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8244407: JVM crashes after transformation in C2 IdealLoopTree::split_…
…fall_in

Reviewed-by: thartmann, kvn
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Yong Zhou authored and Fei Yang committed May 12, 2020
1 parent cdf8cc5 commit dc54da232dd74dcfe1ee38038e080e5f7be42eb9
Showing 2 changed files with 92 additions and 3 deletions.
@@ -1,5 +1,5 @@
/*
* Copyright (c) 1998, 2019, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1998, 2020, Oracle and/or its affiliates. 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
@@ -2098,10 +2098,18 @@ 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 && !_irreducible) {
if (_head->req() > 3) {
// Merge the many backedges into a single backedge but leave
// the hottest backedge as separate edge for the following peel.
merge_many_backedges( phase );
if (!_irreducible) {
merge_many_backedges( phase );
}

// When recursively beautify my children, split_fall_in can change
// loop tree structure when I am an irreducible loop. Then the head
// of my children has a req() not bigger than 3. Here we need to set
// result to true to catch that case in order to tell the caller to
// rebuild loop tree. See issue JDK-8244407 for details.
result = true;
}

@@ -0,0 +1,81 @@
/*
* 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 8244407
* @summary JVM crashes after transformation in C2 IdealLoopTree::split_fall_in
*
* @run main/othervm -Xcomp -XX:-BackgroundCompilation
* -XX:CompileCommand=compileonly,compiler.loopopts.TestBeautifyLoops_2::testMethod
* compiler.loopopts.TestBeautifyLoops_2
*/

package compiler.loopopts;

public class TestBeautifyLoops_2 {

private class X {
public int x() {
return -1;
}
}

private int mI = 0;
private float mF = 0;
private boolean mZ = false;
private X mX = new X();
private long[] mArray = new long[331];

private void testMethod() {
double d = 0;

for (int i = 0; i < 331; i++) {
if (mZ) {
continue;
}

try {
for (int j = mArray.length - 1; j >= 0; j--) {
for (int k = 0; k < 331; k++) {
d += ((double) new Double(d));
switch (267) {
case 256:
default: {
mF += (mX.x());
break;
}
}
}
}
} catch (Exception ignore) {
}
}
}

public static void main(String[] args) {
TestBeautifyLoops_2 obj = new TestBeautifyLoops_2();
obj.testMethod();
}

}

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