------- Additional Comments From jbucata at tulsaconnect dot com 2005-07-18
21:11 -------
FWIW, I'm trying 4.1.0 beta 20050716, and it does better than 4.0.1.
-funroll-loops still slows it down (about 0.5s vs without it), but without, 4.1
shaves about 1.5 seconds off user time vs 4.0.1 (about 9.5s => 8.0s, or 15%
savings). It even does better than 3.4.3.
So maybe it's forgivable if -funroll-loops hurts 4.1's performance a bit, given
how much its base performance has improved over its predecessors. (Maybe the
fact that -funroll-loops on 3.4.3 helped so much was that 3.4.3 simply generated
bad code without it.)
On 4.1, -fprofile-{generate,use} hurts another 0.1s on top of -funroll-loops.
This was all with: -O3 -march=athlon-xp -fomit-frame-pointer (forgot -static,
but in a quick test it didn't seem to help significantly)
So perhaps this isn't a big deal now after all, though I'd like to think that
the PO, a feature to enhance performance, wouldn't hurt code performance *at
all*, either directly or indirectly (by requiring -funroll-loops).
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21527
