title: How to call C++ function in LLVM IR?
body: <p>I am new to LLVM IR, I have a LLVM IR source code and it uses some extern declare functions.
  These functions are implemented in a C++ file.</p>
  
  <p>So my question is :</p>
  
  <p>How to call these c++ function in the LLVM IR?</p>
  
  <p>Is it right way to compile the c++ file into LLVM IR, and <strong>link</strong> them together?</p>