CrossTranslationUnit.h revision 360784 
1//===--- CrossTranslationUnit.h - -------------------------------*- 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//  This file provides an interface to load binary AST dumps on demand. This
10//  feature can be utilized for tools that require cross translation unit
11//  support.
12//
13//===----------------------------------------------------------------------===//
14#ifndef LLVM_CLANG_CROSSTU_CROSSTRANSLATIONUNIT_H
15#define LLVM_CLANG_CROSSTU_CROSSTRANSLATIONUNIT_H
16
17#include "clang/AST/ASTImporterSharedState.h"
18#include "clang/Basic/LLVM.h"
19#include "llvm/ADT/DenseMap.h"
20#include "llvm/ADT/Optional.h"
21#include "llvm/ADT/SmallPtrSet.h"
22#include "llvm/ADT/StringMap.h"
23#include "llvm/Support/Error.h"
24
25namespace clang {
26class CompilerInstance;
27class ASTContext;
28class ASTImporter;
29class ASTUnit;
30class DeclContext;
31class FunctionDecl;
32class VarDecl;
33class NamedDecl;
34class TranslationUnitDecl;
35
36namespace cross_tu {
37
38enum class index_error_code {
39  unspecified = 1,
40  missing_index_file,
41  invalid_index_format,
42  multiple_definitions,
43  missing_definition,
44  failed_import,
45  failed_to_get_external_ast,
46  failed_to_generate_usr,
47  triple_mismatch,
48  lang_mismatch,
49  lang_dialect_mismatch,
50  load_threshold_reached
51};
52
53class IndexError : public llvm::ErrorInfo<IndexError> {
54public:
55  static char ID;
56  IndexError(index_error_code C) : Code(C), LineNo(0) {}
57  IndexError(index_error_code C, std::string FileName, int LineNo = 0)
58      : Code(C), FileName(std::move(FileName)), LineNo(LineNo) {}
59  IndexError(index_error_code C, std::string FileName, std::string TripleToName,
60             std::string TripleFromName)
61      : Code(C), FileName(std::move(FileName)),
62        TripleToName(std::move(TripleToName)),
63        TripleFromName(std::move(TripleFromName)) {}
64  void log(raw_ostream &OS) const override;
65  std::error_code convertToErrorCode() const override;
66  index_error_code getCode() const { return Code; }
67  int getLineNum() const { return LineNo; }
68  std::string getFileName() const { return FileName; }
69  std::string getTripleToName() const { return TripleToName; }
70  std::string getTripleFromName() const { return TripleFromName; }
71
72private:
73  index_error_code Code;
74  std::string FileName;
75  int LineNo;
76  std::string TripleToName;
77  std::string TripleFromName;
78};
79
80/// This function parses an index file that determines which
81///        translation unit contains which definition.
82///
83/// The index file format is the following:
84/// each line consists of an USR and a filepath separated by a space.
85///
86/// \return Returns a map where the USR is the key and the filepath is the value
87///         or an error.
88llvm::Expected<llvm::StringMap<std::string>>
89parseCrossTUIndex(StringRef IndexPath, StringRef CrossTUDir);
90
91std::string createCrossTUIndexString(const llvm::StringMap<std::string> &Index);
92
93// Returns true if the variable or any field of a record variable is const.
94bool containsConst(const VarDecl *VD, const ASTContext &ACtx);
95
96/// This class is used for tools that requires cross translation
97///        unit capability.
98///
99/// This class can load definitions from external AST files.
100/// The loaded definition will be merged back to the original AST using the
101/// AST Importer.
102/// In order to use this class, an index file is required that describes
103/// the locations of the AST files for each definition.
104///
105/// Note that this class also implements caching.
106class CrossTranslationUnitContext {
107public:
108  CrossTranslationUnitContext(CompilerInstance &CI);
109  ~CrossTranslationUnitContext();
110
111  /// This function loads a function or variable definition from an
112  ///        external AST file and merges it into the original AST.
113  ///
114  /// This method should only be used on functions that have no definitions or
115  /// variables that have no initializer in
116  /// the current translation unit. A function definition with the same
117  /// declaration will be looked up in the index file which should be in the
118  /// \p CrossTUDir directory, called \p IndexName. In case the declaration is
119  /// found in the index the corresponding AST file will be loaded and the
120  /// definition will be merged into the original AST using the AST Importer.
121  ///
122  /// \return The declaration with the definition will be returned.
123  /// If no suitable definition is found in the index file or multiple
124  /// definitions found error will be returned.
125  ///
126  /// Note that the AST files should also be in the \p CrossTUDir.
127  llvm::Expected<const FunctionDecl *>
128  getCrossTUDefinition(const FunctionDecl *FD, StringRef CrossTUDir,
129                       StringRef IndexName, bool DisplayCTUProgress = false);
130  llvm::Expected<const VarDecl *>
131  getCrossTUDefinition(const VarDecl *VD, StringRef CrossTUDir,
132                       StringRef IndexName, bool DisplayCTUProgress = false);
133
134  /// This function loads a definition from an external AST file.
135  ///
136  /// A definition with the same declaration will be looked up in the
137  /// index file which should be in the \p CrossTUDir directory, called
138  /// \p IndexName. In case the declaration is found in the index the
139  /// corresponding AST file will be loaded. If the number of TUs imported
140  /// reaches \p CTULoadTreshold, no loading is performed.
141  ///
142  /// \return Returns a pointer to the ASTUnit that contains the definition of
143  /// the looked up name or an Error.
144  /// The returned pointer is never a nullptr.
145  ///
146  /// Note that the AST files should also be in the \p CrossTUDir.
147  llvm::Expected<ASTUnit *> loadExternalAST(StringRef LookupName,
148                                            StringRef CrossTUDir,
149                                            StringRef IndexName,
150                                            bool DisplayCTUProgress = false);
151
152  /// This function merges a definition from a separate AST Unit into
153  ///        the current one which was created by the compiler instance that
154  ///        was passed to the constructor.
155  ///
156  /// \return Returns the resulting definition or an error.
157  llvm::Expected<const FunctionDecl *> importDefinition(const FunctionDecl *FD,
158                                                        ASTUnit *Unit);
159  llvm::Expected<const VarDecl *> importDefinition(const VarDecl *VD,
160                                                   ASTUnit *Unit);
161
162  /// Get a name to identify a named decl.
163  static llvm::Optional<std::string> getLookupName(const NamedDecl *ND);
164
165  /// Emit diagnostics for the user for potential configuration errors.
166  void emitCrossTUDiagnostics(const IndexError &IE);
167
168  /// Determine the original source location in the original TU for an
169  /// imported source location.
170  /// \p ToLoc Source location in the imported-to AST.
171  /// \return Source location in the imported-from AST and the corresponding
172  /// ASTUnit object (the AST was loaded from a file using an internal ASTUnit
173  /// object that is returned here).
174  /// If any error happens (ToLoc is a non-imported source location) empty is
175  /// returned.
176  llvm::Optional<std::pair<SourceLocation /*FromLoc*/, ASTUnit *>>
177  getImportedFromSourceLocation(const clang::SourceLocation &ToLoc) const;
178
179private:
180  using ImportedFileIDMap =
181      llvm::DenseMap<FileID, std::pair<FileID, ASTUnit *>>;
182
183  void lazyInitImporterSharedSt(TranslationUnitDecl *ToTU);
184  ASTImporter &getOrCreateASTImporter(ASTUnit *Unit);
185  template <typename T>
186  llvm::Expected<const T *> getCrossTUDefinitionImpl(const T *D,
187                                                     StringRef CrossTUDir,
188                                                     StringRef IndexName,
189                                                     bool DisplayCTUProgress);
190  template <typename T>
191  const T *findDefInDeclContext(const DeclContext *DC,
192                                StringRef LookupName);
193  template <typename T>
194  llvm::Expected<const T *> importDefinitionImpl(const T *D, ASTUnit *Unit);
195
196  using ImporterMapTy =
197      llvm::DenseMap<TranslationUnitDecl *, std::unique_ptr<ASTImporter>>;
198
199  ImporterMapTy ASTUnitImporterMap;
200
201  ASTContext &Context;
202  std::shared_ptr<ASTImporterSharedState> ImporterSharedSt;
203  /// Map of imported FileID's (in "To" context) to FileID in "From" context
204  /// and the ASTUnit for the From context.
205  /// This map is used by getImportedFromSourceLocation to lookup a FileID and
206  /// its Preprocessor when knowing only the FileID in the 'To' context. The
207  /// FileID could be imported by any of multiple 'From' ASTImporter objects.
208  /// we do not want to loop over all ASTImporter's to find the one that
209  /// imported the FileID.
210  ImportedFileIDMap ImportedFileIDs;
211
212  /// Functor for loading ASTUnits from AST-dump files.
213  class ASTFileLoader {
214  public:
215    ASTFileLoader(const CompilerInstance &CI);
216    std::unique_ptr<ASTUnit> operator()(StringRef ASTFilePath);
217
218  private:
219    const CompilerInstance &CI;
220  };
221
222  /// Maintain number of AST loads and check for reaching the load limit.
223  class ASTLoadGuard {
224  public:
225    ASTLoadGuard(unsigned Limit) : Limit(Limit) {}
226
227    /// Indicates, whether a new load operation is permitted, it is within the
228    /// threshold.
229    operator bool() const { return Count < Limit; }
230
231    /// Tell that a new AST was loaded successfully.
232    void indicateLoadSuccess() { ++Count; }
233
234  private:
235    /// The number of ASTs actually imported.
236    unsigned Count{0u};
237    /// The limit (threshold) value for number of loaded ASTs.
238    const unsigned Limit;
239  };
240
241  /// Storage and load of ASTUnits, cached access, and providing searchability
242  /// are the concerns of ASTUnitStorage class.
243  class ASTUnitStorage {
244  public:
245    ASTUnitStorage(const CompilerInstance &CI);
246    /// Loads an ASTUnit for a function.
247    ///
248    /// \param FunctionName USR name of the function.
249    /// \param CrossTUDir Path to the directory used to store CTU related files.
250    /// \param IndexName Name of the file inside \p CrossTUDir which maps
251    /// function USR names to file paths. These files contain the corresponding
252    /// AST-dumps.
253    /// \param DisplayCTUProgress Display a message about loading new ASTs.
254    ///
255    /// \return An Expected instance which contains the ASTUnit pointer or the
256    /// error occured during the load.
257    llvm::Expected<ASTUnit *> getASTUnitForFunction(StringRef FunctionName,
258                                                    StringRef CrossTUDir,
259                                                    StringRef IndexName,
260                                                    bool DisplayCTUProgress);
261    /// Identifies the path of the file which can be used to load the ASTUnit
262    /// for a given function.
263    ///
264    /// \param FunctionName USR name of the function.
265    /// \param CrossTUDir Path to the directory used to store CTU related files.
266    /// \param IndexName Name of the file inside \p CrossTUDir which maps
267    /// function USR names to file paths. These files contain the corresponding
268    /// AST-dumps.
269    ///
270    /// \return An Expected instance containing the filepath.
271    llvm::Expected<std::string> getFileForFunction(StringRef FunctionName,
272                                                   StringRef CrossTUDir,
273                                                   StringRef IndexName);
274
275  private:
276    llvm::Error ensureCTUIndexLoaded(StringRef CrossTUDir, StringRef IndexName);
277    llvm::Expected<ASTUnit *> getASTUnitForFile(StringRef FileName,
278                                                bool DisplayCTUProgress);
279
280    template <typename... T> using BaseMapTy = llvm::StringMap<T...>;
281    using OwningMapTy = BaseMapTy<std::unique_ptr<clang::ASTUnit>>;
282    using NonOwningMapTy = BaseMapTy<clang::ASTUnit *>;
283
284    OwningMapTy FileASTUnitMap;
285    NonOwningMapTy NameASTUnitMap;
286
287    using IndexMapTy = BaseMapTy<std::string>;
288    IndexMapTy NameFileMap;
289
290    ASTFileLoader FileAccessor;
291
292    /// Limit the number of loaded ASTs. Used to limit the  memory usage of the
293    /// CrossTranslationUnitContext.
294    /// The ASTUnitStorage has the knowledge about if the AST to load is
295    /// actually loaded or returned from cache. This information is needed to
296    /// maintain the counter.
297    ASTLoadGuard LoadGuard;
298  };
299
300  ASTUnitStorage ASTStorage;
301
302};
303
304} // namespace cross_tu
305} // namespace clang
306
307#endif // LLVM_CLANG_CROSSTU_CROSSTRANSLATIONUNIT_H
308