[AST] Improve support of external layouts in `MicrosoftRecordLayoutBuilder`

Summary:
This patch fixes several small problems with external layouts support in
`MicrosoftRecordLayoutBuilder`:
- aligns properly the size of a struct that ends with a bit field. It was
  aligned on byte before, not on the size of the field, so the struct size was
  smaller than it should be;
- adjusts the struct size when injecting a vbptr in the case when there were no
  bases or fields allocated after the vbptr. Similarly, without the adjustment
  the struct was smaller than it should be;
- the same fix as above for the vfptr.
All these fixes affect the non-virtual size of a struct, so they are tested
through non-virtual inheritance.

Reviewers: rnk, zturner, rsmith

Reviewed By: rnk

Subscribers: jdoerfert, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D58544

llvm-svn: 356047

1 files changed, 20 insertions, 1 deletions

diff --git a/clang/test/CodeGenCXX/override-layout.cpp b/clang/test/CodeGenCXX/override-layout.cpp
index a3c4bb446ca..fea2a45c629 100644
--- a/clang/test/CodeGenCXX/override-layout.cpp
+++ b/clang/test/CodeGenCXX/override-layout.cpp
@@ -64,6 +64,23 @@ struct PACKED X5 {
   short r;
 };
 
+// CHECK: Type: struct X6
+struct __attribute__((aligned(16))) X6 {
+  int x;
+  int y;
+  virtual ~X6();
+};
+
+// CHECK: Type: struct X7
+struct X7 {
+  int z;
+};
+
+// CHECK: Type: struct X8
+struct X8 : X6, virtual X7 {
+  char c;
+};
+
 void use_structs() {
   X0 x0s[sizeof(X0)];
   X1 x1s[sizeof(X1)];
@@ -71,7 +88,9 @@ void use_structs() {
   X3 x3s[sizeof(X3)];
   X4 x4s[sizeof(X4)];
   X5 x5s[sizeof(X5)];
+  X6 x6s[sizeof(X6)];
+  X7 x7s[sizeof(X7)];
+  X8 x8s[sizeof(X8)];
   x4s[1].a = 1;
   x5s[1].a = 17;
 }
-