1 /*

     2  * Copyright (c) 2018, Red Hat, Inc. 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 8214862

    26  * @summary Multiple passes of PhaseRemoveUseless causes infinite loop to be optimized out

    27  *

    28  * @run main/othervm -XX:-TieredCompilation -Xcomp -XX:CompileOnly=StringConcatInfiniteLoop::test -XX:CompileCommand=dontinline,*StringBuilder::* StringConcatInfiniteLoop

    29  *

    30  */

    31 

    32 public class StringConcatInfiniteLoop {

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

    34         StringBuilder sb = new StringBuilder();

    35         test(sb, "foo", "bar", true);

    36     }

    37 

    38     private static void test(Object v, String s1, String s2, boolean flag) {

    39         if (flag) {

    40             return;

    41         }

    42         int i = 0;

    43         for (; i < 10; i++);

    44         if (i == 10) {

    45             v = null;

    46         }

    47         StringBuilder sb = new StringBuilder(s1);

    48         sb.append(s2);

    49         while (v == null);

    50     }

    51 

    52     private static class A {

    53     }

    54 }