8304055: G1: Remove OldGCAllocRegion::release

Reviewed-by: iwalulya, tschatzl

Author: albertnetymk

src/hotspot/share/gc/g1/g1AllocRegion.cpp

@@ -364,31 +364,3 @@ size_t G1GCAllocRegion::retire(bool fill_up) {
   }
   return end_waste;
 }
-
-HeapRegion* OldGCAllocRegion::release() {
-  HeapRegion* cur = get();
-  if (cur != NULL) {
-    // Determine how far we are from the next card boundary. If it is smaller than
-    // the minimum object size we can allocate into, expand into the next card.
-    HeapWord* top = cur->top();
-    HeapWord* aligned_top = align_up(top, BOTConstants::card_size());
-
-    size_t to_allocate_words = pointer_delta(aligned_top, top, HeapWordSize);
-
-    if (to_allocate_words != 0) {
-      // We are not at a card boundary. Fill up, possibly into the next, taking the
-      // end of the region and the minimum object size into account.
-      to_allocate_words = MIN2(pointer_delta(cur->end(), cur->top(), HeapWordSize),
-                               MAX2(to_allocate_words, G1CollectedHeap::min_fill_size()));
-
-      // Skip allocation if there is not enough space to allocate even the smallest
-      // possible object. In this case this region will not be retained, so the
-      // original problem cannot occur.
-      if (to_allocate_words >= G1CollectedHeap::min_fill_size()) {
-        HeapWord* dummy = attempt_allocation(to_allocate_words);
-        cur->fill_with_dummy_object(dummy, to_allocate_words);
-      }
-    }
-  }
-  return G1AllocRegion::release();
-}

src/hotspot/share/gc/g1/g1AllocRegion.hpp

@@ -275,13 +275,6 @@ class OldGCAllocRegion : public G1GCAllocRegion {
 public:
   OldGCAllocRegion(G1EvacStats* stats)
   : G1GCAllocRegion("Old GC Alloc Region", true /* bot_updates */, stats, G1HeapRegionAttr::Old) { }
-
-  // This specialization of release() makes sure that the last card that has
-  // been allocated into has been completely filled by a dummy object.  This
-  // avoids races when remembered set scanning wants to update the BOT of the
-  // last card in the retained old gc alloc region, and allocation threads
-  // allocating into that card at the same time.
-  virtual HeapRegion* release();
 };
 
 #endif // SHARE_GC_G1_G1ALLOCREGION_HPP