1 /* 2 * Copyright (c) 2020, 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 * @bug 8237007 27 * @summary Shenandoah: assert(_base == Tuple) failure during C2 compilation 28 * @key gc 29 * @requires vm.flavor == "server" 30 * @requires vm.gc.Shenandoah & !vm.graal.enabled 31 * 32 * @run main/othervm -XX:+UnlockExperimentalVMOptions -XX:-BackgroundCompilation -XX:+UseShenandoahGC LRBRightAfterMemBar 33 * 34 */ 35 36 public class LRBRightAfterMemBar { 37 private static Object field1; 38 private static Object field2; 39 static volatile int barrier; 40 41 public static void main(String[] args) { 42 for (int i = 0; i < 20_000; i++) { 43 test(true, true, new Object()); 44 test(false, false, new Object()); 45 } 46 } 47 48 private static Object test(boolean flag, boolean flag2, Object o2) { 49 for (int i = 0; i < 10; i++) { 50 barrier = 0x42; // Membar 51 if (o2 == null) { // hoisted out of loop 52 } 53 // The following line is converted to a CMove with an out 54 // of loop control once the null check above is 55 // hoisted. The CMove is pinned right after the membar and 56 // assigned the membar as control. 57 Object o = flag ? field1 : field2; 58 if (flag2) { 59 return o; 60 } 61 } 62 63 return null; 64 } 65 }