RFR: 8339168: Optimize ClassFile Util slotSize [v2]

[Claes Redestad]

On Fri, 30 Aug 2024 05:13:33 GMT, Shaojin Wen <swen at openjdk.org> wrote:

>> A small optimization to improve the performance of jdk.internal.classfile.impl.Util#slotSize/isDoubleSlot
>
> Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Suggestions from @cl4es

What I noticed is that in all but one place where we call `slotSize` we're dealing parameters which can't be void. So specializing and having a `paramSlotSize(ClassDesc desc) { return isDoubleSlot(desc) ? 2 : 1; }` would perhaps be better.

As always it's good to annotate performance enhancements like these with some microbenchmark data - if not else to indicate how you've evaluated the gain.

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PR Comment: https://git.openjdk.org/jdk/pull/20747#issuecomment-2326361775