Discussion about merging Go frontend into GCC
gcc.gnu.org
gcc.gnu.org
It would seem that targeting gcc's intermediate representation and using its optimizers and backend would be a powerful paradigm for a language creator. I'm using LLVM for this in my own hobby project, but it'd be interesting to see how I could also use gcc instead.
To the best of my knowledge, the gccgo frontend is not written as a gcc plugin.