在原始类型上快速扩展的性能

Question

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())

Answer 1

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