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8252292: 8240795 may cause anti-dependence to be missed
Reviewed-by: thartmann, kvn
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rwestrel committed Aug 24, 2020
1 parent e6f39e1 commit e292f042646ee87354f58551eba82635408c584b
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Showing 2 changed files with 88 additions and 10 deletions.
@@ -4209,17 +4209,26 @@ Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) {
}
} else {
Node *sctrl = has_ctrl(s) ? get_ctrl(s) : s->in(0);
const TypePtr* adr_type = s->adr_type();
if (s->is_ArrayCopy()) {
// Copy to known instance needs destination type to test for aliasing
const TypePtr* dest_type = s->as_ArrayCopy()->_dest_type;
if (dest_type != TypeOopPtr::BOTTOM) {
adr_type = dest_type;
}
}
assert(sctrl != NULL || !s->is_reachable_from_root(), "must have control");
if (sctrl != NULL && !sctrl->is_top() && C->can_alias(adr_type, load_alias_idx) && is_dominator(early, sctrl)) {
LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n);
if (sctrl != NULL && !sctrl->is_top() && is_dominator(early, sctrl)) {
const TypePtr* adr_type = s->adr_type();
if (s->is_ArrayCopy()) {
// Copy to known instance needs destination type to test for aliasing
const TypePtr* dest_type = s->as_ArrayCopy()->_dest_type;
if (dest_type != TypeOopPtr::BOTTOM) {
adr_type = dest_type;
}
}
if (C->can_alias(adr_type, load_alias_idx)) {
LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n);
} else if (s->is_CFG()) {
for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) {
Node* s1 = s->fast_out(i);
if (_igvn.type(s1) == Type::MEMORY) {
worklist.push(s1);
}
}
}
}
}
}
@@ -0,0 +1,69 @@
/*
* Copyright (c) 2020, 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 8252292
* @summary 8240795 may cause anti-dependency to be missed
* @requires vm.gc.Parallel
*
* @run main/othervm -XX:-BackgroundCompilation -XX:+UseParallelGC TestMissingAntiDependency
*
*/

public class TestMissingAntiDependency {
public static void main(String[] args) {
int[] src = new int[10];
for (int i = 0; i < 20_000; i++) {
test(src, true, true, 10);
test(src, true, false, 10);
test(src, false, false, 10);
}
src[9] = 42;
final int v = test(src, true, true, 1);
if (v != 42) {
throw new RuntimeException("Incorrect return value " + v);
}
}

private static int test(int[] src, boolean flag1, boolean flag2, int stop) {
int v = 0;
int j = 1;
for (; j < 10; j++) {
for (int i = 0; i < 2; i++) {

}
}
int[] dst = new int[10];
for (int i = 0; i < stop; i ++) {
if (flag1) {
System.arraycopy(src, 0, dst, 0, j);
v = dst[9];
if (flag2) {
src[9] = 0x42;
}
}
}
return v;
}
}

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