Implement Obj-C ivar references to aggregates.

Implement Obj-C lvalue message sends (aggregate returns).

Update several places to emit more precise ErrorUnsupported warnings
  for currently unimplemented Obj-C features (main missing chunks are
  property references, Obj-C exception handling, and the for ... in
  syntax).


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@55234 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGExprScalar.cpp b/lib/CodeGen/CGExprScalar.cpp
index ddf1421..3f7b737 100644
--- a/lib/CodeGen/CGExprScalar.cpp
+++ b/lib/CodeGen/CGExprScalar.cpp
@@ -134,6 +134,13 @@
   Value *VisitObjCSelectorExpr(ObjCSelectorExpr *E);
   Value *VisitObjCProtocolExpr(ObjCProtocolExpr *E);
   Value *VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) { return EmitLoadOfLValue(E);}
+  Value *VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) {
+    CGF.ErrorUnsupported(E, "scalar expression (Objective-C property reference)");
+    if (E->getType()->isVoidType())
+      return 0;
+    return llvm::UndefValue::get(CGF.ConvertType(E->getType()));    
+  }
+
   Value *VisitArraySubscriptExpr(ArraySubscriptExpr *E);
   Value *VisitShuffleVectorExpr(ShuffleVectorExpr *E);
   Value *VisitMemberExpr(Expr *E)           { return EmitLoadOfLValue(E); }