1 //===--- PrecompiledPreamble.cpp - Build precompiled preambles --*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // Helper class to build precompiled preamble.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "clang/Frontend/PrecompiledPreamble.h"
14 #include "clang/AST/DeclObjC.h"
15 #include "clang/Basic/FileManager.h"
16 #include "clang/Basic/LangStandard.h"
17 #include "clang/Basic/TargetInfo.h"
18 #include "clang/Frontend/CompilerInstance.h"
19 #include "clang/Frontend/CompilerInvocation.h"
20 #include "clang/Frontend/FrontendActions.h"
21 #include "clang/Frontend/FrontendOptions.h"
22 #include "clang/Lex/HeaderSearch.h"
23 #include "clang/Lex/Lexer.h"
24 #include "clang/Lex/Preprocessor.h"
25 #include "clang/Lex/PreprocessorOptions.h"
26 #include "clang/Serialization/ASTWriter.h"
27 #include "llvm/ADT/SmallString.h"
28 #include "llvm/ADT/StringExtras.h"
29 #include "llvm/ADT/StringSet.h"
30 #include "llvm/ADT/iterator_range.h"
31 #include "llvm/Config/llvm-config.h"
32 #include "llvm/Support/CrashRecoveryContext.h"
33 #include "llvm/Support/FileSystem.h"
34 #include "llvm/Support/Path.h"
35 #include "llvm/Support/Process.h"
36 #include "llvm/Support/VirtualFileSystem.h"
37 #include <limits>
38 #include <mutex>
39 #include <utility>
40
41 using namespace clang;
42
43 namespace {
44
getInMemoryPreamblePath()45 StringRef getInMemoryPreamblePath() {
46 #if defined(LLVM_ON_UNIX)
47 return "/__clang_tmp/___clang_inmemory_preamble___";
48 #elif defined(_WIN32)
49 return "C:\\__clang_tmp\\___clang_inmemory_preamble___";
50 #else
51 #warning "Unknown platform. Defaulting to UNIX-style paths for in-memory PCHs"
52 return "/__clang_tmp/___clang_inmemory_preamble___";
53 #endif
54 }
55
56 IntrusiveRefCntPtr<llvm::vfs::FileSystem>
createVFSOverlayForPreamblePCH(StringRef PCHFilename,std::unique_ptr<llvm::MemoryBuffer> PCHBuffer,IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS)57 createVFSOverlayForPreamblePCH(StringRef PCHFilename,
58 std::unique_ptr<llvm::MemoryBuffer> PCHBuffer,
59 IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS) {
60 // We want only the PCH file from the real filesystem to be available,
61 // so we create an in-memory VFS with just that and overlay it on top.
62 IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem> PCHFS(
63 new llvm::vfs::InMemoryFileSystem());
64 PCHFS->addFile(PCHFilename, 0, std::move(PCHBuffer));
65 IntrusiveRefCntPtr<llvm::vfs::OverlayFileSystem> Overlay(
66 new llvm::vfs::OverlayFileSystem(VFS));
67 Overlay->pushOverlay(PCHFS);
68 return Overlay;
69 }
70
71 class PreambleDependencyCollector : public DependencyCollector {
72 public:
73 // We want to collect all dependencies for correctness. Avoiding the real
74 // system dependencies (e.g. stl from /usr/lib) would probably be a good idea,
75 // but there is no way to distinguish between those and the ones that can be
76 // spuriously added by '-isystem' (e.g. to suppress warnings from those
77 // headers).
needSystemDependencies()78 bool needSystemDependencies() override { return true; }
79 };
80
81 // Collects files whose existence would invalidate the preamble.
82 // Collecting *all* of these would make validating it too slow though, so we
83 // just find all the candidates for 'file not found' diagnostics.
84 //
85 // A caveat that may be significant for generated files: we'll omit files under
86 // search path entries whose roots don't exist when the preamble is built.
87 // These are pruned by InitHeaderSearch and so we don't see the search path.
88 // It would be nice to include them but we don't want to duplicate all the rest
89 // of the InitHeaderSearch logic to reconstruct them.
90 class MissingFileCollector : public PPCallbacks {
91 llvm::StringSet<> &Out;
92 const HeaderSearch &Search;
93 const SourceManager &SM;
94
95 public:
MissingFileCollector(llvm::StringSet<> & Out,const HeaderSearch & Search,const SourceManager & SM)96 MissingFileCollector(llvm::StringSet<> &Out, const HeaderSearch &Search,
97 const SourceManager &SM)
98 : Out(Out), Search(Search), SM(SM) {}
99
InclusionDirective(SourceLocation HashLoc,const Token & IncludeTok,StringRef FileName,bool IsAngled,CharSourceRange FilenameRange,const FileEntry * File,StringRef SearchPath,StringRef RelativePath,const Module * Imported,SrcMgr::CharacteristicKind FileType)100 void InclusionDirective(SourceLocation HashLoc, const Token &IncludeTok,
101 StringRef FileName, bool IsAngled,
102 CharSourceRange FilenameRange, const FileEntry *File,
103 StringRef SearchPath, StringRef RelativePath,
104 const Module *Imported,
105 SrcMgr::CharacteristicKind FileType) override {
106 // File is null if it wasn't found.
107 // (We have some false negatives if PP recovered e.g. <foo> -> "foo")
108 if (File != nullptr)
109 return;
110
111 // If it's a rare absolute include, we know the full path already.
112 if (llvm::sys::path::is_absolute(FileName)) {
113 Out.insert(FileName);
114 return;
115 }
116
117 // Reconstruct the filenames that would satisfy this directive...
118 llvm::SmallString<256> Buf;
119 auto NotFoundRelativeTo = [&](const DirectoryEntry *DE) {
120 Buf = DE->getName();
121 llvm::sys::path::append(Buf, FileName);
122 llvm::sys::path::remove_dots(Buf, /*remove_dot_dot=*/true);
123 Out.insert(Buf);
124 };
125 // ...relative to the including file.
126 if (!IsAngled) {
127 if (const FileEntry *IncludingFile =
128 SM.getFileEntryForID(SM.getFileID(IncludeTok.getLocation())))
129 if (IncludingFile->getDir())
130 NotFoundRelativeTo(IncludingFile->getDir());
131 }
132 // ...relative to the search paths.
133 for (const auto &Dir : llvm::make_range(
134 IsAngled ? Search.angled_dir_begin() : Search.search_dir_begin(),
135 Search.search_dir_end())) {
136 // No support for frameworks or header maps yet.
137 if (Dir.isNormalDir())
138 NotFoundRelativeTo(Dir.getDir());
139 }
140 }
141 };
142
143 /// Keeps a track of files to be deleted in destructor.
144 class TemporaryFiles {
145 public:
146 // A static instance to be used by all clients.
147 static TemporaryFiles &getInstance();
148
149 private:
150 // Disallow constructing the class directly.
151 TemporaryFiles() = default;
152 // Disallow copy.
153 TemporaryFiles(const TemporaryFiles &) = delete;
154
155 public:
156 ~TemporaryFiles();
157
158 /// Adds \p File to a set of tracked files.
159 void addFile(StringRef File);
160
161 /// Remove \p File from disk and from the set of tracked files.
162 void removeFile(StringRef File);
163
164 private:
165 std::mutex Mutex;
166 llvm::StringSet<> Files;
167 };
168
getInstance()169 TemporaryFiles &TemporaryFiles::getInstance() {
170 static TemporaryFiles Instance;
171 return Instance;
172 }
173
~TemporaryFiles()174 TemporaryFiles::~TemporaryFiles() {
175 std::lock_guard<std::mutex> Guard(Mutex);
176 for (const auto &File : Files)
177 llvm::sys::fs::remove(File.getKey());
178 }
179
addFile(StringRef File)180 void TemporaryFiles::addFile(StringRef File) {
181 std::lock_guard<std::mutex> Guard(Mutex);
182 auto IsInserted = Files.insert(File).second;
183 (void)IsInserted;
184 assert(IsInserted && "File has already been added");
185 }
186
removeFile(StringRef File)187 void TemporaryFiles::removeFile(StringRef File) {
188 std::lock_guard<std::mutex> Guard(Mutex);
189 auto WasPresent = Files.erase(File);
190 (void)WasPresent;
191 assert(WasPresent && "File was not tracked");
192 llvm::sys::fs::remove(File);
193 }
194
195 class PrecompilePreambleAction : public ASTFrontendAction {
196 public:
PrecompilePreambleAction(std::string * InMemStorage,PreambleCallbacks & Callbacks)197 PrecompilePreambleAction(std::string *InMemStorage,
198 PreambleCallbacks &Callbacks)
199 : InMemStorage(InMemStorage), Callbacks(Callbacks) {}
200
201 std::unique_ptr<ASTConsumer> CreateASTConsumer(CompilerInstance &CI,
202 StringRef InFile) override;
203
hasEmittedPreamblePCH() const204 bool hasEmittedPreamblePCH() const { return HasEmittedPreamblePCH; }
205
setEmittedPreamblePCH(ASTWriter & Writer)206 void setEmittedPreamblePCH(ASTWriter &Writer) {
207 this->HasEmittedPreamblePCH = true;
208 Callbacks.AfterPCHEmitted(Writer);
209 }
210
shouldEraseOutputFiles()211 bool shouldEraseOutputFiles() override { return !hasEmittedPreamblePCH(); }
hasCodeCompletionSupport() const212 bool hasCodeCompletionSupport() const override { return false; }
hasASTFileSupport() const213 bool hasASTFileSupport() const override { return false; }
getTranslationUnitKind()214 TranslationUnitKind getTranslationUnitKind() override { return TU_Prefix; }
215
216 private:
217 friend class PrecompilePreambleConsumer;
218
219 bool HasEmittedPreamblePCH = false;
220 std::string *InMemStorage;
221 PreambleCallbacks &Callbacks;
222 };
223
224 class PrecompilePreambleConsumer : public PCHGenerator {
225 public:
PrecompilePreambleConsumer(PrecompilePreambleAction & Action,const Preprocessor & PP,InMemoryModuleCache & ModuleCache,StringRef isysroot,std::unique_ptr<raw_ostream> Out)226 PrecompilePreambleConsumer(PrecompilePreambleAction &Action,
227 const Preprocessor &PP,
228 InMemoryModuleCache &ModuleCache,
229 StringRef isysroot,
230 std::unique_ptr<raw_ostream> Out)
231 : PCHGenerator(PP, ModuleCache, "", isysroot,
232 std::make_shared<PCHBuffer>(),
233 ArrayRef<std::shared_ptr<ModuleFileExtension>>(),
234 /*AllowASTWithErrors=*/true),
235 Action(Action), Out(std::move(Out)) {}
236
HandleTopLevelDecl(DeclGroupRef DG)237 bool HandleTopLevelDecl(DeclGroupRef DG) override {
238 Action.Callbacks.HandleTopLevelDecl(DG);
239 return true;
240 }
241
HandleTranslationUnit(ASTContext & Ctx)242 void HandleTranslationUnit(ASTContext &Ctx) override {
243 PCHGenerator::HandleTranslationUnit(Ctx);
244 if (!hasEmittedPCH())
245 return;
246
247 // Write the generated bitstream to "Out".
248 *Out << getPCH();
249 // Make sure it hits disk now.
250 Out->flush();
251 // Free the buffer.
252 llvm::SmallVector<char, 0> Empty;
253 getPCH() = std::move(Empty);
254
255 Action.setEmittedPreamblePCH(getWriter());
256 }
257
shouldSkipFunctionBody(Decl * D)258 bool shouldSkipFunctionBody(Decl *D) override {
259 return Action.Callbacks.shouldSkipFunctionBody(D);
260 }
261
262 private:
263 PrecompilePreambleAction &Action;
264 std::unique_ptr<raw_ostream> Out;
265 };
266
267 std::unique_ptr<ASTConsumer>
CreateASTConsumer(CompilerInstance & CI,StringRef InFile)268 PrecompilePreambleAction::CreateASTConsumer(CompilerInstance &CI,
269 StringRef InFile) {
270 std::string Sysroot;
271 if (!GeneratePCHAction::ComputeASTConsumerArguments(CI, Sysroot))
272 return nullptr;
273
274 std::unique_ptr<llvm::raw_ostream> OS;
275 if (InMemStorage) {
276 OS = std::make_unique<llvm::raw_string_ostream>(*InMemStorage);
277 } else {
278 std::string OutputFile;
279 OS = GeneratePCHAction::CreateOutputFile(CI, InFile, OutputFile);
280 }
281 if (!OS)
282 return nullptr;
283
284 if (!CI.getFrontendOpts().RelocatablePCH)
285 Sysroot.clear();
286
287 return std::make_unique<PrecompilePreambleConsumer>(
288 *this, CI.getPreprocessor(), CI.getModuleCache(), Sysroot, std::move(OS));
289 }
290
moveOnNoError(llvm::ErrorOr<T> Val,T & Output)291 template <class T> bool moveOnNoError(llvm::ErrorOr<T> Val, T &Output) {
292 if (!Val)
293 return false;
294 Output = std::move(*Val);
295 return true;
296 }
297
298 } // namespace
299
ComputePreambleBounds(const LangOptions & LangOpts,const llvm::MemoryBuffer * Buffer,unsigned MaxLines)300 PreambleBounds clang::ComputePreambleBounds(const LangOptions &LangOpts,
301 const llvm::MemoryBuffer *Buffer,
302 unsigned MaxLines) {
303 return Lexer::ComputePreamble(Buffer->getBuffer(), LangOpts, MaxLines);
304 }
305
Build(const CompilerInvocation & Invocation,const llvm::MemoryBuffer * MainFileBuffer,PreambleBounds Bounds,DiagnosticsEngine & Diagnostics,IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,std::shared_ptr<PCHContainerOperations> PCHContainerOps,bool StoreInMemory,PreambleCallbacks & Callbacks)306 llvm::ErrorOr<PrecompiledPreamble> PrecompiledPreamble::Build(
307 const CompilerInvocation &Invocation,
308 const llvm::MemoryBuffer *MainFileBuffer, PreambleBounds Bounds,
309 DiagnosticsEngine &Diagnostics,
310 IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,
311 std::shared_ptr<PCHContainerOperations> PCHContainerOps, bool StoreInMemory,
312 PreambleCallbacks &Callbacks) {
313 assert(VFS && "VFS is null");
314
315 auto PreambleInvocation = std::make_shared<CompilerInvocation>(Invocation);
316 FrontendOptions &FrontendOpts = PreambleInvocation->getFrontendOpts();
317 PreprocessorOptions &PreprocessorOpts =
318 PreambleInvocation->getPreprocessorOpts();
319
320 llvm::Optional<TempPCHFile> TempFile;
321 if (!StoreInMemory) {
322 // Create a temporary file for the precompiled preamble. In rare
323 // circumstances, this can fail.
324 llvm::ErrorOr<PrecompiledPreamble::TempPCHFile> PreamblePCHFile =
325 PrecompiledPreamble::TempPCHFile::CreateNewPreamblePCHFile();
326 if (!PreamblePCHFile)
327 return BuildPreambleError::CouldntCreateTempFile;
328 TempFile = std::move(*PreamblePCHFile);
329 }
330
331 PCHStorage Storage = StoreInMemory ? PCHStorage(InMemoryPreamble())
332 : PCHStorage(std::move(*TempFile));
333
334 // Save the preamble text for later; we'll need to compare against it for
335 // subsequent reparses.
336 std::vector<char> PreambleBytes(MainFileBuffer->getBufferStart(),
337 MainFileBuffer->getBufferStart() +
338 Bounds.Size);
339 bool PreambleEndsAtStartOfLine = Bounds.PreambleEndsAtStartOfLine;
340
341 // Tell the compiler invocation to generate a temporary precompiled header.
342 FrontendOpts.ProgramAction = frontend::GeneratePCH;
343 FrontendOpts.OutputFile =
344 std::string(StoreInMemory ? getInMemoryPreamblePath()
345 : Storage.asFile().getFilePath());
346 PreprocessorOpts.PrecompiledPreambleBytes.first = 0;
347 PreprocessorOpts.PrecompiledPreambleBytes.second = false;
348 // Inform preprocessor to record conditional stack when building the preamble.
349 PreprocessorOpts.GeneratePreamble = true;
350
351 // Create the compiler instance to use for building the precompiled preamble.
352 std::unique_ptr<CompilerInstance> Clang(
353 new CompilerInstance(std::move(PCHContainerOps)));
354
355 // Recover resources if we crash before exiting this method.
356 llvm::CrashRecoveryContextCleanupRegistrar<CompilerInstance> CICleanup(
357 Clang.get());
358
359 Clang->setInvocation(std::move(PreambleInvocation));
360 Clang->setDiagnostics(&Diagnostics);
361
362 // Create the target instance.
363 Clang->setTarget(TargetInfo::CreateTargetInfo(
364 Clang->getDiagnostics(), Clang->getInvocation().TargetOpts));
365 if (!Clang->hasTarget())
366 return BuildPreambleError::CouldntCreateTargetInfo;
367
368 // Inform the target of the language options.
369 //
370 // FIXME: We shouldn't need to do this, the target should be immutable once
371 // created. This complexity should be lifted elsewhere.
372 Clang->getTarget().adjust(Clang->getLangOpts());
373
374 if (Clang->getFrontendOpts().Inputs.size() != 1 ||
375 Clang->getFrontendOpts().Inputs[0].getKind().getFormat() !=
376 InputKind::Source ||
377 Clang->getFrontendOpts().Inputs[0].getKind().getLanguage() ==
378 Language::LLVM_IR) {
379 return BuildPreambleError::BadInputs;
380 }
381
382 // Clear out old caches and data.
383 Diagnostics.Reset();
384 ProcessWarningOptions(Diagnostics, Clang->getDiagnosticOpts());
385
386 VFS =
387 createVFSFromCompilerInvocation(Clang->getInvocation(), Diagnostics, VFS);
388
389 // Create a file manager object to provide access to and cache the filesystem.
390 Clang->setFileManager(new FileManager(Clang->getFileSystemOpts(), VFS));
391
392 // Create the source manager.
393 Clang->setSourceManager(
394 new SourceManager(Diagnostics, Clang->getFileManager()));
395
396 auto PreambleDepCollector = std::make_shared<PreambleDependencyCollector>();
397 Clang->addDependencyCollector(PreambleDepCollector);
398
399 // Remap the main source file to the preamble buffer.
400 StringRef MainFilePath = FrontendOpts.Inputs[0].getFile();
401 auto PreambleInputBuffer = llvm::MemoryBuffer::getMemBufferCopy(
402 MainFileBuffer->getBuffer().slice(0, Bounds.Size), MainFilePath);
403 if (PreprocessorOpts.RetainRemappedFileBuffers) {
404 // MainFileBuffer will be deleted by unique_ptr after leaving the method.
405 PreprocessorOpts.addRemappedFile(MainFilePath, PreambleInputBuffer.get());
406 } else {
407 // In that case, remapped buffer will be deleted by CompilerInstance on
408 // BeginSourceFile, so we call release() to avoid double deletion.
409 PreprocessorOpts.addRemappedFile(MainFilePath,
410 PreambleInputBuffer.release());
411 }
412
413 std::unique_ptr<PrecompilePreambleAction> Act;
414 Act.reset(new PrecompilePreambleAction(
415 StoreInMemory ? &Storage.asMemory().Data : nullptr, Callbacks));
416 Callbacks.BeforeExecute(*Clang);
417 if (!Act->BeginSourceFile(*Clang.get(), Clang->getFrontendOpts().Inputs[0]))
418 return BuildPreambleError::BeginSourceFileFailed;
419
420 std::unique_ptr<PPCallbacks> DelegatedPPCallbacks =
421 Callbacks.createPPCallbacks();
422 if (DelegatedPPCallbacks)
423 Clang->getPreprocessor().addPPCallbacks(std::move(DelegatedPPCallbacks));
424 if (auto CommentHandler = Callbacks.getCommentHandler())
425 Clang->getPreprocessor().addCommentHandler(CommentHandler);
426 llvm::StringSet<> MissingFiles;
427 Clang->getPreprocessor().addPPCallbacks(
428 std::make_unique<MissingFileCollector>(
429 MissingFiles, Clang->getPreprocessor().getHeaderSearchInfo(),
430 Clang->getSourceManager()));
431
432 if (llvm::Error Err = Act->Execute())
433 return errorToErrorCode(std::move(Err));
434
435 // Run the callbacks.
436 Callbacks.AfterExecute(*Clang);
437
438 Act->EndSourceFile();
439
440 if (!Act->hasEmittedPreamblePCH())
441 return BuildPreambleError::CouldntEmitPCH;
442
443 // Keep track of all of the files that the source manager knows about,
444 // so we can verify whether they have changed or not.
445 llvm::StringMap<PrecompiledPreamble::PreambleFileHash> FilesInPreamble;
446
447 SourceManager &SourceMgr = Clang->getSourceManager();
448 for (auto &Filename : PreambleDepCollector->getDependencies()) {
449 auto FileOrErr = Clang->getFileManager().getFile(Filename);
450 if (!FileOrErr ||
451 *FileOrErr == SourceMgr.getFileEntryForID(SourceMgr.getMainFileID()))
452 continue;
453 auto File = *FileOrErr;
454 if (time_t ModTime = File->getModificationTime()) {
455 FilesInPreamble[File->getName()] =
456 PrecompiledPreamble::PreambleFileHash::createForFile(File->getSize(),
457 ModTime);
458 } else {
459 const llvm::MemoryBuffer *Buffer = SourceMgr.getMemoryBufferForFile(File);
460 FilesInPreamble[File->getName()] =
461 PrecompiledPreamble::PreambleFileHash::createForMemoryBuffer(Buffer);
462 }
463 }
464
465 return PrecompiledPreamble(
466 std::move(Storage), std::move(PreambleBytes), PreambleEndsAtStartOfLine,
467 std::move(FilesInPreamble), std::move(MissingFiles));
468 }
469
getBounds() const470 PreambleBounds PrecompiledPreamble::getBounds() const {
471 return PreambleBounds(PreambleBytes.size(), PreambleEndsAtStartOfLine);
472 }
473
getSize() const474 std::size_t PrecompiledPreamble::getSize() const {
475 switch (Storage.getKind()) {
476 case PCHStorage::Kind::Empty:
477 assert(false && "Calling getSize() on invalid PrecompiledPreamble. "
478 "Was it std::moved?");
479 return 0;
480 case PCHStorage::Kind::InMemory:
481 return Storage.asMemory().Data.size();
482 case PCHStorage::Kind::TempFile: {
483 uint64_t Result;
484 if (llvm::sys::fs::file_size(Storage.asFile().getFilePath(), Result))
485 return 0;
486
487 assert(Result <= std::numeric_limits<std::size_t>::max() &&
488 "file size did not fit into size_t");
489 return Result;
490 }
491 }
492 llvm_unreachable("Unhandled storage kind");
493 }
494
CanReuse(const CompilerInvocation & Invocation,const llvm::MemoryBuffer * MainFileBuffer,PreambleBounds Bounds,llvm::vfs::FileSystem * VFS) const495 bool PrecompiledPreamble::CanReuse(const CompilerInvocation &Invocation,
496 const llvm::MemoryBuffer *MainFileBuffer,
497 PreambleBounds Bounds,
498 llvm::vfs::FileSystem *VFS) const {
499
500 assert(
501 Bounds.Size <= MainFileBuffer->getBufferSize() &&
502 "Buffer is too large. Bounds were calculated from a different buffer?");
503
504 auto PreambleInvocation = std::make_shared<CompilerInvocation>(Invocation);
505 PreprocessorOptions &PreprocessorOpts =
506 PreambleInvocation->getPreprocessorOpts();
507
508 // We've previously computed a preamble. Check whether we have the same
509 // preamble now that we did before, and that there's enough space in
510 // the main-file buffer within the precompiled preamble to fit the
511 // new main file.
512 if (PreambleBytes.size() != Bounds.Size ||
513 PreambleEndsAtStartOfLine != Bounds.PreambleEndsAtStartOfLine ||
514 !std::equal(PreambleBytes.begin(), PreambleBytes.end(),
515 MainFileBuffer->getBuffer().begin()))
516 return false;
517 // The preamble has not changed. We may be able to re-use the precompiled
518 // preamble.
519
520 // Check that none of the files used by the preamble have changed.
521 // First, make a record of those files that have been overridden via
522 // remapping or unsaved_files.
523 std::map<llvm::sys::fs::UniqueID, PreambleFileHash> OverriddenFiles;
524 llvm::StringSet<> OverriddenAbsPaths; // Either by buffers or files.
525 for (const auto &R : PreprocessorOpts.RemappedFiles) {
526 llvm::vfs::Status Status;
527 if (!moveOnNoError(VFS->status(R.second), Status)) {
528 // If we can't stat the file we're remapping to, assume that something
529 // horrible happened.
530 return false;
531 }
532 // If a mapped file was previously missing, then it has changed.
533 llvm::SmallString<128> MappedPath(R.first);
534 if (!VFS->makeAbsolute(MappedPath))
535 OverriddenAbsPaths.insert(MappedPath);
536
537 OverriddenFiles[Status.getUniqueID()] = PreambleFileHash::createForFile(
538 Status.getSize(), llvm::sys::toTimeT(Status.getLastModificationTime()));
539 }
540
541 // OverridenFileBuffers tracks only the files not found in VFS.
542 llvm::StringMap<PreambleFileHash> OverridenFileBuffers;
543 for (const auto &RB : PreprocessorOpts.RemappedFileBuffers) {
544 const PrecompiledPreamble::PreambleFileHash PreambleHash =
545 PreambleFileHash::createForMemoryBuffer(RB.second);
546 llvm::vfs::Status Status;
547 if (moveOnNoError(VFS->status(RB.first), Status))
548 OverriddenFiles[Status.getUniqueID()] = PreambleHash;
549 else
550 OverridenFileBuffers[RB.first] = PreambleHash;
551
552 llvm::SmallString<128> MappedPath(RB.first);
553 if (!VFS->makeAbsolute(MappedPath))
554 OverriddenAbsPaths.insert(MappedPath);
555 }
556
557 // Check whether anything has changed.
558 for (const auto &F : FilesInPreamble) {
559 auto OverridenFileBuffer = OverridenFileBuffers.find(F.first());
560 if (OverridenFileBuffer != OverridenFileBuffers.end()) {
561 // The file's buffer was remapped and the file was not found in VFS.
562 // Check whether it matches up with the previous mapping.
563 if (OverridenFileBuffer->second != F.second)
564 return false;
565 continue;
566 }
567
568 llvm::vfs::Status Status;
569 if (!moveOnNoError(VFS->status(F.first()), Status)) {
570 // If the file's buffer is not remapped and we can't stat it,
571 // assume that something horrible happened.
572 return false;
573 }
574
575 std::map<llvm::sys::fs::UniqueID, PreambleFileHash>::iterator Overridden =
576 OverriddenFiles.find(Status.getUniqueID());
577 if (Overridden != OverriddenFiles.end()) {
578 // This file was remapped; check whether the newly-mapped file
579 // matches up with the previous mapping.
580 if (Overridden->second != F.second)
581 return false;
582 continue;
583 }
584
585 // Neither the file's buffer nor the file itself was remapped;
586 // check whether it has changed on disk.
587 if (Status.getSize() != uint64_t(F.second.Size) ||
588 llvm::sys::toTimeT(Status.getLastModificationTime()) !=
589 F.second.ModTime)
590 return false;
591 }
592 for (const auto &F : MissingFiles) {
593 // A missing file may be "provided" by an override buffer or file.
594 if (OverriddenAbsPaths.count(F.getKey()))
595 return false;
596 // If a file previously recorded as missing exists as a regular file, then
597 // consider the preamble out-of-date.
598 if (auto Status = VFS->status(F.getKey())) {
599 if (Status->isRegularFile())
600 return false;
601 }
602 }
603 return true;
604 }
605
AddImplicitPreamble(CompilerInvocation & CI,IntrusiveRefCntPtr<llvm::vfs::FileSystem> & VFS,llvm::MemoryBuffer * MainFileBuffer) const606 void PrecompiledPreamble::AddImplicitPreamble(
607 CompilerInvocation &CI, IntrusiveRefCntPtr<llvm::vfs::FileSystem> &VFS,
608 llvm::MemoryBuffer *MainFileBuffer) const {
609 PreambleBounds Bounds(PreambleBytes.size(), PreambleEndsAtStartOfLine);
610 configurePreamble(Bounds, CI, VFS, MainFileBuffer);
611 }
612
OverridePreamble(CompilerInvocation & CI,IntrusiveRefCntPtr<llvm::vfs::FileSystem> & VFS,llvm::MemoryBuffer * MainFileBuffer) const613 void PrecompiledPreamble::OverridePreamble(
614 CompilerInvocation &CI, IntrusiveRefCntPtr<llvm::vfs::FileSystem> &VFS,
615 llvm::MemoryBuffer *MainFileBuffer) const {
616 auto Bounds = ComputePreambleBounds(*CI.getLangOpts(), MainFileBuffer, 0);
617 configurePreamble(Bounds, CI, VFS, MainFileBuffer);
618 }
619
PrecompiledPreamble(PCHStorage Storage,std::vector<char> PreambleBytes,bool PreambleEndsAtStartOfLine,llvm::StringMap<PreambleFileHash> FilesInPreamble,llvm::StringSet<> MissingFiles)620 PrecompiledPreamble::PrecompiledPreamble(
621 PCHStorage Storage, std::vector<char> PreambleBytes,
622 bool PreambleEndsAtStartOfLine,
623 llvm::StringMap<PreambleFileHash> FilesInPreamble,
624 llvm::StringSet<> MissingFiles)
625 : Storage(std::move(Storage)), FilesInPreamble(std::move(FilesInPreamble)),
626 MissingFiles(std::move(MissingFiles)),
627 PreambleBytes(std::move(PreambleBytes)),
628 PreambleEndsAtStartOfLine(PreambleEndsAtStartOfLine) {
629 assert(this->Storage.getKind() != PCHStorage::Kind::Empty);
630 }
631
632 llvm::ErrorOr<PrecompiledPreamble::TempPCHFile>
CreateNewPreamblePCHFile()633 PrecompiledPreamble::TempPCHFile::CreateNewPreamblePCHFile() {
634 // FIXME: This is a hack so that we can override the preamble file during
635 // crash-recovery testing, which is the only case where the preamble files
636 // are not necessarily cleaned up.
637 if (const char *TmpFile = ::getenv("CINDEXTEST_PREAMBLE_FILE"))
638 return TempPCHFile(TmpFile);
639
640 llvm::SmallString<64> File;
641 // Using a version of createTemporaryFile with a file descriptor guarantees
642 // that we would never get a race condition in a multi-threaded setting
643 // (i.e., multiple threads getting the same temporary path).
644 int FD;
645 auto EC = llvm::sys::fs::createTemporaryFile("preamble", "pch", FD, File);
646 if (EC)
647 return EC;
648 // We only needed to make sure the file exists, close the file right away.
649 llvm::sys::Process::SafelyCloseFileDescriptor(FD);
650 return TempPCHFile(std::string(std::move(File).str()));
651 }
652
TempPCHFile(std::string FilePath)653 PrecompiledPreamble::TempPCHFile::TempPCHFile(std::string FilePath)
654 : FilePath(std::move(FilePath)) {
655 TemporaryFiles::getInstance().addFile(*this->FilePath);
656 }
657
TempPCHFile(TempPCHFile && Other)658 PrecompiledPreamble::TempPCHFile::TempPCHFile(TempPCHFile &&Other) {
659 FilePath = std::move(Other.FilePath);
660 Other.FilePath = None;
661 }
662
663 PrecompiledPreamble::TempPCHFile &PrecompiledPreamble::TempPCHFile::
operator =(TempPCHFile && Other)664 operator=(TempPCHFile &&Other) {
665 RemoveFileIfPresent();
666
667 FilePath = std::move(Other.FilePath);
668 Other.FilePath = None;
669 return *this;
670 }
671
~TempPCHFile()672 PrecompiledPreamble::TempPCHFile::~TempPCHFile() { RemoveFileIfPresent(); }
673
RemoveFileIfPresent()674 void PrecompiledPreamble::TempPCHFile::RemoveFileIfPresent() {
675 if (FilePath) {
676 TemporaryFiles::getInstance().removeFile(*FilePath);
677 FilePath = None;
678 }
679 }
680
getFilePath() const681 llvm::StringRef PrecompiledPreamble::TempPCHFile::getFilePath() const {
682 assert(FilePath && "TempPCHFile doesn't have a FilePath. Had it been moved?");
683 return *FilePath;
684 }
685
PCHStorage(TempPCHFile File)686 PrecompiledPreamble::PCHStorage::PCHStorage(TempPCHFile File)
687 : StorageKind(Kind::TempFile) {
688 new (&asFile()) TempPCHFile(std::move(File));
689 }
690
PCHStorage(InMemoryPreamble Memory)691 PrecompiledPreamble::PCHStorage::PCHStorage(InMemoryPreamble Memory)
692 : StorageKind(Kind::InMemory) {
693 new (&asMemory()) InMemoryPreamble(std::move(Memory));
694 }
695
PCHStorage(PCHStorage && Other)696 PrecompiledPreamble::PCHStorage::PCHStorage(PCHStorage &&Other) : PCHStorage() {
697 *this = std::move(Other);
698 }
699
700 PrecompiledPreamble::PCHStorage &PrecompiledPreamble::PCHStorage::
operator =(PCHStorage && Other)701 operator=(PCHStorage &&Other) {
702 destroy();
703
704 StorageKind = Other.StorageKind;
705 switch (StorageKind) {
706 case Kind::Empty:
707 // do nothing;
708 break;
709 case Kind::TempFile:
710 new (&asFile()) TempPCHFile(std::move(Other.asFile()));
711 break;
712 case Kind::InMemory:
713 new (&asMemory()) InMemoryPreamble(std::move(Other.asMemory()));
714 break;
715 }
716
717 Other.setEmpty();
718 return *this;
719 }
720
~PCHStorage()721 PrecompiledPreamble::PCHStorage::~PCHStorage() { destroy(); }
722
723 PrecompiledPreamble::PCHStorage::Kind
getKind() const724 PrecompiledPreamble::PCHStorage::getKind() const {
725 return StorageKind;
726 }
727
asFile()728 PrecompiledPreamble::TempPCHFile &PrecompiledPreamble::PCHStorage::asFile() {
729 assert(getKind() == Kind::TempFile);
730 return *reinterpret_cast<TempPCHFile *>(Storage.buffer);
731 }
732
733 const PrecompiledPreamble::TempPCHFile &
asFile() const734 PrecompiledPreamble::PCHStorage::asFile() const {
735 return const_cast<PCHStorage *>(this)->asFile();
736 }
737
738 PrecompiledPreamble::InMemoryPreamble &
asMemory()739 PrecompiledPreamble::PCHStorage::asMemory() {
740 assert(getKind() == Kind::InMemory);
741 return *reinterpret_cast<InMemoryPreamble *>(Storage.buffer);
742 }
743
744 const PrecompiledPreamble::InMemoryPreamble &
asMemory() const745 PrecompiledPreamble::PCHStorage::asMemory() const {
746 return const_cast<PCHStorage *>(this)->asMemory();
747 }
748
destroy()749 void PrecompiledPreamble::PCHStorage::destroy() {
750 switch (StorageKind) {
751 case Kind::Empty:
752 return;
753 case Kind::TempFile:
754 asFile().~TempPCHFile();
755 return;
756 case Kind::InMemory:
757 asMemory().~InMemoryPreamble();
758 return;
759 }
760 }
761
setEmpty()762 void PrecompiledPreamble::PCHStorage::setEmpty() {
763 destroy();
764 StorageKind = Kind::Empty;
765 }
766
767 PrecompiledPreamble::PreambleFileHash
createForFile(off_t Size,time_t ModTime)768 PrecompiledPreamble::PreambleFileHash::createForFile(off_t Size,
769 time_t ModTime) {
770 PreambleFileHash Result;
771 Result.Size = Size;
772 Result.ModTime = ModTime;
773 Result.MD5 = {};
774 return Result;
775 }
776
777 PrecompiledPreamble::PreambleFileHash
createForMemoryBuffer(const llvm::MemoryBuffer * Buffer)778 PrecompiledPreamble::PreambleFileHash::createForMemoryBuffer(
779 const llvm::MemoryBuffer *Buffer) {
780 PreambleFileHash Result;
781 Result.Size = Buffer->getBufferSize();
782 Result.ModTime = 0;
783
784 llvm::MD5 MD5Ctx;
785 MD5Ctx.update(Buffer->getBuffer().data());
786 MD5Ctx.final(Result.MD5);
787
788 return Result;
789 }
790
configurePreamble(PreambleBounds Bounds,CompilerInvocation & CI,IntrusiveRefCntPtr<llvm::vfs::FileSystem> & VFS,llvm::MemoryBuffer * MainFileBuffer) const791 void PrecompiledPreamble::configurePreamble(
792 PreambleBounds Bounds, CompilerInvocation &CI,
793 IntrusiveRefCntPtr<llvm::vfs::FileSystem> &VFS,
794 llvm::MemoryBuffer *MainFileBuffer) const {
795 assert(VFS);
796
797 auto &PreprocessorOpts = CI.getPreprocessorOpts();
798
799 // Remap main file to point to MainFileBuffer.
800 auto MainFilePath = CI.getFrontendOpts().Inputs[0].getFile();
801 PreprocessorOpts.addRemappedFile(MainFilePath, MainFileBuffer);
802
803 // Configure ImpicitPCHInclude.
804 PreprocessorOpts.PrecompiledPreambleBytes.first = Bounds.Size;
805 PreprocessorOpts.PrecompiledPreambleBytes.second =
806 Bounds.PreambleEndsAtStartOfLine;
807 PreprocessorOpts.DisablePCHValidation = true;
808
809 setupPreambleStorage(Storage, PreprocessorOpts, VFS);
810 }
811
setupPreambleStorage(const PCHStorage & Storage,PreprocessorOptions & PreprocessorOpts,IntrusiveRefCntPtr<llvm::vfs::FileSystem> & VFS)812 void PrecompiledPreamble::setupPreambleStorage(
813 const PCHStorage &Storage, PreprocessorOptions &PreprocessorOpts,
814 IntrusiveRefCntPtr<llvm::vfs::FileSystem> &VFS) {
815 if (Storage.getKind() == PCHStorage::Kind::TempFile) {
816 const TempPCHFile &PCHFile = Storage.asFile();
817 PreprocessorOpts.ImplicitPCHInclude = std::string(PCHFile.getFilePath());
818
819 // Make sure we can access the PCH file even if we're using a VFS
820 IntrusiveRefCntPtr<llvm::vfs::FileSystem> RealFS =
821 llvm::vfs::getRealFileSystem();
822 auto PCHPath = PCHFile.getFilePath();
823 if (VFS == RealFS || VFS->exists(PCHPath))
824 return;
825 auto Buf = RealFS->getBufferForFile(PCHPath);
826 if (!Buf) {
827 // We can't read the file even from RealFS, this is clearly an error,
828 // but we'll just leave the current VFS as is and let clang's code
829 // figure out what to do with missing PCH.
830 return;
831 }
832
833 // We have a slight inconsistency here -- we're using the VFS to
834 // read files, but the PCH was generated in the real file system.
835 VFS = createVFSOverlayForPreamblePCH(PCHPath, std::move(*Buf), VFS);
836 } else {
837 assert(Storage.getKind() == PCHStorage::Kind::InMemory);
838 // For in-memory preamble, we have to provide a VFS overlay that makes it
839 // accessible.
840 StringRef PCHPath = getInMemoryPreamblePath();
841 PreprocessorOpts.ImplicitPCHInclude = std::string(PCHPath);
842
843 auto Buf = llvm::MemoryBuffer::getMemBuffer(Storage.asMemory().Data);
844 VFS = createVFSOverlayForPreamblePCH(PCHPath, std::move(Buf), VFS);
845 }
846 }
847
BeforeExecute(CompilerInstance & CI)848 void PreambleCallbacks::BeforeExecute(CompilerInstance &CI) {}
AfterExecute(CompilerInstance & CI)849 void PreambleCallbacks::AfterExecute(CompilerInstance &CI) {}
AfterPCHEmitted(ASTWriter & Writer)850 void PreambleCallbacks::AfterPCHEmitted(ASTWriter &Writer) {}
HandleTopLevelDecl(DeclGroupRef DG)851 void PreambleCallbacks::HandleTopLevelDecl(DeclGroupRef DG) {}
createPPCallbacks()852 std::unique_ptr<PPCallbacks> PreambleCallbacks::createPPCallbacks() {
853 return nullptr;
854 }
getCommentHandler()855 CommentHandler *PreambleCallbacks::getCommentHandler() { return nullptr; }
856
857 static llvm::ManagedStatic<BuildPreambleErrorCategory> BuildPreambleErrCategory;
858
make_error_code(BuildPreambleError Error)859 std::error_code clang::make_error_code(BuildPreambleError Error) {
860 return std::error_code(static_cast<int>(Error), *BuildPreambleErrCategory);
861 }
862
name() const863 const char *BuildPreambleErrorCategory::name() const noexcept {
864 return "build-preamble.error";
865 }
866
message(int condition) const867 std::string BuildPreambleErrorCategory::message(int condition) const {
868 switch (static_cast<BuildPreambleError>(condition)) {
869 case BuildPreambleError::CouldntCreateTempFile:
870 return "Could not create temporary file for PCH";
871 case BuildPreambleError::CouldntCreateTargetInfo:
872 return "CreateTargetInfo() return null";
873 case BuildPreambleError::BeginSourceFileFailed:
874 return "BeginSourceFile() return an error";
875 case BuildPreambleError::CouldntEmitPCH:
876 return "Could not emit PCH";
877 case BuildPreambleError::BadInputs:
878 return "Command line arguments must contain exactly one source file";
879 }
880 llvm_unreachable("unexpected BuildPreambleError");
881 }
882