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_GLOBAL_MODULE_INDEX_H 17 #define LLVM_CLANG_SERIALIZATION_GLOBAL_MODULE_INDEX_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 39 namespace serialization { 40 class ModuleFile; 41 } 42 43 using llvm::SmallVector; 44 using llvm::SmallVectorImpl; 45 using llvm::StringRef; 46 using serialization::ModuleFile; 47 48 /// \brief A global index for a set of module files, providing information about 49 /// the identifiers within those module files. 50 /// 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 std::unique_ptr<llvm::MemoryBuffer> Buffer; 63 64 /// \brief The hash table. 65 /// 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; 70 71 /// \brief Information about a given module file. 72 struct ModuleInfo { 73 ModuleInfo() : File(), Size(), ModTime() { } 74 75 /// \brief The module file, once it has been resolved. 76 ModuleFile *File; 77 78 /// \brief The module file name. 79 std::string FileName; 80 81 /// \brief Size of the module file at the time the global index was built. 82 off_t Size; 83 84 /// \brief Modification time of the module file at the time the global 85 /// index was built. 86 time_t ModTime; 87 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; 91 }; 92 93 /// \brief A mapping from module IDs to information about each module. 94 /// 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 97 /// file name. 98 llvm::SmallVector<ModuleInfo, 16> Modules; 99 100 /// \brief Lazily-populated mapping from module files to their 101 /// corresponding index into the \c Modules vector. 102 llvm::DenseMap<ModuleFile *, unsigned> ModulesByFile; 103 104 /// \brief The set of modules that have not yet been resolved. 105 /// 106 /// The string is just the name of the module itself, which maps to the 107 /// module ID. 108 llvm::StringMap<unsigned> UnresolvedModules; 109 110 /// \brief The number of identifier lookups we performed. 111 unsigned NumIdentifierLookups; 112 113 /// \brief The number of identifier lookup hits, where we recognize the 114 /// identifier. 115 unsigned NumIdentifierLookupHits; 116 117 /// \brief Internal constructor. Use \c readIndex() to read an index. 118 explicit GlobalModuleIndex(llvm::MemoryBuffer *Buffer, 119 llvm::BitstreamCursor Cursor); 120 121 GlobalModuleIndex(const GlobalModuleIndex &) LLVM_DELETED_FUNCTION; 122 GlobalModuleIndex &operator=(const GlobalModuleIndex &) LLVM_DELETED_FUNCTION; 123 124 public: 125 ~GlobalModuleIndex(); 126 127 /// \brief An error code returned when trying to read an index. 128 enum ErrorCode { 129 /// \brief No error occurred. 130 EC_None, 131 /// \brief No index was found. 132 EC_NotFound, 133 /// \brief Some other process is currently building the index; it is not 134 /// available yet. 135 EC_Building, 136 /// \brief There was an unspecified I/O error reading or writing the index. 137 EC_IOError 138 }; 139 140 /// \brief Read a global index file for the given directory. 141 /// 142 /// \param Path The path to the specific module cache where the module files 143 /// for the intended configuration reside. 144 /// 145 /// \returns A pair containing the global module index (if it exists) and 146 /// the error code. 147 static std::pair<GlobalModuleIndex *, ErrorCode> 148 readIndex(StringRef Path); 149 150 /// \brief Returns an iterator for identifiers stored in the index table. 151 /// 152 /// The caller accepts ownership of the returned object. 153 IdentifierIterator *createIdentifierIterator() const; 154 155 /// \brief Retrieve the set of modules that have up-to-date indexes. 156 /// 157 /// \param ModuleFiles Will be populated with the set of module files that 158 /// have been indexed. 159 void getKnownModules(SmallVectorImpl<ModuleFile *> &ModuleFiles); 160 161 /// \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); 165 166 /// \brief A set of module files in which we found a result. 167 typedef llvm::SmallPtrSet<ModuleFile *, 4> HitSet; 168 169 /// \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. 171 /// 172 /// \param Name The identifier to look for. 173 /// 174 /// \param Hits Will be populated with the set of module files that have 175 /// information about this name. 176 /// 177 /// \returns true if the identifier is known to the index, false otherwise. 178 bool lookupIdentifier(StringRef Name, HitSet &Hits); 179 180 /// \brief Note that the given module file has been loaded. 181 /// 182 /// \returns false if the global module index has information about this 183 /// module file, and true otherwise. 184 bool loadedModuleFile(ModuleFile *File); 185 186 /// \brief Print statistics to standard error. 187 void printStats(); 188 189 /// \brief Print debugging view to standard error. 190 void dump(); 191 192 /// \brief Write a global index into the given 193 /// 194 /// \param FileMgr The file manager to use to load module files. 195 /// 196 /// \param Path The path to the directory containing module files, into 197 /// which the global index will be written. 198 static ErrorCode writeIndex(FileManager &FileMgr, StringRef Path); 199 }; 200 201 } 202 203 #endif 204
