TestDeadBackbranchArrayAccess.java revision 11707:ad7af1afda7a 
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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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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
35package compiler.loopopts;
36
37public 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}
63