Always generalize all representations when no transition is inserted.

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 6165 matching lines @@
     SimpleTransitionFlag simple_flag =
         (descriptor_index == descriptors->number_of_descriptors() - 1)
          ? SIMPLE_TRANSITION
          : FULL_TRANSITION;
     ASSERT(name == descriptors->GetKey(descriptor_index));
     MaybeObject* maybe_transitions = AddTransition(name, result, simple_flag);
     if (!maybe_transitions->To(&transitions)) return maybe_transitions;
 
     set_transitions(transitions);
     result->SetBackPointer(this);
+  } else {
+    descriptors->InitializeRepresentations(Representation::Tagged());
   }
 
   return result;
 }
 
 
 MaybeObject* Map::CopyInstallDescriptors(int new_descriptor,
                                          DescriptorArray* descriptors) {
   ASSERT(descriptors->IsSortedNoDuplicates());
 
@@ skipping 17 matching lines @@
 
   if (CanHaveMoreTransitions()) {
     Name* name = descriptors->GetKey(new_descriptor);
     TransitionArray* transitions;
     MaybeObject* maybe_transitions =
         AddTransition(name, result, SIMPLE_TRANSITION);
     if (!maybe_transitions->To(&transitions)) return maybe_transitions;
 
     set_transitions(transitions);
     result->SetBackPointer(this);
+  } else {
+    descriptors->InitializeRepresentations(Representation::Tagged());
   }
 
   return result;
 }
 
 
 MaybeObject* Map::CopyAsElementsKind(ElementsKind kind, TransitionFlag flag) {
   if (flag == INSERT_TRANSITION) {
     ASSERT(!HasElementsTransition() ||
         ((elements_transition_map()->elements_kind() == DICTIONARY_ELEMENTS ||
@@ skipping 54 matching lines @@
   JSFunction* ctor = JSFunction::cast(constructor());
   Map* map = ctor->initial_map();
   DescriptorArray* descriptors = map->instance_descriptors();
 
   int number_of_own_descriptors = map->NumberOfOwnDescriptors();
   DescriptorArray* new_descriptors;
   MaybeObject* maybe_descriptors =
       descriptors->CopyUpTo(number_of_own_descriptors);
   if (!maybe_descriptors->To(&new_descriptors)) return maybe_descriptors;
 
-  new_descriptors->InitializeRepresentations(Representation::Tagged());
-
   return CopyReplaceDescriptors(new_descriptors, NULL, OMIT_TRANSITION, 0);
 }
 
 
 MaybeObject* Map::Copy() {
   DescriptorArray* descriptors = instance_descriptors();
   DescriptorArray* new_descriptors;
   int number_of_own_descriptors = NumberOfOwnDescriptors();
   MaybeObject* maybe_descriptors =
       descriptors->CopyUpTo(number_of_own_descriptors);
@@ skipping 8826 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