From: Martin Storsjo <martin@martin.st>
Date: Thu, 31 Aug 2017 08:29:59 +0000 (+0000)
Subject: [ItaniumCXXABI] Always use linkonce_odr linkage for RTTI data on MinGW
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=2c5db5c3849cf368aa6a8e808ed7485c5b60f413;p=clang

[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

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@312224 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/ItaniumCXXABI.cpp b/lib/CodeGen/ItaniumCXXABI.cpp
index d78c032cec..e07dbdd3ab 100644
--- a/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/lib/CodeGen/ItaniumCXXABI.cpp
@@ -2998,15 +2998,13 @@ static llvm::GlobalVariable::LinkageTypes getTypeInfoLinkage(CodeGenModule &CGM,
         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;
diff --git a/test/CodeGenCXX/rtti-mingw64.cpp b/test/CodeGenCXX/rtti-mingw64.cpp
index 818b11b64b..9f3e03961e 100644
--- a/test/CodeGenCXX/rtti-mingw64.cpp
+++ b/test/CodeGenCXX/rtti-mingw64.cpp
@@ -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),