[Attributor] We (should) keep the CG updated so we can mark it as preserved

Author: jdoerfert

llvm/lib/Transforms/IPO/Attributor.cpp

@@ -2324,7 +2324,9 @@ PreservedAnalyses AttributorCGSCCPass::run(LazyCallGraph::SCC &C,
   InformationCache InfoCache(M, AG, Allocator, /* CGSCC */ &Functions);
   if (runAttributorOnFunctions(InfoCache, Functions, AG, CGUpdater)) {
     // FIXME: Think about passes we will preserve and add them here.
-    return PreservedAnalyses::none();
+    PreservedAnalyses PA;
+    PA.preserve<FunctionAnalysisManagerCGSCCProxy>();
+    return PA;
   }
   return PreservedAnalyses::all();
 }