- Promote objects from new gen to old space if they survived a scavenge.

vm/object.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/object.h"
 
 #include "vm/assembler.h"
 #include "vm/assert.h"
 #include "vm/bigint_operations.h"
 #include "vm/bootstrap.h"
@@ skipping 204 matching lines @@
   }
 
   Heap* heap = Isolate::Current()->heap();
   // Allocate and initialize the null instance, except its class_ field.
   // 'null_' must be the first object allocated as it is used in allocation to
   // clear the object.
   {
     uword address = heap->Allocate(Instance::InstanceSize(), Heap::kOld);
     null_ = reinterpret_cast<RawInstance*>(address + kHeapObjectTag);
     InitializeObject(address, Instance::InstanceSize());  // Using 'null_'.
+    null_->ptr()->tags_ = 0;
   }
 
   // Initialize object_store empty array to null_ in order to be able to check
   // if the empty array was allocated (RAW_NULL is not available).
   Isolate::Current()->object_store()->set_empty_array(Array::Handle());
 
   Class& cls = Class::Handle();
 
   // Allocate and initialize the class class.
   // At this point, class_class_ is still RAW_NULL, i.e. different from 'null_',
@@ skipping 7255 matching lines @@
   const String& str = String::Handle(pattern());
   const char* format = "JSRegExp: pattern=%s flags=%s";
   intptr_t len = OS::SNPrint(NULL, 0, format, str.ToCString(), Flags());
   char* chars = reinterpret_cast<char*>(
       Isolate::Current()->current_zone()->Allocate(len + 1));
   OS::SNPrint(chars, (len + 1), format, str.ToCString(), Flags());
   return chars;
 }
 
 }  // namespace dart