if !ok {
				p.errorf("invalid register: %s", name)
			}
			reg := r - p.arch.Register["V0"]
			p.get('.')
			tok := p.next()
			ext := tok.String()
			curArrangement, err := arch.ARM64RegisterArrangement(reg, name, ext)
			if err != nil {
				p.errorf("%v", err)
			}
			if firstReg == -1 {
				// only record the first register and arrangement
				firstReg = int(reg)
				nextReg = firstReg