https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114412
--- Comment #4 from Filip Kastl <pheeck at gcc dot gnu.org> --- (In reply to Tamar Christina from comment #3) > Hi Filip, > > Do you generate these runs with counters based PGO or compiler > instrumentation? > > Just so I know before I start trying to reproduce them. Hi Tamar, By counters you mean some sort of hardware counters? I didn't know there were multiple ways to do PGO with GCC. I think that the answer to your question is "compiler instrumentation". I just do -fprofile-generate, run the instrumented binary and then -fprofile-use.