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  * @test
  26  * @bug 8048170
  27  * @summary Following range check smearing, range check cannot be replaced by dominating identical test.
  28  *
  29  * @run main/othervm -XX:-BackgroundCompilation -XX:-UseOnStackReplacement
  30  *                   compiler.rangechecks.TestRangeCheckSmearingLoopOpts
  31  */
  32 
  33 package compiler.rangechecks;
  34 
  35 public class TestRangeCheckSmearingLoopOpts {
  36 
  37     static int dummy;
  38 
  39     static int m1(int[] array, int i) {
  40         for (;;) {
  41             for (;;) {
  42                 if (array[i] < 0) { // range check (i+0) dominates equivalent check below
  43                     break;
  44                 }
  45                 i++;
  46             }
  47 
  48             // A control flow that stops IfNode::up_one_dom()
  49             if ((i % 2)== 0) {
  50                 if ((array[i] % 2) == 0) {
  51                     dummy = i;
  52                 }
  53             }
  54 
  55             // IfNode::Ideal will rewrite some range checks if Compile::allow_range_check_smearing
  56             if (array[i-1] == 9) {    // range check (i-1) unchanged
  57                 int res = array[i-3]; // range check (i-3) unchanged
  58                 res += array[i];      // range check (i+0) unchanged
  59                 res += array[i-2];    // removed redundant range check
  60                 // the previous access might be hoisted by
  61                 // PhaseIdealLoop::split_if_with_blocks_post because
  62                 // it appears to have the same guard, but it also
  63                 // depends on the previous guards
  64                 return res;
  65             }
  66             i++;
  67         }
  68     }
  69 
  70     static public void main(String[] args) {
  71         int[] array = { 0, 1, 2, -3, 4, 5, -2, 7, 8, 9, -1 };
  72         for (int i = 0; i < 20000; i++) {
  73             m1(array, 0);
  74         }
  75         array[0] = -1;
  76         try {
  77             m1(array, 0);
  78         } catch(ArrayIndexOutOfBoundsException aioobe) {}
  79     }
  80 }