| Message ID | ZCKiZDm40JqnmjZi@tucnak |
|---|---|
| State | New |
| Headers | show |
| Series | [RFC] range-op-float: Only flush_denormals_to_zero for +-*/ [PR109154] | expand |
On 3/28/23 10:16, Jakub Jelinek wrote: > Hi! > > As discussed in the PR, flushing denormals to zero on every frange::set > might be harmful for e.g. x < 0.0 comparisons, because we then on both > sides use ranges that include zero [-Inf, -0.0] on the true side, and > [-0.0, +Inf] NAN on the false side, rather than [-Inf, nextafter (-0.0, -Inf)] > on the true side. > > The following patch does it only in range_operator_float::fold_range > which is right now used for +-*/ (both normal and reverse ops of those). > > Though, I don't see any difference on the testcase in the PR, but not sure > what I should be looking at and the reduced testcase there has undefined > behavior. > > Anyway, bootstrapped/regtested on x86_64-linux and i686-linux. LGTM. Aldy > > If it doesn't help with the PR, could be as well deferred for stage 1. > > 2023-03-28 Jakub Jelinek <jakub@redhat.com> > > PR tree-optimization/109154 > * value-range.h (frange::flush_denormals_to_zero): Make it public > rather than private. > * value-range.cc (frange::set): Don't call flush_denormals_to_zero > here. > * range-op-float.cc (range_operator_float::fold_range): Call > flush_denormals_to_zero. > > --- gcc/value-range.h.jj 2023-03-23 15:25:47.059741131 +0100 > +++ gcc/value-range.h 2023-03-27 18:56:35.164190929 +0200 > @@ -373,6 +373,7 @@ public: > void update_nan (tree) = delete; // Disallow silent conversion to bool. > void update_nan (const nan_state &); > void clear_nan (); > + void flush_denormals_to_zero (); > > // fpclassify like API > bool known_isfinite () const; > @@ -389,7 +390,6 @@ private: > bool union_nans (const frange &); > bool intersect_nans (const frange &); > bool combine_zeros (const frange &, bool union_p); > - void flush_denormals_to_zero (); > > tree m_type; > REAL_VALUE_TYPE m_min; > --- gcc/value-range.cc.jj 2023-03-27 12:50:45.876826415 +0200 > +++ gcc/value-range.cc 2023-03-27 18:45:50.127495492 +0200 > @@ -361,8 +361,6 @@ frange::set (tree type, > > normalize_kind (); > > - flush_denormals_to_zero (); > - > if (flag_checking) > verify_range (); > } > --- gcc/range-op-float.cc.jj 2023-03-27 13:28:18.847264635 +0200 > +++ gcc/range-op-float.cc 2023-03-27 18:50:24.498537727 +0200 > @@ -112,6 +112,8 @@ range_operator_float::fold_range (frange > } > } > > + r.flush_denormals_to_zero (); > + > return true; > } > > > Jakub >
--- gcc/value-range.h.jj 2023-03-23 15:25:47.059741131 +0100 +++ gcc/value-range.h 2023-03-27 18:56:35.164190929 +0200 @@ -373,6 +373,7 @@ public: void update_nan (tree) = delete; // Disallow silent conversion to bool. void update_nan (const nan_state &); void clear_nan (); + void flush_denormals_to_zero (); // fpclassify like API bool known_isfinite () const; @@ -389,7 +390,6 @@ private: bool union_nans (const frange &); bool intersect_nans (const frange &); bool combine_zeros (const frange &, bool union_p); - void flush_denormals_to_zero (); tree m_type; REAL_VALUE_TYPE m_min; --- gcc/value-range.cc.jj 2023-03-27 12:50:45.876826415 +0200 +++ gcc/value-range.cc 2023-03-27 18:45:50.127495492 +0200 @@ -361,8 +361,6 @@ frange::set (tree type, normalize_kind (); - flush_denormals_to_zero (); - if (flag_checking) verify_range (); } --- gcc/range-op-float.cc.jj 2023-03-27 13:28:18.847264635 +0200 +++ gcc/range-op-float.cc 2023-03-27 18:50:24.498537727 +0200 @@ -112,6 +112,8 @@ range_operator_float::fold_range (frange } } + r.flush_denormals_to_zero (); + return true; }