Re: [PATCH, x86_64]: Use soft-fp for TFmode (128bit) FP.

["Joseph S. Myers" <joseph at codesourcery dot com>]

On Thu, 12 Apr 2007, Uros Bizjak wrote:

> This patch implements TFmode (128bit) floating point by using soft-fp for
> x86_64 targets. To support TImode FP-int conversions, a bunch of support files
> is added to soft-fp directory (+ a couple of small bugfixes, as can be seen in
> attached soft-fp diff).

The changes to existing soft-fp files certainly need to go in FSF glibc 
first.

Whether the new files need to go there is less clear; however, I would 
presume that they do need to do so unless RMS says otherwise.  They 
wouldn't be used in glibc by any existing glibc configuration, but since 
the code is shared with GCC this should not be fatal to their inclusion in 
glibc, and they could be useful in glibc for MIPS64 soft-float in future.

Is there any particular reason you didn't include conversions to/from 
XFmode (apart from my notes at 
<http://gcc.gnu.org/wiki/Software_floating_point> that you'd need some 
changes to the core soft-fp conversion macros to handle conversions 
between types with same normal exponent range but different mantissa 
size)?  What happens with such conversions with this patch?

If possible I'd say you should define FP_INIT_ROUNDMODE and 
FP_HANDLE_EXCEPTIONS in sfp-machine.h to use the hardware rounding mode 
and exceptions so that this type works like the other floating-point 
types.

-- 
Joseph S. Myers
joseph@codesourcery.com