Re: long double on ppc-darwin

[Geoff Keating <geoffk at geoffk dot org>]

On 17/12/2005, at 5:56 PM, Mike Stump wrote:

> On Dec 17, 2005, at 6:08 AM, FX Coudert wrote:
>
> > I'm trying to understand the gfortran failure  
> > large_real_kind_2.F90 on ppc-darwin7.9, which can be reduced to:
> >
> > $ cat large_real_kind_2.F90
> >   real(kind=16) :: x
> >   real(8) :: y
> >
> >   x = 1
> >   y = x
> >   x = cos (x)
> >   y = cos (y)
> >   print *, x, y, y-x
> >
> >   end
> > $ ./usr/local/gfortran/bin/gfortran -g large_real_kind_2.F90 && ./ 
> > a.out
> >   0.5403023058681397650104827000000        0.540302305868140        
> > 1.9841535727186827560257490000000E-0004
> >
> > But I can't make a C testcase for that. Is "long double" supposed  
> > to be usable on ppc-darwin7.9 ?
>
> The trick is that things like sinl have a linker name like _sinl 
> $LDBL128.  This is to enable 8 byte long doubles to continue to  
> work, and _sin is an 8 byte long double routine.  Don't ask.   
> Binary compatibility is so very much fun.
>
> Since Geoff invented the scheme, I'm sure he had an idea of how he  
> thought it should work for Fortran.  My guess would be that gcc has  
> to pick the right library names internally for all languages, thus,  
> obviating the need for the asm () fun remap the names in C.

Yes; to do this right, GCC's builtins need to know about the  
different names.

If you're interested in fixing this, I can tell you what to do...

Attachment: smime.p7s
Description: S/MIME cryptographic signature