> On Wed, Jul 20, 2005 at 10:45:01AM -0700, girish vaitheeswaran wrote: > > > --- Steven Bosscher <[EMAIL PROTECTED]> wrote: > > > > > > > On Wednesday 20 July 2005 18:53, girish vaitheeswaran wrote: > > > > > I am seeing a 20% slowdown with feedback optimization. > > > > > Does anyone have any thoughts on this. > > > > > > > > My first thought is that you should probably first > > > > tell what compiler > > > > you are using. > > > > I am using gcc 3.4.3 > > -girish > > Which platform? I've seen slower code for profile-directed optimizations > on powerpc64-linux with GCC 4.0 and mainline. It's a bug, but I haven't > looked into it enough to provide a small test case for a problem report.
Actually I would be very interested in seeing testcases such as those. (and the Girish' slowdown too if possible). In general some slowdowns in side corners are probably unavoidable but both 3.4.3 and 4.0 seems to have pretty consistent improvements with profiling at least for SPEC and i386 I am testing pretty regularly. Such slodowns usually indicate problems like incorrectly updated profile or incorrectly readed in profile because of missmatch in CFGs in between profile and feedback run that are rather dificult to notice and hunt down... Honza > > Janis
