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diff --git a/contrib/llvm/tools/clang/lib/Basic/FileManager.cpp b/contrib/llvm/tools/clang/lib/Basic/FileManager.cpp
new file mode 100644
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+++ b/contrib/llvm/tools/clang/lib/Basic/FileManager.cpp
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+//===--- FileManager.cpp - File System Probing and Caching ----------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file implements the FileManager interface.
+//
+//===----------------------------------------------------------------------===//
+//
+// TODO: This should index all interesting directories with dirent calls.
+//  getdirentries ?
+//  opendir/readdir_r/closedir ?
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Basic/FileManager.h"
+#include "clang/Basic/FileSystemStatCache.h"
+#include "clang/Frontend/PCHContainerOperations.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Config/llvm-config.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/raw_ostream.h"
+#include <map>
+#include <set>
+#include <string>
+#include <system_error>
+
+using namespace clang;
+
+/// NON_EXISTENT_DIR - A special value distinct from null that is used to
+/// represent a dir name that doesn't exist on the disk.
+#define NON_EXISTENT_DIR reinterpret_cast<DirectoryEntry*>((intptr_t)-1)
+
+/// NON_EXISTENT_FILE - A special value distinct from null that is used to
+/// represent a filename that doesn't exist on the disk.
+#define NON_EXISTENT_FILE reinterpret_cast<FileEntry*>((intptr_t)-1)
+
+//===----------------------------------------------------------------------===//
+// Common logic.
+//===----------------------------------------------------------------------===//
+
+FileManager::FileManager(const FileSystemOptions &FSO,
+                         IntrusiveRefCntPtr<vfs::FileSystem> FS)
+  : FS(FS), FileSystemOpts(FSO),
+    SeenDirEntries(64), SeenFileEntries(64), NextFileUID(0) {
+  NumDirLookups = NumFileLookups = 0;
+  NumDirCacheMisses = NumFileCacheMisses = 0;
+
+  // If the caller doesn't provide a virtual file system, just grab the real
+  // file system.
+  if (!FS)
+    this->FS = vfs::getRealFileSystem();
+}
+
+FileManager::~FileManager() = default;
+
+void FileManager::addStatCache(std::unique_ptr<FileSystemStatCache> statCache,
+                               bool AtBeginning) {
+  assert(statCache && "No stat cache provided?");
+  if (AtBeginning || !StatCache.get()) {
+    statCache->setNextStatCache(std::move(StatCache));
+    StatCache = std::move(statCache);
+    return;
+  }
+  
+  FileSystemStatCache *LastCache = StatCache.get();
+  while (LastCache->getNextStatCache())
+    LastCache = LastCache->getNextStatCache();
+
+  LastCache->setNextStatCache(std::move(statCache));
+}
+
+void FileManager::removeStatCache(FileSystemStatCache *statCache) {
+  if (!statCache)
+    return;
+  
+  if (StatCache.get() == statCache) {
+    // This is the first stat cache.
+    StatCache = StatCache->takeNextStatCache();
+    return;
+  }
+  
+  // Find the stat cache in the list.
+  FileSystemStatCache *PrevCache = StatCache.get();
+  while (PrevCache && PrevCache->getNextStatCache() != statCache)
+    PrevCache = PrevCache->getNextStatCache();
+  
+  assert(PrevCache && "Stat cache not found for removal");
+  PrevCache->setNextStatCache(statCache->takeNextStatCache());
+}
+
+void FileManager::clearStatCaches() {
+  StatCache.reset();
+}
+
+/// \brief Retrieve the directory that the given file name resides in.
+/// Filename can point to either a real file or a virtual file.
+static const DirectoryEntry *getDirectoryFromFile(FileManager &FileMgr,
+                                                  StringRef Filename,
+                                                  bool CacheFailure) {
+  if (Filename.empty())
+    return nullptr;
+
+  if (llvm::sys::path::is_separator(Filename[Filename.size() - 1]))
+    return nullptr; // If Filename is a directory.
+
+  StringRef DirName = llvm::sys::path::parent_path(Filename);
+  // Use the current directory if file has no path component.
+  if (DirName.empty())
+    DirName = ".";
+
+  return FileMgr.getDirectory(DirName, CacheFailure);
+}
+
+/// Add all ancestors of the given path (pointing to either a file or
+/// a directory) as virtual directories.
+void FileManager::addAncestorsAsVirtualDirs(StringRef Path) {
+  StringRef DirName = llvm::sys::path::parent_path(Path);
+  if (DirName.empty())
+    return;
+
+  auto &NamedDirEnt =
+      *SeenDirEntries.insert(std::make_pair(DirName, nullptr)).first;
+
+  // When caching a virtual directory, we always cache its ancestors
+  // at the same time.  Therefore, if DirName is already in the cache,
+  // we don't need to recurse as its ancestors must also already be in
+  // the cache.
+  if (NamedDirEnt.second && NamedDirEnt.second != NON_EXISTENT_DIR)
+    return;
+
+  // Add the virtual directory to the cache.
+  auto UDE = llvm::make_unique<DirectoryEntry>();
+  UDE->Name = NamedDirEnt.first().data();
+  NamedDirEnt.second = UDE.get();
+  VirtualDirectoryEntries.push_back(std::move(UDE));
+
+  // Recursively add the other ancestors.
+  addAncestorsAsVirtualDirs(DirName);
+}
+
+const DirectoryEntry *FileManager::getDirectory(StringRef DirName,
+                                                bool CacheFailure) {
+  // stat doesn't like trailing separators except for root directory.
+  // At least, on Win32 MSVCRT, stat() cannot strip trailing '/'.
+  // (though it can strip '\\')
+  if (DirName.size() > 1 &&
+      DirName != llvm::sys::path::root_path(DirName) &&
+      llvm::sys::path::is_separator(DirName.back()))
+    DirName = DirName.substr(0, DirName.size()-1);
+#ifdef LLVM_ON_WIN32
+  // Fixing a problem with "clang C:test.c" on Windows.
+  // Stat("C:") does not recognize "C:" as a valid directory
+  std::string DirNameStr;
+  if (DirName.size() > 1 && DirName.back() == ':' &&
+      DirName.equals_lower(llvm::sys::path::root_name(DirName))) {
+    DirNameStr = DirName.str() + '.';
+    DirName = DirNameStr;
+  }
+#endif
+
+  ++NumDirLookups;
+  auto &NamedDirEnt =
+      *SeenDirEntries.insert(std::make_pair(DirName, nullptr)).first;
+
+  // See if there was already an entry in the map.  Note that the map
+  // contains both virtual and real directories.
+  if (NamedDirEnt.second)
+    return NamedDirEnt.second == NON_EXISTENT_DIR ? nullptr
+                                                  : NamedDirEnt.second;
+
+  ++NumDirCacheMisses;
+
+  // By default, initialize it to invalid.
+  NamedDirEnt.second = NON_EXISTENT_DIR;
+
+  // Get the null-terminated directory name as stored as the key of the
+  // SeenDirEntries map.
+  const char *InterndDirName = NamedDirEnt.first().data();
+
+  // Check to see if the directory exists.
+  FileData Data;
+  if (getStatValue(InterndDirName, Data, false, nullptr /*directory lookup*/)) {
+    // There's no real directory at the given path.
+    if (!CacheFailure)
+      SeenDirEntries.erase(DirName);
+    return nullptr;
+  }
+
+  // It exists.  See if we have already opened a directory with the
+  // same inode (this occurs on Unix-like systems when one dir is
+  // symlinked to another, for example) or the same path (on
+  // Windows).
+  DirectoryEntry &UDE = UniqueRealDirs[Data.UniqueID];
+
+  NamedDirEnt.second = &UDE;
+  if (!UDE.getName()) {
+    // We don't have this directory yet, add it.  We use the string
+    // key from the SeenDirEntries map as the string.
+    UDE.Name  = InterndDirName;
+  }
+
+  return &UDE;
+}
+
+const FileEntry *FileManager::getFile(StringRef Filename, bool openFile,
+                                      bool CacheFailure) {
+  ++NumFileLookups;
+
+  // See if there is already an entry in the map.
+  auto &NamedFileEnt =
+      *SeenFileEntries.insert(std::make_pair(Filename, nullptr)).first;
+
+  // See if there is already an entry in the map.
+  if (NamedFileEnt.second)
+    return NamedFileEnt.second == NON_EXISTENT_FILE ? nullptr
+                                                    : NamedFileEnt.second;
+
+  ++NumFileCacheMisses;
+
+  // By default, initialize it to invalid.
+  NamedFileEnt.second = NON_EXISTENT_FILE;
+
+  // Get the null-terminated file name as stored as the key of the
+  // SeenFileEntries map.
+  const char *InterndFileName = NamedFileEnt.first().data();
+
+  // Look up the directory for the file.  When looking up something like
+  // sys/foo.h we'll discover all of the search directories that have a 'sys'
+  // subdirectory.  This will let us avoid having to waste time on known-to-fail
+  // searches when we go to find sys/bar.h, because all the search directories
+  // without a 'sys' subdir will get a cached failure result.
+  const DirectoryEntry *DirInfo = getDirectoryFromFile(*this, Filename,
+                                                       CacheFailure);
+  if (DirInfo == nullptr) { // Directory doesn't exist, file can't exist.
+    if (!CacheFailure)
+      SeenFileEntries.erase(Filename);
+
+    return nullptr;
+  }
+  
+  // FIXME: Use the directory info to prune this, before doing the stat syscall.
+  // FIXME: This will reduce the # syscalls.
+
+  // Nope, there isn't.  Check to see if the file exists.
+  std::unique_ptr<vfs::File> F;
+  FileData Data;
+  if (getStatValue(InterndFileName, Data, true, openFile ? &F : nullptr)) {
+    // There's no real file at the given path.
+    if (!CacheFailure)
+      SeenFileEntries.erase(Filename);
+
+    return nullptr;
+  }
+
+  assert((openFile || !F) && "undesired open file");
+
+  // It exists.  See if we have already opened a file with the same inode.
+  // This occurs when one dir is symlinked to another, for example.
+  FileEntry &UFE = UniqueRealFiles[Data.UniqueID];
+
+  NamedFileEnt.second = &UFE;
+
+  // If the name returned by getStatValue is different than Filename, re-intern
+  // the name.
+  if (Data.Name != Filename) {
+    auto &NamedFileEnt =
+        *SeenFileEntries.insert(std::make_pair(Data.Name, nullptr)).first;
+    if (!NamedFileEnt.second)
+      NamedFileEnt.second = &UFE;
+    else
+      assert(NamedFileEnt.second == &UFE &&
+             "filename from getStatValue() refers to wrong file");
+    InterndFileName = NamedFileEnt.first().data();
+  }
+
+  if (UFE.isValid()) { // Already have an entry with this inode, return it.
+
+    // FIXME: this hack ensures that if we look up a file by a virtual path in
+    // the VFS that the getDir() will have the virtual path, even if we found
+    // the file by a 'real' path first. This is required in order to find a
+    // module's structure when its headers/module map are mapped in the VFS.
+    // We should remove this as soon as we can properly support a file having
+    // multiple names.
+    if (DirInfo != UFE.Dir && Data.IsVFSMapped)
+      UFE.Dir = DirInfo;
+
+    // Always update the name to use the last name by which a file was accessed.
+    // FIXME: Neither this nor always using the first name is correct; we want
+    // to switch towards a design where we return a FileName object that
+    // encapsulates both the name by which the file was accessed and the
+    // corresponding FileEntry.
+    UFE.Name = InterndFileName;
+
+    return &UFE;
+  }
+
+  // Otherwise, we don't have this file yet, add it.
+  UFE.Name    = InterndFileName;
+  UFE.Size = Data.Size;
+  UFE.ModTime = Data.ModTime;
+  UFE.Dir     = DirInfo;
+  UFE.UID     = NextFileUID++;
+  UFE.UniqueID = Data.UniqueID;
+  UFE.IsNamedPipe = Data.IsNamedPipe;
+  UFE.InPCH = Data.InPCH;
+  UFE.File = std::move(F);
+  UFE.IsValid = true;
+  return &UFE;
+}
+
+const FileEntry *
+FileManager::getVirtualFile(StringRef Filename, off_t Size,
+                            time_t ModificationTime) {
+  ++NumFileLookups;
+
+  // See if there is already an entry in the map.
+  auto &NamedFileEnt =
+      *SeenFileEntries.insert(std::make_pair(Filename, nullptr)).first;
+
+  // See if there is already an entry in the map.
+  if (NamedFileEnt.second && NamedFileEnt.second != NON_EXISTENT_FILE)
+    return NamedFileEnt.second;
+
+  ++NumFileCacheMisses;
+
+  // By default, initialize it to invalid.
+  NamedFileEnt.second = NON_EXISTENT_FILE;
+
+  addAncestorsAsVirtualDirs(Filename);
+  FileEntry *UFE = nullptr;
+
+  // Now that all ancestors of Filename are in the cache, the
+  // following call is guaranteed to find the DirectoryEntry from the
+  // cache.
+  const DirectoryEntry *DirInfo = getDirectoryFromFile(*this, Filename,
+                                                       /*CacheFailure=*/true);
+  assert(DirInfo &&
+         "The directory of a virtual file should already be in the cache.");
+
+  // Check to see if the file exists. If so, drop the virtual file
+  FileData Data;
+  const char *InterndFileName = NamedFileEnt.first().data();
+  if (getStatValue(InterndFileName, Data, true, nullptr) == 0) {
+    Data.Size = Size;
+    Data.ModTime = ModificationTime;
+    UFE = &UniqueRealFiles[Data.UniqueID];
+
+    NamedFileEnt.second = UFE;
+
+    // If we had already opened this file, close it now so we don't
+    // leak the descriptor. We're not going to use the file
+    // descriptor anyway, since this is a virtual file.
+    if (UFE->File)
+      UFE->closeFile();
+
+    // If we already have an entry with this inode, return it.
+    if (UFE->isValid())
+      return UFE;
+
+    UFE->UniqueID = Data.UniqueID;
+    UFE->IsNamedPipe = Data.IsNamedPipe;
+    UFE->InPCH = Data.InPCH;
+  }
+
+  if (!UFE) {
+    VirtualFileEntries.push_back(llvm::make_unique<FileEntry>());
+    UFE = VirtualFileEntries.back().get();
+    NamedFileEnt.second = UFE;
+  }
+
+  UFE->Name    = InterndFileName;
+  UFE->Size    = Size;
+  UFE->ModTime = ModificationTime;
+  UFE->Dir     = DirInfo;
+  UFE->UID     = NextFileUID++;
+  UFE->File.reset();
+  return UFE;
+}
+
+bool FileManager::FixupRelativePath(SmallVectorImpl<char> &path) const {
+  StringRef pathRef(path.data(), path.size());
+
+  if (FileSystemOpts.WorkingDir.empty() 
+      || llvm::sys::path::is_absolute(pathRef))
+    return false;
+
+  SmallString<128> NewPath(FileSystemOpts.WorkingDir);
+  llvm::sys::path::append(NewPath, pathRef);
+  path = NewPath;
+  return true;
+}
+
+bool FileManager::makeAbsolutePath(SmallVectorImpl<char> &Path) const {
+  bool Changed = FixupRelativePath(Path);
+
+  if (!llvm::sys::path::is_absolute(StringRef(Path.data(), Path.size()))) {
+    llvm::sys::fs::make_absolute(Path);
+    Changed = true;
+  }
+
+  return Changed;
+}
+
+llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
+FileManager::getBufferForFile(const FileEntry *Entry, bool isVolatile,
+                              bool ShouldCloseOpenFile) {
+  uint64_t FileSize = Entry->getSize();
+  // If there's a high enough chance that the file have changed since we
+  // got its size, force a stat before opening it.
+  if (isVolatile)
+    FileSize = -1;
+
+  const char *Filename = Entry->getName();
+  // If the file is already open, use the open file descriptor.
+  if (Entry->File) {
+    auto Result =
+        Entry->File->getBuffer(Filename, FileSize,
+                               /*RequiresNullTerminator=*/true, isVolatile);
+    // FIXME: we need a set of APIs that can make guarantees about whether a
+    // FileEntry is open or not.
+    if (ShouldCloseOpenFile)
+      Entry->closeFile();
+    return Result;
+  }
+
+  // Otherwise, open the file.
+
+  if (FileSystemOpts.WorkingDir.empty())
+    return FS->getBufferForFile(Filename, FileSize,
+                                /*RequiresNullTerminator=*/true, isVolatile);
+
+  SmallString<128> FilePath(Entry->getName());
+  FixupRelativePath(FilePath);
+  return FS->getBufferForFile(FilePath, FileSize,
+                              /*RequiresNullTerminator=*/true, isVolatile);
+}
+
+llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
+FileManager::getBufferForFile(StringRef Filename) {
+  if (FileSystemOpts.WorkingDir.empty())
+    return FS->getBufferForFile(Filename);
+
+  SmallString<128> FilePath(Filename);
+  FixupRelativePath(FilePath);
+  return FS->getBufferForFile(FilePath.c_str());
+}
+
+/// getStatValue - Get the 'stat' information for the specified path,
+/// using the cache to accelerate it if possible.  This returns true
+/// if the path points to a virtual file or does not exist, or returns
+/// false if it's an existent real file.  If FileDescriptor is NULL,
+/// do directory look-up instead of file look-up.
+bool FileManager::getStatValue(const char *Path, FileData &Data, bool isFile,
+                               std::unique_ptr<vfs::File> *F) {
+  // FIXME: FileSystemOpts shouldn't be passed in here, all paths should be
+  // absolute!
+  if (FileSystemOpts.WorkingDir.empty())
+    return FileSystemStatCache::get(Path, Data, isFile, F,StatCache.get(), *FS);
+
+  SmallString<128> FilePath(Path);
+  FixupRelativePath(FilePath);
+
+  return FileSystemStatCache::get(FilePath.c_str(), Data, isFile, F,
+                                  StatCache.get(), *FS);
+}
+
+bool FileManager::getNoncachedStatValue(StringRef Path,
+                                        vfs::Status &Result) {
+  SmallString<128> FilePath(Path);
+  FixupRelativePath(FilePath);
+
+  llvm::ErrorOr<vfs::Status> S = FS->status(FilePath.c_str());
+  if (!S)
+    return true;
+  Result = *S;
+  return false;
+}
+
+void FileManager::invalidateCache(const FileEntry *Entry) {
+  assert(Entry && "Cannot invalidate a NULL FileEntry");
+
+  SeenFileEntries.erase(Entry->getName());
+
+  // FileEntry invalidation should not block future optimizations in the file
+  // caches. Possible alternatives are cache truncation (invalidate last N) or
+  // invalidation of the whole cache.
+  UniqueRealFiles.erase(Entry->getUniqueID());
+}
+
+
+void FileManager::GetUniqueIDMapping(
+                   SmallVectorImpl<const FileEntry *> &UIDToFiles) const {
+  UIDToFiles.clear();
+  UIDToFiles.resize(NextFileUID);
+  
+  // Map file entries
+  for (llvm::StringMap<FileEntry*, llvm::BumpPtrAllocator>::const_iterator
+         FE = SeenFileEntries.begin(), FEEnd = SeenFileEntries.end();
+       FE != FEEnd; ++FE)
+    if (FE->getValue() && FE->getValue() != NON_EXISTENT_FILE)
+      UIDToFiles[FE->getValue()->getUID()] = FE->getValue();
+  
+  // Map virtual file entries
+  for (const auto &VFE : VirtualFileEntries)
+    if (VFE && VFE.get() != NON_EXISTENT_FILE)
+      UIDToFiles[VFE->getUID()] = VFE.get();
+}
+
+void FileManager::modifyFileEntry(FileEntry *File,
+                                  off_t Size, time_t ModificationTime) {
+  File->Size = Size;
+  File->ModTime = ModificationTime;
+}
+
+StringRef FileManager::getCanonicalName(const DirectoryEntry *Dir) {
+  // FIXME: use llvm::sys::fs::canonical() when it gets implemented
+  llvm::DenseMap<const DirectoryEntry *, llvm::StringRef>::iterator Known
+    = CanonicalDirNames.find(Dir);
+  if (Known != CanonicalDirNames.end())
+    return Known->second;
+
+  StringRef CanonicalName(Dir->getName());
+
+#ifdef LLVM_ON_UNIX
+  char CanonicalNameBuf[PATH_MAX];
+  if (realpath(Dir->getName(), CanonicalNameBuf))
+    CanonicalName = StringRef(CanonicalNameBuf).copy(CanonicalNameStorage);
+#else
+  SmallString<256> CanonicalNameBuf(CanonicalName);
+  llvm::sys::fs::make_absolute(CanonicalNameBuf);
+  llvm::sys::path::native(CanonicalNameBuf);
+  // We've run into needing to remove '..' here in the wild though, so
+  // remove it.
+  // On Windows, symlinks are significantly less prevalent, so removing
+  // '..' is pretty safe.
+  // Ideally we'd have an equivalent of `realpath` and could implement
+  // sys::fs::canonical across all the platforms.
+  llvm::sys::path::remove_dots(CanonicalNameBuf, /* remove_dot_dot */ true);
+  CanonicalName = StringRef(CanonicalNameBuf).copy(CanonicalNameStorage);
+#endif
+
+  CanonicalDirNames.insert(std::make_pair(Dir, CanonicalName));
+  return CanonicalName;
+}
+
+void FileManager::PrintStats() const {
+  llvm::errs() << "\n*** File Manager Stats:\n";
+  llvm::errs() << UniqueRealFiles.size() << " real files found, "
+               << UniqueRealDirs.size() << " real dirs found.\n";
+  llvm::errs() << VirtualFileEntries.size() << " virtual files found, "
+               << VirtualDirectoryEntries.size() << " virtual dirs found.\n";
+  llvm::errs() << NumDirLookups << " dir lookups, "
+               << NumDirCacheMisses << " dir cache misses.\n";
+  llvm::errs() << NumFileLookups << " file lookups, "
+               << NumFileCacheMisses << " file cache misses.\n";
+
+  //llvm::errs() << PagesMapped << BytesOfPagesMapped << FSLookups;
+}
+
+// Virtual destructors for abstract base classes that need live in Basic.
+PCHContainerWriter::~PCHContainerWriter() {}
+PCHContainerReader::~PCHContainerReader() {}