[lworld] RFR: 8372954: [lworld] Remove old implementation of the substitutability test method [v3]

[Frederic Parain]

On Tue, 3 Feb 2026 12:02:41 GMT, Dan Heidinga <heidinga at openjdk.org> wrote:

>> Paul Hübner 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 13 additional commits since the last revision:
>> 
>>  - Merge branch 'lworld' of https://github.com/openjdk/valhalla into JDK-8372954
>>  - Missed obsolete test
>>  - Years
>>  - Merge branch 'lworld' of https://github.com/openjdk/valhalla into JDK-8372954
>>  - substitutability contract changed
>>  - Legacy handling in ProcessHandleImpl
>>  - typo
>>  - Test flags
>>  - Dead stuff
>>  - Merge branch 'JDK-8372954' of github.com:Arraying/valhalla into JDK-8372954
>>  - ... and 3 more: https://git.openjdk.org/valhalla/compare/e31f9f53...29344379
>
> src/hotspot/share/classfile/classFileParser.cpp line 1399:
> 
>> 1397:   // one for the field the JVM injects when detecting an empty inline class
>> 1398:   const int total_fields = length + num_injected + (is_inline_type ? 2 : 0)
>> 1399:                            + (is_value_class ? 1 : 0);
> 
> Can you update the comment block above to include something like:
> 
> // all value classes, even abstract ones, get an additional slot for the acmp_maps field used by the substitutability check
> 
> 
> We need something to make it clear why we're testing both inline type and value class here and what the new field is

Could you update the comment above, replacing the mention to the pre-allocated default value with the a mention to the null-reset value? 
This is not related to the removal of the old substitutability method, but it's an easy cleanup to do.
Thanks.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/2012#discussion_r2759263758