[Bug libstdc++/54005] Use __atomic_always_lock_free in libstdc++ is_lock_free instead of __atomic_is_lock_free

[amacleod at redhat dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54005

--- Comment #9 from Andrew Macleod <amacleod at redhat dot com> 2012-08-14 22:44:53 UTC ---
Actually, that's the way __atomic_is_lock_free()  has always been implemented
(even in 4.7).  

The change is simply wrong and needs to be reverted.  __atomic_is_lock_free()
*must* call the library routine of the same name if the compiler can't generate
the lock free sequence.  That's the way the 2 routines were designed to
inter-operate. The current code introduces an new upgrade path bug, so its
fixing a problem in the wrong place and introducing another.

And yes, 54004 is legitimate and separate from this issue. Fixing that by
giving targets a say in what atomic alignment is will resolve this one without
any changes.