[Clang] Apply exclude_from_explicit_instantiation to dllimport/dllexport

clang/lib/Sema/SemaDeclCXX.cpp

@@ -6551,6 +6551,8 @@ void Sema::checkClassLevelDLLAttribute(CXXRecordDecl *Class) {
     return;
   }
 
+  TemplateSpecializationKind TSK = Class->getTemplateSpecializationKind();
+
   if (Context.getTargetInfo().shouldDLLImportComdatSymbols() &&
       !ClassAttr->isInherited()) {
     // Diagnose dll attributes on members of class with dll attribute.
@@ -6561,6 +6563,11 @@ void Sema::checkClassLevelDLLAttribute(CXXRecordDecl *Class) {
       if (!MemberAttr || MemberAttr->isInherited() || Member->isInvalidDecl())
         continue;
 
+      if ((TSK == TSK_ExplicitInstantiationDeclaration ||
+           TSK == TSK_ExplicitInstantiationDefinition) &&
+          Member->hasAttr<ExcludeFromExplicitInstantiationAttr>())
+        continue;
+
       Diag(MemberAttr->getLocation(),
              diag::err_attribute_dll_member_of_dll_class)
           << MemberAttr << ClassAttr;
@@ -6583,8 +6590,6 @@ void Sema::checkClassLevelDLLAttribute(CXXRecordDecl *Class) {
       !ClassExported &&
       cast<DLLImportAttr>(ClassAttr)->wasPropagatedToBaseTemplate();
 
-  TemplateSpecializationKind TSK = Class->getTemplateSpecializationKind();
-
   // Ignore explicit dllexport on explicit class template instantiation
   // declarations, except in MinGW mode.
   if (ClassExported && !ClassAttr->isInherited() &&
@@ -6601,6 +6606,11 @@ void Sema::checkClassLevelDLLAttribute(CXXRecordDecl *Class) {
   // seem to be true in practice?
 
   for (Decl *Member : Class->decls()) {
+    if ((TSK == TSK_ExplicitInstantiationDeclaration ||
+         TSK == TSK_ExplicitInstantiationDefinition) &&
+        Member->hasAttr<ExcludeFromExplicitInstantiationAttr>())
+      continue;
+
     VarDecl *VD = dyn_cast<VarDecl>(Member);
     CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Member);
 
@@ -19108,8 +19118,23 @@ bool Sema::DefineUsedVTables() {
         }
       }
 
-      if (IsExplicitInstantiationDeclaration)
+      if (IsExplicitInstantiationDeclaration) {
         DefineVTable = false;
+
+        // Ensure the instance of a virtual member function which is declared
+        // with `__attribute__((exclude_from_explicit_instantiation))` is
+        // accessible from the VTable.
+        for (Decl *decl : Class->decls()) {
+          auto *Method = dyn_cast<CXXMethodDecl>(decl);
+          if (!Method || !Method->isVirtual())
+            continue;
+
+          if (Method->hasAttr<ExcludeFromExplicitInstantiationAttr>()) {
+            MarkFunctionReferenced(Loc, Method);
+            DefinedAnything = true;
+          }
+        }
+      }
     }
 
     // The exception specifications for all virtual members may be needed even

clang/test/CodeGenCXX/attr-exclude_from_explicit_instantiation.exclude_from_dllexport.cpp

@@ -0,0 +1,171 @@
+// RUN: %clang_cc1 -triple x86_64-win32 -fms-extensions -emit-llvm -o - %s | \
+// RUN:     FileCheck %s --check-prefixes=MSC --implicit-check-not=to_be_ --implicit-check-not=dllexport
+// RUN: %clang_cc1 -triple x86_64-mingw                 -emit-llvm -o - %s | \
+// RUN:     FileCheck %s --check-prefixes=GNU --implicit-check-not=to_be_ --implicit-check-not=dllexport
+// RUN: %clang_cc1 -triple x86_64-cygwin                -emit-llvm -o - %s | \
+// RUN:     FileCheck %s --check-prefixes=GNU --implicit-check-not=to_be_ --implicit-check-not=dllexport
+
+// Test that __declspec(dllexport) doesn't instantiate entities marked with
+// the exclude_from_explicit_instantiation attribute unless marked as dllexport explicitly.
+
+// MSC: ModuleID = {{.*}}exclude_from_dllexport.cpp
+// MSC: source_filename = {{.*}}exclude_from_dllexport.cpp
+// GNU: ModuleID = {{.*}}exclude_from_dllexport.cpp
+// GNU: source_filename = {{.*}}exclude_from_dllexport.cpp
+
+#define EXCLUDE_FROM_EXPLICIT_INSTANTIATION __attribute__((exclude_from_explicit_instantiation))
+
+template <class T>
+struct C {
+  // This will be instantiated explicitly as an exported function because it
+  // inherits dllexport from the class instantiation.
+  void to_be_exported() noexcept;
+
+  // This will be instantiated implicitly as an exported function because it is
+  // marked as dllexport explicitly.
+  EXCLUDE_FROM_EXPLICIT_INSTANTIATION __declspec(dllexport) void to_be_exported_explicitly() noexcept;
+
+  // This will be instantiated implicitly but won't be exported.
+  EXCLUDE_FROM_EXPLICIT_INSTANTIATION void not_to_be_exported() noexcept;
+
+  // This won't be instantiated.
+  EXCLUDE_FROM_EXPLICIT_INSTANTIATION void not_to_be_instantiated() noexcept;
+};
+
+template <class T> void C<T>::to_be_exported() noexcept {}
+template <class T> void C<T>::to_be_exported_explicitly() noexcept {}
+template <class T> void C<T>::not_to_be_exported() noexcept {}
+template <class T> void C<T>::not_to_be_instantiated() noexcept {}
+
+// Attach the attribute to class template declaration instead of instantiation declaration.
+template <class T>
+struct __declspec(dllexport) D {
+  // This will be exported if and only if no explicit instantiations are provided.
+  EXCLUDE_FROM_EXPLICIT_INSTANTIATION void to_be_exported_iff_no_explicit_instantiation() noexcept;
+};
+
+template <class T> void D<T>::to_be_exported_iff_no_explicit_instantiation() noexcept {}
+
+// Interaction with VTables.
+template <class T>
+struct E {
+  // This will be instanciated by the explicit template instantiation definition.
+  virtual void to_be_exported() noexcept;
+
+  // This will be instantiated by the VTable definition, regardless of
+  // `exclude_from_explicit_instantiation`.
+  // The dllexport attribute won't be inherited.
+  EXCLUDE_FROM_EXPLICIT_INSTANTIATION virtual void to_be_instantiated() noexcept;
+
+  // This too, but will be exported by the member attribute.
+  EXCLUDE_FROM_EXPLICIT_INSTANTIATION __declspec(dllexport) virtual void to_be_exported_explicitly() noexcept;
+};
+
+template <class T> void E<T>::to_be_exported() noexcept {}
+template <class T> void E<T>::to_be_instantiated() noexcept {}
+template <class T> void E<T>::to_be_exported_explicitly() noexcept {}
+
+// MSC: $"?to_be_exported@?$C@H@@QEAAXXZ" = comdat any
+// MSC: $"?to_be_exported@?$E@H@@UEAAXXZ" = comdat any
+// MSC: $"?to_be_exported@?$E@I@@UEAAXXZ" = comdat any
+// MSC: $"?to_be_exported_explicitly@?$C@H@@QEAAXXZ" = comdat any
+// MSC: $"?not_to_be_exported@?$C@H@@QEAAXXZ" = comdat any
+// MSC: $"?to_be_exported_iff_no_explicit_instantiation@?$D@H@@QEAAXXZ" = comdat any
+// MSC: $"?to_be_exported_iff_no_explicit_instantiation@?$D@I@@QEAAXXZ" = comdat any
+// MSC: $"?to_be_instantiated@?$E@H@@UEAAXXZ" = comdat any
+// MSC: $"?to_be_exported_explicitly@?$E@H@@UEAAXXZ" = comdat any
+// MSC: $"?to_be_instantiated@?$E@I@@UEAAXXZ" = comdat any
+// MSC: $"?to_be_exported_explicitly@?$E@I@@UEAAXXZ" = comdat any
+// GNU: $_ZN1CIiE14to_be_exportedEv = comdat any
+// GNU: $_ZN1EIiE14to_be_exportedEv = comdat any
+// GNU: $_ZN1EIjE14to_be_exportedEv = comdat any
+// GNU: $_ZN1CIiE25to_be_exported_explicitlyEv = comdat any
+// GNU: $_ZN1CIiE18not_to_be_exportedEv = comdat any
+// GNU: $_ZN1DIiE44to_be_exported_iff_no_explicit_instantiationEv = comdat any
+// GNU: $_ZN1DIjE44to_be_exported_iff_no_explicit_instantiationEv = comdat any
+// GNU: $_ZN1EIiE18to_be_instantiatedEv = comdat any
+// GNU: $_ZN1EIiE25to_be_exported_explicitlyEv = comdat any
+// GNU: $_ZN1EIjE18to_be_instantiatedEv = comdat any
+// GNU: $_ZN1EIjE25to_be_exported_explicitlyEv = comdat any
+
+// MSC: @0 = private unnamed_addr constant {{.*}}, comdat($"??_7?$E@H@@6B@")
+// MSC: @1 = private unnamed_addr constant {{.*}}, comdat($"??_7?$E@I@@6B@")
+// MSC: @"??_7?$E@H@@6B@" = dllexport unnamed_addr
+// MSC: @"??_7?$E@I@@6B@" = unnamed_addr
+// GNU:@_ZTV1EIiE = weak_odr dso_local dllexport unnamed_addr constant {{.*}}, comdat
+// GNU:@_ZTV1EIjE = weak_odr dso_local unnamed_addr constant {{.*}}, comdat
+
+// MSC: define weak_odr dso_local dllexport{{.*}} ptr @"??4?$C@H@@QEAAAEAU0@AEBU0@@Z"
+// MSC: define weak_odr dso_local dllexport{{.*}} void @"?to_be_exported@?$C@H@@QEAAXXZ"
+// GNU: define weak_odr dso_local dllexport{{.*}} ptr @_ZN1CIiEaSERKS0_
+// GNU: define weak_odr dso_local dllexport{{.*}} void @_ZN1CIiE14to_be_exportedEv
+template struct __declspec(dllexport) C<int>;
+
+// MSC: define weak_odr dso_local dllexport{{.*}} ptr @"??4?$D@H@@QEAAAEAU0@AEBU0@@Z"
+// GNU: define weak_odr dso_local dllexport{{.*}} ptr @_ZN1DIiEaSERKS0_
+template struct D<int>; // No dllexport here.
+// Don't provide explicit instantiation for D<unsigned>.
+
+
+// MSC: define weak_odr dso_local dllexport{{.*}} ptr @"??4?$E@H@@QEAAAEAU0@AEBU0@@Z"
+// MSC: define weak_odr dso_local dllexport{{.*}} ptr @"??0?$E@H@@QEAA@XZ"
+// MSC: define weak_odr dso_local dllexport{{.*}} ptr @"??0?$E@H@@QEAA@AEBU0@@Z"
+// MSC: define weak_odr dso_local dllexport{{.*}} void @"?to_be_exported@?$E@H@@UEAAXXZ"
+// GNU: define weak_odr dso_local dllexport{{.*}} ptr @_ZN1EIiEaSERKS0_
+// GNU: define weak_odr dso_local dllexport{{.*}} void @_ZN1EIiEC2Ev
+// GNU: define weak_odr dso_local dllexport{{.*}} void @_ZN1EIiEC1Ev
+// GNU: define weak_odr dso_local dllexport{{.*}} void @_ZN1EIiEC2ERKS0_
+// GNU: define weak_odr dso_local dllexport{{.*}} void @_ZN1EIiEC1ERKS0_
+// GNU: define weak_odr dso_local dllexport{{.*}} void @_ZN1EIiE14to_be_exportedEv
+template struct __declspec(dllexport) E<int>;
+
+// MSC: define weak_odr dso_local{{.*}} void @"?to_be_exported@?$E@I@@UEAAXXZ"
+// GNU: define weak_odr dso_local{{.*}} void @_ZN1EIjE14to_be_exportedEv
+template struct E<unsigned int>;
+
+// MSC: define weak_odr dso_local dllexport{{.*}} ptr @"??4?$D@I@@QEAAAEAU0@AEBU0@@Z"
+
+void use() {
+  C<int> c;
+
+  // MSC: call void @"?to_be_exported_explicitly@?$C@H@@QEAAXXZ"
+  // GNU: call void @_ZN1CIiE25to_be_exported_explicitlyEv
+  c.to_be_exported_explicitly(); // implicitly instantiated here
+
+  // MSC: call void @"?not_to_be_exported@?$C@H@@QEAAXXZ"
+  // GNU: call void @_ZN1CIiE18not_to_be_exportedEv
+  c.not_to_be_exported(); // implicitly instantiated here
+
+  D<int> di;
+
+  // MSC: call void @"?to_be_exported_iff_no_explicit_instantiation@?$D@H@@QEAAXXZ"
+  // GNU: call void @_ZN1DIiE44to_be_exported_iff_no_explicit_instantiationEv
+  di.to_be_exported_iff_no_explicit_instantiation(); // implicitly instantiated here
+
+  D<unsigned> dj;
+
+  // MSC: call void @"?to_be_exported_iff_no_explicit_instantiation@?$D@I@@QEAAXXZ"
+  // GNU: call void @_ZN1DIjE44to_be_exported_iff_no_explicit_instantiationEv
+  dj.to_be_exported_iff_no_explicit_instantiation(); // implicitly instantiated here
+}
+
+// MSC: define weak_odr dso_local dllexport{{.*}} void @"?to_be_exported_explicitly@?$C@H@@QEAAXXZ"
+// GNU: define weak_odr dso_local dllexport{{.*}} void @_ZN1CIiE25to_be_exported_explicitlyEv
+
+// MSC: define linkonce_odr dso_local void @"?not_to_be_exported@?$C@H@@QEAAXXZ"
+// GNU: define linkonce_odr dso_local void @_ZN1CIiE18not_to_be_exportedEv
+
+// MSC: define linkonce_odr dso_local void @"?to_be_exported_iff_no_explicit_instantiation@?$D@H@@QEAAXXZ"
+// MSC: define weak_odr dso_local dllexport void @"?to_be_exported_iff_no_explicit_instantiation@?$D@I@@QEAAXXZ"
+// GNU: define linkonce_odr dso_local void @_ZN1DIiE44to_be_exported_iff_no_explicit_instantiationEv
+// GNU: define weak_odr dso_local dllexport void @_ZN1DIjE44to_be_exported_iff_no_explicit_instantiationEv
+
+// MSC: define linkonce_odr dso_local void @"?to_be_instantiated@?$E@H@@UEAAXXZ"
+// MSC: define weak_odr dso_local dllexport void @"?to_be_exported_explicitly@?$E@H@@UEAAXXZ"
+// GNU: define linkonce_odr dso_local void @_ZN1EIiE18to_be_instantiatedEv
+// GNU: define weak_odr dso_local dllexport void @_ZN1EIiE25to_be_exported_explicitlyEv
+
+// MSC: define linkonce_odr dso_local void @"?to_be_instantiated@?$E@I@@UEAAXXZ"
+// MSC: define weak_odr dso_local dllexport void @"?to_be_exported_explicitly@?$E@I@@UEAAXXZ"
+// GNU: define linkonce_odr dso_local void @_ZN1EIjE18to_be_instantiatedEv
+// GNU: define weak_odr dso_local dllexport void @_ZN1EIjE25to_be_exported_explicitlyEv