[Bug fortran/91690] Slow IEEE intrinsics

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91690

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
__builtin_isnan is required to preserve FPU state, not sure why the Fortran FE
thinks it needs some extra magic around it?