r312224 - [ItaniumCXXABI] Always use linkonce_odr linkage for RTTI data on MinGW

[Martin Storsjo via cfe-commits]

Author: mstorsjo
Date: Thu Aug 31 01:29:59 2017
New Revision: 312224

URL: http://llvm.org/viewvc/llvm-project?rev=312224&view=rev
Log:
[ItaniumCXXABI] Always use linkonce_odr linkage for RTTI data on MinGW

This fixes cases where dynamic classes produced RTTI data with
external linkage, producing linker errors about duplicate symbols.

This touches code close to what was changed in SVN r244266, but
this change doesn't break the tests added in that revision.

Differential revision: https://reviews.llvm.org/D37206

Modified:
    cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp
    cfe/trunk/test/CodeGenCXX/rtti-mingw64.cpp

Modified: cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp?rev=312224&r1=312223&r2=312224&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp (original)
+++ cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp Thu Aug 31 01:29:59 2017
@@ -2998,15 +2998,13 @@ static llvm::GlobalVariable::LinkageType
         if (RD->hasAttr<DLLImportAttr>() &&
             ShouldUseExternalRTTIDescriptor(CGM, Ty))
           return llvm::GlobalValue::ExternalLinkage;
-      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;
-      }
+      // MinGW always uses LinkOnceODRLinkage for type info.
+      if (RD->isDynamicClass() &&
+          !CGM.getContext()
+               .getTargetInfo()
+               .getTriple()
+               .isWindowsGNUEnvironment())
+        return CGM.getVTableLinkage(RD);
     }
 
     return llvm::GlobalValue::LinkOnceODRLinkage;

Modified: cfe/trunk/test/CodeGenCXX/rtti-mingw64.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/rtti-mingw64.cpp?rev=312224&r1=312223&r2=312224&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/rtti-mingw64.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/rtti-mingw64.cpp Thu Aug 31 01:29:59 2017
@@ -2,7 +2,12 @@
 struct A { int a; };
 struct B : virtual A { int b; };
 B b;
+class C {
+  virtual ~C();
+};
+C::~C() {}
 
+// CHECK: @_ZTI1C = linkonce_odr
 // CHECK: @_ZTI1B = linkonce_odr constant { i8*, i8*, i32, i32, i8*, i64 }
 // CHECK-SAME:  i8* bitcast (i8** getelementptr inbounds (i8*, i8** @_ZTVN10__cxxabiv121__vmi_class_type_infoE, i64 2) to i8*),
 // CHECK-SAME:  i8* getelementptr inbounds ([3 x i8], [3 x i8]* @_ZTS1B, i32 0, i32 0),