title: Is there a difference between Apple Clang and OpenMP-enabled Clang from Homebrew?
body: <p>I want to know if there are any advantages in Apple's provided Clang compiler compared to the Clang compiler that comes with OpenMP available from Homebrew?
  Will there be any performance loss if switching to OpenMP Clang (regardless of the multi-threading ability)?</p>
  <p>I also found <a href="https://stackoverflow.com/questions/12665744/what-is-the-difference-between-clang-and-apple-clang">this</a> old question that has no good answer</p>
  <hr />
  <h2>Update</h2>
  <p>I compiled the <a href="https://github.com/oofem/oofem" rel="nofollow noreferrer">OOFEM</a> using Apple's Clang and mainstream Clang and ran the same problem,</p>
  <p>Apple's Clang: Real time consumed: 000h:01m:26s</p>
  <p>Mainstream Clang: Real time consumed: 000h:01m:24s</p>
  <p>With multi-threading enabled also the performance is similar.
  One difference that I also noticed, is that Apple's Clang seems to ignore some CMake options e.g. <code>-DOpenMP_CXX_FLAGS=&quot;-I/usr/local/opt/libomp/include&quot;</code> has no effect with Apple's Clang while works fine with the mainstream Clang.</p>