Check first member alignment and uses packed struct if required.

llvm-svn: 51619

2 files changed, 5 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CodeGenTypes.cpp b/clang/lib/CodeGen/CodeGenTypes.cpp
index aa0d2ed0531..5efde77a7d2 100644
--- a/clang/lib/CodeGen/CodeGenTypes.cpp
+++ b/clang/lib/CodeGen/CodeGenTypes.cpp
@@ -516,6 +516,8 @@ void RecordOrganizer::layoutStructFields(const ASTRecordLayout &RL) {
       unsigned Align = CGT.getTargetData().getABITypeAlignment(Ty) * 8;
       if (llvmSize % Align)
         packedStruct = true;
+      else if (offset == 0 && RL.getAlignment() % Align)
+        packedStruct = true;
 
       llvmSize += size;
       CGT.addFieldInfo(FD, LLVMFields.size());
diff --git a/clang/test/CodeGen/struct.c b/clang/test/CodeGen/struct.c
index 4c88c2539fd..f17a7af76c8 100644
--- a/clang/test/CodeGen/struct.c
+++ b/clang/test/CodeGen/struct.c
@@ -160,3 +160,6 @@ int f14(int i, ...) {
   a13 b = __builtin_va_arg(l, a13);
   return b.b;
 }
+
+/* Attribute packed */
+struct __attribute__((packed)) S2839 { double a[19];  signed char b; } s2839[5];