MS ABI: Up the required alignment after inserting padding between vbases

We would correctly insert sufficiently aligned padding between vbases
when our leading base was empty, however we would neglect to increase
the required alignment of the most derived class.

This fixes PR20315.

llvm-svn: 213123

1 files changed, 55 insertions, 0 deletions

diff --git a/clang/test/Layout/ms-x86-pack-and-align.cpp b/clang/test/Layout/ms-x86-pack-and-align.cpp
index be0499c2cbb..73984652aeb 100644
--- a/clang/test/Layout/ms-x86-pack-and-align.cpp
+++ b/clang/test/Layout/ms-x86-pack-and-align.cpp
@@ -544,6 +544,60 @@ struct RE {
 // CHECK-X64-NEXT:      | [sizeof=1029, align=1
 // CHECK-X64-NEXT:      |  nvsize=1029, nvalign=1]
 
+struct NA {};
+struct NB {};
+#pragma pack(push, 1)
+struct NC : virtual NA, virtual NB {};
+#pragma pack(pop)
+struct ND : NC {};
+
+// CHECK: *** Dumping AST Record Layout
+// CHECK-NEXT:    0 | struct NA (empty)
+// CHECK-NEXT:      | [sizeof=1, align=1
+// CHECK-NEXT:      |  nvsize=0, nvalign=1]
+// CHECK: *** Dumping AST Record Layout
+// CHECK-NEXT:    0 | struct NB (empty)
+// CHECK-NEXT:      | [sizeof=1, align=1
+// CHECK-NEXT:      |  nvsize=0, nvalign=1]
+// CHECK: *** Dumping AST Record Layout
+// CHECK-NEXT:    0 | struct NC
+// CHECK-NEXT:    0 |   (NC vbtable pointer)
+// CHECK-NEXT:    4 |   struct NA (virtual base) (empty)
+// CHECK-NEXT:    8 |   struct NB (virtual base) (empty)
+// CHECK-NEXT:      | [sizeof=8, align=1
+// CHECK-NEXT:      |  nvsize=4, nvalign=1]
+// CHECK: *** Dumping AST Record Layout
+// CHECK-NEXT:    0 | struct ND
+// CHECK-NEXT:    0 |   struct NC (base)
+// CHECK-NEXT:    0 |     (NC vbtable pointer)
+// CHECK-NEXT:    4 |   struct NA (virtual base) (empty)
+// CHECK-NEXT:    8 |   struct NB (virtual base) (empty)
+// CHECK-NEXT:      | [sizeof=8, align=4
+// CHECK-NEXT:      |  nvsize=4, nvalign=4]
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64-NEXT:    0 | struct NA (empty)
+// CHECK-X64-NEXT:      | [sizeof=1, align=1
+// CHECK-X64-NEXT:      |  nvsize=0, nvalign=1]
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64-NEXT:    0 | struct NB (empty)
+// CHECK-X64-NEXT:      | [sizeof=1, align=1
+// CHECK-X64-NEXT:      |  nvsize=0, nvalign=1]
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64-NEXT:    0 | struct NC
+// CHECK-X64-NEXT:    0 |   (NC vbtable pointer)
+// CHECK-X64-NEXT:    8 |   struct NA (virtual base) (empty)
+// CHECK-X64-NEXT:   12 |   struct NB (virtual base) (empty)
+// CHECK-X64-NEXT:      | [sizeof=12, align=1
+// CHECK-X64-NEXT:      |  nvsize=8, nvalign=1]
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64-NEXT:    0 | struct ND
+// CHECK-X64-NEXT:    0 |   struct NC (base)
+// CHECK-X64-NEXT:    0 |     (NC vbtable pointer)
+// CHECK-X64-NEXT:    8 |   struct NA (virtual base) (empty)
+// CHECK-X64-NEXT:   12 |   struct NB (virtual base) (empty)
+// CHECK-X64-NEXT:      | [sizeof=12, align=4
+// CHECK-X64-NEXT:      |  nvsize=8, nvalign=4]
+
 int a[
 sizeof(X)+
 sizeof(Y)+
@@ -568,4 +622,5 @@ sizeof(RB2)+
 sizeof(RB3)+
 sizeof(RC)+
 sizeof(RE)+
+sizeof(ND)+
 0];