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8229994: assert(false) failed: Bad graph detected in get_early_ctrl_f…

…or_expensive

Fixes wrong idom information set in loop peeling when a loop strip mined loop is involved.

Reviewed-by: vlivanov, thartmann
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Christian Hagedorn
Christian Hagedorn committed Dec 6, 2019
1 parent 70c62f5 commit fd8832f726df4902fdd464908a0ba6639dd14755
@@ -654,8 +654,8 @@ void PhaseIdealLoop::do_peeling(IdealLoopTree *loop, Node_List &old_new) {

// Step 4: Correct dom-depth info. Set to loop-head depth.

int dd = dom_depth(head);
set_idom(head, head->in(1), dd);
int dd = dom_depth(head->skip_strip_mined());
set_idom(head->skip_strip_mined(), head->skip_strip_mined()->in(LoopNode::EntryControl), dd);
for (uint j3 = 0; j3 < loop->_body.size(); j3++) {
Node *old = loop->_body.at(j3);
Node *nnn = old_new[old->_idx];
@@ -0,0 +1,84 @@
/*
* Copyright (c) 2019, 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 8229994
* @summary Tests dominance in PhaseIdealLoop::get_early_ctrl_for_expensive() if an expensive SqrtD node is peeled.
*
* @run main/othervm -Xbatch -XX:-TieredCompilation
* -XX:CompileCommand=compileonly,compiler.loopopts.PeelingAndLoopStripMining::*
* compiler.loopopts.PeelingAndLoopStripMining
*/

package compiler.loopopts;

public class PeelingAndLoopStripMining {

static double dFld = 3.3;

public void test(int k) {
for (int i = 1; i < 100; i++) {
// Loop invariant check triggers loop peeling
if (k == 300) {
return;
}

/*
* sqrtAdd() is inlined which contains an expensive node SqrtD with a control input from the above IfTrue node 'ifT'
* (flipped in IR, i.e. when not returning). PhaseIdealLoop::peeled_dom_test_elim() will change the control input
* of SqrtD to the peeled IfTrue node 'pifT' of 'ifT' and test if 'pifT' is on the idom chain starting from 'ifT'.
* This failed previously because the new loop entry from the peeled iteration was always set as idom of the
* CountedLoop node and not of the OuterStripMinedLoop node if present. Thus, 'pifT' was not found on the idom chain
* starting from 'ifT' resulting in a bad graph assertion failure in PhaseIdealLoop::get_early_ctrl_for_expensive().
*/
dFld = sqrtAdd(i);
}
}

public static void main(String[] strArr) {
PeelingAndLoopStripMining _instance = new SubClass();
for (int i = 0; i < 10000; i++ ) {
_instance.test(12);
}

_instance = new PeelingAndLoopStripMining();
for (int i = 0; i < 10000; i++ ) {
_instance.test(300);
}
for (int i = 0; i < 10000; i++ ) {
_instance.test(45);
}
}

public double sqrtAdd(int i) {
return 1.0 + Math.sqrt(i);
}
}

class SubClass extends PeelingAndLoopStripMining {
public double sqrtAdd(int i) {
return 2.0 + Math.sqrt(i);
}
}

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