A64: Synchronize with r17441.

src/objects.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 10 matching lines @@
 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include "v8.h"
 
 #include "accessors.h"
+#include "allocation-site-scopes.h"
 #include "api.h"
 #include "arguments.h"
 #include "bootstrapper.h"
 #include "codegen.h"
 #include "cpu-profiler.h"
 #include "debug.h"
 #include "deoptimizer.h"
 #include "date.h"
 #include "elements.h"
 #include "execution.h"
@@ skipping 94 matching lines @@
     } else {
       result->isolate()->PushStackTraceAndDie(
           0xDEAD0000, this, JSReceiver::cast(this)->map(), 0xDEAD0001);
     }
   }
   ASSERT(holder != NULL);  // Cannot handle null or undefined.
   JSReceiver::cast(holder)->Lookup(name, result);
 }
 
 
+Handle<Object> Object::GetPropertyWithReceiver(
+    Handle<Object> object,
+    Handle<Object> receiver,
+    Handle<Name> name,
+    PropertyAttributes* attributes) {
+  LookupResult lookup(name->GetIsolate());
+  object->Lookup(*name, &lookup);
+  Handle<Object> result =
+      GetProperty(object, receiver, &lookup, name, attributes);
+  ASSERT(*attributes <= ABSENT);
+  return result;
+}
+
+
 MaybeObject* Object::GetPropertyWithReceiver(Object* receiver,
                                              Name* name,
                                              PropertyAttributes* attributes) {
   LookupResult result(name->GetIsolate());
   Lookup(name, &result);
   MaybeObject* value = GetProperty(receiver, &result, name, attributes);
   ASSERT(*attributes <= ABSENT);
   return value;
 }
 
@@ skipping 166 matching lines @@
         return GetPrimitiveValue(data->primitive_value_descriptor,
                                  current,
                                  isolate->heap());
     }
   }
   UNREACHABLE();
   return NULL;
 }
 
 
-MaybeObject* JSObject::GetPropertyWithCallback(Object* receiver,
-                                               Object* structure,
-                                               Name* name) {
+Handle<FixedArray> JSObject::EnsureWritableFastElements(
+    Handle<JSObject> object) {
+  CALL_HEAP_FUNCTION(object->GetIsolate(),
+                     object->EnsureWritableFastElements(),
+                     FixedArray);
+}
+
+
+Handle<Object> JSObject::GetPropertyWithCallback(Handle<JSObject> object,
+                                                 Handle<Object> receiver,
+                                                 Handle<Object> structure,
+                                                 Handle<Name> name) {
   Isolate* isolate = name->GetIsolate();
   // To accommodate both the old and the new api we switch on the
   // data structure used to store the callbacks.  Eventually foreign
   // callbacks should be phased out.
   if (structure->IsForeign()) {
     AccessorDescriptor* callback =
         reinterpret_cast<AccessorDescriptor*>(
-            Foreign::cast(structure)->foreign_address());
-    MaybeObject* value = (callback->getter)(isolate, receiver, callback->data);
-    RETURN_IF_SCHEDULED_EXCEPTION(isolate);
-    return value;
+            Handle<Foreign>::cast(structure)->foreign_address());
+    CALL_HEAP_FUNCTION(isolate,
+                       (callback->getter)(isolate, *receiver, callback->data),
+                       Object);
   }
 
   // api style callbacks.
   if (structure->IsAccessorInfo()) {
-    if (!AccessorInfo::cast(structure)->IsCompatibleReceiver(receiver)) {
-      Handle<Object> name_handle(name, isolate);
-      Handle<Object> receiver_handle(receiver, isolate);
-      Handle<Object> args[2] = { name_handle, receiver_handle };
+    Handle<AccessorInfo> accessor_info = Handle<AccessorInfo>::cast(structure);
+    if (!accessor_info->IsCompatibleReceiver(*receiver)) {
+      Handle<Object> args[2] = { name, receiver };
       Handle<Object> error =
           isolate->factory()->NewTypeError("incompatible_method_receiver",
                                            HandleVector(args,
                                                         ARRAY_SIZE(args)));
-      return isolate->Throw(*error);
+      isolate->Throw(*error);
+      return Handle<Object>::null();
     }
     // TODO(rossberg): Handling symbols in the API requires changing the API,
     // so we do not support it for now.
-    if (name->IsSymbol()) return isolate->heap()->undefined_value();
+    if (name->IsSymbol()) return isolate->factory()->undefined_value();
     if (structure->IsDeclaredAccessorInfo()) {
-      return GetDeclaredAccessorProperty(receiver,
-                                         DeclaredAccessorInfo::cast(structure),
-                                         isolate);
+      CALL_HEAP_FUNCTION(
+          isolate,
+          GetDeclaredAccessorProperty(*receiver,
+                                      DeclaredAccessorInfo::cast(*structure),
+                                      isolate),
+          Object);
     }
-    ExecutableAccessorInfo* data = ExecutableAccessorInfo::cast(structure);
-    Object* fun_obj = data->getter();
+
+    Handle<ExecutableAccessorInfo> data =
+        Handle<ExecutableAccessorInfo>::cast(structure);
     v8::AccessorGetterCallback call_fun =
-        v8::ToCData<v8::AccessorGetterCallback>(fun_obj);
-    if (call_fun == NULL) return isolate->heap()->undefined_value();
+        v8::ToCData<v8::AccessorGetterCallback>(data->getter());
+    if (call_fun == NULL) return isolate->factory()->undefined_value();
+
     HandleScope scope(isolate);
-    JSObject* self = JSObject::cast(receiver);
-    Handle<String> key(String::cast(name));
-    LOG(isolate, ApiNamedPropertyAccess("load", self, name));
-    PropertyCallbackArguments args(isolate, data->data(), self, this);
+    Handle<JSObject> self = Handle<JSObject>::cast(receiver);
+    Handle<String> key = Handle<String>::cast(name);
+    LOG(isolate, ApiNamedPropertyAccess("load", *self, *name));
+    PropertyCallbackArguments args(isolate, data->data(), *self, *object);
     v8::Handle<v8::Value> result =
         args.Call(call_fun, v8::Utils::ToLocal(key));
-    RETURN_IF_SCHEDULED_EXCEPTION(isolate);
+    RETURN_HANDLE_IF_SCHEDULED_EXCEPTION(isolate, Object);
     if (result.IsEmpty()) {
-      return isolate->heap()->undefined_value();
+      return isolate->factory()->undefined_value();
     }
-    Object* return_value = *v8::Utils::OpenHandle(*result);
+    Handle<Object> return_value = v8::Utils::OpenHandle(*result);
     return_value->VerifyApiCallResultType();
-    return return_value;
+    return scope.CloseAndEscape(return_value);
   }
 
   // __defineGetter__ callback
-  if (structure->IsAccessorPair()) {
-    Object* getter = AccessorPair::cast(structure)->getter();
-    if (getter->IsSpecFunction()) {
-      // TODO(rossberg): nicer would be to cast to some JSCallable here...
-      return GetPropertyWithDefinedGetter(receiver, JSReceiver::cast(getter));
-    }
-    // Getter is not a function.
-    return isolate->heap()->undefined_value();
+  Handle<Object> getter(Handle<AccessorPair>::cast(structure)->getter(),
+                        isolate);
+  if (getter->IsSpecFunction()) {
+    // TODO(rossberg): nicer would be to cast to some JSCallable here...
+    CALL_HEAP_FUNCTION(
+        isolate,
+        object->GetPropertyWithDefinedGetter(*receiver,
+                                             JSReceiver::cast(*getter)),
+        Object);
   }
-
-  UNREACHABLE();
-  return NULL;
+  // Getter is not a function.
+  return isolate->factory()->undefined_value();
 }
 
 
 MaybeObject* JSProxy::GetPropertyWithHandler(Object* receiver_raw,
                                              Name* name_raw) {
   Isolate* isolate = GetIsolate();
   HandleScope scope(isolate);
   Handle<Object> receiver(receiver_raw, isolate);
   Handle<Object> name(name_raw, isolate);
 
@@ skipping 75 matching lines @@
   bool has_pending_exception;
   Handle<Object> result = Execution::Call(
       isolate, fun, self, 0, NULL, &has_pending_exception, true);
   // Check for pending exception and return the result.
   if (has_pending_exception) return Failure::Exception();
   return *result;
 }
 
 
 // Only deal with CALLBACKS and INTERCEPTOR
-MaybeObject* JSObject::GetPropertyWithFailedAccessCheck(
-    Object* receiver,
+Handle<Object> JSObject::GetPropertyWithFailedAccessCheck(
+    Handle<JSObject> object,
+    Handle<Object> receiver,
     LookupResult* result,
-    Name* name,
+    Handle<Name> name,
     PropertyAttributes* attributes) {
+  Isolate* isolate = name->GetIsolate();
   if (result->IsProperty()) {
     switch (result->type()) {
       case CALLBACKS: {
         // Only allow API accessors.
-        Object* obj = result->GetCallbackObject();
-        if (obj->IsAccessorInfo()) {
-          AccessorInfo* info = AccessorInfo::cast(obj);
-          if (info->all_can_read()) {
-            *attributes = result->GetAttributes();
-            return result->holder()->GetPropertyWithCallback(
-                receiver, result->GetCallbackObject(), name);
-          }
-        } else if (obj->IsAccessorPair()) {
-          AccessorPair* pair = AccessorPair::cast(obj);
-          if (pair->all_can_read()) {
-            return result->holder()->GetPropertyWithCallback(
-                receiver, result->GetCallbackObject(), name);
-          }
+        Handle<Object> callback_obj(result->GetCallbackObject(), isolate);
+        if (callback_obj->IsAccessorInfo()) {
+          if (!AccessorInfo::cast(*callback_obj)->all_can_read()) break;
+          *attributes = result->GetAttributes();
+          // Fall through to GetPropertyWithCallback.
+        } else if (callback_obj->IsAccessorPair()) {
+          if (!AccessorPair::cast(*callback_obj)->all_can_read()) break;
+          // Fall through to GetPropertyWithCallback.
+        } else {
+          break;
         }
-        break;
+        Handle<JSObject> holder(result->holder(), isolate);
+        return GetPropertyWithCallback(holder, receiver, callback_obj, name);
       }
       case NORMAL:
       case FIELD:
       case CONSTANT: {
         // Search ALL_CAN_READ accessors in prototype chain.
-        LookupResult r(GetIsolate());
-        result->holder()->LookupRealNamedPropertyInPrototypes(name, &r);
+        LookupResult r(isolate);
+        result->holder()->LookupRealNamedPropertyInPrototypes(*name, &r);
         if (r.IsProperty()) {
-          return GetPropertyWithFailedAccessCheck(receiver,
-                                                  &r,
-                                                  name,
-                                                  attributes);
+          return GetPropertyWithFailedAccessCheck(
+              object, receiver, &r, name, attributes);
         }
         break;
       }
       case INTERCEPTOR: {
         // If the object has an interceptor, try real named properties.
         // No access check in GetPropertyAttributeWithInterceptor.
-        LookupResult r(GetIsolate());
-        result->holder()->LookupRealNamedProperty(name, &r);
+        LookupResult r(isolate);
+        result->holder()->LookupRealNamedProperty(*name, &r);
         if (r.IsProperty()) {
-          return GetPropertyWithFailedAccessCheck(receiver,
-                                                  &r,
-                                                  name,
-                                                  attributes);
+          return GetPropertyWithFailedAccessCheck(
+              object, receiver, &r, name, attributes);
         }
         break;
       }
       default:
         UNREACHABLE();
     }
   }
 
   // No accessible property found.
   *attributes = ABSENT;
-  Heap* heap = name->GetHeap();
-  Isolate* isolate = heap->isolate();
-  isolate->ReportFailedAccessCheck(this, v8::ACCESS_GET);
-  RETURN_IF_SCHEDULED_EXCEPTION(isolate);
-  return heap->undefined_value();
+  isolate->ReportFailedAccessCheck(*object, v8::ACCESS_GET);
+  RETURN_HANDLE_IF_SCHEDULED_EXCEPTION(isolate, Object);
+  return isolate->factory()->undefined_value();
 }
 
 
 PropertyAttributes JSObject::GetPropertyAttributeWithFailedAccessCheck(
     Object* receiver,
     LookupResult* result,
     Name* name,
     bool continue_search) {
   if (result->IsProperty()) {
     switch (result->type()) {
@@ skipping 225 matching lines @@
                                        LookupResult* result,
                                        Handle<Name> key,
                                        PropertyAttributes* attributes) {
   Isolate* isolate = result->isolate();
   CALL_HEAP_FUNCTION_PASS_EXCEPTION(
       isolate,
       object->GetProperty(*receiver, result, *key, attributes));
 }
 
 
+// TODO(yangguo): handlify this and get rid of.
 MaybeObject* Object::GetProperty(Object* receiver,
                                  LookupResult* result,
                                  Name* name,
                                  PropertyAttributes* attributes) {
   Isolate* isolate = name->GetIsolate();
   Heap* heap = isolate->heap();
 
 #ifdef DEBUG
   // TODO(mstarzinger): Only because of the AssertNoContextChange, drop as soon
   // as this method has been fully handlified.
@@ skipping 18 matching lines @@
     ASSERT(this != this->GetPrototype(isolate));
     for (Object* current = this;
          true;
          current = current->GetPrototype(isolate)) {
       if (current->IsAccessCheckNeeded()) {
         // Check if we're allowed to read from the current object. Note
         // that even though we may not actually end up loading the named
         // property from the current object, we still check that we have
         // access to it.
         JSObject* checked = JSObject::cast(current);
-        if (!heap->isolate()->MayNamedAccess(checked, name, v8::ACCESS_GET)) {
-          return checked->GetPropertyWithFailedAccessCheck(receiver,
-                                                           result,
-                                                           name,
-                                                           attributes);
+        if (!isolate->MayNamedAccess(checked, name, v8::ACCESS_GET)) {
+          HandleScope scope(isolate);
+          Handle<Object> value = JSObject::GetPropertyWithFailedAccessCheck(
+              handle(checked, isolate),
+              handle(receiver, isolate),
+              result,
+              handle(name, isolate),
+              attributes);
+          RETURN_IF_EMPTY_HANDLE(isolate, value);
+          return *value;
         }
       }
       // Stop traversing the chain once we reach the last object in the
       // chain; either the holder of the result or null in case of an
       // absent property.
       if (current == last) break;
     }
   }
 
   if (!result->IsProperty()) {
@@ skipping 10 matching lines @@
     case FIELD: {
       MaybeObject* maybe_result = result->holder()->FastPropertyAt(
           result->representation(),
           result->GetFieldIndex().field_index());
       if (!maybe_result->To(&value)) return maybe_result;
       ASSERT(!value->IsTheHole() || result->IsReadOnly());
       return value->IsTheHole() ? heap->undefined_value() : value;
     }
     case CONSTANT:
       return result->GetConstant();
-    case CALLBACKS:
-      return result->holder()->GetPropertyWithCallback(
-          receiver, result->GetCallbackObject(), name);
+    case CALLBACKS: {
+      HandleScope scope(isolate);
+      Handle<Object> value = JSObject::GetPropertyWithCallback(
+          handle(result->holder(), isolate),
+          handle(receiver, isolate),
+          handle(result->GetCallbackObject(), isolate),
+          handle(name, isolate));
+      RETURN_IF_EMPTY_HANDLE(isolate, value);
+      return *value;
+    }
     case HANDLER:
       return result->proxy()->GetPropertyWithHandler(receiver, name);
-    case INTERCEPTOR:
-      return result->holder()->GetPropertyWithInterceptor(
-          receiver, name, attributes);
+    case INTERCEPTOR: {
+      HandleScope scope(isolate);
+      Handle<Object> value = JSObject::GetPropertyWithInterceptor(
+          handle(result->holder(), isolate),
+          handle(receiver, isolate),
+          handle(name, isolate),
+          attributes);
+      RETURN_IF_EMPTY_HANDLE(isolate, value);
+      return *value;
+    }
     case TRANSITION:
     case NONEXISTENT:
       UNREACHABLE();
       break;
   }
   UNREACHABLE();
   return NULL;
 }
 
 
@@ skipping 258 matching lines @@
     default:
       return this;
   }
 }
 
 
 bool String::MakeExternal(v8::String::ExternalStringResource* resource) {
   // Externalizing twice leaks the external resource, so it's
   // prohibited by the API.
   ASSERT(!this->IsExternalString());
-#ifdef DEBUG
+#ifdef ENABLE_SLOW_ASSERTS
   if (FLAG_enable_slow_asserts) {
     // Assert that the resource and the string are equivalent.
     ASSERT(static_cast<size_t>(this->length()) == resource->length());
     ScopedVector<uc16> smart_chars(this->length());
     String::WriteToFlat(this, smart_chars.start(), 0, this->length());
     ASSERT(memcmp(smart_chars.start(),
                   resource->data(),
                   resource->length() * sizeof(smart_chars[0])) == 0);
   }
 #endif  // DEBUG
@@ skipping 36 matching lines @@
   heap->CreateFillerObjectAt(this->address() + new_size, size - new_size);
   if (Marking::IsBlack(Marking::MarkBitFrom(this))) {
     MemoryChunk::IncrementLiveBytesFromMutator(this->address(),
                                                new_size - size);
   }
   return true;
 }
 
 
 bool String::MakeExternal(v8::String::ExternalAsciiStringResource* resource) {
-#ifdef DEBUG
+#ifdef ENABLE_SLOW_ASSERTS
   if (FLAG_enable_slow_asserts) {
     // Assert that the resource and the string are equivalent.
     ASSERT(static_cast<size_t>(this->length()) == resource->length());
     if (this->IsTwoByteRepresentation()) {
       ScopedVector<uint16_t> smart_chars(this->length());
       String::WriteToFlat(this, smart_chars.start(), 0, this->length());
       ASSERT(String::IsOneByte(smart_chars.start(), this->length()));
     }
     ScopedVector<char> smart_chars(this->length());
     String::WriteToFlat(this, smart_chars.start(), 0, this->length());
@@ skipping 464 matching lines @@
         }
         break;
     }
     return;
   }
 
   switch (type) {
     case FIXED_ARRAY_TYPE:
       FixedArray::BodyDescriptor::IterateBody(this, object_size, v);
       break;
+    case CONSTANT_POOL_ARRAY_TYPE:
+      reinterpret_cast<ConstantPoolArray*>(this)->ConstantPoolIterateBody(v);
+      break;
     case FIXED_DOUBLE_ARRAY_TYPE:
       break;
     case JS_OBJECT_TYPE:
     case JS_CONTEXT_EXTENSION_OBJECT_TYPE:
     case JS_GENERATOR_OBJECT_TYPE:
     case JS_MODULE_TYPE:
     case JS_VALUE_TYPE:
     case JS_DATE_TYPE:
     case JS_ARRAY_TYPE:
     case JS_ARRAY_BUFFER_TYPE:
@@ skipping 376 matching lines @@
     } else {
       // Normalize the object to prevent very large instance descriptors.
       // This eliminates unwanted N^2 allocation and lookup behavior.
       NormalizeProperties(object, CLEAR_INOBJECT_PROPERTIES, 0);
       AddSlowProperty(object, name, value, attributes);
     }
   } else {
     AddSlowProperty(object, name, value, attributes);
   }
 
-  if (FLAG_harmony_observation && object->map()->is_observed()) {
+  if (FLAG_harmony_observation &&
+      object->map()->is_observed() &&
+      *name != isolate->heap()->hidden_string()) {
     Handle<Object> old_value = isolate->factory()->the_hole_value();
     EnqueueChangeRecord(object, "new", name, old_value);
   }
 
   return value;
 }
 
 
 void JSObject::EnqueueChangeRecord(Handle<JSObject> object,
                                    const char* type_str,
@@ skipping 130 matching lines @@
   elms->set_length(len - to_trim);
 
   // Maintain marking consistency for IncrementalMarking.
   if (Marking::IsBlack(Marking::MarkBitFrom(elms))) {
     if (trim_mode == FROM_GC) {
       MemoryChunk::IncrementLiveBytesFromGC(elms->address(), -size_delta);
     } else {
       MemoryChunk::IncrementLiveBytesFromMutator(elms->address(), -size_delta);
     }
   }
+
+  // The array may not be moved during GC,
+  // and size has to be adjusted nevertheless.
+  HeapProfiler* profiler = heap->isolate()->heap_profiler();
+  if (profiler->is_tracking_allocations()) {
+    profiler->UpdateObjectSizeEvent(elms->address(), elms->Size());
+  }
 }
 
 
 bool Map::InstancesNeedRewriting(Map* target,
                                  int target_number_of_fields,
                                  int target_inobject,
                                  int target_unused) {
   // If fields were added (or removed), rewrite the instance.
   int number_of_fields = NumberOfFields();
   ASSERT(target_number_of_fields >= number_of_fields);
@@ skipping 117 matching lines @@
   // size and install the backing store into the object.
   if (external > 0) {
     RightTrimFixedArray<FROM_MUTATOR>(isolate->heap(), *array, inobject);
     object->set_properties(*array);
   }
 
   object->set_map(*new_map);
 }
 
 
+Handle<TransitionArray> Map::AddTransition(Handle<Map> map,
+                                           Handle<Name> key,
+                                           Handle<Map> target,
+                                           SimpleTransitionFlag flag) {
+  CALL_HEAP_FUNCTION(map->GetIsolate(),
+                     map->AddTransition(*key, *target, flag),
+                     TransitionArray);
+}
+
+
 void JSObject::GeneralizeFieldRepresentation(Handle<JSObject> object,
                                              int modify_index,
                                              Representation new_representation,
                                              StoreMode store_mode) {
   Handle<Map> new_map = Map::GeneralizeRepresentation(
       handle(object->map()), modify_index, new_representation, store_mode);
   if (object->map() == *new_map) return;
   return MigrateToMap(object, new_map);
 }
 
@@ skipping 280 matching lines @@
   for (; descriptor < descriptors; descriptor++) {
     new_map = Map::CopyInstallDescriptors(new_map, descriptor, new_descriptors);
     new_map->set_migration_target(true);
   }
 
   new_map->set_owns_descriptors(true);
   return new_map;
 }
 
 
+// Generalize the representation of all FIELD descriptors.
+Handle<Map> Map::GeneralizeAllFieldRepresentations(
+    Handle<Map> map,
+    Representation new_representation) {
+  Handle<DescriptorArray> descriptors(map->instance_descriptors());
+  for (int i = 0; i < map->NumberOfOwnDescriptors(); i++) {
+    PropertyDetails details = descriptors->GetDetails(i);
+    if (details.type() == FIELD) {
+      map = GeneralizeRepresentation(map, i, new_representation, FORCE_FIELD);
+    }
+  }
+  return map;
+}
+
+
 Map* Map::CurrentMapForDeprecated() {
   DisallowHeapAllocation no_allocation;
   if (!is_deprecated()) return this;
 
   DescriptorArray* old_descriptors = instance_descriptors();
 
   int descriptors = NumberOfOwnDescriptors();
   Map* root_map = FindRootMap();
 
   // Check the state of the root map.
@@ skipping 1263 matching lines @@
       Handle<Object> error = isolate->factory()->NewTypeError(
           "strict_read_only_property", HandleVector(args, ARRAY_SIZE(args)));
       isolate->Throw(*error);
       return Handle<Object>();
     } else {
       return value;
     }
   }
 
   Handle<Object> old_value = isolate->factory()->the_hole_value();
-  if (FLAG_harmony_observation &&
-      object->map()->is_observed() && lookup->IsDataProperty()) {
+  bool is_observed = FLAG_harmony_observation &&
+                     object->map()->is_observed() &&
+                     *name != isolate->heap()->hidden_string();
+  if (is_observed && lookup->IsDataProperty()) {
     old_value = Object::GetProperty(object, name);
   }
 
   // This is a real property that is not read-only, or it is a
   // transition or null descriptor and there are no setters in the prototypes.
   Handle<Object> result = value;
   switch (lookup->type()) {
     case NORMAL:
       SetNormalizedProperty(handle(lookup->holder()), lookup, value);
       break;
@@ skipping 18 matching lines @@
       result = SetPropertyUsingTransition(handle(lookup->holder()), lookup,
                                           name, value, attributes);
       break;
     case HANDLER:
     case NONEXISTENT:
       UNREACHABLE();
   }
 
   RETURN_IF_EMPTY_HANDLE_VALUE(isolate, result, Handle<Object>());
 
-  if (FLAG_harmony_observation && object->map()->is_observed()) {
+  if (is_observed) {
     if (lookup->IsTransition()) {
       EnqueueChangeRecord(object, "new", name, old_value);
     } else {
       LookupResult new_lookup(isolate);
       object->LocalLookup(*name, &new_lookup, true);
       if (new_lookup.IsDataProperty()) {
         Handle<Object> new_value = Object::GetProperty(object, name);
         if (!new_value->SameValue(*old_value)) {
           EnqueueChangeRecord(object, "updated", name, old_value);
         }
@@ skipping 80 matching lines @@
 
   // Check for accessor in prototype chain removed here in clone.
   if (!lookup.IsFound()) {
     // Neither properties nor transitions found.
     return AddProperty(object, name, value, attributes, kNonStrictMode,
         MAY_BE_STORE_FROM_KEYED, extensibility_check, value_type, mode);
   }
 
   Handle<Object> old_value = isolate->factory()->the_hole_value();
   PropertyAttributes old_attributes = ABSENT;
-  bool is_observed = FLAG_harmony_observation && object->map()->is_observed();
+  bool is_observed = FLAG_harmony_observation &&
+                     object->map()->is_observed() &&
+                     *name != isolate->heap()->hidden_string();
   if (is_observed && lookup.IsProperty()) {
     if (lookup.IsDataProperty()) old_value =
         Object::GetProperty(object, name);
     old_attributes = lookup.GetAttributes();
   }
 
   // Check of IsReadOnly removed from here in clone.
   switch (lookup.type()) {
     case NORMAL:
       ReplaceSlowProperty(object, name, value, attributes);
@@ skipping 265 matching lines @@
   }
   if (pt->IsNull()) return ABSENT;
   return JSObject::cast(pt)->GetElementAttributeWithReceiver(
       receiver, index, true);
 }
 
 
 Handle<Map> NormalizedMapCache::Get(Handle<NormalizedMapCache> cache,
                                     Handle<JSObject> obj,
                                     PropertyNormalizationMode mode) {
-  Map* fast = obj->map();
-  int index = fast->Hash() % kEntries;
-  Object* result = cache->get(index);
+  int index = obj->map()->Hash() % kEntries;
+  Handle<Object> result = handle(cache->get(index), cache->GetIsolate());
   if (result->IsMap() &&
-      Map::cast(result)->EquivalentToForNormalization(fast, mode)) {
+      Handle<Map>::cast(result)->EquivalentToForNormalization(obj->map(),
+                                                              mode)) {
 #ifdef VERIFY_HEAP
     if (FLAG_verify_heap) {
-      Map::cast(result)->SharedMapVerify();
+      Handle<Map>::cast(result)->SharedMapVerify();
     }
 #endif
-#ifdef DEBUG
+#ifdef ENABLE_SLOW_ASSERTS
     if (FLAG_enable_slow_asserts) {
       // The cached map should match newly created normalized map bit-by-bit,
       // except for the code cache, which can contain some ics which can be
       // applied to the shared map.
-      Object* fresh;
-      MaybeObject* maybe_fresh =
-          fast->CopyNormalized(mode, SHARED_NORMALIZED_MAP);
-      if (maybe_fresh->ToObject(&fresh)) {
-        ASSERT(memcmp(Map::cast(fresh)->address(),
-                      Map::cast(result)->address(),
-                      Map::kCodeCacheOffset) == 0);
-        STATIC_ASSERT(Map::kDependentCodeOffset ==
-                      Map::kCodeCacheOffset + kPointerSize);
-        int offset = Map::kDependentCodeOffset + kPointerSize;
-        ASSERT(memcmp(Map::cast(fresh)->address() + offset,
-                      Map::cast(result)->address() + offset,
-                      Map::kSize - offset) == 0);
-      }
+      Handle<Map> fresh = Map::CopyNormalized(handle(obj->map()), mode,
+                                              SHARED_NORMALIZED_MAP);
+
+      ASSERT(memcmp(fresh->address(),
+                    Handle<Map>::cast(result)->address(),
+                    Map::kCodeCacheOffset) == 0);
+      STATIC_ASSERT(Map::kDependentCodeOffset ==
+                    Map::kCodeCacheOffset + kPointerSize);
+      int offset = Map::kDependentCodeOffset + kPointerSize;
+      ASSERT(memcmp(fresh->address() + offset,
+                    Handle<Map>::cast(result)->address() + offset,
+                    Map::kSize - offset) == 0);
     }
 #endif
-    return handle(Map::cast(result));
+    return Handle<Map>::cast(result);
   }
 
   Isolate* isolate = cache->GetIsolate();
-  Handle<Map> map = Map::CopyNormalized(handle(fast), mode,
+  Handle<Map> map = Map::CopyNormalized(handle(obj->map()), mode,
                                         SHARED_NORMALIZED_MAP);
   ASSERT(map->is_dictionary_map());
   cache->set(index, *map);
   isolate->counters()->normalized_maps()->Increment();
 
   return map;
 }
 
 
 void NormalizedMapCache::Clear() {
@@ skipping 722 matching lines @@
       Handle<Object> args[2] = { name, object };
       Handle<Object> error = isolate->factory()->NewTypeError(
           "strict_delete_property", HandleVector(args, ARRAY_SIZE(args)));
       isolate->Throw(*error);
       return Handle<Object>();
     }
     return isolate->factory()->false_value();
   }
 
   Handle<Object> old_value = isolate->factory()->the_hole_value();
-  bool is_observed = FLAG_harmony_observation && object->map()->is_observed();
+  bool is_observed = FLAG_harmony_observation &&
+                     object->map()->is_observed() &&
+                     *name != isolate->heap()->hidden_string();
   if (is_observed && lookup.IsDataProperty()) {
     old_value = Object::GetProperty(object, name);
   }
   Handle<Object> result;
 
   // Check for interceptor.
   if (lookup.IsInterceptor()) {
     // Skip interceptor if forcing a deletion.
     if (mode == FORCE_DELETION) {
       result = DeletePropertyPostInterceptor(object, name, mode);
@@ skipping 341 matching lines @@
     // Make sure we never go back to the fast case
     dictionary->set_requires_slow_elements();
     // Freeze all elements in the dictionary
     FreezeDictionary(dictionary);
   }
 
   return object;
 }
 
 
-MUST_USE_RESULT MaybeObject* JSObject::SetObserved(Isolate* isolate) {
-  if (map()->is_observed())
-    return isolate->heap()->undefined_value();
+void JSObject::SetObserved(Handle<JSObject> object) {
+  Isolate* isolate = object->GetIsolate();
 
-  Heap* heap = isolate->heap();
+  if (object->map()->is_observed())
+    return;
 
-  if (!HasExternalArrayElements()) {
+  if (!object->HasExternalArrayElements()) {
     // Go to dictionary mode, so that we don't skip map checks.
-    MaybeObject* maybe = NormalizeElements();
-    if (maybe->IsFailure()) return maybe;
-    ASSERT(!HasFastElements());
+    NormalizeElements(object);
+    ASSERT(!object->HasFastElements());
   }
 
   LookupResult result(isolate);
-  map()->LookupTransition(this, heap->observed_symbol(), &result);
+  object->map()->LookupTransition(*object,
+                                  isolate->heap()->observed_symbol(),
+                                  &result);
 
-  Map* new_map;
+  Handle<Map> new_map;
   if (result.IsTransition()) {
-    new_map = result.GetTransitionTarget();
+    new_map = handle(result.GetTransitionTarget());
     ASSERT(new_map->is_observed());
-  } else if (map()->CanHaveMoreTransitions()) {
-    MaybeObject* maybe_new_map = map()->CopyForObserved();
-    if (!maybe_new_map->To(&new_map)) return maybe_new_map;
+  } else if (object->map()->CanHaveMoreTransitions()) {
+    new_map = Map::CopyForObserved(handle(object->map()));
   } else {
-    MaybeObject* maybe_copy = map()->Copy();
-    if (!maybe_copy->To(&new_map)) return maybe_copy;
+    new_map = Map::Copy(handle(object->map()));
     new_map->set_is_observed(true);
   }
-  set_map(new_map);
-
-  return heap->undefined_value();
+  object->set_map(*new_map);
 }
 
 
+Handle<JSObject> JSObject::Copy(Handle<JSObject> object,
+                                Handle<AllocationSite> site) {
+  Isolate* isolate = object->GetIsolate();
+  CALL_HEAP_FUNCTION(isolate,
+                     isolate->heap()->CopyJSObject(*object, *site), JSObject);
+}
+
+
 Handle<JSObject> JSObject::Copy(Handle<JSObject> object) {
   Isolate* isolate = object->GetIsolate();
   CALL_HEAP_FUNCTION(isolate,
                      isolate->heap()->CopyJSObject(*object), JSObject);
 }
 
 
 class JSObjectWalkVisitor {
  public:
-  explicit JSObjectWalkVisitor() {}
+  explicit JSObjectWalkVisitor(AllocationSiteContext* site_context) :
+      site_context_(site_context) {}
   virtual ~JSObjectWalkVisitor() {}
 
   Handle<JSObject> Visit(Handle<JSObject> object) {
     return StructureWalk(object);
   }
 
-  // Returns true if the visitor is a copying visitor.
   virtual bool is_copying() = 0;
 
  protected:
   Handle<JSObject> StructureWalk(Handle<JSObject> object);
 
-  // The returned handle should point to a new object if the visitor is a
-  // copying visitor, otherwise it should be the same as the input object.
+  // The returned handle will be used for the object in all subsequent usages.
+  // This allows VisitObject to make a copy of the object if desired.
   virtual Handle<JSObject> VisitObject(Handle<JSObject> object) = 0;
-
-  // The returned handle should point to a new value if the visitor is a
-  // copying visitor, otherwise it should be the same as the input value.
   virtual Handle<JSObject> VisitElementOrProperty(Handle<JSObject> object,
                                                   Handle<JSObject> value) = 0;
+
+  AllocationSiteContext* site_context() { return site_context_; }
+
+ private:
+  AllocationSiteContext* site_context_;
 };
 
 
 class JSObjectCopyVisitor: public JSObjectWalkVisitor {
  public:
-  explicit JSObjectCopyVisitor() {}
+  explicit JSObjectCopyVisitor(AllocationSiteContext* site_context)
+      : JSObjectWalkVisitor(site_context) {}
 
   virtual bool is_copying() V8_OVERRIDE { return true; }
 
- protected:
+  // The returned handle will be used for the object in all
+  // subsequent usages. This allows VisitObject to make a copy
+  // of the object if desired.
   virtual Handle<JSObject> VisitObject(Handle<JSObject> object) V8_OVERRIDE {
-    return JSObject::Copy(object);
+    // Only create a memento if
+    // 1) we have a JSArray, and
+    // 2) the elements kind is palatable
+    // 3) allow_mementos is true
+    Handle<JSObject> copy;
+    if (site_context()->activated() &&
+        AllocationSite::CanTrack(object->map()->instance_type()) &&
+        AllocationSite::GetMode(object->GetElementsKind()) ==
+        TRACK_ALLOCATION_SITE) {
+      copy = JSObject::Copy(object, site_context()->current());
+    } else {
+      copy = JSObject::Copy(object);
+    }
+
+    return copy;
   }
 
   virtual Handle<JSObject> VisitElementOrProperty(
       Handle<JSObject> object,
       Handle<JSObject> value) V8_OVERRIDE {
-    return StructureWalk(value);
+    Handle<AllocationSite> current_site = site_context()->EnterNewScope();
+    Handle<JSObject> copy_of_value = StructureWalk(value);
+    site_context()->ExitScope(current_site, value);
+    return copy_of_value;
   }
 };
 
+
+class JSObjectCreateAllocationSitesVisitor: public JSObjectWalkVisitor {
+ public:
+  explicit JSObjectCreateAllocationSitesVisitor(
+      AllocationSiteContext* site_context)
+      : JSObjectWalkVisitor(site_context) {}
+
+  virtual bool is_copying() V8_OVERRIDE { return false; }
+
+  // The returned handle will be used for the object in all
+  // subsequent usages. This allows VisitObject to make a copy
+  // of the object if desired.
+  virtual Handle<JSObject> VisitObject(Handle<JSObject> object) V8_OVERRIDE {
+    return object;
+  }
+
+  virtual Handle<JSObject> VisitElementOrProperty(
+      Handle<JSObject> object,
+      Handle<JSObject> value) V8_OVERRIDE {
+    Handle<AllocationSite> current_site = site_context()->EnterNewScope();
+    value = StructureWalk(value);
+    site_context()->ExitScope(current_site, value);
+    return value;
+  }
+};
+
 
 Handle<JSObject> JSObjectWalkVisitor::StructureWalk(Handle<JSObject> object) {
   bool copying = is_copying();
   Isolate* isolate = object->GetIsolate();
   StackLimitCheck check(isolate);
   if (check.HasOverflowed()) {
     isolate->StackOverflow();
     return Handle<JSObject>::null();
   }
 
@@ skipping 123 matching lines @@
     case EXTERNAL_DOUBLE_ELEMENTS:
     case FAST_DOUBLE_ELEMENTS:
     case FAST_HOLEY_DOUBLE_ELEMENTS:
       // No contained objects, nothing to do.
       break;
   }
   return copy;
 }
 
 
-Handle<JSObject> JSObject::DeepCopy(Handle<JSObject> object) {
-  JSObjectCopyVisitor v;
+Handle<JSObject> JSObject::DeepWalk(Handle<JSObject> object,
+                                    AllocationSiteContext* site_context) {
+  JSObjectCreateAllocationSitesVisitor v(site_context);
+  Handle<JSObject> result = v.Visit(object);
+  ASSERT(!v.is_copying() &&
+         (result.is_null() || result.is_identical_to(object)));
+  return result;
+}
+
+
+Handle<JSObject> JSObject::DeepCopy(Handle<JSObject> object,
+                                    AllocationSiteContext* site_context) {
+  JSObjectCopyVisitor v(site_context);
   Handle<JSObject> copy = v.Visit(object);
   ASSERT(v.is_copying() && !copy.is_identical_to(object));
   return copy;
 }
 
 
 // Tests for the fast common case for property enumeration:
 // - This object and all prototypes has an enum cache (which means that
 //   it is no proxy, has no interceptors and needs no access checks).
 // - This object has no elements.
@@ skipping 396 matching lines @@
 
   // Try to flatten before operating on the string.
   if (name->IsString()) String::cast(*name)->TryFlatten();
 
   if (!object->CanSetCallback(*name)) return;
 
   uint32_t index = 0;
   bool is_element = name->AsArrayIndex(&index);
 
   Handle<Object> old_value = isolate->factory()->the_hole_value();
-  bool is_observed = FLAG_harmony_observation && object->map()->is_observed();
+  bool is_observed = FLAG_harmony_observation &&
+                     object->map()->is_observed() &&
+                     *name != isolate->heap()->hidden_string();
   bool preexists = false;
   if (is_observed) {
     if (is_element) {
       preexists = HasLocalElement(object, index);
       if (preexists && object->GetLocalElementAccessorPair(index) == NULL) {
         old_value = Object::GetElement(isolate, object, index);
       }
     } else {
       LookupResult lookup(isolate);
       object->LocalLookup(*name, &lookup, true);
@@ skipping 234 matching lines @@
       !isolate->MayNamedAccess(*object, *name, v8::ACCESS_HAS)) {
     isolate->ReportFailedAccessCheck(*object, v8::ACCESS_HAS);
     RETURN_HANDLE_IF_SCHEDULED_EXCEPTION(isolate, Object);
     return isolate->factory()->undefined_value();
   }
 
   // Make the lookup and include prototypes.
   uint32_t index = 0;
   if (name->AsArrayIndex(&index)) {
     for (Handle<Object> obj = object;
-         *obj != isolate->heap()->null_value();
+         !obj->IsNull();
          obj = handle(JSReceiver::cast(*obj)->GetPrototype(), isolate)) {
       if (obj->IsJSObject() && JSObject::cast(*obj)->HasDictionaryElements()) {
         JSObject* js_object = JSObject::cast(*obj);
         SeededNumberDictionary* dictionary = js_object->element_dictionary();
         int entry = dictionary->FindEntry(index);
         if (entry != SeededNumberDictionary::kNotFound) {
           Object* element = dictionary->ValueAt(entry);
           if (dictionary->DetailsAt(entry).type() == CALLBACKS &&
               element->IsAccessorPair()) {
             return handle(AccessorPair::cast(element)->GetComponent(component),
                           isolate);
           }
         }
       }
     }
   } else {
     for (Handle<Object> obj = object;
-         *obj != isolate->heap()->null_value();
+         !obj->IsNull();
          obj = handle(JSReceiver::cast(*obj)->GetPrototype(), isolate)) {
       LookupResult result(isolate);
       JSReceiver::cast(*obj)->LocalLookup(*name, &result);
       if (result.IsFound()) {
         if (result.IsReadOnly()) return isolate->factory()->undefined_value();
         if (result.IsPropertyCallbacks()) {
           Object* obj = result.GetCallbackObject();
           if (obj->IsAccessorPair()) {
             return handle(AccessorPair::cast(obj)->GetComponent(component),
                           isolate);
@@ skipping 28 matching lines @@
         }
       }
     }
     return GetHeap()->undefined_value();
   } else {
     return property_dictionary()->SlowReverseLookup(value);
   }
 }
 
 
+Handle<Map> Map::RawCopy(Handle<Map> map,
+                         int instance_size) {
+  CALL_HEAP_FUNCTION(map->GetIsolate(),
+                     map->RawCopy(instance_size),
+                     Map);
+}
+
+
 MaybeObject* Map::RawCopy(int instance_size) {
   Map* result;
   MaybeObject* maybe_result =
       GetHeap()->AllocateMap(instance_type(), instance_size);
   if (!maybe_result->To(&result)) return maybe_result;
 
   result->set_prototype(prototype());
   result->set_constructor(constructor());
   result->set_bit_field(bit_field());
   result->set_bit_field2(bit_field2());
   int new_bit_field3 = bit_field3();
   new_bit_field3 = OwnsDescriptors::update(new_bit_field3, true);
   new_bit_field3 = NumberOfOwnDescriptorsBits::update(new_bit_field3, 0);
   new_bit_field3 = EnumLengthBits::update(new_bit_field3, kInvalidEnumCache);
   new_bit_field3 = Deprecated::update(new_bit_field3, false);
   new_bit_field3 = IsUnstable::update(new_bit_field3, false);
   result->set_bit_field3(new_bit_field3);
   return result;
 }
 
 
 Handle<Map> Map::CopyNormalized(Handle<Map> map,
                                 PropertyNormalizationMode mode,
                                 NormalizedMapSharingMode sharing) {
-  CALL_HEAP_FUNCTION(map->GetIsolate(),
-                     map->CopyNormalized(mode, sharing),
-                     Map);
-}
-
-
-MaybeObject* Map::CopyNormalized(PropertyNormalizationMode mode,
-                                 NormalizedMapSharingMode sharing) {
-  int new_instance_size = instance_size();
+  int new_instance_size = map->instance_size();
   if (mode == CLEAR_INOBJECT_PROPERTIES) {
-    new_instance_size -= inobject_properties() * kPointerSize;
+    new_instance_size -= map->inobject_properties() * kPointerSize;
   }
 
-  Map* result;
-  MaybeObject* maybe_result = RawCopy(new_instance_size);
-  if (!maybe_result->To(&result)) return maybe_result;
+  Handle<Map> result = Map::RawCopy(map, new_instance_size);
 
   if (mode != CLEAR_INOBJECT_PROPERTIES) {
-    result->set_inobject_properties(inobject_properties());
+    result->set_inobject_properties(map->inobject_properties());
   }
 
   result->set_is_shared(sharing == SHARED_NORMALIZED_MAP);
   result->set_dictionary_map(true);
   result->set_migration_target(false);
 
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap && result->is_shared()) {
     result->SharedMapVerify();
   }
@@ skipping 129 matching lines @@
     set_transitions(transitions);
     result->SetBackPointer(this);
   } else {
     descriptors->InitializeRepresentations(Representation::Tagged());
   }
 
   return result;
 }
 
 
-Handle<Map> Map::CopyInstallDescriptors(Handle<Map> map,
-                                        int new_descriptor,
-                                        Handle<DescriptorArray> descriptors) {
-  CALL_HEAP_FUNCTION(map->GetIsolate(),
-                     map->CopyInstallDescriptors(new_descriptor, *descriptors),
-                     Map);
-}
-
-
 // Since this method is used to rewrite an existing transition tree, it can
 // always insert transitions without checking.
-MaybeObject* Map::CopyInstallDescriptors(int new_descriptor,
-                                         DescriptorArray* descriptors) {
+Handle<Map> Map::CopyInstallDescriptors(Handle<Map> map,
+                                        int new_descriptor,
+                                        Handle<DescriptorArray> descriptors) {
   ASSERT(descriptors->IsSortedNoDuplicates());
 
-  Map* result;
-  MaybeObject* maybe_result = CopyDropDescriptors();
-  if (!maybe_result->To(&result)) return maybe_result;
+  Handle<Map> result = Map::CopyDropDescriptors(map);
 
-  result->InitializeDescriptors(descriptors);
+  result->InitializeDescriptors(*descriptors);
   result->SetNumberOfOwnDescriptors(new_descriptor + 1);
 
-  int unused_property_fields = this->unused_property_fields();
+  int unused_property_fields = map->unused_property_fields();
   if (descriptors->GetDetails(new_descriptor).type() == FIELD) {
-    unused_property_fields = this->unused_property_fields() - 1;
+    unused_property_fields = map->unused_property_fields() - 1;
     if (unused_property_fields < 0) {
       unused_property_fields += JSObject::kFieldsAdded;
     }
   }
 
   result->set_unused_property_fields(unused_property_fields);
   result->set_owns_descriptors(false);
 
-  Name* name = descriptors->GetKey(new_descriptor);
-  TransitionArray* transitions;
-  MaybeObject* maybe_transitions =
-      AddTransition(name, result, SIMPLE_TRANSITION);
-  if (!maybe_transitions->To(&transitions)) return maybe_transitions;
+  Handle<Name> name = handle(descriptors->GetKey(new_descriptor));
+  Handle<TransitionArray> transitions = Map::AddTransition(map, name, result,
+                                                           SIMPLE_TRANSITION);
 
-  set_transitions(transitions);
-  result->SetBackPointer(this);
+  map->set_transitions(*transitions);
+  result->SetBackPointer(*map);
 
   return result;
 }
 
 
 MaybeObject* Map::CopyAsElementsKind(ElementsKind kind, TransitionFlag flag) {
   if (flag == INSERT_TRANSITION) {
     ASSERT(!HasElementsTransition() ||
         ((elements_transition_map()->elements_kind() == DICTIONARY_ELEMENTS ||
           IsExternalArrayElementsKind(
@@ skipping 37 matching lines @@
   if (insert_transition) {
     MaybeObject* added_elements = set_elements_transition_map(new_map);
     if (added_elements->IsFailure()) return added_elements;
     new_map->SetBackPointer(this);
   }
 
   return new_map;
 }
 
 
-MaybeObject* Map::CopyForObserved() {
-  ASSERT(!is_observed());
+Handle<Map> Map::CopyForObserved(Handle<Map> map) {
+  ASSERT(!map->is_observed());
+
+  Isolate* isolate = map->GetIsolate();
 
   // In case the map owned its own descriptors, share the descriptors and
   // transfer ownership to the new map.
-  Map* new_map;
-  MaybeObject* maybe_new_map;
-  if (owns_descriptors()) {
-    maybe_new_map = CopyDropDescriptors();
+  Handle<Map> new_map;
+  if (map->owns_descriptors()) {
+    new_map = Map::CopyDropDescriptors(map);
   } else {
-    maybe_new_map = Copy();
+    new_map = Map::Copy(map);
   }
-  if (!maybe_new_map->To(&new_map)) return maybe_new_map;
 
-  TransitionArray* transitions;
-  MaybeObject* maybe_transitions = AddTransition(GetHeap()->observed_symbol(),
-                                                 new_map,
-                                                 FULL_TRANSITION);
-  if (!maybe_transitions->To(&transitions)) return maybe_transitions;
-  set_transitions(transitions);
+  Handle<TransitionArray> transitions =
+      Map::AddTransition(map, isolate->factory()->observed_symbol(), new_map,
+                         FULL_TRANSITION);
+
+  map->set_transitions(*transitions);
 
   new_map->set_is_observed(true);
 
-  if (owns_descriptors()) {
-    new_map->InitializeDescriptors(instance_descriptors());
-    set_owns_descriptors(false);
+  if (map->owns_descriptors()) {
+    new_map->InitializeDescriptors(map->instance_descriptors());
+    map->set_owns_descriptors(false);
   }
 
-  new_map->SetBackPointer(this);
+  new_map->SetBackPointer(*map);
   return new_map;
 }
 
 
 MaybeObject* Map::CopyWithPreallocatedFieldDescriptors() {
   if (pre_allocated_property_fields() == 0) return CopyDropDescriptors();
 
   // If the map has pre-allocated properties always start out with a descriptor
   // array describing these properties.
   ASSERT(constructor()->IsJSFunction());
@@ skipping 857 matching lines @@
   return cache;
 }
 
 
 MaybeObject* FixedArray::AddKeysFromJSArray(JSArray* array) {
   ElementsAccessor* accessor = array->GetElementsAccessor();
   MaybeObject* maybe_result =
       accessor->AddElementsToFixedArray(array, array, this);
   FixedArray* result;
   if (!maybe_result->To<FixedArray>(&result)) return maybe_result;
-#ifdef DEBUG
+#ifdef ENABLE_SLOW_ASSERTS
   if (FLAG_enable_slow_asserts) {
     for (int i = 0; i < result->length(); i++) {
       Object* current = result->get(i);
       ASSERT(current->IsNumber() || current->IsName());
     }
   }
 #endif
   return result;
 }
 
 
 MaybeObject* FixedArray::UnionOfKeys(FixedArray* other) {
   ElementsAccessor* accessor = ElementsAccessor::ForArray(other);
   MaybeObject* maybe_result =
       accessor->AddElementsToFixedArray(NULL, NULL, this, other);
   FixedArray* result;
   if (!maybe_result->To(&result)) return maybe_result;
-#ifdef DEBUG
+#ifdef ENABLE_SLOW_ASSERTS
   if (FLAG_enable_slow_asserts) {
     for (int i = 0; i < result->length(); i++) {
       Object* current = result->get(i);
       ASSERT(current->IsNumber() || current->IsName());
     }
   }
 #endif
   return result;
 }
 
@@ skipping 1034 matching lines @@
 
 bool String::SlowEquals(String* other) {
   // Fast check: negative check with lengths.
   int len = length();
   if (len != other->length()) return false;
   if (len == 0) return true;
 
   // Fast check: if hash code is computed for both strings
   // a fast negative check can be performed.
   if (HasHashCode() && other->HasHashCode()) {
-#ifdef DEBUG
+#ifdef ENABLE_SLOW_ASSERTS
     if (FLAG_enable_slow_asserts) {
       if (Hash() != other->Hash()) {
         bool found_difference = false;
         for (int i = 0; i < len; i++) {
           if (Get(i) != other->Get(i)) {
             found_difference = true;
             break;
           }
         }
         ASSERT(found_difference);
@@ skipping 234 matching lines @@
 
   Address start_of_string = string->address();
   ASSERT_OBJECT_ALIGNED(start_of_string);
   ASSERT_OBJECT_ALIGNED(start_of_string + new_size);
 
   Heap* heap = string->GetHeap();
   NewSpace* newspace = heap->new_space();
   if (newspace->Contains(start_of_string) &&
       newspace->top() == start_of_string + old_size) {
     // Last allocated object in new space.  Simply lower allocation top.
-    *(newspace->allocation_top_address()) = start_of_string + new_size;
+    newspace->set_top(start_of_string + new_size);
   } else {
     // Sizes are pointer size aligned, so that we can use filler objects
     // that are a multiple of pointer size.
     heap->CreateFillerObjectAt(start_of_string + new_size, delta);
   }
   if (Marking::IsBlack(Marking::MarkBitFrom(start_of_string))) {
     MemoryChunk::IncrementLiveBytesFromMutator(start_of_string, -delta);
   }
 
 
@@ skipping 215 matching lines @@
   // TODO(verwaest) Should be an assert, otherwise back pointers are not
   // properly cleared.
   if (transition_index == t->number_of_transitions()) return;
 
   int number_of_own_descriptors = NumberOfOwnDescriptors();
 
   if (descriptors_owner_died) {
     if (number_of_own_descriptors > 0) {
       TrimDescriptorArray(heap, this, descriptors, number_of_own_descriptors);
       ASSERT(descriptors->number_of_descriptors() == number_of_own_descriptors);
+      set_owns_descriptors(true);
     } else {
       ASSERT(descriptors == GetHeap()->empty_descriptor_array());
     }
   }
 
   int trim = t->number_of_transitions() - transition_index;
   if (trim > 0) {
     RightTrimFixedArray<FROM_GC>(heap, t, t->IsSimpleTransition()
         ? trim : trim * TransitionArray::kTransitionSize);
   }
@@ skipping 36 matching lines @@
 
 
 bool Map::EquivalentToForNormalization(Map* other,
                                        PropertyNormalizationMode mode) {
   int properties = mode == CLEAR_INOBJECT_PROPERTIES
       ? 0 : other->inobject_properties();
   return CheckEquivalent(this, other) && inobject_properties() == properties;
 }
 
 
+void ConstantPoolArray::ConstantPoolIterateBody(ObjectVisitor* v) {
+  int first_ptr_offset = OffsetOfElementAt(first_ptr_index());
+  int last_ptr_offset =
+      OffsetOfElementAt(first_ptr_index() + count_of_ptr_entries());
+  v->VisitPointers(
+      HeapObject::RawField(this, first_ptr_offset),
+      HeapObject::RawField(this, last_ptr_offset));
+}
+
+
 void JSFunction::JSFunctionIterateBody(int object_size, ObjectVisitor* v) {
   // Iterate over all fields in the body but take care in dealing with
   // the code entry.
   IteratePointers(v, kPropertiesOffset, kCodeEntryOffset);
   v->VisitCodeEntry(this->address() + kCodeEntryOffset);
   IteratePointers(v, kCodeEntryOffset + kPointerSize, object_size);
 }
 
 
 void JSFunction::MarkForLazyRecompilation() {
@@ skipping 425 matching lines @@
 //   "-"      all but the top-level function
 //   "-name"  all but the function "name"
 //   ""       only the top-level function
 //   "name"   only the function "name"
 //   "name*"  only functions starting with "name"
 bool JSFunction::PassesFilter(const char* raw_filter) {
   if (*raw_filter == '*') return true;
   String* name = shared()->DebugName();
   Vector<const char> filter = CStrVector(raw_filter);
   if (filter.length() == 0) return name->length() == 0;
-  if (filter[0] != '-' && name->IsUtf8EqualTo(filter)) return true;
-  if (filter[0] == '-' &&
-      !name->IsUtf8EqualTo(filter.SubVector(1, filter.length()))) {
+  if (filter[0] == '-') {
+    if (filter.length() == 1) {
+      return (name->length() != 0);
+    } else if (!name->IsUtf8EqualTo(filter.SubVector(1, filter.length()))) {
+      return true;
+    }
+  } else if (name->IsUtf8EqualTo(filter)) {
     return true;
   }
   if (filter[filter.length() - 1] == '*' &&
       name->IsUtf8EqualTo(filter.SubVector(0, filter.length() - 1), true)) {
     return true;
   }
   return false;
 }
 
 
@@ skipping 384 matching lines @@
 
 
 void ObjectVisitor::VisitEmbeddedPointer(RelocInfo* rinfo) {
   ASSERT(rinfo->rmode() == RelocInfo::EMBEDDED_OBJECT);
   VisitPointer(rinfo->target_object_address());
 }
 
 
 void ObjectVisitor::VisitExternalReference(RelocInfo* rinfo) {
   Address* p = rinfo->target_reference_address();
-  VisitExternalReferences(p, p + 1);
+  VisitExternalReference(p);
 }
 
 
 void Code::InvalidateRelocation() {
   set_relocation_info(GetHeap()->empty_byte_array());
 }
 
 
 void Code::Relocate(intptr_t delta) {
   for (RelocIterator it(this, RelocInfo::kApplyMask); !it.done(); it.next()) {
@@ skipping 36 matching lines @@
     } else if (RelocInfo::IsCodeTarget(mode)) {
       // rewrite code handles in inline cache targets to direct
       // pointers to the first instruction in the code object
       Handle<Object> p = it.rinfo()->target_object_handle(origin);
       Code* code = Code::cast(*p);
       it.rinfo()->set_target_address(code->instruction_start(),
                                      SKIP_WRITE_BARRIER);
     } else if (RelocInfo::IsRuntimeEntry(mode)) {
       Address p = it.rinfo()->target_runtime_entry(origin);
       it.rinfo()->set_target_runtime_entry(p, SKIP_WRITE_BARRIER);
+    } else if (mode == RelocInfo::CODE_AGE_SEQUENCE) {
+      Handle<Object> p = it.rinfo()->code_age_stub_handle(origin);
+      Code* code = Code::cast(*p);
+      it.rinfo()->set_code_age_stub(code);
     } else {
       it.rinfo()->apply(delta);
     }
   }
   CPU::FlushICache(instruction_start(), instruction_size());
 }
 
 
 // Locate the source position which is closest to the address in the code. This
 // is using the source position information embedded in the relocation info.
@@ skipping 217 matching lines @@
   ASSERT(kind() == FUNCTION);
   BackEdgeTable back_edges(this, &no_gc);
   for (uint32_t i = 0; i < back_edges.length(); i++) {
     if (back_edges.pc_offset(i) == pc_offset) return back_edges.ast_id(i);
   }
   return BailoutId::None();
 }
 
 
 void Code::MakeCodeAgeSequenceYoung(byte* sequence, Isolate* isolate) {
-  PatchPlatformCodeAge(isolate, sequence, kNoAge, NO_MARKING_PARITY);
+  PatchPlatformCodeAge(isolate, sequence, kNoAgeCodeAge, NO_MARKING_PARITY);
 }
 
 
+void Code::MarkCodeAsExecuted(byte* sequence, Isolate* isolate) {
+  PatchPlatformCodeAge(isolate, sequence, kExecutedOnceCodeAge,
+      NO_MARKING_PARITY);
+}
+
+
 void Code::MakeOlder(MarkingParity current_parity) {
   byte* sequence = FindCodeAgeSequence();
   if (sequence != NULL) {
     Age age;
     MarkingParity code_parity;
     GetCodeAgeAndParity(sequence, &age, &code_parity);
     if (age != kLastCodeAge && code_parity != current_parity) {
       PatchPlatformCodeAge(GetIsolate(),
                            sequence,
                            static_cast<Age>(age + 1),
                            current_parity);
     }
   }
 }
 
 
 bool Code::IsOld() {
-  byte* sequence = FindCodeAgeSequence();
-  if (sequence == NULL) return false;
-  Age age;
-  MarkingParity parity;
-  GetCodeAgeAndParity(sequence, &age, &parity);
-  return age >= kSexagenarianCodeAge;
+  Age age = GetAge();
+  return age >= kIsOldCodeAge;
 }
 
 
 byte* Code::FindCodeAgeSequence() {
   return FLAG_age_code &&
-      prologue_offset() != kPrologueOffsetNotSet &&
+      prologue_offset() != Code::kPrologueOffsetNotSet &&
       (kind() == OPTIMIZED_FUNCTION ||
        (kind() == FUNCTION && !has_debug_break_slots()))
       ? instruction_start() + prologue_offset()
       : NULL;
 }
 
 
-int Code::GetAge() {
+Code::Age Code::GetAge() {
   byte* sequence = FindCodeAgeSequence();
   if (sequence == NULL) {
-    return Code::kNoAge;
+    return Code::kNoAgeCodeAge;
   }
   Age age;
   MarkingParity parity;
   GetCodeAgeAndParity(sequence, &age, &parity);
   return age;
 }
 
 
 void Code::GetCodeAgeAndParity(Code* code, Age* age,
                                MarkingParity* parity) {
   Isolate* isolate = code->GetIsolate();
   Builtins* builtins = isolate->builtins();
   Code* stub = NULL;
 #define HANDLE_CODE_AGE(AGE)                                            \
   stub = *builtins->Make##AGE##CodeYoungAgainEvenMarking();             \
   if (code == stub) {                                                   \
     *age = k##AGE##CodeAge;                                             \
     *parity = EVEN_MARKING_PARITY;                                      \
     return;                                                             \
   }                                                                     \
   stub = *builtins->Make##AGE##CodeYoungAgainOddMarking();              \
   if (code == stub) {                                                   \
     *age = k##AGE##CodeAge;                                             \
     *parity = ODD_MARKING_PARITY;                                       \
     return;                                                             \
   }
   CODE_AGE_LIST(HANDLE_CODE_AGE)
 #undef HANDLE_CODE_AGE
+  stub = *builtins->MarkCodeAsExecutedOnce();
+  if (code == stub) {
+    // Treat that's never been executed as old immediatly.
+    *age = kIsOldCodeAge;
+    *parity = NO_MARKING_PARITY;
+    return;
+  }
+  stub = *builtins->MarkCodeAsExecutedTwice();
+  if (code == stub) {
+    // Pre-age code that has only been executed once.
+    *age = kPreAgedCodeAge;
+    *parity = NO_MARKING_PARITY;
+    return;
+  }
   UNREACHABLE();
 }
 
 
 Code* Code::GetCodeAgeStub(Isolate* isolate, Age age, MarkingParity parity) {
   Builtins* builtins = isolate->builtins();
   switch (age) {
 #define HANDLE_CODE_AGE(AGE)                                            \
     case k##AGE##CodeAge: {                                             \
       Code* stub = parity == EVEN_MARKING_PARITY                        \
           ? *builtins->Make##AGE##CodeYoungAgainEvenMarking()           \
           : *builtins->Make##AGE##CodeYoungAgainOddMarking();           \
       return stub;                                                      \
     }
     CODE_AGE_LIST(HANDLE_CODE_AGE)
 #undef HANDLE_CODE_AGE
+    case kNotExecutedCodeAge: {
+      ASSERT(parity == NO_MARKING_PARITY);
+      return *builtins->MarkCodeAsExecutedOnce();
+    }
+    case kExecutedOnceCodeAge: {
+      ASSERT(parity == NO_MARKING_PARITY);
+      return *builtins->MarkCodeAsExecutedTwice();
+    }
     default:
       UNREACHABLE();
       break;
   }
   return NULL;
 }
 
 
 void Code::PrintDeoptLocation(int bailout_id) {
   const char* last_comment = NULL;
@@ skipping 1944 matching lines @@
 }
 
 
 void JSObject::TransitionElementsKind(Handle<JSObject> object,
                                       ElementsKind to_kind) {
   CALL_HEAP_FUNCTION_VOID(object->GetIsolate(),
                           object->TransitionElementsKind(to_kind));
 }
 
 
+bool AllocationSite::IsNestedSite() {
+  ASSERT(FLAG_trace_track_allocation_sites);
+  Object* current = GetHeap()->allocation_sites_list();
+  while (current != NULL && current->IsAllocationSite()) {
+    AllocationSite* current_site = AllocationSite::cast(current);
+    if (current_site->nested_site() == this) {
+      return true;
+    }
+    current = current_site->weak_next();
+  }
+  return false;
+}
+
+
 MaybeObject* JSObject::UpdateAllocationSite(ElementsKind to_kind) {
   if (!FLAG_track_allocation_sites || !IsJSArray()) {
     return this;
   }
 
   AllocationMemento* memento = AllocationMemento::FindForJSObject(this);
   if (memento == NULL || !memento->IsValid()) {
     return this;
   }
 
   // Walk through to the Allocation Site
   AllocationSite* site = memento->GetAllocationSite();
-  if (site->IsLiteralSite()) {
+  if (site->SitePointsToLiteral() &&
+      site->transition_info()->IsJSArray()) {
     JSArray* transition_info = JSArray::cast(site->transition_info());
     ElementsKind kind = transition_info->GetElementsKind();
     // if kind is holey ensure that to_kind is as well.
     if (IsHoleyElementsKind(kind)) {
       to_kind = GetHoleyElementsKind(to_kind);
     }
     if (IsMoreGeneralElementsKindTransition(kind, to_kind)) {
       // If the array is huge, it's not likely to be defined in a local
       // function, so we shouldn't make new instances of it very often.
       uint32_t length = 0;
       CHECK(transition_info->length()->ToArrayIndex(&length));
       if (length <= AllocationSite::kMaximumArrayBytesToPretransition) {
         if (FLAG_trace_track_allocation_sites) {
+          bool is_nested = site->IsNestedSite();
           PrintF(
-              "AllocationSite: JSArray %p boilerplate updated %s->%s\n",
+              "AllocationSite: JSArray %p boilerplate %s updated %s->%s\n",
               reinterpret_cast<void*>(this),
+              is_nested ? "(nested)" : "",
               ElementsKindToString(kind),
               ElementsKindToString(to_kind));
         }
         return transition_info->TransitionElementsKind(to_kind);
       }
     }
   } else {
     ElementsKind kind = site->GetElementsKind();
     // if kind is holey ensure that to_kind is as well.
     if (IsHoleyElementsKind(kind)) {
@@ skipping 382 matching lines @@
 InterceptorInfo* JSObject::GetIndexedInterceptor() {
   ASSERT(map()->has_indexed_interceptor());
   JSFunction* constructor = JSFunction::cast(map()->constructor());
   ASSERT(constructor->shared()->IsApiFunction());
   Object* result =
       constructor->shared()->get_api_func_data()->indexed_property_handler();
   return InterceptorInfo::cast(result);
 }
 
 
-MaybeObject* JSObject::GetPropertyPostInterceptor(
-    Object* receiver,
-    Name* name,
+Handle<Object> JSObject::GetPropertyPostInterceptor(
+    Handle<JSObject> object,
+    Handle<Object> receiver,
+    Handle<Name> name,
     PropertyAttributes* attributes) {
   // Check local property in holder, ignore interceptor.
-  LookupResult result(GetIsolate());
-  LocalLookupRealNamedProperty(name, &result);
-  if (result.IsFound()) {
-    return GetProperty(receiver, &result, name, attributes);
+  Isolate* isolate = object->GetIsolate();
+  LookupResult lookup(isolate);
+  object->LocalLookupRealNamedProperty(*name, &lookup);
+  Handle<Object> result;
+  if (lookup.IsFound()) {
+    result = GetProperty(object, receiver, &lookup, name, attributes);
+  } else {
+    // Continue searching via the prototype chain.
+    Handle<Object> prototype(object->GetPrototype(), isolate);
+    *attributes = ABSENT;
+    if (prototype->IsNull()) return isolate->factory()->undefined_value();
+    result = GetPropertyWithReceiver(prototype, receiver, name, attributes);
   }
-  // Continue searching via the prototype chain.
-  Object* pt = GetPrototype();
-  *attributes = ABSENT;
-  if (pt->IsNull()) return GetHeap()->undefined_value();
-  return pt->GetPropertyWithReceiver(receiver, name, attributes);
+  return result;
 }
 
 
 MaybeObject* JSObject::GetLocalPropertyPostInterceptor(
     Object* receiver,
     Name* name,
     PropertyAttributes* attributes) {
   // Check local property in holder, ignore interceptor.
   LookupResult result(GetIsolate());
   LocalLookupRealNamedProperty(name, &result);
   if (result.IsFound()) {
     return GetProperty(receiver, &result, name, attributes);
   }
   return GetHeap()->undefined_value();
 }
 
 
-MaybeObject* JSObject::GetPropertyWithInterceptor(
-    Object* receiver,
-    Name* name,
+Handle<Object> JSObject::GetPropertyWithInterceptor(
+    Handle<JSObject> object,
+    Handle<Object> receiver,
+    Handle<Name> name,
     PropertyAttributes* attributes) {
+  Isolate* isolate = object->GetIsolate();
+
   // TODO(rossberg): Support symbols in the API.
-  if (name->IsSymbol()) return GetHeap()->undefined_value();
+  if (name->IsSymbol()) return isolate->factory()->undefined_value();
 
-  Isolate* isolate = GetIsolate();
-  InterceptorInfo* interceptor = GetNamedInterceptor();
-  HandleScope scope(isolate);
-  Handle<Object> receiver_handle(receiver, isolate);
-  Handle<JSObject> holder_handle(this);
-  Handle<String> name_handle(String::cast(name));
+  Handle<InterceptorInfo> interceptor(object->GetNamedInterceptor(), isolate);
+  Handle<String> name_string = Handle<String>::cast(name);
 
   if (!interceptor->getter()->IsUndefined()) {
     v8::NamedPropertyGetterCallback getter =
         v8::ToCData<v8::NamedPropertyGetterCallback>(interceptor->getter());
     LOG(isolate,
-        ApiNamedPropertyAccess("interceptor-named-get", *holder_handle, name));
+        ApiNamedPropertyAccess("interceptor-named-get", *object, *name));
     PropertyCallbackArguments
-        args(isolate, interceptor->data(), receiver, this);
+        args(isolate, interceptor->data(), *receiver, *object);
     v8::Handle<v8::Value> result =
-        args.Call(getter, v8::Utils::ToLocal(name_handle));
-    RETURN_IF_SCHEDULED_EXCEPTION(isolate);
+        args.Call(getter, v8::Utils::ToLocal(name_string));
+    RETURN_HANDLE_IF_SCHEDULED_EXCEPTION(isolate, Object);
     if (!result.IsEmpty()) {
       *attributes = NONE;
       Handle<Object> result_internal = v8::Utils::OpenHandle(*result);
       result_internal->VerifyApiCallResultType();
-      return *result_internal;
+      // Rebox handle to escape this scope.
+      return handle(*result_internal, isolate);
     }
   }
 
-  MaybeObject* result = holder_handle->GetPropertyPostInterceptor(
-      *receiver_handle,
-      *name_handle,
-      attributes);
-  RETURN_IF_SCHEDULED_EXCEPTION(isolate);
-  return result;
+  return GetPropertyPostInterceptor(object, receiver, name, attributes);
 }
 
 
-bool JSObject::HasRealNamedProperty(Isolate* isolate, Name* key) {
+bool JSObject::HasRealNamedProperty(Handle<JSObject> object,
+                                    Handle<Name> key) {
+  Isolate* isolate = object->GetIsolate();
+  SealHandleScope shs(isolate);
   // Check access rights if needed.
-  if (IsAccessCheckNeeded()) {
-    if (!isolate->MayNamedAccess(this, key, v8::ACCESS_HAS)) {
-      isolate->ReportFailedAccessCheck(this, v8::ACCESS_HAS);
+  if (object->IsAccessCheckNeeded()) {
+    if (!isolate->MayNamedAccess(*object, *key, v8::ACCESS_HAS)) {
+      isolate->ReportFailedAccessCheck(*object, v8::ACCESS_HAS);
       return false;
     }
   }
 
   LookupResult result(isolate);
-  LocalLookupRealNamedProperty(key, &result);
+  object->LocalLookupRealNamedProperty(*key, &result);
   return result.IsFound() && !result.IsInterceptor();
 }
 
 
-bool JSObject::HasRealElementProperty(Isolate* isolate, uint32_t index) {
+bool JSObject::HasRealElementProperty(Handle<JSObject> object, uint32_t index) {
+  Isolate* isolate = object->GetIsolate();
+  SealHandleScope shs(isolate);
   // Check access rights if needed.
-  if (IsAccessCheckNeeded()) {
-    if (!isolate->MayIndexedAccess(this, index, v8::ACCESS_HAS)) {
-      isolate->ReportFailedAccessCheck(this, v8::ACCESS_HAS);
+  if (object->IsAccessCheckNeeded()) {
+    if (!isolate->MayIndexedAccess(*object, index, v8::ACCESS_HAS)) {
+      isolate->ReportFailedAccessCheck(*object, v8::ACCESS_HAS);
       return false;
     }
   }
 
-  if (IsJSGlobalProxy()) {
-    Object* proto = GetPrototype();
+  if (object->IsJSGlobalProxy()) {
+    HandleScope scope(isolate);
+    Handle<Object> proto(object->GetPrototype(), isolate);
     if (proto->IsNull()) return false;
     ASSERT(proto->IsJSGlobalObject());
-    return JSObject::cast(proto)->HasRealElementProperty(isolate, index);
+    return HasRealElementProperty(Handle<JSObject>::cast(proto), index);
   }
 
-  return GetElementAttributeWithoutInterceptor(this, index, false) != ABSENT;
+  return object->GetElementAttributeWithoutInterceptor(
+             *object, index, false) != ABSENT;
 }
 
 
-bool JSObject::HasRealNamedCallbackProperty(Isolate* isolate, Name* key) {
+bool JSObject::HasRealNamedCallbackProperty(Handle<JSObject> object,
+                                            Handle<Name> key) {
+  Isolate* isolate = object->GetIsolate();
+  SealHandleScope shs(isolate);
   // Check access rights if needed.
-  if (IsAccessCheckNeeded()) {
-    if (!isolate->MayNamedAccess(this, key, v8::ACCESS_HAS)) {
-      isolate->ReportFailedAccessCheck(this, v8::ACCESS_HAS);
+  if (object->IsAccessCheckNeeded()) {
+    if (!isolate->MayNamedAccess(*object, *key, v8::ACCESS_HAS)) {
+      isolate->ReportFailedAccessCheck(*object, v8::ACCESS_HAS);
       return false;
     }
   }
 
   LookupResult result(isolate);
-  LocalLookupRealNamedProperty(key, &result);
+  object->LocalLookupRealNamedProperty(*key, &result);
   return result.IsPropertyCallbacks();
 }
 
 
 int JSObject::NumberOfLocalProperties(PropertyAttributes filter) {
   if (HasFastProperties()) {
     Map* map = this->map();
     if (filter == NONE) return map->NumberOfOwnDescriptors();
     if (filter & DONT_ENUM) {
       int result = map->EnumLength();
@@ skipping 1005 matching lines @@
 template
 int Dictionary<SeededNumberDictionaryShape, uint32_t>::NumberOfEnumElements();
 
 template
 int Dictionary<NameDictionaryShape, Name*>::NumberOfEnumElements();
 
 template
 int HashTable<SeededNumberDictionaryShape, uint32_t>::FindEntry(uint32_t);
 
 
+Handle<Object> JSObject::PrepareSlowElementsForSort(
+    Handle<JSObject> object, uint32_t limit) {
+  CALL_HEAP_FUNCTION(object->GetIsolate(),
+                     object->PrepareSlowElementsForSort(limit),
+                     Object);
+}
+
+
 // Collates undefined and unexisting elements below limit from position
 // zero of the elements. The object stays in Dictionary mode.
 MaybeObject* JSObject::PrepareSlowElementsForSort(uint32_t limit) {
   ASSERT(HasDictionaryElements());
   // Must stay in dictionary mode, either because of requires_slow_elements,
   // or because we are not going to sort (and therefore compact) all of the
   // elements.
   SeededNumberDictionary* dict = element_dictionary();
   HeapNumber* result_double = NULL;
   if (limit > static_cast<uint32_t>(Smi::kMaxValue)) {
@@ skipping 82 matching lines @@
   ASSERT_NE(NULL, result_double);
   result_double->set_value(static_cast<double>(result));
   return result_double;
 }
 
 
 // Collects all defined (non-hole) and non-undefined (array) elements at
 // the start of the elements array.
 // If the object is in dictionary mode, it is converted to fast elements
 // mode.
-MaybeObject* JSObject::PrepareElementsForSort(uint32_t limit) {
-  Heap* heap = GetHeap();
+Handle<Object> JSObject::PrepareElementsForSort(Handle<JSObject> object,
+                                                uint32_t limit) {
+  Isolate* isolate = object->GetIsolate();
 
-  ASSERT(!map()->is_observed());
-  if (HasDictionaryElements()) {
+  ASSERT(!object->map()->is_observed());
+  if (object->HasDictionaryElements()) {
     // Convert to fast elements containing only the existing properties.
     // Ordering is irrelevant, since we are going to sort anyway.
-    SeededNumberDictionary* dict = element_dictionary();
-    if (IsJSArray() || dict->requires_slow_elements() ||
+    Handle<SeededNumberDictionary> dict(object->element_dictionary());
+    if (object->IsJSArray() || dict->requires_slow_elements() ||
         dict->max_number_key() >= limit) {
-      return PrepareSlowElementsForSort(limit);
+      return JSObject::PrepareSlowElementsForSort(object, limit);
     }
     // Convert to fast elements.
 
-    Object* obj;
-    MaybeObject* maybe_obj = GetElementsTransitionMap(GetIsolate(),
-                                                      FAST_HOLEY_ELEMENTS);
-    if (!maybe_obj->ToObject(&obj)) return maybe_obj;
-    Map* new_map = Map::cast(obj);
+    Handle<Map> new_map =
+        JSObject::GetElementsTransitionMap(object, FAST_HOLEY_ELEMENTS);
 
-    PretenureFlag tenure = heap->InNewSpace(this) ? NOT_TENURED: TENURED;
-    Object* new_array;
-    { MaybeObject* maybe_new_array =
-          heap->AllocateFixedArray(dict->NumberOfElements(), tenure);
-      if (!maybe_new_array->ToObject(&new_array)) return maybe_new_array;
-    }
-    FixedArray* fast_elements = FixedArray::cast(new_array);
-    dict->CopyValuesTo(fast_elements);
-    ValidateElements();
+    PretenureFlag tenure = isolate->heap()->InNewSpace(*object) ?
+        NOT_TENURED: TENURED;
+    Handle<FixedArray> fast_elements =
+        isolate->factory()->NewFixedArray(dict->NumberOfElements(), tenure);
+    dict->CopyValuesTo(*fast_elements);
+    object->ValidateElements();
 
-    set_map_and_elements(new_map, fast_elements);
-  } else if (HasExternalArrayElements()) {
+    object->set_map_and_elements(*new_map, *fast_elements);
+  } else if (object->HasExternalArrayElements()) {
     // External arrays cannot have holes or undefined elements.
-    return Smi::FromInt(ExternalArray::cast(elements())->length());
-  } else if (!HasFastDoubleElements()) {
-    Object* obj;
-    { MaybeObject* maybe_obj = EnsureWritableFastElements();
-      if (!maybe_obj->ToObject(&obj)) return maybe_obj;
-    }
+    return handle(Smi::FromInt(
+        ExternalArray::cast(object->elements())->length()), isolate);
+  } else if (!object->HasFastDoubleElements()) {
+    JSObject::EnsureWritableFastElements(object);
   }
-  ASSERT(HasFastSmiOrObjectElements() || HasFastDoubleElements());
+  ASSERT(object->HasFastSmiOrObjectElements() ||
+         object->HasFastDoubleElements());
 
   // Collect holes at the end, undefined before that and the rest at the
   // start, and return the number of non-hole, non-undefined values.
 
-  FixedArrayBase* elements_base = FixedArrayBase::cast(this->elements());
+  Handle<FixedArrayBase> elements_base(object->elements());
   uint32_t elements_length = static_cast<uint32_t>(elements_base->length());
   if (limit > elements_length) {
     limit = elements_length ;
   }
   if (limit == 0) {
-    return Smi::FromInt(0);
-  }
-
-  HeapNumber* result_double = NULL;
-  if (limit > static_cast<uint32_t>(Smi::kMaxValue)) {
-    // Pessimistically allocate space for return value before
-    // we start mutating the array.
-    Object* new_double;
-    { MaybeObject* maybe_new_double = heap->AllocateHeapNumber(0.0);
-      if (!maybe_new_double->ToObject(&new_double)) return maybe_new_double;
-    }
-    result_double = HeapNumber::cast(new_double);
+    return handle(Smi::FromInt(0), isolate);
   }
 
   uint32_t result = 0;
-  if (elements_base->map() == heap->fixed_double_array_map()) {
-    FixedDoubleArray* elements = FixedDoubleArray::cast(elements_base);
+  if (elements_base->map() == isolate->heap()->fixed_double_array_map()) {
+    FixedDoubleArray* elements = FixedDoubleArray::cast(*elements_base);
     // Split elements into defined and the_hole, in that order.
     unsigned int holes = limit;
     // Assume most arrays contain no holes and undefined values, so minimize the
     // number of stores of non-undefined, non-the-hole values.
     for (unsigned int i = 0; i < holes; i++) {
       if (elements->is_the_hole(i)) {
         holes--;
       } else {
         continue;
       }
       // Position i needs to be filled.
       while (holes > i) {
         if (elements->is_the_hole(holes)) {
           holes--;
         } else {
           elements->set(i, elements->get_scalar(holes));
           break;
         }
       }
     }
     result = holes;
     while (holes < limit) {
       elements->set_the_hole(holes);
       holes++;
     }
   } else {
-    FixedArray* elements = FixedArray::cast(elements_base);
+    FixedArray* elements = FixedArray::cast(*elements_base);
     DisallowHeapAllocation no_gc;
 
     // Split elements into defined, undefined and the_hole, in that order.  Only
     // count locations for undefined and the hole, and fill them afterwards.
     WriteBarrierMode write_barrier = elements->GetWriteBarrierMode(no_gc);
     unsigned int undefs = limit;
     unsigned int holes = limit;
     // Assume most arrays contain no holes and undefined values, so minimize the
     // number of stores of non-undefined, non-the-hole values.
     for (unsigned int i = 0; i < undefs; i++) {
@@ skipping 24 matching lines @@
     while (undefs < holes) {
       elements->set_undefined(undefs);
       undefs++;
     }
     while (holes < limit) {
       elements->set_the_hole(holes);
       holes++;
     }
   }
 
-  if (result <= static_cast<uint32_t>(Smi::kMaxValue)) {
-    return Smi::FromInt(static_cast<int>(result));
-  }
-  ASSERT_NE(NULL, result_double);
-  result_double->set_value(static_cast<double>(result));
-  return result_double;
+  return isolate->factory()->NewNumberFromUint(result);
 }
 
 
 ExternalArrayType JSTypedArray::type() {
   switch (elements()->map()->instance_type()) {
     case EXTERNAL_BYTE_ARRAY_TYPE:
       return kExternalByteArray;
     case EXTERNAL_UNSIGNED_BYTE_ARRAY_TYPE:
       return kExternalUnsignedByteArray;
     case EXTERNAL_SHORT_ARRAY_TYPE:
@@ skipping 1785 matching lines @@
   return static_cast<Type*>(type_raw());
 }
 
 
 void PropertyCell::set_type(Type* type, WriteBarrierMode ignored) {
   ASSERT(IsPropertyCell());
   set_type_raw(type, ignored);
 }
 
 
-Type* PropertyCell::UpdateType(Handle<PropertyCell> cell,
-                               Handle<Object> value) {
+Handle<Type> PropertyCell::UpdatedType(Handle<PropertyCell> cell,
+                                       Handle<Object> value) {
   Isolate* isolate = cell->GetIsolate();
   Handle<Type> old_type(cell->type(), isolate);
   // TODO(2803): Do not track ConsString as constant because they cannot be
   // embedded into code.
   Handle<Type> new_type(value->IsConsString() || value->IsTheHole()
                         ? Type::Any()
                         : Type::Constant(value, isolate), isolate);
 
   if (new_type->Is(old_type)) {
-    return *old_type;
+    return old_type;
   }
 
   cell->dependent_code()->DeoptimizeDependentCodeGroup(
       isolate, DependentCode::kPropertyCellChangedGroup);
 
   if (old_type->Is(Type::None()) || old_type->Is(Type::Undefined())) {
-    return *new_type;
+    return new_type;
   }
 
-  return Type::Any();
+  return handle(Type::Any(), isolate);
 }
 
 
 void PropertyCell::SetValueInferType(Handle<PropertyCell> cell,
-                                     Handle<Object> value,
-                                     WriteBarrierMode mode) {
-  CALL_HEAP_FUNCTION_VOID(cell->GetIsolate(),
-                          cell->SetValueInferType(*value, mode));
+                                     Handle<Object> value) {
+  cell->set_value(*value);
+  if (!Type::Any()->Is(cell->type())) {
+    Handle<Type> new_type = UpdatedType(cell, value);
+    cell->set_type(*new_type);
+  }
 }
 
 
-MaybeObject* PropertyCell::SetValueInferType(Object* value,
-                                             WriteBarrierMode ignored) {
-  set_value(value, ignored);
-  if (!Type::Any()->Is(type())) {
-    IdempotentPointerToHandleCodeTrampoline trampoline(GetIsolate());
-    MaybeObject* maybe_type = trampoline.CallWithReturnValue(
-        &PropertyCell::UpdateType,
-        Handle<PropertyCell>(this),
-        Handle<Object>(value, GetIsolate()));
-    Type* new_type = NULL;
-    if (!maybe_type->To(&new_type)) return maybe_type;
-    set_type(new_type);
-  }
-  return value;
-}
-
-
 void PropertyCell::AddDependentCompilationInfo(CompilationInfo* info) {
   Handle<DependentCode> dep(dependent_code());
   Handle<DependentCode> codes =
       DependentCode::Insert(dep, DependentCode::kPropertyCellChangedGroup,
                             info->object_wrapper());
   if (*codes != dependent_code()) set_dependent_code(*codes);
   info->dependencies(DependentCode::kPropertyCellChangedGroup)->Add(
       Handle<HeapObject>(this), info->zone());
 }
 
@@ skipping 11 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