instrument the HIR by synthesizing code and inserting it

[lpxz]

Another question,
I am aware that graal can easily remove nodes and duplicate nodes in the 
graphical IR representation.
I wonder if does graal provide the APIs for synthesizing new nodes and 
inserting them. For example, I want to insert the
counter implementation to each control flow edge to profile the 
execution frequency of each CFG edge.

Thanks a lot!

Regards
Peng