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8260709: C2: assert(false) failed: unscheduable graph
Reviewed-by: thartmann, chagedorn
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rwestrel committed Feb 4, 2021
1 parent 5307afa commit 4de3a6be9e60b9676f2199cd18eadb54a9d6e3fe
Showing with 70 additions and 1 deletion.
  1. +2 −0 src/hotspot/share/opto/loopnode.hpp
  2. +8 −1 src/hotspot/share/opto/loopopts.cpp
  3. +60 −0 test/hotspot/jtreg/compiler/loopopts/TestLoadPinnedAfterAllocate.java
@@ -1607,6 +1607,8 @@ class PhaseIdealLoop : public PhaseTransform {
void check_long_counted_loop(IdealLoopTree* loop, Node* x) NOT_DEBUG_RETURN;

LoopNode* create_inner_head(IdealLoopTree* loop, LongCountedLoopNode* head, LongCountedLoopEndNode* exit_test);

bool is_safe_load_ctrl(Node* ctrl);
};


@@ -1429,7 +1429,7 @@ void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
// If n is a load, and the late control is the same as the current
// control, then the cloning of n is a pointless exercise, because
// GVN will ensure that we end up where we started.
if (!n->is_Load() || late_load_ctrl != n_ctrl) {
if (!n->is_Load() || (late_load_ctrl != n_ctrl && is_safe_load_ctrl(late_load_ctrl))) {
for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
Node *u = n->last_out(j); // Clone private computation per use
_igvn.rehash_node_delayed(u);
@@ -1525,6 +1525,13 @@ void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
}
}

bool PhaseIdealLoop::is_safe_load_ctrl(Node* ctrl) {
if (ctrl->is_Proj() && ctrl->in(0)->is_Call() && ctrl->has_out_with(Op_Catch)) {
return false;
}
return true;
}

//------------------------------split_if_with_blocks---------------------------
// Check for aggressive application of 'split-if' optimization,
// using basic block level info.
@@ -0,0 +1,60 @@
/*
* Copyright (c) 2021, 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 8260709
* @summary C2: assert(false) failed: unscheduable graph
*
* @run main/othervm -XX:-BackgroundCompilation TestLoadPinnedAfterAllocate
*
*/

public class TestLoadPinnedAfterAllocate {
private int field;
private static volatile int barrier;
private static Object field2;

public static void main(String[] args) {
final TestLoadPinnedAfterAllocate test = new TestLoadPinnedAfterAllocate();
for (int i = 0; i < 20_000; i++) {
test.test(1, 10);
}
}

private int test(int start, int stop) {
int[] array = new int[10];
for (int j = 0; j < 10; j++) {
barrier = 1;
// early control for field load below
for (int i = 1; i < 10; i *= 2) {
field2 = array;
array = new int[10];
// late control for field load below
}
}
int v = field;
array[0] = v;
return v+v;
}
}

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