1 //===- BaseSubobject.h - BaseSubobject class --------------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file provides a definition of the BaseSubobject class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_CLANG_AST_BASESUBOBJECT_H
15 #define LLVM_CLANG_AST_BASESUBOBJECT_H
16 
17 #include "clang/AST/CharUnits.h"
18 #include "clang/AST/DeclCXX.h"
19 #include "llvm/ADT/DenseMapInfo.h"
20 #include "llvm/Support/type_traits.h"
21 #include <cstdint>
22 #include <utility>
23 
24 namespace clang {
25 
26 class CXXRecordDecl;
27 
28 // BaseSubobject - Uniquely identifies a direct or indirect base class.
29 // Stores both the base class decl and the offset from the most derived class to
30 // the base class. Used for vtable and VTT generation.
31 class BaseSubobject {
32   /// Base - The base class declaration.
33   const CXXRecordDecl *Base;
34 
35   /// BaseOffset - The offset from the most derived class to the base class.
36   CharUnits BaseOffset;
37 
38 public:
39   BaseSubobject() = default;
BaseSubobject(const CXXRecordDecl * Base,CharUnits BaseOffset)40   BaseSubobject(const CXXRecordDecl *Base, CharUnits BaseOffset)
41       : Base(Base), BaseOffset(BaseOffset) {}
42 
43   /// getBase - Returns the base class declaration.
getBase()44   const CXXRecordDecl *getBase() const { return Base; }
45 
46   /// getBaseOffset - Returns the base class offset.
getBaseOffset()47   CharUnits getBaseOffset() const { return BaseOffset; }
48 
49   friend bool operator==(const BaseSubobject &LHS, const BaseSubobject &RHS) {
50     return LHS.Base == RHS.Base && LHS.BaseOffset == RHS.BaseOffset;
51  }
52 };
53 
54 } // namespace clang
55 
56 namespace llvm {
57 
58 template<> struct DenseMapInfo<clang::BaseSubobject> {
59   static clang::BaseSubobject getEmptyKey() {
60     return clang::BaseSubobject(
61       DenseMapInfo<const clang::CXXRecordDecl *>::getEmptyKey(),
62       clang::CharUnits::fromQuantity(DenseMapInfo<int64_t>::getEmptyKey()));
63   }
64 
65   static clang::BaseSubobject getTombstoneKey() {
66     return clang::BaseSubobject(
67       DenseMapInfo<const clang::CXXRecordDecl *>::getTombstoneKey(),
68       clang::CharUnits::fromQuantity(DenseMapInfo<int64_t>::getTombstoneKey()));
69   }
70 
71   static unsigned getHashValue(const clang::BaseSubobject &Base) {
72     using PairTy = std::pair<const clang::CXXRecordDecl *, clang::CharUnits>;
73 
74     return DenseMapInfo<PairTy>::getHashValue(PairTy(Base.getBase(),
75                                                      Base.getBaseOffset()));
76   }
77 
78   static bool isEqual(const clang::BaseSubobject &LHS,
79                       const clang::BaseSubobject &RHS) {
80     return LHS == RHS;
81   }
82 };
83 
84 // It's OK to treat BaseSubobject as a POD type.
85 template <> struct isPodLike<clang::BaseSubobject> {
86   static const bool value = true;
87 };
88 
89 } // namespace llvm
90 
91 #endif // LLVM_CLANG_AST_BASESUBOBJECT_H
92