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

rguenth at gcc dot gnu.org gcc-bugzilla@gcc.gnu.org
Wed Jun 1 11:49:38 GMT 2022


--- 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.

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