Ever since YJIT’s introduction, I’ve felt simultaneously close to and distant from Ruby’s JIT compiler. I know how to enable it in my Ruby programs. I know it makes my Ruby programs run faster by compiling some of them into machine code. But my understanding around YJIT, or JIT compilers in Ruby in general, seems to end here. A few months ago, my colleague Max Bernstein wrote ZJIT has been merged into Ruby to explain how ZJIT compiles Ruby’s bytecode to HIR, LIR, and then to native code. It shed...