[llvm-dev] Cannot compile LLVM suite with clang+lld

[A. Ilchinger via llvm-dev]

Thank you for your reply. After I added those options nothing changed
at first, then I added LLVM's libunwind to the source tree
(runtimes/libunwind) and it got much better.
However, I get the same errors at the end of the build process. Do I
need LLVM's libunwind already installed? I was hoping I could bootstrap
the whole toolchain directly.

Maybe this warning is also interesting?
[9/10] Linking CXX shared
library /tmp/makepkg/llvm/src/llvm-6.0.0.src/build/lib/libunwind.so.1.0
clang-6.0: warning: argument unused during compilation:
'-rtlib=compiler-rt' [-Wunused-command-line-argument]

This argument was added by -DLIBUNWIND_USE_COMPILER_RT=ON which you
explained, it's strange that it is unused.

The final error again is libcxxabi:
[2715/2724] Linking CXX shared library lib/libc++abi.so.1.0
FAILED: lib/libc++abi.so.1.0


On Sun, 06 May 2018 20:49:39 +0000
Petr Hosek <phosek at chromium.org> wrote:

> You also need -DLIBUNWIND_USE_COMPILER_RT=ON
> -DLIBCXXABI_USE_LLVM_UNWINDER=ON. This is because you set
> -DLIBCXXABI_USE_COMPILER_RT=ON
> so libc++abi.so is no longer being linked agains libgcc_s.so which is
> where the unwinder otherwise comes from.
> 
> On Sun, May 6, 2018 at 4:05 AM via llvm-dev <llvm-dev at lists.llvm.org>
> wrote:
> 
> > I try to compile LLVM, clang, lld and libcxx together in one source
> > directory following the instructions on the website.
> > I'm running Arch Linux and already have LLVM, clang, lld and libcxx
> > installed (prebuilt against libstdc++). Now I want a "pure"
> > llvm toolchain.
> >
> > The following options were used:
> > -DBOOTSTRAP_LLVM_ENABLE_LLD
> > -DCMAKE_C_COMPILER=clang
> > -DCMAKE_CXX_COMPILER=clang++
> > -DCMAKE_LINKER=lld
> > -DCMAKE_LINK_EXECUTABLE="/usr/bin/ld.lld"
> > -DCMAKE_AR="/usr/bin/llvm-ar"
> > -DCMAKE_AS="/usr/bin/llvm-as"
> > -DCLANG_DEFAULT_LINKER=lld
> > -DCLANG_DEFAULT_RTLIB=compiler-rt
> > -DCLANG_ENABLE_BOOTSTRAP=ON
> > -DLIBCXX_USE_COMPILER_RT=ON
> > -DLIBCXXABI_USE_COMPILER_RT=ON
> > -DLLVM_ENABLE_LLD=ON
> > -DLLVM_ENABLE_LIBCXX=ON
> >
> > However, the build fails with (many of those error messages):
> >
> > [1274/2712] Linking CXX shared library lib/libc++abi.so.1.0
> > FAILED: lib/libc++abi.so.1.
> > /usr/bin/ld.lld: error: undefined symbol: _Unwind_Resume  
> > >>> referenced by ld-temp.o
> > >>>               lto.tmp:(__cxa_demangle)  
> >
> > Can anyone please tell me what I am doing wrong and how I can fix
> > the build?
> >
> > Regards
> > Andreas
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >