1 /*
   2  * Copyright (c) 2016, 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  * @test
  25  * @bug 8134918
  26  * @modules java.base/jdk.internal.misc
  27  * @run main/bootclasspath -XX:+IgnoreUnrecognizedVMOptions -XX:TypeProfileLevel=222 -XX:+UseTypeSpeculation -Xbatch
  28  *                         -XX:CompileCommand=dontinline,UnsafeAccess::test*
  29  *                         UnsafeAccess
  30  */
  31 import jdk.internal.misc.Unsafe;
  32 
  33 public class UnsafeAccess {
  34     private static final Unsafe U = Unsafe.getUnsafe();
  35 
  36     static Class cls = Object.class;
  37     static long off = U.ARRAY_OBJECT_BASE_OFFSET;
  38 
  39     static Object testUnsafeAccess(Object o, boolean isObjArray) {
  40         if (o != null && cls.isInstance(o)) { // speculates "o" type to int[]
  41             return helperUnsafeAccess(o, isObjArray);
  42         }
  43         return null;
  44     }
  45 
  46     static Object helperUnsafeAccess(Object o, boolean isObjArray) {
  47         if (isObjArray) {
  48             U.putObject(o, off, new Object());
  49         }
  50         return o;
  51     }
  52 
  53     static Object testUnsafeLoadStore(Object o, boolean isObjArray) {
  54         if (o != null && cls.isInstance(o)) { // speculates "o" type to int[]
  55             return helperUnsafeLoadStore(o, isObjArray);
  56         }
  57         return null;
  58     }
  59 
  60     static Object helperUnsafeLoadStore(Object o, boolean isObjArray) {
  61         if (isObjArray) {
  62             Object o1 = U.getObject(o, off);
  63             U.compareAndSwapObject(o, off, o1, new Object());
  64         }
  65         return o;
  66     }
  67 
  68     public static void main(String[] args) {
  69         Object[] objArray = new Object[10];
  70         int[]    intArray = new    int[10];
  71 
  72         for (int i = 0; i < 20_000; i++) {
  73             helperUnsafeAccess(objArray, true);
  74         }
  75         for (int i = 0; i < 20_000; i++) {
  76             testUnsafeAccess(intArray, false);
  77         }
  78 
  79         for (int i = 0; i < 20_000; i++) {
  80             helperUnsafeLoadStore(objArray, true);
  81         }
  82         for (int i = 0; i < 20_000; i++) {
  83             testUnsafeLoadStore(intArray, false);
  84         }
  85 
  86         System.out.println("TEST PASSED");
  87     }
  88 }