RFR: 8331341: secondary_super_cache does not scale well: C1 and interpreter [v2]

[Vladimir Ivanov]

On Thu, 18 Jul 2024 20:07:14 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>> I think not. It'd complicate C++ runtime for no useful reason.
>
> On the other hand, if `-XX:-UseSecondarySupersTable` is intended solely for diagnostic purposes, then handling all possible execution modes uniformly is preferable, since it gives more confidence when troubleshooting seemingly related failures.

Alternatively, `Klass::is_subtype_of()` can unconditionally perform linear search over secondary_supers array. 

Even though I very much like to see table lookup written in C++ (accompanying heavily optimized platform-specific MacroAssembler variants), it would make C++ runtime even simpler.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19989#discussion_r1683423052