swift234

IRGen: Use stable backreferences when profiling circular archetype references.

<T where T.Foo == T.Bar> and <U where U.Foo == U.Bar> have the same profile, even though the archetypes have different pointers, so we shouldn't use the archetype pointer to profile a backreference to an already-seen archetype. Fixes <rdar://problem/16236728>.

Swift SVN r14687