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 26 * @summary Logic that moves a null check in the expanded barrier may cause a memory access that doesn't depend on the barrier to bypass the null check 27 * @requires vm.flavor == "server" 28 * @run main/othervm -XX:-BackgroundCompilation -XX:-UseOnStackReplacement -XX:-TieredCompilation 29 * -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC 30 * -XX:+StressGCM -XX:+StressLCM TestExpandedWBLostNullCheckDep 31 */ 32 33 public class TestExpandedWBLostNullCheckDep { 34 35 static void test(int i, int[] arr) { 36 // arr.length depends on a null check for arr 37 if (i < 0 || i >= arr.length) { 38 } 39 // The write barrier here also depends on the null check. The 40 // null check is moved in the barrier to enable implicit null 41 // checks. The null check must not be moved arr.length 42 arr[i] = 0x42; 43 } 44 45 static public void main(String[] args) { 46 int[] int_arr = new int[10]; 47 for (int i = 0; i < 20000; i++) { 48 test(0, int_arr); 49 } 50 try { 51 test(0, null); 52 } catch (NullPointerException npe) {} 53 } 54 }