y := x[4:]
		checkString("y[1:]", y[1:])
	}
	{
		x := bytes
		checkBytes("x", x)
		checkBytes("x[5:]", x[5:])
		checkBytes("x[five:]", x[five:])
		checkBytes("x[5:five]", x[5:five])
		checkBytes("x[five:5]", x[five:5])
		checkBytes("x[five:five]", x[five:five])
		checkBytes("x[1:][2:][2:]", x[1:][2:][2:])
		y := x[4:]
		checkBytes("y[1:]", y[1:])
	}
	{
		x := ints
		checkInts("x", x)

	mybytes  []byte
	myrunes  []rune
)

func checkBytes(s []byte, arg string) {
	if len(s) != 0 {
		panic("len(" + arg + ") != 0")
	}
	if s == nil {
		panic(arg + " == nil")
	}
}

func checkRunes(s []rune, arg string) {
	if len(s) != 0 {
		panic("len(" + arg + ") != 0")
	}
	if s == nil {
		panic(arg + " == nil")
	}
}

func main() {
	checkBytes([]byte(""), `[]byte("")`)

	// necessary.

	SUB	SRC, TGT, TMP	// dest - src
	CMPU	TMP, LEN, CR2	// < len?
	BC	12, 8, backward // BLT CR2 backward

	// Copying forward if no overlap.

	BC	12, 6, checkbytes	// BEQ CR1, checkbytes
	SRDCC	$3, DWORDS, OCTWORDS	// 64 byte chunks?
	MOVD	$16, IDX16
	BEQ	lt64gt8			// < 64 bytes

	// Prepare for moves of 64 bytes at a time.

forward64setup:
	DCBTST	(TGT)			// prepare data cache