`@inline` with traits

[timholy]

In JuliaArrays/GetindexArrays.jl#3 (comment) I identified an issue in which SimpleTraits caused a nearly 5x performance hit. SimpleTraits was confirmed to be the source because changes like

@@ -414,9 +416,9 @@ StreamIndexStyle(S::StreamingContainer) = StreamIndexStyle(typeof(S))
 
 filter_space_axes(axes::NTuple{N,Axis}, items::NTuple{N,Any}) where {N} =
     _filter_space_axes(axes, items)
-@inline @traitfn _filter_space_axes(axes::Tuple{Ax,Vararg{Any}}, items) where {Ax<:Axis;  TimeAxis{Ax}} =
+@inline _filter_space_axes(axes::Tuple{<:Axis{:time},Vararg{Any}}, items) =
     _filter_space_axes(tail(axes), tail(items))
-@inline @traitfn _filter_space_axes(axes::Tuple{Ax,Vararg{Any}}, items) where {Ax<:Axis; !TimeAxis{Ax}} =
+@inline _filter_space_axes(axes::Tuple{<:Axis,Vararg{Any}}, items) =
     (items[1], _filter_space_axes(tail(axes), tail(items))...)
 _filter_space_axes(::Tuple{}, ::Tuple{}) = ()
 @inline _filter_space_axes(axes::Tuple{Ax,Vararg{Any}}, items) where {Ax<:Axis{:color}} =

to ImageAxes.jl (and several more similar changes) give the faster performance. I assume the problem is that the @inline annotation is not being applied, but I am unsure. I tried swapping the orders of @traitfn and @inline but it didn't seem to help.

[mauro3]

Thanks for the report! I assume you don't have an idea on how to fix this? From the macroexpand it looks like with either order the inline is applied:

julia> @macroexpand @inline @traitfn f(x::::TT) = 1
quote
    begin
        #= /home/mauro/julia/dot-julia-dev/SimpleTraits/src/SimpleTraits.jl:331 =#
        (f(x::var"##261") where var"##261") = begin
                #= /home/mauro/julia/dot-julia-dev/SimpleTraits/src/SimpleTraits.jl:331 =#
                $(Expr(:meta, :inline))
                #= /home/mauro/julia/dot-julia-dev/SimpleTraits/src/SimpleTraits.jl:331 =#
                f(SimpleTraits.trait(TT{var"##261"}), x)
            end
    end
    begin
        $(Expr(:meta, :doc))
        (f(::Type{TT{var"##261"}}, x::var"##261"; ) where var"##261") = begin
                $(Expr(:meta, :inline))
                #= REPL[5]:1 =#
                1
            end
    end
end

julia> @macroexpand @traitfn @inline f(x::::TT) = 1                                                                                                                                             
quote                                                                                                                                                                                           
    begin                                                                                                                                                                                       
        #= /home/mauro/julia/dot-julia-dev/SimpleTraits/src/SimpleTraits.jl:331 =#                                                                                                              
        (f(x::var"##259") where var"##259") = begin                                                                                                                                             
                #= /home/mauro/julia/dot-julia-dev/SimpleTraits/src/SimpleTraits.jl:331 =#                                                                                                      
                $(Expr(:meta, :inline))                                                                                                                                                         
                #= /home/mauro/julia/dot-julia-dev/SimpleTraits/src/SimpleTraits.jl:331 =#
                f(SimpleTraits.trait(TT{var"##259"}), x)
            end
    end
    begin
        $(Expr(:meta, :doc))
        (f(::Type{TT{var"##259"}}, x::var"##259"; ) where var"##259") = begin
                $(Expr(:meta, :inline))
                #= REPL[4]:1 =#
                1
            end
    end
end

For your example the $(Expr(:meta, :inline)) is also added. So, I'm not sure what's up.

[timholy]

I haven't looked. Thanks for checking! Profiling the test in that GetindexArrays issue I linked does reveal at least something about it (red bars in ProfileView, which indicate runtime dispatch), but I didn't really check further than that.

[mauro3]

Hm, runtime dispatch, that is even worse than not inlining!