[MS] Always use base dtors in place of complete/vbase dtors when possible

Summary:
Previously we tried too hard to uphold the fiction that destructor
variants work like they do on Itanium throughout the ABI-neutral parts
of clang. This lead to MS C++ ABI incompatiblities and other bugs. Now,
-mconstructor-aliases will no longer control this ABI detail, and clang
-cc1's LLVM IR output will be this much closer to the clang driver's.

Based on a patch by Zahira Ammarguellat:
  https://reviews.llvm.org/D39063

I've tried to move the logic that Zahira added into MicrosoftCXXABI.cpp.
There is only one ABI-specific detail sticking out, and that is in
CodeGenModule::getAddrOfCXXStructor, where we collapse complete dtors to
base dtors in the MS ABI.

This fixes PR32990.

Reviewers: erichkeane, zahiraam, majnemer, rjmccall

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D44505

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@327732 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 1 insertions, 1 deletions

diff --git a/test/CodeGenCXX/dllexport-dtor-thunks.cpp b/test/CodeGenCXX/dllexport-dtor-thunks.cpp
index 45cce8bb6a..935dfa5166 100644
--- a/test/CodeGenCXX/dllexport-dtor-thunks.cpp
+++ b/test/CodeGenCXX/dllexport-dtor-thunks.cpp
@@ -5,6 +5,6 @@ struct __declspec(dllexport) B { virtual ~B(); };
 struct __declspec(dllexport) C : A, B { virtual ~C(); };
 C::~C() {}
 
+// CHECK: define dso_local dllexport void @"\01??1C@@UEAA@XZ"
 // This thunk should *not* be dllexport.
 // CHECK: define linkonce_odr dso_local i8* @"\01??_EC@@W7EAAPEAXI@Z"
-// CHECK: define dso_local dllexport void @"\01??1C@@UEAA@XZ"