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