tech-userlevel archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]

Re: clang support flagging



On Tue, 5 Jun 2012 14:03:55 +0200
Joerg Sonnenberger <joerg%britannica.bec.de@localhost> wrote:

> On Tue, Jun 05, 2012 at 12:58:09AM -0400, James K. Lowden wrote:
> > Bringing locales and 80-bit floating point to NetBSD seems to be a
> > matter of porting.  FreeBSD has both, and cephes has most of the C99
> > math.  
> 
> The second part is not true. FreeBSD does not have complete long
> double support, they just cheat by aliasing most to the double
> version. 

http://svnweb.freebsd.org/base/stable/9/lib/msun/src/s_fminl.c?revision=225736&view=markup

I'm not sure what "aliasing" you're referring to.  

The implementation for sqrtl() is here, 

http://svnweb.freebsd.org/base/stable/9/lib/msun/src/e_sqrtl.c?revision=225736&view=markup

starting on line 75.  It might be slow, but afaict it does use 
80 bits.  It certainly works better than ours.  

> I also don't agree that long double support is that support,
> given the significant performance penalty on modern x86 cpus.

Performance is not a factor for compliance.  

Many C++ programs do not need long-double math, or don't use it in ways
that make performance critical.  A slow implementation can be later
optimized; non-implementation prevents use of the library.  

--jkl


Home | Main Index | Thread Index | Old Index