[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, 8 insertions, 0 deletions

diff --git a/lib/CodeGen/CGCXXABI.h b/lib/CodeGen/CGCXXABI.h
index 65a4c3d072..1e4e13273a 100644
--- a/lib/CodeGen/CGCXXABI.h
+++ b/lib/CodeGen/CGCXXABI.h
@@ -319,6 +319,14 @@ public:
   virtual bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor,
                                       CXXDtorType DT) const = 0;
 
+  virtual void setCXXDestructorDLLStorage(llvm::GlobalValue *GV,
+                                          const CXXDestructorDecl *Dtor,
+                                          CXXDtorType DT) const;
+
+  virtual llvm::GlobalValue::LinkageTypes
+  getCXXDestructorLinkage(GVALinkage Linkage, const CXXDestructorDecl *Dtor,
+                          CXXDtorType DT) const;
+
   /// Emit destructor variants required by this ABI.
   virtual void EmitCXXDestructors(const CXXDestructorDecl *D) = 0;