[Bug libfortran/93871] COTAN is slow for complex types

[sgk at troutmask dot apl.washington.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93871

--- Comment #42 from Steve Kargl <sgk at troutmask dot apl.washington.edu> ---
On Wed, Mar 04, 2020 at 04:35:02PM +0000, thenlich at gcc dot gnu.org wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93871
> 
> --- Comment #41 from Thomas Henlich <thenlich at gcc dot gnu.org> ---
> One would assume that fast FMA
> (https://en.wikipedia.org/wiki/FMA_instruction_set) is or will be available to
> the modern Fortran enthusiast, in the year 202x.
> 

It already is.  F2018, 17.11.3 IEEE_FMA.

gfortran currently does not implement IEEE_FMA along
with a few additional IEEE_ARITHMETIC features added
in F2018.

Note, gcc/builtins.def has fma, fmaf, and fmal covered.
We'll need a mapping in libquadmath if it has a __float128
fma.