- Stop-the-world sweep uses pre-locked free list access.

runtime/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/heap.h"
 #include "vm/pages.h"
@@ skipping 27 matching lines @@
         }
         // Expand the free block by the size of this object.
         free_end += next_obj->Size();
       }
       obj_size = free_end - current;
       if (is_executable) {
         memset(reinterpret_cast<void*>(current), 0xcc, obj_size);
       }
       if ((current != start) || (free_end != end)) {
         // Only add to the free list if not covering the whole page.
-        freelist->Free(current, obj_size);
+        freelist->FreeLocked(current, obj_size);

[koda, 2014/08/20 13:52:22]

SweepPage now assumes that 'freelist' is locked, so you should document this
precondition in the method's specification.

[Ivan Posva, 2014/08/20 14:10:20]

Done.

       }
     }
     current += obj_size;
   }
   ASSERT(current == end);
 
   return in_use;
 }
 
 
@@ skipping 12 matching lines @@
   while (current < end) {
     RawObject* cur_obj = RawObject::FromAddr(current);
     ASSERT(!cur_obj->IsMarked());
     current += cur_obj->Size();
   }
 #endif  // DEBUG
   return words_to_end;
 }
 
 }  // namespace dart