[Bug regression/35671] GCC 4.4.x vs. 4.2.x performance regression

[t dot artem at mailcity dot com]

------- 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:

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-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 ...


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35671