diff -r cefb7b496d17 -r ece10494786c src/hotspot/share/gc/g1/g1CardTable.hpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/g1/g1CardTable.hpp	Fri Mar 02 21:00:12 2018 +0100
@@ -0,0 +1,113 @@
+/*
+ * Copyright (c) 2001, 2018, 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_G1CARDTABLE_HPP
+#define SHARE_VM_GC_G1_G1CARDTABLE_HPP
+
+#include "gc/g1/g1RegionToSpaceMapper.hpp"
+#include "gc/shared/cardTable.hpp"
+#include "oops/oopsHierarchy.hpp"
+#include "utilities/macros.hpp"
+
+class G1CardTable;
+class G1RegionToSpaceMapper;
+
+class G1CardTableChangedListener : public G1MappingChangedListener {
+ private:
+  G1CardTable* _card_table;
+ public:
+  G1CardTableChangedListener() : _card_table(NULL) { }
+
+  void set_card_table(G1CardTable* card_table) { _card_table = card_table; }
+
+  virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
+};
+
+class G1CardTable: public CardTable {
+  friend class VMStructs;
+  friend class G1CardTableChangedListener;
+
+  G1CardTableChangedListener _listener;
+
+  enum G1CardValues {
+    g1_young_gen = CT_MR_BS_last_reserved << 1
+  };
+
+public:
+  G1CardTable(MemRegion whole_heap): CardTable(whole_heap, /* scanned concurrently */ true), _listener() {
+    _listener.set_card_table(this);
+  }
+  bool is_card_dirty(size_t card_index) {
+    return _byte_map[card_index] == dirty_card_val();
+  }
+
+  static jbyte g1_young_card_val() { return g1_young_gen; }
+
+/*
+   Claimed and deferred bits are used together in G1 during the evacuation
+   pause. These bits can have the following state transitions:
+   1. The claimed bit can be put over any other card state. Except that
+      the "dirty -> dirty and claimed" transition is checked for in
+      G1 code and is not used.
+   2. Deferred bit can be set only if the previous state of the card
+      was either clean or claimed. mark_card_deferred() is wait-free.
+      We do not care if the operation is be successful because if
+      it does not it will only result in duplicate entry in the update
+      buffer because of the "cache-miss". So it's not worth spinning.
+ */
+
+  bool is_card_claimed(size_t card_index) {
+    jbyte val = _byte_map[card_index];
+    return (val & (clean_card_mask_val() | claimed_card_val())) == claimed_card_val();
+  }
+
+  inline void set_card_claimed(size_t card_index);
+
+  void verify_g1_young_region(MemRegion mr) PRODUCT_RETURN;
+  void g1_mark_as_young(const MemRegion& mr);
+
+  bool mark_card_deferred(size_t card_index);
+
+  bool is_card_deferred(size_t card_index) {
+    jbyte val = _byte_map[card_index];
+    return (val & (clean_card_mask_val() | deferred_card_val())) == deferred_card_val();
+  }
+
+  static size_t compute_size(size_t mem_region_size_in_words) {
+    size_t number_of_slots = (mem_region_size_in_words / card_size_in_words);
+    return ReservedSpace::allocation_align_size_up(number_of_slots);
+  }
+
+  // Returns how many bytes of the heap a single byte of the Card Table corresponds to.
+  static size_t heap_map_factor() { return card_size; }
+
+  void initialize() {}
+  void initialize(G1RegionToSpaceMapper* mapper);
+
+  virtual void resize_covered_region(MemRegion new_region) { ShouldNotReachHere(); }
+
+  virtual bool is_in_young(oop obj) const;
+};
+
+#endif // SHARE_VM_GC_G1_G1CARDTABLE_HPP