Simple non-incremental compaction by evacuation.

src/store-buffer.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 537 matching lines @@
   }
   ASSERT(visitable_end == end_of_page);
   if (visitable_start != visitable_end) {
     (this->*region_callback)(visitable_start,
                              visitable_end,
                              slot_callback);
   }
 }
 
 
-
-void StoreBuffer::IteratePointersToNewSpace(ObjectSlotCallback slot_callback) {
-  // We do not sort or remove duplicated entries from the store buffer because
-  // we expect that callback will rebuild the store buffer thus removing
-  // all duplicates and pointers to old space.
-  bool some_pages_to_scan = PrepareForIteration();
-
+template<StoreBuffer::IterationMode mode>
+void StoreBuffer::IteratePointersInStoreBuffer(
+    ObjectSlotCallback slot_callback) {
   Address* limit = old_top_;
   old_top_ = old_start_;
   {
     DontMoveStoreBufferEntriesScope scope(this);
     for (Address* current = old_start_; current < limit; current++) {
 #ifdef DEBUG
       Address* saved_top = old_top_;
 #endif
       Object** slot = reinterpret_cast<Object**>(*current);
+
+      // TODO(gc): we want to skip slots on evacuation candidates
+      // but we can't simply figure that out from slot address
+      // because slot can belong to a large object.

[Erik Corry, 2011/06/20 20:41:26]

Pity.  I was looking forward to seeing how you would do that :-)

+
       Object* object = *slot;
       if (heap_->InFromSpace(object)) {
         HeapObject* heap_object = reinterpret_cast<HeapObject*>(object);
         slot_callback(reinterpret_cast<HeapObject**>(slot), heap_object);
         if (heap_->InNewSpace(*slot)) {
           EnterDirectlyIntoStoreBuffer(reinterpret_cast<Address>(slot));
         }
       }
       ASSERT(old_top_ == saved_top + 1 || old_top_ == saved_top);
     }
   }
+

[Erik Corry, 2011/06/20 20:41:26]

Spurious blank line.

[Vyacheslav Egorov (Chromium), 2011/06/21 11:44:48]

Done.

+}
+
+
+void StoreBuffer::IteratePointersToNewSpace(ObjectSlotCallback slot_callback,
+                                            IterationMode mode) {
+  // We do not sort or remove duplicated entries from the store buffer because
+  // we expect that callback will rebuild the store buffer thus removing
+  // all duplicates and pointers to old space.
+  bool some_pages_to_scan = PrepareForIteration();
+
+  if (mode == SKIP_SLOTS_IN_EVACUATION_CANDIDATES) {
+    IteratePointersInStoreBuffer<SKIP_SLOTS_IN_EVACUATION_CANDIDATES>(
+        slot_callback);
+  } else {
+    ASSERT(mode == VISIT_ALL_SLOTS);
+    IteratePointersInStoreBuffer<VISIT_ALL_SLOTS>(slot_callback);
+  }
+
+
   // We are done scanning all the pointers that were in the store buffer, but
   // there may be some pages marked scan_on_scavenge that have pointers to new
   // space that are not in the store buffer.  We must scan them now.  As we
   // scan, the surviving pointers to new space will be added to the store
   // buffer.  If there are still a lot of pointers to new space then we will
   // keep the scan_on_scavenge flag on the page and discard the pointers that
   // were added to the store buffer.  If there are not many pointers to new
   // space left on the page we will keep the pointers in the store buffer and
   // remove the flag from the page.
   if (some_pages_to_scan) {
@@ skipping 83 matching lines @@
 }
 
 
 void StoreBuffer::CheckForFullBuffer() {
   if (old_limit_ - old_top_ < kStoreBufferSize * 2) {
     HandleFullness();
   }
 }
 
 } }  // namespace v8::internal