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/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
index f0c056f..a191610 100644
--- a/lib/CodeGen/CGExpr.cpp
+++ b/lib/CodeGen/CGExpr.cpp
@@ -104,8 +104,17 @@
   case Expr::StringLiteralClass:
     return EmitStringLiteralLValue(cast<StringLiteral>(E));
 
+  case Expr::ObjCMessageExprClass:
+    return EmitObjCMessageExprLValue(cast<ObjCMessageExpr>(E));
   case Expr::ObjCIvarRefExprClass: 
     return EmitObjCIvarRefLValue(cast<ObjCIvarRefExpr>(E));
+  case Expr::ObjCPropertyRefExprClass: {
+    // FIXME: Implement!
+    ErrorUnsupported(E, "l-value expression (Objective-C property reference)");
+    llvm::Type *Ty = llvm::PointerType::getUnqual(ConvertType(E->getType()));
+    return LValue::MakeAddr(llvm::UndefValue::get(Ty),
+                            E->getType().getCVRQualifiers());
+  }
     
   case Expr::UnaryOperatorClass: 
     return EmitUnaryOpLValue(cast<UnaryOperator>(E));
@@ -734,6 +743,14 @@
                           E->getType().getCVRQualifiers());
 }
 
+LValue CodeGenFunction::EmitObjCMessageExprLValue(const ObjCMessageExpr *E) {
+  // Can only get l-value for message expression returning aggregate type
+  RValue RV = EmitObjCMessageExpr(E);
+  // FIXME: can this be volatile?
+  return LValue::MakeAddr(RV.getAggregateAddr(),
+                          E->getType().getCVRQualifiers());
+}
+
 LValue CodeGenFunction::EmitObjCIvarRefLValue(const ObjCIvarRefExpr *E) {
   // Objective-C objects are traditionally C structures with their layout
   // defined at compile-time.  In some implementations, their layout is not