Um...function calls do have an overhead. Yes it is negligible in most cases but it certainly made a difference when C was invented. In fact, C++ still carries

Um...function calls do have an overhead. Yes it is negligible in most cases but it certainly made a difference when C was invented. In fact, C++ still carries the "inline" declaration around to avoid function call overhead. The compiler can ignore when knows better but the fact that inlining exits implies that function call overhead is not imaginary.