//===- ModuleManager.cpp - Module Manager -----------------------*- 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

//

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

//

//  This file defines the ModuleManager class, which manages a set of loaded

//  modules for the ASTReader.

//

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

#ifndef LLVM_CLANG_SERIALIZATION_MODULEMANAGER_H

#define LLVM_CLANG_SERIALIZATION_MODULEMANAGER_H

#include "clang/Basic/LLVM.h"

#include "clang/Basic/Module.h"

#include "clang/Basic/SourceLocation.h"

#include "clang/Serialization/ModuleFile.h"

#include "llvm/ADT/DenseMap.h"

#include "llvm/ADT/IntrusiveRefCntPtr.h"

#include "llvm/ADT/STLExtras.h"

#include "llvm/ADT/SmallPtrSet.h"

#include "llvm/ADT/SmallVector.h"

#include "llvm/ADT/StringRef.h"

#include "llvm/ADT/iterator.h"

#include "llvm/ADT/iterator_range.h"

#include <cstdint>

#include <ctime>

#include <memory>

#include <string>

#include <utility>

namespace clang {

class FileEntry;

class FileManager;

class GlobalModuleIndex;

class HeaderSearch;

class InMemoryModuleCache;

class ModuleMap;

class PCHContainerReader;

namespace serialization {

/// Manages the set of modules loaded by an AST reader.

class ModuleManager {

  /// The chain of AST files, in the order in which we started to load

  /// them (this order isn't really useful for anything).

  SmallVector<std::unique_ptr<ModuleFile>, 2> Chain;

  /// The chain of non-module PCH files. The first entry is the one named

  /// by the user, the last one is the one that doesn't depend on anything

  /// further.

  SmallVector<ModuleFile *, 2> PCHChain;

  // The roots of the dependency DAG of AST files. This is used

  // to implement short-circuiting logic when running DFS over the dependencies.

  SmallVector<ModuleFile *, 2> Roots;

  /// All loaded modules, indexed by name.

  llvm::DenseMap<const FileEntry *, ModuleFile *> Modules;

  /// FileManager that handles translating between filenames and

  /// FileEntry *.

  FileManager &FileMgr;

  /// Cache of PCM files.

  IntrusiveRefCntPtr<InMemoryModuleCache> ModuleCache;

  /// Knows how to unwrap module containers.

  const PCHContainerReader &PCHContainerRdr;

  /// Preprocessor's HeaderSearchInfo containing the module map.

  const HeaderSearch &HeaderSearchInfo;

  /// A lookup of in-memory (virtual file) buffers

  llvm::DenseMap<const FileEntry *, std::unique_ptr<llvm::MemoryBuffer>>

      InMemoryBuffers;

  /// The visitation order.

  SmallVector<ModuleFile *, 4> VisitOrder;

  /// The list of module files that both we and the global module index

  /// know about.

  ///

  /// Either the global index or the module manager may have modules that the

  /// other does not know about, because the global index can be out-of-date

  /// (in which case the module manager could have modules it does not) and

  /// this particular translation unit might not have loaded all of the modules

  /// known to the global index.

  SmallVector<ModuleFile *, 4> ModulesInCommonWithGlobalIndex;

  /// The global module index, if one is attached.

  ///

  /// The global module index will actually be owned by the ASTReader; this is

  /// just an non-owning pointer.

  GlobalModuleIndex *GlobalIndex = nullptr;

  /// State used by the "visit" operation to avoid malloc traffic in

  /// calls to visit().

  struct VisitState {

    explicit VisitState(unsigned N) : VisitNumber(N, 0) {

      Stack.reserve(N);

    }

    /// The stack used when marking the imports of a particular module

    /// as not-to-be-visited.

    SmallVector<ModuleFile *, 4> Stack;

    /// The visit number of each module file, which indicates when

    /// this module file was last visited.

    SmallVector<unsigned, 4> VisitNumber;

    /// The next visit number to use to mark visited module files.

    unsigned NextVisitNumber = 1;

    /// The next visit state.

    std::unique_ptr<VisitState> NextState;

  };

  /// The first visit() state in the chain.

  std::unique_ptr<VisitState> FirstVisitState;

  std::unique_ptr<VisitState> allocateVisitState();

  void returnVisitState(std::unique_ptr<VisitState> State);

public:

  using ModuleIterator = llvm::pointee_iterator<

      SmallVectorImpl<std::unique_ptr<ModuleFile>>::iterator>;

  using ModuleConstIterator = llvm::pointee_iterator<

      SmallVectorImpl<std::unique_ptr<ModuleFile>>::const_iterator>;

  using ModuleReverseIterator = llvm::pointee_iterator<

      SmallVectorImpl<std::unique_ptr<ModuleFile>>::reverse_iterator>;

  using ModuleOffset = std::pair<uint32_t, StringRef>;

  explicit ModuleManager(FileManager &FileMgr, InMemoryModuleCache &ModuleCache,

                         const PCHContainerReader &PCHContainerRdr,

                         const HeaderSearch &HeaderSearchInfo);

  /// Forward iterator to traverse all loaded modules.

  ModuleIterator begin() { return Chain.begin(); }

  /// Forward iterator end-point to traverse all loaded modules

  ModuleIterator end() { return Chain.end(); }

  /// Const forward iterator to traverse all loaded modules.

  ModuleConstIterator begin() const { return Chain.begin(); }

  /// Const forward iterator end-point to traverse all loaded modules

  ModuleConstIterator end() const { return Chain.end(); }

  /// Reverse iterator to traverse all loaded modules.

  ModuleReverseIterator rbegin() { return Chain.rbegin(); }

  /// Reverse iterator end-point to traverse all loaded modules.

  ModuleReverseIterator rend() { return Chain.rend(); }

  /// A range covering the PCH and preamble module files loaded.

  llvm::iterator_range<SmallVectorImpl<ModuleFile *>::const_iterator>

  pch_modules() const {

    return llvm::make_range(PCHChain.begin(), PCHChain.end());

  }

  /// Returns the primary module associated with the manager, that is,

  /// the first module loaded

  ModuleFile &getPrimaryModule() { return *Chain[0]; }

  /// Returns the primary module associated with the manager, that is,

  /// the first module loaded.

  ModuleFile &getPrimaryModule() const { return *Chain[0]; }

  /// Returns the module associated with the given index

  ModuleFile &operator[](unsigned Index) const { return *Chain[Index]; }

  /// Returns the module associated with the given file name.

  ModuleFile *lookupByFileName(StringRef FileName) const;

  /// Returns the module associated with the given module name.

  ModuleFile *lookupByModuleName(StringRef ModName) const;

  /// Returns the module associated with the given module file.

  ModuleFile *lookup(const FileEntry *File) const;

  /// Returns the in-memory (virtual file) buffer with the given name

  std::unique_ptr<llvm::MemoryBuffer> lookupBuffer(StringRef Name);

  /// Number of modules loaded

  unsigned size() const { return Chain.size(); }

  /// The result of attempting to add a new module.

  enum AddModuleResult {

    /// The module file had already been loaded.

    AlreadyLoaded,

    /// The module file was just loaded in response to this call.

    NewlyLoaded,

    /// The module file is missing.

    Missing,

    /// The module file is out-of-date.

    OutOfDate

  };

  using ASTFileSignatureReader = ASTFileSignature (*)(StringRef);

  /// Attempts to create a new module and add it to the list of known

  /// modules.

  ///

  /// \param FileName The file name of the module to be loaded.

  ///

  /// \param Type The kind of module being loaded.

  ///

  /// \param ImportLoc The location at which the module is imported.

  ///

  /// \param ImportedBy The module that is importing this module, or NULL if

  /// this module is imported directly by the user.

  ///

  /// \param Generation The generation in which this module was loaded.

  ///

  /// \param ExpectedSize The expected size of the module file, used for

  /// validation. This will be zero if unknown.

  ///

  /// \param ExpectedModTime The expected modification time of the module

  /// file, used for validation. This will be zero if unknown.

  ///

  /// \param ExpectedSignature The expected signature of the module file, used

  /// for validation. This will be zero if unknown.

  ///

  /// \param ReadSignature Reads the signature from an AST file without actually

  /// loading it.

  ///

  /// \param Module A pointer to the module file if the module was successfully

  /// loaded.

  ///

  /// \param ErrorStr Will be set to a non-empty string if any errors occurred

  /// while trying to load the module.

  ///

  /// \return A pointer to the module that corresponds to this file name,

  /// and a value indicating whether the module was loaded.

  AddModuleResult addModule(StringRef FileName, ModuleKind Type,

                            SourceLocation ImportLoc,

                            ModuleFile *ImportedBy, unsigned Generation,

                            off_t ExpectedSize, time_t ExpectedModTime,

                            ASTFileSignature ExpectedSignature,

                            ASTFileSignatureReader ReadSignature,

                            ModuleFile *&Module,

                            std::string &ErrorStr);

  /// Remove the modules starting from First (to the end).

  void removeModules(ModuleIterator First, ModuleMap *modMap);

  /// Add an in-memory buffer the list of known buffers

  void addInMemoryBuffer(StringRef FileName,

                         std::unique_ptr<llvm::MemoryBuffer> Buffer);

  /// Set the global module index.

  void setGlobalIndex(GlobalModuleIndex *Index);

  /// Notification from the AST reader that the given module file

  /// has been "accepted", and will not (can not) be unloaded.

  void moduleFileAccepted(ModuleFile *MF);

  /// Visit each of the modules.

  ///

  /// This routine visits each of the modules, starting with the

  /// "root" modules that no other loaded modules depend on, and

  /// proceeding to the leaf modules, visiting each module only once

  /// during the traversal.

  ///

  /// This traversal is intended to support various "lookup"

  /// operations that can find data in any of the loaded modules.

  ///

  /// \param Visitor A visitor function that will be invoked with each

  /// module. The return value must be convertible to bool; when false, the

  /// visitation continues to modules that the current module depends on. When

  /// true, the visitation skips any modules that the current module depends on.

  ///

  /// \param ModuleFilesHit If non-NULL, contains the set of module files

  /// that we know we need to visit because the global module index told us to.

  /// Any module that is known to both the global module index and the module

  /// manager that is *not* in this set can be skipped.

  void visit(llvm::function_ref<bool(ModuleFile &M)> Visitor,

             llvm::SmallPtrSetImpl<ModuleFile *> *ModuleFilesHit = nullptr);

  /// Attempt to resolve the given module file name to a file entry.

  ///

  /// \param FileName The name of the module file.

  ///

  /// \param ExpectedSize The size that the module file is expected to have.

  /// If the actual size differs, the resolver should return \c true.

  ///

  /// \param ExpectedModTime The modification time that the module file is

  /// expected to have. If the actual modification time differs, the resolver

  /// should return \c true.

  ///

  /// \param File Will be set to the file if there is one, or null

  /// otherwise.

  ///

  /// \returns True if a file exists but does not meet the size/

  /// modification time criteria, false if the file is either available and

  /// suitable, or is missing.

  bool lookupModuleFile(StringRef FileName, off_t ExpectedSize,

                        time_t ExpectedModTime, Optional<FileEntryRef> &File);

  /// View the graphviz representation of the module graph.

  void viewGraph();

  InMemoryModuleCache &getModuleCache() const { return *ModuleCache; }

};

} // namespace serialization

} // namespace clang

#endif // LLVM_CLANG_SERIALIZATION_MODULEMANAGER_H