- Trigger old-gen GCs when needed.

vm/gc_sweeper.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/gc_sweeper.h"
 
 #include "vm/freelist.h"
 #include "vm/globals.h"
 #include "vm/pages.h"
 
@@ skipping 42 matching lines @@
       }
     }
     current += obj_size;
   }
 
   return in_use_swept;
 }
 
 
 intptr_t GCSweeper::SweepLargePage(HeapPage* page) {
-  UNIMPLEMENTED();
-  return 0;
+  RawObject* raw_obj = RawObject::FromAddr(page->first_object_start());
+  if (!raw_obj->IsMarked()) {
+    // The large object was not marked. Used size is zero, which also tells the
+    // calling code that the large object page can be recycled.
+    return 0;
+  }
+  raw_obj->ClearMarkBit();
+  return raw_obj->Size();
 }
 
 }  // namespace dart