Serialization: Change InputFile to use FileEntryRef and add getVirtualFileRef, NFC

Change the `InputFile` class to store `Optional<FileEntryRef>` instead
of `FileEntry*`. This paged in a few API changes:

- Added `FileManager::getVirtualFileRef`, and converted `getVirtualFile`
  to a wrapper of it.
- Updated `SourceManager::bypassFileContentsOverride` to take
  `FileEntryRef` and return `Optional<FileEntryRef>`
  (`ASTReader::getInputFile` is the only caller).

Differential Revision: https://reviews.llvm.org/D90053

clang/include/clang/Basic/FileManager.h

@@ -239,6 +239,9 @@ public:
   /// if there were a file with the given name on disk.
   ///
   /// The file itself is not accessed.
+  FileEntryRef getVirtualFileRef(StringRef Filename, off_t Size,
+                                 time_t ModificationTime);
+
   const FileEntry *getVirtualFile(StringRef Filename, off_t Size,
                                   time_t ModificationTime);
 

clang/include/clang/Basic/SourceManager.h

@@ -35,6 +35,7 @@
 #define LLVM_CLANG_BASIC_SOURCEMANAGER_H
 
 #include "clang/Basic/Diagnostic.h"
+#include "clang/Basic/FileEntry.h"
 #include "clang/Basic/SourceLocation.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/BitVector.h"
@@ -60,8 +61,6 @@ namespace clang {
 class ASTReader;
 class ASTWriter;
 class FileManager;
-class FileEntry;
-class FileEntryRef;
 class LineTableInfo;
 class SourceManager;
 
@@ -982,11 +981,11 @@ public:
   }
 
   /// Bypass the overridden contents of a file.  This creates a new FileEntry
-  /// and initializes the content cache for it.  Returns nullptr if there is no
+  /// and initializes the content cache for it.  Returns None if there is no
   /// such file in the filesystem.
   ///
   /// This should be called before parsing has begun.
-  const FileEntry *bypassFileContentsOverride(const FileEntry &File);
+  Optional<FileEntryRef> bypassFileContentsOverride(FileEntryRef File);
 
   /// Specify that a file is transient.
   void setFileIsTransient(const FileEntry *SourceFile);

clang/include/clang/Serialization/ModuleFile.h

@@ -67,13 +67,13 @@ class InputFile {
     OutOfDate = 2,
     NotFound = 3
   };
-  llvm::PointerIntPair<const FileEntry *, 2, unsigned> Val;
+  llvm::PointerIntPair<const FileEntryRef::MapEntry *, 2, unsigned> Val;
 
 public:
   InputFile() = default;
 
-  InputFile(const FileEntry *File,
-            bool isOverridden = false, bool isOutOfDate = false) {
+  InputFile(FileEntryRef File, bool isOverridden = false,
+            bool isOutOfDate = false) {
     assert(!(isOverridden && isOutOfDate) &&
            "an overridden cannot be out-of-date");
     unsigned intVal = 0;
@@ -81,7 +81,7 @@ public:
       intVal = Overridden;
     else if (isOutOfDate)
       intVal = OutOfDate;
-    Val.setPointerAndInt(File, intVal);
+    Val.setPointerAndInt(&File.getMapEntry(), intVal);
   }
 
   static InputFile getNotFound() {
@@ -90,7 +90,11 @@ public:
     return File;
   }
 
-  const FileEntry *getFile() const { return Val.getPointer(); }
+  OptionalFileEntryRefDegradesToFileEntryPtr getFile() const {
+    if (auto *P = Val.getPointer())
+      return FileEntryRef(*P);
+    return None;
+  }
   bool isOverridden() const { return Val.getInt() == Overridden; }
   bool isOutOfDate() const { return Val.getInt() == OutOfDate; }
   bool isNotFound() const { return Val.getInt() == NotFound; }

clang/lib/Basic/FileManager.cpp

@@ -335,9 +335,13 @@ FileManager::getFileRef(StringRef Filename, bool openFile, bool CacheFailure) {
   return ReturnedRef;
 }
 
-const FileEntry *
-FileManager::getVirtualFile(StringRef Filename, off_t Size,
-                            time_t ModificationTime) {
+const FileEntry *FileManager::getVirtualFile(StringRef Filename, off_t Size,
+                                             time_t ModificationTime) {
+  return &getVirtualFileRef(Filename, Size, ModificationTime).getFileEntry();
+}
+
+FileEntryRef FileManager::getVirtualFileRef(StringRef Filename, off_t Size,
+                                            time_t ModificationTime) {
   ++NumFileLookups;
 
   // See if there is already an entry in the map for an existing file.
@@ -345,12 +349,10 @@ FileManager::getVirtualFile(StringRef Filename, off_t Size,
       {Filename, std::errc::no_such_file_or_directory}).first;
   if (NamedFileEnt.second) {
     FileEntryRef::MapValue Value = *NamedFileEnt.second;
-    FileEntry *FE;
-    if (LLVM_LIKELY(FE = Value.V.dyn_cast<FileEntry *>()))
-      return FE;
-    return &FileEntryRef(*reinterpret_cast<const FileEntryRef::MapEntry *>(
-                             Value.V.get<const void *>()))
-                .getFileEntry();
+    if (LLVM_LIKELY(Value.V.is<FileEntry *>()))
+      return FileEntryRef(NamedFileEnt);
+    return FileEntryRef(*reinterpret_cast<const FileEntryRef::MapEntry *>(
+        Value.V.get<const void *>()));
   }
 
   // We've not seen this before, or the file is cached as non-existent.
@@ -389,7 +391,7 @@ FileManager::getVirtualFile(StringRef Filename, off_t Size,
     // FIXME: Surely this should add a reference by the new name, and return
     // it instead...
     if (UFE->isValid())
-      return UFE;
+      return FileEntryRef(NamedFileEnt);
 
     UFE->UniqueID = Status.getUniqueID();
     UFE->IsNamedPipe = Status.getType() == llvm::sys::fs::file_type::fifo_file;
@@ -407,7 +409,7 @@ FileManager::getVirtualFile(StringRef Filename, off_t Size,
   UFE->UID     = NextFileUID++;
   UFE->IsValid = true;
   UFE->File.reset();
-  return UFE;
+  return FileEntryRef(NamedFileEnt);
 }
 
 llvm::Optional<FileEntryRef> FileManager::getBypassFile(FileEntryRef VF) {

clang/lib/Basic/SourceManager.cpp

@@ -698,19 +698,17 @@ void SourceManager::overrideFileContents(const FileEntry *SourceFile,
   getOverriddenFilesInfo().OverriddenFiles[SourceFile] = NewFile;
 }
 
-const FileEntry *
-SourceManager::bypassFileContentsOverride(const FileEntry &File) {
-  assert(isFileOverridden(&File));
-  llvm::Optional<FileEntryRef> BypassFile =
-      FileMgr.getBypassFile(File.getLastRef());
+Optional<FileEntryRef>
+SourceManager::bypassFileContentsOverride(FileEntryRef File) {
+  assert(isFileOverridden(&File.getFileEntry()));
+  llvm::Optional<FileEntryRef> BypassFile = FileMgr.getBypassFile(File);
 
   // If the file can't be found in the FS, give up.
   if (!BypassFile)
-    return nullptr;
+    return None;
 
-  const FileEntry *FE = &BypassFile->getFileEntry();
-  (void)getOrCreateContentCache(FE);
-  return FE;
+  (void)getOrCreateContentCache(&BypassFile->getFileEntry());
+  return BypassFile;
 }
 
 void SourceManager::setFileIsTransient(const FileEntry *File) {

clang/lib/Serialization/ASTReader.cpp

@@ -2296,27 +2296,25 @@ InputFile ASTReader::getInputFile(ModuleFile &F, unsigned ID, bool Complain) {
   StringRef Filename = FI.Filename;
   uint64_t StoredContentHash = FI.ContentHash;
 
-  const FileEntry *File = nullptr;
-  if (auto FE = FileMgr.getFile(Filename, /*OpenFile=*/false))
-    File = *FE;
+  OptionalFileEntryRefDegradesToFileEntryPtr File =
+      expectedToOptional(FileMgr.getFileRef(Filename, /*OpenFile=*/false));
 
   // If we didn't find the file, resolve it relative to the
   // original directory from which this AST file was created.
-  if (File == nullptr && !F.OriginalDir.empty() && !F.BaseDirectory.empty() &&
+  if (!File && !F.OriginalDir.empty() && !F.BaseDirectory.empty() &&
       F.OriginalDir != F.BaseDirectory) {
     std::string Resolved = resolveFileRelativeToOriginalDir(
         std::string(Filename), F.OriginalDir, F.BaseDirectory);
     if (!Resolved.empty())
-      if (auto FE = FileMgr.getFile(Resolved))
-        File = *FE;
+      File = expectedToOptional(FileMgr.getFileRef(Resolved));
   }
 
   // For an overridden file, create a virtual file with the stored
   // size/timestamp.
-  if ((Overridden || Transient) && File == nullptr)
-    File = FileMgr.getVirtualFile(Filename, StoredSize, StoredTime);
+  if ((Overridden || Transient) && !File)
+    File = FileMgr.getVirtualFileRef(Filename, StoredSize, StoredTime);
 
-  if (File == nullptr) {
+  if (!File) {
     if (Complain) {
       std::string ErrorStr = "could not find file '";
       ErrorStr += Filename;
@@ -2418,7 +2416,7 @@ InputFile ASTReader::getInputFile(ModuleFile &F, unsigned ID, bool Complain) {
   // FIXME: If the file is overridden and we've already opened it,
   // issue an error (or split it into a separate FileEntry).
 
-  InputFile IF = InputFile(File, Overridden || Transient, IsOutOfDate);
+  InputFile IF = InputFile(*File, Overridden || Transient, IsOutOfDate);
 
   // Note that we've loaded this input file.
   F.InputFilesLoaded[ID-1] = IF;
@@ -9274,7 +9272,7 @@ void ASTReader::visitTopLevelModuleMaps(
     InputFileInfo IFI = readInputFileInfo(MF, I + 1);
     if (IFI.TopLevelModuleMap)
       // FIXME: This unnecessarily re-reads the InputFileInfo.
-      if (auto *FE = getInputFile(MF, I + 1).getFile())
+      if (auto FE = getInputFile(MF, I + 1).getFile())
         Visitor(FE);
   }
 }