--- /dev/null	2019-02-14 11:31:37.500399000 +0100
+++ new/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/gc/z/ZUtils.java	2019-02-18 10:36:43.074871712 +0100
@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 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.
+ *
+ */
+
+package sun.jvm.hotspot.gc.z;
+
+import sun.jvm.hotspot.debugger.Address;
+import sun.jvm.hotspot.runtime.VM;
+
+class ZUtils {
+    private static final long MSB = ~0L ^ (~0L >>> 1);
+
+    private static Address msbAddress() {
+        return VM.getVM().getUniverse().heap().start().orWithMask(MSB).andWithMask(MSB);
+    }
+
+    static Address longToAddress(long value) {
+        // If the value of an Address becomes 0, null is returned instead of an Address.
+        // Start with a one-bit address and as a last step, remove that bit.
+        Address oneAddress = msbAddress();
+        return oneAddress.orWithMask(value).xorWithMask(ZAddress.as_long(oneAddress));
+    }
+}