Improve generalization / migration tracing.

src/objects.h

 // 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 2654 matching lines @@
   inline void PrintTransitions() {
     PrintTransitions(stdout);
   }
   void PrintTransitions(FILE* out);
 #endif
 
   void PrintElementsTransition(
       FILE* file, ElementsKind from_kind, FixedArrayBase* from_elements,
       ElementsKind to_kind, FixedArrayBase* to_elements);
 
+  void PrintInstanceMigration(FILE* file, Map* original_map, Map* new_map);
+
 #ifdef DEBUG
   // Structure for collecting spill information about JSObjects.
   class SpillInformation {
    public:
     void Clear();
     void Print();
     int number_of_objects_;
     int number_of_objects_with_fast_properties_;
     int number_of_objects_with_fast_elements_;
     int number_of_fast_used_fields_;
@@ skipping 2931 matching lines @@
                               int target_unused);
   static Handle<Map> GeneralizeRepresentation(
       Handle<Map> map,
       int modify_index,
       Representation new_representation);
   MUST_USE_RESULT MaybeObject* GeneralizeRepresentation(
       int modify_index,
       Representation representation);
   MUST_USE_RESULT MaybeObject* CopyGeneralizeAllRepresentations();
 
+  void PrintGeneralization(FILE* file,
+                           int modify_index,
+                           int split,
+                           int descriptors,
+                           Representation old_representation,
+                           Representation new_representation);
+
+  // Returns the constructor name (the name (possibly, inferred name) of the
+  // function that was used to instantiate the object).
+  String* constructor_name();
+
   // Tells whether the map is attached to SharedFunctionInfo
   // (for inobject slack tracking).
   inline void set_attached_to_shared_function_info(bool value);
 
   inline bool attached_to_shared_function_info();
 
   // Tells whether the map is shared between objects that may have different
   // behavior. If true, the map should never be modified, instead a clone
   // should be created and modified.
   inline void set_is_shared(bool value);
@@ skipping 4535 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_