Yeah, everyone please go contribute code to LLVM! LLVM is very pleasant to hack on with a genuinely clean design, unlike GCC, which is just a big nasty mess. Hacking on LLVM is fun, hacking on GCC is a chore.

"Reload is the GCC equivalent of Satan." http://gcc.gnu.org/wiki/reload

GCC's internal garbage collector. Yes, they really wrote a garbage collector for a C app, and dealing with it is just as pleasant as you'd imagine. http://gcc.gnu.org/wiki/Memory_management