https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107569
--- Comment #34 from Jakub Jelinek <jakub at gcc dot gnu.org> --- (In reply to Aldy Hernandez from comment #33) > (In reply to Jakub Jelinek from comment #31) > > Created attachment 53873 [details] > > gcc13-pr107569-div.patch > > > > This is what I meant by complete nightmare - division. > > We can take this to gcc-patches when you're done, but just a few thoughts... > > + // If +-0.0 is in both ranges, it is a maybe NAN. > + if (real_compare (LE_EXPR, &lh_lb, &dconst0) > + && real_compare (GE_EXPR, &lh_ub, &dconst0) > + && real_compare (LE_EXPR, &rh_lb, &dconst0) > + && real_compare (GE_EXPR, &rh_ub, &dconst0)) > > Perhaps we could provide frange::contains_zero_p ()? Well, contains_p in irange is a method on the value range, while here we don't have a frange, but just naked REAL_VALUE_TYPEs. It is twice contains_zero_p... > > + // +-0.0 / +-0.0 or +-INF / +-INF is a known NAN. > + if ((real_iszero (&lh_lb) > + && real_iszero (&lh_ub) > + && real_iszero (&rh_lb) > + && real_iszero (&rh_ub)) > > This looks like frange::contains_zerp_p () as well. No, this is twice zero_p. Due to signed zeros it isn't a singleton + contains_zero_p, just both boundaries are zero. > + || (real_isinf (&lh_lb) > + && real_isinf (&lh_ub, real_isneg (&lh_lb)) > + && real_isinf (&rh_lb) > + && real_isinf (&rh_ub, real_isneg (&rh_lb)))) > > Note that, real_isinf with only one argument checks for +-INF. I know. I'm intentionally using one and 2 argument ones to verify that lh is either [INF,INF] or [-INF,-INF], but not [-INF,INF]. > But I think > what you're looking for is frange::maybe_isinf. Again, that works on frange, which I don't have here. > > Could your patch be simplified with some of these? > > // fpclassify like API > bool known_isfinite () const; > bool known_isnan () const; > bool known_isinf () const; > bool maybe_isnan () const; > bool maybe_isnan (bool sign) const; > bool maybe_isinf () const; > bool signbit_p (bool &signbit) const; > bool nan_signbit_p (bool &signbit) const; > > We should ultimately avoid peeking at the end points unnecessarily in order > to prepare ourselves for next release when we (hopefully) have sub-ranges. No, see above (at least for now). The peeking at the end points is needed because those end points behave weirdly.
