r244266 - [ItaniumCXXABI] Don't import RTTI data for classes with key functions

[David Majnemer via cfe-commits]

Author: majnemer
Date: Thu Aug  6 15:56:55 2015
New Revision: 244266

URL: http://llvm.org/viewvc/llvm-project?rev=244266&view=rev
Log:
[ItaniumCXXABI] Don't import RTTI data for classes with key functions

MinGW has some pretty strange behvaior around RTTI and
dllimport/dllexport:
- RTTI data is never imported
- RTTI data is only exported if the class has no key function.

Modified:
    cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp
    cfe/trunk/test/CodeGenCXX/dllimport-rtti.cpp

Modified: cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp?rev=244266&r1=244265&r2=244266&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp (original)
+++ cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp Thu Aug  6 15:56:55 2015
@@ -2450,10 +2450,13 @@ static bool ShouldUseExternalRTTIDescrip
 
     // FIXME: this may need to be reconsidered if the key function
     // changes.
+    // N.B. We must always emit the RTTI data ourselves if there exists a key
+    // function.
+    bool IsDLLImport = RD->hasAttr<DLLImportAttr>();
     if (CGM.getVTables().isVTableExternal(RD))
-      return true;
+      return IsDLLImport ? false : true;
 
-    if (RD->hasAttr<DLLImportAttr>())
+    if (IsDLLImport)
       return true;
   }
 
@@ -2683,8 +2686,15 @@ static llvm::GlobalVariable::LinkageType
       const CXXRecordDecl *RD = cast<CXXRecordDecl>(Record->getDecl());
       if (RD->hasAttr<WeakAttr>())
         return llvm::GlobalValue::WeakODRLinkage;
-      if (RD->isDynamicClass())
-        return CGM.getVTableLinkage(RD);
+      if (RD->isDynamicClass()) {
+        llvm::GlobalValue::LinkageTypes LT = CGM.getVTableLinkage(RD);
+        // MinGW won't export the RTTI information when there is a key function.
+        // Make sure we emit our own copy instead of attempting to dllimport it.
+        if (RD->hasAttr<DLLImportAttr>() &&
+            llvm::GlobalValue::isAvailableExternallyLinkage(LT))
+          LT = llvm::GlobalValue::LinkOnceODRLinkage;
+        return LT;
+      }
     }
 
     return llvm::GlobalValue::LinkOnceODRLinkage;

Modified: cfe/trunk/test/CodeGenCXX/dllimport-rtti.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/dllimport-rtti.cpp?rev=244266&r1=244265&r2=244266&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/dllimport-rtti.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/dllimport-rtti.cpp Thu Aug  6 15:56:55 2015
@@ -15,3 +15,10 @@ struct __declspec(dllimport) S {
 
 struct U : S {
 } u;
+
+struct __declspec(dllimport) V {
+  virtual void f();
+} v;
+// GNU-DAG: @_ZTV1V = available_externally dllimport
+// GNU-DAG: @_ZTS1V = linkonce_odr
+// GNU-DAG: @_ZTI1V = linkonce_odr