1/* 2 * Copyright (c) 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 8139771 27 * @summary Eliminating CastPP nodes at Phis when they all come from a unique input may cause crash 28 * @requires vm.gc=="Serial" | vm.gc=="Parallel" 29 * 30 * @run main/othervm -XX:-BackgroundCompilation -XX:-UseOnStackReplacement 31 * -XX:+UnlockDiagnosticVMOptions -XX:+IgnoreUnrecognizedVMOptions -XX:+StressGCM 32 * compiler.controldependency.TestEliminatedCastPPAtPhi 33 * 34 */ 35 36package compiler.controldependency; 37 38public class TestEliminatedCastPPAtPhi { 39 40 static TestEliminatedCastPPAtPhi saved; 41 static TestEliminatedCastPPAtPhi saved_not_null; 42 43 int f; 44 45 static int test(TestEliminatedCastPPAtPhi obj, int[] array, boolean flag) { 46 int ret = array[0] + array[20]; 47 saved = obj; 48 if (obj == null) { 49 return ret; 50 } 51 saved_not_null = obj; 52 53 // empty loop to be optimized out. Delays range check smearing 54 // for the array access below until the if diamond is 55 // optimized out 56 int i = 0; 57 for (; i < 10; i++); 58 59 ret += array[i]; 60 61 TestEliminatedCastPPAtPhi res; 62 if (flag) { 63 // load is optimized out and res is obj here 64 res = saved; 65 } else { 66 // load is optimized out and res is non null CastPP of res here 67 res = saved_not_null; 68 } 69 // null check + CastPP here for res field load below 70 71 // 1) null check is pushed in the branches of the if above by 72 // split through phi because res is non null in the second 73 // branch and the null check can be optimized out in that 74 // branch. The Castpp stays here. 75 76 // 2) null check in the first branch is also optimized out 77 // because a dominating null check is found (the explicit null 78 // check at the beggining of the test) 79 80 // 3) the Phi for the if above merges a CastPP'ed value and 81 // the same value so it's optimized out and replaced by the 82 // uncasted value: obj 83 84 // 4) the if above has 2 empty branches so it's optimized 85 // out. The control of the CastPP that is still here is now 86 // the success branch of the range check for the array access 87 // above 88 89 // 5) the loop above is optimized out, i = 10, the range check 90 // for the array access above is optimized out and all its 91 // uses are replaced by the range check for the array accesses 92 // at the beginning of the method. The castPP here is one of 93 // the uses and so its control is now the range check at the 94 // beginning of the method: the control of the CastPP bypasses 95 // the explicit null check 96 97 return ret + res.f; 98 } 99 100 static public void main(String[] args) { 101 int[] array = new int[100]; 102 TestEliminatedCastPPAtPhi obj = new TestEliminatedCastPPAtPhi(); 103 for (int i = 0; i < 20000; i++) { 104 test(obj, array, (i%2) == 0); 105 } 106 test(null, array, true); 107 } 108 109} 110