Force specialization of a very big function quotientAndRemainder for the most popular values of generic type parameters.

This reduces the amount of work to be done on the client side, because specializations from the stdlib can be used there.

Author: swiftix

stdlib/public/core/DoubleWidth.swift.gyb

@@ -297,6 +297,11 @@ public struct DoubleWidth<Base : FixedWidthInteger> :
     return (result, didCarry || hadPositiveOverflow)
   }
 
+  // Specialize for the most popular types.
+  @_specialize(where Base == Int)
+  @_specialize(where Base == UInt)
+  @_specialize(where Base == Int64)
+  @_specialize(where Base == UInt64)
   public func quotientAndRemainder(dividingBy other: DoubleWidth)
     -> (quotient: DoubleWidth, remainder: DoubleWidth) {
     let isNegative = (self < (0 as DoubleWidth)) != (other < (0 as DoubleWidth))