[Bug gcov-profile/80952] gcc 7.1.1 has a drastic performance downgrade using "-fprofile-arcs" compared to 6.3.1 version

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80952

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I suspect this is due to using atomic increments for the profile data now.
Before there were many race conditions and profile arch would produce incorrect
values for threaded (openmp is such) code.