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-fprofile-generate and -fprofile-use
- From: girish vaitheeswaran <girish_vaithees at yahoo dot com>
- To: gcc at gcc dot gnu dot org
- Date: Wed, 20 Jul 2005 09:53:23 -0700 (PDT)
- Subject: -fprofile-generate and -fprofile-use
I am seeing a 20% slowdown with feedback optimization.
Does anyone have any thoughts on this.
These are the steps I followed
1. Compiled the application using -fprofile-generate.
I used this flag both in the compile flags and as part
of the link flags. I also had to use libgcov.a during
the link phase otherwise it would die looking for gcov
functions.
2. Ran a representative work-load
3. Followed (1) except that instead of
-fprofile-generate used -fprofile-use
I had to drop the "-fprofile-use" on 2 files as they
had corrupted profile data. I have tried this
experiment with -fprofile-arc and
-fbranch-probabilities as well and I get the same 20%
slowdown.
Thx
-girish