Bruce Cran wrote: > I'm afraid you're wrong - the V2SI datatype and MMX functions > automatically become available after -march=pentium2, while > with other processor types you've got to explicitly add -mmmx. > -msse is presumed with -march=pentium3 and up. I'm afraid I'm not; I was talking strictly about -march=pentiumpro, not -march=pentium2 et cetera.
> ... I've seen code which runs 40x faster when compiled for > athlon-xp than for i386, and I would guess that a lot of that > is because of clever use of sse and mmx. That wasn't an > audio/video program, it was the libgmp arbitrary precision maths > package. MMX won't help you even a bit in precise mathematical calculations, unlike SSE. Also, if you're familiar with the way how MMX works, you won't enable it when compiling any application that requires heavy floating-point computations, because constant switching between MMX unit and FPU results in significant latency. > Also, I'm sure most people wouldn't say no to 50% more processing > speed for free! I didn't mean to stop using MMX at all; I only intended to note that there is no need to enable it for _all_ applications. > So, if you've got a pentium, k6 or pentiumpro which supports MMX, > you _do_ need to explicitly add -mmmx, but for other processors > it's implied. You didn't pay enough attention to my original post; PPro doesn't support MMX. Though, you can specify -mmmx anyway, if you feel comfortable with SIGILLs. --- Regards, Rhett __________________________________________________ Do you Yahoo!? Yahoo! Tax Center - forms, calculators, tips, more http://taxes.yahoo.com/ To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-current" in the body of the message
