https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69368
--- Comment #81 from rguenther at suse dot de <rguenther at suse dot de> --- On February 23, 2016 4:20:48 PM GMT+01:00, "alalaw01 at gcc dot gnu.org" <gcc-bugzi...@gcc.gnu.org> wrote: >https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69368 > >--- Comment #79 from alalaw01 at gcc dot gnu.org --- >(In reply to rguent...@suse.de from comment #78) >> >> That would pessimize it too much IMHO. > >I'm not sure how to evaluate the pessimization, given it's thought to >be a >widespread pseudo-FORTRAN construct; so I probably have to defer to >your >judgement here. However... > >Given maxsize of an array as two elements, say, would the compiler not >be >entitled to optimize an index selection down to, say, computing only >the LSBit >of the actual index? Whereas 'unknown' means, well, exactly what is >the case. >So I fear this is storing problems up for the future. It doesn't do that. >Is the concern that we can't hide this behind an option, as that would >"drive >people away from gfortran" ? If that's the case, can we hide it behind >an >option that defaults to pessimization (?? at least for fortran)?? I don't think it's necessary to hide it behind an option.
