New unsigned saturation downconvert patterns detection was implemented in
(truncate (smin (smax (x, C1), C2)) to dest_type), where C1 >= 0 and C2 is unsigned max of destination type. (truncate (smax (smin (x, C2), C1)) to dest_type) where C1 >= 0, C2 is unsigned max of destination type and C1 <= C2.
These two patterns are equivalent to:
(truncate (umin (smax(x, C1), unsigned_max_of_dest_type)) to dest_type)