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8245714: "Bad graph detected in build_loop_late" when loads are pinne…
…d on loop limit check uncommon branch

Reviewed-by: thartmann
  • Loading branch information
rwestrel committed May 28, 2020
1 parent 01cfedf commit 9c99008aff3443bb0c3f7a8baf7e91b859294c0d
Showing with 91 additions and 7 deletions.
  1. +6 −7 src/hotspot/share/opto/loopPredicate.cpp
  2. +85 −0 test/hotspot/jtreg/compiler/loopopts/TestBadControlLoopLimitCheck.java
@@ -122,20 +122,19 @@ ProjNode* PhaseIdealLoop::create_new_if_for_predicate(ProjNode* cont_proj, Node*
CallNode* call = rgn->as_Call();
IdealLoopTree* loop = get_loop(call);
rgn = new RegionNode(1);
Node* uncommon_proj_orig = uncommon_proj;
uncommon_proj = uncommon_proj->clone()->as_Proj();
register_control(uncommon_proj, loop, iff);
rgn->add_req(uncommon_proj);
register_control(rgn, loop, uncommon_proj);
_igvn.replace_input_of(call, 0, rgn);
// When called from beautify_loops() idom is not constructed yet.
if (_idom != NULL) {
set_idom(call, rgn, dom_depth(rgn));
}
for (DUIterator_Fast imax, i = uncommon_proj->fast_outs(imax); i < imax; i++) {
Node* n = uncommon_proj->fast_out(i);
if (n->is_Load() || n->is_Store()) {
_igvn.replace_input_of(n, 0, rgn);
--i; --imax;
}
}
// Move nodes pinned on the projection or whose control is set to
// the projection to the region.
lazy_replace(uncommon_proj_orig, rgn);
} else {
// Find region's edge corresponding to uncommon_proj
for (; proj_index < rgn->req(); proj_index++)
@@ -0,0 +1,85 @@
/*
* 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 8245714
* @requires vm.compiler2.enabled
* @summary "Bad graph detected in build_loop_late" when loads are pinned on loop limit check uncommon branch
*
* @run main/othervm -XX:-BackgroundCompilation -XX:ArrayCopyLoadStoreMaxElem=0 TestBadControlLoopLimitCheck
*/

public class TestBadControlLoopLimitCheck {
public static void main(String[] args) {
int[] int_array = {0, 0};
A[] obj_array = {new A(), new A()};
for (int i = 0; i < 20_000; i++) {
test1(int_array, 0, 10, false);
test_helper(42);
test2(obj_array, 0, 10, false);
}
}

private static int test1(int[] a, int start, int stop, boolean flag) {
int[] b = new int[2]; // non escaping allocation
System.arraycopy(a, 0, b, 0, 2); // optimized out
int v = 1;
int j = 0;
for (; j < 10; j++);
int inc = test_helper(j); // delay transformation to counted loop
// loop limit check here has loads pinned on unc branch
for (int i = start; i < stop; i += inc) {
v *= 2;
}
if (flag) {
v += b[0] + b[1];
}
return v;
}

private static int test2(A[] a, int start, int stop, boolean flag) {
A[] b = new A[2]; // non escaping allocation
System.arraycopy(a, 0, b, 0, 2); // optimized out
int v = 1;
int j = 0;
for (; j < 10; j++);
int inc = test_helper(j); // delay transformation to counted loop
// loop limit check here has loads pinned on unc branch
for (int i = start; i < stop; i += inc) {
v *= 2;
}
if (flag) {
v += b[0].f + b[1].f;
}
return v;
}

static class A {
int f;
}

static int test_helper(int j) {
return j == 10 ? 10 : 1;
}
}

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