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 /** 26 * @test 27 * @bug 8139771 28 * @summary Eliminating CastPP nodes at Phis when they all come from a unique input may cause crash 29 * @requires vm.gc=="Serial" | vm.gc=="Parallel" 30 * @run main/othervm -XX:-BackgroundCompilation -XX:-UseOnStackReplacement -XX:+IgnoreUnrecognizedVMOptions -XX:+StressGCM TestEliminatedCastPPAtPhi 31 * 32 */ 33 34 public class TestEliminatedCastPPAtPhi { 35 36 static TestEliminatedCastPPAtPhi saved; 37 static TestEliminatedCastPPAtPhi saved_not_null; 38 39 int f; 40 41 static int test(TestEliminatedCastPPAtPhi obj, int[] array, boolean flag) { 42 int ret = array[0] + array[20]; 43 saved = obj; 44 if (obj == null) { 45 return ret; 46 } 47 saved_not_null = obj; 48 49 // empty loop to be optimized out. Delays range check smearing 50 // for the array access below until the if diamond is 51 // optimized out 52 int i = 0; 53 for (; i < 10; i++); 54 55 ret += array[i]; 56 57 TestEliminatedCastPPAtPhi res; 58 if (flag) { 59 // load is optimized out and res is obj here 60 res = saved; 61 } else { 62 // load is optimized out and res is non null CastPP of res here 63 res = saved_not_null; 64 } 65 // null check + CastPP here for res field load below 66 67 // 1) null check is pushed in the branches of the if above by 68 // split through phi because res is non null in the second 69 // branch and the null check can be optimized out in that 70 // branch. The Castpp stays here. 71 72 // 2) null check in the first branch is also optimized out 73 // because a dominating null check is found (the explicit null 74 // check at the beggining of the test) 75 76 // 3) the Phi for the if above merges a CastPP'ed value and 77 // the same value so it's optimized out and replaced by the 78 // uncasted value: obj 79 80 // 4) the if above has 2 empty branches so it's optimized 81 // out. The control of the CastPP that is still here is now 82 // the success branch of the range check for the array access 83 // above 84 85 // 5) the loop above is optimized out, i = 10, the range check 86 // for the array access above is optimized out and all its 87 // uses are replaced by the range check for the array accesses 88 // at the beginning of the method. The castPP here is one of 89 // the uses and so its control is now the range check at the 90 // beginning of the method: the control of the CastPP bypasses 91 // the explicit null check 92 93 return ret + res.f; 94 } 95 96 static public void main(String[] args) { 97 int[] array = new int[100]; 98 TestEliminatedCastPPAtPhi obj = new TestEliminatedCastPPAtPhi(); 99 for (int i = 0; i < 20000; i++) { 100 test(obj, array, (i%2) == 0); 101 } 102 test(null, array, true); 103 } 104 105 }