Having the -mfused-madd option honored
Serge Torres
Serge.Torres@ens-lyon.fr
Fri Nov 9 09:16:00 GMT 2007
Hi,
> Just to be sure, have you compiled the program with optimization (such as -O,
> -O2, or -O3)? The GCC combiner that builds up complex insns like multiply and
> add is only run when optimizing. I happen to have a PowerPC cross compiler
> built from a few weeks ago, and it generates fmadd and fmadds instructions if I
> use -mcpu=power5 and -mfused-madd.
Yes, I tried again with -O -O2 and -O3. None worked. I had already
figured out that gcc would only trigger fmadd and fmasub as
optimizations. I also removed the options that enforce the C99
compliance, since fmad and fsub break the semantics of the operations
from the rounding point of view.
Thank four your help.
Regards,
Serge Torres
More information about the Gcc-help
mailing list