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 }