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8313262: C2: Sinking node may cause required cast to be dropped
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Backport-of: 1cee3b9fd9720e7938029a6992460b9053e65e57
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shipilev committed Aug 30, 2023
1 parent 42aec91 commit 511224a
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Showing 2 changed files with 69 additions and 1 deletion.
2 changes: 1 addition & 1 deletion src/hotspot/share/opto/loopopts.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -1642,7 +1642,7 @@ void PhaseIdealLoop::try_sink_out_of_loop(Node* n) {
// Find control for 'x' next to use but not inside inner loops.
x_ctrl = place_outside_loop(x_ctrl, n_loop);
// Replace all uses
if (u->is_ConstraintCast() && u->bottom_type()->higher_equal(_igvn.type(n)) && u->in(0) == x_ctrl) {
if (u->is_ConstraintCast() && _igvn.type(n)->higher_equal(u->bottom_type()) && u->in(0) == x_ctrl) {
// If we're sinking a chain of data nodes, we might have inserted a cast to pin the use which is not necessary
// anymore now that we're going to pin n as well
_igvn.replace_node(u, x);
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Original file line number Diff line number Diff line change
@@ -0,0 +1,68 @@
/*
* Copyright (c) 2023, 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 8313262
* @summary Sinking node may cause required cast to be dropped
* @requires vm.gc.Shenandoah
* @run main/othervm -XX:-BackgroundCompilation -XX:+UseShenandoahGC TestSinkingNodeDropsNotNullCast
*/

import java.util.Arrays;

public class TestSinkingNodeDropsNotNullCast {
public static void main(String[] args) {
Object[] array1 = new Object[100];
Object[] array2 = new Object[100];
Arrays.fill(array2, new Object());
for (int i = 0; i < 20_000; i++) {
test(array1);
test(array1);
test(array2);
}
}

private static Object test(Object[] array) {
Object o;
int i = 1;
do {
synchronized (new Object()) {
}
o = array[i];
if (o != null) {
if (o instanceof A) {
return ((A) o).field;
} else {
return o;
}
}
i++;
} while (i < 100);
return o;
}

private static class A {
Object field;
}
}

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