https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63671
--- Comment #20 from Markus Trippelsdorf <trippels at gcc dot gnu.org> --- At some point you start measuring processor characteristics. On my old AMD box (Phenom II) gcc-5 now is the fastest: -Ofast : 2.9 -O3 : 3.6 PGO/-Ofast: 2.7 gcc-4.9: -Ofast : 3.0 -O3 : 3.7 PGO/-Ofast: 2.8 gcc-4.8: -Ofast : 3.4 -O3 : 4.0 PGO/-Ofast: 3.1
