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

rev 51979 : imported patch 8071913-almost-done
rev 51980 : imported patch 8071913-alternate
rev 51982 : [mq]: 8211388-make-otherregionstable-unaware-of-to-region

@@ -74,11 +74,10 @@
 class OtherRegionsTable {
   friend class HeapRegionRemSetIterator;
 
   G1CollectedHeap* _g1h;
   Mutex*           _m;
-  HeapRegion*      _hr;
 
   // These are protected by "_m".
   CHeapBitMap _coarse_map;
   size_t      _n_coarse_entries;
   static jint _n_coarsenings;

@@ -122,15 +121,13 @@
   void unlink_from_all(PerRegionTable * prt);
 
   bool contains_reference_locked(OopOrNarrowOopStar from) const;
 
 public:
-  // Clear the from_card_cache entries for this region.
-  void clear_fcc();
   // Create a new remembered set for the given heap region. The given mutex should
   // be used to ensure consistency.
-  OtherRegionsTable(HeapRegion* hr, Mutex* m);
+  OtherRegionsTable(Mutex* m);
 
   // Returns the card index of the given within_region pointer relative to the bottom
   // of the given heap region.
   static CardIdx_t card_within_region(OopOrNarrowOopStar within_region, HeapRegion* hr);
   // Adds the reference from "from to this remembered set.

@@ -180,10 +177,14 @@
 
   Mutex _m;
 
   OtherRegionsTable _other_regions;
 
+  HeapRegion* _hr;
+
+  void clear_fcc();
+
 public:
   HeapRegionRemSet(G1BlockOffsetTable* bot, HeapRegion* hr);
 
   static void setup_remset_size();
 

@@ -241,22 +242,22 @@
   void set_state_empty() {
     guarantee(SafepointSynchronize::is_at_safepoint() || !is_tracked(), "Should only set to Untracked during safepoint but is %s.", get_state_str());
     if (_state == Untracked) {
       return;
     }
-    _other_regions.clear_fcc();
+    clear_fcc();
     _state = Untracked;
   }
 
   void set_state_updating() {
     guarantee(SafepointSynchronize::is_at_safepoint() && !is_tracked(), "Should only set to Updating from Untracked during safepoint but is %s", get_state_str());
-    _other_regions.clear_fcc();
+    clear_fcc();
     _state = Updating;
   }
 
   void set_state_complete() {
-    _other_regions.clear_fcc();
+    clear_fcc();
     _state = Complete;
   }
 
   // Used in the sequential case.
   void add_reference(OopOrNarrowOopStar from) {

@@ -267,10 +268,19 @@
   void add_reference(OopOrNarrowOopStar from, uint tid) {
     RemSetState state = _state;
     if (state == Untracked) {
       return;
     }
+
+    uint cur_idx = _hr->hrm_index();
+    uintptr_t from_card = uintptr_t(from) >> CardTable::card_shift;
+
+    if (G1FromCardCache::contains_or_replace(tid, cur_idx, from_card)) {
+      assert(contains_reference(from), "We just found " PTR_FORMAT " in the FromCardCache", p2i(from));
+      return;
+    }
+
     _other_regions.add_reference(from, tid);
   }
 
   // The region is being reclaimed; clear its remset, and any mention of
   // entries for this region in other remsets.