https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118175
Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |alias --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Looks like an alias issue. Changing the matrix definitions to: extern float matA[], matB[], matC[]; Allows GCC to vectorize the loop even for x86_64.