//===--- CrossTranslationUnit.h - -------------------------------*- 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 provides an interface to load binary AST dumps on demand. This

//  feature can be utilized for tools that require cross translation unit

//  support.

//

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

#ifndef LLVM_CLANG_CROSSTU_CROSSTRANSLATIONUNIT_H

#define LLVM_CLANG_CROSSTU_CROSSTRANSLATIONUNIT_H

#include "clang/AST/ASTImporterSharedState.h"

#include "clang/Analysis/MacroExpansionContext.h"

#include "clang/Basic/LLVM.h"

#include "llvm/ADT/DenseMap.h"

#include "llvm/ADT/Optional.h"

#include "llvm/ADT/SmallPtrSet.h"

#include "llvm/ADT/StringMap.h"

#include "llvm/Support/Error.h"

#include "llvm/Support/Path.h"

namespace clang {

class CompilerInstance;

class ASTContext;

class ASTImporter;

class ASTUnit;

class DeclContext;

class FunctionDecl;

class VarDecl;

class NamedDecl;

class TranslationUnitDecl;

namespace cross_tu {

enum class index_error_code {

  success = 0,

  unspecified = 1,

  missing_index_file,

  invalid_index_format,

  multiple_definitions,

  missing_definition,

  failed_import,

  failed_to_get_external_ast,

  failed_to_generate_usr,

  triple_mismatch,

  lang_mismatch,

  lang_dialect_mismatch,

  load_threshold_reached,

  invocation_list_ambiguous,

  invocation_list_file_not_found,

  invocation_list_empty,

  invocation_list_wrong_format,

  invocation_list_lookup_unsuccessful

};

class IndexError : public llvm::ErrorInfo<IndexError> {

public:

  static char ID;

  IndexError(index_error_code C) : Code(C), LineNo(0) {}

  IndexError(index_error_code C, std::string FileName, int LineNo = 0)

      : Code(C), FileName(std::move(FileName)), LineNo(LineNo) {}

  IndexError(index_error_code C, std::string FileName, std::string TripleToName,

             std::string TripleFromName)

      : Code(C), FileName(std::move(FileName)),

        TripleToName(std::move(TripleToName)),

        TripleFromName(std::move(TripleFromName)) {}

  void log(raw_ostream &OS) const override;

  std::error_code convertToErrorCode() const override;

  index_error_code getCode() const { return Code; }

  int getLineNum() const { return LineNo; }

  std::string getFileName() const { return FileName; }

  std::string getTripleToName() const { return TripleToName; }

  std::string getTripleFromName() const { return TripleFromName; }

private:

  index_error_code Code;

  std::string FileName;

  int LineNo;

  std::string TripleToName;

  std::string TripleFromName;

};

/// This function parses an index file that determines which

/// translation unit contains which definition. The IndexPath is not prefixed

/// with CTUDir, so an absolute path is expected for consistent results.

///

/// The index file format is the following:

/// each line consists of an USR and a filepath separated by a space.

///

/// \return Returns a map where the USR is the key and the filepath is the value

///         or an error.

llvm::Expected<llvm::StringMap<std::string>>

parseCrossTUIndex(StringRef IndexPath);

std::string createCrossTUIndexString(const llvm::StringMap<std::string> &Index);

using InvocationListTy = llvm::StringMap<llvm::SmallVector<std::string, 32>>;

/// Parse the YAML formatted invocation list file content \p FileContent.

/// The format is expected to be a mapping from from absolute source file

/// paths in the filesystem to a list of command-line parts, which

/// constitute the invocation needed to compile that file. That invocation

/// will be used to produce the AST of the TU.

llvm::Expected<InvocationListTy> parseInvocationList(

    StringRef FileContent,

    llvm::sys::path::Style PathStyle = llvm::sys::path::Style::posix);

/// Returns true if it makes sense to import a foreign variable definition.

/// For instance, we don't want to import variables that have non-trivial types

/// because the constructor might have side-effects.

bool shouldImport(const VarDecl *VD, const ASTContext &ACtx);

/// This class is used for tools that requires cross translation

///        unit capability.

///

/// This class can load definitions from external AST sources.

/// The loaded definition will be merged back to the original AST using the

/// AST Importer.

/// In order to use this class, an index file is required that describes

/// the locations of the AST files for each definition.

///

/// Note that this class also implements caching.

class CrossTranslationUnitContext {

public:

  CrossTranslationUnitContext(CompilerInstance &CI);

  ~CrossTranslationUnitContext();

  /// This function loads a function or variable definition from an

  ///        external AST file and merges it into the original AST.

  ///

  /// This method should only be used on functions that have no definitions or

  /// variables that have no initializer in

  /// the current translation unit. A function definition with the same

  /// declaration will be looked up in the index file which should be in the

  /// \p CrossTUDir directory, called \p IndexName. In case the declaration is

  /// found in the index the corresponding AST will be loaded and the

  /// definition will be merged into the original AST using the AST Importer.

  ///

  /// \return The declaration with the definition will be returned.

  /// If no suitable definition is found in the index file or multiple

  /// definitions found error will be returned.

  ///

  /// Note that the AST files should also be in the \p CrossTUDir.

  llvm::Expected<const FunctionDecl *>

  getCrossTUDefinition(const FunctionDecl *FD, StringRef CrossTUDir,

                       StringRef IndexName, bool DisplayCTUProgress = false);

  llvm::Expected<const VarDecl *>

  getCrossTUDefinition(const VarDecl *VD, StringRef CrossTUDir,

                       StringRef IndexName, bool DisplayCTUProgress = false);

  /// This function loads a definition from an external AST file.

  ///

  /// A definition with the same declaration will be looked up in the

  /// index file which should be in the \p CrossTUDir directory, called

  /// \p IndexName. In case the declaration is found in the index the

  /// corresponding AST will be loaded. If the number of TUs imported

  /// reaches \p CTULoadTreshold, no loading is performed.

  ///

  /// \return Returns a pointer to the ASTUnit that contains the definition of

  /// the looked up name or an Error.

  /// The returned pointer is never a nullptr.

  ///

  /// Note that the AST files should also be in the \p CrossTUDir.

  llvm::Expected<ASTUnit *> loadExternalAST(StringRef LookupName,

                                            StringRef CrossTUDir,

                                            StringRef IndexName,

                                            bool DisplayCTUProgress = false);

  /// This function merges a definition from a separate AST Unit into

  ///        the current one which was created by the compiler instance that

  ///        was passed to the constructor.

  ///

  /// \return Returns the resulting definition or an error.

  llvm::Expected<const FunctionDecl *> importDefinition(const FunctionDecl *FD,

                                                        ASTUnit *Unit);

  llvm::Expected<const VarDecl *> importDefinition(const VarDecl *VD,

                                                   ASTUnit *Unit);

  /// Get a name to identify a named decl.

  static llvm::Optional<std::string> getLookupName(const NamedDecl *ND);

  /// Emit diagnostics for the user for potential configuration errors.

  void emitCrossTUDiagnostics(const IndexError &IE);

  /// Returns the MacroExpansionContext for the imported TU to which the given

  /// source-location corresponds.

  /// \p ToLoc Source location in the imported-to AST.

  /// \note If any error happens such as \p ToLoc is a non-imported

  ///       source-location, empty is returned.

  /// \note Macro expansion tracking for imported TUs is not implemented yet.

  ///       It returns empty unconditionally.

  llvm::Optional<clang::MacroExpansionContext>

  getMacroExpansionContextForSourceLocation(

      const clang::SourceLocation &ToLoc) const;

private:

  void lazyInitImporterSharedSt(TranslationUnitDecl *ToTU);

  ASTImporter &getOrCreateASTImporter(ASTUnit *Unit);

  template <typename T>

  llvm::Expected<const T *> getCrossTUDefinitionImpl(const T *D,

                                                     StringRef CrossTUDir,

                                                     StringRef IndexName,

                                                     bool DisplayCTUProgress);

  template <typename T>

  const T *findDefInDeclContext(const DeclContext *DC,

                                StringRef LookupName);

  template <typename T>

  llvm::Expected<const T *> importDefinitionImpl(const T *D, ASTUnit *Unit);

  using ImporterMapTy =

      llvm::DenseMap<TranslationUnitDecl *, std::unique_ptr<ASTImporter>>;

  ImporterMapTy ASTUnitImporterMap;

  ASTContext &Context;

  std::shared_ptr<ASTImporterSharedState> ImporterSharedSt;

  using LoadResultTy = llvm::Expected<std::unique_ptr<ASTUnit>>;

  /// Loads ASTUnits from AST-dumps or source-files.

  class ASTLoader {

  public:

    ASTLoader(CompilerInstance &CI, StringRef CTUDir,

              StringRef InvocationListFilePath);

    /// Load the ASTUnit by its identifier found in the index file. If the

    /// identifier is suffixed with '.ast' it is considered a dump. Otherwise

    /// it is treated as source-file, and on-demand parsed. Relative paths are

    /// prefixed with CTUDir.

    LoadResultTy load(StringRef Identifier);

    /// Lazily initialize the invocation list information, which is needed for

    /// on-demand parsing.

    llvm::Error lazyInitInvocationList();

  private:

    /// The style used for storage and lookup of filesystem paths.

    /// Defaults to posix.

    const llvm::sys::path::Style PathStyle = llvm::sys::path::Style::posix;

    /// Loads an AST from a pch-dump.

    LoadResultTy loadFromDump(StringRef Identifier);

    /// Loads an AST from a source-file.

    LoadResultTy loadFromSource(StringRef Identifier);

    CompilerInstance &CI;

    StringRef CTUDir;

    /// The path to the file containing the invocation list, which is in YAML

    /// format, and contains a mapping from source files to compiler invocations

    /// that produce the AST used for analysis.

    StringRef InvocationListFilePath;

    /// In case of on-demand parsing, the invocations for parsing the source

    /// files is stored.

    llvm::Optional<InvocationListTy> InvocationList;

    index_error_code PreviousParsingResult = index_error_code::success;

  };

  /// Maintain number of AST loads and check for reaching the load limit.

  class ASTLoadGuard {

  public:

    ASTLoadGuard(unsigned Limit) : Limit(Limit) {}

    /// Indicates, whether a new load operation is permitted, it is within the

    /// threshold.

    operator bool() const { return Count < Limit; }

    /// Tell that a new AST was loaded successfully.

    void indicateLoadSuccess() { ++Count; }

  private:

    /// The number of ASTs actually imported.

    unsigned Count{0u};

    /// The limit (threshold) value for number of loaded ASTs.

    const unsigned Limit;

  };

  /// Storage and load of ASTUnits, cached access, and providing searchability

  /// are the concerns of ASTUnitStorage class.

  class ASTUnitStorage {

  public:

    ASTUnitStorage(CompilerInstance &CI);

    /// Loads an ASTUnit for a function.

    ///

    /// \param FunctionName USR name of the function.

    /// \param CrossTUDir Path to the directory used to store CTU related files.

    /// \param IndexName Name of the file inside \p CrossTUDir which maps

    /// function USR names to file paths. These files contain the corresponding

    /// AST-dumps.

    /// \param DisplayCTUProgress Display a message about loading new ASTs.

    ///

    /// \return An Expected instance which contains the ASTUnit pointer or the

    /// error occurred during the load.

    llvm::Expected<ASTUnit *> getASTUnitForFunction(StringRef FunctionName,

                                                    StringRef CrossTUDir,

                                                    StringRef IndexName,

                                                    bool DisplayCTUProgress);

    /// Identifies the path of the file which can be used to load the ASTUnit

    /// for a given function.

    ///

    /// \param FunctionName USR name of the function.

    /// \param CrossTUDir Path to the directory used to store CTU related files.

    /// \param IndexName Name of the file inside \p CrossTUDir which maps

    /// function USR names to file paths. These files contain the corresponding

    /// AST-dumps.

    ///

    /// \return An Expected instance containing the filepath.

    llvm::Expected<std::string> getFileForFunction(StringRef FunctionName,

                                                   StringRef CrossTUDir,

                                                   StringRef IndexName);

  private:

    llvm::Error ensureCTUIndexLoaded(StringRef CrossTUDir, StringRef IndexName);

    llvm::Expected<ASTUnit *> getASTUnitForFile(StringRef FileName,

                                                bool DisplayCTUProgress);

    template <typename... T> using BaseMapTy = llvm::StringMap<T...>;

    using OwningMapTy = BaseMapTy<std::unique_ptr<clang::ASTUnit>>;

    using NonOwningMapTy = BaseMapTy<clang::ASTUnit *>;

    OwningMapTy FileASTUnitMap;

    NonOwningMapTy NameASTUnitMap;

    using IndexMapTy = BaseMapTy<std::string>;

    IndexMapTy NameFileMap;

    /// Loads the AST based on the identifier found in the index.

    ASTLoader Loader;

    /// Limit the number of loaded ASTs. It is used to limit the  memory usage

    /// of the CrossTranslationUnitContext. The ASTUnitStorage has the

    /// information whether the AST to load is actually loaded or returned from

    /// cache. This information is needed to maintain the counter.

    ASTLoadGuard LoadGuard;

  };

  ASTUnitStorage ASTStorage;

};

} // namespace cross_tu

} // namespace clang

#endif // LLVM_CLANG_CROSSTU_CROSSTRANSLATIONUNIT_H