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

[Andrew Haley]

On Thu, 18 Jul 2024 20:11:03 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

> 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.

It would, but there is something to be said for being able to provide a fast "no" answer for interface membership. I'll agree it's probably not a huge difference. I guess `is_cloneable_fast()` exists only because searching the interfaces is slow.
Also, if table lookup is written in C++ but not used, it will rot.
Also also, `Klass::is_subtype_of()` is used for C1 runtime.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19989#discussion_r1686707925