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