[GHC DevOps Group] CircleCI status

[Phyx]

On Sat, Dec 22, 2018 at 7:21 PM Ben Gamari <ben at well-typed.com> wrote:

> Phyx <lonetiger at gmail.com> writes:
>
> > On Sat, Dec 22, 2018 at 5:40 PM Ben Gamari <ben at well-typed.com> wrote:
> >
> >> Ccing our Windows czar, Tamar.
> >>
> >>
> >> "Greg Steuck (Sh-toy-k)" <gnezdo at google.com> writes:
> >>
> >> > FWIW, lld seems pretty well supported on Windows
> >> > <https://lld.llvm.org/windows_support.html>. We have some evidence
> that
> >> lld
> >> > is faster than gold and ld.bfd on Linux.
> >> >
> >> Indeed that is the option that I am investigating. I have opened #16084
> >> [1] and an msys2 [2] ticket to track this. Unfortunately, GCC shipped
> >> with msys2 doesn't currently support -fuse-ld=lld, so we are stuck with
> >> ld.bfd until GCC 9 is released. However, even then it sounds like
> >> lld <8 and mingw aren't known to interact well.
> >>
> >
> > I wasn't even aware they added a mingw front-end back into LLD, this does
> > make it a viable option.
> > That said I also have a somewhat optimized binutils port here
> > https://github.com/Mistuke/binutils-gdb
> >
> > The patch for fuse-ld=lld support is a trivial backport. I can easily
> build
> > a GCC 8 release with it included and
> > a tip of trunk LLD 8 if you'd like to try them out.
>
> That would be fantastic. I quickly looked at what would be involved to
> do this myself. The process appears to be fairly straightforward
> However, it's a bit unclear which directory in the MSYS2-packages
> repository corresponds to the mingw-w64-$(uname -m)-gcc toolchain we use
> for builds. My guess is that [1] is the relevant package. Can you
> confirm?
>

No, that one is the cross compilers for MSYS2, e.g. when you want to cross
compile from
the posix emulated environment to native Windows. The cross builds still
rely on the msys2
runtime so won't be usable I think.

We use the full native bootstrapped builds [1]. Note that this is already
at GCC8,
we use GCC 7 in GHC atm, so a validate build may not work due to the new
warnings added,
so require you to turn off -Werror for the experiment. We haven't upgraded
to GCC8 as they
haven't published a GCC8 for the 32 bit builds as Ada is currently broken.

[1] https://github.com/Alexpux/MINGW-packages/tree/master/mingw-w64-gcc


>
> > I wouldn't recommend GCC 9 atm as we're in stage 3 and things are
> > routinely broken..
> >
>
> Cheers,
>
> - Ben
>
> [1]
> https://github.com/Alexpux/MSYS2-packages/blob/master/mingw-w64-cross-gcc/PKGBUILD
>
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