Fix ctor/dtor aliases losing 'dllexport' (for Itanium ABI)

This patch makes sure that the dllexport attribute is transferred to the alias when such alias is created. It only affects the Itanium ABI because for the MSVC ABI a workaround is in place to not generate aliases of dllexport ctors/dtors.
A new CodeGenModule function is provided, CodeGenModule::setAliasAttributes, to factor the code for transferring attributes to aliases.

llvm-svn: 218159

3 files changed, 17 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 5e87fc2799c..6e7da49a44d 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -786,6 +786,16 @@ void CodeGenModule::SetCommonAttributes(const Decl *D,
     addUsedGlobal(GV);
 }
 
+void CodeGenModule::setAliasAttributes(const Decl *D,
+                                       llvm::GlobalValue *GV) {
+  SetCommonAttributes(D, GV);
+
+  // Process the dllexport attribute based on whether the original definition
+  // (not necessarily the aliasee) was exported.
+  if (D->hasAttr<DLLExportAttr>())
+    GV->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
+}
+
 void CodeGenModule::setNonAliasAttributes(const Decl *D,
                                           llvm::GlobalObject *GO) {
   SetCommonAttributes(D, GO);
diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index a095c9ddbb9..afd5b5d404f 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -1069,6 +1069,12 @@ public:
   /// NOTE: This should only be called for definitions.
   void SetCommonAttributes(const Decl *D, llvm::GlobalValue *GV);
 
+  /// Set attributes which must be preserved by an alias. This includes common
+  /// attributes (i.e. it includes a call to SetCommonAttributes).
+  ///
+  /// NOTE: This should only be called for definitions.
+  void setAliasAttributes(const Decl *D, llvm::GlobalValue *GV);
+
   void addReplacement(StringRef Name, llvm::Constant *C);
 private:
 
diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index ed7b4e9dadd..84bfb6aa505 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -3077,7 +3077,7 @@ static void emitConstructorDestructorAlias(CodeGenModule &CGM,
   }
 
   // Finally, set up the alias with its proper name and attributes.
-  CGM.SetCommonAttributes(cast<NamedDecl>(AliasDecl.getDecl()), Alias);
+  CGM.setAliasAttributes(cast<NamedDecl>(AliasDecl.getDecl()), Alias);
 }
 
 void ItaniumCXXABI::emitCXXStructor(const CXXMethodDecl *MD,