DWARF: Add basic support for line tables.

The llvm-dwarfdump output isn't very verbose yet.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139771 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 707 insertions, 0 deletions

diff --git a/lib/DebugInfo/CMakeLists.txt b/lib/DebugInfo/CMakeLists.txt
index 91d20dd..fdffcb6 100644
--- a/lib/DebugInfo/CMakeLists.txt
+++ b/lib/DebugInfo/CMakeLists.txt
@@ -7,6 +7,7 @@ add_llvm_library(LLVMDebugInfo
   DWARFDebugArangeSet.cpp
   DWARFDebugAranges.cpp
   DWARFDebugInfoEntry.cpp
+  DWARFDebugLine.cpp
   DWARFFormValue.cpp
   )
 
diff --git a/lib/DebugInfo/DWARFContext.cpp b/lib/DebugInfo/DWARFContext.cpp
index 3359ae3..68f58d9 100644
--- a/lib/DebugInfo/DWARFContext.cpp
+++ b/lib/DebugInfo/DWARFContext.cpp
@@ -25,6 +25,10 @@ void DWARFContext::dump(raw_ostream &OS) {
   DWARFDebugArangeSet set;
   while (set.extract(arangesData, &offset))
     set.dump(OS);
+
+  OS << "\n.debug_lines contents:\n";
+  DataExtractor lineData(getLineSection(), isLittleEndian(), 8);
+  DWARFDebugLine::dump(lineData, OS);
 }
 
 const DWARFDebugAbbrev *DWARFContext::getDebugAbbrev() {
@@ -51,6 +55,17 @@ const DWARFDebugAranges *DWARFContext::getDebugAranges() {
   return Aranges.get();
 }
 
+const DWARFDebugLine *DWARFContext::getDebugLine() {
+  if (Line)
+    return Line.get();
+
+  DataExtractor lineData(getLineSection(), isLittleEndian(), 0);
+
+  Line.reset(new DWARFDebugLine());
+  Line->parse(lineData);
+  return Line.get();
+}
+
 void DWARFContext::parseCompileUnits() {
   uint32_t offset = 0;
   const DataExtractor &debug_info_data = DataExtractor(getInfoSection(),
diff --git a/lib/DebugInfo/DWARFContext.h b/lib/DebugInfo/DWARFContext.h
index 3eca952..ead169e 100644
--- a/lib/DebugInfo/DWARFContext.h
+++ b/lib/DebugInfo/DWARFContext.h
@@ -12,6 +12,7 @@
 
 #include "DWARFCompileUnit.h"
 #include "DWARFDebugAranges.h"
+#include "DWARFDebugLine.h"
 #include "llvm/DebugInfo/DIContext.h"
 #include "llvm/ADT/OwningPtr.h"
 #include "llvm/ADT/SmallVector.h"
@@ -28,6 +29,7 @@ class DWARFContext : public DIContext {
   SmallVector<DWARFCompileUnit, 1> CUs;
   OwningPtr<DWARFDebugAbbrev> Abbrev;
   OwningPtr<DWARFDebugAranges> Aranges;
+  OwningPtr<DWARFDebugLine> Line;
 
   DWARFContext(DWARFContext &); // = delete
   DWARFContext &operator=(DWARFContext &); // = delete
@@ -57,6 +59,9 @@ public:
   /// Get a pointer to the parsed DebugAranges object.
   const DWARFDebugAranges *getDebugAranges();
 
+  /// Get a pointer to the parsed DWARFDebugLine object.
+  const DWARFDebugLine *getDebugLine();
+
   bool isLittleEndian() const { return IsLittleEndian; }
 
   virtual StringRef getInfoSection() = 0;
diff --git a/lib/DebugInfo/DWARFDebugLine.cpp b/lib/DebugInfo/DWARFDebugLine.cpp
new file mode 100644
index 0000000..ba68433
--- /dev/null
+++ b/lib/DebugInfo/DWARFDebugLine.cpp
@@ -0,0 +1,491 @@
+//===-- DWARFDebugLine.cpp ------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "DWARFDebugLine.h"
+#include "llvm/Support/Dwarf.h"
+#include "llvm/Support/Format.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+using namespace dwarf;
+
+void DWARFDebugLine::Prologue::dump(raw_ostream &OS) const {
+  OS << "Line table prologue:\n"
+     << format("   total_length: 0x%8.8x\n", TotalLength)
+     << format("        version: %u\n", Version)
+     << format("prologue_length: 0x%8.8x\n", PrologueLength)
+     << format("min_inst_length: %u\n", MinInstLength)
+     << format("default_is_stmt: %u\n", DefaultIsStmt)
+     << format("      line_base: %i\n", LineBase)
+     << format("     line_range: %u\n", LineRange)
+     << format("    opcode_base: %u\n", OpcodeBase);
+
+  for (uint32_t i = 0; i < StandardOpcodeLengths.size(); ++i)
+    OS << format("standard_opcode_lengths[%s] = %u\n", LNStandardString(i+1),
+                 StandardOpcodeLengths[i]);
+
+  if (!IncludeDirectories.empty())
+    for (uint32_t i = 0; i < IncludeDirectories.size(); ++i)
+      OS << format("include_directories[%3u] = '", i+1)
+         << IncludeDirectories[i] << "'\n";
+
+  if (!FileNames.empty()) {
+    OS << "                Dir  Mod Time   File Len   File Name\n"
+       << "                ---- ---------- ---------- -----------"
+          "----------------\n";
+    for (uint32_t i = 0; i < FileNames.size(); ++i) {
+      const FileNameEntry& fileEntry = FileNames[i];
+      OS << format("file_names[%3u] %4u ", i+1, fileEntry.DirIdx)
+         << format("0x%8.8x 0x%8.8x ", fileEntry.ModTime, fileEntry.Length)
+         << fileEntry.Name << '\n';
+    }
+  }
+}
+
+void DWARFDebugLine::Row::postAppend() {
+  BasicBlock = false;
+  PrologueEnd = false;
+  EpilogueBegin = false;
+}
+
+void DWARFDebugLine::Row::reset(bool default_is_stmt) {
+  Address = 0;
+  Line = 1;
+  Column = 0;
+  File = 1;
+  Isa = 0;
+  IsStmt = default_is_stmt;
+  BasicBlock = false;
+  EndSequence = false;
+  PrologueEnd = false;
+  EpilogueBegin = false;
+}
+
+void DWARFDebugLine::Row::dump(raw_ostream &OS) const {
+  OS << format("0x%16.16llx %6u %6u", Address, Line, Column)
+     << format(" %6u %3u ", File, Isa)
+     << (IsStmt ? " is_stmt" : "")
+     << (BasicBlock ? " basic_block" : "")
+     << (PrologueEnd ? " prologue_end" : "")
+     << (EpilogueBegin ? " epilogue_begin" : "")
+     << (EndSequence ? " end_sequence" : "")
+     << '\n';
+}
+
+void DWARFDebugLine::LineTable::dump(raw_ostream &OS) const {
+  Prologue.dump(OS);
+  OS << '\n';
+
+  if (!Rows.empty()) {
+    OS << "Address            Line   Column File   ISA Flags\n"
+       << "------------------ ------ ------ ------ --- -------------\n";
+    for (std::vector<Row>::const_iterator pos = Rows.begin(),
+         end = Rows.end(); pos != end; ++pos)
+      pos->dump(OS);
+  }
+}
+
+void DWARFDebugLine::State::appendRowToMatrix(uint32_t offset) {
+  ++row;  // Increase the row number.
+  LineTable::appendRow(*this);
+  Row::postAppend();
+}
+
+void DWARFDebugLine::parse(const DataExtractor debug_line_data) {
+  LineTableMap.clear();
+  uint32_t offset = 0;
+  State state;
+  while (debug_line_data.isValidOffset(offset)) {
+    const uint32_t debug_line_offset = offset;
+
+    if (parseStatementTable(debug_line_data, &offset, state)) {
+      // Make sure we don't don't loop infinitely
+      if (offset <= debug_line_offset)
+        break;
+
+      LineTableMap[debug_line_offset] = state;
+      state.reset();
+    }
+    else
+      ++offset; // Try next byte in line table
+  }
+}
+
+void DWARFDebugLine::DumpingState::finalize(uint32_t offset) {
+  LineTable::dump(OS);
+}
+
+void DWARFDebugLine::dump(const DataExtractor debug_line_data, raw_ostream &OS){
+  uint32_t offset = 0;
+  DumpingState state(OS);
+    while (debug_line_data.isValidOffset(offset)) {
+    const uint32_t debug_line_offset = offset;
+
+    if (parseStatementTable(debug_line_data, &offset, state)) {
+      // Make sure we don't don't loop infinitely
+      if (offset <= debug_line_offset)
+        break;
+
+      state.reset();
+    }
+    else
+      ++offset; // Try next byte in line table
+  }
+}
+
+const DWARFDebugLine::LineTable *
+DWARFDebugLine::getLineTable(uint32_t offset) const {
+  LineTableConstIter pos = LineTableMap.find(offset);
+  if (pos != LineTableMap.end())
+    return &pos->second;
+  return 0;
+}
+
+bool
+DWARFDebugLine::parsePrologue(DataExtractor debug_line_data,
+                              uint32_t *offset_ptr, Prologue *prologue) {
+  const uint32_t prologue_offset = *offset_ptr;
+
+  prologue->clear();
+  prologue->TotalLength = debug_line_data.getU32(offset_ptr);
+  prologue->Version = debug_line_data.getU16(offset_ptr);
+  if (prologue->Version != 2)
+    return false;
+
+  prologue->PrologueLength = debug_line_data.getU32(offset_ptr);
+  const uint32_t end_prologue_offset = prologue->PrologueLength + *offset_ptr;
+  prologue->MinInstLength = debug_line_data.getU8(offset_ptr);
+  prologue->DefaultIsStmt = debug_line_data.getU8(offset_ptr);
+  prologue->LineBase = debug_line_data.getU8(offset_ptr);
+  prologue->LineRange = debug_line_data.getU8(offset_ptr);
+  prologue->OpcodeBase = debug_line_data.getU8(offset_ptr);
+
+  prologue->StandardOpcodeLengths.reserve(prologue->OpcodeBase-1);
+  for (uint32_t i = 1; i < prologue->OpcodeBase; ++i) {
+    uint8_t op_len = debug_line_data.getU8(offset_ptr);
+    prologue->StandardOpcodeLengths.push_back(op_len);
+  }
+
+  while (*offset_ptr < end_prologue_offset) {
+    const char *s = debug_line_data.getCStr(offset_ptr);
+    if (s && s[0])
+      prologue->IncludeDirectories.push_back(s);
+    else
+      break;
+  }
+
+  while (*offset_ptr < end_prologue_offset) {
+    const char *name = debug_line_data.getCStr(offset_ptr);
+    if (name && name[0]) {
+      FileNameEntry fileEntry;
+      fileEntry.Name = name;
+      fileEntry.DirIdx = debug_line_data.getULEB128(offset_ptr);
+      fileEntry.ModTime = debug_line_data.getULEB128(offset_ptr);
+      fileEntry.Length = debug_line_data.getULEB128(offset_ptr);
+      prologue->FileNames.push_back(fileEntry);
+    } else {
+      break;
+    }
+  }
+
+  if (*offset_ptr != end_prologue_offset) {
+    fprintf(stderr, "warning: parsing line table prologue at 0x%8.8x should"
+                    " have ended at 0x%8.8x but it ended ad 0x%8.8x\n", 
+            prologue_offset, end_prologue_offset, *offset_ptr);
+  }
+  return end_prologue_offset;
+}
+
+bool
+DWARFDebugLine::parseStatementTable(DataExtractor debug_line_data,
+                                    uint32_t *offset_ptr, State &state) {
+  const uint32_t debug_line_offset = *offset_ptr;
+
+  Prologue *prologue = &state.Prologue;
+
+  if (!parsePrologue(debug_line_data, offset_ptr, prologue)) {
+    // Restore our offset and return false to indicate failure!
+    *offset_ptr = debug_line_offset;
+    return false;
+  }
+
+  const uint32_t end_offset = debug_line_offset + prologue->TotalLength +
+                              sizeof(prologue->TotalLength);
+
+  while (*offset_ptr < end_offset) {
+    uint8_t opcode = debug_line_data.getU8(offset_ptr);
+
+    if (opcode == 0) {
+      // Extended Opcodes always start with a zero opcode followed by
+      // a uleb128 length so you can skip ones you don't know about
+      uint32_t ext_offset = *offset_ptr;
+      uint64_t len = debug_line_data.getULEB128(offset_ptr);
+      uint32_t arg_size = len - (*offset_ptr - ext_offset);
+
+      uint8_t sub_opcode = debug_line_data.getU8(offset_ptr);
+      switch (sub_opcode) {
+      case DW_LNE_end_sequence:
+        // Set the end_sequence register of the state machine to true and
+        // append a row to the matrix using the current values of the
+        // state-machine registers. Then reset the registers to the initial
+        // values specified above. Every statement program sequence must end
+        // with a DW_LNE_end_sequence instruction which creates a row whose
+        // address is that of the byte after the last target machine instruction
+        // of the sequence.
+        state.EndSequence = true;
+        state.appendRowToMatrix(*offset_ptr);
+        state.reset();
+        break;
+
+      case DW_LNE_set_address:
+        // Takes a single relocatable address as an operand. The size of the
+        // operand is the size appropriate to hold an address on the target
+        // machine. Set the address register to the value given by the
+        // relocatable address. All of the other statement program opcodes
+        // that affect the address register add a delta to it. This instruction
+        // stores a relocatable value into it instead.
+        state.Address = debug_line_data.getAddress(offset_ptr);
+        break;
+
+      case DW_LNE_define_file:
+        // Takes 4 arguments. The first is a null terminated string containing
+        // a source file name. The second is an unsigned LEB128 number
+        // representing the directory index of the directory in which the file
+        // was found. The third is an unsigned LEB128 number representing the
+        // time of last modification of the file. The fourth is an unsigned
+        // LEB128 number representing the length in bytes of the file. The time
+        // and length fields may contain LEB128(0) if the information is not
+        // available.
+        //
+        // The directory index represents an entry in the include_directories
+        // section of the statement program prologue. The index is LEB128(0)
+        // if the file was found in the current directory of the compilation,
+        // LEB128(1) if it was found in the first directory in the
+        // include_directories section, and so on. The directory index is
+        // ignored for file names that represent full path names.
+        //
+        // The files are numbered, starting at 1, in the order in which they
+        // appear; the names in the prologue come before names defined by
+        // the DW_LNE_define_file instruction. These numbers are used in the
+        // the file register of the state machine.
+        {
+          FileNameEntry fileEntry;
+          fileEntry.Name = debug_line_data.getCStr(offset_ptr);
+          fileEntry.DirIdx = debug_line_data.getULEB128(offset_ptr);
+          fileEntry.ModTime = debug_line_data.getULEB128(offset_ptr);
+          fileEntry.Length = debug_line_data.getULEB128(offset_ptr);
+          prologue->FileNames.push_back(fileEntry);
+        }
+        break;
+
+      default:
+        // Length doesn't include the zero opcode byte or the length itself, but
+        // it does include the sub_opcode, so we have to adjust for that below
+        (*offset_ptr) += arg_size;
+        break;
+      }
+    } else if (opcode < prologue->OpcodeBase) {
+      switch (opcode) {
+      // Standard Opcodes
+      case DW_LNS_copy:
+        // Takes no arguments. Append a row to the matrix using the
+        // current values of the state-machine registers. Then set
+        // the basic_block register to false.
+        state.appendRowToMatrix(*offset_ptr);
+        break;
+
+      case DW_LNS_advance_pc:
+        // Takes a single unsigned LEB128 operand, multiplies it by the
+        // min_inst_length field of the prologue, and adds the
+        // result to the address register of the state machine.
+        state.Address += debug_line_data.getULEB128(offset_ptr) *
+                         prologue->MinInstLength;
+        break;
+
+      case DW_LNS_advance_line:
+        // Takes a single signed LEB128 operand and adds that value to
+        // the line register of the state machine.
+        state.Line += debug_line_data.getSLEB128(offset_ptr);
+        break;
+
+      case DW_LNS_set_file:
+        // Takes a single unsigned LEB128 operand and stores it in the file
+        // register of the state machine.
+        state.File = debug_line_data.getULEB128(offset_ptr);
+        break;
+
+      case DW_LNS_set_column:
+        // Takes a single unsigned LEB128 operand and stores it in the
+        // column register of the state machine.
+        state.Column = debug_line_data.getULEB128(offset_ptr);
+        break;
+
+      case DW_LNS_negate_stmt:
+        // Takes no arguments. Set the is_stmt register of the state
+        // machine to the logical negation of its current value.
+        state.IsStmt = !state.IsStmt;
+        break;
+
+      case DW_LNS_set_basic_block:
+        // Takes no arguments. Set the basic_block register of the
+        // state machine to true
+        state.BasicBlock = true;
+        break;
+
+      case DW_LNS_const_add_pc:
+        // Takes no arguments. Add to the address register of the state
+        // machine the address increment value corresponding to special
+        // opcode 255. The motivation for DW_LNS_const_add_pc is this:
+        // when the statement program needs to advance the address by a
+        // small amount, it can use a single special opcode, which occupies
+        // a single byte. When it needs to advance the address by up to
+        // twice the range of the last special opcode, it can use
+        // DW_LNS_const_add_pc followed by a special opcode, for a total
+        // of two bytes. Only if it needs to advance the address by more
+        // than twice that range will it need to use both DW_LNS_advance_pc
+        // and a special opcode, requiring three or more bytes.
+        {
+          uint8_t adjust_opcode = 255 - prologue->OpcodeBase;
+          uint64_t addr_offset = (adjust_opcode / prologue->LineRange) *
+                                 prologue->MinInstLength;
+          state.Address += addr_offset;
+        }
+        break;
+
+      case DW_LNS_fixed_advance_pc:
+        // Takes a single uhalf operand. Add to the address register of
+        // the state machine the value of the (unencoded) operand. This
+        // is the only extended opcode that takes an argument that is not
+        // a variable length number. The motivation for DW_LNS_fixed_advance_pc
+        // is this: existing assemblers cannot emit DW_LNS_advance_pc or
+        // special opcodes because they cannot encode LEB128 numbers or
+        // judge when the computation of a special opcode overflows and
+        // requires the use of DW_LNS_advance_pc. Such assemblers, however,
+        // can use DW_LNS_fixed_advance_pc instead, sacrificing compression.
+        state.Address += debug_line_data.getU16(offset_ptr);
+        break;
+
+      case DW_LNS_set_prologue_end:
+        // Takes no arguments. Set the prologue_end register of the
+        // state machine to true
+        state.PrologueEnd = true;
+        break;
+
+      case DW_LNS_set_epilogue_begin:
+        // Takes no arguments. Set the basic_block register of the
+        // state machine to true
+        state.EpilogueBegin = true;
+        break;
+
+      case DW_LNS_set_isa:
+        // Takes a single unsigned LEB128 operand and stores it in the
+        // column register of the state machine.
+        state.Isa = debug_line_data.getULEB128(offset_ptr);
+        break;
+
+      default:
+        // Handle any unknown standard opcodes here. We know the lengths
+        // of such opcodes because they are specified in the prologue
+        // as a multiple of LEB128 operands for each opcode.
+        {
+          assert(opcode - 1 < prologue->StandardOpcodeLengths.size());
+          uint8_t opcode_length = prologue->StandardOpcodeLengths[opcode - 1];
+          for (uint8_t i=0; i<opcode_length; ++i)
+            debug_line_data.getULEB128(offset_ptr);
+        }
+        break;
+      }
+    } else {
+      // Special Opcodes
+
+      // A special opcode value is chosen based on the amount that needs
+      // to be added to the line and address registers. The maximum line
+      // increment for a special opcode is the value of the line_base
+      // field in the header, plus the value of the line_range field,
+      // minus 1 (line base + line range - 1). If the desired line
+      // increment is greater than the maximum line increment, a standard
+      // opcode must be used instead of a special opcode. The “address
+      // advance” is calculated by dividing the desired address increment
+      // by the minimum_instruction_length field from the header. The
+      // special opcode is then calculated using the following formula:
+      //
+      //  opcode = (desired line increment - line_base) +
+      //           (line_range * address advance) + opcode_base
+      //
+      // If the resulting opcode is greater than 255, a standard opcode
+      // must be used instead.
+      //
+      // To decode a special opcode, subtract the opcode_base from the
+      // opcode itself to give the adjusted opcode. The amount to
+      // increment the address register is the result of the adjusted
+      // opcode divided by the line_range multiplied by the
+      // minimum_instruction_length field from the header. That is:
+      //
+      //  address increment = (adjusted opcode / line_range) *
+      //                      minimum_instruction_length
+      //
+      // The amount to increment the line register is the line_base plus
+      // the result of the adjusted opcode modulo the line_range. That is:
+      //
+      // line increment = line_base + (adjusted opcode % line_range)
+
+      uint8_t adjust_opcode = opcode - prologue->OpcodeBase;
+      uint64_t addr_offset = (adjust_opcode / prologue->LineRange) *
+                             prologue->MinInstLength;
+      int32_t line_offset = prologue->LineBase +
+                            (adjust_opcode % prologue->LineRange);
+      state.Line += line_offset;
+      state.Address += addr_offset;
+      state.appendRowToMatrix(*offset_ptr);
+    }
+  }
+
+  state.finalize(*offset_ptr);
+
+  return end_offset;
+}
+
+static bool findMatchingAddress(const DWARFDebugLine::Row& row1,
+                                const DWARFDebugLine::Row& row2) {
+  return row1.Address < row2.Address;
+}
+
+uint32_t
+DWARFDebugLine::LineTable::lookupAddress(uint64_t address,
+                                         uint64_t cu_high_pc) const {
+  uint32_t index = UINT32_MAX;
+  if (!Rows.empty()) {
+    // Use the lower_bound algorithm to perform a binary search since we know
+    // that our line table data is ordered by address.
+    DWARFDebugLine::Row row;
+    row.Address = address;
+    typedef std::vector<Row>::const_iterator iterator;
+    iterator begin_pos = Rows.begin();
+    iterator end_pos = Rows.end();
+    iterator pos = std::lower_bound(begin_pos, end_pos, row,
+                                    findMatchingAddress);
+    if (pos == end_pos) {
+      if (address < cu_high_pc)
+        return Rows.size()-1;
+    } else {
+      // Rely on fact that we are using a std::vector and we can do
+      // pointer arithmetic to find the row index (which will be one less
+      // that what we found since it will find the first position after
+      // the current address) since std::vector iterators are just
+      // pointers to the container type.
+      index = pos - begin_pos;
+      if (pos->Address > address) {
+        if (index > 0)
+          --index;
+        else
+          index = UINT32_MAX;
+      }
+    }
+  }
+  return index; // Failed to find address.
+}
diff --git a/lib/DebugInfo/DWARFDebugLine.h b/lib/DebugInfo/DWARFDebugLine.h
new file mode 100644
index 0000000..6c3946f
--- /dev/null
+++ b/lib/DebugInfo/DWARFDebugLine.h
@@ -0,0 +1,195 @@
+//===-- DWARFDebugLine.h ----------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_DEBUGINFO_DWARFDEBUGLINE_H
+#define LLVM_DEBUGINFO_DWARFDEBUGLINE_H
+
+#include "llvm/Support/DataExtractor.h"
+#include <map>
+#include <string>
+#include <vector>
+
+namespace llvm {
+
+class raw_ostream;
+
+class DWARFDebugLine {
+public:
+  struct FileNameEntry {
+    FileNameEntry() : DirIdx(0), ModTime(0), Length(0) {}
+
+    std::string Name;
+    uint64_t DirIdx;
+    uint64_t ModTime;
+    uint64_t Length;
+  };
+
+  struct Prologue {
+    Prologue()
+      : TotalLength(0), Version(0), PrologueLength(0), MinInstLength(0),
+        DefaultIsStmt(0), LineBase(0), LineRange(0), OpcodeBase(0) {}
+
+    // The size in bytes of the statement information for this compilation unit
+    // (not including the total_length field itself).
+    uint32_t TotalLength;
+    // Version identifier for the statement information format.
+    uint16_t Version;
+    // The number of bytes following the prologue_length field to the beginning
+    // of the first byte of the statement program itself.
+    uint32_t PrologueLength;
+    // The size in bytes of the smallest target machine instruction. Statement
+    // program opcodes that alter the address register first multiply their
+    // operands by this value.
+    uint8_t MinInstLength;
+    // The initial value of theis_stmtregister.
+    uint8_t DefaultIsStmt;
+    // This parameter affects the meaning of the special opcodes. See below.
+    int8_t LineBase;
+    // This parameter affects the meaning of the special opcodes. See below.
+    uint8_t LineRange;
+    // The number assigned to the first special opcode.
+    uint8_t OpcodeBase;
+    std::vector<uint8_t> StandardOpcodeLengths;
+    std::vector<std::string> IncludeDirectories;
+    std::vector<FileNameEntry> FileNames;
+
+    // Length of the prologue in bytes.
+    uint32_t getLength() const {
+      return PrologueLength + sizeof(TotalLength) + sizeof(Version) +
+             sizeof(PrologueLength);
+    }
+    // Length of the line table data in bytes (not including the prologue).
+    uint32_t getStatementTableLength() const {
+      return TotalLength + sizeof(TotalLength) - getLength();
+    }
+    int32_t getMaxLineIncrementForSpecialOpcode() const {
+      return LineBase + (int8_t)LineRange - 1;
+    }
+    void dump(raw_ostream &OS) const;
+    void clear() {
+      TotalLength = Version = PrologueLength = 0;
+      MinInstLength = LineBase = LineRange = OpcodeBase = 0;
+      StandardOpcodeLengths.clear();
+      IncludeDirectories.clear();
+      FileNames.clear();
+    }
+    bool getFile(uint32_t file_idx, std::string& file, std::string& dir) const;
+  };
+
+  // Standard .debug_line state machine structure.
+  struct Row {
+    Row(bool default_is_stmt = false) { reset(default_is_stmt); }
+    /// Called after a row is appended to the matrix.
+    void postAppend();
+    void reset(bool default_is_stmt);
+    void dump(raw_ostream &OS) const;
+
+    // The program-counter value corresponding to a machine instruction
+    // generated by the compiler.
+    uint64_t Address;
+    // An unsigned integer indicating a source line number. Lines are numbered
+    // beginning at 1. The compiler may emit the value 0 in cases where an
+    // instruction cannot be attributed to any source line.
+    uint32_t Line;
+    // An unsigned integer indicating a column number within a source line.
+    // Columns are numbered beginning at 1. The value 0 is reserved to indicate
+    // that a statement begins at the 'left edge' of the line.
+    uint16_t Column;
+    // An unsigned integer indicating the identity of the source file
+    // corresponding to a machine instruction.
+    uint16_t File;
+    // An unsigned integer whose value encodes the applicable instruction set
+    // architecture for the current instruction.
+    uint8_t Isa;
+    // A boolean indicating that the current instruction is the beginning of a
+    // statement.
+    uint8_t IsStmt:1,
+            // A boolean indicating that the current instruction is the
+            // beginning of a basic block.
+            BasicBlock:1,
+            // A boolean indicating that the current address is that of the
+            // first byte after the end of a sequence of target machine
+            // instructions.
+            EndSequence:1,
+            // A boolean indicating that the current address is one (of possibly
+            // many) where execution should be suspended for an entry breakpoint
+            // of a function.
+            PrologueEnd:1,
+            // A boolean indicating that the current address is one (of possibly
+            // many) where execution should be suspended for an exit breakpoint
+            // of a function.
+            EpilogueBegin:1;
+  };
+
+  struct LineTable {
+    void appendRow(const DWARFDebugLine::Row &state) { Rows.push_back(state); }
+    void clear() {
+      Prologue.clear();
+      Rows.clear();
+    }
+
+    uint32_t lookupAddress(uint64_t address, uint64_t cu_high_pc) const;
+    void dump(raw_ostream &OS) const;
+
+    struct Prologue Prologue;
+    std::vector<Row> Rows;
+  };
+
+  struct State : public Row, public LineTable {
+    // Special row codes.
+    enum {
+      StartParsingLineTable = 0,
+      DoneParsingLineTable = -1
+    };
+
+    State() : row(0) {}
+
+    virtual void appendRowToMatrix(uint32_t offset);
+    virtual void finalize(uint32_t offset) { row = DoneParsingLineTable; }
+    virtual void reset() { Row::reset(Prologue.DefaultIsStmt); }
+
+    // The row number that starts at zero for the prologue, and increases for
+    // each row added to the matrix.
+    unsigned row;
+  };
+
+  struct DumpingState : public State {
+    DumpingState(raw_ostream &OS) : OS(OS) {}
+    virtual void finalize(uint32_t offset);
+  private:
+    raw_ostream &OS;
+  };
+
+  static bool parsePrologue(DataExtractor debug_line_data, uint32_t *offset_ptr,
+                            Prologue *prologue);
+  /// Parse a single line table (prologue and all rows).
+  static bool parseStatementTable(DataExtractor debug_line_data,
+                                  uint32_t *offset_ptr, State &state);
+
+  /// Parse all information in the debug_line_data into an internal
+  /// representation.
+  void parse(DataExtractor debug_line_data);
+  void parseIfNeeded(DataExtractor debug_line_data) {
+    if (LineTableMap.empty())
+      parse(debug_line_data);
+  }
+  static void dump(DataExtractor debug_line_data, raw_ostream &OS);
+  const LineTable *getLineTable(uint32_t offset) const;
+
+protected:
+  typedef std::map<uint32_t, LineTable> LineTableMapTy;
+  typedef LineTableMapTy::iterator LineTableIter;
+  typedef LineTableMapTy::const_iterator LineTableConstIter;
+
+  LineTableMapTy LineTableMap;
+};
+
+}
+
+#endif