YQ Connector: support managed ClickHouse

Со стороны dqrun можно обратиться к инстансу коннектора, который работает на streaming стенде, и извлечь данные из облачного CH.

1 files changed, 2267 insertions, 0 deletions

diff --git a/contrib/libs/clang14/lib/Basic/SourceManager.cpp b/contrib/libs/clang14/lib/Basic/SourceManager.cpp
new file mode 100644
index 00000000000..ec3e35595bb
--- /dev/null
+++ b/contrib/libs/clang14/lib/Basic/SourceManager.cpp
@@ -0,0 +1,2267 @@
+//===- SourceManager.cpp - Track and cache source files -------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file implements the SourceManager interface.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Basic/SourceManager.h"
+#include "clang/Basic/Diagnostic.h"
+#include "clang/Basic/FileManager.h"
+#include "clang/Basic/LLVM.h"
+#include "clang/Basic/SourceLocation.h"
+#include "clang/Basic/SourceManagerInternals.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/None.h"
+#include "llvm/ADT/Optional.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/StringSwitch.h"
+#include "llvm/Support/Allocator.h"
+#include "llvm/Support/Capacity.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/raw_ostream.h"
+#include <algorithm>
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <memory>
+#include <tuple>
+#include <utility>
+#include <vector>
+
+using namespace clang;
+using namespace SrcMgr;
+using llvm::MemoryBuffer;
+
+//===----------------------------------------------------------------------===//
+// SourceManager Helper Classes
+//===----------------------------------------------------------------------===//
+
+/// getSizeBytesMapped - Returns the number of bytes actually mapped for this
+/// ContentCache. This can be 0 if the MemBuffer was not actually expanded.
+unsigned ContentCache::getSizeBytesMapped() const {
+  return Buffer ? Buffer->getBufferSize() : 0;
+}
+
+/// Returns the kind of memory used to back the memory buffer for
+/// this content cache.  This is used for performance analysis.
+llvm::MemoryBuffer::BufferKind ContentCache::getMemoryBufferKind() const {
+  if (Buffer == nullptr) {
+    assert(0 && "Buffer should never be null");
+    return llvm::MemoryBuffer::MemoryBuffer_Malloc;
+  }
+  return Buffer->getBufferKind();
+}
+
+/// getSize - Returns the size of the content encapsulated by this ContentCache.
+///  This can be the size of the source file or the size of an arbitrary
+///  scratch buffer.  If the ContentCache encapsulates a source file, that
+///  file is not lazily brought in from disk to satisfy this query.
+unsigned ContentCache::getSize() const {
+  return Buffer ? (unsigned)Buffer->getBufferSize()
+                : (unsigned)ContentsEntry->getSize();
+}
+
+const char *ContentCache::getInvalidBOM(StringRef BufStr) {
+  // If the buffer is valid, check to see if it has a UTF Byte Order Mark
+  // (BOM).  We only support UTF-8 with and without a BOM right now.  See
+  // http://en.wikipedia.org/wiki/Byte_order_mark for more information.
+  const char *InvalidBOM =
+      llvm::StringSwitch<const char *>(BufStr)
+          .StartsWith(llvm::StringLiteral::withInnerNUL("\x00\x00\xFE\xFF"),
+                      "UTF-32 (BE)")
+          .StartsWith(llvm::StringLiteral::withInnerNUL("\xFF\xFE\x00\x00"),
+                      "UTF-32 (LE)")
+          .StartsWith("\xFE\xFF", "UTF-16 (BE)")
+          .StartsWith("\xFF\xFE", "UTF-16 (LE)")
+          .StartsWith("\x2B\x2F\x76", "UTF-7")
+          .StartsWith("\xF7\x64\x4C", "UTF-1")
+          .StartsWith("\xDD\x73\x66\x73", "UTF-EBCDIC")
+          .StartsWith("\x0E\xFE\xFF", "SCSU")
+          .StartsWith("\xFB\xEE\x28", "BOCU-1")
+          .StartsWith("\x84\x31\x95\x33", "GB-18030")
+          .Default(nullptr);
+
+  return InvalidBOM;
+}
+
+llvm::Optional<llvm::MemoryBufferRef>
+ContentCache::getBufferOrNone(DiagnosticsEngine &Diag, FileManager &FM,
+                              SourceLocation Loc) const {
+  // Lazily create the Buffer for ContentCaches that wrap files.  If we already
+  // computed it, just return what we have.
+  if (IsBufferInvalid)
+    return None;
+  if (Buffer)
+    return Buffer->getMemBufferRef();
+  if (!ContentsEntry)
+    return None;
+
+  // Start with the assumption that the buffer is invalid to simplify early
+  // return paths.
+  IsBufferInvalid = true;
+
+  auto BufferOrError = FM.getBufferForFile(ContentsEntry, IsFileVolatile);
+
+  // If we were unable to open the file, then we are in an inconsistent
+  // situation where the content cache referenced a file which no longer
+  // exists. Most likely, we were using a stat cache with an invalid entry but
+  // the file could also have been removed during processing. Since we can't
+  // really deal with this situation, just create an empty buffer.
+  if (!BufferOrError) {
+    if (Diag.isDiagnosticInFlight())
+      Diag.SetDelayedDiagnostic(diag::err_cannot_open_file,
+                                ContentsEntry->getName(),
+                                BufferOrError.getError().message());
+    else
+      Diag.Report(Loc, diag::err_cannot_open_file)
+          << ContentsEntry->getName() << BufferOrError.getError().message();
+
+    return None;
+  }
+
+  Buffer = std::move(*BufferOrError);
+
+  // Check that the file's size fits in an 'unsigned' (with room for a
+  // past-the-end value). This is deeply regrettable, but various parts of
+  // Clang (including elsewhere in this file!) use 'unsigned' to represent file
+  // offsets, line numbers, string literal lengths, and so on, and fail
+  // miserably on large source files.
+  //
+  // Note: ContentsEntry could be a named pipe, in which case
+  // ContentsEntry::getSize() could have the wrong size. Use
+  // MemoryBuffer::getBufferSize() instead.
+  if (Buffer->getBufferSize() >= std::numeric_limits<unsigned>::max()) {
+    if (Diag.isDiagnosticInFlight())
+      Diag.SetDelayedDiagnostic(diag::err_file_too_large,
+                                ContentsEntry->getName());
+    else
+      Diag.Report(Loc, diag::err_file_too_large)
+        << ContentsEntry->getName();
+
+    return None;
+  }
+
+  // Unless this is a named pipe (in which case we can handle a mismatch),
+  // check that the file's size is the same as in the file entry (which may
+  // have come from a stat cache).
+  if (!ContentsEntry->isNamedPipe() &&
+      Buffer->getBufferSize() != (size_t)ContentsEntry->getSize()) {
+    if (Diag.isDiagnosticInFlight())
+      Diag.SetDelayedDiagnostic(diag::err_file_modified,
+                                ContentsEntry->getName());
+    else
+      Diag.Report(Loc, diag::err_file_modified)
+        << ContentsEntry->getName();
+
+    return None;
+  }
+
+  // If the buffer is valid, check to see if it has a UTF Byte Order Mark
+  // (BOM).  We only support UTF-8 with and without a BOM right now.  See
+  // http://en.wikipedia.org/wiki/Byte_order_mark for more information.
+  StringRef BufStr = Buffer->getBuffer();
+  const char *InvalidBOM = getInvalidBOM(BufStr);
+
+  if (InvalidBOM) {
+    Diag.Report(Loc, diag::err_unsupported_bom)
+      << InvalidBOM << ContentsEntry->getName();
+    return None;
+  }
+
+  // Buffer has been validated.
+  IsBufferInvalid = false;
+  return Buffer->getMemBufferRef();
+}
+
+unsigned LineTableInfo::getLineTableFilenameID(StringRef Name) {
+  auto IterBool = FilenameIDs.try_emplace(Name, FilenamesByID.size());
+  if (IterBool.second)
+    FilenamesByID.push_back(&*IterBool.first);
+  return IterBool.first->second;
+}
+
+/// Add a line note to the line table that indicates that there is a \#line or
+/// GNU line marker at the specified FID/Offset location which changes the
+/// presumed location to LineNo/FilenameID. If EntryExit is 0, then this doesn't
+/// change the presumed \#include stack.  If it is 1, this is a file entry, if
+/// it is 2 then this is a file exit. FileKind specifies whether this is a
+/// system header or extern C system header.
+void LineTableInfo::AddLineNote(FileID FID, unsigned Offset, unsigned LineNo,
+                                int FilenameID, unsigned EntryExit,
+                                SrcMgr::CharacteristicKind FileKind) {
+  std::vector<LineEntry> &Entries = LineEntries[FID];
+
+  assert((Entries.empty() || Entries.back().FileOffset < Offset) &&
+         "Adding line entries out of order!");
+
+  unsigned IncludeOffset = 0;
+  if (EntryExit == 1) {
+    // Push #include
+    IncludeOffset = Offset-1;
+  } else {
+    const auto *PrevEntry = Entries.empty() ? nullptr : &Entries.back();
+    if (EntryExit == 2) {
+      // Pop #include
+      assert(PrevEntry && PrevEntry->IncludeOffset &&
+             "PPDirectives should have caught case when popping empty include "
+             "stack");
+      PrevEntry = FindNearestLineEntry(FID, PrevEntry->IncludeOffset);
+    }
+    if (PrevEntry) {
+      IncludeOffset = PrevEntry->IncludeOffset;
+      if (FilenameID == -1) {
+        // An unspecified FilenameID means use the previous (or containing)
+        // filename if available, or the main source file otherwise.
+        FilenameID = PrevEntry->FilenameID;
+      }
+    }
+  }
+
+  Entries.push_back(LineEntry::get(Offset, LineNo, FilenameID, FileKind,
+                                   IncludeOffset));
+}
+
+/// FindNearestLineEntry - Find the line entry nearest to FID that is before
+/// it.  If there is no line entry before Offset in FID, return null.
+const LineEntry *LineTableInfo::FindNearestLineEntry(FileID FID,
+                                                     unsigned Offset) {
+  const std::vector<LineEntry> &Entries = LineEntries[FID];
+  assert(!Entries.empty() && "No #line entries for this FID after all!");
+
+  // It is very common for the query to be after the last #line, check this
+  // first.
+  if (Entries.back().FileOffset <= Offset)
+    return &Entries.back();
+
+  // Do a binary search to find the maximal element that is still before Offset.
+  std::vector<LineEntry>::const_iterator I = llvm::upper_bound(Entries, Offset);
+  if (I == Entries.begin())
+    return nullptr;
+  return &*--I;
+}
+
+/// Add a new line entry that has already been encoded into
+/// the internal representation of the line table.
+void LineTableInfo::AddEntry(FileID FID,
+                             const std::vector<LineEntry> &Entries) {
+  LineEntries[FID] = Entries;
+}
+
+/// getLineTableFilenameID - Return the uniqued ID for the specified filename.
+unsigned SourceManager::getLineTableFilenameID(StringRef Name) {
+  return getLineTable().getLineTableFilenameID(Name);
+}
+
+/// AddLineNote - Add a line note to the line table for the FileID and offset
+/// specified by Loc.  If FilenameID is -1, it is considered to be
+/// unspecified.
+void SourceManager::AddLineNote(SourceLocation Loc, unsigned LineNo,
+                                int FilenameID, bool IsFileEntry,
+                                bool IsFileExit,
+                                SrcMgr::CharacteristicKind FileKind) {
+  std::pair<FileID, unsigned> LocInfo = getDecomposedExpansionLoc(Loc);
+
+  bool Invalid = false;
+  const SLocEntry &Entry = getSLocEntry(LocInfo.first, &Invalid);
+  if (!Entry.isFile() || Invalid)
+    return;
+
+  const SrcMgr::FileInfo &FileInfo = Entry.getFile();
+
+  // Remember that this file has #line directives now if it doesn't already.
+  const_cast<SrcMgr::FileInfo&>(FileInfo).setHasLineDirectives();
+
+  (void) getLineTable();
+
+  unsigned EntryExit = 0;
+  if (IsFileEntry)
+    EntryExit = 1;
+  else if (IsFileExit)
+    EntryExit = 2;
+
+  LineTable->AddLineNote(LocInfo.first, LocInfo.second, LineNo, FilenameID,
+                         EntryExit, FileKind);
+}
+
+LineTableInfo &SourceManager::getLineTable() {
+  if (!LineTable)
+    LineTable.reset(new LineTableInfo());
+  return *LineTable;
+}
+
+//===----------------------------------------------------------------------===//
+// Private 'Create' methods.
+//===----------------------------------------------------------------------===//
+
+SourceManager::SourceManager(DiagnosticsEngine &Diag, FileManager &FileMgr,
+                             bool UserFilesAreVolatile)
+  : Diag(Diag), FileMgr(FileMgr), UserFilesAreVolatile(UserFilesAreVolatile) {
+  clearIDTables();
+  Diag.setSourceManager(this);
+}
+
+SourceManager::~SourceManager() {
+  // Delete FileEntry objects corresponding to content caches.  Since the actual
+  // content cache objects are bump pointer allocated, we just have to run the
+  // dtors, but we call the deallocate method for completeness.
+  for (unsigned i = 0, e = MemBufferInfos.size(); i != e; ++i) {
+    if (MemBufferInfos[i]) {
+      MemBufferInfos[i]->~ContentCache();
+      ContentCacheAlloc.Deallocate(MemBufferInfos[i]);
+    }
+  }
+  for (llvm::DenseMap<const FileEntry*, SrcMgr::ContentCache*>::iterator
+       I = FileInfos.begin(), E = FileInfos.end(); I != E; ++I) {
+    if (I->second) {
+      I->second->~ContentCache();
+      ContentCacheAlloc.Deallocate(I->second);
+    }
+  }
+}
+
+void SourceManager::clearIDTables() {
+  MainFileID = FileID();
+  LocalSLocEntryTable.clear();
+  LoadedSLocEntryTable.clear();
+  SLocEntryLoaded.clear();
+  LastLineNoFileIDQuery = FileID();
+  LastLineNoContentCache = nullptr;
+  LastFileIDLookup = FileID();
+
+  if (LineTable)
+    LineTable->clear();
+
+  // Use up FileID #0 as an invalid expansion.
+  NextLocalOffset = 0;
+  CurrentLoadedOffset = MaxLoadedOffset;
+  createExpansionLoc(SourceLocation(), SourceLocation(), SourceLocation(), 1);
+}
+
+bool SourceManager::isMainFile(const FileEntry &SourceFile) {
+  assert(MainFileID.isValid() && "expected initialized SourceManager");
+  if (auto *FE = getFileEntryForID(MainFileID))
+    return FE->getUID() == SourceFile.getUID();
+  return false;
+}
+
+void SourceManager::initializeForReplay(const SourceManager &Old) {
+  assert(MainFileID.isInvalid() && "expected uninitialized SourceManager");
+
+  auto CloneContentCache = [&](const ContentCache *Cache) -> ContentCache * {
+    auto *Clone = new (ContentCacheAlloc.Allocate<ContentCache>()) ContentCache;
+    Clone->OrigEntry = Cache->OrigEntry;
+    Clone->ContentsEntry = Cache->ContentsEntry;
+    Clone->BufferOverridden = Cache->BufferOverridden;
+    Clone->IsFileVolatile = Cache->IsFileVolatile;
+    Clone->IsTransient = Cache->IsTransient;
+    Clone->setUnownedBuffer(Cache->getBufferIfLoaded());
+    return Clone;
+  };
+
+  // Ensure all SLocEntries are loaded from the external source.
+  for (unsigned I = 0, N = Old.LoadedSLocEntryTable.size(); I != N; ++I)
+    if (!Old.SLocEntryLoaded[I])
+      Old.loadSLocEntry(I, nullptr);
+
+  // Inherit any content cache data from the old source manager.
+  for (auto &FileInfo : Old.FileInfos) {
+    SrcMgr::ContentCache *&Slot = FileInfos[FileInfo.first];
+    if (Slot)
+      continue;
+    Slot = CloneContentCache(FileInfo.second);
+  }
+}
+
+ContentCache &SourceManager::getOrCreateContentCache(FileEntryRef FileEnt,
+                                                     bool isSystemFile) {
+  // Do we already have information about this file?
+  ContentCache *&Entry = FileInfos[FileEnt];
+  if (Entry)
+    return *Entry;
+
+  // Nope, create a new Cache entry.
+  Entry = ContentCacheAlloc.Allocate<ContentCache>();
+
+  if (OverriddenFilesInfo) {
+    // If the file contents are overridden with contents from another file,
+    // pass that file to ContentCache.
+    llvm::DenseMap<const FileEntry *, const FileEntry *>::iterator
+        overI = OverriddenFilesInfo->OverriddenFiles.find(FileEnt);
+    if (overI == OverriddenFilesInfo->OverriddenFiles.end())
+      new (Entry) ContentCache(FileEnt);
+    else
+      new (Entry) ContentCache(OverridenFilesKeepOriginalName ? FileEnt
+                                                              : overI->second,
+                               overI->second);
+  } else {
+    new (Entry) ContentCache(FileEnt);
+  }
+
+  Entry->IsFileVolatile = UserFilesAreVolatile && !isSystemFile;
+  Entry->IsTransient = FilesAreTransient;
+  Entry->BufferOverridden |= FileEnt.isNamedPipe();
+
+  return *Entry;
+}
+
+/// Create a new ContentCache for the specified memory buffer.
+/// This does no caching.
+ContentCache &SourceManager::createMemBufferContentCache(
+    std::unique_ptr<llvm::MemoryBuffer> Buffer) {
+  // Add a new ContentCache to the MemBufferInfos list and return it.
+  ContentCache *Entry = ContentCacheAlloc.Allocate<ContentCache>();
+  new (Entry) ContentCache();
+  MemBufferInfos.push_back(Entry);
+  Entry->setBuffer(std::move(Buffer));
+  return *Entry;
+}
+
+const SrcMgr::SLocEntry &SourceManager::loadSLocEntry(unsigned Index,
+                                                      bool *Invalid) const {
+  assert(!SLocEntryLoaded[Index]);
+  if (ExternalSLocEntries->ReadSLocEntry(-(static_cast<int>(Index) + 2))) {
+    if (Invalid)
+      *Invalid = true;
+    // If the file of the SLocEntry changed we could still have loaded it.
+    if (!SLocEntryLoaded[Index]) {
+      // Try to recover; create a SLocEntry so the rest of clang can handle it.
+      if (!FakeSLocEntryForRecovery)
+        FakeSLocEntryForRecovery = std::make_unique<SLocEntry>(SLocEntry::get(
+            0, FileInfo::get(SourceLocation(), getFakeContentCacheForRecovery(),
+                             SrcMgr::C_User, "")));
+      return *FakeSLocEntryForRecovery;
+    }
+  }
+
+  return LoadedSLocEntryTable[Index];
+}
+
+std::pair<int, SourceLocation::UIntTy>
+SourceManager::AllocateLoadedSLocEntries(unsigned NumSLocEntries,
+                                         SourceLocation::UIntTy TotalSize) {
+  assert(ExternalSLocEntries && "Don't have an external sloc source");
+  // Make sure we're not about to run out of source locations.
+  if (CurrentLoadedOffset - TotalSize < NextLocalOffset)
+    return std::make_pair(0, 0);
+  LoadedSLocEntryTable.resize(LoadedSLocEntryTable.size() + NumSLocEntries);
+  SLocEntryLoaded.resize(LoadedSLocEntryTable.size());
+  CurrentLoadedOffset -= TotalSize;
+  int ID = LoadedSLocEntryTable.size();
+  return std::make_pair(-ID - 1, CurrentLoadedOffset);
+}
+
+/// As part of recovering from missing or changed content, produce a
+/// fake, non-empty buffer.
+llvm::MemoryBufferRef SourceManager::getFakeBufferForRecovery() const {
+  if (!FakeBufferForRecovery)
+    FakeBufferForRecovery =
+        llvm::MemoryBuffer::getMemBuffer("<<<INVALID BUFFER>>");
+
+  return *FakeBufferForRecovery;
+}
+
+/// As part of recovering from missing or changed content, produce a
+/// fake content cache.
+SrcMgr::ContentCache &SourceManager::getFakeContentCacheForRecovery() const {
+  if (!FakeContentCacheForRecovery) {
+    FakeContentCacheForRecovery = std::make_unique<SrcMgr::ContentCache>();
+    FakeContentCacheForRecovery->setUnownedBuffer(getFakeBufferForRecovery());
+  }
+  return *FakeContentCacheForRecovery;
+}
+
+/// Returns the previous in-order FileID or an invalid FileID if there
+/// is no previous one.
+FileID SourceManager::getPreviousFileID(FileID FID) const {
+  if (FID.isInvalid())
+    return FileID();
+
+  int ID = FID.ID;
+  if (ID == -1)
+    return FileID();
+
+  if (ID > 0) {
+    if (ID-1 == 0)
+      return FileID();
+  } else if (unsigned(-(ID-1) - 2) >= LoadedSLocEntryTable.size()) {
+    return FileID();
+  }
+
+  return FileID::get(ID-1);
+}
+
+/// Returns the next in-order FileID or an invalid FileID if there is
+/// no next one.
+FileID SourceManager::getNextFileID(FileID FID) const {
+  if (FID.isInvalid())
+    return FileID();
+
+  int ID = FID.ID;
+  if (ID > 0) {
+    if (unsigned(ID+1) >= local_sloc_entry_size())
+      return FileID();
+  } else if (ID+1 >= -1) {
+    return FileID();
+  }
+
+  return FileID::get(ID+1);
+}
+
+//===----------------------------------------------------------------------===//
+// Methods to create new FileID's and macro expansions.
+//===----------------------------------------------------------------------===//
+
+/// Create a new FileID that represents the specified file
+/// being \#included from the specified IncludePosition.
+///
+/// This translates NULL into standard input.
+FileID SourceManager::createFileID(const FileEntry *SourceFile,
+                                   SourceLocation IncludePos,
+                                   SrcMgr::CharacteristicKind FileCharacter,
+                                   int LoadedID,
+                                   SourceLocation::UIntTy LoadedOffset) {
+  return createFileID(SourceFile->getLastRef(), IncludePos, FileCharacter,
+                      LoadedID, LoadedOffset);
+}
+
+FileID SourceManager::createFileID(FileEntryRef SourceFile,
+                                   SourceLocation IncludePos,
+                                   SrcMgr::CharacteristicKind FileCharacter,
+                                   int LoadedID,
+                                   SourceLocation::UIntTy LoadedOffset) {
+  SrcMgr::ContentCache &IR = getOrCreateContentCache(SourceFile,
+                                                     isSystem(FileCharacter));
+
+  // If this is a named pipe, immediately load the buffer to ensure subsequent
+  // calls to ContentCache::getSize() are accurate.
+  if (IR.ContentsEntry->isNamedPipe())
+    (void)IR.getBufferOrNone(Diag, getFileManager(), SourceLocation());
+
+  return createFileIDImpl(IR, SourceFile.getName(), IncludePos, FileCharacter,
+                          LoadedID, LoadedOffset);
+}
+
+/// Create a new FileID that represents the specified memory buffer.
+///
+/// This does no caching of the buffer and takes ownership of the
+/// MemoryBuffer, so only pass a MemoryBuffer to this once.
+FileID SourceManager::createFileID(std::unique_ptr<llvm::MemoryBuffer> Buffer,
+                                   SrcMgr::CharacteristicKind FileCharacter,
+                                   int LoadedID,
+                                   SourceLocation::UIntTy LoadedOffset,
+                                   SourceLocation IncludeLoc) {
+  StringRef Name = Buffer->getBufferIdentifier();
+  return createFileIDImpl(createMemBufferContentCache(std::move(Buffer)), Name,
+                          IncludeLoc, FileCharacter, LoadedID, LoadedOffset);
+}
+
+/// Create a new FileID that represents the specified memory buffer.
+///
+/// This does not take ownership of the MemoryBuffer. The memory buffer must
+/// outlive the SourceManager.
+FileID SourceManager::createFileID(const llvm::MemoryBufferRef &Buffer,
+                                   SrcMgr::CharacteristicKind FileCharacter,
+                                   int LoadedID,
+                                   SourceLocation::UIntTy LoadedOffset,
+                                   SourceLocation IncludeLoc) {
+  return createFileID(llvm::MemoryBuffer::getMemBuffer(Buffer), FileCharacter,
+                      LoadedID, LoadedOffset, IncludeLoc);
+}
+
+/// Get the FileID for \p SourceFile if it exists. Otherwise, create a
+/// new FileID for the \p SourceFile.
+FileID
+SourceManager::getOrCreateFileID(const FileEntry *SourceFile,
+                                 SrcMgr::CharacteristicKind FileCharacter) {
+  FileID ID = translateFile(SourceFile);
+  return ID.isValid() ? ID : createFileID(SourceFile, SourceLocation(),
+					  FileCharacter);
+}
+
+/// createFileID - Create a new FileID for the specified ContentCache and
+/// include position.  This works regardless of whether the ContentCache
+/// corresponds to a file or some other input source.
+FileID SourceManager::createFileIDImpl(ContentCache &File, StringRef Filename,
+                                       SourceLocation IncludePos,
+                                       SrcMgr::CharacteristicKind FileCharacter,
+                                       int LoadedID,
+                                       SourceLocation::UIntTy LoadedOffset) {
+  if (LoadedID < 0) {
+    assert(LoadedID != -1 && "Loading sentinel FileID");
+    unsigned Index = unsigned(-LoadedID) - 2;
+    assert(Index < LoadedSLocEntryTable.size() && "FileID out of range");
+    assert(!SLocEntryLoaded[Index] && "FileID already loaded");
+    LoadedSLocEntryTable[Index] = SLocEntry::get(
+        LoadedOffset, FileInfo::get(IncludePos, File, FileCharacter, Filename));
+    SLocEntryLoaded[Index] = true;
+    return FileID::get(LoadedID);
+  }
+  unsigned FileSize = File.getSize();
+  if (!(NextLocalOffset + FileSize + 1 > NextLocalOffset &&
+        NextLocalOffset + FileSize + 1 <= CurrentLoadedOffset)) {
+    Diag.Report(IncludePos, diag::err_include_too_large);
+    return FileID();
+  }
+  LocalSLocEntryTable.push_back(
+      SLocEntry::get(NextLocalOffset,
+                     FileInfo::get(IncludePos, File, FileCharacter, Filename)));
+  // We do a +1 here because we want a SourceLocation that means "the end of the
+  // file", e.g. for the "no newline at the end of the file" diagnostic.
+  NextLocalOffset += FileSize + 1;
+
+  // Set LastFileIDLookup to the newly created file.  The next getFileID call is
+  // almost guaranteed to be from that file.
+  FileID FID = FileID::get(LocalSLocEntryTable.size()-1);
+  return LastFileIDLookup = FID;
+}
+
+SourceLocation
+SourceManager::createMacroArgExpansionLoc(SourceLocation SpellingLoc,
+                                          SourceLocation ExpansionLoc,
+                                          unsigned TokLength) {
+  ExpansionInfo Info = ExpansionInfo::createForMacroArg(SpellingLoc,
+                                                        ExpansionLoc);
+  return createExpansionLocImpl(Info, TokLength);
+}
+
+SourceLocation SourceManager::createExpansionLoc(
+    SourceLocation SpellingLoc, SourceLocation ExpansionLocStart,
+    SourceLocation ExpansionLocEnd, unsigned TokLength,
+    bool ExpansionIsTokenRange, int LoadedID,
+    SourceLocation::UIntTy LoadedOffset) {
+  ExpansionInfo Info = ExpansionInfo::create(
+      SpellingLoc, ExpansionLocStart, ExpansionLocEnd, ExpansionIsTokenRange);
+  return createExpansionLocImpl(Info, TokLength, LoadedID, LoadedOffset);
+}
+
+SourceLocation SourceManager::createTokenSplitLoc(SourceLocation Spelling,
+                                                  SourceLocation TokenStart,
+                                                  SourceLocation TokenEnd) {
+  assert(getFileID(TokenStart) == getFileID(TokenEnd) &&
+         "token spans multiple files");
+  return createExpansionLocImpl(
+      ExpansionInfo::createForTokenSplit(Spelling, TokenStart, TokenEnd),
+      TokenEnd.getOffset() - TokenStart.getOffset());
+}
+
+SourceLocation
+SourceManager::createExpansionLocImpl(const ExpansionInfo &Info,
+                                      unsigned TokLength, int LoadedID,
+                                      SourceLocation::UIntTy LoadedOffset) {
+  if (LoadedID < 0) {
+    assert(LoadedID != -1 && "Loading sentinel FileID");
+    unsigned Index = unsigned(-LoadedID) - 2;
+    assert(Index < LoadedSLocEntryTable.size() && "FileID out of range");
+    assert(!SLocEntryLoaded[Index] && "FileID already loaded");
+    LoadedSLocEntryTable[Index] = SLocEntry::get(LoadedOffset, Info);
+    SLocEntryLoaded[Index] = true;
+    return SourceLocation::getMacroLoc(LoadedOffset);
+  }
+  LocalSLocEntryTable.push_back(SLocEntry::get(NextLocalOffset, Info));
+  assert(NextLocalOffset + TokLength + 1 > NextLocalOffset &&
+         NextLocalOffset + TokLength + 1 <= CurrentLoadedOffset &&
+         "Ran out of source locations!");
+  // See createFileID for that +1.
+  NextLocalOffset += TokLength + 1;
+  return SourceLocation::getMacroLoc(NextLocalOffset - (TokLength + 1));
+}
+
+llvm::Optional<llvm::MemoryBufferRef>
+SourceManager::getMemoryBufferForFileOrNone(const FileEntry *File) {
+  SrcMgr::ContentCache &IR = getOrCreateContentCache(File->getLastRef());
+  return IR.getBufferOrNone(Diag, getFileManager(), SourceLocation());
+}
+
+void SourceManager::overrideFileContents(
+    const FileEntry *SourceFile, std::unique_ptr<llvm::MemoryBuffer> Buffer) {
+  SrcMgr::ContentCache &IR = getOrCreateContentCache(SourceFile->getLastRef());
+
+  IR.setBuffer(std::move(Buffer));
+  IR.BufferOverridden = true;
+
+  getOverriddenFilesInfo().OverriddenFilesWithBuffer.insert(SourceFile);
+}
+
+void SourceManager::overrideFileContents(const FileEntry *SourceFile,
+                                         const FileEntry *NewFile) {
+  assert(SourceFile->getSize() == NewFile->getSize() &&
+         "Different sizes, use the FileManager to create a virtual file with "
+         "the correct size");
+  assert(FileInfos.count(SourceFile) == 0 &&
+         "This function should be called at the initialization stage, before "
+         "any parsing occurs.");
+  getOverriddenFilesInfo().OverriddenFiles[SourceFile] = NewFile;
+}
+
+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 None;
+
+  (void)getOrCreateContentCache(*BypassFile);
+  return BypassFile;
+}
+
+void SourceManager::setFileIsTransient(const FileEntry *File) {
+  getOrCreateContentCache(File->getLastRef()).IsTransient = true;
+}
+
+Optional<StringRef>
+SourceManager::getNonBuiltinFilenameForID(FileID FID) const {
+  if (const SrcMgr::SLocEntry *Entry = getSLocEntryForFile(FID))
+    if (Entry->getFile().getContentCache().OrigEntry)
+      return Entry->getFile().getName();
+  return None;
+}
+
+StringRef SourceManager::getBufferData(FileID FID, bool *Invalid) const {
+  auto B = getBufferDataOrNone(FID);
+  if (Invalid)
+    *Invalid = !B;
+  return B ? *B : "<<<<<INVALID SOURCE LOCATION>>>>>";
+}
+
+llvm::Optional<StringRef>
+SourceManager::getBufferDataIfLoaded(FileID FID) const {
+  if (const SrcMgr::SLocEntry *Entry = getSLocEntryForFile(FID))
+    return Entry->getFile().getContentCache().getBufferDataIfLoaded();
+  return None;
+}
+
+llvm::Optional<StringRef> SourceManager::getBufferDataOrNone(FileID FID) const {
+  if (const SrcMgr::SLocEntry *Entry = getSLocEntryForFile(FID))
+    if (auto B = Entry->getFile().getContentCache().getBufferOrNone(
+            Diag, getFileManager(), SourceLocation()))
+      return B->getBuffer();
+  return None;
+}
+
+//===----------------------------------------------------------------------===//
+// SourceLocation manipulation methods.
+//===----------------------------------------------------------------------===//
+
+/// Return the FileID for a SourceLocation.
+///
+/// This is the cache-miss path of getFileID. Not as hot as that function, but
+/// still very important. It is responsible for finding the entry in the
+/// SLocEntry tables that contains the specified location.
+FileID SourceManager::getFileIDSlow(SourceLocation::UIntTy SLocOffset) const {
+  if (!SLocOffset)
+    return FileID::get(0);
+
+  // Now it is time to search for the correct file. See where the SLocOffset
+  // sits in the global view and consult local or loaded buffers for it.
+  if (SLocOffset < NextLocalOffset)
+    return getFileIDLocal(SLocOffset);
+  return getFileIDLoaded(SLocOffset);
+}
+
+/// Return the FileID for a SourceLocation with a low offset.
+///
+/// This function knows that the SourceLocation is in a local buffer, not a
+/// loaded one.
+FileID SourceManager::getFileIDLocal(SourceLocation::UIntTy SLocOffset) const {
+  assert(SLocOffset < NextLocalOffset && "Bad function choice");
+
+  // After the first and second level caches, I see two common sorts of
+  // behavior: 1) a lot of searched FileID's are "near" the cached file
+  // location or are "near" the cached expansion location. 2) others are just
+  // completely random and may be a very long way away.
+  //
+  // To handle this, we do a linear search for up to 8 steps to catch #1 quickly
+  // then we fall back to a less cache efficient, but more scalable, binary
+  // search to find the location.
+
+  // See if this is near the file point - worst case we start scanning from the
+  // most newly created FileID.
+  const SrcMgr::SLocEntry *I;
+
+  if (LastFileIDLookup.ID < 0 ||
+      LocalSLocEntryTable[LastFileIDLookup.ID].getOffset() < SLocOffset) {
+    // Neither loc prunes our search.
+    I = LocalSLocEntryTable.end();
+  } else {
+    // Perhaps it is near the file point.
+    I = LocalSLocEntryTable.begin()+LastFileIDLookup.ID;
+  }
+
+  // Find the FileID that contains this.  "I" is an iterator that points to a
+  // FileID whose offset is known to be larger than SLocOffset.
+  unsigned NumProbes = 0;
+  while (true) {
+    --I;
+    if (I->getOffset() <= SLocOffset) {
+      FileID Res = FileID::get(int(I - LocalSLocEntryTable.begin()));
+      // Remember it.  We have good locality across FileID lookups.
+      LastFileIDLookup = Res;
+      NumLinearScans += NumProbes+1;
+      return Res;
+    }
+    if (++NumProbes == 8)
+      break;
+  }
+
+  // Convert "I" back into an index.  We know that it is an entry whose index is
+  // larger than the offset we are looking for.
+  unsigned GreaterIndex = I - LocalSLocEntryTable.begin();
+  // LessIndex - This is the lower bound of the range that we're searching.
+  // We know that the offset corresponding to the FileID is is less than
+  // SLocOffset.
+  unsigned LessIndex = 0;
+  NumProbes = 0;
+  while (true) {
+    unsigned MiddleIndex = (GreaterIndex-LessIndex)/2+LessIndex;
+    SourceLocation::UIntTy MidOffset =
+        getLocalSLocEntry(MiddleIndex).getOffset();
+
+    ++NumProbes;
+
+    // If the offset of the midpoint is too large, chop the high side of the
+    // range to the midpoint.
+    if (MidOffset > SLocOffset) {
+      GreaterIndex = MiddleIndex;
+      continue;
+    }
+
+    // If the middle index contains the value, succeed and return.
+    if (MiddleIndex + 1 == LocalSLocEntryTable.size() ||
+        SLocOffset < getLocalSLocEntry(MiddleIndex + 1).getOffset()) {
+      FileID Res = FileID::get(MiddleIndex);
+
+      // Remember it.  We have good locality across FileID lookups.
+      LastFileIDLookup = Res;
+      NumBinaryProbes += NumProbes;
+      return Res;
+    }
+
+    // Otherwise, move the low-side up to the middle index.
+    LessIndex = MiddleIndex;
+  }
+}
+
+/// Return the FileID for a SourceLocation with a high offset.
+///
+/// This function knows that the SourceLocation is in a loaded buffer, not a
+/// local one.
+FileID SourceManager::getFileIDLoaded(SourceLocation::UIntTy SLocOffset) const {
+  if (SLocOffset < CurrentLoadedOffset) {
+    assert(0 && "Invalid SLocOffset or bad function choice");
+    return FileID();
+  }
+
+  // Essentially the same as the local case, but the loaded array is sorted
+  // in the other direction.
+
+  // First do a linear scan from the last lookup position, if possible.
+  unsigned I;
+  int LastID = LastFileIDLookup.ID;
+  if (LastID >= 0 || getLoadedSLocEntryByID(LastID).getOffset() < SLocOffset)
+    I = 0;
+  else
+    I = (-LastID - 2) + 1;
+
+  unsigned NumProbes;
+  for (NumProbes = 0; NumProbes < 8; ++NumProbes, ++I) {
+    // Make sure the entry is loaded!
+    const SrcMgr::SLocEntry &E = getLoadedSLocEntry(I);
+    if (E.getOffset() <= SLocOffset) {
+      FileID Res = FileID::get(-int(I) - 2);
+      LastFileIDLookup = Res;
+      NumLinearScans += NumProbes + 1;
+      return Res;
+    }
+  }
+
+  // Linear scan failed. Do the binary search. Note the reverse sorting of the
+  // table: GreaterIndex is the one where the offset is greater, which is
+  // actually a lower index!
+  unsigned GreaterIndex = I;
+  unsigned LessIndex = LoadedSLocEntryTable.size();
+  NumProbes = 0;
+  while (true) {
+    ++NumProbes;
+    unsigned MiddleIndex = (LessIndex - GreaterIndex) / 2 + GreaterIndex;
+    const SrcMgr::SLocEntry &E = getLoadedSLocEntry(MiddleIndex);
+    if (E.getOffset() == 0)
+      return FileID(); // invalid entry.
+
+    ++NumProbes;
+
+    if (E.getOffset() > SLocOffset) {
+      if (GreaterIndex == MiddleIndex) {
+        assert(0 && "binary search missed the entry");
+        return FileID();
+      }
+      GreaterIndex = MiddleIndex;
+      continue;
+    }
+
+    if (isOffsetInFileID(FileID::get(-int(MiddleIndex) - 2), SLocOffset)) {
+      FileID Res = FileID::get(-int(MiddleIndex) - 2);
+      LastFileIDLookup = Res;
+      NumBinaryProbes += NumProbes;
+      return Res;
+    }
+
+    if (LessIndex == MiddleIndex) {
+      assert(0 && "binary search missed the entry");
+      return FileID();
+    }
+    LessIndex = MiddleIndex;
+  }
+}
+
+SourceLocation SourceManager::
+getExpansionLocSlowCase(SourceLocation Loc) const {
+  do {
+    // Note: If Loc indicates an offset into a token that came from a macro
+    // expansion (e.g. the 5th character of the token) we do not want to add
+    // this offset when going to the expansion location.  The expansion
+    // location is the macro invocation, which the offset has nothing to do
+    // with.  This is unlike when we get the spelling loc, because the offset
+    // directly correspond to the token whose spelling we're inspecting.
+    Loc = getSLocEntry(getFileID(Loc)).getExpansion().getExpansionLocStart();
+  } while (!Loc.isFileID());
+
+  return Loc;
+}
+
+SourceLocation SourceManager::getSpellingLocSlowCase(SourceLocation Loc) const {
+  do {
+    std::pair<FileID, unsigned> LocInfo = getDecomposedLoc(Loc);
+    Loc = getSLocEntry(LocInfo.first).getExpansion().getSpellingLoc();
+    Loc = Loc.getLocWithOffset(LocInfo.second);
+  } while (!Loc.isFileID());
+  return Loc;
+}
+
+SourceLocation SourceManager::getFileLocSlowCase(SourceLocation Loc) const {
+  do {
+    if (isMacroArgExpansion(Loc))
+      Loc = getImmediateSpellingLoc(Loc);
+    else
+      Loc = getImmediateExpansionRange(Loc).getBegin();
+  } while (!Loc.isFileID());
+  return Loc;
+}
+
+
+std::pair<FileID, unsigned>
+SourceManager::getDecomposedExpansionLocSlowCase(
+                                             const SrcMgr::SLocEntry *E) const {
+  // If this is an expansion record, walk through all the expansion points.
+  FileID FID;
+  SourceLocation Loc;
+  unsigned Offset;
+  do {
+    Loc = E->getExpansion().getExpansionLocStart();
+
+    FID = getFileID(Loc);
+    E = &getSLocEntry(FID);
+    Offset = Loc.getOffset()-E->getOffset();
+  } while (!Loc.isFileID());
+
+  return std::make_pair(FID, Offset);
+}
+
+std::pair<FileID, unsigned>
+SourceManager::getDecomposedSpellingLocSlowCase(const SrcMgr::SLocEntry *E,
+                                                unsigned Offset) const {
+  // If this is an expansion record, walk through all the expansion points.
+  FileID FID;
+  SourceLocation Loc;
+  do {
+    Loc = E->getExpansion().getSpellingLoc();
+    Loc = Loc.getLocWithOffset(Offset);
+
+    FID = getFileID(Loc);
+    E = &getSLocEntry(FID);
+    Offset = Loc.getOffset()-E->getOffset();
+  } while (!Loc.isFileID());
+
+  return std::make_pair(FID, Offset);
+}
+
+/// getImmediateSpellingLoc - Given a SourceLocation object, return the
+/// spelling location referenced by the ID.  This is the first level down
+/// towards the place where the characters that make up the lexed token can be
+/// found.  This should not generally be used by clients.
+SourceLocation SourceManager::getImmediateSpellingLoc(SourceLocation Loc) const{
+  if (Loc.isFileID()) return Loc;
+  std::pair<FileID, unsigned> LocInfo = getDecomposedLoc(Loc);
+  Loc = getSLocEntry(LocInfo.first).getExpansion().getSpellingLoc();
+  return Loc.getLocWithOffset(LocInfo.second);
+}
+
+/// Return the filename of the file containing a SourceLocation.
+StringRef SourceManager::getFilename(SourceLocation SpellingLoc) const {
+  if (const FileEntry *F = getFileEntryForID(getFileID(SpellingLoc)))
+    return F->getName();
+  return StringRef();
+}
+
+/// getImmediateExpansionRange - Loc is required to be an expansion location.
+/// Return the start/end of the expansion information.
+CharSourceRange
+SourceManager::getImmediateExpansionRange(SourceLocation Loc) const {
+  assert(Loc.isMacroID() && "Not a macro expansion loc!");
+  const ExpansionInfo &Expansion = getSLocEntry(getFileID(Loc)).getExpansion();
+  return Expansion.getExpansionLocRange();
+}
+
+SourceLocation SourceManager::getTopMacroCallerLoc(SourceLocation Loc) const {
+  while (isMacroArgExpansion(Loc))
+    Loc = getImmediateSpellingLoc(Loc);
+  return Loc;
+}
+
+/// getExpansionRange - Given a SourceLocation object, return the range of
+/// tokens covered by the expansion in the ultimate file.
+CharSourceRange SourceManager::getExpansionRange(SourceLocation Loc) const {
+  if (Loc.isFileID())
+    return CharSourceRange(SourceRange(Loc, Loc), true);
+
+  CharSourceRange Res = getImmediateExpansionRange(Loc);
+
+  // Fully resolve the start and end locations to their ultimate expansion
+  // points.
+  while (!Res.getBegin().isFileID())
+    Res.setBegin(getImmediateExpansionRange(Res.getBegin()).getBegin());
+  while (!Res.getEnd().isFileID()) {
+    CharSourceRange EndRange = getImmediateExpansionRange(Res.getEnd());
+    Res.setEnd(EndRange.getEnd());
+    Res.setTokenRange(EndRange.isTokenRange());
+  }
+  return Res;
+}
+
+bool SourceManager::isMacroArgExpansion(SourceLocation Loc,
+                                        SourceLocation *StartLoc) const {
+  if (!Loc.isMacroID()) return false;
+
+  FileID FID = getFileID(Loc);
+  const SrcMgr::ExpansionInfo &Expansion = getSLocEntry(FID).getExpansion();
+  if (!Expansion.isMacroArgExpansion()) return false;
+
+  if (StartLoc)
+    *StartLoc = Expansion.getExpansionLocStart();
+  return true;
+}
+
+bool SourceManager::isMacroBodyExpansion(SourceLocation Loc) const {
+  if (!Loc.isMacroID()) return false;
+
+  FileID FID = getFileID(Loc);
+  const SrcMgr::ExpansionInfo &Expansion = getSLocEntry(FID).getExpansion();
+  return Expansion.isMacroBodyExpansion();
+}
+
+bool SourceManager::isAtStartOfImmediateMacroExpansion(SourceLocation Loc,
+                                             SourceLocation *MacroBegin) const {
+  assert(Loc.isValid() && Loc.isMacroID() && "Expected a valid macro loc");
+
+  std::pair<FileID, unsigned> DecompLoc = getDecomposedLoc(Loc);
+  if (DecompLoc.second > 0)
+    return false; // Does not point at the start of expansion range.
+
+  bool Invalid = false;
+  const SrcMgr::ExpansionInfo &ExpInfo =
+      getSLocEntry(DecompLoc.first, &Invalid).getExpansion();
+  if (Invalid)
+    return false;
+  SourceLocation ExpLoc = ExpInfo.getExpansionLocStart();
+
+  if (ExpInfo.isMacroArgExpansion()) {
+    // For macro argument expansions, check if the previous FileID is part of
+    // the same argument expansion, in which case this Loc is not at the
+    // beginning of the expansion.
+    FileID PrevFID = getPreviousFileID(DecompLoc.first);
+    if (!PrevFID.isInvalid()) {
+      const SrcMgr::SLocEntry &PrevEntry = getSLocEntry(PrevFID, &Invalid);
+      if (Invalid)
+        return false;
+      if (PrevEntry.isExpansion() &&
+          PrevEntry.getExpansion().getExpansionLocStart() == ExpLoc)
+        return false;
+    }
+  }
+
+  if (MacroBegin)
+    *MacroBegin = ExpLoc;
+  return true;
+}
+
+bool SourceManager::isAtEndOfImmediateMacroExpansion(SourceLocation Loc,
+                                               SourceLocation *MacroEnd) const {
+  assert(Loc.isValid() && Loc.isMacroID() && "Expected a valid macro loc");
+
+  FileID FID = getFileID(Loc);
+  SourceLocation NextLoc = Loc.getLocWithOffset(1);
+  if (isInFileID(NextLoc, FID))
+    return false; // Does not point at the end of expansion range.
+
+  bool Invalid = false;
+  const SrcMgr::ExpansionInfo &ExpInfo =
+      getSLocEntry(FID, &Invalid).getExpansion();
+  if (Invalid)
+    return false;
+
+  if (ExpInfo.isMacroArgExpansion()) {
+    // For macro argument expansions, check if the next FileID is part of the
+    // same argument expansion, in which case this Loc is not at the end of the
+    // expansion.
+    FileID NextFID = getNextFileID(FID);
+    if (!NextFID.isInvalid()) {
+      const SrcMgr::SLocEntry &NextEntry = getSLocEntry(NextFID, &Invalid);
+      if (Invalid)
+        return false;
+      if (NextEntry.isExpansion() &&
+          NextEntry.getExpansion().getExpansionLocStart() ==
+              ExpInfo.getExpansionLocStart())
+        return false;
+    }
+  }
+
+  if (MacroEnd)
+    *MacroEnd = ExpInfo.getExpansionLocEnd();
+  return true;
+}
+
+//===----------------------------------------------------------------------===//
+// Queries about the code at a SourceLocation.
+//===----------------------------------------------------------------------===//
+
+/// getCharacterData - Return a pointer to the start of the specified location
+/// in the appropriate MemoryBuffer.
+const char *SourceManager::getCharacterData(SourceLocation SL,
+                                            bool *Invalid) const {
+  // Note that this is a hot function in the getSpelling() path, which is
+  // heavily used by -E mode.
+  std::pair<FileID, unsigned> LocInfo = getDecomposedSpellingLoc(SL);
+
+  // Note that calling 'getBuffer()' may lazily page in a source file.
+  bool CharDataInvalid = false;
+  const SLocEntry &Entry = getSLocEntry(LocInfo.first, &CharDataInvalid);
+  if (CharDataInvalid || !Entry.isFile()) {
+    if (Invalid)
+      *Invalid = true;
+
+    return "<<<<INVALID BUFFER>>>>";
+  }
+  llvm::Optional<llvm::MemoryBufferRef> Buffer =
+      Entry.getFile().getContentCache().getBufferOrNone(Diag, getFileManager(),
+                                                        SourceLocation());
+  if (Invalid)
+    *Invalid = !Buffer;
+  return Buffer ? Buffer->getBufferStart() + LocInfo.second
+                : "<<<<INVALID BUFFER>>>>";
+}
+
+/// getColumnNumber - Return the column # for the specified file position.
+/// this is significantly cheaper to compute than the line number.
+unsigned SourceManager::getColumnNumber(FileID FID, unsigned FilePos,
+                                        bool *Invalid) const {
+  llvm::Optional<llvm::MemoryBufferRef> MemBuf = getBufferOrNone(FID);
+  if (Invalid)
+    *Invalid = !MemBuf;
+
+  if (!MemBuf)
+    return 1;
+
+  // It is okay to request a position just past the end of the buffer.
+  if (FilePos > MemBuf->getBufferSize()) {
+    if (Invalid)
+      *Invalid = true;
+    return 1;
+  }
+
+  const char *Buf = MemBuf->getBufferStart();
+  // See if we just calculated the line number for this FilePos and can use
+  // that to lookup the start of the line instead of searching for it.
+  if (LastLineNoFileIDQuery == FID && LastLineNoContentCache->SourceLineCache &&
+      LastLineNoResult < LastLineNoContentCache->SourceLineCache.size()) {
+    const unsigned *SourceLineCache =
+        LastLineNoContentCache->SourceLineCache.begin();
+    unsigned LineStart = SourceLineCache[LastLineNoResult - 1];
+    unsigned LineEnd = SourceLineCache[LastLineNoResult];
+    if (FilePos >= LineStart && FilePos < LineEnd) {
+      // LineEnd is the LineStart of the next line.
+      // A line ends with separator LF or CR+LF on Windows.
+      // FilePos might point to the last separator,
+      // but we need a column number at most 1 + the last column.
+      if (FilePos + 1 == LineEnd && FilePos > LineStart) {
+        if (Buf[FilePos - 1] == '\r' || Buf[FilePos - 1] == '\n')
+          --FilePos;
+      }
+      return FilePos - LineStart + 1;
+    }
+  }
+
+  unsigned LineStart = FilePos;
+  while (LineStart && Buf[LineStart-1] != '\n' && Buf[LineStart-1] != '\r')
+    --LineStart;
+  return FilePos-LineStart+1;
+}
+
+// isInvalid - Return the result of calling loc.isInvalid(), and
+// if Invalid is not null, set its value to same.
+template<typename LocType>
+static bool isInvalid(LocType Loc, bool *Invalid) {
+  bool MyInvalid = Loc.isInvalid();
+  if (Invalid)
+    *Invalid = MyInvalid;
+  return MyInvalid;
+}
+
+unsigned SourceManager::getSpellingColumnNumber(SourceLocation Loc,
+                                                bool *Invalid) const {
+  if (isInvalid(Loc, Invalid)) return 0;
+  std::pair<FileID, unsigned> LocInfo = getDecomposedSpellingLoc(Loc);
+  return getColumnNumber(LocInfo.first, LocInfo.second, Invalid);
+}
+
+unsigned SourceManager::getExpansionColumnNumber(SourceLocation Loc,
+                                                 bool *Invalid) const {
+  if (isInvalid(Loc, Invalid)) return 0;
+  std::pair<FileID, unsigned> LocInfo = getDecomposedExpansionLoc(Loc);
+  return getColumnNumber(LocInfo.first, LocInfo.second, Invalid);
+}
+
+unsigned SourceManager::getPresumedColumnNumber(SourceLocation Loc,
+                                                bool *Invalid) const {
+  PresumedLoc PLoc = getPresumedLoc(Loc);
+  if (isInvalid(PLoc, Invalid)) return 0;
+  return PLoc.getColumn();
+}
+
+// Check if mutli-byte word x has bytes between m and n, included. This may also
+// catch bytes equal to n + 1.
+// The returned value holds a 0x80 at each byte position that holds a match.
+// see http://graphics.stanford.edu/~seander/bithacks.html#HasBetweenInWord
+template <class T>
+static constexpr inline T likelyhasbetween(T x, unsigned char m,
+                                           unsigned char n) {
+  return ((x - ~static_cast<T>(0) / 255 * (n + 1)) & ~x &
+          ((x & ~static_cast<T>(0) / 255 * 127) +
+           (~static_cast<T>(0) / 255 * (127 - (m - 1))))) &
+         ~static_cast<T>(0) / 255 * 128;
+}
+
+LineOffsetMapping LineOffsetMapping::get(llvm::MemoryBufferRef Buffer,
+                                         llvm::BumpPtrAllocator &Alloc) {
+
+  // Find the file offsets of all of the *physical* source lines.  This does
+  // not look at trigraphs, escaped newlines, or anything else tricky.
+  SmallVector<unsigned, 256> LineOffsets;
+
+  // Line #1 starts at char 0.
+  LineOffsets.push_back(0);
+
+  const unsigned char *Buf = (const unsigned char *)Buffer.getBufferStart();
+  const unsigned char *End = (const unsigned char *)Buffer.getBufferEnd();
+  const std::size_t BufLen = End - Buf;
+
+  unsigned I = 0;
+  uint64_t Word;
+
+  // scan sizeof(Word) bytes at a time for new lines.
+  // This is much faster than scanning each byte independently.
+  if (BufLen > sizeof(Word)) {
+    do {
+      Word = llvm::support::endian::read64(Buf + I, llvm::support::little);
+      // no new line => jump over sizeof(Word) bytes.
+      auto Mask = likelyhasbetween(Word, '\n', '\r');
+      if (!Mask) {
+        I += sizeof(Word);
+        continue;
+      }
+
+      // At that point, Mask contains 0x80 set at each byte that holds a value
+      // in [\n, \r + 1 [
+
+      // Scan for the next newline - it's very likely there's one.
+      unsigned N =
+          llvm::countTrailingZeros(Mask) - 7; // -7 because 0x80 is the marker
+      Word >>= N;
+      I += N / 8 + 1;
+      unsigned char Byte = Word;
+      if (Byte == '\n') {
+        LineOffsets.push_back(I);
+      } else if (Byte == '\r') {
+        // If this is \r\n, skip both characters.
+        if (Buf[I] == '\n')
+          ++I;
+        LineOffsets.push_back(I);
+      }
+    } while (I < BufLen - sizeof(Word) - 1);
+  }
+
+  // Handle tail using a regular check.
+  while (I < BufLen) {
+    if (Buf[I] == '\n') {
+      LineOffsets.push_back(I + 1);
+    } else if (Buf[I] == '\r') {
+      // If this is \r\n, skip both characters.
+      if (I + 1 < BufLen && Buf[I + 1] == '\n')
+        ++I;
+      LineOffsets.push_back(I + 1);
+    }
+    ++I;
+  }
+
+  return LineOffsetMapping(LineOffsets, Alloc);
+}
+
+LineOffsetMapping::LineOffsetMapping(ArrayRef<unsigned> LineOffsets,
+                                     llvm::BumpPtrAllocator &Alloc)
+    : Storage(Alloc.Allocate<unsigned>(LineOffsets.size() + 1)) {
+  Storage[0] = LineOffsets.size();
+  std::copy(LineOffsets.begin(), LineOffsets.end(), Storage + 1);
+}
+
+/// getLineNumber - Given a SourceLocation, return the spelling line number
+/// for the position indicated.  This requires building and caching a table of
+/// line offsets for the MemoryBuffer, so this is not cheap: use only when
+/// about to emit a diagnostic.
+unsigned SourceManager::getLineNumber(FileID FID, unsigned FilePos,
+                                      bool *Invalid) const {
+  if (FID.isInvalid()) {
+    if (Invalid)
+      *Invalid = true;
+    return 1;
+  }
+
+  const ContentCache *Content;
+  if (LastLineNoFileIDQuery == FID)
+    Content = LastLineNoContentCache;
+  else {
+    bool MyInvalid = false;
+    const SLocEntry &Entry = getSLocEntry(FID, &MyInvalid);
+    if (MyInvalid || !Entry.isFile()) {
+      if (Invalid)
+        *Invalid = true;
+      return 1;
+    }
+
+    Content = &Entry.getFile().getContentCache();
+  }
+
+  // If this is the first use of line information for this buffer, compute the
+  /// SourceLineCache for it on demand.
+  if (!Content->SourceLineCache) {
+    llvm::Optional<llvm::MemoryBufferRef> Buffer =
+        Content->getBufferOrNone(Diag, getFileManager(), SourceLocation());
+    if (Invalid)
+      *Invalid = !Buffer;
+    if (!Buffer)
+      return 1;
+
+    Content->SourceLineCache =
+        LineOffsetMapping::get(*Buffer, ContentCacheAlloc);
+  } else if (Invalid)
+    *Invalid = false;
+
+  // Okay, we know we have a line number table.  Do a binary search to find the
+  // line number that this character position lands on.
+  const unsigned *SourceLineCache = Content->SourceLineCache.begin();
+  const unsigned *SourceLineCacheStart = SourceLineCache;
+  const unsigned *SourceLineCacheEnd = Content->SourceLineCache.end();
+
+  unsigned QueriedFilePos = FilePos+1;
+
+  // FIXME: I would like to be convinced that this code is worth being as
+  // complicated as it is, binary search isn't that slow.
+  //
+  // If it is worth being optimized, then in my opinion it could be more
+  // performant, simpler, and more obviously correct by just "galloping" outward
+  // from the queried file position. In fact, this could be incorporated into a
+  // generic algorithm such as lower_bound_with_hint.
+  //
+  // If someone gives me a test case where this matters, and I will do it! - DWD
+
+  // If the previous query was to the same file, we know both the file pos from
+  // that query and the line number returned.  This allows us to narrow the
+  // search space from the entire file to something near the match.
+  if (LastLineNoFileIDQuery == FID) {
+    if (QueriedFilePos >= LastLineNoFilePos) {
+      // FIXME: Potential overflow?
+      SourceLineCache = SourceLineCache+LastLineNoResult-1;
+
+      // The query is likely to be nearby the previous one.  Here we check to
+      // see if it is within 5, 10 or 20 lines.  It can be far away in cases
+      // where big comment blocks and vertical whitespace eat up lines but
+      // contribute no tokens.
+      if (SourceLineCache+5 < SourceLineCacheEnd) {
+        if (SourceLineCache[5] > QueriedFilePos)
+          SourceLineCacheEnd = SourceLineCache+5;
+        else if (SourceLineCache+10 < SourceLineCacheEnd) {
+          if (SourceLineCache[10] > QueriedFilePos)
+            SourceLineCacheEnd = SourceLineCache+10;
+          else if (SourceLineCache+20 < SourceLineCacheEnd) {
+            if (SourceLineCache[20] > QueriedFilePos)
+              SourceLineCacheEnd = SourceLineCache+20;
+          }
+        }
+      }
+    } else {
+      if (LastLineNoResult < Content->SourceLineCache.size())
+        SourceLineCacheEnd = SourceLineCache+LastLineNoResult+1;
+    }
+  }
+
+  const unsigned *Pos =
+      std::lower_bound(SourceLineCache, SourceLineCacheEnd, QueriedFilePos);
+  unsigned LineNo = Pos-SourceLineCacheStart;
+
+  LastLineNoFileIDQuery = FID;
+  LastLineNoContentCache = Content;
+  LastLineNoFilePos = QueriedFilePos;
+  LastLineNoResult = LineNo;
+  return LineNo;
+}
+
+unsigned SourceManager::getSpellingLineNumber(SourceLocation Loc,
+                                              bool *Invalid) const {
+  if (isInvalid(Loc, Invalid)) return 0;
+  std::pair<FileID, unsigned> LocInfo = getDecomposedSpellingLoc(Loc);
+  return getLineNumber(LocInfo.first, LocInfo.second);
+}
+unsigned SourceManager::getExpansionLineNumber(SourceLocation Loc,
+                                               bool *Invalid) const {
+  if (isInvalid(Loc, Invalid)) return 0;
+  std::pair<FileID, unsigned> LocInfo = getDecomposedExpansionLoc(Loc);
+  return getLineNumber(LocInfo.first, LocInfo.second);
+}
+unsigned SourceManager::getPresumedLineNumber(SourceLocation Loc,
+                                              bool *Invalid) const {
+  PresumedLoc PLoc = getPresumedLoc(Loc);
+  if (isInvalid(PLoc, Invalid)) return 0;
+  return PLoc.getLine();
+}
+
+/// getFileCharacteristic - return the file characteristic of the specified
+/// source location, indicating whether this is a normal file, a system
+/// header, or an "implicit extern C" system header.
+///
+/// This state can be modified with flags on GNU linemarker directives like:
+///   # 4 "foo.h" 3
+/// which changes all source locations in the current file after that to be
+/// considered to be from a system header.
+SrcMgr::CharacteristicKind
+SourceManager::getFileCharacteristic(SourceLocation Loc) const {
+  assert(Loc.isValid() && "Can't get file characteristic of invalid loc!");
+  std::pair<FileID, unsigned> LocInfo = getDecomposedExpansionLoc(Loc);
+  const SLocEntry *SEntry = getSLocEntryForFile(LocInfo.first);
+  if (!SEntry)
+    return C_User;
+
+  const SrcMgr::FileInfo &FI = SEntry->getFile();
+
+  // If there are no #line directives in this file, just return the whole-file
+  // state.
+  if (!FI.hasLineDirectives())
+    return FI.getFileCharacteristic();
+
+  assert(LineTable && "Can't have linetable entries without a LineTable!");
+  // See if there is a #line directive before the location.
+  const LineEntry *Entry =
+    LineTable->FindNearestLineEntry(LocInfo.first, LocInfo.second);
+
+  // If this is before the first line marker, use the file characteristic.
+  if (!Entry)
+    return FI.getFileCharacteristic();
+
+  return Entry->FileKind;
+}
+
+/// Return the filename or buffer identifier of the buffer the location is in.
+/// Note that this name does not respect \#line directives.  Use getPresumedLoc
+/// for normal clients.
+StringRef SourceManager::getBufferName(SourceLocation Loc,
+                                       bool *Invalid) const {
+  if (isInvalid(Loc, Invalid)) return "<invalid loc>";
+
+  auto B = getBufferOrNone(getFileID(Loc));
+  if (Invalid)
+    *Invalid = !B;
+  return B ? B->getBufferIdentifier() : "<invalid buffer>";
+}
+
+/// getPresumedLoc - This method returns the "presumed" location of a
+/// SourceLocation specifies.  A "presumed location" can be modified by \#line
+/// or GNU line marker directives.  This provides a view on the data that a
+/// user should see in diagnostics, for example.
+///
+/// Note that a presumed location is always given as the expansion point of an
+/// expansion location, not at the spelling location.
+PresumedLoc SourceManager::getPresumedLoc(SourceLocation Loc,
+                                          bool UseLineDirectives) const {
+  if (Loc.isInvalid()) return PresumedLoc();
+
+  // Presumed locations are always for expansion points.
+  std::pair<FileID, unsigned> LocInfo = getDecomposedExpansionLoc(Loc);
+
+  bool Invalid = false;
+  const SLocEntry &Entry = getSLocEntry(LocInfo.first, &Invalid);
+  if (Invalid || !Entry.isFile())
+    return PresumedLoc();
+
+  const SrcMgr::FileInfo &FI = Entry.getFile();
+  const SrcMgr::ContentCache *C = &FI.getContentCache();
+
+  // To get the source name, first consult the FileEntry (if one exists)
+  // before the MemBuffer as this will avoid unnecessarily paging in the
+  // MemBuffer.
+  FileID FID = LocInfo.first;
+  StringRef Filename;
+  if (C->OrigEntry)
+    Filename = C->OrigEntry->getName();
+  else if (auto Buffer = C->getBufferOrNone(Diag, getFileManager()))
+    Filename = Buffer->getBufferIdentifier();
+
+  unsigned LineNo = getLineNumber(LocInfo.first, LocInfo.second, &Invalid);
+  if (Invalid)
+    return PresumedLoc();
+  unsigned ColNo  = getColumnNumber(LocInfo.first, LocInfo.second, &Invalid);
+  if (Invalid)
+    return PresumedLoc();
+
+  SourceLocation IncludeLoc = FI.getIncludeLoc();
+
+  // If we have #line directives in this file, update and overwrite the physical
+  // location info if appropriate.
+  if (UseLineDirectives && FI.hasLineDirectives()) {
+    assert(LineTable && "Can't have linetable entries without a LineTable!");
+    // See if there is a #line directive before this.  If so, get it.
+    if (const LineEntry *Entry =
+          LineTable->FindNearestLineEntry(LocInfo.first, LocInfo.second)) {
+      // If the LineEntry indicates a filename, use it.
+      if (Entry->FilenameID != -1) {
+        Filename = LineTable->getFilename(Entry->FilenameID);
+        // The contents of files referenced by #line are not in the
+        // SourceManager
+        FID = FileID::get(0);
+      }
+
+      // Use the line number specified by the LineEntry.  This line number may
+      // be multiple lines down from the line entry.  Add the difference in
+      // physical line numbers from the query point and the line marker to the
+      // total.
+      unsigned MarkerLineNo = getLineNumber(LocInfo.first, Entry->FileOffset);
+      LineNo = Entry->LineNo + (LineNo-MarkerLineNo-1);
+
+      // Note that column numbers are not molested by line markers.
+
+      // Handle virtual #include manipulation.
+      if (Entry->IncludeOffset) {
+        IncludeLoc = getLocForStartOfFile(LocInfo.first);
+        IncludeLoc = IncludeLoc.getLocWithOffset(Entry->IncludeOffset);
+      }
+    }
+  }
+
+  return PresumedLoc(Filename.data(), FID, LineNo, ColNo, IncludeLoc);
+}
+
+/// Returns whether the PresumedLoc for a given SourceLocation is
+/// in the main file.
+///
+/// This computes the "presumed" location for a SourceLocation, then checks
+/// whether it came from a file other than the main file. This is different
+/// from isWrittenInMainFile() because it takes line marker directives into
+/// account.
+bool SourceManager::isInMainFile(SourceLocation Loc) const {
+  if (Loc.isInvalid()) return false;
+
+  // Presumed locations are always for expansion points.
+  std::pair<FileID, unsigned> LocInfo = getDecomposedExpansionLoc(Loc);
+
+  const SLocEntry *Entry = getSLocEntryForFile(LocInfo.first);
+  if (!Entry)
+    return false;
+
+  const SrcMgr::FileInfo &FI = Entry->getFile();
+
+  // Check if there is a line directive for this location.
+  if (FI.hasLineDirectives())
+    if (const LineEntry *Entry =
+            LineTable->FindNearestLineEntry(LocInfo.first, LocInfo.second))
+      if (Entry->IncludeOffset)
+        return false;
+
+  return FI.getIncludeLoc().isInvalid();
+}
+
+/// The size of the SLocEntry that \p FID represents.
+unsigned SourceManager::getFileIDSize(FileID FID) const {
+  bool Invalid = false;
+  const SrcMgr::SLocEntry &Entry = getSLocEntry(FID, &Invalid);
+  if (Invalid)
+    return 0;
+
+  int ID = FID.ID;
+  SourceLocation::UIntTy NextOffset;
+  if ((ID > 0 && unsigned(ID+1) == local_sloc_entry_size()))
+    NextOffset = getNextLocalOffset();
+  else if (ID+1 == -1)
+    NextOffset = MaxLoadedOffset;
+  else
+    NextOffset = getSLocEntry(FileID::get(ID+1)).getOffset();
+
+  return NextOffset - Entry.getOffset() - 1;
+}
+
+//===----------------------------------------------------------------------===//
+// Other miscellaneous methods.
+//===----------------------------------------------------------------------===//
+
+/// Get the source location for the given file:line:col triplet.
+///
+/// If the source file is included multiple times, the source location will
+/// be based upon an arbitrary inclusion.
+SourceLocation SourceManager::translateFileLineCol(const FileEntry *SourceFile,
+                                                  unsigned Line,
+                                                  unsigned Col) const {
+  assert(SourceFile && "Null source file!");
+  assert(Line && Col && "Line and column should start from 1!");
+
+  FileID FirstFID = translateFile(SourceFile);
+  return translateLineCol(FirstFID, Line, Col);
+}
+
+/// Get the FileID for the given file.
+///
+/// If the source file is included multiple times, the FileID will be the
+/// first inclusion.
+FileID SourceManager::translateFile(const FileEntry *SourceFile) const {
+  assert(SourceFile && "Null source file!");
+
+  // First, check the main file ID, since it is common to look for a
+  // location in the main file.
+  if (MainFileID.isValid()) {
+    bool Invalid = false;
+    const SLocEntry &MainSLoc = getSLocEntry(MainFileID, &Invalid);
+    if (Invalid)
+      return FileID();
+
+    if (MainSLoc.isFile()) {
+      if (MainSLoc.getFile().getContentCache().OrigEntry == SourceFile)
+        return MainFileID;
+    }
+  }
+
+  // The location we're looking for isn't in the main file; look
+  // through all of the local source locations.
+  for (unsigned I = 0, N = local_sloc_entry_size(); I != N; ++I) {
+    const SLocEntry &SLoc = getLocalSLocEntry(I);
+    if (SLoc.isFile() &&
+        SLoc.getFile().getContentCache().OrigEntry == SourceFile)
+      return FileID::get(I);
+  }
+
+  // If that still didn't help, try the modules.
+  for (unsigned I = 0, N = loaded_sloc_entry_size(); I != N; ++I) {
+    const SLocEntry &SLoc = getLoadedSLocEntry(I);
+    if (SLoc.isFile() &&
+        SLoc.getFile().getContentCache().OrigEntry == SourceFile)
+      return FileID::get(-int(I) - 2);
+  }
+
+  return FileID();
+}
+
+/// Get the source location in \arg FID for the given line:col.
+/// Returns null location if \arg FID is not a file SLocEntry.
+SourceLocation SourceManager::translateLineCol(FileID FID,
+                                               unsigned Line,
+                                               unsigned Col) const {
+  // Lines are used as a one-based index into a zero-based array. This assert
+  // checks for possible buffer underruns.
+  assert(Line && Col && "Line and column should start from 1!");
+
+  if (FID.isInvalid())
+    return SourceLocation();
+
+  bool Invalid = false;
+  const SLocEntry &Entry = getSLocEntry(FID, &Invalid);
+  if (Invalid)
+    return SourceLocation();
+
+  if (!Entry.isFile())
+    return SourceLocation();
+
+  SourceLocation FileLoc = SourceLocation::getFileLoc(Entry.getOffset());
+
+  if (Line == 1 && Col == 1)
+    return FileLoc;
+
+  const ContentCache *Content = &Entry.getFile().getContentCache();
+
+  // If this is the first use of line information for this buffer, compute the
+  // SourceLineCache for it on demand.
+  llvm::Optional<llvm::MemoryBufferRef> Buffer =
+      Content->getBufferOrNone(Diag, getFileManager());
+  if (!Buffer)
+    return SourceLocation();
+  if (!Content->SourceLineCache)
+    Content->SourceLineCache =
+        LineOffsetMapping::get(*Buffer, ContentCacheAlloc);
+
+  if (Line > Content->SourceLineCache.size()) {
+    unsigned Size = Buffer->getBufferSize();
+    if (Size > 0)
+      --Size;
+    return FileLoc.getLocWithOffset(Size);
+  }
+
+  unsigned FilePos = Content->SourceLineCache[Line - 1];
+  const char *Buf = Buffer->getBufferStart() + FilePos;
+  unsigned BufLength = Buffer->getBufferSize() - FilePos;
+  if (BufLength == 0)
+    return FileLoc.getLocWithOffset(FilePos);
+
+  unsigned i = 0;
+
+  // Check that the given column is valid.
+  while (i < BufLength-1 && i < Col-1 && Buf[i] != '\n' && Buf[i] != '\r')
+    ++i;
+  return FileLoc.getLocWithOffset(FilePos + i);
+}
+
+/// Compute a map of macro argument chunks to their expanded source
+/// location. Chunks that are not part of a macro argument will map to an
+/// invalid source location. e.g. if a file contains one macro argument at
+/// offset 100 with length 10, this is how the map will be formed:
+///     0   -> SourceLocation()
+///     100 -> Expanded macro arg location
+///     110 -> SourceLocation()
+void SourceManager::computeMacroArgsCache(MacroArgsMap &MacroArgsCache,
+                                          FileID FID) const {
+  assert(FID.isValid());
+
+  // Initially no macro argument chunk is present.
+  MacroArgsCache.insert(std::make_pair(0, SourceLocation()));
+
+  int ID = FID.ID;
+  while (true) {
+    ++ID;
+    // Stop if there are no more FileIDs to check.
+    if (ID > 0) {
+      if (unsigned(ID) >= local_sloc_entry_size())
+        return;
+    } else if (ID == -1) {
+      return;
+    }
+
+    bool Invalid = false;
+    const SrcMgr::SLocEntry &Entry = getSLocEntryByID(ID, &Invalid);
+    if (Invalid)
+      return;
+    if (Entry.isFile()) {
+      auto& File = Entry.getFile();
+      if (File.getFileCharacteristic() == C_User_ModuleMap ||
+          File.getFileCharacteristic() == C_System_ModuleMap)
+        continue;
+
+      SourceLocation IncludeLoc = File.getIncludeLoc();
+      bool IncludedInFID =
+          (IncludeLoc.isValid() && isInFileID(IncludeLoc, FID)) ||
+          // Predefined header doesn't have a valid include location in main
+          // file, but any files created by it should still be skipped when
+          // computing macro args expanded in the main file.
+          (FID == MainFileID && Entry.getFile().getName() == "<built-in>");
+      if (IncludedInFID) {
+        // Skip the files/macros of the #include'd file, we only care about
+        // macros that lexed macro arguments from our file.
+        if (Entry.getFile().NumCreatedFIDs)
+          ID += Entry.getFile().NumCreatedFIDs - 1 /*because of next ++ID*/;
+        continue;
+      } else if (IncludeLoc.isValid()) {
+        // If file was included but not from FID, there is no more files/macros
+        // that may be "contained" in this file.
+        return;
+      }
+      continue;
+    }
+
+    const ExpansionInfo &ExpInfo = Entry.getExpansion();
+
+    if (ExpInfo.getExpansionLocStart().isFileID()) {
+      if (!isInFileID(ExpInfo.getExpansionLocStart(), FID))
+        return; // No more files/macros that may be "contained" in this file.
+    }
+
+    if (!ExpInfo.isMacroArgExpansion())
+      continue;
+
+    associateFileChunkWithMacroArgExp(MacroArgsCache, FID,
+                                 ExpInfo.getSpellingLoc(),
+                                 SourceLocation::getMacroLoc(Entry.getOffset()),
+                                 getFileIDSize(FileID::get(ID)));
+  }
+}
+
+void SourceManager::associateFileChunkWithMacroArgExp(
+                                         MacroArgsMap &MacroArgsCache,
+                                         FileID FID,
+                                         SourceLocation SpellLoc,
+                                         SourceLocation ExpansionLoc,
+                                         unsigned ExpansionLength) const {
+  if (!SpellLoc.isFileID()) {
+    SourceLocation::UIntTy SpellBeginOffs = SpellLoc.getOffset();
+    SourceLocation::UIntTy SpellEndOffs = SpellBeginOffs + ExpansionLength;
+
+    // The spelling range for this macro argument expansion can span multiple
+    // consecutive FileID entries. Go through each entry contained in the
+    // spelling range and if one is itself a macro argument expansion, recurse
+    // and associate the file chunk that it represents.
+
+    FileID SpellFID; // Current FileID in the spelling range.
+    unsigned SpellRelativeOffs;
+    std::tie(SpellFID, SpellRelativeOffs) = getDecomposedLoc(SpellLoc);
+    while (true) {
+      const SLocEntry &Entry = getSLocEntry(SpellFID);
+      SourceLocation::UIntTy SpellFIDBeginOffs = Entry.getOffset();
+      unsigned SpellFIDSize = getFileIDSize(SpellFID);
+      SourceLocation::UIntTy SpellFIDEndOffs = SpellFIDBeginOffs + SpellFIDSize;
+      const ExpansionInfo &Info = Entry.getExpansion();
+      if (Info.isMacroArgExpansion()) {
+        unsigned CurrSpellLength;
+        if (SpellFIDEndOffs < SpellEndOffs)
+          CurrSpellLength = SpellFIDSize - SpellRelativeOffs;
+        else
+          CurrSpellLength = ExpansionLength;
+        associateFileChunkWithMacroArgExp(MacroArgsCache, FID,
+                      Info.getSpellingLoc().getLocWithOffset(SpellRelativeOffs),
+                      ExpansionLoc, CurrSpellLength);
+      }
+
+      if (SpellFIDEndOffs >= SpellEndOffs)
+        return; // we covered all FileID entries in the spelling range.
+
+      // Move to the next FileID entry in the spelling range.
+      unsigned advance = SpellFIDSize - SpellRelativeOffs + 1;
+      ExpansionLoc = ExpansionLoc.getLocWithOffset(advance);
+      ExpansionLength -= advance;
+      ++SpellFID.ID;
+      SpellRelativeOffs = 0;
+    }
+  }
+
+  assert(SpellLoc.isFileID());
+
+  unsigned BeginOffs;
+  if (!isInFileID(SpellLoc, FID, &BeginOffs))
+    return;
+
+  unsigned EndOffs = BeginOffs + ExpansionLength;
+
+  // Add a new chunk for this macro argument. A previous macro argument chunk
+  // may have been lexed again, so e.g. if the map is
+  //     0   -> SourceLocation()
+  //     100 -> Expanded loc #1
+  //     110 -> SourceLocation()
+  // and we found a new macro FileID that lexed from offset 105 with length 3,
+  // the new map will be:
+  //     0   -> SourceLocation()
+  //     100 -> Expanded loc #1
+  //     105 -> Expanded loc #2
+  //     108 -> Expanded loc #1
+  //     110 -> SourceLocation()
+  //
+  // Since re-lexed macro chunks will always be the same size or less of
+  // previous chunks, we only need to find where the ending of the new macro
+  // chunk is mapped to and update the map with new begin/end mappings.
+
+  MacroArgsMap::iterator I = MacroArgsCache.upper_bound(EndOffs);
+  --I;
+  SourceLocation EndOffsMappedLoc = I->second;
+  MacroArgsCache[BeginOffs] = ExpansionLoc;
+  MacroArgsCache[EndOffs] = EndOffsMappedLoc;
+}
+
+/// If \arg Loc points inside a function macro argument, the returned
+/// location will be the macro location in which the argument was expanded.
+/// If a macro argument is used multiple times, the expanded location will
+/// be at the first expansion of the argument.
+/// e.g.
+///   MY_MACRO(foo);
+///             ^
+/// Passing a file location pointing at 'foo', will yield a macro location
+/// where 'foo' was expanded into.
+SourceLocation
+SourceManager::getMacroArgExpandedLocation(SourceLocation Loc) const {
+  if (Loc.isInvalid() || !Loc.isFileID())
+    return Loc;
+
+  FileID FID;
+  unsigned Offset;
+  std::tie(FID, Offset) = getDecomposedLoc(Loc);
+  if (FID.isInvalid())
+    return Loc;
+
+  std::unique_ptr<MacroArgsMap> &MacroArgsCache = MacroArgsCacheMap[FID];
+  if (!MacroArgsCache) {
+    MacroArgsCache = std::make_unique<MacroArgsMap>();
+    computeMacroArgsCache(*MacroArgsCache, FID);
+  }
+
+  assert(!MacroArgsCache->empty());
+  MacroArgsMap::iterator I = MacroArgsCache->upper_bound(Offset);
+  // In case every element in MacroArgsCache is greater than Offset we can't
+  // decrement the iterator.
+  if (I == MacroArgsCache->begin())
+    return Loc;
+
+  --I;
+
+  SourceLocation::UIntTy MacroArgBeginOffs = I->first;
+  SourceLocation MacroArgExpandedLoc = I->second;
+  if (MacroArgExpandedLoc.isValid())
+    return MacroArgExpandedLoc.getLocWithOffset(Offset - MacroArgBeginOffs);
+
+  return Loc;
+}
+
+std::pair<FileID, unsigned>
+SourceManager::getDecomposedIncludedLoc(FileID FID) const {
+  if (FID.isInvalid())
+    return std::make_pair(FileID(), 0);
+
+  // Uses IncludedLocMap to retrieve/cache the decomposed loc.
+
+  using DecompTy = std::pair<FileID, unsigned>;
+  auto InsertOp = IncludedLocMap.try_emplace(FID);
+  DecompTy &DecompLoc = InsertOp.first->second;
+  if (!InsertOp.second)
+    return DecompLoc; // already in map.
+
+  SourceLocation UpperLoc;
+  bool Invalid = false;
+  const SrcMgr::SLocEntry &Entry = getSLocEntry(FID, &Invalid);
+  if (!Invalid) {
+    if (Entry.isExpansion())
+      UpperLoc = Entry.getExpansion().getExpansionLocStart();
+    else
+      UpperLoc = Entry.getFile().getIncludeLoc();
+  }
+
+  if (UpperLoc.isValid())
+    DecompLoc = getDecomposedLoc(UpperLoc);
+
+  return DecompLoc;
+}
+
+/// Given a decomposed source location, move it up the include/expansion stack
+/// to the parent source location.  If this is possible, return the decomposed
+/// version of the parent in Loc and return false.  If Loc is the top-level
+/// entry, return true and don't modify it.
+static bool MoveUpIncludeHierarchy(std::pair<FileID, unsigned> &Loc,
+                                   const SourceManager &SM) {
+  std::pair<FileID, unsigned> UpperLoc = SM.getDecomposedIncludedLoc(Loc.first);
+  if (UpperLoc.first.isInvalid())
+    return true; // We reached the top.
+
+  Loc = UpperLoc;
+  return false;
+}
+
+/// Return the cache entry for comparing the given file IDs
+/// for isBeforeInTranslationUnit.
+InBeforeInTUCacheEntry &SourceManager::getInBeforeInTUCache(FileID LFID,
+                                                            FileID RFID) const {
+  // This is a magic number for limiting the cache size.  It was experimentally
+  // derived from a small Objective-C project (where the cache filled
+  // out to ~250 items).  We can make it larger if necessary.
+  enum { MagicCacheSize = 300 };
+  IsBeforeInTUCacheKey Key(LFID, RFID);
+
+  // If the cache size isn't too large, do a lookup and if necessary default
+  // construct an entry.  We can then return it to the caller for direct
+  // use.  When they update the value, the cache will get automatically
+  // updated as well.
+  if (IBTUCache.size() < MagicCacheSize)
+    return IBTUCache[Key];
+
+  // Otherwise, do a lookup that will not construct a new value.
+  InBeforeInTUCache::iterator I = IBTUCache.find(Key);
+  if (I != IBTUCache.end())
+    return I->second;
+
+  // Fall back to the overflow value.
+  return IBTUCacheOverflow;
+}
+
+/// Determines the order of 2 source locations in the translation unit.
+///
+/// \returns true if LHS source location comes before RHS, false otherwise.
+bool SourceManager::isBeforeInTranslationUnit(SourceLocation LHS,
+                                              SourceLocation RHS) const {
+  assert(LHS.isValid() && RHS.isValid() && "Passed invalid source location!");
+  if (LHS == RHS)
+    return false;
+
+  std::pair<FileID, unsigned> LOffs = getDecomposedLoc(LHS);
+  std::pair<FileID, unsigned> ROffs = getDecomposedLoc(RHS);
+
+  // getDecomposedLoc may have failed to return a valid FileID because, e.g. it
+  // is a serialized one referring to a file that was removed after we loaded
+  // the PCH.
+  if (LOffs.first.isInvalid() || ROffs.first.isInvalid())
+    return LOffs.first.isInvalid() && !ROffs.first.isInvalid();
+
+  std::pair<bool, bool> InSameTU = isInTheSameTranslationUnit(LOffs, ROffs);
+  if (InSameTU.first)
+    return InSameTU.second;
+
+  // If we arrived here, the location is either in a built-ins buffer or
+  // associated with global inline asm. PR5662 and PR22576 are examples.
+
+  StringRef LB = getBufferOrFake(LOffs.first).getBufferIdentifier();
+  StringRef RB = getBufferOrFake(ROffs.first).getBufferIdentifier();
+  bool LIsBuiltins = LB == "<built-in>";
+  bool RIsBuiltins = RB == "<built-in>";
+  // Sort built-in before non-built-in.
+  if (LIsBuiltins || RIsBuiltins) {
+    if (LIsBuiltins != RIsBuiltins)
+      return LIsBuiltins;
+    // Both are in built-in buffers, but from different files. We just claim that
+    // lower IDs come first.
+    return LOffs.first < ROffs.first;
+  }
+  bool LIsAsm = LB == "<inline asm>";
+  bool RIsAsm = RB == "<inline asm>";
+  // Sort assembler after built-ins, but before the rest.
+  if (LIsAsm || RIsAsm) {
+    if (LIsAsm != RIsAsm)
+      return RIsAsm;
+    assert(LOffs.first == ROffs.first);
+    return false;
+  }
+  bool LIsScratch = LB == "<scratch space>";
+  bool RIsScratch = RB == "<scratch space>";
+  // Sort scratch after inline asm, but before the rest.
+  if (LIsScratch || RIsScratch) {
+    if (LIsScratch != RIsScratch)
+      return LIsScratch;
+    return LOffs.second < ROffs.second;
+  }
+  llvm_unreachable("Unsortable locations found");
+}
+
+std::pair<bool, bool> SourceManager::isInTheSameTranslationUnit(
+    std::pair<FileID, unsigned> &LOffs,
+    std::pair<FileID, unsigned> &ROffs) const {
+  // If the source locations are in the same file, just compare offsets.
+  if (LOffs.first == ROffs.first)
+    return std::make_pair(true, LOffs.second < ROffs.second);
+
+  // If we are comparing a source location with multiple locations in the same
+  // file, we get a big win by caching the result.
+  InBeforeInTUCacheEntry &IsBeforeInTUCache =
+    getInBeforeInTUCache(LOffs.first, ROffs.first);
+
+  // If we are comparing a source location with multiple locations in the same
+  // file, we get a big win by caching the result.
+  if (IsBeforeInTUCache.isCacheValid(LOffs.first, ROffs.first))
+    return std::make_pair(
+        true, IsBeforeInTUCache.getCachedResult(LOffs.second, ROffs.second));
+
+  // Okay, we missed in the cache, start updating the cache for this query.
+  IsBeforeInTUCache.setQueryFIDs(LOffs.first, ROffs.first,
+                          /*isLFIDBeforeRFID=*/LOffs.first.ID < ROffs.first.ID);
+
+  // We need to find the common ancestor. The only way of doing this is to
+  // build the complete include chain for one and then walking up the chain
+  // of the other looking for a match.
+  // We use a map from FileID to Offset to store the chain. Easier than writing
+  // a custom set hash info that only depends on the first part of a pair.
+  using LocSet = llvm::SmallDenseMap<FileID, unsigned, 16>;
+  LocSet LChain;
+  do {
+    LChain.insert(LOffs);
+    // We catch the case where LOffs is in a file included by ROffs and
+    // quit early. The other way round unfortunately remains suboptimal.
+  } while (LOffs.first != ROffs.first && !MoveUpIncludeHierarchy(LOffs, *this));
+  LocSet::iterator I;
+  while((I = LChain.find(ROffs.first)) == LChain.end()) {
+    if (MoveUpIncludeHierarchy(ROffs, *this))
+      break; // Met at topmost file.
+  }
+  if (I != LChain.end())
+    LOffs = *I;
+
+  // If we exited because we found a nearest common ancestor, compare the
+  // locations within the common file and cache them.
+  if (LOffs.first == ROffs.first) {
+    IsBeforeInTUCache.setCommonLoc(LOffs.first, LOffs.second, ROffs.second);
+    return std::make_pair(
+        true, IsBeforeInTUCache.getCachedResult(LOffs.second, ROffs.second));
+  }
+  // Clear the lookup cache, it depends on a common location.
+  IsBeforeInTUCache.clear();
+  return std::make_pair(false, false);
+}
+
+void SourceManager::PrintStats() const {
+  llvm::errs() << "\n*** Source Manager Stats:\n";
+  llvm::errs() << FileInfos.size() << " files mapped, " << MemBufferInfos.size()
+               << " mem buffers mapped.\n";
+  llvm::errs() << LocalSLocEntryTable.size() << " local SLocEntry's allocated ("
+               << llvm::capacity_in_bytes(LocalSLocEntryTable)
+               << " bytes of capacity), "
+               << NextLocalOffset << "B of Sloc address space used.\n";
+  llvm::errs() << LoadedSLocEntryTable.size()
+               << " loaded SLocEntries allocated, "
+               << MaxLoadedOffset - CurrentLoadedOffset
+               << "B of Sloc address space used.\n";
+
+  unsigned NumLineNumsComputed = 0;
+  unsigned NumFileBytesMapped = 0;
+  for (fileinfo_iterator I = fileinfo_begin(), E = fileinfo_end(); I != E; ++I){
+    NumLineNumsComputed += bool(I->second->SourceLineCache);
+    NumFileBytesMapped  += I->second->getSizeBytesMapped();
+  }
+  unsigned NumMacroArgsComputed = MacroArgsCacheMap.size();
+
+  llvm::errs() << NumFileBytesMapped << " bytes of files mapped, "
+               << NumLineNumsComputed << " files with line #'s computed, "
+               << NumMacroArgsComputed << " files with macro args computed.\n";
+  llvm::errs() << "FileID scans: " << NumLinearScans << " linear, "
+               << NumBinaryProbes << " binary.\n";
+}
+
+LLVM_DUMP_METHOD void SourceManager::dump() const {
+  llvm::raw_ostream &out = llvm::errs();
+
+  auto DumpSLocEntry = [&](int ID, const SrcMgr::SLocEntry &Entry,
+                           llvm::Optional<SourceLocation::UIntTy> NextStart) {
+    out << "SLocEntry <FileID " << ID << "> " << (Entry.isFile() ? "file" : "expansion")
+        << " <SourceLocation " << Entry.getOffset() << ":";
+    if (NextStart)
+      out << *NextStart << ">\n";
+    else
+      out << "???\?>\n";
+    if (Entry.isFile()) {
+      auto &FI = Entry.getFile();
+      if (FI.NumCreatedFIDs)
+        out << "  covers <FileID " << ID << ":" << int(ID + FI.NumCreatedFIDs)
+            << ">\n";
+      if (FI.getIncludeLoc().isValid())
+        out << "  included from " << FI.getIncludeLoc().getOffset() << "\n";
+      auto &CC = FI.getContentCache();
+      out << "  for " << (CC.OrigEntry ? CC.OrigEntry->getName() : "<none>")
+          << "\n";
+      if (CC.BufferOverridden)
+        out << "  contents overridden\n";
+      if (CC.ContentsEntry != CC.OrigEntry) {
+        out << "  contents from "
+            << (CC.ContentsEntry ? CC.ContentsEntry->getName() : "<none>")
+            << "\n";
+      }
+    } else {
+      auto &EI = Entry.getExpansion();
+      out << "  spelling from " << EI.getSpellingLoc().getOffset() << "\n";
+      out << "  macro " << (EI.isMacroArgExpansion() ? "arg" : "body")
+          << " range <" << EI.getExpansionLocStart().getOffset() << ":"
+          << EI.getExpansionLocEnd().getOffset() << ">\n";
+    }
+  };
+
+  // Dump local SLocEntries.
+  for (unsigned ID = 0, NumIDs = LocalSLocEntryTable.size(); ID != NumIDs; ++ID) {
+    DumpSLocEntry(ID, LocalSLocEntryTable[ID],
+                  ID == NumIDs - 1 ? NextLocalOffset
+                                   : LocalSLocEntryTable[ID + 1].getOffset());
+  }
+  // Dump loaded SLocEntries.
+  llvm::Optional<SourceLocation::UIntTy> NextStart;
+  for (unsigned Index = 0; Index != LoadedSLocEntryTable.size(); ++Index) {
+    int ID = -(int)Index - 2;
+    if (SLocEntryLoaded[Index]) {
+      DumpSLocEntry(ID, LoadedSLocEntryTable[Index], NextStart);
+      NextStart = LoadedSLocEntryTable[Index].getOffset();
+    } else {
+      NextStart = None;
+    }
+  }
+}
+
+ExternalSLocEntrySource::~ExternalSLocEntrySource() = default;
+
+/// Return the amount of memory used by memory buffers, breaking down
+/// by heap-backed versus mmap'ed memory.
+SourceManager::MemoryBufferSizes SourceManager::getMemoryBufferSizes() const {
+  size_t malloc_bytes = 0;
+  size_t mmap_bytes = 0;
+
+  for (unsigned i = 0, e = MemBufferInfos.size(); i != e; ++i)
+    if (size_t sized_mapped = MemBufferInfos[i]->getSizeBytesMapped())
+      switch (MemBufferInfos[i]->getMemoryBufferKind()) {
+        case llvm::MemoryBuffer::MemoryBuffer_MMap:
+          mmap_bytes += sized_mapped;
+          break;
+        case llvm::MemoryBuffer::MemoryBuffer_Malloc:
+          malloc_bytes += sized_mapped;
+          break;
+      }
+
+  return MemoryBufferSizes(malloc_bytes, mmap_bytes);
+}
+
+size_t SourceManager::getDataStructureSizes() const {
+  size_t size = llvm::capacity_in_bytes(MemBufferInfos)
+    + llvm::capacity_in_bytes(LocalSLocEntryTable)
+    + llvm::capacity_in_bytes(LoadedSLocEntryTable)
+    + llvm::capacity_in_bytes(SLocEntryLoaded)
+    + llvm::capacity_in_bytes(FileInfos);
+
+  if (OverriddenFilesInfo)
+    size += llvm::capacity_in_bytes(OverriddenFilesInfo->OverriddenFiles);
+
+  return size;
+}
+
+SourceManagerForFile::SourceManagerForFile(StringRef FileName,
+                                           StringRef Content) {
+  // This is referenced by `FileMgr` and will be released by `FileMgr` when it
+  // is deleted.
+  IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem> InMemoryFileSystem(
+      new llvm::vfs::InMemoryFileSystem);
+  InMemoryFileSystem->addFile(
+      FileName, 0,
+      llvm::MemoryBuffer::getMemBuffer(Content, FileName,
+                                       /*RequiresNullTerminator=*/false));
+  // This is passed to `SM` as reference, so the pointer has to be referenced
+  // in `Environment` so that `FileMgr` can out-live this function scope.
+  FileMgr =
+      std::make_unique<FileManager>(FileSystemOptions(), InMemoryFileSystem);
+  // This is passed to `SM` as reference, so the pointer has to be referenced
+  // by `Environment` due to the same reason above.
+  Diagnostics = std::make_unique<DiagnosticsEngine>(
+      IntrusiveRefCntPtr<DiagnosticIDs>(new DiagnosticIDs),
+      new DiagnosticOptions);
+  SourceMgr = std::make_unique<SourceManager>(*Diagnostics, *FileMgr);
+  FileID ID = SourceMgr->createFileID(*FileMgr->getFile(FileName),
+                                      SourceLocation(), clang::SrcMgr::C_User);
+  assert(ID.isValid());
+  SourceMgr->setMainFileID(ID);
+}