1 /* 2 * Copyright (c) 2009, 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 6843752 27 * @summary missing code for an anti-dependent Phi in GCM 28 * @run main/othervm -Xbatch Test 29 */ 30 31 public class Test { 32 33 Item list; 34 35 static class Item { 36 public Item next; 37 public Item prev; 38 public boolean remove; 39 40 Item(boolean r) { remove = r; } 41 } 42 43 private void linkIn(Item item) { 44 Item head = list; 45 if (head == null) { 46 item.next = item; 47 item.prev = item; 48 list = item; 49 } else { 50 item.next = head; 51 item.prev = head.prev; 52 head.prev.next = item; 53 head.prev = item; 54 } 55 } 56 57 private void linkOut(Item item) { 58 Item head = list; 59 if (item.next == item) { 60 list = null; 61 } else { 62 item.prev.next = item.next; 63 item.next.prev = item.prev; 64 if (head == item) { 65 list = item.next; 66 } 67 } 68 item.next = null; 69 item.prev = null; // this is the null pointer we are seeing 70 } 71 72 private void removeItems(int numItems) { 73 Item item = list; 74 if (item == null) { 75 return; 76 } 77 Item last = item.prev; 78 boolean done = false; 79 while (!done && numItems > 1) { 80 // the original code "done = (item == last);" triggered an infinite loop 81 // and was changed slightly in order to produce an exception instead. 82 done = (item.next == last.next); 83 item = item.next; 84 if (item.prev.remove) { 85 linkOut(item.prev); 86 } 87 } 88 } 89 90 public void perform(int numItems) { 91 for (int i = 0; i < numItems; i++) { 92 linkIn(new Item(i == 0)); 93 } 94 removeItems(numItems); 95 list = null; 96 } 97 98 static public void main(String[] args) { 99 int caseCnt = 0; 100 Test bj = new Test(); 101 try { 102 for (; caseCnt < 500000;) { 103 int numItems = (++caseCnt % 2); 104 if ((caseCnt % 64) == 0) { 105 numItems = 5; 106 } 107 bj.perform(numItems); 108 if ((caseCnt % 100000) == 0) { 109 System.out.println("successfully performed " + caseCnt + " cases"); 110 } 111 } 112 } catch (Exception e) { 113 System.out.println("ERROR: crashed during case " + caseCnt); 114 e.printStackTrace(System.out); 115 System.exit(97); 116 } 117 } 118 } 119