1 //===- llvm/Linker.h - Module Linker Interface ------------------*- 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 interface to the module/file/archive linker. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_LINKER_H 15 #define LLVM_LINKER_H 16 17 #include <memory> 18 #include <string> 19 #include <vector> 20 21 namespace llvm { 22 namespace sys { class Path; } 23 24 class Module; 25 class LLVMContext; 26 class StringRef; 27 28 /// This class provides the core functionality of linking in LLVM. It retains a 29 /// Module object which is the composite of the modules and libraries linked 30 /// into it. The composite Module can be retrieved via the getModule() method. 31 /// In this case the Linker still retains ownership of the Module. If the 32 /// releaseModule() method is used, the ownership of the Module is transferred 33 /// to the caller and the Linker object is only suitable for destruction. 34 /// The Linker can link Modules from memory. It retains a set of search paths 35 /// in which to find any libraries presented to it. By default, the linker 36 /// will generate error and warning messages to stderr but this capability can 37 /// be turned off with the QuietWarnings and QuietErrors flags. It can also be 38 /// instructed to verbosely print out the linking actions it is taking with 39 /// the Verbose flag. 40 /// @brief The LLVM Linker. 41 class Linker { 42 43 /// @name Types 44 /// @{ 45 public: 46 /// This enumeration is used to control various optional features of the 47 /// linker. 48 enum ControlFlags { 49 Verbose = 1, ///< Print to stderr what steps the linker is taking 50 QuietWarnings = 2, ///< Don't print warnings to stderr. 51 QuietErrors = 4 ///< Don't print errors to stderr. 52 }; 53 54 enum LinkerMode { 55 DestroySource = 0, // Allow source module to be destroyed. 56 PreserveSource = 1 // Preserve the source module. 57 }; 58 59 /// @} 60 /// @name Constructors 61 /// @{ 62 public: 63 /// Construct the Linker with an empty module which will be given the 64 /// name \p progname. \p progname will also be used for error messages. 65 /// @brief Construct with empty module 66 Linker(StringRef progname, ///< name of tool running linker 67 StringRef modulename, ///< name of linker's end-result module 68 LLVMContext &C, ///< Context for global info 69 unsigned Flags = 0 ///< ControlFlags (one or more |'d together) 70 ); 71 72 /// Construct the Linker with a previously defined module, \p aModule. Use 73 /// \p progname for the name of the program in error messages. 74 /// @brief Construct with existing module 75 Linker(StringRef progname, Module* aModule, unsigned Flags = 0); 76 77 /// Destruct the Linker. 78 /// @brief Destructor 79 ~Linker(); 80 81 /// @} 82 /// @name Accessors 83 /// @{ 84 public: 85 /// This method gets the composite module into which linking is being 86 /// done. The Composite module starts out empty and accumulates modules 87 /// linked into it via the various LinkIn* methods. This method does not 88 /// release the Module to the caller. The Linker retains ownership and will 89 /// destruct the Module when the Linker is destructed. 90 /// @see releaseModule 91 /// @brief Get the linked/composite module. 92 Module* getModule() const { return Composite; } 93 94 /// This method releases the composite Module into which linking is being 95 /// done. Ownership of the composite Module is transferred to the caller who 96 /// must arrange for its destruct. After this method is called, the Linker 97 /// terminates the linking session for the returned Module. It will no 98 /// longer utilize the returned Module but instead resets itself for 99 /// subsequent linking as if the constructor had been called. The Linker's 100 /// LibPaths and flags to be reset, and memory will be released. 101 /// @brief Release the linked/composite module. 102 Module* releaseModule(); 103 104 /// This method gets the list of libraries that form the path that the 105 /// Linker will search when it is presented with a library name. 106 /// @brief Get the Linkers library path 107 const std::vector<sys::Path>& getLibPaths() const { return LibPaths; } 108 109 /// This method returns an error string suitable for printing to the user. 110 /// The return value will be empty unless an error occurred in one of the 111 /// LinkIn* methods. In those cases, the LinkIn* methods will have returned 112 /// true, indicating an error occurred. At most one error is retained so 113 /// this function always returns the last error that occurred. Note that if 114 /// the Quiet control flag is not set, the error string will have already 115 /// been printed to stderr. 116 /// @brief Get the text of the last error that occurred. 117 const std::string &getLastError() const { return Error; } 118 119 /// @} 120 /// @name Mutators 121 /// @{ 122 public: 123 /// Add a path to the list of paths that the Linker will search. The Linker 124 /// accumulates the set of libraries added 125 /// library paths for the target platform. The standard libraries will 126 /// always be searched last. The added libraries will be searched in the 127 /// order added. 128 /// @brief Add a path. 129 void addPath(const sys::Path& path); 130 131 /// Add a set of paths to the list of paths that the linker will search. The 132 /// Linker accumulates the set of libraries added. The \p paths will be 133 /// added to the end of the Linker's list. Order will be retained. 134 /// @brief Add a set of paths. 135 void addPaths(const std::vector<std::string>& paths); 136 137 /// This method augments the Linker's list of library paths with the system 138 /// paths of the host operating system, include LLVM_LIB_SEARCH_PATH. 139 /// @brief Add the system paths. 140 void addSystemPaths(); 141 142 /// Control optional linker behavior by setting a group of flags. The flags 143 /// are defined in the ControlFlags enumeration. 144 /// @see ControlFlags 145 /// @brief Set control flags. 146 void setFlags(unsigned flags) { Flags = flags; } 147 148 /// This method links the \p Src module into the Linker's Composite module 149 /// by calling LinkModules. 150 /// @see LinkModules 151 /// @returns True if an error occurs, false otherwise. 152 /// @brief Link in a module. 153 bool LinkInModule( 154 Module* Src, ///< Module linked into \p Dest 155 std::string* ErrorMsg = 0 /// Error/diagnostic string 156 ) { 157 return LinkModules(Composite, Src, Linker::DestroySource, ErrorMsg); 158 } 159 160 /// This is the heart of the linker. This method will take unconditional 161 /// control of the \p Src module and link it into the \p Dest module. The 162 /// \p Src module will be destructed or subsumed by this method. In either 163 /// case it is not usable by the caller after this method is invoked. Only 164 /// the \p Dest module will remain. The \p Src module is linked into the 165 /// Linker's composite module such that types, global variables, functions, 166 /// and etc. are matched and resolved. If an error occurs, this function 167 /// returns true and ErrorMsg is set to a descriptive message about the 168 /// error. 169 /// @returns True if an error occurs, false otherwise. 170 /// @brief Generically link two modules together. 171 static bool LinkModules(Module* Dest, Module* Src, unsigned Mode, 172 std::string* ErrorMsg); 173 174 /// @} 175 /// @name Implementation 176 /// @{ 177 private: 178 bool warning(StringRef message); 179 bool error(StringRef message); 180 void verbose(StringRef message); 181 182 /// @} 183 /// @name Data 184 /// @{ 185 private: 186 LLVMContext& Context; ///< The context for global information 187 Module* Composite; ///< The composite module linked together 188 std::vector<sys::Path> LibPaths; ///< The library search paths 189 unsigned Flags; ///< Flags to control optional behavior. 190 std::string Error; ///< Text of error that occurred. 191 std::string ProgramName; ///< Name of the program being linked 192 /// @} 193 194 }; 195 196 } // End llvm namespace 197 198 #endif 199
