lib/Linker/LinkItems.cpp

   1 //===- lib/Linker/LinkItems.cpp - Link LLVM objects and libraries ---------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file was developed by Reid Spencer and is distributed under the
   6 // University of Illinois Open Source License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file contains routines to handle linking together LLVM bytecode files,
  11 // and to handle annoying things like static libraries.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "llvm/Linker.h"
  16 #include "llvm/Module.h"
  17
  18 using namespace llvm;
  19
  20 // LinkItems - This function is the main entry point into linking. It takes a
  21 // list of LinkItem which indicates the order the files should be linked and
  22 // how each file should be treated (plain file or with library search). The
  23 // function only links bytecode and produces a result list of items that are
  24 // native objects.
  25 bool
  26 Linker::LinkInItems(const ItemList& Items, ItemList& NativeItems) {
  27   // Clear the NativeItems just in case
  28   NativeItems.clear();
  29
  30   // For each linkage item ...
  31   for (ItemList::const_iterator I = Items.begin(), E = Items.end();
  32        I != E; ++I) {
  33     if (I->second) {
  34       // Link in the library suggested.
  35       bool is_file = true;
  36       if (LinkInLibrary(I->first,is_file))
  37         return true;
  38       if (!is_file)
  39         NativeItems.push_back(*I);
  40     } else {
  41       // Link in the file suggested
  42       if (LinkInFile(sys::Path(I->first)))
  43         return true;
  44     }
  45   }
  46
  47   // At this point we have processed all the link items provided to us. Since
  48   // we have an aggregated module at this point, the dependent libraries in
  49   // that module should also be aggregated with duplicates eliminated. This is
  50   // now the time to process the dependent libraries to resolve any remaining
  51   // symbols.
  52   bool is_bytecode;
  53   for (Module::lib_iterator I = Composite->lib_begin(),
  54          E = Composite->lib_end(); I != E; ++I)
  55     if(LinkInLibrary(*I, is_bytecode))
  56       return true;
  57
  58   return false;
  59 }
  60
  61
  62 /// LinkInLibrary - links one library into the HeadModule.
  63 ///
  64 bool Linker::LinkInLibrary(const std::string& Lib, bool& is_file) {
  65   is_file = false;
  66   // Determine where this library lives.
  67   sys::Path Pathname = FindLib(Lib);
  68   if (Pathname.isEmpty())
  69     return warning("Cannot find library '" + Lib + "'");
  70
  71   // If its an archive, try to link it in
  72   std::string Magic;
  73   Pathname.getMagicNumber(Magic, 64);
  74   switch (sys::IdentifyFileType(Magic.c_str(), 64)) {
  75     case sys::BytecodeFileType:
  76     case sys::CompressedBytecodeFileType:
  77       // LLVM ".so" file.
  78       if (LinkInFile(Pathname))
  79         return error("Cannot link file '" + Pathname.toString() + "'");
  80       is_file = true;
  81       break;
  82     case sys::ArchiveFileType:
  83       if (LinkInArchive(Pathname))
  84         return error("Cannot link archive '" + Pathname.toString() + "'");
  85       break;
  86     default:
  87       return warning("Supposed library '" + Lib + "' isn't a library.");
  88   }
  89   return false;
  90 }
  91
  92 /// LinkLibraries - takes the specified library files and links them into the
  93 /// main bytecode object file.
  94 ///
  95 /// Inputs:
  96 ///  Libraries  - The list of libraries to link into the module.
  97 ///
  98 /// Return value:
  99 ///  FALSE - No error.
 100 ///  TRUE  - Error.
 101 ///
 102 bool Linker::LinkInLibraries(const std::vector<std::string> &Libraries) {
 103
 104   // Process the set of libraries we've been provided.
 105   bool is_bytecode;
 106   for (unsigned i = 0; i < Libraries.size(); ++i)
 107     if (LinkInLibrary(Libraries[i], is_bytecode))
 108       return true;
 109
 110   // At this point we have processed all the libraries provided to us. Since
 111   // we have an aggregated module at this point, the dependent libraries in
 112   // that module should also be aggregated with duplicates eliminated. This is
 113   // now the time to process the dependent libraries to resolve any remaining
 114   // symbols.
 115   const Module::LibraryListType& DepLibs = Composite->getLibraries();
 116   for (Module::LibraryListType::const_iterator I = DepLibs.begin(),
 117          E = DepLibs.end(); I != E; ++I)
 118     if (LinkInLibrary(*I, is_bytecode))
 119       return true;
 120
 121   return false;
 122 }
 123
 124 /// LinkInFile - opens a bytecode file and links in all objects which
 125 /// provide symbols that are currently undefined.
 126 ///
 127 /// Inputs:
 128 ///  File - The pathname of the bytecode file.
 129 ///
 130 /// Outputs:
 131 ///  ErrorMessage - A C++ string detailing what error occurred, if any.
 132 ///
 133 /// Return Value:
 134 ///  TRUE  - An error occurred.
 135 ///  FALSE - No errors.
 136 ///
 137 bool Linker::LinkInFile(const sys::Path &File) {
 138   // Make sure we can at least read the file
 139   if (!File.canRead())
 140     return error("Cannot find linker input '" + File.toString() + "'");
 141
 142   // A user may specify an ar archive without -l, perhaps because it
 143   // is not installed as a library. Detect that and link the library.
 144   if (File.isArchive()) {
 145     if (LinkInArchive(File))
 146       return error("Cannot link archive '" + File.toString() + "'");
 147   } else if (File.isBytecodeFile()) {
 148     verbose("Linking bytecode file '" + File.toString() + "'");
 149
 150     std::auto_ptr<Module> M(LoadObject(File));
 151     if (M.get() == 0)
 152       return error("Cannot load file '" + File.toString() + "'" + Error);
 153     if (LinkInModule(M.get()))
 154       return error("Cannot link file '" + File.toString() + "'" + Error);
 155
 156     verbose("Linked in file '" + File.toString() + "'");
 157   } else {
 158     return warning("File of unknown type '" + File.toString() + "' ignored.");
 159   }
 160   return false;
 161 }
 162
 163 /// LinkFiles - takes a module and a list of files and links them all together.
 164 /// It locates the file either in the current directory, as its absolute
 165 /// or relative pathname, or as a file somewhere in LLVM_LIB_SEARCH_PATH.
 166 ///
 167 /// Inputs:
 168 ///  Files      - A vector of sys::Path indicating the LLVM bytecode filenames
 169 ///               to be linked.  The names can refer to a mixture of pure LLVM
 170 ///               bytecode files and archive (ar) formatted files.
 171 ///
 172 /// Return value:
 173 ///  FALSE - No errors.
 174 ///  TRUE  - Some error occurred.
 175 ///
 176 bool Linker::LinkInFiles(const std::vector<sys::Path> &Files) {
 177   for (unsigned i = 0; i < Files.size(); ++i)
 178     if (LinkInFile(Files[i]))
 179       return true;
 180   return false;
 181 }