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8256934: C2: assert(C->live_nodes() <= C->max_node_limit()) failed: L…
…ive Node limit exceeded limit

Reviewed-by: roland, vlivanov
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chhagedorn committed Jun 16, 2021
1 parent 19f5fab commit 9ad19f7838e6f6e128583c191c5507c1e2bd5083
Showing 2 changed files with 88 additions and 3 deletions.
@@ -2819,6 +2819,12 @@ int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, No
worklist.push(use);
}
}

if (C->check_node_count(worklist.size() + NodeLimitFudgeFactor,
"Too many clones required in clone_for_use_outside_loop in partial peeling")) {
return -1;
}

while( worklist.size() ) {
Node *use = worklist.pop();
if (!has_node(use) || use->in(0) == C->top()) continue;
@@ -3371,6 +3377,7 @@ bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
#endif

// Evacuate nodes in peel region into the not_peeled region if possible
bool too_many_clones = false;
uint new_phi_cnt = 0;
uint cloned_for_outside_use = 0;
for (uint i = 0; i < peel_list.size();) {
@@ -3387,7 +3394,12 @@ bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
// if not pinned and not a load (which maybe anti-dependent on a store)
// and not a CMove (Matcher expects only bool->cmove).
if (n->in(0) == NULL && !n->is_Load() && !n->is_CMove()) {
cloned_for_outside_use += clone_for_use_outside_loop(loop, n, worklist);
int new_clones = clone_for_use_outside_loop(loop, n, worklist);
if (new_clones == -1) {
too_many_clones = true;
break;
}
cloned_for_outside_use += new_clones;
sink_list.push(n);
peel.remove(n->_idx);
not_peel.set(n->_idx);
@@ -3415,9 +3427,9 @@ bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
bool exceed_node_budget = !may_require_nodes(estimate);
bool exceed_phi_limit = new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta;

if (exceed_node_budget || exceed_phi_limit) {
if (too_many_clones || exceed_node_budget || exceed_phi_limit) {
#ifndef PRODUCT
if (TracePartialPeeling) {
if (TracePartialPeeling && exceed_phi_limit) {
tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
}
@@ -0,0 +1,73 @@
/*
* Copyright (c) 2021, 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 8256934
* @summary Sinking of nodes in partial peeling creates too many clones resulting in a live node limit exceeded assertion failure.
* @requires vm.compiler2.enabled
* @run main/othervm -Xcomp -XX:-TieredCompilation -XX:CompileCommand=compileonly,compiler.loopopts.TestPartialPeelingSinkNodes::test
* compiler.loopopts.TestPartialPeelingSinkNodes
*/

package compiler.loopopts;

public class TestPartialPeelingSinkNodes {
static int i5 = 168, iFld = 2, x, y;
static boolean b = false, b2 = false;

public static void main(String[] strArr) {
test();
}

// The algorithm in partial peeling creates ~90000 nodes for this method which triggers the assertion failure.
public static void test() {
for (int i = 0; i < 2480; i++) {
int i2 = -37052, i3 = 39651, i4 = -37052;
int i5 = 168, i6 = -133, i7 = 1, i8 = -10;
double d = -20.82293;

float fArr[] = new float[400];
for (int j = 0; j < 400; j++) {
fArr[j] = (j % 2 == 0) ? 0.300F + j : 0.300F - j;
}

while (--i5 > 0) {
i6 = 1;
do {
i4 += (((i6 * i2) + i3) - i3);
i2 += i4;
} while (++i6 < 9);
i3 -= i4;
for (i7 = 1; i7 < 18; i7++) {
i4 = i5;
d -= i4;
i2 -= i8;
i2 = i8;
}
}
}
}
}

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