Author: majnemer Date: Wed Feb 10 11:40:47 2016 New Revision: 260388 URL: http://llvm.org/viewvc/llvm-project?rev=260388&view=rev Log: [MS ABI] Never reference dllimport'd vtables
Referencing a dllimported vtable is impossible in a constexpr constructor. It would be friendlier to C++ programmers if we synthesized a copy of the vftable which referenced imported virtual functions. This would let us initialize the object in a way which preserves both the intent to import functionality from another DLL while also making constexpr work. Differential Revision: http://reviews.llvm.org/D17061 Modified: cfe/trunk/lib/AST/MicrosoftMangle.cpp cfe/trunk/lib/AST/VTableBuilder.cpp cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp cfe/trunk/test/CodeGenCXX/dllimport-rtti.cpp cfe/trunk/test/CodeGenCXX/dllimport.cpp cfe/trunk/test/CodeGenCXX/microsoft-abi-vftables.cpp Modified: cfe/trunk/lib/AST/MicrosoftMangle.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/MicrosoftMangle.cpp?rev=260388&r1=260387&r2=260388&view=diff ============================================================================== --- cfe/trunk/lib/AST/MicrosoftMangle.cpp (original) +++ cfe/trunk/lib/AST/MicrosoftMangle.cpp Wed Feb 10 11:40:47 2016 @@ -2599,7 +2599,10 @@ void MicrosoftMangleContextImpl::mangleC // NOTE: <cvr-qualifiers> here is always 'B' (const). <storage-class> // is always '6' for vftables. MicrosoftCXXNameMangler Mangler(*this, Out); - Mangler.getStream() << "\01??_7"; + if (Derived->hasAttr<DLLImportAttr>()) + Mangler.getStream() << "\01??_S"; + else + Mangler.getStream() << "\01??_7"; Mangler.mangleName(Derived); Mangler.getStream() << "6B"; // '6' for vftable, 'B' for const. for (const CXXRecordDecl *RD : BasePath) Modified: cfe/trunk/lib/AST/VTableBuilder.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/VTableBuilder.cpp?rev=260388&r1=260387&r2=260388&view=diff ============================================================================== --- cfe/trunk/lib/AST/VTableBuilder.cpp (original) +++ cfe/trunk/lib/AST/VTableBuilder.cpp Wed Feb 10 11:40:47 2016 @@ -2548,7 +2548,6 @@ public: // Only include the RTTI component if we know that we will provide a // definition of the vftable. HasRTTIComponent = Context.getLangOpts().RTTIData && - !MostDerivedClass->hasAttr<DLLImportAttr>() && MostDerivedClass->getTemplateSpecializationKind() != TSK_ExplicitInstantiationDeclaration; Modified: cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp?rev=260388&r1=260387&r2=260388&view=diff ============================================================================== --- cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp (original) +++ cfe/trunk/lib/CodeGen/MicrosoftCXXABI.cpp Wed Feb 10 11:40:47 2016 @@ -1673,7 +1673,16 @@ llvm::GlobalVariable *MicrosoftCXXABI::g SmallString<256> VFTableName; mangleVFTableName(getMangleContext(), RD, VFPtr, VFTableName); - llvm::GlobalValue::LinkageTypes VFTableLinkage = CGM.getVTableLinkage(RD); + // Classes marked __declspec(dllimport) need vftables generated on the + // import-side in order to support features like constexpr. No other + // translation unit relies on the emission of the local vftable, translation + // units are expected to generate them as needed. + // + // Because of this unique behavior, we maintain this logic here instead of + // getVTableLinkage. + llvm::GlobalValue::LinkageTypes VFTableLinkage = + RD->hasAttr<DLLImportAttr>() ? llvm::GlobalValue::LinkOnceODRLinkage + : CGM.getVTableLinkage(RD); bool VFTableComesFromAnotherTU = llvm::GlobalValue::isAvailableExternallyLinkage(VFTableLinkage) || llvm::GlobalValue::isExternalLinkage(VFTableLinkage); @@ -1746,9 +1755,7 @@ llvm::GlobalVariable *MicrosoftCXXABI::g if (C) VTable->setComdat(C); - if (RD->hasAttr<DLLImportAttr>()) - VFTable->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass); - else if (RD->hasAttr<DLLExportAttr>()) + if (RD->hasAttr<DLLExportAttr>()) VFTable->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass); VFTablesMap[ID] = VFTable; Modified: cfe/trunk/test/CodeGenCXX/dllimport-rtti.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/dllimport-rtti.cpp?rev=260388&r1=260387&r2=260388&view=diff ============================================================================== --- cfe/trunk/test/CodeGenCXX/dllimport-rtti.cpp (original) +++ cfe/trunk/test/CodeGenCXX/dllimport-rtti.cpp Wed Feb 10 11:40:47 2016 @@ -4,7 +4,8 @@ struct __declspec(dllimport) S { virtual void f() {} } s; -// MSVC-DAG: @"\01??_7S@@6B@" = available_externally dllimport +// MSVC: [[VF_S:.*]] = private unnamed_addr constant [2 x i8*] +// MSVC-DAG: @"\01??_SS@@6B@" = unnamed_addr alias i8*, getelementptr inbounds ([2 x i8*], [2 x i8*]* [[VF_S]], i32 0, i32 1) // MSVC-DAG: @"\01??_R0?AUS@@@8" = linkonce_odr // MSVC-DAG: @"\01??_R1A@?0A@EA@S@@8" = linkonce_odr // MSVC-DAG: @"\01??_R2S@@8" = linkonce_odr Modified: cfe/trunk/test/CodeGenCXX/dllimport.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/dllimport.cpp?rev=260388&r1=260387&r2=260388&view=diff ============================================================================== --- cfe/trunk/test/CodeGenCXX/dllimport.cpp (original) +++ cfe/trunk/test/CodeGenCXX/dllimport.cpp Wed Feb 10 11:40:47 2016 @@ -614,7 +614,7 @@ USEMEMFUNC(V, foo) struct __declspec(dllimport) W { virtual void foo() {} }; USECLASS(W) // vftable: -// MO1-DAG: @"\01??_7W@@6B@" = available_externally dllimport unnamed_addr constant [1 x i8*] [i8* bitcast (void (%struct.W*)* @"\01?foo@W@@UAEXXZ" to i8*)] +// MO1-DAG: @"\01??_SW@@6B@" = linkonce_odr unnamed_addr constant [1 x i8*] [i8* bitcast (void (%struct.W*)* @"\01?foo@W@@UAEXXZ" to i8*)] // GO1-DAG: @_ZTV1W = available_externally dllimport unnamed_addr constant [3 x i8*] [i8* null, i8* null, i8* bitcast (void (%struct.W*)* @_ZN1W3fooEv to i8*)] struct __declspec(dllimport) KeyFuncClass { Modified: cfe/trunk/test/CodeGenCXX/microsoft-abi-vftables.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/microsoft-abi-vftables.cpp?rev=260388&r1=260387&r2=260388&view=diff ============================================================================== --- cfe/trunk/test/CodeGenCXX/microsoft-abi-vftables.cpp (original) +++ cfe/trunk/test/CodeGenCXX/microsoft-abi-vftables.cpp Wed Feb 10 11:40:47 2016 @@ -4,8 +4,6 @@ // RTTI-DAG: $"\01??_7S@@6B@" = comdat largest // RTTI-DAG: $"\01??_7V@@6B@" = comdat largest -// RTTI-NOT: @"\01??_R4U@@6B@" - struct S { virtual ~S(); } s; @@ -19,9 +17,10 @@ struct __declspec(dllimport) U { virtual ~U(); } u; -// RTTI-DAG: @"\01??_7U@@6B@" = available_externally dllimport unnamed_addr constant [1 x i8*] [i8* bitcast ({{.*}} @"\01??_GU@@UAEPAXI@Z" to i8*)] +// RTTI-DAG: [[VTABLE_U:@.*]] = private unnamed_addr constant [2 x i8*] [i8* bitcast ({{.*}} @"\01??_R4U@@6B@" to i8*), i8* bitcast ({{.*}} @"\01??_GU@@UAEPAXI@Z" to i8*)] +// RTTI-DAG: @"\01??_SU@@6B@" = unnamed_addr alias i8*, getelementptr inbounds ([2 x i8*], [2 x i8*]* [[VTABLE_U]], i32 0, i32 1) -// NO-RTTI-DAG: @"\01??_7U@@6B@" = available_externally dllimport unnamed_addr constant [1 x i8*] [i8* bitcast ({{.*}} @"\01??_GU@@UAEPAXI@Z" to i8*)] +// NO-RTTI-DAG: @"\01??_SU@@6B@" = linkonce_odr unnamed_addr constant [1 x i8*] [i8* bitcast ({{.*}} @"\01??_GU@@UAEPAXI@Z" to i8*)] struct __declspec(dllexport) V { virtual ~V(); _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits