Updated the check for unmodfied objects to handle Smi Objects.

src/heap/heap.cc

 // Copyright 2012 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/heap/heap.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/ast/scopeinfo.h"
 #include "src/base/bits.h"
@@ skipping 1475 matching lines @@
 
 
 static bool IsUnscavengedHeapObject(Heap* heap, Object** p) {
   return heap->InNewSpace(*p) &&
          !HeapObject::cast(*p)->map_word().IsForwardingAddress();
 }
 
 
 static bool IsUnmodifiedHeapObject(Object** p) {
   Object* object = *p;
+  if (object->IsSmi()) return true;

[mythria, 2015/12/02 09:45:49]

I thought we can collect all Smi objects. If you think it is more expensive to
collect them and recreate them when necessary, I will just return false. In that
case they will not be collected by minor GC.

[mythria, 2015/12/02 09:45:49]

I am a little surprised that we have Smi objects that are marked weak in new
space nodes. Is it expected? This is the code which generates a Weak Smi object:

Promise.reject(42); from the test
inspector/console/console-uncaught-promise.html in LayoutTests

[jochen (gone - plz use gerrit), 2015/12/02 09:48:28]

actually, I think we should return false for all objects that weren't created
via the C++ API.

While it's possible to recreate e.g. 42, blink has no way of knowing that it
should recreate 42

[mythria, 2015/12/02 12:32:38]

Done.

   DCHECK(object->IsHeapObject());

[mythria, 2015/12/02 09:45:49]

I think we could remove this DCHECK right? or is it safer to have it?

[jochen (gone - plz use gerrit), 2015/12/02 09:48:28]

you can remove it

[mythria, 2015/12/02 12:32:38]

Done.

   HeapObject* heap_object = HeapObject::cast(object);
   if (!object->IsJSObject()) return false;
   Object* obj_constructor = (JSObject::cast(object))->map()->GetConstructor();
   if (!obj_constructor->IsJSFunction()) return false;
   JSFunction* constructor = JSFunction::cast(obj_constructor);
   if (constructor != nullptr &&
       constructor->initial_map() == heap_object->map()) {
     return true;
   }
   return false;
@@ skipping 4592 matching lines @@
 }
 
 
 // static
 int Heap::GetStaticVisitorIdForMap(Map* map) {
   return StaticVisitorBase::GetVisitorId(map);
 }
 
 }  // namespace internal
 }  // namespace v8