Message ID | Y43dD0/eSrUNx/8Z@tucnak |
---|---|
State | New |
Headers | show |
Series | range-op-float: Improve multiplication reverse operation | expand |
On 12/5/22 12:59, Jakub Jelinek wrote: > On Mon, Dec 05, 2022 at 10:54:41AM +0100, Aldy Hernandez wrote: >>> Do you mind if I try that incrementally and only if it doesn't make the >>> code too large/too unreadable? >> >> Sure. And don't feel obligated to implement it either. range-ops is a >> never ending pit of possible optimizations. We found that out quite early >> in the design. >> >> If you don't get to it, could you at least add a comment? > > So like this for multiplication op1/2_range if it passes bootstrap/regtest? > For division I'll need to go to a drawing board... Sure, looks good to me. > > 2022-12-05 Jakub Jelinek <jakub@redhat.com> > > * range-op-float.cc (zero_to_max_range): New function. > (foperator_plus::op1_range): If lhs can't be INF nor NAN, > op1 can't be INF. > > --- gcc/range-op-float.cc.jj 2022-12-05 11:17:34.900573272 +0100 > +++ gcc/range-op-float.cc 2022-12-05 12:32:30.286753929 +0100 > @@ -2004,6 +2004,29 @@ zero_to_inf_range (REAL_VALUE_TYPE &lb, > } > } > > +// Set [lb, ub] to [-MAX, -0], [-MAX, +MAX] or [+0, +MAX] depending on > +// signbit_known. > +static void > +zero_to_max_range (REAL_VALUE_TYPE &lb, REAL_VALUE_TYPE &ub, tree type, > + int signbit_known) My apologies for having to passs around [lb, ub] everywhere. At least for rv_fold(), I'd like to rewrite it next year as: void rv_fold (frange &r, tree type, ...); ...instead of having to pass LB, UB, and maybe_nan as references. All the information in LB, UB, and maybe_nan can fit nicely in an frange. This is what we do in irange (wi_fold). It also sets us up nicely for when we have subranges, and we can union the result. I'll clean it up early next release. Aldy > +{ > + if (signbit_known > 0) > + { > + lb = dconst0; > + ub = real_max_representable (type); > + } > + else if (signbit_known < 0) > + { > + lb = real_min_representable (type); > + ub = real_value_negate (&dconst0); > + } > + else > + { > + lb = real_min_representable (type); > + ub = real_max_representable (type); > + } > +} > + > class foperator_plus : public range_operator_float > { > using range_operator_float::op1_range; > @@ -2159,7 +2182,14 @@ public: > // and perhaps if it can be NAN or not. > REAL_VALUE_TYPE lb, ub; > int signbit_known = signbit_known_p (lhs_lb, lhs_ub, op2_lb, op2_ub); > - zero_to_inf_range (lb, ub, signbit_known); > + // If lhs can't be +-INF nor NAN, then op1 can't be +-INF - > + // +-INF * anything is either +-INF or NAN (if op2 is +-0 or NAN). > + if (!real_isinf (&lhs_lb) > + && !real_isinf (&lhs_ub) > + && !lhs.maybe_isnan ()) > + zero_to_max_range (lb, ub, type, signbit_known); > + else > + zero_to_inf_range (lb, ub, signbit_known); > r.set (type, lb, ub); > } > // Otherwise, if op2 is a singleton INF and lhs doesn't include INF, > > > Jakub >
--- gcc/range-op-float.cc.jj 2022-12-05 11:17:34.900573272 +0100 +++ gcc/range-op-float.cc 2022-12-05 12:32:30.286753929 +0100 @@ -2004,6 +2004,29 @@ zero_to_inf_range (REAL_VALUE_TYPE &lb, } } +// Set [lb, ub] to [-MAX, -0], [-MAX, +MAX] or [+0, +MAX] depending on +// signbit_known. +static void +zero_to_max_range (REAL_VALUE_TYPE &lb, REAL_VALUE_TYPE &ub, tree type, + int signbit_known) +{ + if (signbit_known > 0) + { + lb = dconst0; + ub = real_max_representable (type); + } + else if (signbit_known < 0) + { + lb = real_min_representable (type); + ub = real_value_negate (&dconst0); + } + else + { + lb = real_min_representable (type); + ub = real_max_representable (type); + } +} + class foperator_plus : public range_operator_float { using range_operator_float::op1_range; @@ -2159,7 +2182,14 @@ public: // and perhaps if it can be NAN or not. REAL_VALUE_TYPE lb, ub; int signbit_known = signbit_known_p (lhs_lb, lhs_ub, op2_lb, op2_ub); - zero_to_inf_range (lb, ub, signbit_known); + // If lhs can't be +-INF nor NAN, then op1 can't be +-INF - + // +-INF * anything is either +-INF or NAN (if op2 is +-0 or NAN). + if (!real_isinf (&lhs_lb) + && !real_isinf (&lhs_ub) + && !lhs.maybe_isnan ()) + zero_to_max_range (lb, ub, type, signbit_known); + else + zero_to_inf_range (lb, ub, signbit_known); r.set (type, lb, ub); } // Otherwise, if op2 is a singleton INF and lhs doesn't include INF,