1 /* 2 * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved. 3 * Copyright (c) 2016, Red Hat, Inc. All rights reserved. 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 6 * This code is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 only, as 8 * published by the Free Software Foundation. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 */ 24 25 /** 26 * @test 27 * @bug 8167298 28 * @summary Unsafe.compareAndExchangeReference should keep track of returned type after matching 29 * @modules java.base/jdk.internal.misc 30 * @run main/othervm -XX:+IgnoreUnrecognizedVMOptions -XX:-BackgroundCompilation -XX:-UseOnStackReplacement -XX:-UseCompressedOops TestCAEAntiDep 31 * 32 */ 33 34 import java.lang.reflect.Field; 35 import jdk.internal.misc.Unsafe; 36 37 public class TestCAEAntiDep { 38 static final jdk.internal.misc.Unsafe UNSAFE = Unsafe.getUnsafe(); 39 static final long O_OFFSET; 40 41 static class C { 42 int f1; 43 } 44 45 C o = new C(); 46 47 static { 48 try { 49 Field oField = TestCAEAntiDep.class.getDeclaredField("o"); 50 O_OFFSET = UNSAFE.objectFieldOffset(oField); 51 } catch (Exception e) { 52 throw new RuntimeException(e); 53 } 54 } 55 56 static int m(TestCAEAntiDep test, Object expected, Object x) { 57 C old = (C)UNSAFE.compareAndExchangeReference(test, O_OFFSET, expected, x); 58 int res = old.f1; 59 old.f1 = 0x42; 60 return res; 61 } 62 63 static public void main(String[] args) { 64 TestCAEAntiDep test = new TestCAEAntiDep(); 65 for (int i = 0; i < 20000; i++) { 66 m(test, test.o, test.o); 67 } 68 } 69 }