if string(m) != expect {
		t.Errorf("rot13: expected %q got %q", expect, m)
	}

	// 5. Drop
	dropNotLatin := func(r rune) rune {
		if unicode.Is(unicode.Latin, r) {
			return r
		}
		return -1
	}
	m = Map(dropNotLatin, []byte("Hello, 세계"))
	expect = "Hello"
	if string(m) != expect {
		t.Errorf("drop: expected %q got %q", expect, m)
	}

	// 6. Invalid rune

	MOVD SPR(3), 4(R1)              // 7fe302a6fbe10004
	MOVD XER, 4(R1)                 // 7fe102a6fbe10004
	MOVD 4(R1), SPR(3)              // ebe100047fe303a6
	MOVD 4(R1), XER                 // ebe100047fe103a6
	PNOP                            // 0700000000000000

	SETB CR1,R3                     // 7c640100
	VCLZLSBB V1,R2                  // 10400e02
	VCTZLSBB V1,R2                  // 10410e02

	input         []lex.Token
	inputPos      int
	pendingLabels []string // Labels to attach to next instruction.
	labels        map[string]*obj.Prog
	toPatch       []Patch
	addr          []obj.Addr
	arch          *arch.Arch
	ctxt          *obj.Link
	firstProg     *obj.Prog
	lastProg      *obj.Prog
	dataAddr      map[string]int64 // Most recent address for DATA for this symbol.

				prog.AddRestDest(a[2])
			default:
				prog.From = a[0]
				prog.Reg = p.getRegister(prog, op, &a[1])
				prog.To = a[2]
			}
		case sys.I386:
			prog.From = a[0]
			prog.AddRestSource(a[1])
			prog.To = a[2]
		case sys.PPC64:
			if arch.IsPPC64CMP(op) {
				// CMPW etc.; third argument is a CR register that goes into prog.Reg.
				prog.From = a[0]