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8308892: Bad graph detected in build_loop_late after JDK-8305635
Reviewed-by: rcastanedalo, roland, thartmann
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chhagedorn committed Jun 2, 2023
1 parent dc8bc6c commit 7dbdad5
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Showing 2 changed files with 97 additions and 2 deletions.
10 changes: 8 additions & 2 deletions src/hotspot/share/opto/loopPredicate.cpp
Expand Up @@ -1835,6 +1835,9 @@ ParsePredicateNode* ParsePredicates::get_parse_predicate_or_null(Node* parse_pre
}

// Initialize the Parse Predicate projection field that matches the kind of the parent of `parse_predicate_proj`.
// Only initialize if Parse Predicate projection itself or any of the Parse Predicate projections coming further up
// in the graph are not already initialized (this would be a sign of repeated Parse Predicates which are not cleaned up,
// yet).
bool ParsePredicates::assign_predicate_proj(ParsePredicateSuccessProj* parse_predicate_proj) {
ParsePredicateNode* parse_predicate = get_parse_predicate_or_null(parse_predicate_proj);
assert(parse_predicate != nullptr, "must exist");
Expand All @@ -1847,13 +1850,16 @@ bool ParsePredicates::assign_predicate_proj(ParsePredicateSuccessProj* parse_pre
_loop_predicate_proj = parse_predicate_proj;
break;
case Deoptimization::DeoptReason::Reason_profile_predicate:
if (_profiled_loop_predicate_proj != nullptr) {
if (_profiled_loop_predicate_proj != nullptr ||
_loop_predicate_proj != nullptr) {
return false;
}
_profiled_loop_predicate_proj = parse_predicate_proj;
break;
case Deoptimization::DeoptReason::Reason_loop_limit_check:
if (_loop_limit_check_predicate_proj != nullptr) {
if (_loop_limit_check_predicate_proj != nullptr ||
_loop_predicate_proj != nullptr ||
_profiled_loop_predicate_proj != nullptr) {
return false;
}
_loop_limit_check_predicate_proj = parse_predicate_proj;
Expand Down
@@ -0,0 +1,89 @@
/*
* Copyright (c) 2023, 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 8308892
* @summary Test that Parse Predicates immediately following other Parse Predicates
are cleaned up properly.
* @run main/othervm -Xbatch compiler.predicates.TestWrongPredicateOrder
*/

package compiler.predicates;

public class TestWrongPredicateOrder {
static boolean flag;
static int iFld = 0;
static int iFld2 = 34;
static int iArr[] = new int[1005];
static int iArr2[] = new int[2];


public static void main(String[] strArr) {
// We will keep hitting the Profiled Loop Predicate for RC1 (Integer.MAX_VALUE - 1 - 3 > 1005) such that we will
// not emit the Profile Loop Parse Predicate anymore. After that, we will also keep hitting the Loop Limit Check
// Predicate (Interger.MAX_VALUE - 1 > Integer.MAX_VALUE - 2) such that we will also not emit the Loop Limit Check
// Parse Predicate anymore. As a result, we'll only emit the Loop Parse Predicate in the next re-compilation.
// In the next re-compilation, we'll hoist IC1 as Loop Predicate and IC2 as Profiled Loop Predicate.
// They have a data dependency between them but this is normally okay because Profiled Loop Predicates are below
// Loop Predicates in the graph. But due to the flipped order of Parse Predicates in this bug, we create the
// Hoisted Predicates in the wrong order and we end up with a bad graph and assert.
for (int i = 0; i < 10000; i++) {
flag = !flag;
test();
}
}

public static void test() {
// Ensure to emit Loop Limit Check Predicate which is hit too often
// -> no Loop Limit Check Parse Predicate is added in re-compilation anymore
int limit = flag ? Integer.MAX_VALUE - 1 : 1000;

int i = 0;
// Loop Limit Check Predicate: limit <= Integer.MAX_VALUE - stride + 1 = Integer.MAX_VALUE - 2
while (i < limit) {
i += 3;
// Invariant check hoisted as Loop Predicate
iArr2[iFld] = 1; // (IC1)

if (flag) {
// Early exit -> enables Profiled Loop Predicate creation below
return;
}

// Invariant check hoisted as Profiled Loop Predicate
// Data dependency on Loop Predicate for "iArr2[0] = 1"
iArr2[1] = 5; // (IC2)

// Profiled Loop Predicate for range check hit too much -> no Profiled Loop Parse Predicate is added in
// re-compilation anymore
iArr[i] = 34; // (RC1)

if (iFld2 == 5555) {
i++; // UCT -> ensures to emit Parse Predicates twice with an If in between that is folded after parsing
}
}
}
}

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