--- /dev/null	2018-04-03 12:55:20.301839954 +0200
+++ new/src/hotspot/share/gc/z/zMarkStackEntry.hpp	2018-06-08 19:46:19.074671994 +0200
@@ -0,0 +1,118 @@
+/*
+ * 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_ZMARKSTACKENTRY_HPP
+#define SHARE_GC_Z_ZMARKSTACKENTRY_HPP
+
+#include "gc/z/zBitField.hpp"
+#include "memory/allocation.hpp"
+
+//
+// Mark stack entry layout
+// -----------------------
+//
+//  Object entry
+//  ------------
+//
+//   6
+//   3                                                                   2 1 0
+//  +---------------------------------------------------------------------+-+-+
+//  |11111111 11111111 11111111 11111111 11111111 11111111 11111111 111111|1|1|
+//  +---------------------------------------------------------------------+-+-+
+//  |                                                                     | |
+//  |                                      1-1 Partial Array Flag (1-bit) * |
+//  |                                                                       |
+//  |                                                0-0 Final Flag (1-bit) *
+//  |
+//  * 63-2 Object Address (62-bits)
+//
+//
+//  Partial array entry
+//  -------------------
+//
+//   6                                 3  3
+//   3                                 2  1                               2 1 0
+//  +------------------------------------+---------------------------------+-+-+
+//  |11111111 11111111 11111111 11111111 |11111111 11111111 11111111 111111|1|1|
+//  +------------------------------------+---------------------------------+-+-+
+//  |                                    |                                 | |
+//  |                                    |  1-1 Partial Array Flag (1-bit) * |
+//  |                                    |                                   |
+//  |                                    |            0-0 Final Flag (1-bit) *
+//  |                                    |
+//  |                                    * 31-2 Partial Array Length (30-bits)
+//  |
+//  * 63-32 Partial Array Address Offset (32-bits)
+//
+
+class ZMarkStackEntry  {
+private:
+  typedef ZBitField<uint64_t, bool,      0,  1>  field_finalizable;
+  typedef ZBitField<uint64_t, bool,      1,  1>  field_partial_array;
+  typedef ZBitField<uint64_t, uintptr_t, 2,  62> field_object_address;
+  typedef ZBitField<uint64_t, size_t,    2,  30> field_partial_array_length;
+  typedef ZBitField<uint64_t, size_t,    32, 32> field_partial_array_offset;
+
+  uint64_t _entry;
+
+public:
+  ZMarkStackEntry() {
+    // This constructor is intentionally left emtpy and does not initialize
+    // _entry to allow it to be optimized out when instantiating ZMarkStack,
+    // which has a long array of ZMarkStackEntry elements, but doesn't care
+    // what _entry is initialized to.
+  }
+
+  ZMarkStackEntry(uintptr_t object_address, bool finalizable) :
+      _entry(field_object_address::encode(object_address) |
+             field_partial_array::encode(false) |
+             field_finalizable::encode(finalizable)) {}
+
+  ZMarkStackEntry(size_t partial_array_offset, size_t partial_array_length, bool finalizable) :
+      _entry(field_partial_array_offset::encode(partial_array_offset) |
+             field_partial_array_length::encode(partial_array_length) |
+             field_partial_array::encode(true) |
+             field_finalizable::encode(finalizable)) {}
+
+  bool finalizable() const {
+    return field_finalizable::decode(_entry);
+  }
+
+  bool partial_array() const {
+    return field_partial_array::decode(_entry);
+  }
+
+  size_t partial_array_offset() const {
+    return field_partial_array_offset::decode(_entry);
+  }
+
+  size_t partial_array_length() const {
+    return field_partial_array_length::decode(_entry);
+  }
+
+  uintptr_t object_address() const {
+    return field_object_address::decode(_entry);
+  }
+};
+
+#endif // SHARE_GC_Z_ZMARKSTACKENTRY_HPP