mkSimpleLit (MachWord64 i) = CmmInt i W64
mkSimpleLit (MachFloat r) = CmmFloat r W32
mkSimpleLit (MachDouble r) = CmmFloat r W64
mkSimpleLit (MachWord64 i) = CmmInt i W64
mkSimpleLit (MachFloat r) = CmmFloat r W32
mkSimpleLit (MachDouble r) = CmmFloat r W64