[maemo-developers] [maemo-developers] Strange behavior with -O3 CFLAGS on ARM

[From: Giuseppe Zompatori]

Il giorno lun, 08/08/2005 alle 18.02 -0300, Rudá Moura ha scritto:
> Well, in resume: pygame was never the problem, the problem was in
> compiling Python 2.4 with -O3 CFLAGS and then compiling PyGame with -O3,
> this just make bugged code for ARM. So I recompiled everything with -O2
> CFLAGS to be more conservative.
> 

Going "-O3" instead of "-O2" for production builds tends to produce
bigger executables which also tend to be buggier, bloated & slower as
opposed to faster.
This is something everyone with good gcc knowledge knows ;)

And the only really tested configuration from the FSS is "-O2 -g".

That said "-O2 -march=<insert your CPU here> -fomit-frame-pointer
-ffast-math" usually produces good code which is usually faster and not
as bloated as with "-O3" on most platforms.
The "-fomit-frame-pointer" bit can be left out on some platforms (as it
doesn't give any extra gain) and for debugging because it makes
debbugging impposible.

No go try to figure out how to tell this to people that put "-O6" in
their Makefiles and expect it to be faster than any other option.

Cheers,

-Giuseppe



	

	
		
___________________________________ 
Yahoo! Mail: gratis 1GB per i messaggi e allegati da 10MB 
http://mail.yahoo.it