Does x.isNaN == (x != x)?

[RonAvitzur]

@AlexanderM

@inlinable // FIXME(inline-always)
          public var isNaN:  Bool {
            @inline(__always)
            get {
              return !isFinite && significandBitPattern != 0
            }
          }
          

Thank you. That "fixes" the issue with it not being inlined in the specialization. Though, as discussed in When should both @inlinable and @inline(__always) be used? - #2 by scanon, I need to consider whether the particular test case I'm looking at is representative or whether the code expansion of forcing inline will hurt performance elsewhere.