How to makeup two word in tablegen like Micro fun in C language

like this:
class register;
def M : register;
def M_A : register;
def M_B : register;
class ins{
…<n#_A>…;
…<n#_B>…;
}
def my_ins < M > : …;

I’m not 100% sure I understand the question, but you might want !cast<register>(M # "_A") (assuming ins takes a string parameter you’re calling M).

Yes, that is what I need.
thanks.