RFR: 8354996: Reduce dynamic code generation for a single downcall [v2]

[Chen Liang]

On Fri, 18 Apr 2025 18:15:09 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> So just `Linker.nativeLinker().downcallHandle(MemorySegment.ofArray(new byte[0]), signature)` suffices?
>
> Yes, that would work, but I was thinking just `Linker.nativeLinker().downcallHandle(signature)`

Yep, simplified this, the startup results are still similar.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24742#discussion_r2050975328