Code Gen Plugins

[Muhammed Fawzy]

Hi ,
    I would like to know if  it is possible with GCC Plugins to write a code 
gen plugin to modify certain things.
What I want to achieve is to use the gcc backend, but only change the way 
callsites are generated,  so the plugin should fallback to use gcc, and only 
works when gcc tries to emit code to call functions..

is this something possible with gcc?

thanks