--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/DebugInfo/PDB/Native/NamedStreamMap.cpp	Fri Oct 27 17:07:41 2017 +0900
@@ -0,0 +1,152 @@
+//===- NamedStreamMap.cpp - PDB Named Stream Map --------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/DebugInfo/PDB/Native/NamedStreamMap.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/iterator_range.h"
+#include "llvm/DebugInfo/PDB/Native/HashTable.h"
+#include "llvm/DebugInfo/PDB/Native/RawError.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamRef.h"
+#include "llvm/Support/BinaryStreamWriter.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/Error.h"
+#include <algorithm>
+#include <cassert>
+#include <cstdint>
+#include <tuple>
+
+using namespace llvm;
+using namespace llvm::pdb;
+
+// FIXME: This shouldn't be necessary, but if we insert the strings in any
+// other order, cvdump cannot read the generated name map.  This suggests that
+// we may be using the wrong hash function.  A closer inspection of the cvdump
+// source code may reveal something, but for now this at least makes us work,
+// even if only by accident.
+static constexpr const char *OrderedStreamNames[] = {"/LinkInfo", "/names",
+                                                     "/src/headerblock"};
+
+NamedStreamMap::NamedStreamMap() = default;
+
+Error NamedStreamMap::load(BinaryStreamReader &Stream) {
+  Mapping.clear();
+  FinalizedHashTable.clear();
+  FinalizedInfo.reset();
+
+  uint32_t StringBufferSize;
+  if (auto EC = Stream.readInteger(StringBufferSize))
+    return joinErrors(std::move(EC),
+                      make_error<RawError>(raw_error_code::corrupt_file,
+                                           "Expected string buffer size"));
+
+  BinaryStreamRef StringsBuffer;
+  if (auto EC = Stream.readStreamRef(StringsBuffer, StringBufferSize))
+    return EC;
+
+  HashTable OffsetIndexMap;
+  if (auto EC = OffsetIndexMap.load(Stream))
+    return EC;
+
+  uint32_t NameOffset;
+  uint32_t NameIndex;
+  for (const auto &Entry : OffsetIndexMap) {
+    std::tie(NameOffset, NameIndex) = Entry;
+
+    // Compute the offset of the start of the string relative to the stream.
+    BinaryStreamReader NameReader(StringsBuffer);
+    NameReader.setOffset(NameOffset);
+    // Pump out our c-string from the stream.
+    StringRef Str;
+    if (auto EC = NameReader.readCString(Str))
+      return joinErrors(std::move(EC),
+                        make_error<RawError>(raw_error_code::corrupt_file,
+                                             "Expected name map name"));
+
+    // Add this to a string-map from name to stream number.
+    Mapping.insert({Str, NameIndex});
+  }
+
+  return Error::success();
+}
+
+Error NamedStreamMap::commit(BinaryStreamWriter &Writer) const {
+  assert(FinalizedInfo.hasValue());
+
+  // The first field is the number of bytes of string data.
+  if (auto EC = Writer.writeInteger(FinalizedInfo->StringDataBytes))
+    return EC;
+
+  for (const auto &Name : OrderedStreamNames) {
+    auto Item = Mapping.find(Name);
+    if (Item == Mapping.end())
+      continue;
+    if (auto EC = Writer.writeCString(Item->getKey()))
+      return EC;
+  }
+
+  // And finally the Offset Index map.
+  if (auto EC = FinalizedHashTable.commit(Writer))
+    return EC;
+
+  return Error::success();
+}
+
+uint32_t NamedStreamMap::finalize() {
+  if (FinalizedInfo.hasValue())
+    return FinalizedInfo->SerializedLength;
+
+  // Build the finalized hash table.
+  FinalizedHashTable.clear();
+  FinalizedInfo.emplace();
+
+  for (const auto &Name : OrderedStreamNames) {
+    auto Item = Mapping.find(Name);
+    if (Item == Mapping.end())
+      continue;
+    FinalizedHashTable.set(FinalizedInfo->StringDataBytes, Item->getValue());
+    FinalizedInfo->StringDataBytes += Item->getKeyLength() + 1;
+  }
+
+  // Number of bytes of string data.
+  FinalizedInfo->SerializedLength += sizeof(support::ulittle32_t);
+  // Followed by that many actual bytes of string data.
+  FinalizedInfo->SerializedLength += FinalizedInfo->StringDataBytes;
+  // Followed by the mapping from Offset to Index.
+  FinalizedInfo->SerializedLength +=
+      FinalizedHashTable.calculateSerializedLength();
+  return FinalizedInfo->SerializedLength;
+}
+
+iterator_range<StringMapConstIterator<uint32_t>>
+NamedStreamMap::entries() const {
+  return make_range<StringMapConstIterator<uint32_t>>(Mapping.begin(),
+                                                      Mapping.end());
+}
+
+uint32_t NamedStreamMap::size() const { return Mapping.size(); }
+
+bool NamedStreamMap::get(StringRef Stream, uint32_t &StreamNo) const {
+  auto Iter = Mapping.find(Stream);
+  if (Iter == Mapping.end())
+    return false;
+  StreamNo = Iter->second;
+  return true;
+}
+
+void NamedStreamMap::set(StringRef Stream, uint32_t StreamNo) {
+  FinalizedInfo.reset();
+  Mapping[Stream] = StreamNo;
+}
+
+void NamedStreamMap::remove(StringRef Stream) {
+  FinalizedInfo.reset();
+  Mapping.erase(Stream);
+}