[runtime] Mark maps created as a result of field representation generalization as transition targets

src/objects.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <memory>
 #include <sstream>
@@ skipping 9141 matching lines @@
                                      Handle<Object> value) {
   if (CanHoldValue(map->instance_descriptors(), descriptor, *value)) return map;
 
   Isolate* isolate = map->GetIsolate();
   PropertyAttributes attributes =
       map->instance_descriptors()->GetDetails(descriptor).attributes();
   Representation representation = value->OptimalRepresentation();
   Handle<FieldType> type = value->OptimalType(isolate, representation);
 
   MapUpdater mu(isolate, map);
-  return mu.ReconfigureToDataField(descriptor, attributes, representation,
-                                   type);
+  Handle<Map> new_map =
+      mu.ReconfigureToDataField(descriptor, attributes, representation, type);
+  new_map->set_migration_target(true);
+  return new_map;
 }
 
 }  // namespace
 
 // static
 Handle<Map> Map::PrepareForDataProperty(Handle<Map> map, int descriptor,
                                         Handle<Object> value) {
   // Dictionaries can store any property value.
   DCHECK(!map->is_dictionary_map());
   // Update to the newest map before storing the property.
@@ skipping 10719 matching lines @@
       // depend on this.
       return DICTIONARY_ELEMENTS;
     }
     DCHECK_LE(kind, LAST_ELEMENTS_KIND);
     return kind;
   }
 }
 
 }  // namespace internal
 }  // namespace v8