[llvm-dev] How to compile glibc with clang/llvm?

[Alberto Barbaro via llvm-dev]

Hi,
Could you keep us posted, or at least me? I'm interested to compile glibc
as well and obtain the bitcode.

Would you consider to use https://www.musl-libc.org in the meantime?

Thanks

On Sun, Dec 23, 2018, 12:00 Kristina Brooks via llvm-dev <
llvm-dev at lists.llvm.org wrote:

> Hi.
>
> Actually from reading the README, it seems to imply that it can be built
> with Clang 6.0.0 and above now, though it does incorporate a lot of
> patches not
> specific to Clang building so you will end up with them as well:
>
>
> ----------------------------------------------------------------------------
> BUILDING GRTE WITH CLANG
>
> GRTE v5 and later can also be built with clang and (optionally) lld.
> LLVM support for GNU source code continues to evolve (as of June
> 2018), so the process is less straightforward, and likely to change
> from what is documented here.  There are a number of glibc patches
> that make this work, including additional configure options mentioned
> below.
>
> The minimum version of clang is 6.0.0.  If lld is to be used for linking,
> it needs to be newer than 6.0.0.
>
> Configure:
>
>   CC=path-to-llvm/clang CXX=path-to-llvm/clang++ \
>     ../glibc/configure --disable-werror --with-clang --disable-float128 \
>       --with-lld --with-default-link --disable-multi-arch
> --prefix=/something
>
> ------------------------------------------------------------------------------
>
> On 23/12/2018 02:51, Kristina Brooks wrote:
> > Hi.
> >
> > I've managed to do it before, with a lot of patches to Glibc, as well as
> ld.so and getting basic programs to start with
> > it. However, a lot of tests did not pass and in general I abandoned it
> due to the fact that Glibc source code is not
> > very easy to work with.
> >
> > I can upload it somewhere, not sure if there is any general interest in
> this kind of thing. I think current GRTE may
> > also be build-able with Clang (my fork was based on older GRTE which had
> unfinished patches to support Clang), though I
> > haven't had the time to look at that recently.
> >
> > I should add a huge disclaimer: this won't be easy and requires
> understanding the macro hell in glibc, GRTE relies on
> > some hacky uses of `_Pragma` to supplement for some macros otherwise not
> possible with Clang. Even if you do get it to
> > build I think it may be a waste of time to try and just implement the
> missing symbols in your case (or figure out why
> > they're not being exported).
> >
> > Thanks.
> >
> > On 22/12/2018 09:29, xuruobin via llvm-dev wrote:
> >> To whom it may concern,
> >>
> >>      Is there a way to build glibc with clang/llvm? I’m working on
> enabling llvm-cov for my compiler which is a totally new arch with a libc.a
> built from newlib. I successfully built compiler-rt but when I typed the
> command ` clang++ --target=xxx -fprofile-instr-generate -fcoverage-mapping
> foo.cc -o foo`, the linker failed because of undefined reference to
> `mmap'/`ftruncate'/`mkdir'. I found these functions are supported by glibc
> but I cannot bulid glibc with clang/llvm(configure gave me an error “These
> critical programs are missing or too old: compiler”). So I want to know how
> can I compile glibc with clang/llvm or are there some WIP patches to help
> me with this requirement?
> >>
> >> Thanks,
> >> Ruobin.
> >> _______________________________________________
> >> LLVM Developers mailing list
> >> llvm-dev at lists.llvm.org
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >>
> >
>
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