StrideArraysCore not able to SIMD

[jwscook]

I was using Polyester.jl to thread an outer loop and wanted to SIMD the inner loop but got an error. Apparently Polyester converts vectors into StrideArraysCore.PtrArray which does not dispatch on SIMD._pointer. Below is the MWE example of the error and a fix. I'd be happy to provide the fix here but StrideArraysCore.jl is not a dependency, so thought I'd raise the issue here.

julia> using StrideArraysCore, SIMD

julia> x = StrideArraysCore.PtrArray(rand(4))
4-element PtrArray{Float64, 1, (1,), Tuple{Int64}, Tuple{Nothing}, Tuple{StaticInt{1}}}:
 0.5349256395906962
 0.17431749301270416
 0.8864181731419128
 0.30373397033508265

julia> lane = VecRange{4}(0)
VecRange{4}(0)

julia> x[1 + lane]
ERROR: MethodError: no method matching _pointer(::PtrArray{Float64, 1, (1,), Tuple{Int64}, Tuple{Nothing}, Tuple{StaticInt{1}}}, ::Int64, ::Tuple{})

Closest candidates are:
  _pointer(::SubArray{T, N, P, I, true} where {T, N, P, I<:Union{Tuple{Vararg{Real}}, Tuple{AbstractUnitRange, Vararg{Any}}}}, ::Any, ::Tuple{})
   @ SIMD ~/.julia/packages/SIMD/2fAdM/src/arrayops.jl:290
  _pointer(::SubArray{T, N, P, I, true} where {T, N, P, I<:Union{Tuple{Vararg{Real}}, Tuple{AbstractUnitRange, Vararg{Any}}}}, ::Any, ::Any)
   @ SIMD ~/.julia/packages/SIMD/2fAdM/src/arrayops.jl:288
  _pointer(::SubArray, ::Any, ::Any)
   @ SIMD ~/.julia/packages/SIMD/2fAdM/src/arrayops.jl:295
  ...

Stacktrace:
 [1] getindex(::PtrArray{Float64, 1, (1,), Tuple{Int64}, Tuple{Nothing}, Tuple{StaticInt{1}}}, ::VecRange{4})
   @ SIMD ~/.julia/packages/SIMD/2fAdM/src/arrayops.jl:302
 [2] top-level scope
   @ REPL[4]:1

The obvious fix is

Base.@propagate_inbounds SIMD._pointer(arr::StrideArraysCore.PtrArray, i, I) =
    pointer(Base.unsafe_view(arr, 1, I...), i)

[KristofferC]

I would have thought that maybe

SIMD.jl/src/arrayops.jl

Lines 288 to 289 in ecf1f4a

	Base.@propagate_inbounds _pointer(arr::Base.FastContiguousSubArray, i, I) =
	pointer(arr, (i, I...))

would match this but perhaps this is the difference between "FastContiguousArray" and "ContiguousArray". I don't fully understand all the typealiases in that file...

[KristofferC]

I'd be happy to provide the fix here but StrideArraysCore.jl is not a dependency, so thought I'd raise the issue here.

In theory we could add an extension for StrideArraysCore and provide it there but if it can be done generically, that would be better.

[jwscook]

Yep, extending it treats the symptom but a cure would be better.