LLVM has another C-language family front-end called
CLANG which can speed up compilation in optimization mode
(-O2/-O3) upto 20%-25%.  So even as LLVM optimizations
are not faster than GCC optimizations, CLANG front-end is really
faster than GCC-frontend.  I think GCC community should pay more attention
to this fact.  Fortunately, a few new GCC projects address to this problem
and I hope this problem will be solved or alleviated.

http://gcc.gnu.org/ml/gcc/2011-09/msg00043.html
и соответственно тесты
http://vmakarov.fedorapeople.org/spec/