I have an idea.

Find all add, sub, mul, div operators using fx

Define Add, Sub, Mul, Div class.
Add those modules using Module.add_module

Run fx again and replace a+b to self.add(a, b)


Then those operators would be like a Module instead of  a operator. So that I can use forward_hook.
BUT IT’S EXTREMELY COMPLEX， do you have any better suggestions? @ptrblck