Are operators faster than functions?

Question

While searching for the difference in new and malloc, I came across this statement (source):

new is faster than malloc() because an operator is always faster than a function.

Are operators always faster than functions? If so, why? I would really appreciate low-level explanations (you can assume basic compiler, SASS, and hardware knowledge).

Answer 1

new is faster than malloc() because an operator is always faster than a function.

This is completely untrue. In fact, it is quite typical that the default behaviour of new expression is to internally call malloc, in which case it cannot possibly be faster.

There is no reason to expect different performance for using one over another as long as the contending programs do the same thing. The reasons to use new instead of malloc are not related to performance.

Are operators faster than functions?

Calling a function at runtime is potentially slower than not calling a function.

But, as we've found out, an operator can actually internally call a function. Besides, a function call for the abstract machine doesn't necessarily mean that a function will be called at runtime. As long as the compiler is able to produce the result of the function at compile time, or if it is able to expand the call inline, then there is no need for any function call overhead.

So, it depends on what function calls we are discussing. As far as a C++ function call is concerned: It is not necessarily slower than the use of an operator.

Also, do note that all overloaded operators that operate on class types are actually function calls to the operator overload function.