1 /*
   2  * Copyright (c) 2014, 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 8054478
  28  * @summary dead backbranch in main loop results in erroneous array access
  29  *
  30  * @run main/othervm -Xcomp
  31  *      -XX:CompileCommand=compileonly,compiler.loopopts.TestDeadBackbranchArrayAccess::*
  32  *      compiler.loopopts.TestDeadBackbranchArrayAccess
  33  */
  34 
  35 package compiler.loopopts;
  36 
  37 public class TestDeadBackbranchArrayAccess {
  38     static char[] pattern0 = {0};
  39     static char[] pattern1 = {1};
  40 
  41     static void test(char[] array) {
  42         if (pattern1 == null) return;
  43 
  44         int i = 0;
  45         int pos = 0;
  46         char c = array[pos];
  47 
  48         while (i >= 0 && (c == pattern0[i] || c == pattern1[i])) {
  49             i--;
  50             pos--;
  51             if (pos != -1) {
  52                 c = array[pos];
  53             }
  54         }
  55     }
  56 
  57     public static void main(String[] args) {
  58         for (int i = 0; i < 1000000; i++) {
  59             test(new char[1]);
  60         }
  61     }
  62 }