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/*
* Copyright (c) 2023, 2024, 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.
*/
package compiler.gcbarriers;
import java.util.Arrays;
/**
* @test
* @bug 8312749
* @summary Test that, when using a larger object alignment, ZGC arraycopy
* barriers are only applied to actual OOPs, and not to object
* alignment padding words.
* @requires vm.gc.Z
* @run main/othervm -Xbatch -XX:-TieredCompilation
* -XX:CompileOnly=compiler.gcbarriers.TestArrayCopyWithLargeObjectAlignment::*
* -XX:ObjectAlignmentInBytes=16
* -XX:+UseZGC
* compiler.gcbarriers.TestArrayCopyWithLargeObjectAlignment
*/
public class TestArrayCopyWithLargeObjectAlignment {
static Object[] doCopyOf(Object[] array) {
return Arrays.copyOf(array, array.length);
}
static Object[] doClone(Object[] array) {
return array.clone();
}
public static void main(String[] args) {
for (int i = 0; i < 10_000; i++) {
// This test allocates an array 'a', copies it into a new array 'b'
// using Arrays.copyOf, and clones 'b' into yet another array. For
// ObjectAlignmentInBytes=16, the intrinsic implementation of
// Arrays.copyOf leaves the object alignment padding word "b[1]"
// untouched, preserving the badHeapWordVal value '0xbaadbabe'. The
// test checks that this padding word is not processed as a valid
// OOP by the ZGC arraycopy stub underlying the intrinsic
// implementation of Object.clone. Allocating b using the intrinsic
// implementation of Arrays.copyOf is key to reproducing the issue
// because, unlike regular (fast or slow) array allocation,
// Arrays.copyOf does not zero-clear the padding word.
Object[] a = {new Object()};
Object[] b = doCopyOf(a);
doClone(b);
}
}
}
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