| //===- CXXInheritance.h - C++ Inheritance -----------------------*- C++ -*-===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file provides routines that help analyzing C++ inheritance hierarchies. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_CLANG_AST_CXXINHERITANCE_H |
| #define LLVM_CLANG_AST_CXXINHERITANCE_H |
| |
| #include "clang/AST/DeclBase.h" |
| #include "clang/AST/DeclCXX.h" |
| #include "clang/AST/DeclarationName.h" |
| #include "clang/AST/Type.h" |
| #include "clang/AST/TypeOrdering.h" |
| #include "clang/Basic/Specifiers.h" |
| #include "llvm/ADT/DenseMap.h" |
| #include "llvm/ADT/DenseSet.h" |
| #include "llvm/ADT/MapVector.h" |
| #include "llvm/ADT/SmallSet.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/ADT/iterator_range.h" |
| #include <list> |
| #include <memory> |
| #include <utility> |
| |
| namespace clang { |
| |
| class ASTContext; |
| class NamedDecl; |
| |
| /// Represents an element in a path from a derived class to a |
| /// base class. |
| /// |
| /// Each step in the path references the link from a |
| /// derived class to one of its direct base classes, along with a |
| /// base "number" that identifies which base subobject of the |
| /// original derived class we are referencing. |
| struct CXXBasePathElement { |
| /// The base specifier that states the link from a derived |
| /// class to a base class, which will be followed by this base |
| /// path element. |
| const CXXBaseSpecifier *Base; |
| |
| /// The record decl of the class that the base is a base of. |
| const CXXRecordDecl *Class; |
| |
| /// Identifies which base class subobject (of type |
| /// \c Base->getType()) this base path element refers to. |
| /// |
| /// This value is only valid if \c !Base->isVirtual(), because there |
| /// is no base numbering for the zero or one virtual bases of a |
| /// given type. |
| int SubobjectNumber; |
| }; |
| |
| /// Represents a path from a specific derived class |
| /// (which is not represented as part of the path) to a particular |
| /// (direct or indirect) base class subobject. |
| /// |
| /// Individual elements in the path are described by the \c CXXBasePathElement |
| /// structure, which captures both the link from a derived class to one of its |
| /// direct bases and identification describing which base class |
| /// subobject is being used. |
| class CXXBasePath : public SmallVector<CXXBasePathElement, 4> { |
| public: |
| /// The access along this inheritance path. This is only |
| /// calculated when recording paths. AS_none is a special value |
| /// used to indicate a path which permits no legal access. |
| AccessSpecifier Access = AS_public; |
| |
| CXXBasePath() = default; |
| |
| /// The declarations found inside this base class subobject. |
| DeclContext::lookup_iterator Decls; |
| |
| void clear() { |
| SmallVectorImpl<CXXBasePathElement>::clear(); |
| Access = AS_public; |
| } |
| }; |
| |
| /// BasePaths - Represents the set of paths from a derived class to |
| /// one of its (direct or indirect) bases. For example, given the |
| /// following class hierarchy: |
| /// |
| /// @code |
| /// class A { }; |
| /// class B : public A { }; |
| /// class C : public A { }; |
| /// class D : public B, public C{ }; |
| /// @endcode |
| /// |
| /// There are two potential BasePaths to represent paths from D to a |
| /// base subobject of type A. One path is (D,0) -> (B,0) -> (A,0) |
| /// and another is (D,0)->(C,0)->(A,1). These two paths actually |
| /// refer to two different base class subobjects of the same type, |
| /// so the BasePaths object refers to an ambiguous path. On the |
| /// other hand, consider the following class hierarchy: |
| /// |
| /// @code |
| /// class A { }; |
| /// class B : public virtual A { }; |
| /// class C : public virtual A { }; |
| /// class D : public B, public C{ }; |
| /// @endcode |
| /// |
| /// Here, there are two potential BasePaths again, (D, 0) -> (B, 0) |
| /// -> (A,v) and (D, 0) -> (C, 0) -> (A, v), but since both of them |
| /// refer to the same base class subobject of type A (the virtual |
| /// one), there is no ambiguity. |
| class CXXBasePaths { |
| friend class CXXRecordDecl; |
| |
| /// The type from which this search originated. |
| const CXXRecordDecl *Origin = nullptr; |
| |
| /// Paths - The actual set of paths that can be taken from the |
| /// derived class to the same base class. |
| std::list<CXXBasePath> Paths; |
| |
| /// ClassSubobjects - Records the class subobjects for each class |
| /// type that we've seen. The first element IsVirtBase says |
| /// whether we found a path to a virtual base for that class type, |
| /// while NumberOfNonVirtBases contains the number of non-virtual base |
| /// class subobjects for that class type. The key of the map is |
| /// the cv-unqualified canonical type of the base class subobject. |
| struct IsVirtBaseAndNumberNonVirtBases { |
| unsigned IsVirtBase : 1; |
| unsigned NumberOfNonVirtBases : 31; |
| }; |
| llvm::SmallDenseMap<QualType, IsVirtBaseAndNumberNonVirtBases, 8> |
| ClassSubobjects; |
| |
| /// VisitedDependentRecords - Records the dependent records that have been |
| /// already visited. |
| llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedDependentRecords; |
| |
| /// DetectedVirtual - The base class that is virtual. |
| const RecordType *DetectedVirtual = nullptr; |
| |
| /// ScratchPath - A BasePath that is used by Sema::lookupInBases |
| /// to help build the set of paths. |
| CXXBasePath ScratchPath; |
| |
| /// FindAmbiguities - Whether Sema::IsDerivedFrom should try find |
| /// ambiguous paths while it is looking for a path from a derived |
| /// type to a base type. |
| bool FindAmbiguities; |
| |
| /// RecordPaths - Whether Sema::IsDerivedFrom should record paths |
| /// while it is determining whether there are paths from a derived |
| /// type to a base type. |
| bool RecordPaths; |
| |
| /// DetectVirtual - Whether Sema::IsDerivedFrom should abort the search |
| /// if it finds a path that goes across a virtual base. The virtual class |
| /// is also recorded. |
| bool DetectVirtual; |
| |
| bool lookupInBases(ASTContext &Context, const CXXRecordDecl *Record, |
| CXXRecordDecl::BaseMatchesCallback BaseMatches, |
| bool LookupInDependent = false); |
| |
| public: |
| using paths_iterator = std::list<CXXBasePath>::iterator; |
| using const_paths_iterator = std::list<CXXBasePath>::const_iterator; |
| using decl_iterator = NamedDecl **; |
| |
| /// BasePaths - Construct a new BasePaths structure to record the |
| /// paths for a derived-to-base search. |
| explicit CXXBasePaths(bool FindAmbiguities = true, bool RecordPaths = true, |
| bool DetectVirtual = true) |
| : FindAmbiguities(FindAmbiguities), RecordPaths(RecordPaths), |
| DetectVirtual(DetectVirtual) {} |
| |
| paths_iterator begin() { return Paths.begin(); } |
| paths_iterator end() { return Paths.end(); } |
| const_paths_iterator begin() const { return Paths.begin(); } |
| const_paths_iterator end() const { return Paths.end(); } |
| |
| CXXBasePath& front() { return Paths.front(); } |
| const CXXBasePath& front() const { return Paths.front(); } |
| |
| using decl_range = llvm::iterator_range<decl_iterator>; |
| |
| /// Determine whether the path from the most-derived type to the |
| /// given base type is ambiguous (i.e., it refers to multiple subobjects of |
| /// the same base type). |
| bool isAmbiguous(CanQualType BaseType); |
| |
| /// Whether we are finding multiple paths to detect ambiguities. |
| bool isFindingAmbiguities() const { return FindAmbiguities; } |
| |
| /// Whether we are recording paths. |
| bool isRecordingPaths() const { return RecordPaths; } |
| |
| /// Specify whether we should be recording paths or not. |
| void setRecordingPaths(bool RP) { RecordPaths = RP; } |
| |
| /// Whether we are detecting virtual bases. |
| bool isDetectingVirtual() const { return DetectVirtual; } |
| |
| /// The virtual base discovered on the path (if we are merely |
| /// detecting virtuals). |
| const RecordType* getDetectedVirtual() const { |
| return DetectedVirtual; |
| } |
| |
| /// Retrieve the type from which this base-paths search |
| /// began |
| const CXXRecordDecl *getOrigin() const { return Origin; } |
| void setOrigin(const CXXRecordDecl *Rec) { Origin = Rec; } |
| |
| /// Clear the base-paths results. |
| void clear(); |
| |
| /// Swap this data structure's contents with another CXXBasePaths |
| /// object. |
| void swap(CXXBasePaths &Other); |
| }; |
| |
| /// Uniquely identifies a virtual method within a class |
| /// hierarchy by the method itself and a class subobject number. |
| struct UniqueVirtualMethod { |
| /// The overriding virtual method. |
| CXXMethodDecl *Method = nullptr; |
| |
| /// The subobject in which the overriding virtual method |
| /// resides. |
| unsigned Subobject = 0; |
| |
| /// The virtual base class subobject of which this overridden |
| /// virtual method is a part. Note that this records the closest |
| /// derived virtual base class subobject. |
| const CXXRecordDecl *InVirtualSubobject = nullptr; |
| |
| UniqueVirtualMethod() = default; |
| |
| UniqueVirtualMethod(CXXMethodDecl *Method, unsigned Subobject, |
| const CXXRecordDecl *InVirtualSubobject) |
| : Method(Method), Subobject(Subobject), |
| InVirtualSubobject(InVirtualSubobject) {} |
| |
| friend bool operator==(const UniqueVirtualMethod &X, |
| const UniqueVirtualMethod &Y) { |
| return X.Method == Y.Method && X.Subobject == Y.Subobject && |
| X.InVirtualSubobject == Y.InVirtualSubobject; |
| } |
| |
| friend bool operator!=(const UniqueVirtualMethod &X, |
| const UniqueVirtualMethod &Y) { |
| return !(X == Y); |
| } |
| }; |
| |
| /// The set of methods that override a given virtual method in |
| /// each subobject where it occurs. |
| /// |
| /// The first part of the pair is the subobject in which the |
| /// overridden virtual function occurs, while the second part of the |
| /// pair is the virtual method that overrides it (including the |
| /// subobject in which that virtual function occurs). |
| class OverridingMethods { |
| using ValuesT = SmallVector<UniqueVirtualMethod, 4>; |
| using MapType = llvm::MapVector<unsigned, ValuesT>; |
| |
| MapType Overrides; |
| |
| public: |
| // Iterate over the set of subobjects that have overriding methods. |
| using iterator = MapType::iterator; |
| using const_iterator = MapType::const_iterator; |
| |
| iterator begin() { return Overrides.begin(); } |
| const_iterator begin() const { return Overrides.begin(); } |
| iterator end() { return Overrides.end(); } |
| const_iterator end() const { return Overrides.end(); } |
| unsigned size() const { return Overrides.size(); } |
| |
| // Iterate over the set of overriding virtual methods in a given |
| // subobject. |
| using overriding_iterator = |
| SmallVectorImpl<UniqueVirtualMethod>::iterator; |
| using overriding_const_iterator = |
| SmallVectorImpl<UniqueVirtualMethod>::const_iterator; |
| |
| // Add a new overriding method for a particular subobject. |
| void add(unsigned OverriddenSubobject, UniqueVirtualMethod Overriding); |
| |
| // Add all of the overriding methods from "other" into overrides for |
| // this method. Used when merging the overrides from multiple base |
| // class subobjects. |
| void add(const OverridingMethods &Other); |
| |
| // Replace all overriding virtual methods in all subobjects with the |
| // given virtual method. |
| void replaceAll(UniqueVirtualMethod Overriding); |
| }; |
| |
| /// A mapping from each virtual member function to its set of |
| /// final overriders. |
| /// |
| /// Within a class hierarchy for a given derived class, each virtual |
| /// member function in that hierarchy has one or more "final |
| /// overriders" (C++ [class.virtual]p2). A final overrider for a |
| /// virtual function "f" is the virtual function that will actually be |
| /// invoked when dispatching a call to "f" through the |
| /// vtable. Well-formed classes have a single final overrider for each |
| /// virtual function; in abstract classes, the final overrider for at |
| /// least one virtual function is a pure virtual function. Due to |
| /// multiple, virtual inheritance, it is possible for a class to have |
| /// more than one final overrider. Athough this is an error (per C++ |
| /// [class.virtual]p2), it is not considered an error here: the final |
| /// overrider map can represent multiple final overriders for a |
| /// method, and it is up to the client to determine whether they are |
| /// problem. For example, the following class \c D has two final |
| /// overriders for the virtual function \c A::f(), one in \c C and one |
| /// in \c D: |
| /// |
| /// \code |
| /// struct A { virtual void f(); }; |
| /// struct B : virtual A { virtual void f(); }; |
| /// struct C : virtual A { virtual void f(); }; |
| /// struct D : B, C { }; |
| /// \endcode |
| /// |
| /// This data structure contains a mapping from every virtual |
| /// function *that does not override an existing virtual function* and |
| /// in every subobject where that virtual function occurs to the set |
| /// of virtual functions that override it. Thus, the same virtual |
| /// function \c A::f can actually occur in multiple subobjects of type |
| /// \c A due to multiple inheritance, and may be overridden by |
| /// different virtual functions in each, as in the following example: |
| /// |
| /// \code |
| /// struct A { virtual void f(); }; |
| /// struct B : A { virtual void f(); }; |
| /// struct C : A { virtual void f(); }; |
| /// struct D : B, C { }; |
| /// \endcode |
| /// |
| /// Unlike in the previous example, where the virtual functions \c |
| /// B::f and \c C::f both overrode \c A::f in the same subobject of |
| /// type \c A, in this example the two virtual functions both override |
| /// \c A::f but in *different* subobjects of type A. This is |
| /// represented by numbering the subobjects in which the overridden |
| /// and the overriding virtual member functions are located. Subobject |
| /// 0 represents the virtual base class subobject of that type, while |
| /// subobject numbers greater than 0 refer to non-virtual base class |
| /// subobjects of that type. |
| class CXXFinalOverriderMap |
| : public llvm::MapVector<const CXXMethodDecl *, OverridingMethods> {}; |
| |
| /// A set of all the primary bases for a class. |
| class CXXIndirectPrimaryBaseSet |
| : public llvm::SmallSet<const CXXRecordDecl*, 32> {}; |
| |
| inline bool |
| inheritanceModelHasVBPtrOffsetField(MSInheritanceModel Inheritance) { |
| return Inheritance == MSInheritanceModel::Unspecified; |
| } |
| |
| // Only member pointers to functions need a this adjustment, since it can be |
| // combined with the field offset for data pointers. |
| inline bool inheritanceModelHasNVOffsetField(bool IsMemberFunction, |
| MSInheritanceModel Inheritance) { |
| return IsMemberFunction && Inheritance >= MSInheritanceModel::Multiple; |
| } |
| |
| inline bool |
| inheritanceModelHasVBTableOffsetField(MSInheritanceModel Inheritance) { |
| return Inheritance >= MSInheritanceModel::Virtual; |
| } |
| |
| inline bool inheritanceModelHasOnlyOneField(bool IsMemberFunction, |
| MSInheritanceModel Inheritance) { |
| if (IsMemberFunction) |
| return Inheritance <= MSInheritanceModel::Single; |
| return Inheritance <= MSInheritanceModel::Multiple; |
| } |
| |
| } // namespace clang |
| |
| #endif // LLVM_CLANG_AST_CXXINHERITANCE_H |