Make our marking of virtual members functions in a class be

deterministic and work properly with templates. Once a class that
needs a vtable has been defined, we now do one if two things:

  - If the class has no key function, we place the class on a list of
    classes whose virtual functions will need to be "marked" at the
    end of the translation unit. The delay until the end of the
    translation unit is needed because we might see template
    specializations of these virtual functions.
  - If the class has a key function, we do nothing; when the key
    function is defined, the class will be placed on the
    aforementioned list.

At the end of the translation unit, we "mark" all of the virtual
functions of the classes on the list as used, possibly causing
template instantiation and other classes to be added to the
list. This gets LLVM's lib/Support/CommandLine.cpp compiling again.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@92821 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 36 insertions, 56 deletions

diff --git a/lib/Sema/Sema.h b/lib/Sema/Sema.h
index df6f18f95b..87ebea72f2 100644
--- a/lib/Sema/Sema.h
+++ b/lib/Sema/Sema.h
@@ -2172,11 +2172,11 @@ public:
   void MarkBaseAndMemberDestructorsReferenced(CXXDestructorDecl *Destructor);
 
   /// ClassesWithUnmarkedVirtualMembers - Contains record decls whose virtual
-  /// members might need to be marked as referenced. This is either done when
-  /// the key function definition is emitted (this is handled by by 
-  /// MaybeMarkVirtualMembersReferenced), or at the end of the translation unit
-  /// (done by ProcessPendingClassesWithUnmarkedVirtualMembers).
-  std::map<CXXRecordDecl *, SourceLocation> ClassesWithUnmarkedVirtualMembers;
+  /// members need to be marked as referenced at the end of the translation
+  /// unit. It will contain polymorphic classes that do not have a key
+  /// function or have a key function that has been defined.
+  llvm::SmallVector<std::pair<CXXRecordDecl *, SourceLocation>, 4>
+    ClassesWithUnmarkedVirtualMembers;
 
   /// MaybeMarkVirtualMembersReferenced - If the passed in method is the
   /// key function of the record decl, will mark virtual member functions as 
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 0fc61e3b58..383893cc2f 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -5098,6 +5098,16 @@ void Sema::ActOnTagFinishDefinition(Scope *S, DeclPtrTy TagD,
   // Exit this scope of this tag's definition.
   PopDeclContext();
 
+  // If this is a polymorphic C++ class without a key function, we'll
+  // have to mark all of the virtual members to allow emission of a vtable
+  // in this translation unit.
+  if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Tag)) {
+    if (!Record->isDependentContext() && Record->isDynamicClass() &&
+        !Context.getKeyFunction(Record))
+      ClassesWithUnmarkedVirtualMembers.push_back(std::make_pair(Record, 
+                                                                 RBraceLoc));
+  }
+
   // Notify the consumer that we've defined a tag.
   Consumer.HandleTagDeclDefinition(Tag);
 }
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index ecf95d7eb6..623bf8ae7e 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -2054,7 +2054,7 @@ void Sema::CheckCompletedCXXClass(CXXRecordDecl *Record) {
 
   if (!Record->isDependentType())
     AddImplicitlyDeclaredMembersToClass(Record);
-
+  
   if (Record->isInvalidDecl())
     return;
 
@@ -5693,67 +5693,30 @@ void Sema::MaybeMarkVirtualMembersReferenced(SourceLocation Loc,
   if (!RD->isDynamicClass())
     return;
 
-  if (!MD->isOutOfLine()) {
-    // The only inline functions we care about are constructors. We also defer
-    // marking the virtual members as referenced until we've reached the end
-    // of the translation unit. We do this because we need to know the key
-    // function of the class in order to determine the key function.
-    if (isa<CXXConstructorDecl>(MD))
-      ClassesWithUnmarkedVirtualMembers.insert(std::make_pair(RD, Loc));
+  // Only out-of-line definitions matter.
+  if (!MD->isOutOfLine())
+    return;
+  
+  const CXXMethodDecl *KeyFunction = Context.getKeyFunction(RD);
+  if (!KeyFunction || KeyFunction->getCanonicalDecl() != MD->getCanonicalDecl())
     return;
-  }
-
-  switch (RD->getTemplateSpecializationKind()) {
-  case TSK_Undeclared:
-  case TSK_ExplicitSpecialization: {
-    const CXXMethodDecl *KeyFunction = Context.getKeyFunction(RD);
-
-    if (!KeyFunction) {
-      // This record does not have a key function, so we assume that the vtable
-      // will be emitted when it's used by the constructor.
-      if (!isa<CXXConstructorDecl>(MD))
-        return;
-    } else if (KeyFunction->getCanonicalDecl() != MD->getCanonicalDecl()) {
-      // We don't have the right key function.
-      return;
-    }
-    break;
-  }
-
-  case TSK_ImplicitInstantiation:
-  case TSK_ExplicitInstantiationDeclaration:
-  case TSK_ExplicitInstantiationDefinition:
-    // Always mark the virtual members of an instantiated template.
-    break;
-  }
 
-  // Mark the members as referenced.
-  MarkVirtualMembersReferenced(Loc, RD);
-  ClassesWithUnmarkedVirtualMembers.erase(RD);
+  // We will need to mark all of the virtual members as referenced to build the
+  // vtable.
+  ClassesWithUnmarkedVirtualMembers.push_back(std::make_pair(RD, Loc));
 }
 
 bool Sema::ProcessPendingClassesWithUnmarkedVirtualMembers() {
   if (ClassesWithUnmarkedVirtualMembers.empty())
     return false;
   
-  for (std::map<CXXRecordDecl *, SourceLocation>::iterator i = 
-       ClassesWithUnmarkedVirtualMembers.begin(), 
-       e = ClassesWithUnmarkedVirtualMembers.end(); i != e; ++i) {
-    CXXRecordDecl *RD = i->first;
-    
-    const CXXMethodDecl *KeyFunction = Context.getKeyFunction(RD);
-    if (KeyFunction) {
-      // We know that the class has a key function. If the key function was
-      // declared in this translation unit, then it the class decl would not 
-      // have been in the ClassesWithUnmarkedVirtualMembers map.
-      continue;
-    }
-    
-    SourceLocation Loc = i->second;
+  while (!ClassesWithUnmarkedVirtualMembers.empty()) {
+    CXXRecordDecl *RD = ClassesWithUnmarkedVirtualMembers.back().first;
+    SourceLocation Loc = ClassesWithUnmarkedVirtualMembers.back().second;
+    ClassesWithUnmarkedVirtualMembers.pop_back();
     MarkVirtualMembersReferenced(Loc, RD);
   }
   
-  ClassesWithUnmarkedVirtualMembers.clear();
   return true;
 }
 
diff --git a/lib/Sema/SemaTemplateInstantiate.cpp b/lib/Sema/SemaTemplateInstantiate.cpp
index d974f89bc6..2db0deb509 100644
--- a/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/lib/Sema/SemaTemplateInstantiate.cpp
@@ -1060,6 +1060,13 @@ Sema::InstantiateClass(SourceLocation PointOfInstantiation,
   // Exit the scope of this instantiation.
   CurContext = PreviousContext;
 
+  // If this is a polymorphic C++ class without a key function, we'll
+  // have to mark all of the virtual members to allow emission of a vtable
+  // in this translation unit.
+  if (Instantiation->isDynamicClass() && !Context.getKeyFunction(Instantiation))
+      ClassesWithUnmarkedVirtualMembers.push_back(std::make_pair(Instantiation,
+                                                       PointOfInstantiation));
+
   if (!Invalid)
     Consumer.HandleTagDeclDefinition(Instantiation);