Reapply r99775 with a fix for a silly bug - we were setting the vtable pointer for all bases, even those without a vtable pointer :)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@99777 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/CGClass.cpp

@@ -690,7 +690,7 @@ CodeGenFunction::SynthesizeCXXCopyConstructor(const FunctionArgList &Args) {
     }
   }
 
-  InitializeVtablePtrs(ClassDecl);
+  InitializeVTablePointers(ClassDecl);
 }
 
 /// SynthesizeCXXCopyAssignment - Implicitly define copy assignment operator.
@@ -1010,7 +1010,7 @@ void CodeGenFunction::EmitCtorPrologue(const CXXConstructorDecl *CD,
       MemberInitializers.push_back(Member);
   }
 
-  InitializeVtablePtrs(ClassDecl);
+  InitializeVTablePointers(ClassDecl);
 
   for (unsigned I = 0, E = MemberInitializers.size(); I != E; ++I) {
     assert(LiveTemporaries.empty() &&
@@ -1060,7 +1060,7 @@ void CodeGenFunction::EmitDestructorBody(FunctionArgList &Args) {
   // Otherwise, we're in the base variant, so we need to ensure the
   // vtable ptrs are right before emitting the body.
   } else {
-    InitializeVtablePtrs(Dtor->getParent());
+    InitializeVTablePointers(Dtor->getParent());
   }
 
   // Emit the body of the statement.
@@ -1561,7 +1561,6 @@ CodeGenFunction::InitializeVTablePointer(BaseSubobject Base,
                                          bool BaseIsMorallyVirtual,
                                          llvm::Constant *VTable,
                                          const CXXRecordDecl *VTableClass) {
-  
   // Compute the address point.
   const CodeGenVTables::AddrSubMap_t& AddressPoints =
     CGM.getVTables().getAddressPoints(VTableClass);
@@ -1584,59 +1583,71 @@ CodeGenFunction::InitializeVTablePointer(BaseSubobject Base,
   Builder.CreateStore(VTableAddressPoint, VTableField);
 }
 
-void CodeGenFunction::InitializeVtablePtrs(const CXXRecordDecl *RD) {
+void
+CodeGenFunction::InitializeVTablePointers(BaseSubobject Base, 
+                                          bool BaseIsMorallyVirtual,
+                                          bool BaseIsNonVirtualPrimaryBase,
+                                          llvm::Constant *VTable,
+                                          const CXXRecordDecl *VTableClass,
+                                          VisitedVirtualBasesSetTy& VBases) {
+  // If this base is a non-virtual primary base the address point has already
+  // been set.
+  if (!BaseIsNonVirtualPrimaryBase) {
+    // Initialize the vtable pointer for this base.
+    InitializeVTablePointer(Base, BaseIsMorallyVirtual, VTable, VTableClass);
+  }
+  
+  const CXXRecordDecl *RD = Base.getBase();
+
+  // Traverse bases.
+  for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 
+       E = RD->bases_end(); I != E; ++I) {
+    CXXRecordDecl *BaseDecl
+      = cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
+
+    // Ignore classes without a vtable.
+    if (!BaseDecl->isDynamicClass())
+      continue;
+
+    uint64_t BaseOffset;
+
+    if (I->isVirtual()) {
+      // Check if we've visited this virtual base before.
+      if (!VBases.insert(BaseDecl))
+        continue;
+
+      const ASTRecordLayout &Layout = 
+        getContext().getASTRecordLayout(VTableClass);
+
+      BaseIsMorallyVirtual = true;
+      BaseIsNonVirtualPrimaryBase = false;
+      
+      BaseOffset = Layout.getVBaseClassOffset(BaseDecl);
+    } else {
+      const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
+
+      BaseOffset = Base.getBaseOffset() + Layout.getBaseClassOffset(BaseDecl);
+      BaseIsNonVirtualPrimaryBase = Layout.getPrimaryBase() == BaseDecl;
+    }
+    
+    InitializeVTablePointers(BaseSubobject(BaseDecl, BaseOffset), 
+                             BaseIsMorallyVirtual, BaseIsNonVirtualPrimaryBase, 
+                             VTable, VTableClass, VBases);
+  }
+}
+
+void CodeGenFunction::InitializeVTablePointers(const CXXRecordDecl *RD) {
+  // Ignore classes without a vtable.
   if (!RD->isDynamicClass())
     return;
 
   // Get the VTable.
   llvm::Constant *VTable = CGM.getVTables().GetAddrOfVTable(RD);
-  
-  // Store address points for the current class and its non-virtual bases.
-  InitializeVtablePtrs(BaseSubobject(RD, 0), VTable, RD);
-  
-  if (!RD->getNumVBases())
-    return;
 
-  const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
-
-  // Store address points for virtual basess.
-  for (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(), 
-       E = RD->vbases_end(); I != E; ++I) {
-    CXXRecordDecl *BaseDecl
-      = cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
-    
-    uint64_t BaseOffset = Layout.getVBaseClassOffset(BaseDecl);
-    InitializeVtablePtrs(BaseSubobject(BaseDecl, BaseOffset), VTable, RD);
-  }
-}
-
-void CodeGenFunction::InitializeVtablePtrs(BaseSubobject Base, 
-                                           llvm::Constant *VTable,
-                                           const CXXRecordDecl *VTableClass) {
-  const CXXRecordDecl *RD = Base.getBase();
-  
-  // Ignore classes without a vtable pointer.
-  if (!RD->isDynamicClass())
-    return;
-  
-  const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
-
-  // Store address points for non-virtual bases.
-  for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 
-       E = RD->bases_end(); I != E; ++I) {
-    if (I->isVirtual())
-      continue;
-    
-    CXXRecordDecl *BaseDecl
-      = cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
-    uint64_t BaseOffset = Base.getBaseOffset() + 
-      Layout.getBaseClassOffset(BaseDecl);
-    
-    InitializeVtablePtrs(BaseSubobject(BaseDecl, BaseOffset), 
-                         VTable, VTableClass);
-  }
-
-  // FIXME: BaseIsMorallyVirtual is not correct here.
-  InitializeVTablePointer(Base, /*BaseIsMorallyVirtual=*/false, VTable, 
-                          VTableClass);
+  // Initialize the vtable pointers for this class and all of its bases.
+  VisitedVirtualBasesSetTy VBases;
+  InitializeVTablePointers(BaseSubobject(RD, 0),
+                           /*BaseIsMorallyVirtual=*/false, 
+                           /*BaseIsNonVirtualPrimaryBase=*/false, 
+                           VTable, RD, VBases);
 }

lib/CodeGen/CodeGenFunction.h

@@ -519,11 +519,13 @@ public:
                                const CXXRecordDecl *VTableClass);
 
   typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy;
+  void InitializeVTablePointers(BaseSubobject Base, bool BaseIsMorallyVirtual,
+                                bool BaseIsNonVirtualPrimaryBase,
+                                llvm::Constant *VTable,
+                                const CXXRecordDecl *VTableClass,
+                                VisitedVirtualBasesSetTy& VBases);
 
-  void InitializeVtablePtrs(BaseSubobject Base, llvm::Constant *VTable,
-                            const CXXRecordDecl *VTableClass);
-
-  void InitializeVtablePtrs(const CXXRecordDecl *ClassDecl);
+  void InitializeVTablePointers(const CXXRecordDecl *ClassDecl);
 
 
   void SynthesizeCXXCopyConstructor(const FunctionArgList &Args);