On Thu, Mar 08, 2001 at 04:48:21PM +0100, Gabriel Paubert wrote: > -Os was faster than -O2 which was faster than -O3 for some routines.
I had similar results benchmarking our application on an 855T: -Os was both smallest and fastest on gcc-2.95.2. This makes sense since the I-cache on embedded CPUs is relatively small, and tighter/smaller code takes less time to fetch. The difference between -Os and -O2 in terms of speed and space were only very minor. -O3 made code larger and slower, by inlining functions and blowing the cache out too much; I'd strongly recommend against using it. My suggestion is that the best starting point is to use -Os. Regards, Graham -- Graham Stoney Assistant Technology Manager Canon Information Systems Research Australia Ph: +61 2 9805 2909 Fax: +61 2 9805 2929 ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
