[CodeGen][ObjC] Emit a primitive store to store a __strong field in

ExpandTypeFromArgs

This fixes a bug in IRGen where a call to `llvm.objc.storeStrong` was
being emitted to initialize a __strong field of an uninitialized
temporary struct, which caused crashes at runtime.

rdar://problem/51807365

1 files changed, 5 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 6e3a26e2c78..cd42faefab0 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -4544,7 +4544,11 @@ RValue CodeGenFunction::EmitRValueForField(LValue LV,
     // don't load reference fields.
     if (FD->getType()->isReferenceType())
       return RValue::get(FieldLV.getPointer(*this));
-    return EmitLoadOfLValue(FieldLV, Loc);
+    // Call EmitLoadOfScalar except when the lvalue is a bitfield to emit a
+    // primitive load.
+    if (FieldLV.isBitField())
+      return EmitLoadOfLValue(FieldLV, Loc);
+    return RValue::get(EmitLoadOfScalar(FieldLV, Loc));
   }
   llvm_unreachable("bad evaluation kind");
 }