MethodError: no method matching vload(::Ptr{Float64}, ::Int64, ::Mask{4,UInt8})

[baggepinnen]

Trying to produce a MWE for another problem, I stumbled into the following. If the length of x is changed to 12, the error goes away.

julia> function avx_problem(x::AbstractVector{T}, m) where T
           N = length(x)
           n = N-m+1
           ent = zeros(T, N)
           x isa AbstractVector && (x = x')
           @avx for i = 1:N
               for j = 1:size(x,1)
                   ent[i] += x[j,i]*log(x[j,i])
               end
           end
           ent
       end
avx_problem (generic function with 1 method)

julia> x = rand(10);

julia> e1 = avx_problem(x, 4);
ERROR: MethodError: no method matching vload(::Ptr{Float64}, ::Int64, ::VectorizationBase.Mask{4,UInt8})
Closest candidates are:
  vload(::Ptr{T}, ::I) where {T<:Union{Bool, Float16, Float32, Float64, Int128, Int16, Int32, Int64, Int8, UInt128, UInt16, UInt32, UInt64, UInt8}, I<:Integer} at /home/fredrikb/.julia/packages/VectorizationBase/WoChf/src/vectorizable.jl:58
  vload(::VectorizationBase.RangeWrapper, ::Any, ::Any) at /home/fredrikb/.julia/packages/VectorizationBase/WoChf/src/vectorizable.jl:565
  vload(::Ptr, ::VectorizationBase.SVec{W,I}, ::VectorizationBase.Mask{W,U} where U<:Unsigned, ::Val{Aligned}) where {W, I<:Integer, Aligned} at /home/fredrikb/.julia/packages/SIMDPirates/ShWZm/src/memory.jl:685
  ...
Stacktrace:
 [1] vload at /home/fredrikb/.julia/packages/VectorizationBase/WoChf/src/vectorizable.jl:217 [inlined]
 [2] macro expansion at /home/fredrikb/.julia/packages/LoopVectorization/WAJXF/src/reconstruct_loopset.jl:465 [inlined]
 [3] _avx_! at /home/fredrikb/.julia/packages/LoopVectorization/WAJXF/src/reconstruct_loopset.jl:465 [inlined]
 [4] avx_problem(::Array{Float64,1}, ::Int64) at ./none:6
 [5] top-level scope at none:0

[chriselrod]

Thanks for the report. I'm overhauling how indexing is handled on LoopVectorization master, so I'll add this as a test case for the 0.8 release and make sure it's resolved.

As a hotfix, I think the vload method at VectorizationBase.jl/src/vectorizable.jl L217 should be

@inline function vload(ptr::AbstractPointer, i::Tuple, u::Union{AbstractMask,Unsigned})
    vload(ptr.ptr, offset(ptr, staticm1(i)), extract_data(u))
end

instead of the current definition (shown in long form below for readability)

@inline function vload(ptr::AbstractPointer, i::Tuple, u::Union{AbstractMask,Unsigned})
    vload(ptr.ptr, offset(ptr, staticm1(i)), u)
end

but I'd have to make sure this doesn't break other code, since the call may be recursive and the method for OffsetStridedPtrs might not be generic enough.

[chriselrod]

On my local versions...

julia> function avx_problem(x::AbstractVector{T}, m) where T
           N = length(x)
           n = N-m+1
           ent = zeros(T, N)
           x isa AbstractVector && (x = x')
           @avx for i = 1:N
               for j = 1:size(x,1)
                   ent[i] += x[j,i]*log(x[j,i])
               end
           end
           ent
       end
avx_problem (generic function with 1 method)

julia> x = rand(10);

julia> e1 = avx_problem(x, 4);

julia> e1
10-element Array{Float64,1}:
 -0.014324309330997381
 -0.3574754936802546
 -0.1615672896072288
 -0.3575533568057155
 -0.3080345204163032
 -0.28612490368920807
 -0.11497348037080715
 -0.08191664892303317
 -0.2838872967103637
 -0.3384879959637381

julia> function no_avx_problem(x::AbstractVector{T}, m) where T
           N = length(x)
           n = N-m+1
           ent = zeros(T, N)
           x isa AbstractVector && (x = x')
           for i = 1:N
               for j = 1:size(x,1)
                   ent[i] += x[j,i]*log(x[j,i])
               end
           end
           ent
       end
no_avx_problem (generic function with 1 method)

julia> e2 = no_avx_problem(x, 4);

julia> e2
10-element Array{Float64,1}:
 -0.014324309330997381
 -0.3574754936802546
 -0.1615672896072288
 -0.3575533568057155
 -0.30803452041630325
 -0.2861249036892081
 -0.11497348037080715
 -0.08191664892303317
 -0.2838872967103638
 -0.3384879959637381

[chriselrod]

Finally merged the branch into master. I'll register shortly.