Message ID | Y5C54d2clIOm0hrr@tucnak |
---|---|
State | New |
Headers | show |
Series | range-op-float, v2: frange_arithmetic tweaks for MODE_COMPOSITE_P | expand |
OK, thanks. Aldy On 12/7/22 17:05, Jakub Jelinek wrote: > On Wed, Dec 07, 2022 at 04:38:14PM +0100, Aldy Hernandez wrote: >>> So, perhaps a combination of that, change frange_nextafter to do the above >>> and change frange_arithmetic for the initial inexact rounding only to >>> do it by hand using range_nextafter and starting from value. >> >> Either way is fine. Whatever is cleaner. > > Now in patch form: > > 2022-12-07 Jakub Jelinek <jakub@redhat.com> > > * range-op-float.cc (frange_nextafter): For MODE_COMPOSITE_P from > denormal or zero, use real_nextafter on DFmode with conversions > around it. > (frange_arithmetic): For mode_composite, on top of rounding in the > right direction accept extra 1ulp error for PLUS/MINUS_EXPR, extra > 2ulps error for MULT_EXPR and extra 3ulps error for RDIV_EXPR. > > --- gcc/range-op-float.cc.jj 2022-12-07 12:46:01.536123757 +0100 > +++ gcc/range-op-float.cc 2022-12-07 16:58:02.406062286 +0100 > @@ -254,10 +254,21 @@ frange_nextafter (enum machine_mode mode > REAL_VALUE_TYPE &value, > const REAL_VALUE_TYPE &inf) > { > - const real_format *fmt = REAL_MODE_FORMAT (mode); > - REAL_VALUE_TYPE tmp; > - real_nextafter (&tmp, fmt, &value, &inf); > - value = tmp; > + if (MODE_COMPOSITE_P (mode) > + && (real_isdenormal (&value, mode) || real_iszero (&value))) > + { > + // IBM extended denormals only have DFmode precision. > + REAL_VALUE_TYPE tmp, tmp2; > + real_convert (&tmp2, DFmode, &value); > + real_nextafter (&tmp, REAL_MODE_FORMAT (DFmode), &tmp2, &inf); > + real_convert (&value, mode, &tmp); > + } > + else > + { > + REAL_VALUE_TYPE tmp; > + real_nextafter (&tmp, REAL_MODE_FORMAT (mode), &value, &inf); > + value = tmp; > + } > } > > // Like real_arithmetic, but round the result to INF if the operation > @@ -324,21 +335,40 @@ frange_arithmetic (enum tree_code code, > } > if (round && (inexact || !real_identical (&result, &value))) > { > - if (mode_composite) > + if (mode_composite > + && (real_isdenormal (&result, mode) || real_iszero (&result))) > { > - if (real_isdenormal (&result, mode) > - || real_iszero (&result)) > - { > - // IBM extended denormals only have DFmode precision. > - REAL_VALUE_TYPE tmp; > - real_convert (&tmp, DFmode, &value); > - frange_nextafter (DFmode, tmp, inf); > - real_convert (&result, mode, &tmp); > - return; > - } > + // IBM extended denormals only have DFmode precision. > + REAL_VALUE_TYPE tmp, tmp2; > + real_convert (&tmp2, DFmode, &value); > + real_nextafter (&tmp, REAL_MODE_FORMAT (DFmode), &tmp2, &inf); > + real_convert (&result, mode, &tmp); > } > - frange_nextafter (mode, result, inf); > + else > + frange_nextafter (mode, result, inf); > } > + if (mode_composite) > + switch (code) > + { > + case PLUS_EXPR: > + case MINUS_EXPR: > + // ibm-ldouble-format documents 1ulp for + and -. > + frange_nextafter (mode, result, inf); > + break; > + case MULT_EXPR: > + // ibm-ldouble-format documents 2ulps for *. > + frange_nextafter (mode, result, inf); > + frange_nextafter (mode, result, inf); > + break; > + case RDIV_EXPR: > + // ibm-ldouble-format documents 3ulps for /. > + frange_nextafter (mode, result, inf); > + frange_nextafter (mode, result, inf); > + frange_nextafter (mode, result, inf); > + break; > + default: > + break; > + } > } > > // Crop R to [-INF, MAX] where MAX is the maximum representable number > > > Jakub >
--- gcc/range-op-float.cc.jj 2022-12-07 12:46:01.536123757 +0100 +++ gcc/range-op-float.cc 2022-12-07 16:58:02.406062286 +0100 @@ -254,10 +254,21 @@ frange_nextafter (enum machine_mode mode REAL_VALUE_TYPE &value, const REAL_VALUE_TYPE &inf) { - const real_format *fmt = REAL_MODE_FORMAT (mode); - REAL_VALUE_TYPE tmp; - real_nextafter (&tmp, fmt, &value, &inf); - value = tmp; + if (MODE_COMPOSITE_P (mode) + && (real_isdenormal (&value, mode) || real_iszero (&value))) + { + // IBM extended denormals only have DFmode precision. + REAL_VALUE_TYPE tmp, tmp2; + real_convert (&tmp2, DFmode, &value); + real_nextafter (&tmp, REAL_MODE_FORMAT (DFmode), &tmp2, &inf); + real_convert (&value, mode, &tmp); + } + else + { + REAL_VALUE_TYPE tmp; + real_nextafter (&tmp, REAL_MODE_FORMAT (mode), &value, &inf); + value = tmp; + } } // Like real_arithmetic, but round the result to INF if the operation @@ -324,21 +335,40 @@ frange_arithmetic (enum tree_code code, } if (round && (inexact || !real_identical (&result, &value))) { - if (mode_composite) + if (mode_composite + && (real_isdenormal (&result, mode) || real_iszero (&result))) { - if (real_isdenormal (&result, mode) - || real_iszero (&result)) - { - // IBM extended denormals only have DFmode precision. - REAL_VALUE_TYPE tmp; - real_convert (&tmp, DFmode, &value); - frange_nextafter (DFmode, tmp, inf); - real_convert (&result, mode, &tmp); - return; - } + // IBM extended denormals only have DFmode precision. + REAL_VALUE_TYPE tmp, tmp2; + real_convert (&tmp2, DFmode, &value); + real_nextafter (&tmp, REAL_MODE_FORMAT (DFmode), &tmp2, &inf); + real_convert (&result, mode, &tmp); } - frange_nextafter (mode, result, inf); + else + frange_nextafter (mode, result, inf); } + if (mode_composite) + switch (code) + { + case PLUS_EXPR: + case MINUS_EXPR: + // ibm-ldouble-format documents 1ulp for + and -. + frange_nextafter (mode, result, inf); + break; + case MULT_EXPR: + // ibm-ldouble-format documents 2ulps for *. + frange_nextafter (mode, result, inf); + frange_nextafter (mode, result, inf); + break; + case RDIV_EXPR: + // ibm-ldouble-format documents 3ulps for /. + frange_nextafter (mode, result, inf); + frange_nextafter (mode, result, inf); + frange_nextafter (mode, result, inf); + break; + default: + break; + } } // Crop R to [-INF, MAX] where MAX is the maximum representable number