http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32089
--- Comment #8 from Jan Hubicka <hubicka at gcc dot gnu.org> 2012-05-23 15:07:13 UTC --- Yes, it is a prediction of future, see http://citeseer.ist.psu.edu/viewdoc/summary?doi=10.1.1.43.6404 for details. Inline decision and branch prediction is set of heuristics that are based on common observations of the program behaviour. You can use -fprofile-generate/-fprofile-use when this technique fails (or provide self contained testcases how the heuristics can be improved)
