It's an interesting idea but the current LLVM JIT is pretty slow so it hurts my head to think about JIT'ing average size C++ programs. Leaving that aside, the c

It's an interesting idea but the current LLVM JIT is pretty slow so it hurts my head to think about JIT'ing average size C++ programs. Leaving that aside, the cost of doing this for every codepath would probably outweigh the benefits except in very specific use cases (especially on a cpu with decent indirect prediction). This would be an ideal place for a tracing JIT, which LLVM does not have at the moment.