\begin{code}
mkSplitUniqSupply (C# c#)
= let
-#if __GLASGOW_HASKELL__ >= 503
mask# = (i2w (ord# c#)) `uncheckedShiftL#` (i2w_s 24#)
-#else
- mask# = (i2w (ord# c#)) `shiftL#` (i2w_s 24#)
-#endif
-- here comes THE MAGIC:
-- This is one of the most hammered bits in the whole compiler