Refactor part of handles.cc

src/runtime.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 2942 matching lines @@
         source_shared, Handle<Code>(source_shared->code()));
   }
 
   return *target;
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_SetExpectedNumberOfProperties) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 2);
-  CONVERT_ARG_HANDLE_CHECKED(JSFunction, function, 0);
+  CONVERT_ARG_HANDLE_CHECKED(JSFunction, func, 0);
   CONVERT_SMI_ARG_CHECKED(num, 1);
   RUNTIME_ASSERT(num >= 0);
-  SetExpectedNofProperties(function, num);
+  // If objects constructed from this function exist then changing
+  // 'estimated_nof_properties' is dangerous since the previous value might
+  // have been compiled into the fast construct stub. More over, the inobject

[rossberg, 2013/10/16 09:50:22]

Nit: Moreover

+  // slack tracking logic might have adjusted the previous value, so even
+  // passing the same value is risky.
+  if (!func->shared()->live_objects_may_exist()) {
+    func->shared()->set_expected_nof_properties(num);
+    if (func->has_initial_map()) {
+      Handle<Map> new_initial_map =
+          func->GetIsolate()->factory()->CopyMap(
+              Handle<Map>(func->initial_map()));
+      new_initial_map->set_unused_property_fields(num);
+      func->set_initial_map(*new_initial_map);
+    }
+  }
   return isolate->heap()->undefined_value();
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_CreateJSGeneratorObject) {
   SealHandleScope shs(isolate);
   ASSERT(args.length() == 0);
 
   JavaScriptFrameIterator it(isolate);
   JavaScriptFrame* frame = it.frame();
@@ skipping 11857 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal