xref: /freebsd/contrib/llvm-project/lld/MachO/Driver.cpp (revision fe815331bb40604ba31312acf7e4619674631777) 
1 //===- Driver.cpp ---------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "Driver.h"
10 #include "Config.h"
11 #include "InputFiles.h"
12 #include "OutputSection.h"
13 #include "OutputSegment.h"
14 #include "SymbolTable.h"
15 #include "Symbols.h"
16 #include "Target.h"
17 #include "Writer.h"
18 
19 #include "lld/Common/Args.h"
20 #include "lld/Common/Driver.h"
21 #include "lld/Common/ErrorHandler.h"
22 #include "lld/Common/LLVM.h"
23 #include "lld/Common/Memory.h"
24 #include "lld/Common/Version.h"
25 #include "llvm/ADT/DenseSet.h"
26 #include "llvm/ADT/StringExtras.h"
27 #include "llvm/ADT/StringRef.h"
28 #include "llvm/BinaryFormat/MachO.h"
29 #include "llvm/BinaryFormat/Magic.h"
30 #include "llvm/Object/Archive.h"
31 #include "llvm/Option/ArgList.h"
32 #include "llvm/Option/Option.h"
33 #include "llvm/Support/Host.h"
34 #include "llvm/Support/MemoryBuffer.h"
35 #include "llvm/Support/Path.h"
36 
37 using namespace llvm;
38 using namespace llvm::MachO;
39 using namespace llvm::sys;
40 using namespace llvm::opt;
41 using namespace lld;
42 using namespace lld::macho;
43 
44 Configuration *lld::macho::config;
45 
46 // Create prefix string literals used in Options.td
47 #define PREFIX(NAME, VALUE) const char *NAME[] = VALUE;
48 #include "Options.inc"
49 #undef PREFIX
50 
51 // Create table mapping all options defined in Options.td
52 static const opt::OptTable::Info optInfo[] = {
53 #define OPTION(X1, X2, ID, KIND, GROUP, ALIAS, X7, X8, X9, X10, X11, X12)      \
54   {X1, X2, X10,         X11,         OPT_##ID, opt::Option::KIND##Class,       \
55    X9, X8, OPT_##GROUP, OPT_##ALIAS, X7,       X12},
56 #include "Options.inc"
57 #undef OPTION
58 };
59 
60 MachOOptTable::MachOOptTable() : OptTable(optInfo) {}
61 
62 opt::InputArgList MachOOptTable::parse(ArrayRef<const char *> argv) {
63   // Make InputArgList from string vectors.
64   unsigned missingIndex;
65   unsigned missingCount;
66   SmallVector<const char *, 256> vec(argv.data(), argv.data() + argv.size());
67 
68   opt::InputArgList args = ParseArgs(vec, missingIndex, missingCount);
69 
70   if (missingCount)
71     error(Twine(args.getArgString(missingIndex)) + ": missing argument");
72 
73   for (opt::Arg *arg : args.filtered(OPT_UNKNOWN))
74     error("unknown argument: " + arg->getSpelling());
75   return args;
76 }
77 
78 void MachOOptTable::printHelp(const char *argv0, bool showHidden) const {
79   PrintHelp(lld::outs(), (std::string(argv0) + " [options] file...").c_str(),
80             "LLVM Linker", showHidden);
81   lld::outs() << "\n";
82 }
83 
84 static Optional<std::string> findLibrary(StringRef name) {
85   std::string stub = (llvm::Twine("lib") + name + ".tbd").str();
86   std::string shared = (llvm::Twine("lib") + name + ".dylib").str();
87   std::string archive = (llvm::Twine("lib") + name + ".a").str();
88   llvm::SmallString<260> location;
89 
90   for (StringRef dir : config->librarySearchPaths) {
91     for (StringRef library : {stub, shared, archive}) {
92       location = dir;
93       llvm::sys::path::append(location, library);
94       if (fs::exists(location))
95         return location.str().str();
96     }
97   }
98   return {};
99 }
100 
101 static TargetInfo *createTargetInfo(opt::InputArgList &args) {
102   StringRef arch = args.getLastArgValue(OPT_arch, "x86_64");
103   config->arch = llvm::MachO::getArchitectureFromName(
104       args.getLastArgValue(OPT_arch, arch));
105   switch (config->arch) {
106   case llvm::MachO::AK_x86_64:
107   case llvm::MachO::AK_x86_64h:
108     return createX86_64TargetInfo();
109   default:
110     fatal("missing or unsupported -arch " + arch);
111   }
112 }
113 
114 static bool isDirectory(StringRef option, StringRef path) {
115   if (!fs::exists(path)) {
116     warn("directory not found for option -" + option + path);
117     return false;
118   } else if (!fs::is_directory(path)) {
119     warn("option -" + option + path + " references a non-directory path");
120     return false;
121   }
122   return true;
123 }
124 
125 static void getSearchPaths(std::vector<StringRef> &paths, unsigned optionCode,
126                            opt::InputArgList &args,
127                            const SmallVector<StringRef, 2> &systemPaths) {
128   StringRef optionLetter{(optionCode == OPT_F ? "F" : "L")};
129   for (auto const &path : args::getStrings(args, optionCode)) {
130     if (isDirectory(optionLetter, path))
131       paths.push_back(path);
132   }
133   if (!args.hasArg(OPT_Z) && Triple(sys::getProcessTriple()).isOSDarwin()) {
134     for (auto const &path : systemPaths) {
135       if (isDirectory(optionLetter, path))
136         paths.push_back(path);
137     }
138   }
139 }
140 
141 static void getLibrarySearchPaths(std::vector<StringRef> &paths,
142                                   opt::InputArgList &args) {
143   getSearchPaths(paths, OPT_L, args, {"/usr/lib", "/usr/local/lib"});
144 }
145 
146 static void getFrameworkSearchPaths(std::vector<StringRef> &paths,
147                                     opt::InputArgList &args) {
148   getSearchPaths(paths, OPT_F, args,
149                  {"/Library/Frameworks", "/System/Library/Frameworks"});
150 }
151 
152 static void addFile(StringRef path) {
153   Optional<MemoryBufferRef> buffer = readFile(path);
154   if (!buffer)
155     return;
156   MemoryBufferRef mbref = *buffer;
157 
158   switch (identify_magic(mbref.getBuffer())) {
159   case file_magic::archive: {
160     std::unique_ptr<object::Archive> file = CHECK(
161         object::Archive::create(mbref), path + ": failed to parse archive");
162 
163     if (!file->isEmpty() && !file->hasSymbolTable())
164       error(path + ": archive has no index; run ranlib to add one");
165 
166     inputFiles.push_back(make<ArchiveFile>(std::move(file)));
167     break;
168   }
169   case file_magic::macho_object:
170     inputFiles.push_back(make<ObjFile>(mbref));
171     break;
172   case file_magic::macho_dynamically_linked_shared_lib:
173     inputFiles.push_back(make<DylibFile>(mbref));
174     break;
175   case file_magic::tapi_file: {
176     llvm::Expected<std::unique_ptr<llvm::MachO::InterfaceFile>> result =
177         TextAPIReader::get(mbref);
178     if (!result)
179       return;
180 
181     inputFiles.push_back(make<DylibFile>(std::move(*result)));
182     break;
183   }
184   default:
185     error(path + ": unhandled file type");
186   }
187 }
188 
189 static std::array<StringRef, 6> archNames{"arm",    "arm64", "i386",
190                                           "x86_64", "ppc",   "ppc64"};
191 static bool isArchString(StringRef s) {
192   static DenseSet<StringRef> archNamesSet(archNames.begin(), archNames.end());
193   return archNamesSet.find(s) != archNamesSet.end();
194 }
195 
196 // An order file has one entry per line, in the following format:
197 //
198 //   <arch>:<object file>:<symbol name>
199 //
200 // <arch> and <object file> are optional. If not specified, then that entry
201 // matches any symbol of that name.
202 //
203 // If a symbol is matched by multiple entries, then it takes the lowest-ordered
204 // entry (the one nearest to the front of the list.)
205 //
206 // The file can also have line comments that start with '#'.
207 void parseOrderFile(StringRef path) {
208   Optional<MemoryBufferRef> buffer = readFile(path);
209   if (!buffer) {
210     error("Could not read order file at " + path);
211     return;
212   }
213 
214   MemoryBufferRef mbref = *buffer;
215   size_t priority = std::numeric_limits<size_t>::max();
216   for (StringRef rest : args::getLines(mbref)) {
217     StringRef arch, objectFile, symbol;
218 
219     std::array<StringRef, 3> fields;
220     uint8_t fieldCount = 0;
221     while (rest != "" && fieldCount < 3) {
222       std::pair<StringRef, StringRef> p = getToken(rest, ": \t\n\v\f\r");
223       StringRef tok = p.first;
224       rest = p.second;
225 
226       // Check if we have a comment
227       if (tok == "" || tok[0] == '#')
228         break;
229 
230       fields[fieldCount++] = tok;
231     }
232 
233     switch (fieldCount) {
234     case 3:
235       arch = fields[0];
236       objectFile = fields[1];
237       symbol = fields[2];
238       break;
239     case 2:
240       (isArchString(fields[0]) ? arch : objectFile) = fields[0];
241       symbol = fields[1];
242       break;
243     case 1:
244       symbol = fields[0];
245       break;
246     case 0:
247       break;
248     default:
249       llvm_unreachable("too many fields in order file");
250     }
251 
252     if (!arch.empty()) {
253       if (!isArchString(arch)) {
254         error("invalid arch \"" + arch + "\" in order file: expected one of " +
255               llvm::join(archNames, ", "));
256         continue;
257       }
258 
259       // TODO: Update when we extend support for other archs
260       if (arch != "x86_64")
261         continue;
262     }
263 
264     if (!objectFile.empty() && !objectFile.endswith(".o")) {
265       error("invalid object file name \"" + objectFile +
266             "\" in order file: should end with .o");
267       continue;
268     }
269 
270     if (!symbol.empty()) {
271       SymbolPriorityEntry &entry = config->priorities[symbol];
272       if (!objectFile.empty())
273         entry.objectFiles.insert(std::make_pair(objectFile, priority));
274       else
275         entry.anyObjectFile = std::max(entry.anyObjectFile, priority);
276     }
277 
278     --priority;
279   }
280 }
281 
282 // We expect sub-library names of the form "libfoo", which will match a dylib
283 // with a path of .*/libfoo.dylib.
284 static bool markSubLibrary(StringRef searchName) {
285   for (InputFile *file : inputFiles) {
286     if (auto *dylibFile = dyn_cast<DylibFile>(file)) {
287       StringRef filename = path::filename(dylibFile->getName());
288       if (filename.consume_front(searchName) && filename == ".dylib") {
289         dylibFile->reexport = true;
290         return true;
291       }
292     }
293   }
294   return false;
295 }
296 
297 static void handlePlatformVersion(const opt::Arg *arg) {
298   // TODO: implementation coming very soon ...
299 }
300 
301 static void warnIfDeprecatedOption(const opt::Option &opt) {
302   if (!opt.getGroup().isValid())
303     return;
304   if (opt.getGroup().getID() == OPT_grp_deprecated) {
305     warn("Option `" + opt.getPrefixedName() + "' is deprecated in ld64:");
306     warn(opt.getHelpText());
307   }
308 }
309 
310 static void warnIfUnimplementedOption(const opt::Option &opt) {
311   if (!opt.getGroup().isValid())
312     return;
313   switch (opt.getGroup().getID()) {
314   case OPT_grp_deprecated:
315     // warn about deprecated options elsewhere
316     break;
317   case OPT_grp_undocumented:
318     warn("Option `" + opt.getPrefixedName() +
319          "' is undocumented. Should lld implement it?");
320     break;
321   case OPT_grp_obsolete:
322     warn("Option `" + opt.getPrefixedName() +
323          "' is obsolete. Please modernize your usage.");
324     break;
325   case OPT_grp_ignored:
326     warn("Option `" + opt.getPrefixedName() + "' is ignored.");
327     break;
328   default:
329     warn("Option `" + opt.getPrefixedName() +
330          "' is not yet implemented. Stay tuned...");
331     break;
332   }
333 }
334 
335 bool macho::link(llvm::ArrayRef<const char *> argsArr, bool canExitEarly,
336                  raw_ostream &stdoutOS, raw_ostream &stderrOS) {
337   lld::stdoutOS = &stdoutOS;
338   lld::stderrOS = &stderrOS;
339 
340   stderrOS.enable_colors(stderrOS.has_colors());
341   // TODO: Set up error handler properly, e.g. the errorLimitExceededMsg
342 
343   MachOOptTable parser;
344   opt::InputArgList args = parser.parse(argsArr.slice(1));
345 
346   if (args.hasArg(OPT_help_hidden)) {
347     parser.printHelp(argsArr[0], /*showHidden=*/true);
348     return true;
349   } else if (args.hasArg(OPT_help)) {
350     parser.printHelp(argsArr[0], /*showHidden=*/false);
351     return true;
352   }
353 
354   config = make<Configuration>();
355   symtab = make<SymbolTable>();
356   target = createTargetInfo(args);
357 
358   config->entry = symtab->addUndefined(args.getLastArgValue(OPT_e, "_main"));
359   config->outputFile = args.getLastArgValue(OPT_o, "a.out");
360   config->installName =
361       args.getLastArgValue(OPT_install_name, config->outputFile);
362   getLibrarySearchPaths(config->librarySearchPaths, args);
363   getFrameworkSearchPaths(config->frameworkSearchPaths, args);
364   config->outputType = args.hasArg(OPT_dylib) ? MH_DYLIB : MH_EXECUTE;
365 
366   if (args.hasArg(OPT_v)) {
367     message(getLLDVersion());
368     message(StringRef("Library search paths:") +
369             (config->librarySearchPaths.size()
370                  ? "\n\t" + llvm::join(config->librarySearchPaths, "\n\t")
371                  : ""));
372     message(StringRef("Framework search paths:") +
373             (config->frameworkSearchPaths.size()
374                  ? "\n\t" + llvm::join(config->frameworkSearchPaths, "\n\t")
375                  : ""));
376     freeArena();
377     return !errorCount();
378   }
379 
380   for (const auto &arg : args) {
381     const auto &opt = arg->getOption();
382     warnIfDeprecatedOption(opt);
383     switch (arg->getOption().getID()) {
384     case OPT_INPUT:
385       addFile(arg->getValue());
386       break;
387     case OPT_l: {
388       StringRef name = arg->getValue();
389       if (Optional<std::string> path = findLibrary(name)) {
390         addFile(*path);
391         break;
392       }
393       error("library not found for -l" + name);
394       break;
395     }
396     case OPT_platform_version:
397       handlePlatformVersion(arg);
398       break;
399     case OPT_o:
400     case OPT_dylib:
401     case OPT_e:
402     case OPT_L:
403     case OPT_Z:
404     case OPT_arch:
405       // handled elsewhere
406       break;
407     default:
408       warnIfUnimplementedOption(opt);
409       break;
410     }
411   }
412 
413   // Now that all dylibs have been loaded, search for those that should be
414   // re-exported.
415   for (opt::Arg *arg : args.filtered(OPT_sub_library)) {
416     config->hasReexports = true;
417     StringRef searchName = arg->getValue();
418     if (!markSubLibrary(searchName))
419       error("-sub_library " + searchName + " does not match a supplied dylib");
420   }
421 
422   StringRef orderFile = args.getLastArgValue(OPT_order_file);
423   if (!orderFile.empty())
424     parseOrderFile(orderFile);
425 
426   if (config->outputType == MH_EXECUTE && !isa<Defined>(config->entry)) {
427     error("undefined symbol: " + config->entry->getName());
428     return false;
429   }
430 
431   createSyntheticSections();
432 
433   // Initialize InputSections.
434   for (InputFile *file : inputFiles) {
435     for (SubsectionMap &map : file->subsections) {
436       for (auto &p : map) {
437         InputSection *isec = p.second;
438         inputSections.push_back(isec);
439       }
440     }
441   }
442 
443   // Write to an output file.
444   writeResult();
445 
446   if (canExitEarly)
447     exitLld(errorCount() ? 1 : 0);
448 
449   freeArena();
450   return !errorCount();
451 }
452