On Fri, Jan 14, 2022 at 3:32 PM Jakub Jelinek <ja...@redhat.com> wrote:
>
> Hi!
>
> gcc 12 snapshot has landed as the system compiler into rawhide today.
> GCC 12 is going to enter its stage4 development phase (only regression
> and documentation bugfixes allowed) on Monday 17th, so there should be
> just those bugfixes and not new features etc. anymore.
> https://gcc.gnu.org/gcc-12/changes.html lists important changes,
> most important is probably that vectorization is enabled at -O2 now
> which is the option with most of the distribution is built with.
>
> https://gcc.gnu.org/gcc-12/porting_to.html is so far incomplete and lists
> some cases where people need to adjust their code. Other things
> include the usual C++ header changes, where previously some standard
> header included some other header as an implementation detail but it doesn't
> any longer and so code that relied on such indirect include that isn't
> required by the standard needs to include the header that provides whatever
> it relies on. Or e.g. packages using -Werror where new warnings are
> reported with the newer compiler and -Werror results in build failures.
>
> If there are bugs on the compiler side, please let me know immediately,
> so that those bugs can be fixed before the mass rebuild next week.
>
> Another important thing I wanted to say is that we'd like to switch
> ppc64le from the numerically problematic IBM extended long double to
> IEEE 754 quad long double. This is an ABI change. Some libraries
> are already built so that they support both ABIs at the same time,
> including glibc, libstdc++, libgcc, libgfortran etc.
> For other libraries and binaries, the compiler, assembler and linker
> will notice if they use long double and flag them as using either
> IBM or IEEE long double and linker (or I think dynamic linker too)
> might complain when things are mixed.
> Right now the rawhide gcc still defaults to -mabi=ibmlongdouble
> but the glibc/gcc libraries are built compatibly with both.
> We'd like to configure gcc shortly before the mass rebuild with
> --with-long-double-format=ieee so that it will default to
> -mabi=ieeelongdouble, probably on a side-tag build first, and it
> will be highly desirable to rebuild at least some of the most commonly
> used library packages in the order of dependencies there, otherwise
> I'd be afraid the mass rebuild could fail for way too many packages
> (as the mass rebuild doesn't do dependency order rebuilds but just
> goes through packages alphabetically or so).
> Any suggestions on which packages have commonly used library packages
> that use long double?
> readelf -A on libraries on ppc64le prints either nothing (either
> the library is thought not to use long double or supports both ABIs
> transparently or hasn't been rebuilt for some years), or
> Attribute Section: gnu
> File Attributes
> Tag_GNU_Power_ABI_FP: hard float, 128-bit IBM long double
> for libraries (or binaries or object files) that use IBM long double
> only or
> Attribute Section: gnu
> File Attributes
> Tag_GNU_Power_ABI_FP: hard float, 128-bit IEEE long double
> for IEEE long doubles.
> So I think we want to rebuild on a side-tag packages that
> provide shared libraries used by hundreds of other packages that
> are
> Tag_GNU_Power_ABI_FP: hard float, 128-bit IBM long double
> right now.
Hi!
Have the command line arguments that are accepted by gcc?
The test suite of the "cc" crate (used for compiling and linking to C
code within Rust projects) started failing with GCC 12 with this
error:
gcc: error: unrecognized command-line option '-arbitrary'
I looked that the docs for gcc 12 (gcc-12/porting_to.html and
gcc-12/changes.html) but neither mention any change in accepted
command line arguments.
Fabio
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