--- /dev/null	2018-04-03 12:55:20.301839954 +0200
+++ new/src/hotspot/share/gc/z/zForwardingTableEntry.hpp	2018-06-01 22:30:32.457529000 +0200
@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2017, 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_GC_Z_ZFORWARDINGTABLEENTRY_HPP
+#define SHARE_GC_Z_ZFORWARDINGTABLEENTRY_HPP
+
+#include "gc/z/zBitField.hpp"
+#include "memory/allocation.hpp"
+#include "metaprogramming/primitiveConversions.hpp"
+
+//
+// Forwarding table entry layout
+// -----------------------------
+//
+//   6                      4 4                                             0
+//   3                      2 1                                             0
+//  +------------------------+-----------------------------------------------+
+//  |11111111 11111111 111111|11 11111111 11111111 11111111 11111111 11111111|
+//  +------------------------+-----------------------------------------------+
+//  |                        |
+//  |                        * 41-0 To Object Offset (42-bits)
+//  |
+//  * 63-42 From Object Index (22-bits)
+//
+
+class ZForwardingTableEntry {
+  friend struct PrimitiveConversions;
+
+private:
+  typedef ZBitField<uint64_t, size_t, 0,  42> field_to_offset;
+  typedef ZBitField<uint64_t, size_t, 42, 22> field_from_index;
+
+  uint64_t _entry;
+
+public:
+  ZForwardingTableEntry() :
+      _entry(empty()) {}
+
+  ZForwardingTableEntry(size_t from_index, size_t to_offset) :
+      _entry(field_from_index::encode(from_index) |
+             field_to_offset::encode(to_offset)) {}
+
+  static uintptr_t empty() {
+    return (uintptr_t)-1;
+  }
+
+  bool is_empty() const {
+    return _entry == empty();
+  }
+
+  size_t to_offset() const {
+    return field_to_offset::decode(_entry);
+  }
+
+  size_t from_index() const {
+    return field_from_index::decode(_entry);
+  }
+};
+
+// Needed to allow atomic operations on ZForwardingTableEntry
+template <>
+struct PrimitiveConversions::Translate<ZForwardingTableEntry> : public TrueType {
+  typedef ZForwardingTableEntry Value;
+  typedef uint64_t              Decayed;
+
+  static Decayed decay(Value v) {
+    return v._entry;
+  }
+
+  static Value recover(Decayed d) {
+    ZForwardingTableEntry entry;
+    entry._entry = d;
+    return entry;
+  }
+};
+
+#endif // SHARE_GC_Z_ZFORWARDINGTABLEENTRY_HPP