src/share/vm/gc/g1/heapRegionRemSet.cpp

rev 11047 : [mq]: 8155233-jon-review

@@ -517,12 +517,14 @@
 void OtherRegionsTable::scrub(G1CardLiveData* live_data) {
   // First eliminated garbage regions from the coarse map.
   log_develop_trace(gc, remset, scrub)("Scrubbing region %u:", _hr->hrm_index());
 
   log_develop_trace(gc, remset, scrub)("   Coarse map: before = " SIZE_FORMAT "...", _n_coarse_entries);
+  if (_n_coarse_entries > 0) {
   live_data->remove_nonlive_regions(&_coarse_map);
   _n_coarse_entries = _coarse_map.count_one_bits();
+  }
   log_develop_trace(gc, remset, scrub)("   after = " SIZE_FORMAT ".", _n_coarse_entries);
 
   // Now do the fine-grained maps.
   for (size_t i = 0; i < _max_fine_entries; i++) {
     PerRegionTable* cur = _fine_grain_regions[i];

@@ -644,11 +646,13 @@
     guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
   }
 
   _first_all_fine_prts = _last_all_fine_prts = NULL;
   _sparse_table.clear();
+  if (_n_coarse_entries > 0) {
   _coarse_map.clear();
+  }
   _n_fine_entries = 0;
   _n_coarse_entries = 0;
 
   clear_fcc();
 }