1 /*
   2  * Copyright (c) 2016, 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 8078262
  27  * @summary Tests correct dominator information after loop peeling.
  28  *
  29  * @run main/othervm -Xcomp
  30  *      -XX:CompileCommand=compileonly,compiler.loopopts.TestLoopPeeling::test*
  31  *      compiler.loopopts.TestLoopPeeling
  32  */
  33 
  34 package compiler.loopopts;
  35 
  36 public class TestLoopPeeling {
  37 
  38     public int[] array = new int[100];
  39 
  40     public static void main(String args[]) {
  41         TestLoopPeeling test = new TestLoopPeeling();
  42         try {
  43             test.testArrayAccess(0, 1);
  44             test.testArrayAllocation(0, 1);
  45         } catch (Exception e) {
  46             // Ignore exceptions
  47         }
  48     }
  49 
  50     public void testArrayAccess(int index, int inc) {
  51         int storeIndex = -1;
  52 
  53         for (; index < 10; index += inc) {
  54             // This loop invariant check triggers loop peeling because it can
  55             // be moved out of the loop (see 'IdealLoopTree::policy_peeling').
  56             if (inc == 42) return;
  57 
  58             // This loop variant usage of LShiftL( ConvI2L( Phi(storeIndex) ) )
  59             // prevents the split if optimization that would otherwise clone the
  60             // LShiftL and ConvI2L nodes and assign them to their corresponding array
  61             // address computation (see 'PhaseIdealLoop::split_if_with_blocks_post').
  62             if (storeIndex > 0 && array[storeIndex] == 42) return;
  63 
  64             if (index == 42) {
  65                 // This store and the corresponding range check are moved out of the
  66                 // loop and both used after old loop and the peeled iteration exit.
  67                 // For the peeled iteration, storeIndex is always -1 and the ConvI2L
  68                 // is replaced by TOP. However, the range check is not folded because
  69                 // we don't do the split if optimization in PhaseIdealLoop2.
  70                 // As a result, we have a (dead) control path from the peeled iteration
  71                 // to the StoreI but the data path is removed.
  72                 array[storeIndex] = 1;
  73                 return;
  74             }
  75 
  76             storeIndex++;
  77         }
  78     }
  79 
  80     public byte[] testArrayAllocation(int index, int inc) {
  81         int allocationCount = -1;
  82         byte[] result;
  83 
  84         for (; index < 10; index += inc) {
  85             // This loop invariant check triggers loop peeling because it can
  86             // be moved out of the loop (see 'IdealLoopTree::policy_peeling').
  87             if (inc == 42) return null;
  88 
  89             if (index == 42) {
  90                 // This allocation and the corresponding size check are moved out of the
  91                 // loop and both used after old loop and the peeled iteration exit.
  92                 // For the peeled iteration, allocationCount is always -1 and the ConvI2L
  93                 // is replaced by TOP. However, the size check is not folded because
  94                 // we don't do the split if optimization in PhaseIdealLoop2.
  95                 // As a result, we have a (dead) control path from the peeled iteration
  96                 // to the allocation but the data path is removed.
  97                 result = new byte[allocationCount];
  98                 return result;
  99             }
 100 
 101             allocationCount++;
 102         }
 103         return null;
 104     }
 105 }
 106