[PATCH] [-cxx-abi microsoft] Emit thunks for pointers to virtual member functions

[Hans Wennborg]

  Thanks for all the comments! Committing.


================
Comment at: lib/CodeGen/CodeGenFunction.h:1159
@@ +1158,3 @@
+  void EmitCallAndReturnForThunk(GlobalDecl GD, llvm::Value *Callee,
+                                 llvm::Value *ThisPtr,
+                                 const ThunkInfo *Thunk);
----------------
Timur Iskhodzhanov wrote:
> Do you need ThisPtr as a parameter yet?
> You pass `CGF.LoadCXXThis()` as an argument in both places.
Done.

================
Comment at: lib/CodeGen/MicrosoftCXXABI.cpp:993
@@ +992,3 @@
+  LinkageInfo LV = MD->getLinkageAndVisibility();
+  ThunkFn->setLinkage(LV.getLinkage() != ExternalLinkage
+                          ? llvm::GlobalValue::InternalLinkage
----------------
Reid Kleckner wrote:
> I think you really want MD->isExternallyVisible() to handle the VisibleNoLinkage case, which would be triggered by something evil like:
> 
>   inline __forceinline bool foo(bool set_mp) {
>     struct B {
>       virtual void f() {}
>       static bool compare_mps(void (B::*mp1)(), void (B::*mp2)()) {
>         return mp1 == mp2;
>       }
>     };
>     if (set_mp)
>       mp = reinterpret_cast<void (A::*)()>(&B::f);
>     return B::compare_mps(&B::f, reinterpret_cast<void (B::*)()>(mp));
>   }
> 
> If you use internal linkage here, you'll get two distinct thunks, and the comparison will be false when it shouldn't be.
Done.


http://llvm-reviews.chandlerc.com/D2104