1 //===- Linker.cpp - Link together LLVM objects and libraries --------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains routines to handle linking together LLVM bytecode files,
11 // and to handle annoying things like static libraries.
13 //===----------------------------------------------------------------------===//
16 #include "llvm/Module.h"
17 #include "llvm/PassManager.h"
18 #include "llvm/Bytecode/Reader.h"
19 #include "llvm/Bytecode/WriteBytecodePass.h"
20 #include "llvm/Target/TargetData.h"
21 #include "llvm/Transforms/IPO.h"
22 #include "llvm/Transforms/Scalar.h"
23 #include "llvm/Transforms/Utils/Linker.h"
24 #include "Support/CommandLine.h"
25 #include "Support/FileUtilities.h"
26 #include "Support/Signals.h"
27 #include "Support/SystemUtils.h"
35 /// FindLib - Try to convert Filename into the name of a file that we can open,
36 /// if it does not already name a file we can open, by first trying to open
37 /// Filename, then libFilename.<suffix> for each of a set of several common
38 /// library suffixes, in each of the directories in Paths and the directory
39 /// named by the value of the environment variable LLVM_LIB_SEARCH_PATH. Returns
40 /// an empty string if no matching file can be found.
42 std::string FindLib(const std::string &Filename,
43 const std::vector<std::string> &Paths,
44 bool SharedObjectOnly) {
45 // Determine if the pathname can be found as it stands.
46 if (FileOpenable(Filename))
49 // If that doesn't work, convert the name into a library name.
50 std::string LibName = "lib" + Filename;
52 // Iterate over the directories in Paths to see if we can find the library
54 for (unsigned Index = 0; Index != Paths.size(); ++Index) {
55 std::string Directory = Paths[Index] + "/";
57 if (!SharedObjectOnly && FileOpenable(Directory + LibName + ".bc"))
58 return Directory + LibName + ".bc";
60 if (FileOpenable(Directory + LibName + ".so"))
61 return Directory + LibName + ".so";
63 if (!SharedObjectOnly && FileOpenable(Directory + LibName + ".a"))
64 return Directory + LibName + ".a";
67 // One last hope: Check LLVM_LIB_SEARCH_PATH.
68 char *SearchPath = getenv("LLVM_LIB_SEARCH_PATH");
69 if (SearchPath == NULL)
72 LibName = std::string(SearchPath) + "/" + LibName;
73 if (FileOpenable(LibName))
79 /// GetAllDefinedSymbols - Modifies its parameter DefinedSymbols to contain the
80 /// name of each externally-visible symbol defined in M.
82 void GetAllDefinedSymbols(Module *M, std::set<std::string> &DefinedSymbols) {
83 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
84 if (I->hasName() && !I->isExternal() && !I->hasInternalLinkage())
85 DefinedSymbols.insert(I->getName());
86 for (Module::giterator I = M->gbegin(), E = M->gend(); I != E; ++I)
87 if (I->hasName() && !I->isExternal() && !I->hasInternalLinkage())
88 DefinedSymbols.insert(I->getName());
91 /// GetAllUndefinedSymbols - calculates the set of undefined symbols that still
92 /// exist in an LLVM module. This is a bit tricky because there may be two
93 /// symbols with the same name but different LLVM types that will be resolved to
94 /// each other but aren't currently (thus we need to treat it as resolved).
97 /// M - The module in which to find undefined symbols.
100 /// UndefinedSymbols - A set of C++ strings containing the name of all
101 /// undefined symbols.
104 GetAllUndefinedSymbols(Module *M, std::set<std::string> &UndefinedSymbols) {
105 std::set<std::string> DefinedSymbols;
106 UndefinedSymbols.clear(); // Start out empty
108 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
111 UndefinedSymbols.insert(I->getName());
112 else if (!I->hasInternalLinkage())
113 DefinedSymbols.insert(I->getName());
115 for (Module::giterator I = M->gbegin(), E = M->gend(); I != E; ++I)
118 UndefinedSymbols.insert(I->getName());
119 else if (!I->hasInternalLinkage())
120 DefinedSymbols.insert(I->getName());
123 // Prune out any defined symbols from the undefined symbols set...
124 for (std::set<std::string>::iterator I = UndefinedSymbols.begin();
125 I != UndefinedSymbols.end(); )
126 if (DefinedSymbols.count(*I))
127 UndefinedSymbols.erase(I++); // This symbol really is defined!
129 ++I; // Keep this symbol in the undefined symbols list
133 /// LoadObject - Read in and parse the bytecode file named by FN and return the
134 /// module it contains (wrapped in an auto_ptr), or 0 and set ErrorMessage if an
137 std::auto_ptr<Module> LoadObject(const std::string &FN,
138 std::string &ErrorMessage) {
139 std::string ParserErrorMessage;
140 Module *Result = ParseBytecodeFile(FN, &ParserErrorMessage);
141 if (Result) return std::auto_ptr<Module>(Result);
142 ErrorMessage = "Bytecode file '" + FN + "' could not be loaded";
143 if (ParserErrorMessage.size()) ErrorMessage += ": " + ParserErrorMessage;
144 return std::auto_ptr<Module>();
147 /// LinkInArchive - opens an archive library and link in all objects which
148 /// provide symbols that are currently undefined.
151 /// M - The module in which to link the archives.
152 /// Filename - The pathname of the archive.
153 /// Verbose - Flags whether verbose messages should be printed.
156 /// ErrorMessage - A C++ string detailing what error occurred, if any.
159 /// TRUE - An error occurred.
160 /// FALSE - No errors.
162 static bool LinkInArchive(Module *M,
163 const std::string &Filename,
164 std::string &ErrorMessage,
167 // Find all of the symbols currently undefined in the bytecode program.
168 // If all the symbols are defined, the program is complete, and there is
169 // no reason to link in any archive files.
170 std::set<std::string> UndefinedSymbols;
171 GetAllUndefinedSymbols(M, UndefinedSymbols);
172 if (UndefinedSymbols.empty()) {
173 if (Verbose) std::cerr << " No symbols undefined, don't link library!\n";
174 return false; // No need to link anything in!
177 // Load in the archive objects.
178 if (Verbose) std::cerr << " Loading archive file '" << Filename << "'\n";
179 std::vector<Module*> Objects;
180 if (ReadArchiveFile(Filename, Objects, &ErrorMessage))
183 // Figure out which symbols are defined by all of the modules in the archive.
184 std::vector<std::set<std::string> > DefinedSymbols;
185 DefinedSymbols.resize(Objects.size());
186 for (unsigned i = 0; i != Objects.size(); ++i) {
187 GetAllDefinedSymbols(Objects[i], DefinedSymbols[i]);
190 // While we are linking in object files, loop.
195 for (unsigned i = 0; i != Objects.size(); ++i) {
196 // Consider whether we need to link in this module... we only need to
197 // link it in if it defines some symbol which is so far undefined.
199 const std::set<std::string> &DefSymbols = DefinedSymbols[i];
201 bool ObjectRequired = false;
202 for (std::set<std::string>::iterator I = UndefinedSymbols.begin(),
203 E = UndefinedSymbols.end(); I != E; ++I)
204 if (DefSymbols.count(*I)) {
206 std::cerr << " Found object '"
207 << Objects[i]->getModuleIdentifier ()
208 << "' providing symbol '" << *I << "'...\n";
209 ObjectRequired = true;
213 // We DO need to link this object into the program...
214 if (ObjectRequired) {
215 if (LinkModules(M, Objects[i], &ErrorMessage))
216 return true; // Couldn't link in the right object file...
218 // Since we have linked in this object, delete it from the list of
219 // objects to consider in this archive file.
220 std::swap(Objects[i], Objects.back());
221 std::swap(DefinedSymbols[i], DefinedSymbols.back());
223 DefinedSymbols.pop_back();
224 --i; // Do not skip an entry
226 // The undefined symbols set should have shrunk.
227 GetAllUndefinedSymbols(M, UndefinedSymbols);
228 Linked = true; // We have linked something in!
236 /// LinkInFile - opens a bytecode file and links in all objects which
237 /// provide symbols that are currently undefined.
240 /// HeadModule - The module in which to link the bytecode file.
241 /// Filename - The pathname of the bytecode file.
242 /// Verbose - Flags whether verbose messages should be printed.
245 /// ErrorMessage - A C++ string detailing what error occurred, if any.
248 /// TRUE - An error occurred.
249 /// FALSE - No errors.
251 static bool LinkInFile(Module *HeadModule,
252 const std::string &Filename,
253 std::string &ErrorMessage,
256 std::auto_ptr<Module> M(LoadObject(Filename, ErrorMessage));
257 if (M.get() == 0) return true;
258 bool Result = LinkModules(HeadModule, M.get(), &ErrorMessage);
259 if (Verbose) std::cerr << "Linked in bytecode file '" << Filename << "'\n";
263 /// LinkFiles - takes a module and a list of files and links them all together.
264 /// It locates the file either in the current directory, as its absolute
265 /// or relative pathname, or as a file somewhere in LLVM_LIB_SEARCH_PATH.
268 /// progname - The name of the program (infamous argv[0]).
269 /// HeadModule - The module under which all files will be linked.
270 /// Files - A vector of C++ strings indicating the LLVM bytecode filenames
271 /// to be linked. The names can refer to a mixture of pure LLVM
272 /// bytecode files and archive (ar) formatted files.
273 /// Verbose - Flags whether verbose output should be printed while linking.
276 /// HeadModule - The module will have the specified LLVM bytecode files linked
280 /// FALSE - No errors.
281 /// TRUE - Some error occurred.
283 bool LinkFiles(const char *progname,
285 const std::vector<std::string> &Files,
288 // String in which to receive error messages.
289 std::string ErrorMessage;
291 // Full pathname of the file
292 std::string Pathname;
294 // Get the library search path from the environment
295 char *SearchPath = getenv("LLVM_LIB_SEARCH_PATH");
297 for (unsigned i = 0; i < Files.size(); ++i) {
298 // Determine where this file lives.
299 if (FileOpenable(Files[i])) {
302 if (SearchPath == NULL) {
303 std::cerr << progname << ": Cannot find linker input file '"
304 << Files[i] << "'\n";
305 std::cerr << progname
306 << ": Warning: Your LLVM_LIB_SEARCH_PATH is unset.\n";
310 Pathname = std::string(SearchPath)+"/"+Files[i];
311 if (!FileOpenable(Pathname)) {
312 std::cerr << progname << ": Cannot find linker input file '"
313 << Files[i] << "'\n";
318 // A user may specify an ar archive without -l, perhaps because it
319 // is not installed as a library. Detect that and link the library.
320 if (IsArchive(Pathname)) {
322 std::cerr << "Trying to link archive '" << Pathname << "'\n";
324 if (LinkInArchive(HeadModule, Pathname, ErrorMessage, Verbose)) {
325 PrintAndReturn(progname, ErrorMessage,
326 ": Error linking in archive '" + Pathname + "'");
329 } else if (IsBytecode(Pathname)) {
331 std::cerr << "Trying to link bytecode file '" << Pathname << "'\n";
333 if (LinkInFile(HeadModule, Pathname, ErrorMessage, Verbose)) {
334 PrintAndReturn(progname, ErrorMessage,
335 ": Error linking in bytecode file '" + Pathname + "'");
344 /// LinkLibraries - takes the specified library files and links them into the
345 /// main bytecode object file.
348 /// progname - The name of the program (infamous argv[0]).
349 /// HeadModule - The module into which all necessary libraries will be linked.
350 /// Libraries - The list of libraries to link into the module.
351 /// LibPaths - The list of library paths in which to find libraries.
352 /// Verbose - Flags whether verbose messages should be printed.
353 /// Native - Flags whether native code is being generated.
356 /// HeadModule - The module will have all necessary libraries linked in.
359 /// FALSE - No error.
362 bool LinkLibraries(const char *progname,
364 const std::vector<std::string> &Libraries,
365 const std::vector<std::string> &LibPaths,
369 // String in which to receive error messages.
370 std::string ErrorMessage;
372 for (unsigned i = 0; i < Libraries.size(); ++i) {
373 // Determine where this library lives.
374 std::string Pathname = FindLib(Libraries[i], LibPaths);
375 if (Pathname.empty()) {
376 // If the pathname does not exist, then continue to the next one if
377 // we're doing a native link and give an error if we're doing a bytecode
380 PrintAndReturn(progname, "Cannot find library -l" + Libraries[i]
386 // A user may specify an ar archive without -l, perhaps because it
387 // is not installed as a library. Detect that and link the library.
388 if (IsArchive(Pathname)) {
390 std::cerr << "Trying to link archive '" << Pathname << "' (-l"
391 << Libraries[i] << ")\n";
393 if (LinkInArchive(HeadModule, Pathname, ErrorMessage, Verbose)) {
394 PrintAndReturn(progname, ErrorMessage,
395 ": Error linking in archive '" + Pathname
396 + "' (-l" + Libraries[i] + ")");
399 } else if (IsBytecode(Pathname)) {
401 std::cerr << "Trying to link bytecode file '" << Pathname
402 << "' (-l" << Libraries[i] << ")\n";
404 if (LinkInFile(HeadModule, Pathname, ErrorMessage, Verbose)) {
405 PrintAndReturn(progname, ErrorMessage,
406 ": error linking in bytecode file '" + Pathname
407 + "' (-l" + Libraries[i] + ")");
416 } // End llvm namespace