On Mon, 2004-11-29 at 10:16 +0100, Arjan van de Ven wrote:
On Mon, Nov 29, 2004 at 01:02:46AM -0800, Nicholas Miell wrote:
> CMOVcc will use less space in the instruction cache than the Jcc/MOV
> pair, though.
only sometimes.... since cmov doens't work on all register/memory
combinations extra code might be needed to glue that together...
.... and we're suddenly talking about 0.01% performance ;)
Well, yeah. :)
There's also branch prediction and decode bandwidth issues that I didn't
bother to mention.
But, if you're going to optimize for i686 or better for other reasons,
there's no reason not to use CMOVcc instead of Jcc/MOV, where possible.
Not that you'll ever notice the difference...
--
Nicholas Miell <nmiell(a)comcast.net>