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

[Chen Liang]

On Tue, 3 Feb 2026 14:05:43 GMT, Frederic Parain <fparain at openjdk.org> wrote:

>> 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.

I have added the comments and briefly describes the field map records superclass fields so it is computed recursively and is present on AVCs.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/2012#discussion_r2759587618