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8337660: C2: basic blocks with only BoxLock nodes are wrongly treated as empty

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Co-authored-by: Emanuel Peter <epeter@openjdk.org>
Reviewed-by: qamai, thartmann, kvn
This commit is contained in:
Roberto Castañeda Lozano 2024-11-26 08:51:34 +00:00
parent 4e68d665be
commit 0105203575
2 changed files with 93 additions and 5 deletions
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11
src/hotspot/share/opto/block.cpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1997, 2024, 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
@ -181,10 +181,11 @@ int Block::is_Empty() const {
return success_result;
}
// Ideal nodes are allowable in empty blocks: skip them Only MachNodes
// turn directly into code, because only MachNodes have non-trivial
// emit() functions.
while ((end_idx > 0) && !get_node(end_idx)->is_Mach()) {
// Ideal nodes (except BoxLock) are allowable in empty blocks: skip them. Only
// Mach and BoxLock nodes turn directly into code via emit().
while ((end_idx > 0) &&
!get_node(end_idx)->is_Mach() &&
!get_node(end_idx)->is_BoxLock()) {
end_idx--;
}

87
test/hotspot/jtreg/compiler/locks/TestSynchronizeWithEmptyBlock.java Normal file
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@ -0,0 +1,87 @@
/*
* Copyright (c) 2024, 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
* 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 8337660
* @summary Test that C2 does not remove blocks with BoxLock nodes that are
* otherwise empty.
* @run main/othervm -Xbatch -XX:LockingMode=1
* -XX:CompileOnly=compiler.locks.TestSynchronizeWithEmptyBlock::*
* compiler.locks.TestSynchronizeWithEmptyBlock
* @run main/othervm -Xbatch
* -XX:CompileOnly=compiler.locks.TestSynchronizeWithEmptyBlock::*
* compiler.locks.TestSynchronizeWithEmptyBlock
*/
package compiler.locks;
public class TestSynchronizeWithEmptyBlock {
static int c;
static final Object obj = new Object();
static void test1() {
synchronized (TestSynchronizeWithEmptyBlock.class) {
int i = 0;
while (i < 1000) {
i++;
if (i < 5);
}
}
synchronized (TestSynchronizeWithEmptyBlock.class) {
int i = 0;
do {
i++;
if (i < 4) {
boolean p = true;
int j = 0;
do {
j++;
if (p) {
c++;
}
} while (j < 100);
}
} while (i < 1000);
}
}
static void test2() {
synchronized (obj) {
for (long i = 0; i < 1_000_000_000_000L; i+=6_500_000_000L) {}
}
synchronized (obj) {
for (long i = 0; i < 1_000_000_000_000L; i+=6_500_000_000L) {}
}
}
public static void main(String[] args) {
for (int i = 0; i < 10_000; i++) {
test1();
}
for (int i = 0; i < 10_000; i++) {
test2();
}
}
}