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      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:
     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