1 /*
2  * Copyright (c) 2015, 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 8077504
27  * @summary Unsafe load can loose control dependency and cause crash
28  * @run main/othervm -XX:-BackgroundCompilation -XX:-UseOnStackReplacement TestUnsafeLoadControl
29  *
30  */
31 
32 import java.lang.reflect.Field;
33 import sun.misc.Unsafe;
34 
35 public class TestUnsafeLoadControl {
36 
37     private static final Unsafe UNSAFE;
38 
39     static {
40         try {
41             Field unsafeField = Unsafe.class.getDeclaredField("theUnsafe");
42             unsafeField.setAccessible(true);
43             UNSAFE = (Unsafe) unsafeField.get(null);
44         } catch(Exception e) {
45             throw new RuntimeException(e);
46         }
47     }
48 
49     static int val;
test1(int[] a, boolean[] flags, boolean flag, long j)50     static void test1(int[] a, boolean[] flags, boolean flag, long j) {
51         for (int i = 0; i < 10; i++) {
52             if (flags[i]) {
53                 if (flag) {
54                     long address = (j << 2) + UNSAFE.ARRAY_INT_BASE_OFFSET;
55                     int v = UNSAFE.getInt(a, address);
56                     val = v;
57                 }
58             }
59         }
60     }
61 
test2(int[] a, boolean[] flags, boolean flag, long j)62     static int test2(int[] a, boolean[] flags, boolean flag, long j) {
63         int sum = 0;
64         for (int i = 0; i < 10; i++) {
65             if (flags[i]) {
66                 if (flag) {
67                     long address = (j << 2) + UNSAFE.ARRAY_INT_BASE_OFFSET;
68                     int v = UNSAFE.getInt(a, address);
69                     if (v == 0) {
70                         sum++;
71                     }
72                 }
73             }
74         }
75         return sum;
76     }
77 
main(String[] args)78     static public void main(String[] args) {
79         boolean[] flags = new boolean[10];
80         for (int i = 0; i < flags.length; i++) {
81             flags[i] = true;
82         }
83         int[] array = new int[10];
84         for (int i = 0; i < 20000; i++) {
85             test1(array, flags, true, 0);
86         }
87         for (int i = 0; i < flags.length; i++) {
88             flags[i] = false;
89         }
90         test1(array, flags, true, Long.MAX_VALUE/4);
91 
92         for (int i = 0; i < flags.length; i++) {
93             flags[i] = true;
94         }
95         for (int i = 0; i < 20000; i++) {
96             test2(array, flags, true, 0);
97         }
98         for (int i = 0; i < flags.length; i++) {
99             flags[i] = false;
100         }
101         test2(array, flags, true, Long.MAX_VALUE/4);
102     }
103 }
104