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 }