>One idea is merely a form of control flow (like 'if' or 'goto') that could jump down the call stack.

Interestingly this is more or less how Symbian handled exceptions back in the day. It was a giant mess. You basically called setjmp in a surrounding function (using a macro IIRC) and then longjmp (in the form of user::leave()) which unwound the stack without calling any destructors.

It was very fast and the source of endless memory leaks.