xref: /llvm-project/clang/lib/Frontend/CompilerInstance.cpp (revision a97eaa1bc04636ad0d9e9b6b98f6c5cf6418dc7b)
1 //===--- CompilerInstance.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/CompilerInstance.h"
11 #include "clang/AST/ASTConsumer.h"
12 #include "clang/AST/ASTContext.h"
13 #include "clang/AST/Decl.h"
14 #include "clang/Basic/Diagnostic.h"
15 #include "clang/Basic/FileManager.h"
16 #include "clang/Basic/SourceManager.h"
17 #include "clang/Basic/TargetInfo.h"
18 #include "clang/Basic/Version.h"
19 #include "clang/Config/config.h"
20 #include "clang/Frontend/ChainedDiagnosticConsumer.h"
21 #include "clang/Frontend/FrontendAction.h"
22 #include "clang/Frontend/FrontendActions.h"
23 #include "clang/Frontend/FrontendDiagnostic.h"
24 #include "clang/Frontend/LogDiagnosticPrinter.h"
25 #include "clang/Frontend/SerializedDiagnosticPrinter.h"
26 #include "clang/Frontend/TextDiagnosticPrinter.h"
27 #include "clang/Frontend/Utils.h"
28 #include "clang/Frontend/VerifyDiagnosticConsumer.h"
29 #include "clang/Lex/HeaderSearch.h"
30 #include "clang/Lex/PTHManager.h"
31 #include "clang/Lex/Preprocessor.h"
32 #include "clang/Sema/CodeCompleteConsumer.h"
33 #include "clang/Sema/Sema.h"
34 #include "clang/Serialization/ASTReader.h"
35 #include "clang/Serialization/GlobalModuleIndex.h"
36 #include "llvm/ADT/Statistic.h"
37 #include "llvm/Support/CrashRecoveryContext.h"
38 #include "llvm/Support/Errc.h"
39 #include "llvm/Support/FileSystem.h"
40 #include "llvm/Support/Host.h"
41 #include "llvm/Support/LockFileManager.h"
42 #include "llvm/Support/MemoryBuffer.h"
43 #include "llvm/Support/Path.h"
44 #include "llvm/Support/Program.h"
45 #include "llvm/Support/Signals.h"
46 #include "llvm/Support/Timer.h"
47 #include "llvm/Support/raw_ostream.h"
48 #include <sys/stat.h>
49 #include <system_error>
50 #include <time.h>
51 
52 using namespace clang;
53 
54 CompilerInstance::CompilerInstance(bool BuildingModule)
55   : ModuleLoader(BuildingModule),
56     Invocation(new CompilerInvocation()), ModuleManager(nullptr),
57     BuildGlobalModuleIndex(false), HaveFullGlobalModuleIndex(false),
58     ModuleBuildFailed(false) {
59 }
60 
61 CompilerInstance::~CompilerInstance() {
62   assert(OutputFiles.empty() && "Still output files in flight?");
63 }
64 
65 void CompilerInstance::setInvocation(CompilerInvocation *Value) {
66   Invocation = Value;
67 }
68 
69 bool CompilerInstance::shouldBuildGlobalModuleIndex() const {
70   return (BuildGlobalModuleIndex ||
71           (ModuleManager && ModuleManager->isGlobalIndexUnavailable() &&
72            getFrontendOpts().GenerateGlobalModuleIndex)) &&
73          !ModuleBuildFailed;
74 }
75 
76 void CompilerInstance::setDiagnostics(DiagnosticsEngine *Value) {
77   Diagnostics = Value;
78 }
79 
80 void CompilerInstance::setTarget(TargetInfo *Value) {
81   Target = Value;
82 }
83 
84 void CompilerInstance::setFileManager(FileManager *Value) {
85   FileMgr = Value;
86   if (Value)
87     VirtualFileSystem = Value->getVirtualFileSystem();
88   else
89     VirtualFileSystem.reset();
90 }
91 
92 void CompilerInstance::setSourceManager(SourceManager *Value) {
93   SourceMgr = Value;
94 }
95 
96 void CompilerInstance::setPreprocessor(Preprocessor *Value) { PP = Value; }
97 
98 void CompilerInstance::setASTContext(ASTContext *Value) { Context = Value; }
99 
100 void CompilerInstance::setSema(Sema *S) {
101   TheSema.reset(S);
102 }
103 
104 void CompilerInstance::setASTConsumer(std::unique_ptr<ASTConsumer> Value) {
105   Consumer = std::move(Value);
106 }
107 
108 void CompilerInstance::setCodeCompletionConsumer(CodeCompleteConsumer *Value) {
109   CompletionConsumer.reset(Value);
110 }
111 
112 std::unique_ptr<Sema> CompilerInstance::takeSema() {
113   return std::move(TheSema);
114 }
115 
116 IntrusiveRefCntPtr<ASTReader> CompilerInstance::getModuleManager() const {
117   return ModuleManager;
118 }
119 void CompilerInstance::setModuleManager(IntrusiveRefCntPtr<ASTReader> Reader) {
120   ModuleManager = Reader;
121 }
122 
123 std::shared_ptr<ModuleDependencyCollector>
124 CompilerInstance::getModuleDepCollector() const {
125   return ModuleDepCollector;
126 }
127 
128 void CompilerInstance::setModuleDepCollector(
129     std::shared_ptr<ModuleDependencyCollector> Collector) {
130   ModuleDepCollector = Collector;
131 }
132 
133 // Diagnostics
134 static void SetUpDiagnosticLog(DiagnosticOptions *DiagOpts,
135                                const CodeGenOptions *CodeGenOpts,
136                                DiagnosticsEngine &Diags) {
137   std::error_code EC;
138   bool OwnsStream = false;
139   raw_ostream *OS = &llvm::errs();
140   if (DiagOpts->DiagnosticLogFile != "-") {
141     // Create the output stream.
142     llvm::raw_fd_ostream *FileOS(new llvm::raw_fd_ostream(
143         DiagOpts->DiagnosticLogFile, EC,
144         llvm::sys::fs::F_Append | llvm::sys::fs::F_Text));
145     if (EC) {
146       Diags.Report(diag::warn_fe_cc_log_diagnostics_failure)
147           << DiagOpts->DiagnosticLogFile << EC.message();
148     } else {
149       FileOS->SetUnbuffered();
150       FileOS->SetUseAtomicWrites(true);
151       OS = FileOS;
152       OwnsStream = true;
153     }
154   }
155 
156   // Chain in the diagnostic client which will log the diagnostics.
157   LogDiagnosticPrinter *Logger = new LogDiagnosticPrinter(*OS, DiagOpts,
158                                                           OwnsStream);
159   if (CodeGenOpts)
160     Logger->setDwarfDebugFlags(CodeGenOpts->DwarfDebugFlags);
161   Diags.setClient(new ChainedDiagnosticConsumer(Diags.takeClient(), Logger));
162 }
163 
164 static void SetupSerializedDiagnostics(DiagnosticOptions *DiagOpts,
165                                        DiagnosticsEngine &Diags,
166                                        StringRef OutputFile) {
167   std::error_code EC;
168   std::unique_ptr<llvm::raw_fd_ostream> OS;
169   OS.reset(
170       new llvm::raw_fd_ostream(OutputFile.str(), EC, llvm::sys::fs::F_None));
171 
172   if (EC) {
173     Diags.Report(diag::warn_fe_serialized_diag_failure) << OutputFile
174                                                         << EC.message();
175     return;
176   }
177 
178   DiagnosticConsumer *SerializedConsumer =
179       clang::serialized_diags::create(OS.release(), DiagOpts);
180 
181   Diags.setClient(new ChainedDiagnosticConsumer(Diags.takeClient(),
182                                                 SerializedConsumer));
183 }
184 
185 void CompilerInstance::createDiagnostics(DiagnosticConsumer *Client,
186                                          bool ShouldOwnClient) {
187   Diagnostics = createDiagnostics(&getDiagnosticOpts(), Client,
188                                   ShouldOwnClient, &getCodeGenOpts());
189 }
190 
191 IntrusiveRefCntPtr<DiagnosticsEngine>
192 CompilerInstance::createDiagnostics(DiagnosticOptions *Opts,
193                                     DiagnosticConsumer *Client,
194                                     bool ShouldOwnClient,
195                                     const CodeGenOptions *CodeGenOpts) {
196   IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
197   IntrusiveRefCntPtr<DiagnosticsEngine>
198       Diags(new DiagnosticsEngine(DiagID, Opts));
199 
200   // Create the diagnostic client for reporting errors or for
201   // implementing -verify.
202   if (Client) {
203     Diags->setClient(Client, ShouldOwnClient);
204   } else
205     Diags->setClient(new TextDiagnosticPrinter(llvm::errs(), Opts));
206 
207   // Chain in -verify checker, if requested.
208   if (Opts->VerifyDiagnostics)
209     Diags->setClient(new VerifyDiagnosticConsumer(*Diags));
210 
211   // Chain in -diagnostic-log-file dumper, if requested.
212   if (!Opts->DiagnosticLogFile.empty())
213     SetUpDiagnosticLog(Opts, CodeGenOpts, *Diags);
214 
215   if (!Opts->DiagnosticSerializationFile.empty())
216     SetupSerializedDiagnostics(Opts, *Diags,
217                                Opts->DiagnosticSerializationFile);
218 
219   // Configure our handling of diagnostics.
220   ProcessWarningOptions(*Diags, *Opts);
221 
222   return Diags;
223 }
224 
225 // File Manager
226 
227 void CompilerInstance::createFileManager() {
228   if (!hasVirtualFileSystem()) {
229     // TODO: choose the virtual file system based on the CompilerInvocation.
230     setVirtualFileSystem(vfs::getRealFileSystem());
231   }
232   FileMgr = new FileManager(getFileSystemOpts(), VirtualFileSystem);
233 }
234 
235 // Source Manager
236 
237 void CompilerInstance::createSourceManager(FileManager &FileMgr) {
238   SourceMgr = new SourceManager(getDiagnostics(), FileMgr);
239 }
240 
241 // Initialize the remapping of files to alternative contents, e.g.,
242 // those specified through other files.
243 static void InitializeFileRemapping(DiagnosticsEngine &Diags,
244                                     SourceManager &SourceMgr,
245                                     FileManager &FileMgr,
246                                     const PreprocessorOptions &InitOpts) {
247   // Remap files in the source manager (with buffers).
248   for (const auto &RB : InitOpts.RemappedFileBuffers) {
249     // Create the file entry for the file that we're mapping from.
250     const FileEntry *FromFile =
251         FileMgr.getVirtualFile(RB.first, RB.second->getBufferSize(), 0);
252     if (!FromFile) {
253       Diags.Report(diag::err_fe_remap_missing_from_file) << RB.first;
254       if (!InitOpts.RetainRemappedFileBuffers)
255         delete RB.second;
256       continue;
257     }
258 
259     // Override the contents of the "from" file with the contents of
260     // the "to" file.
261     SourceMgr.overrideFileContents(FromFile, RB.second,
262                                    InitOpts.RetainRemappedFileBuffers);
263   }
264 
265   // Remap files in the source manager (with other files).
266   for (const auto &RF : InitOpts.RemappedFiles) {
267     // Find the file that we're mapping to.
268     const FileEntry *ToFile = FileMgr.getFile(RF.second);
269     if (!ToFile) {
270       Diags.Report(diag::err_fe_remap_missing_to_file) << RF.first << RF.second;
271       continue;
272     }
273 
274     // Create the file entry for the file that we're mapping from.
275     const FileEntry *FromFile =
276         FileMgr.getVirtualFile(RF.first, ToFile->getSize(), 0);
277     if (!FromFile) {
278       Diags.Report(diag::err_fe_remap_missing_from_file) << RF.first;
279       continue;
280     }
281 
282     // Override the contents of the "from" file with the contents of
283     // the "to" file.
284     SourceMgr.overrideFileContents(FromFile, ToFile);
285   }
286 
287   SourceMgr.setOverridenFilesKeepOriginalName(
288       InitOpts.RemappedFilesKeepOriginalName);
289 }
290 
291 // Preprocessor
292 
293 void CompilerInstance::createPreprocessor(TranslationUnitKind TUKind) {
294   const PreprocessorOptions &PPOpts = getPreprocessorOpts();
295 
296   // Create a PTH manager if we are using some form of a token cache.
297   PTHManager *PTHMgr = nullptr;
298   if (!PPOpts.TokenCache.empty())
299     PTHMgr = PTHManager::Create(PPOpts.TokenCache, getDiagnostics());
300 
301   // Create the Preprocessor.
302   HeaderSearch *HeaderInfo = new HeaderSearch(&getHeaderSearchOpts(),
303                                               getSourceManager(),
304                                               getDiagnostics(),
305                                               getLangOpts(),
306                                               &getTarget());
307   PP = new Preprocessor(&getPreprocessorOpts(), getDiagnostics(), getLangOpts(),
308                         getSourceManager(), *HeaderInfo, *this, PTHMgr,
309                         /*OwnsHeaderSearch=*/true, TUKind);
310   PP->Initialize(getTarget());
311 
312   // Note that this is different then passing PTHMgr to Preprocessor's ctor.
313   // That argument is used as the IdentifierInfoLookup argument to
314   // IdentifierTable's ctor.
315   if (PTHMgr) {
316     PTHMgr->setPreprocessor(&*PP);
317     PP->setPTHManager(PTHMgr);
318   }
319 
320   if (PPOpts.DetailedRecord)
321     PP->createPreprocessingRecord();
322 
323   // Apply remappings to the source manager.
324   InitializeFileRemapping(PP->getDiagnostics(), PP->getSourceManager(),
325                           PP->getFileManager(), PPOpts);
326 
327   // Predefine macros and configure the preprocessor.
328   InitializePreprocessor(*PP, PPOpts, getFrontendOpts());
329 
330   // Initialize the header search object.
331   ApplyHeaderSearchOptions(PP->getHeaderSearchInfo(), getHeaderSearchOpts(),
332                            PP->getLangOpts(), PP->getTargetInfo().getTriple());
333 
334   PP->setPreprocessedOutput(getPreprocessorOutputOpts().ShowCPP);
335 
336   // Set up the module path, including the hash for the
337   // module-creation options.
338   SmallString<256> SpecificModuleCache(
339                            getHeaderSearchOpts().ModuleCachePath);
340   if (!getHeaderSearchOpts().DisableModuleHash)
341     llvm::sys::path::append(SpecificModuleCache,
342                             getInvocation().getModuleHash());
343   PP->getHeaderSearchInfo().setModuleCachePath(SpecificModuleCache);
344 
345   // Handle generating dependencies, if requested.
346   const DependencyOutputOptions &DepOpts = getDependencyOutputOpts();
347   if (!DepOpts.OutputFile.empty())
348     TheDependencyFileGenerator.reset(
349         DependencyFileGenerator::CreateAndAttachToPreprocessor(*PP, DepOpts));
350   if (!DepOpts.DOTOutputFile.empty())
351     AttachDependencyGraphGen(*PP, DepOpts.DOTOutputFile,
352                              getHeaderSearchOpts().Sysroot);
353 
354   for (auto &Listener : DependencyCollectors)
355     Listener->attachToPreprocessor(*PP);
356 
357   // If we don't have a collector, but we are collecting module dependencies,
358   // then we're the top level compiler instance and need to create one.
359   if (!ModuleDepCollector && !DepOpts.ModuleDependencyOutputDir.empty())
360     ModuleDepCollector = std::make_shared<ModuleDependencyCollector>(
361         DepOpts.ModuleDependencyOutputDir);
362 
363   // Handle generating header include information, if requested.
364   if (DepOpts.ShowHeaderIncludes)
365     AttachHeaderIncludeGen(*PP);
366   if (!DepOpts.HeaderIncludeOutputFile.empty()) {
367     StringRef OutputPath = DepOpts.HeaderIncludeOutputFile;
368     if (OutputPath == "-")
369       OutputPath = "";
370     AttachHeaderIncludeGen(*PP, /*ShowAllHeaders=*/true, OutputPath,
371                            /*ShowDepth=*/false);
372   }
373 
374   if (DepOpts.PrintShowIncludes) {
375     AttachHeaderIncludeGen(*PP, /*ShowAllHeaders=*/false, /*OutputPath=*/"",
376                            /*ShowDepth=*/true, /*MSStyle=*/true);
377   }
378 }
379 
380 // ASTContext
381 
382 void CompilerInstance::createASTContext() {
383   Preprocessor &PP = getPreprocessor();
384   Context = new ASTContext(getLangOpts(), PP.getSourceManager(),
385                            PP.getIdentifierTable(), PP.getSelectorTable(),
386                            PP.getBuiltinInfo());
387   Context->InitBuiltinTypes(getTarget());
388 }
389 
390 // ExternalASTSource
391 
392 void CompilerInstance::createPCHExternalASTSource(
393     StringRef Path, bool DisablePCHValidation, bool AllowPCHWithCompilerErrors,
394     void *DeserializationListener, bool OwnDeserializationListener) {
395   IntrusiveRefCntPtr<ExternalASTSource> Source;
396   bool Preamble = getPreprocessorOpts().PrecompiledPreambleBytes.first != 0;
397   Source = createPCHExternalASTSource(
398       Path, getHeaderSearchOpts().Sysroot, DisablePCHValidation,
399       AllowPCHWithCompilerErrors, getPreprocessor(), getASTContext(),
400       DeserializationListener, OwnDeserializationListener, Preamble,
401       getFrontendOpts().UseGlobalModuleIndex);
402   ModuleManager = static_cast<ASTReader*>(Source.get());
403   getASTContext().setExternalSource(Source);
404 }
405 
406 ExternalASTSource *CompilerInstance::createPCHExternalASTSource(
407     StringRef Path, const std::string &Sysroot, bool DisablePCHValidation,
408     bool AllowPCHWithCompilerErrors, Preprocessor &PP, ASTContext &Context,
409     void *DeserializationListener, bool OwnDeserializationListener,
410     bool Preamble, bool UseGlobalModuleIndex) {
411   HeaderSearchOptions &HSOpts = PP.getHeaderSearchInfo().getHeaderSearchOpts();
412 
413   std::unique_ptr<ASTReader> Reader;
414   Reader.reset(new ASTReader(PP, Context,
415                              Sysroot.empty() ? "" : Sysroot.c_str(),
416                              DisablePCHValidation,
417                              AllowPCHWithCompilerErrors,
418                              /*AllowConfigurationMismatch*/false,
419                              HSOpts.ModulesValidateSystemHeaders,
420                              UseGlobalModuleIndex));
421 
422   Reader->setDeserializationListener(
423       static_cast<ASTDeserializationListener *>(DeserializationListener),
424       /*TakeOwnership=*/OwnDeserializationListener);
425   switch (Reader->ReadAST(Path,
426                           Preamble ? serialization::MK_Preamble
427                                    : serialization::MK_PCH,
428                           SourceLocation(),
429                           ASTReader::ARR_None)) {
430   case ASTReader::Success:
431     // Set the predefines buffer as suggested by the PCH reader. Typically, the
432     // predefines buffer will be empty.
433     PP.setPredefines(Reader->getSuggestedPredefines());
434     return Reader.release();
435 
436   case ASTReader::Failure:
437     // Unrecoverable failure: don't even try to process the input file.
438     break;
439 
440   case ASTReader::Missing:
441   case ASTReader::OutOfDate:
442   case ASTReader::VersionMismatch:
443   case ASTReader::ConfigurationMismatch:
444   case ASTReader::HadErrors:
445     // No suitable PCH file could be found. Return an error.
446     break;
447   }
448 
449   return nullptr;
450 }
451 
452 // Code Completion
453 
454 static bool EnableCodeCompletion(Preprocessor &PP,
455                                  const std::string &Filename,
456                                  unsigned Line,
457                                  unsigned Column) {
458   // Tell the source manager to chop off the given file at a specific
459   // line and column.
460   const FileEntry *Entry = PP.getFileManager().getFile(Filename);
461   if (!Entry) {
462     PP.getDiagnostics().Report(diag::err_fe_invalid_code_complete_file)
463       << Filename;
464     return true;
465   }
466 
467   // Truncate the named file at the given line/column.
468   PP.SetCodeCompletionPoint(Entry, Line, Column);
469   return false;
470 }
471 
472 void CompilerInstance::createCodeCompletionConsumer() {
473   const ParsedSourceLocation &Loc = getFrontendOpts().CodeCompletionAt;
474   if (!CompletionConsumer) {
475     setCodeCompletionConsumer(
476       createCodeCompletionConsumer(getPreprocessor(),
477                                    Loc.FileName, Loc.Line, Loc.Column,
478                                    getFrontendOpts().CodeCompleteOpts,
479                                    llvm::outs()));
480     if (!CompletionConsumer)
481       return;
482   } else if (EnableCodeCompletion(getPreprocessor(), Loc.FileName,
483                                   Loc.Line, Loc.Column)) {
484     setCodeCompletionConsumer(nullptr);
485     return;
486   }
487 
488   if (CompletionConsumer->isOutputBinary() &&
489       llvm::sys::ChangeStdoutToBinary()) {
490     getPreprocessor().getDiagnostics().Report(diag::err_fe_stdout_binary);
491     setCodeCompletionConsumer(nullptr);
492   }
493 }
494 
495 void CompilerInstance::createFrontendTimer() {
496   FrontendTimer.reset(new llvm::Timer("Clang front-end timer"));
497 }
498 
499 CodeCompleteConsumer *
500 CompilerInstance::createCodeCompletionConsumer(Preprocessor &PP,
501                                                const std::string &Filename,
502                                                unsigned Line,
503                                                unsigned Column,
504                                                const CodeCompleteOptions &Opts,
505                                                raw_ostream &OS) {
506   if (EnableCodeCompletion(PP, Filename, Line, Column))
507     return nullptr;
508 
509   // Set up the creation routine for code-completion.
510   return new PrintingCodeCompleteConsumer(Opts, OS);
511 }
512 
513 void CompilerInstance::createSema(TranslationUnitKind TUKind,
514                                   CodeCompleteConsumer *CompletionConsumer) {
515   TheSema.reset(new Sema(getPreprocessor(), getASTContext(), getASTConsumer(),
516                          TUKind, CompletionConsumer));
517 }
518 
519 // Output Files
520 
521 void CompilerInstance::addOutputFile(const OutputFile &OutFile) {
522   assert(OutFile.OS && "Attempt to add empty stream to output list!");
523   OutputFiles.push_back(OutFile);
524 }
525 
526 void CompilerInstance::clearOutputFiles(bool EraseFiles) {
527   for (std::list<OutputFile>::iterator
528          it = OutputFiles.begin(), ie = OutputFiles.end(); it != ie; ++it) {
529     delete it->OS;
530     if (!it->TempFilename.empty()) {
531       if (EraseFiles) {
532         llvm::sys::fs::remove(it->TempFilename);
533       } else {
534         SmallString<128> NewOutFile(it->Filename);
535 
536         // If '-working-directory' was passed, the output filename should be
537         // relative to that.
538         FileMgr->FixupRelativePath(NewOutFile);
539         if (std::error_code ec =
540                 llvm::sys::fs::rename(it->TempFilename, NewOutFile.str())) {
541           getDiagnostics().Report(diag::err_unable_to_rename_temp)
542             << it->TempFilename << it->Filename << ec.message();
543 
544           llvm::sys::fs::remove(it->TempFilename);
545         }
546       }
547     } else if (!it->Filename.empty() && EraseFiles)
548       llvm::sys::fs::remove(it->Filename);
549 
550   }
551   OutputFiles.clear();
552 }
553 
554 llvm::raw_fd_ostream *
555 CompilerInstance::createDefaultOutputFile(bool Binary,
556                                           StringRef InFile,
557                                           StringRef Extension) {
558   return createOutputFile(getFrontendOpts().OutputFile, Binary,
559                           /*RemoveFileOnSignal=*/true, InFile, Extension,
560                           /*UseTemporary=*/true);
561 }
562 
563 llvm::raw_null_ostream *CompilerInstance::createNullOutputFile() {
564   llvm::raw_null_ostream *OS = new llvm::raw_null_ostream();
565   addOutputFile(OutputFile("", "", OS));
566   return OS;
567 }
568 
569 llvm::raw_fd_ostream *
570 CompilerInstance::createOutputFile(StringRef OutputPath,
571                                    bool Binary, bool RemoveFileOnSignal,
572                                    StringRef InFile,
573                                    StringRef Extension,
574                                    bool UseTemporary,
575                                    bool CreateMissingDirectories) {
576   std::string OutputPathName, TempPathName;
577   std::error_code EC;
578   llvm::raw_fd_ostream *OS = createOutputFile(
579       OutputPath, EC, Binary, RemoveFileOnSignal, InFile, Extension,
580       UseTemporary, CreateMissingDirectories, &OutputPathName, &TempPathName);
581   if (!OS) {
582     getDiagnostics().Report(diag::err_fe_unable_to_open_output) << OutputPath
583                                                                 << EC.message();
584     return nullptr;
585   }
586 
587   // Add the output file -- but don't try to remove "-", since this means we are
588   // using stdin.
589   addOutputFile(OutputFile((OutputPathName != "-") ? OutputPathName : "",
590                 TempPathName, OS));
591 
592   return OS;
593 }
594 
595 llvm::raw_fd_ostream *CompilerInstance::createOutputFile(
596     StringRef OutputPath, std::error_code &Error, bool Binary,
597     bool RemoveFileOnSignal, StringRef InFile, StringRef Extension,
598     bool UseTemporary, bool CreateMissingDirectories,
599     std::string *ResultPathName, std::string *TempPathName) {
600   assert((!CreateMissingDirectories || UseTemporary) &&
601          "CreateMissingDirectories is only allowed when using temporary files");
602 
603   std::string OutFile, TempFile;
604   if (!OutputPath.empty()) {
605     OutFile = OutputPath;
606   } else if (InFile == "-") {
607     OutFile = "-";
608   } else if (!Extension.empty()) {
609     SmallString<128> Path(InFile);
610     llvm::sys::path::replace_extension(Path, Extension);
611     OutFile = Path.str();
612   } else {
613     OutFile = "-";
614   }
615 
616   std::unique_ptr<llvm::raw_fd_ostream> OS;
617   std::string OSFile;
618 
619   if (UseTemporary) {
620     if (OutFile == "-")
621       UseTemporary = false;
622     else {
623       llvm::sys::fs::file_status Status;
624       llvm::sys::fs::status(OutputPath, Status);
625       if (llvm::sys::fs::exists(Status)) {
626         // Fail early if we can't write to the final destination.
627         if (!llvm::sys::fs::can_write(OutputPath))
628           return nullptr;
629 
630         // Don't use a temporary if the output is a special file. This handles
631         // things like '-o /dev/null'
632         if (!llvm::sys::fs::is_regular_file(Status))
633           UseTemporary = false;
634       }
635     }
636   }
637 
638   if (UseTemporary) {
639     // Create a temporary file.
640     SmallString<128> TempPath;
641     TempPath = OutFile;
642     TempPath += "-%%%%%%%%";
643     int fd;
644     std::error_code EC =
645         llvm::sys::fs::createUniqueFile(TempPath.str(), fd, TempPath);
646 
647     if (CreateMissingDirectories &&
648         EC == llvm::errc::no_such_file_or_directory) {
649       StringRef Parent = llvm::sys::path::parent_path(OutputPath);
650       EC = llvm::sys::fs::create_directories(Parent);
651       if (!EC) {
652         EC = llvm::sys::fs::createUniqueFile(TempPath.str(), fd, TempPath);
653       }
654     }
655 
656     if (!EC) {
657       OS.reset(new llvm::raw_fd_ostream(fd, /*shouldClose=*/true));
658       OSFile = TempFile = TempPath.str();
659     }
660     // If we failed to create the temporary, fallback to writing to the file
661     // directly. This handles the corner case where we cannot write to the
662     // directory, but can write to the file.
663   }
664 
665   if (!OS) {
666     OSFile = OutFile;
667     OS.reset(new llvm::raw_fd_ostream(
668         OSFile, Error,
669         (Binary ? llvm::sys::fs::F_None : llvm::sys::fs::F_Text)));
670     if (Error)
671       return nullptr;
672   }
673 
674   // Make sure the out stream file gets removed if we crash.
675   if (RemoveFileOnSignal)
676     llvm::sys::RemoveFileOnSignal(OSFile);
677 
678   if (ResultPathName)
679     *ResultPathName = OutFile;
680   if (TempPathName)
681     *TempPathName = TempFile;
682 
683   return OS.release();
684 }
685 
686 // Initialization Utilities
687 
688 bool CompilerInstance::InitializeSourceManager(const FrontendInputFile &Input){
689   return InitializeSourceManager(Input, getDiagnostics(),
690                                  getFileManager(), getSourceManager(),
691                                  getFrontendOpts());
692 }
693 
694 bool CompilerInstance::InitializeSourceManager(const FrontendInputFile &Input,
695                                                DiagnosticsEngine &Diags,
696                                                FileManager &FileMgr,
697                                                SourceManager &SourceMgr,
698                                                const FrontendOptions &Opts) {
699   SrcMgr::CharacteristicKind
700     Kind = Input.isSystem() ? SrcMgr::C_System : SrcMgr::C_User;
701 
702   if (Input.isBuffer()) {
703     SourceMgr.setMainFileID(SourceMgr.createFileID(
704         std::unique_ptr<llvm::MemoryBuffer>(Input.getBuffer()), Kind));
705     assert(!SourceMgr.getMainFileID().isInvalid() &&
706            "Couldn't establish MainFileID!");
707     return true;
708   }
709 
710   StringRef InputFile = Input.getFile();
711 
712   // Figure out where to get and map in the main file.
713   if (InputFile != "-") {
714     const FileEntry *File = FileMgr.getFile(InputFile, /*OpenFile=*/true);
715     if (!File) {
716       Diags.Report(diag::err_fe_error_reading) << InputFile;
717       return false;
718     }
719 
720     // The natural SourceManager infrastructure can't currently handle named
721     // pipes, but we would at least like to accept them for the main
722     // file. Detect them here, read them with the volatile flag so FileMgr will
723     // pick up the correct size, and simply override their contents as we do for
724     // STDIN.
725     if (File->isNamedPipe()) {
726       std::string ErrorStr;
727       if (std::unique_ptr<llvm::MemoryBuffer> MB =
728               FileMgr.getBufferForFile(File, &ErrorStr, /*isVolatile=*/true)) {
729         // Create a new virtual file that will have the correct size.
730         File = FileMgr.getVirtualFile(InputFile, MB->getBufferSize(), 0);
731         SourceMgr.overrideFileContents(File, std::move(MB));
732       } else {
733         Diags.Report(diag::err_cannot_open_file) << InputFile << ErrorStr;
734         return false;
735       }
736     }
737 
738     SourceMgr.setMainFileID(
739         SourceMgr.createFileID(File, SourceLocation(), Kind));
740   } else {
741     llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> SBOrErr =
742         llvm::MemoryBuffer::getSTDIN();
743     if (std::error_code EC = SBOrErr.getError()) {
744       Diags.Report(diag::err_fe_error_reading_stdin) << EC.message();
745       return false;
746     }
747     std::unique_ptr<llvm::MemoryBuffer> SB = std::move(SBOrErr.get());
748 
749     const FileEntry *File = FileMgr.getVirtualFile(SB->getBufferIdentifier(),
750                                                    SB->getBufferSize(), 0);
751     SourceMgr.setMainFileID(
752         SourceMgr.createFileID(File, SourceLocation(), Kind));
753     SourceMgr.overrideFileContents(File, std::move(SB));
754   }
755 
756   assert(!SourceMgr.getMainFileID().isInvalid() &&
757          "Couldn't establish MainFileID!");
758   return true;
759 }
760 
761 // High-Level Operations
762 
763 bool CompilerInstance::ExecuteAction(FrontendAction &Act) {
764   assert(hasDiagnostics() && "Diagnostics engine is not initialized!");
765   assert(!getFrontendOpts().ShowHelp && "Client must handle '-help'!");
766   assert(!getFrontendOpts().ShowVersion && "Client must handle '-version'!");
767 
768   // FIXME: Take this as an argument, once all the APIs we used have moved to
769   // taking it as an input instead of hard-coding llvm::errs.
770   raw_ostream &OS = llvm::errs();
771 
772   // Create the target instance.
773   setTarget(TargetInfo::CreateTargetInfo(getDiagnostics(),
774                                          getInvocation().TargetOpts));
775   if (!hasTarget())
776     return false;
777 
778   // Inform the target of the language options.
779   //
780   // FIXME: We shouldn't need to do this, the target should be immutable once
781   // created. This complexity should be lifted elsewhere.
782   getTarget().adjust(getLangOpts());
783 
784   // rewriter project will change target built-in bool type from its default.
785   if (getFrontendOpts().ProgramAction == frontend::RewriteObjC)
786     getTarget().noSignedCharForObjCBool();
787 
788   // Validate/process some options.
789   if (getHeaderSearchOpts().Verbose)
790     OS << "clang -cc1 version " CLANG_VERSION_STRING
791        << " based upon " << BACKEND_PACKAGE_STRING
792        << " default target " << llvm::sys::getDefaultTargetTriple() << "\n";
793 
794   if (getFrontendOpts().ShowTimers)
795     createFrontendTimer();
796 
797   if (getFrontendOpts().ShowStats)
798     llvm::EnableStatistics();
799 
800   for (unsigned i = 0, e = getFrontendOpts().Inputs.size(); i != e; ++i) {
801     // Reset the ID tables if we are reusing the SourceManager and parsing
802     // regular files.
803     if (hasSourceManager() && !Act.isModelParsingAction())
804       getSourceManager().clearIDTables();
805 
806     if (Act.BeginSourceFile(*this, getFrontendOpts().Inputs[i])) {
807       Act.Execute();
808       Act.EndSourceFile();
809     }
810   }
811 
812   // Notify the diagnostic client that all files were processed.
813   getDiagnostics().getClient()->finish();
814 
815   if (getDiagnosticOpts().ShowCarets) {
816     // We can have multiple diagnostics sharing one diagnostic client.
817     // Get the total number of warnings/errors from the client.
818     unsigned NumWarnings = getDiagnostics().getClient()->getNumWarnings();
819     unsigned NumErrors = getDiagnostics().getClient()->getNumErrors();
820 
821     if (NumWarnings)
822       OS << NumWarnings << " warning" << (NumWarnings == 1 ? "" : "s");
823     if (NumWarnings && NumErrors)
824       OS << " and ";
825     if (NumErrors)
826       OS << NumErrors << " error" << (NumErrors == 1 ? "" : "s");
827     if (NumWarnings || NumErrors)
828       OS << " generated.\n";
829   }
830 
831   if (getFrontendOpts().ShowStats && hasFileManager()) {
832     getFileManager().PrintStats();
833     OS << "\n";
834   }
835 
836   return !getDiagnostics().getClient()->getNumErrors();
837 }
838 
839 /// \brief Determine the appropriate source input kind based on language
840 /// options.
841 static InputKind getSourceInputKindFromOptions(const LangOptions &LangOpts) {
842   if (LangOpts.OpenCL)
843     return IK_OpenCL;
844   if (LangOpts.CUDA)
845     return IK_CUDA;
846   if (LangOpts.ObjC1)
847     return LangOpts.CPlusPlus? IK_ObjCXX : IK_ObjC;
848   return LangOpts.CPlusPlus? IK_CXX : IK_C;
849 }
850 
851 /// \brief Compile a module file for the given module, using the options
852 /// provided by the importing compiler instance. Returns true if the module
853 /// was built without errors.
854 static bool compileModuleImpl(CompilerInstance &ImportingInstance,
855                               SourceLocation ImportLoc,
856                               Module *Module,
857                               StringRef ModuleFileName) {
858   ModuleMap &ModMap
859     = ImportingInstance.getPreprocessor().getHeaderSearchInfo().getModuleMap();
860 
861   // Construct a compiler invocation for creating this module.
862   IntrusiveRefCntPtr<CompilerInvocation> Invocation
863     (new CompilerInvocation(ImportingInstance.getInvocation()));
864 
865   PreprocessorOptions &PPOpts = Invocation->getPreprocessorOpts();
866 
867   // For any options that aren't intended to affect how a module is built,
868   // reset them to their default values.
869   Invocation->getLangOpts()->resetNonModularOptions();
870   PPOpts.resetNonModularOptions();
871 
872   // Remove any macro definitions that are explicitly ignored by the module.
873   // They aren't supposed to affect how the module is built anyway.
874   const HeaderSearchOptions &HSOpts = Invocation->getHeaderSearchOpts();
875   PPOpts.Macros.erase(
876       std::remove_if(PPOpts.Macros.begin(), PPOpts.Macros.end(),
877                      [&HSOpts](const std::pair<std::string, bool> &def) {
878         StringRef MacroDef = def.first;
879         return HSOpts.ModulesIgnoreMacros.count(MacroDef.split('=').first) > 0;
880       }),
881       PPOpts.Macros.end());
882 
883   // Note the name of the module we're building.
884   Invocation->getLangOpts()->CurrentModule = Module->getTopLevelModuleName();
885 
886   // Make sure that the failed-module structure has been allocated in
887   // the importing instance, and propagate the pointer to the newly-created
888   // instance.
889   PreprocessorOptions &ImportingPPOpts
890     = ImportingInstance.getInvocation().getPreprocessorOpts();
891   if (!ImportingPPOpts.FailedModules)
892     ImportingPPOpts.FailedModules = new PreprocessorOptions::FailedModulesSet;
893   PPOpts.FailedModules = ImportingPPOpts.FailedModules;
894 
895   // If there is a module map file, build the module using the module map.
896   // Set up the inputs/outputs so that we build the module from its umbrella
897   // header.
898   FrontendOptions &FrontendOpts = Invocation->getFrontendOpts();
899   FrontendOpts.OutputFile = ModuleFileName.str();
900   FrontendOpts.DisableFree = false;
901   FrontendOpts.GenerateGlobalModuleIndex = false;
902   FrontendOpts.Inputs.clear();
903   InputKind IK = getSourceInputKindFromOptions(*Invocation->getLangOpts());
904 
905   // Don't free the remapped file buffers; they are owned by our caller.
906   PPOpts.RetainRemappedFileBuffers = true;
907 
908   Invocation->getDiagnosticOpts().VerifyDiagnostics = 0;
909   assert(ImportingInstance.getInvocation().getModuleHash() ==
910          Invocation->getModuleHash() && "Module hash mismatch!");
911 
912   // Construct a compiler instance that will be used to actually create the
913   // module.
914   CompilerInstance Instance(/*BuildingModule=*/true);
915   Instance.setInvocation(&*Invocation);
916 
917   Instance.createDiagnostics(new ForwardingDiagnosticConsumer(
918                                    ImportingInstance.getDiagnosticClient()),
919                              /*ShouldOwnClient=*/true);
920 
921   Instance.setVirtualFileSystem(&ImportingInstance.getVirtualFileSystem());
922 
923   // Note that this module is part of the module build stack, so that we
924   // can detect cycles in the module graph.
925   Instance.setFileManager(&ImportingInstance.getFileManager());
926   Instance.createSourceManager(Instance.getFileManager());
927   SourceManager &SourceMgr = Instance.getSourceManager();
928   SourceMgr.setModuleBuildStack(
929     ImportingInstance.getSourceManager().getModuleBuildStack());
930   SourceMgr.pushModuleBuildStack(Module->getTopLevelModuleName(),
931     FullSourceLoc(ImportLoc, ImportingInstance.getSourceManager()));
932 
933   // If we're collecting module dependencies, we need to share a collector
934   // between all of the module CompilerInstances.
935   Instance.setModuleDepCollector(ImportingInstance.getModuleDepCollector());
936 
937   // Get or create the module map that we'll use to build this module.
938   std::string InferredModuleMapContent;
939   if (const FileEntry *ModuleMapFile =
940           ModMap.getContainingModuleMapFile(Module)) {
941     // Use the module map where this module resides.
942     FrontendOpts.Inputs.push_back(
943         FrontendInputFile(ModuleMapFile->getName(), IK));
944   } else {
945     llvm::raw_string_ostream OS(InferredModuleMapContent);
946     Module->print(OS);
947     OS.flush();
948     FrontendOpts.Inputs.push_back(
949         FrontendInputFile("__inferred_module.map", IK));
950 
951     std::unique_ptr<llvm::MemoryBuffer> ModuleMapBuffer =
952         llvm::MemoryBuffer::getMemBuffer(InferredModuleMapContent);
953     ModuleMapFile = Instance.getFileManager().getVirtualFile(
954         "__inferred_module.map", InferredModuleMapContent.size(), 0);
955     SourceMgr.overrideFileContents(ModuleMapFile, std::move(ModuleMapBuffer));
956   }
957 
958   // Construct a module-generating action. Passing through the module map is
959   // safe because the FileManager is shared between the compiler instances.
960   GenerateModuleAction CreateModuleAction(
961       ModMap.getModuleMapFileForUniquing(Module), Module->IsSystem);
962 
963   // Execute the action to actually build the module in-place. Use a separate
964   // thread so that we get a stack large enough.
965   const unsigned ThreadStackSize = 8 << 20;
966   llvm::CrashRecoveryContext CRC;
967   CRC.RunSafelyOnThread([&]() { Instance.ExecuteAction(CreateModuleAction); },
968                         ThreadStackSize);
969 
970   // Delete the temporary module map file.
971   // FIXME: Even though we're executing under crash protection, it would still
972   // be nice to do this with RemoveFileOnSignal when we can. However, that
973   // doesn't make sense for all clients, so clean this up manually.
974   Instance.clearOutputFiles(/*EraseFiles=*/true);
975 
976   // We've rebuilt a module. If we're allowed to generate or update the global
977   // module index, record that fact in the importing compiler instance.
978   if (ImportingInstance.getFrontendOpts().GenerateGlobalModuleIndex) {
979     ImportingInstance.setBuildGlobalModuleIndex(true);
980   }
981 
982   return !Instance.getDiagnostics().hasErrorOccurred();
983 }
984 
985 static bool compileAndLoadModule(CompilerInstance &ImportingInstance,
986                                  SourceLocation ImportLoc,
987                                  SourceLocation ModuleNameLoc, Module *Module,
988                                  StringRef ModuleFileName) {
989   auto diagnoseBuildFailure = [&] {
990     ImportingInstance.getDiagnostics().Report(ModuleNameLoc,
991                                               diag::err_module_not_built)
992         << Module->Name << SourceRange(ImportLoc, ModuleNameLoc);
993   };
994 
995   // FIXME: have LockFileManager return an error_code so that we can
996   // avoid the mkdir when the directory already exists.
997   StringRef Dir = llvm::sys::path::parent_path(ModuleFileName);
998   llvm::sys::fs::create_directories(Dir);
999 
1000   while (1) {
1001     unsigned ModuleLoadCapabilities = ASTReader::ARR_Missing;
1002     llvm::LockFileManager Locked(ModuleFileName);
1003     switch (Locked) {
1004     case llvm::LockFileManager::LFS_Error:
1005       return false;
1006 
1007     case llvm::LockFileManager::LFS_Owned:
1008       // We're responsible for building the module ourselves.
1009       if (!compileModuleImpl(ImportingInstance, ModuleNameLoc, Module,
1010                              ModuleFileName)) {
1011         diagnoseBuildFailure();
1012         return false;
1013       }
1014       break;
1015 
1016     case llvm::LockFileManager::LFS_Shared:
1017       // Someone else is responsible for building the module. Wait for them to
1018       // finish.
1019       if (Locked.waitForUnlock() == llvm::LockFileManager::Res_OwnerDied)
1020         continue; // try again to get the lock.
1021       ModuleLoadCapabilities |= ASTReader::ARR_OutOfDate;
1022       break;
1023     }
1024 
1025     // Try to read the module file, now that we've compiled it.
1026     ASTReader::ASTReadResult ReadResult =
1027         ImportingInstance.getModuleManager()->ReadAST(
1028             ModuleFileName, serialization::MK_Module, ImportLoc,
1029             ModuleLoadCapabilities);
1030 
1031     if (ReadResult == ASTReader::OutOfDate &&
1032         Locked == llvm::LockFileManager::LFS_Shared) {
1033       // The module may be out of date in the presence of file system races,
1034       // or if one of its imports depends on header search paths that are not
1035       // consistent with this ImportingInstance.  Try again...
1036       continue;
1037     } else if (ReadResult == ASTReader::Missing) {
1038       diagnoseBuildFailure();
1039     }
1040     return ReadResult == ASTReader::Success;
1041   }
1042 }
1043 
1044 /// \brief Diagnose differences between the current definition of the given
1045 /// configuration macro and the definition provided on the command line.
1046 static void checkConfigMacro(Preprocessor &PP, StringRef ConfigMacro,
1047                              Module *Mod, SourceLocation ImportLoc) {
1048   IdentifierInfo *Id = PP.getIdentifierInfo(ConfigMacro);
1049   SourceManager &SourceMgr = PP.getSourceManager();
1050 
1051   // If this identifier has never had a macro definition, then it could
1052   // not have changed.
1053   if (!Id->hadMacroDefinition())
1054     return;
1055 
1056   // If this identifier does not currently have a macro definition,
1057   // check whether it had one on the command line.
1058   if (!Id->hasMacroDefinition()) {
1059     MacroDirective::DefInfo LatestDef =
1060         PP.getMacroDirectiveHistory(Id)->getDefinition();
1061     for (MacroDirective::DefInfo Def = LatestDef; Def;
1062            Def = Def.getPreviousDefinition()) {
1063       FileID FID = SourceMgr.getFileID(Def.getLocation());
1064       if (FID.isInvalid())
1065         continue;
1066 
1067       // We only care about the predefines buffer.
1068       if (FID != PP.getPredefinesFileID())
1069         continue;
1070 
1071       // This macro was defined on the command line, then #undef'd later.
1072       // Complain.
1073       PP.Diag(ImportLoc, diag::warn_module_config_macro_undef)
1074         << true << ConfigMacro << Mod->getFullModuleName();
1075       if (LatestDef.isUndefined())
1076         PP.Diag(LatestDef.getUndefLocation(), diag::note_module_def_undef_here)
1077           << true;
1078       return;
1079     }
1080 
1081     // Okay: no definition in the predefines buffer.
1082     return;
1083   }
1084 
1085   // This identifier has a macro definition. Check whether we had a definition
1086   // on the command line.
1087   MacroDirective::DefInfo LatestDef =
1088       PP.getMacroDirectiveHistory(Id)->getDefinition();
1089   MacroDirective::DefInfo PredefinedDef;
1090   for (MacroDirective::DefInfo Def = LatestDef; Def;
1091          Def = Def.getPreviousDefinition()) {
1092     FileID FID = SourceMgr.getFileID(Def.getLocation());
1093     if (FID.isInvalid())
1094       continue;
1095 
1096     // We only care about the predefines buffer.
1097     if (FID != PP.getPredefinesFileID())
1098       continue;
1099 
1100     PredefinedDef = Def;
1101     break;
1102   }
1103 
1104   // If there was no definition for this macro in the predefines buffer,
1105   // complain.
1106   if (!PredefinedDef ||
1107       (!PredefinedDef.getLocation().isValid() &&
1108        PredefinedDef.getUndefLocation().isValid())) {
1109     PP.Diag(ImportLoc, diag::warn_module_config_macro_undef)
1110       << false << ConfigMacro << Mod->getFullModuleName();
1111     PP.Diag(LatestDef.getLocation(), diag::note_module_def_undef_here)
1112       << false;
1113     return;
1114   }
1115 
1116   // If the current macro definition is the same as the predefined macro
1117   // definition, it's okay.
1118   if (LatestDef.getMacroInfo() == PredefinedDef.getMacroInfo() ||
1119       LatestDef.getMacroInfo()->isIdenticalTo(*PredefinedDef.getMacroInfo(),PP,
1120                                               /*Syntactically=*/true))
1121     return;
1122 
1123   // The macro definitions differ.
1124   PP.Diag(ImportLoc, diag::warn_module_config_macro_undef)
1125     << false << ConfigMacro << Mod->getFullModuleName();
1126   PP.Diag(LatestDef.getLocation(), diag::note_module_def_undef_here)
1127     << false;
1128 }
1129 
1130 /// \brief Write a new timestamp file with the given path.
1131 static void writeTimestampFile(StringRef TimestampFile) {
1132   std::error_code EC;
1133   llvm::raw_fd_ostream Out(TimestampFile.str(), EC, llvm::sys::fs::F_None);
1134 }
1135 
1136 /// \brief Prune the module cache of modules that haven't been accessed in
1137 /// a long time.
1138 static void pruneModuleCache(const HeaderSearchOptions &HSOpts) {
1139   struct stat StatBuf;
1140   llvm::SmallString<128> TimestampFile;
1141   TimestampFile = HSOpts.ModuleCachePath;
1142   llvm::sys::path::append(TimestampFile, "modules.timestamp");
1143 
1144   // Try to stat() the timestamp file.
1145   if (::stat(TimestampFile.c_str(), &StatBuf)) {
1146     // If the timestamp file wasn't there, create one now.
1147     if (errno == ENOENT) {
1148       writeTimestampFile(TimestampFile);
1149     }
1150     return;
1151   }
1152 
1153   // Check whether the time stamp is older than our pruning interval.
1154   // If not, do nothing.
1155   time_t TimeStampModTime = StatBuf.st_mtime;
1156   time_t CurrentTime = time(nullptr);
1157   if (CurrentTime - TimeStampModTime <= time_t(HSOpts.ModuleCachePruneInterval))
1158     return;
1159 
1160   // Write a new timestamp file so that nobody else attempts to prune.
1161   // There is a benign race condition here, if two Clang instances happen to
1162   // notice at the same time that the timestamp is out-of-date.
1163   writeTimestampFile(TimestampFile);
1164 
1165   // Walk the entire module cache, looking for unused module files and module
1166   // indices.
1167   std::error_code EC;
1168   SmallString<128> ModuleCachePathNative;
1169   llvm::sys::path::native(HSOpts.ModuleCachePath, ModuleCachePathNative);
1170   for (llvm::sys::fs::directory_iterator
1171          Dir(ModuleCachePathNative.str(), EC), DirEnd;
1172        Dir != DirEnd && !EC; Dir.increment(EC)) {
1173     // If we don't have a directory, there's nothing to look into.
1174     if (!llvm::sys::fs::is_directory(Dir->path()))
1175       continue;
1176 
1177     // Walk all of the files within this directory.
1178     for (llvm::sys::fs::directory_iterator File(Dir->path(), EC), FileEnd;
1179          File != FileEnd && !EC; File.increment(EC)) {
1180       // We only care about module and global module index files.
1181       StringRef Extension = llvm::sys::path::extension(File->path());
1182       if (Extension != ".pcm" && Extension != ".timestamp" &&
1183           llvm::sys::path::filename(File->path()) != "modules.idx")
1184         continue;
1185 
1186       // Look at this file. If we can't stat it, there's nothing interesting
1187       // there.
1188       if (::stat(File->path().c_str(), &StatBuf))
1189         continue;
1190 
1191       // If the file has been used recently enough, leave it there.
1192       time_t FileAccessTime = StatBuf.st_atime;
1193       if (CurrentTime - FileAccessTime <=
1194               time_t(HSOpts.ModuleCachePruneAfter)) {
1195         continue;
1196       }
1197 
1198       // Remove the file.
1199       llvm::sys::fs::remove(File->path());
1200 
1201       // Remove the timestamp file.
1202       std::string TimpestampFilename = File->path() + ".timestamp";
1203       llvm::sys::fs::remove(TimpestampFilename);
1204     }
1205 
1206     // If we removed all of the files in the directory, remove the directory
1207     // itself.
1208     if (llvm::sys::fs::directory_iterator(Dir->path(), EC) ==
1209             llvm::sys::fs::directory_iterator() && !EC)
1210       llvm::sys::fs::remove(Dir->path());
1211   }
1212 }
1213 
1214 void CompilerInstance::createModuleManager() {
1215   if (!ModuleManager) {
1216     if (!hasASTContext())
1217       createASTContext();
1218 
1219     // If we're not recursively building a module, check whether we
1220     // need to prune the module cache.
1221     if (getSourceManager().getModuleBuildStack().empty() &&
1222         getHeaderSearchOpts().ModuleCachePruneInterval > 0 &&
1223         getHeaderSearchOpts().ModuleCachePruneAfter > 0) {
1224       pruneModuleCache(getHeaderSearchOpts());
1225     }
1226 
1227     HeaderSearchOptions &HSOpts = getHeaderSearchOpts();
1228     std::string Sysroot = HSOpts.Sysroot;
1229     const PreprocessorOptions &PPOpts = getPreprocessorOpts();
1230     ModuleManager = new ASTReader(getPreprocessor(), *Context,
1231                                   Sysroot.empty() ? "" : Sysroot.c_str(),
1232                                   PPOpts.DisablePCHValidation,
1233                                   /*AllowASTWithCompilerErrors=*/false,
1234                                   /*AllowConfigurationMismatch=*/false,
1235                                   HSOpts.ModulesValidateSystemHeaders,
1236                                   getFrontendOpts().UseGlobalModuleIndex);
1237     if (hasASTConsumer()) {
1238       ModuleManager->setDeserializationListener(
1239         getASTConsumer().GetASTDeserializationListener());
1240       getASTContext().setASTMutationListener(
1241         getASTConsumer().GetASTMutationListener());
1242     }
1243     getASTContext().setExternalSource(ModuleManager);
1244     if (hasSema())
1245       ModuleManager->InitializeSema(getSema());
1246     if (hasASTConsumer())
1247       ModuleManager->StartTranslationUnit(&getASTConsumer());
1248   }
1249 }
1250 
1251 ModuleLoadResult
1252 CompilerInstance::loadModule(SourceLocation ImportLoc,
1253                              ModuleIdPath Path,
1254                              Module::NameVisibilityKind Visibility,
1255                              bool IsInclusionDirective) {
1256   // Determine what file we're searching from.
1257   StringRef ModuleName = Path[0].first->getName();
1258   SourceLocation ModuleNameLoc = Path[0].second;
1259 
1260   // If we've already handled this import, just return the cached result.
1261   // This one-element cache is important to eliminate redundant diagnostics
1262   // when both the preprocessor and parser see the same import declaration.
1263   if (!ImportLoc.isInvalid() && LastModuleImportLoc == ImportLoc) {
1264     // Make the named module visible.
1265     if (LastModuleImportResult && ModuleName != getLangOpts().CurrentModule &&
1266         ModuleName != getLangOpts().ImplementationOfModule)
1267       ModuleManager->makeModuleVisible(LastModuleImportResult, Visibility,
1268                                        ImportLoc, /*Complain=*/false);
1269     return LastModuleImportResult;
1270   }
1271 
1272   clang::Module *Module = nullptr;
1273 
1274   // If we don't already have information on this module, load the module now.
1275   llvm::DenseMap<const IdentifierInfo *, clang::Module *>::iterator Known
1276     = KnownModules.find(Path[0].first);
1277   if (Known != KnownModules.end()) {
1278     // Retrieve the cached top-level module.
1279     Module = Known->second;
1280   } else if (ModuleName == getLangOpts().CurrentModule ||
1281              ModuleName == getLangOpts().ImplementationOfModule) {
1282     // This is the module we're building.
1283     Module = PP->getHeaderSearchInfo().lookupModule(ModuleName);
1284     Known = KnownModules.insert(std::make_pair(Path[0].first, Module)).first;
1285   } else {
1286     // Search for a module with the given name.
1287     Module = PP->getHeaderSearchInfo().lookupModule(ModuleName);
1288     if (!Module) {
1289       getDiagnostics().Report(ModuleNameLoc, diag::err_module_not_found)
1290       << ModuleName
1291       << SourceRange(ImportLoc, ModuleNameLoc);
1292       ModuleBuildFailed = true;
1293       return ModuleLoadResult();
1294     }
1295 
1296     std::string ModuleFileName =
1297         PP->getHeaderSearchInfo().getModuleFileName(Module);
1298 
1299     // If we don't already have an ASTReader, create one now.
1300     if (!ModuleManager)
1301       createModuleManager();
1302 
1303     if (TheDependencyFileGenerator)
1304       TheDependencyFileGenerator->AttachToASTReader(*ModuleManager);
1305 
1306     if (ModuleDepCollector)
1307       ModuleDepCollector->attachToASTReader(*ModuleManager);
1308 
1309     for (auto &Listener : DependencyCollectors)
1310       Listener->attachToASTReader(*ModuleManager);
1311 
1312     // Try to load the module file.
1313     unsigned ARRFlags = ASTReader::ARR_OutOfDate | ASTReader::ARR_Missing;
1314     switch (ModuleManager->ReadAST(ModuleFileName, serialization::MK_Module,
1315                                    ImportLoc, ARRFlags)) {
1316     case ASTReader::Success:
1317       break;
1318 
1319     case ASTReader::OutOfDate:
1320     case ASTReader::Missing: {
1321       // The module file is missing or out-of-date. Build it.
1322       assert(Module && "missing module file");
1323       // Check whether there is a cycle in the module graph.
1324       ModuleBuildStack ModPath = getSourceManager().getModuleBuildStack();
1325       ModuleBuildStack::iterator Pos = ModPath.begin(), PosEnd = ModPath.end();
1326       for (; Pos != PosEnd; ++Pos) {
1327         if (Pos->first == ModuleName)
1328           break;
1329       }
1330 
1331       if (Pos != PosEnd) {
1332         SmallString<256> CyclePath;
1333         for (; Pos != PosEnd; ++Pos) {
1334           CyclePath += Pos->first;
1335           CyclePath += " -> ";
1336         }
1337         CyclePath += ModuleName;
1338 
1339         getDiagnostics().Report(ModuleNameLoc, diag::err_module_cycle)
1340           << ModuleName << CyclePath;
1341         return ModuleLoadResult();
1342       }
1343 
1344       getDiagnostics().Report(ImportLoc, diag::remark_module_build)
1345           << ModuleName << ModuleFileName;
1346 
1347       // Check whether we have already attempted to build this module (but
1348       // failed).
1349       if (getPreprocessorOpts().FailedModules &&
1350           getPreprocessorOpts().FailedModules->hasAlreadyFailed(ModuleName)) {
1351         getDiagnostics().Report(ModuleNameLoc, diag::err_module_not_built)
1352           << ModuleName
1353           << SourceRange(ImportLoc, ModuleNameLoc);
1354         ModuleBuildFailed = true;
1355         return ModuleLoadResult();
1356       }
1357 
1358       // Try to compile and then load the module.
1359       if (!compileAndLoadModule(*this, ImportLoc, ModuleNameLoc, Module,
1360                                 ModuleFileName)) {
1361         if (getPreprocessorOpts().FailedModules)
1362           getPreprocessorOpts().FailedModules->addFailed(ModuleName);
1363         KnownModules[Path[0].first] = nullptr;
1364         ModuleBuildFailed = true;
1365         return ModuleLoadResult();
1366       }
1367 
1368       // Okay, we've rebuilt and now loaded the module.
1369       break;
1370     }
1371 
1372     case ASTReader::VersionMismatch:
1373     case ASTReader::ConfigurationMismatch:
1374     case ASTReader::HadErrors:
1375       ModuleLoader::HadFatalFailure = true;
1376       // FIXME: The ASTReader will already have complained, but can we showhorn
1377       // that diagnostic information into a more useful form?
1378       KnownModules[Path[0].first] = nullptr;
1379       return ModuleLoadResult();
1380 
1381     case ASTReader::Failure:
1382       ModuleLoader::HadFatalFailure = true;
1383       // Already complained, but note now that we failed.
1384       KnownModules[Path[0].first] = nullptr;
1385       ModuleBuildFailed = true;
1386       return ModuleLoadResult();
1387     }
1388 
1389     // Cache the result of this top-level module lookup for later.
1390     Known = KnownModules.insert(std::make_pair(Path[0].first, Module)).first;
1391   }
1392 
1393   // If we never found the module, fail.
1394   if (!Module)
1395     return ModuleLoadResult();
1396 
1397   // Verify that the rest of the module path actually corresponds to
1398   // a submodule.
1399   if (Path.size() > 1) {
1400     for (unsigned I = 1, N = Path.size(); I != N; ++I) {
1401       StringRef Name = Path[I].first->getName();
1402       clang::Module *Sub = Module->findSubmodule(Name);
1403 
1404       if (!Sub) {
1405         // Attempt to perform typo correction to find a module name that works.
1406         SmallVector<StringRef, 2> Best;
1407         unsigned BestEditDistance = (std::numeric_limits<unsigned>::max)();
1408 
1409         for (clang::Module::submodule_iterator J = Module->submodule_begin(),
1410                                             JEnd = Module->submodule_end();
1411              J != JEnd; ++J) {
1412           unsigned ED = Name.edit_distance((*J)->Name,
1413                                            /*AllowReplacements=*/true,
1414                                            BestEditDistance);
1415           if (ED <= BestEditDistance) {
1416             if (ED < BestEditDistance) {
1417               Best.clear();
1418               BestEditDistance = ED;
1419             }
1420 
1421             Best.push_back((*J)->Name);
1422           }
1423         }
1424 
1425         // If there was a clear winner, user it.
1426         if (Best.size() == 1) {
1427           getDiagnostics().Report(Path[I].second,
1428                                   diag::err_no_submodule_suggest)
1429             << Path[I].first << Module->getFullModuleName() << Best[0]
1430             << SourceRange(Path[0].second, Path[I-1].second)
1431             << FixItHint::CreateReplacement(SourceRange(Path[I].second),
1432                                             Best[0]);
1433 
1434           Sub = Module->findSubmodule(Best[0]);
1435         }
1436       }
1437 
1438       if (!Sub) {
1439         // No submodule by this name. Complain, and don't look for further
1440         // submodules.
1441         getDiagnostics().Report(Path[I].second, diag::err_no_submodule)
1442           << Path[I].first << Module->getFullModuleName()
1443           << SourceRange(Path[0].second, Path[I-1].second);
1444         break;
1445       }
1446 
1447       Module = Sub;
1448     }
1449   }
1450 
1451   // Don't make the module visible if we are in the implementation.
1452   if (ModuleName == getLangOpts().ImplementationOfModule)
1453     return ModuleLoadResult(Module, false);
1454 
1455   // Make the named module visible, if it's not already part of the module
1456   // we are parsing.
1457   if (ModuleName != getLangOpts().CurrentModule) {
1458     if (!Module->IsFromModuleFile) {
1459       // We have an umbrella header or directory that doesn't actually include
1460       // all of the headers within the directory it covers. Complain about
1461       // this missing submodule and recover by forgetting that we ever saw
1462       // this submodule.
1463       // FIXME: Should we detect this at module load time? It seems fairly
1464       // expensive (and rare).
1465       getDiagnostics().Report(ImportLoc, diag::warn_missing_submodule)
1466         << Module->getFullModuleName()
1467         << SourceRange(Path.front().second, Path.back().second);
1468 
1469       return ModuleLoadResult(nullptr, true);
1470     }
1471 
1472     // Check whether this module is available.
1473     clang::Module::Requirement Requirement;
1474     clang::Module::HeaderDirective MissingHeader;
1475     if (!Module->isAvailable(getLangOpts(), getTarget(), Requirement,
1476                              MissingHeader)) {
1477       if (MissingHeader.FileNameLoc.isValid()) {
1478         getDiagnostics().Report(MissingHeader.FileNameLoc,
1479                                 diag::err_module_header_missing)
1480           << MissingHeader.IsUmbrella << MissingHeader.FileName;
1481       } else {
1482         getDiagnostics().Report(ImportLoc, diag::err_module_unavailable)
1483           << Module->getFullModuleName()
1484           << Requirement.second << Requirement.first
1485           << SourceRange(Path.front().second, Path.back().second);
1486       }
1487       LastModuleImportLoc = ImportLoc;
1488       LastModuleImportResult = ModuleLoadResult();
1489       return ModuleLoadResult();
1490     }
1491 
1492     ModuleManager->makeModuleVisible(Module, Visibility, ImportLoc,
1493                                      /*Complain=*/true);
1494   }
1495 
1496   // Check for any configuration macros that have changed.
1497   clang::Module *TopModule = Module->getTopLevelModule();
1498   for (unsigned I = 0, N = TopModule->ConfigMacros.size(); I != N; ++I) {
1499     checkConfigMacro(getPreprocessor(), TopModule->ConfigMacros[I],
1500                      Module, ImportLoc);
1501   }
1502 
1503   // If this module import was due to an inclusion directive, create an
1504   // implicit import declaration to capture it in the AST.
1505   if (IsInclusionDirective && hasASTContext()) {
1506     TranslationUnitDecl *TU = getASTContext().getTranslationUnitDecl();
1507     ImportDecl *ImportD = ImportDecl::CreateImplicit(getASTContext(), TU,
1508                                                      ImportLoc, Module,
1509                                                      Path.back().second);
1510     TU->addDecl(ImportD);
1511     if (Consumer)
1512       Consumer->HandleImplicitImportDecl(ImportD);
1513   }
1514 
1515   LastModuleImportLoc = ImportLoc;
1516   LastModuleImportResult = ModuleLoadResult(Module, false);
1517   return LastModuleImportResult;
1518 }
1519 
1520 void CompilerInstance::makeModuleVisible(Module *Mod,
1521                                          Module::NameVisibilityKind Visibility,
1522                                          SourceLocation ImportLoc,
1523                                          bool Complain){
1524   ModuleManager->makeModuleVisible(Mod, Visibility, ImportLoc, Complain);
1525 }
1526 
1527 GlobalModuleIndex *CompilerInstance::loadGlobalModuleIndex(
1528     SourceLocation TriggerLoc) {
1529   if (!ModuleManager)
1530     createModuleManager();
1531   // Can't do anything if we don't have the module manager.
1532   if (!ModuleManager)
1533     return nullptr;
1534   // Get an existing global index.  This loads it if not already
1535   // loaded.
1536   ModuleManager->loadGlobalIndex();
1537   GlobalModuleIndex *GlobalIndex = ModuleManager->getGlobalIndex();
1538   // If the global index doesn't exist, create it.
1539   if (!GlobalIndex && shouldBuildGlobalModuleIndex() && hasFileManager() &&
1540       hasPreprocessor()) {
1541     llvm::sys::fs::create_directories(
1542       getPreprocessor().getHeaderSearchInfo().getModuleCachePath());
1543     GlobalModuleIndex::writeIndex(
1544       getFileManager(),
1545       getPreprocessor().getHeaderSearchInfo().getModuleCachePath());
1546     ModuleManager->resetForReload();
1547     ModuleManager->loadGlobalIndex();
1548     GlobalIndex = ModuleManager->getGlobalIndex();
1549   }
1550   // For finding modules needing to be imported for fixit messages,
1551   // we need to make the global index cover all modules, so we do that here.
1552   if (!HaveFullGlobalModuleIndex && GlobalIndex && !buildingModule()) {
1553     ModuleMap &MMap = getPreprocessor().getHeaderSearchInfo().getModuleMap();
1554     bool RecreateIndex = false;
1555     for (ModuleMap::module_iterator I = MMap.module_begin(),
1556         E = MMap.module_end(); I != E; ++I) {
1557       Module *TheModule = I->second;
1558       const FileEntry *Entry = TheModule->getASTFile();
1559       if (!Entry) {
1560         SmallVector<std::pair<IdentifierInfo *, SourceLocation>, 2> Path;
1561         Path.push_back(std::make_pair(
1562 				  getPreprocessor().getIdentifierInfo(TheModule->Name), TriggerLoc));
1563         std::reverse(Path.begin(), Path.end());
1564 		    // Load a module as hidden.  This also adds it to the global index.
1565         loadModule(TheModule->DefinitionLoc, Path,
1566                                              Module::Hidden, false);
1567         RecreateIndex = true;
1568       }
1569     }
1570     if (RecreateIndex) {
1571       GlobalModuleIndex::writeIndex(
1572         getFileManager(),
1573         getPreprocessor().getHeaderSearchInfo().getModuleCachePath());
1574       ModuleManager->resetForReload();
1575       ModuleManager->loadGlobalIndex();
1576       GlobalIndex = ModuleManager->getGlobalIndex();
1577     }
1578     HaveFullGlobalModuleIndex = true;
1579   }
1580   return GlobalIndex;
1581 }
1582 
1583 // Check global module index for missing imports.
1584 bool
1585 CompilerInstance::lookupMissingImports(StringRef Name,
1586                                        SourceLocation TriggerLoc) {
1587   // Look for the symbol in non-imported modules, but only if an error
1588   // actually occurred.
1589   if (!buildingModule()) {
1590     // Load global module index, or retrieve a previously loaded one.
1591     GlobalModuleIndex *GlobalIndex = loadGlobalModuleIndex(
1592       TriggerLoc);
1593 
1594     // Only if we have a global index.
1595     if (GlobalIndex) {
1596       GlobalModuleIndex::HitSet FoundModules;
1597 
1598       // Find the modules that reference the identifier.
1599       // Note that this only finds top-level modules.
1600       // We'll let diagnoseTypo find the actual declaration module.
1601       if (GlobalIndex->lookupIdentifier(Name, FoundModules))
1602         return true;
1603     }
1604   }
1605 
1606   return false;
1607 }
1608 void CompilerInstance::resetAndLeakSema() { BuryPointer(takeSema()); }
1609