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