Not usually, no. Some languages support automatic tail-call optimization (when a recursive call is the returned value of a function, you can effectively replace

Not usually, no. Some languages support automatic tail-call optimization (when a recursive call is the returned value of a function, you can effectively replace the current stack with the recursively-called one), but in general, there are limits to how "sufficiently-advanced" real compilers are. Eliminating recursion might be difficult to detect if multiple functions form a mutually-recursive set, or if data structures have to be introduced to compensate for no stack (e.g., converting a depth-first search from recursive to iterative form requires a stack).