[Bug middle-end/105781] GCC does not unroll auto-vectorized loops.

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105781

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
The issue is cost modeling which is what the existing -funroll-[all-]loops RTL
unrolling lacks.  The vectorizer meanwhile can unroll vectorized loops by means
of increasing the vectorization factor which the target can suggest by
adjusting m_suggested_unroll_factor in the finish_cost hook.  See the aarch64
port for an example.