Renamed ConvertDescriptorToFieldAndMapTransition to ConvertTransitionToMapTransition, and let it re…

src/objects.cc

 // Copyright 2012 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 1761 matching lines @@
   if (old_index != -1) {
     // All calls to ReplaceSlowProperty have had all transitions removed.
     new_enumeration_index = dictionary->DetailsAt(old_index).index();
   }
 
   PropertyDetails new_details(attributes, NORMAL, new_enumeration_index);
   return SetNormalizedProperty(name, value, new_details);
 }
 
 
-MaybeObject* JSObject::ConvertDescriptorToFieldAndMapTransition(
+MaybeObject* JSObject::ConvertTransitionToMapTransition(
+    int transition_index,
     String* name,
     Object* new_value,
     PropertyAttributes attributes) {
   Map* old_map = map();
-  FixedArray* old_properties = properties();
   Object* result;
 
   MaybeObject* maybe_result =
       ConvertDescriptorToField(name, new_value, attributes);
   if (!maybe_result->To(&result)) return maybe_result;
 
   if (!HasFastProperties()) return result;
 
   // This method should only be used to convert existing transitions. Objects
   // with the map of "new Object()" cannot have transitions in the first place.
   ASSERT(map() != GetIsolate()->empty_object_map());
 
-  TransitionArray* new_transitions;
-  MaybeObject* maybe_new_transitions = old_map->AddTransition(name, map());
-  if (!maybe_new_transitions->To(&new_transitions)) {
-    // Undo changes and return failure.
-    set_map(old_map);
-    set_properties(old_properties);
-    return maybe_new_transitions;
-  }
-
-  MaybeObject* transition_added = old_map->set_transitions(new_transitions);
-  if (transition_added->IsFailure()) {
-    // Undo changes and return failure.
-    set_map(old_map);
-    set_properties(old_properties);
-    return transition_added;
-  }
-
+  // TODO(verwaest): From here on we lose existing map transitions, causing
+  // invalid back pointers. This will change once we can store multiple
+  // transitions with the same key.
+  old_map->SetTransition(transition_index, map());
   map()->SetBackPointer(old_map);
   return result;
 }
 
 
 MaybeObject* JSObject::ConvertDescriptorToField(String* name,
                                                 Object* new_value,
                                                 PropertyAttributes attributes) {
   if (map()->unused_property_fields() == 0 &&
       TooManyFastProperties(properties()->length(), MAY_BE_STORE_FROM_KEYED)) {
@@ skipping 1080 matching lines @@
       // Is transition to CONSTANT_FUNCTION.
       Object* constant_function = descriptors->GetValue(descriptor);
       // If the same constant function is being added we can simply
       // transition to the target map.
       if (constant_function == *value) {
         self->set_map(transition_map);
         return constant_function;
       }
       // Otherwise, replace with a map transition to a new map with a FIELD,
       // even if the value is a constant function.
-      return self->ConvertDescriptorToFieldAndMapTransition(*name,
-                                                            *value,
-                                                            attributes);
+      return ConvertTransitionToMapTransition(
+          result->GetTransitionIndex(), *name, *value, attributes);
     }
     case HANDLER:
     case NONEXISTENT:
       UNREACHABLE();
       return *value;
   }
   UNREACHABLE();  // keep the compiler happy
   return *value;
 }
 
@@ skipping 93 matching lines @@
           return AddFastPropertyUsingMap(transition_map,
                                          name,
                                          value,
                                          field_index);
         }
         return ConvertDescriptorToField(name, value, attributes);
       }
 
       // Was transition to CONSTANT_FUNCTION. Replace with a map transition to a
       // new map with a FIELD, even if the value is a function.
-      return ConvertDescriptorToFieldAndMapTransition(name, value, attributes);
+      return ConvertTransitionToMapTransition(
+          result.GetTransitionIndex(), name, value, attributes);
     }
     case HANDLER:
     case NONEXISTENT:
       UNREACHABLE();
   }
   UNREACHABLE();  // keep the compiler happy
   return value;
 }
 
 
@@ skipping 10223 matching lines @@
   set_year(Smi::FromInt(year), SKIP_WRITE_BARRIER);
   set_month(Smi::FromInt(month), SKIP_WRITE_BARRIER);
   set_day(Smi::FromInt(day), SKIP_WRITE_BARRIER);
   set_weekday(Smi::FromInt(weekday), SKIP_WRITE_BARRIER);
   set_hour(Smi::FromInt(hour), SKIP_WRITE_BARRIER);
   set_min(Smi::FromInt(min), SKIP_WRITE_BARRIER);
   set_sec(Smi::FromInt(sec), SKIP_WRITE_BARRIER);
 }
 
 } }  // namespace v8::internal