1 //===-- ODRHash.h - Hashing to diagnose ODR failures ------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 ///
9 /// \file
10 /// This file contains the declaration of the ODRHash class, which calculates
11 /// a hash based on AST nodes, which is stable across different runs.
12 ///
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_CLANG_AST_ODRHASH_H
16 #define LLVM_CLANG_AST_ODRHASH_H
17 
18 #include "clang/AST/DeclarationName.h"
19 #include "clang/AST/Type.h"
20 #include "clang/AST/TemplateBase.h"
21 #include "llvm/ADT/DenseMap.h"
22 #include "llvm/ADT/FoldingSet.h"
23 #include "llvm/ADT/PointerUnion.h"
24 #include "llvm/ADT/SmallVector.h"
25 
26 namespace clang {
27 
28 class APValue;
29 class Decl;
30 class IdentifierInfo;
31 class NestedNameSpecifier;
32 class Stmt;
33 class TemplateParameterList;
34 
35 // ODRHash is used to calculate a hash based on AST node contents that
36 // does not rely on pointer addresses.  This allows the hash to not vary
37 // between runs and is usable to detect ODR problems in modules.  To use,
38 // construct an ODRHash object, then call Add* methods over the nodes that
39 // need to be hashed.  Then call CalculateHash to get the hash value.
40 // Typically, only one Add* call is needed.  clear can be called to reuse the
41 // object.
42 class ODRHash {
43   // Use DenseMaps to convert from DeclarationName and Type pointers
44   // to an index value.
45   llvm::DenseMap<DeclarationName, unsigned> DeclNameMap;
46 
47   // Save space by processing bools at the end.
48   llvm::SmallVector<bool, 128> Bools;
49 
50   llvm::FoldingSetNodeID ID;
51 
52 public:
ODRHash()53   ODRHash() {}
54 
55   // Use this for ODR checking classes between modules.  This method compares
56   // more information than the AddDecl class.
57   void AddCXXRecordDecl(const CXXRecordDecl *Record);
58 
59   // Use this for ODR checking records in C/Objective-C between modules. This
60   // method compares more information than the AddDecl class.
61   void AddRecordDecl(const RecordDecl *Record);
62 
63   // Use this for ODR checking ObjC interfaces. This
64   // method compares more information than the AddDecl class.
65   void AddObjCInterfaceDecl(const ObjCInterfaceDecl *Record);
66 
67   // Use this for ODR checking functions between modules.  This method compares
68   // more information than the AddDecl class.  SkipBody will process the
69   // hash as if the function has no body.
70   void AddFunctionDecl(const FunctionDecl *Function, bool SkipBody = false);
71 
72   // Use this for ODR checking enums between modules.  This method compares
73   // more information than the AddDecl class.
74   void AddEnumDecl(const EnumDecl *Enum);
75 
76   // Use this for ODR checking ObjC protocols. This
77   // method compares more information than the AddDecl class.
78   void AddObjCProtocolDecl(const ObjCProtocolDecl *P);
79 
80   // Process SubDecls of the main Decl.  This method calls the DeclVisitor
81   // while AddDecl does not.
82   void AddSubDecl(const Decl *D);
83 
84   // Reset the object for reuse.
85   void clear();
86 
87   // Add booleans to ID and uses it to calculate the hash.
88   unsigned CalculateHash();
89 
90   // Add AST nodes that need to be processed.
91   void AddDecl(const Decl *D);
92   void AddType(const Type *T);
93   void AddQualType(QualType T);
94   void AddStmt(const Stmt *S);
95   void AddIdentifierInfo(const IdentifierInfo *II);
96   void AddNestedNameSpecifier(const NestedNameSpecifier *NNS);
97   void AddTemplateName(TemplateName Name);
98   void AddDeclarationName(DeclarationName Name, bool TreatAsDecl = false);
99   void AddTemplateArgument(TemplateArgument TA);
100   void AddTemplateParameterList(const TemplateParameterList *TPL);
101 
102   // Save booleans until the end to lower the size of data to process.
103   void AddBoolean(bool value);
104 
105   void AddStructuralValue(const APValue &);
106 
107   static bool isSubDeclToBeProcessed(const Decl *D, const DeclContext *Parent);
108 
109 private:
110   void AddDeclarationNameImpl(DeclarationName Name);
111 };
112 
113 }  // end namespace clang
114 
115 #endif
116