1 /*
   2  * Copyright (c) 2014, Oracle and/or its affiliates. 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 TestMemBarAcquire
  26  * @bug 8048879
  27  * @summary Tests optimization of MemBarAcquireNodes
  28  * @run main/othervm -XX:-TieredCompilation -XX:-BackgroundCompilation
  29  *                   compiler.membars.TestMemBarAcquire
  30  */
  31 
  32 package compiler.membars;
  33 
  34 public class TestMemBarAcquire {
  35     private volatile static Object defaultObj = new Object();
  36     private Object obj;
  37 
  38     public TestMemBarAcquire(Object param) {
  39         // Volatile load. MemBarAcquireNode is added after the
  40         // load to prevent following loads from floating up past.
  41         // StoreNode is added to store result of load in 'obj'.
  42         this.obj = defaultObj;
  43         // Overrides 'obj' and therefore makes previous StoreNode
  44         // and the corresponding LoadNode useless. However, the
  45         // LoadNode is still connected to the MemBarAcquireNode
  46         // that should now release the reference.
  47         this.obj = param;
  48     }
  49 
  50     public static void main(String[] args) throws Exception {
  51         // Make sure TestMemBarAcquire::<init> is compiled
  52         for (int i = 0; i < 100000; ++i) {
  53             TestMemBarAcquire p = new TestMemBarAcquire(new Object());
  54         }
  55     }
  56 }
  57