Specialize for strided contiguous SubArrays

Author: jishnub

src/generic.jl

@@ -2004,8 +2004,8 @@ function isapprox(x::AbstractArray, y::AbstractArray;
     atol::Real=0,
     rtol::Real=Base.rtoldefault(promote_leaf_eltypes(x),promote_leaf_eltypes(y),atol),
     nans::Bool=false, norm::Function=norm)
+    Base.promote_shape(size(x), size(y)) # ensure compatible size
     d = if isempty(x) && isempty(y)
-        Base.promote_shape(size(x), size(y)) # ensure same size
         norm(zero(eltype(x)) - zero(eltype(y)))
     else
         norm_x_minus_y(x, y)
@@ -2020,8 +2020,8 @@ function isapprox(x::AbstractArray, y::AbstractArray;
 end
 
 norm_x_minus_y(x, y) = norm(x - y)
-function norm_x_minus_y(x::Array, y::Array)
-    Base.promote_shape(size(x), size(y)) # ensure same size
+const ArrayOrFastContiguousSubArrayStrided = Union{Array, FastContiguousSubArrayStrided}
+function norm_x_minus_y(x::ArrayOrFastContiguousSubArrayStrided, y::ArrayOrFastContiguousSubArrayStrided)
     norm(Iterators.map(splat(-), zip(x,y)))
 end