1 /*
   2  * Copyright (c) 2016, Red Hat, Inc. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 /**
  25  * @test
  26  * @bug 8167298
  27  * @summary Unsafe.compareAndExchangeObject should keep track of returned type after matching
  28  * @modules java.base/jdk.internal.misc
  29  * @run main/othervm -XX:+IgnoreUnrecognizedVMOptions -XX:-BackgroundCompilation -XX:-UseOnStackReplacement -XX:-UseCompressedOops TestCAEAntiDep
  30  *
  31  */
  32 
  33 import java.lang.reflect.Field;
  34 import jdk.internal.misc.Unsafe;
  35 
  36 public class TestCAEAntiDep {
  37     static final jdk.internal.misc.Unsafe UNSAFE = Unsafe.getUnsafe();
  38     static final long O_OFFSET;
  39 
  40     static class C {
  41         int f1;
  42     }
  43 
  44     C o = new C();
  45 
  46     static {
  47         try {
  48             Field oField = TestCAEAntiDep.class.getDeclaredField("o");
  49             O_OFFSET = UNSAFE.objectFieldOffset(oField);
  50         } catch (Exception e) {
  51             throw new RuntimeException(e);
  52         }
  53     }
  54 
  55     static int m(TestCAEAntiDep test, Object expected, Object x) {
  56         C old = (C)UNSAFE.compareAndExchangeObjectVolatile(test, O_OFFSET, expected, x);
  57         int res = old.f1;
  58         old.f1 = 0x42;
  59         return res;
  60     }
  61 
  62     static public void main(String[] args) {
  63         TestCAEAntiDep test = new TestCAEAntiDep();
  64         for (int i = 0; i < 20000; i++) {
  65             m(test, test.o, test.o);
  66         }
  67     }
  68 }