On 06/16/2011 03:10 PM, Laurent Desnogues wrote: > On Thu, Jun 16, 2011 at 2:44 PM, Bernd Schmidt <ber...@codesourcery.com> > wrote: >> Several processors have a "count redundant sign bits" instruction: >> >> * SIGNBITS on Blackfin >> * NORM on C6X >> * SBC, apparently, on picochip > > picoChip defines __builtin_sbc. Wouldn't that make it redundant > with your __builtin_clrsb?
Yes. But the fact that many processors support the same operation suggests we shouldn't add a builtin function to every backend, but rather provide it as a general feature. > I'm not sure I like clrsb. The trailing 'b' looks superfluous if you > compare to clz. And clr looks too much like clear :-) Well, you would say "leading zeros" but not "leading signs". OTOH "leading" is redundant when talking about sign bits, so maybe "crsb"? I don't really care as long as the patch is otherwise approved :) Bernd
