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CrossTranslationUnit.h
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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 
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 
25 namespace clang {
26 class CompilerInstance;
27 class ASTContext;
28 class ASTImporter;
29 class ASTUnit;
30 class DeclContext;
31 class FunctionDecl;
32 class VarDecl;
33 class NamedDecl;
34 class TranslationUnitDecl;
35 
36 namespace cross_tu {
37 
38 enum class index_error_code {
39  unspecified = 1,
51 };
52 
53 class IndexError : public llvm::ErrorInfo<IndexError> {
54 public:
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 
72 private:
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.
89 parseCrossTUIndex(StringRef IndexPath, StringRef CrossTUDir);
90 
91 std::string createCrossTUIndexString(const llvm::StringMap<std::string> &Index);
92 
93 // Returns true if the variable or any field of a record variable is const.
94 bool 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.
107 public:
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.
128  getCrossTUDefinition(const FunctionDecl *FD, StringRef CrossTUDir,
129  StringRef IndexName, bool DisplayCTUProgress = false);
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 
179 private:
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
Represents a function declaration or definition.
Definition: Decl.h:1784
Represents a variable declaration or definition.
Definition: Decl.h:827
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:160
Utility class for loading a ASTContext from an AST file.
Definition: ASTUnit.h:89
Definition: Format.h:2392
Forward-declares and imports various common LLVM datatypes that clang wants to use unqualified...
bool containsConst(const VarDecl *VD, const ASTContext &ACtx)
std::string createCrossTUIndexString(const llvm::StringMap< std::string > &Index)
#define bool
Definition: stdbool.h:15
llvm::Expected< llvm::StringMap< std::string > > parseCrossTUIndex(StringRef IndexPath, StringRef CrossTUDir)
This function parses an index file that determines which translation unit contains which definition...
#define log(__x)
Definition: tgmath.h:460
CompilerInstance - Helper class for managing a single instance of the Clang compiler.
Encodes a location in the source.
IndexError(index_error_code C, std::string FileName, std::string TripleToName, std::string TripleFromName)
Dataflow Directional Tag Classes.
DeclContext - This is used only as base class of specific decl types that can act as declaration cont...
Definition: DeclBase.h:1271
This class is used for tools that requires cross translation unit capability.
index_error_code getCode() const
Imports selected nodes from one AST context into another context, merging AST nodes where appropriate...
Definition: ASTImporter.h:84
IndexError(index_error_code C, std::string FileName, int LineNo=0)
The top declaration context.
Definition: Decl.h:107
This represents a decl that may have a name.
Definition: Decl.h:248
std::string getTripleToName() const
std::string getTripleFromName() const