Volunteering/Consulting for libm Development in glibc

[Joseph Myers]

On Tue, 18 Feb 2025, Ayan Shafqat wrote:

> Joseph (and everyone):
> 
> Thank you very much for the detailed explanation and clarifications. I
> am indeed eager to work on adding _Float16 support (and potentially
> other C23-related libm functions) in glibc, but given the extent of the
> work, it would require my full-time commitment (We can discuss this
> separately). I plan to start by checking in with the #gcc team regarding
> the compiler’s current status for _Float16, then move forward with
> glibc-side tasks.

I think these projects are not very suitable for people who are beginners 
to glibc development, since they are much more about a thorough 
understanding of how all the pieces in glibc fit together and the issues 
associated with the many different configurations supported by glibc (and 
ABI considerations, support for different compiler versions for building 
code with glibc, ...), than about floating-point function implementation.  
Improvements to individual functions (that are already present in glibc) 
are more suitable for people familiar with floating point but not more 
broadly with the full range of glibc configurations and development 
principles.

<tgmath.h> is another example of something tricky involved with _Float16 
support - where there are at least four different cases to test and 
consider (GCC <= 6, GCC 7, GCC 8 to 12, GCC >= 13) - though Arm __fp16 was 
too restricted to be usable in place of _Float16 so the GCC <= 6 case may 
not actually be relevant for _Float16.

-- 
Joseph S. Myers
josmyers@redhat.com