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8240576: JVM crashes after transformation in C2 IdealLoopTree::merge_…
…many_backedges

Reviewed-by: kvn
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dongbohe authored and Fei Yang committed Mar 9, 2020
1 parent e0fec43 commit aa2be1141dde5d696db02ed701e7167b963e5e18
Showing with 62 additions and 1 deletion.
  1. +1 −1 src/hotspot/share/opto/loopnode.cpp
  2. +61 −0 test/hotspot/jtreg/compiler/loopopts/TestBeautifyLoops.java
@@ -2091,7 +2091,7 @@ bool IdealLoopTree::beautify_loops( PhaseIdealLoop *phase ) {
// If I am a shared header (multiple backedges), peel off the many
// backedges into a private merge point and use the merge point as
// the one true backedge.
if( _head->req() > 3 ) {
if (_head->req() > 3 && !_irreducible) {
// Merge the many backedges into a single backedge but leave
// the hottest backedge as separate edge for the following peel.
merge_many_backedges( phase );
@@ -0,0 +1,61 @@
/*
* Copyright (c) 2020, Huawei Technologies Co. Ltd. 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 8240576
* @summary JVM crashes after transformation in C2 IdealLoopTree::merge_many_backedges
*
* @run main/othervm -XX:-TieredCompilation -XX:-BackgroundCompilation
* compiler.loopopts.TestBeautifyLoops
*/

package compiler.loopopts;

public class TestBeautifyLoops {
private int mI = 0;
private long mJ = 0;
private float mF = 0f;

public void testMethod() {
for (int i0 = 0; i0 < 100; i0++) {
if (mF != 0) {
// do nothing
} else {
try {
mJ = Long.MAX_VALUE;
for (int i1 = 0; i1 < 101; i1++) {
for (int i2 = 0; i2 < 102; i2++) {
mI = new Integer(0x1234);
}
}
} catch (Exception ignored) {}
}
}
}

public static void main(String[] args) {
TestBeautifyLoops obj = new TestBeautifyLoops();
obj.testMethod();
}
}

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