1 /* 2 * Copyright (c) 2016, 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 TestWriteBarrierClearControl 26 * @summary Clearing control during final graph reshape causes memory barrier to loose dependency on null check 27 * @key gc 28 * @requires vm.gc.Shenandoah 29 * @run main/othervm -XX:-BackgroundCompilation -XX:-UseOnStackReplacement -XX:-TieredCompilation 30 * -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC 31 * -XX:+UnlockDiagnosticVMOptions -XX:+StressLCM -XX:+StressGCM 32 * TestWriteBarrierClearControl 33 * 34 */ 35 public class TestWriteBarrierClearControl { 36 37 int f; 38 39 static void test1(TestWriteBarrierClearControl o) { 40 o.f = 0x42; 41 } 42 43 static TestWriteBarrierClearControl fo = new TestWriteBarrierClearControl(); 44 45 static void test2() { 46 TestWriteBarrierClearControl o = fo; 47 o.f = 0x42; 48 } 49 50 static public void main(String[] args) { 51 TestWriteBarrierClearControl o = new TestWriteBarrierClearControl(); 52 for (int i = 0; i < 20000; i++) { 53 test1(o); 54 test2(); 55 } 56 try { 57 test1(null); 58 } catch (NullPointerException npe) {} 59 fo = null; 60 try { 61 test2(); 62 } catch (NullPointerException npe) {} 63 } 64 }