[lworld] RFR: 8353432: [lworld] Deoptimization needs to handle nullable, flat fields in non-value class holders [v2]

[Tobias Hartmann]

On Tue, 3 Jun 2025 16:57:40 GMT, Quan Anh Mai <qamai at openjdk.org> wrote:

>> Hi,
>> 
>> This patch adds handling of nullable flat fields in non-value class holder. Currently, we add all the fields to the safepoint, then add all the null markers. I decide to change this to adding the null marker of a flat field right after all the subfields of it. It makes the shape similar to how we pass nullable flat fields in the ABI, as well as simplifies the implementation since we do not have to keep track of all null markers when traversing the object payload.
>> 
>> Please take a look and leave your reviews, thanks a lot.
>
> Quan Anh Mai has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains four commits:
> 
>  - whitespace
>  - better debug
>  - Merge branch 'lworld' into safepoint
>  - handle nullable flat fields in safepoint

Thanks for making these adjustments. All tests passed and the fix looks good to me!

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

Marked as reviewed by thartmann (Committer).

PR Review: https://git.openjdk.org/valhalla/pull/1478#pullrequestreview-2895990543