On Tue, May 4, 2021 at 7:12 AM Jonathan Wakely <jwak...@redhat.com> wrote: > > On 30/04/21 16:24 -0400, David Edelsohn via Libstdc++ wrote: > >On Fri, Jan 8, 2021 at 11:10 AM Jonathan Wakely <jwak...@redhat.com> wrote: > >> > >> On 03/01/21 22:26 -0500, David Edelsohn via Libstdc++ wrote: > >> >On Sun, Jan 3, 2021 at 9:45 PM Jonathan Wakely <jwakely....@gmail.com> > >> >wrote: > >> >> > >> >> On Mon, 4 Jan 2021, 00:44 David Edelsohn via Libstdc++, > >> >> <libstd...@gcc.gnu.org> wrote: > >> >>> > >> >>> Or is there some other reason that _GLIBCXX_USE_INT128 and > >> >>> __SIZEOF_INT128__ are used in different contexts? > >> >> > >> >> Yes. > >> >> > >> >> I'll reply when I'm back from taking some time off. Probably Wednesday. > >> > > >> >If the uses of _GLIBCXX_USE_INT128 in libstdc++ headers specifically > >> >are checking if __int128 type is different than "long" and "long > >> >long", as opposed to the availability of the __int128, can c++config.h > >> > >> Yes, the test is not just "is __int128 a valid type?" but "should we > >> use __int128 as a larger integer type?" > >> > >> We used to use it more widely, but many places that use __int128 > >> conditionally now check __GLIBCXX_INT_N_0 instead, because that is > >> defined when __int128 is available and we're not compiling in a > >> "strict ansi" dialect. > >> > >> Of the two remaining uses of _GLIBCXX_USE_INT128 I think one is wrong > >> and should test __SIZEOF__INT128__ directly. We specifically do want > >> to use unsigned __int128 in __to_chars_unsigned_type even if it's the > >> same as a standard type. > >> > >> So that leaves one remaining use, and I think that should do as you > >> suggest here ... > >> > >> >define _GLIBCXX_USE_INT128 by comparing __SIZEOF_INT128__ to > >> >__SIZEOF_LONG_LONG__ and __SIZEOF_LONG__ instead of the libstdc++ > >> >configure template typename test? > >> > >> Yes, that seems fine. But since we only need it in one place, let's > >> just do that test in that one place. It makes the purpose of the test > >> more explicit, and so you don't need to look up what > >> _GLIBCXX_USE_INT128 means and when it's true. > >> > >> Does the attached patch work for you? > > > >Hi, Jonathan > > > >Thanks for pushing the INT64_T patch. > > > >I tested your revised patch in January and it works perfectly. > > > >Could you push your INT128 patch to trunk when you have a moment? > > > >Thanks, David > > I've pushed the attached to trunk after testing on powerpc-aix and > x86_64-linux. > > Contrary to what I said in January, I think both sues of > _GLIBCXX_USE_INT128 do want to only use __int128 if it's larger than > long long. For __to_chars_unsigned_type there's no point trying to use > unsigned __int128 if it's the same size as unsigned long long, because > we'd already have chosen unsigned long long.
Hi, Jonathan Excellent. Thank you very much for addressing this issue and removing the multilib size dependencies in libstdc++ headers. Thanks, David
