From 810def84aca2e23a9e028a422820fed0c1b97500 Mon Sep 17 00:00:00 2001 From: David Majnemer Date: Fri, 13 Mar 2015 22:36:55 +0000 Subject: [PATCH] MS ABI: Generate default constructor closures The MS ABI utilizes a compiler generated function called the "vector constructor iterator" to construct arrays of objects with non-trivial constructors/destructors. For this to work, the constructor must follow a specific calling convention. A thunk must be created if the default constructor has default arguments, is variadic or is otherwise incompatible. This thunk is called the default constructor closure. N.B. Default constructor closures are only generated if the default constructor is exported because clang itself does not utilize vector constructor iterators. Failing to export the default constructor closure will result in link/load failure if a translation unit compiled with MSVC is on the import side. Differential Revision: http://reviews.llvm.org/D8331 git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@232229 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/AST/MicrosoftMangle.cpp | 3 +- lib/CodeGen/CGCall.cpp | 8 +++- lib/CodeGen/CodeGenTypes.h | 3 +- lib/CodeGen/MicrosoftCXXABI.cpp | 66 ++++++++++++++++++++++----------- lib/Sema/SemaDecl.cpp | 28 +++++++++++++- test/CodeGenCXX/dllexport.cpp | 22 +++++++++++ 6 files changed, 103 insertions(+), 27 deletions(-) diff --git a/lib/AST/MicrosoftMangle.cpp b/lib/AST/MicrosoftMangle.cpp index f56da26a09..6a0ebda7b3 100644 --- a/lib/AST/MicrosoftMangle.cpp +++ b/lib/AST/MicrosoftMangle.cpp @@ -1640,10 +1640,11 @@ void MicrosoftCXXNameMangler::mangleFunctionType(const FunctionType *T, ->getPointeeType(), /*SpelledAsLValue=*/true), Range); + Out << '@'; } else { llvm_unreachable("unexpected constructor closure!"); } - Out << "@Z"; + Out << 'Z'; return; } Out << '@'; diff --git a/lib/CodeGen/CGCall.cpp b/lib/CodeGen/CGCall.cpp index 6784964211..3cb72bd151 100644 --- a/lib/CodeGen/CGCall.cpp +++ b/lib/CodeGen/CGCall.cpp @@ -347,12 +347,16 @@ CodeGenTypes::arrangeMSMemberPointerThunk(const CXXMethodDecl *MD) { } const CGFunctionInfo & -CodeGenTypes::arrangeMSCopyCtorClosure(const CXXConstructorDecl *CD) { +CodeGenTypes::arrangeMSCtorClosure(const CXXConstructorDecl *CD, + CXXCtorType CT) { + assert(CT == Ctor_CopyingClosure || CT == Ctor_DefaultClosure); + CanQual FTP = GetFormalType(CD); SmallVector ArgTys; const CXXRecordDecl *RD = CD->getParent(); ArgTys.push_back(GetThisType(Context, RD)); - ArgTys.push_back(*FTP->param_type_begin()); + if (CT == Ctor_CopyingClosure) + ArgTys.push_back(*FTP->param_type_begin()); if (RD->getNumVBases() > 0) ArgTys.push_back(Context.IntTy); CallingConv CC = Context.getDefaultCallingConvention( diff --git a/lib/CodeGen/CodeGenTypes.h b/lib/CodeGen/CodeGenTypes.h index f9cd3837fe..26d37f3c24 100644 --- a/lib/CodeGen/CodeGenTypes.h +++ b/lib/CodeGen/CodeGenTypes.h @@ -264,7 +264,8 @@ public: const FunctionProtoType *type, RequiredArgs required); const CGFunctionInfo &arrangeMSMemberPointerThunk(const CXXMethodDecl *MD); - const CGFunctionInfo &arrangeMSCopyCtorClosure(const CXXConstructorDecl *CD); + const CGFunctionInfo &arrangeMSCtorClosure(const CXXConstructorDecl *CD, + CXXCtorType CT); const CGFunctionInfo &arrangeFreeFunctionType(CanQual Ty); const CGFunctionInfo &arrangeFreeFunctionType(CanQual Ty); diff --git a/lib/CodeGen/MicrosoftCXXABI.cpp b/lib/CodeGen/MicrosoftCXXABI.cpp index 6b53359f28..96fcb2f8db 100644 --- a/lib/CodeGen/MicrosoftCXXABI.cpp +++ b/lib/CodeGen/MicrosoftCXXABI.cpp @@ -635,7 +635,8 @@ public: return Fn; } - llvm::Function *getAddrOfCXXCopyCtorClosure(const CXXConstructorDecl *CD); + llvm::Function *getAddrOfCXXCtorClosure(const CXXConstructorDecl *CD, + CXXCtorType CT); llvm::Constant *getCatchableType(QualType T, uint32_t NVOffset = 0, @@ -1060,9 +1061,29 @@ void MicrosoftCXXABI::initializeHiddenVirtualInheritanceMembers( } } +static bool hasDefaultCXXMethodCC(ASTContext &Context, + const CXXMethodDecl *MD) { + CallingConv ExpectedCallingConv = Context.getDefaultCallingConvention( + /*IsVariadic=*/false, /*IsCXXMethod=*/true); + CallingConv ActualCallingConv = + MD->getType()->getAs()->getCallConv(); + return ExpectedCallingConv == ActualCallingConv; +} + void MicrosoftCXXABI::EmitCXXConstructors(const CXXConstructorDecl *D) { // There's only one constructor type in this ABI. CGM.EmitGlobal(GlobalDecl(D, Ctor_Complete)); + + // Exported default constructors either have a simple call-site where they use + // the typical calling convention and have a single 'this' pointer for an + // argument -or- they get a wrapper function which appropriately thunks to the + // real default constructor. This thunk is the default constructor closure. + if (D->hasAttr() && D->isDefaultConstructor()) + if (!hasDefaultCXXMethodCC(getContext(), D) || D->getNumParams() != 0) { + llvm::Function *Fn = getAddrOfCXXCtorClosure(D, Ctor_DefaultClosure); + Fn->setLinkage(llvm::GlobalValue::WeakODRLinkage); + Fn->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass); + } } void MicrosoftCXXABI::EmitVBPtrStores(CodeGenFunction &CGF, @@ -3223,11 +3244,14 @@ void MicrosoftCXXABI::emitCXXStructor(const CXXMethodDecl *MD, } llvm::Function * -MicrosoftCXXABI::getAddrOfCXXCopyCtorClosure(const CXXConstructorDecl *CD) { +MicrosoftCXXABI::getAddrOfCXXCtorClosure(const CXXConstructorDecl *CD, + CXXCtorType CT) { + assert(CT == Ctor_CopyingClosure || CT == Ctor_DefaultClosure); + // Calculate the mangled name. SmallString<256> ThunkName; llvm::raw_svector_ostream Out(ThunkName); - getMangleContext().mangleCXXCtor(CD, Ctor_CopyingClosure, Out); + getMangleContext().mangleCXXCtor(CD, CT, Out); Out.flush(); // If the thunk has been generated previously, just return it. @@ -3235,12 +3259,13 @@ MicrosoftCXXABI::getAddrOfCXXCopyCtorClosure(const CXXConstructorDecl *CD) { return cast(GV); // Create the llvm::Function. - const CGFunctionInfo &FnInfo = CGM.getTypes().arrangeMSCopyCtorClosure(CD); + const CGFunctionInfo &FnInfo = CGM.getTypes().arrangeMSCtorClosure(CD, CT); llvm::FunctionType *ThunkTy = CGM.getTypes().GetFunctionType(FnInfo); const CXXRecordDecl *RD = CD->getParent(); QualType RecordTy = getContext().getRecordType(RD); llvm::Function *ThunkFn = llvm::Function::Create( ThunkTy, getLinkageForRTTI(RecordTy), ThunkName.str(), &CGM.getModule()); + bool IsCopy = CT == Ctor_CopyingClosure; // Start codegen. CodeGenFunction CGF(CGM); @@ -3249,8 +3274,7 @@ MicrosoftCXXABI::getAddrOfCXXCopyCtorClosure(const CXXConstructorDecl *CD) { // Build FunctionArgs. FunctionArgList FunctionArgs; - // A copy constructor always starts with a 'this' pointer as its first - // argument. + // A constructor always starts with a 'this' pointer as its first argument. buildThisParam(CGF, FunctionArgs); // Following the 'this' pointer is a reference to the source object that we @@ -3259,11 +3283,12 @@ MicrosoftCXXABI::getAddrOfCXXCopyCtorClosure(const CXXConstructorDecl *CD) { getContext(), nullptr, SourceLocation(), &getContext().Idents.get("src"), getContext().getLValueReferenceType(RecordTy, /*SpelledAsLValue=*/true)); - FunctionArgs.push_back(&SrcParam); + if (IsCopy) + FunctionArgs.push_back(&SrcParam); - // Copy constructors for classes which utilize virtual bases have an - // additional parameter which indicates whether or not it is being delegated - // to by a more derived constructor. + // Constructors for classes which utilize virtual bases have an additional + // parameter which indicates whether or not it is being delegated to by a more + // derived constructor. ImplicitParamDecl IsMostDerived(getContext(), nullptr, SourceLocation(), &getContext().Idents.get("is_most_derived"), getContext().IntTy); @@ -3278,7 +3303,8 @@ MicrosoftCXXABI::getAddrOfCXXCopyCtorClosure(const CXXConstructorDecl *CD) { llvm::Value *This = getThisValue(CGF); llvm::Value *SrcVal = - CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(&SrcParam), "src"); + IsCopy ? CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(&SrcParam), "src") + : nullptr; CallArgList Args; @@ -3286,11 +3312,12 @@ MicrosoftCXXABI::getAddrOfCXXCopyCtorClosure(const CXXConstructorDecl *CD) { Args.add(RValue::get(This), CD->getThisType(getContext())); // Push the src ptr. - Args.add(RValue::get(SrcVal), SrcParam.getType()); + if (SrcVal) + Args.add(RValue::get(SrcVal), SrcParam.getType()); // Add the rest of the default arguments. std::vector ArgVec; - for (unsigned I = 1, E = CD->getNumParams(); I != E; ++I) + for (unsigned I = IsCopy ? 1 : 0, E = CD->getNumParams(); I != E; ++I) ArgVec.push_back(getContext().getDefaultArgExprForConstructor(CD, I)); CodeGenFunction::RunCleanupsScope Cleanups(CGF); @@ -3298,7 +3325,7 @@ MicrosoftCXXABI::getAddrOfCXXCopyCtorClosure(const CXXConstructorDecl *CD) { const auto *FPT = CD->getType()->castAs(); ConstExprIterator ArgBegin(ArgVec.data()), ArgEnd(ArgVec.data() + ArgVec.size()); - CGF.EmitCallArgs(Args, FPT, ArgBegin, ArgEnd, CD, 1); + CGF.EmitCallArgs(Args, FPT, ArgBegin, ArgEnd, CD, IsCopy ? 1 : 0); // Insert any ABI-specific implicit constructor arguments. unsigned ExtraArgs = addImplicitConstructorArgs(CGF, CD, Ctor_Complete, @@ -3330,14 +3357,9 @@ llvm::Constant *MicrosoftCXXABI::getCatchableType(QualType T, const CXXConstructorDecl *CD = RD ? CGM.getContext().getCopyConstructorForExceptionObject(RD) : nullptr; CXXCtorType CT = Ctor_Complete; - if (CD) { - CallingConv ExpectedCallingConv = getContext().getDefaultCallingConvention( - /*IsVariadic=*/false, /*IsCXXMethod=*/true); - CallingConv ActualCallingConv = - CD->getType()->getAs()->getCallConv(); - if (ExpectedCallingConv != ActualCallingConv || CD->getNumParams() != 1) + if (CD) + if (!hasDefaultCXXMethodCC(getContext(), CD) || CD->getNumParams() != 1) CT = Ctor_CopyingClosure; - } uint32_t Size = getContext().getTypeSizeInChars(T).getQuantity(); SmallString<256> MangledName; @@ -3358,7 +3380,7 @@ llvm::Constant *MicrosoftCXXABI::getCatchableType(QualType T, llvm::Constant *CopyCtor; if (CD) { if (CT == Ctor_CopyingClosure) - CopyCtor = getAddrOfCXXCopyCtorClosure(CD); + CopyCtor = getAddrOfCXXCtorClosure(CD, Ctor_CopyingClosure); else CopyCtor = CGM.getAddrOfCXXStructor(CD, StructorType::Complete); diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp index 9c6f638119..7a70cddf9d 100644 --- a/lib/Sema/SemaDecl.cpp +++ b/lib/Sema/SemaDecl.cpp @@ -12064,6 +12064,24 @@ void Sema::ActOnStartCXXMemberDeclarations(Scope *S, Decl *TagD, "Broken injected-class-name"); } +static void getDefaultArgExprsForConstructors(Sema &S, CXXRecordDecl *Class) { + for (Decl *Member : Class->decls()) { + auto *CD = dyn_cast(Member); + if (!CD || !CD->isDefaultConstructor() || !CD->hasAttr()) + continue; + + for (unsigned I = 0, E = CD->getNumParams(); I != E; ++I) { + // Skip any default arguments that we've already instantiated. + if (S.Context.getDefaultArgExprForConstructor(CD, I)) + continue; + + Expr *DefaultArg = S.BuildCXXDefaultArgExpr(Class->getLocation(), CD, + CD->getParamDecl(I)).get(); + S.Context.addDefaultArgExprForConstructor(CD, I, DefaultArg); + } + } +} + void Sema::ActOnTagFinishDefinition(Scope *S, Decl *TagD, SourceLocation RBraceLoc) { AdjustDeclIfTemplate(TagD); @@ -12077,9 +12095,17 @@ void Sema::ActOnTagFinishDefinition(Scope *S, Decl *TagD, RD->completeDefinition(); } - if (isa(Tag)) + if (auto *Class = dyn_cast(Tag)) { FieldCollector->FinishClass(); + // Default constructors that are annotated with __declspec(dllexport) which + // have default arguments or don't use the standard calling convention are + // wrapped with a thunk called the default constructor closure. + if (!Class->getDescribedClassTemplate() && + Context.getTargetInfo().getCXXABI().isMicrosoft()) + getDefaultArgExprsForConstructors(*this, Class); + } + // Exit this scope of this tag's definition. PopDeclContext(); diff --git a/test/CodeGenCXX/dllexport.cpp b/test/CodeGenCXX/dllexport.cpp index 3b04c264c5..60d37ef0a8 100644 --- a/test/CodeGenCXX/dllexport.cpp +++ b/test/CodeGenCXX/dllexport.cpp @@ -484,6 +484,28 @@ struct S { }; }; +struct CtorWithClosure { + __declspec(dllexport) CtorWithClosure(...) {} +// M32-DAG: define weak_odr dllexport void @"\01??_FCtorWithClosure@@QAEXXZ" +// M32-DAG: %[[this_addr:.*]] = alloca %struct.CtorWithClosure*, align 4 +// M32-DAG: store %struct.CtorWithClosure* %this, %struct.CtorWithClosure** %[[this_addr]], align 4 +// M32-DAG: %[[this:.*]] = load %struct.CtorWithClosure*, %struct.CtorWithClosure** %[[this_addr]] +// M32-DAG: call %struct.CtorWithClosure* (%struct.CtorWithClosure*, ...)* @"\01??0CtorWithClosure@@QAA@ZZ"(%struct.CtorWithClosure* %[[this]]) +// M32-DAG: ret void +}; + +struct __declspec(dllexport) ClassWithClosure { + ClassWithClosure(ClassWithClosure &&) = delete; + ClassWithClosure(ClassWithClosure &) = delete; + ~ClassWithClosure() = delete; + ClassWithClosure(...) {} +// M32-DAG: define weak_odr dllexport void @"\01??_FClassWithClosure@@QAEXXZ" +// M32-DAG: %[[this_addr:.*]] = alloca %struct.ClassWithClosure*, align 4 +// M32-DAG: store %struct.ClassWithClosure* %this, %struct.ClassWithClosure** %[[this_addr]], align 4 +// M32-DAG: %[[this:.*]] = load %struct.ClassWithClosure*, %struct.ClassWithClosure** %[[this_addr]] +// M32-DAG: call %struct.ClassWithClosure* (%struct.ClassWithClosure*, ...)* @"\01??0ClassWithClosure@@QAA@ZZ"(%struct.ClassWithClosure* %[[this]]) +// M32-DAG: ret void +}; struct __declspec(dllexport) T { // Copy assignment operator: -- 2.40.0