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8253756: C2 CompilerThread0 crash in Node::add_req(Node*)
Reviewed-by: vlivanov, thartmann
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rwestrel committed Oct 8, 2020
1 parent 8f9e479 commit 76a5852776830777feb56e97497ad417ec6b8e6c
Showing 3 changed files with 83 additions and 1 deletion.
@@ -1105,7 +1105,7 @@ void LoopNode::verify_strip_mined(int expect_skeleton) const {
bool has_skeleton = outer_le->in(1)->bottom_type()->singleton() && outer_le->in(1)->bottom_type()->is_int()->get_con() == 0;
if (has_skeleton) {
assert(expect_skeleton == 1 || expect_skeleton == -1, "unexpected skeleton node");
assert(outer->outcnt() == 2, "only phis");
assert(outer->outcnt() == 2, "only control nodes");
} else {
assert(expect_skeleton == 0 || expect_skeleton == -1, "no skeleton node?");
uint phis = 0;
@@ -1733,9 +1733,30 @@ const Type* OuterStripMinedLoopEndNode::Value(PhaseGVN* phase) const {
if (phase->type(in(0)) == Type::TOP)
return Type::TOP;

// Until expansion, the loop end condition is not set so this should not constant fold.
if (is_expanded(phase)) {
return IfNode::Value(phase);
}

return TypeTuple::IFBOTH;
}

bool OuterStripMinedLoopEndNode::is_expanded(PhaseGVN *phase) const {
// The outer strip mined loop head only has Phi uses after expansion
if (phase->is_IterGVN()) {
Node* backedge = proj_out_or_null(true);
if (backedge != NULL) {
Node* head = backedge->unique_ctrl_out();
if (head != NULL && head->is_OuterStripMinedLoop()) {
if (head->find_out_with(Op_Phi) != NULL) {
return true;
}
}
}
}
return false;
}

Node *OuterStripMinedLoopEndNode::Ideal(PhaseGVN *phase, bool can_reshape) {
if (remove_dead_region(phase, can_reshape)) return this;

@@ -469,6 +469,8 @@ class OuterStripMinedLoopEndNode : public IfNode {

virtual const Type* Value(PhaseGVN* phase) const;
virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);

bool is_expanded(PhaseGVN *phase) const;
};

// -----------------------------IdealLoopTree----------------------------------
@@ -0,0 +1,59 @@
/*
* 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 8253756
* @summary dead outer strip mined not optimized out after expansion
* @requires vm.compiler2.enabled
*
* @run main/othervm -XX:-BackgroundCompilation -XX:LoopMaxUnroll=2 TestOuterStripMinedDeadAfterExpansion
*
*/

public class TestOuterStripMinedDeadAfterExpansion {
private static int field;

public static void main(String[] args) {
int[] array = new int[100];
for (int i = 0; i < 20_000; i++) {
test(array, array, array.length);
test_helper(array, 100);
}
}

private static int test(int[] src, int[] dst, int length) {
field = 4 << 17;
System.arraycopy(src, 0, dst, 0, length);
int stop = field >>> 17;
return test_helper(dst, stop);
}

private static int test_helper(int[] dst, int stop) {
int res = 0;
for (int i = 0; i < stop; i++) {
res += dst[i];
}
return res;
}
}

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