https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91573
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- >2) If WIDTH is larger. e.g. #define WIDTH 16 Either we are unrolling the loop and not doing SLP on the following loop or it is a cost issue saying it is not profitable for some reason. Use -fno-vect-cost-model to disabled the cost model. You can also use -fdump-tree-all-details to find out about the cost model or use -fopt-info option.