byteSliceOverwriteConstantBytes,
	byteSliceShuffleBytes,
	byteSliceSwapBytes,
}

func (m *mutator) mutateBytes(ptrB *[]byte) {
	b := *ptrB
	defer func() {
		if unsafe.SliceData(*ptrB) != unsafe.SliceData(b) {
			panic("data moved to new address")
		}
		*ptrB = b
	}()

	for {
		mut := byteSliceMutators[m.rand(len(byteSliceMutators))]
		if mutated := mut(m, b); mutated != nil {

	} else if b.addr != b {
		panic("strings: illegal use of non-zero Builder copied by value")
	}
}

// String returns the accumulated string.
func (b *Builder) String() string {
	return unsafe.String(unsafe.SliceData(b.buf), len(b.buf))
}

// Len returns the number of accumulated bytes; b.Len() == len(b.String()).
func (b *Builder) Len() int { return len(b.buf) }

	{"println", ir.OPRINTLN},
	{"real", ir.OREAL},
	{"recover", ir.ORECOVER},
}

var unsafeFuncs = [...]struct {
	name string
	op   ir.Op
}{
	{"Add", ir.OUNSAFEADD},
	{"Slice", ir.OUNSAFESLICE},
	{"SliceData", ir.OUNSAFESLICEDATA},
	{"String", ir.OUNSAFESTRING},
	{"StringData", ir.OUNSAFESTRINGDATA},
}

// InitUniverse initializes the universe block.
func InitUniverse() {

		fail:    false,
	},
	{
		name:    "slicedata",
		c:       `void f42(void* p) {}`,
		imports: []string{"unsafe"},
		body:    `s := []*byte{nil, new(byte)}; C.f42(unsafe.Pointer(unsafe.SliceData(s)))`,
		fail:    true,
	},
	{
		name:    "slicedata2",
		c:       `void f43(void* p) {}`,
		imports: []string{"unsafe"},

	var _ []int = unsafe.Slice(&x, 0)
	_ = unsafe.Slice(&x, 1.0)
	_ = unsafe.Slice((*int)(nil), 0)
}

func SliceData1() {
	var s []int
	unsafe.SliceData(0 /* ERROR "not a slice" */)
	unsafe /* ERROR "not used" */ .SliceData(s)

	type S []int
	_ = unsafe.SliceData(s)
	_ = unsafe.SliceData(S{})
}

func String1() {
	var b byte
	unsafe.String()        // ERROR "not enough arguments"

	_Alignof:    {"Alignof", 1, false, expression},
	_Offsetof:   {"Offsetof", 1, false, expression},
	_Sizeof:     {"Sizeof", 1, false, expression},
	_Slice:      {"Slice", 2, false, expression},
	_SliceData:  {"SliceData", 1, false, expression},
	_String:     {"String", 2, false, expression},
	_StringData: {"StringData", 1, false, expression},

	_Assert: {"assert", 1, false, statement},
	_Trace:  {"trace", 0, true, statement},

	_Alignof:    {"Alignof", 1, false, expression},
	_Offsetof:   {"Offsetof", 1, false, expression},
	_Sizeof:     {"Sizeof", 1, false, expression},
	_Slice:      {"Slice", 2, false, expression},
	_SliceData:  {"SliceData", 1, false, expression},
	_String:     {"String", 2, false, expression},
	_StringData: {"StringData", 1, false, expression},

	_Assert: {"assert", 1, false, statement},
	_Trace:  {"trace", 0, true, statement},

		x.mode = value
		x.typ = NewSlice(ptr.base)
		if check.recordTypes() {
			check.recordBuiltinType(call.Fun, makeSig(x.typ, ptr, y.typ))
		}

	case _SliceData:
		// unsafe.SliceData(slice []T) *T
		check.verifyVersionf(call.Fun, go1_20, "unsafe.SliceData")

		slice, _ := coreType(x.typ).(*Slice)
		if slice == nil {
			check.errorf(x, InvalidUnsafeSliceData, invalidArg+"%s is not a slice", x)
			return
		}

		x.mode = value
		x.typ = NewSlice(ptr.base)
		if check.recordTypes() {
			check.recordBuiltinType(call.Fun, makeSig(x.typ, ptr, y.typ))
		}

	case _SliceData:
		// unsafe.SliceData(slice []T) *T
		check.verifyVersionf(call.Fun, go1_20, "unsafe.SliceData")

		slice, _ := coreType(x.typ).(*Slice)
		if slice == nil {
			check.errorf(x, InvalidUnsafeSliceData, invalidArg+"%s is not a slice", x)
			return
		}

		as2 := make([]Attr, 0, len(as)-n)
		for _, a := range as {
			if !a.Value.isEmptyGroup() {
				as2 = append(as2, a)
			}
		}
		as = as2
	}
	return Value{num: uint64(len(as)), any: groupptr(unsafe.SliceData(as))}
}

// countEmptyGroups returns the number of empty group values in its argument.
func countEmptyGroups(as []Attr) int {
	n := 0
	for _, a := range as {
		if a.Value.isEmptyGroup() {
			n++
		}