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8341471: Reversed field layout caused by unstable sorting

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Reviewed-by: jwaters, jsjolen
This commit is contained in:
Fei Gao 2024-10-14 08:40:03 +00:00
parent e3f6503937
commit dcac4b0a53
2 changed files with 79 additions and 7 deletions
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10
src/hotspot/share/classfile/fieldLayoutBuilder.hpp
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@ -1,5 +1,5 @@
/* /*
* Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved. * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
* *
* This code is free software; you can redistribute it and/or modify it * This code is free software; you can redistribute it and/or modify it
@ -101,17 +101,13 @@ class LayoutRawBlock : public ResourceObj {
// sort fields in decreasing order. // sort fields in decreasing order.
// Note: with line types, the comparison should include alignment constraint if sizes are equals // Note: with line types, the comparison should include alignment constraint if sizes are equals
static int compare_size_inverted(LayoutRawBlock** x, LayoutRawBlock** y) { static int compare_size_inverted(LayoutRawBlock** x, LayoutRawBlock** y) {
#ifdef _WINDOWS
// qsort() on Windows reverse the order of fields with the same size
// the extension of the comparison function below preserves this order
int diff = (*y)->size() - (*x)->size(); int diff = (*y)->size() - (*x)->size();
// qsort() may reverse the order of fields with the same size.
// The extension is to ensure stable sort.
if (diff == 0) { if (diff == 0) {
diff = (*x)->field_index() - (*y)->field_index(); diff = (*x)->field_index() - (*y)->field_index();
} }
return diff; return diff;
#else
return (*y)->size() - (*x)->size();
#endif // _WINDOWS
} }
}; };

76
test/hotspot/jtreg/runtime/FieldLayout/TestFieldLayout.java Normal file
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@ -0,0 +1,76 @@
/*
* Copyright (c) 2024, 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.
*/
import java.lang.reflect.Field;
import jdk.internal.misc.Unsafe;
/*
* @test
* @bug 8341471
* @summary Reversed field layout caused by unstable sorting
* @modules java.base/jdk.internal.misc
* @run main/othervm TestFieldLayout
*/
public class TestFieldLayout {
private static final Unsafe U = Unsafe.getUnsafe();
public static void main(String[] args) throws Exception {
boolean endResult = true;
long previous = 0;
for (Field f : Test.class.getDeclaredFields()) {
long current = U.objectFieldOffset(f);
if (current < previous) {
System.out.printf("FAILED: field %s offset %d previous %d\n",
f.getName(), current, previous);
endResult = false;
}
previous = current;
}
System.out.println(endResult ? "Test PASSES" : "Test FAILS");
if (!endResult) {
throw new Error("Test failed");
}
}
public class Test {
char a000;
char a001;
char a002;
char a003;
char a004;
char a005;
char a006;
char a007;
char a008;
char a009;
char a00a;
char a00b;
}
}