Base.HWReal on Apple silicon

[ctkelley]

Why is Float16 missing from Base.HWReal on Apple silicon? On my M2 Pro, Julia 1.10 I get

julia> Base.HWReal
Union{Float32, Float64, Int16, Int32, Int64, Int8, UInt16, UInt32, UInt64, UInt8}

[vchuravy]

There is a bit of a challenge here. HWReal is per architecture, and Float16 is per micro-architecture.

x-ref: #46499 #43327 #40216

[ctkelley]

OK. Some useful packages query Base.HWReal. LoopVecrtorization.jl is one example.

[vchuravy]

Yeah we would need to have a has_float16 predicate like has_fma

[giordano]

Fixed by #55929.