For the past three years, I've been participating in adding just-in-time compilation (JIT) to CRuby. Now, CRuby has the method-based just-in-time compiler (MJIT), which improves performance for non-input/output-bound programs. The most popular approach to implementing a JIT is to use LLVM or GCC JIT interfaces, like ORC or LibGCCJIT. GCC and LLVM developers spend huge effort to implement the optim