We are on the same page irt tail calls. I assume that instruction handlers (non-standard calling convention, tail-calls next handler) need to invoke helper func

We are on the same page irt tail calls. I assume that instruction handlers (non-standard calling convention, tail-calls next handler) need to invoke helper functions quite often. These helpers adhere to standard C calling convention. VM state is in registers. Unless they are callee-saved, registers have to be saved to stack and restored after each helper call. (LuaJIT VM uses helper functions heavily.)