include/llvm/Linker.h - llvm - Git at Google

 //===- llvm/Linker.h - Module Linker Interface ------------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines the interface to the module/file/archive linker.
 //
 //===----------------------------------------------------------------------===//

 #ifndef LLVM_LINKER_H
 #define LLVM_LINKER_H

 #include <memory>
 #include <vector>
 #include "llvm/ADT/StringRef.h"

 namespace llvm {
   namespace sys { class Path; }

 class Module;
 class LLVMContext;

 /// This class provides the core functionality of linking in LLVM. It retains a
 /// Module object which is the composite of the modules and libraries linked
 /// into it. The composite Module can be retrieved via the getModule() method.
 /// In this case the Linker still retains ownership of the Module. If the
 /// releaseModule() method is used, the ownership of the Module is transferred
 /// to the caller and the Linker object is only suitable for destruction.
 /// The Linker can link Modules from memory, bitcode files, or bitcode
 /// archives.  It retains a set of search paths in which to find any libraries
 /// presented to it. By default, the linker will generate error and warning
 /// messages to stderr but this capability can be turned off with the
 /// QuietWarnings and QuietErrors flags. It can also be instructed to verbosely
 /// print out the linking actions it is taking with the Verbose flag.
 /// @brief The LLVM Linker.
 class Linker {

   /// @name Types
   /// @{
   public:
     /// This type is used to pass the linkage items (libraries and files) to
     /// the LinkItems function. It is composed of string/bool pairs. The string
     /// provides the name of the file or library (as with the -l option). The
     /// bool should be true for libraries and false for files, signifying
     /// "isLibrary".
     /// @brief A list of linkage items
     typedef std::vector<std::pair<std::string,bool> > ItemList;

     /// This enumeration is used to control various optional features of the
     /// linker.
     enum ControlFlags {
       Verbose       = 1, ///< Print to stderr what steps the linker is taking
       QuietWarnings = 2, ///< Don't print warnings to stderr.
       QuietErrors   = 4  ///< Don't print errors to stderr.
     };

     enum LinkerMode {
       DestroySource = 0, // Allow source module to be destroyed.
       PreserveSource = 1 // Preserve the source module.
     };

   /// @}
   /// @name Constructors
   /// @{
   public:
     /// Construct the Linker with an empty module which will be given the
     /// name \p progname. \p progname will also be used for error messages.
     /// @brief Construct with empty module
     Linker(StringRef progname, ///< name of tool running linker
            StringRef modulename, ///< name of linker's end-result module
            LLVMContext &C, ///< Context for global info
            unsigned Flags = 0  ///< ControlFlags (one or more |'d together)
     );

     /// Construct the Linker with a previously defined module, \p aModule. Use
     /// \p progname for the name of the program in error messages.
     /// @brief Construct with existing module
     Linker(StringRef progname, Module* aModule, unsigned Flags = 0);

     /// Destruct the Linker.
     /// @brief Destructor
     ~Linker();

   /// @}
   /// @name Accessors
   /// @{
   public:
     /// This method gets the composite module into which linking is being
     /// done. The Composite module starts out empty and accumulates modules
     /// linked into it via the various LinkIn* methods. This method does not
     /// release the Module to the caller. The Linker retains ownership and will
     /// destruct the Module when the Linker is destructed.
     /// @see releaseModule
     /// @brief Get the linked/composite module.
     Module* getModule() const { return Composite; }

     /// This method releases the composite Module into which linking is being
     /// done. Ownership of the composite Module is transferred to the caller who
     /// must arrange for its destruct. After this method is called, the Linker
     /// terminates the linking session for the returned Module. It will no
     /// longer utilize the returned Module but instead resets itself for
     /// subsequent linking as if the constructor had been called. The Linker's
     /// LibPaths and flags to be reset, and memory will be released.
     /// @brief Release the linked/composite module.
     Module* releaseModule();

     /// This method gets the list of libraries that form the path that the
     /// Linker will search when it is presented with a library name.
     /// @brief Get the Linkers library path
     const std::vector<sys::Path>& getLibPaths() const { return LibPaths; }

     /// This method returns an error string suitable for printing to the user.
     /// The return value will be empty unless an error occurred in one of the
     /// LinkIn* methods. In those cases, the LinkIn* methods will have returned
     /// true, indicating an error occurred. At most one error is retained so
     /// this function always returns the last error that occurred. Note that if
     /// the Quiet control flag is not set, the error string will have already
     /// been printed to stderr.
     /// @brief Get the text of the last error that occurred.
     const std::string &getLastError() const { return Error; }

   /// @}
   /// @name Mutators
   /// @{
   public:
     /// Add a path to the list of paths that the Linker will search. The Linker
     /// accumulates the set of libraries added
     /// library paths for the target platform. The standard libraries will
     /// always be searched last. The added libraries will be searched in the
     /// order added.
     /// @brief Add a path.
     void addPath(const sys::Path& path);

     /// Add a set of paths to the list of paths that the linker will search. The
     /// Linker accumulates the set of libraries added. The \p paths will be
     /// added to the end of the Linker's list. Order will be retained.
     /// @brief Add a set of paths.
     void addPaths(const std::vector<std::string>& paths);

     /// This method augments the Linker's list of library paths with the system
     /// paths of the host operating system, include LLVM_LIB_SEARCH_PATH.
     /// @brief Add the system paths.
     void addSystemPaths();

     /// Control optional linker behavior by setting a group of flags. The flags
     /// are defined in the ControlFlags enumeration.
     /// @see ControlFlags
     /// @brief Set control flags.
     void setFlags(unsigned flags) { Flags = flags; }

     /// This method is the main interface to the linker. It can be used to
     /// link a set of linkage items into a module. A linkage item is either a
     /// file name with fully qualified path, or a library for which the Linker's
     /// LibraryPath will be utilized to locate the library. The bool value in
     /// the LinkItemKind should be set to true for libraries.  This function
     /// allows linking to preserve the order of specification associated with
     /// the command line, or for other purposes. Each item will be linked in
     /// turn as it occurs in \p Items.
     /// @returns true if an error occurred, false otherwise
     /// @see LinkItemKind
     /// @see getLastError
     bool LinkInItems (
       const ItemList& Items, ///< Set of libraries/files to link in
       ItemList& NativeItems  ///< Output list of native files/libs
     );

     /// This function links the bitcode \p Files into the composite module.
     /// Note that this does not do any linking of unresolved symbols. The \p
     /// Files are all completely linked into \p HeadModule regardless of
     /// unresolved symbols. This function just loads each bitcode file and
     /// calls LinkInModule on them.
     /// @returns true if an error occurs, false otherwise
     /// @see getLastError
     /// @brief Link in multiple files.
     bool LinkInFiles (
       const std::vector<sys::Path> & Files ///< Files to link in
     );

     /// This function links a single bitcode file, \p File, into the composite
     /// module. Note that this does not attempt to resolve symbols. This method
     /// just loads the bitcode file and calls LinkInModule on it. If an error
     /// occurs, the Linker's error string is set.
     /// @returns true if an error occurs, false otherwise
     /// @see getLastError
     /// @brief Link in a single file.
     bool LinkInFile(
       const sys::Path& File, ///< File to link in.
       bool &is_native        ///< Indicates if the file is native object file
     );

     /// This function provides a way to selectively link in a set of modules,
     /// found in libraries, based on the unresolved symbols in the composite
     /// module. Each item in \p Libraries should be the base name of a library,
     /// as if given with the -l option of a linker tool.  The Linker's LibPaths
     /// are searched for the \p Libraries and any found will be linked in with
     /// LinkInArchive.  If an error occurs, the Linker's error string is set.
     /// @see LinkInArchive
     /// @see getLastError
     /// @returns true if an error occurs, false otherwise
     /// @brief Link libraries into the module
     bool LinkInLibraries (
       const std::vector<std::string> & Libraries ///< Libraries to link in
     );

     /// This function provides a way to selectively link in a set of modules,
     /// found in one library, based on the unresolved symbols in the composite
     /// module.The \p Library should be the base name of a library, as if given
     /// with the -l option of a linker tool. The Linker's LibPaths are searched
     /// for the \p Library and if found, it will be linked in with via the
     /// LinkInArchive method. If an error occurs, the Linker's error string is
     /// set.
     /// @see LinkInArchive
     /// @see getLastError
     /// @returns true if an error occurs, false otherwise
     /// @brief Link one library into the module
     bool LinkInLibrary (
       StringRef Library, ///< The library to link in
       bool& is_native    ///< Indicates if lib a native library
     );

     /// This function links one bitcode archive, \p Filename, into the module.
     /// The archive is searched to resolve outstanding symbols. Any modules in
     /// the archive that resolve outstanding symbols will be linked in. The
     /// library is searched repeatedly until no more modules that resolve
     /// symbols can be found. If an error occurs, the error string is  set.
     /// To speed up this function, ensure the archive has been processed
     /// llvm-ranlib or the S option was given to llvm-ar when the archive was
     /// created. These tools add a symbol table to the archive which makes the
     /// search for undefined symbols much faster.
     /// @see getLastError
     /// @returns true if an error occurs, otherwise false.
     /// @brief Link in one archive.
     bool LinkInArchive(
       const sys::Path& Filename, ///< Filename of the archive to link
       bool& is_native            ///<  Indicates if archive is a native archive
     );

     /// This method links the \p Src module into the Linker's Composite module
     /// by calling LinkModules.  All the other LinkIn* methods eventually
     /// result in calling this method to link a Module into the Linker's
     /// composite.
     /// @see LinkModules
     /// @returns True if an error occurs, false otherwise.
     /// @brief Link in a module.
     bool LinkInModule(
       Module* Src,              ///< Module linked into \p Dest
       std::string* ErrorMsg = 0 /// Error/diagnostic string
     ) {
       return LinkModules(Composite, Src, Linker::DestroySource, ErrorMsg );
     }

     /// This is the heart of the linker. This method will take unconditional
     /// control of the \p Src module and link it into the \p Dest module. The
     /// \p Src module will be destructed or subsumed by this method. In either
     /// case it is not usable by the caller after this method is invoked. Only
     /// the \p Dest module will remain. The \p Src module is linked into the
     /// Linker's composite module such that types, global variables, functions,
     /// and etc. are matched and resolved.  If an error occurs, this function
     /// returns true and ErrorMsg is set to a descriptive message about the
     /// error.
     /// @returns True if an error occurs, false otherwise.
     /// @brief Generically link two modules together.
     static bool LinkModules(Module* Dest, Module* Src, unsigned Mode,
                             std::string* ErrorMsg);

     /// This function looks through the Linker's LibPaths to find a library with
     /// the name \p Filename. If the library cannot be found, the returned path
     /// will be empty (i.e. sys::Path::isEmpty() will return true).
     /// @returns A sys::Path to the found library
     /// @brief Find a library from its short name.
     sys::Path FindLib(StringRef Filename);

   /// @}
   /// @name Implementation
   /// @{
   private:
     /// Read in and parse the bitcode file named by FN and return the
     /// Module it contains (wrapped in an auto_ptr), or 0 if an error occurs.
     std::auto_ptr<Module> LoadObject(const sys::Path& FN);

     bool warning(StringRef message);
     bool error(StringRef message);
     void verbose(StringRef message);

   /// @}
   /// @name Data
   /// @{
   private:
     LLVMContext& Context; ///< The context for global information
     Module* Composite; ///< The composite module linked together
     std::vector<sys::Path> LibPaths; ///< The library search paths
     unsigned Flags;    ///< Flags to control optional behavior.
     std::string Error; ///< Text of error that occurred.
     std::string ProgramName; ///< Name of the program being linked
   /// @}

 };

 } // End llvm namespace

 #endif
	//===- llvm/Linker.h - Module Linker Interface ------------------- C++ --===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This file defines the interface to the module/file/archive linker.
	//
	//===----------------------------------------------------------------------===//

	#ifndef LLVM_LINKER_H
	#define LLVM_LINKER_H

	#include <memory>
	#include <vector>
	#include "llvm/ADT/StringRef.h"

	namespace llvm {
	namespace sys { class Path; }

	class Module;
	class LLVMContext;

	/// This class provides the core functionality of linking in LLVM. It retains a
	/// Module object which is the composite of the modules and libraries linked
	/// into it. The composite Module can be retrieved via the getModule() method.
	/// In this case the Linker still retains ownership of the Module. If the
	/// releaseModule() method is used, the ownership of the Module is transferred
	/// to the caller and the Linker object is only suitable for destruction.
	/// The Linker can link Modules from memory, bitcode files, or bitcode
	/// archives. It retains a set of search paths in which to find any libraries
	/// presented to it. By default, the linker will generate error and warning
	/// messages to stderr but this capability can be turned off with the
	/// QuietWarnings and QuietErrors flags. It can also be instructed to verbosely
	/// print out the linking actions it is taking with the Verbose flag.
	/// @brief The LLVM Linker.
	class Linker {

	/// @name Types
	/// @{
	public:
	/// This type is used to pass the linkage items (libraries and files) to
	/// the LinkItems function. It is composed of string/bool pairs. The string
	/// provides the name of the file or library (as with the -l option). The
	/// bool should be true for libraries and false for files, signifying
	/// "isLibrary".
	/// @brief A list of linkage items
	typedef std::vector<std::pair<std::string,bool> > ItemList;

	/// This enumeration is used to control various optional features of the
	/// linker.
	enum ControlFlags {
	Verbose = 1, ///< Print to stderr what steps the linker is taking
	QuietWarnings = 2, ///< Don't print warnings to stderr.
	QuietErrors = 4 ///< Don't print errors to stderr.
	};

	enum LinkerMode {
	DestroySource = 0, // Allow source module to be destroyed.
	PreserveSource = 1 // Preserve the source module.
	};

	/// @}
	/// @name Constructors
	/// @{
	public:
	/// Construct the Linker with an empty module which will be given the
	/// name \p progname. \p progname will also be used for error messages.
	/// @brief Construct with empty module
	Linker(StringRef progname, ///< name of tool running linker
	StringRef modulename, ///< name of linker's end-result module
	LLVMContext &C, ///< Context for global info
	unsigned Flags = 0 ///< ControlFlags (one or more \|'d together)
	);

	/// Construct the Linker with a previously defined module, \p aModule. Use
	/// \p progname for the name of the program in error messages.
	/// @brief Construct with existing module
	Linker(StringRef progname, Module* aModule, unsigned Flags = 0);

	/// Destruct the Linker.
	/// @brief Destructor
	~Linker();

	/// @}
	/// @name Accessors
	/// @{
	public:
	/// This method gets the composite module into which linking is being
	/// done. The Composite module starts out empty and accumulates modules
	/// linked into it via the various LinkIn* methods. This method does not
	/// release the Module to the caller. The Linker retains ownership and will
	/// destruct the Module when the Linker is destructed.
	/// @see releaseModule
	/// @brief Get the linked/composite module.
	Module* getModule() const { return Composite; }

	/// This method releases the composite Module into which linking is being
	/// done. Ownership of the composite Module is transferred to the caller who
	/// must arrange for its destruct. After this method is called, the Linker
	/// terminates the linking session for the returned Module. It will no
	/// longer utilize the returned Module but instead resets itself for
	/// subsequent linking as if the constructor had been called. The Linker's
	/// LibPaths and flags to be reset, and memory will be released.
	/// @brief Release the linked/composite module.
	Module* releaseModule();

	/// This method gets the list of libraries that form the path that the
	/// Linker will search when it is presented with a library name.
	/// @brief Get the Linkers library path
	const std::vector<sys::Path>& getLibPaths() const { return LibPaths; }

	/// This method returns an error string suitable for printing to the user.
	/// The return value will be empty unless an error occurred in one of the
	/// LinkIn* methods. In those cases, the LinkIn* methods will have returned
	/// true, indicating an error occurred. At most one error is retained so
	/// this function always returns the last error that occurred. Note that if
	/// the Quiet control flag is not set, the error string will have already
	/// been printed to stderr.
	/// @brief Get the text of the last error that occurred.
	const std::string &getLastError() const { return Error; }

	/// @}
	/// @name Mutators
	/// @{
	public:
	/// Add a path to the list of paths that the Linker will search. The Linker
	/// accumulates the set of libraries added
	/// library paths for the target platform. The standard libraries will
	/// always be searched last. The added libraries will be searched in the
	/// order added.
	/// @brief Add a path.
	void addPath(const sys::Path& path);

	/// Add a set of paths to the list of paths that the linker will search. The
	/// Linker accumulates the set of libraries added. The \p paths will be
	/// added to the end of the Linker's list. Order will be retained.
	/// @brief Add a set of paths.
	void addPaths(const std::vector<std::string>& paths);

	/// This method augments the Linker's list of library paths with the system
	/// paths of the host operating system, include LLVM_LIB_SEARCH_PATH.
	/// @brief Add the system paths.
	void addSystemPaths();

	/// Control optional linker behavior by setting a group of flags. The flags
	/// are defined in the ControlFlags enumeration.
	/// @see ControlFlags
	/// @brief Set control flags.
	void setFlags(unsigned flags) { Flags = flags; }

	/// This method is the main interface to the linker. It can be used to
	/// link a set of linkage items into a module. A linkage item is either a
	/// file name with fully qualified path, or a library for which the Linker's
	/// LibraryPath will be utilized to locate the library. The bool value in
	/// the LinkItemKind should be set to true for libraries. This function
	/// allows linking to preserve the order of specification associated with
	/// the command line, or for other purposes. Each item will be linked in
	/// turn as it occurs in \p Items.
	/// @returns true if an error occurred, false otherwise
	/// @see LinkItemKind
	/// @see getLastError
	bool LinkInItems (
	const ItemList& Items, ///< Set of libraries/files to link in
	ItemList& NativeItems ///< Output list of native files/libs
	);

	/// This function links the bitcode \p Files into the composite module.
	/// Note that this does not do any linking of unresolved symbols. The \p
	/// Files are all completely linked into \p HeadModule regardless of
	/// unresolved symbols. This function just loads each bitcode file and
	/// calls LinkInModule on them.
	/// @returns true if an error occurs, false otherwise
	/// @see getLastError
	/// @brief Link in multiple files.
	bool LinkInFiles (
	const std::vector<sys::Path> & Files ///< Files to link in
	);

	/// This function links a single bitcode file, \p File, into the composite
	/// module. Note that this does not attempt to resolve symbols. This method
	/// just loads the bitcode file and calls LinkInModule on it. If an error
	/// occurs, the Linker's error string is set.
	/// @returns true if an error occurs, false otherwise
	/// @see getLastError
	/// @brief Link in a single file.
	bool LinkInFile(
	const sys::Path& File, ///< File to link in.
	bool &is_native ///< Indicates if the file is native object file
	);

	/// This function provides a way to selectively link in a set of modules,
	/// found in libraries, based on the unresolved symbols in the composite
	/// module. Each item in \p Libraries should be the base name of a library,
	/// as if given with the -l option of a linker tool. The Linker's LibPaths
	/// are searched for the \p Libraries and any found will be linked in with
	/// LinkInArchive. If an error occurs, the Linker's error string is set.
	/// @see LinkInArchive
	/// @see getLastError
	/// @returns true if an error occurs, false otherwise
	/// @brief Link libraries into the module
	bool LinkInLibraries (
	const std::vector<std::string> & Libraries ///< Libraries to link in
	);

	/// This function provides a way to selectively link in a set of modules,
	/// found in one library, based on the unresolved symbols in the composite
	/// module.The \p Library should be the base name of a library, as if given
	/// with the -l option of a linker tool. The Linker's LibPaths are searched
	/// for the \p Library and if found, it will be linked in with via the
	/// LinkInArchive method. If an error occurs, the Linker's error string is
	/// set.
	/// @see LinkInArchive
	/// @see getLastError
	/// @returns true if an error occurs, false otherwise
	/// @brief Link one library into the module
	bool LinkInLibrary (
	StringRef Library, ///< The library to link in
	bool& is_native ///< Indicates if lib a native library
	);

	/// This function links one bitcode archive, \p Filename, into the module.
	/// The archive is searched to resolve outstanding symbols. Any modules in
	/// the archive that resolve outstanding symbols will be linked in. The
	/// library is searched repeatedly until no more modules that resolve
	/// symbols can be found. If an error occurs, the error string is set.
	/// To speed up this function, ensure the archive has been processed
	/// llvm-ranlib or the S option was given to llvm-ar when the archive was
	/// created. These tools add a symbol table to the archive which makes the
	/// search for undefined symbols much faster.
	/// @see getLastError
	/// @returns true if an error occurs, otherwise false.
	/// @brief Link in one archive.
	bool LinkInArchive(
	const sys::Path& Filename, ///< Filename of the archive to link
	bool& is_native ///< Indicates if archive is a native archive
	);

	/// This method links the \p Src module into the Linker's Composite module
	/// by calling LinkModules. All the other LinkIn* methods eventually
	/// result in calling this method to link a Module into the Linker's
	/// composite.
	/// @see LinkModules
	/// @returns True if an error occurs, false otherwise.
	/// @brief Link in a module.
	bool LinkInModule(
	Module* Src, ///< Module linked into \p Dest
	std::string* ErrorMsg = 0 /// Error/diagnostic string
	) {
	return LinkModules(Composite, Src, Linker::DestroySource, ErrorMsg );
	}

	/// This is the heart of the linker. This method will take unconditional
	/// control of the \p Src module and link it into the \p Dest module. The
	/// \p Src module will be destructed or subsumed by this method. In either
	/// case it is not usable by the caller after this method is invoked. Only
	/// the \p Dest module will remain. The \p Src module is linked into the
	/// Linker's composite module such that types, global variables, functions,
	/// and etc. are matched and resolved. If an error occurs, this function
	/// returns true and ErrorMsg is set to a descriptive message about the
	/// error.
	/// @returns True if an error occurs, false otherwise.
	/// @brief Generically link two modules together.
	static bool LinkModules(Module* Dest, Module* Src, unsigned Mode,
	std::string* ErrorMsg);

	/// This function looks through the Linker's LibPaths to find a library with
	/// the name \p Filename. If the library cannot be found, the returned path
	/// will be empty (i.e. sys::Path::isEmpty() will return true).
	/// @returns A sys::Path to the found library
	/// @brief Find a library from its short name.
	sys::Path FindLib(StringRef Filename);

	/// @}
	/// @name Implementation
	/// @{
	private:
	/// Read in and parse the bitcode file named by FN and return the
	/// Module it contains (wrapped in an auto_ptr), or 0 if an error occurs.
	std::auto_ptr<Module> LoadObject(const sys::Path& FN);

	bool warning(StringRef message);
	bool error(StringRef message);
	void verbose(StringRef message);

	/// @}
	/// @name Data
	/// @{
	private:
	LLVMContext& Context; ///< The context for global information
	Module* Composite; ///< The composite module linked together
	std::vector<sys::Path> LibPaths; ///< The library search paths
	unsigned Flags; ///< Flags to control optional behavior.
	std::string Error; ///< Text of error that occurred.
	std::string ProgramName; ///< Name of the program being linked
	/// @}

	};

	} // End llvm namespace

	#endif