[lworld] RFR: 8373864: [lworld] Hide and rename InstanceKlassFixedBlock [v2]

[Stefan Karlsson]

On Wed, 17 Dec 2025 13:29:54 GMT, Frederic Parain <fparain at openjdk.org> wrote:

>> Stefan Karlsson has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:
>> 
>>  - Fix null check
>>  - Merge remote-tracking branch 'valhalla/lworld' into lworld_8373864_inline_klass_members
>>  - 8373864: [lworld] Hide and rename InstanceKlassFixedBlock
>
> src/hotspot/share/oops/inlineKlass.hpp line 53:
> 
>> 51:   // features (see InstanceKlass::size). Therefore, we can't put C++ fields
>> 52:   // directly into the InlineKlass class, but instead we stamp out a block of
>> 53:   // these members after the part of the object that comes from the InstanceKlass.
> 
> Suggestion: clarify in the comment that the goal was to have the same offset for the vtable in both InstanceKlass and InlineKlass, so the vtable could be accessed without having to differentiate between the two kinds of Klass.
> 
> Otherwise, nice rework!

Thanks! I've updated the comment to go into more details. Please, take a look and see if this is better.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/1812#discussion_r2627201378