1 //===- DriverUtils.cpp ----------------------------------------------------===//
2 //
3 //                             The LLVM Linker
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file contains utility functions for the driver. Because there
11 // are so many small functions, we created this separate file to make
12 // Driver.cpp less cluttered.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #include "Config.h"
17 #include "Driver.h"
18 #include "Symbols.h"
19 #include "lld/Common/ErrorHandler.h"
20 #include "lld/Common/Memory.h"
21 #include "llvm/ADT/Optional.h"
22 #include "llvm/ADT/StringSwitch.h"
23 #include "llvm/BinaryFormat/COFF.h"
24 #include "llvm/Object/COFF.h"
25 #include "llvm/Object/WindowsResource.h"
26 #include "llvm/Option/Arg.h"
27 #include "llvm/Option/ArgList.h"
28 #include "llvm/Option/Option.h"
29 #include "llvm/Support/CommandLine.h"
30 #include "llvm/Support/FileUtilities.h"
31 #include "llvm/Support/MathExtras.h"
32 #include "llvm/Support/Process.h"
33 #include "llvm/Support/Program.h"
34 #include "llvm/Support/raw_ostream.h"
35 #include "llvm/WindowsManifest/WindowsManifestMerger.h"
36 #include <memory>
37 
38 using namespace llvm::COFF;
39 using namespace llvm;
40 using llvm::sys::Process;
41 
42 namespace lld {
43 namespace coff {
44 namespace {
45 
46 const uint16_t SUBLANG_ENGLISH_US = 0x0409;
47 const uint16_t RT_MANIFEST = 24;
48 
49 class Executor {
50 public:
51   explicit Executor(StringRef S) : Prog(Saver.save(S)) {}
52   void add(StringRef S) { Args.push_back(Saver.save(S)); }
53   void add(std::string &S) { Args.push_back(Saver.save(S)); }
54   void add(Twine S) { Args.push_back(Saver.save(S)); }
55   void add(const char *S) { Args.push_back(Saver.save(S)); }
56 
57   void run() {
58     ErrorOr<std::string> ExeOrErr = sys::findProgramByName(Prog);
59     if (auto EC = ExeOrErr.getError())
60       fatal("unable to find " + Prog + " in PATH: " + EC.message());
61     StringRef Exe = Saver.save(*ExeOrErr);
62     Args.insert(Args.begin(), Exe);
63 
64     std::vector<const char *> Vec;
65     for (StringRef S : Args)
66       Vec.push_back(S.data());
67     Vec.push_back(nullptr);
68 
69     if (sys::ExecuteAndWait(Args[0], Vec.data()) != 0)
70       fatal("ExecuteAndWait failed: " +
71             llvm::join(Args.begin(), Args.end(), " "));
72   }
73 
74 private:
75   StringRef Prog;
76   std::vector<StringRef> Args;
77 };
78 
79 } // anonymous namespace
80 
81 // Returns /machine's value.
82 MachineTypes getMachineType(StringRef S) {
83   MachineTypes MT = StringSwitch<MachineTypes>(S.lower())
84                         .Cases("x64", "amd64", AMD64)
85                         .Cases("x86", "i386", I386)
86                         .Case("arm", ARMNT)
87                         .Case("arm64", ARM64)
88                         .Default(IMAGE_FILE_MACHINE_UNKNOWN);
89   if (MT != IMAGE_FILE_MACHINE_UNKNOWN)
90     return MT;
91   fatal("unknown /machine argument: " + S);
92 }
93 
94 StringRef machineToStr(MachineTypes MT) {
95   switch (MT) {
96   case ARMNT:
97     return "arm";
98   case ARM64:
99     return "arm64";
100   case AMD64:
101     return "x64";
102   case I386:
103     return "x86";
104   default:
105     llvm_unreachable("unknown machine type");
106   }
107 }
108 
109 // Parses a string in the form of "<integer>[,<integer>]".
110 void parseNumbers(StringRef Arg, uint64_t *Addr, uint64_t *Size) {
111   StringRef S1, S2;
112   std::tie(S1, S2) = Arg.split(',');
113   if (S1.getAsInteger(0, *Addr))
114     fatal("invalid number: " + S1);
115   if (Size && !S2.empty() && S2.getAsInteger(0, *Size))
116     fatal("invalid number: " + S2);
117 }
118 
119 // Parses a string in the form of "<integer>[.<integer>]".
120 // If second number is not present, Minor is set to 0.
121 void parseVersion(StringRef Arg, uint32_t *Major, uint32_t *Minor) {
122   StringRef S1, S2;
123   std::tie(S1, S2) = Arg.split('.');
124   if (S1.getAsInteger(0, *Major))
125     fatal("invalid number: " + S1);
126   *Minor = 0;
127   if (!S2.empty() && S2.getAsInteger(0, *Minor))
128     fatal("invalid number: " + S2);
129 }
130 
131 void parseGuard(StringRef FullArg) {
132   SmallVector<StringRef, 1> SplitArgs;
133   FullArg.split(SplitArgs, ",");
134   for (StringRef Arg : SplitArgs) {
135     if (Arg.equals_lower("no"))
136       Config->GuardCF = GuardCFLevel::Off;
137     else if (Arg.equals_lower("nolongjmp"))
138       Config->GuardCF = GuardCFLevel::NoLongJmp;
139     else if (Arg.equals_lower("cf") || Arg.equals_lower("longjmp"))
140       Config->GuardCF = GuardCFLevel::Full;
141     else
142       fatal("invalid argument to /guard: " + Arg);
143   }
144 }
145 
146 // Parses a string in the form of "<subsystem>[,<integer>[.<integer>]]".
147 void parseSubsystem(StringRef Arg, WindowsSubsystem *Sys, uint32_t *Major,
148                     uint32_t *Minor) {
149   StringRef SysStr, Ver;
150   std::tie(SysStr, Ver) = Arg.split(',');
151   *Sys = StringSwitch<WindowsSubsystem>(SysStr.lower())
152     .Case("boot_application", IMAGE_SUBSYSTEM_WINDOWS_BOOT_APPLICATION)
153     .Case("console", IMAGE_SUBSYSTEM_WINDOWS_CUI)
154     .Case("efi_application", IMAGE_SUBSYSTEM_EFI_APPLICATION)
155     .Case("efi_boot_service_driver", IMAGE_SUBSYSTEM_EFI_BOOT_SERVICE_DRIVER)
156     .Case("efi_rom", IMAGE_SUBSYSTEM_EFI_ROM)
157     .Case("efi_runtime_driver", IMAGE_SUBSYSTEM_EFI_RUNTIME_DRIVER)
158     .Case("native", IMAGE_SUBSYSTEM_NATIVE)
159     .Case("posix", IMAGE_SUBSYSTEM_POSIX_CUI)
160     .Case("windows", IMAGE_SUBSYSTEM_WINDOWS_GUI)
161     .Default(IMAGE_SUBSYSTEM_UNKNOWN);
162   if (*Sys == IMAGE_SUBSYSTEM_UNKNOWN)
163     fatal("unknown subsystem: " + SysStr);
164   if (!Ver.empty())
165     parseVersion(Ver, Major, Minor);
166 }
167 
168 // Parse a string of the form of "<from>=<to>".
169 // Results are directly written to Config.
170 void parseAlternateName(StringRef S) {
171   StringRef From, To;
172   std::tie(From, To) = S.split('=');
173   if (From.empty() || To.empty())
174     fatal("/alternatename: invalid argument: " + S);
175   auto It = Config->AlternateNames.find(From);
176   if (It != Config->AlternateNames.end() && It->second != To)
177     fatal("/alternatename: conflicts: " + S);
178   Config->AlternateNames.insert(It, std::make_pair(From, To));
179 }
180 
181 // Parse a string of the form of "<from>=<to>".
182 // Results are directly written to Config.
183 void parseMerge(StringRef S) {
184   StringRef From, To;
185   std::tie(From, To) = S.split('=');
186   if (From.empty() || To.empty())
187     fatal("/merge: invalid argument: " + S);
188   auto Pair = Config->Merge.insert(std::make_pair(From, To));
189   bool Inserted = Pair.second;
190   if (!Inserted) {
191     StringRef Existing = Pair.first->second;
192     if (Existing != To)
193       warn(S + ": already merged into " + Existing);
194   }
195 }
196 
197 static uint32_t parseSectionAttributes(StringRef S) {
198   uint32_t Ret = 0;
199   for (char C : S.lower()) {
200     switch (C) {
201     case 'd':
202       Ret |= IMAGE_SCN_MEM_DISCARDABLE;
203       break;
204     case 'e':
205       Ret |= IMAGE_SCN_MEM_EXECUTE;
206       break;
207     case 'k':
208       Ret |= IMAGE_SCN_MEM_NOT_CACHED;
209       break;
210     case 'p':
211       Ret |= IMAGE_SCN_MEM_NOT_PAGED;
212       break;
213     case 'r':
214       Ret |= IMAGE_SCN_MEM_READ;
215       break;
216     case 's':
217       Ret |= IMAGE_SCN_MEM_SHARED;
218       break;
219     case 'w':
220       Ret |= IMAGE_SCN_MEM_WRITE;
221       break;
222     default:
223       fatal("/section: invalid argument: " + S);
224     }
225   }
226   return Ret;
227 }
228 
229 // Parses /section option argument.
230 void parseSection(StringRef S) {
231   StringRef Name, Attrs;
232   std::tie(Name, Attrs) = S.split(',');
233   if (Name.empty() || Attrs.empty())
234     fatal("/section: invalid argument: " + S);
235   Config->Section[Name] = parseSectionAttributes(Attrs);
236 }
237 
238 // Parses /aligncomm option argument.
239 void parseAligncomm(StringRef S) {
240   StringRef Name, Align;
241   std::tie(Name, Align) = S.split(',');
242   if (Name.empty() || Align.empty()) {
243     error("/aligncomm: invalid argument: " + S);
244     return;
245   }
246   int V;
247   if (Align.getAsInteger(0, V)) {
248     error("/aligncomm: invalid argument: " + S);
249     return;
250   }
251   Config->AlignComm[Name] = std::max(Config->AlignComm[Name], 1 << V);
252 }
253 
254 // Parses a string in the form of "EMBED[,=<integer>]|NO".
255 // Results are directly written to Config.
256 void parseManifest(StringRef Arg) {
257   if (Arg.equals_lower("no")) {
258     Config->Manifest = Configuration::No;
259     return;
260   }
261   if (!Arg.startswith_lower("embed"))
262     fatal("invalid option " + Arg);
263   Config->Manifest = Configuration::Embed;
264   Arg = Arg.substr(strlen("embed"));
265   if (Arg.empty())
266     return;
267   if (!Arg.startswith_lower(",id="))
268     fatal("invalid option " + Arg);
269   Arg = Arg.substr(strlen(",id="));
270   if (Arg.getAsInteger(0, Config->ManifestID))
271     fatal("invalid option " + Arg);
272 }
273 
274 // Parses a string in the form of "level=<string>|uiAccess=<string>|NO".
275 // Results are directly written to Config.
276 void parseManifestUAC(StringRef Arg) {
277   if (Arg.equals_lower("no")) {
278     Config->ManifestUAC = false;
279     return;
280   }
281   for (;;) {
282     Arg = Arg.ltrim();
283     if (Arg.empty())
284       return;
285     if (Arg.startswith_lower("level=")) {
286       Arg = Arg.substr(strlen("level="));
287       std::tie(Config->ManifestLevel, Arg) = Arg.split(" ");
288       continue;
289     }
290     if (Arg.startswith_lower("uiaccess=")) {
291       Arg = Arg.substr(strlen("uiaccess="));
292       std::tie(Config->ManifestUIAccess, Arg) = Arg.split(" ");
293       continue;
294     }
295     fatal("invalid option " + Arg);
296   }
297 }
298 
299 // An RAII temporary file class that automatically removes a temporary file.
300 namespace {
301 class TemporaryFile {
302 public:
303   TemporaryFile(StringRef Prefix, StringRef Extn, StringRef Contents = "") {
304     SmallString<128> S;
305     if (auto EC = sys::fs::createTemporaryFile("lld-" + Prefix, Extn, S))
306       fatal("cannot create a temporary file: " + EC.message());
307     Path = S.str();
308 
309     if (!Contents.empty()) {
310       std::error_code EC;
311       raw_fd_ostream OS(Path, EC, sys::fs::F_None);
312       if (EC)
313         fatal("failed to open " + Path + ": " + EC.message());
314       OS << Contents;
315     }
316   }
317 
318   TemporaryFile(TemporaryFile &&Obj) {
319     std::swap(Path, Obj.Path);
320   }
321 
322   ~TemporaryFile() {
323     if (Path.empty())
324       return;
325     if (sys::fs::remove(Path))
326       fatal("failed to remove " + Path);
327   }
328 
329   // Returns a memory buffer of this temporary file.
330   // Note that this function does not leave the file open,
331   // so it is safe to remove the file immediately after this function
332   // is called (you cannot remove an opened file on Windows.)
333   std::unique_ptr<MemoryBuffer> getMemoryBuffer() {
334     // IsVolatileSize=true forces MemoryBuffer to not use mmap().
335     return CHECK(MemoryBuffer::getFile(Path, /*FileSize=*/-1,
336                                        /*RequiresNullTerminator=*/false,
337                                        /*IsVolatileSize=*/true),
338                  "could not open " + Path);
339   }
340 
341   std::string Path;
342 };
343 }
344 
345 static std::string createDefaultXml() {
346   std::string Ret;
347   raw_string_ostream OS(Ret);
348 
349   // Emit the XML. Note that we do *not* verify that the XML attributes are
350   // syntactically correct. This is intentional for link.exe compatibility.
351   OS << "<?xml version=\"1.0\" standalone=\"yes\"?>\n"
352      << "<assembly xmlns=\"urn:schemas-microsoft-com:asm.v1\"\n"
353      << "          manifestVersion=\"1.0\">\n";
354   if (Config->ManifestUAC) {
355     OS << "  <trustInfo>\n"
356        << "    <security>\n"
357        << "      <requestedPrivileges>\n"
358        << "         <requestedExecutionLevel level=" << Config->ManifestLevel
359        << " uiAccess=" << Config->ManifestUIAccess << "/>\n"
360        << "      </requestedPrivileges>\n"
361        << "    </security>\n"
362        << "  </trustInfo>\n";
363   }
364   if (!Config->ManifestDependency.empty()) {
365     OS << "  <dependency>\n"
366        << "    <dependentAssembly>\n"
367        << "      <assemblyIdentity " << Config->ManifestDependency << " />\n"
368        << "    </dependentAssembly>\n"
369        << "  </dependency>\n";
370   }
371   OS << "</assembly>\n";
372   return OS.str();
373 }
374 
375 static std::string createManifestXmlWithInternalMt(StringRef DefaultXml) {
376   std::unique_ptr<MemoryBuffer> DefaultXmlCopy =
377       MemoryBuffer::getMemBufferCopy(DefaultXml);
378 
379   windows_manifest::WindowsManifestMerger Merger;
380   if (auto E = Merger.merge(*DefaultXmlCopy.get()))
381     fatal("internal manifest tool failed on default xml: " +
382           toString(std::move(E)));
383 
384   for (StringRef Filename : Config->ManifestInput) {
385     std::unique_ptr<MemoryBuffer> Manifest =
386         check(MemoryBuffer::getFile(Filename));
387     if (auto E = Merger.merge(*Manifest.get()))
388       fatal("internal manifest tool failed on file " + Filename + ": " +
389             toString(std::move(E)));
390   }
391 
392   return Merger.getMergedManifest().get()->getBuffer();
393 }
394 
395 static std::string createManifestXmlWithExternalMt(StringRef DefaultXml) {
396   // Create the default manifest file as a temporary file.
397   TemporaryFile Default("defaultxml", "manifest");
398   std::error_code EC;
399   raw_fd_ostream OS(Default.Path, EC, sys::fs::F_Text);
400   if (EC)
401     fatal("failed to open " + Default.Path + ": " + EC.message());
402   OS << DefaultXml;
403   OS.close();
404 
405   // Merge user-supplied manifests if they are given.  Since libxml2 is not
406   // enabled, we must shell out to Microsoft's mt.exe tool.
407   TemporaryFile User("user", "manifest");
408 
409   Executor E("mt.exe");
410   E.add("/manifest");
411   E.add(Default.Path);
412   for (StringRef Filename : Config->ManifestInput) {
413     E.add("/manifest");
414     E.add(Filename);
415   }
416   E.add("/nologo");
417   E.add("/out:" + StringRef(User.Path));
418   E.run();
419 
420   return CHECK(MemoryBuffer::getFile(User.Path), "could not open " + User.Path)
421       .get()
422       ->getBuffer();
423 }
424 
425 static std::string createManifestXml() {
426   std::string DefaultXml = createDefaultXml();
427   if (Config->ManifestInput.empty())
428     return DefaultXml;
429 
430   if (windows_manifest::isAvailable())
431     return createManifestXmlWithInternalMt(DefaultXml);
432 
433   return createManifestXmlWithExternalMt(DefaultXml);
434 }
435 
436 static std::unique_ptr<WritableMemoryBuffer>
437 createMemoryBufferForManifestRes(size_t ManifestSize) {
438   size_t ResSize = alignTo(
439       object::WIN_RES_MAGIC_SIZE + object::WIN_RES_NULL_ENTRY_SIZE +
440           sizeof(object::WinResHeaderPrefix) + sizeof(object::WinResIDs) +
441           sizeof(object::WinResHeaderSuffix) + ManifestSize,
442       object::WIN_RES_DATA_ALIGNMENT);
443   return WritableMemoryBuffer::getNewMemBuffer(ResSize, Config->OutputFile +
444                                                             ".manifest.res");
445 }
446 
447 static void writeResFileHeader(char *&Buf) {
448   memcpy(Buf, COFF::WinResMagic, sizeof(COFF::WinResMagic));
449   Buf += sizeof(COFF::WinResMagic);
450   memset(Buf, 0, object::WIN_RES_NULL_ENTRY_SIZE);
451   Buf += object::WIN_RES_NULL_ENTRY_SIZE;
452 }
453 
454 static void writeResEntryHeader(char *&Buf, size_t ManifestSize) {
455   // Write the prefix.
456   auto *Prefix = reinterpret_cast<object::WinResHeaderPrefix *>(Buf);
457   Prefix->DataSize = ManifestSize;
458   Prefix->HeaderSize = sizeof(object::WinResHeaderPrefix) +
459                        sizeof(object::WinResIDs) +
460                        sizeof(object::WinResHeaderSuffix);
461   Buf += sizeof(object::WinResHeaderPrefix);
462 
463   // Write the Type/Name IDs.
464   auto *IDs = reinterpret_cast<object::WinResIDs *>(Buf);
465   IDs->setType(RT_MANIFEST);
466   IDs->setName(Config->ManifestID);
467   Buf += sizeof(object::WinResIDs);
468 
469   // Write the suffix.
470   auto *Suffix = reinterpret_cast<object::WinResHeaderSuffix *>(Buf);
471   Suffix->DataVersion = 0;
472   Suffix->MemoryFlags = object::WIN_RES_PURE_MOVEABLE;
473   Suffix->Language = SUBLANG_ENGLISH_US;
474   Suffix->Version = 0;
475   Suffix->Characteristics = 0;
476   Buf += sizeof(object::WinResHeaderSuffix);
477 }
478 
479 // Create a resource file containing a manifest XML.
480 std::unique_ptr<MemoryBuffer> createManifestRes() {
481   std::string Manifest = createManifestXml();
482 
483   std::unique_ptr<WritableMemoryBuffer> Res =
484       createMemoryBufferForManifestRes(Manifest.size());
485 
486   char *Buf = Res->getBufferStart();
487   writeResFileHeader(Buf);
488   writeResEntryHeader(Buf, Manifest.size());
489 
490   // Copy the manifest data into the .res file.
491   std::copy(Manifest.begin(), Manifest.end(), Buf);
492   return std::move(Res);
493 }
494 
495 void createSideBySideManifest() {
496   std::string Path = Config->ManifestFile;
497   if (Path == "")
498     Path = Config->OutputFile + ".manifest";
499   std::error_code EC;
500   raw_fd_ostream Out(Path, EC, sys::fs::F_Text);
501   if (EC)
502     fatal("failed to create manifest: " + EC.message());
503   Out << createManifestXml();
504 }
505 
506 // Parse a string in the form of
507 // "<name>[=<internalname>][,@ordinal[,NONAME]][,DATA][,PRIVATE]"
508 // or "<name>=<dllname>.<name>".
509 // Used for parsing /export arguments.
510 Export parseExport(StringRef Arg) {
511   Export E;
512   StringRef Rest;
513   std::tie(E.Name, Rest) = Arg.split(",");
514   if (E.Name.empty())
515     goto err;
516 
517   if (E.Name.contains('=')) {
518     StringRef X, Y;
519     std::tie(X, Y) = E.Name.split("=");
520 
521     // If "<name>=<dllname>.<name>".
522     if (Y.contains(".")) {
523       E.Name = X;
524       E.ForwardTo = Y;
525       return E;
526     }
527 
528     E.ExtName = X;
529     E.Name = Y;
530     if (E.Name.empty())
531       goto err;
532   }
533 
534   // If "<name>=<internalname>[,@ordinal[,NONAME]][,DATA][,PRIVATE]"
535   while (!Rest.empty()) {
536     StringRef Tok;
537     std::tie(Tok, Rest) = Rest.split(",");
538     if (Tok.equals_lower("noname")) {
539       if (E.Ordinal == 0)
540         goto err;
541       E.Noname = true;
542       continue;
543     }
544     if (Tok.equals_lower("data")) {
545       E.Data = true;
546       continue;
547     }
548     if (Tok.equals_lower("constant")) {
549       E.Constant = true;
550       continue;
551     }
552     if (Tok.equals_lower("private")) {
553       E.Private = true;
554       continue;
555     }
556     if (Tok.startswith("@")) {
557       int32_t Ord;
558       if (Tok.substr(1).getAsInteger(0, Ord))
559         goto err;
560       if (Ord <= 0 || 65535 < Ord)
561         goto err;
562       E.Ordinal = Ord;
563       continue;
564     }
565     goto err;
566   }
567   return E;
568 
569 err:
570   fatal("invalid /export: " + Arg);
571 }
572 
573 static StringRef undecorate(StringRef Sym) {
574   if (Config->Machine != I386)
575     return Sym;
576   // In MSVC mode, a fully decorated stdcall function is exported
577   // as-is with the leading underscore (with type IMPORT_NAME).
578   // In MinGW mode, a decorated stdcall function gets the underscore
579   // removed, just like normal cdecl functions.
580   if (Sym.startswith("_") && Sym.contains('@') && !Config->MinGW)
581     return Sym;
582   return Sym.startswith("_") ? Sym.substr(1) : Sym;
583 }
584 
585 // Convert stdcall/fastcall style symbols into unsuffixed symbols,
586 // with or without a leading underscore. (MinGW specific.)
587 static StringRef killAt(StringRef Sym, bool Prefix) {
588   if (Sym.empty())
589     return Sym;
590   // Strip any trailing stdcall suffix
591   Sym = Sym.substr(0, Sym.find('@', 1));
592   if (!Sym.startswith("@")) {
593     if (Prefix && !Sym.startswith("_"))
594       return Saver.save("_" + Sym);
595     return Sym;
596   }
597   // For fastcall, remove the leading @ and replace it with an
598   // underscore, if prefixes are used.
599   Sym = Sym.substr(1);
600   if (Prefix)
601     Sym = Saver.save("_" + Sym);
602   return Sym;
603 }
604 
605 // Performs error checking on all /export arguments.
606 // It also sets ordinals.
607 void fixupExports() {
608   // Symbol ordinals must be unique.
609   std::set<uint16_t> Ords;
610   for (Export &E : Config->Exports) {
611     if (E.Ordinal == 0)
612       continue;
613     if (!Ords.insert(E.Ordinal).second)
614       fatal("duplicate export ordinal: " + E.Name);
615   }
616 
617   for (Export &E : Config->Exports) {
618     Symbol *Sym = E.Sym;
619     if (!E.ForwardTo.empty() || !Sym) {
620       E.SymbolName = E.Name;
621     } else {
622       if (auto *U = dyn_cast<Undefined>(Sym))
623         if (U->WeakAlias)
624           Sym = U->WeakAlias;
625       E.SymbolName = Sym->getName();
626     }
627   }
628 
629   for (Export &E : Config->Exports) {
630     if (!E.ForwardTo.empty()) {
631       E.ExportName = undecorate(E.Name);
632     } else {
633       E.ExportName = undecorate(E.ExtName.empty() ? E.Name : E.ExtName);
634     }
635   }
636 
637   if (Config->KillAt && Config->Machine == I386) {
638     for (Export &E : Config->Exports) {
639       E.Name = killAt(E.Name, true);
640       E.ExportName = killAt(E.ExportName, false);
641       E.ExtName = killAt(E.ExtName, true);
642       E.SymbolName = killAt(E.SymbolName, true);
643     }
644   }
645 
646   // Uniquefy by name.
647   DenseMap<StringRef, Export *> Map(Config->Exports.size());
648   std::vector<Export> V;
649   for (Export &E : Config->Exports) {
650     auto Pair = Map.insert(std::make_pair(E.ExportName, &E));
651     bool Inserted = Pair.second;
652     if (Inserted) {
653       V.push_back(E);
654       continue;
655     }
656     Export *Existing = Pair.first->second;
657     if (E == *Existing || E.Name != Existing->Name)
658       continue;
659     warn("duplicate /export option: " + E.Name);
660   }
661   Config->Exports = std::move(V);
662 
663   // Sort by name.
664   std::sort(Config->Exports.begin(), Config->Exports.end(),
665             [](const Export &A, const Export &B) {
666               return A.ExportName < B.ExportName;
667             });
668 }
669 
670 void assignExportOrdinals() {
671   // Assign unique ordinals if default (= 0).
672   uint16_t Max = 0;
673   for (Export &E : Config->Exports)
674     Max = std::max(Max, E.Ordinal);
675   for (Export &E : Config->Exports)
676     if (E.Ordinal == 0)
677       E.Ordinal = ++Max;
678 }
679 
680 // Parses a string in the form of "key=value" and check
681 // if value matches previous values for the same key.
682 void checkFailIfMismatch(StringRef Arg) {
683   StringRef K, V;
684   std::tie(K, V) = Arg.split('=');
685   if (K.empty() || V.empty())
686     fatal("/failifmismatch: invalid argument: " + Arg);
687   StringRef Existing = Config->MustMatch[K];
688   if (!Existing.empty() && V != Existing)
689     fatal("/failifmismatch: mismatch detected: " + Existing + " and " + V +
690           " for key " + K);
691   Config->MustMatch[K] = V;
692 }
693 
694 // Convert Windows resource files (.res files) to a .obj file.
695 MemoryBufferRef convertResToCOFF(ArrayRef<MemoryBufferRef> MBs) {
696   object::WindowsResourceParser Parser;
697 
698   for (MemoryBufferRef MB : MBs) {
699     std::unique_ptr<object::Binary> Bin = check(object::createBinary(MB));
700     object::WindowsResource *RF = dyn_cast<object::WindowsResource>(Bin.get());
701     if (!RF)
702       fatal("cannot compile non-resource file as resource");
703     if (auto EC = Parser.parse(RF))
704       fatal("failed to parse .res file: " + toString(std::move(EC)));
705   }
706 
707   Expected<std::unique_ptr<MemoryBuffer>> E =
708       llvm::object::writeWindowsResourceCOFF(Config->Machine, Parser);
709   if (!E)
710     fatal("failed to write .res to COFF: " + toString(E.takeError()));
711 
712   MemoryBufferRef MBRef = **E;
713   make<std::unique_ptr<MemoryBuffer>>(std::move(*E)); // take ownership
714   return MBRef;
715 }
716 
717 // Run MSVC link.exe for given in-memory object files.
718 // Command line options are copied from those given to LLD.
719 // This is for the /msvclto option.
720 void runMSVCLinker(std::string Rsp, ArrayRef<StringRef> Objects) {
721   // Write the in-memory object files to disk.
722   std::vector<TemporaryFile> Temps;
723   for (StringRef S : Objects) {
724     Temps.emplace_back("lto", "obj", S);
725     Rsp += quote(Temps.back().Path) + "\n";
726   }
727 
728   log("link.exe " + Rsp);
729 
730   // Run MSVC link.exe.
731   Temps.emplace_back("lto", "rsp", Rsp);
732   Executor E("link.exe");
733   E.add(Twine("@" + Temps.back().Path));
734   E.run();
735 }
736 
737 // Create OptTable
738 
739 // Create prefix string literals used in Options.td
740 #define PREFIX(NAME, VALUE) const char *const NAME[] = VALUE;
741 #include "Options.inc"
742 #undef PREFIX
743 
744 // Create table mapping all options defined in Options.td
745 static const llvm::opt::OptTable::Info InfoTable[] = {
746 #define OPTION(X1, X2, ID, KIND, GROUP, ALIAS, X7, X8, X9, X10, X11, X12)      \
747   {X1, X2, X10,         X11,         OPT_##ID, llvm::opt::Option::KIND##Class, \
748    X9, X8, OPT_##GROUP, OPT_##ALIAS, X7,       X12},
749 #include "Options.inc"
750 #undef OPTION
751 };
752 
753 COFFOptTable::COFFOptTable() : OptTable(InfoTable, true) {}
754 
755 static cl::TokenizerCallback getQuotingStyle(opt::InputArgList &Args) {
756   if (auto *Arg = Args.getLastArg(OPT_rsp_quoting)) {
757     StringRef S = Arg->getValue();
758     if (S != "windows" && S != "posix")
759       error("invalid response file quoting: " + S);
760     if (S == "windows")
761       return cl::TokenizeWindowsCommandLine;
762     return cl::TokenizeGNUCommandLine;
763   }
764   // The COFF linker always defaults to Windows quoting.
765   return cl::TokenizeWindowsCommandLine;
766 }
767 
768 // Parses a given list of options.
769 opt::InputArgList ArgParser::parse(ArrayRef<const char *> Argv) {
770   // Make InputArgList from string vectors.
771   unsigned MissingIndex;
772   unsigned MissingCount;
773   SmallVector<const char *, 256> Vec(Argv.data(), Argv.data() + Argv.size());
774 
775   // We need to get the quoting style for response files before parsing all
776   // options so we parse here before and ignore all the options but
777   // --rsp-quoting.
778   opt::InputArgList Args = Table.ParseArgs(Vec, MissingIndex, MissingCount);
779 
780   // Expand response files (arguments in the form of @<filename>)
781   // and then parse the argument again.
782   cl::ExpandResponseFiles(Saver, getQuotingStyle(Args), Vec);
783   Args = Table.ParseArgs(Vec, MissingIndex, MissingCount);
784 
785   // Print the real command line if response files are expanded.
786   if (Args.hasArg(OPT_verbose) && Argv.size() != Vec.size()) {
787     std::string Msg = "Command line:";
788     for (const char *S : Vec)
789       Msg += " " + std::string(S);
790     message(Msg);
791   }
792 
793   // Handle /WX early since it converts missing argument warnings to errors.
794   errorHandler().FatalWarnings = Args.hasFlag(OPT_WX, OPT_WX_no, false);
795 
796   if (MissingCount)
797     fatal(Twine(Args.getArgString(MissingIndex)) + ": missing argument");
798   for (auto *Arg : Args.filtered(OPT_UNKNOWN))
799     warn("ignoring unknown argument: " + Arg->getSpelling());
800   return Args;
801 }
802 
803 // Tokenizes and parses a given string as command line in .drective section.
804 // /EXPORT options are processed in fastpath.
805 std::pair<opt::InputArgList, std::vector<StringRef>>
806 ArgParser::parseDirectives(StringRef S) {
807   std::vector<StringRef> Exports;
808   SmallVector<const char *, 16> Rest;
809 
810   for (StringRef Tok : tokenize(S)) {
811     if (Tok.startswith_lower("/export:") || Tok.startswith_lower("-export:"))
812       Exports.push_back(Tok.substr(strlen("/export:")));
813     else
814       Rest.push_back(Tok.data());
815   }
816 
817   // Make InputArgList from unparsed string vectors.
818   unsigned MissingIndex;
819   unsigned MissingCount;
820 
821   opt::InputArgList Args = Table.ParseArgs(Rest, MissingIndex, MissingCount);
822 
823   if (MissingCount)
824     fatal(Twine(Args.getArgString(MissingIndex)) + ": missing argument");
825   for (auto *Arg : Args.filtered(OPT_UNKNOWN))
826     warn("ignoring unknown argument: " + Arg->getSpelling());
827   return {std::move(Args), std::move(Exports)};
828 }
829 
830 // link.exe has an interesting feature. If LINK or _LINK_ environment
831 // variables exist, their contents are handled as command line strings.
832 // So you can pass extra arguments using them.
833 opt::InputArgList ArgParser::parseLINK(std::vector<const char *> Argv) {
834   // Concatenate LINK env and command line arguments, and then parse them.
835   if (Optional<std::string> S = Process::GetEnv("LINK")) {
836     std::vector<const char *> V = tokenize(*S);
837     Argv.insert(Argv.begin(), V.begin(), V.end());
838   }
839   if (Optional<std::string> S = Process::GetEnv("_LINK_")) {
840     std::vector<const char *> V = tokenize(*S);
841     Argv.insert(Argv.begin(), V.begin(), V.end());
842   }
843   return parse(Argv);
844 }
845 
846 std::vector<const char *> ArgParser::tokenize(StringRef S) {
847   SmallVector<const char *, 16> Tokens;
848   cl::TokenizeWindowsCommandLine(S, Saver, Tokens);
849   return std::vector<const char *>(Tokens.begin(), Tokens.end());
850 }
851 
852 void printHelp(const char *Argv0) {
853   COFFOptTable().PrintHelp(outs(), Argv0, "LLVM Linker", false);
854 }
855 
856 } // namespace coff
857 } // namespace lld
858