[heap] Concurrently free empty slot set buckets.

src/heap/mark-compact.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/mark-compact.h"
 
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/base/sys-info.h"
 #include "src/code-stubs.h"
@@ skipping 3812 matching lines @@
     } else if (identity == CODE_SPACE) {
       max_freed = RawSweep(page, REBUILD_FREE_LIST, free_space_mode);
     } else {
       max_freed = RawSweep(page, REBUILD_FREE_LIST, free_space_mode);
     }
 
     // After finishing sweeping of a page we clean up its remembered set.
     if (page->typed_old_to_new_slots()) {
       page->typed_old_to_new_slots()->FreeToBeFreedChunks();
     }
+    if (page->old_to_new_slots()) {
+      page->old_to_new_slots()->FreeToBeFreedBuckets();
+    }
 
     {
       base::LockGuard<base::Mutex> guard(&mutex_);
       swept_list_[identity].Add(page);
     }
     page->concurrent_sweeping_state().SetValue(Page::kSweepingDone);
     page->mutex()->Unlock();
   }
   return max_freed;
 }
@@ skipping 155 matching lines @@
       // The target is always in old space, we don't have to record the slot in
       // the old-to-new remembered set.
       DCHECK(!heap()->InNewSpace(target));
       RecordRelocSlot(host, &rinfo, target);
     }
   }
 }
 
 }  // namespace internal
 }  // namespace v8