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