[lworld] RFR: 8357373: [lworld] jdk/valhalla/valuetypes/ObjectMethods.java fails with -XX:+UseAtomicValueFlattening [v2]

[Volkan Yazici]

On Thu, 4 Dec 2025 22:38:39 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

>> This test failing with VM options prompted a refatoring and cleanup of the test (and renaming to be more appropriate).
>> The test is re-enabled with a 4 combinations of command line flags.
>> 
>> Refactored test to verify that hashcode changed with each change to a field. Previously, the test tried to compute the hashCode for the value class. That was fragile in the presence of the VM changing the layout information. Check the hashCodes are equal for objects that are `.equals`. Renamed to 'ValueObjectMethodsTest`.
>
> Roger Riggs has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Correct check for identityHashCode

test/jdk/valhalla/valuetypes/ValueObjectMethodsTest.java line 253:

> 251:         Line l3 = new Line(0, 9, 2, 3);
> 252:         Line l4 = new Line(0, 1, 9, 3);
> 253:         Line l5 = new Line(0, 1, 2, 9);

Random thought: Would it be a good idea to randomize the content to increase coverage over time? For example,

    var r = new java.util.Random();
    var coordinates = Stream
            .generate(() -> List.of(r.nextInt(), r.nextInt()))
            .distinct()
            .limit(4)
            .toList();
    int i = 0;
    var p1 = new Point(coordinates.get(i).get(0), coordinates.get(i).get(1)); i++;
    var p2 = new Point(coordinates.get(i).get(0), coordinates.get(i).get(1)); i++;
    var p3 = new Point(coordinates.get(i).get(0), coordinates.get(i).get(1)); i++;
    var p4 = new Point(coordinates.get(i).get(0), coordinates.get(i).get(1));

test/jdk/valhalla/valuetypes/ValueObjectMethodsTest.java line 280:

> 278:     @MethodSource("hashcodeTests")
> 279:     public void testHashCode(List<Object> objects) {
> 280:         assertTrue(objects.size() > 1, "More than one object is required: " + objects);

_Nit:_ I doubt if displaying `[]` will contribute much to the diagnostics context.

Suggestion:

        assertFalse(objects.isEmpty(), "More than one object is required");

-------------

PR Review Comment: https://git.openjdk.org/valhalla/pull/1771#discussion_r2591865591
PR Review Comment: https://git.openjdk.org/valhalla/pull/1771#discussion_r2591872272