Don't use Apple-LLVM and Clang-LLVM. They are all shit compilers and they often create broken binaries that segfault when executed no matter the code.
Use gcc, it's much better and more powerful. The binaries produced by gcc are much smaller and run much ftaer and smoother then app or clang llvm.
Also recently, apple has added a surveillance capability to all llvm and clang versions so you should not use them.