See <file:///usr/share/doc/gcc-4.8/README.Bugs> for instructions.
The bug is not reproducible, so it is likely a hardware or OS problem.
The last line above may be relevant. "When debian gcc encounters an internal error it tries to run the code through the compilation core again. If it gets the same results every time it assumes it really is a bug in the compiler core. If it doesn't then you get the "The bug is not reproducible, so it is likely a hardware or OS problem." message." Can you reproduce this on a different machine, or run memtest on the problematic one?