These patches are still awaiting review. Use __builtin_unreachable() in gcc_assert(): http://gcc.gnu.org/ml/gcc-patches/2009-07/msg00408.html Fix several ICEs that were found with __builtin_unreachable(): http://gcc.gnu.org/ml/gcc-patches/2009-06/msg01267.html http://gcc.gnu.org/ml/gcc-patches/2009-06/msg01978.html