1 /*
2  * Copyright (c) 2013, 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
26  * @bug 8016474
27  * @summary The bug only happens with C1 and G1 using a different ObjectAlignmentInBytes than KlassAlignmentInBytes (which is 8)
28  * @run main/othervm -Xbatch -XX:+IgnoreUnrecognizedVMOptions -XX:ObjectAlignmentInBytes=32 GetUnsafeObjectG1PreBarrier
29  */
30 
31 import java.lang.reflect.Field;
32 
33 import sun.misc.Unsafe;
34 
35 public class GetUnsafeObjectG1PreBarrier {
36     private static final Unsafe unsafe;
37     private static final int N = 100_000;
38 
39     static {
40         try {
41             Field theUnsafe = Unsafe.class.getDeclaredField("theUnsafe");
42             theUnsafe.setAccessible(true);
43             unsafe = (Unsafe) theUnsafe.get(null);
44         } catch (NoSuchFieldException | IllegalAccessException e) {
45             throw new IllegalStateException(e);
46         }
47     }
48 
49     public Object a;
50 
main(String[] args)51     public static void main(String[] args) throws Throwable {
52         new GetUnsafeObjectG1PreBarrier();
53     }
54 
GetUnsafeObjectG1PreBarrier()55     public GetUnsafeObjectG1PreBarrier() throws Throwable {
56         doit();
57     }
58 
doit()59     private void doit() throws Throwable {
60         Field field = GetUnsafeObjectG1PreBarrier.class.getField("a");
61         long fieldOffset = unsafe.objectFieldOffset(field);
62 
63         for (int i = 0; i < N; i++) {
64             readField(this, fieldOffset);
65         }
66     }
67 
readField(Object o, long fieldOffset)68     private void readField(Object o, long fieldOffset) {
69         unsafe.getObject(o, fieldOffset);
70     }
71 }
72