[Bug tree-optimization/116142] vec_widen_smult_{odd,even}_M ineffective for a simple widening dot product (vect_used_by_reduction is not set?)

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116142

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
To make it used by the reduction you'd need to have a dot_product covering the
accumulation as well.