Products of sparse by dense matrices don't revert to specialized methods

General Usage
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1

Apparently in 1.7.2 the product of a sparse (SparseMatrixCSC) and a dense matrix (both directions) never use the specialized method. Looking at this old discussion it seems that at least the sparse by dense product should be handled by SparseArrays.

julia> using BenchmarkTools, SparseArrays, LinearAlgebra

julia> A = sprand(100,100,0.01)
julia> B = rand(100,100)
julia> C = A*B

julia> println(typeof(A))
SparseMatrixCSC{Float64, Int64}

julia> println(typeof(B))
Matrix{Float64}

julia> println(typeof(C))
Matrix{Float64}

julia> @which mul!(C, A, B)
mul!(C, A, B) in LinearAlgebra at /Applications/Julia-1.7.app/Contents/Resources/julia/share/julia/stdlib/v1.7/LinearAlgebra/src/matmul.jl:274

julia> @which mul!(C, B, A)
mul!(C, A, B) in LinearAlgebra at /Applications/Julia-1.7.app/Contents/Resources/julia/share/julia/stdlib/v1.7/LinearAlgebra/src/matmul.jl:274
2

On 1.9, I’m seeing *(X::AdjOrTransDenseMatrix, A::SparseMatrixCSCUnion{TvA}) and *(A::SparseMatrixCSCUnion{TA}, B::AdjOrTransDenseMatrix)