RFR: 8331341: secondary_super_cache does not scale well: C1 and interpreter [v3]

[Andrew Haley]

On Fri, 5 Jul 2024 22:30:09 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>> Andrew Haley has updated the pull request incrementally with four additional commits since the last revision:
>> 
>>  - Review feedback
>>  - Review feedback
>>  - Review feedback
>>  - Cleanup check_klass_subtype_fast_path for AArch64, deleting dead code
>
> src/hotspot/share/oops/klass.cpp line 175:
> 
>> 173:     if (secondary_supers()->at(i) == k) {
>> 174:       if (UseSecondarySupersCache) {
>> 175:         ((Klass*)this)->set_secondary_super_cache(k);
> 
> Does it make sense to assert `UseSecondarySupersCache` in `Klass::set_secondary_super_cache()`?

I kinda hate this because we're casting away `const`, which is UB. I think I'd just take it out, but once I do that, I don't think anything sets `_secondary_super_cache`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19989#discussion_r1686631030