Re-land "[MS] Don't expect vftables to be provided for extern template instantiations"
Reverts r273305 and re-instates r273296.
We needed to fix a bug in Sema::MarkVTableUsed to ensure that operator
delete lookup occurs when the vtable is referenced. We already had a
special case to look up operator delete when dllimport was used, but I
think should really mark virtual destructors referenced any time the
vtable is used.
llvm-svn: 274147
diff --git a/clang/lib/AST/VTableBuilder.cpp b/clang/lib/AST/VTableBuilder.cpp
index e43acc4..640fbf4 100644
--- a/clang/lib/AST/VTableBuilder.cpp
+++ b/clang/lib/AST/VTableBuilder.cpp
@@ -2545,14 +2545,13 @@
MostDerivedClassLayout(Context.getASTRecordLayout(MostDerivedClass)),
WhichVFPtr(*Which),
Overriders(MostDerivedClass, CharUnits(), MostDerivedClass) {
- // Only include the RTTI component if we know that we will provide a
- // definition of the vftable. We always provide the definition of
- // dllimported classes.
+ // Provide the RTTI component if RTTIData is enabled. If the vftable would
+ // be available externally, we should not provide the RTTI componenent. It
+ // is currently impossible to get available externally vftables with either
+ // dllimport or extern template instantiations, but eventually we may add a
+ // flag to support additional devirtualization that needs this.
if (Context.getLangOpts().RTTIData)
- if (MostDerivedClass->hasAttr<DLLImportAttr>() ||
- MostDerivedClass->getTemplateSpecializationKind() !=
- TSK_ExplicitInstantiationDeclaration)
- HasRTTIComponent = true;
+ HasRTTIComponent = true;
LayoutVFTable();
diff --git a/clang/lib/CodeGen/CGVTables.cpp b/clang/lib/CodeGen/CGVTables.cpp
index 83974e0..9570550 100644
--- a/clang/lib/CodeGen/CGVTables.cpp
+++ b/clang/lib/CodeGen/CGVTables.cpp
@@ -794,6 +794,10 @@
return DiscardableODRLinkage;
case TSK_ExplicitInstantiationDeclaration:
+ // Explicit instantiations in MSVC do not provide vtables, so we must emit
+ // our own.
+ if (getTarget().getCXXABI().isMicrosoft())
+ return DiscardableODRLinkage;
return shouldEmitAvailableExternallyVTable(*this, RD)
? llvm::GlobalVariable::AvailableExternallyLinkage
: llvm::GlobalVariable::ExternalLinkage;
@@ -839,9 +843,9 @@
bool CodeGenVTables::isVTableExternal(const CXXRecordDecl *RD) {
assert(RD->isDynamicClass() && "Non-dynamic classes have no VTable.");
- // We always synthesize vtables on the import side regardless of whether or
- // not it is an explicit instantiation declaration.
- if (CGM.getTarget().getCXXABI().isMicrosoft() && RD->hasAttr<DLLImportAttr>())
+ // We always synthesize vtables if they are needed in the MS ABI. MSVC doesn't
+ // emit them even if there is an explicit template instantiation.
+ if (CGM.getTarget().getCXXABI().isMicrosoft())
return false;
// If we have an explicit instantiation declaration (and not a
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index d8bb3d0..948ad5f 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -13425,20 +13425,18 @@
// checks (i.e. operator delete() lookup) when the vtable is marked used, as
// the deleting destructor is emitted with the vtable, not with the
// destructor definition as in the Itanium ABI.
- // If it has a definition, we do the check at that point instead.
if (Context.getTargetInfo().getCXXABI().isMicrosoft()) {
- if (Class->hasUserDeclaredDestructor() &&
- !Class->getDestructor()->isDefined() &&
- !Class->getDestructor()->isDeleted()) {
- CXXDestructorDecl *DD = Class->getDestructor();
- ContextRAII SavedContext(*this, DD);
- CheckDestructor(DD);
- } else if (Class->hasAttr<DLLImportAttr>()) {
- // We always synthesize vtables on the import side. To make sure
- // CheckDestructor gets called, mark the destructor referenced.
- assert(Class->getDestructor() &&
- "The destructor has always been declared on a dllimport class");
- MarkFunctionReferenced(Loc, Class->getDestructor());
+ CXXDestructorDecl *DD = Class->getDestructor();
+ if (DD && DD->isVirtual() && !DD->isDeleted()) {
+ if (Class->hasUserDeclaredDestructor() && !DD->isDefined()) {
+ // If this is an out-of-line declaration, marking it referenced will
+ // not do anything. Manually call CheckDestructor to look up operator
+ // delete().
+ ContextRAII SavedContext(*this, DD);
+ CheckDestructor(DD);
+ } else {
+ MarkFunctionReferenced(Loc, Class->getDestructor());
+ }
}
}
}