best optimization under IRIX ?

Matthias Kurz mk@baerlap.north.de
Wed Sep 6 07:26:00 GMT 2000


On Wed, Sep 06, 2000 at 01:06:29PM +0000, Erik Mouw wrote:
> On Wed, 6 Sep 2000 05:20:36 +0200, Matthias Kurz wrote:
> > What are the optimization options that give the maximum speed on
> > a O2000/R10000 ?
> 
> I usually use (on an Onyx2/R12000):
> -O2 -mabi=n32 -mips4 -mcpu=r8000 -funroll-loops -fomit-frame-pointer

No effect. Well, it's like -funroll-all-loops, just the other direction,
that means somewhat slower. Hmmm, hope i'm not doing something silly.
I have to check twice.
It's gcc-2.95.2, maybe i'll try the current CVS later. Any hints for
configure options ?

> > Currently the native "cc" with "-32 -Ofast=IP27" generates code that runs
> > twice as fast as "gcc -mabi=n32 -O3 -mips3 -r4000". 
> 
> Depends a lot on the source code. I have examples where gcc-2.95.2
> generates code that runs three to four times as fast as the native MipsPRO
> C compiler.

Sure that no dnetc was running when you tested the MipsPRO results ? One
should shoot them... Or a screen saver ?
The cc code runs twice as fast on a R12000, again (did not try gcc,
i guess it will be also twice as fast). But then, the R12000/300 has 8MB
cache, while the R10000/180 has only 1MB.

> > I see neither -mips4 nor -r10000 in the man page.
> 
> The manpage is not up to date. Read the info files.

And break my fingers ? :-) I'll try.


   (mk)

-- 
Matthias Kurz; Fuldastr. 3; D-28199 Bremen; VOICE +49 421 53 600 47


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