--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/shared/modRefBarrierSet.hpp	Wed May 13 15:16:06 2015 +0200
@@ -0,0 +1,105 @@
+/*
+ * Copyright (c) 2000, 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_SHARED_MODREFBARRIERSET_HPP
+#define SHARE_VM_GC_SHARED_MODREFBARRIERSET_HPP
+
+#include "gc/shared/barrierSet.hpp"
+
+// This kind of "BarrierSet" allows a "CollectedHeap" to detect and
+// enumerate ref fields that have been modified (since the last
+// enumeration), using a card table.
+
+class OopClosure;
+class Generation;
+
+class ModRefBarrierSet: public BarrierSet {
+public:
+
+  // Barriers only on ref writes.
+  bool has_read_ref_barrier() { return false; }
+  bool has_read_prim_barrier() { return false; }
+  bool has_write_ref_barrier() { return true; }
+  bool has_write_prim_barrier() { return false; }
+
+  bool read_ref_needs_barrier(void* field) { return false; }
+  bool read_prim_needs_barrier(HeapWord* field, size_t bytes) { return false; }
+  bool write_prim_needs_barrier(HeapWord* field, size_t bytes,
+                                juint val1, juint val2) { return false; }
+
+  void write_prim_field(oop obj, size_t offset, size_t bytes,
+                        juint val1, juint val2) {}
+
+  void read_ref_field(void* field) {}
+  void read_prim_field(HeapWord* field, size_t bytes) {}
+
+protected:
+
+  ModRefBarrierSet(const BarrierSet::FakeRtti& fake_rtti)
+    : BarrierSet(fake_rtti.add_tag(BarrierSet::ModRef)) { }
+  ~ModRefBarrierSet() { }
+
+  virtual void write_ref_field_work(void* field, oop new_val, bool release = false) = 0;
+public:
+  void write_prim_field(HeapWord* field, size_t bytes,
+                        juint val1, juint val2) {}
+
+  bool has_read_ref_array_opt() { return false; }
+  bool has_read_prim_array_opt() { return false; }
+  bool has_write_prim_array_opt() { return false; }
+
+  bool has_read_region_opt() { return false; }
+
+
+  // These operations should assert false unless the corresponding operation
+  // above returns true.
+  void read_ref_array(MemRegion mr) {
+    assert(false, "can't call");
+  }
+  void read_prim_array(MemRegion mr) {
+    assert(false, "can't call");
+  }
+  void write_prim_array(MemRegion mr) {
+    assert(false, "can't call");
+  }
+  void read_region(MemRegion mr) {
+    assert(false, "can't call");
+  }
+
+  // Causes all refs in "mr" to be assumed to be modified.  If "whole_heap"
+  // is true, the caller asserts that the entire heap is being invalidated,
+  // which may admit an optimized implementation for some barriers.
+  virtual void invalidate(MemRegion mr, bool whole_heap = false) = 0;
+
+  // The caller guarantees that "mr" contains no references.  (Perhaps it's
+  // objects have been moved elsewhere.)
+  virtual void clear(MemRegion mr) = 0;
+};
+
+template<>
+struct BarrierSet::GetName<ModRefBarrierSet> {
+  static const BarrierSet::Name value = BarrierSet::ModRef;
+};
+
+#endif // SHARE_VM_GC_SHARED_MODREFBARRIERSET_HPP