Get rid of ConvertFieldToDescriptor.

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 959e3d38648277f47e94c492297adc411f6fe800..d8a05eb01c528f81c29d87cb8e83482d1450b986 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -1927,7 +1927,8 @@ MaybeObject* JSObject::AddFastProperty(Name* name,
                                        Object* value,
                                        PropertyAttributes attributes,
                                        StoreFromKeyed store_mode,
-                                       ValueType value_type) {
+                                       ValueType value_type,
+                                       TransitionFlag flag) {
   ASSERT(!IsJSGlobalProxy());
   ASSERT(DescriptorArray::kNotFound ==
          map()->instance_descriptors()->Search(
@@ -1937,15 +1938,13 @@ MaybeObject* JSObject::AddFastProperty(Name* name,
   // hidden strings) and is not a real identifier.
   // Normalize the object if it will have too many fast properties.
   Isolate* isolate = GetHeap()->isolate();
-  if ((!name->IsSymbol() && !IsIdentifier(isolate->unicode_cache(), name)
-       && name != isolate->heap()->hidden_string()) ||
-      (map()->unused_property_fields() == 0 &&
-       TooManyFastProperties(properties()->length(), store_mode))) {
-    Object* obj;
-    MaybeObject* maybe_obj =
+  if ((!name->IsSymbol() &&
+       !IsIdentifier(isolate->unicode_cache(), name) &&
+       name != isolate->heap()->hidden_string()) ||
+      TooManyFastProperties(store_mode)) {
+    MaybeObject* maybe_failure =
         NormalizeProperties(CLEAR_INOBJECT_PROPERTIES, 0);
-    if (!maybe_obj->ToObject(&obj)) return maybe_obj;
-
+    if (maybe_failure->IsFailure()) return maybe_failure;
     return AddSlowProperty(name, value, attributes);
   }
 
@@ -1972,8 +1971,6 @@ MaybeObject* JSObject::AddFastProperty(Name* name,
     if (!maybe_values->To(&values)) return maybe_values;
   }
 
-  TransitionFlag flag = INSERT_TRANSITION;
-
   Heap* heap = isolate->heap();
 
   Object* storage;
@@ -2006,7 +2003,8 @@ MaybeObject* JSObject::AddFastProperty(Name* name,
 MaybeObject* JSObject::AddConstantProperty(
     Name* name,
     Object* constant,
-    PropertyAttributes attributes) {
+    PropertyAttributes attributes,
+    TransitionFlag initial_flag) {
   // Allocate new instance descriptors with (name, constant) added
   ConstantDescriptor d(name, constant, attributes);
 
@@ -2017,7 +2015,7 @@ MaybeObject* JSObject::AddConstantProperty(
       // attributes.
        attributes != NONE)
       ? OMIT_TRANSITION
-      : INSERT_TRANSITION;
+      : initial_flag;
 
   Map* new_map;
   MaybeObject* maybe_new_map = map()->CopyAddDescriptor(&d, flag);
@@ -2077,7 +2075,8 @@ MaybeObject* JSObject::AddProperty(Name* name,
                                    JSReceiver::StoreFromKeyed store_mode,
                                    ExtensibilityCheck extensibility_check,
                                    ValueType value_type,
-                                   StoreMode mode) {
+                                   StoreMode mode,
+                                   TransitionFlag transition_flag) {
   ASSERT(!IsJSGlobalProxy());
   Map* map_of_this = map();
   Heap* heap = GetHeap();
@@ -2104,10 +2103,10 @@ MaybeObject* JSObject::AddProperty(Name* name,
       //     !value->IsTheHole() &&
       //     !value->IsConsString()) {
       if (value->IsJSFunction()) {
-        result = AddConstantProperty(name, value, attributes);
+        result = AddConstantProperty(name, value, attributes, transition_flag);
       } else {
         result = AddFastProperty(
-            name, value, attributes, store_mode, value_type);
+            name, value, attributes, store_mode, value_type, transition_flag);
       }
     } else {
       // Normalize the object to prevent very large instance descriptors.
@@ -2211,56 +2210,6 @@ MaybeObject* JSObject::ReplaceSlowProperty(Name* name,
 }
 
 
-MaybeObject* JSObject::ConvertDescriptorToField(Name* name,
-                                                Object* new_value,
-                                                PropertyAttributes attributes,
-                                                TransitionFlag flag) {
-  if (map()->unused_property_fields() == 0 &&
-      TooManyFastProperties(properties()->length(), MAY_BE_STORE_FROM_KEYED)) {
-    Object* obj;
-    MaybeObject* maybe_obj = NormalizeProperties(CLEAR_INOBJECT_PROPERTIES, 0);
-    if (!maybe_obj->ToObject(&obj)) return maybe_obj;
-    return ReplaceSlowProperty(name, new_value, attributes);
-  }
-
-  Representation representation = IsJSContextExtensionObject()
-      ? Representation::Tagged() : new_value->OptimalRepresentation();
-  int index = map()->NextFreePropertyIndex();
-  FieldDescriptor new_field(name, index, attributes, representation);
-
-  // Make a new map for the object.
-  Map* new_map;
-  MaybeObject* maybe_new_map = map()->CopyInsertDescriptor(&new_field, flag);
-  if (!maybe_new_map->To(&new_map)) return maybe_new_map;
-
-  // Make new properties array if necessary.
-  FixedArray* new_properties = NULL;
-  int new_unused_property_fields = map()->unused_property_fields() - 1;
-  if (map()->unused_property_fields() == 0) {
-    new_unused_property_fields = kFieldsAdded - 1;
-    MaybeObject* maybe_new_properties =
-        properties()->CopySize(properties()->length() + kFieldsAdded);
-    if (!maybe_new_properties->To(&new_properties)) return maybe_new_properties;
-  }
-
-  Heap* heap = GetHeap();
-  Object* storage;
-  MaybeObject* maybe_storage =
-      new_value->AllocateNewStorageFor(heap, representation);
-  if (!maybe_storage->To(&storage)) return maybe_storage;
-
-  // Update pointers to commit changes.
-  // Object points to the new map.
-  new_map->set_unused_property_fields(new_unused_property_fields);
-  set_map(new_map);
-  if (new_properties != NULL) {
-    set_properties(new_properties);
-  }
-  FastPropertyAtPut(index, storage);
-  return new_value;
-}
-
-
 const char* Representation::Mnemonic() const {
   switch (kind_) {
     case kNone: return "v";
@@ -2407,6 +2356,10 @@ MaybeObject* JSObject::MigrateToMap(Map* new_map) {
     PropertyDetails details = new_descriptors->GetDetails(i);
     if (details.type() != FIELD) continue;
     PropertyDetails old_details = old_descriptors->GetDetails(i);
+    if (old_details.type() == CALLBACKS) {
+      ASSERT(details.representation().IsTagged());
+      continue;
+    }
     ASSERT(old_details.type() == CONSTANT ||
            old_details.type() == FIELD);
     Object* value = old_details.type() == CONSTANT
@@ -2488,6 +2441,7 @@ int Map::NumberOfFields() {
 MaybeObject* Map::CopyGeneralizeAllRepresentations(
     int modify_index,
     StoreMode store_mode,
+    PropertyAttributes attributes,
     const char* reason) {
   Map* new_map;
   MaybeObject* maybe_map = this->Copy();
@@ -2501,7 +2455,7 @@ MaybeObject* Map::CopyGeneralizeAllRepresentations(
   if (store_mode == FORCE_FIELD && details.type() != FIELD) {
     FieldDescriptor d(descriptors->GetKey(modify_index),
                       new_map->NumberOfFields(),
-                      details.attributes(),
+                      attributes,
                       Representation::Tagged());
     d.SetSortedKeyIndex(details.pointer());
     descriptors->Set(modify_index, &d);
@@ -2666,8 +2620,8 @@ MaybeObject* Map::GeneralizeRepresentation(int modify_index,
                                            StoreMode store_mode) {
   Map* old_map = this;
   DescriptorArray* old_descriptors = old_map->instance_descriptors();
-  Representation old_representation =
-      old_descriptors->GetDetails(modify_index).representation();
+  PropertyDetails old_details = old_descriptors->GetDetails(modify_index);
+  Representation old_representation = old_details.representation();
 
   // It's fine to transition from None to anything but double without any
   // modification to the object, because the default uninitialized value for
@@ -2686,21 +2640,22 @@ MaybeObject* Map::GeneralizeRepresentation(int modify_index,
   // Check the state of the root map.
   if (!old_map->EquivalentToForTransition(root_map)) {
     return CopyGeneralizeAllRepresentations(
-        modify_index, store_mode, "not equivalent");
+        modify_index, store_mode, old_details.attributes(), "not equivalent");
   }
 
   int verbatim = root_map->NumberOfOwnDescriptors();
 
   if (store_mode != ALLOW_AS_CONSTANT && modify_index < verbatim) {
     return CopyGeneralizeAllRepresentations(
-        modify_index, store_mode, "root modification");
+        modify_index, store_mode,
+        old_details.attributes(), "root modification");
   }
 
   Map* updated = root_map->FindUpdatedMap(
       verbatim, descriptors, old_descriptors);
   if (updated == NULL) {
     return CopyGeneralizeAllRepresentations(
-        modify_index, store_mode, "incompatible");
+        modify_index, store_mode, old_details.attributes(), "incompatible");
   }
 
   DescriptorArray* updated_descriptors = updated->instance_descriptors();
@@ -3816,8 +3771,14 @@ static MaybeObject* SetPropertyUsingTransition(LookupResult* lookup,
   PropertyDetails details = descriptors->GetDetails(descriptor);
 
   if (details.type() == CALLBACKS || attributes != details.attributes()) {
-    return lookup->holder()->ConvertDescriptorToField(
-        *name, *value, attributes);
+    // AddProperty will either normalize the object, or create a new fast copy
+    // of the map. If we get a fast copy of the map, all field representations
+    // will be tagged since the transition is omitted.
+    return lookup->holder()->AddProperty(
+        *name, *value, attributes, kNonStrictMode,
+        JSReceiver::CERTAINLY_NOT_STORE_FROM_KEYED,
+        JSReceiver::OMIT_EXTENSIBILITY_CHECK,
+        JSObject::FORCE_TAGGED, FORCE_FIELD, OMIT_TRANSITION);
   }
 
   // Keep the target CONSTANT if the same value is stored.
@@ -3882,6 +3843,56 @@ static MaybeObject* SetPropertyToField(LookupResult* lookup,
 }
 
 
+static MaybeObject* ConvertAndSetLocalProperty(LookupResult* lookup,
+                                               Name* name,
+                                               Object* value,
+                                               PropertyAttributes attributes) {
+  JSObject* object = lookup->holder();
+  if (object->TooManyFastProperties()) {
+    MaybeObject* maybe_failure = object->NormalizeProperties(
+        CLEAR_INOBJECT_PROPERTIES, 0);
+    if (maybe_failure->IsFailure()) return maybe_failure;
+  }
+
+  if (!object->HasFastProperties()) {
+    return object->ReplaceSlowProperty(name, value, attributes);
+  }
+
+  int descriptor_index = lookup->GetDescriptorIndex();
+  if (lookup->GetAttributes() == attributes) {
+    MaybeObject* maybe_failure = object->GeneralizeFieldRepresentation(
+        descriptor_index, Representation::Tagged(), FORCE_FIELD);
+    if (maybe_failure->IsFailure()) return maybe_failure;
+  } else {
+    Map* map;
+    MaybeObject* maybe_map = object->map()->CopyGeneralizeAllRepresentations(
+        descriptor_index, FORCE_FIELD, attributes, "attributes mismatch");
+    if (!maybe_map->To(&map)) return maybe_map;
+    MaybeObject* maybe_failure = object->MigrateToMap(map);
+    if (maybe_failure->IsFailure()) return maybe_failure;
+  }
+
+  DescriptorArray* descriptors = object->map()->instance_descriptors();
+  int index = descriptors->GetDetails(descriptor_index).field_index();
+  object->FastPropertyAtPut(index, value);
+  return value;
+}
+
+
+static MaybeObject* SetPropertyToFieldWithAttributes(
+    LookupResult* lookup,
+    Handle<Name> name,
+    Handle<Object> value,
+    PropertyAttributes attributes) {
+  if (lookup->GetAttributes() == attributes) {
+    if (value->IsUninitialized()) return *value;
+    return SetPropertyToField(lookup, name, value);
+  } else {
+    return ConvertAndSetLocalProperty(lookup, *name, *value, attributes);
+  }
+}
+
+
 MaybeObject* JSObject::SetPropertyForResult(LookupResult* lookup,
                                             Name* name_raw,
                                             Object* value_raw,
@@ -4105,25 +4116,41 @@ MaybeObject* JSObject::SetLocalPropertyIgnoreAttributes(
   // Check of IsReadOnly removed from here in clone.
   MaybeObject* result = *value;
   switch (lookup.type()) {
-    case NORMAL: {
-      PropertyDetails details = PropertyDetails(attributes, NORMAL, 0);
-      result = self->SetNormalizedProperty(*name, *value, details);
+    case NORMAL:
+      result = self->ReplaceSlowProperty(*name, *value, attributes);
       break;
-    }
     case FIELD:
-      if (value->IsUninitialized()) break;
-      result = SetPropertyToField(&lookup, name, value);
+      result = SetPropertyToFieldWithAttributes(
+          &lookup, name, value, attributes);
       break;
     case CONSTANT:
       // Only replace the constant if necessary.
-      if (*value == lookup.GetConstant()) return *value;
-      if (value->IsUninitialized()) break;
-      result = SetPropertyToField(&lookup, name, value);
+      if (lookup.GetAttributes() != attributes ||
+          *value != lookup.GetConstant()) {
+        result = SetPropertyToFieldWithAttributes(
+            &lookup, name, value, attributes);
+      }
       break;
     case CALLBACKS:
+      // Callbacks are not guaranteed to be installed on the receiver. Also
+      // perform a local lookup again. Fall through.
     case INTERCEPTOR:
-      // Override callback in clone
-      result = self->ConvertDescriptorToField(*name, *value, attributes);
+      self->LocalLookupRealNamedProperty(*name, &lookup);
+      if (lookup.IsFound()) {
+        if (lookup.IsPropertyCallbacks()) {
+          result = ConvertAndSetLocalProperty(
+              &lookup, *name, *value, attributes);
+        } else if (lookup.IsNormal()) {
+          result = self->ReplaceSlowProperty(*name, *value, attributes);
+        } else {
+          result = SetPropertyToFieldWithAttributes(
+              &lookup, name, value, attributes);
+        }
+      } else {
+        result = self->AddProperty(
+            *name, *value, attributes, kNonStrictMode, MAY_BE_STORE_FROM_KEYED,
+            extensibility_check, value_type, mode);
+      }
       break;
     case TRANSITION:
       result = SetPropertyUsingTransition(&lookup, name, value, attributes);