[LLVMdev] Correctly compiling shared libraries for llvm-gcov on OSX

[Artur Szostak]

Hi,

I have the following problem. I am trying to compile and link a binary and shared library on OS X 10.9 using the clang compiler on that platform. The binary links against the shared library (libgiraffe.19.dylib). I am using the -coverage flag for compilation and linking. Everything works fine until I get the following run time errors when trying to execute the binary:

dyld: lazy symbol binding failed: Symbol not found: _llvm_gcov_init
  Referenced from: /Users/buildacc/jenkinsBuild/workspace/test-giraf-head-coverage-clone/BUILD_TYPE/debug/label/testnode/giraffe/.libs/libgiraffe.19.dylib
  Expected in: flat namespace

dyld: Symbol not found: _llvm_gcov_init
  Referenced from: /Users/buildacc/jenkinsBuild/workspace/test-giraf-head-coverage-clone/BUILD_TYPE/debug/label/testnode/giraffe/.libs/libgiraffe.19.dylib
  Expected in: flat namespace

My immediate assumption is that I need to pass an extra library when linking the shared library (libgiraffe.19.dylib), which contains _llvm_gcov_init. However, I could not find a single library on the platform that provides this function. This makes me think that LLVM implicitly adds these functions when linking a binary. Indeed, in the binary I do find a private symbol _llvm_gcov_init.

So, can I tell LLVM to export the _llvm_gcov_init symbol in the binary so the shared library gets a chance to resolve it?
Or, how could I create a library with the required function like _llvm_gcov_init to link my libraries against?

Kind regards.

Artur