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 Decl;
29 class IdentifierInfo;
30 class NestedNameSpecifier;
31 class Stmt;
32 class TemplateParameterList;
33 
34 // ODRHash is used to calculate a hash based on AST node contents that
35 // does not rely on pointer addresses.  This allows the hash to not vary
36 // between runs and is usable to detect ODR problems in modules.  To use,
37 // construct an ODRHash object, then call Add* methods over the nodes that
38 // need to be hashed.  Then call CalculateHash to get the hash value.
39 // Typically, only one Add* call is needed.  clear can be called to reuse the
40 // object.
41 class ODRHash {
42   // Use DenseMaps to convert from DeclarationName and Type pointers
43   // to an index value.
44   llvm::DenseMap<DeclarationName, unsigned> DeclNameMap;
45 
46   // Save space by processing bools at the end.
47   llvm::SmallVector<bool, 128> Bools;
48 
49   llvm::FoldingSetNodeID ID;
50 
51 public:
ODRHash()52   ODRHash() {}
53 
54   // Use this for ODR checking classes between modules.  This method compares
55   // more information than the AddDecl class.
56   void AddCXXRecordDecl(const CXXRecordDecl *Record);
57 
58   // Use this for ODR checking functions between modules.  This method compares
59   // more information than the AddDecl class.  SkipBody will process the
60   // hash as if the function has no body.
61   void AddFunctionDecl(const FunctionDecl *Function, bool SkipBody = false);
62 
63   // Use this for ODR checking enums between modules.  This method compares
64   // more information than the AddDecl class.
65   void AddEnumDecl(const EnumDecl *Enum);
66 
67   // Process SubDecls of the main Decl.  This method calls the DeclVisitor
68   // while AddDecl does not.
69   void AddSubDecl(const Decl *D);
70 
71   // Reset the object for reuse.
72   void clear();
73 
74   // Add booleans to ID and uses it to calculate the hash.
75   unsigned CalculateHash();
76 
77   // Add AST nodes that need to be processed.
78   void AddDecl(const Decl *D);
79   void AddType(const Type *T);
80   void AddQualType(QualType T);
81   void AddStmt(const Stmt *S);
82   void AddIdentifierInfo(const IdentifierInfo *II);
83   void AddNestedNameSpecifier(const NestedNameSpecifier *NNS);
84   void AddTemplateName(TemplateName Name);
85   void AddDeclarationName(DeclarationName Name, bool TreatAsDecl = false);
86   void AddTemplateArgument(TemplateArgument TA);
87   void AddTemplateParameterList(const TemplateParameterList *TPL);
88 
89   // Save booleans until the end to lower the size of data to process.
90   void AddBoolean(bool value);
91 
92   static bool isDeclToBeProcessed(const Decl* D, const DeclContext *Parent);
93 
94 private:
95   void AddDeclarationNameImpl(DeclarationName Name);
96 };
97 
98 }  // end namespace clang
99 
100 #endif
101