for item := range *ss {
		items = append(items, item)
	}
	sort.Strings(items)
	return strings.Join(items, ",")
}

func (ss *stringSetFlag) Set(s string) error {
	m := make(map[string]bool) // clobber previous value
	if s != "" {
		for _, name := range strings.Split(s, ",") {
			if name == "" {
				continue // TODO: report error? proceed?
			}
			m[name] = true
		}
	}
	*ss = m
	return nil

	// match: (MOVBZreg <t> x:(MOVBload [o] {s} p mem))
	// cond: x.Uses == 1 && clobber(x)
	// result: @x.Block (MOVBZload <t> [o] {s} p mem)
	for {
		t := v.Type
		x := v_0
		if x.Op != OpS390XMOVBload {
			break
		}
		o := auxIntToInt32(x.AuxInt)
		s := auxToSym(x.Aux)
		mem := x.Args[1]
		p := x.Args[0]
		if !(x.Uses == 1 && clobber(x)) {
			break
		}
		b = x.Block

	&& isSamePtr(p1, p2) && store.Uses == 1
	&& n >= o2 + t2.Size()
	&& clobber(store)
	=> (Zero {t1} [n] p1 mem)
(Move {t1} [n] dst1 src1 store:(Store {t2} op:(OffPtr [o2] dst2) _ mem))
	&& isSamePtr(dst1, dst2) && store.Uses == 1
	&& n >= o2 + t2.Size()
	&& disjoint(src1, n, op, t2.Size())
	&& clobber(store)
	=> (Move {t1} [n] dst1 src1 mem)

			}

			if len(chunks) == 0 {
				return
			}

			// Verify that appending to the end of the first chunk does not
			// clobber the beginning of the next chunk.
			s := Clone(tc.s)
			chunks[0] = append(chunks[0], -1)
			if !Equal(s, tc.s) {
				t.Errorf("slice was clobbered: %v, want %v", s, tc.s)
			}
		})
	}
}

func TestChunkPanics(t *testing.T) {
	for _, test := range []struct {

			}
			*cause = msg
		}
	}

	// generic cases with specific type terms
	// (generic operands cannot be constants, so we can ignore x.val)
	switch {
	case Vp != nil && Tp != nil:
		x := *x // don't clobber outer x
		return Vp.is(func(V *term) bool {
			if V == nil {
				return false // no specific types
			}
			x.typ = V.typ
			return Tp.is(func(T *term) bool {
				if T == nil {

(MOVHreg  <t> x:(MOVHUload [off] {sym} ptr mem)) && x.Uses == 1 && clobber(x) => @x.Block (MOVHload  <t> [off] {sym} ptr mem)
(MOVWreg  <t> x:(MOVWUload [off] {sym} ptr mem)) && x.Uses == 1 && clobber(x) => @x.Block (MOVWload  <t> [off] {sym} ptr mem)

// to the buffer space in R8.
// It clobbers condition codes.
// It does not clobber any other general-purpose registers,
// but may clobber others (e.g., floating point registers).
// The act of CALLing gcWriteBarrier will clobber R14 (LR).
TEXT gcWriteBarrier<>(SB),NOSPLIT|NOFRAME,$0
	// Save the registers clobbered by the fast path.
	MOVM.DB.W	[R0,R1], (R13)
retry:
	MOVW	g_m(g), R0

// to the buffer space in R25.
// It clobbers R23 (the linker temp register).
// The act of CALLing gcWriteBarrier will clobber R31 (LR).
// It does not clobber any other general-purpose registers,
// but may clobber others (e.g., floating point registers).
TEXT gcWriteBarrier<>(SB),NOSPLIT,$192
	// Save the registers clobbered by the fast path.
	MOVV	R1, 184(R29)
	MOVV	R2, 192(R29)
retry:

// number of bytes of buffer needed in R9, and returns a pointer
// to the buffer space in R9.
// It clobbers R10 (the temp register) and R1 (used by PLT stub).
// It does not clobber any other general-purpose registers,
// but may clobber others (e.g., floating point registers).
TEXT gcWriteBarrier<>(SB),NOSPLIT,$96
	// Save the registers clobbered by the fast path.
	MOVD	R4, 96(R15)
retry:
	MOVD	g_m(g), R1
	MOVD	m_p(R1), R1

// to the buffer space in X24.
// It clobbers X31 aka T6 (the linker temp register - REG_TMP).
// The act of CALLing gcWriteBarrier will clobber RA (LR).
// It does not clobber any other general-purpose registers,
// but may clobber others (e.g., floating point registers).
TEXT gcWriteBarrier<>(SB),NOSPLIT,$208
	// Save the registers clobbered by the fast path.
	MOV	A0, 24*8(X2)
	MOV	A1, 25*8(X2)
retry: