[Bug fortran/107071] gfortran.dg/ieee/modes_1.f90 fails on aarch64-linux

[fxcoudert at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107071

--- Comment #9 from Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> ---
OK so there are three things tested here:

- underflow mode
- rounding mode
- trapping mode

For glibc targets, underflow control is only marked as supported for the float
and double types on __alpha__. For rounding mode, the code makes incorrect
assumptions and I have proposed a prototype patch to
support_fpu_rounding_mode().

For trapping modes, it means that support_fpu_trap() needs to perform correct
runtime checks. As I understand, this can be done by calling feenableexcept()
and checking whether it returns -1 (flag not supported) or something else (flag
supported). Then I need to restore the flag with fedisableexcept(), if the flag
was not already set prior to the feenableexcept() call.

I will write a patch when I have time. Thanks for pointing the issue out to me.