--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/shared/accessBarrierSupport.cpp	Mon Nov 20 13:07:44 2017 +0100
@@ -0,0 +1,40 @@
+/*
+ * 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.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "classfile/javaClasses.inline.hpp"
+#include "gc/shared/accessBarrierSupport.inline.hpp"
+#include "oops/access.hpp"
+
+DecoratorSet AccessBarrierSupport::resolve_unknown_oop_ref_strength(DecoratorSet decorators, oop base, ptrdiff_t offset) {
+  DecoratorSet ds = decorators & ~ON_UNKNOWN_OOP_REF;
+  if (!java_lang_ref_Reference::is_referent_field(base, offset)) {
+    ds |= ON_STRONG_OOP_REF;
+  } else if (java_lang_ref_Reference::is_phantom(base)) {
+    ds |= ON_PHANTOM_OOP_REF;
+  } else {
+    ds |= ON_WEAK_OOP_REF;
+  }
+  return ds;
+}