1 /*

     2  * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.

     3  * Copyright (c) 2016, Red Hat, Inc. All rights reserved.

     4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     5  *

     6  * This code is free software; you can redistribute it and/or modify it

     7  * under the terms of the GNU General Public License version 2 only, as

     8  * published by the Free Software Foundation.

     9  *

    10  * This code is distributed in the hope that it will be useful, but WITHOUT

    11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    13  * version 2 for more details (a copy is included in the LICENSE file that

    14  * accompanied this code).

    15  *

    16  * You should have received a copy of the GNU General Public License version

    17  * 2 along with this work; if not, write to the Free Software Foundation,

    18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    19  *

    20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    21  * or visit www.oracle.com if you need additional information or have any

    22  * questions.

    23  */

    24 

    25 /**

    26  * @test

    27  * @bug 8167298

    28  * @summary Unsafe.compareAndExchangeObject should keep track of returned type after matching

    29  * @modules java.base/jdk.internal.misc

    30  * @run main/othervm -XX:+IgnoreUnrecognizedVMOptions -XX:-BackgroundCompilation -XX:-UseOnStackReplacement -XX:-UseCompressedOops TestCAEAntiDep

    31  *

    32  */

    33 

    34 import java.lang.reflect.Field;

    35 import jdk.internal.misc.Unsafe;

    36 

    37 public class TestCAEAntiDep {

    38     static final jdk.internal.misc.Unsafe UNSAFE = Unsafe.getUnsafe();

    39     static final long O_OFFSET;

    40 

    41     static class C {

    42         int f1;

    43     }

    44 

    45     C o = new C();

    46 

    47     static {

    48         try {

    49             Field oField = TestCAEAntiDep.class.getDeclaredField("o");

    50             O_OFFSET = UNSAFE.objectFieldOffset(oField);

    51         } catch (Exception e) {

    52             throw new RuntimeException(e);

    53         }

    54     }

    55 

    56     static int m(TestCAEAntiDep test, Object expected, Object x) {

    57         C old = (C)UNSAFE.compareAndExchangeObject(test, O_OFFSET, expected, x);

    58         int res = old.f1;

    59         old.f1 = 0x42;

    60         return res;

    61     }

    62 

    63     static public void main(String[] args) {

    64         TestCAEAntiDep test = new TestCAEAntiDep();

    65         for (int i = 0; i < 20000; i++) {

    66             m(test, test.o, test.o);

    67         }

    68     }

    69 }