//===-- ODRHash.h - Hashing to diagnose ODR failures ------------*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

///

/// \file

/// This file contains the declaration of the ODRHash class, which calculates

/// a hash based on AST nodes, which is stable across different runs.

///

//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_AST_ODRHASH_H

#define LLVM_CLANG_AST_ODRHASH_H

#include "clang/AST/DeclarationName.h"

#include "clang/AST/Type.h"

#include "clang/AST/TemplateBase.h"

#include "llvm/ADT/DenseMap.h"

#include "llvm/ADT/FoldingSet.h"

#include "llvm/ADT/PointerUnion.h"

#include "llvm/ADT/SmallVector.h"

namespace clang {

class Decl;

class IdentifierInfo;

class NestedNameSpecifier;

class Stmt;

class TemplateParameterList;

// ODRHash is used to calculate a hash based on AST node contents that

// does not rely on pointer addresses.  This allows the hash to not vary

// between runs and is usable to detect ODR problems in modules.  To use,

// construct an ODRHash object, then call Add* methods over the nodes that

// need to be hashed.  Then call CalculateHash to get the hash value.

// Typically, only one Add* call is needed.  clear can be called to reuse the

// object.

class ODRHash {

  // Use DenseMaps to convert from DeclarationName and Type pointers

  // to an index value.

  llvm::DenseMap<DeclarationName, unsigned> DeclNameMap;

  // Save space by processing bools at the end.

  llvm::SmallVector<bool, 128> Bools;

  llvm::FoldingSetNodeID ID;

public:

  ODRHash() {}

  // Use this for ODR checking classes between modules.  This method compares

  // more information than the AddDecl class.

  void AddCXXRecordDecl(const CXXRecordDecl *Record);

  // Use this for ODR checking functions between modules.  This method compares

  // more information than the AddDecl class.  SkipBody will process the

  // hash as if the function has no body.

  void AddFunctionDecl(const FunctionDecl *Function, bool SkipBody = false);

  // Use this for ODR checking enums between modules.  This method compares

  // more information than the AddDecl class.

  void AddEnumDecl(const EnumDecl *Enum);

  // Process SubDecls of the main Decl.  This method calls the DeclVisitor

  // while AddDecl does not.

  void AddSubDecl(const Decl *D);

  // Reset the object for reuse.

  void clear();

  // Add booleans to ID and uses it to calculate the hash.

  unsigned CalculateHash();

  // Add AST nodes that need to be processed.

  void AddDecl(const Decl *D);

  void AddType(const Type *T);

  void AddQualType(QualType T);

  void AddStmt(const Stmt *S);

  void AddIdentifierInfo(const IdentifierInfo *II);

  void AddNestedNameSpecifier(const NestedNameSpecifier *NNS);

  void AddTemplateName(TemplateName Name);

  void AddDeclarationName(DeclarationName Name, bool TreatAsDecl = false);

  void AddTemplateArgument(TemplateArgument TA);

  void AddTemplateParameterList(const TemplateParameterList *TPL);

  // Save booleans until the end to lower the size of data to process.

  void AddBoolean(bool value);

  static bool isDeclToBeProcessed(const Decl* D, const DeclContext *Parent);

private:

  void AddDeclarationNameImpl(DeclarationName Name);

};

}  // end namespace clang

#endif