1 //===--- FrontendActions.cpp ----------------------------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "clang/Frontend/FrontendActions.h"
11 #include "clang/AST/ASTConsumer.h"
12 #include "clang/Basic/FileManager.h"
13 #include "clang/Frontend/ASTConsumers.h"
14 #include "clang/Frontend/ASTUnit.h"
15 #include "clang/Frontend/CompilerInstance.h"
16 #include "clang/Frontend/FrontendDiagnostic.h"
17 #include "clang/Frontend/Utils.h"
18 #include "clang/Lex/HeaderSearch.h"
19 #include "clang/Lex/Pragma.h"
20 #include "clang/Lex/Preprocessor.h"
21 #include "clang/Parse/Parser.h"
22 #include "clang/Serialization/ASTReader.h"
23 #include "clang/Serialization/ASTWriter.h"
24 #include "llvm/Support/FileSystem.h"
25 #include "llvm/Support/MemoryBuffer.h"
26 #include "llvm/Support/raw_ostream.h"
27 #include "llvm/Support/system_error.h"
28 #include <memory>
29 
30 using namespace clang;
31 
32 //===----------------------------------------------------------------------===//
33 // Custom Actions
34 //===----------------------------------------------------------------------===//
35 
36 ASTConsumer *InitOnlyAction::CreateASTConsumer(CompilerInstance &CI,
37                                                StringRef InFile) {
38   return new ASTConsumer();
39 }
40 
41 void InitOnlyAction::ExecuteAction() {
42 }
43 
44 //===----------------------------------------------------------------------===//
45 // AST Consumer Actions
46 //===----------------------------------------------------------------------===//
47 
48 ASTConsumer *ASTPrintAction::CreateASTConsumer(CompilerInstance &CI,
49                                                StringRef InFile) {
50   if (raw_ostream *OS = CI.createDefaultOutputFile(false, InFile))
51     return CreateASTPrinter(OS, CI.getFrontendOpts().ASTDumpFilter);
52   return nullptr;
53 }
54 
55 ASTConsumer *ASTDumpAction::CreateASTConsumer(CompilerInstance &CI,
56                                               StringRef InFile) {
57   return CreateASTDumper(CI.getFrontendOpts().ASTDumpFilter,
58                          CI.getFrontendOpts().ASTDumpLookups);
59 }
60 
61 ASTConsumer *ASTDeclListAction::CreateASTConsumer(CompilerInstance &CI,
62                                                   StringRef InFile) {
63   return CreateASTDeclNodeLister();
64 }
65 
66 ASTConsumer *ASTViewAction::CreateASTConsumer(CompilerInstance &CI,
67                                               StringRef InFile) {
68   return CreateASTViewer();
69 }
70 
71 ASTConsumer *DeclContextPrintAction::CreateASTConsumer(CompilerInstance &CI,
72                                                        StringRef InFile) {
73   return CreateDeclContextPrinter();
74 }
75 
76 ASTConsumer *GeneratePCHAction::CreateASTConsumer(CompilerInstance &CI,
77                                                   StringRef InFile) {
78   std::string Sysroot;
79   std::string OutputFile;
80   raw_ostream *OS = nullptr;
81   if (ComputeASTConsumerArguments(CI, InFile, Sysroot, OutputFile, OS))
82     return nullptr;
83 
84   if (!CI.getFrontendOpts().RelocatablePCH)
85     Sysroot.clear();
86   return new PCHGenerator(CI.getPreprocessor(), OutputFile, nullptr, Sysroot,
87                           OS);
88 }
89 
90 bool GeneratePCHAction::ComputeASTConsumerArguments(CompilerInstance &CI,
91                                                     StringRef InFile,
92                                                     std::string &Sysroot,
93                                                     std::string &OutputFile,
94                                                     raw_ostream *&OS) {
95   Sysroot = CI.getHeaderSearchOpts().Sysroot;
96   if (CI.getFrontendOpts().RelocatablePCH && Sysroot.empty()) {
97     CI.getDiagnostics().Report(diag::err_relocatable_without_isysroot);
98     return true;
99   }
100 
101   // We use createOutputFile here because this is exposed via libclang, and we
102   // must disable the RemoveFileOnSignal behavior.
103   // We use a temporary to avoid race conditions.
104   OS = CI.createOutputFile(CI.getFrontendOpts().OutputFile, /*Binary=*/true,
105                            /*RemoveFileOnSignal=*/false, InFile,
106                            /*Extension=*/"", /*useTemporary=*/true);
107   if (!OS)
108     return true;
109 
110   OutputFile = CI.getFrontendOpts().OutputFile;
111   return false;
112 }
113 
114 ASTConsumer *GenerateModuleAction::CreateASTConsumer(CompilerInstance &CI,
115                                                      StringRef InFile) {
116   std::string Sysroot;
117   std::string OutputFile;
118   raw_ostream *OS = nullptr;
119   if (ComputeASTConsumerArguments(CI, InFile, Sysroot, OutputFile, OS))
120     return nullptr;
121 
122   return new PCHGenerator(CI.getPreprocessor(), OutputFile, Module,
123                           Sysroot, OS);
124 }
125 
126 static SmallVectorImpl<char> &
127 operator+=(SmallVectorImpl<char> &Includes, StringRef RHS) {
128   Includes.append(RHS.begin(), RHS.end());
129   return Includes;
130 }
131 
132 static llvm::error_code addHeaderInclude(StringRef HeaderName,
133                                          SmallVectorImpl<char> &Includes,
134                                          const LangOptions &LangOpts,
135                                          bool IsExternC) {
136   if (IsExternC && LangOpts.CPlusPlus)
137     Includes += "extern \"C\" {\n";
138   if (LangOpts.ObjC1)
139     Includes += "#import \"";
140   else
141     Includes += "#include \"";
142   // Use an absolute path for the include; there's no reason to think that
143   // a relative path will work (. might not be on our include path) or that
144   // it will find the same file.
145   if (llvm::sys::path::is_absolute(HeaderName)) {
146     Includes += HeaderName;
147   } else {
148     SmallString<256> Header = HeaderName;
149     if (llvm::error_code Err = llvm::sys::fs::make_absolute(Header))
150       return Err;
151     Includes += Header;
152   }
153   Includes += "\"\n";
154   if (IsExternC && LangOpts.CPlusPlus)
155     Includes += "}\n";
156   return llvm::error_code();
157 }
158 
159 static llvm::error_code addHeaderInclude(const FileEntry *Header,
160                                          SmallVectorImpl<char> &Includes,
161                                          const LangOptions &LangOpts,
162                                          bool IsExternC) {
163   return addHeaderInclude(Header->getName(), Includes, LangOpts, IsExternC);
164 }
165 
166 /// \brief Collect the set of header includes needed to construct the given
167 /// module and update the TopHeaders file set of the module.
168 ///
169 /// \param Module The module we're collecting includes from.
170 ///
171 /// \param Includes Will be augmented with the set of \#includes or \#imports
172 /// needed to load all of the named headers.
173 static llvm::error_code
174 collectModuleHeaderIncludes(const LangOptions &LangOpts, FileManager &FileMgr,
175                             ModuleMap &ModMap, clang::Module *Module,
176                             SmallVectorImpl<char> &Includes) {
177   // Don't collect any headers for unavailable modules.
178   if (!Module->isAvailable())
179     return llvm::error_code();
180 
181   // Add includes for each of these headers.
182   for (unsigned I = 0, N = Module->NormalHeaders.size(); I != N; ++I) {
183     const FileEntry *Header = Module->NormalHeaders[I];
184     Module->addTopHeader(Header);
185     if (llvm::error_code Err =
186             addHeaderInclude(Header, Includes, LangOpts, Module->IsExternC))
187       return Err;
188   }
189   // Note that Module->PrivateHeaders will not be a TopHeader.
190 
191   if (const FileEntry *UmbrellaHeader = Module->getUmbrellaHeader()) {
192     Module->addTopHeader(UmbrellaHeader);
193     if (Module->Parent) {
194       // Include the umbrella header for submodules.
195       if (llvm::error_code Err = addHeaderInclude(UmbrellaHeader, Includes,
196                                                   LangOpts, Module->IsExternC))
197         return Err;
198     }
199   } else if (const DirectoryEntry *UmbrellaDir = Module->getUmbrellaDir()) {
200     // Add all of the headers we find in this subdirectory.
201     llvm::error_code EC;
202     SmallString<128> DirNative;
203     llvm::sys::path::native(UmbrellaDir->getName(), DirNative);
204     for (llvm::sys::fs::recursive_directory_iterator Dir(DirNative.str(), EC),
205                                                      DirEnd;
206          Dir != DirEnd && !EC; Dir.increment(EC)) {
207       // Check whether this entry has an extension typically associated with
208       // headers.
209       if (!llvm::StringSwitch<bool>(llvm::sys::path::extension(Dir->path()))
210           .Cases(".h", ".H", ".hh", ".hpp", true)
211           .Default(false))
212         continue;
213 
214       // If this header is marked 'unavailable' in this module, don't include
215       // it.
216       if (const FileEntry *Header = FileMgr.getFile(Dir->path())) {
217         if (ModMap.isHeaderUnavailableInModule(Header, Module))
218           continue;
219         Module->addTopHeader(Header);
220       }
221 
222       // Include this header as part of the umbrella directory.
223       if (llvm::error_code Err = addHeaderInclude(Dir->path(), Includes,
224                                                   LangOpts, Module->IsExternC))
225         return Err;
226     }
227 
228     if (EC)
229       return EC;
230   }
231 
232   // Recurse into submodules.
233   for (clang::Module::submodule_iterator Sub = Module->submodule_begin(),
234                                       SubEnd = Module->submodule_end();
235        Sub != SubEnd; ++Sub)
236     if (llvm::error_code Err = collectModuleHeaderIncludes(
237             LangOpts, FileMgr, ModMap, *Sub, Includes))
238       return Err;
239 
240   return llvm::error_code();
241 }
242 
243 bool GenerateModuleAction::BeginSourceFileAction(CompilerInstance &CI,
244                                                  StringRef Filename) {
245   // Find the module map file.
246   const FileEntry *ModuleMap = CI.getFileManager().getFile(Filename);
247   if (!ModuleMap)  {
248     CI.getDiagnostics().Report(diag::err_module_map_not_found)
249       << Filename;
250     return false;
251   }
252 
253   // Parse the module map file.
254   HeaderSearch &HS = CI.getPreprocessor().getHeaderSearchInfo();
255   if (HS.loadModuleMapFile(ModuleMap, IsSystem))
256     return false;
257 
258   if (CI.getLangOpts().CurrentModule.empty()) {
259     CI.getDiagnostics().Report(diag::err_missing_module_name);
260 
261     // FIXME: Eventually, we could consider asking whether there was just
262     // a single module described in the module map, and use that as a
263     // default. Then it would be fairly trivial to just "compile" a module
264     // map with a single module (the common case).
265     return false;
266   }
267 
268   // If we're being run from the command-line, the module build stack will not
269   // have been filled in yet, so complete it now in order to allow us to detect
270   // module cycles.
271   SourceManager &SourceMgr = CI.getSourceManager();
272   if (SourceMgr.getModuleBuildStack().empty())
273     SourceMgr.pushModuleBuildStack(CI.getLangOpts().CurrentModule,
274                                    FullSourceLoc(SourceLocation(), SourceMgr));
275 
276   // Dig out the module definition.
277   Module = HS.lookupModule(CI.getLangOpts().CurrentModule,
278                            /*AllowSearch=*/false);
279   if (!Module) {
280     CI.getDiagnostics().Report(diag::err_missing_module)
281       << CI.getLangOpts().CurrentModule << Filename;
282 
283     return false;
284   }
285 
286   // Check whether we can build this module at all.
287   clang::Module::Requirement Requirement;
288   clang::Module::HeaderDirective MissingHeader;
289   if (!Module->isAvailable(CI.getLangOpts(), CI.getTarget(), Requirement,
290                            MissingHeader)) {
291     if (MissingHeader.FileNameLoc.isValid()) {
292       CI.getDiagnostics().Report(MissingHeader.FileNameLoc,
293                                  diag::err_module_header_missing)
294         << MissingHeader.IsUmbrella << MissingHeader.FileName;
295     } else {
296       CI.getDiagnostics().Report(diag::err_module_unavailable)
297         << Module->getFullModuleName()
298         << Requirement.second << Requirement.first;
299     }
300 
301     return false;
302   }
303 
304   if (!ModuleMapForUniquing)
305     ModuleMapForUniquing = ModuleMap;
306   Module->ModuleMap = ModuleMapForUniquing;
307   assert(Module->ModuleMap && "missing module map file");
308 
309   FileManager &FileMgr = CI.getFileManager();
310 
311   // Collect the set of #includes we need to build the module.
312   SmallString<256> HeaderContents;
313   llvm::error_code Err = llvm::error_code();
314   if (const FileEntry *UmbrellaHeader = Module->getUmbrellaHeader())
315     Err = addHeaderInclude(UmbrellaHeader, HeaderContents, CI.getLangOpts(),
316                            Module->IsExternC);
317   if (!Err)
318     Err = collectModuleHeaderIncludes(
319         CI.getLangOpts(), FileMgr,
320         CI.getPreprocessor().getHeaderSearchInfo().getModuleMap(), Module,
321         HeaderContents);
322 
323   if (Err) {
324     CI.getDiagnostics().Report(diag::err_module_cannot_create_includes)
325       << Module->getFullModuleName() << Err.message();
326     return false;
327   }
328 
329   llvm::MemoryBuffer *InputBuffer =
330       llvm::MemoryBuffer::getMemBufferCopy(HeaderContents,
331                                            Module::getModuleInputBufferName());
332   // Ownership of InputBuffer will be transferred to the SourceManager.
333   setCurrentInput(FrontendInputFile(InputBuffer, getCurrentFileKind(),
334                                     Module->IsSystem));
335   return true;
336 }
337 
338 bool GenerateModuleAction::ComputeASTConsumerArguments(CompilerInstance &CI,
339                                                        StringRef InFile,
340                                                        std::string &Sysroot,
341                                                        std::string &OutputFile,
342                                                        raw_ostream *&OS) {
343   // If no output file was provided, figure out where this module would go
344   // in the module cache.
345   if (CI.getFrontendOpts().OutputFile.empty()) {
346     HeaderSearch &HS = CI.getPreprocessor().getHeaderSearchInfo();
347     CI.getFrontendOpts().OutputFile =
348         HS.getModuleFileName(CI.getLangOpts().CurrentModule,
349                              ModuleMapForUniquing->getName());
350   }
351 
352   // We use createOutputFile here because this is exposed via libclang, and we
353   // must disable the RemoveFileOnSignal behavior.
354   // We use a temporary to avoid race conditions.
355   OS = CI.createOutputFile(CI.getFrontendOpts().OutputFile, /*Binary=*/true,
356                            /*RemoveFileOnSignal=*/false, InFile,
357                            /*Extension=*/"", /*useTemporary=*/true,
358                            /*CreateMissingDirectories=*/true);
359   if (!OS)
360     return true;
361 
362   OutputFile = CI.getFrontendOpts().OutputFile;
363   return false;
364 }
365 
366 ASTConsumer *SyntaxOnlyAction::CreateASTConsumer(CompilerInstance &CI,
367                                                  StringRef InFile) {
368   return new ASTConsumer();
369 }
370 
371 ASTConsumer *DumpModuleInfoAction::CreateASTConsumer(CompilerInstance &CI,
372                                                      StringRef InFile) {
373   return new ASTConsumer();
374 }
375 
376 ASTConsumer *VerifyPCHAction::CreateASTConsumer(CompilerInstance &CI,
377                                                 StringRef InFile) {
378   return new ASTConsumer();
379 }
380 
381 void VerifyPCHAction::ExecuteAction() {
382   CompilerInstance &CI = getCompilerInstance();
383   bool Preamble = CI.getPreprocessorOpts().PrecompiledPreambleBytes.first != 0;
384   const std::string &Sysroot = CI.getHeaderSearchOpts().Sysroot;
385   std::unique_ptr<ASTReader> Reader(
386       new ASTReader(CI.getPreprocessor(), CI.getASTContext(),
387                     Sysroot.empty() ? "" : Sysroot.c_str(),
388                     /*DisableValidation*/ false,
389                     /*AllowPCHWithCompilerErrors*/ false,
390                     /*AllowConfigurationMismatch*/ true,
391                     /*ValidateSystemInputs*/ true));
392 
393   Reader->ReadAST(getCurrentFile(),
394                   Preamble ? serialization::MK_Preamble
395                            : serialization::MK_PCH,
396                   SourceLocation(),
397                   ASTReader::ARR_ConfigurationMismatch);
398 }
399 
400 namespace {
401   /// \brief AST reader listener that dumps module information for a module
402   /// file.
403   class DumpModuleInfoListener : public ASTReaderListener {
404     llvm::raw_ostream &Out;
405 
406   public:
407     DumpModuleInfoListener(llvm::raw_ostream &Out) : Out(Out) { }
408 
409 #define DUMP_BOOLEAN(Value, Text)                       \
410     Out.indent(4) << Text << ": " << (Value? "Yes" : "No") << "\n"
411 
412     bool ReadFullVersionInformation(StringRef FullVersion) override {
413       Out.indent(2)
414         << "Generated by "
415         << (FullVersion == getClangFullRepositoryVersion()? "this"
416                                                           : "a different")
417         << " Clang: " << FullVersion << "\n";
418       return ASTReaderListener::ReadFullVersionInformation(FullVersion);
419     }
420 
421     void ReadModuleName(StringRef ModuleName) override {
422       Out.indent(2) << "Module name: " << ModuleName << "\n";
423     }
424     void ReadModuleMapFile(StringRef ModuleMapPath) override {
425       Out.indent(2) << "Module map file: " << ModuleMapPath << "\n";
426     }
427 
428     bool ReadLanguageOptions(const LangOptions &LangOpts,
429                              bool Complain) override {
430       Out.indent(2) << "Language options:\n";
431 #define LANGOPT(Name, Bits, Default, Description) \
432       DUMP_BOOLEAN(LangOpts.Name, Description);
433 #define ENUM_LANGOPT(Name, Type, Bits, Default, Description) \
434       Out.indent(4) << Description << ": "                   \
435                     << static_cast<unsigned>(LangOpts.get##Name()) << "\n";
436 #define VALUE_LANGOPT(Name, Bits, Default, Description) \
437       Out.indent(4) << Description << ": " << LangOpts.Name << "\n";
438 #define BENIGN_LANGOPT(Name, Bits, Default, Description)
439 #define BENIGN_ENUM_LANGOPT(Name, Type, Bits, Default, Description)
440 #include "clang/Basic/LangOptions.def"
441       return false;
442     }
443 
444     bool ReadTargetOptions(const TargetOptions &TargetOpts,
445                            bool Complain) override {
446       Out.indent(2) << "Target options:\n";
447       Out.indent(4) << "  Triple: " << TargetOpts.Triple << "\n";
448       Out.indent(4) << "  CPU: " << TargetOpts.CPU << "\n";
449       Out.indent(4) << "  ABI: " << TargetOpts.ABI << "\n";
450 
451       if (!TargetOpts.FeaturesAsWritten.empty()) {
452         Out.indent(4) << "Target features:\n";
453         for (unsigned I = 0, N = TargetOpts.FeaturesAsWritten.size();
454              I != N; ++I) {
455           Out.indent(6) << TargetOpts.FeaturesAsWritten[I] << "\n";
456         }
457       }
458 
459       return false;
460     }
461 
462     virtual bool
463     ReadDiagnosticOptions(IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts,
464                           bool Complain) override {
465       Out.indent(2) << "Diagnostic options:\n";
466 #define DIAGOPT(Name, Bits, Default) DUMP_BOOLEAN(DiagOpts->Name, #Name);
467 #define ENUM_DIAGOPT(Name, Type, Bits, Default) \
468       Out.indent(4) << #Name << ": " << DiagOpts->get##Name() << "\n";
469 #define VALUE_DIAGOPT(Name, Bits, Default) \
470       Out.indent(4) << #Name << ": " << DiagOpts->Name << "\n";
471 #include "clang/Basic/DiagnosticOptions.def"
472 
473       Out.indent(4) << "Warning options:\n";
474       for (const std::string &Warning : DiagOpts->Warnings) {
475         Out.indent(6) << "-W" << Warning << "\n";
476       }
477 
478       return false;
479     }
480 
481     bool ReadHeaderSearchOptions(const HeaderSearchOptions &HSOpts,
482                                  bool Complain) override {
483       Out.indent(2) << "Header search options:\n";
484       Out.indent(4) << "System root [-isysroot=]: '" << HSOpts.Sysroot << "'\n";
485       DUMP_BOOLEAN(HSOpts.UseBuiltinIncludes,
486                    "Use builtin include directories [-nobuiltininc]");
487       DUMP_BOOLEAN(HSOpts.UseStandardSystemIncludes,
488                    "Use standard system include directories [-nostdinc]");
489       DUMP_BOOLEAN(HSOpts.UseStandardCXXIncludes,
490                    "Use standard C++ include directories [-nostdinc++]");
491       DUMP_BOOLEAN(HSOpts.UseLibcxx,
492                    "Use libc++ (rather than libstdc++) [-stdlib=]");
493       return false;
494     }
495 
496     bool ReadPreprocessorOptions(const PreprocessorOptions &PPOpts,
497                                  bool Complain,
498                                  std::string &SuggestedPredefines) override {
499       Out.indent(2) << "Preprocessor options:\n";
500       DUMP_BOOLEAN(PPOpts.UsePredefines,
501                    "Uses compiler/target-specific predefines [-undef]");
502       DUMP_BOOLEAN(PPOpts.DetailedRecord,
503                    "Uses detailed preprocessing record (for indexing)");
504 
505       if (!PPOpts.Macros.empty()) {
506         Out.indent(4) << "Predefined macros:\n";
507       }
508 
509       for (std::vector<std::pair<std::string, bool/*isUndef*/> >::const_iterator
510              I = PPOpts.Macros.begin(), IEnd = PPOpts.Macros.end();
511            I != IEnd; ++I) {
512         Out.indent(6);
513         if (I->second)
514           Out << "-U";
515         else
516           Out << "-D";
517         Out << I->first << "\n";
518       }
519       return false;
520     }
521 #undef DUMP_BOOLEAN
522   };
523 }
524 
525 void DumpModuleInfoAction::ExecuteAction() {
526   // Set up the output file.
527   std::unique_ptr<llvm::raw_fd_ostream> OutFile;
528   StringRef OutputFileName = getCompilerInstance().getFrontendOpts().OutputFile;
529   if (!OutputFileName.empty() && OutputFileName != "-") {
530     std::string ErrorInfo;
531     OutFile.reset(new llvm::raw_fd_ostream(OutputFileName.str().c_str(),
532                                            ErrorInfo, llvm::sys::fs::F_Text));
533   }
534   llvm::raw_ostream &Out = OutFile.get()? *OutFile.get() : llvm::outs();
535 
536   Out << "Information for module file '" << getCurrentFile() << "':\n";
537   DumpModuleInfoListener Listener(Out);
538   ASTReader::readASTFileControlBlock(getCurrentFile(),
539                                      getCompilerInstance().getFileManager(),
540                                      Listener);
541 }
542 
543 //===----------------------------------------------------------------------===//
544 // Preprocessor Actions
545 //===----------------------------------------------------------------------===//
546 
547 void DumpRawTokensAction::ExecuteAction() {
548   Preprocessor &PP = getCompilerInstance().getPreprocessor();
549   SourceManager &SM = PP.getSourceManager();
550 
551   // Start lexing the specified input file.
552   const llvm::MemoryBuffer *FromFile = SM.getBuffer(SM.getMainFileID());
553   Lexer RawLex(SM.getMainFileID(), FromFile, SM, PP.getLangOpts());
554   RawLex.SetKeepWhitespaceMode(true);
555 
556   Token RawTok;
557   RawLex.LexFromRawLexer(RawTok);
558   while (RawTok.isNot(tok::eof)) {
559     PP.DumpToken(RawTok, true);
560     llvm::errs() << "\n";
561     RawLex.LexFromRawLexer(RawTok);
562   }
563 }
564 
565 void DumpTokensAction::ExecuteAction() {
566   Preprocessor &PP = getCompilerInstance().getPreprocessor();
567   // Start preprocessing the specified input file.
568   Token Tok;
569   PP.EnterMainSourceFile();
570   do {
571     PP.Lex(Tok);
572     PP.DumpToken(Tok, true);
573     llvm::errs() << "\n";
574   } while (Tok.isNot(tok::eof));
575 }
576 
577 void GeneratePTHAction::ExecuteAction() {
578   CompilerInstance &CI = getCompilerInstance();
579   if (CI.getFrontendOpts().OutputFile.empty() ||
580       CI.getFrontendOpts().OutputFile == "-") {
581     // FIXME: Don't fail this way.
582     // FIXME: Verify that we can actually seek in the given file.
583     llvm::report_fatal_error("PTH requires a seekable file for output!");
584   }
585   llvm::raw_fd_ostream *OS =
586     CI.createDefaultOutputFile(true, getCurrentFile());
587   if (!OS) return;
588 
589   CacheTokens(CI.getPreprocessor(), OS);
590 }
591 
592 void PreprocessOnlyAction::ExecuteAction() {
593   Preprocessor &PP = getCompilerInstance().getPreprocessor();
594 
595   // Ignore unknown pragmas.
596   PP.IgnorePragmas();
597 
598   Token Tok;
599   // Start parsing the specified input file.
600   PP.EnterMainSourceFile();
601   do {
602     PP.Lex(Tok);
603   } while (Tok.isNot(tok::eof));
604 }
605 
606 void PrintPreprocessedAction::ExecuteAction() {
607   CompilerInstance &CI = getCompilerInstance();
608   // Output file may need to be set to 'Binary', to avoid converting Unix style
609   // line feeds (<LF>) to Microsoft style line feeds (<CR><LF>).
610   //
611   // Look to see what type of line endings the file uses. If there's a
612   // CRLF, then we won't open the file up in binary mode. If there is
613   // just an LF or CR, then we will open the file up in binary mode.
614   // In this fashion, the output format should match the input format, unless
615   // the input format has inconsistent line endings.
616   //
617   // This should be a relatively fast operation since most files won't have
618   // all of their source code on a single line. However, that is still a
619   // concern, so if we scan for too long, we'll just assume the file should
620   // be opened in binary mode.
621   bool BinaryMode = true;
622   bool InvalidFile = false;
623   const SourceManager& SM = CI.getSourceManager();
624   const llvm::MemoryBuffer *Buffer = SM.getBuffer(SM.getMainFileID(),
625                                                      &InvalidFile);
626   if (!InvalidFile) {
627     const char *cur = Buffer->getBufferStart();
628     const char *end = Buffer->getBufferEnd();
629     const char *next = (cur != end) ? cur + 1 : end;
630 
631     // Limit ourselves to only scanning 256 characters into the source
632     // file.  This is mostly a sanity check in case the file has no
633     // newlines whatsoever.
634     if (end - cur > 256) end = cur + 256;
635 
636     while (next < end) {
637       if (*cur == 0x0D) {  // CR
638         if (*next == 0x0A)  // CRLF
639           BinaryMode = false;
640 
641         break;
642       } else if (*cur == 0x0A)  // LF
643         break;
644 
645       ++cur, ++next;
646     }
647   }
648 
649   raw_ostream *OS = CI.createDefaultOutputFile(BinaryMode, getCurrentFile());
650   if (!OS) return;
651 
652   DoPrintPreprocessedInput(CI.getPreprocessor(), OS,
653                            CI.getPreprocessorOutputOpts());
654 }
655 
656 void PrintPreambleAction::ExecuteAction() {
657   switch (getCurrentFileKind()) {
658   case IK_C:
659   case IK_CXX:
660   case IK_ObjC:
661   case IK_ObjCXX:
662   case IK_OpenCL:
663   case IK_CUDA:
664     break;
665 
666   case IK_None:
667   case IK_Asm:
668   case IK_PreprocessedC:
669   case IK_PreprocessedCXX:
670   case IK_PreprocessedObjC:
671   case IK_PreprocessedObjCXX:
672   case IK_AST:
673   case IK_LLVM_IR:
674     // We can't do anything with these.
675     return;
676   }
677 
678   CompilerInstance &CI = getCompilerInstance();
679   llvm::MemoryBuffer *Buffer
680       = CI.getFileManager().getBufferForFile(getCurrentFile());
681   if (Buffer) {
682     unsigned Preamble = Lexer::ComputePreamble(Buffer, CI.getLangOpts()).first;
683     llvm::outs().write(Buffer->getBufferStart(), Preamble);
684     delete Buffer;
685   }
686 }
687