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 * @key stress randomness 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 * 31 * @run main/othervm -XX:-BackgroundCompilation -XX:-UseOnStackReplacement 32 * -XX:+UnlockDiagnosticVMOptions -XX:+IgnoreUnrecognizedVMOptions -XX:+StressGCM 33 * compiler.controldependency.TestEliminatedCastPPAtPhi 34 * 35 */ 36 37 package compiler.controldependency; 38 39 public class TestEliminatedCastPPAtPhi { 40 41 static TestEliminatedCastPPAtPhi saved; 42 static TestEliminatedCastPPAtPhi saved_not_null; 43 44 int f; 45 test(TestEliminatedCastPPAtPhi obj, int[] array, boolean flag)46 static int test(TestEliminatedCastPPAtPhi obj, int[] array, boolean flag) { 47 int ret = array[0] + array[20]; 48 saved = obj; 49 if (obj == null) { 50 return ret; 51 } 52 saved_not_null = obj; 53 54 // empty loop to be optimized out. Delays range check smearing 55 // for the array access below until the if diamond is 56 // optimized out 57 int i = 0; 58 for (; i < 10; i++); 59 60 ret += array[i]; 61 62 TestEliminatedCastPPAtPhi res; 63 if (flag) { 64 // load is optimized out and res is obj here 65 res = saved; 66 } else { 67 // load is optimized out and res is non null CastPP of res here 68 res = saved_not_null; 69 } 70 // null check + CastPP here for res field load below 71 72 // 1) null check is pushed in the branches of the if above by 73 // split through phi because res is non null in the second 74 // branch and the null check can be optimized out in that 75 // branch. The Castpp stays here. 76 77 // 2) null check in the first branch is also optimized out 78 // because a dominating null check is found (the explicit null 79 // check at the beggining of the test) 80 81 // 3) the Phi for the if above merges a CastPP'ed value and 82 // the same value so it's optimized out and replaced by the 83 // uncasted value: obj 84 85 // 4) the if above has 2 empty branches so it's optimized 86 // out. The control of the CastPP that is still here is now 87 // the success branch of the range check for the array access 88 // above 89 90 // 5) the loop above is optimized out, i = 10, the range check 91 // for the array access above is optimized out and all its 92 // uses are replaced by the range check for the array accesses 93 // at the beginning of the method. The castPP here is one of 94 // the uses and so its control is now the range check at the 95 // beginning of the method: the control of the CastPP bypasses 96 // the explicit null check 97 98 return ret + res.f; 99 } 100 main(String[] args)101 static public void main(String[] args) { 102 int[] array = new int[100]; 103 TestEliminatedCastPPAtPhi obj = new TestEliminatedCastPPAtPhi(); 104 for (int i = 0; i < 20000; i++) { 105 test(obj, array, (i%2) == 0); 106 } 107 test(null, array, true); 108 } 109 110 } 111