Use std::map::insert instead of emplace for libstdc++ 4.7

[rnk]

Summary

Rename WinCodeViewLineTables to CodeViewDebug, similar to DwarfDebug

Soon it will be responsible for more than line tables.

[majnemer]

LGTM

[rnk]

Silly phab, got the wrong title.

llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

 // This file implements the AsmPrinter class.
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/CodeGen/AsmPrinter.h"
 #include "DwarfDebug.h"
 #include "DwarfException.h"
 #include "WinException.h"
-#include "WinCodeViewLineTables.h"
+#include "CodeViewDebug.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/ConstantFolding.h"
 #include "llvm/CodeGen/Analysis.h"
 #include "llvm/CodeGen/GCMetadataPrinter.h"
 #include "llvm/CodeGen/MachineConstantPool.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineFunction.h"
EmitInlineAsm(M.getModuleInlineAsm()+"\n",
                   OutContext.getSubtargetCopy(*STI), TM.Options.MCOptions);
     OutStreamer->AddComment("End of file scope inline assembly");
     OutStreamer->AddBlankLine();
   }
 
   if (MAI->doesSupportDebugInformation()) {
     bool EmitCodeView = MMI->getModule()->getCodeViewFlag();
     if (EmitCodeView && TM.getTargetTriple().isKnownWindowsMSVCEnvironment()) {
-      Handlers.push_back(HandlerInfo(new WinCodeViewLineTables(this),
+      Handlers.push_back(HandlerInfo(new CodeViewDebug(this),
                                      DbgTimerName,
                                      CodeViewLineTablesGroupName));
     }
     if (!EmitCodeView || MMI->getModule()->getDwarfVersion()) {
       DD = new DwarfDebug(this, &M);
       Handlers.push_back(HandlerInfo(DD, DbgTimerName, DWARFGroupName));
     }
   }

llvm/trunk/lib/CodeGen/AsmPrinter/CMakeLists.txt

add_llvm_library(LLVMAsmPrinter
   DwarfExpression.cpp
   DwarfFile.cpp
   DwarfStringPool.cpp
   DwarfUnit.cpp
   EHStreamer.cpp
   ErlangGCPrinter.cpp
   OcamlGCPrinter.cpp
   WinException.cpp
-  WinCodeViewLineTables.cpp
+  CodeViewDebug.cpp
   )
 
 add_dependencies(LLVMAsmPrinter intrinsics_gen)

llvm/trunk/lib/CodeGen/AsmPrinter/CodeViewDebug.h

+//===-- llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.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 Microsoft CodeView debug info.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_CODEVIEWDEBUG_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_CODEVIEWDEBUG_H
+
+#include "AsmPrinterHandler.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/CodeGen/AsmPrinter.h"
+#include "llvm/CodeGen/LexicalScopes.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/IR/DebugInfo.h"
+#include "llvm/IR/DebugLoc.h"
+#include "llvm/MC/MCStreamer.h"
+#include "llvm/Target/TargetLoweringObjectFile.h"
+
+namespace llvm {
+/// \brief Collects and handles line tables information in a CodeView format.
+class LLVM_LIBRARY_VISIBILITY CodeViewDebug : public AsmPrinterHandler {
+  AsmPrinter *Asm;
+  DebugLoc PrevInstLoc;
+
+  // 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;
+    FunctionInfo() : End(nullptr) {}
+  } *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;
+    unsigned ColumnNumber;
+
+    InstrInfoTy() : LineNumber(0), ColumnNumber(0) {}
+
+    InstrInfoTy(StringRef Filename, unsigned LineNumber, unsigned ColumnNumber)
+        : Filename(Filename), LineNumber(LineNumber),
+          ColumnNumber(ColumnNumber) {}
+  };
+  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>, std::string>
+      DirAndFilenameToFilepathMapTy;
+  DirAndFilenameToFilepathMapTy DirAndFilenameToFilepathMap;
+  StringRef getFullFilepath(const MDNode *S);
+
+  void maybeRecordLocation(DebugLoc DL, const MachineFunction *MF);
+
+  void clear() {
+    assert(CurFn == nullptr);
+    FileNameRegistry.clear();
+    InstrInfo.clear();
+  }
+
+  void emitDebugInfoForFunction(const Function *GV);
+
+public:
+  CodeViewDebug(AsmPrinter *Asm);
+
+  void setSymbolSize(const llvm::MCSymbol *, uint64_t) override {}
+
+  /// \brief Emit the COFF section that holds the line table information.
+  void endModule() override;
+
+  /// \brief Gather pre-function debug information.
+  void beginFunction(const MachineFunction *MF) override;
+
+  /// \brief Gather post-function debug information.
+  void endFunction(const MachineFunction *) override;
+
+  /// \brief Process beginning of an instruction.
+  void beginInstruction(const MachineInstr *MI) override;
+
+  /// \brief Process end of an instruction.
+  void endInstruction() override {}
+};
+} // End of namespace llvm
+
+#endif

llvm/trunk/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp

+//===-- llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.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 Microsoft CodeView debug info.
+//
+//===----------------------------------------------------------------------===//
+
+#include "CodeViewDebug.h"
+#include "llvm/DebugInfo/CodeView/CodeView.h"
+#include "llvm/DebugInfo/CodeView/SymbolRecord.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCSymbol.h"
+#include "llvm/Support/COFF.h"
+
+using namespace llvm::codeview;
+
+namespace llvm {
+
+StringRef CodeViewDebug::getFullFilepath(const MDNode *S) {
+  assert(S);
+  assert((isa<DICompileUnit>(S) || isa<DIFile>(S) || isa<DISubprogram>(S) ||
+          isa<DILexicalBlockBase>(S)) &&
+         "Unexpected scope info");
+
+  auto *Scope = cast<DIScope>(S);
+  StringRef Dir = Scope->getDirectory(),
+            Filename = Scope->getFilename();
+  std::string &Filepath =
+      DirAndFilenameToFilepathMap[std::make_pair(Dir, Filename)];
+  if (!Filepath.empty())
+    return Filepath;
+
+  // 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.
+  if (Filename.find(':') == 1)
+    Filepath = Filename;
+  else
+    Filepath = (Dir + "\\" + 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);
+
+  return Filepath;
+}
+
+void CodeViewDebug::maybeRecordLocation(DebugLoc DL,
+                                                const MachineFunction *MF) {
+  const MDNode *Scope = DL.getScope();
+  if (!Scope)
+    return;
+  unsigned LineNumber = DL.getLine();
+  // Skip this line if it is longer than the maximum we can record.
+  if (LineNumber > COFF::CVL_MaxLineNumber)
+    return;
+
+  unsigned ColumnNumber = DL.getCol();
+  // Truncate the column number if it is longer than the maximum we can record.
+  if (ColumnNumber > COFF::CVL_MaxColumnNumber)
+    ColumnNumber = 0;
+
+  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 == LineNumber &&
+        LastInstr.ColumnNumber == ColumnNumber)
+      return;
+  }
+  FileNameRegistry.add(Filename);
+
+  MCSymbol *MCL = Asm->MMI->getContext().createTempSymbol();
+  Asm->OutStreamer->EmitLabel(MCL);
+  CurFn->Instrs.push_back(MCL);
+  InstrInfo[MCL] = InstrInfoTy(Filename, LineNumber, ColumnNumber);
+}
+
+CodeViewDebug::CodeViewDebug(AsmPrinter *AP)
+    : Asm(nullptr), CurFn(nullptr) {
+  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;
+}
+
+void CodeViewDebug::endModule() {
+  if (FnDebugInfo.empty())
+    return;
+
+  // FIXME: For functions that are comdat, we should emit separate .debug$S
+  // sections that are comdat associative with the main function instead of
+  // having one big .debug$S section.
+  assert(Asm != nullptr);
+  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.
+
+  // Emit per-function debug information.  This code is extracted into a
+  // separate function for readability.
+  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(unsigned(ModuleSubstreamKind::FileChecksums));
+  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 its 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(unsigned(ModuleSubstreamKind::StringTable));
+  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();
+}
+
+static void EmitLabelDiff(MCStreamer &Streamer,
+                          const MCSymbol *From, const MCSymbol *To,
+                          unsigned int Size = 4) {
+  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, Size);
+}
+
+void CodeViewDebug::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);
+  assert(Fn);
+
+  const FunctionInfo &FI = FnDebugInfo[GV];
+  if (FI.Instrs.empty())
+    return;
+  assert(FI.End && "Don't know where the function ends?");
+
+  StringRef FuncName;
+  if (auto *SP = getDISubprogram(GV))
+    FuncName = SP->getDisplayName();
+
+  // If our DISubprogram name is empty, use the mangled name.
+  if (FuncName.empty())
+    FuncName = GlobalValue::getRealLinkageName(GV->getName());
+
+  // Emit a symbol subsection, required by VS2012+ to find function boundaries.
+  MCSymbol *SymbolsBegin = Asm->MMI->getContext().createTempSymbol(),
+           *SymbolsEnd = Asm->MMI->getContext().createTempSymbol();
+  Asm->OutStreamer->AddComment("Symbol subsection for " + Twine(FuncName));
+  Asm->EmitInt32(unsigned(ModuleSubstreamKind::Symbols));
+  EmitLabelDiff(*Asm->OutStreamer, SymbolsBegin, SymbolsEnd);
+  Asm->OutStreamer->EmitLabel(SymbolsBegin);
+  {
+    MCSymbol *ProcSegmentBegin = Asm->MMI->getContext().createTempSymbol(),
+             *ProcSegmentEnd = Asm->MMI->getContext().createTempSymbol();
+    EmitLabelDiff(*Asm->OutStreamer, ProcSegmentBegin, ProcSegmentEnd, 2);
+    Asm->OutStreamer->EmitLabel(ProcSegmentBegin);
+
+    Asm->EmitInt16(unsigned(SymbolRecordKind::S_GPROC32_ID));
+
+    // Some bytes of this segment don't seem to be required for basic debugging,
+    // so just fill them with zeroes.
+    Asm->OutStreamer->EmitFill(12, 0);
+    // This is the important bit that tells the debugger where the function
+    // code is located and what's its size:
+    EmitLabelDiff(*Asm->OutStreamer, Fn, FI.End);
+    Asm->OutStreamer->EmitFill(12, 0);
+    Asm->OutStreamer->EmitCOFFSecRel32(Fn);
+    Asm->OutStreamer->EmitCOFFSectionIndex(Fn);
+    Asm->EmitInt8(0);
+    // Emit the function display name as a null-terminated string.
+    Asm->OutStreamer->EmitBytes(FuncName);
+    Asm->EmitInt8(0);
+    Asm->OutStreamer->EmitLabel(ProcSegmentEnd);
+
+    // We're done with this function.
+    Asm->EmitInt16(0x0002);
+    Asm->EmitInt16(unsigned(SymbolRecordKind::S_PROC_ID_END));
+  }
+  Asm->OutStreamer->EmitLabel(SymbolsEnd);
+  // Every subsection must be aligned to a 4-byte boundary.
+  Asm->OutStreamer->EmitFill((-FuncName.size()) % 4, 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 a line table subsection, required to do PC-to-file:line lookup.
+  Asm->OutStreamer->AddComment("Line table subsection for " + Twine(FuncName));
+  Asm->EmitInt32(unsigned(ModuleSubstreamKind::Lines));
+  MCSymbol *LineTableBegin = Asm->MMI->getContext().createTempSymbol(),
+           *LineTableEnd = Asm->MMI->getContext().createTempSymbol();
+  EmitLabelDiff(*Asm->OutStreamer, LineTableBegin, LineTableEnd);
+  Asm->OutStreamer->EmitLabel(LineTableBegin);
+
+  // Identify the function this subsection is for.
+  Asm->OutStreamer->EmitCOFFSecRel32(Fn);
+  Asm->OutStreamer->EmitCOFFSectionIndex(Fn);
+  // Insert flags after a 16-bit section index.
+  Asm->EmitInt16(COFF::DEBUG_LINE_TABLES_HAVE_COLUMN_RECORDS);
+
+  // Length of the function's code, in bytes.
+  EmitLabelDiff(*Asm->OutStreamer, Fn, FI.End);
+
+  // PC-to-linenumber lookup table:
+  MCSymbol *FileSegmentEnd = nullptr;
+
+  // The start of the last segment:
+  size_t LastSegmentStart = 0;
+
+  auto FinishPreviousChunk = [&] {
+    if (!FileSegmentEnd)
+      return;
+    for (size_t ColSegI = LastSegmentStart,
+                ColSegEnd = ColSegI + FilenameSegmentLengths[LastSegmentStart];
+         ColSegI != ColSegEnd; ++ColSegI) {
+      unsigned ColumnNumber = InstrInfo[FI.Instrs[ColSegI]].ColumnNumber;
+      assert(ColumnNumber <= COFF::CVL_MaxColumnNumber);
+      Asm->EmitInt16(ColumnNumber); // Start column
+      Asm->EmitInt16(0);            // End column
+    }
+    Asm->OutStreamer->EmitLabel(FileSegmentEnd);
+  };
+
+  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.
+      FinishPreviousChunk();
+      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);
+      LastSegmentStart = J;
+    }
+
+    // The first PC with the given linenumber and the linenumber itself.
+    EmitLabelDiff(*Asm->OutStreamer, Fn, Instr);
+    uint32_t LineNumber = InstrInfo[Instr].LineNumber;
+    assert(LineNumber <= COFF::CVL_MaxLineNumber);
+    uint32_t LineData = LineNumber | COFF::CVL_IsStatement;
+    Asm->EmitInt32(LineData);
+  }
+
+  FinishPreviousChunk();
+  Asm->OutStreamer->EmitLabel(LineTableEnd);
+}
+
+void CodeViewDebug::beginFunction(const MachineFunction *MF) {
+  assert(!CurFn && "Can't process two functions at once!");
+
+  if (!Asm || !Asm->MMI->hasDebugInfo())
+    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 (const auto &MBB : *MF) {
+    if (PrologEndLoc)
+      break;
+    for (const auto &MI : MBB) {
+      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()) {
+        PrologEndLoc = MI.getDebugLoc();
+        break;
+      }
+      EmptyPrologue = false;
+    }
+  }
+  // Record beginning of function if we have a non-empty prologue.
+  if (PrologEndLoc && !EmptyPrologue) {
+    DebugLoc FnStartDL = PrologEndLoc.getFnDebugLoc();
+    maybeRecordLocation(FnStartDL, MF);
+  }
+}
+
+void CodeViewDebug::endFunction(const MachineFunction *MF) {
+  if (!Asm || !CurFn)  // We haven't created any debug info for this function.
+    return;
+
+  const Function *GV = MF->getFunction();
+  assert(FnDebugInfo.count(GV));
+  assert(CurFn == &FnDebugInfo[GV]);
+
+  if (CurFn->Instrs.empty()) {
+    FnDebugInfo.erase(GV);
+    VisitedFunctions.pop_back();
+  } else {
+    CurFn->End = Asm->getFunctionEnd();
+  }
+  CurFn = nullptr;
+}
+
+void CodeViewDebug::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)
+    return;
+  maybeRecordLocation(DL, Asm->MF);
+}
+}

llvm/trunk/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.h

-//===-- 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 LLVM_LIB_CODEGEN_ASMPRINTER_WINCODEVIEWLINETABLES_H
-#define LLVM_LIB_CODEGEN_ASMPRINTER_WINCODEVIEWLINETABLES_H
-
-#include "AsmPrinterHandler.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/StringMap.h"
-#include "llvm/ADT/StringRef.h"
-#include "llvm/CodeGen/AsmPrinter.h"
-#include "llvm/CodeGen/LexicalScopes.h"
-#include "llvm/CodeGen/MachineFunction.h"
-#include "llvm/CodeGen/MachineModuleInfo.h"
-#include "llvm/IR/DebugInfo.h"
-#include "llvm/IR/DebugLoc.h"
-#include "llvm/MC/MCStreamer.h"
-#include "llvm/Target/TargetLoweringObjectFile.h"
-
-namespace llvm {
-/// \brief Collects and handles line tables information in a CodeView format.
-class LLVM_LIBRARY_VISIBILITY WinCodeViewLineTables : public AsmPrinterHandler {
-  AsmPrinter *Asm;
-  DebugLoc PrevInstLoc;
-
-  // 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;
-    FunctionInfo() : End(nullptr) {}
-  } *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;
-    unsigned ColumnNumber;
-
-    InstrInfoTy() : LineNumber(0), ColumnNumber(0) {}
-
-    InstrInfoTy(StringRef Filename, unsigned LineNumber, unsigned ColumnNumber)
-        : Filename(Filename), LineNumber(LineNumber),
-          ColumnNumber(ColumnNumber) {}
-  };
-  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>, std::string>
-      DirAndFilenameToFilepathMapTy;
-  DirAndFilenameToFilepathMapTy DirAndFilenameToFilepathMap;
-  StringRef getFullFilepath(const MDNode *S);
-
-  void maybeRecordLocation(DebugLoc DL, const MachineFunction *MF);
-
-  void clear() {
-    assert(CurFn == nullptr);
-    FileNameRegistry.clear();
-    InstrInfo.clear();
-  }
-
-  void emitDebugInfoForFunction(const Function *GV);
-
-public:
-  WinCodeViewLineTables(AsmPrinter *Asm);
-
-  void setSymbolSize(const llvm::MCSymbol *, uint64_t) override {}
-
-  /// \brief Emit the COFF section that holds the line table information.
-  void endModule() override;
-
-  /// \brief Gather pre-function debug information.
-  void beginFunction(const MachineFunction *MF) override;
-
-  /// \brief Gather post-function debug information.
-  void endFunction(const MachineFunction *) override;
-
-  /// \brief Process beginning of an instruction.
-  void beginInstruction(const MachineInstr *MI) override;
-
-  /// \brief Process end of an instruction.
-  void endInstruction() override {}
-};
-} // End of namespace llvm
-
-#endif

llvm/trunk/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp

-//===-- 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/DebugInfo/CodeView/CodeView.h"
-#include "llvm/DebugInfo/CodeView/SymbolRecord.h"
-#include "llvm/MC/MCExpr.h"
-#include "llvm/MC/MCSymbol.h"
-#include "llvm/Support/COFF.h"
-
-using namespace llvm::codeview;
-
-namespace llvm {
-
-StringRef WinCodeViewLineTables::getFullFilepath(const MDNode *S) {
-  assert(S);
-  assert((isa<DICompileUnit>(S) || isa<DIFile>(S) || isa<DISubprogram>(S) ||
-          isa<DILexicalBlockBase>(S)) &&
-         "Unexpected scope info");
-
-  auto *Scope = cast<DIScope>(S);
-  StringRef Dir = Scope->getDirectory(),
-            Filename = Scope->getFilename();
-  std::string &Filepath =
-      DirAndFilenameToFilepathMap[std::make_pair(Dir, Filename)];
-  if (!Filepath.empty())
-    return Filepath;
-
-  // 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.
-  if (Filename.find(':') == 1)
-    Filepath = Filename;
-  else
-    Filepath = (Dir + "\\" + 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);
-
-  return Filepath;
-}
-
-void WinCodeViewLineTables::maybeRecordLocation(DebugLoc DL,
-                                                const MachineFunction *MF) {
-  const MDNode *Scope = DL.getScope();
-  if (!Scope)
-    return;
-  unsigned LineNumber = DL.getLine();
-  // Skip this line if it is longer than the maximum we can record.
-  if (LineNumber > COFF::CVL_MaxLineNumber)
-    return;
-
-  unsigned ColumnNumber = DL.getCol();
-  // Truncate the column number if it is longer than the maximum we can record.
-  if (ColumnNumber > COFF::CVL_MaxColumnNumber)
-    ColumnNumber = 0;
-
-  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 == LineNumber &&
-        LastInstr.ColumnNumber == ColumnNumber)
-      return;
-  }
-  FileNameRegistry.add(Filename);
-
-  MCSymbol *MCL = Asm->MMI->getContext().createTempSymbol();
-  Asm->OutStreamer->EmitLabel(MCL);
-  CurFn->Instrs.push_back(MCL);
-  InstrInfo[MCL] = InstrInfoTy(Filename, LineNumber, ColumnNumber);
-}
-
-WinCodeViewLineTables::WinCodeViewLineTables(AsmPrinter *AP)
-    : Asm(nullptr), CurFn(nullptr) {
-  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;
-}
-
-void WinCodeViewLineTables::endModule() {
-  if (FnDebugInfo.empty())
-    return;
-
-  // FIXME: For functions that are comdat, we should emit separate .debug$S
-  // sections that are comdat associative with the main function instead of
-  // having one big .debug$S section.
-  assert(Asm != nullptr);
-  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.
-
-  // Emit per-function debug information.  This code is extracted into a
-  // separate function for readability.
-  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(unsigned(ModuleSubstreamKind::FileChecksums));
-  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 its 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(unsigned(ModuleSubstreamKind::StringTable));
-  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();
-}
-
-static void EmitLabelDiff(MCStreamer &Streamer,
-                          const MCSymbol *From, const MCSymbol *To,
-                          unsigned int Size = 4) {
-  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, Size);
-}
-
-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);
-  assert(Fn);
-
-  const FunctionInfo &FI = FnDebugInfo[GV];
-  if (FI.Instrs.empty())
-    return;
-  assert(FI.End && "Don't know where the function ends?");
-
-  StringRef FuncName;
-  if (auto *SP = getDISubprogram(GV))
-    FuncName = SP->getDisplayName();
-
-  // If our DISubprogram name is empty, use the mangled name.
-  if (FuncName.empty())
-    FuncName = GlobalValue::getRealLinkageName(GV->getName());
-
-  // Emit a symbol subsection, required by VS2012+ to find function boundaries.
-  MCSymbol *SymbolsBegin = Asm->MMI->getContext().createTempSymbol(),
-           *SymbolsEnd = Asm->MMI->getContext().createTempSymbol();
-  Asm->OutStreamer->AddComment("Symbol subsection for " + Twine(FuncName));
-  Asm->EmitInt32(unsigned(ModuleSubstreamKind::Symbols));
-  EmitLabelDiff(*Asm->OutStreamer, SymbolsBegin, SymbolsEnd);
-  Asm->OutStreamer->EmitLabel(SymbolsBegin);
-  {
-    MCSymbol *ProcSegmentBegin = Asm->MMI->getContext().createTempSymbol(),
-             *ProcSegmentEnd = Asm->MMI->getContext().createTempSymbol();
-    EmitLabelDiff(*Asm->OutStreamer, ProcSegmentBegin, ProcSegmentEnd, 2);
-    Asm->OutStreamer->EmitLabel(ProcSegmentBegin);
-
-    Asm->EmitInt16(unsigned(SymbolRecordKind::S_GPROC32_ID));
-
-    // Some bytes of this segment don't seem to be required for basic debugging,
-    // so just fill them with zeroes.
-    Asm->OutStreamer->EmitFill(12, 0);
-    // This is the important bit that tells the debugger where the function
-    // code is located and what's its size:
-    EmitLabelDiff(*Asm->OutStreamer, Fn, FI.End);
-    Asm->OutStreamer->EmitFill(12, 0);
-    Asm->OutStreamer->EmitCOFFSecRel32(Fn);
-    Asm->OutStreamer->EmitCOFFSectionIndex(Fn);
-    Asm->EmitInt8(0);
-    // Emit the function display name as a null-terminated string.
-    Asm->OutStreamer->EmitBytes(FuncName);
-    Asm->EmitInt8(0);
-    Asm->OutStreamer->EmitLabel(ProcSegmentEnd);
-
-    // We're done with this function.
-    Asm->EmitInt16(0x0002);
-    Asm->EmitInt16(unsigned(SymbolRecordKind::S_PROC_ID_END));
-  }
-  Asm->OutStreamer->EmitLabel(SymbolsEnd);
-  // Every subsection must be aligned to a 4-byte boundary.
-  Asm->OutStreamer->EmitFill((-FuncName.size()) % 4, 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 a line table subsection, required to do PC-to-file:line lookup.
-  Asm->OutStreamer->AddComment("Line table subsection for " + Twine(FuncName));
-  Asm->EmitInt32(unsigned(ModuleSubstreamKind::Lines));
-  MCSymbol *LineTableBegin = Asm->MMI->getContext().createTempSymbol(),
-           *LineTableEnd = Asm->MMI->getContext().createTempSymbol();
-  EmitLabelDiff(*Asm->OutStreamer, LineTableBegin, LineTableEnd);
-  Asm->OutStreamer->EmitLabel(LineTableBegin);
-
-  // Identify the function this subsection is for.
-  Asm->OutStreamer->EmitCOFFSecRel32(Fn);
-  Asm->OutStreamer->EmitCOFFSectionIndex(Fn);
-  // Insert flags after a 16-bit section index.
-  Asm->EmitInt16(COFF::DEBUG_LINE_TABLES_HAVE_COLUMN_RECORDS);
-
-  // Length of the function's code, in bytes.
-  EmitLabelDiff(*Asm->OutStreamer, Fn, FI.End);
-
-  // PC-to-linenumber lookup table:
-  MCSymbol *FileSegmentEnd = nullptr;
-
-  // The start of the last segment:
-  size_t LastSegmentStart = 0;
-
-  auto FinishPreviousChunk = [&] {
-    if (!FileSegmentEnd)
-      return;
-    for (size_t ColSegI = LastSegmentStart,
-                ColSegEnd = ColSegI + FilenameSegmentLengths[LastSegmentStart];
-         ColSegI != ColSegEnd; ++ColSegI) {
-      unsigned ColumnNumber = InstrInfo[FI.Instrs[ColSegI]].ColumnNumber;
-      assert(ColumnNumber <= COFF::CVL_MaxColumnNumber);
-      Asm->EmitInt16(ColumnNumber); // Start column
-      Asm->EmitInt16(0);            // End column
-    }
-    Asm->OutStreamer->EmitLabel(FileSegmentEnd);
-  };
-
-  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.
-      FinishPreviousChunk();
-      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);
-      LastSegmentStart = J;
-    }
-
-    // The first PC with the given linenumber and the linenumber itself.
-    EmitLabelDiff(*Asm->OutStreamer, Fn, Instr);
-    uint32_t LineNumber = InstrInfo[Instr].LineNumber;
-    assert(LineNumber <= COFF::CVL_MaxLineNumber);
-    uint32_t LineData = LineNumber | COFF::CVL_IsStatement;
-    Asm->EmitInt32(LineData);
-  }
-
-  FinishPreviousChunk();
-  Asm->OutStreamer->EmitLabel(LineTableEnd);
-}
-
-void WinCodeViewLineTables::beginFunction(const MachineFunction *MF) {
-  assert(!CurFn && "Can't process two functions at once!");
-
-  if (!Asm || !Asm->MMI->hasDebugInfo())
-    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 (const auto &MBB : *MF) {
-    if (PrologEndLoc)
-      break;
-    for (const auto &MI : MBB) {
-      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()) {
-        PrologEndLoc = MI.getDebugLoc();
-        break;
-      }
-      EmptyPrologue = false;
-    }
-  }
-  // Record beginning of function if we have a non-empty prologue.
-  if (PrologEndLoc && !EmptyPrologue) {
-    DebugLoc FnStartDL = PrologEndLoc.getFnDebugLoc();
-    maybeRecordLocation(FnStartDL, MF);
-  }
-}
-
-void WinCodeViewLineTables::endFunction(const MachineFunction *MF) {
-  if (!Asm || !CurFn)  // We haven't created any debug info for this function.
-    return;
-
-  const Function *GV = MF->getFunction();
-  assert(FnDebugInfo.count(GV));
-  assert(CurFn == &FnDebugInfo[GV]);
-
-  if (CurFn->Instrs.empty()) {
-    FnDebugInfo.erase(GV);
-    VisitedFunctions.pop_back();
-  } else {
-    CurFn->End = Asm->getFunctionEnd();
-  }
-  CurFn = nullptr;
-}
-
-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)
-    return;
-  maybeRecordLocation(DL, Asm->MF);
-}
-}