// slice may share memory with the BitString.
func (b BitString) RightAlign() []byte {
	shift := uint(8 - (b.BitLength % 8))
	if shift == 8 || len(b.Bytes) == 0 {
		return b.Bytes
	}

	a := make([]byte, len(b.Bytes))
	a[0] = b.Bytes[0] >> shift
	for i := 1; i < len(b.Bytes); i++ {
		a[i] = b.Bytes[i-1] << (8 - shift)
		a[i] |= b.Bytes[i] >> shift
	}

	return a
}

	var a []complex64
	_ = imag(a... /* ERROR "invalid use of ..." */ )

	// if argument is untyped, result is untyped
	const _ byte = imag(1.2 + 3i)
	const _ complex128 = imag(1.2 + 3i)

	// lhs constant shift operands are typed as complex128
	var s uint
	_ = imag(1 /* ERROR "must be integer" */ << s)
}

func imag2() {
	f1 := func() (x complex128) { return }
	f2 := func() (x, y complex128) { return }

func quo(x, y Value) Value { return BinaryOp(x, token.QUO, y) }

// Shift returns the result of the shift expression x op s
// with op == [token.SHL] or [token.SHR] (<< or >>). x must be
// an [Int] or an [Unknown]. If x is [Unknown], the result is x.
func Shift(x Value, op token.Token, s uint) Value {
	switch x := x.(type) {
	case unknownVal:
		return x

	case int64Val:

			//    floating-point numbers if possible,
			// 2) if one of them is not constant (possible because
			//    it contains a shift that is yet untyped), convert
			//    both of them to float64 since they must have the
			//    same type to succeed (this will result in an error
			//    because shifts of floats are not permitted)
			if x.mode == constant_ && y.mode == constant_ {
				toFloat := func(x *operand) {

// uses unsafe.Pointer for speed.
func readvarintUnsafe(fd unsafe.Pointer) (uint32, unsafe.Pointer) {
	var r uint32
	var shift int
	for {
		b := *(*uint8)(fd)
		fd = add(fd, unsafe.Sizeof(b))
		if b < 128 {
			return r + uint32(b)<<shift, fd
		}
		r += uint32(b&0x7F) << (shift & 31)
		shift += 7
		if shift > 28 {
			panic("Bad varint")
		}
	}
}

// A PanicNilError happens when code calls panic(nil).
//

	// TODO(gri) having a combined add-and-shift primitive
	//           could make this code significantly faster
	switch {
	case ex < ey:
		if al {
			t := nat(nil).shl(y.mant, uint(ey-ex))
			z.mant = z.mant.add(x.mant, t)
		} else {
			z.mant = z.mant.shl(y.mant, uint(ey-ex))
			z.mant = z.mant.add(x.mant, z.mant)
		}
	default:
		// ex == ey, no shift needed
		z.mant = z.mant.add(x.mant, y.mant)

copy:
	MOVD	ZR, c+56(FP)
	CMP	R1, R3
	BEQ	done
copy_4:				// no carry flag, copy the rest
	vwOneIterCopy(R0, done)
	B	copy_4

// func shlVU(z, x []Word, s uint) (c Word)
// This implementation handles the shift operation from the high word to the low word,
// which may be an error for the case where the low word of x overlaps with the high
// word of z. When calling this function directly, you need to pay attention to this
// situation.

	{"$1000000000", "$1000000000"},
	{"$__tsan_func_enter(SB)", "$__tsan_func_enter(SB)"},
	{"$main(SB)", "$main(SB)"},
	{"$masks<>(SB)", "$masks<>(SB)"},
	{"$setg_gcc<>(SB)", "$setg_gcc<>(SB)"},
	{"$shifts<>(SB)", "$shifts<>(SB)"},
	{"$~(1<<63)", "$9223372036854775807"},
	{"$~0x3F", "$-64"},
	{"$~15", "$-16"},
	{"(((8)&0xf)*4)(SP)", "32(SP)"},
	{"(((8-14)&0xf)*4)(SP)", "40(SP)"},
	{"(6+8)(AX)", "14(AX)"},

//		Encoding:
//			type = TYPE_TEXTSIZE
//			offset = x
//			val = int32(y)
//
//	reg<<shift, reg>>shift, reg->shift, reg@>shift
//		Shifted register value, for ARM and ARM64.
//		In this form, reg must be a register and shift can be a register or an integer constant.
//		Encoding:
//			type = TYPE_SHIFT
//		On ARM:
//			offset = (reg&15) | shifttype<<5 | count

<code>R0-&gt;16</code>
<br>
<code>R0&gt;&gt;16</code>
<br>
<code>R0&lt;&lt;16</code>
<br>
<code>R0@&gt;16</code>:
For <code>&lt;&lt;</code>, left shift <code>R0</code> by 16 bits.
The other codes are <code>-&gt;</code> (arithmetic right shift),
<code>&gt;&gt;</code> (logical right shift), and
<code>@&gt;</code> (rotate right).
</li>

<li>
<code>R0-&gt;R1</code>
<br>
<code>R0&gt;&gt;R1</code>
<br>