Reland r200340 - 'Add line table debug info to COFF files when using a win32 triple'

This incorporates a couple of fixes reviewed at http://llvm-reviews.chandlerc.com/D2651

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200440 91177308-0d34-0410-b5e6-96231b3b80d8

7 files changed, 514 insertions, 28 deletions

diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index fbee17f563..c5726633d2 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -50,11 +50,13 @@
 #include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/Target/TargetSubtargetInfo.h"
 #include "llvm/Transforms/Utils/GlobalStatus.h"
+#include "WinCodeViewLineTables.h"
 using namespace llvm;
 
 static const char *const DWARFGroupName = "DWARF Emission";
-static const char *const DbgTimerName = "DWARF Debug Writer";
+static const char *const DbgTimerName = "Debug Info Emission";
 static const char *const EHTimerName = "DWARF Exception Writer";
+static const char *const CodeViewLineTablesGroupName = "CodeView Line Tables";
 
 STATISTIC(EmittedInsts, "Number of machine instrs printed");
 
@@ -202,8 +204,14 @@ bool AsmPrinter::doInitialization(Module &M) {
   }
 
   if (MAI->doesSupportDebugInformation()) {
-    DD = new DwarfDebug(this, &M);
-    Handlers.push_back(HandlerInfo(DD, DbgTimerName, DWARFGroupName));
+    if (Triple(TM.getTargetTriple()).getOS() == Triple::Win32) {
+      Handlers.push_back(HandlerInfo(new WinCodeViewLineTables(this),
+                                     DbgTimerName,
+                                     CodeViewLineTablesGroupName));
+    } else {
+      DD = new DwarfDebug(this, &M);
+      Handlers.push_back(HandlerInfo(DD, DbgTimerName, DWARFGroupName));
+    }
   }
 
   DwarfException *DE = 0;
diff --git a/lib/CodeGen/AsmPrinter/CMakeLists.txt b/lib/CodeGen/AsmPrinter/CMakeLists.txt
index 2ad24e1af9..b3eddac191 100644
--- a/lib/CodeGen/AsmPrinter/CMakeLists.txt
+++ b/lib/CodeGen/AsmPrinter/CMakeLists.txt
@@ -13,6 +13,7 @@ add_llvm_library(LLVMAsmPrinter
   ErlangGCPrinter.cpp
   OcamlGCPrinter.cpp
   Win64Exception.cpp
+  WinCodeViewLineTables.cpp
   )
 
 add_dependencies(LLVMAsmPrinter intrinsics_gen)
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 43297d23db..e4188c39b0 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -1527,30 +1527,6 @@ void DwarfDebug::identifyScopeMarkers() {
   }
 }
 
-// Get MDNode for DebugLoc's scope.
-static MDNode *getScopeNode(DebugLoc DL, const LLVMContext &Ctx) {
-  if (MDNode *InlinedAt = DL.getInlinedAt(Ctx))
-    return getScopeNode(DebugLoc::getFromDILocation(InlinedAt), Ctx);
-  return DL.getScope(Ctx);
-}
-
-// Walk up the scope chain of given debug loc and find line number info
-// for the function.
-static DebugLoc getFnDebugLoc(DebugLoc DL, const LLVMContext &Ctx) {
-  const MDNode *Scope = getScopeNode(DL, Ctx);
-  DISubprogram SP = getDISubprogram(Scope);
-  if (SP.isSubprogram()) {
-    // Check for number of operands since the compatibility is
-    // cheap here.
-    if (SP->getNumOperands() > 19)
-      return DebugLoc::get(SP.getScopeLineNumber(), 0, SP);
-    else
-      return DebugLoc::get(SP.getLineNumber(), 0, SP);
-  }
-
-  return DebugLoc();
-}
-
 // Gather pre-function debug information.  Assumes being called immediately
 // after the function entry point has been emitted.
 void DwarfDebug::beginFunction(const MachineFunction *MF) {
@@ -1745,7 +1721,7 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
   // Record beginning of function.
   if (!PrologEndLoc.isUnknown()) {
     DebugLoc FnStartDL =
-        getFnDebugLoc(PrologEndLoc, MF->getFunction()->getContext());
+        PrologEndLoc.getFnDebugLoc(MF->getFunction()->getContext());
     recordSourceLine(
         FnStartDL.getLine(), FnStartDL.getCol(),
         FnStartDL.getScope(MF->getFunction()->getContext()),
diff --git a/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp b/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp
new file mode 100644
index 0000000000..bb8b0735e5
--- /dev/null
+++ b/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp
@@ -0,0 +1,333 @@
+//===-- llvm/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp --*- C++ -*--===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains support for writing line tables info into COFF files.
+//
+//===----------------------------------------------------------------------===//
+
+#include "WinCodeViewLineTables.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCSymbol.h"
+#include "llvm/Support/COFF.h"
+
+namespace llvm {
+
+StringRef WinCodeViewLineTables::getFullFilepath(const MDNode *S) {
+  assert(S);
+  DIDescriptor D(S);
+  assert((D.isCompileUnit() || D.isFile() || D.isSubprogram() ||
+          D.isLexicalBlockFile() || D.isLexicalBlock()) &&
+         "Unexpected scope info");
+
+  DIScope Scope(S);
+  StringRef Dir = Scope.getDirectory(),
+            Filename = Scope.getFilename();
+  char *&Result = DirAndFilenameToFilepathMap[std::make_pair(Dir, Filename)];
+  if (Result != 0)
+    return Result;
+
+  // Clang emits directory and relative filename info into the IR, but CodeView
+  // operates on full paths.  We could change Clang to emit full paths too, but
+  // that would increase the IR size and probably not needed for other users.
+  // For now, just concatenate and canonicalize the path here.
+  std::string Filepath;
+  if (Filename.find(':') == 1)
+    Filepath = Filename;
+  else
+    Filepath = (Dir + Twine("\\") + Filename).str();
+
+  // Canonicalize the path.  We have to do it textually because we may no longer
+  // have access the file in the filesystem.
+  // First, replace all slashes with backslashes.
+  std::replace(Filepath.begin(), Filepath.end(), '/', '\\');
+
+  // Remove all "\.\" with "\".
+  size_t Cursor = 0;
+  while ((Cursor = Filepath.find("\\.\\", Cursor)) != std::string::npos)
+    Filepath.erase(Cursor, 2);
+
+  // Replace all "\XXX\..\" with "\".  Don't try too hard though as the original
+  // path should be well-formatted, e.g. start with a drive letter, etc.
+  Cursor = 0;
+  while ((Cursor = Filepath.find("\\..\\", Cursor)) != std::string::npos) {
+    // Something's wrong if the path starts with "\..\", abort.
+    if (Cursor == 0)
+      break;
+
+    size_t PrevSlash = Filepath.rfind('\\', Cursor - 1);
+    if (PrevSlash == std::string::npos)
+      // Something's wrong, abort.
+      break;
+
+    Filepath.erase(PrevSlash, Cursor + 3 - PrevSlash);
+    // The next ".." might be following the one we've just erased.
+    Cursor = PrevSlash;
+  }
+
+  // Remove all duplicate backslashes.
+  Cursor = 0;
+  while ((Cursor = Filepath.find("\\\\", Cursor)) != std::string::npos)
+    Filepath.erase(Cursor, 1);
+
+  Result = strdup(Filepath.c_str());
+  return StringRef(Result);
+}
+
+void WinCodeViewLineTables::maybeRecordLocation(DebugLoc DL,
+                                                const MachineFunction *MF) {
+  const MDNode *Scope = DL.getScope(MF->getFunction()->getContext());
+  if (!Scope)
+    return;
+  StringRef Filename = getFullFilepath(Scope);
+
+  // Skip this instruction if it has the same file:line as the previous one.
+  assert(CurFn);
+  if (!CurFn->Instrs.empty()) {
+    const InstrInfoTy &LastInstr = InstrInfo[CurFn->Instrs.back()];
+    if (LastInstr.Filename == Filename && LastInstr.LineNumber == DL.getLine())
+      return;
+  }
+  FileNameRegistry.add(Filename);
+
+  MCSymbol *MCL = Asm->MMI->getContext().CreateTempSymbol();
+  Asm->OutStreamer.EmitLabel(MCL);
+  CurFn->Instrs.push_back(MCL);
+  InstrInfo[MCL] = InstrInfoTy(Filename, DL.getLine());
+}
+
+WinCodeViewLineTables::WinCodeViewLineTables(AsmPrinter *AP)
+    : Asm(0), CurFn(0) {
+  MachineModuleInfo *MMI = AP->MMI;
+
+  // If module doesn't have named metadata anchors or COFF debug section
+  // is not available, skip any debug info related stuff.
+  if (!MMI->getModule()->getNamedMetadata("llvm.dbg.cu") ||
+      !AP->getObjFileLowering().getCOFFDebugSymbolsSection())
+    return;
+
+  // Tell MMI that we have debug info.
+  MMI->setDebugInfoAvailability(true);
+  Asm = AP;
+}
+
+static void EmitLabelDiff(MCStreamer &Streamer,
+                          const MCSymbol *From, const MCSymbol *To) {
+  MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
+  MCContext &Context = Streamer.getContext();
+  const MCExpr *FromRef = MCSymbolRefExpr::Create(From, Variant, Context),
+               *ToRef   = MCSymbolRefExpr::Create(To, Variant, Context);
+  const MCExpr *AddrDelta =
+      MCBinaryExpr::Create(MCBinaryExpr::Sub, ToRef, FromRef, Context);
+  Streamer.EmitValue(AddrDelta, 4);
+}
+
+void WinCodeViewLineTables::emitDebugInfoForFunction(const Function *GV) {
+  // For each function there is a separate subsection
+  // which holds the PC to file:line table.
+  const MCSymbol *Fn = Asm->getSymbol(GV);
+  const FunctionInfo &FI = FnDebugInfo[GV];
+  assert(Fn);
+  assert(FI.Instrs.size() > 0);
+
+  // PCs/Instructions are grouped into segments sharing the same filename.
+  // Pre-calculate the lengths (in instructions) of these segments and store
+  // them in a map for convenience.  Each index in the map is the sequential
+  // number of the respective instruction that starts a new segment.
+  DenseMap<size_t, size_t> FilenameSegmentLengths;
+  size_t LastSegmentEnd = 0;
+  StringRef PrevFilename = InstrInfo[FI.Instrs[0]].Filename;
+  for (size_t J = 1, F = FI.Instrs.size(); J != F; ++J) {
+    if (PrevFilename == InstrInfo[FI.Instrs[J]].Filename)
+      continue;
+    FilenameSegmentLengths[LastSegmentEnd] = J - LastSegmentEnd;
+    LastSegmentEnd = J;
+    PrevFilename = InstrInfo[FI.Instrs[J]].Filename;
+  }
+  FilenameSegmentLengths[LastSegmentEnd] = FI.Instrs.size() - LastSegmentEnd;
+
+  // Emit the control code of the subsection followed by the payload size.
+  Asm->OutStreamer.AddComment(
+      "Linetable subsection for " + Twine(Fn->getName()));
+  Asm->EmitInt32(COFF::DEBUG_LINE_TABLE_SUBSECTION);
+  MCSymbol *SubsectionBegin = Asm->MMI->getContext().CreateTempSymbol(),
+           *SubsectionEnd = Asm->MMI->getContext().CreateTempSymbol();
+  EmitLabelDiff(Asm->OutStreamer, SubsectionBegin, SubsectionEnd);
+  Asm->OutStreamer.EmitLabel(SubsectionBegin);
+
+  // Identify the function this subsection is for.
+  Asm->OutStreamer.EmitCOFFSecRel32(Fn);
+  Asm->OutStreamer.EmitCOFFSectionIndex(Fn);
+
+  // Length of the function's code, in bytes.
+  EmitLabelDiff(Asm->OutStreamer, Fn, FI.End);
+
+  // PC-to-linenumber lookup table:
+  MCSymbol *FileSegmentEnd = 0;
+  for (size_t J = 0, F = FI.Instrs.size(); J != F; ++J) {
+    MCSymbol *Instr = FI.Instrs[J];
+    assert(InstrInfo.count(Instr));
+
+    if (FilenameSegmentLengths.count(J)) {
+      // We came to a beginning of a new filename segment.
+      if (FileSegmentEnd)
+        Asm->OutStreamer.EmitLabel(FileSegmentEnd);
+      StringRef CurFilename = InstrInfo[FI.Instrs[J]].Filename;
+      assert(FileNameRegistry.Infos.count(CurFilename));
+      size_t IndexInStringTable =
+          FileNameRegistry.Infos[CurFilename].FilenameID;
+      // Each segment starts with the offset of the filename
+      // in the string table.
+      Asm->OutStreamer.AddComment(
+          "Segment for file '" + Twine(CurFilename) + "' begins");
+      MCSymbol *FileSegmentBegin = Asm->MMI->getContext().CreateTempSymbol();
+      Asm->OutStreamer.EmitLabel(FileSegmentBegin);
+      Asm->EmitInt32(8 * IndexInStringTable);
+
+      // Number of PC records in the lookup table.
+      size_t SegmentLength = FilenameSegmentLengths[J];
+      Asm->EmitInt32(SegmentLength);
+
+      // Full size of the segment for this filename, including the prev two
+      // records.
+      FileSegmentEnd = Asm->MMI->getContext().CreateTempSymbol();
+      EmitLabelDiff(Asm->OutStreamer, FileSegmentBegin, FileSegmentEnd);
+    }
+
+    // The first PC with the given linenumber and the linenumber itself.
+    EmitLabelDiff(Asm->OutStreamer, Fn, Instr);
+    Asm->EmitInt32(InstrInfo[Instr].LineNumber);
+  }
+
+  if (FileSegmentEnd)
+    Asm->OutStreamer.EmitLabel(FileSegmentEnd);
+  Asm->OutStreamer.EmitLabel(SubsectionEnd);
+}
+
+void WinCodeViewLineTables::endModule() {
+  if (FnDebugInfo.empty())
+    return;
+
+  assert(Asm != 0);
+  Asm->OutStreamer.SwitchSection(
+      Asm->getObjFileLowering().getCOFFDebugSymbolsSection());
+  Asm->EmitInt32(COFF::DEBUG_SECTION_MAGIC);
+
+  // The COFF .debug$S section consists of several subsections, each starting
+  // with a 4-byte control code (e.g. 0xF1, 0xF2, etc) and then a 4-byte length
+  // of the payload followed by the payload itself.  The subsections are 4-byte
+  // aligned.
+
+  for (size_t I = 0, E = VisitedFunctions.size(); I != E; ++I)
+    emitDebugInfoForFunction(VisitedFunctions[I]);
+
+  // This subsection holds a file index to offset in string table table.
+  Asm->OutStreamer.AddComment("File index to string table offset subsection");
+  Asm->EmitInt32(COFF::DEBUG_INDEX_SUBSECTION);
+  size_t NumFilenames = FileNameRegistry.Infos.size();
+  Asm->EmitInt32(8 * NumFilenames);
+  for (size_t I = 0, E = FileNameRegistry.Filenames.size(); I != E; ++I) {
+    StringRef Filename = FileNameRegistry.Filenames[I];
+    // For each unique filename, just write it's offset in the string table.
+    Asm->EmitInt32(FileNameRegistry.Infos[Filename].StartOffset);
+    // The function name offset is not followed by any additional data.
+    Asm->EmitInt32(0);
+  }
+
+  // This subsection holds the string table.
+  Asm->OutStreamer.AddComment("String table");
+  Asm->EmitInt32(COFF::DEBUG_STRING_TABLE_SUBSECTION);
+  Asm->EmitInt32(FileNameRegistry.LastOffset);
+  // The payload starts with a null character.
+  Asm->EmitInt8(0);
+
+  for (size_t I = 0, E = FileNameRegistry.Filenames.size(); I != E; ++I) {
+    // Just emit unique filenames one by one, separated by a null character.
+    Asm->OutStreamer.EmitBytes(FileNameRegistry.Filenames[I]);
+    Asm->EmitInt8(0);
+  }
+
+  // No more subsections. Fill with zeros to align the end of the section by 4.
+  Asm->OutStreamer.EmitFill((-FileNameRegistry.LastOffset) % 4, 0);
+
+  clear();
+}
+
+void WinCodeViewLineTables::beginFunction(const MachineFunction *MF) {
+  assert(!CurFn && "Can't process two functions at once!");
+
+  if (!Asm || !Asm->MMI->hasDebugInfo())
+    return;
+
+  // Grab the lexical scopes for the function, if we don't have any of those
+  // then we're not going to be able to do anything.
+  LScopes.initialize(*MF);
+  if (LScopes.empty())
+    return;
+
+  const Function *GV = MF->getFunction();
+  assert(FnDebugInfo.count(GV) == false);
+  VisitedFunctions.push_back(GV);
+  CurFn = &FnDebugInfo[GV];
+
+  // Find the end of the function prolog.
+  // FIXME: is there a simpler a way to do this? Can we just search
+  // for the first instruction of the function, not the last of the prolog?
+  DebugLoc PrologEndLoc;
+  bool EmptyPrologue = true;
+  for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
+       I != E && PrologEndLoc.isUnknown(); ++I) {
+    for (MachineBasicBlock::const_iterator II = I->begin(), IE = I->end();
+         II != IE; ++II) {
+      const MachineInstr *MI = II;
+      if (MI->isDebugValue())
+        continue;
+
+      // First known non-DBG_VALUE and non-frame setup location marks
+      // the beginning of the function body.
+      // FIXME: do we need the first subcondition?
+      if (!MI->getFlag(MachineInstr::FrameSetup) &&
+          (!MI->getDebugLoc().isUnknown())) {
+        PrologEndLoc = MI->getDebugLoc();
+        break;
+      }
+      EmptyPrologue = false;
+    }
+  }
+  // Record beginning of function if we have a non-empty prologue.
+  if (!PrologEndLoc.isUnknown() && !EmptyPrologue) {
+    DebugLoc FnStartDL =
+        PrologEndLoc.getFnDebugLoc(MF->getFunction()->getContext());
+    maybeRecordLocation(FnStartDL, MF);
+  }
+}
+
+void WinCodeViewLineTables::endFunction(const MachineFunction *) {
+  if (!Asm || !CurFn)  // We haven't created any debug info for this function.
+    return;
+
+  if (CurFn->Instrs.empty())
+    llvm_unreachable("Can this ever happen?");
+
+  // Define end label for subprogram.
+  MCSymbol *FunctionEndSym = Asm->OutStreamer.getContext().CreateTempSymbol();
+  Asm->OutStreamer.EmitLabel(FunctionEndSym);
+  CurFn->End = FunctionEndSym;
+  CurFn = 0;
+}
+
+void WinCodeViewLineTables::beginInstruction(const MachineInstr *MI) {
+  // Ignore DBG_VALUE locations and function prologue.
+  if (!Asm || MI->isDebugValue() || MI->getFlag(MachineInstr::FrameSetup))
+    return;
+  DebugLoc DL = MI->getDebugLoc();
+  if (DL == PrevInstLoc || DL.isUnknown())
+    return;
+  maybeRecordLocation(DL, Asm->MF);
+}
+}
diff --git a/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.h b/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.h
new file mode 100644
index 0000000000..f61ecc2f64
--- /dev/null
+++ b/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.h
@@ -0,0 +1,144 @@
+//===-- llvm/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.h ----*- C++ -*--===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains support for writing line tables info into COFF files.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef CODEGEN_ASMPRINTER_WINCODEVIEWLINETABLES_H__
+#define CODEGEN_ASMPRINTER_WINCODEVIEWLINETABLES_H__
+
+#include "AsmPrinterHandler.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/DebugInfo.h"
+#include "llvm/CodeGen/AsmPrinter.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/CodeGen/LexicalScopes.h"
+#include "llvm/MC/MCStreamer.h"
+#include "llvm/Support/DebugLoc.h"
+#include "llvm/Target/TargetLoweringObjectFile.h"
+
+namespace llvm {
+/// \brief Collects and handles line tables information in a CodeView format.
+class WinCodeViewLineTables : public AsmPrinterHandler {
+  AsmPrinter *Asm;
+  DebugLoc PrevInstLoc;
+  LexicalScopes LScopes;
+
+  // For each function, store a vector of labels to its instructions, as well as
+  // to the end of the function.
+  struct FunctionInfo {
+    SmallVector<MCSymbol *, 10> Instrs;
+    MCSymbol *End;
+  } *CurFn;
+
+  typedef DenseMap<const Function *, FunctionInfo> FnDebugInfoTy;
+  FnDebugInfoTy FnDebugInfo;
+  // Store the functions we've visited in a vector so we can maintain a stable
+  // order while emitting subsections.
+  SmallVector<const Function *, 10> VisitedFunctions;
+
+  // InstrInfoTy - Holds the Filename:LineNumber information for every
+  // instruction with a unique debug location.
+  struct InstrInfoTy {
+    StringRef Filename;
+    unsigned LineNumber;
+
+    InstrInfoTy() : LineNumber(0) {}
+
+    InstrInfoTy(StringRef Filename, unsigned LineNumber)
+        : Filename(Filename), LineNumber(LineNumber) {}
+  };
+  DenseMap<MCSymbol *, InstrInfoTy> InstrInfo;
+
+  // FileNameRegistry - Manages filenames observed while generating debug info
+  // by filtering out duplicates and bookkeeping the offsets in the string
+  // table to be generated.
+  struct FileNameRegistryTy {
+    SmallVector<StringRef, 10> Filenames;
+    struct PerFileInfo {
+      size_t FilenameID, StartOffset;
+    };
+    StringMap<PerFileInfo> Infos;
+
+    // The offset in the string table where we'll write the next unique
+    // filename.
+    size_t LastOffset;
+
+    FileNameRegistryTy() {
+      clear();
+    }
+
+    // Add Filename to the registry, if it was not observed before.
+    void add(StringRef Filename) {
+      if (Infos.count(Filename))
+        return;
+      size_t OldSize = Infos.size();
+      Infos[Filename].FilenameID = OldSize;
+      Infos[Filename].StartOffset = LastOffset;
+      LastOffset += Filename.size() + 1;
+      Filenames.push_back(Filename);
+    }
+
+    void clear() {
+      LastOffset = 1;
+      Infos.clear();
+      Filenames.clear();
+    }
+  } FileNameRegistry;
+
+  typedef std::map<std::pair<StringRef, StringRef>, char *>
+      DirAndFilenameToFilepathMapTy;
+  DirAndFilenameToFilepathMapTy DirAndFilenameToFilepathMap;
+  StringRef getFullFilepath(const MDNode *S);
+
+  void maybeRecordLocation(DebugLoc DL, const MachineFunction *MF);
+
+  void clear() {
+    assert(CurFn == 0);
+    FileNameRegistry.clear();
+    InstrInfo.clear();
+  }
+
+  void emitDebugInfoForFunction(const Function *GV);
+
+public:
+  WinCodeViewLineTables(AsmPrinter *Asm);
+
+  ~WinCodeViewLineTables() {
+    for (DirAndFilenameToFilepathMapTy::iterator
+             I = DirAndFilenameToFilepathMap.begin(),
+             E = DirAndFilenameToFilepathMap.end();
+         I != E; ++I)
+      free(I->second);
+  }
+
+  virtual void setSymbolSize(const llvm::MCSymbol *, uint64_t) {}
+
+  /// \brief Emit the COFF section that holds the line table information.
+  virtual void endModule();
+
+  /// \brief Gather pre-function debug information.
+  virtual void beginFunction(const MachineFunction *MF);
+
+  /// \brief Gather post-function debug information.
+  virtual void endFunction(const MachineFunction *);
+
+  /// \brief Process beginning of an instruction.
+  virtual void beginInstruction(const MachineInstr *MI);
+
+  /// \brief Process end of an instruction.
+  virtual void endInstruction() {}
+};
+} // End of namespace llvm
+
+#endif
diff --git a/lib/IR/DebugLoc.cpp b/lib/IR/DebugLoc.cpp
index c57b5a3053..fcb6f4194e 100644
--- a/lib/IR/DebugLoc.cpp
+++ b/lib/IR/DebugLoc.cpp
@@ -70,6 +70,26 @@ void DebugLoc::getScopeAndInlinedAt(MDNode *&Scope, MDNode *&IA,
   IA    = Ctx.pImpl->ScopeInlinedAtRecords[-ScopeIdx-1].second.get();
 }
 
+MDNode *DebugLoc::getScopeNode(const LLVMContext &Ctx) const {
+  if (MDNode *InlinedAt = getInlinedAt(Ctx))
+    return DebugLoc::getFromDILocation(InlinedAt).getScopeNode(Ctx);
+  return getScope(Ctx);
+}
+
+DebugLoc DebugLoc::getFnDebugLoc(const LLVMContext &Ctx) {
+  const MDNode *Scope = getScopeNode(Ctx);
+  DISubprogram SP = getDISubprogram(Scope);
+  if (SP.isSubprogram()) {
+    // Check for number of operands since the compatibility is
+    // cheap here.  FIXME: Name the magic constant.
+    if (SP->getNumOperands() > 19)
+      return DebugLoc::get(SP.getScopeLineNumber(), 0, SP);
+    else
+      return DebugLoc::get(SP.getLineNumber(), 0, SP);
+  }
+
+  return DebugLoc();
+}
 
 DebugLoc DebugLoc::get(unsigned Line, unsigned Col,
                        MDNode *Scope, MDNode *InlinedAt) {
diff --git a/lib/MC/MCObjectFileInfo.cpp b/lib/MC/MCObjectFileInfo.cpp
index 796d03bfeb..a160f298e1 100644
--- a/lib/MC/MCObjectFileInfo.cpp
+++ b/lib/MC/MCObjectFileInfo.cpp
@@ -150,6 +150,8 @@ void MCObjectFileInfo::InitMachOMCObjectFileInfo(Triple T) {
   LSDASection = Ctx->getMachOSection("__TEXT", "__gcc_except_tab", 0,
                                      SectionKind::getReadOnlyWithRel());
 
+  COFFDebugSymbolsSection = 0;
+
   if (T.isMacOSX() && !T.isMacOSXVersionLT(10, 6)) {
     CompactUnwindSection =
       Ctx->getMachOSection("__LD", "__compact_unwind",
@@ -458,6 +460,8 @@ void MCObjectFileInfo::InitELFMCObjectFileInfo(Triple T) {
                        ELF::SHF_ALLOC,
                        SectionKind::getReadOnly());
 
+  COFFDebugSymbolsSection = 0;
+
   // Debug Info Sections.
   DwarfAbbrevSection =
     Ctx->getELFSection(".debug_abbrev", ELF::SHT_PROGBITS, 0,