[re-thc]

> SIMD is supported by Java out of the box but the optimizer might miss some opportunities

It's a little limited due to how objects are stored in memory. Might improve with Valhalla.

[dzaima]

Lucene here just dealing with plain float[]s, so Valhalla at least shouldn't affect it much. It seems the limiting thing here is that it has sum accumulators, which the optimizer can't reorder because addition isn't associative.

(for reference: scalar impl: https://github.com/ChrisHegarty/lucene/blob/dd4eaac9af346a21... and SIMD impl: https://github.com/ChrisHegarty/lucene/blob/dd4eaac9af346a21...)