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/CompilerInstance.h"
15 #include "clang/Frontend/FrontendDiagnostic.h"
16 #include "clang/Frontend/MultiplexConsumer.h"
17 #include "clang/Frontend/Utils.h"
18 #include "clang/Lex/HeaderSearch.h"
19 #include "clang/Lex/Preprocessor.h"
20 #include "clang/Lex/PreprocessorOptions.h"
21 #include "clang/Serialization/ASTReader.h"
22 #include "clang/Serialization/ASTWriter.h"
23 #include "llvm/Support/FileSystem.h"
24 #include "llvm/Support/MemoryBuffer.h"
25 #include "llvm/Support/Path.h"
26 #include "llvm/Support/raw_ostream.h"
27 #include <memory>
28 #include <system_error>
29 
30 using namespace clang;
31 
32 //===----------------------------------------------------------------------===//
33 // Custom Actions
34 //===----------------------------------------------------------------------===//
35 
36 std::unique_ptr<ASTConsumer>
37 InitOnlyAction::CreateASTConsumer(CompilerInstance &CI, StringRef InFile) {
38   return llvm::make_unique<ASTConsumer>();
39 }
40 
41 void InitOnlyAction::ExecuteAction() {
42 }
43 
44 //===----------------------------------------------------------------------===//
45 // AST Consumer Actions
46 //===----------------------------------------------------------------------===//
47 
48 std::unique_ptr<ASTConsumer>
49 ASTPrintAction::CreateASTConsumer(CompilerInstance &CI, StringRef InFile) {
50   if (std::unique_ptr<raw_ostream> OS =
51           CI.createDefaultOutputFile(false, InFile))
52     return CreateASTPrinter(std::move(OS), CI.getFrontendOpts().ASTDumpFilter);
53   return nullptr;
54 }
55 
56 std::unique_ptr<ASTConsumer>
57 ASTDumpAction::CreateASTConsumer(CompilerInstance &CI, StringRef InFile) {
58   return CreateASTDumper(CI.getFrontendOpts().ASTDumpFilter,
59                          CI.getFrontendOpts().ASTDumpDecls,
60                          CI.getFrontendOpts().ASTDumpAll,
61                          CI.getFrontendOpts().ASTDumpLookups);
62 }
63 
64 std::unique_ptr<ASTConsumer>
65 ASTDeclListAction::CreateASTConsumer(CompilerInstance &CI, StringRef InFile) {
66   return CreateASTDeclNodeLister();
67 }
68 
69 std::unique_ptr<ASTConsumer>
70 ASTViewAction::CreateASTConsumer(CompilerInstance &CI, StringRef InFile) {
71   return CreateASTViewer();
72 }
73 
74 std::unique_ptr<ASTConsumer>
75 DeclContextPrintAction::CreateASTConsumer(CompilerInstance &CI,
76                                           StringRef InFile) {
77   return CreateDeclContextPrinter();
78 }
79 
80 std::unique_ptr<ASTConsumer>
81 GeneratePCHAction::CreateASTConsumer(CompilerInstance &CI, StringRef InFile) {
82   std::string Sysroot;
83   std::string OutputFile;
84   std::unique_ptr<raw_pwrite_stream> OS =
85       ComputeASTConsumerArguments(CI, InFile, Sysroot, OutputFile);
86   if (!OS)
87     return nullptr;
88 
89   if (!CI.getFrontendOpts().RelocatablePCH)
90     Sysroot.clear();
91 
92   auto Buffer = std::make_shared<PCHBuffer>();
93   std::vector<std::unique_ptr<ASTConsumer>> Consumers;
94   Consumers.push_back(llvm::make_unique<PCHGenerator>(
95                         CI.getPreprocessor(), OutputFile, Sysroot,
96                         Buffer, CI.getFrontendOpts().ModuleFileExtensions,
97       /*AllowASTWithErrors*/CI.getPreprocessorOpts().AllowPCHWithCompilerErrors,
98                         /*IncludeTimestamps*/
99                           +CI.getFrontendOpts().IncludeTimestamps));
100   Consumers.push_back(CI.getPCHContainerWriter().CreatePCHContainerGenerator(
101       CI, InFile, OutputFile, std::move(OS), Buffer));
102 
103   return llvm::make_unique<MultiplexConsumer>(std::move(Consumers));
104 }
105 
106 std::unique_ptr<raw_pwrite_stream>
107 GeneratePCHAction::ComputeASTConsumerArguments(CompilerInstance &CI,
108                                                StringRef InFile,
109                                                std::string &Sysroot,
110                                                std::string &OutputFile) {
111   Sysroot = CI.getHeaderSearchOpts().Sysroot;
112   if (CI.getFrontendOpts().RelocatablePCH && Sysroot.empty()) {
113     CI.getDiagnostics().Report(diag::err_relocatable_without_isysroot);
114     return nullptr;
115   }
116 
117   // We use createOutputFile here because this is exposed via libclang, and we
118   // must disable the RemoveFileOnSignal behavior.
119   // We use a temporary to avoid race conditions.
120   std::unique_ptr<raw_pwrite_stream> OS =
121       CI.createOutputFile(CI.getFrontendOpts().OutputFile, /*Binary=*/true,
122                           /*RemoveFileOnSignal=*/false, InFile,
123                           /*Extension=*/"", /*useTemporary=*/true);
124   if (!OS)
125     return nullptr;
126 
127   OutputFile = CI.getFrontendOpts().OutputFile;
128   return OS;
129 }
130 
131 bool GeneratePCHAction::shouldEraseOutputFiles() {
132   if (getCompilerInstance().getPreprocessorOpts().AllowPCHWithCompilerErrors)
133     return false;
134   return ASTFrontendAction::shouldEraseOutputFiles();
135 }
136 
137 bool GeneratePCHAction::BeginSourceFileAction(CompilerInstance &CI) {
138   CI.getLangOpts().CompilingPCH = true;
139   return true;
140 }
141 
142 std::unique_ptr<ASTConsumer>
143 GenerateModuleAction::CreateASTConsumer(CompilerInstance &CI,
144                                         StringRef InFile) {
145   std::unique_ptr<raw_pwrite_stream> OS = CreateOutputFile(CI, InFile);
146   if (!OS)
147     return nullptr;
148 
149   std::string OutputFile = CI.getFrontendOpts().OutputFile;
150   std::string Sysroot;
151 
152   auto Buffer = std::make_shared<PCHBuffer>();
153   std::vector<std::unique_ptr<ASTConsumer>> Consumers;
154 
155   Consumers.push_back(llvm::make_unique<PCHGenerator>(
156                         CI.getPreprocessor(), OutputFile, Sysroot,
157                         Buffer, CI.getFrontendOpts().ModuleFileExtensions,
158                         /*AllowASTWithErrors=*/false,
159                         /*IncludeTimestamps=*/
160                           +CI.getFrontendOpts().BuildingImplicitModule));
161   Consumers.push_back(CI.getPCHContainerWriter().CreatePCHContainerGenerator(
162       CI, InFile, OutputFile, std::move(OS), Buffer));
163   return llvm::make_unique<MultiplexConsumer>(std::move(Consumers));
164 }
165 
166 bool GenerateModuleFromModuleMapAction::BeginSourceFileAction(
167     CompilerInstance &CI) {
168   if (!CI.getLangOpts().Modules) {
169     CI.getDiagnostics().Report(diag::err_module_build_requires_fmodules);
170     return false;
171   }
172 
173   return GenerateModuleAction::BeginSourceFileAction(CI);
174 }
175 
176 std::unique_ptr<raw_pwrite_stream>
177 GenerateModuleFromModuleMapAction::CreateOutputFile(CompilerInstance &CI,
178                                                     StringRef InFile) {
179   // If no output file was provided, figure out where this module would go
180   // in the module cache.
181   if (CI.getFrontendOpts().OutputFile.empty()) {
182     StringRef ModuleMapFile = CI.getFrontendOpts().OriginalModuleMap;
183     if (ModuleMapFile.empty())
184       ModuleMapFile = InFile;
185 
186     HeaderSearch &HS = CI.getPreprocessor().getHeaderSearchInfo();
187     CI.getFrontendOpts().OutputFile =
188         HS.getCachedModuleFileName(CI.getLangOpts().CurrentModule,
189                                    ModuleMapFile);
190   }
191 
192   // We use createOutputFile here because this is exposed via libclang, and we
193   // must disable the RemoveFileOnSignal behavior.
194   // We use a temporary to avoid race conditions.
195   return CI.createOutputFile(CI.getFrontendOpts().OutputFile, /*Binary=*/true,
196                              /*RemoveFileOnSignal=*/false, InFile,
197                              /*Extension=*/"", /*useTemporary=*/true,
198                              /*CreateMissingDirectories=*/true);
199 }
200 
201 bool GenerateModuleInterfaceAction::BeginSourceFileAction(
202     CompilerInstance &CI) {
203   if (!CI.getLangOpts().ModulesTS) {
204     CI.getDiagnostics().Report(diag::err_module_interface_requires_modules_ts);
205     return false;
206   }
207 
208   CI.getLangOpts().setCompilingModule(LangOptions::CMK_ModuleInterface);
209 
210   return GenerateModuleAction::BeginSourceFileAction(CI);
211 }
212 
213 std::unique_ptr<raw_pwrite_stream>
214 GenerateModuleInterfaceAction::CreateOutputFile(CompilerInstance &CI,
215                                                 StringRef InFile) {
216   return CI.createDefaultOutputFile(/*Binary=*/true, InFile, "pcm");
217 }
218 
219 SyntaxOnlyAction::~SyntaxOnlyAction() {
220 }
221 
222 std::unique_ptr<ASTConsumer>
223 SyntaxOnlyAction::CreateASTConsumer(CompilerInstance &CI, StringRef InFile) {
224   return llvm::make_unique<ASTConsumer>();
225 }
226 
227 std::unique_ptr<ASTConsumer>
228 DumpModuleInfoAction::CreateASTConsumer(CompilerInstance &CI,
229                                         StringRef InFile) {
230   return llvm::make_unique<ASTConsumer>();
231 }
232 
233 std::unique_ptr<ASTConsumer>
234 VerifyPCHAction::CreateASTConsumer(CompilerInstance &CI, StringRef InFile) {
235   return llvm::make_unique<ASTConsumer>();
236 }
237 
238 void VerifyPCHAction::ExecuteAction() {
239   CompilerInstance &CI = getCompilerInstance();
240   bool Preamble = CI.getPreprocessorOpts().PrecompiledPreambleBytes.first != 0;
241   const std::string &Sysroot = CI.getHeaderSearchOpts().Sysroot;
242   std::unique_ptr<ASTReader> Reader(new ASTReader(
243       CI.getPreprocessor(), &CI.getASTContext(), CI.getPCHContainerReader(),
244       CI.getFrontendOpts().ModuleFileExtensions,
245       Sysroot.empty() ? "" : Sysroot.c_str(),
246       /*DisableValidation*/ false,
247       /*AllowPCHWithCompilerErrors*/ false,
248       /*AllowConfigurationMismatch*/ true,
249       /*ValidateSystemInputs*/ true));
250 
251   Reader->ReadAST(getCurrentFile(),
252                   Preamble ? serialization::MK_Preamble
253                            : serialization::MK_PCH,
254                   SourceLocation(),
255                   ASTReader::ARR_ConfigurationMismatch);
256 }
257 
258 namespace {
259   /// \brief AST reader listener that dumps module information for a module
260   /// file.
261   class DumpModuleInfoListener : public ASTReaderListener {
262     llvm::raw_ostream &Out;
263 
264   public:
265     DumpModuleInfoListener(llvm::raw_ostream &Out) : Out(Out) { }
266 
267 #define DUMP_BOOLEAN(Value, Text)                       \
268     Out.indent(4) << Text << ": " << (Value? "Yes" : "No") << "\n"
269 
270     bool ReadFullVersionInformation(StringRef FullVersion) override {
271       Out.indent(2)
272         << "Generated by "
273         << (FullVersion == getClangFullRepositoryVersion()? "this"
274                                                           : "a different")
275         << " Clang: " << FullVersion << "\n";
276       return ASTReaderListener::ReadFullVersionInformation(FullVersion);
277     }
278 
279     void ReadModuleName(StringRef ModuleName) override {
280       Out.indent(2) << "Module name: " << ModuleName << "\n";
281     }
282     void ReadModuleMapFile(StringRef ModuleMapPath) override {
283       Out.indent(2) << "Module map file: " << ModuleMapPath << "\n";
284     }
285 
286     bool ReadLanguageOptions(const LangOptions &LangOpts, bool Complain,
287                              bool AllowCompatibleDifferences) override {
288       Out.indent(2) << "Language options:\n";
289 #define LANGOPT(Name, Bits, Default, Description) \
290       DUMP_BOOLEAN(LangOpts.Name, Description);
291 #define ENUM_LANGOPT(Name, Type, Bits, Default, Description) \
292       Out.indent(4) << Description << ": "                   \
293                     << static_cast<unsigned>(LangOpts.get##Name()) << "\n";
294 #define VALUE_LANGOPT(Name, Bits, Default, Description) \
295       Out.indent(4) << Description << ": " << LangOpts.Name << "\n";
296 #define BENIGN_LANGOPT(Name, Bits, Default, Description)
297 #define BENIGN_ENUM_LANGOPT(Name, Type, Bits, Default, Description)
298 #include "clang/Basic/LangOptions.def"
299 
300       if (!LangOpts.ModuleFeatures.empty()) {
301         Out.indent(4) << "Module features:\n";
302         for (StringRef Feature : LangOpts.ModuleFeatures)
303           Out.indent(6) << Feature << "\n";
304       }
305 
306       return false;
307     }
308 
309     bool ReadTargetOptions(const TargetOptions &TargetOpts, bool Complain,
310                            bool AllowCompatibleDifferences) override {
311       Out.indent(2) << "Target options:\n";
312       Out.indent(4) << "  Triple: " << TargetOpts.Triple << "\n";
313       Out.indent(4) << "  CPU: " << TargetOpts.CPU << "\n";
314       Out.indent(4) << "  ABI: " << TargetOpts.ABI << "\n";
315 
316       if (!TargetOpts.FeaturesAsWritten.empty()) {
317         Out.indent(4) << "Target features:\n";
318         for (unsigned I = 0, N = TargetOpts.FeaturesAsWritten.size();
319              I != N; ++I) {
320           Out.indent(6) << TargetOpts.FeaturesAsWritten[I] << "\n";
321         }
322       }
323 
324       return false;
325     }
326 
327     bool ReadDiagnosticOptions(IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts,
328                                bool Complain) override {
329       Out.indent(2) << "Diagnostic options:\n";
330 #define DIAGOPT(Name, Bits, Default) DUMP_BOOLEAN(DiagOpts->Name, #Name);
331 #define ENUM_DIAGOPT(Name, Type, Bits, Default) \
332       Out.indent(4) << #Name << ": " << DiagOpts->get##Name() << "\n";
333 #define VALUE_DIAGOPT(Name, Bits, Default) \
334       Out.indent(4) << #Name << ": " << DiagOpts->Name << "\n";
335 #include "clang/Basic/DiagnosticOptions.def"
336 
337       Out.indent(4) << "Diagnostic flags:\n";
338       for (const std::string &Warning : DiagOpts->Warnings)
339         Out.indent(6) << "-W" << Warning << "\n";
340       for (const std::string &Remark : DiagOpts->Remarks)
341         Out.indent(6) << "-R" << Remark << "\n";
342 
343       return false;
344     }
345 
346     bool ReadHeaderSearchOptions(const HeaderSearchOptions &HSOpts,
347                                  StringRef SpecificModuleCachePath,
348                                  bool Complain) override {
349       Out.indent(2) << "Header search options:\n";
350       Out.indent(4) << "System root [-isysroot=]: '" << HSOpts.Sysroot << "'\n";
351       Out.indent(4) << "Resource dir [ -resource-dir=]: '" << HSOpts.ResourceDir << "'\n";
352       Out.indent(4) << "Module Cache: '" << SpecificModuleCachePath << "'\n";
353       DUMP_BOOLEAN(HSOpts.UseBuiltinIncludes,
354                    "Use builtin include directories [-nobuiltininc]");
355       DUMP_BOOLEAN(HSOpts.UseStandardSystemIncludes,
356                    "Use standard system include directories [-nostdinc]");
357       DUMP_BOOLEAN(HSOpts.UseStandardCXXIncludes,
358                    "Use standard C++ include directories [-nostdinc++]");
359       DUMP_BOOLEAN(HSOpts.UseLibcxx,
360                    "Use libc++ (rather than libstdc++) [-stdlib=]");
361       return false;
362     }
363 
364     bool ReadPreprocessorOptions(const PreprocessorOptions &PPOpts,
365                                  bool Complain,
366                                  std::string &SuggestedPredefines) override {
367       Out.indent(2) << "Preprocessor options:\n";
368       DUMP_BOOLEAN(PPOpts.UsePredefines,
369                    "Uses compiler/target-specific predefines [-undef]");
370       DUMP_BOOLEAN(PPOpts.DetailedRecord,
371                    "Uses detailed preprocessing record (for indexing)");
372 
373       if (!PPOpts.Macros.empty()) {
374         Out.indent(4) << "Predefined macros:\n";
375       }
376 
377       for (std::vector<std::pair<std::string, bool/*isUndef*/> >::const_iterator
378              I = PPOpts.Macros.begin(), IEnd = PPOpts.Macros.end();
379            I != IEnd; ++I) {
380         Out.indent(6);
381         if (I->second)
382           Out << "-U";
383         else
384           Out << "-D";
385         Out << I->first << "\n";
386       }
387       return false;
388     }
389 
390     /// Indicates that a particular module file extension has been read.
391     void readModuleFileExtension(
392            const ModuleFileExtensionMetadata &Metadata) override {
393       Out.indent(2) << "Module file extension '"
394                     << Metadata.BlockName << "' " << Metadata.MajorVersion
395                     << "." << Metadata.MinorVersion;
396       if (!Metadata.UserInfo.empty()) {
397         Out << ": ";
398         Out.write_escaped(Metadata.UserInfo);
399       }
400 
401       Out << "\n";
402     }
403 #undef DUMP_BOOLEAN
404   };
405 }
406 
407 bool DumpModuleInfoAction::BeginInvocation(CompilerInstance &CI) {
408   // The Object file reader also supports raw ast files and there is no point in
409   // being strict about the module file format in -module-file-info mode.
410   CI.getHeaderSearchOpts().ModuleFormat = "obj";
411   return true;
412 }
413 
414 void DumpModuleInfoAction::ExecuteAction() {
415   // Set up the output file.
416   std::unique_ptr<llvm::raw_fd_ostream> OutFile;
417   StringRef OutputFileName = getCompilerInstance().getFrontendOpts().OutputFile;
418   if (!OutputFileName.empty() && OutputFileName != "-") {
419     std::error_code EC;
420     OutFile.reset(new llvm::raw_fd_ostream(OutputFileName.str(), EC,
421                                            llvm::sys::fs::F_Text));
422   }
423   llvm::raw_ostream &Out = OutFile.get()? *OutFile.get() : llvm::outs();
424 
425   Out << "Information for module file '" << getCurrentFile() << "':\n";
426   auto &FileMgr = getCompilerInstance().getFileManager();
427   auto Buffer = FileMgr.getBufferForFile(getCurrentFile());
428   StringRef Magic = (*Buffer)->getMemBufferRef().getBuffer();
429   bool IsRaw = (Magic.size() >= 4 && Magic[0] == 'C' && Magic[1] == 'P' &&
430                 Magic[2] == 'C' && Magic[3] == 'H');
431   Out << "  Module format: " << (IsRaw ? "raw" : "obj") << "\n";
432 
433   Preprocessor &PP = getCompilerInstance().getPreprocessor();
434   DumpModuleInfoListener Listener(Out);
435   HeaderSearchOptions &HSOpts =
436       PP.getHeaderSearchInfo().getHeaderSearchOpts();
437   ASTReader::readASTFileControlBlock(
438       getCurrentFile(), FileMgr, getCompilerInstance().getPCHContainerReader(),
439       /*FindModuleFileExtensions=*/true, Listener,
440       HSOpts.ModulesValidateDiagnosticOptions);
441 }
442 
443 //===----------------------------------------------------------------------===//
444 // Preprocessor Actions
445 //===----------------------------------------------------------------------===//
446 
447 void DumpRawTokensAction::ExecuteAction() {
448   Preprocessor &PP = getCompilerInstance().getPreprocessor();
449   SourceManager &SM = PP.getSourceManager();
450 
451   // Start lexing the specified input file.
452   const llvm::MemoryBuffer *FromFile = SM.getBuffer(SM.getMainFileID());
453   Lexer RawLex(SM.getMainFileID(), FromFile, SM, PP.getLangOpts());
454   RawLex.SetKeepWhitespaceMode(true);
455 
456   Token RawTok;
457   RawLex.LexFromRawLexer(RawTok);
458   while (RawTok.isNot(tok::eof)) {
459     PP.DumpToken(RawTok, true);
460     llvm::errs() << "\n";
461     RawLex.LexFromRawLexer(RawTok);
462   }
463 }
464 
465 void DumpTokensAction::ExecuteAction() {
466   Preprocessor &PP = getCompilerInstance().getPreprocessor();
467   // Start preprocessing the specified input file.
468   Token Tok;
469   PP.EnterMainSourceFile();
470   do {
471     PP.Lex(Tok);
472     PP.DumpToken(Tok, true);
473     llvm::errs() << "\n";
474   } while (Tok.isNot(tok::eof));
475 }
476 
477 void GeneratePTHAction::ExecuteAction() {
478   CompilerInstance &CI = getCompilerInstance();
479   std::unique_ptr<raw_pwrite_stream> OS =
480       CI.createDefaultOutputFile(true, getCurrentFile());
481   if (!OS)
482     return;
483 
484   CacheTokens(CI.getPreprocessor(), OS.get());
485 }
486 
487 void PreprocessOnlyAction::ExecuteAction() {
488   Preprocessor &PP = getCompilerInstance().getPreprocessor();
489 
490   // Ignore unknown pragmas.
491   PP.IgnorePragmas();
492 
493   Token Tok;
494   // Start parsing the specified input file.
495   PP.EnterMainSourceFile();
496   do {
497     PP.Lex(Tok);
498   } while (Tok.isNot(tok::eof));
499 }
500 
501 void PrintPreprocessedAction::ExecuteAction() {
502   CompilerInstance &CI = getCompilerInstance();
503   // Output file may need to be set to 'Binary', to avoid converting Unix style
504   // line feeds (<LF>) to Microsoft style line feeds (<CR><LF>).
505   //
506   // Look to see what type of line endings the file uses. If there's a
507   // CRLF, then we won't open the file up in binary mode. If there is
508   // just an LF or CR, then we will open the file up in binary mode.
509   // In this fashion, the output format should match the input format, unless
510   // the input format has inconsistent line endings.
511   //
512   // This should be a relatively fast operation since most files won't have
513   // all of their source code on a single line. However, that is still a
514   // concern, so if we scan for too long, we'll just assume the file should
515   // be opened in binary mode.
516   bool BinaryMode = true;
517   bool InvalidFile = false;
518   const SourceManager& SM = CI.getSourceManager();
519   const llvm::MemoryBuffer *Buffer = SM.getBuffer(SM.getMainFileID(),
520                                                      &InvalidFile);
521   if (!InvalidFile) {
522     const char *cur = Buffer->getBufferStart();
523     const char *end = Buffer->getBufferEnd();
524     const char *next = (cur != end) ? cur + 1 : end;
525 
526     // Limit ourselves to only scanning 256 characters into the source
527     // file.  This is mostly a sanity check in case the file has no
528     // newlines whatsoever.
529     if (end - cur > 256) end = cur + 256;
530 
531     while (next < end) {
532       if (*cur == 0x0D) {  // CR
533         if (*next == 0x0A)  // CRLF
534           BinaryMode = false;
535 
536         break;
537       } else if (*cur == 0x0A)  // LF
538         break;
539 
540       ++cur;
541       ++next;
542     }
543   }
544 
545   std::unique_ptr<raw_ostream> OS =
546       CI.createDefaultOutputFile(BinaryMode, getCurrentFile());
547   if (!OS) return;
548 
549   // If we're preprocessing a module map, start by dumping the contents of the
550   // module itself before switching to the input buffer.
551   auto &Input = getCurrentInput();
552   if (Input.getKind().getFormat() == InputKind::ModuleMap) {
553     if (Input.isFile()) {
554       (*OS) << "# 1 \"";
555       OS->write_escaped(Input.getFile());
556       (*OS) << "\"\n";
557     }
558     // FIXME: Include additional information here so that we don't need the
559     // original source files to exist on disk.
560     getCurrentModule()->print(*OS);
561     (*OS) << "#pragma clang module contents\n";
562   }
563 
564   DoPrintPreprocessedInput(CI.getPreprocessor(), OS.get(),
565                            CI.getPreprocessorOutputOpts());
566 }
567 
568 void PrintPreambleAction::ExecuteAction() {
569   switch (getCurrentFileKind().getLanguage()) {
570   case InputKind::C:
571   case InputKind::CXX:
572   case InputKind::ObjC:
573   case InputKind::ObjCXX:
574   case InputKind::OpenCL:
575   case InputKind::CUDA:
576     break;
577 
578   case InputKind::Unknown:
579   case InputKind::Asm:
580   case InputKind::LLVM_IR:
581   case InputKind::RenderScript:
582     // We can't do anything with these.
583     return;
584   }
585 
586   // We don't expect to find any #include directives in a preprocessed input.
587   if (getCurrentFileKind().isPreprocessed())
588     return;
589 
590   CompilerInstance &CI = getCompilerInstance();
591   auto Buffer = CI.getFileManager().getBufferForFile(getCurrentFile());
592   if (Buffer) {
593     unsigned Preamble =
594         Lexer::ComputePreamble((*Buffer)->getBuffer(), CI.getLangOpts()).Size;
595     llvm::outs().write((*Buffer)->getBufferStart(), Preamble);
596   }
597 }
598