[Bug target/63599] "wrong" branch optimization with Ofast in a loop

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63599

--- Comment #3 from Marc Glisse <glisse at gcc dot gnu.org> ---
ifcvt making a transformation that doesn't help vectorization and ends up
pessimizing the code... not really the first time this happens. I believe Jakub
had a big patch for that, but it never got in. Maybe vectors could be
special-cased if we never vectorize them anyway.