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8264958: C2 compilation fails with assert "n is later than its clone"
Reviewed-by: neliasso, thartmann
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rwestrel committed Apr 16, 2021
1 parent 1d66a15 commit 7137328006739e839e8bed8826f286883ebf3d00
Showing with 58 additions and 1 deletion.
  1. +1 −1 src/hotspot/share/opto/loopopts.cpp
  2. +57 −0 test/hotspot/jtreg/compiler/loopstripmining/OuterStripMinedLoopLoadWronglyHoisted.java
@@ -1479,7 +1479,7 @@ void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
IdealLoopTree* x_loop = get_loop(x_ctrl);
Node* x_head = x_loop->_head;
if (x_head->is_Loop() && (x_head->is_OuterStripMinedLoop() || x_head->as_Loop()->is_strip_mined())) {
if (is_dominator(n_ctrl, x_head)) {
if (is_dominator(n_ctrl, x_head) && n_ctrl != x_head) {
// Anti dependence analysis is sometimes too
// conservative: a store in the outer strip mined loop
// can prevent a load from floating out of the outer
@@ -0,0 +1,57 @@
/*
* Copyright (c) 2021, Red Hat, Inc. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/

/**
* @test
* @bug 8264958
* @summary C2 compilation fails with assert "n is later than its clone"
*
* @run main/othervm -Xbatch OuterStripMinedLoopLoadWronglyHoisted
*
*/


public class OuterStripMinedLoopLoadWronglyHoisted {
int a;
int b;
short c;

void test() {
for (int i = 0; i < 10; ++i) {
a = c;
if (i > 1) {
b = 0;
}
c = (short)(b - 7);
}
a--;
}

public static void main(String[] args) {
OuterStripMinedLoopLoadWronglyHoisted t = new OuterStripMinedLoopLoadWronglyHoisted();
for (int i = 0; i < 100_000; ++i) {
t.test();
}
}
}

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