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GlobalModuleIndex.h
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1 //===--- GlobalModuleIndex.h - Global Module Index --------------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines the GlobalModuleIndex class, which manages a global index
11 // containing all of the identifiers known to the various modules within a given
12 // subdirectory of the module cache. It is used to improve the performance of
13 // queries such as "do any modules know about this identifier?"
14 //
15 //===----------------------------------------------------------------------===//
16 #ifndef LLVM_CLANG_SERIALIZATION_GLOBALMODULEINDEX_H
17 #define LLVM_CLANG_SERIALIZATION_GLOBALMODULEINDEX_H
18 
19 #include "llvm/ADT/DenseMap.h"
20 #include "llvm/ADT/SmallPtrSet.h"
21 #include "llvm/ADT/SmallVector.h"
22 #include "llvm/ADT/StringMap.h"
23 #include "llvm/ADT/StringRef.h"
24 #include <memory>
25 #include <utility>
26 
27 namespace llvm {
28 class BitstreamCursor;
29 class MemoryBuffer;
30 }
31 
32 namespace clang {
33 
34 class DirectoryEntry;
35 class FileEntry;
36 class FileManager;
37 class IdentifierIterator;
38 class PCHContainerOperations;
39 class PCHContainerReader;
40 
41 namespace serialization {
42  class ModuleFile;
43 }
44 
45 using llvm::SmallVector;
47 using llvm::StringRef;
48 using serialization::ModuleFile;
49 
50 /// \brief A global index for a set of module files, providing information about
51 /// the identifiers within those module files.
52 ///
53 /// The global index is an aid for name lookup into modules, offering a central
54 /// place where one can look for identifiers determine which
55 /// module files contain any information about that identifier. This
56 /// allows the client to restrict the search to only those module files known
57 /// to have a information about that identifier, improving performance. Moreover,
58 /// the global module index may know about module files that have not been
59 /// imported, and can be queried to determine which modules the current
60 /// translation could or should load to fix a problem.
62  /// \brief Buffer containing the index file, which is lazily accessed so long
63  /// as the global module index is live.
64  std::unique_ptr<llvm::MemoryBuffer> Buffer;
65 
66  /// \brief The hash table.
67  ///
68  /// This pointer actually points to a IdentifierIndexTable object,
69  /// but that type is only accessible within the implementation of
70  /// GlobalModuleIndex.
71  void *IdentifierIndex;
72 
73  /// \brief Information about a given module file.
74  struct ModuleInfo {
75  ModuleInfo() : File(), Size(), ModTime() { }
76 
77  /// \brief The module file, once it has been resolved.
78  ModuleFile *File;
79 
80  /// \brief The module file name.
81  std::string FileName;
82 
83  /// \brief Size of the module file at the time the global index was built.
84  off_t Size;
85 
86  /// \brief Modification time of the module file at the time the global
87  /// index was built.
88  time_t ModTime;
89 
90  /// \brief The module IDs on which this module directly depends.
91  /// FIXME: We don't really need a vector here.
92  llvm::SmallVector<unsigned, 4> Dependencies;
93  };
94 
95  /// \brief A mapping from module IDs to information about each module.
96  ///
97  /// This vector may have gaps, if module files have been removed or have
98  /// been updated since the index was built. A gap is indicated by an empty
99  /// file name.
101 
102  /// \brief Lazily-populated mapping from module files to their
103  /// corresponding index into the \c Modules vector.
104  llvm::DenseMap<ModuleFile *, unsigned> ModulesByFile;
105 
106  /// \brief The set of modules that have not yet been resolved.
107  ///
108  /// The string is just the name of the module itself, which maps to the
109  /// module ID.
110  llvm::StringMap<unsigned> UnresolvedModules;
111 
112  /// \brief The number of identifier lookups we performed.
113  unsigned NumIdentifierLookups;
114 
115  /// \brief The number of identifier lookup hits, where we recognize the
116  /// identifier.
117  unsigned NumIdentifierLookupHits;
118 
119  /// \brief Internal constructor. Use \c readIndex() to read an index.
120  explicit GlobalModuleIndex(std::unique_ptr<llvm::MemoryBuffer> Buffer,
121  llvm::BitstreamCursor Cursor);
122 
123  GlobalModuleIndex(const GlobalModuleIndex &) = delete;
124  GlobalModuleIndex &operator=(const GlobalModuleIndex &) = delete;
125 
126 public:
128 
129  /// \brief An error code returned when trying to read an index.
130  enum ErrorCode {
131  /// \brief No error occurred.
133  /// \brief No index was found.
135  /// \brief Some other process is currently building the index; it is not
136  /// available yet.
138  /// \brief There was an unspecified I/O error reading or writing the index.
139  EC_IOError
140  };
141 
142  /// \brief Read a global index file for the given directory.
143  ///
144  /// \param Path The path to the specific module cache where the module files
145  /// for the intended configuration reside.
146  ///
147  /// \returns A pair containing the global module index (if it exists) and
148  /// the error code.
149  static std::pair<GlobalModuleIndex *, ErrorCode>
150  readIndex(StringRef Path);
151 
152  /// \brief Returns an iterator for identifiers stored in the index table.
153  ///
154  /// The caller accepts ownership of the returned object.
155  IdentifierIterator *createIdentifierIterator() const;
156 
157  /// \brief Retrieve the set of modules that have up-to-date indexes.
158  ///
159  /// \param ModuleFiles Will be populated with the set of module files that
160  /// have been indexed.
161  void getKnownModules(SmallVectorImpl<ModuleFile *> &ModuleFiles);
162 
163  /// \brief Retrieve the set of module files on which the given module file
164  /// directly depends.
165  void getModuleDependencies(ModuleFile *File,
166  SmallVectorImpl<ModuleFile *> &Dependencies);
167 
168  /// \brief A set of module files in which we found a result.
169  typedef llvm::SmallPtrSet<ModuleFile *, 4> HitSet;
170 
171  /// \brief Look for all of the module files with information about the given
172  /// identifier, e.g., a global function, variable, or type with that name.
173  ///
174  /// \param Name The identifier to look for.
175  ///
176  /// \param Hits Will be populated with the set of module files that have
177  /// information about this name.
178  ///
179  /// \returns true if the identifier is known to the index, false otherwise.
180  bool lookupIdentifier(StringRef Name, HitSet &Hits);
181 
182  /// \brief Note that the given module file has been loaded.
183  ///
184  /// \returns false if the global module index has information about this
185  /// module file, and true otherwise.
186  bool loadedModuleFile(ModuleFile *File);
187 
188  /// \brief Print statistics to standard error.
189  void printStats();
190 
191  /// \brief Print debugging view to standard error.
192  void dump();
193 
194  /// \brief Write a global index into the given
195  ///
196  /// \param FileMgr The file manager to use to load module files.
197  /// \param PCHContainerRdr - The PCHContainerOperations to use for loading and
198  /// creating modules.
199  /// \param Path The path to the directory containing module files, into
200  /// which the global index will be written.
201  static ErrorCode writeIndex(FileManager &FileMgr,
202  const PCHContainerReader &PCHContainerRdr,
203  StringRef Path);
204 };
205 }
206 
207 #endif
Implements support for file system lookup, file system caching, and directory search management...
Definition: FileManager.h:116
DominatorTree GraphTraits specialization so the DominatorTree can be iterable by generic graph iterat...
Definition: Dominators.h:26
llvm::SmallPtrSet< ModuleFile *, 4 > HitSet
A set of module files in which we found a result.
static void dump(llvm::raw_ostream &OS, StringRef FunctionName, ArrayRef< CounterExpression > Expressions, ArrayRef< CounterMappingRegion > Regions)
ErrorCode
An error code returned when trying to read an index.
This abstract interface provides operations for unwrapping containers for serialized ASTs (precompile...
Information about a module that has been loaded by the ASTReader.
Definition: Module.h:100
An iterator that walks over all of the known identifiers in the lookup table.
A global index for a set of module files, providing information about the identifiers within those mo...
Dataflow Directional Tag Classes.
Some other process is currently building the index; it is not available yet.