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8231988: Unexpected test result caused by C2 IdealLoopTree::do_remove_empty_loop

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Duplicate cmp node in empty loop if it has other users

Co-authored-by: Tuo Xie <xietuo@huawei.com>
Reviewed-by: neliasso, thartmann
This commit is contained in:
Huang Wang 2019-10-11 16:52:18 +08:00 committed by Fei Yang
parent 5b7d56fdb9
commit 4fb2bb554d
2 changed files with 62 additions and 0 deletions
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7
src/hotspot/share/opto/loopTransform.cpp
View File

@ -3129,6 +3129,13 @@ bool IdealLoopTree::do_remove_empty_loop(PhaseIdealLoop *phase) {
// We also need to replace the original limit to collapse loop exit.
Node* cmp = cl->loopexit()->cmp_node();
assert(cl->limit() == cmp->in(2), "sanity");
// Duplicate cmp node if it has other users
if (cmp->outcnt() > 1) {
cmp = cmp->clone();
cmp = phase->_igvn.register_new_node_with_optimizer(cmp);
BoolNode *bol = cl->loopexit()->in(CountedLoopEndNode::TestValue)->as_Bool();
phase->_igvn.replace_input_of(bol, 1, cmp); // put bol on worklist
}
phase->_igvn._worklist.push(cmp->in(2)); // put limit on worklist
phase->_igvn.replace_input_of(cmp, 2, exact_limit); // put cmp on worklist
}

55
test/hotspot/jtreg/compiler/loopopts/TestRemoveEmptyLoop.java Normal file
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@ -0,0 +1,55 @@
/*
* Copyright (c) 2019, 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 8231988
* @summary Unexpected test result caused by C2 IdealLoopTree::do_remove_empty_loop
*
* @run main/othervm -XX:-TieredCompilation -XX:-BackgroundCompilation
* compiler.loopopts.TestRemoveEmptyLoop
*/
package compiler.loopopts;
public class TestRemoveEmptyLoop {
public void test() {
int i = 34;
for (; i > 0; i -= 11);
if (i < 0) {
// do nothing
} else {
throw new RuntimeException("Test failed.");
}
}
public static void main(String[] args) {
TestRemoveEmptyLoop _instance = new TestRemoveEmptyLoop();
for (int i = 0; i < 50000; i++) {
_instance.test();
}
System.out.println("Test passed.");
}
}