Inf and NaN have been handled at speed at least as far back as Core (probably on P4 too, but I'm not certain, as I never really worked with those). [edit: I’m r

Inf and NaN have been handled at speed at least as far back as Core (probably on P4 too, but I'm not certain, as I never really worked with those). [edit: I’m referring to SSE/AVX; I forget that there are people who still use x87, where this stall is still around]. Denormal stalls, which are on the order of 100x, started to go away for addition in SNB. (IIRC, AMD doesn't handle denormals at speed either, but I'd need to double-check that).