[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, 17 insertions, 1 deletions

diff --git a/clang/test/CodeGenCXX/override-bit-field-layout.cpp b/clang/test/CodeGenCXX/override-bit-field-layout.cpp
index e84fcb0f450..dee7944f6a5 100644
--- a/clang/test/CodeGenCXX/override-bit-field-layout.cpp
+++ b/clang/test/CodeGenCXX/override-bit-field-layout.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -w -fdump-record-layouts-simple -foverride-record-layout=%S/Inputs/override-bit-field-layout.layout %s | FileCheck %s
+// RUN: %clang_cc1 -w -triple=x86_64-pc-win32 -fms-compatibility -fdump-record-layouts-simple -foverride-record-layout=%S/Inputs/override-bit-field-layout.layout %s | FileCheck %s
 
 // CHECK: Type: struct S1
 // CHECK:   FieldOffsets: [0, 11]
@@ -14,7 +14,23 @@ struct S2 {
   short a : 3;
 };
 
+// CHECK: Type: struct S3
+// CHECK:   Size:32
+// CHECK:   FieldOffsets: [0, 1]
+struct S3 {
+  int a : 1;
+  int b : 2;
+};
+
+// CHECK: Type: struct S4
+// CHECK:   FieldOffsets: [32]
+struct S4 : S3 {
+  char c;
+};
+
 void use_structs() {
   S1 s1s[sizeof(S1)];
   S2 s2s[sizeof(S2)];
+  S3 s3s[sizeof(S3)];
+  S4 s4s[sizeof(S4)];
 }