On 04/07/2019 16:58, Matthew Wilcox wrote: > On Thu, Jul 04, 2019 at 04:00:00PM +0300, Boaz Harrosh wrote: <> >> Matthew you must be kidding an ilog2 in binary is zero clocks >> (Return the highest bit or something like that) > > You might want to actually check the documentation instead of just > making shit up. > Yes you are right I stand corrected. Must be smoking ;-) > https://www.agner.org/optimize/instruction_tables.pdf > > I think in this instance what we want is BSR (aka ffz) since the input is > going to be one of 0, 1, 3, 7, 15 or 31 (and we want 0, 1, 2, 3, 4, 5 as > results). > <> > The compiler doesn't know the range of 'sibs'. Unless we do the > profile-feedback thing. > Would you please consider the use of get_order() macro from #include <getorder.h> Just for the sake of understanding? (Or at least a comment) Thanks Boaz
