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  *

    29  * @run main/othervm -Xbatch compiler.c2.Test6843752

    30  */

    31 

    32 package compiler.c2;

    33 

    34 public class Test6843752 {

    35 

    36     Item list;

    37 

    38     static class Item {

    39         public Item    next;

    40         public Item    prev;

    41         public boolean remove;

    42 

    43         Item(boolean r) { remove = r; }

    44     }

    45 

    46     private void linkIn(Item item) {

    47         Item head = list;

    48         if (head == null) {

    49             item.next = item;

    50             item.prev = item;

    51             list = item;

    52         } else {

    53             item.next = head;

    54             item.prev = head.prev;

    55             head.prev.next = item;

    56             head.prev = item;

    57         }

    58     }

    59 

    60     private void linkOut(Item item) {

    61         Item head = list;

    62         if (item.next == item) {

    63             list = null;

    64         } else {

    65             item.prev.next = item.next;

    66             item.next.prev = item.prev;

    67             if (head == item) {

    68                 list = item.next;

    69             }

    70         }

    71         item.next = null;

    72         item.prev = null; // this is the null pointer we are seeing

    73     }

    74 

    75     private void removeItems(int numItems) {

    76         Item item = list;

    77         if (item == null) {

    78             return;

    79         }

    80         Item last = item.prev;

    81         boolean done = false;

    82         while (!done && numItems > 1) {

    83             // the original code "done = (item == last);" triggered an infinite loop

    84             // and was changed slightly in order to produce an exception instead.

    85             done = (item.next == last.next);

    86             item = item.next;

    87             if (item.prev.remove) {

    88                 linkOut(item.prev);

    89             }

    90         }

    91     }

    92 

    93     public void perform(int numItems) {

    94         for (int i = 0; i < numItems; i++) {

    95             linkIn(new Item(i == 0));

    96         }

    97         removeItems(numItems);

    98         list = null;

    99     }

   100 

   101     static public void main(String[] args) {

   102         int caseCnt = 0;

   103         Test6843752 bj = new Test6843752();

   104         try {

   105             for (; caseCnt < 500000;) {

   106                 int numItems = (++caseCnt % 2);

   107                 if ((caseCnt % 64) == 0) {

   108                     numItems = 5;

   109                 }

   110                 bj.perform(numItems);

   111                 if ((caseCnt % 100000) == 0) {

   112                     System.out.println("successfully performed " + caseCnt + " cases");

   113                 }

   114             }

   115         } catch (Exception e) {

   116             System.out.println("ERROR: crashed during case " + caseCnt);

   117             e.printStackTrace(System.out);

   118             System.exit(97);

   119         }

   120     }

   121 }

   122