && index < this->length());
  int offset = kHeaderSize + index * kPointerSize;
  WRITE_FIELD(this, offset, value);
  WRITE_BARRIER(GetHeap(), this, offset, value);
}
 
 
inline bool FixedDoubleArray::is_the_hole_nan(double value) {
  return bit_cast<uint64_t, double>(value) == kHoleNanInt64;
}
 
 
inline double FixedDoubleArray::hole_nan_as_double() {
  return bit_cast<double, uint64_t>(kHoleNanInt64);
}
 
 
inline double FixedDoubleArray::canonical_not_the_hole_nan_as_double() {
  DCHECK(bit_cast<uint64_t>(base::OS::nan_value()) != kHoleNanInt64);
  DCHECK((bit_cast<uint64_t>(base::OS::nan_value()) >> 32) != kHoleNanUpper32);
  return base::OS::nan_value();
}
 
 
double FixedDoubleArray::get_scalar(int index) {
  DCHECK(map() != GetHeap()->fixed_cow_array_map() &&
         map() != GetHeap()->fixed_array_map());
  DCHECK(index >= 0 && index < this->length());
  double result = READ_DOUBLE_FIELD(this, kHeaderSize + index * kDoubleSize);
  DCHECK(!is_the_hole_nan(result));
  return result;
}
 
int64_t FixedDoubleArray::get_representation(int index) {
  DCHECK(map() != GetHeap()->fixed_cow_array_map() &&
         map() != GetHeap()->fixed_array_map());
  DCHECK(index >= 0 && index < this->length());
  return READ_INT64_FIELD(this, kHeaderSize + index * kDoubleSize);
}
 
 
Handle<Object> FixedDoubleArray::get(Handle<FixedDoubleArray> array,
                                     int index) {
  if (array->is_the_hole(index)) {
    return array->GetIsolate()->factory()->the_hole_value();
  } else {
    return array->GetIsolate()->factory()->NewNumber(array->get_scalar(index));
  }
}
 
 
void FixedDoubleArray::set(int index, double value) {
  DCHECK(map() != GetHeap()->fixed_cow_array_map() &&
         map() != GetHeap()->fixed_array_map());
  int offset = kHeaderSize + index * kDoubleSize;
  if (std::isnan(value)) value = canonical_not_the_hole_nan_as_double();
  WRITE_DOUBLE_FIELD(this, offset, value);
}
 
 
void FixedDoubleArray::set_the_hole(int index) {
  DCHECK(map() != GetHeap()->fixed_cow_array_map() &&
         map() != GetHeap()->fixed_array_map());
  int offset = kHeaderSize + index * kDoubleSize;
  WRITE_DOUBLE_FIELD(this, offset, hole_nan_as_double());
}
 
 
bool FixedDoubleArray::is_the_hole(int index) {
  int offset = kHeaderSize + index * kDoubleSize;
  return is_the_hole_nan(READ_DOUBLE_FIELD(this, offset));
}
 
 
double* FixedDoubleArray::data_start() {
  return reinterpret_cast<double*>(FIELD_ADDR(this, kHeaderSize));
}
 
 
void FixedDoubleArray::FillWithHoles(int from, int to) {
  for (int i = from; i < to; i++) {
    set_the_hole(i);
  }
}
 
 
void ConstantPoolArray::NumberOfEntries::increment(Type type) {
  DCHECK(type < NUMBER_OF_TYPES);
  element_counts_[type]++;
}
 
 
int ConstantPoolArray::NumberOfEntries::equals(
    const ConstantPoolArray::NumberOfEntries& other) const {
  for (int i = 0; i < NUMBER_OF_TYPES; i++) {
    if (element_counts_[i] != other.element_counts_[i]) return false;
  }
  return true;
}
 
 
bool ConstantPoolArray::NumberOfEntries::is_empty() const {
  return total_count() == 0;
}
 
 
int ConstantPoolArray::NumberOfEntries::count_of(Type type) const {
  DCHECK(type < NUMBER_OF_TYPES);
  return element_counts_[type];
}
 
 
int ConstantPoolArray::NumberOfEntries::base_of(Type type) const {
  int base = 0;
  DCHECK(type < NUMBER_OF_TYPES);
  for (int i = 0; i < type; i++) {
    base += element_counts_[i];
  }
  return base;
}
 
 
int ConstantPoolArray::NumberOfEntries::total_count() const {
  int count = 0;
  for (int i = 0; i < NUMBER_OF_TYPES; i++) {
    count += element_counts_[i];
  }
  return count;
}
 
 
int ConstantPoolArray::NumberOfEntries::are_in_range(int min, int max) const {
  for (int i = FIRST_TYPE; i < NUMBER_OF_TYPES; i++) {
    if (element_counts_[i] < min || element_counts_[i] > max) {
      return false;
    }
  }
  return true;
}
 
 
int ConstantPoolArray::Iterator::next_index() {
  DCHECK(!is_finished());
  int ret = next_index_++;
  update_section();
  return ret;
}
 
 
bool ConstantPoolArray::Iterator::is_finished() {
  return next_index_ > array_->last_index(type_, final_section_);
}
 
 
void ConstantPoolArray::Iterator::update_section() {
  if (next_index_ > array_->last_index(type_, current_section_) &&
      current_section_ != final_section_) {
    DCHECK(final_section_ == EXTENDED_SECTION);
    current_section_ = EXTENDED_SECTION;
    next_index_ = array_->first_index(type_, EXTENDED_SECTION);
  }
}
 
 
bool ConstantPoolArray::is_extended_layout() {
  uint32_t small_layout_1 = READ_UINT32_FIELD(this, kSmallLayout1Offset);
  return IsExtendedField::decode(small_layout_1);
}
 
 
ConstantPoolArray::LayoutSection ConstantPoolArray::final_section() {
  return is_extended_layout() ? EXTENDED_SECTION : SMALL_SECTION;
}
 
 
int ConstantPoolArray::first_extended_section_index() {
  DCHECK(is_extended_layout());
  uint32_t small_layout_2 = READ_UINT32_FIELD(this, kSmallLayout2Offset);
  return TotalCountField::decode(small_layout_2);
}
 
 
int ConstantPoolArray::get_extended_section_header_offset() {
  return RoundUp(SizeFor(NumberOfEntries(this, SMALL_SECTION)), kInt64Size);
}
 
 
ConstantPoolArray::WeakObjectState ConstantPoolArray::get_weak_object_state() {
  uint32_t small_layout_2 = READ_UINT32_FIELD(this, kSmallLayout2Offset);
  return WeakObjectStateField::decode(small_layout_2);
}
 
 
void ConstantPoolArray::set_weak_object_state(
      ConstantPoolArray::WeakObjectState state) {
  uint32_t small_layout_2 = READ_UINT32_FIELD(this, kSmallLayout2Offset);
  small_layout_2 = WeakObjectStateField::update(small_layout_2, state);
  WRITE_INT32_FIELD(this, kSmallLayout2Offset, small_layout_2);
}
 
 
int ConstantPoolArray::first_index(Type type, LayoutSection section) {
  int index = 0;
  if (section == EXTENDED_SECTION) {
    DCHECK(is_extended_layout());
    index += first_extended_section_index();
  }
 
  for (Type type_iter = FIRST_TYPE; type_iter < type;
       type_iter = next_type(type_iter)) {
    index += number_of_entries(type_iter, section);
  }
 
  return index;
}
 
 
int ConstantPoolArray::last_index(Type type, LayoutSection section) {
  return first_index(type, section) + number_of_entries(type, section) - 1;
}
 
 
int ConstantPoolArray::number_of_entries(Type type, LayoutSection section) {
  if (section == SMALL_SECTION) {
    uint32_t small_layout_1 = READ_UINT32_FIELD(this, kSmallLayout1Offset);
    uint32_t small_layout_2 = READ_UINT32_FIELD(this, kSmallLayout2Offset);
    switch (type) {
      case INT64:
        return Int64CountField::decode(small_layout_1);
      case CODE_PTR:
        return CodePtrCountField::decode(small_layout_1);
      case HEAP_PTR:
        return HeapPtrCountField::decode(small_layout_1);
      case INT32:
        return Int32CountField::decode(small_layout_2);
      default:
        UNREACHABLE();
        return 0;
    }
  } else {
    DCHECK(section == EXTENDED_SECTION && is_extended_layout());
    int offset = get_extended_section_header_offset();
    switch (type) {
      case INT64:
        offset += kExtendedInt64CountOffset;
        break;
      case CODE_PTR:
        offset += kExtendedCodePtrCountOffset;
        break;
      case HEAP_PTR:
        offset += kExtendedHeapPtrCountOffset;
        break;
      case INT32:
        offset += kExtendedInt32CountOffset;
        break;
      default:
        UNREACHABLE();
    }
    return READ_INT_FIELD(this, offset);
  }
}
 
 
bool ConstantPoolArray::offset_is_type(int offset, Type type) {
  return (offset >= OffsetOfElementAt(first_index(type, SMALL_SECTION)) &&
          offset <= OffsetOfElementAt(last_index(type, SMALL_SECTION))) ||
         (is_extended_layout() &&
          offset >= OffsetOfElementAt(first_index(type, EXTENDED_SECTION)) &&
          offset <= OffsetOfElementAt(last_index(type, EXTENDED_SECTION)));
}
 
 
ConstantPoolArray::Type ConstantPoolArray::get_type(int index) {
  LayoutSection section;
  if (is_extended_layout() && index >= first_extended_section_index()) {
    section = EXTENDED_SECTION;
  } else {
    section = SMALL_SECTION;
  }
 
  Type type = FIRST_TYPE;
  while (index > last_index(type, section)) {
    type = next_type(type);
  }
  DCHECK(type <= LAST_TYPE);
  return type;
}
 
 
int64_t ConstantPoolArray::get_int64_entry(int index) {
  DCHECK(map() == GetHeap()->constant_pool_array_map());
  DCHECK(get_type(index) == INT64);
  return READ_INT64_FIELD(this, OffsetOfElementAt(index));
}
 
 
double ConstantPoolArray::get_int64_entry_as_double(int index) {
  STATIC_ASSERT(kDoubleSize == kInt64Size);
  DCHECK(map() == GetHeap()->constant_pool_array_map());
  DCHECK(get_type(index) == INT64);
  return READ_DOUBLE_FIELD(this, OffsetOfElementAt(index));
}
 
 
Address ConstantPoolArray::get_code_ptr_entry(int index) {
  DCHECK(map() == GetHeap()->constant_pool_array_map());
  DCHECK(get_type(index) == CODE_PTR);
  return reinterpret_cast<Address>(READ_FIELD(this, OffsetOfElementAt(index)));
}
 
 
Object* ConstantPoolArray::get_heap_ptr_entry(int index) {
  DCHECK(map() == GetHeap()->constant_pool_array_map());
  DCHECK(get_type(index) == HEAP_PTR);
  return READ_FIELD(this, OffsetOfElementAt(index));
}
 
 
int32_t ConstantPoolArray::get_int32_entry(int index) {
  DCHECK(map() == GetHeap()->constant_pool_array_map());
  DCHECK(get_type(index) == INT32);
  return READ_INT32_FIELD(this, OffsetOfElementAt(index));
}
 
 
void ConstantPoolArray::set(int index, int64_t value) {
  DCHECK(map() == GetHeap()->constant_pool_array_map());
  DCHECK(get_type(index) == INT64);
  WRITE_INT64_FIELD(this, OffsetOfElementAt(index), value);
}
 
 
void ConstantPoolArray::set(int index, double value) {
  STATIC_ASSERT(kDoubleSize == kInt64Size);
  DCHECK(map() == GetHeap()->constant_pool_array_map());
  DCHECK(get_type(index) == INT64);
  WRITE_DOUBLE_FIELD(this, OffsetOfElementAt(index), value);
}
 
 
void ConstantPoolArray::set(int index, Address value) {
  DCHECK(map() == GetHeap()->constant_pool_array_map());
  DCHECK(get_type(index) == CODE_PTR);
  WRITE_FIELD(this, OffsetOfElementAt(index), reinterpret_cast<Object*>(value));
}
 
 
void ConstantPoolArray::set(int index, Object* value) {
  DCHECK(map() == GetHeap()->constant_pool_array_map());
  DCHECK(!GetHeap()->InNewSpace(value));
  DCHECK(get_type(index) == HEAP_PTR);
  WRITE_FIELD(this, OffsetOfElementAt(index), value);
  WRITE_BARRIER(GetHeap(), this, OffsetOfElementAt(index), value);
}
 
 
void ConstantPoolArray::set(int index, int32_t value) {
  DCHECK(map() == GetHeap()->constant_pool_array_map());
  DCHECK(get_type(index) == INT32);
  WRITE_INT32_FIELD(this, OffsetOfElementAt(index), value);
}
 
 
void ConstantPoolArray::set_at_offset(int offset, int32_t value) {
  DCHECK(map() == GetHeap()->constant_pool_array_map());
  DCHECK(offset_is_type(offset, INT32));
  WRITE_INT32_FIELD(this, offset, value);
}
 
 
void ConstantPoolArray::set_at_offset(int offset, int64_t value) {
  DCHECK(map() == GetHeap()->constant_pool_array_map());
  DCHECK(offset_is_type(offset, INT64));
  WRITE_INT64_FIELD(this, offset, value);
}
 
 
void ConstantPoolArray::set_at_offset(int offset, double value) {
  DCHECK(map() == GetHeap()->constant_pool_array_map());
  DCHECK(offset_is_type(offset, INT64));
  WRITE_DOUBLE_FIELD(this, offset, value);
}
 
 
void ConstantPoolArray::set_at_offset(int offset, Address value) {
  DCHECK(map() == GetHeap()->constant_pool_array_map());
  DCHECK(offset_is_type(offset, CODE_PTR));
  WRITE_FIELD(this, offset, reinterpret_cast<Object*>(value));
  WRITE_BARRIER(GetHeap(), this, offset, reinterpret_cast<Object*>(value));
}
 
 
void ConstantPoolArray::set_at_offset(int offset, Object* value) {
  DCHECK(map() == GetHeap()->constant_pool_array_map());
  DCHECK(!GetHeap()->InNewSpace(value));
  DCHECK(offset_is_type(offset, HEAP_PTR));
  WRITE_FIELD(this, offset, value);
  WRITE_BARRIER(GetHeap(), this, offset, value);
}
 
 
void ConstantPoolArray::Init(const NumberOfEntries& small) {
  uint32_t small_layout_1 =
      Int64CountField::encode(small.count_of(INT64)) |
      CodePtrCountField::encode(small.count_of(CODE_PTR)) |
      HeapPtrCountField::encode(small.count_of(HEAP_PTR)) |
      IsExtendedField::encode(false);
  uint32_t small_layout_2 =
      Int32CountField::encode(small.count_of(INT32)) |
      TotalCountField::encode(small.total_count()) |
      WeakObjectStateField::encode(NO_WEAK_OBJECTS);
  WRITE_UINT32_FIELD(this, kSmallLayout1Offset, small_layout_1);
  WRITE_UINT32_FIELD(this, kSmallLayout2Offset, small_layout_2);
  if (kHeaderSize != kFirstEntryOffset) {
    DCHECK(kFirstEntryOffset - kHeaderSize == kInt32Size);
    WRITE_UINT32_FIELD(this, kHeaderSize, 0);  // Zero out header padding.
  }
}
 
 
void ConstantPoolArray::InitExtended(const NumberOfEntries& small,
                                     const NumberOfEntries& extended) {
  // Initialize small layout fields first.
  Init(small);
 
  // Set is_extended_layout field.
  uint32_t small_layout_1 = READ_UINT32_FIELD(this, kSmallLayout1Offset);
  small_layout_1 = IsExtendedField::update(small_layout_1, true);
  WRITE_INT32_FIELD(this, kSmallLayout1Offset, small_layout_1);
 
  // Initialize the extended layout fields.
  int extended_header_offset = get_extended_section_header_offset();
  WRITE_INT_FIELD(this, extended_header_offset + kExtendedInt64CountOffset,
      extended.count_of(INT64));
  WRITE_INT_FIELD(this, extended_header_offset + kExtendedCodePtrCountOffset,
      extended.count_of(CODE_PTR));
  WRITE_INT_FIELD(this, extended_header_offset + kExtendedHeapPtrCountOffset,
      extended.count_of(HEAP_PTR));
  WRITE_INT_FIELD(this, extended_header_offset + kExtendedInt32CountOffset,
      extended.count_of(INT32));
}
 
 
int ConstantPoolArray::size() {
  NumberOfEntries small(this, SMALL_SECTION);
  if (!is_extended_layout()) {
    return SizeFor(small);
  } else {
    NumberOfEntries extended(this, EXTENDED_SECTION);
    return SizeForExtended(small, extended);
  }
}
 
 
int ConstantPoolArray::length() {
  uint32_t small_layout_2 = READ_UINT32_FIELD(this, kSmallLayout2Offset);
  int length = TotalCountField::decode(small_layout_2);
  if (is_extended_layout()) {
    length += number_of_entries(INT64, EXTENDED_SECTION) +
              number_of_entries(CODE_PTR, EXTENDED_SECTION) +
              number_of_entries(HEAP_PTR, EXTENDED_SECTION) +
              number_of_entries(INT32, EXTENDED_SECTION);
  }
  return length;
}
 
 
WriteBarrierMode HeapObject::GetWriteBarrierMode(
    const DisallowHeapAllocation& promise) {
  Heap* heap = GetHeap();
  if (heap->incremental_marking()->IsMarking()) return UPDATE_WRITE_BARRIER;
  if (heap->InNewSpace(this)) return SKIP_WRITE_BARRIER;
  return UPDATE_WRITE_BARRIER;
}
 
 
void FixedArray::set(int index,
                     Object* value,
                     WriteBarrierMode mode) {
  DCHECK(map() != GetHeap()->fixed_cow_array_map());
  DCHECK(index >= 0 && index < this->length());
  int offset = kHeaderSize + index * kPointerSize;
  WRITE_FIELD(this, offset, value);
  CONDITIONAL_WRITE_BARRIER(GetHeap(), this, offset, value, mode);
}
 
 
void FixedArray::NoIncrementalWriteBarrierSet(FixedArray* array,
                                              int index,
                                              Object* value) {
  DCHECK(array->map() != array->GetHeap()->fixed_cow_array_map());
  DCHECK(index >= 0 && index < array->length());
  int offset = kHeaderSize + index * kPointerSize;
  WRITE_FIELD(array, offset, value);
  Heap* heap = array->GetHeap();
  if (heap->InNewSpace(value)) {
    heap->RecordWrite(array->address(), offset);
  }
}
 
 
void FixedArray::NoWriteBarrierSet(FixedArray* array,
                                   int index,
                                   Object* value) {
  DCHECK(array->map() != array->GetHeap()->fixed_cow_array_map());
  DCHECK(index >= 0 && index < array->length());
  DCHECK(!array->GetHeap()->InNewSpace(value));
  WRITE_FIELD(array, kHeaderSize + index * kPointerSize, value);
}
 
 
void FixedArray::set_undefined(int index) {
  DCHECK(map() != GetHeap()->fixed_cow_array_map());
  DCHECK(index >= 0 && index < this->length());
  DCHECK(!GetHeap()->InNewSpace(GetHeap()->undefined_value()));
  WRITE_FIELD(this,
              kHeaderSize + index * kPointerSize,
              GetHeap()->undefined_value());
}
 
 
void FixedArray::set_null(int index) {
  DCHECK(index >= 0 && index < this->length());
  DCHECK(!GetHeap()->InNewSpace(GetHeap()->null_value()));
  WRITE_FIELD(this,
              kHeaderSize + index * kPointerSize,
              GetHeap()->null_value());
}
 
 
void FixedArray::set_the_hole(int index) {
  DCHECK(map() != GetHeap()->fixed_cow_array_map());
  DCHECK(index >= 0 && index < this->length());
  DCHECK(!GetHeap()->InNewSpace(GetHeap()->the_hole_value()));
  WRITE_FIELD(this,
              kHeaderSize + index * kPointerSize,
              GetHeap()->the_hole_value());
}
 
 
void FixedArray::FillWithHoles(int from, int to) {
  for (int i = from; i < to; i++) {
    set_the_hole(i);
  }
}
 
 
Object** FixedArray::data_start() {
  return HeapObject::RawField(this, kHeaderSize);
}
 
 
bool DescriptorArray::IsEmpty() {
  DCHECK(length() >= kFirstIndex ||
         this == GetHeap()->empty_descriptor_array());
  return length() < kFirstIndex;
}
 
 
void DescriptorArray::SetNumberOfDescriptors(int number_of_descriptors) {
  WRITE_FIELD(
      this, kDescriptorLengthOffset, Smi::FromInt(number_of_descriptors));
}
 
 
// Perform a binary search in a fixed array. Low and high are entry indices. If
// there are three entries in this array it should be called with low=0 and
// high=2.
template<SearchMode search_mode, typename T>
int BinarySearch(T* array, Name* name, int low, int high, int valid_entries) {
  uint32_t hash = name->Hash();
  int limit = high;
 
  DCHECK(low <= high);
 
  while (low != high) {
    int mid = (low + high) / 2;
    Name* mid_name = array->GetSortedKey(mid);
    uint32_t mid_hash = mid_name->Hash();
 
    if (mid_hash >= hash) {
      high = mid;
    } else {
      low = mid + 1;
    }
  }
 
  for (; low <= limit; ++low) {
    int sort_index = array->GetSortedKeyIndex(low);
    Name* entry = array->GetKey(sort_index);
    if (entry->Hash() != hash) break;
    if (entry->Equals(name)) {
      if (search_mode == ALL_ENTRIES || sort_index < valid_entries) {
        return sort_index;
      }
      return T::kNotFound;
    }
  }
 
  return T::kNotFound;
}
 
 
// Perform a linear search in this fixed array. len is the number of entry
// indices that are valid.
template<SearchMode search_mode, typename T>
int LinearSearch(T* array, Name* name, int len, int valid_entries) {
  uint32_t hash = name->Hash();
  if (search_mode == ALL_ENTRIES) {
    for (int number = 0; number < len; number++) {
      int sorted_index = array->GetSortedKeyIndex(number);
      Name* entry = array->GetKey(sorted_index);
      uint32_t current_hash = entry->Hash();
      if (current_hash > hash) break;
      if (current_hash == hash && entry->Equals(name)) return sorted_index;
    }
  } else {
    DCHECK(len >= valid_entries);
    for (int number = 0; number < valid_entries; number++) {
      Name* entry = array->GetKey(number);
      uint32_t current_hash = entry->Hash();
      if (current_hash == hash && entry->Equals(name)) return number;
    }
  }
  return T::kNotFound;
}
 
 
template<SearchMode search_mode, typename T>
int Search(T* array, Name* name, int valid_entries) {
  if (search_mode == VALID_ENTRIES) {
    SLOW_DCHECK(array->IsSortedNoDuplicates(valid_entries));
  } else {
    SLOW_DCHECK(array->IsSortedNoDuplicates());
  }
 
  int nof = array->number_of_entries();
  if (nof == 0) return T::kNotFound;
 
  // Fast case: do linear search for small arrays.
  const int kMaxElementsForLinearSearch = 8;
  if ((search_mode == ALL_ENTRIES &&
       nof <= kMaxElementsForLinearSearch) ||
      (search_mode == VALID_ENTRIES &&
       valid_entries <= (kMaxElementsForLinearSearch * 3))) {
    return LinearSearch<search_mode>(array, name, nof, valid_entries);
  }
 
  // Slow case: perform binary search.
  return BinarySearch<search_mode>(array, name, 0, nof - 1, valid_entries);
}
 
 
int DescriptorArray::Search(Name* name, int valid_descriptors) {
  return internal::Search<VALID_ENTRIES>(this, name, valid_descriptors);
}
 
 
int DescriptorArray::SearchWithCache(Name* name, Map* map) {
  int number_of_own_descriptors = map->NumberOfOwnDescriptors();
  if (number_of_own_descriptors == 0) return kNotFound;
 
  DescriptorLookupCache* cache = GetIsolate()->descriptor_lookup_cache();
  int number = cache->Lookup(map, name);
 
  if (number == DescriptorLookupCache::kAbsent) {
    number = Search(name, number_of_own_descriptors);
    cache->Update(map, name, number);
  }
 
  return number;
}
 
 
PropertyDetails Map::GetLastDescriptorDetails() {
  return instance_descriptors()->GetDetails(LastAdded());
}
 
 
void Map::LookupDescriptor(JSObject* holder,
                           Name* name,
                           LookupResult* result) {
  DescriptorArray* descriptors = this->instance_descriptors();
  int number = descriptors->SearchWithCache(name, this);
  if (number == DescriptorArray::kNotFound) return result->NotFound();
  result->DescriptorResult(holder, descriptors->GetDetails(number), number);
}
 
 
void Map::LookupTransition(JSObject* holder,
                           Name* name,
                           LookupResult* result) {
  int transition_index = this->SearchTransition(name);
  if (transition_index == TransitionArray::kNotFound) return result->NotFound();
  result->TransitionResult(holder, this->GetTransition(transition_index));
}
 
 
FixedArrayBase* Map::GetInitialElements() {
  if (has_fast_smi_or_object_elements() ||
      has_fast_double_elements()) {
    DCHECK(!GetHeap()->InNewSpace(GetHeap()->empty_fixed_array()));
    return GetHeap()->empty_fixed_array();
  } else if (has_external_array_elements()) {
    ExternalArray* empty_array = GetHeap()->EmptyExternalArrayForMap(this);
    DCHECK(!GetHeap()->InNewSpace(empty_array));
    return empty_array;
  } else if (has_fixed_typed_array_elements()) {
    FixedTypedArrayBase* empty_array =
      GetHeap()->EmptyFixedTypedArrayForMap(this);
    DCHECK(!GetHeap()->InNewSpace(empty_array));
    return empty_array;
  } else {
    UNREACHABLE();
  }
  return NULL;
}
 
 
Object** DescriptorArray::GetKeySlot(int descriptor_number) {
  DCHECK(descriptor_number < number_of_descriptors());
  return RawFieldOfElementAt(ToKeyIndex(descriptor_number));
}
 
 
Object** DescriptorArray::GetDescriptorStartSlot(int descriptor_number) {
  return GetKeySlot(descriptor_number);
}
 
 
Object** DescriptorArray::GetDescriptorEndSlot(int descriptor_number) {
  return GetValueSlot(descriptor_number - 1) + 1;
}
 
 
Name* DescriptorArray::GetKey(int descriptor_number) {
  DCHECK(descriptor_number < number_of_descriptors());
  return Name::cast(get(ToKeyIndex(descriptor_number)));
}
 
 
int DescriptorArray::GetSortedKeyIndex(int descriptor_number) {
  return GetDetails(descriptor_number).pointer();
}
 
 
Name* DescriptorArray::GetSortedKey(int descriptor_number) {
  return GetKey(GetSortedKeyIndex(descriptor_number));
}
 
 
void DescriptorArray::SetSortedKey(int descriptor_index, int pointer) {
  PropertyDetails details = GetDetails(descriptor_index);
  set(ToDetailsIndex(descriptor_index), details.set_pointer(pointer).AsSmi());
}
 
 
void DescriptorArray::SetRepresentation(int descriptor_index,
                                        Representation representation) {
  DCHECK(!representation.IsNone());
  PropertyDetails details = GetDetails(descriptor_index);
  set(ToDetailsIndex(descriptor_index),
      details.CopyWithRepresentation(representation).AsSmi());
}
 
 
Object** DescriptorArray::GetValueSlot(int descriptor_number) {
  DCHECK(descriptor_number < number_of_descriptors());
  return RawFieldOfElementAt(ToValueIndex(descriptor_number));
}
 
 
int DescriptorArray::GetValueOffset(int descriptor_number) {
  return OffsetOfElementAt(ToValueIndex(descriptor_number));
}
 
 
Object* DescriptorArray::GetValue(int descriptor_number) {
  DCHECK(descriptor_number < number_of_descriptors());
  return get(ToValueIndex(descriptor_number));
}
 
 
void DescriptorArray::SetValue(int descriptor_index, Object* value) {
  set(ToValueIndex(descriptor_index), value);
}
 
 
PropertyDetails DescriptorArray::GetDetails(int descriptor_number) {
  DCHECK(descriptor_number < number_of_descriptors());
  Object* details = get(ToDetailsIndex(descriptor_number));
  return PropertyDetails(Smi::cast(details));
}
 
 
PropertyType DescriptorArray::GetType(int descriptor_number) {
  return GetDetails(descriptor_number).type();
}
 
 
int DescriptorArray::GetFieldIndex(int descriptor_number) {
  DCHECK(GetDetails(descriptor_number).type() == FIELD);
  return GetDetails(descriptor_number).field_index();
}
 
 
HeapType* DescriptorArray::GetFieldType(int descriptor_number) {
  DCHECK(GetDetails(descriptor_number).type() == FIELD);
  return HeapType::cast(GetValue(descriptor_number));
}
 
 
Object* DescriptorArray::GetConstant(int descriptor_number) {
  return GetValue(descriptor_number);
}
 
 
Object* DescriptorArray::GetCallbacksObject(int descriptor_number) {
  DCHECK(GetType(descriptor_number) == CALLBACKS);
  return GetValue(descriptor_number);
}
 
 
AccessorDescriptor* DescriptorArray::GetCallbacks(int descriptor_number) {
  DCHECK(GetType(descriptor_number) == CALLBACKS);
  Foreign* p = Foreign::cast(GetCallbacksObject(descriptor_number));
  return reinterpret_cast<AccessorDescriptor*>(p->foreign_address());
}
 
 
void DescriptorArray::Get(int descriptor_number, Descriptor* desc) {
  desc->Init(handle(GetKey(descriptor_number), GetIsolate()),
             handle(GetValue(descriptor_number), GetIsolate()),
             GetDetails(descriptor_number));
}
 
 
void DescriptorArray::Set(int descriptor_number,
                          Descriptor* desc,
                          const WhitenessWitness&) {
  // Range check.
  DCHECK(descriptor_number < number_of_descriptors());
 
  NoIncrementalWriteBarrierSet(this,
                               ToKeyIndex(descriptor_number),
                               *desc->GetKey());
  NoIncrementalWriteBarrierSet(this,
                               ToValueIndex(descriptor_number),
                               *desc->GetValue());
  NoIncrementalWriteBarrierSet(this,
                               ToDetailsIndex(descriptor_number),
                               desc->GetDetails().AsSmi());
}
 
 
void DescriptorArray::Set(int descriptor_number, Descriptor* desc) {
  // Range check.
  DCHECK(descriptor_number < number_of_descriptors());
 
  set(ToKeyIndex(descriptor_number), *desc->GetKey());
  set(ToValueIndex(descriptor_number), *desc->GetValue());
  set(ToDetailsIndex(descriptor_number), desc->GetDetails().AsSmi());
}
 
 
void DescriptorArray::Append(Descriptor* desc) {
  DisallowHeapAllocation no_gc;
  int descriptor_number = number_of_descriptors();
  SetNumberOfDescriptors(descriptor_number + 1);
  Set(descriptor_number, desc);
 
  uint32_t hash = desc->GetKey()->Hash();
 
  int insertion;
 
  for (insertion = descriptor_number; insertion > 0; --insertion) {
    Name* key = GetSortedKey(insertion - 1);
    if (key->Hash() <= hash) break;
    SetSortedKey(insertion, GetSortedKeyIndex(insertion - 1));
  }
 
  SetSortedKey(insertion, descriptor_number);
}
 
 
void DescriptorArray::SwapSortedKeys(int first, int second) {
  int first_key = GetSortedKeyIndex(first);
  SetSortedKey(first, GetSortedKeyIndex(second));
  SetSortedKey(second, first_key);
}
 
 
DescriptorArray::WhitenessWitness::WhitenessWitness(DescriptorArray* array)
    : marking_(array->GetHeap()->incremental_marking()) {
  marking_->EnterNoMarkingScope();
  DCHECK(!marking_->IsMarking() ||
         Marking::Color(array) == Marking::WHITE_OBJECT);
}
 
 
DescriptorArray::WhitenessWitness::~WhitenessWitness() {
  marking_->LeaveNoMarkingScope();
}
 
 
template<typename Derived, typename Shape, typename Key>
int HashTable<Derived, Shape, Key>::ComputeCapacity(int at_least_space_for) {
  const int kMinCapacity = 32;
  int capacity = base::bits::RoundUpToPowerOfTwo32(at_least_space_for * 2);
  if (capacity < kMinCapacity) {
    capacity = kMinCapacity;  // Guarantee min capacity.
  }
  return capacity;
}
 
 
template<typename Derived, typename Shape, typename Key>
int HashTable<Derived, Shape, Key>::FindEntry(Key key) {
  return FindEntry(GetIsolate(), key);
}
 
 
// Find entry for key otherwise return kNotFound.
template<typename Derived, typename Shape, typename Key>
int HashTable<Derived, Shape, Key>::FindEntry(Isolate* isolate, Key key) {
  uint32_t capacity = Capacity();
  uint32_t entry = FirstProbe(HashTable::Hash(key), capacity);
  uint32_t count = 1;
  // EnsureCapacity will guarantee the hash table is never full.
  while (true) {
    Object* element = KeyAt(entry);
    // Empty entry. Uses raw unchecked accessors because it is called by the
    // string table during bootstrapping.
    if (element == isolate->heap()->raw_unchecked_undefined_value()) break;
    if (element != isolate->heap()->raw_unchecked_the_hole_value() &&
        Shape::IsMatch(key, element)) return entry;
    entry = NextProbe(entry, count++, capacity);
  }
  return kNotFound;
}
 
 
bool SeededNumberDictionary::requires_slow_elements() {
  Object* max_index_object = get(kMaxNumberKeyIndex);
  if (!max_index_object->IsSmi()) return false;
  return 0 !=
      (Smi::cast(max_index_object)->value() & kRequiresSlowElementsMask);
}
 
uint32_t SeededNumberDictionary::max_number_key() {
  DCHECK(!requires_slow_elements());
  Object* max_index_object = get(kMaxNumberKeyIndex);
  if (!max_index_object->IsSmi()) return 0;
  uint32_t value = static_cast<uint32_t>(Smi::cast(max_index_object)->value());
  return value >> kRequiresSlowElementsTagSize;
}
 
void SeededNumberDictionary::set_requires_slow_elements() {
  set(kMaxNumberKeyIndex, Smi::FromInt(kRequiresSlowElementsMask));
}
 
 
// ------------------------------------
// Cast operations
 
 
CAST_ACCESSOR(AccessorInfo)
CAST_ACCESSOR(ByteArray)
CAST_ACCESSOR(Cell)
CAST_ACCESSOR(Code)
CAST_ACCESSOR(CodeCacheHashTable)
CAST_ACCESSOR(CompilationCacheTable)
CAST_ACCESSOR(ConsString)
CAST_ACCESSOR(ConstantPoolArray)
CAST_ACCESSOR(DeoptimizationInputData)
CAST_ACCESSOR(DeoptimizationOutputData)
CAST_ACCESSOR(DependentCode)
CAST_ACCESSOR(DescriptorArray)
CAST_ACCESSOR(ExternalArray)
CAST_ACCESSOR(ExternalOneByteString)
CAST_ACCESSOR(ExternalFloat32Array)
CAST_ACCESSOR(ExternalFloat64Array)
CAST_ACCESSOR(ExternalInt16Array)
CAST_ACCESSOR(ExternalInt32Array)
CAST_ACCESSOR(ExternalInt8Array)
CAST_ACCESSOR(ExternalString)
CAST_ACCESSOR(ExternalTwoByteString)
CAST_ACCESSOR(ExternalUint16Array)
CAST_ACCESSOR(ExternalUint32Array)
CAST_ACCESSOR(ExternalUint8Array)
CAST_ACCESSOR(ExternalUint8ClampedArray)
CAST_ACCESSOR(FixedArray)
CAST_ACCESSOR(FixedArrayBase)
CAST_ACCESSOR(FixedDoubleArray)
CAST_ACCESSOR(FixedTypedArrayBase)
CAST_ACCESSOR(Foreign)
CAST_ACCESSOR(FreeSpace)
CAST_ACCESSOR(GlobalObject)
CAST_ACCESSOR(HeapObject)
CAST_ACCESSOR(JSArray)
CAST_ACCESSOR(JSArrayBuffer)
CAST_ACCESSOR(JSArrayBufferView)
CAST_ACCESSOR(JSBuiltinsObject)
CAST_ACCESSOR(JSDataView)
CAST_ACCESSOR(JSDate)
CAST_ACCESSOR(JSFunction)
CAST_ACCESSOR(JSFunctionProxy)
CAST_ACCESSOR(JSFunctionResultCache)
CAST_ACCESSOR(JSGeneratorObject)
CAST_ACCESSOR(JSGlobalObject)
CAST_ACCESSOR(JSGlobalProxy)
CAST_ACCESSOR(JSMap)
CAST_ACCESSOR(JSMapIterator)
CAST_ACCESSOR(JSMessageObject)
CAST_ACCESSOR(JSModule)
CAST_ACCESSOR(JSObject)
CAST_ACCESSOR(JSProxy)
CAST_ACCESSOR(JSReceiver)
CAST_ACCESSOR(JSRegExp)
CAST_ACCESSOR(JSSet)
CAST_ACCESSOR(JSSetIterator)
CAST_ACCESSOR(JSTypedArray)
CAST_ACCESSOR(JSValue)
CAST_ACCESSOR(JSWeakMap)
CAST_ACCESSOR(JSWeakSet)
CAST_ACCESSOR(Map)
CAST_ACCESSOR(MapCache)
CAST_ACCESSOR(Name)
CAST_ACCESSOR(NameDictionary)
CAST_ACCESSOR(NormalizedMapCache)
CAST_ACCESSOR(Object)
CAST_ACCESSOR(ObjectHashTable)
CAST_ACCESSOR(Oddball)
CAST_ACCESSOR(OrderedHashMap)
CAST_ACCESSOR(OrderedHashSet)
CAST_ACCESSOR(PolymorphicCodeCacheHashTable)
CAST_ACCESSOR(PropertyCell)
CAST_ACCESSOR(ScopeInfo)
CAST_ACCESSOR(SeededNumberDictionary)
CAST_ACCESSOR(SeqOneByteString)
CAST_ACCESSOR(SeqString)
CAST_ACCESSOR(SeqTwoByteString)
CAST_ACCESSOR(SharedFunctionInfo)
CAST_ACCESSOR(SlicedString)
CAST_ACCESSOR(Smi)
CAST_ACCESSOR(String)
CAST_ACCESSOR(StringTable)
CAST_ACCESSOR(Struct)
CAST_ACCESSOR(Symbol)
CAST_ACCESSOR(UnseededNumberDictionary)
CAST_ACCESSOR(WeakHashTable)
 
 
template <class Traits>
FixedTypedArray<Traits>* FixedTypedArray<Traits>::cast(Object* object) {
  SLOW_DCHECK(object->IsHeapObject() &&
              HeapObject::cast(object)->map()->instance_type() ==
              Traits::kInstanceType);
  return reinterpret_cast<FixedTypedArray<Traits>*>(object);
}
 
 
template <class Traits>
const FixedTypedArray<Traits>*
FixedTypedArray<Traits>::cast(const Object* object) {
  SLOW_DCHECK(object->IsHeapObject() &&
              HeapObject::cast(object)->map()->instance_type() ==
              Traits::kInstanceType);
  return reinterpret_cast<FixedTypedArray<Traits>*>(object);
}
 
 
#define MAKE_STRUCT_CAST(NAME, Name, name) CAST_ACCESSOR(Name)
  STRUCT_LIST(MAKE_STRUCT_CAST)
#undef MAKE_STRUCT_CAST
 
 
template <typename Derived, typename Shape, typename Key>
HashTable<Derived, Shape, Key>*
HashTable<Derived, Shape, Key>::cast(Object* obj) {
  SLOW_DCHECK(obj->IsHashTable());
  return reinterpret_cast<HashTable*>(obj);
}
 
 
template <typename Derived, typename Shape, typename Key>
const HashTable<Derived, Shape, Key>*
HashTable<Derived, Shape, Key>::cast(const Object* obj) {
  SLOW_DCHECK(obj->IsHashTable());
  return reinterpret_cast<const HashTable*>(obj);
}
 
 
SMI_ACCESSORS(FixedArrayBase, length, kLengthOffset)
SYNCHRONIZED_SMI_ACCESSORS(FixedArrayBase, length, kLengthOffset)
 
SMI_ACCESSORS(FreeSpace, size, kSizeOffset)
NOBARRIER_SMI_ACCESSORS(FreeSpace, size, kSizeOffset)
 
SMI_ACCESSORS(String, length, kLengthOffset)
SYNCHRONIZED_SMI_ACCESSORS(String, length, kLengthOffset)
 
 
uint32_t Name::hash_field() {
  return READ_UINT32_FIELD(this, kHashFieldOffset);
}
 
 
void Name::set_hash_field(uint32_t value) {
  WRITE_UINT32_FIELD(this, kHashFieldOffset, value);
#if V8_HOST_ARCH_64_BIT
  WRITE_UINT32_FIELD(this, kHashFieldOffset + kIntSize, 0);
#endif
}
 
 
bool Name::Equals(Name* other) {
  if (other == this) return true;
  if ((this->IsInternalizedString() && other->IsInternalizedString()) ||
      this->IsSymbol() || other->IsSymbol()) {
    return false;
  }
  return String::cast(this)->SlowEquals(String::cast(other));
}
 
 
bool Name::Equals(Handle<Name> one, Handle<Name> two) {
  if (one.is_identical_to(two)) return true;
  if ((one->IsInternalizedString() && two->IsInternalizedString()) ||
      one->IsSymbol() || two->IsSymbol()) {
    return false;
  }
  return String::SlowEquals(Handle<String>::cast(one),
                            Handle<String>::cast(two));
}
 
 
ACCESSORS(Symbol, name, Object, kNameOffset)
ACCESSORS(Symbol, flags, Smi, kFlagsOffset)
BOOL_ACCESSORS(Symbol, flags, is_private, kPrivateBit)
BOOL_ACCESSORS(Symbol, flags, is_own, kOwnBit)
 
 
bool String::Equals(String* other) {
  if (other == this) return true;
  if (this->IsInternalizedString() && other->IsInternalizedString()) {
    return false;
  }
  return SlowEquals(other);
}
 
 
bool String::Equals(Handle<String> one, Handle<String> two) {
  if (one.is_identical_to(two)) return true;
  if (one->IsInternalizedString() && two->IsInternalizedString()) {
    return false;
  }
  return SlowEquals(one, two);
}
 
 
Handle<String> String::Flatten(Handle<String> string, PretenureFlag pretenure) {
  if (!string->IsConsString()) return string;
  Handle<ConsString> cons = Handle<ConsString>::cast(string);
  if (cons->IsFlat()) return handle(cons->first());
  return SlowFlatten(cons, pretenure);
}
 
 
uint16_t String::Get(int index) {
  DCHECK(index >= 0 && index < length());
  switch (StringShape(this).full_representation_tag()) {
    case kSeqStringTag | kOneByteStringTag:
      return SeqOneByteString::cast(this)->SeqOneByteStringGet(index);
    case kSeqStringTag | kTwoByteStringTag:
      return SeqTwoByteString::cast(this)->SeqTwoByteStringGet(index);
    case kConsStringTag | kOneByteStringTag:
    case kConsStringTag | kTwoByteStringTag:
      return ConsString::cast(this)->ConsStringGet(index);
    case kExternalStringTag | kOneByteStringTag:
      return ExternalOneByteString::cast(this)->ExternalOneByteStringGet(index);
    case kExternalStringTag | kTwoByteStringTag:
      return ExternalTwoByteString::cast(this)->ExternalTwoByteStringGet(index);
    case kSlicedStringTag | kOneByteStringTag:
    case kSlicedStringTag | kTwoByteStringTag:
      return SlicedString::cast(this)->SlicedStringGet(index);
    default:
      break;
  }
 
  UNREACHABLE();
  return 0;
}
 
 
void String::Set(int index, uint16_t value) {
  DCHECK(index >= 0 && index < length());
  DCHECK(StringShape(this).IsSequential());
 
  return this->IsOneByteRepresentation()
      ? SeqOneByteString::cast(this)->SeqOneByteStringSet(index, value)
      : SeqTwoByteString::cast(this)->SeqTwoByteStringSet(index, value);
}
 
 
bool String::IsFlat() {
  if (!StringShape(this).IsCons()) return true;
  return ConsString::cast(this)->second()->length() == 0;
}
 
 
String* String::GetUnderlying() {
  // Giving direct access to underlying string only makes sense if the
  // wrapping string is already flattened.
  DCHECK(this->IsFlat());
  DCHECK(StringShape(this).IsIndirect());
  STATIC_ASSERT(ConsString::kFirstOffset == SlicedString::kParentOffset);
  const int kUnderlyingOffset = SlicedString::kParentOffset;
  return String::cast(READ_FIELD(this, kUnderlyingOffset));
}
 
 
template<class Visitor>
ConsString* String::VisitFlat(Visitor* visitor,
                              String* string,
                              const int offset) {
  int slice_offset = offset;
  const int length = string->length();
  DCHECK(offset <= length);
  while (true) {
    int32_t type = string->map()->instance_type();
    switch (type & (kStringRepresentationMask | kStringEncodingMask)) {
      case kSeqStringTag | kOneByteStringTag:
        visitor->VisitOneByteString(
            SeqOneByteString::cast(string)->GetChars() + slice_offset,
            length - offset);
        return NULL;
 
      case kSeqStringTag | kTwoByteStringTag:
        visitor->VisitTwoByteString(
            SeqTwoByteString::cast(string)->GetChars() + slice_offset,
            length - offset);
        return NULL;
 
      case kExternalStringTag | kOneByteStringTag:
        visitor->VisitOneByteString(
            ExternalOneByteString::cast(string)->GetChars() + slice_offset,
            length - offset);
        return NULL;
 
      case kExternalStringTag | kTwoByteStringTag:
        visitor->VisitTwoByteString(
            ExternalTwoByteString::cast(string)->GetChars() + slice_offset,
            length - offset);
        return NULL;
 
      case kSlicedStringTag | kOneByteStringTag:
      case kSlicedStringTag | kTwoByteStringTag: {
        SlicedString* slicedString = SlicedString::cast(string);
        slice_offset += slicedString->offset();
        string = slicedString->parent();
        continue;
      }
 
      case kConsStringTag | kOneByteStringTag:
      case kConsStringTag | kTwoByteStringTag:
        return ConsString::cast(string);
 
      default:
        UNREACHABLE();
        return NULL;
    }
  }
}
 
 
uint16_t SeqOneByteString::SeqOneByteStringGet(int index) {
  DCHECK(index >= 0 && index < length());
  return READ_BYTE_FIELD(this, kHeaderSize + index * kCharSize);
}
 
 
void SeqOneByteString::SeqOneByteStringSet(int index, uint16_t value) {
  DCHECK(index >= 0 && index < length() && value <= kMaxOneByteCharCode);
  WRITE_BYTE_FIELD(this, kHeaderSize + index * kCharSize,
                   static_cast<byte>(value));
}
 
 
Address SeqOneByteString::GetCharsAddress() {
  return FIELD_ADDR(this, kHeaderSize);
}
 
 
uint8_t* SeqOneByteString::GetChars() {
  return reinterpret_cast<uint8_t*>(GetCharsAddress());
}
 
 
Address SeqTwoByteString::GetCharsAddress() {
  return FIELD_ADDR(this, kHeaderSize);
}
 
 
uc16* SeqTwoByteString::GetChars() {
  return reinterpret_cast<uc16*>(FIELD_ADDR(this, kHeaderSize));
}
 
 
uint16_t SeqTwoByteString::SeqTwoByteStringGet(int index) {
  DCHECK(index >= 0 && index < length());
  return READ_SHORT_FIELD(this, kHeaderSize + index * kShortSize);
}
 
 
void SeqTwoByteString::SeqTwoByteStringSet(int index, uint16_t value) {
  DCHECK(index >= 0 && index < length());
  WRITE_SHORT_FIELD(this, kHeaderSize + index * kShortSize, value);
}
 
 
int SeqTwoByteString::SeqTwoByteStringSize(InstanceType instance_type) {
  return SizeFor(length());
}
 
 
int SeqOneByteString::SeqOneByteStringSize(InstanceType instance_type) {
  return SizeFor(length());
}
 
 
String* SlicedString::parent() {
  return String::cast(READ_FIELD(this, kParentOffset));
}
 
 
void SlicedString::set_parent(String* parent, WriteBarrierMode mode) {
  DCHECK(parent->IsSeqString() || parent->IsExternalString());
  WRITE_FIELD(this, kParentOffset, parent);
  CONDITIONAL_WRITE_BARRIER(GetHeap(), this, kParentOffset, parent, mode);
}
 
 
SMI_ACCESSORS(SlicedString, offset, kOffsetOffset)
 
 
String* ConsString::first() {
  return String::cast(READ_FIELD(this, kFirstOffset));
}
 
 
Object* ConsString::unchecked_first() {
  return READ_FIELD(this, kFirstOffset);
}
 
 
void ConsString::set_first(String* value, WriteBarrierMode mode) {
  WRITE_FIELD(this, kFirstOffset, value);
  CONDITIONAL_WRITE_BARRIER(GetHeap(), this, kFirstOffset, value, mode);
}
 
 
String* ConsString::second() {
  return String::cast(READ_FIELD(this, kSecondOffset));
}
 
 
Object* ConsString::unchecked_second() {
  return READ_FIELD(this, kSecondOffset);
}
 
 
void ConsString::set_second(String* value, WriteBarrierMode mode) {
  WRITE_FIELD(this, kSecondOffset, value);
  CONDITIONAL_WRITE_BARRIER(GetHeap(), this, kSecondOffset, value, mode);
}
 
 
bool ExternalString::is_short() {
  InstanceType type = map()->instance_type();
  return (type & kShortExternalStringMask) == kShortExternalStringTag;
}
 
 
const ExternalOneByteString::Resource* ExternalOneByteString::resource() {
  return *reinterpret_cast<Resource**>(FIELD_ADDR(this, kResourceOffset));
}
 
 
void ExternalOneByteString::update_data_cache() {
  if (is_short()) return;
  const char** data_field =
      reinterpret_cast<const char**>(FIELD_ADDR(this, kResourceDataOffset));
  *data_field = resource()->data();
}
 
 
void ExternalOneByteString::set_resource(
    const ExternalOneByteString::Resource* resource) {
  DCHECK(IsAligned(reinterpret_cast<intptr_t>(resource), kPointerSize));
  *reinterpret_cast<const Resource**>(
      FIELD_ADDR(this, kResourceOffset)) = resource;
  if (resource != NULL) update_data_cache();
}
 
 
const uint8_t* ExternalOneByteString::GetChars() {
  return reinterpret_cast<const uint8_t*>(resource()->data());
}
 
 
uint16_t ExternalOneByteString::ExternalOneByteStringGet(int index) {
  DCHECK(index >= 0 && index < length());
  return GetChars()[index];
}
 
 
const ExternalTwoByteString::Resource* ExternalTwoByteString::resource() {
  return *reinterpret_cast<Resource**>(FIELD_ADDR(this, kResourceOffset));
}
 
 
void ExternalTwoByteString::update_data_cache() {
  if (is_short()) return;
  const uint16_t** data_field =
      reinterpret_cast<const uint16_t**>(FIELD_ADDR(this, kResourceDataOffset));
  *data_field = resource()->data();
}
 
 
void ExternalTwoByteString::set_resource(
    const ExternalTwoByteString::Resource* resource) {
  *reinterpret_cast<const Resource**>(
      FIELD_ADDR(this, kResourceOffset)) = resource;
  if (resource != NULL) update_data_cache();
}
 
 
const uint16_t* ExternalTwoByteString::GetChars() {
  return resource()->data();
}
 
 
uint16_t ExternalTwoByteString::ExternalTwoByteStringGet(int index) {
  DCHECK(index >= 0 && index < length());
  return GetChars()[index];
}
 
 
const uint16_t* ExternalTwoByteString::ExternalTwoByteStringGetData(
      unsigned start) {
  return GetChars() + start;
}
 
 
int ConsStringIteratorOp::OffsetForDepth(int depth) {
  return depth & kDepthMask;
}
 
 
void ConsStringIteratorOp::PushLeft(ConsString* string) {
  frames_[depth_++ & kDepthMask] = string;
}
 
 
void ConsStringIteratorOp::PushRight(ConsString* string) {
  // Inplace update.
  frames_[(depth_-1) & kDepthMask] = string;
}
 
 
void ConsStringIteratorOp::AdjustMaximumDepth() {
  if (depth_ > maximum_depth_) maximum_depth_ = depth_;
}
 
 
void ConsStringIteratorOp::Pop() {
  DCHECK(depth_ > 0);
  DCHECK(depth_ <= maximum_depth_);
  depth_--;
}
 
 
uint16_t StringCharacterStream::GetNext() {
  DCHECK(buffer8_ != NULL && end_ != NULL);
  // Advance cursor if needed.
  if (buffer8_ == end_) HasMore();
  DCHECK(buffer8_ < end_);
  return is_one_byte_ ? *buffer8_++ : *buffer16_++;
}
 
 
StringCharacterStream::StringCharacterStream(String* string,
                                             ConsStringIteratorOp* op,
                                             int offset)
  : is_one_byte_(false),
    op_(op) {
  Reset(string, offset);
}
 
 
void StringCharacterStream::Reset(String* string, int offset) {
  buffer8_ = NULL;
  end_ = NULL;
  ConsString* cons_string = String::VisitFlat(this, string, offset);
  op_->Reset(cons_string, offset);
  if (cons_string != NULL) {
    string = op_->Next(&offset);
    if (string != NULL) String::VisitFlat(this, string, offset);
  }
}
 
 
bool StringCharacterStream::HasMore() {
  if (buffer8_ != end_) return true;
  int offset;
  String* string = op_->Next(&offset);
  DCHECK_EQ(offset, 0);
  if (string == NULL) return false;
  String::VisitFlat(this, string);
  DCHECK(buffer8_ != end_);
  return true;
}
 
 
void StringCharacterStream::VisitOneByteString(
    const uint8_t* chars, int length) {
  is_one_byte_ = true;
  buffer8_ = chars;
  end_ = chars + length;
}
 
 
void StringCharacterStream::VisitTwoByteString(
    const uint16_t* chars, int length) {
  is_one_byte_ = false;
  buffer16_ = chars;
  end_ = reinterpret_cast<const uint8_t*>(chars + length);
}
 
 
void JSFunctionResultCache::MakeZeroSize() {
  set_finger_index(kEntriesIndex);
  set_size(kEntriesIndex);
}
 
 
void JSFunctionResultCache::Clear() {
  int cache_size = size();
  Object** entries_start = RawFieldOfElementAt(kEntriesIndex);
  MemsetPointer(entries_start,
                GetHeap()->the_hole_value(),
                cache_size - kEntriesIndex);
  MakeZeroSize();
}
 
 
int JSFunctionResultCache::size() {
  return Smi::cast(get(kCacheSizeIndex))->value();
}
 
 
void JSFunctionResultCache::set_size(int size) {
  set(kCacheSizeIndex, Smi::FromInt(size));
}
 
 
int JSFunctionResultCache::finger_index() {
  return Smi::cast(get(kFingerIndex))->value();
}
 
 
void JSFunctionResultCache::set_finger_index(int finger_index) {
  set(kFingerIndex, Smi::FromInt(finger_index));
}
 
 
byte ByteArray::get(int index) {
  DCHECK(index >= 0 && index < this->length());
  return READ_BYTE_FIELD(this, kHeaderSize + index * kCharSize);
}
 
 
void ByteArray::set(int index, byte value) {
  DCHECK(index >= 0 && index < this->length());
  WRITE_BYTE_FIELD(this, kHeaderSize + index * kCharSize, value);
}
 
 
int ByteArray::get_int(int index) {
  DCHECK(index >= 0 && (index * kIntSize) < this->length());
  return READ_INT_FIELD(this, kHeaderSize + index * kIntSize);
}
 
 
ByteArray* ByteArray::FromDataStartAddress(Address address) {
  DCHECK_TAG_ALIGNED(address);
  return reinterpret_cast<ByteArray*>(address - kHeaderSize + kHeapObjectTag);
}
 
 
Address ByteArray::GetDataStartAddress() {
  return reinterpret_cast<Address>(this) - kHeapObjectTag + kHeaderSize;
}
 
 
uint8_t* ExternalUint8ClampedArray::external_uint8_clamped_pointer() {
  return reinterpret_cast<uint8_t*>(external_pointer());
}
 
 
uint8_t ExternalUint8ClampedArray::get_scalar(int index) {
  DCHECK((index >= 0) && (index < this->length()));
  uint8_t* ptr = external_uint8_clamped_pointer();
  return ptr[index];
}
 
 
Handle<Object> ExternalUint8ClampedArray::get(
    Handle<ExternalUint8ClampedArray> array,
    int index) {
  return Handle<Smi>(Smi::FromInt(array->get_scalar(index)),
                     array->GetIsolate());
}
 
 
void ExternalUint8ClampedArray::set(int index, uint8_t value) {
  DCHECK((index >= 0) && (index < this->length()));
  uint8_t* ptr = external_uint8_clamped_pointer();
  ptr[index] = value;
}
 
 
void* ExternalArray::external_pointer() const {
  intptr_t ptr = READ_INTPTR_FIELD(this, kExternalPointerOffset);
  return reinterpret_cast<void*>(ptr);
}
 
 
void ExternalArray::set_external_pointer(void* value, WriteBarrierMode mode) {
  intptr_t ptr = reinterpret_cast<intptr_t>(value);
  WRITE_INTPTR_FIELD(this, kExternalPointerOffset, ptr);
}
 
 
int8_t ExternalInt8Array::get_scalar(int index) {
  DCHECK((index >= 0) && (index < this->length()));
  int8_t* ptr = static_cast<int8_t*>(external_pointer());
  return ptr[index];
}
 
 
Handle<Object> ExternalInt8Array::get(Handle<ExternalInt8Array> array,
                                      int index) {
  return Handle<Smi>(Smi::FromInt(array->get_scalar(index)),
                     array->GetIsolate());
}
 
 
void ExternalInt8Array::set(int index, int8_t value) {
  DCHECK((index >= 0) && (index < this->length()));
  int8_t* ptr = static_cast<int8_t*>(external_pointer());
  ptr[index] = value;
}
 
 
uint8_t ExternalUint8Array::get_scalar(int index) {
  DCHECK((index >= 0) && (index < this->length()));
  uint8_t* ptr = static_cast<uint8_t*>(external_pointer());
  return ptr[index];
}
 
 
Handle<Object> ExternalUint8Array::get(Handle<ExternalUint8Array> array,
                                       int index) {
  return Handle<Smi>(Smi::FromInt(array->get_scalar(index)),
                     array->GetIsolate());
}
 
 
void ExternalUint8Array::set(int index, uint8_t value) {
  DCHECK((index >= 0) && (index < this->length()));
  uint8_t* ptr = static_cast<uint8_t*>(external_pointer());
  ptr[index] = value;
}
 
 
int16_t ExternalInt16Array::get_scalar(int index) {
  DCHECK((index >= 0) && (index < this->length()));
  int16_t* ptr = static_cast<int16_t*>(external_pointer());
  return ptr[index];
}
 
 
Handle<Object> ExternalInt16Array::get(Handle<ExternalInt16Array> array,
                                       int index) {
  return Handle<Smi>(Smi::FromInt(array->get_scalar(index)),
                     array->GetIsolate());
}
 
 
void ExternalInt16Array::set(int index, int16_t value) {
  DCHECK((index >= 0) && (index < this->length()));
  int16_t* ptr = static_cast<int16_t*>(external_pointer());
  ptr[index] = value;
}
 
 
uint16_t ExternalUint16Array::get_scalar(int index) {
  DCHECK((index >= 0) && (index < this->length()));
  uint16_t* ptr = static_cast<uint16_t*>(external_pointer());
  return ptr[index];
}
 
 
Handle<Object> ExternalUint16Array::get(Handle<ExternalUint16Array> array,
                                        int index) {
  return Handle<Smi>(Smi::FromInt(array->get_scalar(index)),
                     array->GetIsolate());
}
 
 
void ExternalUint16Array::set(int index, uint16_t value) {
  DCHECK((index >= 0) && (index < this->length()));
  uint16_t* ptr = static_cast<uint16_t*>(external_pointer());
  ptr[index] = value;
}
 
 
int32_t ExternalInt32Array::get_scalar(int index) {
  DCHECK((index >= 0) && (index < this->length()));
  int32_t* ptr = static_cast<int32_t*>(external_pointer());
  return ptr[index];
}
 
 
Handle<Object> ExternalInt32Array::get(Handle<ExternalInt32Array> array,
                                       int index) {
  return array->GetIsolate()->factory()->
      NewNumberFromInt(array->get_scalar(index));
}
 
 
void ExternalInt32Array::set(int index, int32_t value) {
  DCHECK((index >= 0) && (index < this->length()));
  int32_t* ptr = static_cast<int32_t*>(external_pointer());
  ptr[index] = value;
}
 
 
uint32_t ExternalUint32Array::get_scalar(int index) {
  DCHECK((index >= 0) && (index < this->length()));
  uint32_t* ptr = static_cast<uint32_t*>(external_pointer());
  return ptr[index];
}
 
 
Handle<Object> ExternalUint32Array::get(Handle<ExternalUint32Array> array,
                                        int index) {
  return array->GetIsolate()->factory()->
      NewNumberFromUint(array->get_scalar(index));
}
 
 
void ExternalUint32Array::set(int index, uint32_t value) {
  DCHECK((index >= 0) && (index < this->length()));
  uint32_t* ptr = static_cast<uint32_t*>(external_pointer());
  ptr[index] = value;
}
 
 
float ExternalFloat32Array::get_scalar(int index) {
  DCHECK((index >= 0) && (index < this->length()));
  float* ptr = static_cast<float*>(external_pointer());
  return ptr[index];
}
 
 
Handle<Object> ExternalFloat32Array::get(Handle<ExternalFloat32Array> array,
                                         int index) {
  return array->GetIsolate()->factory()->NewNumber(array->get_scalar(index));
}
 
 
void ExternalFloat32Array::set(int index, float value) {
  DCHECK((index >= 0) && (index < this->length()));
  float* ptr = static_cast<float*>(external_pointer());
  ptr[index] = value;
}
 
 
double ExternalFloat64Array::get_scalar(int index) {
  DCHECK((index >= 0) && (index < this->length()));
  double* ptr = static_cast<double*>(external_pointer());
  return ptr[index];
}
 
 
Handle<Object> ExternalFloat64Array::get(Handle<ExternalFloat64Array> array,
                                         int index) {
  return array->GetIsolate()->factory()->NewNumber(array->get_scalar(index));
}
 
 
void ExternalFloat64Array::set(int index, double value) {
  DCHECK((index >= 0) && (index < this->length()));
  double* ptr = static_cast<double*>(external_pointer());
  ptr[index] = value;
}
 
 
void* FixedTypedArrayBase::DataPtr() {
  return FIELD_ADDR(this, kDataOffset);
}
 
 
int FixedTypedArrayBase::DataSize(InstanceType type) {
  int element_size;
  switch (type) {
#define TYPED_ARRAY_CASE(Type, type, TYPE, ctype, size)                       \
    case FIXED_##TYPE##_ARRAY_TYPE:                                           \
      element_size = size;                                                    \
      break;
 
    TYPED_ARRAYS(TYPED_ARRAY_CASE)
#undef TYPED_ARRAY_CASE
    default:
      UNREACHABLE();
      return 0;
  }
  return length() * element_size;
}
 
 
int FixedTypedArrayBase::DataSize() {
  return DataSize(map()->instance_type());
}
 
 
int FixedTypedArrayBase::size() {
  return OBJECT_POINTER_ALIGN(kDataOffset + DataSize());
}
 
 
int FixedTypedArrayBase::TypedArraySize(InstanceType type) {
  return OBJECT_POINTER_ALIGN(kDataOffset + DataSize(type));
}
 
 
uint8_t Uint8ArrayTraits::defaultValue() { return 0; }
 
 
uint8_t Uint8ClampedArrayTraits::defaultValue() { return 0; }
 
 
int8_t Int8ArrayTraits::defaultValue() { return 0; }
 
 
uint16_t Uint16ArrayTraits::defaultValue() { return 0; }
 
 
int16_t Int16ArrayTraits::defaultValue() { return 0; }
 
 
uint32_t Uint32ArrayTraits::defaultValue() { return 0; }
 
 
int32_t Int32ArrayTraits::defaultValue() { return 0; }
 
 
float Float32ArrayTraits::defaultValue() {
  return static_cast<float>(base::OS::nan_value());
}
 
 
double Float64ArrayTraits::defaultValue() { return base::OS::nan_value(); }
 
 
template <class Traits>
typename Traits::ElementType FixedTypedArray<Traits>::get_scalar(int index) {
  DCHECK((index >= 0) && (index < this->length()));
  ElementType* ptr = reinterpret_cast<ElementType*>(
      FIELD_ADDR(this, kDataOffset));
  return ptr[index];
}
 
 
template<> inline
FixedTypedArray<Float64ArrayTraits>::ElementType
    FixedTypedArray<Float64ArrayTraits>::get_scalar(int index) {
  DCHECK((index >= 0) && (index < this->length()));
  return READ_DOUBLE_FIELD(this, ElementOffset(index));
}
 
 
template <class Traits>
void FixedTypedArray<Traits>::set(int index, ElementType value) {
  DCHECK((index >= 0) && (index < this->length()));
  ElementType* ptr = reinterpret_cast<ElementType*>(
      FIELD_ADDR(this, kDataOffset));
  ptr[index] = value;
}
 
 
template<> inline
void FixedTypedArray<Float64ArrayTraits>::set(
    int index, Float64ArrayTraits::ElementType value) {
  DCHECK((index >= 0) && (index < this->length()));
  WRITE_DOUBLE_FIELD(this, ElementOffset(index), value);
}
 
 
template <class Traits>
typename Traits::ElementType FixedTypedArray<Traits>::from_int(int value) {
  return static_cast<ElementType>(value);
}
 
 
template <> inline
uint8_t FixedTypedArray<Uint8ClampedArrayTraits>::from_int(int value) {
  if (value < 0) return 0;
  if (value > 0xFF) return 0xFF;
  return static_cast<uint8_t>(value);
}
 
 
template <class Traits>
typename Traits::ElementType FixedTypedArray<Traits>::from_double(
    double value) {
  return static_cast<ElementType>(DoubleToInt32(value));
}
 
 
template<> inline
uint8_t FixedTypedArray<Uint8ClampedArrayTraits>::from_double(double value) {
  if (value < 0) return 0;
  if (value > 0xFF) return 0xFF;
  return static_cast<uint8_t>(lrint(value));
}
 
 
template<> inline
float FixedTypedArray<Float32ArrayTraits>::from_double(double value) {
  return static_cast<float>(value);
}
 
 
template<> inline
double FixedTypedArray<Float64ArrayTraits>::from_double(double value) {
  return value;
}
 
 
template <class Traits>
Handle<Object> FixedTypedArray<Traits>::get(
    Handle<FixedTypedArray<Traits> > array,
    int index) {
  return Traits::ToHandle(array->GetIsolate(), array->get_scalar(index));
}
 
 
template <class Traits>
Handle<Object> FixedTypedArray<Traits>::SetValue(
    Handle<FixedTypedArray<Traits> > array,
    uint32_t index,
    Handle<Object> value) {
  ElementType cast_value = Traits::defaultValue();
  if (index < static_cast<uint32_t>(array->length())) {
    if (value->IsSmi()) {
      int int_value = Handle<Smi>::cast(value)->value();
      cast_value = from_int(int_value);
    } else if (value->IsHeapNumber()) {
      double double_value = Handle<HeapNumber>::cast(value)->value();
      cast_value = from_double(double_value);
    } else {
      // Clamp undefined to the default value. All other types have been
      // converted to a number type further up in the call chain.
      DCHECK(value->IsUndefined());
    }
    array->set(index, cast_value);
  }
  return Traits::ToHandle(array->GetIsolate(), cast_value);
}
 
 
Handle<Object> Uint8ArrayTraits::ToHandle(Isolate* isolate, uint8_t scalar) {
  return handle(Smi::FromInt(scalar), isolate);
}
 
 
Handle<Object> Uint8ClampedArrayTraits::ToHandle(Isolate* isolate,
                                                 uint8_t scalar) {
  return handle(Smi::FromInt(scalar), isolate);
}
 
 
Handle<Object> Int8ArrayTraits::ToHandle(Isolate* isolate, int8_t scalar) {
  return handle(Smi::FromInt(scalar), isolate);
}
 
 
Handle<Object> Uint16ArrayTraits::ToHandle(Isolate* isolate, uint16_t scalar) {
  return handle(Smi::FromInt(scalar), isolate);
}
 
 
Handle<Object> Int16ArrayTraits::ToHandle(Isolate* isolate, int16_t scalar) {
  return handle(Smi::FromInt(scalar), isolate);
}
 
 
Handle<Object> Uint32ArrayTraits::ToHandle(Isolate* isolate, uint32_t scalar) {
  return isolate->factory()->NewNumberFromUint(scalar);
}
 
 
Handle<Object> Int32ArrayTraits::ToHandle(Isolate* isolate, int32_t scalar) {
  return isolate->factory()->NewNumberFromInt(scalar);
}
 
 
Handle<Object> Float32ArrayTraits::ToHandle(Isolate* isolate, float scalar) {
  return isolate->factory()->NewNumber(scalar);
}
 
 
Handle<Object> Float64ArrayTraits::ToHandle(Isolate* isolate, double scalar) {
  return isolate->factory()->NewNumber(scalar);
}
 
 
int Map::visitor_id() {
  return READ_BYTE_FIELD(this, kVisitorIdOffset);
}
 
 
void Map::set_visitor_id(int id) {
  DCHECK(0 <= id && id < 256);
  WRITE_BYTE_FIELD(this, kVisitorIdOffset, static_cast<byte>(id));
}
 
 
int Map::instance_size() {
  return NOBARRIER_READ_BYTE_FIELD(
      this, kInstanceSizeOffset) << kPointerSizeLog2;
}
 
 
int Map::inobject_properties() {
  return READ_BYTE_FIELD(this, kInObjectPropertiesOffset);
}
 
 
int Map::pre_allocated_property_fields() {
  return READ_BYTE_FIELD(this, kPreAllocatedPropertyFieldsOffset);
}
 
 
int Map::GetInObjectPropertyOffset(int index) {
  // Adjust for the number of properties stored in the object.
  index -= inobject_properties();
  DCHECK(index <= 0);
  return instance_size() + (index * kPointerSize);
}
 
 
int HeapObject::SizeFromMap(Map* map) {
  int instance_size = map->instance_size();
  if (instance_size != kVariableSizeSentinel) return instance_size;
  // Only inline the most frequent cases.
  InstanceType instance_type = map->instance_type();
  if (instance_type == FIXED_ARRAY_TYPE) {
    return FixedArray::BodyDescriptor::SizeOf(map, this);
  }
  if (instance_type == ONE_BYTE_STRING_TYPE ||
      instance_type == ONE_BYTE_INTERNALIZED_STRING_TYPE) {
    return SeqOneByteString::SizeFor(
        reinterpret_cast<SeqOneByteString*>(this)->length());
  }
  if (instance_type == BYTE_ARRAY_TYPE) {
    return reinterpret_cast<ByteArray*>(this)->ByteArraySize();
  }
  if (instance_type == FREE_SPACE_TYPE) {
    return reinterpret_cast<FreeSpace*>(this)->nobarrier_size();
  }
  if (instance_type == STRING_TYPE ||
      instance_type == INTERNALIZED_STRING_TYPE) {
    return SeqTwoByteString::SizeFor(
        reinterpret_cast<SeqTwoByteString*>(this)->length());
  }
  if (instance_type == FIXED_DOUBLE_ARRAY_TYPE) {
    return FixedDoubleArray::SizeFor(
        reinterpret_cast<FixedDoubleArray*>(this)->length());
  }
  if (instance_type == CONSTANT_POOL_ARRAY_TYPE) {
    return reinterpret_cast<ConstantPoolArray*>(this)->size();
  }
  if (instance_type >= FIRST_FIXED_TYPED_ARRAY_TYPE &&
      instance_type <= LAST_FIXED_TYPED_ARRAY_TYPE) {
    return reinterpret_cast<FixedTypedArrayBase*>(
        this)->TypedArraySize(instance_type);
  }
  DCHECK(instance_type == CODE_TYPE);
  return reinterpret_cast<Code*>(this)->CodeSize();
}
 
 
void Map::set_instance_size(int value) {
  DCHECK_EQ(0, value & (kPointerSize - 1));
  value >>= kPointerSizeLog2;
  DCHECK(0 <= value && value < 256);
  NOBARRIER_WRITE_BYTE_FIELD(
      this, kInstanceSizeOffset, static_cast<byte>(value));
}
 
 
void Map::set_inobject_properties(int value) {
  DCHECK(0 <= value && value < 256);
  WRITE_BYTE_FIELD(this, kInObjectPropertiesOffset, static_cast<byte>(value));
}
 
 
void Map::set_pre_allocated_property_fields(int value) {
  DCHECK(0 <= value && value < 256);
  WRITE_BYTE_FIELD(this,
                   kPreAllocatedPropertyFieldsOffset,
                   static_cast<byte>(value));
}
 
 
InstanceType Map::instance_type() {
  return static_cast<InstanceType>(READ_BYTE_FIELD(this, kInstanceTypeOffset));
}
 
 
void Map::set_instance_type(InstanceType value) {
  WRITE_BYTE_FIELD(this, kInstanceTypeOffset, value);
}
 
 
int Map::unused_property_fields() {
  return READ_BYTE_FIELD(this, kUnusedPropertyFieldsOffset);
}
 
 
void Map::set_unused_property_fields(int value) {
  WRITE_BYTE_FIELD(this, kUnusedPropertyFieldsOffset, Min(value, 255));
}
 
 
byte Map::bit_field() {
  return READ_BYTE_FIELD(this, kBitFieldOffset);
}
 
 
void Map::set_bit_field(byte value) {
  WRITE_BYTE_FIELD(this, kBitFieldOffset, value);
}
 
 
byte Map::bit_field2() {
  return READ_BYTE_FIELD(this, kBitField2Offset);
}
 
 
void Map::set_bit_field2(byte value) {
  WRITE_BYTE_FIELD(this, kBitField2Offset, value);
}
 
 
void Map::set_non_instance_prototype(bool value) {
  if (value) {
    set_bit_field(bit_field() | (1 << kHasNonInstancePrototype));
  } else {
    set_bit_field(bit_field() & ~(1 << kHasNonInstancePrototype));
  }
}
 
 
bool Map::has_non_instance_prototype() {
  return ((1 << kHasNonInstancePrototype) & bit_field()) != 0;
}
 
 
void Map::set_function_with_prototype(bool value) {
  set_bit_field(FunctionWithPrototype::update(bit_field(), value));
}
 
 
bool Map::function_with_prototype() {
  return FunctionWithPrototype::decode(bit_field());
}
 
 
void Map::set_is_access_check_needed(bool access_check_needed) {
  if (access_check_needed) {
    set_bit_field(bit_field() | (1 << kIsAccessCheckNeeded));
  } else {
    set_bit_field(bit_field() & ~(1 << kIsAccessCheckNeeded));
  }
}
 
 
bool Map::is_access_check_needed() {
  return ((1 << kIsAccessCheckNeeded) & bit_field()) != 0;
}
 
 
void Map::set_is_extensible(bool value) {
  if (value) {
    set_bit_field2(bit_field2() | (1 << kIsExtensible));
  } else {
    set_bit_field2(bit_field2() & ~(1 << kIsExtensible));
  }
}
 
bool Map::is_extensible() {
  return ((1 << kIsExtensible) & bit_field2()) != 0;
}
 
 
void Map::set_is_prototype_map(bool value) {
  set_bit_field2(IsPrototypeMapBits::update(bit_field2(), value));
}
 
bool Map::is_prototype_map() {
  return IsPrototypeMapBits::decode(bit_field2());
}
 
 
void Map::set_dictionary_map(bool value) {
  uint32_t new_bit_field3 = DictionaryMap::update(bit_field3(), value);
  new_bit_field3 = IsUnstable::update(new_bit_field3, value);
  set_bit_field3(new_bit_field3);
}
 
 
bool Map::is_dictionary_map() {
  return DictionaryMap::decode(bit_field3());
}
 
 
Code::Flags Code::flags() {
  return static_cast<Flags>(READ_INT_FIELD(this, kFlagsOffset));
}
 
 
void Map::set_owns_descriptors(bool owns_descriptors) {
  set_bit_field3(OwnsDescriptors::update(bit_field3(), owns_descriptors));
}
 
 
bool Map::owns_descriptors() {
  return OwnsDescriptors::decode(bit_field3());
}
 
 
void Map::set_has_instance_call_handler() {
  set_bit_field3(HasInstanceCallHandler::update(bit_field3(), true));
}
 
 
bool Map::has_instance_call_handler() {
  return HasInstanceCallHandler::decode(bit_field3());
}
 
 
void Map::deprecate() {
  set_bit_field3(Deprecated::update(bit_field3(), true));
}
 
 
bool Map::is_deprecated() {
  return Deprecated::decode(bit_field3());
}
 
 
void Map::set_migration_target(bool value) {
  set_bit_field3(IsMigrationTarget::update(bit_field3(), value));
}
 
 
bool Map::is_migration_target() {
  return IsMigrationTarget::decode(bit_field3());
}
 
 
void Map::set_done_inobject_slack_tracking(bool value) {
  set_bit_field3(DoneInobjectSlackTracking::update(bit_field3(), value));
}
 
 
bool Map::done_inobject_slack_tracking() {
  return DoneInobjectSlackTracking::decode(bit_field3());
}
 
 
void Map::set_construction_count(int value) {
  set_bit_field3(ConstructionCount::update(bit_field3(), value));
}
 
 
int Map::construction_count() {
  return ConstructionCount::decode(bit_field3());
}
 
 
void Map::freeze() {
  set_bit_field3(IsFrozen::update(bit_field3(), true));
}
 
 
bool Map::is_frozen() {
  return IsFrozen::decode(bit_field3());
}
 
 
void Map::mark_unstable() {
  set_bit_field3(IsUnstable::update(bit_field3(), true));
}
 
 
bool Map::is_stable() {
  return !IsUnstable::decode(bit_field3());
}
 
 
bool Map::has_code_cache() {
  return code_cache() != GetIsolate()->heap()->empty_fixed_array();
}
 
 
bool Map::CanBeDeprecated() {
  int descriptor = LastAdded();
  for (int i = 0; i <= descriptor; i++) {
    PropertyDetails details = instance_descriptors()->GetDetails(i);
    if (details.representation().IsNone()) return true;
    if (details.representation().IsSmi()) return true;
    if (details.representation().IsDouble()) return true;
    if (details.representation().IsHeapObject()) return true;
    if (details.type() == CONSTANT) return true;
  }
  return false;
}
 
 
void Map::NotifyLeafMapLayoutChange() {
  if (is_stable()) {
    mark_unstable();
    dependent_code()->DeoptimizeDependentCodeGroup(
        GetIsolate(),
        DependentCode::kPrototypeCheckGroup);
  }
}
 
 
bool Map::CanOmitMapChecks() {
  return is_stable() && FLAG_omit_map_checks_for_leaf_maps;
}
 
 
int DependentCode::number_of_entries(DependencyGroup group) {
  if (length() == 0) return 0;
  return Smi::cast(get(group))->value();
}
 
 
void DependentCode::set_number_of_entries(DependencyGroup group, int value) {
  set(group, Smi::FromInt(value));
}
 
 
bool DependentCode::is_code_at(int i) {
  return get(kCodesStartIndex + i)->IsCode();
}
 
Code* DependentCode::code_at(int i) {
  return Code::cast(get(kCodesStartIndex + i));
}
 
 
CompilationInfo* DependentCode::compilation_info_at(int i) {
  return reinterpret_cast<CompilationInfo*>(
      Foreign::cast(get(kCodesStartIndex + i))->foreign_address());
}
 
 
void DependentCode::set_object_at(int i, Object* object) {
  set(kCodesStartIndex + i, object);
}
 
 
Object* DependentCode::object_at(int i) {
  return get(kCodesStartIndex + i);
}
 
 
Object** DependentCode::slot_at(int i) {
  return RawFieldOfElementAt(kCodesStartIndex + i);
}
 
 
void DependentCode::clear_at(int i) {
  set_undefined(kCodesStartIndex + i);
}
 
 
void DependentCode::copy(int from, int to) {
  set(kCodesStartIndex + to, get(kCodesStartIndex + from));
}
 
 
void DependentCode::ExtendGroup(DependencyGroup group) {
  GroupStartIndexes starts(this);
  for (int g = kGroupCount - 1; g > group; g--) {
    if (starts.at(g) < starts.at(g + 1)) {
      copy(starts.at(g), starts.at(g + 1));
    }
  }
}
 
 
void Code::set_flags(Code::Flags flags) {
  STATIC_ASSERT(Code::NUMBER_OF_KINDS <= KindField::kMax + 1);
  WRITE_INT_FIELD(this, kFlagsOffset, flags);
}
 
 
Code::Kind Code::kind() {
  return ExtractKindFromFlags(flags());
}
 
 
bool Code::IsCodeStubOrIC() {
  return kind() == STUB || kind() == HANDLER || kind() == LOAD_IC ||
         kind() == KEYED_LOAD_IC || kind() == CALL_IC || kind() == STORE_IC ||
         kind() == KEYED_STORE_IC || kind() == BINARY_OP_IC ||
         kind() == COMPARE_IC || kind() == COMPARE_NIL_IC ||
         kind() == TO_BOOLEAN_IC;
}
 
 
InlineCacheState Code::ic_state() {
  InlineCacheState result = ExtractICStateFromFlags(flags());
  // Only allow uninitialized or debugger states for non-IC code
  // objects. This is used in the debugger to determine whether or not
  // a call to code object has been replaced with a debug break call.
  DCHECK(is_inline_cache_stub() ||
         result == UNINITIALIZED ||
         result == DEBUG_STUB);
  return result;
}
 
 
ExtraICState Code::extra_ic_state() {
  DCHECK(is_inline_cache_stub() || ic_state() == DEBUG_STUB);
  return ExtractExtraICStateFromFlags(flags());
}
 
 
Code::StubType Code::type() {
  return ExtractTypeFromFlags(flags());
}
 
 
// For initialization.
void Code::set_raw_kind_specific_flags1(int value) {
  WRITE_INT_FIELD(this, kKindSpecificFlags1Offset, value);
}
 
 
void Code::set_raw_kind_specific_flags2(int value) {
  WRITE_INT_FIELD(this, kKindSpecificFlags2Offset, value);
}
 
 
inline bool Code::is_crankshafted() {
  return IsCrankshaftedField::decode(
      READ_UINT32_FIELD(this, kKindSpecificFlags2Offset));
}
 
 
inline bool Code::is_hydrogen_stub() {
  return is_crankshafted() && kind() != OPTIMIZED_FUNCTION;
}
 
 
inline void Code::set_is_crankshafted(bool value) {
  int previous = READ_UINT32_FIELD(this, kKindSpecificFlags2Offset);
  int updated = IsCrankshaftedField::update(previous, value);
  WRITE_UINT32_FIELD(this, kKindSpecificFlags2Offset, updated);
}
 
 
inline bool Code::is_turbofanned() {
  DCHECK(kind() == OPTIMIZED_FUNCTION || kind() == STUB);
  return IsTurbofannedField::decode(
      READ_UINT32_FIELD(this, kKindSpecificFlags1Offset));
}
 
 
inline void Code::set_is_turbofanned(bool value) {
  DCHECK(kind() == OPTIMIZED_FUNCTION || kind() == STUB);
  int previous = READ_UINT32_FIELD(this, kKindSpecificFlags1Offset);
  int updated = IsTurbofannedField::update(previous, value);
  WRITE_UINT32_FIELD(this, kKindSpecificFlags1Offset, updated);
}
 
 
bool Code::optimizable() {
  DCHECK_EQ(FUNCTION, kind());
  return READ_BYTE_FIELD(this, kOptimizableOffset) == 1;
}
 
 
void Code::set_optimizable(bool value) {
  DCHECK_EQ(FUNCTION, kind());
  WRITE_BYTE_FIELD(this, kOptimizableOffset, value ? 1 : 0);
}
 
 
bool Code::has_deoptimization_support() {
  DCHECK_EQ(FUNCTION, kind());
  byte flags = READ_BYTE_FIELD(this, kFullCodeFlags);
  return FullCodeFlagsHasDeoptimizationSupportField::decode(flags);
}
 
 
void Code::set_has_deoptimization_support(bool value) {
  DCHECK_EQ(FUNCTION, kind());
  byte flags = READ_BYTE_FIELD(this, kFullCodeFlags);
  flags = FullCodeFlagsHasDeoptimizationSupportField::update(flags, value);
  WRITE_BYTE_FIELD(this, kFullCodeFlags, flags);
}
 
 
bool Code::has_debug_break_slots() {
  DCHECK_EQ(FUNCTION, kind());
  byte flags = READ_BYTE_FIELD(this, kFullCodeFlags);
  return FullCodeFlagsHasDebugBreakSlotsField::decode(flags);
}
 
 
void Code::set_has_debug_break_slots(bool value) {
  DCHECK_EQ(FUNCTION, kind());
  byte flags = READ_BYTE_FIELD(this, kFullCodeFlags);
  flags = FullCodeFlagsHasDebugBreakSlotsField::update(flags, value);
  WRITE_BYTE_FIELD(this, kFullCodeFlags, flags);
}
 
 
bool Code::is_compiled_optimizable() {
  DCHECK_EQ(FUNCTION, kind());
  byte flags = READ_BYTE_FIELD(this, kFullCodeFlags);
  return FullCodeFlagsIsCompiledOptimizable::decode(flags);
}
 
 
void Code::set_compiled_optimizable(bool value) {
  DCHECK_EQ(FUNCTION, kind());
  byte flags = READ_BYTE_FIELD(this, kFullCodeFlags);
  flags = FullCodeFlagsIsCompiledOptimizable::update(flags, value);
  WRITE_BYTE_FIELD(this, kFullCodeFlags, flags);
}
 
 
int Code::allow_osr_at_loop_nesting_level() {
  DCHECK_EQ(FUNCTION, kind());
  int fields = READ_UINT32_FIELD(this, kKindSpecificFlags2Offset);
  return AllowOSRAtLoopNestingLevelField::decode(fields);
}
 
 
void Code::set_allow_osr_at_loop_nesting_level(int level) {
  DCHECK_EQ(FUNCTION, kind());
  DCHECK(level >= 0 && level <= kMaxLoopNestingMarker);
  int previous = READ_UINT32_FIELD(this, kKindSpecificFlags2Offset);
  int updated = AllowOSRAtLoopNestingLevelField::update(previous, level);
  WRITE_UINT32_FIELD(this, kKindSpecificFlags2Offset, updated);
}
 
 
int Code::profiler_ticks() {
  DCHECK_EQ(FUNCTION, kind());
  return READ_BYTE_FIELD(this, kProfilerTicksOffset);
}
 
 
void Code::set_profiler_ticks(int ticks) {
  DCHECK(ticks < 256);
  if (kind() == FUNCTION) {
    WRITE_BYTE_FIELD(this, kProfilerTicksOffset, ticks);
  }
}
 
 
int Code::builtin_index() {
  DCHECK_EQ(BUILTIN, kind());
  return READ_INT32_FIELD(this, kKindSpecificFlags1Offset);
}
 
 
void Code::set_builtin_index(int index) {
  DCHECK_EQ(BUILTIN, kind());
  WRITE_INT32_FIELD(this, kKindSpecificFlags1Offset, index);
}
 
 
unsigned Code::stack_slots() {
  DCHECK(is_crankshafted());
  return StackSlotsField::decode(
      READ_UINT32_FIELD(this, kKindSpecificFlags1Offset));
}
 
 
void Code::set_stack_slots(unsigned slots) {
  CHECK(slots <= (1 << kStackSlotsBitCount));
  DCHECK(is_crankshafted());
  int previous = READ_UINT32_FIELD(this, kKindSpecificFlags1Offset);
  int updated = StackSlotsField::update(previous, slots);
  WRITE_UINT32_FIELD(this, kKindSpecificFlags1Offset, updated);
}
 
 
unsigned Code::safepoint_table_offset() {
  DCHECK(is_crankshafted());
  return SafepointTableOffsetField::decode(
      READ_UINT32_FIELD(this, kKindSpecificFlags2Offset));
}
 
 
void Code::set_safepoint_table_offset(unsigned offset) {
  CHECK(offset <= (1 << kSafepointTableOffsetBitCount));
  DCHECK(is_crankshafted());
  DCHECK(IsAligned(offset, static_cast<unsigned>(kIntSize)));
  int previous = READ_UINT32_FIELD(this, kKindSpecificFlags2Offset);
  int updated = SafepointTableOffsetField::update(previous, offset);
  WRITE_UINT32_FIELD(this, kKindSpecificFlags2Offset, updated);
}
 
 
unsigned Code::back_edge_table_offset() {
  DCHECK_EQ(FUNCTION, kind());
  return BackEdgeTableOffsetField::decode(
      READ_UINT32_FIELD(this, kKindSpecificFlags2Offset)) << kPointerSizeLog2;
}
 
 
void Code::set_back_edge_table_offset(unsigned offset) {
  DCHECK_EQ(FUNCTION, kind());
  DCHECK(IsAligned(offset, static_cast<unsigned>(kPointerSize)));
  offset = offset >> kPointerSizeLog2;
  int previous = READ_UINT32_FIELD(this, kKindSpecificFlags2Offset);
  int updated = BackEdgeTableOffsetField::update(previous, offset);
  WRITE_UINT32_FIELD(this, kKindSpecificFlags2Offset, updated);
}
 
 
bool Code::back_edges_patched_for_osr() {
  DCHECK_EQ(FUNCTION, kind());
  return allow_osr_at_loop_nesting_level() > 0;
}
 
 
byte Code::to_boolean_state() {
  return extra_ic_state();
}
 
 
bool Code::has_function_cache() {
  DCHECK(kind() == STUB);
  return HasFunctionCacheField::decode(
      READ_UINT32_FIELD(this, kKindSpecificFlags1Offset));
}
 
 
void Code::set_has_function_cache(bool flag) {
  DCHECK(kind() == STUB);
  int previous = READ_UINT32_FIELD(this, kKindSpecificFlags1Offset);
  int updated = HasFunctionCacheField::update(previous, flag);
  WRITE_UINT32_FIELD(this, kKindSpecificFlags1Offset, updated);
}
 
 
bool Code::marked_for_deoptimization() {
  DCHECK(kind() == OPTIMIZED_FUNCTION);
  return MarkedForDeoptimizationField::decode(
      READ_UINT32_FIELD(this, kKindSpecificFlags1Offset));
}
 
 
void Code::set_marked_for_deoptimization(bool flag) {
  DCHECK(kind() == OPTIMIZED_FUNCTION);
  DCHECK(!flag || AllowDeoptimization::IsAllowed(GetIsolate()));
  int previous = READ_UINT32_FIELD(this, kKindSpecificFlags1Offset);
  int updated = MarkedForDeoptimizationField::update(previous, flag);
  WRITE_UINT32_FIELD(this, kKindSpecificFlags1Offset, updated);
}
 
 
bool Code::is_weak_stub() {
  return CanBeWeakStub() && WeakStubField::decode(
      READ_UINT32_FIELD(this, kKindSpecificFlags1Offset));
}
 
 
void Code::mark_as_weak_stub() {
  DCHECK(CanBeWeakStub());
  int previous = READ_UINT32_FIELD(this, kKindSpecificFlags1Offset);
  int updated = WeakStubField::update(previous, true);
  WRITE_UINT32_FIELD(this, kKindSpecificFlags1Offset, updated);
}
 
 
bool Code::is_invalidated_weak_stub() {
  return is_weak_stub() && InvalidatedWeakStubField::decode(
      READ_UINT32_FIELD(this, kKindSpecificFlags1Offset));
}
 
 
void Code::mark_as_invalidated_weak_stub() {
  DCHECK(is_inline_cache_stub());
  int previous = READ_UINT32_FIELD(this, kKindSpecificFlags1Offset);
  int updated = InvalidatedWeakStubField::update(previous, true);
  WRITE_UINT32_FIELD(this, kKindSpecificFlags1Offset, updated);
}
 
 
bool Code::is_inline_cache_stub() {
  Kind kind = this->kind();
  switch (kind) {
#define CASE(name) case name: return true;
    IC_KIND_LIST(CASE)
#undef CASE
    default: return false;
  }
}
 
 
bool Code::is_keyed_stub() {
  return is_keyed_load_stub() || is_keyed_store_stub();
}
 
 
bool Code::is_debug_stub() {
  return ic_state() == DEBUG_STUB;
}
 
 
ConstantPoolArray* Code::constant_pool() {
  return ConstantPoolArray::cast(READ_FIELD(this, kConstantPoolOffset));
}
 
 
void Code::set_constant_pool(Object* value) {
  DCHECK(value->IsConstantPoolArray());
  WRITE_FIELD(this, kConstantPoolOffset, value);
  WRITE_BARRIER(GetHeap(), this, kConstantPoolOffset, value);
}
 
 
Code::Flags Code::ComputeFlags(Kind kind, InlineCacheState ic_state,
                               ExtraICState extra_ic_state, StubType type,
                               CacheHolderFlag holder) {
  // Compute the bit mask.
  unsigned int bits = KindField::encode(kind)
      | ICStateField::encode(ic_state)
      | TypeField::encode(type)
      | ExtraICStateField::encode(extra_ic_state)
      | CacheHolderField::encode(holder);
  return static_cast<Flags>(bits);
}
 
 
Code::Flags Code::ComputeMonomorphicFlags(Kind kind,
                                          ExtraICState extra_ic_state,
                                          CacheHolderFlag holder,
                                          StubType type) {
  return ComputeFlags(kind, MONOMORPHIC, extra_ic_state, type, holder);
}
 
 
Code::Flags Code::ComputeHandlerFlags(Kind handler_kind, StubType type,
                                      CacheHolderFlag holder) {
  return ComputeFlags(Code::HANDLER, MONOMORPHIC, handler_kind, type, holder);
}
 
 
Code::Kind Code::ExtractKindFromFlags(Flags flags) {
  return KindField::decode(flags);
}
 
 
InlineCacheState Code::ExtractICStateFromFlags(Flags flags) {
  return ICStateField::decode(flags);
}
 
 
ExtraICState Code::ExtractExtraICStateFromFlags(Flags flags) {
  return ExtraICStateField::decode(flags);
}
 
 
Code::StubType Code::ExtractTypeFromFlags(Flags flags) {
  return TypeField::decode(flags);
}
 
 
CacheHolderFlag Code::ExtractCacheHolderFromFlags(Flags flags) {
  return CacheHolderField::decode(flags);
}
 
 
Code::Flags Code::RemoveTypeFromFlags(Flags flags) {
  int bits = flags & ~TypeField::kMask;
  return static_cast<Flags>(bits);
}
 
 
Code::Flags Code::RemoveTypeAndHolderFromFlags(Flags flags) {
  int bits = flags & ~TypeField::kMask & ~CacheHolderField::kMask;
  return static_cast<Flags>(bits);
}
 
 
Code* Code::GetCodeFromTargetAddress(Address address) {
  HeapObject* code = HeapObject::FromAddress(address - Code::kHeaderSize);
  // GetCodeFromTargetAddress might be called when marking objects during mark
  // sweep. reinterpret_cast is therefore used instead of the more appropriate
  // Code::cast. Code::cast does not work when the object's map is
  // marked.
  Code* result = reinterpret_cast<Code*>(code);
  return result;
}
 
 
Object* Code::GetObjectFromEntryAddress(Address location_of_address) {
  return HeapObject::
      FromAddress(Memory::Address_at(location_of_address) - Code::kHeaderSize);
}
 
 
bool Code::IsWeakObjectInOptimizedCode(Object* object) {
  if (!FLAG_collect_maps) return false;
  if (object->IsMap()) {
    return Map::cast(object)->CanTransition() &&
           FLAG_weak_embedded_maps_in_optimized_code;
  }
  if (object->IsJSObject() ||
      (object->IsCell() && Cell::cast(object)->value()->IsJSObject())) {
    return FLAG_weak_embedded_objects_in_optimized_code;
  }
  return false;
}
 
 
class Code::FindAndReplacePattern {
 public:
  FindAndReplacePattern() : count_(0) { }
  void Add(Handle<Map> map_to_find, Handle<Object> obj_to_replace) {
    DCHECK(count_ < kMaxCount);
    find_[count_] = map_to_find;
    replace_[count_] = obj_to_replace;
    ++count_;
  }
 private:
  static const int kMaxCount = 4;
  int count_;
  Handle<Map> find_[kMaxCount];
  Handle<Object> replace_[kMaxCount];
  friend class Code;
};
 
 
bool Code::IsWeakObjectInIC(Object* object) {
  return object->IsMap() && Map::cast(object)->CanTransition() &&
         FLAG_collect_maps &&
         FLAG_weak_embedded_maps_in_ic;
}
 
 
Object* Map::prototype() const {
  return READ_FIELD(this, kPrototypeOffset);
}
 
 
void Map::set_prototype(Object* value, WriteBarrierMode mode) {
  DCHECK(value->IsNull() || value->IsJSReceiver());
  WRITE_FIELD(this, kPrototypeOffset, value);
  CONDITIONAL_WRITE_BARRIER(GetHeap(), this, kPrototypeOffset, value, mode);
}
 
 
// If the descriptor is using the empty transition array, install a new empty
// transition array that will have place for an element transition.
static void EnsureHasTransitionArray(Handle<Map> map) {
  Handle<TransitionArray> transitions;
  if (!map->HasTransitionArray()) {
    transitions = TransitionArray::Allocate(map->GetIsolate(), 0);
    transitions->set_back_pointer_storage(map->GetBackPointer());
  } else if (!map->transitions()->IsFullTransitionArray()) {
    transitions = TransitionArray::ExtendToFullTransitionArray(map);
  } else {
    return;
  }
  map->set_transitions(*transitions);
}
 
 
void Map::InitializeDescriptors(DescriptorArray* descriptors) {
  int len = descriptors->number_of_descriptors();
  set_instance_descriptors(descriptors);
  SetNumberOfOwnDescriptors(len);
}
 
 
ACCESSORS(Map, instance_descriptors, DescriptorArray, kDescriptorsOffset)
 
 
void Map::set_bit_field3(uint32_t bits) {
  if (kInt32Size != kPointerSize) {
    WRITE_UINT32_FIELD(this, kBitField3Offset + kInt32Size, 0);
  }
  WRITE_UINT32_FIELD(this, kBitField3Offset, bits);
}
 
 
uint32_t Map::bit_field3() {
  return READ_UINT32_FIELD(this, kBitField3Offset);
}
 
 
void Map::AppendDescriptor(Descriptor* desc) {
  DescriptorArray* descriptors = instance_descriptors();
  int number_of_own_descriptors = NumberOfOwnDescriptors();
  DCHECK(descriptors->number_of_descriptors() == number_of_own_descriptors);
  descriptors->Append(desc);
  SetNumberOfOwnDescriptors(number_of_own_descriptors + 1);
}
 
 
Object* Map::GetBackPointer() {
  Object* object = READ_FIELD(this, kTransitionsOrBackPointerOffset);
  if (object->IsDescriptorArray()) {
    return TransitionArray::cast(object)->back_pointer_storage();
  } else {
    DCHECK(object->IsMap() || object->IsUndefined());
    return object;
  }
}
 
 
bool Map::HasElementsTransition() {
  return HasTransitionArray() && transitions()->HasElementsTransition();
}
 
 
bool Map::HasTransitionArray() const {
  Object* object = READ_FIELD(this, kTransitionsOrBackPointerOffset);
  return object->IsTransitionArray();
}
 
 
Map* Map::elements_transition_map() {
  int index = transitions()->Search(GetHeap()->elements_transition_symbol());
  return transitions()->GetTarget(index);
}
 
 
bool Map::CanHaveMoreTransitions() {
  if (!HasTransitionArray()) return true;
  return FixedArray::SizeFor(transitions()->length() +
                             TransitionArray::kTransitionSize)
      <= Page::kMaxRegularHeapObjectSize;
}
 
 
Map* Map::GetTransition(int transition_index) {
  return transitions()->GetTarget(transition_index);
}
 
 
int Map::SearchTransition(Name* name) {
  if (HasTransitionArray()) return transitions()->Search(name);
  return TransitionArray::kNotFound;
}
 
 
FixedArray* Map::GetPrototypeTransitions() {
  if (!HasTransitionArray()) return GetHeap()->empty_fixed_array();
  if (!transitions()->HasPrototypeTransitions()) {
    return GetHeap()->empty_fixed_array();
  }
  return transitions()->GetPrototypeTransitions();
}
 
 
void Map::SetPrototypeTransitions(
    Handle<Map> map, Handle<FixedArray> proto_transitions) {
  EnsureHasTransitionArray(map);
  int old_number_of_transitions = map->NumberOfProtoTransitions();
#ifdef DEBUG
  if (map->HasPrototypeTransitions()) {
    DCHECK(map->GetPrototypeTransitions() != *proto_transitions);
    map->ZapPrototypeTransitions();
  }
#endif
  map->transitions()->SetPrototypeTransitions(*proto_transitions);
  map->SetNumberOfProtoTransitions(old_number_of_transitions);
}
 
 
bool Map::HasPrototypeTransitions() {
  return HasTransitionArray() && transitions()->HasPrototypeTransitions();
}
 
 
TransitionArray* Map::transitions() const {
  DCHECK(HasTransitionArray());
  Object* object = READ_FIELD(this, kTransitionsOrBackPointerOffset);
  return TransitionArray::cast(object);
}
 
 
void Map::set_transitions(TransitionArray* transition_array,
                          WriteBarrierMode mode) {
  // Transition arrays are not shared. When one is replaced, it should not
  // keep referenced objects alive, so we zap it.
  // When there is another reference to the array somewhere (e.g. a handle),
  // not zapping turns from a waste of memory into a source of crashes.
  if (HasTransitionArray()) {
#ifdef DEBUG
    for (int i = 0; i < transitions()->number_of_transitions(); i++) {
      Map* target = transitions()->GetTarget(i);
      if (target->instance_descriptors() == instance_descriptors()) {
        Name* key = transitions()->GetKey(i);
        int new_target_index = transition_array->Search(key);
        DCHECK(new_target_index != TransitionArray::kNotFound);
        DCHECK(transition_array->GetTarget(new_target_index) == target);
      }
    }
#endif
    DCHECK(transitions() != transition_array);
    ZapTransitions();
  }
 
  WRITE_FIELD(this, kTransitionsOrBackPointerOffset, transition_array);
  CONDITIONAL_WRITE_BARRIER(
      GetHeap(), this, kTransitionsOrBackPointerOffset, transition_array, mode);
}
 
 
void Map::init_back_pointer(Object* undefined) {
  DCHECK(undefined->IsUndefined());
  WRITE_FIELD(this, kTransitionsOrBackPointerOffset, undefined);
}
 
 
void Map::SetBackPointer(Object* value, WriteBarrierMode mode) {
  DCHECK(instance_type() >= FIRST_JS_RECEIVER_TYPE);
  DCHECK((value->IsUndefined() && GetBackPointer()->IsMap()) ||
         (value->IsMap() && GetBackPointer()->IsUndefined()));
  Object* object = READ_FIELD(this, kTransitionsOrBackPointerOffset);
  if (object->IsTransitionArray()) {
    TransitionArray::cast(object)->set_back_pointer_storage(value);
  } else {
    WRITE_FIELD(this, kTransitionsOrBackPointerOffset, value);
    CONDITIONAL_WRITE_BARRIER(
        GetHeap(), this, kTransitionsOrBackPointerOffset, value, mode);
  }
}
 
 
ACCESSORS(Map, code_cache, Object, kCodeCacheOffset)
ACCESSORS(Map, dependent_code, DependentCode, kDependentCodeOffset)
ACCESSORS(Map, constructor, Object, kConstructorOffset)
 
ACCESSORS(JSFunction, shared, SharedFunctionInfo, kSharedFunctionInfoOffset)
ACCESSORS(JSFunction, literals_or_bindings, FixedArray, kLiteralsOffset)
ACCESSORS(JSFunction, next_function_link, Object, kNextFunctionLinkOffset)
 
ACCESSORS(GlobalObject, builtins, JSBuiltinsObject, kBuiltinsOffset)
ACCESSORS(GlobalObject, native_context, Context, kNativeContextOffset)
ACCESSORS(GlobalObject, global_context, Context, kGlobalContextOffset)
ACCESSORS(GlobalObject, global_proxy, JSObject, kGlobalProxyOffset)
 
ACCESSORS(JSGlobalProxy, native_context, Object, kNativeContextOffset)
ACCESSORS(JSGlobalProxy, hash, Object, kHashOffset)
 
ACCESSORS(AccessorInfo, name, Object, kNameOffset)
ACCESSORS_TO_SMI(AccessorInfo, flag, kFlagOffset)
ACCESSORS(AccessorInfo, expected_receiver_type, Object,
          kExpectedReceiverTypeOffset)
 
ACCESSORS(DeclaredAccessorDescriptor, serialized_data, ByteArray,
          kSerializedDataOffset)
 
ACCESSORS(DeclaredAccessorInfo, descriptor, DeclaredAccessorDescriptor,
          kDescriptorOffset)
 
ACCESSORS(ExecutableAccessorInfo, getter, Object, kGetterOffset)
ACCESSORS(ExecutableAccessorInfo, setter, Object, kSetterOffset)
ACCESSORS(ExecutableAccessorInfo, data, Object, kDataOffset)
 
ACCESSORS(Box, value, Object, kValueOffset)
 
ACCESSORS(AccessorPair, getter, Object, kGetterOffset)
ACCESSORS(AccessorPair, setter, Object, kSetterOffset)
 
ACCESSORS(AccessCheckInfo, named_callback, Object, kNamedCallbackOffset)
ACCESSORS(AccessCheckInfo, indexed_callback, Object, kIndexedCallbackOffset)
ACCESSORS(AccessCheckInfo, data, Object, kDataOffset)
 
ACCESSORS(InterceptorInfo, getter, Object, kGetterOffset)
ACCESSORS(InterceptorInfo, setter, Object, kSetterOffset)
ACCESSORS(InterceptorInfo, query, Object, kQueryOffset)
ACCESSORS(InterceptorInfo, deleter, Object, kDeleterOffset)
ACCESSORS(InterceptorInfo, enumerator, Object, kEnumeratorOffset)
ACCESSORS(InterceptorInfo, data, Object, kDataOffset)
 
ACCESSORS(CallHandlerInfo, callback, Object, kCallbackOffset)
ACCESSORS(CallHandlerInfo, data, Object, kDataOffset)
 
ACCESSORS(TemplateInfo, tag, Object, kTagOffset)
ACCESSORS(TemplateInfo, property_list, Object, kPropertyListOffset)
ACCESSORS(TemplateInfo, property_accessors, Object, kPropertyAccessorsOffset)
 
ACCESSORS(FunctionTemplateInfo, serial_number, Object, kSerialNumberOffset)
ACCESSORS(FunctionTemplateInfo, call_code, Object, kCallCodeOffset)
ACCESSORS(FunctionTemplateInfo, prototype_template, Object,
          kPrototypeTemplateOffset)
ACCESSORS(FunctionTemplateInfo, parent_template, Object, kParentTemplateOffset)
ACCESSORS(FunctionTemplateInfo, named_property_handler, Object,
          kNamedPropertyHandlerOffset)
ACCESSORS(FunctionTemplateInfo, indexed_property_handler, Object,
          kIndexedPropertyHandlerOffset)
ACCESSORS(FunctionTemplateInfo, instance_template, Object,
          kInstanceTemplateOffset)
ACCESSORS(FunctionTemplateInfo, class_name, Object, kClassNameOffset)
ACCESSORS(FunctionTemplateInfo, signature, Object, kSignatureOffset)
ACCESSORS(FunctionTemplateInfo, instance_call_handler, Object,
          kInstanceCallHandlerOffset)
ACCESSORS(FunctionTemplateInfo, access_check_info, Object,
          kAccessCheckInfoOffset)
ACCESSORS_TO_SMI(FunctionTemplateInfo, flag, kFlagOffset)
 
ACCESSORS(ObjectTemplateInfo, constructor, Object, kConstructorOffset)
ACCESSORS(ObjectTemplateInfo, internal_field_count, Object,
          kInternalFieldCountOffset)
 
ACCESSORS(SignatureInfo, receiver, Object, kReceiverOffset)
ACCESSORS(SignatureInfo, args, Object, kArgsOffset)
 
ACCESSORS(TypeSwitchInfo, types, Object, kTypesOffset)
 
ACCESSORS(AllocationSite, transition_info, Object, kTransitionInfoOffset)
ACCESSORS(AllocationSite, nested_site, Object, kNestedSiteOffset)
ACCESSORS_TO_SMI(AllocationSite, pretenure_data, kPretenureDataOffset)
ACCESSORS_TO_SMI(AllocationSite, pretenure_create_count,
                 kPretenureCreateCountOffset)
ACCESSORS(AllocationSite, dependent_code, DependentCode,
          kDependentCodeOffset)
ACCESSORS(AllocationSite, weak_next, Object, kWeakNextOffset)
ACCESSORS(AllocationMemento, allocation_site, Object, kAllocationSiteOffset)
 
ACCESSORS(Script, source, Object, kSourceOffset)
ACCESSORS(Script, name, Object, kNameOffset)
ACCESSORS(Script, id, Smi, kIdOffset)
ACCESSORS_TO_SMI(Script, line_offset, kLineOffsetOffset)
ACCESSORS_TO_SMI(Script, column_offset, kColumnOffsetOffset)
ACCESSORS(Script, context_data, Object, kContextOffset)
ACCESSORS(Script, wrapper, Foreign, kWrapperOffset)
ACCESSORS_TO_SMI(Script, type, kTypeOffset)
ACCESSORS(Script, line_ends, Object, kLineEndsOffset)
ACCESSORS(Script, eval_from_shared, Object, kEvalFromSharedOffset)
ACCESSORS_TO_SMI(Script, eval_from_instructions_offset,
                 kEvalFrominstructionsOffsetOffset)
ACCESSORS_TO_SMI(Script, flags, kFlagsOffset)
BOOL_ACCESSORS(Script, flags, is_shared_cross_origin, kIsSharedCrossOriginBit)
ACCESSORS(Script, source_url, Object, kSourceUrlOffset)
ACCESSORS(Script, source_mapping_url, Object, kSourceMappingUrlOffset)
 
Script::CompilationType Script::compilation_type() {
  return BooleanBit::get(flags(), kCompilationTypeBit) ?
      COMPILATION_TYPE_EVAL : COMPILATION_TYPE_HOST;
}
void Script::set_compilation_type(CompilationType type) {
  set_flags(BooleanBit::set(flags(), kCompilationTypeBit,
      type == COMPILATION_TYPE_EVAL));
}
Script::CompilationState Script::compilation_state() {
  return BooleanBit::get(flags(), kCompilationStateBit) ?
      COMPILATION_STATE_COMPILED : COMPILATION_STATE_INITIAL;
}
void Script::set_compilation_state(CompilationState state) {
  set_flags(BooleanBit::set(flags(), kCompilationStateBit,
      state == COMPILATION_STATE_COMPILED));
}
 
 
ACCESSORS(DebugInfo, shared, SharedFunctionInfo, kSharedFunctionInfoIndex)
ACCESSORS(DebugInfo, original_code, Code, kOriginalCodeIndex)
ACCESSORS(DebugInfo, code, Code, kPatchedCodeIndex)
ACCESSORS(DebugInfo, break_points, FixedArray, kBreakPointsStateIndex)
 
ACCESSORS_TO_SMI(BreakPointInfo, code_position, kCodePositionIndex)
ACCESSORS_TO_SMI(BreakPointInfo, source_position, kSourcePositionIndex)
ACCESSORS_TO_SMI(BreakPointInfo, statement_position, kStatementPositionIndex)
ACCESSORS(BreakPointInfo, break_point_objects, Object, kBreakPointObjectsIndex)
 
ACCESSORS(SharedFunctionInfo, name, Object, kNameOffset)
ACCESSORS(SharedFunctionInfo, optimized_code_map, Object,
                 kOptimizedCodeMapOffset)
ACCESSORS(SharedFunctionInfo, construct_stub, Code, kConstructStubOffset)
ACCESSORS(SharedFunctionInfo, feedback_vector, TypeFeedbackVector,
          kFeedbackVectorOffset)
ACCESSORS(SharedFunctionInfo, instance_class_name, Object,
          kInstanceClassNameOffset)
ACCESSORS(SharedFunctionInfo, function_data, Object, kFunctionDataOffset)
ACCESSORS(SharedFunctionInfo, script, Object, kScriptOffset)
ACCESSORS(SharedFunctionInfo, debug_info, Object, kDebugInfoOffset)
ACCESSORS(SharedFunctionInfo, inferred_name, String, kInferredNameOffset)
 
 
SMI_ACCESSORS(FunctionTemplateInfo, length, kLengthOffset)
BOOL_ACCESSORS(FunctionTemplateInfo, flag, hidden_prototype,
               kHiddenPrototypeBit)
BOOL_ACCESSORS(FunctionTemplateInfo, flag, undetectable, kUndetectableBit)
BOOL_ACCESSORS(FunctionTemplateInfo, flag, needs_access_check,
               kNeedsAccessCheckBit)
BOOL_ACCESSORS(FunctionTemplateInfo, flag, read_only_prototype,
               kReadOnlyPrototypeBit)
BOOL_ACCESSORS(FunctionTemplateInfo, flag, remove_prototype,
               kRemovePrototypeBit)
BOOL_ACCESSORS(FunctionTemplateInfo, flag, do_not_cache,
               kDoNotCacheBit)
BOOL_ACCESSORS(SharedFunctionInfo, start_position_and_type, is_expression,
               kIsExpressionBit)
BOOL_ACCESSORS(SharedFunctionInfo, start_position_and_type, is_toplevel,
               kIsTopLevelBit)
 
BOOL_ACCESSORS(SharedFunctionInfo,
               compiler_hints,
               allows_lazy_compilation,
               kAllowLazyCompilation)
BOOL_ACCESSORS(SharedFunctionInfo,
               compiler_hints,
               allows_lazy_compilation_without_context,
               kAllowLazyCompilationWithoutContext)
BOOL_ACCESSORS(SharedFunctionInfo,
               compiler_hints,
               uses_arguments,
               kUsesArguments)
BOOL_ACCESSORS(SharedFunctionInfo,
               compiler_hints,
               has_duplicate_parameters,
               kHasDuplicateParameters)
BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, asm_function, kIsAsmFunction)
 
 
#if V8_HOST_ARCH_32_BIT
SMI_ACCESSORS(SharedFunctionInfo, length, kLengthOffset)
SMI_ACCESSORS(SharedFunctionInfo, formal_parameter_count,
              kFormalParameterCountOffset)
SMI_ACCESSORS(SharedFunctionInfo, expected_nof_properties,
              kExpectedNofPropertiesOffset)
SMI_ACCESSORS(SharedFunctionInfo, num_literals, kNumLiteralsOffset)
SMI_ACCESSORS(SharedFunctionInfo, start_position_and_type,
              kStartPositionAndTypeOffset)
SMI_ACCESSORS(SharedFunctionInfo, end_position, kEndPositionOffset)
SMI_ACCESSORS(SharedFunctionInfo, function_token_position,
              kFunctionTokenPositionOffset)
SMI_ACCESSORS(SharedFunctionInfo, compiler_hints,
              kCompilerHintsOffset)
SMI_ACCESSORS(SharedFunctionInfo, opt_count_and_bailout_reason,
              kOptCountAndBailoutReasonOffset)
SMI_ACCESSORS(SharedFunctionInfo, counters, kCountersOffset)
SMI_ACCESSORS(SharedFunctionInfo, ast_node_count, kAstNodeCountOffset)
SMI_ACCESSORS(SharedFunctionInfo, profiler_ticks, kProfilerTicksOffset)
 
#else
 
#define PSEUDO_SMI_ACCESSORS_LO(holder, name, offset)             \
  STATIC_ASSERT(holder::offset % kPointerSize == 0);              \
  int holder::name() const {                                      \
    int value = READ_INT_FIELD(this, offset);                     \
    DCHECK(kHeapObjectTag == 1);                                  \
    DCHECK((value & kHeapObjectTag) == 0);                        \
    return value >> 1;                                            \
  }                                                               \
  void holder::set_##name(int value) {                            \
    DCHECK(kHeapObjectTag == 1);                                  \
    DCHECK((value & 0xC0000000) == 0xC0000000 ||                  \
           (value & 0xC0000000) == 0x0);                          \
    WRITE_INT_FIELD(this,                                         \
                    offset,                                       \
                    (value << 1) & ~kHeapObjectTag);              \
  }
 
#define PSEUDO_SMI_ACCESSORS_HI(holder, name, offset)             \
  STATIC_ASSERT(holder::offset % kPointerSize == kIntSize);       \
  INT_ACCESSORS(holder, name, offset)
 
 
PSEUDO_SMI_ACCESSORS_LO(SharedFunctionInfo, length, kLengthOffset)
PSEUDO_SMI_ACCESSORS_HI(SharedFunctionInfo,
                        formal_parameter_count,
                        kFormalParameterCountOffset)
 
PSEUDO_SMI_ACCESSORS_LO(SharedFunctionInfo,
                        expected_nof_properties,
                        kExpectedNofPropertiesOffset)
PSEUDO_SMI_ACCESSORS_HI(SharedFunctionInfo, num_literals, kNumLiteralsOffset)
 
PSEUDO_SMI_ACCESSORS_LO(SharedFunctionInfo, end_position, kEndPositionOffset)
PSEUDO_SMI_ACCESSORS_HI(SharedFunctionInfo,
                        start_position_and_type,
                        kStartPositionAndTypeOffset)
 
PSEUDO_SMI_ACCESSORS_LO(SharedFunctionInfo,
                        function_token_position,
                        kFunctionTokenPositionOffset)
PSEUDO_SMI_ACCESSORS_HI(SharedFunctionInfo,
                        compiler_hints,
                        kCompilerHintsOffset)
 
PSEUDO_SMI_ACCESSORS_LO(SharedFunctionInfo,
                        opt_count_and_bailout_reason,
                        kOptCountAndBailoutReasonOffset)
PSEUDO_SMI_ACCESSORS_HI(SharedFunctionInfo, counters, kCountersOffset)
 
PSEUDO_SMI_ACCESSORS_LO(SharedFunctionInfo,
                        ast_node_count,
                        kAstNodeCountOffset)
PSEUDO_SMI_ACCESSORS_HI(SharedFunctionInfo,
                        profiler_ticks,
                        kProfilerTicksOffset)
 
#endif
 
 
BOOL_GETTER(SharedFunctionInfo,
            compiler_hints,
            optimization_disabled,
            kOptimizationDisabled)
 
 
void SharedFunctionInfo::set_optimization_disabled(bool disable) {
  set_compiler_hints(BooleanBit::set(compiler_hints(),
                                     kOptimizationDisabled,
                                     disable));
  // If disabling optimizations we reflect that in the code object so
  // it will not be counted as optimizable code.
  if ((code()->kind() == Code::FUNCTION) && disable) {
    code()->set_optimizable(false);
  }
}
 
 
StrictMode SharedFunctionInfo::strict_mode() {
  return BooleanBit::get(compiler_hints(), kStrictModeFunction)
      ? STRICT : SLOPPY;
}
 
 
void SharedFunctionInfo::set_strict_mode(StrictMode strict_mode) {
  // We only allow mode transitions from sloppy to strict.
  DCHECK(this->strict_mode() == SLOPPY || this->strict_mode() == strict_mode);
  int hints = compiler_hints();
  hints = BooleanBit::set(hints, kStrictModeFunction, strict_mode == STRICT);
  set_compiler_hints(hints);
}
 
 
FunctionKind SharedFunctionInfo::kind() {
  return FunctionKindBits::decode(compiler_hints());
}
 
 
void SharedFunctionInfo::set_kind(FunctionKind kind) {
  DCHECK(IsValidFunctionKind(kind));
  int hints = compiler_hints();
  hints = FunctionKindBits::update(hints, kind);
  set_compiler_hints(hints);
}
 
 
BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, native, kNative)
BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, inline_builtin,
               kInlineBuiltin)
BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints,
               name_should_print_as_anonymous,
               kNameShouldPrintAsAnonymous)
BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, bound, kBoundFunction)
BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, is_anonymous, kIsAnonymous)
BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, is_function, kIsFunction)
BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, dont_cache, kDontCache)
BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, dont_flush, kDontFlush)
BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, is_arrow, kIsArrow)
BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, is_generator, kIsGenerator)
BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, is_concise_method,
               kIsConciseMethod)
 
ACCESSORS(CodeCache, default_cache, FixedArray, kDefaultCacheOffset)
ACCESSORS(CodeCache, normal_type_cache, Object, kNormalTypeCacheOffset)
 
ACCESSORS(PolymorphicCodeCache, cache, Object, kCacheOffset)
 
bool Script::HasValidSource() {
  Object* src = this->source();
  if (!src->IsString()) return true;
  String* src_str = String::cast(src);
  if (!StringShape(src_str).IsExternal()) return true;
  if (src_str->IsOneByteRepresentation()) {
    return ExternalOneByteString::cast(src)->resource() != NULL;
  } else if (src_str->IsTwoByteRepresentation()) {
    return ExternalTwoByteString::cast(src)->resource() != NULL;
  }
  return true;
}
 
 
void SharedFunctionInfo::DontAdaptArguments() {
  DCHECK(code()->kind() == Code::BUILTIN);
  set_formal_parameter_count(kDontAdaptArgumentsSentinel);
}
 
 
int SharedFunctionInfo::start_position() const {
  return start_position_and_type() >> kStartPositionShift;
}
 
 
void SharedFunctionInfo::set_start_position(int start_position) {
  set_start_position_and_type((start_position << kStartPositionShift)
    | (start_position_and_type() & ~kStartPositionMask));
}
 
 
Code* SharedFunctionInfo::code() const {
  return Code::cast(READ_FIELD(this, kCodeOffset));
}
 
 
void SharedFunctionInfo::set_code(Code* value, WriteBarrierMode mode) {
  DCHECK(value->kind() != Code::OPTIMIZED_FUNCTION);
  WRITE_FIELD(this, kCodeOffset, value);
  CONDITIONAL_WRITE_BARRIER(value->GetHeap(), this, kCodeOffset, value, mode);
}
 
 
void SharedFunctionInfo::ReplaceCode(Code* value) {
  // If the GC metadata field is already used then the function was
  // enqueued as a code flushing candidate and we remove it now.
  if (code()->gc_metadata() != NULL) {
    CodeFlusher* flusher = GetHeap()->mark_compact_collector()->code_flusher();
    flusher->EvictCandidate(this);
  }
 
  DCHECK(code()->gc_metadata() == NULL && value->gc_metadata() == NULL);
 
  set_code(value);
}
 
 
ScopeInfo* SharedFunctionInfo::scope_info() const {
  return reinterpret_cast<ScopeInfo*>(READ_FIELD(this, kScopeInfoOffset));
}
 
 
void SharedFunctionInfo::set_scope_info(ScopeInfo* value,
                                        WriteBarrierMode mode) {
  WRITE_FIELD(this, kScopeInfoOffset, reinterpret_cast<Object*>(value));
  CONDITIONAL_WRITE_BARRIER(GetHeap(),
                            this,
                            kScopeInfoOffset,
                            reinterpret_cast<Object*>(value),
                            mode);
}
 
 
bool SharedFunctionInfo::is_compiled() {
  return code() != GetIsolate()->builtins()->builtin(Builtins::kCompileLazy);
}
 
 
bool SharedFunctionInfo::IsApiFunction() {
  return function_data()->IsFunctionTemplateInfo();
}
 
 
FunctionTemplateInfo* SharedFunctionInfo::get_api_func_data() {
  DCHECK(IsApiFunction());
  return FunctionTemplateInfo::cast(function_data());
}
 
 
bool SharedFunctionInfo::HasBuiltinFunctionId() {
  return function_data()->IsSmi();
}
 
 
BuiltinFunctionId SharedFunctionInfo::builtin_function_id() {
  DCHECK(HasBuiltinFunctionId());
  return static_cast<BuiltinFunctionId>(Smi::cast(function_data())->value());
}
 
 
int SharedFunctionInfo::ic_age() {
  return ICAgeBits::decode(counters());
}
 
 
void SharedFunctionInfo::set_ic_age(int ic_age) {
  set_counters(ICAgeBits::update(counters(), ic_age));
}
 
 
int SharedFunctionInfo::deopt_count() {
  return DeoptCountBits::decode(counters());
}
 
 
void SharedFunctionInfo::set_deopt_count(int deopt_count) {
  set_counters(DeoptCountBits::update(counters(), deopt_count));
}
 
 
void SharedFunctionInfo::increment_deopt_count() {
  int value = counters();
  int deopt_count = DeoptCountBits::decode(value);
  deopt_count = (deopt_count + 1) & DeoptCountBits::kMax;
  set_counters(DeoptCountBits::update(value, deopt_count));
}
 
 
int SharedFunctionInfo::opt_reenable_tries() {
  return OptReenableTriesBits::decode(counters());
}
 
 
void SharedFunctionInfo::set_opt_reenable_tries(int tries) {
  set_counters(OptReenableTriesBits::update(counters(), tries));
}
 
 
int SharedFunctionInfo::opt_count() {
  return OptCountBits::decode(opt_count_and_bailout_reason());
}
 
 
void SharedFunctionInfo::set_opt_count(int opt_count) {
  set_opt_count_and_bailout_reason(
      OptCountBits::update(opt_count_and_bailout_reason(), opt_count));
}
 
 
BailoutReason SharedFunctionInfo::DisableOptimizationReason() {
  BailoutReason reason = static_cast<BailoutReason>(
      DisabledOptimizationReasonBits::decode(opt_count_and_bailout_reason()));
  return reason;
}
 
 
bool SharedFunctionInfo::has_deoptimization_support() {
  Code* code = this->code();
  return code->kind() == Code::FUNCTION && code->has_deoptimization_support();
}
 
 
void SharedFunctionInfo::TryReenableOptimization() {
  int tries = opt_reenable_tries();
  set_opt_reenable_tries((tries + 1) & OptReenableTriesBits::kMax);
  // We reenable optimization whenever the number of tries is a large
  // enough power of 2.
  if (tries >= 16 && (((tries - 1) & tries) == 0)) {
    set_optimization_disabled(false);
    set_opt_count(0);
    set_deopt_count(0);
    code()->set_optimizable(true);
  }
}
 
 
bool JSFunction::IsBuiltin() {
  return context()->global_object()->IsJSBuiltinsObject();
}
 
 
bool JSFunction::IsFromNativeScript() {
  Object* script = shared()->script();
  bool native = script->IsScript() &&
                Script::cast(script)->type()->value() == Script::TYPE_NATIVE;
  DCHECK(!IsBuiltin() || native);  // All builtins are also native.
  return native;
}
 
 
bool JSFunction::IsFromExtensionScript() {
  Object* script = shared()->script();
  return script->IsScript() &&
         Script::cast(script)->type()->value() == Script::TYPE_EXTENSION;
}
 
 
bool JSFunction::NeedsArgumentsAdaption() {
  return shared()->formal_parameter_count() !=
      SharedFunctionInfo::kDontAdaptArgumentsSentinel;
}
 
 
bool JSFunction::IsOptimized() {
  return code()->kind() == Code::OPTIMIZED_FUNCTION;
}
 
 
bool JSFunction::IsOptimizable() {
  return code()->kind() == Code::FUNCTION && code()->optimizable();
}
 
 
bool JSFunction::IsMarkedForOptimization() {
  return code() == GetIsolate()->builtins()->builtin(
      Builtins::kCompileOptimized);
}
 
 
bool JSFunction::IsMarkedForConcurrentOptimization() {
  return code() == GetIsolate()->builtins()->builtin(
      Builtins::kCompileOptimizedConcurrent);
}
 
 
bool JSFunction::IsInOptimizationQueue() {
  return code() == GetIsolate()->builtins()->builtin(
      Builtins::kInOptimizationQueue);
}
 
 
bool JSFunction::IsInobjectSlackTrackingInProgress() {
  return has_initial_map() &&
      initial_map()->construction_count() != JSFunction::kNoSlackTracking;
}
 
 
Code* JSFunction::code() {
  return Code::cast(
      Code::GetObjectFromEntryAddress(FIELD_ADDR(this, kCodeEntryOffset)));
}
 
 
void JSFunction::set_code(Code* value) {
  DCHECK(!GetHeap()->InNewSpace(value));
  Address entry = value->entry();
  WRITE_INTPTR_FIELD(this, kCodeEntryOffset, reinterpret_cast<intptr_t>(entry));
  GetHeap()->incremental_marking()->RecordWriteOfCodeEntry(
      this,
      HeapObject::RawField(this, kCodeEntryOffset),
      value);
}
 
 
void JSFunction::set_code_no_write_barrier(Code* value) {
  DCHECK(!GetHeap()->InNewSpace(value));
  Address entry = value->entry();
  WRITE_INTPTR_FIELD(this, kCodeEntryOffset, reinterpret_cast<intptr_t>(entry));
}
 
 
void JSFunction::ReplaceCode(Code* code) {
  bool was_optimized = IsOptimized();
  bool is_optimized = code->kind() == Code::OPTIMIZED_FUNCTION;
 
  if (was_optimized && is_optimized) {
    shared()->EvictFromOptimizedCodeMap(this->code(),
        "Replacing with another optimized code");
  }
 
  set_code(code);
 
  // Add/remove the function from the list of optimized functions for this
  // context based on the state change.
  if (!was_optimized && is_optimized) {
    context()->native_context()->AddOptimizedFunction(this);
  }
  if (was_optimized && !is_optimized) {
    // TODO(titzer): linear in the number of optimized functions; fix!
    context()->native_context()->RemoveOptimizedFunction(this);
  }
}
 
 
Context* JSFunction::context() {
  return Context::cast(READ_FIELD(this, kContextOffset));
}
 
 
JSObject* JSFunction::global_proxy() {
  return context()->global_proxy();
}
 
 
void JSFunction::set_context(Object* value) {
  DCHECK(value->IsUndefined() || value->IsContext());
  WRITE_FIELD(this, kContextOffset, value);
  WRITE_BARRIER(GetHeap(), this, kContextOffset, value);
}
 
ACCESSORS(JSFunction, prototype_or_initial_map, Object,
          kPrototypeOrInitialMapOffset)
 
 
Map* JSFunction::initial_map() {
  return Map::cast(prototype_or_initial_map());
}
 
 
bool JSFunction::has_initial_map() {
  return prototype_or_initial_map()->IsMap();
}
 
 
bool JSFunction::has_instance_prototype() {
  return has_initial_map() || !prototype_or_initial_map()->IsTheHole();
}
 
 
bool JSFunction::has_prototype() {
  return map()->has_non_instance_prototype() || has_instance_prototype();
}
 
 
Object* JSFunction::instance_prototype() {
  DCHECK(has_instance_prototype());
  if (has_initial_map()) return initial_map()->prototype();
  // When there is no initial map and the prototype is a JSObject, the
  // initial map field is used for the prototype field.
  return prototype_or_initial_map();
}
 
 
Object* JSFunction::prototype() {
  DCHECK(has_prototype());
  // If the function's prototype property has been set to a non-JSObject
  // value, that value is stored in the constructor field of the map.
  if (map()->has_non_instance_prototype()) return map()->constructor();
  return instance_prototype();
}
 
 
bool JSFunction::should_have_prototype() {
  return map()->function_with_prototype();
}
 
 
bool JSFunction::is_compiled() {
  return code() != GetIsolate()->builtins()->builtin(Builtins::kCompileLazy);
}
 
 
FixedArray* JSFunction::literals() {
  DCHECK(!shared()->bound());
  return literals_or_bindings();
}
 
 
void JSFunction::set_literals(FixedArray* literals) {
  DCHECK(!shared()->bound());
  set_literals_or_bindings(literals);
}
 
 
FixedArray* JSFunction::function_bindings() {
  DCHECK(shared()->bound());
  return literals_or_bindings();
}
 
 
void JSFunction::set_function_bindings(FixedArray* bindings) {
  DCHECK(shared()->bound());
  // Bound function literal may be initialized to the empty fixed array
  // before the bindings are set.
  DCHECK(bindings == GetHeap()->empty_fixed_array() ||
         bindings->map() == GetHeap()->fixed_cow_array_map());
  set_literals_or_bindings(bindings);
}
 
 
int JSFunction::NumberOfLiterals() {
  DCHECK(!shared()->bound());
  return literals()->length();
}
 
 
Object* JSBuiltinsObject::javascript_builtin(Builtins::JavaScript id) {
  DCHECK(id < kJSBuiltinsCount);  // id is unsigned.
  return READ_FIELD(this, OffsetOfFunctionWithId(id));
}
 
 
void JSBuiltinsObject::set_javascript_builtin(Builtins::JavaScript id,
                                              Object* value) {
  DCHECK(id < kJSBuiltinsCount);  // id is unsigned.
  WRITE_FIELD(this, OffsetOfFunctionWithId(id), value);
  WRITE_BARRIER(GetHeap(), this, OffsetOfFunctionWithId(id), value);
}
 
 
Code* JSBuiltinsObject::javascript_builtin_code(Builtins::JavaScript id) {
  DCHECK(id < kJSBuiltinsCount);  // id is unsigned.
  return Code::cast(READ_FIELD(this, OffsetOfCodeWithId(id)));
}
 
 
void JSBuiltinsObject::set_javascript_builtin_code(Builtins::JavaScript id,
                                                   Code* value) {
  DCHECK(id < kJSBuiltinsCount);  // id is unsigned.
  WRITE_FIELD(this, OffsetOfCodeWithId(id), value);
  DCHECK(!GetHeap()->InNewSpace(value));
}
 
 
ACCESSORS(JSProxy, handler, Object, kHandlerOffset)
ACCESSORS(JSProxy, hash, Object, kHashOffset)
ACCESSORS(JSFunctionProxy, call_trap, Object, kCallTrapOffset)
ACCESSORS(JSFunctionProxy, construct_trap, Object, kConstructTrapOffset)
 
 
void JSProxy::InitializeBody(int object_size, Object* value) {
  DCHECK(!value->IsHeapObject() || !GetHeap()->InNewSpace(value));
  for (int offset = kHeaderSize; offset < object_size; offset += kPointerSize) {
    WRITE_FIELD(this, offset, value);
  }
}
 
 
ACCESSORS(JSCollection, table, Object, kTableOffset)
 
 
#define ORDERED_HASH_TABLE_ITERATOR_ACCESSORS(name, type, offset)    \
  template<class Derived, class TableType>                           \
  type* OrderedHashTableIterator<Derived, TableType>::name() const { \
    return type::cast(READ_FIELD(this, offset));                     \
  }                                                                  \
  template<class Derived, class TableType>                           \
  void OrderedHashTableIterator<Derived, TableType>::set_##name(     \
      type* value, WriteBarrierMode mode) {                          \
    WRITE_FIELD(this, offset, value);                                \
    CONDITIONAL_WRITE_BARRIER(GetHeap(), this, offset, value, mode); \
  }
 
ORDERED_HASH_TABLE_ITERATOR_ACCESSORS(table, Object, kTableOffset)
ORDERED_HASH_TABLE_ITERATOR_ACCESSORS(index, Object, kIndexOffset)
ORDERED_HASH_TABLE_ITERATOR_ACCESSORS(kind, Object, kKindOffset)
 
#undef ORDERED_HASH_TABLE_ITERATOR_ACCESSORS
 
 
ACCESSORS(JSWeakCollection, table, Object, kTableOffset)
ACCESSORS(JSWeakCollection, next, Object, kNextOffset)
 
 
Address Foreign::foreign_address() {
  return AddressFrom<Address>(READ_INTPTR_FIELD(this, kForeignAddressOffset));
}
 
 
void Foreign::set_foreign_address(Address value) {
  WRITE_INTPTR_FIELD(this, kForeignAddressOffset, OffsetFrom(value));
}
 
 
ACCESSORS(JSGeneratorObject, function, JSFunction, kFunctionOffset)
ACCESSORS(JSGeneratorObject, context, Context, kContextOffset)
ACCESSORS(JSGeneratorObject, receiver, Object, kReceiverOffset)
SMI_ACCESSORS(JSGeneratorObject, continuation, kContinuationOffset)
ACCESSORS(JSGeneratorObject, operand_stack, FixedArray, kOperandStackOffset)
SMI_ACCESSORS(JSGeneratorObject, stack_handler_index, kStackHandlerIndexOffset)
 
bool JSGeneratorObject::is_suspended() {
  DCHECK_LT(kGeneratorExecuting, kGeneratorClosed);
  DCHECK_EQ(kGeneratorClosed, 0);
  return continuation() > 0;
}
 
bool JSGeneratorObject::is_closed() {
  return continuation() == kGeneratorClosed;
}
 
bool JSGeneratorObject::is_executing() {
  return continuation() == kGeneratorExecuting;
}
 
ACCESSORS(JSModule, context, Object, kContextOffset)
ACCESSORS(JSModule, scope_info, ScopeInfo, kScopeInfoOffset)
 
 
ACCESSORS(JSValue, value, Object, kValueOffset)
 
 
HeapNumber* HeapNumber::cast(Object* object) {
  SLOW_DCHECK(object->IsHeapNumber() || object->IsMutableHeapNumber());
  return reinterpret_cast<HeapNumber*>(object);
}
 
 
const HeapNumber* HeapNumber::cast(const Object* object) {
  SLOW_DCHECK(object->IsHeapNumber() || object->IsMutableHeapNumber());
  return reinterpret_cast<const HeapNumber*>(object);
}
 
 
ACCESSORS(JSDate, value, Object, kValueOffset)
ACCESSORS(JSDate, cache_stamp, Object, kCacheStampOffset)
ACCESSORS(JSDate, year, Object, kYearOffset)
ACCESSORS(JSDate, month, Object, kMonthOffset)
ACCESSORS(JSDate, day, Object, kDayOffset)
ACCESSORS(JSDate, weekday, Object, kWeekdayOffset)
ACCESSORS(JSDate, hour, Object, kHourOffset)
ACCESSORS(JSDate, min, Object, kMinOffset)
ACCESSORS(JSDate, sec, Object, kSecOffset)
 
 
ACCESSORS(JSMessageObject, type, String, kTypeOffset)
ACCESSORS(JSMessageObject, arguments, JSArray, kArgumentsOffset)
ACCESSORS(JSMessageObject, script, Object, kScriptOffset)
ACCESSORS(JSMessageObject, stack_frames, Object, kStackFramesOffset)
SMI_ACCESSORS(JSMessageObject, start_position, kStartPositionOffset)
SMI_ACCESSORS(JSMessageObject, end_position, kEndPositionOffset)
 
 
INT_ACCESSORS(Code, instruction_size, kInstructionSizeOffset)
INT_ACCESSORS(Code, prologue_offset, kPrologueOffset)
ACCESSORS(Code, relocation_info, ByteArray, kRelocationInfoOffset)
ACCESSORS(Code, handler_table, FixedArray, kHandlerTableOffset)
ACCESSORS(Code, deoptimization_data, FixedArray, kDeoptimizationDataOffset)
ACCESSORS(Code, raw_type_feedback_info, Object, kTypeFeedbackInfoOffset)
ACCESSORS(Code, next_code_link, Object, kNextCodeLinkOffset)
 
 
void Code::WipeOutHeader() {
  WRITE_FIELD(this, kRelocationInfoOffset, NULL);
  WRITE_FIELD(this, kHandlerTableOffset, NULL);
  WRITE_FIELD(this, kDeoptimizationDataOffset, NULL);
  WRITE_FIELD(this, kConstantPoolOffset, NULL);
  // Do not wipe out major/minor keys on a code stub or IC
  if (!READ_FIELD(this, kTypeFeedbackInfoOffset)->IsSmi()) {
    WRITE_FIELD(this, kTypeFeedbackInfoOffset, NULL);
  }
}
 
 
Object* Code::type_feedback_info() {
  DCHECK(kind() == FUNCTION);
  return raw_type_feedback_info();
}
 
 
void Code::set_type_feedback_info(Object* value, WriteBarrierMode mode) {
  DCHECK(kind() == FUNCTION);
  set_raw_type_feedback_info(value, mode);
  CONDITIONAL_WRITE_BARRIER(GetHeap(), this, kTypeFeedbackInfoOffset,
                            value, mode);
}
 
 
uint32_t Code::stub_key() {
  DCHECK(IsCodeStubOrIC());
  Smi* smi_key = Smi::cast(raw_type_feedback_info());
  return static_cast<uint32_t>(smi_key->value());
}
 
 
void Code::set_stub_key(uint32_t key) {
  DCHECK(IsCodeStubOrIC());
  set_raw_type_feedback_info(Smi::FromInt(key));
}
 
 
ACCESSORS(Code, gc_metadata, Object, kGCMetadataOffset)
INT_ACCESSORS(Code, ic_age, kICAgeOffset)
 
 
byte* Code::instruction_start()  {
  return FIELD_ADDR(this, kHeaderSize);
}
 
 
byte* Code::instruction_end()  {
  return instruction_start() + instruction_size();
}
 
 
int Code::body_size() {
  return RoundUp(instruction_size(), kObjectAlignment);
}
 
 
ByteArray* Code::unchecked_relocation_info() {
  return reinterpret_cast<ByteArray*>(READ_FIELD(this, kRelocationInfoOffset));
}
 
 
byte* Code::relocation_start() {
  return unchecked_relocation_info()->GetDataStartAddress();
}
 
 
int Code::relocation_size() {
  return unchecked_relocation_info()->length();
}
 
 
byte* Code::entry() {
  return instruction_start();
}
 
 
bool Code::contains(byte* inner_pointer) {
  return (address() <= inner_pointer) && (inner_pointer <= address() + Size());
}
 
 
ACCESSORS(JSArray, length, Object, kLengthOffset)
 
 
void* JSArrayBuffer::backing_store() const {
  intptr_t ptr = READ_INTPTR_FIELD(this, kBackingStoreOffset);
  return reinterpret_cast<void*>(ptr);
}
 
 
void JSArrayBuffer::set_backing_store(void* value, WriteBarrierMode mode) {
  intptr_t ptr = reinterpret_cast<intptr_t>(value);
  WRITE_INTPTR_FIELD(this, kBackingStoreOffset, ptr);
}
 
 
ACCESSORS(JSArrayBuffer, byte_length, Object, kByteLengthOffset)
ACCESSORS_TO_SMI(JSArrayBuffer, flag, kFlagOffset)
 
 
bool JSArrayBuffer::is_external() {
  return BooleanBit::get(flag(), kIsExternalBit);
}
 
 
void JSArrayBuffer::set_is_external(bool value) {
  set_flag(BooleanBit::set(flag(), kIsExternalBit, value));
}
 
 
bool JSArrayBuffer::should_be_freed() {
  return BooleanBit::get(flag(), kShouldBeFreed);
}
 
 
void JSArrayBuffer::set_should_be_freed(bool value) {
  set_flag(BooleanBit::set(flag(), kShouldBeFreed, value));
}
 
 
ACCESSORS(JSArrayBuffer, weak_next, Object, kWeakNextOffset)
ACCESSORS(JSArrayBuffer, weak_first_view, Object, kWeakFirstViewOffset)
 
 
ACCESSORS(JSArrayBufferView, buffer, Object, kBufferOffset)
ACCESSORS(JSArrayBufferView, byte_offset, Object, kByteOffsetOffset)
ACCESSORS(JSArrayBufferView, byte_length, Object, kByteLengthOffset)
ACCESSORS(JSArrayBufferView, weak_next, Object, kWeakNextOffset)
ACCESSORS(JSTypedArray, length, Object, kLengthOffset)
 
ACCESSORS(JSRegExp, data, Object, kDataOffset)
 
 
JSRegExp::Type JSRegExp::TypeTag() {
  Object* data = this->data();
  if (data->IsUndefined()) return JSRegExp::NOT_COMPILED;
  Smi* smi = Smi::cast(FixedArray::cast(data)->get(kTagIndex));
  return static_cast<JSRegExp::Type>(smi->value());
}
 
 
int JSRegExp::CaptureCount() {
  switch (TypeTag()) {
    case ATOM:
      return 0;
    case IRREGEXP:
      return Smi::cast(DataAt(kIrregexpCaptureCountIndex))->value();
    default:
      UNREACHABLE();
      return -1;
  }
}
 
 
JSRegExp::Flags JSRegExp::GetFlags() {
  DCHECK(this->data()->IsFixedArray());
  Object* data = this->data();
  Smi* smi = Smi::cast(FixedArray::cast(data)->get(kFlagsIndex));
  return Flags(smi->value());
}
 
 
String* JSRegExp::Pattern() {
  DCHECK(this->data()->IsFixedArray());
  Object* data = this->data();
  String* pattern= String::cast(FixedArray::cast(data)->get(kSourceIndex));
  return pattern;
}
 
 
Object* JSRegExp::DataAt(int index) {
  DCHECK(TypeTag() != NOT_COMPILED);
  return FixedArray::cast(data())->get(index);
}
 
 
void JSRegExp::SetDataAt(int index, Object* value) {
  DCHECK(TypeTag() != NOT_COMPILED);
  DCHECK(index >= kDataIndex);  // Only implementation data can be set this way.
  FixedArray::cast(data())->set(index, value);
}
 
 
ElementsKind JSObject::GetElementsKind() {
  ElementsKind kind = map()->elements_kind();
#if DEBUG
  FixedArrayBase* fixed_array =
      reinterpret_cast<FixedArrayBase*>(READ_FIELD(this, kElementsOffset));
 
  // If a GC was caused while constructing this object, the elements
  // pointer may point to a one pointer filler map.
  if (ElementsAreSafeToExamine()) {
    Map* map = fixed_array->map();
    DCHECK((IsFastSmiOrObjectElementsKind(kind) &&
            (map == GetHeap()->fixed_array_map() ||
             map == GetHeap()->fixed_cow_array_map())) ||
           (IsFastDoubleElementsKind(kind) &&
            (fixed_array->IsFixedDoubleArray() ||
             fixed_array == GetHeap()->empty_fixed_array())) ||
           (kind == DICTIONARY_ELEMENTS &&
            fixed_array->IsFixedArray() &&
            fixed_array->IsDictionary()) ||
           (kind > DICTIONARY_ELEMENTS));
    DCHECK((kind != SLOPPY_ARGUMENTS_ELEMENTS) ||
           (elements()->IsFixedArray() && elements()->length() >= 2));
  }
#endif
  return kind;
}
 
 
ElementsAccessor* JSObject::GetElementsAccessor() {
  return ElementsAccessor::ForKind(GetElementsKind());
}
 
 
bool JSObject::HasFastObjectElements() {
  return IsFastObjectElementsKind(GetElementsKind());
}
 
 
bool JSObject::HasFastSmiElements() {
  return IsFastSmiElementsKind(GetElementsKind());
}
 
 
bool JSObject::HasFastSmiOrObjectElements() {
  return IsFastSmiOrObjectElementsKind(GetElementsKind());
}
 
 
bool JSObject::HasFastDoubleElements() {
  return IsFastDoubleElementsKind(GetElementsKind());
}
 
 
bool JSObject::HasFastHoleyElements() {
  return IsFastHoleyElementsKind(GetElementsKind());
}
 
 
bool JSObject::HasFastElements() {
  return IsFastElementsKind(GetElementsKind());
}
 
 
bool JSObject::HasDictionaryElements() {
  return GetElementsKind() == DICTIONARY_ELEMENTS;
}
 
 
bool JSObject::HasSloppyArgumentsElements() {
  return GetElementsKind() == SLOPPY_ARGUMENTS_ELEMENTS;
}
 
 
bool JSObject::HasExternalArrayElements() {
  HeapObject* array = elements();
  DCHECK(array != NULL);
  return array->IsExternalArray();
}
 
 
#define EXTERNAL_ELEMENTS_CHECK(Type, type, TYPE, ctype, size)          \
bool JSObject::HasExternal##Type##Elements() {                          \
  HeapObject* array = elements();                                       \
  DCHECK(array != NULL);                                                \
  if (!array->IsHeapObject())                                           \
    return false;                                                       \
  return array->map()->instance_type() == EXTERNAL_##TYPE##_ARRAY_TYPE; \
}
 
TYPED_ARRAYS(EXTERNAL_ELEMENTS_CHECK)
 
#undef EXTERNAL_ELEMENTS_CHECK
 
 
bool JSObject::HasFixedTypedArrayElements() {
  HeapObject* array = elements();
  DCHECK(array != NULL);
  return array->IsFixedTypedArrayBase();
}
 
 
#define FIXED_TYPED_ELEMENTS_CHECK(Type, type, TYPE, ctype, size)         \
bool JSObject::HasFixed##Type##Elements() {                               \
  HeapObject* array = elements();                                         \
  DCHECK(array != NULL);                                                  \
  if (!array->IsHeapObject())                                             \
    return false;                                                         \
  return array->map()->instance_type() == FIXED_##TYPE##_ARRAY_TYPE;      \
}
 
TYPED_ARRAYS(FIXED_TYPED_ELEMENTS_CHECK)
 
#undef FIXED_TYPED_ELEMENTS_CHECK
 
 
bool JSObject::HasNamedInterceptor() {
  return map()->has_named_interceptor();
}
 
 
bool JSObject::HasIndexedInterceptor() {
  return map()->has_indexed_interceptor();
}
 
 
NameDictionary* JSObject::property_dictionary() {
  DCHECK(!HasFastProperties());
  return NameDictionary::cast(properties());
}
 
 
SeededNumberDictionary* JSObject::element_dictionary() {
  DCHECK(HasDictionaryElements());
  return SeededNumberDictionary::cast(elements());
}
 
 
bool Name::IsHashFieldComputed(uint32_t field) {
  return (field & kHashNotComputedMask) == 0;
}
 
 
bool Name::HasHashCode() {
  return IsHashFieldComputed(hash_field());
}
 
 
uint32_t Name::Hash() {
  // Fast case: has hash code already been computed?
  uint32_t field = hash_field();
  if (IsHashFieldComputed(field)) return field >> kHashShift;
  // Slow case: compute hash code and set it. Has to be a string.
  return String::cast(this)->ComputeAndSetHash();
}
 
bool Name::IsOwn() {
  return this->IsSymbol() && Symbol::cast(this)->is_own();
}
 
 
StringHasher::StringHasher(int length, uint32_t seed)
  : length_(length),
    raw_running_hash_(seed),
    array_index_(0),
    is_array_index_(0 < length_ && length_ <= String::kMaxArrayIndexSize),
    is_first_char_(true) {
  DCHECK(FLAG_randomize_hashes || raw_running_hash_ == 0);
}
 
 
bool StringHasher::has_trivial_hash() {
  return length_ > String::kMaxHashCalcLength;
}
 
 
uint32_t StringHasher::AddCharacterCore(uint32_t running_hash, uint16_t c) {
  running_hash += c;
  running_hash += (running_hash << 10);
  running_hash ^= (running_hash >> 6);
  return running_hash;
}
 
 
uint32_t StringHasher::GetHashCore(uint32_t running_hash) {
  running_hash += (running_hash << 3);
  running_hash ^= (running_hash >> 11);
  running_hash += (running_hash << 15);
  if ((running_hash & String::kHashBitMask) == 0) {
    return kZeroHash;
  }
  return running_hash;
}
 
 
void StringHasher::AddCharacter(uint16_t c) {
  // Use the Jenkins one-at-a-time hash function to update the hash
  // for the given character.
  raw_running_hash_ = AddCharacterCore(raw_running_hash_, c);
}
 
 
bool StringHasher::UpdateIndex(uint16_t c) {
  DCHECK(is_array_index_);
  if (c < '0' || c > '9') {
    is_array_index_ = false;
    return false;
  }
  int d = c - '0';
  if (is_first_char_) {
    is_first_char_ = false;
    if (c == '0' && length_ > 1) {
      is_array_index_ = false;
      return false;
    }
  }
  if (array_index_ > 429496729U - ((d + 2) >> 3)) {
    is_array_index_ = false;
    return false;
  }
  array_index_ = array_index_ * 10 + d;
  return true;
}
 
 
template<typename Char>
inline void StringHasher::AddCharacters(const Char* chars, int length) {
  DCHECK(sizeof(Char) == 1 || sizeof(Char) == 2);
  int i = 0;
  if (is_array_index_) {
    for (; i < length; i++) {
      AddCharacter(chars[i]);
      if (!UpdateIndex(chars[i])) {
        i++;
        break;
      }
    }
  }
  for (; i < length; i++) {
    DCHECK(!is_array_index_);
    AddCharacter(chars[i]);
  }
}
 
 
template <typename schar>
uint32_t StringHasher::HashSequentialString(const schar* chars,
                                            int length,
                                            uint32_t seed) {
  StringHasher hasher(length, seed);
  if (!hasher.has_trivial_hash()) hasher.AddCharacters(chars, length);
  return hasher.GetHashField();
}
 
 
uint32_t IteratingStringHasher::Hash(String* string, uint32_t seed) {
  IteratingStringHasher hasher(string->length(), seed);
  // Nothing to do.
  if (hasher.has_trivial_hash()) return hasher.GetHashField();
  ConsString* cons_string = String::VisitFlat(&hasher, string);
  // The string was flat.
  if (cons_string == NULL) return hasher.GetHashField();
  // This is a ConsString, iterate across it.
  ConsStringIteratorOp op(cons_string);
  int offset;
  while (NULL != (string = op.Next(&offset))) {
    String::VisitFlat(&hasher, string, offset);
  }
  return hasher.GetHashField();
}
 
 
void IteratingStringHasher::VisitOneByteString(const uint8_t* chars,
                                               int length) {
  AddCharacters(chars, length);
}
 
 
void IteratingStringHasher::VisitTwoByteString(const uint16_t* chars,
                                               int length) {
  AddCharacters(chars, length);
}
 
 
bool Name::AsArrayIndex(uint32_t* index) {
  return IsString() && String::cast(this)->AsArrayIndex(index);
}
 
 
bool String::AsArrayIndex(uint32_t* index) {
  uint32_t field = hash_field();
  if (IsHashFieldComputed(field) && (field & kIsNotArrayIndexMask)) {
    return false;
  }
  return SlowAsArrayIndex(index);
}
 
 
void String::SetForwardedInternalizedString(String* canonical) {
  DCHECK(IsInternalizedString());
  DCHECK(HasHashCode());
  if (canonical == this) return;  // No need to forward.
  DCHECK(SlowEquals(canonical));
  DCHECK(canonical->IsInternalizedString());
  DCHECK(canonical->HasHashCode());
  WRITE_FIELD(this, kHashFieldOffset, canonical);
  // Setting the hash field to a tagged value sets the LSB, causing the hash
  // code to be interpreted as uninitialized.  We use this fact to recognize
  // that we have a forwarded string.
  DCHECK(!HasHashCode());
}
 
 
String* String::GetForwardedInternalizedString() {
  DCHECK(IsInternalizedString());
  if (HasHashCode()) return this;
  String* canonical = String::cast(READ_FIELD(this, kHashFieldOffset));
  DCHECK(canonical->IsInternalizedString());
  DCHECK(SlowEquals(canonical));
  DCHECK(canonical->HasHashCode());
  return canonical;
}
 
 
Object* JSReceiver::GetConstructor() {
  return map()->constructor();
}
 
 
Maybe<bool> JSReceiver::HasProperty(Handle<JSReceiver> object,
                                    Handle<Name> name) {
  if (object->IsJSProxy()) {
    Handle<JSProxy> proxy = Handle<JSProxy>::cast(object);
    return JSProxy::HasPropertyWithHandler(proxy, name);
  }
  Maybe<PropertyAttributes> result = GetPropertyAttributes(object, name);
  if (!result.has_value) return Maybe<bool>();
  return maybe(result.value != ABSENT);
}
 
 
Maybe<bool> JSReceiver::HasOwnProperty(Handle<JSReceiver> object,
                                       Handle<Name> name) {
  if (object->IsJSProxy()) {
    Handle<JSProxy> proxy = Handle<JSProxy>::cast(object);
    return JSProxy::HasPropertyWithHandler(proxy, name);
  }
  Maybe<PropertyAttributes> result = GetOwnPropertyAttributes(object, name);
  if (!result.has_value) return Maybe<bool>();
  return maybe(result.value != ABSENT);
}
 
 
Maybe<PropertyAttributes> JSReceiver::GetPropertyAttributes(
    Handle<JSReceiver> object, Handle<Name> key) {
  uint32_t index;
  if (object->IsJSObject() && key->AsArrayIndex(&index)) {
    return GetElementAttribute(object, index);
  }
  LookupIterator it(object, key);
  return GetPropertyAttributes(&it);
}
 
 
Maybe<PropertyAttributes> JSReceiver::GetElementAttribute(
    Handle<JSReceiver> object, uint32_t index) {
  if (object->IsJSProxy()) {
    return JSProxy::GetElementAttributeWithHandler(
        Handle<JSProxy>::cast(object), object, index);
  }
  return JSObject::GetElementAttributeWithReceiver(
      Handle<JSObject>::cast(object), object, index, true);
}
 
 
bool JSGlobalObject::IsDetached() {
  return JSGlobalProxy::cast(global_proxy())->IsDetachedFrom(this);
}
 
 
bool JSGlobalProxy::IsDetachedFrom(GlobalObject* global) const {
  const PrototypeIterator iter(this->GetIsolate(),
                               const_cast<JSGlobalProxy*>(this));
  return iter.GetCurrent() != global;
}
 
 
Handle<Smi> JSReceiver::GetOrCreateIdentityHash(Handle<JSReceiver> object) {
  return object->IsJSProxy()
      ? JSProxy::GetOrCreateIdentityHash(Handle<JSProxy>::cast(object))
      : JSObject::GetOrCreateIdentityHash(Handle<JSObject>::cast(object));
}
 
 
Object* JSReceiver::GetIdentityHash() {
  return IsJSProxy()
      ? JSProxy::cast(this)->GetIdentityHash()
      : JSObject::cast(this)->GetIdentityHash();
}
 
 
Maybe<bool> JSReceiver::HasElement(Handle<JSReceiver> object, uint32_t index) {
  if (object->IsJSProxy()) {
    Handle<JSProxy> proxy = Handle<JSProxy>::cast(object);
    return JSProxy::HasElementWithHandler(proxy, index);
  }
  Maybe<PropertyAttributes> result = JSObject::GetElementAttributeWithReceiver(
      Handle<JSObject>::cast(object), object, index, true);
  if (!result.has_value) return Maybe<bool>();
  return maybe(result.value != ABSENT);
}
 
 
Maybe<bool> JSReceiver::HasOwnElement(Handle<JSReceiver> object,
                                      uint32_t index) {
  if (object->IsJSProxy()) {
    Handle<JSProxy> proxy = Handle<JSProxy>::cast(object);
    return JSProxy::HasElementWithHandler(proxy, index);
  }
  Maybe<PropertyAttributes> result = JSObject::GetElementAttributeWithReceiver(
      Handle<JSObject>::cast(object), object, index, false);
  if (!result.has_value) return Maybe<bool>();
  return maybe(result.value != ABSENT);
}
 
 
Maybe<PropertyAttributes> JSReceiver::GetOwnElementAttribute(
    Handle<JSReceiver> object, uint32_t index) {
  if (object->IsJSProxy()) {
    return JSProxy::GetElementAttributeWithHandler(
        Handle<JSProxy>::cast(object), object, index);
  }
  return JSObject::GetElementAttributeWithReceiver(
      Handle<JSObject>::cast(object), object, index, false);
}
 
 
bool AccessorInfo::all_can_read() {
  return BooleanBit::get(flag(), kAllCanReadBit);
}
 
 
void AccessorInfo::set_all_can_read(bool value) {
  set_flag(BooleanBit::set(flag(), kAllCanReadBit, value));
}
 
 
bool AccessorInfo::all_can_write() {
  return BooleanBit::get(flag(), kAllCanWriteBit);
}
 
 
void AccessorInfo::set_all_can_write(bool value) {
  set_flag(BooleanBit::set(flag(), kAllCanWriteBit, value));
}
 
 
PropertyAttributes AccessorInfo::property_attributes() {
  return AttributesField::decode(static_cast<uint32_t>(flag()->value()));
}
 
 
void AccessorInfo::set_property_attributes(PropertyAttributes attributes) {
  set_flag(Smi::FromInt(AttributesField::update(flag()->value(), attributes)));
}
 
 
bool AccessorInfo::IsCompatibleReceiver(Object* receiver) {
  if (!HasExpectedReceiverType()) return true;
  if (!receiver->IsJSObject()) return false;
  return FunctionTemplateInfo::cast(expected_receiver_type())
      ->IsTemplateFor(JSObject::cast(receiver)->map());
}
 
 
void ExecutableAccessorInfo::clear_setter() {
  set_setter(GetIsolate()->heap()->undefined_value(), SKIP_WRITE_BARRIER);
}
 
 
template<typename Derived, typename Shape, typename Key>
void Dictionary<Derived, Shape, Key>::SetEntry(int entry,
                                               Handle<Object> key,
                                               Handle<Object> value) {
  SetEntry(entry, key, value, PropertyDetails(Smi::FromInt(0)));
}
 
 
template<typename Derived, typename Shape, typename Key>
void Dictionary<Derived, Shape, Key>::SetEntry(int entry,
                                               Handle<Object> key,
                                               Handle<Object> value,
                                               PropertyDetails details) {
  DCHECK(!key->IsName() ||
         details.IsDeleted() ||
         details.dictionary_index() > 0);
  int index = DerivedHashTable::EntryToIndex(entry);
  DisallowHeapAllocation no_gc;
  WriteBarrierMode mode = FixedArray::GetWriteBarrierMode(no_gc);
  FixedArray::set(index, *key, mode);
  FixedArray::set(index+1, *value, mode);
  FixedArray::set(index+2, details.AsSmi());
}
 
 
bool NumberDictionaryShape::IsMatch(uint32_t key, Object* other) {
  DCHECK(other->IsNumber());
  return key == static_cast<uint32_t>(other->Number());
}
 
 
uint32_t UnseededNumberDictionaryShape::Hash(uint32_t key) {
  return ComputeIntegerHash(key, 0);
}
 
 
uint32_t UnseededNumberDictionaryShape::HashForObject(uint32_t key,
                                                      Object* other) {
  DCHECK(other->IsNumber());
  return ComputeIntegerHash(static_cast<uint32_t>(other->Number()), 0);
}
 
 
uint32_t SeededNumberDictionaryShape::SeededHash(uint32_t key, uint32_t seed) {
  return ComputeIntegerHash(key, seed);
}
 
 
uint32_t SeededNumberDictionaryShape::SeededHashForObject(uint32_t key,
                                                          uint32_t seed,
                                                          Object* other) {
  DCHECK(other->IsNumber());
  return ComputeIntegerHash(static_cast<uint32_t>(other->Number()), seed);
}
 
 
Handle<Object> NumberDictionaryShape::AsHandle(Isolate* isolate, uint32_t key) {
  return isolate->factory()->NewNumberFromUint(key);
}
 
 
bool NameDictionaryShape::IsMatch(Handle<Name> key, Object* other) {
  // We know that all entries in a hash table had their hash keys created.
  // Use that knowledge to have fast failure.
  if (key->Hash() != Name::cast(other)->Hash()) return false;
  return key->Equals(Name::cast(other));
}
 
 
uint32_t NameDictionaryShape::Hash(Handle<Name> key) {
  return key->Hash();
}
 
 
uint32_t NameDictionaryShape::HashForObject(Handle<Name> key, Object* other) {
  return Name::cast(other)->Hash();
}
 
 
Handle<Object> NameDictionaryShape::AsHandle(Isolate* isolate,
                                             Handle<Name> key) {
  DCHECK(key->IsUniqueName());
  return key;
}
 
 
void NameDictionary::DoGenerateNewEnumerationIndices(
    Handle<NameDictionary> dictionary) {
  DerivedDictionary::GenerateNewEnumerationIndices(dictionary);
}
 
 
bool ObjectHashTableShape::IsMatch(Handle<Object> key, Object* other) {
  return key->SameValue(other);
}
 
 
uint32_t ObjectHashTableShape::Hash(Handle<Object> key) {
  return Smi::cast(key->GetHash())->value();
}
 
 
uint32_t ObjectHashTableShape::HashForObject(Handle<Object> key,
                                             Object* other) {
  return Smi::cast(other->GetHash())->value();
}
 
 
Handle<Object> ObjectHashTableShape::AsHandle(Isolate* isolate,
                                              Handle<Object> key) {
  return key;
}
 
 
Handle<ObjectHashTable> ObjectHashTable::Shrink(
    Handle<ObjectHashTable> table, Handle<Object> key) {
  return DerivedHashTable::Shrink(table, key);
}
 
 
template <int entrysize>
bool WeakHashTableShape<entrysize>::IsMatch(Handle<Object> key, Object* other) {
  return key->SameValue(other);
}
 
 
template <int entrysize>
uint32_t WeakHashTableShape<entrysize>::Hash(Handle<Object> key) {
  intptr_t hash = reinterpret_cast<intptr_t>(*key);
  return (uint32_t)(hash & 0xFFFFFFFF);
}
 
 
template <int entrysize>
uint32_t WeakHashTableShape<entrysize>::HashForObject(Handle<Object> key,
                                                      Object* other) {
  intptr_t hash = reinterpret_cast<intptr_t>(other);
  return (uint32_t)(hash & 0xFFFFFFFF);
}
 
 
template <int entrysize>
Handle<Object> WeakHashTableShape<entrysize>::AsHandle(Isolate* isolate,
                                                       Handle<Object> key) {
  return key;
}
 
 
void Map::ClearCodeCache(Heap* heap) {
  // No write barrier is needed since empty_fixed_array is not in new space.
  // Please note this function is used during marking:
  //  - MarkCompactCollector::MarkUnmarkedObject
  //  - IncrementalMarking::Step
  DCHECK(!heap->InNewSpace(heap->empty_fixed_array()));
  WRITE_FIELD(this, kCodeCacheOffset, heap->empty_fixed_array());
}
 
 
void JSArray::EnsureSize(Handle<JSArray> array, int required_size) {
  DCHECK(array->HasFastSmiOrObjectElements());
  Handle<FixedArray> elts = handle(FixedArray::cast(array->elements()));
  const int kArraySizeThatFitsComfortablyInNewSpace = 128;
  if (elts->length() < required_size) {
    // Doubling in size would be overkill, but leave some slack to avoid
    // constantly growing.
    Expand(array, required_size + (required_size >> 3));
    // It's a performance benefit to keep a frequently used array in new-space.
  } else if (!array->GetHeap()->new_space()->Contains(*elts) &&
             required_size < kArraySizeThatFitsComfortablyInNewSpace) {
    // Expand will allocate a new backing store in new space even if the size
    // we asked for isn't larger than what we had before.
    Expand(array, required_size);
  }
}
 
 
void JSArray::set_length(Smi* length) {
  // Don't need a write barrier for a Smi.
  set_length(static_cast<Object*>(length), SKIP_WRITE_BARRIER);
}
 
 
bool JSArray::AllowsSetElementsLength() {
  bool result = elements()->IsFixedArray() || elements()->IsFixedDoubleArray();
  DCHECK(result == !HasExternalArrayElements());
  return result;
}
 
 
void JSArray::SetContent(Handle<JSArray> array,
                         Handle<FixedArrayBase> storage) {
  EnsureCanContainElements(array, storage, storage->length(),
                           ALLOW_COPIED_DOUBLE_ELEMENTS);
 
  DCHECK((storage->map() == array->GetHeap()->fixed_double_array_map() &&
          IsFastDoubleElementsKind(array->GetElementsKind())) ||
         ((storage->map() != array->GetHeap()->fixed_double_array_map()) &&
          (IsFastObjectElementsKind(array->GetElementsKind()) ||
           (IsFastSmiElementsKind(array->GetElementsKind()) &&
            Handle<FixedArray>::cast(storage)->ContainsOnlySmisOrHoles()))));
  array->set_elements(*storage);
  array->set_length(Smi::FromInt(storage->length()));
}
 
 
int TypeFeedbackInfo::ic_total_count() {
  int current = Smi::cast(READ_FIELD(this, kStorage1Offset))->value();
  return ICTotalCountField::decode(current);
}
 
 
void TypeFeedbackInfo::set_ic_total_count(int count) {
  int value = Smi::cast(READ_FIELD(this, kStorage1Offset))->value();
  value = ICTotalCountField::update(value,
                                    ICTotalCountField::decode(count));
  WRITE_FIELD(this, kStorage1Offset, Smi::FromInt(value));
}
 
 
int TypeFeedbackInfo::ic_with_type_info_count() {
  int current = Smi::cast(READ_FIELD(this, kStorage2Offset))->value();
  return ICsWithTypeInfoCountField::decode(current);
}
 
 
void TypeFeedbackInfo::change_ic_with_type_info_count(int delta) {
  if (delta == 0) return;
  int value = Smi::cast(READ_FIELD(this, kStorage2Offset))->value();
  int new_count = ICsWithTypeInfoCountField::decode(value) + delta;
  // We can get negative count here when the type-feedback info is
  // shared between two code objects. The can only happen when
  // the debugger made a shallow copy of code object (see Heap::CopyCode).
  // Since we do not optimize when the debugger is active, we can skip
  // this counter update.
  if (new_count >= 0) {
    new_count &= ICsWithTypeInfoCountField::kMask;
    value = ICsWithTypeInfoCountField::update(value, new_count);
    WRITE_FIELD(this, kStorage2Offset, Smi::FromInt(value));
  }
}
 
 
int TypeFeedbackInfo::ic_generic_count() {
  return Smi::cast(READ_FIELD(this, kStorage3Offset))->value();
}
 
 
void TypeFeedbackInfo::change_ic_generic_count(int delta) {
  if (delta == 0) return;
  int new_count = ic_generic_count() + delta;
  if (new_count >= 0) {
    new_count &= ~Smi::kMinValue;
    WRITE_FIELD(this, kStorage3Offset, Smi::FromInt(new_count));
  }
}
 
 
void TypeFeedbackInfo::initialize_storage() {
  WRITE_FIELD(this, kStorage1Offset, Smi::FromInt(0));
  WRITE_FIELD(this, kStorage2Offset, Smi::FromInt(0));
  WRITE_FIELD(this, kStorage3Offset, Smi::FromInt(0));
}
 
 
void TypeFeedbackInfo::change_own_type_change_checksum() {
  int value = Smi::cast(READ_FIELD(this, kStorage1Offset))->value();
  int checksum = OwnTypeChangeChecksum::decode(value);
  checksum = (checksum + 1) % (1 << kTypeChangeChecksumBits);
  value = OwnTypeChangeChecksum::update(value, checksum);
  // Ensure packed bit field is in Smi range.
  if (value > Smi::kMaxValue) value |= Smi::kMinValue;
  if (value < Smi::kMinValue) value &= ~Smi::kMinValue;
  WRITE_FIELD(this, kStorage1Offset, Smi::FromInt(value));
}
 
 
void TypeFeedbackInfo::set_inlined_type_change_checksum(int checksum) {
  int value = Smi::cast(READ_FIELD(this, kStorage2Offset))->value();
  int mask = (1 << kTypeChangeChecksumBits) - 1;
  value = InlinedTypeChangeChecksum::update(value, checksum & mask);
  // Ensure packed bit field is in Smi range.
  if (value > Smi::kMaxValue) value |= Smi::kMinValue;
  if (value < Smi::kMinValue) value &= ~Smi::kMinValue;
  WRITE_FIELD(this, kStorage2Offset, Smi::FromInt(value));
}
 
 
int TypeFeedbackInfo::own_type_change_checksum() {
  int value = Smi::cast(READ_FIELD(this, kStorage1Offset))->value();
  return OwnTypeChangeChecksum::decode(value);
}
 
 
bool TypeFeedbackInfo::matches_inlined_type_change_checksum(int checksum) {
  int value = Smi::cast(READ_FIELD(this, kStorage2Offset))->value();
  int mask = (1 << kTypeChangeChecksumBits) - 1;
  return InlinedTypeChangeChecksum::decode(value) == (checksum & mask);
}
 
 
SMI_ACCESSORS(AliasedArgumentsEntry, aliased_context_slot, kAliasedContextSlot)
 
 
Relocatable::Relocatable(Isolate* isolate) {
  isolate_ = isolate;
  prev_ = isolate->relocatable_top();
  isolate->set_relocatable_top(this);
}
 
 
Relocatable::~Relocatable() {
  DCHECK_EQ(isolate_->relocatable_top(), this);
  isolate_->set_relocatable_top(prev_);
}
 
 
int JSObject::BodyDescriptor::SizeOf(Map* map, HeapObject* object) {
  return map->instance_size();
}
 
 
void Foreign::ForeignIterateBody(ObjectVisitor* v) {
  v->VisitExternalReference(
      reinterpret_cast<Address*>(FIELD_ADDR(this, kForeignAddressOffset)));
}
 
 
template<typename StaticVisitor>
void Foreign::ForeignIterateBody() {
  StaticVisitor::VisitExternalReference(
      reinterpret_cast<Address*>(FIELD_ADDR(this, kForeignAddressOffset)));
}
 
 
void ExternalOneByteString::ExternalOneByteStringIterateBody(ObjectVisitor* v) {
  typedef v8::String::ExternalOneByteStringResource Resource;
  v->VisitExternalOneByteString(
      reinterpret_cast<Resource**>(FIELD_ADDR(this, kResourceOffset)));
}
 
 
template <typename StaticVisitor>
void ExternalOneByteString::ExternalOneByteStringIterateBody() {
  typedef v8::String::ExternalOneByteStringResource Resource;
  StaticVisitor::VisitExternalOneByteString(
      reinterpret_cast<Resource**>(FIELD_ADDR(this, kResourceOffset)));
}
 
 
void ExternalTwoByteString::ExternalTwoByteStringIterateBody(ObjectVisitor* v) {
  typedef v8::String::ExternalStringResource Resource;
  v->VisitExternalTwoByteString(
      reinterpret_cast<Resource**>(FIELD_ADDR(this, kResourceOffset)));
}
 
 
template<typename StaticVisitor>
void ExternalTwoByteString::ExternalTwoByteStringIterateBody() {
  typedef v8::String::ExternalStringResource Resource;
  StaticVisitor::VisitExternalTwoByteString(
      reinterpret_cast<Resource**>(FIELD_ADDR(this, kResourceOffset)));
}
 
 
template<int start_offset, int end_offset, int size>
void FixedBodyDescriptor<start_offset, end_offset, size>::IterateBody(
    HeapObject* obj,
    ObjectVisitor* v) {
    v->VisitPointers(HeapObject::RawField(obj, start_offset),
                     HeapObject::RawField(obj, end_offset));
}
 
 
template<int start_offset>
void FlexibleBodyDescriptor<start_offset>::IterateBody(HeapObject* obj,
                                                       int object_size,
                                                       ObjectVisitor* v) {
  v->VisitPointers(HeapObject::RawField(obj, start_offset),
                   HeapObject::RawField(obj, object_size));
}
 
 
template<class Derived, class TableType>
Object* OrderedHashTableIterator<Derived, TableType>::CurrentKey() {
  TableType* table(TableType::cast(this->table()));
  int index = Smi::cast(this->index())->value();
  Object* key = table->KeyAt(index);
  DCHECK(!key->IsTheHole());
  return key;
}
 
 
void JSSetIterator::PopulateValueArray(FixedArray* array) {
  array->set(0, CurrentKey());
}
 
 
void JSMapIterator::PopulateValueArray(FixedArray* array) {
  array->set(0, CurrentKey());
  array->set(1, CurrentValue());
}
 
 
Object* JSMapIterator::CurrentValue() {
  OrderedHashMap* table(OrderedHashMap::cast(this->table()));
  int index = Smi::cast(this->index())->value();
  Object* value = table->ValueAt(index);
  DCHECK(!value->IsTheHole());
  return value;
}
 
 
#undef TYPE_CHECKER
#undef CAST_ACCESSOR
#undef INT_ACCESSORS
#undef ACCESSORS
#undef ACCESSORS_TO_SMI
#undef SMI_ACCESSORS
#undef SYNCHRONIZED_SMI_ACCESSORS
#undef NOBARRIER_SMI_ACCESSORS
#undef BOOL_GETTER
#undef BOOL_ACCESSORS
#undef FIELD_ADDR
#undef FIELD_ADDR_CONST
#undef READ_FIELD
#undef NOBARRIER_READ_FIELD
#undef WRITE_FIELD
#undef NOBARRIER_WRITE_FIELD
#undef WRITE_BARRIER
#undef CONDITIONAL_WRITE_BARRIER
#undef READ_DOUBLE_FIELD
#undef WRITE_DOUBLE_FIELD
#undef READ_INT_FIELD
#undef WRITE_INT_FIELD
#undef READ_INTPTR_FIELD
#undef WRITE_INTPTR_FIELD
#undef READ_UINT32_FIELD
#undef WRITE_UINT32_FIELD
#undef READ_SHORT_FIELD
#undef WRITE_SHORT_FIELD
#undef READ_BYTE_FIELD
#undef WRITE_BYTE_FIELD
#undef NOBARRIER_READ_BYTE_FIELD
#undef NOBARRIER_WRITE_BYTE_FIELD
 
} }  // namespace v8::internal
 
#endif  // V8_OBJECTS_INL_H_