On Fri, 25 Aug 2000, Antony Suter wrote:
>
> I think that this is in error. I understand from gcc 2.95 documentation that
> only one of the flags -m, -mcpu and -march need be specified.
>
> My understanding is that:-
> "-mcpu=pentium" specifies to optimise for the pentium but allow to run on
> other cpus.
> "-march=pentium" specifies to optimise fully for the pentium, dropping
> compatibility for other cpus.
>
That's it. The cpu= stuff provides optimal instruction ordering for
Pentiums (note that this same order differs for PPro and upper!) whereas the
arch= introduces arch specific instructions.
> I think that it is non optimal to specify both -mcpu and -march at the same
> time.
Well, it is - for Pentiums. Ppros run fine with it too, at least faster than
without any of these. I don't know what the -mpentium is for.
Oh, one last thing: using fast-math is tricky, especially for apps expecting
full IEEE compliance. Try at all possible NOT to use it.
--
Francis Galiegue, [EMAIL PROTECTED]
"Programming is a race between programmers, who try and make more and more
idiot-proof software, and universe, which produces more and more remarkable
idiots. Until now, universe leads the race" -- R. Cook
