HEADS DOWN

[Kostik Belousov]

On Sun, May 06, 2007 at 10:59:23AM +1000, Bruce Evans wrote:
> The setup overhead for using string instructions may be much larger than
> the 14-16 in the above table.  It is also necessary to set the direction
> flag and maybe to shuffle registers so as to use the registers required
> by the string instructions.  cld/std is fast enough on Athlons (1/2
> cycles) but is slow on Pentium4 and later (IIRC, 43 cycles for std on
> one Pentium model).
gcc 4.3 claims to not issue cld instruction anymore (ABI requires direction
flag to be clear since eon).
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