does Go's compiler emit SIMD instructions? it'd be cool to see the disassembly for the final, column order version since that loop would vectorize well. the same question goes for the speed-of-light benchmark -- there may be room to push even further there if it's doing a single multiply at a time.

It does not. You can use something like Avo to lighten the load a bit of writing those assembly routines. It takes care of register allocation, struct fields, and the necessary function stubs.

I was recently profiling some code in utf8 package and it caught my attention that some easily SIMDable code was lighting up in the flame chart. Kind of lame it can’t do that

+1 avo is on our radar as a tool to use in the future