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//===- 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 <string>
#include <vector>
namespace llvm {
namespace sys { class Path; }
class Module;
class LLVMContext;
class StringRef;
/// 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 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);
/// @}
/// @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
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