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8283408: Fix a C2 crash when filling arrays with unsafe

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Backport-of: a6740c010b7d37f991c8547be6ea72b198e9094f
This commit is contained in:
Tobias Hartmann 2022-04-04 06:02:00 +00:00
parent c9b8589a47
commit 29c7f1c427
2 changed files with 73 additions and 3 deletions
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13
src/hotspot/share/opto/loopTransform.cpp
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@ -3924,10 +3924,17 @@ bool PhaseIdealLoop::intrinsify_fill(IdealLoopTree* lpt) {
index = new LShiftXNode(index, shift->in(2));
_igvn.register_new_node_with_optimizer(index);
}
index = new AddPNode(base, base, index);
_igvn.register_new_node_with_optimizer(index);
Node* from = new AddPNode(base, index, offset);
Node* from = new AddPNode(base, base, index);
_igvn.register_new_node_with_optimizer(from);
// For normal array fills, C2 uses two AddP nodes for array element
// addressing. But for array fills with Unsafe call, there's only one
// AddP node adding an absolute offset, so we do a NULL check here.
assert(offset != NULL || C->has_unsafe_access(),
"Only array fills with unsafe have no extra offset");
if (offset != NULL) {
from = new AddPNode(base, from, offset);
_igvn.register_new_node_with_optimizer(from);
}
// Compute the number of elements to copy
Node* len = new SubINode(head->limit(), head->init_trip());
_igvn.register_new_node_with_optimizer(len);

63
test/hotspot/jtreg/compiler/loopopts/FillArrayWithUnsafe.java Normal file
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@ -0,0 +1,63 @@
/*
* Copyright (c) 2022, Arm Limited. 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 8283408
* @summary Fill a byte array with Java Unsafe API
* @run main/othervm -XX:+OptimizeFill compiler.loopopts.FillArrayWithUnsafe
*/
package compiler.loopopts;
import java.lang.reflect.Field;
import sun.misc.Unsafe;
public class FillArrayWithUnsafe {
private static Unsafe unsafe;
public static void main(String[] args) throws Exception {
Class klass = Unsafe.class;
Field field = klass.getDeclaredField("theUnsafe");
field.setAccessible(true);
unsafe = (Unsafe) field.get(null);
byte[] buffer;
// Make sure method newByteArray is compiled by C2
for (int i = 0; i < 50000; i++) {
buffer = newByteArray(100, (byte) 0x80);
}
}
public static byte[] newByteArray(int size, byte val) {
byte[] arr = new byte[size];
int offset = unsafe.arrayBaseOffset(byte[].class);
for (int i = offset; i < offset + size; i++) {
unsafe.putByte(arr, i, val);
}
return arr;
}
}