if present {
		return true
	}
	// Parenthesized register: R(10).
	return p.arch.RegisterPrefix[name] && p.peek() == '('
}

// atRegisterShift reports whether we are at the start of an ARM shifted register.
// We have consumed the register or R prefix.
func (p *Parser) atRegisterShift() bool {
	// ARM only.
	if !p.arch.InFamily(sys.ARM, sys.ARM64) {
		return false
	}
	// R1<<...
	if lex.IsRegisterShift(p.peek()) {