1 //===--- GlobalModuleIndex.h - Global Module Index --------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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?"
15 //===----------------------------------------------------------------------===//
16 #ifndef LLVM_CLANG_SERIALIZATION_GLOBAL_MODULE_INDEX_H
17 #define LLVM_CLANG_SERIALIZATION_GLOBAL_MODULE_INDEX_H
19 #include "llvm/ADT/DenseMap.h"
20 #include "llvm/ADT/OwningPtr.h"
21 #include "llvm/ADT/SmallPtrSet.h"
22 #include "llvm/ADT/SmallVector.h"
23 #include "llvm/ADT/StringMap.h"
24 #include "llvm/ADT/StringRef.h"
28 class BitstreamCursor;
37 class IdentifierIterator;
39 namespace serialization {
43 using llvm::SmallVector;
44 using llvm::SmallVectorImpl;
45 using llvm::StringRef;
46 using serialization::ModuleFile;
48 /// \brief A global index for a set of module files, providing information about
49 /// the identifiers within those module files.
51 /// The global index is an aid for name lookup into modules, offering a central
52 /// place where one can look for identifiers determine which
53 /// module files contain any information about that identifier. This
54 /// allows the client to restrict the search to only those module files known
55 /// to have a information about that identifier, improving performance. Moreover,
56 /// the global module index may know about module files that have not been
57 /// imported, and can be queried to determine which modules the current
58 /// translation could or should load to fix a problem.
59 class GlobalModuleIndex {
60 /// \brief Buffer containing the index file, which is lazily accessed so long
61 /// as the global module index is live.
62 llvm::OwningPtr<llvm::MemoryBuffer> Buffer;
64 /// \brief The hash table.
66 /// This pointer actually points to a IdentifierIndexTable object,
67 /// but that type is only accessible within the implementation of
68 /// GlobalModuleIndex.
69 void *IdentifierIndex;
71 /// \brief Information about a given module file.
73 ModuleInfo() : File(), Size(), ModTime() { }
75 /// \brief The module file, once it has been resolved.
78 /// \brief The module file name.
81 /// \brief Size of the module file at the time the global index was built.
84 /// \brief Modification time of the module file at the time the global
88 /// \brief The module IDs on which this module directly depends.
89 /// FIXME: We don't really need a vector here.
90 llvm::SmallVector<unsigned, 4> Dependencies;
93 /// \brief A mapping from module IDs to information about each module.
95 /// This vector may have gaps, if module files have been removed or have
96 /// been updated since the index was built. A gap is indicated by an empty
98 llvm::SmallVector<ModuleInfo, 16> Modules;
100 /// \brief Lazily-populated mapping from module files to their
101 /// corresponding index into the \c Modules vector.
102 llvm::DenseMap<ModuleFile *, unsigned> ModulesByFile;
104 /// \brief The set of modules that have not yet been resolved.
106 /// The string is just the name of the module itself, which maps to the
108 llvm::StringMap<unsigned> UnresolvedModules;
110 /// \brief The number of identifier lookups we performed.
111 unsigned NumIdentifierLookups;
113 /// \brief The number of identifier lookup hits, where we recognize the
115 unsigned NumIdentifierLookupHits;
117 /// \brief Internal constructor. Use \c readIndex() to read an index.
118 explicit GlobalModuleIndex(llvm::MemoryBuffer *Buffer,
119 llvm::BitstreamCursor Cursor);
121 GlobalModuleIndex(const GlobalModuleIndex &) LLVM_DELETED_FUNCTION;
122 GlobalModuleIndex &operator=(const GlobalModuleIndex &) LLVM_DELETED_FUNCTION;
125 ~GlobalModuleIndex();
127 /// \brief An error code returned when trying to read an index.
129 /// \brief No error occurred.
131 /// \brief No index was found.
133 /// \brief Some other process is currently building the index; it is not
136 /// \brief There was an unspecified I/O error reading or writing the index.
140 /// \brief Read a global index file for the given directory.
142 /// \param Path The path to the specific module cache where the module files
143 /// for the intended configuration reside.
145 /// \returns A pair containing the global module index (if it exists) and
147 static std::pair<GlobalModuleIndex *, ErrorCode>
148 readIndex(StringRef Path);
150 /// \brief Returns an iterator for identifiers stored in the index table.
152 /// The caller accepts ownership of the returned object.
153 IdentifierIterator *createIdentifierIterator() const;
155 /// \brief Retrieve the set of modules that have up-to-date indexes.
157 /// \param ModuleFiles Will be populated with the set of module files that
158 /// have been indexed.
159 void getKnownModules(SmallVectorImpl<ModuleFile *> &ModuleFiles);
161 /// \brief Retrieve the set of module files on which the given module file
162 /// directly depends.
163 void getModuleDependencies(ModuleFile *File,
164 SmallVectorImpl<ModuleFile *> &Dependencies);
166 /// \brief A set of module files in which we found a result.
167 typedef llvm::SmallPtrSet<ModuleFile *, 4> HitSet;
169 /// \brief Look for all of the module files with information about the given
170 /// identifier, e.g., a global function, variable, or type with that name.
172 /// \param Name The identifier to look for.
174 /// \param Hits Will be populated with the set of module files that have
175 /// information about this name.
177 /// \returns true if the identifier is known to the index, false otherwise.
178 bool lookupIdentifier(StringRef Name, HitSet &Hits);
180 /// \brief Note that the given module file has been loaded.
182 /// \returns false if the global module index has information about this
183 /// module file, and true otherwise.
184 bool loadedModuleFile(ModuleFile *File);
186 /// \brief Print statistics to standard error.
189 /// \brief Write a global index into the given
191 /// \param FileMgr The file manager to use to load module files.
193 /// \param Path The path to the directory containing module files, into
194 /// which the global index will be written.
195 static ErrorCode writeIndex(FileManager &FileMgr, StringRef Path);