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8287432: C2: assert(tn->in(0) != __null) failed: must have live top node

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Reviewed-by: kvn, thartmann
This commit is contained in:
Christian Hagedorn 2022-06-08 14:12:09 +00:00
parent f7791ad0ea
commit 78d371266a
2 changed files with 56 additions and 1 deletions
src/hotspot/share/opto
compile.cpp
test/hotspot/jtreg/compiler/c2
TestRemoveMemBarPrecEdge.java

2
src/hotspot/share/opto/compile.cpp

@ -3664,7 +3664,7 @@ void Compile::final_graph_reshaping_main_switch(Node* n, Final_Reshape_Counts& f
n->set_req(MemBarNode::Precedent, top());
while (wq.size() > 0) {
Node* m = wq.pop();
if (m->outcnt() == 0) {
if (m->outcnt() == 0 && m != top()) {
for (uint j = 0; j < m->req(); j++) {
Node* in = m->in(j);
if (in != NULL) {

55
test/hotspot/jtreg/compiler/c2/TestRemoveMemBarPrecEdge.java Normal file

@ -0,0 +1,55 @@
/*
* Copyright (c) 2022, 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 8287432
* @summary Test removal of precedence edge of MemBarAcquire together with other now dead input nodes which visits a
* top node. This resulted in a crash before as it disconnected top from the graph which is unexpected.
*
* @run main/othervm -Xbatch compiler.c2.TestRemoveMemBarPrecEdge
*/
package compiler.c2;
public class TestRemoveMemBarPrecEdge {
static boolean flag = false;
public static void main(String[] args) {
for (int i = 0; i < 10000; i++) {
test();
flag = !flag;
}
}
public static void test() {
// currentThread() is intrinsified and C2 emits a special AddP node with a base that is top.
Thread t = Thread.currentThread();
// getName() returns the volatile _name field. The method is inlined and we just emit a LoadN + DecodeN which
// is a precedence edge input into both MemBarAcquire nodes below for the volatile field _name.
if (flag) {
t.getName();
} else {
t.getName();
}
}
}