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_native = false;
  36       if (LinkInLibrary(I->first, is_native))
  37         return true;
  38       if (is_native)
  39         NativeItems.push_back(*I);
  40     } else {
  41       // Link in the file suggested
  42       bool is_native = false;
  43       if (LinkInFile(sys::Path(I->first), is_native))
  44         return true;
  45       if (is_native)
  46         NativeItems.push_back(*I);
  47     }
  48   }
  49
  50   // At this point we have processed all the link items provided to us. Since
  51   // we have an aggregated module at this point, the dependent libraries in
  52   // that module should also be aggregated with duplicates eliminated. This is
  53   // now the time to process the dependent libraries to resolve any remaining
  54   // symbols.
  55   bool is_native;
  56   for (Module::lib_iterator I = Composite->lib_begin(),
  57          E = Composite->lib_end(); I != E; ++I) {
  58     if(LinkInLibrary(*I, is_native))
  59       return true;
  60     if (is_native)
  61       NativeItems.push_back(std::make_pair(*I, true));
  62   }
  63
  64   return false;
  65 }
  66
  67
  68 /// LinkInLibrary - links one library into the HeadModule.
  69 ///
  70 bool Linker::LinkInLibrary(const std::string& Lib, bool& is_native) {
  71   is_native = false;
  72   // Determine where this library lives.
  73   sys::Path Pathname = FindLib(Lib);
  74   if (Pathname.isEmpty())
  75     return warning("Cannot find library '" + Lib + "'");
  76
  77   // If its an archive, try to link it in
  78   std::string Magic;
  79   Pathname.getMagicNumber(Magic, 64);
  80   switch (sys::IdentifyFileType(Magic.c_str(), 64)) {
  81     default: assert(0 && "Bad file type identification");
  82     case sys::Unknown_FileType:
  83       return warning("Supposed library '" + Lib + "' isn't a library.");
  84
  85     case sys::Bytecode_FileType:
  86     case sys::Bitcode_FileType:
  87     case sys::CompressedBytecode_FileType:
  88       // LLVM ".so" file.
  89       if (LinkInFile(Pathname, is_native))
  90         return error("Cannot link file '" + Pathname.toString() + "'");
  91       break;
  92
  93     case sys::Archive_FileType:
  94       if (LinkInArchive(Pathname, is_native))
  95         return error("Cannot link archive '" + Pathname.toString() + "'");
  96       break;
  97
  98     case sys::ELF_Relocatable_FileType:
  99     case sys::ELF_SharedObject_FileType:
 100     case sys::Mach_O_Object_FileType:
 101     case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
 102     case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
 103     case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
 104     case sys::COFF_FileType:
 105       is_native = true;
 106       break;
 107   }
 108   return false;
 109 }
 110
 111 /// LinkLibraries - takes the specified library files and links them into the
 112 /// main bytecode object file.
 113 ///
 114 /// Inputs:
 115 ///  Libraries  - The list of libraries to link into the module.
 116 ///
 117 /// Return value:
 118 ///  FALSE - No error.
 119 ///  TRUE  - Error.
 120 ///
 121 bool Linker::LinkInLibraries(const std::vector<std::string> &Libraries) {
 122
 123   // Process the set of libraries we've been provided.
 124   bool is_native = false;
 125   for (unsigned i = 0; i < Libraries.size(); ++i)
 126     if (LinkInLibrary(Libraries[i], is_native))
 127       return true;
 128
 129   // At this point we have processed all the libraries provided to us. Since
 130   // we have an aggregated module at this point, the dependent libraries in
 131   // that module should also be aggregated with duplicates eliminated. This is
 132   // now the time to process the dependent libraries to resolve any remaining
 133   // symbols.
 134   const Module::LibraryListType& DepLibs = Composite->getLibraries();
 135   for (Module::LibraryListType::const_iterator I = DepLibs.begin(),
 136          E = DepLibs.end(); I != E; ++I)
 137     if (LinkInLibrary(*I, is_native))
 138       return true;
 139
 140   return false;
 141 }
 142
 143 /// LinkInFile - opens a bytecode file and links in all objects which
 144 /// provide symbols that are currently undefined.
 145 ///
 146 /// Inputs:
 147 ///  File - The pathname of the bytecode file.
 148 ///
 149 /// Outputs:
 150 ///  ErrorMessage - A C++ string detailing what error occurred, if any.
 151 ///
 152 /// Return Value:
 153 ///  TRUE  - An error occurred.
 154 ///  FALSE - No errors.
 155 ///
 156 bool Linker::LinkInFile(const sys::Path &File, bool &is_native) {
 157   is_native = false;
 158   // Make sure we can at least read the file
 159   if (!File.canRead())
 160     return error("Cannot find linker input '" + File.toString() + "'");
 161
 162   // If its an archive, try to link it in
 163   std::string Magic;
 164   File.getMagicNumber(Magic, 64);
 165   switch (sys::IdentifyFileType(Magic.c_str(), 64)) {
 166     default: assert(0 && "Bad file type identification");
 167     case sys::Unknown_FileType:
 168       return warning("Supposed object file '" + File.toString() +
 169                      "' not recognized as such");
 170
 171     case sys::Archive_FileType:
 172       // A user may specify an ar archive without -l, perhaps because it
 173       // is not installed as a library. Detect that and link the archive.
 174       verbose("Linking archive file '" + File.toString() + "'");
 175       if (LinkInArchive(File, is_native))
 176         return error("Cannot link archive '" + File.toString() + "'");
 177       break;
 178
 179     case sys::Bitcode_FileType:
 180     case sys::Bytecode_FileType:
 181     case sys::CompressedBytecode_FileType: {
 182       verbose("Linking bytecode file '" + File.toString() + "'");
 183       std::auto_ptr<Module> M(LoadObject(File));
 184       if (M.get() == 0)
 185         return error("Cannot load file '" + File.toString() + "'" + Error);
 186       if (LinkInModule(M.get()))
 187         return error("Cannot link file '" + File.toString() + "'" + Error);
 188
 189       verbose("Linked in file '" + File.toString() + "'");
 190       break;
 191     }
 192
 193     case sys::ELF_Relocatable_FileType:
 194     case sys::ELF_SharedObject_FileType:
 195     case sys::Mach_O_Object_FileType:
 196     case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
 197     case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
 198     case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
 199     case sys::COFF_FileType:
 200       is_native = true;
 201       break;
 202   }
 203   return false;
 204 }
 205
 206 /// LinkFiles - takes a module and a list of files and links them all together.
 207 /// It locates the file either in the current directory, as its absolute
 208 /// or relative pathname, or as a file somewhere in LLVM_LIB_SEARCH_PATH.
 209 ///
 210 /// Inputs:
 211 ///  Files      - A vector of sys::Path indicating the LLVM bytecode filenames
 212 ///               to be linked.  The names can refer to a mixture of pure LLVM
 213 ///               bytecode files and archive (ar) formatted files.
 214 ///
 215 /// Return value:
 216 ///  FALSE - No errors.
 217 ///  TRUE  - Some error occurred.
 218 ///
 219 bool Linker::LinkInFiles(const std::vector<sys::Path> &Files) {
 220   bool is_native;
 221   for (unsigned i = 0; i < Files.size(); ++i)
 222     if (LinkInFile(Files[i], is_native))
 223       return true;
 224   return false;
 225 }