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

[xry111 at gcc dot gnu.org via Gcc-bugs]

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

--- Comment #5 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
And if I add sdot_prodv8hi it works for the test case 1 as expected, but not
the test case 2.