From: Anders Carlsson Date: Tue, 16 Feb 2010 16:02:57 +0000 (+0000) Subject: Fix a bug where we would not emit secondary vtables for bases of a primary base. X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=c7b631682f66b5d6144968cf75d3af895b611fc6;p=clang Fix a bug where we would not emit secondary vtables for bases of a primary base. git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@96351 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/lib/CodeGen/CGVtable.cpp b/lib/CodeGen/CGVtable.cpp index 970bbd777f..6199c055b7 100644 --- a/lib/CodeGen/CGVtable.cpp +++ b/lib/CodeGen/CGVtable.cpp @@ -822,6 +822,10 @@ private: /// LayoutVtable - Layout a vtable and all its secondary vtables. void LayoutVtable(BaseSubobject Base); + /// LayoutSecondaryVtables - Layout the secondary vtables for the given base + /// subobject. + void LayoutSecondaryVtables(BaseSubobject Base); + public: VtableBuilder(CGVtableInfo &VtableInfo, const CXXRecordDecl *MostDerivedClass) : VtableInfo(VtableInfo), MostDerivedClass(MostDerivedClass), @@ -1070,36 +1074,49 @@ void VtableBuilder::LayoutVtable(BaseSubobject Base) { AddressPoints.insert(std::make_pair(PrimaryBase, AddressPoint)); } + // Layout secondary vtables. + LayoutSecondaryVtables(Base); + + // FIXME: Emit vtables for virtual bases here. +} + +void VtableBuilder::LayoutSecondaryVtables(BaseSubobject Base) { + // Itanium C++ ABI 2.5.2: + // Following the primary virtual table of a derived class are secondary + // virtual tables for each of its proper base classes, except any primary + // base(s) with which it shares its primary virtual table. + + const CXXRecordDecl *RD = Base.getBase(); const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); - - // Layout secondary vtables. + for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), E = RD->bases_end(); I != E; ++I) { + // Ignore virtual bases, we'll emit them later. + if (I->isVirtual()) + continue; + const CXXRecordDecl *BaseDecl = cast(I->getType()->getAs()->getDecl()); // Ignore bases that don't have a vtable. if (!BaseDecl->isDynamicClass()) continue; - - // Ignore the primary base. - if (BaseDecl == PrimaryBase) - continue; - // Ignore virtual bases, we'll emit them later. - if (I->isVirtual()) - continue; - // Get the base offset of this base. uint64_t BaseOffset = Base.getBaseOffset() + Layout.getBaseClassOffset(BaseDecl); + + // Don't emit a secondary vtable for a primary base. We might however want + // to emit secondary vtables for other bases of this base. + if (BaseDecl == PrimaryBase) { + LayoutSecondaryVtables(BaseSubobject(BaseDecl, BaseOffset)); + continue; + } // Layout this secondary vtable. LayoutVtable(BaseSubobject(BaseDecl, BaseOffset)); } - - // FIXME: Emit vtables for virtual bases here. } /// dumpLayout - Dump the vtable layout. diff --git a/test/CodeGenCXX/vtable-layout.cpp b/test/CodeGenCXX/vtable-layout.cpp index 8fbe486faa..b714511a38 100644 --- a/test/CodeGenCXX/vtable-layout.cpp +++ b/test/CodeGenCXX/vtable-layout.cpp @@ -365,3 +365,33 @@ struct B : virtual A1, virtual A2 { void B::f() { } } + +namespace Test10 { + +// Test for a bug where we would not emit secondary vtables for bases +// of a primary base. +struct A1 { virtual void a1(); }; +struct A2 { virtual void a2(); }; + +// CHECK: Vtable for 'Test10::C' (7 entries). +// CHECK-NEXT: 0 | offset_to_top (0) +// CHECK-NEXT: 1 | Test10::C RTTI +// CHECK-NEXT: -- (Test10::A1, 0) vtable address -- +// CHECK-NEXT: -- (Test10::B, 0) vtable address -- +// CHECK-NEXT: -- (Test10::C, 0) vtable address -- +// CHECK-NEXT: 2 | void Test10::A1::a1() +// CHECK-NEXT: 3 | void Test10::C::f() +// CHECK-NEXT: 4 | offset_to_top (-8) +// CHECK-NEXT: 5 | Test10::C RTTI +// CHECK-NEXT: -- (Test10::A2, 8) vtable address -- +// CHECK-NEXT: 6 | void Test10::A2::a2() +struct B : A1, A2 { + int b; +}; + +struct C : B { + virtual void f(); +}; +void C::f() { } + +}