But more seriously, the JVM's support for vector intrinsics is very basic right now, and I think I'd spend far more time battling the JVM to output the code I want it to output than is fun. Java just isn't the right language if you need to superoptimize stuff.
Theoretically all of the above is super simple SIMD stuff, but I have a suspicion that SIMD scatter/gather (needed for the state lookup table) isn't implemented.
If you really want to nerd snipe, write an optimized version in a non-JVM language to compare to the fastest Java one. But that's kind of boring anyway, we've seen this play out a thousand times.
I still appreciate the intention of seeing how far we can squeeze performance of modern Java+JVM though. Too bad very few folks have the freedom to apply that at their day jobs though.
It sounds like you're unfamiliar with vectorized string processing tasks, so you could surely learn a lot by working on an implementation of the proposed approach. I think it's fine to make it in C++ and then port to Java.
But more seriously, the JVM's support for vector intrinsics is very basic right now, and I think I'd spend far more time battling the JVM to output the code I want it to output than is fun. Java just isn't the right language if you need to superoptimize stuff.
Theoretically all of the above is super simple SIMD stuff, but I have a suspicion that SIMD scatter/gather (needed for the state lookup table) isn't implemented.