On Thu, 18 Jul 2024 16:35:16 GMT, Andrew Haley <a...@openjdk.org> wrote:
>> On a second thought the following setter may be the culprit:
>>
>> void Klass::set_secondary_supers(Array<Klass*>* secondaries) {
>> assert(!UseSecondarySupersTable || secondaries == nullptr, "");
>> set_secondary_supers(secondaries, SECONDARY_SUPERS_BITMAP_EMPTY);
>> }
>>
>> It should be adjusted to set `SECONDARY_SUPERS_BITMAP_FULL` instead.
>
> I've spent a while trying to reproduce the problem but I can't.
>
> I was seeing a problem where
> `Klass::is_subtype_of(vmClasses::Cloneable_klass())` was being called before
> the bitmap had been set. I'm not sure what to think, really. Maybe I should
> just back out this change to see what happens.
I'm in favor of backing out this change and adding an assert/guarantee (on
`_secondary_supers != nullptr`) in `Klass::is_subtype_of()` to ensure no
subtype checks happen on uninitialized Klasses. Then we should be able to spot
and fix all the places where problematic checks happen.
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PR Review Comment: https://git.openjdk.org/jdk/pull/19989#discussion_r1683409343
