How to use llvm libraries

Question

I am working in a project that consist of some C++ teams. Each team delivers libraries and our team is integrating these libraries into a front end application.

The application is cross platform, so it means that other the teams have to provide the same (static) libraries compiled for different platforms/CPU architecture/configuration. Eg. we have Visual Studio 2015/2013, 32bit/64bit, linux, Debug/Release etc.

It would be nice to reduce the number of these static library "manifests", so I was looking into the Clang/LLVM. The idea would be compile the static libraries into LLVM bitcode and use the llvm-ar tool to create an llvm static library. When we have to make the binaries for a specific platform we would use the llc (LLVM platform compiler) to create the native code static library and do the linking with the platform linker.

Questions:

• is there a better way to do what I want to achieve?
• the llc does not seem to support the compiling of a static library, only individual translation units (.bc -> .o). Of course I can extract each individual bitcode file, assemble it to native object file and use the platform librarian tool (lib/ar) to make the static library, but I wonder if there is a more streamlined solution.
• the gold linker seems to make something I need, but seems to be restricted to ELF format. I have to support Windows/Linux and maybe IOS

Answer 1

LLVM IR generated from target-specific and platform-specific language (C/C++) won't be target neutral. Think about type sizes, alignments, ABI requirements, etc. Not the mention pure source code features like preprocessor. So, no, the approach you thought about won't work at all.

See LLVM bitcode cross-platform for some more information.