The first niche that came to mind was x86 code running under Rosetta 2; despite ARM having an equivalent to F16C, Rosetta 2 doesn’t translate AVX, and F16C doesn’t have a non-AVX encoding.
Indeed. Worth noting that Accelerate.framework provides fast and correct bulk f16 <-> f32 conversions as `vImageConvert_Planar16FtoPlanarF` and `vImageConvert_PlanarFtoPlanar16F`, and that the arm conversion instructions are unconditionally available for apps that compile for arm64 (they're part of the base ARMv8 ISA), so any _new_ code shouldn't need to worry about this.
