[Bug libstdc++/51798] [4.7 regression] libstdc++ atomicity performance regression due to __sync_fetch_and_add

[dje at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51798

--- Comment #13 from David Edelsohn <dje at gcc dot gnu.org> 2012-01-26 
15:02:14 UTC ---
If libstdc++-v3 does not consistently use its own atomicity.h everywhere, then
it is even more broken.  Any code that explicitly calls __sync_* in
libstdc++-v3 has introduced a performance regression.