aboutsummaryrefslogtreecommitdiffstats
path: root/lib/Linker/LinkItems.cpp
blob: 52a0d175a5cdd8bd66a81b04b05279bc46eea4a4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
//===- lib/Linker/LinkItems.cpp - Link LLVM objects and libraries ---------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains routines to handle linking together LLVM bitcode files,
// and to handle annoying things like static libraries.
//
//===----------------------------------------------------------------------===//

#include "llvm/Linker.h"
#include "llvm/Module.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/system_error.h"
using namespace llvm;

// LinkItems - This function is the main entry point into linking. It takes a
// list of LinkItem which indicates the order the files should be linked and
// how each file should be treated (plain file or with library search). The
// function only links bitcode and produces a result list of items that are
// native objects. 
bool
Linker::LinkInItems(const ItemList& Items, ItemList& NativeItems) {
  // Clear the NativeItems just in case
  NativeItems.clear();

  // For each linkage item ...
  for (ItemList::const_iterator I = Items.begin(), E = Items.end();
       I != E; ++I) {
    if (I->second) {
      // Link in the library suggested.
      bool is_native = false;
      if (LinkInLibrary(I->first, is_native))
        return true;
      if (is_native)
        NativeItems.push_back(*I);
    } else {
      // Link in the file suggested
      bool is_native = false;
      if (LinkInFile(sys::Path(I->first), is_native))
        return true;
      if (is_native)
        NativeItems.push_back(*I);
    }
  }

  // At this point we have processed all the link items provided to us. Since
  // we have an aggregated module at this point, the dependent libraries in
  // that module should also be aggregated with duplicates eliminated. This is
  // now the time to process the dependent libraries to resolve any remaining
  // symbols.
  bool is_native;
  for (Module::lib_iterator I = Composite->lib_begin(),
         E = Composite->lib_end(); I != E; ++I) {
    if(LinkInLibrary(*I, is_native))
      return true;
    if (is_native)
      NativeItems.push_back(std::make_pair(*I, true));
  }

  return false;
}


/// LinkInLibrary - links one library into the HeadModule.
///
bool Linker::LinkInLibrary(StringRef Lib, bool& is_native) {
  is_native = false;
  // Determine where this library lives.
  sys::Path Pathname = FindLib(Lib);
  if (Pathname.isEmpty())
    return error("Cannot find library '" + Lib.str() + "'");

  // If its an archive, try to link it in
  std::string Magic;
  Pathname.getMagicNumber(Magic, 64);
  switch (sys::IdentifyFileType(Magic.c_str(), 64)) {
    default: llvm_unreachable("Bad file type identification");
    case sys::Unknown_FileType:
      return warning("Supposed library '" + Lib.str() + "' isn't a library.");

    case sys::Bitcode_FileType:
      // LLVM ".so" file.
      if (LinkInFile(Pathname, is_native))
        return true;
      break;

    case sys::Archive_FileType:
      if (LinkInArchive(Pathname, is_native))
        return error("Cannot link archive '" + Pathname.str() + "'");
      break;

    case sys::ELF_Relocatable_FileType:
    case sys::ELF_SharedObject_FileType:
    case sys::Mach_O_Object_FileType:
    case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
    case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
    case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
    case sys::COFF_FileType:
      is_native = true;
      break;
  }
  return false;
}

/// LinkLibraries - takes the specified library files and links them into the
/// main bitcode object file.
///
/// Inputs:
///  Libraries  - The list of libraries to link into the module.
///
/// Return value:
///  FALSE - No error.
///  TRUE  - Error.
///
bool Linker::LinkInLibraries(const std::vector<std::string> &Libraries) {

  // Process the set of libraries we've been provided.
  bool is_native = false;
  for (unsigned i = 0; i < Libraries.size(); ++i)
    if (LinkInLibrary(Libraries[i], is_native))
      return true;

  // At this point we have processed all the libraries provided to us. Since
  // we have an aggregated module at this point, the dependent libraries in
  // that module should also be aggregated with duplicates eliminated. This is
  // now the time to process the dependent libraries to resolve any remaining
  // symbols.
  const Module::LibraryListType& DepLibs = Composite->getLibraries();
  for (Module::LibraryListType::const_iterator I = DepLibs.begin(),
         E = DepLibs.end(); I != E; ++I)
    if (LinkInLibrary(*I, is_native))
      return true;

  return false;
}

/// LinkInFile - opens a bitcode file and links in all objects which
/// provide symbols that are currently undefined.
///
/// Inputs:
///  File - The pathname of the bitcode file.
///
/// Outputs:
///  ErrorMessage - A C++ string detailing what error occurred, if any.
///
/// Return Value:
///  TRUE  - An error occurred.
///  FALSE - No errors.
///
bool Linker::LinkInFile(const sys::Path &File, bool &is_native) {
  is_native = false;
  
  // Check for a file of name "-", which means "read standard input"
  if (File.str() == "-") {
    std::auto_ptr<Module> M;
    OwningPtr<MemoryBuffer> Buffer;
    error_code ec;
    if (!(ec = MemoryBuffer::getSTDIN(Buffer))) {
      if (!Buffer->getBufferSize()) {
        Error = "standard input is empty";
      } else {
        M.reset(ParseBitcodeFile(Buffer.get(), Context, &Error));
        if (M.get())
          if (!LinkInModule(M.get(), &Error))
            return false;
      }
    }
    return error("Cannot link stdin: " + ec.message());
  }

  // Determine what variety of file it is.
  std::string Magic;
  if (!File.getMagicNumber(Magic, 64))
    return error("Cannot find linker input '" + File.str() + "'");

  switch (sys::IdentifyFileType(Magic.c_str(), 64)) {
    default: llvm_unreachable("Bad file type identification");
    case sys::Unknown_FileType:
      return warning("Ignoring file '" + File.str() + 
                   "' because does not contain bitcode.");

    case sys::Archive_FileType:
      // A user may specify an ar archive without -l, perhaps because it
      // is not installed as a library. Detect that and link the archive.
      if (LinkInArchive(File, is_native))
        return true;
      break;

    case sys::Bitcode_FileType: {
      verbose("Linking bitcode file '" + File.str() + "'");
      std::auto_ptr<Module> M(LoadObject(File));
      if (M.get() == 0)
        return error("Cannot load file '" + File.str() + "': " + Error);
      if (LinkInModule(M.get(), &Error))
        return error("Cannot link file '" + File.str() + "': " + Error);

      verbose("Linked in file '" + File.str() + "'");
      break;
    }

    case sys::ELF_Relocatable_FileType:
    case sys::ELF_SharedObject_FileType:
    case sys::Mach_O_Object_FileType:
    case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
    case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
    case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
    case sys::COFF_FileType:
      is_native = true;
      break;
  }
  return false;
}

/// LinkFiles - takes a module and a list of files and links them all together.
/// It locates the file either in the current directory, as its absolute
/// or relative pathname, or as a file somewhere in LLVM_LIB_SEARCH_PATH.
///
/// Inputs:
///  Files      - A vector of sys::Path indicating the LLVM bitcode filenames
///               to be linked.  The names can refer to a mixture of pure LLVM
///               bitcode files and archive (ar) formatted files.
///
/// Return value:
///  FALSE - No errors.
///  TRUE  - Some error occurred.
///
bool Linker::LinkInFiles(const std::vector<sys::Path> &Files) {
  bool is_native;
  for (unsigned i = 0; i < Files.size(); ++i)
    if (LinkInFile(Files[i], is_native))
      return true;
  return false;
}