[PD] Hunting denormals?

Miller Puckette mpuckett at imusic1.ucsd.edu
Tue Nov 4 01:39:35 CET 2008


Yep, I remember trying the MXCSR thing once and it not working, but I
forget what processor it was on.  If indeed it's equivalent to using this
gcc flag, I'm happier usin the compiler flag because it keeps the code
cleaner.  
OTOH, it sounds like non-SSE processors will always need code to check things 
manually.

cheers
Miller

On Mon, Nov 03, 2008 at 10:25:55PM +0000, Tim Blechmann wrote:
> > Looking into this once again (I've had this problem for 10 years or more
> > now) I just found out that gcc has a -ffast-math flag that prevents
> > denormals for slowing the code down, as long as the CPU has SSE
> > instructions.  I don't know if the geode does or not, though!
> 
> according to wikipedia not all geode processors support sse 
> instructions ...
> the sse unit can be configured to handle denormals as zero, by setting 
> the MXCSR control register, no need to rely on specific compiler 
> flags ... iirc, i added the specific code to the devel_0_37 a few years 
> ago ...
> 
> tim
> 
> -- 
> tim at klingt.org
> http://tim.klingt.org
> 
> It is better to make a piece of music than to perform one, better to
> perform one than to listen to one, better to listen to one than to
> misuse it as a means of distraction, entertainment, or acquisition of
> 'culture'.
>   John Cage
> 
> 
> _______________________________________________
> Pd-list at iem.at mailing list
> UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list




More information about the Pd-list mailing list