Performance of swift extensions on primitive types

问题

I am wondering if there would be any performance difference between the following in swift:

let x = 42.42
print(floor(x))

and

let x = 42.42
extension Double {
  func myFloor() -> Double {
    return floor(self)
  }
}
print(x.myFloor())

回答1:

The compiler inlines the code in the second case and produces the same machine code. You can see for yourself, here.

来源：https://stackoverflow.com/questions/45558276/performance-of-swift-extensions-on-primitive-types