src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/gc/z/ZOop.java

/*
 * 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.debugger.OopHandle;
import sun.jvm.hotspot.runtime.VM;

class ZOop {
    private static final long MSB = ~0L ^ (~0L >>> 1);

    private static Address msbAddress() {
        return VM.getVM().getUniverse().heap().start().orWithMask(MSB).andWithMask(MSB);
    }

    static Address to_address(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));
    }

    static Address to_address(OopHandle oop) {
        return to_address(ZAddress.as_long(oop));
    }
}