1 /* 2 * Copyright (c) 2017, 2018, Red Hat, Inc. 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 * @summary cast before unsafe access moved in dominating null check null path causes crash 27 * @modules java.base/jdk.internal.misc:+open 28 * 29 * @run main/othervm -XX:-UseOnStackReplacement -XX:-BackgroundCompilation -XX:-TieredCompilation TestMaybeNullUnsafeAccess 30 * 31 */ 32 33 import jdk.internal.misc.Unsafe; 34 import java.lang.reflect.Field; 35 36 public class TestMaybeNullUnsafeAccess { 37 38 static final jdk.internal.misc.Unsafe UNSAFE = Unsafe.getUnsafe(); 39 static final long F_OFFSET; 40 41 static class A { 42 int f; 43 } 44 45 static { 46 try { 47 Field fField = A.class.getDeclaredField("f"); 48 F_OFFSET = UNSAFE.objectFieldOffset(fField); 49 } catch (Exception e) { 50 throw new RuntimeException(e); 51 } 52 } 53 54 static A test_helper(Object o) { 55 return (A)o; 56 } 57 58 static int test(Object o) { 59 int f = 0; 60 for (int i = 0; i < 100; i++) { 61 A a = test_helper(o); 62 f = UNSAFE.getInt(a, F_OFFSET); 63 } 64 return f; 65 } 66 67 static public void main(String[] args) { 68 A a = new A(); 69 for (int i = 0; i < 20000; i++) { 70 test_helper(null); 71 test_helper(a); 72 test(a); 73 } 74 } 75 76 }