proper tail recursion for gcc

[John Vickers]

Joern Rennecke wrote:
> 
> > When foo_with_bar returns, it will return to foo's caller, which
> > will pop off b and c.  a remains on the stack, but does no harm.
> > When foo's caller returns, a will get popped, just as if a had
> > been alocated with alloca.

Every argument frame written to the stack for a tail call
has to start at the beginning of the argument frame of the caller:
i.e. each tail caller in effect pops it's own arguments before pushing
the tail callee's arguments.

Otherwise tail recursion between two functions with different sized
argument frames would use unbounded memory.

> >
> > This will fail if foo's caller is compiled to not use a frame pointer,
> > since the stack pointer will not be where it expects it.
> 
> And even if it has been compiled with a frame pointer, there can
> be a stack overflow if the call is done in a loop with many iterations.

What is this "loop" construct of which you speak ?

Regards,

John.