[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, 6 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index f992f904fe7..ca6b1d409c2 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -1047,8 +1047,13 @@ void CodeGenFunction::ExpandTypeFromArgs(
     auto imagValue = *AI++;
     EmitStoreOfComplex(ComplexPairTy(realValue, imagValue), LV, /*init*/ true);
   } else {
+    // Call EmitStoreOfScalar except when the lvalue is a bitfield to emit a
+    // primitive store.
     assert(isa<NoExpansion>(Exp.get()));
-    EmitStoreThroughLValue(RValue::get(*AI++), LV);
+    if (LV.isBitField())
+      EmitStoreThroughLValue(RValue::get(*AI++), LV);
+    else
+      EmitStoreOfScalar(*AI++, LV);
   }
 }