{name: "Bswap64", argLength: 1}, // Swap bytes

	{name: "BitRev8", argLength: 1},  // Reverse the bits in arg[0]
	{name: "BitRev16", argLength: 1}, // Reverse the bits in arg[0]
	{name: "BitRev32", argLength: 1}, // Reverse the bits in arg[0]
	{name: "BitRev64", argLength: 1}, // Reverse the bits in arg[0]

	{name: "PopCount8", argLength: 1},  // Count bits in arg[0]

(BitLen32 x) => (SUB (MOVDconst [32]) (CLZW <typ.Int> x))

(Bswap64 ...) => (REV ...)
(Bswap32 ...) => (REVW ...)
(Bswap16 ...) => (REV16W ...)

(BitRev64 ...) => (RBIT ...)
(BitRev32 ...) => (RBITW ...)
(BitRev16   x) => (SRLconst [48] (RBIT <typ.UInt64> x))
(BitRev8    x) => (SRLconst [56] (RBIT <typ.UInt64> x))

	},
	{
		name:    "BitRev8",
		argLen:  1,
		generic: true,
	},
	{
		name:    "BitRev16",
		argLen:  1,
		generic: true,
	},
	{
		name:    "BitRev32",
		argLen:  1,
		generic: true,
	},
	{
		name:    "BitRev64",
		argLen:  1,
		generic: true,
	},
	{
		name:    "PopCount8",
		argLen:  1,
		generic: true,