[arc-opts] After the arc optimizer converges, run another round of the ARC

optimizer freezing releases in the epilogue of functions that match to
SILArguments. This allows us to treat all such SILArguments throughout the
entire function as having a post dominating release.

<rdar://problem/18923030>

Swift SVN r23253

include/swift/SILAnalysis/ARCAnalysis.h

@@ -107,7 +107,14 @@ void
 destroyARCMatchingSetComputationContext(ARCMatchingSetComputationContext *Ctx);
 
 /// Use the opaque context to recompute the matching set for the input function.
+///
+/// \param Ctx The opaque context for the computation.
+/// \param FreezeOwningPtrEpiloqueReleases Should we not attempt to move, remove
+/// epilogue release pointers and instead use them as post dominating releases
+/// for other pointers.
+/// \param Fun The function to call with the ARC matching
 bool computeARCMatchingSet(ARCMatchingSetComputationContext *Ctx,
+                           bool FreezeOwningPtrEpiloqueReleases,
                            std::function<void (ARCMatchingSet&)> Fun);
 
 /// A class that attempts to match owned arguments and corresponding epilogue