diff -r e45861098f5a -r fec48bf5a827 hotspot/src/share/vm/gc/g1/g1CardCounts.hpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/g1/g1CardCounts.hpp	Wed May 13 15:16:06 2015 +0200
@@ -0,0 +1,132 @@
+/*
+ * Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_GC_G1_G1CARDCOUNTS_HPP
+#define SHARE_VM_GC_G1_G1CARDCOUNTS_HPP
+
+#include "gc/g1/g1RegionToSpaceMapper.hpp"
+#include "memory/allocation.hpp"
+#include "memory/virtualspace.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+class CardTableModRefBS;
+class G1CardCounts;
+class G1CollectedHeap;
+class G1RegionToSpaceMapper;
+class HeapRegion;
+
+class G1CardCountsMappingChangedListener : public G1MappingChangedListener {
+ private:
+  G1CardCounts* _counts;
+ public:
+  void set_cardcounts(G1CardCounts* counts) { _counts = counts; }
+
+  virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
+};
+
+// Table to track the number of times a card has been refined. Once
+// a card has been refined a certain number of times, it is
+// considered 'hot' and its refinement is delayed by inserting the
+// card into the hot card cache. The card will then be refined when
+// it is evicted from the hot card cache, or when the hot card cache
+// is 'drained' during the next evacuation pause.
+
+class G1CardCounts: public CHeapObj<mtGC> {
+  G1CardCountsMappingChangedListener _listener;
+
+  G1CollectedHeap* _g1h;
+
+  // The table of counts
+  jubyte* _card_counts;
+
+  // Max capacity of the reserved space for the counts table
+  size_t _reserved_max_card_num;
+
+  // CardTable bottom.
+  const jbyte* _ct_bot;
+
+  // Barrier set
+  CardTableModRefBS* _ct_bs;
+
+  // Returns true if the card counts table has been reserved.
+  bool has_reserved_count_table() { return _card_counts != NULL; }
+
+  // Returns true if the card counts table has been reserved and committed.
+  bool has_count_table() {
+    return has_reserved_count_table();
+  }
+
+  size_t ptr_2_card_num(const jbyte* card_ptr) {
+    assert(card_ptr >= _ct_bot,
+           err_msg("Invalid card pointer: "
+                   "card_ptr: " PTR_FORMAT ", "
+                   "_ct_bot: " PTR_FORMAT,
+                   p2i(card_ptr), p2i(_ct_bot)));
+    size_t card_num = pointer_delta(card_ptr, _ct_bot, sizeof(jbyte));
+    assert(card_num < _reserved_max_card_num,
+           err_msg("card pointer out of range: " PTR_FORMAT, p2i(card_ptr)));
+    return card_num;
+  }
+
+  jbyte* card_num_2_ptr(size_t card_num) {
+    assert(card_num < _reserved_max_card_num,
+           err_msg("card num out of range: "SIZE_FORMAT, card_num));
+    return (jbyte*) (_ct_bot + card_num);
+  }
+
+  // Clear the counts table for the given (exclusive) index range.
+  void clear_range(size_t from_card_num, size_t to_card_num);
+
+ public:
+  G1CardCounts(G1CollectedHeap* g1h);
+
+  // Return the number of slots needed for a card counts table
+  // that covers mem_region_words words.
+  static size_t compute_size(size_t mem_region_size_in_words);
+
+  // Returns how many bytes of the heap a single byte of the card counts table
+  // corresponds to.
+  static size_t heap_map_factor();
+
+  void initialize(G1RegionToSpaceMapper* mapper);
+
+  // Increments the refinement count for the given card.
+  // Returns the pre-increment count value.
+  uint add_card_count(jbyte* card_ptr);
+
+  // Returns true if the given count is high enough to be considered
+  // 'hot'; false otherwise.
+  bool is_hot(uint count);
+
+  // Clears the card counts for the cards spanned by the region
+  void clear_region(HeapRegion* hr);
+
+  // Clears the card counts for the cards spanned by the MemRegion
+  void clear_range(MemRegion mr);
+
+  // Clear the entire card counts table during GC.
+  void clear_all();
+};
+
+#endif // SHARE_VM_GC_G1_G1CARDCOUNTS_HPP