1 /*
   2  * Copyright (c) 2017, 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 7170145
  27  * @summary C1 doesn't respect the JMM with volatile field loads
  28  *
  29  * @run main/othervm -XX:TieredStopAtLevel=1 VolatileGuardTest
  30  */
  31 public class VolatileGuardTest {
  32     volatile static private int a;
  33     static private int b;
  34 
  35     public static void main(String [] args) throws Exception {
  36         for (int i = 0; i < 100; i++) {
  37             new Thread() {
  38 
  39                 @Override
  40                 public void run() {
  41                     int tt = b; // makes the JVM CSE the value of b
  42 
  43                     while (a == 0) {} // burn
  44                     if (b == 0) {
  45                         System.out.println("error");
  46                         System.exit(1); // fail hard
  47                     }
  48                 }
  49 
  50             }.start();
  51         }
  52 
  53         b = 1;
  54         a = 1;
  55     }
  56 }