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@xxxxxxxxxxx>
