PING**2 On Wed, Mar 21, 2012 at 23:45, Janne Blomqvist <blomqvist.ja...@gmail.com> wrote: > PING > > On Wed, Mar 14, 2012 at 01:03, Janne Blomqvist > <blomqvist.ja...@gmail.com> wrote: >> Hi, >> >> the attached patch implements a few fixes and cleanups for the MOD and >> MODULO intrinsics. >> >> - When the arguments are constant, use mpfr_fmod instead of the naive >> algorithms which are numerically unstable for large arguments. This >> extends the PR 24518 fix to constant arguments as well, and makes the >> compile-time evaluation match the runtime implementation which also >> uses fmod in the same manner. >> >> - Remove the old fallback path for the case builtin_fmod is not >> available, as the builtin is AFAICS always available. >> >> The patch does not per se fix the corner-case bug as reported in PR >> 49010, in fact it makes it worse in a way as with the patch the result >> if the arguments are parameters is the same as the runtime result >> (previously, the compile-time result was correct). But, I think we >> should leave it as it is. Due to the reasons above, we're not using >> the naive algorithms anyway, and IMHO -0.0 is quite a good >> approximation for +0.0 anyway. One might even argue that due to the >> numerical instability, specifying the naive algorithms is a bug in the >> standard. >> >> The patch adds notes to the documentation about the usage of fmod, so >> users interested in corner-case behavior can look up how that function >> is supposed to behave on their target. FWIW, AFAICS MPFR and glibc >> fmod conform to the behavior specified in C99 Annex F. >> >> Regtested on x86_64-unknown-linux-gnu, Ok for trunk? >> >> 2012-03-14 Janne Blomqvist <j...@gcc.gnu.org> >> >> PR fortran/49010 >> PR fortran/24518 >> * intrinsic.texi (MOD,MODULO): Mention usage of fmod instead of >> naive algorithm. >> * simplify.c (gfc_simplify_mod): Use mpfr_fmod. >> (gfc_simplify_modulo): Likewise. >> * trans-intrinsic.c (gfc_conv_intrinsic_mod): Remove fallback as >> builtin_fmod is always available. >> >> >> -- >> Janne Blomqvist > > > > -- > Janne Blomqvist
-- Janne Blomqvist
