[Bug tree-optimization/91201] [7~9 Regression] SIMD not generated for horizontal sum of bytes in array

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91201

--- Comment #1 from Marc Glisse <glisse at gcc dot gnu.org> ---
We unroll the loop (-fdisable-tree-cunrolli) and SLP does not handle
reductions.