vendor/llvm/llvm-trunk-r302069

19 files changed, 1097 insertions, 378 deletions

diff --git a/lib/DebugInfo/CodeView/CMakeLists.txt b/lib/DebugInfo/CodeView/CMakeLists.txt
index 421f22ca5d8d7..410d5a3777d47 100644
--- a/lib/DebugInfo/CodeView/CMakeLists.txt
+++ b/lib/DebugInfo/CodeView/CMakeLists.txt
@@ -15,6 +15,7 @@ add_llvm_library(LLVMDebugInfoCodeView
   ModuleDebugLineFragment.cpp
   ModuleDebugUnknownFragment.cpp
   RecordSerialization.cpp
+  StringTable.cpp
   SymbolRecordMapping.cpp
   SymbolDumper.cpp
   SymbolSerializer.cpp
diff --git a/lib/DebugInfo/CodeView/ModuleDebugFileChecksumFragment.cpp b/lib/DebugInfo/CodeView/ModuleDebugFileChecksumFragment.cpp
index c349e7ecce961..42f0afc3e2d74 100644
--- a/lib/DebugInfo/CodeView/ModuleDebugFileChecksumFragment.cpp
+++ b/lib/DebugInfo/CodeView/ModuleDebugFileChecksumFragment.cpp
@@ -10,6 +10,7 @@
 #include "llvm/DebugInfo/CodeView/ModuleDebugFileChecksumFragment.h"
 
 #include "llvm/DebugInfo/CodeView/CodeViewError.h"
+#include "llvm/DebugInfo/CodeView/StringTable.h"
 #include "llvm/Support/BinaryStreamReader.h"
 
 using namespace llvm;
@@ -25,7 +26,7 @@ struct FileChecksumEntryHeader {
 };
 
 Error llvm::VarStreamArrayExtractor<FileChecksumEntry>::extract(
-    BinaryStreamRef Stream, uint32_t &Len, FileChecksumEntry &Item, void *Ctx) {
+    BinaryStreamRef Stream, uint32_t &Len, FileChecksumEntry &Item) {
   BinaryStreamReader Reader(Stream);
 
   const FileChecksumEntryHeader *Header;
@@ -49,10 +50,12 @@ Error ModuleDebugFileChecksumFragmentRef::initialize(
   return Error::success();
 }
 
-ModuleDebugFileChecksumFragment::ModuleDebugFileChecksumFragment()
-    : ModuleDebugFragment(ModuleDebugFragmentKind::FileChecksums) {}
+ModuleDebugFileChecksumFragment::ModuleDebugFileChecksumFragment(
+    StringTable &Strings)
+    : ModuleDebugFragment(ModuleDebugFragmentKind::FileChecksums),
+      Strings(Strings) {}
 
-void ModuleDebugFileChecksumFragment::addChecksum(uint32_t StringTableOffset,
+void ModuleDebugFileChecksumFragment::addChecksum(StringRef FileName,
                                                   FileChecksumKind Kind,
                                                   ArrayRef<uint8_t> Bytes) {
   FileChecksumEntry Entry;
@@ -61,13 +64,14 @@ void ModuleDebugFileChecksumFragment::addChecksum(uint32_t StringTableOffset,
     ::memcpy(Copy, Bytes.data(), Bytes.size());
     Entry.Checksum = makeArrayRef(Copy, Bytes.size());
   }
-  Entry.FileNameOffset = StringTableOffset;
+
+  Entry.FileNameOffset = Strings.insert(FileName);
   Entry.Kind = Kind;
   Checksums.push_back(Entry);
 
   // This maps the offset of this string in the string table to the offset
   // of this checksum entry in the checksum buffer.
-  OffsetMap[StringTableOffset] = SerializedSize;
+  OffsetMap[Entry.FileNameOffset] = SerializedSize;
   assert(SerializedSize % 4 == 0);
 
   uint32_t Len = alignTo(sizeof(FileChecksumEntryHeader) + Bytes.size(), 4);
@@ -94,9 +98,10 @@ Error ModuleDebugFileChecksumFragment::commit(BinaryStreamWriter &Writer) {
   return Error::success();
 }
 
-uint32_t ModuleDebugFileChecksumFragment::mapChecksumOffset(
-    uint32_t StringTableOffset) const {
-  auto Iter = OffsetMap.find(StringTableOffset);
+uint32_t
+ModuleDebugFileChecksumFragment::mapChecksumOffset(StringRef FileName) const {
+  uint32_t Offset = Strings.getStringId(FileName);
+  auto Iter = OffsetMap.find(Offset);
   assert(Iter != OffsetMap.end());
   return Iter->second;
 }
diff --git a/lib/DebugInfo/CodeView/ModuleDebugInlineeLinesFragment.cpp b/lib/DebugInfo/CodeView/ModuleDebugInlineeLinesFragment.cpp
index 483f7cb5c5ad3..cb6a8478797f9 100644
--- a/lib/DebugInfo/CodeView/ModuleDebugInlineeLinesFragment.cpp
+++ b/lib/DebugInfo/CodeView/ModuleDebugInlineeLinesFragment.cpp
@@ -10,20 +10,22 @@
 #include "llvm/DebugInfo/CodeView/ModuleDebugInlineeLinesFragment.h"
 
 #include "llvm/DebugInfo/CodeView/CodeViewError.h"
+#include "llvm/DebugInfo/CodeView/ModuleDebugFileChecksumFragment.h"
 #include "llvm/DebugInfo/CodeView/ModuleDebugFragmentRecord.h"
+#include "llvm/DebugInfo/CodeView/StringTable.h"
 
 using namespace llvm;
 using namespace llvm::codeview;
 
 Error VarStreamArrayExtractor<InlineeSourceLine>::extract(
     BinaryStreamRef Stream, uint32_t &Len, InlineeSourceLine &Item,
-    ContextType *Fragment) {
+    bool HasExtraFiles) {
   BinaryStreamReader Reader(Stream);
 
   if (auto EC = Reader.readObject(Item.Header))
     return EC;
 
-  if (Fragment->hasExtraFiles()) {
+  if (HasExtraFiles) {
     uint32_t ExtraFileCount;
     if (auto EC = Reader.readInteger(ExtraFileCount))
       return EC;
@@ -42,7 +44,8 @@ Error ModuleDebugInlineeLineFragmentRef::initialize(BinaryStreamReader Reader) {
   if (auto EC = Reader.readEnum(Signature))
     return EC;
 
-  if (auto EC = Reader.readArray(Lines, Reader.bytesRemaining(), this))
+  if (auto EC =
+          Reader.readArray(Lines, Reader.bytesRemaining(), hasExtraFiles()))
     return EC;
 
   assert(Reader.bytesRemaining() == 0);
@@ -54,9 +57,9 @@ bool ModuleDebugInlineeLineFragmentRef::hasExtraFiles() const {
 }
 
 ModuleDebugInlineeLineFragment::ModuleDebugInlineeLineFragment(
-    bool HasExtraFiles)
+    ModuleDebugFileChecksumFragment &Checksums, bool HasExtraFiles)
     : ModuleDebugFragment(ModuleDebugFragmentKind::InlineeLines),
-      HasExtraFiles(HasExtraFiles) {}
+      Checksums(Checksums), HasExtraFiles(HasExtraFiles) {}
 
 uint32_t ModuleDebugInlineeLineFragment::calculateSerializedLength() {
   // 4 bytes for the signature
@@ -99,18 +102,22 @@ Error ModuleDebugInlineeLineFragment::commit(BinaryStreamWriter &Writer) {
   return Error::success();
 }
 
-void ModuleDebugInlineeLineFragment::addExtraFile(uint32_t FileOffset) {
+void ModuleDebugInlineeLineFragment::addExtraFile(StringRef FileName) {
+  uint32_t Offset = Checksums.mapChecksumOffset(FileName);
+
   auto &Entry = Entries.back();
-  Entry.ExtraFiles.push_back(ulittle32_t(FileOffset));
+  Entry.ExtraFiles.push_back(ulittle32_t(Offset));
   ++ExtraFileCount;
 }
 
 void ModuleDebugInlineeLineFragment::addInlineSite(TypeIndex FuncId,
-                                                   uint32_t FileOffset,
+                                                   StringRef FileName,
                                                    uint32_t SourceLine) {
+  uint32_t Offset = Checksums.mapChecksumOffset(FileName);
+
   Entries.emplace_back();
   auto &Entry = Entries.back();
-  Entry.Header.FileID = FileOffset;
+  Entry.Header.FileID = Offset;
   Entry.Header.SourceLineNum = SourceLine;
   Entry.Header.Inlinee = FuncId;
 }
diff --git a/lib/DebugInfo/CodeView/ModuleDebugLineFragment.cpp b/lib/DebugInfo/CodeView/ModuleDebugLineFragment.cpp
index 103010ca28332..e0ee934709ba5 100644
--- a/lib/DebugInfo/CodeView/ModuleDebugLineFragment.cpp
+++ b/lib/DebugInfo/CodeView/ModuleDebugLineFragment.cpp
@@ -10,7 +10,9 @@
 #include "llvm/DebugInfo/CodeView/ModuleDebugLineFragment.h"
 
 #include "llvm/DebugInfo/CodeView/CodeViewError.h"
+#include "llvm/DebugInfo/CodeView/ModuleDebugFileChecksumFragment.h"
 #include "llvm/DebugInfo/CodeView/ModuleDebugFragmentRecord.h"
+#include "llvm/DebugInfo/CodeView/StringTable.h"
 
 using namespace llvm;
 using namespace llvm::codeview;
@@ -65,11 +67,15 @@ bool ModuleDebugLineFragmentRef::hasColumnInfo() const {
   return !!(Header->Flags & LF_HaveColumns);
 }
 
-ModuleDebugLineFragment::ModuleDebugLineFragment()
-    : ModuleDebugFragment(ModuleDebugFragmentKind::Lines) {}
+ModuleDebugLineFragment::ModuleDebugLineFragment(
+    ModuleDebugFileChecksumFragment &Checksums, StringTable &Strings)
+    : ModuleDebugFragment(ModuleDebugFragmentKind::Lines),
+      Checksums(Checksums) {}
 
-void ModuleDebugLineFragment::createBlock(uint32_t ChecksumBufferOffset) {
-  Blocks.emplace_back(ChecksumBufferOffset);
+void ModuleDebugLineFragment::createBlock(StringRef FileName) {
+  uint32_t Offset = Checksums.mapChecksumOffset(FileName);
+
+  Blocks.emplace_back(Offset);
 }
 
 void ModuleDebugLineFragment::addLineInfo(uint32_t Offset,
diff --git a/lib/DebugInfo/CodeView/StringTable.cpp b/lib/DebugInfo/CodeView/StringTable.cpp
new file mode 100644
index 0000000000000..21f11204686b4
--- /dev/null
+++ b/lib/DebugInfo/CodeView/StringTable.cpp
@@ -0,0 +1,71 @@
+//===- StringTable.cpp - CodeView String Table Reader/Writer ----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/DebugInfo/CodeView/StringTable.h"
+
+#include "llvm/Support/BinaryStream.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamWriter.h"
+
+using namespace llvm;
+using namespace llvm::codeview;
+
+StringTableRef::StringTableRef() {}
+
+Error StringTableRef::initialize(BinaryStreamRef Contents) {
+  Stream = Contents;
+  return Error::success();
+}
+
+Expected<StringRef> StringTableRef::getString(uint32_t Offset) const {
+  BinaryStreamReader Reader(Stream);
+  Reader.setOffset(Offset);
+  StringRef Result;
+  if (auto EC = Reader.readCString(Result))
+    return std::move(EC);
+  return Result;
+}
+
+uint32_t StringTable::insert(StringRef S) {
+  auto P = Strings.insert({S, StringSize});
+
+  // If a given string didn't exist in the string table, we want to increment
+  // the string table size.
+  if (P.second)
+    StringSize += S.size() + 1; // +1 for '\0'
+  return P.first->second;
+}
+
+uint32_t StringTable::calculateSerializedSize() const { return StringSize; }
+
+Error StringTable::commit(BinaryStreamWriter &Writer) const {
+  assert(Writer.bytesRemaining() == StringSize);
+  uint32_t MaxOffset = 1;
+
+  for (auto &Pair : Strings) {
+    StringRef S = Pair.getKey();
+    uint32_t Offset = Pair.getValue();
+    Writer.setOffset(Offset);
+    if (auto EC = Writer.writeCString(S))
+      return EC;
+    MaxOffset = std::max<uint32_t>(MaxOffset, Offset + S.size() + 1);
+  }
+
+  Writer.setOffset(MaxOffset);
+  assert(Writer.bytesRemaining() == 0);
+  return Error::success();
+}
+
+uint32_t StringTable::size() const { return Strings.size(); }
+
+uint32_t StringTable::getStringId(StringRef S) const {
+  auto P = Strings.find(S);
+  assert(P != Strings.end());
+  return P->second;
+}
diff --git a/lib/DebugInfo/CodeView/SymbolDumper.cpp b/lib/DebugInfo/CodeView/SymbolDumper.cpp
index 134471e81cacd..5395e4349b28d 100644
--- a/lib/DebugInfo/CodeView/SymbolDumper.cpp
+++ b/lib/DebugInfo/CodeView/SymbolDumper.cpp
@@ -13,6 +13,7 @@
 #include "llvm/DebugInfo/CodeView/CVSymbolVisitor.h"
 #include "llvm/DebugInfo/CodeView/CVTypeDumper.h"
 #include "llvm/DebugInfo/CodeView/EnumTables.h"
+#include "llvm/DebugInfo/CodeView/StringTable.h"
 #include "llvm/DebugInfo/CodeView/SymbolDeserializer.h"
 #include "llvm/DebugInfo/CodeView/SymbolDumpDelegate.h"
 #include "llvm/DebugInfo/CodeView/SymbolRecord.h"
@@ -369,14 +370,14 @@ Error CVSymbolDumperImpl::visitKnownRecord(
   DictScope S(W, "DefRangeSubfield");
 
   if (ObjDelegate) {
-    StringRef StringTable = ObjDelegate->getStringTable();
-    auto ProgramStringTableOffset = DefRangeSubfield.Program;
-    if (ProgramStringTableOffset >= StringTable.size())
+    StringTableRef Strings = ObjDelegate->getStringTable();
+    auto ExpectedProgram = Strings.getString(DefRangeSubfield.Program);
+    if (!ExpectedProgram) {
+      consumeError(ExpectedProgram.takeError());
       return llvm::make_error<CodeViewError>(
           "String table offset outside of bounds of String Table!");
-    StringRef Program =
-        StringTable.drop_front(ProgramStringTableOffset).split('\0').first;
-    W.printString("Program", Program);
+    }
+    W.printString("Program", *ExpectedProgram);
   }
   W.printNumber("OffsetInParent", DefRangeSubfield.OffsetInParent);
   printLocalVariableAddrRange(DefRangeSubfield.Range,
@@ -390,14 +391,14 @@ Error CVSymbolDumperImpl::visitKnownRecord(CVSymbol &CVR,
   DictScope S(W, "DefRange");
 
   if (ObjDelegate) {
-    StringRef StringTable = ObjDelegate->getStringTable();
-    auto ProgramStringTableOffset = DefRange.Program;
-    if (ProgramStringTableOffset >= StringTable.size())
+    StringTableRef Strings = ObjDelegate->getStringTable();
+    auto ExpectedProgram = Strings.getString(DefRange.Program);
+    if (!ExpectedProgram) {
+      consumeError(ExpectedProgram.takeError());
       return llvm::make_error<CodeViewError>(
           "String table offset outside of bounds of String Table!");
-    StringRef Program =
-        StringTable.drop_front(ProgramStringTableOffset).split('\0').first;
-    W.printString("Program", Program);
+    }
+    W.printString("Program", *ExpectedProgram);
   }
   printLocalVariableAddrRange(DefRange.Range, DefRange.getRelocationOffset());
   printLocalVariableAddrGap(DefRange.Gaps);
diff --git a/lib/DebugInfo/DWARF/CMakeLists.txt b/lib/DebugInfo/DWARF/CMakeLists.txt
index 495edb7b48db0..6ca6e64bd8e6f 100644
--- a/lib/DebugInfo/DWARF/CMakeLists.txt
+++ b/lib/DebugInfo/DWARF/CMakeLists.txt
@@ -19,6 +19,7 @@ add_llvm_library(LLVMDebugInfoDWARF
   DWARFTypeUnit.cpp
   DWARFUnitIndex.cpp
   DWARFUnit.cpp
+  DWARFVerifier.cpp
   SyntaxHighlighting.cpp
 
   ADDITIONAL_HEADER_DIRS
diff --git a/lib/DebugInfo/DWARF/DWARFContext.cpp b/lib/DebugInfo/DWARF/DWARFContext.cpp
index b4ecbf805d1e3..573d37d77fee2 100644
--- a/lib/DebugInfo/DWARF/DWARFContext.cpp
+++ b/lib/DebugInfo/DWARF/DWARFContext.cpp
@@ -7,17 +7,17 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/DebugInfo/DWARF/DWARFContext.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/StringSwitch.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/StringSwitch.h"
 #include "llvm/DebugInfo/DWARF/DWARFAcceleratorTable.h"
 #include "llvm/DebugInfo/DWARF/DWARFCompileUnit.h"
-#include "llvm/DebugInfo/DWARF/DWARFContext.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugAbbrev.h"
-#include "llvm/DebugInfo/DWARF/DWARFDebugAranges.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugArangeSet.h"
+#include "llvm/DebugInfo/DWARF/DWARFDebugAranges.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugFrame.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugLine.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugLoc.h"
@@ -29,6 +29,7 @@
 #include "llvm/DebugInfo/DWARF/DWARFGdbIndex.h"
 #include "llvm/DebugInfo/DWARF/DWARFSection.h"
 #include "llvm/DebugInfo/DWARF/DWARFUnitIndex.h"
+#include "llvm/DebugInfo/DWARF/DWARFVerifier.h"
 #include "llvm/Object/Decompressor.h"
 #include "llvm/Object/MachO.h"
 #include "llvm/Object/ObjectFile.h"
@@ -42,6 +43,8 @@
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <cstdint>
+#include <map>
+#include <set>
 #include <string>
 #include <utility>
 #include <vector>
@@ -284,11 +287,30 @@ void DWARFContext::dump(raw_ostream &OS, DIDumpType DumpType, bool DumpEH,
                      getStringSection(), isLittleEndian());
 }
 
-bool DWARFContext::verify(raw_ostream &OS, DIDumpType DumpType) {
-  bool Success = true;
-  if (DumpType == DIDT_All || DumpType == DIDT_Info) {
+DWARFDie DWARFContext::getDIEForOffset(uint32_t Offset) {
+  parseCompileUnits();
+  if (auto *CU = CUs.getUnitForOffset(Offset))
+    return CU->getDIEForOffset(Offset);
+  return DWARFDie();
+}
+
+namespace {
+  
+class Verifier {
+  raw_ostream &OS;
+  DWARFContext &DCtx;
+public:
+  Verifier(raw_ostream &S, DWARFContext &D) : OS(S), DCtx(D) {}
+  
+  bool HandleDebugInfo() {
+    bool Success = true;
+    // A map that tracks all references (converted absolute references) so we
+    // can verify each reference points to a valid DIE and not an offset that
+    // lies between to valid DIEs.
+    std::map<uint64_t, std::set<uint32_t>> ReferenceToDIEOffsets;
+
     OS << "Verifying .debug_info...\n";
-    for (const auto &CU : compile_units()) {
+    for (const auto &CU : DCtx.compile_units()) {
       unsigned NumDies = CU->getNumDIEs();
       for (unsigned I = 0; I < NumDies; ++I) {
         auto Die = CU->getDIEAtIndex(I);
@@ -299,101 +321,231 @@ bool DWARFContext::verify(raw_ostream &OS, DIDumpType DumpType) {
           const auto Attr = AttrValue.Attr;
           const auto Form = AttrValue.Value.getForm();
           switch (Attr) {
-          case DW_AT_ranges:
-            // Make sure the offset in the DW_AT_ranges attribute is valid.
-            if (auto SectionOffset = AttrValue.Value.getAsSectionOffset()) {
-              if (*SectionOffset >= getRangeSection().Data.size()) {
+            case DW_AT_ranges:
+              // Make sure the offset in the DW_AT_ranges attribute is valid.
+              if (auto SectionOffset = AttrValue.Value.getAsSectionOffset()) {
+                if (*SectionOffset >= DCtx.getRangeSection().Data.size()) {
+                  Success = false;
+                  OS << "error: DW_AT_ranges offset is beyond .debug_ranges "
+                  "bounds:\n";
+                  Die.dump(OS, 0);
+                  OS << "\n";
+                }
+              } else {
                 Success = false;
-                OS << "error: DW_AT_ranges offset is beyond .debug_ranges "
-                      "bounds:\n";
+                OS << "error: DIE has invalid DW_AT_ranges encoding:\n";
                 Die.dump(OS, 0);
                 OS << "\n";
               }
-            } else {
-              Success = false;
-              OS << "error: DIE has invalid DW_AT_ranges encoding:\n";
-              Die.dump(OS, 0);
-              OS << "\n";
-            }
-            break;
-          case DW_AT_stmt_list:
-            // Make sure the offset in the DW_AT_stmt_list attribute is valid.
-            if (auto SectionOffset = AttrValue.Value.getAsSectionOffset()) {
-              if (*SectionOffset >= getLineSection().Data.size()) {
+              break;
+            case DW_AT_stmt_list:
+              // Make sure the offset in the DW_AT_stmt_list attribute is valid.
+              if (auto SectionOffset = AttrValue.Value.getAsSectionOffset()) {
+                if (*SectionOffset >= DCtx.getLineSection().Data.size()) {
+                  Success = false;
+                  OS << "error: DW_AT_stmt_list offset is beyond .debug_line "
+                  "bounds: "
+                  << format("0x%08" PRIx32, *SectionOffset) << "\n";
+                  CU->getUnitDIE().dump(OS, 0);
+                  OS << "\n";
+                }
+              } else {
                 Success = false;
-                OS << "error: DW_AT_stmt_list offset is beyond .debug_line "
-                      "bounds: "
-                   << format("0x%08" PRIx32, *SectionOffset) << "\n";
-                CU->getUnitDIE().dump(OS, 0);
+                OS << "error: DIE has invalid DW_AT_stmt_list encoding:\n";
+                Die.dump(OS, 0);
                 OS << "\n";
               }
-            } else {
-              Success = false;
-              OS << "error: DIE has invalid DW_AT_stmt_list encoding:\n";
-              Die.dump(OS, 0);
-              OS << "\n";
-            }
-            break;
-
-          default:
-            break;
+              break;
+              
+            default:
+              break;
           }
           switch (Form) {
-          case DW_FORM_ref1:
-          case DW_FORM_ref2:
-          case DW_FORM_ref4:
-          case DW_FORM_ref8:
-          case DW_FORM_ref_udata: {
-            // Verify all CU relative references are valid CU offsets.
-            Optional<uint64_t> RefVal = AttrValue.Value.getAsReference();
-            assert(RefVal);
-            if (RefVal) {
-              auto DieCU = Die.getDwarfUnit();
-              auto CUSize = DieCU->getNextUnitOffset() - DieCU->getOffset();
-              auto CUOffset = AttrValue.Value.getRawUValue();
-              if (CUOffset >= CUSize) {
+            case DW_FORM_ref1:
+            case DW_FORM_ref2:
+            case DW_FORM_ref4:
+            case DW_FORM_ref8:
+            case DW_FORM_ref_udata: {
+              // Verify all CU relative references are valid CU offsets.
+              Optional<uint64_t> RefVal = AttrValue.Value.getAsReference();
+              assert(RefVal);
+              if (RefVal) {
+                auto DieCU = Die.getDwarfUnit();
+                auto CUSize = DieCU->getNextUnitOffset() - DieCU->getOffset();
+                auto CUOffset = AttrValue.Value.getRawUValue();
+                if (CUOffset >= CUSize) {
+                  Success = false;
+                  OS << "error: " << FormEncodingString(Form) << " CU offset "
+                  << format("0x%08" PRIx32, CUOffset)
+                  << " is invalid (must be less than CU size of "
+                  << format("0x%08" PRIx32, CUSize) << "):\n";
+                  Die.dump(OS, 0);
+                  OS << "\n";
+                } else {
+                  // Valid reference, but we will verify it points to an actual
+                  // DIE later.
+                  ReferenceToDIEOffsets[*RefVal].insert(Die.getOffset());
+                }
+              }
+              break;
+            }
+            case DW_FORM_ref_addr: {
+              // Verify all absolute DIE references have valid offsets in the
+              // .debug_info section.
+              Optional<uint64_t> RefVal = AttrValue.Value.getAsReference();
+              assert(RefVal);
+              if (RefVal) {
+                if(*RefVal >= DCtx.getInfoSection().Data.size()) {
+                  Success = false;
+                  OS << "error: DW_FORM_ref_addr offset beyond .debug_info "
+                        "bounds:\n";
+                  Die.dump(OS, 0);
+                  OS << "\n";
+                } else {
+                  // Valid reference, but we will verify it points to an actual
+                  // DIE later.
+                  ReferenceToDIEOffsets[*RefVal].insert(Die.getOffset());
+                }
+              }
+              break;
+            }
+            case DW_FORM_strp: {
+              auto SecOffset = AttrValue.Value.getAsSectionOffset();
+              assert(SecOffset); // DW_FORM_strp is a section offset.
+              if (SecOffset && *SecOffset >= DCtx.getStringSection().size()) {
                 Success = false;
-                OS << "error: " << FormEncodingString(Form) << " CU offset "
-                   << format("0x%08" PRIx32, CUOffset)
-                   << " is invalid (must be less than CU size of "
-                   << format("0x%08" PRIx32, CUSize) << "):\n";
+                OS << "error: DW_FORM_strp offset beyond .debug_str bounds:\n";
                 Die.dump(OS, 0);
                 OS << "\n";
               }
+              break;
             }
-            break;
+            default:
+              break;
           }
-          case DW_FORM_ref_addr: {
-            // Verify all absolute DIE references have valid offsets in the
-            // .debug_info section.
-            Optional<uint64_t> RefVal = AttrValue.Value.getAsReference();
-            assert(RefVal);
-            if (RefVal && *RefVal >= getInfoSection().Data.size()) {
-              Success = false;
-              OS << "error: DW_FORM_ref_addr offset beyond .debug_info "
-                    "bounds:\n";
-              Die.dump(OS, 0);
-              OS << "\n";
-            }
-            break;
-          }
-          case DW_FORM_strp: {
-            auto SecOffset = AttrValue.Value.getAsSectionOffset();
-            assert(SecOffset); // DW_FORM_strp is a section offset.
-            if (SecOffset && *SecOffset >= getStringSection().size()) {
-              Success = false;
-              OS << "error: DW_FORM_strp offset beyond .debug_str bounds:\n";
-              Die.dump(OS, 0);
-              OS << "\n";
-            }
-            break;
-          }
-          default:
-            break;
+        }
+      }
+    }
+
+    // Take all references and make sure they point to an actual DIE by
+    // getting the DIE by offset and emitting an error
+    OS << "Verifying .debug_info references...\n";
+    for (auto Pair: ReferenceToDIEOffsets) {
+      auto Die = DCtx.getDIEForOffset(Pair.first);
+      if (Die)
+        continue;
+      Success = false;
+      OS << "error: invalid DIE reference " << format("0x%08" PRIx64, Pair.first)
+         << ". Offset is in between DIEs:\n";
+      for (auto Offset: Pair.second) {
+        auto ReferencingDie = DCtx.getDIEForOffset(Offset);
+        ReferencingDie.dump(OS, 0);
+        OS << "\n";
+      }
+      OS << "\n";
+    }
+    return Success;
+  }
+
+  bool HandleDebugLine() {
+    std::map<uint64_t, DWARFDie> StmtListToDie;
+    bool Success = true;
+    OS << "Verifying .debug_line...\n";
+    for (const auto &CU : DCtx.compile_units()) {
+      uint32_t LineTableOffset = 0;
+      auto CUDie = CU->getUnitDIE();
+      auto StmtFormValue = CUDie.find(DW_AT_stmt_list);
+      if (!StmtFormValue) {
+        // No line table for this compile unit.
+        continue;
+      }
+      // Get the attribute value as a section offset. No need to produce an
+      // error here if the encoding isn't correct because we validate this in
+      // the .debug_info verifier.
+      if (auto StmtSectionOffset = toSectionOffset(StmtFormValue)) {
+        LineTableOffset = *StmtSectionOffset;
+        if (LineTableOffset >= DCtx.getLineSection().Data.size()) {
+          // Make sure we don't get a valid line table back if the offset
+          // is wrong.
+          assert(DCtx.getLineTableForUnit(CU.get()) == nullptr);
+          // Skip this line table as it isn't valid. No need to create an error
+          // here because we validate this in the .debug_info verifier.
+          continue;
+        } else {
+          auto Iter = StmtListToDie.find(LineTableOffset);
+          if (Iter != StmtListToDie.end()) {
+            Success = false;
+            OS << "error: two compile unit DIEs, "
+               << format("0x%08" PRIx32, Iter->second.getOffset()) << " and "
+               << format("0x%08" PRIx32, CUDie.getOffset())
+               << ", have the same DW_AT_stmt_list section offset:\n";
+            Iter->second.dump(OS, 0);
+            CUDie.dump(OS, 0);
+            OS << '\n';
+            // Already verified this line table before, no need to do it again.
+            continue;
           }
+          StmtListToDie[LineTableOffset] = CUDie;
         }
       }
+      auto LineTable = DCtx.getLineTableForUnit(CU.get());
+      if (!LineTable) {
+        Success = false;
+        OS << "error: .debug_line[" << format("0x%08" PRIx32, LineTableOffset)
+           << "] was not able to be parsed for CU:\n";
+        CUDie.dump(OS, 0);
+        OS << '\n';
+        continue;
+      }
+      uint32_t MaxFileIndex = LineTable->Prologue.FileNames.size();
+      uint64_t PrevAddress = 0;
+      uint32_t RowIndex = 0;
+      for (const auto &Row : LineTable->Rows) {
+        if (Row.Address < PrevAddress) {
+          Success = false;
+          OS << "error: .debug_line[" << format("0x%08" PRIx32, LineTableOffset)
+             << "] row[" << RowIndex
+             << "] decreases in address from previous row:\n";
+
+          DWARFDebugLine::Row::dumpTableHeader(OS);
+          if (RowIndex > 0)
+            LineTable->Rows[RowIndex - 1].dump(OS);
+          Row.dump(OS);
+          OS << '\n';
+        }
+
+        if (Row.File > MaxFileIndex) {
+          Success = false;
+          OS << "error: .debug_line[" << format("0x%08" PRIx32, LineTableOffset)
+             << "][" << RowIndex << "] has invalid file index " << Row.File
+             << " (valid values are [1," << MaxFileIndex << "]):\n";
+          DWARFDebugLine::Row::dumpTableHeader(OS);
+          Row.dump(OS);
+          OS << '\n';
+        }
+        if (Row.EndSequence)
+          PrevAddress = 0;
+        else
+          PrevAddress = Row.Address;
+        ++RowIndex;
+      }
     }
+    return Success;
+  }
+};
+  
+} // anonymous namespace
+
+bool DWARFContext::verify(raw_ostream &OS, DIDumpType DumpType) {
+  bool Success = true;
+  DWARFVerifier verifier(OS, *this);
+  if (DumpType == DIDT_All || DumpType == DIDT_Info) {
+    if (!verifier.handleDebugInfo())
+      Success = false;
+  }
+  if (DumpType == DIDT_All || DumpType == DIDT_Line) {
+    if (!verifier.handleDebugLine())
+      Success = false;
   }
   return Success;
 }
diff --git a/lib/DebugInfo/DWARF/DWARFDebugLine.cpp b/lib/DebugInfo/DWARF/DWARFDebugLine.cpp
index 77f3c00cc03fd..f32e8fe763579 100644
--- a/lib/DebugInfo/DWARF/DWARFDebugLine.cpp
+++ b/lib/DebugInfo/DWARF/DWARFDebugLine.cpp
@@ -10,6 +10,7 @@
 #include "llvm/DebugInfo/DWARF/DWARFDebugLine.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
+#include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
 #include "llvm/DebugInfo/DWARF/DWARFRelocMap.h"
 #include "llvm/Support/Dwarf.h"
 #include "llvm/Support/Format.h"
@@ -26,11 +27,19 @@ using namespace llvm;
 using namespace dwarf;
 
 typedef DILineInfoSpecifier::FileLineInfoKind FileLineInfoKind;
+namespace {
+struct ContentDescriptor {
+  dwarf::LineNumberEntryFormat Type;
+  dwarf::Form Form;
+};
+typedef SmallVector<ContentDescriptor, 4> ContentDescriptors;
+} // end anonmyous namespace
 
 DWARFDebugLine::Prologue::Prologue() { clear(); }
 
 void DWARFDebugLine::Prologue::clear() {
   TotalLength = Version = PrologueLength = 0;
+  AddressSize = SegSelectorSize = 0;
   MinInstLength = MaxOpsPerInst = DefaultIsStmt = LineBase = LineRange = 0;
   OpcodeBase = 0;
   IsDWARF64 = false;
@@ -43,6 +52,8 @@ void DWARFDebugLine::Prologue::dump(raw_ostream &OS) const {
   OS << "Line table prologue:\n"
      << format("    total_length: 0x%8.8" PRIx64 "\n", TotalLength)
      << format("         version: %u\n", Version)
+     << format(Version >= 5 ? "    address_size: %u\n" : "", AddressSize)
+     << format(Version >= 5 ? " seg_select_size: %u\n" : "", SegSelectorSize)
      << format(" prologue_length: 0x%8.8" PRIx64 "\n", PrologueLength)
      << format(" min_inst_length: %u\n", MinInstLength)
      << format(Version >= 4 ? "max_ops_per_inst: %u\n" : "", MaxOpsPerInst)
@@ -74,6 +85,125 @@ void DWARFDebugLine::Prologue::dump(raw_ostream &OS) const {
   }
 }
 
+// Parse v2-v4 directory and file tables.
+static void
+parseV2DirFileTables(DataExtractor DebugLineData, uint32_t *OffsetPtr,
+                     uint64_t EndPrologueOffset,
+                     std::vector<StringRef> &IncludeDirectories,
+                     std::vector<DWARFDebugLine::FileNameEntry> &FileNames) {
+  while (*OffsetPtr < EndPrologueOffset) {
+    StringRef S = DebugLineData.getCStrRef(OffsetPtr);
+    if (S.empty())
+      break;
+    IncludeDirectories.push_back(S);
+  }
+
+  while (*OffsetPtr < EndPrologueOffset) {
+    StringRef Name = DebugLineData.getCStrRef(OffsetPtr);
+    if (Name.empty())
+      break;
+    DWARFDebugLine::FileNameEntry FileEntry;
+    FileEntry.Name = Name;
+    FileEntry.DirIdx = DebugLineData.getULEB128(OffsetPtr);
+    FileEntry.ModTime = DebugLineData.getULEB128(OffsetPtr);
+    FileEntry.Length = DebugLineData.getULEB128(OffsetPtr);
+    FileNames.push_back(FileEntry);
+  }
+}
+
+// Parse v5 directory/file entry content descriptions.
+// Returns the descriptors, or an empty vector if we did not find a path or
+// ran off the end of the prologue.
+static ContentDescriptors
+parseV5EntryFormat(DataExtractor DebugLineData, uint32_t *OffsetPtr,
+                   uint64_t EndPrologueOffset) {
+  ContentDescriptors Descriptors;
+  int FormatCount = DebugLineData.getU8(OffsetPtr);
+  bool HasPath = false;
+  for (int I = 0; I != FormatCount; ++I) {
+    if (*OffsetPtr >= EndPrologueOffset)
+      return ContentDescriptors();
+    ContentDescriptor Descriptor;
+    Descriptor.Type =
+      dwarf::LineNumberEntryFormat(DebugLineData.getULEB128(OffsetPtr));
+    Descriptor.Form = dwarf::Form(DebugLineData.getULEB128(OffsetPtr));
+    if (Descriptor.Type == dwarf::DW_LNCT_path)
+      HasPath = true;
+    Descriptors.push_back(Descriptor);
+  }
+  return HasPath ? Descriptors : ContentDescriptors();
+}
+
+static bool
+parseV5DirFileTables(DataExtractor DebugLineData, uint32_t *OffsetPtr,
+                     uint64_t EndPrologueOffset,
+                     std::vector<StringRef> &IncludeDirectories,
+                     std::vector<DWARFDebugLine::FileNameEntry> &FileNames) {
+  // Get the directory entry description.
+  ContentDescriptors DirDescriptors =
+    parseV5EntryFormat(DebugLineData, OffsetPtr, EndPrologueOffset);
+  if (DirDescriptors.empty())
+    return false;
+
+  // Get the directory entries, according to the format described above.
+  int DirEntryCount = DebugLineData.getU8(OffsetPtr);
+  for (int I = 0; I != DirEntryCount; ++I) {
+    if (*OffsetPtr >= EndPrologueOffset)
+      return false;
+    for (auto Descriptor : DirDescriptors) {
+      DWARFFormValue Value(Descriptor.Form);
+      switch (Descriptor.Type) {
+      case DW_LNCT_path:
+        if (!Value.extractValue(DebugLineData, OffsetPtr, nullptr))
+          return false;
+        IncludeDirectories.push_back(Value.getAsCString().getValue());
+        break;
+      default:
+        if (!Value.skipValue(DebugLineData, OffsetPtr, nullptr))
+          return false;
+      }
+    }
+  }
+
+  // Get the file entry description.
+  ContentDescriptors FileDescriptors =
+    parseV5EntryFormat(DebugLineData, OffsetPtr, EndPrologueOffset);
+  if (FileDescriptors.empty())
+    return false;
+
+  // Get the file entries, according to the format described above.
+  int FileEntryCount = DebugLineData.getU8(OffsetPtr);
+  for (int I = 0; I != FileEntryCount; ++I) {
+    if (*OffsetPtr >= EndPrologueOffset)
+      return false;
+    DWARFDebugLine::FileNameEntry FileEntry;
+    for (auto Descriptor : FileDescriptors) {
+      DWARFFormValue Value(Descriptor.Form);
+      if (!Value.extractValue(DebugLineData, OffsetPtr, nullptr))
+        return false;
+      switch (Descriptor.Type) {
+      case DW_LNCT_path:
+        FileEntry.Name = Value.getAsCString().getValue();
+        break;
+      case DW_LNCT_directory_index:
+        FileEntry.DirIdx = Value.getAsUnsignedConstant().getValue();
+        break;
+      case DW_LNCT_timestamp:
+        FileEntry.ModTime = Value.getAsUnsignedConstant().getValue();
+        break;
+      case DW_LNCT_size:
+        FileEntry.Length = Value.getAsUnsignedConstant().getValue();
+        break;
+      // FIXME: Add MD5
+      default:
+        break;
+      }
+    }
+    FileNames.push_back(FileEntry);
+  }
+  return true;
+}
+
 bool DWARFDebugLine::Prologue::parse(DataExtractor DebugLineData,
                                      uint32_t *OffsetPtr) {
   const uint64_t PrologueOffset = *OffsetPtr;
@@ -90,6 +220,11 @@ bool DWARFDebugLine::Prologue::parse(DataExtractor DebugLineData,
   if (Version < 2)
     return false;
 
+  if (Version >= 5) {
+    AddressSize = DebugLineData.getU8(OffsetPtr);
+    SegSelectorSize = DebugLineData.getU8(OffsetPtr);
+  }
+
   PrologueLength = DebugLineData.getUnsigned(OffsetPtr, sizeofPrologueLength());
   const uint64_t EndPrologueOffset = PrologueLength + *OffsetPtr;
   MinInstLength = DebugLineData.getU8(OffsetPtr);
@@ -106,27 +241,18 @@ bool DWARFDebugLine::Prologue::parse(DataExtractor DebugLineData,
     StandardOpcodeLengths.push_back(OpLen);
   }
 
-  while (*OffsetPtr < EndPrologueOffset) {
-    const char *S = DebugLineData.getCStr(OffsetPtr);
-    if (S && S[0])
-      IncludeDirectories.push_back(S);
-    else
-      break;
-  }
-
-  while (*OffsetPtr < EndPrologueOffset) {
-    const char *Name = DebugLineData.getCStr(OffsetPtr);
-    if (Name && Name[0]) {
-      FileNameEntry FileEntry;
-      FileEntry.Name = Name;
-      FileEntry.DirIdx = DebugLineData.getULEB128(OffsetPtr);
-      FileEntry.ModTime = DebugLineData.getULEB128(OffsetPtr);
-      FileEntry.Length = DebugLineData.getULEB128(OffsetPtr);
-      FileNames.push_back(FileEntry);
-    } else {
-      break;
+  if (Version >= 5) {
+    if (!parseV5DirFileTables(DebugLineData, OffsetPtr, EndPrologueOffset,
+                              IncludeDirectories, FileNames)) {
+      fprintf(stderr,
+              "warning: parsing line table prologue at 0x%8.8" PRIx64
+              " found an invalid directory or file table description at"
+              " 0x%8.8" PRIx64 "\n", PrologueOffset, (uint64_t)*OffsetPtr);
+      return false;
     }
-  }
+  } else
+    parseV2DirFileTables(DebugLineData, OffsetPtr, EndPrologueOffset,
+                         IncludeDirectories, FileNames);
 
   if (*OffsetPtr != EndPrologueOffset) {
     fprintf(stderr,
@@ -161,6 +287,12 @@ void DWARFDebugLine::Row::reset(bool DefaultIsStmt) {
   EpilogueBegin = false;
 }
 
+void DWARFDebugLine::Row::dumpTableHeader(raw_ostream &OS) {
+  OS << "Address            Line   Column File   ISA Discriminator Flags\n"
+     << "------------------ ------ ------ ------ --- ------------- "
+        "-------------\n";
+}
+
 void DWARFDebugLine::Row::dump(raw_ostream &OS) const {
   OS << format("0x%16.16" PRIx64 " %6u %6u", Address, Line, Column)
      << format(" %6u %3u %13u ", File, Isa, Discriminator)
@@ -187,9 +319,7 @@ void DWARFDebugLine::LineTable::dump(raw_ostream &OS) const {
   OS << '\n';
 
   if (!Rows.empty()) {
-    OS << "Address            Line   Column File   ISA Discriminator Flags\n"
-       << "------------------ ------ ------ ------ --- ------------- "
-          "-------------\n";
+    Row::dumpTableHeader(OS);
     for (const Row &R : Rows) {
       R.dump(OS);
     }
@@ -637,7 +767,7 @@ bool DWARFDebugLine::LineTable::getFileNameByIndex(uint64_t FileIndex,
   if (Kind == FileLineInfoKind::None || !hasFileAtIndex(FileIndex))
     return false;
   const FileNameEntry &Entry = Prologue.FileNames[FileIndex - 1];
-  const char *FileName = Entry.Name;
+  StringRef FileName = Entry.Name;
   if (Kind != FileLineInfoKind::AbsoluteFilePath ||
       sys::path::is_absolute(FileName)) {
     Result = FileName;
@@ -646,7 +776,7 @@ bool DWARFDebugLine::LineTable::getFileNameByIndex(uint64_t FileIndex,
 
   SmallString<16> FilePath;
   uint64_t IncludeDirIndex = Entry.DirIdx;
-  const char *IncludeDir = "";
+  StringRef IncludeDir;
   // Be defensive about the contents of Entry.
   if (IncludeDirIndex > 0 &&
       IncludeDirIndex <= Prologue.IncludeDirectories.size())
diff --git a/lib/DebugInfo/DWARF/DWARFVerifier.cpp b/lib/DebugInfo/DWARF/DWARFVerifier.cpp
new file mode 100644
index 0000000000000..9494e876da155
--- /dev/null
+++ b/lib/DebugInfo/DWARF/DWARFVerifier.cpp
@@ -0,0 +1,277 @@
+//===- DWARFVerifier.cpp --------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/DebugInfo/DWARF/DWARFVerifier.h"
+#include "llvm/DebugInfo/DWARF/DWARFCompileUnit.h"
+#include "llvm/DebugInfo/DWARF/DWARFContext.h"
+#include "llvm/DebugInfo/DWARF/DWARFDebugLine.h"
+#include "llvm/DebugInfo/DWARF/DWARFDie.h"
+#include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
+#include "llvm/DebugInfo/DWARF/DWARFSection.h"
+#include "llvm/Support/raw_ostream.h"
+#include <map>
+#include <set>
+#include <vector>
+
+using namespace llvm;
+using namespace dwarf;
+using namespace object;
+
+void DWARFVerifier::verifyDebugInfoAttribute(DWARFDie &Die,
+                                             DWARFAttribute &AttrValue) {
+  const auto Attr = AttrValue.Attr;
+  switch (Attr) {
+  case DW_AT_ranges:
+    // Make sure the offset in the DW_AT_ranges attribute is valid.
+    if (auto SectionOffset = AttrValue.Value.getAsSectionOffset()) {
+      if (*SectionOffset >= DCtx.getRangeSection().Data.size()) {
+        ++NumDebugInfoErrors;
+        OS << "error: DW_AT_ranges offset is beyond .debug_ranges "
+              "bounds:\n";
+        Die.dump(OS, 0);
+        OS << "\n";
+      }
+    } else {
+      ++NumDebugInfoErrors;
+      OS << "error: DIE has invalid DW_AT_ranges encoding:\n";
+      Die.dump(OS, 0);
+      OS << "\n";
+    }
+    break;
+  case DW_AT_stmt_list:
+    // Make sure the offset in the DW_AT_stmt_list attribute is valid.
+    if (auto SectionOffset = AttrValue.Value.getAsSectionOffset()) {
+      if (*SectionOffset >= DCtx.getLineSection().Data.size()) {
+        ++NumDebugInfoErrors;
+        OS << "error: DW_AT_stmt_list offset is beyond .debug_line "
+              "bounds: "
+           << format("0x%08" PRIx32, *SectionOffset) << "\n";
+        Die.dump(OS, 0);
+        OS << "\n";
+      }
+    } else {
+      ++NumDebugInfoErrors;
+      OS << "error: DIE has invalid DW_AT_stmt_list encoding:\n";
+      Die.dump(OS, 0);
+      OS << "\n";
+    }
+    break;
+
+  default:
+    break;
+  }
+}
+
+void DWARFVerifier::verifyDebugInfoForm(DWARFDie &Die,
+                                        DWARFAttribute &AttrValue) {
+  const auto Form = AttrValue.Value.getForm();
+  switch (Form) {
+  case DW_FORM_ref1:
+  case DW_FORM_ref2:
+  case DW_FORM_ref4:
+  case DW_FORM_ref8:
+  case DW_FORM_ref_udata: {
+    // Verify all CU relative references are valid CU offsets.
+    Optional<uint64_t> RefVal = AttrValue.Value.getAsReference();
+    assert(RefVal);
+    if (RefVal) {
+      auto DieCU = Die.getDwarfUnit();
+      auto CUSize = DieCU->getNextUnitOffset() - DieCU->getOffset();
+      auto CUOffset = AttrValue.Value.getRawUValue();
+      if (CUOffset >= CUSize) {
+        ++NumDebugInfoErrors;
+        OS << "error: " << FormEncodingString(Form) << " CU offset "
+           << format("0x%08" PRIx32, CUOffset)
+           << " is invalid (must be less than CU size of "
+           << format("0x%08" PRIx32, CUSize) << "):\n";
+        Die.dump(OS, 0);
+        OS << "\n";
+      } else {
+        // Valid reference, but we will verify it points to an actual
+        // DIE later.
+        ReferenceToDIEOffsets[*RefVal].insert(Die.getOffset());
+      }
+    }
+    break;
+  }
+  case DW_FORM_ref_addr: {
+    // Verify all absolute DIE references have valid offsets in the
+    // .debug_info section.
+    Optional<uint64_t> RefVal = AttrValue.Value.getAsReference();
+    assert(RefVal);
+    if (RefVal) {
+      if (*RefVal >= DCtx.getInfoSection().Data.size()) {
+        ++NumDebugInfoErrors;
+        OS << "error: DW_FORM_ref_addr offset beyond .debug_info "
+              "bounds:\n";
+        Die.dump(OS, 0);
+        OS << "\n";
+      } else {
+        // Valid reference, but we will verify it points to an actual
+        // DIE later.
+        ReferenceToDIEOffsets[*RefVal].insert(Die.getOffset());
+      }
+    }
+    break;
+  }
+  case DW_FORM_strp: {
+    auto SecOffset = AttrValue.Value.getAsSectionOffset();
+    assert(SecOffset); // DW_FORM_strp is a section offset.
+    if (SecOffset && *SecOffset >= DCtx.getStringSection().size()) {
+      ++NumDebugInfoErrors;
+      OS << "error: DW_FORM_strp offset beyond .debug_str bounds:\n";
+      Die.dump(OS, 0);
+      OS << "\n";
+    }
+    break;
+  }
+  default:
+    break;
+  }
+}
+
+void DWARFVerifier::veifyDebugInfoReferences() {
+  // Take all references and make sure they point to an actual DIE by
+  // getting the DIE by offset and emitting an error
+  OS << "Verifying .debug_info references...\n";
+  for (auto Pair : ReferenceToDIEOffsets) {
+    auto Die = DCtx.getDIEForOffset(Pair.first);
+    if (Die)
+      continue;
+    ++NumDebugInfoErrors;
+    OS << "error: invalid DIE reference " << format("0x%08" PRIx64, Pair.first)
+       << ". Offset is in between DIEs:\n";
+    for (auto Offset : Pair.second) {
+      auto ReferencingDie = DCtx.getDIEForOffset(Offset);
+      ReferencingDie.dump(OS, 0);
+      OS << "\n";
+    }
+    OS << "\n";
+  }
+}
+
+bool DWARFVerifier::handleDebugInfo() {
+  NumDebugInfoErrors = 0;
+  OS << "Verifying .debug_info...\n";
+  for (const auto &CU : DCtx.compile_units()) {
+    unsigned NumDies = CU->getNumDIEs();
+    for (unsigned I = 0; I < NumDies; ++I) {
+      auto Die = CU->getDIEAtIndex(I);
+      const auto Tag = Die.getTag();
+      if (Tag == DW_TAG_null)
+        continue;
+      for (auto AttrValue : Die.attributes()) {
+        verifyDebugInfoAttribute(Die, AttrValue);
+        verifyDebugInfoForm(Die, AttrValue);
+      }
+    }
+  }
+  veifyDebugInfoReferences();
+  return NumDebugInfoErrors == 0;
+}
+
+void DWARFVerifier::verifyDebugLineStmtOffsets() {
+  std::map<uint64_t, DWARFDie> StmtListToDie;
+  for (const auto &CU : DCtx.compile_units()) {
+    auto Die = CU->getUnitDIE();
+    // Get the attribute value as a section offset. No need to produce an
+    // error here if the encoding isn't correct because we validate this in
+    // the .debug_info verifier.
+    auto StmtSectionOffset = toSectionOffset(Die.find(DW_AT_stmt_list));
+    if (!StmtSectionOffset)
+      continue;
+    const uint32_t LineTableOffset = *StmtSectionOffset;
+    auto LineTable = DCtx.getLineTableForUnit(CU.get());
+    if (LineTableOffset < DCtx.getLineSection().Data.size()) {
+      if (!LineTable) {
+        ++NumDebugLineErrors;
+        OS << "error: .debug_line[" << format("0x%08" PRIx32, LineTableOffset)
+           << "] was not able to be parsed for CU:\n";
+        Die.dump(OS, 0);
+        OS << '\n';
+        continue;
+      }
+    } else {
+      // Make sure we don't get a valid line table back if the offset is wrong.
+      assert(LineTable == nullptr);
+      // Skip this line table as it isn't valid. No need to create an error
+      // here because we validate this in the .debug_info verifier.
+      continue;
+    }
+    auto Iter = StmtListToDie.find(LineTableOffset);
+    if (Iter != StmtListToDie.end()) {
+      ++NumDebugLineErrors;
+      OS << "error: two compile unit DIEs, "
+         << format("0x%08" PRIx32, Iter->second.getOffset()) << " and "
+         << format("0x%08" PRIx32, Die.getOffset())
+         << ", have the same DW_AT_stmt_list section offset:\n";
+      Iter->second.dump(OS, 0);
+      Die.dump(OS, 0);
+      OS << '\n';
+      // Already verified this line table before, no need to do it again.
+      continue;
+    }
+    StmtListToDie[LineTableOffset] = Die;
+  }
+}
+
+void DWARFVerifier::verifyDebugLineRows() {
+  for (const auto &CU : DCtx.compile_units()) {
+    auto Die = CU->getUnitDIE();
+    auto LineTable = DCtx.getLineTableForUnit(CU.get());
+    // If there is no line table we will have created an error in the
+    // .debug_info verifier or in verifyDebugLineStmtOffsets().
+    if (!LineTable)
+      continue;
+    uint32_t MaxFileIndex = LineTable->Prologue.FileNames.size();
+    uint64_t PrevAddress = 0;
+    uint32_t RowIndex = 0;
+    for (const auto &Row : LineTable->Rows) {
+      if (Row.Address < PrevAddress) {
+        ++NumDebugLineErrors;
+        OS << "error: .debug_line["
+           << format("0x%08" PRIx32,
+                     *toSectionOffset(Die.find(DW_AT_stmt_list)))
+           << "] row[" << RowIndex
+           << "] decreases in address from previous row:\n";
+
+        DWARFDebugLine::Row::dumpTableHeader(OS);
+        if (RowIndex > 0)
+          LineTable->Rows[RowIndex - 1].dump(OS);
+        Row.dump(OS);
+        OS << '\n';
+      }
+
+      if (Row.File > MaxFileIndex) {
+        ++NumDebugLineErrors;
+        OS << "error: .debug_line["
+           << format("0x%08" PRIx32,
+                     *toSectionOffset(Die.find(DW_AT_stmt_list)))
+           << "][" << RowIndex << "] has invalid file index " << Row.File
+           << " (valid values are [1," << MaxFileIndex << "]):\n";
+        DWARFDebugLine::Row::dumpTableHeader(OS);
+        Row.dump(OS);
+        OS << '\n';
+      }
+      if (Row.EndSequence)
+        PrevAddress = 0;
+      else
+        PrevAddress = Row.Address;
+      ++RowIndex;
+    }
+  }
+}
+
+bool DWARFVerifier::handleDebugLine() {
+  NumDebugLineErrors = 0;
+  OS << "Verifying .debug_line...\n";
+  verifyDebugLineStmtOffsets();
+  verifyDebugLineRows();
+  return NumDebugLineErrors == 0;
+}
diff --git a/lib/DebugInfo/PDB/CMakeLists.txt b/lib/DebugInfo/PDB/CMakeLists.txt
index bd35efb51c74e..e1753018c7df3 100644
--- a/lib/DebugInfo/PDB/CMakeLists.txt
+++ b/lib/DebugInfo/PDB/CMakeLists.txt
@@ -48,11 +48,11 @@ add_pdb_impl_folder(Native
   Native/NativeSession.cpp
   Native/PDBFile.cpp
   Native/PDBFileBuilder.cpp
+  Native/PDBStringTable.cpp
+  Native/PDBStringTableBuilder.cpp
   Native/PDBTypeServerHandler.cpp
   Native/PublicsStream.cpp
   Native/RawError.cpp
-  Native/StringTable.cpp
-  Native/StringTableBuilder.cpp
   Native/SymbolStream.cpp
   Native/TpiHashing.cpp
   Native/TpiStream.cpp
diff --git a/lib/DebugInfo/PDB/Native/DbiModuleDescriptorBuilder.cpp b/lib/DebugInfo/PDB/Native/DbiModuleDescriptorBuilder.cpp
index f994b4538ef08..867864e47dce5 100644
--- a/lib/DebugInfo/PDB/Native/DbiModuleDescriptorBuilder.cpp
+++ b/lib/DebugInfo/PDB/Native/DbiModuleDescriptorBuilder.cpp
@@ -89,6 +89,14 @@ uint32_t DbiModuleDescriptorBuilder::calculateSerializedLength() const {
   return alignTo(L + M + O, sizeof(uint32_t));
 }
 
+template <typename T> struct Foo {
+  explicit Foo(T &&Answer) : Answer(Answer) {}
+
+  T Answer;
+};
+
+template <typename T> Foo<T> makeFoo(T &&t) { return Foo<T>(std::move(t)); }
+
 void DbiModuleDescriptorBuilder::finalize() {
   Layout.FileNameOffs = 0; // TODO: Fix this
   Layout.Flags = 0;        // TODO: Fix this
diff --git a/lib/DebugInfo/PDB/Native/DbiStream.cpp b/lib/DebugInfo/PDB/Native/DbiStream.cpp
index 4802cc6e8197e..db703809f7c9c 100644
--- a/lib/DebugInfo/PDB/Native/DbiStream.cpp
+++ b/lib/DebugInfo/PDB/Native/DbiStream.cpp
@@ -146,7 +146,7 @@ Error DbiStream::reload() {
 
   if (ECSubstream.getLength() > 0) {
     BinaryStreamReader ECReader(ECSubstream);
-    if (auto EC = ECNames.load(ECReader))
+    if (auto EC = ECNames.reload(ECReader))
       return EC;
   }
 
diff --git a/lib/DebugInfo/PDB/Native/PDBFile.cpp b/lib/DebugInfo/PDB/Native/PDBFile.cpp
index 943e7fa13ab76..859295d2c7d33 100644
--- a/lib/DebugInfo/PDB/Native/PDBFile.cpp
+++ b/lib/DebugInfo/PDB/Native/PDBFile.cpp
@@ -15,9 +15,9 @@
 #include "llvm/DebugInfo/PDB/Native/DbiStream.h"
 #include "llvm/DebugInfo/PDB/Native/GlobalsStream.h"
 #include "llvm/DebugInfo/PDB/Native/InfoStream.h"
+#include "llvm/DebugInfo/PDB/Native/PDBStringTable.h"
 #include "llvm/DebugInfo/PDB/Native/PublicsStream.h"
 #include "llvm/DebugInfo/PDB/Native/RawError.h"
-#include "llvm/DebugInfo/PDB/Native/StringTable.h"
 #include "llvm/DebugInfo/PDB/Native/SymbolStream.h"
 #include "llvm/DebugInfo/PDB/Native/TpiStream.h"
 #include "llvm/Support/BinaryStream.h"
@@ -337,8 +337,8 @@ Expected<SymbolStream &> PDBFile::getPDBSymbolStream() {
   return *Symbols;
 }
 
-Expected<StringTable &> PDBFile::getStringTable() {
-  if (!Strings || !StringTableStream) {
+Expected<PDBStringTable &> PDBFile::getStringTable() {
+  if (!Strings) {
     auto IS = getPDBInfoStream();
     if (!IS)
       return IS.takeError();
@@ -350,12 +350,13 @@ Expected<StringTable &> PDBFile::getStringTable() {
     if (!NS)
       return NS.takeError();
 
+    auto N = llvm::make_unique<PDBStringTable>();
     BinaryStreamReader Reader(**NS);
-    auto N = llvm::make_unique<StringTable>();
-    if (auto EC = N->load(Reader))
+    if (auto EC = N->reload(Reader))
       return std::move(EC);
-    Strings = std::move(N);
+    assert(Reader.bytesRemaining() == 0);
     StringTableStream = std::move(*NS);
+    Strings = std::move(N);
   }
   return *Strings;
 }
@@ -389,7 +390,7 @@ bool PDBFile::hasPDBSymbolStream() {
 
 bool PDBFile::hasPDBTpiStream() const { return StreamTPI < getNumStreams(); }
 
-bool PDBFile::hasStringTable() {
+bool PDBFile::hasPDBStringTable() {
   auto IS = getPDBInfoStream();
   if (!IS)
     return false;
diff --git a/lib/DebugInfo/PDB/Native/PDBFileBuilder.cpp b/lib/DebugInfo/PDB/Native/PDBFileBuilder.cpp
index b3c84903bc7e7..4dd965c69071e 100644
--- a/lib/DebugInfo/PDB/Native/PDBFileBuilder.cpp
+++ b/lib/DebugInfo/PDB/Native/PDBFileBuilder.cpp
@@ -17,8 +17,8 @@
 #include "llvm/DebugInfo/PDB/Native/DbiStreamBuilder.h"
 #include "llvm/DebugInfo/PDB/Native/InfoStream.h"
 #include "llvm/DebugInfo/PDB/Native/InfoStreamBuilder.h"
+#include "llvm/DebugInfo/PDB/Native/PDBStringTableBuilder.h"
 #include "llvm/DebugInfo/PDB/Native/RawError.h"
-#include "llvm/DebugInfo/PDB/Native/StringTableBuilder.h"
 #include "llvm/DebugInfo/PDB/Native/TpiStream.h"
 #include "llvm/DebugInfo/PDB/Native/TpiStreamBuilder.h"
 #include "llvm/Support/BinaryStream.h"
@@ -67,7 +67,9 @@ TpiStreamBuilder &PDBFileBuilder::getIpiBuilder() {
   return *Ipi;
 }
 
-StringTableBuilder &PDBFileBuilder::getStringTableBuilder() { return Strings; }
+PDBStringTableBuilder &PDBFileBuilder::getStringTableBuilder() {
+  return Strings;
+}
 
 Error PDBFileBuilder::addNamedStream(StringRef Name, uint32_t Size) {
   auto ExpectedStream = Msf->addStream(Size);
@@ -78,9 +80,9 @@ Error PDBFileBuilder::addNamedStream(StringRef Name, uint32_t Size) {
 }
 
 Expected<msf::MSFLayout> PDBFileBuilder::finalizeMsfLayout() {
-  uint32_t StringTableSize = Strings.finalize();
+  uint32_t StringsLen = Strings.calculateSerializedSize();
 
-  if (auto EC = addNamedStream("/names", StringTableSize))
+  if (auto EC = addNamedStream("/names", StringsLen))
     return std::move(EC);
   if (auto EC = addNamedStream("/LinkInfo", 0))
     return std::move(EC);
@@ -107,6 +109,13 @@ Expected<msf::MSFLayout> PDBFileBuilder::finalizeMsfLayout() {
   return Msf->build();
 }
 
+Expected<uint32_t> PDBFileBuilder::getNamedStreamIndex(StringRef Name) const {
+  uint32_t SN = 0;
+  if (!NamedStreams.get(Name, SN))
+    return llvm::make_error<pdb::RawError>(raw_error_code::no_stream);
+  return SN;
+}
+
 Error PDBFileBuilder::commit(StringRef Filename) {
   auto ExpectedLayout = finalizeMsfLayout();
   if (!ExpectedLayout)
@@ -144,12 +153,12 @@ Error PDBFileBuilder::commit(StringRef Filename) {
       return EC;
   }
 
-  uint32_t StringTableStreamNo = 0;
-  if (!NamedStreams.get("/names", StringTableStreamNo))
-    return llvm::make_error<pdb::RawError>(raw_error_code::no_stream);
+  auto ExpectedSN = getNamedStreamIndex("/names");
+  if (!ExpectedSN)
+    return ExpectedSN.takeError();
 
   auto NS = WritableMappedBlockStream::createIndexedStream(Layout, Buffer,
-                                                           StringTableStreamNo);
+                                                           *ExpectedSN);
   BinaryStreamWriter NSWriter(*NS);
   if (auto EC = Strings.commit(NSWriter))
     return EC;
diff --git a/lib/DebugInfo/PDB/Native/PDBStringTable.cpp b/lib/DebugInfo/PDB/Native/PDBStringTable.cpp
new file mode 100644
index 0000000000000..e84573fe07b8e
--- /dev/null
+++ b/lib/DebugInfo/PDB/Native/PDBStringTable.cpp
@@ -0,0 +1,134 @@
+//===- PDBStringTable.cpp - PDB String Table ---------------------*- C++-*-===//
+//
+//                     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/PDBStringTable.h"
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/DebugInfo/MSF/MappedBlockStream.h"
+#include "llvm/DebugInfo/PDB/Native/Hash.h"
+#include "llvm/DebugInfo/PDB/Native/RawError.h"
+#include "llvm/DebugInfo/PDB/Native/RawTypes.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/Endian.h"
+
+using namespace llvm;
+using namespace llvm::support;
+using namespace llvm::pdb;
+
+uint32_t PDBStringTable::getByteSize() const { return ByteSize; }
+uint32_t PDBStringTable::getNameCount() const { return NameCount; }
+uint32_t PDBStringTable::getHashVersion() const { return Header->HashVersion; }
+uint32_t PDBStringTable::getSignature() const { return Header->Signature; }
+
+Error PDBStringTable::readHeader(BinaryStreamReader &Reader) {
+  if (auto EC = Reader.readObject(Header))
+    return EC;
+
+  if (Header->Signature != PDBStringTableSignature)
+    return make_error<RawError>(raw_error_code::corrupt_file,
+                                "Invalid hash table signature");
+  if (Header->HashVersion != 1 && Header->HashVersion != 2)
+    return make_error<RawError>(raw_error_code::corrupt_file,
+                                "Unsupported hash version");
+
+  assert(Reader.bytesRemaining() == 0);
+  return Error::success();
+}
+
+Error PDBStringTable::readStrings(BinaryStreamReader &Reader) {
+  BinaryStreamRef Stream;
+  if (auto EC = Reader.readStreamRef(Stream))
+    return EC;
+
+  if (auto EC = Strings.initialize(Stream)) {
+    return joinErrors(std::move(EC),
+                      make_error<RawError>(raw_error_code::corrupt_file,
+                                           "Invalid hash table byte length"));
+  }
+
+  assert(Reader.bytesRemaining() == 0);
+  return Error::success();
+}
+
+Error PDBStringTable::readHashTable(BinaryStreamReader &Reader) {
+  const support::ulittle32_t *HashCount;
+  if (auto EC = Reader.readObject(HashCount))
+    return EC;
+
+  if (auto EC = Reader.readArray(IDs, *HashCount)) {
+    return joinErrors(std::move(EC),
+                      make_error<RawError>(raw_error_code::corrupt_file,
+                                           "Could not read bucket array"));
+  }
+
+  return Error::success();
+}
+
+Error PDBStringTable::readEpilogue(BinaryStreamReader &Reader) {
+  if (auto EC = Reader.readInteger(NameCount))
+    return EC;
+
+  assert(Reader.bytesRemaining() == 0);
+  return Error::success();
+}
+
+Error PDBStringTable::reload(BinaryStreamReader &Reader) {
+
+  BinaryStreamReader SectionReader;
+
+  std::tie(SectionReader, Reader) = Reader.split(sizeof(PDBStringTableHeader));
+  if (auto EC = readHeader(SectionReader))
+    return EC;
+
+  std::tie(SectionReader, Reader) = Reader.split(Header->ByteSize);
+  if (auto EC = readStrings(SectionReader))
+    return EC;
+
+  // We don't know how long the hash table is until we parse it, so let the
+  // function responsible for doing that figure it out.
+  if (auto EC = readHashTable(Reader))
+    return EC;
+
+  std::tie(SectionReader, Reader) = Reader.split(sizeof(uint32_t));
+  if (auto EC = readEpilogue(SectionReader))
+    return EC;
+
+  assert(Reader.bytesRemaining() == 0);
+  return Error::success();
+}
+
+Expected<StringRef> PDBStringTable::getStringForID(uint32_t ID) const {
+  return Strings.getString(ID);
+}
+
+Expected<uint32_t> PDBStringTable::getIDForString(StringRef Str) const {
+  uint32_t Hash =
+      (Header->HashVersion == 1) ? hashStringV1(Str) : hashStringV2(Str);
+  size_t Count = IDs.size();
+  uint32_t Start = Hash % Count;
+  for (size_t I = 0; I < Count; ++I) {
+    // The hash is just a starting point for the search, but if it
+    // doesn't work we should find the string no matter what, because
+    // we iterate the entire array.
+    uint32_t Index = (Start + I) % Count;
+
+    uint32_t ID = IDs[Index];
+    auto ExpectedStr = getStringForID(ID);
+    if (!ExpectedStr)
+      return ExpectedStr.takeError();
+
+    if (*ExpectedStr == Str)
+      return ID;
+  }
+  return make_error<RawError>(raw_error_code::no_entry);
+}
+
+FixedStreamArray<support::ulittle32_t> PDBStringTable::name_ids() const {
+  return IDs;
+}
diff --git a/lib/DebugInfo/PDB/Native/PDBStringTableBuilder.cpp b/lib/DebugInfo/PDB/Native/PDBStringTableBuilder.cpp
new file mode 100644
index 0000000000000..a472181a4895c
--- /dev/null
+++ b/lib/DebugInfo/PDB/Native/PDBStringTableBuilder.cpp
@@ -0,0 +1,133 @@
+//===- PDBStringTableBuilder.cpp - PDB String Table -------------*- C++ -*-===//
+//
+//                     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/PDBStringTableBuilder.h"
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/DebugInfo/MSF/MappedBlockStream.h"
+#include "llvm/DebugInfo/PDB/Native/Hash.h"
+#include "llvm/DebugInfo/PDB/Native/PDBFileBuilder.h"
+#include "llvm/DebugInfo/PDB/Native/RawTypes.h"
+#include "llvm/Support/BinaryStreamWriter.h"
+#include "llvm/Support/Endian.h"
+
+using namespace llvm;
+using namespace llvm::msf;
+using namespace llvm::support;
+using namespace llvm::support::endian;
+using namespace llvm::pdb;
+
+uint32_t PDBStringTableBuilder::insert(StringRef S) {
+  return Strings.insert(S);
+}
+
+static uint32_t computeBucketCount(uint32_t NumStrings) {
+  // The /names stream is basically an on-disk open-addressing hash table.
+  // Hash collisions are resolved by linear probing. We cannot make
+  // utilization 100% because it will make the linear probing extremely
+  // slow. But lower utilization wastes disk space. As a reasonable
+  // load factor, we choose 80%. We need +1 because slot 0 is reserved.
+  return (NumStrings + 1) * 1.25;
+}
+
+uint32_t PDBStringTableBuilder::calculateHashTableSize() const {
+  uint32_t Size = sizeof(uint32_t); // Hash table begins with 4-byte size field.
+  Size += sizeof(uint32_t) * computeBucketCount(Strings.size());
+
+  return Size;
+}
+
+uint32_t PDBStringTableBuilder::calculateSerializedSize() const {
+  uint32_t Size = 0;
+  Size += sizeof(PDBStringTableHeader);
+  Size += Strings.calculateSerializedSize();
+  Size += calculateHashTableSize();
+  Size += sizeof(uint32_t); // The /names stream ends with the string count.
+  return Size;
+}
+
+Error PDBStringTableBuilder::writeHeader(BinaryStreamWriter &Writer) const {
+  // Write a header
+  PDBStringTableHeader H;
+  H.Signature = PDBStringTableSignature;
+  H.HashVersion = 1;
+  H.ByteSize = Strings.calculateSerializedSize();
+  if (auto EC = Writer.writeObject(H))
+    return EC;
+  assert(Writer.bytesRemaining() == 0);
+  return Error::success();
+}
+
+Error PDBStringTableBuilder::writeStrings(BinaryStreamWriter &Writer) const {
+  if (auto EC = Strings.commit(Writer))
+    return EC;
+
+  assert(Writer.bytesRemaining() == 0);
+  return Error::success();
+}
+
+Error PDBStringTableBuilder::writeHashTable(BinaryStreamWriter &Writer) const {
+  // Write a hash table.
+  uint32_t BucketCount = computeBucketCount(Strings.size());
+  if (auto EC = Writer.writeInteger(BucketCount))
+    return EC;
+  std::vector<ulittle32_t> Buckets(BucketCount);
+
+  for (auto &Pair : Strings) {
+    StringRef S = Pair.getKey();
+    uint32_t Offset = Pair.getValue();
+    uint32_t Hash = hashStringV1(S);
+
+    for (uint32_t I = 0; I != BucketCount; ++I) {
+      uint32_t Slot = (Hash + I) % BucketCount;
+      if (Slot == 0)
+        continue; // Skip reserved slot
+      if (Buckets[Slot] != 0)
+        continue;
+      Buckets[Slot] = Offset;
+      break;
+    }
+  }
+
+  if (auto EC = Writer.writeArray(ArrayRef<ulittle32_t>(Buckets)))
+    return EC;
+
+  assert(Writer.bytesRemaining() == 0);
+  return Error::success();
+}
+
+Error PDBStringTableBuilder::writeEpilogue(BinaryStreamWriter &Writer) const {
+  if (auto EC = Writer.writeInteger<uint32_t>(Strings.size()))
+    return EC;
+  assert(Writer.bytesRemaining() == 0);
+  return Error::success();
+}
+
+Error PDBStringTableBuilder::commit(BinaryStreamWriter &Writer) const {
+  BinaryStreamWriter SectionWriter;
+
+  std::tie(SectionWriter, Writer) = Writer.split(sizeof(PDBStringTableHeader));
+  if (auto EC = writeHeader(SectionWriter))
+    return EC;
+
+  std::tie(SectionWriter, Writer) =
+      Writer.split(Strings.calculateSerializedSize());
+  if (auto EC = writeStrings(SectionWriter))
+    return EC;
+
+  std::tie(SectionWriter, Writer) = Writer.split(calculateHashTableSize());
+  if (auto EC = writeHashTable(SectionWriter))
+    return EC;
+
+  std::tie(SectionWriter, Writer) = Writer.split(sizeof(uint32_t));
+  if (auto EC = writeEpilogue(SectionWriter))
+    return EC;
+
+  return Error::success();
+}
diff --git a/lib/DebugInfo/PDB/Native/StringTable.cpp b/lib/DebugInfo/PDB/Native/StringTable.cpp
deleted file mode 100644
index 7e28389b83831..0000000000000
--- a/lib/DebugInfo/PDB/Native/StringTable.cpp
+++ /dev/null
@@ -1,109 +0,0 @@
-//===- StringTable.cpp - PDB String Table -----------------------*- C++ -*-===//
-//
-//                     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/StringTable.h"
-
-#include "llvm/ADT/ArrayRef.h"
-#include "llvm/DebugInfo/PDB/Native/Hash.h"
-#include "llvm/DebugInfo/PDB/Native/RawError.h"
-#include "llvm/DebugInfo/PDB/Native/RawTypes.h"
-#include "llvm/Support/BinaryStreamReader.h"
-#include "llvm/Support/Endian.h"
-
-using namespace llvm;
-using namespace llvm::support;
-using namespace llvm::pdb;
-
-StringTable::StringTable() {}
-
-Error StringTable::load(BinaryStreamReader &Stream) {
-  ByteSize = Stream.getLength();
-
-  const StringTableHeader *H;
-  if (auto EC = Stream.readObject(H))
-    return EC;
-
-  if (H->Signature != StringTableSignature)
-    return make_error<RawError>(raw_error_code::corrupt_file,
-                                "Invalid hash table signature");
-  if (H->HashVersion != 1 && H->HashVersion != 2)
-    return make_error<RawError>(raw_error_code::corrupt_file,
-                                "Unsupported hash version");
-
-  Signature = H->Signature;
-  HashVersion = H->HashVersion;
-  if (auto EC = Stream.readStreamRef(NamesBuffer, H->ByteSize))
-    return joinErrors(std::move(EC),
-                      make_error<RawError>(raw_error_code::corrupt_file,
-                                           "Invalid hash table byte length"));
-
-  const support::ulittle32_t *HashCount;
-  if (auto EC = Stream.readObject(HashCount))
-    return EC;
-
-  if (auto EC = Stream.readArray(IDs, *HashCount))
-    return joinErrors(std::move(EC),
-                      make_error<RawError>(raw_error_code::corrupt_file,
-                                           "Could not read bucket array"));
-
-  if (Stream.bytesRemaining() < sizeof(support::ulittle32_t))
-    return make_error<RawError>(raw_error_code::corrupt_file,
-                                "Missing name count");
-
-  if (auto EC = Stream.readInteger(NameCount))
-    return EC;
-
-  if (Stream.bytesRemaining() > 0)
-    return make_error<RawError>(raw_error_code::stream_too_long,
-      "Unexpected bytes found in string table");
-
-  return Error::success();
-}
-
-uint32_t StringTable::getByteSize() const {
-  return ByteSize;
-}
-
-StringRef StringTable::getStringForID(uint32_t ID) const {
-  if (ID == IDs[0])
-    return StringRef();
-
-  // NamesBuffer is a buffer of null terminated strings back to back.  ID is
-  // the starting offset of the string we're looking for.  So just seek into
-  // the desired offset and a read a null terminated stream from that offset.
-  StringRef Result;
-  BinaryStreamReader NameReader(NamesBuffer);
-  NameReader.setOffset(ID);
-  if (auto EC = NameReader.readCString(Result))
-    consumeError(std::move(EC));
-  return Result;
-}
-
-uint32_t StringTable::getIDForString(StringRef Str) const {
-  uint32_t Hash = (HashVersion == 1) ? hashStringV1(Str) : hashStringV2(Str);
-  size_t Count = IDs.size();
-  uint32_t Start = Hash % Count;
-  for (size_t I = 0; I < Count; ++I) {
-    // The hash is just a starting point for the search, but if it
-    // doesn't work we should find the string no matter what, because
-    // we iterate the entire array.
-    uint32_t Index = (Start + I) % Count;
-
-    uint32_t ID = IDs[Index];
-    StringRef S = getStringForID(ID);
-    if (S == Str)
-      return ID;
-  }
-  // IDs[0] contains the ID of the "invalid" entry.
-  return IDs[0];
-}
-
-FixedStreamArray<support::ulittle32_t> StringTable::name_ids() const {
-  return IDs;
-}
diff --git a/lib/DebugInfo/PDB/Native/StringTableBuilder.cpp b/lib/DebugInfo/PDB/Native/StringTableBuilder.cpp
deleted file mode 100644
index 40dc8e1bfcb12..0000000000000
--- a/lib/DebugInfo/PDB/Native/StringTableBuilder.cpp
+++ /dev/null
@@ -1,108 +0,0 @@
-//===- StringTableBuilder.cpp - PDB String Table ----------------*- C++ -*-===//
-//
-//                     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/StringTableBuilder.h"
-#include "llvm/ADT/ArrayRef.h"
-#include "llvm/DebugInfo/PDB/Native/Hash.h"
-#include "llvm/DebugInfo/PDB/Native/RawTypes.h"
-#include "llvm/Support/BinaryStreamWriter.h"
-#include "llvm/Support/Endian.h"
-
-using namespace llvm;
-using namespace llvm::support;
-using namespace llvm::support::endian;
-using namespace llvm::pdb;
-
-uint32_t StringTableBuilder::insert(StringRef S) {
-  auto P = Strings.insert({S, StringSize});
-
-  // If a given string didn't exist in the string table, we want to increment
-  // the string table size.
-  if (P.second)
-    StringSize += S.size() + 1; // +1 for '\0'
-  return P.first->second;
-}
-
-uint32_t StringTableBuilder::getStringIndex(StringRef S) {
-  auto Iter = Strings.find(S);
-  assert(Iter != Strings.end());
-  return Iter->second;
-}
-
-static uint32_t computeBucketCount(uint32_t NumStrings) {
-  // The /names stream is basically an on-disk open-addressing hash table.
-  // Hash collisions are resolved by linear probing. We cannot make
-  // utilization 100% because it will make the linear probing extremely
-  // slow. But lower utilization wastes disk space. As a reasonable
-  // load factor, we choose 80%. We need +1 because slot 0 is reserved.
-  return (NumStrings + 1) * 1.25;
-}
-
-uint32_t StringTableBuilder::finalize() {
-  uint32_t Size = 0;
-  Size += sizeof(StringTableHeader);
-  Size += StringSize;
-  Size += sizeof(uint32_t); // Hash table begins with 4-byte size field.
-
-  uint32_t BucketCount = computeBucketCount(Strings.size());
-  Size += BucketCount * sizeof(uint32_t);
-
-  Size +=
-      sizeof(uint32_t); // The /names stream ends with the number of strings.
-  return Size;
-}
-
-Error StringTableBuilder::commit(BinaryStreamWriter &Writer) const {
-  // Write a header
-  StringTableHeader H;
-  H.Signature = StringTableSignature;
-  H.HashVersion = 1;
-  H.ByteSize = StringSize;
-  if (auto EC = Writer.writeObject(H))
-    return EC;
-
-  // Write a string table.
-  uint32_t StringStart = Writer.getOffset();
-  for (auto Pair : Strings) {
-    StringRef S = Pair.first;
-    uint32_t Offset = Pair.second;
-    Writer.setOffset(StringStart + Offset);
-    if (auto EC = Writer.writeCString(S))
-      return EC;
-  }
-  Writer.setOffset(StringStart + StringSize);
-
-  // Write a hash table.
-  uint32_t BucketCount = computeBucketCount(Strings.size());
-  if (auto EC = Writer.writeInteger(BucketCount))
-    return EC;
-  std::vector<ulittle32_t> Buckets(BucketCount);
-
-  for (auto Pair : Strings) {
-    StringRef S = Pair.first;
-    uint32_t Offset = Pair.second;
-    uint32_t Hash = hashStringV1(S);
-
-    for (uint32_t I = 0; I != BucketCount; ++I) {
-      uint32_t Slot = (Hash + I) % BucketCount;
-      if (Slot == 0)
-        continue; // Skip reserved slot
-      if (Buckets[Slot] != 0)
-        continue;
-      Buckets[Slot] = Offset;
-      break;
-    }
-  }
-
-  if (auto EC = Writer.writeArray(ArrayRef<ulittle32_t>(Buckets)))
-    return EC;
-  if (auto EC = Writer.writeInteger(static_cast<uint32_t>(Strings.size())))
-    return EC;
-  return Error::success();
-}