Re: [PATCH] [2.4] [2.5] [i386] Add support for GCC 3.1 -march=pentium{-mmx,3,4}

Dave Jones
2002-05-29T11:42:05Z

On Mon, May 27, 2002 at 08:53:02AM +0000, Pavel Machek wrote:
> Hi!
>
> > I would be (pleasantly) surprised to see gcc turn a C memcpy into faster
> > assembly than our current implementation. And I'll bet
>
> gcc has hand-coded assembly inside itself, if gcc compiled memcpy is slower
> than hand-optimized one, you found a compiler bug.

Not at all. gcc compiled memcpy just has no knowledge of things like
non-temporal stores, and using mmx/sse to move 64 bits at a time instead
of 32 bit registers. (It's only recently it got prefetch abilities too).

--
| Dave Jones. http://www.codemonkey.org.uk
| SuSE Labs