Re: [PATCH] define WIDEST_HARDWARE_FP_SIZE on mips

[Laurent GUERBY <laurent at guerby dot net>]

On Wed, 2009-03-04 at 23:19 +0000, Joseph S. Myers wrote:
> On Wed, 4 Mar 2009, Laurent GUERBY wrote:
> 
> > $ bc -l
> > scale = 18
> > e (1)
> > 2.718281828459045235
> > Ada expects:
> > 2.71828182845904524
> > which seems coherent with bc
> > 128 bit mips soft fp seems to return:
> > 2.71828182845904509
> > which seems wrong in the two last digits. Now I don't know
> > who provides the 128 bits soft FP code, and there
> > may be something wrong before we reach such code.
> 
> An obvious question would be whether you have a recent enough glibc 
> version (2.5-ish or later) to provide 128-bit long double versions, and 
> whether the libm function expl (rather than exp) is indeed being called.  
> Also, if you do not have my patch

I checked and GLIBC is 2.7-18 (debian) and the Ada RTS as currently
configured calls the C "exp" with a 64 bits args and results and not the
needed "expl" with 128 bits args which explains the cxg results.

I will do an experiment with a specific gcc/ada/a-numaux-longdouble.ads
when abi=64 and report what ACATS says but since the current GNAT will
call the same set of functions for all FP types it won't go into
production :).

Thanks for your help on this issue,

Laurent