text: //===- 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/Optional.h"
  #include "llvm/ADT/None.h"
  #include "llvm/ADT/STLExtras.h"
  #include "llvm/ADT/SmallVector.h"
  #include "llvm/ADT/StringSwitch.h"
  #include "llvm/ADT/StringRef.h"
  #include "llvm/Support/Allocator.h"
  #include "llvm/Support/Capacity.h"
  #include "llvm/Support/Compiler.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
  //===----------------------------------------------------------------------===//
  
  ContentCache::~ContentCache() {
    if (shouldFreeBuffer())
      delete Buffer.getPointer();
  }
  
  /// 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.getPointer() ? Buffer.getPointer()->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 {
    assert(Buffer.getPointer());
  
    // Should be unreachable, but keep for sanity.
    if (!Buffer.getPointer())
      return llvm::MemoryBuffer::MemoryBuffer_Malloc;
  
    const llvm::MemoryBuffer *buf = Buffer.getPointer();
    return buf->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.getPointer() ? (unsigned) Buffer.getPointer()->getBufferSize()
                               : (unsigned) ContentsEntry->getSize();
  }
  
  void ContentCache::replaceBuffer(const llvm::MemoryBuffer *B, bool DoNotFree) {
    if (B && B == Buffer.getPointer()) {
      assert(0 && "Replacing with the same buffer");
      Buffer.setInt(DoNotFree? DoNotFreeFlag : 0);
      return;
    }
  
    if (shouldFreeBuffer())
      delete Buffer.getPointer();
    Buffer.setPointer(B);
    Buffer.setInt((B && DoNotFree) ? DoNotFreeFlag : 0);
  }
  
  const llvm::MemoryBuffer *ContentCache::getBuffer(DiagnosticsEngine &Diag,
                                                    FileManager &FM,
                                                    SourceLocation Loc,
                                                    bool *Invalid) const {
    // Lazily create the Buffer for ContentCaches that wrap files.  If we already
    // computed it, just return what we have.
    if (Buffer.getPointer() || !ContentsEntry) {
      if (Invalid)
        *Invalid = isBufferInvalid();
  
      return Buffer.getPointer();
    }
  
    // 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.
    if ((uint64_t)ContentsEntry->getSize() >=
        std::numeric_limits<unsigned>::max()) {
      // We can't make a memory buffer of the required size, so just make a small
      // one. We should never hit a situation where we've already parsed to a
      // later offset of the file, so it shouldn't matter that the buffer is
      // smaller than the file.
      Buffer.setPointer(
          llvm::MemoryBuffer::getMemBuffer("", ContentsEntry->getName())
              .release());
      if (Diag.isDiagnosticInFlight())
        Diag.SetDelayedDiagnostic(diag::err_file_too_large,
                                  ContentsEntry->getName());
      else
        Diag.Report(Loc, diag::err_file_too_large)
          << ContentsEntry->getName();
  
      Buffer.setInt(Buffer.getInt() | InvalidFlag);
      if (Invalid) *Invalid = true;
      return Buffer.getPointer();
    }
  
    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.
    //
    // FIXME: This is definitely not ideal, but our immediate clients can't
    // currently handle returning a null entry here. Ideally we should detect
    // that we are in an inconsistent situation and error out as quickly as
    // possible.
    if (!BufferOrError) {
      StringRef FillStr("<<<MISSING SOURCE FILE>>>\n");
      auto BackupBuffer = llvm::WritableMemoryBuffer::getNewUninitMemBuffer(
          ContentsEntry->getSize(), "<invalid>");
      char *Ptr = BackupBuffer->getBufferStart();
      for (unsigned i = 0, e = ContentsEntry->getSize(); i != e; ++i)
        Ptr[i] = FillStr[i % FillStr.size()];
      Buffer.setPointer(BackupBuffer.release());
  
      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();
  
      Buffer.setInt(Buffer.getInt() | InvalidFlag);
  
      if (Invalid) *Invalid = true;
      return Buffer.getPointer();
    }
  
    Buffer.setPointer(BufferOrError->release());
  
    // Check that the file's size is the same as in the file entry (which may
    // have come from a stat cache).
    if (getRawBuffer()->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();
  
      Buffer.setInt(Buffer.getInt() | InvalidFlag);
      if (Invalid) *Invalid = true;
      return Buffer.getPointer();
    }
  
    // 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.getPointer()->getBuffer();
    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);
  
    if (InvalidBOM) {
      Diag.Report(Loc, diag::err_unsupported_bom)
        << InvalidBOM << ContentsEntry->getName();
      Buffer.setInt(Buffer.getInt() | InvalidFlag);
    }
  
    if (Invalid)
      *Invalid = isBufferInvalid();
  
    return Buffer.getPointer();
  }
  
  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];
  
    // An unspecified FilenameID means use the last filename if available, or the
    // main source file otherwise.
    if (FilenameID == -1 && !Entries.empty())
      FilenameID = Entries.back().FilenameID;
  
    assert((Entries.empty() || Entries.back().FileOffset < Offset) &&
           "Adding line entries out of order!");
  
    unsigned IncludeOffset = 0;
    if (EntryExit == 0) {  // No #include stack change.
      IncludeOffset = Entries.empty() ? 0 : Entries.back().IncludeOffset;
    } else if (EntryExit == 1) {
      IncludeOffset = Offset-1;
    } else if (EntryExit == 2) {
      assert(!Entries.empty() && Entries.back().IncludeOffset &&
         "PPDirectives should have caught case when popping empty include stack");
  
      // Get the include loc of the last entries' include loc as our include loc.
      IncludeOffset = 0;
      if (const LineEntry *PrevEntry =
            FindNearestLineEntry(FID, Entries.back().IncludeOffset))
        IncludeOffset = PrevEntry->IncludeOffset;
    }
  
    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);
  }
  
  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->replaceBuffer(Cache->getRawBuffer(), /*DoNotFree*/true);
      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);
    }
  }
  
  /// getOrCreateContentCache - Create or return a cached ContentCache for the
  /// specified file.
  const ContentCache *
  SourceManager::getOrCreateContentCache(const FileEntry *FileEnt,
                                         bool isSystemFile) {
    assert(FileEnt && "Didn't specify a file entry to use?");
  
    // 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;
  
    return Entry;
  }
  
  /// Create a new ContentCache for the specified memory buffer.
  /// This does no caching.
  const ContentCache *
  SourceManager::createMemBufferContentCache(const llvm::MemoryBuffer *Buffer,
                                             bool DoNotFree) {
    // Add a new ContentCache to the MemBufferInfos list and return it.
    ContentCache *Entry = ContentCacheAlloc.Allocate<ContentCache>();
    new (Entry) ContentCache();
    MemBufferInfos.push_back(Entry);
    Entry->replaceBuffer(Buffer, DoNotFree);
    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.
        LoadedSLocEntryTable[Index] = SLocEntry::get(
            0, FileInfo::get(SourceLocation(), getFakeContentCacheForRecovery(),
                             SrcMgr::C_User, ""));
      }
    }
  
    return LoadedSLocEntryTable[Index];
  }
  
  std::pair<int, unsigned>
  SourceManager::AllocateLoadedSLocEntries(unsigned NumSLocEntries,
                                           unsigned 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::MemoryBuffer *SourceManager::getFakeBufferForRecovery() const {
    if (!FakeBufferForRecovery)
      FakeBufferForRecovery =
          llvm::MemoryBuffer::getMemBuffer("<<<INVALID BUFFER>>");
  
    return FakeBufferForRecovery.get();
  }
  
  /// As part of recovering from missing or changed content, produce a
  /// fake content cache.
  const SrcMgr::ContentCache *
  SourceManager::getFakeContentCacheForRecovery() const {
    if (!FakeContentCacheForRecovery) {
      FakeContentCacheForRecovery = std::make_unique<SrcMgr::ContentCache>();
      FakeContentCacheForRecovery->replaceBuffer(getFakeBufferForRecovery(),
                                                 /*DoNotFree=*/true);
    }
    return FakeContentCacheForRecovery.get();
  }
  
  /// 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.
  //===----------------------------------------------------------------------===//
  
  /// 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::createFileID(const ContentCache *File, StringRef Filename,
                                     SourceLocation IncludePos,
                                     SrcMgr::CharacteristicKind FileCharacter,
                                     int LoadedID, unsigned 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);
    }
    LocalSLocEntryTable.push_back(
        SLocEntry::get(NextLocalOffset,
                       FileInfo::get(IncludePos, File, FileCharacter, Filename)));
    unsigned FileSize = File->getSize();
    assert(NextLocalOffset + FileSize + 1 > NextLocalOffset &&
           NextLocalOffset + FileSize + 1 <= CurrentLoadedOffset &&
           "Ran out of source locations!");
    // 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,
                                    unsigned 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,
                                        unsigned 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));
  }
  
  const llvm::MemoryBuffer *
  SourceManager::getMemoryBufferForFile(const FileEntry *File, bool *Invalid) {
    const SrcMgr::ContentCache *IR = getOrCreateContentCache(File);
    assert(IR && "getOrCreateContentCache() cannot return NULL");
    return IR->getBuffer(Diag, getFileManager(), SourceLocation(), Invalid);
  }
  
  void SourceManager::overrideFileContents(const FileEntry *SourceFile,
                                           llvm::MemoryBuffer *Buffer,
                                           bool DoNotFree) {
    const SrcMgr::ContentCache *IR = getOrCreateContentCache(SourceFile);
    assert(IR && "getOrCreateContentCache() cannot return NULL");
  
    const_cast<SrcMgr::ContentCache *>(IR)->replaceBuffer(Buffer, DoNotFree);
    const_cast<SrcMgr::ContentCache *>(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;
  }
  
  void SourceManager::disableFileContentsOverride(const FileEntry *File) {
    if (!isFileOverridden(File))
      return;
  
    const SrcMgr::ContentCache *IR = getOrCreateContentCache(File);
    const_cast<SrcMgr::ContentCache *>(IR)->replaceBuffer(nullptr);
    const_cast<SrcMgr::ContentCache *>(IR)->ContentsEntry = IR->OrigEntry;
  
    assert(OverriddenFilesInfo);
    OverriddenFilesInfo->OverriddenFiles.erase(File);
    OverriddenFilesInfo->OverriddenFilesWithBuffer.erase(File);
  }
  
  void SourceManager::setFileIsTransient(const FileEntry *File) {
    const SrcMgr::ContentCache *CC = getOrCreateContentCache(File);
    const_cast<SrcMgr::ContentCache *>(CC)->IsTransient = true;
  }
  
  StringRef SourceManager::getBufferData(FileID FID, bool *Invalid) const {
    bool MyInvalid = false;
    const SLocEntry &SLoc = getSLocEntry(FID, &MyInvalid);
    if (!SLoc.isFile() || MyInvalid) {
      if (Invalid)
        *Invalid = true;
      return "<<<<<INVALID SOURCE LOCATION>>>>>";
    }
  
    const llvm::MemoryBuffer *Buf = SLoc.getFile().getContentCache()->getBuffer(
        Diag, getFileManager(), SourceLocation(), &MyInvalid);
    if (Invalid)
      *Invalid = MyInvalid;
  
    if (MyInvalid)
      return "<<<<<INVALID SOURCE LOCATION>>>>>";
  
    return Buf->getBuffer();
  }
  
  //===----------------------------------------------------------------------===//
  // 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(unsigned 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(unsigned 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()));
  
        // If this isn't an expansion, remember it.  We have good locality across
        // FileID lookups.
        if (!I->isExpansion())
          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) {
      bool Invalid = false;
      unsigned MiddleIndex = (GreaterIndex-LessIndex)/2+LessIndex;
      unsigned MidOffset = getLocalSLocEntry(MiddleIndex, &Invalid).getOffset();
      if (Invalid)
        return FileID::get(0);
  
      ++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.
      // FIXME: This could be made faster by using a function that's aware of
      // being in the local area.
      if (isOffsetInFileID(FileID::get(MiddleIndex), SLocOffset)) {
        FileID Res = FileID::get(MiddleIndex);
  
        // If this isn't a macro expansion, remember it.  We have good locality
        // across FileID lookups.
        if (!LocalSLocEntryTable[MiddleIndex].isExpansion())
          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(unsigned SLocOffset) const {
    // Sanity checking, otherwise a bug may lead to hanging in release build.
    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);
  
        if (!E.isExpansion())
          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) {
        // Sanity checking, otherwise a bug may lead to hanging in release build.
        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);
        if (!E.isExpansion())
          LastFileIDLookup = Res;
        NumBinaryProbes += NumProbes;
        return Res;
      }
  
      // Sanity checking, otherwise a bug may lead to hanging in release build.
      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);
  }
  
  /// 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>>>>";
    }
    const llvm::MemoryBuffer *Buffer =
        Entry.getFile().getContentCache()->getBuffer(
            Diag, getFileManager(), SourceLocation(), &CharDataInvalid);
    if (Invalid)
      *Invalid = CharDataInvalid;
    return Buffer->getBufferStart() + (CharDataInvalid? 0 : LocInfo.second);
  }
  
  /// 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 {
    bool MyInvalid = false;
    const llvm::MemoryBuffer *MemBuf = getBuffer(FID, &MyInvalid);
    if (Invalid)
      *Invalid = MyInvalid;
  
    if (MyInvalid)
      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 != nullptr &&
        LastLineNoResult < LastLineNoContentCache->NumLines) {
      unsigned *SourceLineCache = LastLineNoContentCache->SourceLineCache;
      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();
  }
  
  #ifdef __SSE2__
  #include <emmintrin.h>
  #endif
  
  static LLVM_ATTRIBUTE_NOINLINE void
  ComputeLineNumbers(DiagnosticsEngine &Diag, ContentCache *FI,
                     llvm::BumpPtrAllocator &Alloc,
                     const SourceManager &SM, bool &Invalid);
  static void ComputeLineNumbers(DiagnosticsEngine &Diag, ContentCache *FI,
                                 llvm::BumpPtrAllocator &Alloc,
                                 const SourceManager &SM, bool &Invalid) {
    // Note that calling 'getBuffer()' may lazily page in the file.
    const MemoryBuffer *Buffer =
        FI->getBuffer(Diag, SM.getFileManager(), SourceLocation(), &Invalid);
    if (Invalid)
      return;
  
    // 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();
    unsigned I = 0;
    while (true) {
      // Skip over the contents of the line.
      while (Buf[I] != '\n' && Buf[I] != '\r' && Buf[I] != '\0')
        ++I;
  
      if (Buf[I] == '\n' || Buf[I] == '\r') {
        // If this is \r\n, skip both characters.
        if (Buf[I] == '\r' && Buf[I+1] == '\n')
          ++I;
        ++I;
        LineOffsets.push_back(I);
      } else {
        // Otherwise, this is a NUL. If end of file, exit.
        if (Buf+I == End) break;
        ++I;
      }
    }
  
    // Copy the offsets into the FileInfo structure.
    FI->NumLines = LineOffsets.size();
    FI->SourceLineCache = Alloc.Allocate<unsigned>(LineOffsets.size());
    std::copy(LineOffsets.begin(), LineOffsets.end(), FI->SourceLineCache);
  }
  
  /// 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;
    }
  
    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 = const_cast<ContentCache*>(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) {
      bool MyInvalid = false;
      ComputeLineNumbers(Diag, Content, ContentCacheAlloc, *this, MyInvalid);
      if (Invalid)
        *Invalid = MyInvalid;
      if (MyInvalid)
        return 1;
    } 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.
    unsigned *SourceLineCache = Content->SourceLineCache;
    unsigned *SourceLineCacheStart = SourceLineCache;
    unsigned *SourceLineCacheEnd = SourceLineCache + Content->NumLines;
  
    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->NumLines)
          SourceLineCacheEnd = SourceLineCache+LastLineNoResult+1;
      }
    }
  
    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);
    bool Invalid = false;
    const SLocEntry &SEntry = getSLocEntry(LocInfo.first, &Invalid);
    if (Invalid || !SEntry.isFile())
      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>";
  
    return getBuffer(getFileID(Loc), Invalid)->getBufferIdentifier();
  }
  
  /// 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
      Filename = C->getBuffer(Diag, getFileManager())->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);
  
    bool Invalid = false;
    const SLocEntry &Entry = getSLocEntry(LocInfo.first, &Invalid);
    if (Invalid || !Entry.isFile())
      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;
    unsigned 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()) {
        const ContentCache *MainContentCache =
            MainSLoc.getFile().getContentCache();
        if (MainContentCache && MainContentCache->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) {
      bool Invalid = false;
      const SLocEntry &SLoc = getLocalSLocEntry(I, &Invalid);
      if (Invalid)
        return FileID();
  
      if (SLoc.isFile() && SLoc.getFile().getContentCache() &&
          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() &&
          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;
  
    ContentCache *Content
      = const_cast<ContentCache *>(Entry.getFile().getContentCache());
    if (!Content)
      return SourceLocation();
  
    // If this is the first use of line information for this buffer, compute the
    // SourceLineCache for it on demand.
    if (!Content->SourceLineCache) {
      bool MyInvalid = false;
      ComputeLineNumbers(Diag, Content, ContentCacheAlloc, *this, MyInvalid);
      if (MyInvalid)
        return SourceLocation();
    }
  
    if (Line > Content->NumLines) {
      unsigned Size = Content->getBuffer(Diag, getFileManager())->getBufferSize();
      if (Size > 0)
        --Size;
      return FileLoc.getLocWithOffset(Size);
    }
  
    const llvm::MemoryBuffer *Buffer = Content->getBuffer(Diag, getFileManager());
    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()) {
        SourceLocation IncludeLoc = Entry.getFile().getIncludeLoc();
        if (IncludeLoc.isInvalid())
          continue;
        if (!isInFileID(IncludeLoc, FID))
          return; // No more files/macros that may be "contained" in this file.
  
        // 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;
      }
  
      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()) {
      unsigned SpellBeginOffs = SpellLoc.getOffset();
      unsigned 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);
        unsigned SpellFIDBeginOffs = Entry.getOffset();
        unsigned SpellFIDSize = getFileIDSize(SpellFID);
        unsigned 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);
    --I;
  
    unsigned 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 = getBuffer(LOffs.first)->getBufferIdentifier();
    StringRef RB = getBuffer(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 += I->second->SourceLineCache != nullptr;
      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<unsigned> 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";
        if (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<unsigned> 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);
  }
  