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[Bug regression/35671] GCC 4.4.x vs. 4.2.x performance regression
- From: "t dot artem at mailcity dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 18 Apr 2009 08:18:03 -0000
- Subject: [Bug regression/35671] GCC 4.4.x vs. 4.2.x performance regression
- References: <bug-35671-5637@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #6 from t dot artem at mailcity dot com 2009-04-18 08:18 -------
Many Linux distros compile binaries for a common lowest denominator so that you
could run a distro on very old computers and CPUs - their developers in most
cases choose -march=i686 or -march=i586.
I compile binaries which I have to run on very old computers like Pentium 2,
that's why I chose -march=pentium2 in the first place. Let's go back to the
results:
________________________________________________________
-march=i386 -O2 -pipe -ftree-vectorize
unrar-424 size: 169384 time: 1m34.372s
unrar-440 size: 175836 time: 1m32.014s
Without CPU optimizations a binary produced by GCC 4.4.0 is larger but a bit
faster.
________________________________________________________
-march=native -O2 -pipe -ftree-vectorize
unrar-424 size: 180488 time: 1m17.608s
unrar-440 size: 188348 time: 1m27.211s
With native CPU optimizations a binary produced by GCC 4.4.0 is again larger
but noticeably slower.
________________________________________________________
Pentium2 results have been already posted.
This is the second major release of GCC which produces subpar results ...
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35671