Adding statement to an already defined function

[Nikola Ikonic <nikola dot ikonic at gmail dot com>]

Hello,

I am working on modifying GCC and I would like to ask you one question.

I am trying figure out a way to add an external statement to already
generated function. Is that possible?

For example, let's say that if I want to check is function with name
"DoSomething" already generated/parsed (bottom line, does it exist).
Can I do that somehow? And if I can, is there a way to add new
statement (e.g call of some function) into to
body of "DoSomething"?

This situation could for example happen when the "DoSomething" is in
A.c file and the compiler is currently parsing B.c and it needs to
look has DoSomething been already processed in files before (in this
case A.c file).

Is that possible somehow?

Thank you in advance!

Best regards,
      Nikola