Remove the extensibility flag. Instead just rely on hidden_string as indication.

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 "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/allocation-site-scopes.h"
 #include "src/api.h"
 #include "src/arguments.h"
@@ skipping 2905 matching lines @@
               return SetDataProperty(it, value);
             }
         }
         done = true;
         break;
     }
 
     if (done) break;
   }
 
-  return AddDataProperty(it, value, NONE, strict_mode, store_mode,
-                         PERFORM_EXTENSIBILITY_CHECK);
+  return AddDataProperty(it, value, NONE, strict_mode, store_mode);
 }
 
 
 MaybeHandle<Object> Object::WriteToReadOnlyProperty(LookupIterator* it,
                                                     Handle<Object> value,
                                                     StrictMode strict_mode) {
   if (strict_mode != STRICT) return value;
 
   Handle<Object> args[] = {it->name(), it->GetReceiver()};
   Handle<Object> error = it->factory()->NewTypeError(
@@ skipping 34 matching lines @@
   }
 
   return value;
 }
 
 
 MaybeHandle<Object> Object::AddDataProperty(LookupIterator* it,
                                             Handle<Object> value,
                                             PropertyAttributes attributes,
                                             StrictMode strict_mode,
-                                            StoreFromKeyed store_mode,
-                                            ExtensibilityCheck check) {
+                                            StoreFromKeyed store_mode) {
   DCHECK(!it->GetReceiver()->IsJSProxy());
   if (!it->GetReceiver()->IsJSObject()) {
     // TODO(verwaest): Throw a TypeError with a more specific message.
     return WriteToReadOnlyProperty(it, value, strict_mode);
   }
   Handle<JSObject> receiver = Handle<JSObject>::cast(it->GetReceiver());
 
   // If the receiver is a JSGlobalProxy, store on the prototype (JSGlobalObject)
   // instead. If the prototype is Null, the proxy is detached.
   if (receiver->IsJSGlobalProxy()) {
     // Trying to assign to a detached proxy.
     PrototypeIterator iter(it->isolate(), receiver);
     if (iter.IsAtEnd()) return value;
     receiver =
         Handle<JSGlobalObject>::cast(PrototypeIterator::GetCurrent(iter));
   }
 
-  if (check == PERFORM_EXTENSIBILITY_CHECK &&
+  if (!it->name().is_identical_to(it->isolate()->factory()->hidden_string()) &&
       !receiver->map()->is_extensible()) {
     if (strict_mode == SLOPPY) return value;
 
     Handle<Object> args[1] = {it->name()};
     Handle<Object> error = it->factory()->NewTypeError(
         "object_not_extensible", HandleVector(args, ARRAY_SIZE(args)));
     return it->isolate()->Throw<Object>(error);
   }
 
   // Possibly migrate to the most up-to-date map that will be able to store
@@ skipping 854 matching lines @@
     box->set_value(value->Number());
   } else {
     FastPropertyAtPut(index, value);
   }
 }
 
 
 void JSObject::AddProperty(Handle<JSObject> object, Handle<Name> name,
                            Handle<Object> value,
                            PropertyAttributes attributes) {
+  LookupIterator it(object, name, LookupIterator::CHECK_OWN_REAL);
 #ifdef DEBUG
   uint32_t index;
   DCHECK(!object->IsJSProxy());
   DCHECK(!name->AsArrayIndex(&index));
-  LookupIterator it(object, name, LookupIterator::CHECK_OWN_REAL);
   Maybe<PropertyAttributes> maybe = GetPropertyAttributes(&it);
   DCHECK(maybe.has_value);
   DCHECK(!it.IsFound());
-  DCHECK(object->map()->is_extensible());
+  DCHECK(object->map()->is_extensible() ||
+         name.is_identical_to(it.isolate()->factory()->hidden_string()));
 #endif
-  SetOwnPropertyIgnoreAttributes(object, name, value, attributes,
-                                 OMIT_EXTENSIBILITY_CHECK).Check();
+  AddDataProperty(&it, value, attributes, STRICT,
+                  CERTAINLY_NOT_STORE_FROM_KEYED).Check();
 }
 
 
 // Reconfigures a property to a data property with attributes, even if it is not
 // reconfigurable.
 MaybeHandle<Object> JSObject::SetOwnPropertyIgnoreAttributes(
     Handle<JSObject> object,
     Handle<Name> name,
     Handle<Object> value,
     PropertyAttributes attributes,
-    ExtensibilityCheck extensibility_check,
     StoreFromKeyed store_from_keyed,
     ExecutableAccessorInfoHandling handling) {
   DCHECK(!value->IsTheHole());
   LookupIterator it(object, name, LookupIterator::CHECK_HIDDEN_ACCESS);
   bool is_observed = object->map()->is_observed() &&
                      *name != it.isolate()->heap()->hidden_string();
   for (; it.IsFound(); it.Next()) {
     switch (it.state()) {
       case LookupIterator::NOT_FOUND:
       case LookupIterator::JSPROXY:
@@ skipping 98 matching lines @@
             old_value = it.isolate()->factory()->the_hole_value();
           }
           EnqueueChangeRecord(object, "reconfigure", name, old_value);
         }
 
         return value;
       }
     }
   }
 
-  return AddDataProperty(&it, value, attributes, STRICT, store_from_keyed,
-                         extensibility_check);
+  return AddDataProperty(&it, value, attributes, STRICT, store_from_keyed);
 }
 
 
 Maybe<PropertyAttributes> JSObject::GetPropertyAttributesWithInterceptor(
     Handle<JSObject> holder,
     Handle<Object> receiver,
     Handle<Name> name) {
   // TODO(rossberg): Support symbols in the API.
   if (name->IsSymbol()) return maybe(ABSENT);
 
@@ skipping 807 matching lines @@
       isolate, kInitialCapacity, USE_CUSTOM_MINIMUM_CAPACITY);
 
   if (inline_value->IsSmi()) {
     // We were storing the identity hash inline and now allocated an actual
     // dictionary.  Put the identity hash into the new dictionary.
     hashtable = ObjectHashTable::Put(hashtable,
                                      isolate->factory()->identity_hash_string(),
                                      inline_value);
   }
 
-  JSObject::SetOwnPropertyIgnoreAttributes(
-      object, isolate->factory()->hidden_string(),
-      hashtable, DONT_ENUM).Assert();
-
+  SetHiddenPropertiesHashTable(object, hashtable);
   return hashtable;
 }
 
 
 Handle<Object> JSObject::SetHiddenPropertiesHashTable(Handle<JSObject> object,
                                                       Handle<Object> value) {
   DCHECK(!object->IsJSGlobalProxy());
-
   Isolate* isolate = object->GetIsolate();
-
-  // We can store the identity hash inline iff there is no backing store
-  // for hidden properties yet.
-  DCHECK(JSObject::HasHiddenProperties(object) != value->IsSmi());
-  if (object->HasFastProperties()) {
-    // If the object has fast properties, check whether the first slot
-    // in the descriptor array matches the hidden string. Since the
-    // hidden strings hash code is zero (and no other name has hash
-    // code zero) it will always occupy the first entry if present.
-    DescriptorArray* descriptors = object->map()->instance_descriptors();
-    if (descriptors->number_of_descriptors() > 0) {
-      int sorted_index = descriptors->GetSortedKeyIndex(0);
-      if (descriptors->GetKey(sorted_index) == isolate->heap()->hidden_string()
-          && sorted_index < object->map()->NumberOfOwnDescriptors()) {
-        object->WriteToField(sorted_index, *value);
-        return object;
-      }
-    }
-  }
-
-  SetOwnPropertyIgnoreAttributes(object, isolate->factory()->hidden_string(),
-                                 value, DONT_ENUM,
-                                 OMIT_EXTENSIBILITY_CHECK).Assert();
+  Handle<Name> name = isolate->factory()->hidden_string();
+  SetOwnPropertyIgnoreAttributes(object, name, value, DONT_ENUM).Assert();
   return object;
 }
 
 
 Handle<Object> JSObject::DeletePropertyPostInterceptor(Handle<JSObject> object,
                                                        Handle<Name> name,
                                                        DeleteMode delete_mode) {
   // Check own property, ignore interceptor.
   Isolate* isolate = object->GetIsolate();
   LookupResult lookup(isolate);
@@ skipping 11815 matching lines @@
 #define ERROR_MESSAGES_TEXTS(C, T) T,
   static const char* error_messages_[] = {
       ERROR_MESSAGES_LIST(ERROR_MESSAGES_TEXTS)
   };
 #undef ERROR_MESSAGES_TEXTS
   return error_messages_[reason];
 }
 
 
 } }  // namespace v8::internal