Re: [PATCH] PPC64 IEEE128 bit FP support

[Rich Felker <dalias@libc.org>]

On Fri, Oct 26, 2018 at 03:01:20PM +0200, Szabolcs Nagy wrote:
> * Markus Wichmann <nullplan@gmx.net> [2018-10-26 06:28:29 +0200]:
> > Now you just need to look through all the maths code to find all the
> > places that need changing. __floatscan() comes to mind immediately. And
> > I don't know if any of the libm functions needs adjustment for this new
> > format.
> 
> generic c code in musl should work for all supported
> floating-point formats, which includes ieee binary128
> for long double.
> 
> only float.h needs to be set up according to the abi.
> 
> some long double math functions don't have high quality
> implementations for ieee binary128 format though.

Yes. Assuming there aren't other problems revealed by my questions
about argument passing and ISA levels, I think the only blocking issue
here is naming the ABI. I forgot to mention but that should also
involve a gcc patch that we can put in mcm and eventually upstream.

QoI issues for IEEE-quad-based [sub]archs can be improved later;
aarch64 and s390x are already affected IIRC.

Rich