default:
						goto bad

					case REG_DS:
						ab.Put1(0xc5)

					case REG_SS:
						ab.Put2(0x0f, 0xb2)

					case REG_ES:
						ab.Put1(0xc4)

					case REG_FS:
						ab.Put2(0x0f, 0xb4)

					case REG_GS:
						ab.Put2(0x0f, 0xb5)
					}

					ab.asmand(ctxt, cursym, p, &p.From, &p.To)

				case movDoubleShift:
					if t[0] == Pw {

	defer mux.mu.Unlock()
	// Check for conflict.
	if err := mux.index.possiblyConflictingPatterns(pat, func(pat2 *pattern) error {
		if pat.conflictsWith(pat2) {
			d := describeConflict(pat, pat2)
			return fmt.Errorf("pattern %q (registered at %s) conflicts with pattern %q (registered at %s):\n%s",
				pat, pat.loc, pat2, pat2.loc, d)
		}
		return nil
	}); err != nil {
		return err
	}