r218159 - Fix ctor/dtor aliases losing 'dllexport' (for Itanium ABI)

[Dario Domizioli]

Author: ddomizioli
Date: Fri Sep 19 17:06:24 2014
New Revision: 218159

URL: http://llvm.org/viewvc/llvm-project?rev=218159&view=rev
Log:
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.


Added:
    cfe/trunk/test/CodeGenCXX/dllexport-alias.cpp
Modified:
    cfe/trunk/lib/CodeGen/CodeGenModule.cpp
    cfe/trunk/lib/CodeGen/CodeGenModule.h
    cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp

Modified: cfe/trunk/lib/CodeGen/CodeGenModule.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenModule.cpp?rev=218159&r1=218158&r2=218159&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenModule.cpp (original)
+++ cfe/trunk/lib/CodeGen/CodeGenModule.cpp Fri Sep 19 17:06:24 2014
@@ -786,6 +786,16 @@ void CodeGenModule::SetCommonAttributes(
     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);

Modified: cfe/trunk/lib/CodeGen/CodeGenModule.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenModule.h?rev=218159&r1=218158&r2=218159&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenModule.h (original)
+++ cfe/trunk/lib/CodeGen/CodeGenModule.h Fri Sep 19 17:06:24 2014
@@ -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:
 

Modified: cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp?rev=218159&r1=218158&r2=218159&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp (original)
+++ cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp Fri Sep 19 17:06:24 2014
@@ -3077,7 +3077,7 @@ static void emitConstructorDestructorAli
   }
 
   // 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,

Added: cfe/trunk/test/CodeGenCXX/dllexport-alias.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/dllexport-alias.cpp?rev=218159&view=auto
==============================================================================
--- cfe/trunk/test/CodeGenCXX/dllexport-alias.cpp (added)
+++ cfe/trunk/test/CodeGenCXX/dllexport-alias.cpp Fri Sep 19 17:06:24 2014
@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 -triple x86_64-windows-gnu -mconstructor-aliases %s -S -emit-llvm -o - | FileCheck %s
+
+// This test assumes that the C1 constructor will be aliased to the C2
+// constructor, and the D1 destructor to the D2. It then checks that the aliases
+// are dllexport'ed.
+
+class __declspec(dllexport) A {
+public:
+    A();
+    ~A();
+};
+
+A::A() {}
+
+A::~A() {}
+
+// CHECK: @_ZN1AC1Ev = dllexport alias void (%class.A*)* @_ZN1AC2Ev
+// CHECK: @_ZN1AD1Ev = dllexport alias void (%class.A*)* @_ZN1AD2Ev