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

[t dot artem at mailcity dot com]

------- Comment #8 from t dot artem at mailcity dot com  2009-04-19 13:51 -------
If anyone cares to repeat my test results, here's a simple test case:

1) Obtain a large enough collection of WAV files (however I'm sure all other
compressible material will also fit this test). If you have wine emulator
installed you can get many large wav files by running this application
(http://www.scene.org/file.php?file=/demos/groups/farb-rausch/fr-028.zip&fileinfo)
- "record" all files to the same folder.

2) Compress your test folder with RAR archiver
(http://rarlabs.com/rar/rarlinux-3.8.0.tar.gz) using these parameters:

rar -r -m5 -mdG arhive_name.rar folder

3) Compile unrar (http://www.rarlab.com/rar/unrarsrc-3.8.5.tar.gz) with the
already given parameters.

See :)

(In reply to comment #7)
> For better speed with -march=pentium2 you should add -mtune=generic which
> will use only pentium2 features but tunes the code to not pessimize newer
> processors.
> 

As you can see 1) GCC 4.2 "pessimizes" code less than GCC 4.4, and 2) I'm sure
no new pentium2 optimizations have been introduced for the last two years - so
I'm sure general -O2 code produced by GCC 4.4 (and 4.3) is less optimized than
code produced by GCC 4.2.

At least it's quite obvious than most binaries are larger - but performance
benefit is not so clear.


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