1 /* 2 * Copyright (c) 2013, 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 8016474 27 * @summary The bug only happens with C1 and G1 using a different ObjectAlignmentInBytes than KlassAlignmentInBytes (which is 8) 28 * @run main/othervm -Xbatch -XX:+IgnoreUnrecognizedVMOptions -XX:ObjectAlignmentInBytes=32 GetUnsafeObjectG1PreBarrier 29 */ 30 31 import java.lang.reflect.Field; 32 33 import sun.misc.Unsafe; 34 35 public class GetUnsafeObjectG1PreBarrier { 36 private static final Unsafe unsafe; 37 private static final int N = 100_000; 38 39 static { 40 try { 41 Field theUnsafe = Unsafe.class.getDeclaredField("theUnsafe"); 42 theUnsafe.setAccessible(true); 43 unsafe = (Unsafe) theUnsafe.get(null); 44 } catch (NoSuchFieldException | IllegalAccessException e) { 45 throw new IllegalStateException(e); 46 } 47 } 48 49 public Object a; 50 main(String[] args)51 public static void main(String[] args) throws Throwable { 52 new GetUnsafeObjectG1PreBarrier(); 53 } 54 GetUnsafeObjectG1PreBarrier()55 public GetUnsafeObjectG1PreBarrier() throws Throwable { 56 doit(); 57 } 58 doit()59 private void doit() throws Throwable { 60 Field field = GetUnsafeObjectG1PreBarrier.class.getField("a"); 61 long fieldOffset = unsafe.objectFieldOffset(field); 62 63 for (int i = 0; i < N; i++) { 64 readField(this, fieldOffset); 65 } 66 } 67 readField(Object o, long fieldOffset)68 private void readField(Object o, long fieldOffset) { 69 unsafe.getObject(o, fieldOffset); 70 } 71 } 72