diff --git a/src/hotspot/share/classfile/fieldLayoutBuilder.hpp b/src/hotspot/share/classfile/fieldLayoutBuilder.hpp index cda64788acffa..9b0d80b2a5583 100644 --- a/src/hotspot/share/classfile/fieldLayoutBuilder.hpp +++ b/src/hotspot/share/classfile/fieldLayoutBuilder.hpp @@ -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. * * 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. // Note: with line types, the comparison should include alignment constraint if sizes are equals 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(); + // qsort() may reverse the order of fields with the same size. + // The extension is to ensure stable sort. if (diff == 0) { diff = (*x)->field_index() - (*y)->field_index(); } return diff; -#else - return (*y)->size() - (*x)->size(); -#endif // _WINDOWS } }; diff --git a/test/hotspot/jtreg/runtime/FieldLayout/TestFieldLayout.java b/test/hotspot/jtreg/runtime/FieldLayout/TestFieldLayout.java new file mode 100644 index 0000000000000..4066d6dd743d5 --- /dev/null +++ b/test/hotspot/jtreg/runtime/FieldLayout/TestFieldLayout.java @@ -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; + } + +} +