A tail-recursive function computes $f(n, acc) = \begin{cases} acc & \text{if } n = 0 \\ f(n-1, acc \cdot n) & \text{otherwise} \end{cases}$ with initial call $f(n, 1)$. How does the stack depth (call depth) scale with $n$ when the compiler does NOT perform tail-call optimization, and how does it scale when the compiler DOES?