Re: [Fortran] half-cycle trig functions and atan[d] fixes

[FX Coudert <fxcoudert@gmail.com>]

Hi Steve,

Thanks for the patch. I’ll take time to do a proper review, but after a first read I had the following questions:

- "an OS's libm may/will contain cospi(), etc.”: do those functions conform to any standard? Are there plans to implement them outside FreeBSD at this point?

- On systems where libquadmath is used for _Float128, does libquadmath contain the implementation of the q() variants for those functions?

- If I get this right, to take one example, the Fortran front-end will emit a call to gfortran_acospi_r4(), libgfortran provides this as a wrapper calling acospif(), which is called either from libm or from libgfortran. This is different from other math library functions, like ACOS() where the acosf() call is generated directly from the front-end (and then the implementation comes either from libm or from libgfortran). Why not follow our usual way of doing things?

- On most targets, cospi() and friends are not available. Therefore, we end up doing the fallback (with limited precision as you noted) but with a lot of indirection. We could generate that code directly in the front-end, couldn’t we?


Best,
FX