Does the compiler optimize the function parameters passed by value?

Question

Lets say I have a function where the parameter is passed by value instead of const-reference. Further, lets assume that only the value is used inside the function i.e. the f

Answer 1

Only if the function is not exported there is a chance the compiler to convert call-by-reference to call-by-value (or vise-versa).

Otherwise, due to the calling convention, the function must keep the call-by-value/reference semantic.