[llvm-dev] libcompiler_rt.so and libcompiler_rt.a are not being built

[Dmitry Golovin via llvm-dev]

16.12.2016, 18:23, "Vedant Kumar" <vsk at apple.com>:
>>  On Dec 16, 2016, at 7:06 AM, Dmitry Golovin via llvm-dev <llvm-dev at lists.llvm.org> wrote:
>>
>>  I want to build LLVM-based toolchain with Musl, I have LLVM sources with clang and lld (under `tools` directory) and libunwind, compiler-rt, libcxx and libcxxabi (under `projects` directory). All are the latest versions cloned from GitHub mirror, branch `master`.
>>
>>  I'm trying to configure with the following options:
>>     CLANG_DEFAULT_CXX_STDLIB = libc++
>>     CLANG_DEFAULT_RTLIB = compiler-rt
>>     CLANG_DEFAULT_LINKER = lld
>>     LLVM_DEFAULT_TARGET_TRIPLE=x86_64-pc-linux-musl
>>
>>  I use cmake to configure and ninja to build.
>>
>>  It configures fine and builds, but I need libcompiler_rt.so and it is not among build targets, so it is not built and installed.
>>
>>  I think it is a bug and libcompiler_rt.so should be built. I don't have a bugzilla account, so I would appreciate if someone reports it for me.
>
> I don't think a single library that encompasses all of compiler-rt exists, or
> even *can* exist. E.g, the runtimes for ASan and TSan both export interceptors
> for common library routines which would be mutually incompatible. So, I don't
> think this is a bug.
>
> If you want to build all of compiler-rt, try building the phony 'compiler-rt'
> target. All of the libraries you need will show up in:
>
>   <build-dir>/lib/clang/<version>/lib
>
> best,
> vedant
>
>>  Regards,
>>  Dmitry

I'm sure that this library can and should exist. You can search it by it's name and it is mentioned a lot on the Internet. Now I've got a linking problem when building musl:

    (function cpow): undefined symbol '__muldc3'
    (function cpowf): undefined symbol '__mulsc3'
    (function cpowl): undefined symbol '__mulxc3'
    (function csqrt): undefined symbol '__muldc3'

I'm pretty sure this problem is solved by just adding -lcompiler_rt to LDFLAGS.

Regards,
Dmitry