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

[Vedant Kumar via llvm-dev]

> On Dec 18, 2016, at 3:48 AM, Dmitry Golovin <dima at golovin.in> wrote:
> 
> 
> 
> 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.

I think we're talking about different things.

It looks like you just want the builtins: this exists.

E.g on Darwin, you can find muldc3 in libclang_rt.hard_pic.a.


> 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.

Did that work?

If not, try building the builtins for your platform, e.g:

$ ninja libclang_rt.builtins_x86_64_osx.a

best,
vedant