I have been writing a compiler and have discussed this situation with a colleague.

In the most general case, suppose you have your arguments on the stack (once argument registers are exhausted).

If tail recursion:

• simply overwrite the stack arguments, set stack pointer to your frame pointer, and make the call

Otherwise:

• if the callee has less arguments than the caller, simply overwrite the first K, and do the same

Question:

• if the callee has more arguments, what do you do?

Here’s a picture representation:

A's frame
....
arg2 of B
arg1 of B
_______
B's frame

and now B wants to call C and do TCO, but C has 3 arguments, what do you do?

One solution is to make a minimal frame just responsible for handling this control and placing the arguments; however, that seems like it defeats the purpose of TCO.

My colleague says that it is impossible to perform TCO in this case.