Reland of "Remove ExternalArray, derived types, and element kinds"

src/objects.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <iomanip>
 #include <sstream>
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
@@ skipping 1263 matching lines @@
     case BYTE_ARRAY_TYPE:
       os << "<ByteArray[" << ByteArray::cast(this)->length() << "]>";
       break;
     case BYTECODE_ARRAY_TYPE:
       os << "<BytecodeArray[" << BytecodeArray::cast(this)->length() << "]>";
       break;
     case FREE_SPACE_TYPE:
       os << "<FreeSpace[" << FreeSpace::cast(this)->Size() << "]>";
       break;
 #define TYPED_ARRAY_SHORT_PRINT(Type, type, TYPE, ctype, size)                \
-  case EXTERNAL_##TYPE##_ARRAY_TYPE:                                          \
-    os << "<External" #Type "Array["                                          \
-       << External##Type##Array::cast(this)->length() << "]>";                \
-    break;                                                                    \
   case FIXED_##TYPE##_ARRAY_TYPE:                                             \
     os << "<Fixed" #Type "Array[" << Fixed##Type##Array::cast(this)->length() \
        << "]>";                                                               \
     break;
 
     TYPED_ARRAYS(TYPED_ARRAY_SHORT_PRINT)
 #undef TYPED_ARRAY_SHORT_PRINT
 
     case SHARED_FUNCTION_INFO_TYPE: {
       SharedFunctionInfo* shared = SharedFunctionInfo::cast(this);
@@ skipping 203 matching lines @@
     case HEAP_NUMBER_TYPE:
     case MUTABLE_HEAP_NUMBER_TYPE:
     case FLOAT32X4_TYPE:
     case FILLER_TYPE:
     case BYTE_ARRAY_TYPE:
     case BYTECODE_ARRAY_TYPE:
     case FREE_SPACE_TYPE:
       break;
 
 #define TYPED_ARRAY_CASE(Type, type, TYPE, ctype, size) \
-  case EXTERNAL_##TYPE##_ARRAY_TYPE:                    \
-    break;                                              \
-                                                        \
   case FIXED_##TYPE##_ARRAY_TYPE:                       \
     reinterpret_cast<FixedTypedArrayBase*>(this)        \
         ->FixedTypedArrayBaseIterateBody(v);            \
     break;
 
 
     TYPED_ARRAYS(TYPED_ARRAY_CASE)
 #undef TYPED_ARRAY_CASE
 
     case SHARED_FUNCTION_INFO_TYPE: {
@@ skipping 1787 matching lines @@
   // Fetch before transforming the object since the encoding may become
   // incompatible with what's cached in |it|.
   bool is_observed = receiver->map()->is_observed() &&
                      (it->IsElement() ||
                       !it->isolate()->IsInternallyUsedPropertyName(it->name()));
   MaybeHandle<Object> maybe_old;
   if (is_observed) maybe_old = it->GetDataValue();
 
   Handle<Object> to_assign = value;
   // Convert the incoming value to a number for storing into typed arrays.
-  if (it->IsElement() && (receiver->HasExternalArrayElements() ||
-                          receiver->HasFixedTypedArrayElements())) {
+  if (it->IsElement() && receiver->HasFixedTypedArrayElements()) {
     if (!value->IsNumber() && !value->IsUndefined()) {
       ASSIGN_RETURN_ON_EXCEPTION(it->isolate(), to_assign,
                                  Execution::ToNumber(it->isolate(), value),
                                  Object);
       // ToNumber above might modify the receiver, causing the cached
       // holder_map to mismatch the actual holder->map() after this point.
       // Reload the map to be in consistent state. Other cached state cannot
       // have been invalidated since typed array elements cannot be reconfigured
       // in any way.
       it->ReloadHolderMap();
@@ skipping 91 matching lines @@
 
   if (it->IsElement()) {
     if (receiver->IsJSArray()) {
       Handle<JSArray> array = Handle<JSArray>::cast(receiver);
       if (JSArray::WouldChangeReadOnlyLength(array, it->index())) {
         if (is_sloppy(language_mode)) return value;
         return JSArray::ReadOnlyLengthError(array);
       }
 
       if (FLAG_trace_external_array_abuse &&
-          (array->HasExternalArrayElements() ||
-           array->HasFixedTypedArrayElements())) {
+          array->HasFixedTypedArrayElements()) {
         CheckArrayAbuse(array, "typed elements write", it->index(), true);
       }
 
-      if (FLAG_trace_js_array_abuse && !array->HasExternalArrayElements() &&
-          !array->HasFixedTypedArrayElements()) {
+      if (FLAG_trace_js_array_abuse && !array->HasFixedTypedArrayElements()) {
         CheckArrayAbuse(array, "elements write", it->index(), false);
       }
     }
 
     MaybeHandle<Object> result =
         JSObject::AddDataElement(receiver, it->index(), value, attributes);
     JSObject::ValidateElements(receiver);
     return result;
   } else {
     // Migrate to the most up-to-date map that will be able to store |value|
@@ skipping 808 matching lines @@
       case LookupIterator::DATA: {
         PropertyDetails details = it->property_details();
         Handle<Object> old_value = it->factory()->the_hole_value();
         // Regular property update if the attributes match.
         if (details.attributes() == attributes) {
           return SetDataProperty(it, value);
         }
 
         // Special case: properties of typed arrays cannot be reconfigured to
         // non-writable nor to non-enumerable.
-        if (it->IsElement() && (object->HasExternalArrayElements() ||
-                                object->HasFixedTypedArrayElements())) {
+        if (it->IsElement() && object->HasFixedTypedArrayElements()) {
           return RedefineNonconfigurableProperty(it->isolate(), it->GetName(),
                                                  value, STRICT);
         }
 
         // Reconfigure the data property if the attributes mismatch.
         if (is_observed) old_value = it->GetDataValue();
 
         it->ReconfigureDataProperty(value, attributes);
         it->WriteDataValue(value);
 
@@ skipping 562 matching lines @@
                    : elements->length();
   int used = object->GetFastElementsUsage();
   Handle<SeededNumberDictionary> dictionary =
       SeededNumberDictionary::New(isolate, used);
   return CopyFastElementsToDictionary(elements, length, dictionary);
 }
 
 
 Handle<SeededNumberDictionary> JSObject::NormalizeElements(
     Handle<JSObject> object) {
-  DCHECK(!object->HasExternalArrayElements() &&
-         !object->HasFixedTypedArrayElements());
+  DCHECK(!object->HasFixedTypedArrayElements());
   Isolate* isolate = object->GetIsolate();
 
   // Find the backing store.
   Handle<FixedArrayBase> elements(object->elements(), isolate);
   bool is_arguments = object->HasSloppyArgumentsElements();
   if (is_arguments) {
     FixedArray* parameter_map = FixedArray::cast(*elements);
     elements = handle(FixedArrayBase::cast(parameter_map->get(1)), isolate);
   }
 
@@ skipping 484 matching lines @@
   if (!key->IsUndefined()) {
     return true;
   }
 
   // Check if the object is among the indexed properties.
   ElementsKind kind = GetElementsKind();
   switch (kind) {
     // Raw pixels and external arrays do not reference other
     // objects.
 #define TYPED_ARRAY_CASE(Type, type, TYPE, ctype, size)                        \
-    case EXTERNAL_##TYPE##_ELEMENTS:                                           \
     case TYPE##_ELEMENTS:                                                      \
       break;
 
     TYPED_ARRAYS(TYPED_ARRAY_CASE)
 #undef TYPED_ARRAY_CASE
 
     case FAST_DOUBLE_ELEMENTS:
     case FAST_HOLEY_DOUBLE_ELEMENTS:
       break;
     case FAST_SMI_ELEMENTS:
@@ skipping 89 matching lines @@
 
   if (object->IsJSGlobalProxy()) {
     PrototypeIterator iter(isolate, object);
     if (iter.IsAtEnd()) return object;
     DCHECK(PrototypeIterator::GetCurrent(iter)->IsJSGlobalObject());
     return PreventExtensions(
         Handle<JSObject>::cast(PrototypeIterator::GetCurrent(iter)));
   }
 
   // It's not possible to seal objects with external array elements
-  if (object->HasExternalArrayElements() ||
-      object->HasFixedTypedArrayElements()) {
+  if (object->HasFixedTypedArrayElements()) {
     THROW_NEW_ERROR(
         isolate, NewTypeError(MessageTemplate::kCannotPreventExtExternalArray),
         Object);
   }
 
   // If there are fast elements we normalize.
   Handle<SeededNumberDictionary> dictionary = NormalizeElements(object);
   DCHECK(object->HasDictionaryElements() || object->HasSlowArgumentsElements());
 
   // Make sure that we never go back to fast case.
@@ skipping 72 matching lines @@
 
   if (object->IsJSGlobalProxy()) {
     PrototypeIterator iter(isolate, object);
     if (iter.IsAtEnd()) return object;
     DCHECK(PrototypeIterator::GetCurrent(iter)->IsJSGlobalObject());
     return PreventExtensionsWithTransition<attrs>(
         Handle<JSObject>::cast(PrototypeIterator::GetCurrent(iter)));
   }
 
   // It's not possible to seal or freeze objects with external array elements
-  if (object->HasExternalArrayElements() ||
-      object->HasFixedTypedArrayElements()) {
+  if (object->HasFixedTypedArrayElements()) {
     THROW_NEW_ERROR(
         isolate, NewTypeError(MessageTemplate::kCannotPreventExtExternalArray),
         Object);
   }
 
   Handle<SeededNumberDictionary> new_element_dictionary;
   if (!object->HasDictionaryElements()) {
     int length =
         object->IsJSArray()
             ? Smi::cast(Handle<JSArray>::cast(object)->length())->value()
@@ skipping 248 matching lines @@
           if (copying) {
             // Creating object copy for literals. No strict mode needed.
             JSObject::SetProperty(copy, key_string, result, SLOPPY).Assert();
           }
         }
       }
     }
 
     // Deep copy own elements.
     // Pixel elements cannot be created using an object literal.
-    DCHECK(!copy->HasExternalArrayElements());
+    DCHECK(!copy->HasFixedTypedArrayElements());
     switch (kind) {
       case FAST_SMI_ELEMENTS:
       case FAST_ELEMENTS:
       case FAST_HOLEY_SMI_ELEMENTS:
       case FAST_HOLEY_ELEMENTS: {
         Handle<FixedArray> elements(FixedArray::cast(copy->elements()));
         if (elements->map() == isolate->heap()->fixed_cow_array_map()) {
 #ifdef DEBUG
           for (int i = 0; i < elements->length(); i++) {
             DCHECK(!elements->get(i)->IsJSObject());
@@ skipping 41 matching lines @@
         }
         break;
       }
       case FAST_SLOPPY_ARGUMENTS_ELEMENTS:
       case SLOW_SLOPPY_ARGUMENTS_ELEMENTS:
         UNIMPLEMENTED();
         break;
 
 
 #define TYPED_ARRAY_CASE(Type, type, TYPE, ctype, size)                        \
-      case EXTERNAL_##TYPE##_ELEMENTS:                                         \
       case TYPE##_ELEMENTS:                                                    \
 
       TYPED_ARRAYS(TYPED_ARRAY_CASE)
 #undef TYPED_ARRAY_CASE
 
       case FAST_DOUBLE_ELEMENTS:
       case FAST_HOLEY_DOUBLE_ELEMENTS:
         // No contained objects, nothing to do.
         break;
     }
@@ skipping 382 matching lines @@
   if (it.state() == LookupIterator::ACCESS_CHECK) {
     if (!it.HasAccess()) {
       isolate->ReportFailedAccessCheck(it.GetHolder<JSObject>());
       RETURN_EXCEPTION_IF_SCHEDULED_EXCEPTION(isolate, Object);
       return isolate->factory()->undefined_value();
     }
     it.Next();
   }
 
   // Ignore accessors on typed arrays.
-  if (it.IsElement() && (object->HasFixedTypedArrayElements() ||
-                         object->HasExternalArrayElements())) {
+  if (it.IsElement() && object->HasFixedTypedArrayElements()) {
     return it.factory()->undefined_value();
   }
 
   Handle<Object> old_value = isolate->factory()->the_hole_value();
   bool is_observed = object->map()->is_observed() &&
                      !isolate->IsInternallyUsedPropertyName(name);
   bool preexists = false;
   if (is_observed) {
     CHECK(GetPropertyAttributes(&it).IsJust());
     preexists = it.IsFound();
@@ skipping 42 matching lines @@
   if (it.state() == LookupIterator::ACCESS_CHECK) {
     if (!it.HasAccess()) {
       isolate->ReportFailedAccessCheck(object);
       RETURN_EXCEPTION_IF_SCHEDULED_EXCEPTION(isolate, Object);
       return it.factory()->undefined_value();
     }
     it.Next();
   }
 
   // Ignore accessors on typed arrays.
-  if (it.IsElement() && (object->HasFixedTypedArrayElements() ||
-                         object->HasExternalArrayElements())) {
+  if (it.IsElement() && object->HasFixedTypedArrayElements()) {
     return it.factory()->undefined_value();
   }
 
   CHECK(GetPropertyAttributes(&it).IsJust());
 
   // ES5 forbids turning a property into an accessor if it's not
   // configurable. See 8.6.1 (Table 5).
   if (it.IsFound() && !it.IsConfigurable()) {
     return it.factory()->undefined_value();
   }
@@ skipping 396 matching lines @@
 
   return result;
 }
 
 
 Handle<Map> Map::CopyAsElementsKind(Handle<Map> map, ElementsKind kind,
                                     TransitionFlag flag) {
   Map* maybe_elements_transition_map = NULL;
   if (flag == INSERT_TRANSITION) {
     maybe_elements_transition_map = map->ElementsTransitionMap();
-    DCHECK(
-        maybe_elements_transition_map == NULL ||
-        ((maybe_elements_transition_map->elements_kind() ==
-              DICTIONARY_ELEMENTS ||
-          IsExternalArrayElementsKind(
-              maybe_elements_transition_map->elements_kind())) &&
-         (kind == DICTIONARY_ELEMENTS || IsExternalArrayElementsKind(kind))));
+    DCHECK(maybe_elements_transition_map == NULL ||
+           (maybe_elements_transition_map->elements_kind() ==
+                DICTIONARY_ELEMENTS &&
+            kind == DICTIONARY_ELEMENTS));
     DCHECK(!IsFastElementsKind(kind) ||
            IsMoreGeneralElementsKindTransition(map->elements_kind(), kind));
     DCHECK(kind != map->elements_kind());
   }
 
   bool insert_transition = flag == INSERT_TRANSITION &&
                            TransitionArray::CanHaveMoreTransitions(map) &&
                            maybe_elements_transition_map == NULL;
 
   if (insert_transition) {
@@ skipping 5795 matching lines @@
     case FAST_HOLEY_SMI_ELEMENTS:
     case FAST_HOLEY_ELEMENTS:
       return FastHoleyElementsUsage(this, FixedArray::cast(store));
     case FAST_HOLEY_DOUBLE_ELEMENTS:
       if (elements()->length() == 0) return 0;
       return FastHoleyElementsUsage(this, FixedDoubleArray::cast(store));
 
     case SLOW_SLOPPY_ARGUMENTS_ELEMENTS:
     case DICTIONARY_ELEMENTS:
 #define TYPED_ARRAY_CASE(Type, type, TYPE, ctype, size)                      \
-    case EXTERNAL_##TYPE##_ELEMENTS:                                         \
     case TYPE##_ELEMENTS:                                                    \
 
     TYPED_ARRAYS(TYPED_ARRAY_CASE)
 #undef TYPED_ARRAY_CASE
     UNREACHABLE();
   }
   return 0;
 }
 
 
@@ skipping 413 matching lines @@
             storage->set(counter, Smi::FromInt(i));
           }
           counter++;
         }
       }
       DCHECK(!storage || storage->length() >= counter);
       break;
     }
 
 #define TYPED_ARRAY_CASE(Type, type, TYPE, ctype, size)                      \
-    case EXTERNAL_##TYPE##_ELEMENTS:                                         \
     case TYPE##_ELEMENTS:                                                    \
 
     TYPED_ARRAYS(TYPED_ARRAY_CASE)
 #undef TYPED_ARRAY_CASE
     {
       int length = FixedArrayBase::cast(elements())->length();
       while (counter < length) {
         if (storage != NULL) {
           storage->set(counter, Smi::FromInt(counter));
         }
@@ skipping 801 matching lines @@
         JSObject::GetElementsTransitionMap(object, FAST_HOLEY_ELEMENTS);
 
     PretenureFlag tenure = isolate->heap()->InNewSpace(*object) ?
         NOT_TENURED: TENURED;
     Handle<FixedArray> fast_elements =
         isolate->factory()->NewFixedArray(dict->NumberOfElements(), tenure);
     dict->CopyValuesTo(*fast_elements);
     JSObject::ValidateElements(object);
 
     JSObject::SetMapAndElements(object, new_map, fast_elements);
-  } else if (object->HasExternalArrayElements() ||
-             object->HasFixedTypedArrayElements()) {
+  } else if (object->HasFixedTypedArrayElements()) {
     // Typed arrays cannot have holes or undefined elements.
     return handle(Smi::FromInt(
         FixedArrayBase::cast(object->elements())->length()), isolate);
   } else if (!object->HasFastDoubleElements()) {
     EnsureWritableFastElements(object);
   }
   DCHECK(object->HasFastSmiOrObjectElements() ||
          object->HasFastDoubleElements());
 
   // Collect holes at the end, undefined before that and the rest at the
@@ skipping 82 matching lines @@
     }
   }
 
   return isolate->factory()->NewNumberFromUint(result);
 }
 
 
 ExternalArrayType JSTypedArray::type() {
   switch (elements()->map()->instance_type()) {
 #define INSTANCE_TYPE_TO_ARRAY_TYPE(Type, type, TYPE, ctype, size)            \
-    case EXTERNAL_##TYPE##_ARRAY_TYPE:                                        \
     case FIXED_##TYPE##_ARRAY_TYPE:                                           \
       return kExternal##Type##Array;
 
     TYPED_ARRAYS(INSTANCE_TYPE_TO_ARRAY_TYPE)
 #undef INSTANCE_TYPE_TO_ARRAY_TYPE
 
     default:
       UNREACHABLE();
       return static_cast<ExternalArrayType>(-1);
   }
 }
 
 
 size_t JSTypedArray::element_size() {
   switch (elements()->map()->instance_type()) {
-#define INSTANCE_TYPE_TO_ELEMENT_SIZE(Type, type, TYPE, ctype, size)          \
-    case EXTERNAL_##TYPE##_ARRAY_TYPE:                                        \
-      return size;
+#define INSTANCE_TYPE_TO_ELEMENT_SIZE(Type, type, TYPE, ctype, size) \
+  case FIXED_##TYPE##_ARRAY_TYPE:                                    \
+    return size;
 
     TYPED_ARRAYS(INSTANCE_TYPE_TO_ELEMENT_SIZE)
 #undef INSTANCE_TYPE_TO_ELEMENT_SIZE
 
     default:
       UNREACHABLE();
       return 0;
   }
 }
 
 
 void FixedArray::SetValue(uint32_t index, Object* value) { set(index, value); }
 
 
 void FixedDoubleArray::SetValue(uint32_t index, Object* value) {
   set(index, value->Number());
 }
-
-
-void ExternalUint8ClampedArray::SetValue(uint32_t index, Object* value) {
-  uint8_t clamped_value = 0;
-  if (value->IsSmi()) {
-    int int_value = Smi::cast(value)->value();
-    if (int_value < 0) {
-      clamped_value = 0;
-    } else if (int_value > 255) {
-      clamped_value = 255;
-    } else {
-      clamped_value = static_cast<uint8_t>(int_value);
-    }
-  } else if (value->IsHeapNumber()) {
-    double double_value = HeapNumber::cast(value)->value();
-    if (!(double_value > 0)) {
-      // NaN and less than zero clamp to zero.
-      clamped_value = 0;
-    } else if (double_value > 255) {
-      // Greater than 255 clamp to 255.
-      clamped_value = 255;
-    } else {
-      // Other doubles are rounded to the nearest integer.
-      clamped_value = static_cast<uint8_t>(lrint(double_value));
-    }
-  } else {
-    // Clamp undefined to zero (default). All other types have been
-    // converted to a number type further up in the call chain.
-    DCHECK(value->IsUndefined());
-  }
-  set(index, clamped_value);
-}
-
-
-template <typename ExternalArrayClass, typename ValueType>
-static void ExternalArrayIntSetter(ExternalArrayClass* receiver, uint32_t index,
-                                   Object* value) {
-  ValueType cast_value = 0;
-  if (value->IsSmi()) {
-    int int_value = Smi::cast(value)->value();
-    cast_value = static_cast<ValueType>(int_value);
-  } else if (value->IsHeapNumber()) {
-    double double_value = HeapNumber::cast(value)->value();
-    cast_value = static_cast<ValueType>(DoubleToInt32(double_value));
-  } else {
-    // Clamp undefined to zero (default). All other types have been
-    // converted to a number type further up in the call chain.
-    DCHECK(value->IsUndefined());
-  }
-  receiver->set(index, cast_value);
-}
-
-
-void ExternalInt8Array::SetValue(uint32_t index, Object* value) {
-  ExternalArrayIntSetter<ExternalInt8Array, int8_t>(this, index, value);
-}
-
-
-void ExternalUint8Array::SetValue(uint32_t index, Object* value) {
-  ExternalArrayIntSetter<ExternalUint8Array, uint8_t>(this, index, value);
-}
-
-
-void ExternalInt16Array::SetValue(uint32_t index, Object* value) {
-  ExternalArrayIntSetter<ExternalInt16Array, int16_t>(this, index, value);
-}
-
-
-void ExternalUint16Array::SetValue(uint32_t index, Object* value) {
-  ExternalArrayIntSetter<ExternalUint16Array, uint16_t>(this, index, value);
-}
-
-
-void ExternalInt32Array::SetValue(uint32_t index, Object* value) {
-  ExternalArrayIntSetter<ExternalInt32Array, int32_t>(this, index, value);
-}
-
-
-void ExternalUint32Array::SetValue(uint32_t index, Object* value) {
-  uint32_t cast_value = 0;
-  if (value->IsSmi()) {
-    int int_value = Smi::cast(value)->value();
-    cast_value = static_cast<uint32_t>(int_value);
-  } else if (value->IsHeapNumber()) {
-    double double_value = HeapNumber::cast(value)->value();
-    cast_value = static_cast<uint32_t>(DoubleToUint32(double_value));
-  } else {
-    // Clamp undefined to zero (default). All other types have been
-    // converted to a number type further up in the call chain.
-    DCHECK(value->IsUndefined());
-  }
-  set(index, cast_value);
-}
-
-
-void ExternalFloat32Array::SetValue(uint32_t index, Object* value) {
-  float cast_value = std::numeric_limits<float>::quiet_NaN();
-  if (value->IsSmi()) {
-    int int_value = Smi::cast(value)->value();
-    cast_value = static_cast<float>(int_value);
-  } else if (value->IsHeapNumber()) {
-    double double_value = HeapNumber::cast(value)->value();
-    cast_value = static_cast<float>(double_value);
-  } else {
-    // Clamp undefined to NaN (default). All other types have been
-    // converted to a number type further up in the call chain.
-    DCHECK(value->IsUndefined());
-  }
-  set(index, cast_value);
-}
-
-
-void ExternalFloat64Array::SetValue(uint32_t index, Object* value) {
-  double double_value = std::numeric_limits<double>::quiet_NaN();
-  if (value->IsNumber()) {
-    double_value = value->Number();
-  } else {
-    // Clamp undefined to NaN (default). All other types have been
-    // converted to a number type further up in the call chain.
-    DCHECK(value->IsUndefined());
-  }
-  set(index, double_value);
-}
-
-
 void GlobalObject::InvalidatePropertyCell(Handle<GlobalObject> global,
                                           Handle<Name> name) {
   DCHECK(!global->HasFastProperties());
   auto dictionary = handle(global->global_dictionary());
   int entry = dictionary->FindEntry(name);
   if (entry == GlobalDictionary::kNotFound) return;
   PropertyCell::InvalidateEntry(dictionary, entry);
 }
 
 
@@ skipping 1591 matching lines @@
 
 void JSArrayBuffer::Neuter() {
   CHECK(is_neuterable());
   CHECK(is_external());
   set_backing_store(NULL);
   set_byte_length(Smi::FromInt(0));
   set_was_neutered(true);
 }
 
 
-static ElementsKind FixedToExternalElementsKind(ElementsKind elements_kind) {
-  switch (elements_kind) {
-#define TYPED_ARRAY_CASE(Type, type, TYPE, ctype, size)                       \
-    case TYPE##_ELEMENTS: return EXTERNAL_##TYPE##_ELEMENTS;
-
-    TYPED_ARRAYS(TYPED_ARRAY_CASE)
-#undef TYPED_ARRAY_CASE
-
-    default:
-      UNREACHABLE();
-      return FIRST_EXTERNAL_ARRAY_ELEMENTS_KIND;
-  }
-}
-
-
 Handle<JSArrayBuffer> JSTypedArray::MaterializeArrayBuffer(
     Handle<JSTypedArray> typed_array) {
 
   Handle<Map> map(typed_array->map());
   Isolate* isolate = typed_array->GetIsolate();
 
   DCHECK(IsFixedTypedArrayElementsKind(map->elements_kind()));
 
-  Handle<Map> new_map = Map::TransitionElementsTo(
-          map,
-          FixedToExternalElementsKind(map->elements_kind()));
-
   Handle<FixedTypedArrayBase> fixed_typed_array(
       FixedTypedArrayBase::cast(typed_array->elements()));
 
   Handle<JSArrayBuffer> buffer(JSArrayBuffer::cast(typed_array->buffer()),
                                isolate);
   void* backing_store =
       isolate->array_buffer_allocator()->AllocateUninitialized(
           fixed_typed_array->DataSize());
   buffer->set_backing_store(backing_store);
   buffer->set_is_external(false);
   isolate->heap()->RegisterNewArrayBuffer(isolate->heap()->InNewSpace(*buffer),
                                           backing_store,
                                           fixed_typed_array->DataSize());
   memcpy(buffer->backing_store(),
          fixed_typed_array->DataPtr(),
          fixed_typed_array->DataSize());
-  Handle<ExternalArray> new_elements =
-      isolate->factory()->NewExternalArray(
+  Handle<FixedTypedArrayBase> new_elements =
+      isolate->factory()->NewFixedTypedArrayWithExternalPointer(
           fixed_typed_array->length(), typed_array->type(),
           static_cast<uint8_t*>(buffer->backing_store()));
 
-  JSObject::SetMapAndElements(typed_array, new_map, new_elements);
+  typed_array->set_elements(*new_elements);
 
   return buffer;
 }
 
 
 Handle<JSArrayBuffer> JSTypedArray::GetBuffer() {
-  if (IsExternalArrayElementsKind(map()->elements_kind())) {
-    Handle<Object> result(buffer(), GetIsolate());
-    return Handle<JSArrayBuffer>::cast(result);
+  Handle<JSArrayBuffer> array_buffer(JSArrayBuffer::cast(buffer()),
+                                     GetIsolate());
+  if (array_buffer->was_neutered() ||
+      array_buffer->backing_store() != nullptr) {
+    return array_buffer;
   }
   Handle<JSTypedArray> self(this);
   return MaterializeArrayBuffer(self);
 }
 
 
 Handle<PropertyCell> PropertyCell::InvalidateEntry(
     Handle<GlobalDictionary> dictionary, int entry) {
   Isolate* isolate = dictionary->GetIsolate();
   // Swap with a copy.
@@ skipping 125 matching lines @@
   if (cell->value() != *new_value) {
     cell->set_value(*new_value);
     Isolate* isolate = cell->GetIsolate();
     cell->dependent_code()->DeoptimizeDependentCodeGroup(
         isolate, DependentCode::kPropertyCellChangedGroup);
   }
 }
 
 }  // namespace internal
 }  // namespace v8