1 /*

     2  * Copyright (c) 2019, 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 8230062

    27  * @summary The IR of this test contains a reduction chain which corresponds to a pack in which the 2nd last element has a usage outside of the optimized loop.

    28  *

    29  * @run main/othervm -Xbatch -XX:CompileCommand=compileonly,compiler.loopopts.superword.SuperWordIntermediateUse::test

    30  *      compiler.loopopts.superword.SuperWordIntermediateUse

    31  */

    32 

    33 package compiler.loopopts.superword;

    34 

    35 public class SuperWordIntermediateUse {

    36 

    37     private int iFld;

    38     private int[] iArr = new int[1024];

    39 

    40     public void test() {

    41         int local = 4;

    42 

    43         /**

    44          * Before unrolling this loop:

    45          * iFld:   AddI 1 = -85 + Phi 1

    46          * local:  MulI 2 = Phi 1 * LoadI 3

    47          *

    48          * This loop is now unrolled. 'local' is a reduction. The loop is first copied:

    49          * iFldCopy:  AddI C1 = -85 + Phi C1

    50          * localCopy: MulI C2 = Phi C1 * LoadI C3

    51          *

    52          * iFld:   AddI 1 = -85 + Phi 1

    53          * local:  MulI 2 = Phi 1 * LoadI 3

    54          *

    55          * Then, the unnecessary nodes like phis are removed from the original loop by igvn:

    56          * (iFldCopy:  AddI C1 = -85 + Phi C1) field store optimized away

    57          * localCopy: MulI C2 = Phi C1 * LoadI C3

    58          *

    59          * iFld:   AddI 1 = -85 + MulI C2

    60          * local:  MulI 2 = MulI C2 * LoadI 3 -> Input into Phi C1

    61          *

    62          *  As a result AddI 1 has an input from MulI C2 which isn't the last operation in the reduction chain

    63          *  Phi C1 -> MulI C2 -> MulI 2 -> Phi C1 and therefore not the last element in a pack.

    64          *  Additionally, AddI 1 does not belong to the loop being optimized: The store node for iFld is put outside of the loop being optimized.

    65          *  This triggers the assertion bug when unrolled at least 4 times which creates packs of at least size 4.

    66          */

    67         for (int i = 0; i < 1024; i++) {

    68             iFld = -85;

    69             iFld = iFld + local;

    70             local = local * iArr[i];

    71             iArr[i] = 3; // Just used to trigger SuperWord optimization

    72         }

    73     }

    74 

    75     public static void main(String[] strArr) {

    76         SuperWordIntermediateUse instance = new SuperWordIntermediateUse();

    77         for (int i = 0; i < 1000; i++) {

    78             instance.test();

    79         }

    80     }

    81 }