[GCC front end] add new TREE CODE

[Andi Hellmund]

Hey Asma,
> my question is : should I also care about how to translate those tree code al
> over the compiler chain: gimple -->  ssa -->  unssa -->  rtl -->  ass ...
>    
The idea of GCC's modularization is that a front-end should maximally 
care about GIMPLE. All the other transformations are done by the 
middle-end.
> did you suggest to follow an example of an existing front end that adds some
> tree code cause the C++ one seems to be mature and complete.
>    
Yes, the C++ front-end uses quite a lot of own TREE codes, but I would 
then start with a very simple one and check how it "translates" the TREE 
codes into a GIMPLE sequence, e.g. by looking at the 'gimplify_expr' 
language hook which is 'cp_gimplify_expr' for C++.

I hope that helps. If you have any further question about the specific 
transformation from TREE codes to GIMPLE, just let us know ...

Andi