[ychen306]

LLVM's JIT is in a sense different from that of, say, PyPy. It's more primitive. When people talk about JIT in the context of LLVM, they mean the set of APIs provided by LLVM's library. That is, give it a set of IR functions, and things they depend on, the library dynamically compiles and links them for you. More concretely, for example, given the IR of a function, it gives you a raw pointer to the compiled version that you can call directly. It takes care of the boring (and often platform dependent) parts efficiently -- code gen, linking, etc -- so that you can focus on generating efficient IR (which is the hard part for a JIT).