[heap] Use the thread-safe free modes also for RemoveRange in SlotSet.

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/context-slot-cache.h"
 #include "src/base/bits.h"
@@ skipping 5945 matching lines @@
     RememberedSet<OLD_TO_NEW>::Remove(page, slot_addr);
     RememberedSet<OLD_TO_OLD>::Remove(page, slot_addr);
   }
 }
 
 void Heap::ClearRecordedSlotRange(Address start, Address end) {
   Page* page = Page::FromAddress(start);
   if (!page->InNewSpace()) {
     store_buffer()->MoveEntriesToRememberedSet();
     DCHECK_EQ(page->owner()->identity(), OLD_SPACE);
-    RememberedSet<OLD_TO_NEW>::RemoveRange(page, start, end);
-    RememberedSet<OLD_TO_OLD>::RemoveRange(page, start, end);
+    RememberedSet<OLD_TO_NEW>::RemoveRange(page, start, end,
+                                           SlotSet::PREFREE_EMPTY_BUCKETS);
+    RememberedSet<OLD_TO_OLD>::RemoveRange(page, start, end,

[Hannes Payer (out of office), 2016/10/07 07:50:57]

I added an additional mode here because old to old will never have concurrent
access and can be freed directly. However, it may be beneficial to never
deallocate on the main thread an push the work to concurrent tasks. Any
thoughts?

[Michael Lippautz, 2016/10/07 09:11:06]

Even if there's not concurrent access, I would in the end try to free them at
the same place, i.e., I would deallocate them in the sweeper.

+                                           SlotSet::FREE_EMPTY_BUCKETS);
   }
 }
 
 void Heap::RecordWriteIntoCodeSlow(Code* host, RelocInfo* rinfo,
                                    Object* value) {
   DCHECK(InNewSpace(value));
   Page* source_page = Page::FromAddress(reinterpret_cast<Address>(host));
   RelocInfo::Mode rmode = rinfo->rmode();
   Address addr = rinfo->pc();
   SlotType slot_type = SlotTypeForRelocInfoMode(rmode);
@@ skipping 550 matching lines @@
 }
 
 
 // static
 int Heap::GetStaticVisitorIdForMap(Map* map) {
   return StaticVisitorBase::GetVisitorId(map);
 }
 
 }  // namespace internal
 }  // namespace v8