FWIW, OS X at least used to, and I think still does, use a JITed software renderer using LLVM.<p>See &lt;<a href="http:&#x2F;&#x2F;lists.llvm.org&#x2F;pipermail&#x2F;llvm-dev&#x2F;2006-August&#x2F;006497.html&gt;" rel="nofollow">http:&#x2F;&#x2F;lists.llvm.org&#x2F;pipermail&#x2F;llvm-dev&#x2F;2006-August&#x2F;006497....</a> for a short overview and &lt;<a href="http:&#x2F;&#x2F;www.llvm.org&#x2F;devmtg&#x2F;2007-05&#x2F;10-Lattner-OpenGL.pdf&gt;" rel="nofollow">http:&#x2F;&#x2F;www.llvm.org&#x2F;devmtg&#x2F;2007-05&#x2F;10-Lattner-OpenGL.pdf&gt;</a> (slides, PDF) for a longer one.