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