* the SB-SIMD contrib now supports ARM64. (Thanks to Sylvia Harrington)
    * AVX512 instructions are now supported on X86-64. (Thanks to Robert Smith and Arthur Miller)
    * additional support for SIMD instructions on ARM64 and X86-64. (Thanks to Arthur Miller)

These seem like pretty awesome additions. Does anyone know how SIMD works in SBCL? Is this at the codegen layer? i.e. can it auto-vectorize or anything like that? Or are these intrinsics you have to explicitly ask for?