[ownership] Add another run of SemanticARCOpts right before eliminating ARC on the stdlib functions.

This just canonicalizes the ARC before we lower OME in the face of ARC twiddles
by other passes.

Author: gottesmm

lib/SILOptimizer/PassManager/PassPipeline.cpp

@@ -300,7 +300,8 @@ void addFunctionPasses(SILPassPipelinePlan &P,
   P.addMem2Reg();
 
   // We earlier eliminated ownership if we are not compiling the stdlib. Now
-  // handle the stdlib functions.
+  // handle the stdlib functions, re-simplifying, eliminating ARC as we do.
+  P.addSemanticARCOpts();
   P.addNonTransparentFunctionOwnershipModelEliminator();
 
   // Run the existential specializer Pass.

lib/SILOptimizer/SemanticARC/SemanticARCOpts.cpp

@@ -100,8 +100,10 @@ struct SemanticARCOpts : SILFunctionTransform {
   void run() override {
     SILFunction &f = *getFunction();
 
-    // Return early if we are not performing OSSA optimizations.
-    if (!f.getModule().getOptions().EnableOSSAOptimizations)
+    // Return early if we are not performing OSSA optimizations or we are not in
+    // ownership.
+    if (!f.getModule().getOptions().EnableOSSAOptimizations ||
+        !f.hasOwnership())
       return;
 
     // Make sure we are running with ownership verification enabled.