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      1 //===-- ODRHash.h - Hashing to diagnose ODR failures ------------*- 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 /// \file
     11 /// This file contains the declaration of the ODRHash class, which calculates
     12 /// a hash based on AST nodes, which is stable across different runs.
     13 ///
     14 //===----------------------------------------------------------------------===//
     15 
     16 #include "clang/AST/DeclarationName.h"
     17 #include "clang/AST/Type.h"
     18 #include "clang/AST/TemplateBase.h"
     19 #include "llvm/ADT/DenseMap.h"
     20 #include "llvm/ADT/FoldingSet.h"
     21 #include "llvm/ADT/PointerUnion.h"
     22 #include "llvm/ADT/SmallVector.h"
     23 
     24 namespace clang {
     25 
     26 class Decl;
     27 class IdentifierInfo;
     28 class NestedNameSpecifer;
     29 class Stmt;
     30 class TemplateParameterList;
     31 
     32 // ODRHash is used to calculate a hash based on AST node contents that
     33 // does not rely on pointer addresses.  This allows the hash to not vary
     34 // between runs and is usable to detect ODR problems in modules.  To use,
     35 // construct an ODRHash object, then call Add* methods over the nodes that
     36 // need to be hashed.  Then call CalculateHash to get the hash value.
     37 // Typically, only one Add* call is needed.  clear can be called to reuse the
     38 // object.
     39 class ODRHash {
     40   // Use DenseMaps to convert between Decl and Type pointers and an index value.
     41   llvm::DenseMap<const Decl*, unsigned> DeclMap;
     42   llvm::DenseMap<const Type*, unsigned> TypeMap;
     43 
     44   // Save space by processing bools at the end.
     45   llvm::SmallVector<bool, 128> Bools;
     46 
     47   llvm::FoldingSetNodeID ID;
     48 
     49 public:
     50   ODRHash() {}
     51 
     52   // Use this for ODR checking classes between modules.  This method compares
     53   // more information than the AddDecl class.
     54   void AddCXXRecordDecl(const CXXRecordDecl *Record);
     55 
     56   // Process SubDecls of the main Decl.  This method calls the DeclVisitor
     57   // while AddDecl does not.
     58   void AddSubDecl(const Decl *D);
     59 
     60   // Reset the object for reuse.
     61   void clear();
     62 
     63   // Add booleans to ID and uses it to calculate the hash.
     64   unsigned CalculateHash();
     65 
     66   // Add AST nodes that need to be processed.
     67   void AddDecl(const Decl *D);
     68   void AddType(const Type *T);
     69   void AddQualType(QualType T);
     70   void AddStmt(const Stmt *S);
     71   void AddIdentifierInfo(const IdentifierInfo *II);
     72   void AddNestedNameSpecifier(const NestedNameSpecifier *NNS);
     73   void AddTemplateName(TemplateName Name);
     74   void AddDeclarationName(DeclarationName Name);
     75   void AddTemplateArgument(TemplateArgument TA);
     76   void AddTemplateParameterList(const TemplateParameterList *TPL);
     77 
     78   // Save booleans until the end to lower the size of data to process.
     79   void AddBoolean(bool value);
     80 
     81   static bool isWhitelistedDecl(const Decl* D, const CXXRecordDecl *Record);
     82 };
     83 
     84 }  // end namespace clang
     85