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 }