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[Bug middle-end/35544] Error with -fprofile-use
- From: "pinskia at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 12 Mar 2008 06:50:34 -0000
- Subject: [Bug middle-end/35544] Error with -fprofile-use
- References: <bug-35544-9436@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #5 from pinskia at gcc dot gnu dot org 2008-03-12 06:50 -------
For reference see:
http://gcc.gnu.org/ml/gcc-patches/2007-01/msg01205.html
http://gcc.gnu.org/ml/gcc-patches/2005-03/msg00200.html
http://gcc.gnu.org/ml/gcc/2005-12/msg00215.html
And most likely a couple others too. I cannot find a good reference explaining
why early inline helps a lot for C++ code like tramp3d.
>Again, how much performance gain can be achieved with early optimization for
instrumented binary (which is slow anyway)?
IIRC there was a huge win (like a 10x speedup) for doing this.
> At least it is tricky with cross module inlining happening for instrumented
> functions -- the inline instances should really updating counters in the
> original routines.
Depends on if the inline is done with early inline or late and really really if
it is done with late, the counters will be emitted with the LTO file before
reading them back in so the counters will be correct already and inlining
becomes obvious.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35544