GCC 3.2.1 Optimizations and Via C3 Ezra CPU

Bryan K. Walton zxcvbnm at tds.net
Tue Feb 17 10:54:28 PST 2004


Hi Joel,
	Thank you for your email.  Hmmm, now to decide whether I want
to spring for the newer C3s.

-Bryan

On Sat, Feb 14, 2004 at 10:29:51PM -0500, Joel Miller wrote:
> On Sat, 14 Feb 2004 21:04:36 -0600, Bryan K. Walton <zxcvbnm at tds.net> 
> wrote:
> 
> >Hi,
> >	I have a question regarding compiler optimizations for the Via
> >C3 Ezra processor. I did a little searching around on the web and found
> >this:
> >
> >CHOST="i586-pc-linux-gnu"
> >CFLAGS="-march=i586 -m3dnow -O3 -pipe -fomit-frame-pointer"
> >CXXFLAGS="-march=i586 -m3dnow -O3 -pipe -fomit-frame-pointer"
> >
> >Now, that makes sense to me.  However, when I issue a "uname -m" on
> >this box, it reports that it is a i686.  And sure enough, when I
> >compile gcc on this box, without any optimizations, it seems to be
> >identifying the host as i686-pc-linux-gnu.  Any ideas what might be
> >going on here.  Is gcc incorrectly identifying hardware on the box?
> >I'm using GCC 3.2.1.  Or can I specify i686 in those three
> >optimization lines?
> >
> >Thanks!!
> >Bryan Walton
> 
> IIRC the C3 processor is a 686 processor but it lacks the CMov instruction 
> that other 686 processors have. Thus default i686 instructions will call 
> CMOV and you will get an error stating an illegal instruction has been 
> called. I also seem to remember hearing that newer C3's didnt have this 
> problem. Take what I say with a grain of salt, as I'm trying to recall all 
> this from memory.
> 
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