clang  10.0.0svn
ModuleManager.cpp
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1 //===- ModuleManager.cpp - Module Manager ---------------------------------===//
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 // This file defines the ModuleManager class, which manages a set of loaded
10 // modules for the ASTReader.
11 //
12 //===----------------------------------------------------------------------===//
13 
16 #include "clang/Basic/LLVM.h"
17 #include "clang/Lex/HeaderSearch.h"
18 #include "clang/Lex/ModuleMap.h"
23 #include "llvm/ADT/STLExtras.h"
24 #include "llvm/ADT/SetVector.h"
25 #include "llvm/ADT/SmallPtrSet.h"
26 #include "llvm/ADT/SmallVector.h"
27 #include "llvm/ADT/StringRef.h"
28 #include "llvm/ADT/iterator.h"
29 #include "llvm/Support/Chrono.h"
30 #include "llvm/Support/DOTGraphTraits.h"
31 #include "llvm/Support/ErrorOr.h"
32 #include "llvm/Support/GraphWriter.h"
33 #include "llvm/Support/MemoryBuffer.h"
34 #include "llvm/Support/VirtualFileSystem.h"
35 #include <algorithm>
36 #include <cassert>
37 #include <memory>
38 #include <string>
39 #include <system_error>
40 
41 using namespace clang;
42 using namespace serialization;
43 
45  auto Entry = FileMgr.getFile(Name, /*OpenFile=*/false,
46  /*CacheFailure=*/false);
47  if (Entry)
48  return lookup(*Entry);
49 
50  return nullptr;
51 }
52 
54  if (const Module *Mod = HeaderSearchInfo.getModuleMap().findModule(Name))
55  if (const FileEntry *File = Mod->getASTFile())
56  return lookup(File);
57 
58  return nullptr;
59 }
60 
62  auto Known = Modules.find(File);
63  if (Known == Modules.end())
64  return nullptr;
65 
66  return Known->second;
67 }
68 
69 std::unique_ptr<llvm::MemoryBuffer>
70 ModuleManager::lookupBuffer(StringRef Name) {
71  auto Entry = FileMgr.getFile(Name, /*OpenFile=*/false,
72  /*CacheFailure=*/false);
73  if (!Entry)
74  return nullptr;
75  return std::move(InMemoryBuffers[*Entry]);
76 }
77 
78 static bool checkSignature(ASTFileSignature Signature,
79  ASTFileSignature ExpectedSignature,
80  std::string &ErrorStr) {
81  if (!ExpectedSignature || Signature == ExpectedSignature)
82  return false;
83 
84  ErrorStr =
85  Signature ? "signature mismatch" : "could not read module signature";
86  return true;
87 }
88 
89 static void updateModuleImports(ModuleFile &MF, ModuleFile *ImportedBy,
90  SourceLocation ImportLoc) {
91  if (ImportedBy) {
92  MF.ImportedBy.insert(ImportedBy);
93  ImportedBy->Imports.insert(&MF);
94  } else {
95  if (!MF.DirectlyImported)
96  MF.ImportLoc = ImportLoc;
97 
98  MF.DirectlyImported = true;
99  }
100 }
101 
104  SourceLocation ImportLoc, ModuleFile *ImportedBy,
105  unsigned Generation,
106  off_t ExpectedSize, time_t ExpectedModTime,
107  ASTFileSignature ExpectedSignature,
108  ASTFileSignatureReader ReadSignature,
109  ModuleFile *&Module,
110  std::string &ErrorStr) {
111  Module = nullptr;
112 
113  // Look for the file entry. This only fails if the expected size or
114  // modification time differ.
115  const FileEntry *Entry;
116  if (Type == MK_ExplicitModule || Type == MK_PrebuiltModule) {
117  // If we're not expecting to pull this file out of the module cache, it
118  // might have a different mtime due to being moved across filesystems in
119  // a distributed build. The size must still match, though. (As must the
120  // contents, but we can't check that.)
121  ExpectedModTime = 0;
122  }
123  // Note: ExpectedSize and ExpectedModTime will be 0 for MK_ImplicitModule
124  // when using an ASTFileSignature.
125  if (lookupModuleFile(FileName, ExpectedSize, ExpectedModTime, Entry)) {
126  ErrorStr = "module file out of date";
127  return OutOfDate;
128  }
129 
130  if (!Entry && FileName != "-") {
131  ErrorStr = "module file not found";
132  return Missing;
133  }
134 
135  // Check whether we already loaded this module, before
136  if (ModuleFile *ModuleEntry = Modules.lookup(Entry)) {
137  // Check the stored signature.
138  if (checkSignature(ModuleEntry->Signature, ExpectedSignature, ErrorStr))
139  return OutOfDate;
140 
141  Module = ModuleEntry;
142  updateModuleImports(*ModuleEntry, ImportedBy, ImportLoc);
143  return AlreadyLoaded;
144  }
145 
146  // Allocate a new module.
147  auto NewModule = std::make_unique<ModuleFile>(Type, Generation);
148  NewModule->Index = Chain.size();
149  NewModule->FileName = FileName.str();
150  NewModule->File = Entry;
151  NewModule->ImportLoc = ImportLoc;
152  NewModule->InputFilesValidationTimestamp = 0;
153 
154  if (NewModule->Kind == MK_ImplicitModule) {
155  std::string TimestampFilename = NewModule->getTimestampFilename();
156  llvm::vfs::Status Status;
157  // A cached stat value would be fine as well.
158  if (!FileMgr.getNoncachedStatValue(TimestampFilename, Status))
159  NewModule->InputFilesValidationTimestamp =
160  llvm::sys::toTimeT(Status.getLastModificationTime());
161  }
162 
163  // Load the contents of the module
164  if (std::unique_ptr<llvm::MemoryBuffer> Buffer = lookupBuffer(FileName)) {
165  // The buffer was already provided for us.
166  NewModule->Buffer = &ModuleCache->addBuiltPCM(FileName, std::move(Buffer));
167  // Since the cached buffer is reused, it is safe to close the file
168  // descriptor that was opened while stat()ing the PCM in
169  // lookupModuleFile() above, it won't be needed any longer.
170  Entry->closeFile();
171  } else if (llvm::MemoryBuffer *Buffer =
172  getModuleCache().lookupPCM(FileName)) {
173  NewModule->Buffer = Buffer;
174  // As above, the file descriptor is no longer needed.
175  Entry->closeFile();
176  } else if (getModuleCache().shouldBuildPCM(FileName)) {
177  // Report that the module is out of date, since we tried (and failed) to
178  // import it earlier.
179  Entry->closeFile();
180  return OutOfDate;
181  } else {
182  // Open the AST file.
183  llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> Buf((std::error_code()));
184  if (FileName == "-") {
185  Buf = llvm::MemoryBuffer::getSTDIN();
186  } else {
187  // Get a buffer of the file and close the file descriptor when done.
188  Buf = FileMgr.getBufferForFile(NewModule->File, /*isVolatile=*/false);
189  }
190 
191  if (!Buf) {
192  ErrorStr = Buf.getError().message();
193  return Missing;
194  }
195 
196  NewModule->Buffer = &getModuleCache().addPCM(FileName, std::move(*Buf));
197  }
198 
199  // Initialize the stream.
200  NewModule->Data = PCHContainerRdr.ExtractPCH(*NewModule->Buffer);
201 
202  // Read the signature eagerly now so that we can check it. Avoid calling
203  // ReadSignature unless there's something to check though.
204  if (ExpectedSignature && checkSignature(ReadSignature(NewModule->Data),
205  ExpectedSignature, ErrorStr))
206  return OutOfDate;
207 
208  // We're keeping this module. Store it everywhere.
209  Module = Modules[Entry] = NewModule.get();
210 
211  updateModuleImports(*NewModule, ImportedBy, ImportLoc);
212 
213  if (!NewModule->isModule())
214  PCHChain.push_back(NewModule.get());
215  if (!ImportedBy)
216  Roots.push_back(NewModule.get());
217 
218  Chain.push_back(std::move(NewModule));
219  return NewlyLoaded;
220 }
221 
223  ModuleIterator First,
224  llvm::SmallPtrSetImpl<ModuleFile *> &LoadedSuccessfully,
225  ModuleMap *modMap) {
226  auto Last = end();
227  if (First == Last)
228  return;
229 
230  // Explicitly clear VisitOrder since we might not notice it is stale.
231  VisitOrder.clear();
232 
233  // Collect the set of module file pointers that we'll be removing.
234  llvm::SmallPtrSet<ModuleFile *, 4> victimSet(
235  (llvm::pointer_iterator<ModuleIterator>(First)),
236  (llvm::pointer_iterator<ModuleIterator>(Last)));
237 
238  auto IsVictim = [&](ModuleFile *MF) {
239  return victimSet.count(MF);
240  };
241  // Remove any references to the now-destroyed modules.
242  for (auto I = begin(); I != First; ++I) {
243  I->Imports.remove_if(IsVictim);
244  I->ImportedBy.remove_if(IsVictim);
245  }
246  Roots.erase(std::remove_if(Roots.begin(), Roots.end(), IsVictim),
247  Roots.end());
248 
249  // Remove the modules from the PCH chain.
250  for (auto I = First; I != Last; ++I) {
251  if (!I->isModule()) {
252  PCHChain.erase(llvm::find(PCHChain, &*I), PCHChain.end());
253  break;
254  }
255  }
256 
257  // Delete the modules and erase them from the various structures.
258  for (ModuleIterator victim = First; victim != Last; ++victim) {
259  Modules.erase(victim->File);
260 
261  if (modMap) {
262  StringRef ModuleName = victim->ModuleName;
263  if (Module *mod = modMap->findModule(ModuleName)) {
264  mod->setASTFile(nullptr);
265  }
266  }
267  }
268 
269  // Delete the modules.
270  Chain.erase(Chain.begin() + (First - begin()), Chain.end());
271 }
272 
273 void
275  std::unique_ptr<llvm::MemoryBuffer> Buffer) {
276  const FileEntry *Entry =
277  FileMgr.getVirtualFile(FileName, Buffer->getBufferSize(), 0);
278  InMemoryBuffers[Entry] = std::move(Buffer);
279 }
280 
281 ModuleManager::VisitState *ModuleManager::allocateVisitState() {
282  // Fast path: if we have a cached state, use it.
283  if (FirstVisitState) {
284  VisitState *Result = FirstVisitState;
285  FirstVisitState = FirstVisitState->NextState;
286  Result->NextState = nullptr;
287  return Result;
288  }
289 
290  // Allocate and return a new state.
291  return new VisitState(size());
292 }
293 
294 void ModuleManager::returnVisitState(VisitState *State) {
295  assert(State->NextState == nullptr && "Visited state is in list?");
296  State->NextState = FirstVisitState;
297  FirstVisitState = State;
298 }
299 
301  GlobalIndex = Index;
302  if (!GlobalIndex) {
303  ModulesInCommonWithGlobalIndex.clear();
304  return;
305  }
306 
307  // Notify the global module index about all of the modules we've already
308  // loaded.
309  for (ModuleFile &M : *this)
310  if (!GlobalIndex->loadedModuleFile(&M))
311  ModulesInCommonWithGlobalIndex.push_back(&M);
312 }
313 
315  if (!GlobalIndex || GlobalIndex->loadedModuleFile(MF))
316  return;
317 
318  ModulesInCommonWithGlobalIndex.push_back(MF);
319 }
320 
322  InMemoryModuleCache &ModuleCache,
323  const PCHContainerReader &PCHContainerRdr,
324  const HeaderSearch &HeaderSearchInfo)
325  : FileMgr(FileMgr), ModuleCache(&ModuleCache),
326  PCHContainerRdr(PCHContainerRdr), HeaderSearchInfo(HeaderSearchInfo) {}
327 
328 ModuleManager::~ModuleManager() { delete FirstVisitState; }
329 
330 void ModuleManager::visit(llvm::function_ref<bool(ModuleFile &M)> Visitor,
331  llvm::SmallPtrSetImpl<ModuleFile *> *ModuleFilesHit) {
332  // If the visitation order vector is the wrong size, recompute the order.
333  if (VisitOrder.size() != Chain.size()) {
334  unsigned N = size();
335  VisitOrder.clear();
336  VisitOrder.reserve(N);
337 
338  // Record the number of incoming edges for each module. When we
339  // encounter a module with no incoming edges, push it into the queue
340  // to seed the queue.
342  Queue.reserve(N);
343  llvm::SmallVector<unsigned, 4> UnusedIncomingEdges;
344  UnusedIncomingEdges.resize(size());
345  for (ModuleFile &M : llvm::reverse(*this)) {
346  unsigned Size = M.ImportedBy.size();
347  UnusedIncomingEdges[M.Index] = Size;
348  if (!Size)
349  Queue.push_back(&M);
350  }
351 
352  // Traverse the graph, making sure to visit a module before visiting any
353  // of its dependencies.
354  while (!Queue.empty()) {
355  ModuleFile *CurrentModule = Queue.pop_back_val();
356  VisitOrder.push_back(CurrentModule);
357 
358  // For any module that this module depends on, push it on the
359  // stack (if it hasn't already been marked as visited).
360  for (auto M = CurrentModule->Imports.rbegin(),
361  MEnd = CurrentModule->Imports.rend();
362  M != MEnd; ++M) {
363  // Remove our current module as an impediment to visiting the
364  // module we depend on. If we were the last unvisited module
365  // that depends on this particular module, push it into the
366  // queue to be visited.
367  unsigned &NumUnusedEdges = UnusedIncomingEdges[(*M)->Index];
368  if (NumUnusedEdges && (--NumUnusedEdges == 0))
369  Queue.push_back(*M);
370  }
371  }
372 
373  assert(VisitOrder.size() == N && "Visitation order is wrong?");
374 
375  delete FirstVisitState;
376  FirstVisitState = nullptr;
377  }
378 
379  VisitState *State = allocateVisitState();
380  unsigned VisitNumber = State->NextVisitNumber++;
381 
382  // If the caller has provided us with a hit-set that came from the global
383  // module index, mark every module file in common with the global module
384  // index that is *not* in that set as 'visited'.
385  if (ModuleFilesHit && !ModulesInCommonWithGlobalIndex.empty()) {
386  for (unsigned I = 0, N = ModulesInCommonWithGlobalIndex.size(); I != N; ++I)
387  {
388  ModuleFile *M = ModulesInCommonWithGlobalIndex[I];
389  if (!ModuleFilesHit->count(M))
390  State->VisitNumber[M->Index] = VisitNumber;
391  }
392  }
393 
394  for (unsigned I = 0, N = VisitOrder.size(); I != N; ++I) {
395  ModuleFile *CurrentModule = VisitOrder[I];
396  // Should we skip this module file?
397  if (State->VisitNumber[CurrentModule->Index] == VisitNumber)
398  continue;
399 
400  // Visit the module.
401  assert(State->VisitNumber[CurrentModule->Index] == VisitNumber - 1);
402  State->VisitNumber[CurrentModule->Index] = VisitNumber;
403  if (!Visitor(*CurrentModule))
404  continue;
405 
406  // The visitor has requested that cut off visitation of any
407  // module that the current module depends on. To indicate this
408  // behavior, we mark all of the reachable modules as having been visited.
409  ModuleFile *NextModule = CurrentModule;
410  do {
411  // For any module that this module depends on, push it on the
412  // stack (if it hasn't already been marked as visited).
413  for (llvm::SetVector<ModuleFile *>::iterator
414  M = NextModule->Imports.begin(),
415  MEnd = NextModule->Imports.end();
416  M != MEnd; ++M) {
417  if (State->VisitNumber[(*M)->Index] != VisitNumber) {
418  State->Stack.push_back(*M);
419  State->VisitNumber[(*M)->Index] = VisitNumber;
420  }
421  }
422 
423  if (State->Stack.empty())
424  break;
425 
426  // Pop the next module off the stack.
427  NextModule = State->Stack.pop_back_val();
428  } while (true);
429  }
430 
431  returnVisitState(State);
432 }
433 
434 bool ModuleManager::lookupModuleFile(StringRef FileName,
435  off_t ExpectedSize,
436  time_t ExpectedModTime,
437  const FileEntry *&File) {
438  if (FileName == "-") {
439  File = nullptr;
440  return false;
441  }
442 
443  // Open the file immediately to ensure there is no race between stat'ing and
444  // opening the file.
445  auto FileOrErr = FileMgr.getFile(FileName, /*OpenFile=*/true,
446  /*CacheFailure=*/false);
447  if (!FileOrErr) {
448  File = nullptr;
449  return false;
450  }
451  File = *FileOrErr;
452 
453  if ((ExpectedSize && ExpectedSize != File->getSize()) ||
454  (ExpectedModTime && ExpectedModTime != File->getModificationTime()))
455  // Do not destroy File, as it may be referenced. If we need to rebuild it,
456  // it will be destroyed by removeModules.
457  return true;
458 
459  return false;
460 }
461 
462 #ifndef NDEBUG
463 namespace llvm {
464 
465  template<>
467  using NodeRef = ModuleFile *;
468  using ChildIteratorType = llvm::SetVector<ModuleFile *>::const_iterator;
469  using nodes_iterator = pointer_iterator<ModuleManager::ModuleConstIterator>;
470 
472  return Node->Imports.begin();
473  }
474 
476  return Node->Imports.end();
477  }
478 
479  static nodes_iterator nodes_begin(const ModuleManager &Manager) {
480  return nodes_iterator(Manager.begin());
481  }
482 
483  static nodes_iterator nodes_end(const ModuleManager &Manager) {
484  return nodes_iterator(Manager.end());
485  }
486  };
487 
488  template<>
490  explicit DOTGraphTraits(bool IsSimple = false)
491  : DefaultDOTGraphTraits(IsSimple) {}
492 
493  static bool renderGraphFromBottomUp() { return true; }
494 
495  std::string getNodeLabel(ModuleFile *M, const ModuleManager&) {
496  return M->ModuleName;
497  }
498  };
499 
500 } // namespace llvm
501 
503  llvm::ViewGraph(*this, "Modules");
504 }
505 #endif
Implements support for file system lookup, file system caching, and directory search management...
Definition: FileManager.h:171
llvm::SetVector< ModuleFile * >::const_iterator ChildIteratorType
ModuleFile * lookup(const FileEntry *File) const
Returns the module associated with the given module file.
Defines the clang::FileManager interface and associated types.
time_t getModificationTime() const
Definition: FileManager.h:108
Specialize PointerLikeTypeTraits to allow LazyGenerationalUpdatePtr to be placed into a PointerUnion...
Definition: Dominators.h:30
void closeFile() const
Definition: FileManager.h:119
std::string ModuleName
The name of the module.
Definition: Module.h:125
The module file is out-of-date.
The base class of the type hierarchy.
Definition: Type.h:1436
unsigned Index
The index of this module in the list of modules.
Definition: Module.h:116
ModuleFile * lookupByFileName(StringRef FileName) const
Returns the module associated with the given file name.
DOTGraphTraits(bool isSimple=false)
Manages the set of modules loaded by an AST reader.
Definition: ModuleManager.h:48
ModuleMap & getModuleMap()
Retrieve the module map.
Definition: HeaderSearch.h:660
SourceLocation ImportLoc
The source location where this module was first imported.
Definition: Module.h:204
AddModuleResult
The result of attempting to add a new module.
ModuleIterator begin()
Forward iterator to traverse all loaded modules.
LineState State
void viewGraph()
View the graphviz representation of the module graph.
void visit(llvm::function_ref< bool(ModuleFile &M)> Visitor, llvm::SmallPtrSetImpl< ModuleFile *> *ModuleFilesHit=nullptr)
Visit each of the modules.
The signature of a module, which is a hash of the AST content.
Definition: Module.h:54
void setGlobalIndex(GlobalModuleIndex *Index)
Set the global module index.
Describes a module or submodule.
Definition: Module.h:64
virtual llvm::StringRef ExtractPCH(llvm::MemoryBufferRef Buffer) const =0
Returns the serialized AST inside the PCH container Buffer.
Module * findModule(StringRef Name) const
Retrieve a module with the given name.
Definition: ModuleMap.cpp:770
Forward-declares and imports various common LLVM datatypes that clang wants to use unqualified...
bool lookupModuleFile(StringRef FileName, off_t ExpectedSize, time_t ExpectedModTime, const FileEntry *&File)
Attempt to resolve the given module file name to a file entry.
ModuleIterator end()
Forward iterator end-point to traverse all loaded modules.
This abstract interface provides operations for unwrapping containers for serialized ASTs (precompile...
Encapsulates the information needed to find the file referenced by a #include or #include_next, (sub-)framework lookup, etc.
Definition: HeaderSearch.h:158
ASTFileSignature(*)(StringRef) ASTFileSignatureReader
ModuleKind
Specifies the kind of module that has been loaded.
Definition: Module.h:42
File is from a prebuilt module path.
Definition: Module.h:59
static nodes_iterator nodes_end(const ModuleManager &Manager)
llvm::MemoryBuffer & addPCM(llvm::StringRef Filename, std::unique_ptr< llvm::MemoryBuffer > Buffer)
Store the PCM under the Filename.
InMemoryModuleCache & getModuleCache() const
Information about a module that has been loaded by the ASTReader.
Definition: Module.h:107
AddModuleResult addModule(StringRef FileName, ModuleKind Type, SourceLocation ImportLoc, ModuleFile *ImportedBy, unsigned Generation, off_t ExpectedSize, time_t ExpectedModTime, ASTFileSignature ExpectedSignature, ASTFileSignatureReader ReadSignature, ModuleFile *&Module, std::string &ErrorStr)
Attempts to create a new module and add it to the list of known modules.
In-memory cache for modules.
void addInMemoryBuffer(StringRef FileName, std::unique_ptr< llvm::MemoryBuffer > Buffer)
Add an in-memory buffer the list of known buffers.
static nodes_iterator nodes_begin(const ModuleManager &Manager)
Encodes a location in the source.
File is an implicitly-loaded module.
Definition: Module.h:44
Cached information about one file (either on disk or in the virtual file system). ...
Definition: FileManager.h:78
static ChildIteratorType child_begin(NodeRef Node)
std::error_code getNoncachedStatValue(StringRef Path, llvm::vfs::Status &Result)
Get the &#39;stat&#39; information for the given Path.
const FileEntry * getVirtualFile(StringRef Filename, off_t Size, time_t ModificationTime)
Retrieve a file entry for a "virtual" file that acts as if there were a file with the given name on d...
llvm::SetVector< ModuleFile * > ImportedBy
List of modules which depend on this module.
Definition: Module.h:466
A global index for a set of module files, providing information about the identifiers within those mo...
The module file was just loaded in response to this call.
pointer_iterator< ModuleManager::ModuleConstIterator > nodes_iterator
ast_type_traits::DynTypedNode Node
Dataflow Directional Tag Classes.
ModuleManager(FileManager &FileMgr, InMemoryModuleCache &ModuleCache, const PCHContainerReader &PCHContainerRdr, const HeaderSearch &HeaderSearchInfo)
off_t getSize() const
Definition: FileManager.h:105
File is an explicitly-loaded module.
Definition: Module.h:47
ModuleFile * lookupByModuleName(StringRef ModName) const
Returns the module associated with the given module name.
static void updateModuleImports(ModuleFile &MF, ModuleFile *ImportedBy, SourceLocation ImportLoc)
void removeModules(ModuleIterator First, llvm::SmallPtrSetImpl< ModuleFile *> &LoadedSuccessfully, ModuleMap *modMap)
Remove the modules starting from First (to the end).
void moduleFileAccepted(ModuleFile *MF)
Notification from the AST reader that the given module file has been "accepted", and will not (can no...
llvm::ErrorOr< const FileEntry * > getFile(StringRef Filename, bool OpenFile=false, bool CacheFailure=true)
Lookup, cache, and verify the specified file (real or virtual).
std::string getNodeLabel(ModuleFile *M, const ModuleManager &)
unsigned size() const
Number of modules loaded.
The module file had already been loaded.
static ChildIteratorType child_end(NodeRef Node)
llvm::ErrorOr< std::unique_ptr< llvm::MemoryBuffer > > getBufferForFile(const FileEntry *Entry, bool isVolatile=false)
Open the specified file as a MemoryBuffer, returning a new MemoryBuffer if successful, otherwise returning null.
llvm::pointee_iterator< SmallVectorImpl< std::unique_ptr< ModuleFile > >::iterator > ModuleIterator
bool DirectlyImported
Whether this module has been directly imported by the user.
Definition: Module.h:171
llvm::SetVector< ModuleFile * > Imports
List of modules which this module depends on.
Definition: Module.h:469
std::unique_ptr< llvm::MemoryBuffer > lookupBuffer(StringRef Name)
Returns the in-memory (virtual file) buffer with the given name.
bool loadedModuleFile(ModuleFile *File)
Note that the given module file has been loaded.
static bool checkSignature(ASTFileSignature Signature, ASTFileSignature ExpectedSignature, std::string &ErrorStr)