[Bug fortran/78611] -march=native makes code 3x slower

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78611

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
It's hard to guess what happens, esp. w/o optimization the difference should
be minimal.

It would be nice if you can isolate the difference to a specific architecture
flag rather than native (-march=core-avx-i ?)