[arch-ports] [arch-dev-public] x86_64: improving default CFLAGS

[Andreas Radke]

Am Tue, 3 Apr 2007 16:40:20 -0500
schrieb "Aaron Griffin" <aaronmgriffin at gmail.com>:

> > > to not break backward compatibility for those few early cpus that
> > > lack SSE3 extensions we want to do it with -mtune. this is how we
> > > want to set it for the future:
> > >
> > > CFLAGS="-march=x86-64 -mtune=nocona -O2 -pipe"
> > > CXXFLAGS="-march=x86-64 -mtune=nocona -O2 -pipe"
> 
> I don't know the details, so I assumed you looked into it all.  Just
> in case: what 64bit processors does this "leave in the dust".
> 
> Dropping support for some processors is not a huge problem (the age
> old Via C3 + Arch problem), but i think it might be important to put a
> blurb somewhere saying "If you have an XYZ processor, you need to use
> the arch i686".
> 

i don't want to drop support for any early x86_64 cpu.

that's why i want to use "mtune". code will be optimized for SSE3
capable cpus but will still run on non SSE3 capable processors. that's
the difference mtune to march.

i686 had something similar prepared in the old makepkg.conf

i don't expect a big gain at all but in certain multimedia apps it can
speedup things a lot. so why not make use of the additional registers?
apps *might* run a little bit slower if they cannot make use of the
additional flags and will it probably raise the pkg size a bit. but it
should be still worth it.

Andy