Re: Linux doesn't follow x86/x86-64 ABI wrt direction flag

Michael Matz
2008-03-07T14:09:56Z

Hi,

On Thu, 6 Mar 2008, Andi Kleen wrote:

> To be realistic it is very unlikely anybody will measure a difference
> from a few more or a few less clds in a program.

Only an assumption, and in fact wrong. See upthread for a benchmark.
IIRC Uros also made measurements to justify the removal of cld (on P4 I
think), where it helps tremendously on small memcpy loops.

Ciao,
Michael.