-fprofile-generate and -fprofile-use

[girish vaitheeswaran]

I have tried with gcc 3.4.4 and still see the same
20%slowdown. If you folks are able to crack this, do
let me know.  On my earlier attempts I had tried to
disable all of the flags that feedback optimization
turns on (except the ones that are turned on by
default) and still got the 20% slowdown.
Is there something that you would want me to try out
wrt to enabling/disabling certain flags, i'd be happy
to. The versions I have tried out so far are 
2.95,3.4.3 and 3.4.4

-girish

--- Jan Hubicka <jh@suse.cz> wrote:

> > 
> > There was some discussion a few weeks ago about
> some apps running slower
> > with FDO enabled.
> > 
> > I've recently investigated a similar situation
> using mainline.  In my case,
> > the fact that the loop_optimize pass is disabled
> during FDO was the cause
> > of the slowdown.  It appears that was recently
> disabled as part of Jan
> > Hubicka's patch to eliminate RTL based profiling. 
> The commentary indicates
> > that the old loop optimizer is incompatible with
> tree profiling.
> > 
> > While this doesn't explain all of the degradations
> discussed (some were
> > showing up on older versions of the compiler), it
> may explain some.
> 
> Do you have specific testcase?  It would be
> interesting to see if new
> optimizer can catch up at least on kill-loop branch.
> 
> Thanks for investigating!
> Honza
> > 
> > Pete
>