Unnamed bit-fields in a union should be laid out with a type that doesn't affect alignment.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@101673 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGRecordLayoutBuilder.cpp b/lib/CodeGen/CGRecordLayoutBuilder.cpp
index 60ef7fe..215b39e 100644
--- a/lib/CodeGen/CGRecordLayoutBuilder.cpp
+++ b/lib/CodeGen/CGRecordLayoutBuilder.cpp
@@ -332,10 +332,26 @@
if (FieldSize == 0)
return 0;
+ const llvm::Type *FieldTy;
+
+ if (!Field->getDeclName()) {
+ // This is an unnamed bit-field, which shouldn't affect alignment on the
+ // struct so we use an array of bytes for it.
+
+ FieldTy = llvm::Type::getInt8Ty(Types.getLLVMContext());
+
+ unsigned NumBytesToAppend =
+ llvm::RoundUpToAlignment(FieldSize, 8) / 8;
+
+ if (NumBytesToAppend > 1)
+ FieldTy = llvm::ArrayType::get(FieldTy, NumBytesToAppend);
+ } else
+ FieldTy = Types.ConvertTypeForMemRecursive(Field->getType());
+
// Add the bit field info.
LLVMBitFields.push_back(
LLVMBitFieldInfo(Field, ComputeBitFieldInfo(Types, Field, 0, FieldSize)));
- return Types.ConvertTypeForMemRecursive(Field->getType());
+ return FieldTy;
}
// This is a regular union field.
diff --git a/test/CodeGenCXX/bitfield-layout.cpp b/test/CodeGenCXX/bitfield-layout.cpp
index c77c925..9425019 100644
--- a/test/CodeGenCXX/bitfield-layout.cpp
+++ b/test/CodeGenCXX/bitfield-layout.cpp
@@ -1,9 +1,17 @@
// RUN: %clang_cc1 %s -triple=x86_64-apple-darwin10 -emit-llvm -o - | FileCheck %s
-// CHECK: = type { i32, [4 x i8] }
+// CHECK: %union.Test1 = type { i32, [4 x i8] }
union Test1 {
int a;
int b: 39;
-};
+} t1;
-Test1 t1;
+// CHECK: %union.Test2 = type { i8 }
+union Test2 {
+ int : 6;
+} t2;
+
+// CHECK: %union.Test3 = type { [2 x i8] }
+union Test3 {
+ int : 9;
+} t3;