LLVM API Documentation

LinkItems.cpp

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00001 //===- lib/Linker/LinkItems.cpp - Link LLVM objects and libraries ---------===//
00002 //
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file was developed by Reid Spencer and is distributed under the
00006 // University of Illinois Open Source License. See LICENSE.TXT for details.
00007 //
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This file contains routines to handle linking together LLVM bytecode files,
00011 // and to handle annoying things like static libraries.
00012 //
00013 //===----------------------------------------------------------------------===//
00014 
00015 #include "llvm/Linker.h"
00016 #include "llvm/Module.h"
00017 
00018 using namespace llvm;
00019 
00020 // LinkItems - This function is the main entry point into linking. It takes a
00021 // list of LinkItem which indicates the order the files should be linked and
00022 // how each file should be treated (plain file or with library search). The
00023 // function only links bytecode and produces a result list of items that are
00024 // native objects. 
00025 bool
00026 Linker::LinkInItems(const ItemList& Items, ItemList& NativeItems) {
00027   // Clear the NativeItems just in case
00028   NativeItems.clear();
00029 
00030   // For each linkage item ...
00031   for (ItemList::const_iterator I = Items.begin(), E = Items.end();
00032        I != E; ++I) {
00033     if (I->second) {
00034       // Link in the library suggested.
00035       bool is_file = true;
00036       if (LinkInLibrary(I->first,is_file))
00037         return true;
00038       if (!is_file)
00039         NativeItems.push_back(*I);
00040     } else {
00041       // Link in the file suggested
00042       if (LinkInFile(sys::Path(I->first)))
00043         return true;
00044     }
00045   }
00046 
00047   // At this point we have processed all the link items provided to us. Since
00048   // we have an aggregated module at this point, the dependent libraries in
00049   // that module should also be aggregated with duplicates eliminated. This is
00050   // now the time to process the dependent libraries to resolve any remaining
00051   // symbols.
00052   bool is_bytecode;
00053   for (Module::lib_iterator I = Composite->lib_begin(),
00054          E = Composite->lib_end(); I != E; ++I)
00055     if(LinkInLibrary(*I, is_bytecode))
00056       return true;
00057 
00058   return false;
00059 }
00060 
00061 
00062 /// LinkInLibrary - links one library into the HeadModule.
00063 ///
00064 bool Linker::LinkInLibrary(const std::string& Lib, bool& is_file) {
00065   is_file = false;
00066   // Determine where this library lives.
00067   sys::Path Pathname = FindLib(Lib);
00068   if (Pathname.isEmpty())
00069     return warning("Cannot find library '" + Lib + "'");
00070 
00071   // If its an archive, try to link it in
00072   std::string Magic;
00073   Pathname.getMagicNumber(Magic, 64);
00074   switch (sys::IdentifyFileType(Magic.c_str(), 64)) {
00075     case sys::BytecodeFileType:
00076     case sys::CompressedBytecodeFileType:
00077       // LLVM ".so" file.
00078       if (LinkInFile(Pathname))
00079         return error("Cannot link file '" + Pathname.toString() + "'");
00080       is_file = true;
00081       break;
00082     case sys::ArchiveFileType:
00083       if (LinkInArchive(Pathname))
00084         return error("Cannot link archive '" + Pathname.toString() + "'");
00085       break;
00086     default:
00087       return warning("Supposed library '" + Lib + "' isn't a library.");
00088   }
00089   return false;
00090 }
00091 
00092 /// LinkLibraries - takes the specified library files and links them into the
00093 /// main bytecode object file.
00094 ///
00095 /// Inputs:
00096 ///  Libraries  - The list of libraries to link into the module.
00097 ///
00098 /// Return value:
00099 ///  FALSE - No error.
00100 ///  TRUE  - Error.
00101 ///
00102 bool Linker::LinkInLibraries(const std::vector<std::string> &Libraries) {
00103 
00104   // Process the set of libraries we've been provided.
00105   bool is_bytecode;
00106   for (unsigned i = 0; i < Libraries.size(); ++i)
00107     if (LinkInLibrary(Libraries[i], is_bytecode))
00108       return true;
00109 
00110   // At this point we have processed all the libraries provided to us. Since
00111   // we have an aggregated module at this point, the dependent libraries in
00112   // that module should also be aggregated with duplicates eliminated. This is
00113   // now the time to process the dependent libraries to resolve any remaining
00114   // symbols.
00115   const Module::LibraryListType& DepLibs = Composite->getLibraries();
00116   for (Module::LibraryListType::const_iterator I = DepLibs.begin(),
00117          E = DepLibs.end(); I != E; ++I)
00118     if (LinkInLibrary(*I, is_bytecode))
00119       return true;
00120 
00121   return false;
00122 }
00123 
00124 /// LinkInFile - opens a bytecode file and links in all objects which
00125 /// provide symbols that are currently undefined.
00126 ///
00127 /// Inputs:
00128 ///  File - The pathname of the bytecode file.
00129 ///
00130 /// Outputs:
00131 ///  ErrorMessage - A C++ string detailing what error occurred, if any.
00132 ///
00133 /// Return Value:
00134 ///  TRUE  - An error occurred.
00135 ///  FALSE - No errors.
00136 ///
00137 bool Linker::LinkInFile(const sys::Path &File) {
00138   // Make sure we can at least read the file
00139   if (!File.canRead())
00140     return error("Cannot find linker input '" + File.toString() + "'");
00141 
00142   // A user may specify an ar archive without -l, perhaps because it
00143   // is not installed as a library. Detect that and link the library.
00144   if (File.isArchive()) {
00145     if (LinkInArchive(File))
00146       return error("Cannot link archive '" + File.toString() + "'");
00147   } else if (File.isBytecodeFile()) {
00148     verbose("Linking bytecode file '" + File.toString() + "'");
00149 
00150     std::auto_ptr<Module> M(LoadObject(File));
00151     if (M.get() == 0)
00152       return error("Cannot load file '" + File.toString() + "'" + Error);
00153     if (LinkInModule(M.get()))
00154       return error("Cannot link file '" + File.toString() + "'" + Error);
00155 
00156     verbose("Linked in file '" + File.toString() + "'");
00157   } else {
00158     return warning("File of unknown type '" + File.toString() + "' ignored.");
00159   }
00160   return false;
00161 }
00162 
00163 /// LinkFiles - takes a module and a list of files and links them all together.
00164 /// It locates the file either in the current directory, as its absolute
00165 /// or relative pathname, or as a file somewhere in LLVM_LIB_SEARCH_PATH.
00166 ///
00167 /// Inputs:
00168 ///  Files      - A vector of sys::Path indicating the LLVM bytecode filenames
00169 ///               to be linked.  The names can refer to a mixture of pure LLVM
00170 ///               bytecode files and archive (ar) formatted files.
00171 ///
00172 /// Return value:
00173 ///  FALSE - No errors.
00174 ///  TRUE  - Some error occurred.
00175 ///
00176 bool Linker::LinkInFiles(const std::vector<sys::Path> &Files) {
00177   for (unsigned i = 0; i < Files.size(); ++i)
00178     if (LinkInFile(Files[i]))
00179       return true;
00180   return false;
00181 }