If the alignment of the chosen field in a union is greater than the alignment of the union, we need to use a packed LLVM struct. Fixes <rdar://problem/7184250>.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@80964 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 1 deletions

diff --git a/lib/CodeGen/CGRecordLayoutBuilder.cpp b/lib/CodeGen/CGRecordLayoutBuilder.cpp
index 74ef2eacc9..f2fd885ee4 100644
--- a/lib/CodeGen/CGRecordLayoutBuilder.cpp
+++ b/lib/CodeGen/CGRecordLayoutBuilder.cpp
@@ -199,8 +199,15 @@ void CGRecordLayoutBuilder::LayoutUnion(const RecordDecl *D) {
   }
   
   // Now add our field.
-  if (Ty)
+  if (Ty) {
     AppendField(0, Ty);
+
+    if (getTypeAlignment(Ty) > Layout.getAlignment() / 8) {
+      // We need a packed struct.
+      Packed = true;
+      Align = 1;
+    }
+  }
   
   // Append tail padding.
   if (Layout.getSize() / 8 > Size)