[lworld] RFR: 8376221: [lworld] Do not store array of InlineLayoutInfo for all InstanceKlasses [v4]

[Joel Sikström]

On Wed, 28 Jan 2026 12:30:09 GMT, Paul Hübner <phubner at openjdk.org> wrote:

>> Joel Sikström has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Exception check should really be an assert
>>  - Move inlineable check to static helper
>
> src/hotspot/share/classfile/fieldLayoutBuilder.cpp line 108:
> 
>> 106:   }
>> 107: 
>> 108:   if (!fieldinfo.field_flags().is_injected() &&
> 
> What's the rationale of not inlining injected fields? Is there a reason we need to treat them specially? I think I see this behaviour in the removed code as well, but I'm curious why this is the case.

The logic is the same as we had before, I just moved it to this helper. With that said, I'm not sure why we check this, as an injected field should likely not be present in `_inline_layout_info_array` so should not get through this check at all...

> src/hotspot/share/classfile/fieldLayoutBuilder.cpp line 965:
> 
>> 963:         assert(_inline_layout_info_array != nullptr, "Array must have been created");
>> 964:         assert(_inline_layout_info_array->adr_at(field_index)->klass() != nullptr, "Klass must have been set");
>> 965:         _has_inlined_fields = true;
> 
> Nit: can we have some sort of `set/mark_inlined_fields_checked` which does this? I saw the exact same code block above.

Maybe we can hold off on this and address that in a follow-up? I think it would be good to try to extract common logic from the following two methods, which are very similar right now:

FieldLayoutBuilder::inline_class_field_sorting()
FieldLayoutBuilder::regular_field_sorting()

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PR Review Comment: https://git.openjdk.org/valhalla/pull/1966#discussion_r2737999879
PR Review Comment: https://git.openjdk.org/valhalla/pull/1966#discussion_r2738000437