naive question about porting

[Erick Alphonse]

Hello all,

I'm taking advantage of the recent thread about porting to ask you some 
questions about it:
- What are the pros and cons of porting compared to writing a front-end 
to a compiler like gcc?
- Is the result the same? Or are there some things platform-specific 
that can not be handled by gcc?
- By writing a front-end to gcc, can one benefit from some optimisations 
made by gcc? In other words, does gcc perform optimisation on its 
"abstract machine code"?

Thank you a lot for any information,
Regards,
Erick.