diff --git a/include/llvm/CodeGen/DwarfWriter.h b/include/llvm/CodeGen/DwarfWriter.h
index 1a7c5a5..e178c91 100644
--- a/include/llvm/CodeGen/DwarfWriter.h
+++ b/include/llvm/CodeGen/DwarfWriter.h
@@ -7,14 +7,26 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This file contains support for writing dwarf debug info into asm files.
+// This file contains support for writing Dwarf debug info into asm files.  For
+// Details on the Dwarf 3 specfication see DWARF Debugging Information Format
+// V.3 reference manual http://dwarf.freestandards.org ,
 //
+// The role of the Dwarf Writer class is to extract debug information from the
+// MachineDebugInfo object, organize it in Dwarf form and then emit it into asm
+// the current asm file using data and high level Dwarf directives.
+// 
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CODEGEN_DWARFPRINTER_H
 #define LLVM_CODEGEN_DWARFPRINTER_H
 
+#include "llvm/ADT/UniqueVector.h"
+
 #include <iosfwd>
+#include <map>
+#include <string>
+#include <vector>
+
 
 namespace llvm {
 
@@ -23,6 +35,8 @@
   // reference manual http://dwarf.freestandards.org .
   //
   enum dwarf_constants {
+    DWARF_VERSION = 2,
+    
    // Tags
     DW_TAG_array_type = 0x01,
     DW_TAG_class_type = 0x02,
@@ -425,23 +439,246 @@
     DW_CFA_hi_user = 0x3f
   };
   
+  //===--------------------------------------------------------------------===//
+  // DWLabel - Labels are used to track locations in the assembler file.
+  // Labels appear in the form <prefix>debug_<Tag><Number>, where the tag is a
+  // category of label (Ex. location) and number is a value unique in that
+  // category.
+  struct DWLabel {
+    const char *Tag;                    // Label category tag. Should always be
+                                        // a staticly declared C string.
+    unsigned    Number;                 // Unique number
+
+    DWLabel() : Tag(NULL), Number(0) {}
+    DWLabel(const char *T, unsigned N) : Tag(T), Number(N) {}
+  };
+
+  //===--------------------------------------------------------------------===//
+  // DIEAbbrev - Dwarf abbreviation, describes the organization of a debug
+  // information object.
+  //
+  class DIEAbbrev {
+  private:
+    const unsigned char *Data;          // Static array of bytes containing the
+                                        // image of the raw abbreviation data.
+
+  public:
+  
+    DIEAbbrev(const unsigned char *D)
+    : Data(D)
+    {}
+    
+    /// operator== - Used by UniqueVector to locate entry.
+    ///
+    bool operator==(const DIEAbbrev &DA) const {
+      return Data == DA.Data;
+    }
+
+    /// operator< - Used by UniqueVector to locate entry.
+    ///
+    bool operator<(const DIEAbbrev &DA) const {
+      return Data < DA.Data;
+    }
+
+    // Accessors
+    unsigned getTag()                 const { return Data[0]; }
+    unsigned getChildrenFlag()        const { return Data[1]; }
+    unsigned getAttribute(unsigned i) const { return Data[2 + 2 * i + 0]; }
+    unsigned getForm(unsigned i)      const { return Data[2 + 2 * i + 1]; }
+  };
+
+  //===--------------------------------------------------------------------===//
+  // DIEValue - A debug information entry value.
+  //
+  class DwarfWriter; 
+  class DIEValue {
+  public:
+    enum {
+      isInteger,
+      isString,
+      isLabel,
+      isDelta
+    };
+    
+    unsigned Type;                      // Type of the value
+    
+    DIEValue(unsigned T) : Type(T) {}
+    virtual ~DIEValue() {}
+    
+    // Implement isa/cast/dyncast.
+    static bool classof(const DIEValue *) { return true; }
+    
+    /// EmitValue - Emit value via the Dwarf writer.
+    ///
+    virtual void EmitValue(const DwarfWriter &DW, unsigned Form) const = 0;
+    
+    /// SizeOf - Return the size of a value in bytes.
+    ///
+    virtual unsigned SizeOf(const DwarfWriter &DW, unsigned Form) const = 0;
+  };
+
+  //===--------------------------------------------------------------------===//
+  // DWInteger - An integer value DIE.
+  // 
+  class DIEInteger : public DIEValue {
+  private:
+    int Value;
+    
+  public:
+    DIEInteger(int V) : DIEValue(isInteger), Value(V) {}
+
+    // Implement isa/cast/dyncast.
+    static bool classof(const DIEInteger *) { return true; }
+    static bool classof(const DIEValue *V)  { return V->Type == isInteger; }
+    
+    /// EmitValue - Emit integer of appropriate size.
+    ///
+    virtual void EmitValue(const DwarfWriter &DW, unsigned Form) const;
+    
+    /// SizeOf - Determine size of integer value in bytes.
+    ///
+    virtual unsigned SizeOf(const DwarfWriter &DW, unsigned Form) const;
+  };
+
+  //===--------------------------------------------------------------------===//
+  // DIEString - A string value DIE.
+  // 
+  struct DIEString : public DIEValue {
+    const std::string Value;
+    
+    DIEString(const std::string &V) : DIEValue(isString), Value(V) {}
+
+    // Implement isa/cast/dyncast.
+    static bool classof(const DIEString *) { return true; }
+    static bool classof(const DIEValue *V) { return V->Type == isString; }
+    
+    /// EmitValue - Emit string value.
+    ///
+    virtual void EmitValue(const DwarfWriter &DW, unsigned Form) const;
+    
+    /// SizeOf - Determine size of string value in bytes.
+    ///
+    virtual unsigned SizeOf(const DwarfWriter &DW, unsigned Form) const;
+  };
+
+  //===--------------------------------------------------------------------===//
+  // DIELabel - A simple label expression DIE.
+  //
+  struct DIELabel : public DIEValue {
+    const DWLabel Value;
+    
+    DIELabel(const DWLabel &V) : DIEValue(DW_FORM_ref4), Value(V) {}
+
+    // Implement isa/cast/dyncast.
+    static bool classof(const DWLabel *)   { return true; }
+    static bool classof(const DIEValue *V) { return V->Type == isLabel; }
+    
+    /// EmitValue - Emit label value.
+    ///
+    virtual void EmitValue(const DwarfWriter &DW, unsigned Form) const;
+    
+    /// SizeOf - Determine size of label value in bytes.
+    ///
+    virtual unsigned SizeOf(const DwarfWriter &DW, unsigned Form) const;
+  };
+
+  //===--------------------------------------------------------------------===//
+  // DIEDelta - A simple label difference DIE.
+  // 
+  struct DIEDelta : public DIEValue {
+    const DWLabel Value1;
+    const DWLabel Value2;
+    
+    DIEDelta(const DWLabel &V1, const DWLabel &V2)
+    : DIEValue(DW_FORM_addr), Value1(V1), Value2(V2) {}
+
+    // Implement isa/cast/dyncast.
+    static bool classof(const DIEDelta *)  { return true; }
+    static bool classof(const DIEValue *V) { return V->Type == isDelta; }
+    
+    /// EmitValue - Emit delta value.
+    ///
+    virtual void EmitValue(const DwarfWriter &DW, unsigned Form) const;
+    
+    /// SizeOf - Determine size of delta value in bytes.
+    ///
+    virtual unsigned SizeOf(const DwarfWriter &DW, unsigned Form) const;
+  };
+  
+  //===--------------------------------------------------------------------===//
+  // DIE - A structured debug information entry.  Has an abbreviation which
+  // describes it's organization.
+  class DIE {
+  private:
+    unsigned AbbrevID;                    // Decribing abbreviation ID.
+    unsigned Offset;                      // Offset in debug info section
+    unsigned Size;                        // Size of instance + children
+    std::vector<DIE *> Children;          // Children DIEs
+    std::vector<DIEValue *> Values;       // Attributes values
+    
+  public:
+    DIE(unsigned AbbrevID)
+    : AbbrevID(AbbrevID)
+    , Offset(0)
+    , Size(0)
+    , Children()
+    , Values()
+    {}
+    virtual ~DIE() {
+    }
+    
+    // Accessors
+    unsigned getAbbrevID()                     const { return AbbrevID; }
+    unsigned getOffset()                       const { return Offset; }
+    unsigned getSize()                         const { return Size; }
+    const std::vector<DIE *> &getChildren()    const { return Children; }
+    const std::vector<DIEValue *> &getValues() const { return Values; }
+    void setOffset(unsigned O)                 { Offset = O; }
+    void setSize(unsigned S)                   { Size = S; }
+    
+    /// AddValue - Add an attribute value of appropriate type.
+    ///
+    void AddValue(int Value) {
+      Values.push_back(new DIEInteger(Value));
+    }
+    void AddValue(const std::string &Value) {
+      Values.push_back(new DIEString(Value));
+    }
+    void AddValue(const DWLabel &Value) {
+      Values.push_back(new DIELabel(Value));
+    }
+    void AddValue(const DWLabel &Value1, const DWLabel &Value2) {
+      Values.push_back(new DIEDelta(Value1, Value2));
+    }
+    
+    /// SiblingOffset - Return the offset of the debug information entry's
+    /// sibling.
+    unsigned SiblingOffset() const { return Offset + Size; }
+  };
+
+  //===--------------------------------------------------------------------===//
   // Forward declarations.
   //
   class AsmPrinter;
   class MachineDebugInfo;
   
   //===--------------------------------------------------------------------===//
-  // DwarfWriter - emits dwarf debug and exception handling directives.
+  // DwarfWriter - emits Dwarf debug and exception handling directives.
   //
   class DwarfWriter {
   
   protected:
   
+    //===------------------------------------------------------------------===//
+    // Core attributes used by the Dwarf  writer.
+    //
+    
+    //
     /// O - Stream to .s file.
     ///
     std::ostream &O;
 
-    /// Asm - Target of dwarf emission.
+    /// Asm - Target of Dwarf emission.
     ///
     AsmPrinter *Asm;
     
@@ -454,8 +691,25 @@
     bool didInitial;
     
     //===------------------------------------------------------------------===//
+    // Attributes used to construct specific Dwarf sections.
+    //
+    
+    /// CompileUnits - All the compile units involved in this build.  The index
+    /// of each entry in this vector corresponds to the sources in DebugInfo.
+    std::vector<DIE *> CompileUnits;
+
+    /// Abbreviations - A UniqueVector of TAG structure abbreviations.
+    ///
+    UniqueVector<DIEAbbrev> Abbreviations;
+    
+    //===------------------------------------------------------------------===//
     // Properties to be set by the derived class ctor, used to configure the
-    // dwarf writer.
+    // Dwarf writer.
+    //
+    
+    /// AddressSize - Size of addresses used in file.
+    ///
+    unsigned AddressSize;
 
     /// hasLEB128 - True if target asm supports leb128 directives.
     ///
@@ -473,93 +727,174 @@
     /// directives.
     bool needsSet; /// Defaults to false.
     
-    /// DwarfAbbrevSection - section directive arg for dwarf abbrev.
+    /// DwarfAbbrevSection - Section directive for Dwarf abbrev.
     ///
     const char *DwarfAbbrevSection; /// Defaults to ".debug_abbrev".
 
-    /// DwarfInfoSection - section directive arg for dwarf info.
+    /// DwarfInfoSection - Section directive for Dwarf info.
     ///
     const char *DwarfInfoSection; /// Defaults to ".debug_info".
 
-    /// DwarfLineSection - section directive arg for dwarf info.
+    /// DwarfLineSection - Section directive for Dwarf info.
     ///
     const char *DwarfLineSection; /// Defaults to ".debug_line".
+    
+    /// TextSection - Section directive for standard text.
+    ///
+    const char *TextSection; /// Defaults to ".text".
+    
+    /// DataSection - Section directive for standard data.
+    ///
+    const char *DataSection; /// Defaults to ".data".
 
     //===------------------------------------------------------------------===//
+    // Emission and print routines
+    //
 
-  public:
-    
-    // Ctor.
-    DwarfWriter(std::ostream &o, AsmPrinter *ap)
-    : O(o)
-    , Asm(ap)
-    , DebugInfo(NULL)
-    , didInitial(false)
-    , hasLEB128(false)
-    , hasDotLoc(false)
-    , hasDotFile(false)
-    , needsSet(false)
-    , DwarfAbbrevSection(".debug_abbrev")
-    , DwarfInfoSection(".debug_info")
-    , DwarfLineSection(".debug_line")
-    {}
-    
-    /// SetDebugInfo - Set DebugInfo at when it's know that pass manager
-    /// has created it.
-    void SetDebugInfo(MachineDebugInfo *di) { DebugInfo = di; }
-    
-    /// EmitHex - Emit a hexidecimal string to the output stream.
+public:
+    /// getAddressSize - Return the size of a target address in bytes.
     ///
-    void EmitHex(unsigned Value) const;
-    
-    /// EmitComment - Emit a simple string comment.
-    ///
-    void EmitComment(const char *Comment) const;
+    unsigned getAddressSize() const { return AddressSize; }
 
-    /// EmitULEB128 - Emit a series of hexidecimal values (separated by commas)
-    /// representing an unsigned leb128 value.
+    /// PrintHex - Print a value as a hexidecimal value.
     ///
-    void EmitULEB128(unsigned Value) const;
+    void PrintHex(int Value) const;
 
-    /// EmitSLEB128 - Emit a series of hexidecimal values (separated by commas)
-    /// representing a signed leb128 value.
-    ///
-    void EmitSLEB128(int Value) const;
-    
-    /// EmitLabelName - Emit label name for internal use by dwarf.
-    ///
-    void EmitLabelName(const char *Tag, int Num) const;
-    
-    /// EmitLabel - Emit location label for internal use by dwarf.
-    ///
-    void EmitLabel(const char *Tag, int Num) const;
-    
+    /// EOL - Print a newline character to asm stream.  If a comment is present
+    /// then it will be printed first.  Comments should not contain '\n'.
+    void EOL(const std::string &Comment) const;
+                                          
     /// EmitULEB128Bytes - Emit an assembler byte data directive to compose an
-    /// unsigned leb128 value.  Comment is added to the end of the directive if
-    /// DwarfVerbose is true (should not contain any newlines.)
-    ///
-    void EmitULEB128Bytes(unsigned Value, const char *Comment) const;
+    /// unsigned leb128 value.
+    void EmitULEB128Bytes(unsigned Value) const;
     
-    /// EmitSLEB128Bytes - Emit an assembler byte data directive to compose a
-    /// signed leb128 value.  Comment is added to the end of the directive if
-    /// DwarfVerbose is true (should not contain any newlines.)
-    ///
-    void EmitSLEB128Bytes(int Value, const char *Comment) const;
+    /// EmitSLEB128Bytes - print an assembler byte data directive to compose a
+    /// signed leb128 value.
+    void EmitSLEB128Bytes(int Value) const;
     
-    /// EmitInitial - Emit initial dwarf declarations.
+    /// PrintULEB128 - Print a series of hexidecimal values (separated by
+    /// commas) representing an unsigned leb128 value.
+    void PrintULEB128(unsigned Value) const;
+
+    /// SizeULEB128 - Compute the number of bytes required for an unsigned
+    /// leb128 value.
+    static unsigned SizeULEB128(unsigned Value);
+    
+    /// PrintSLEB128 - Print a series of hexidecimal values (separated by
+    /// commas) representing a signed leb128 value.
+    void PrintSLEB128(int Value) const;
+    
+    /// SizeSLEB128 - Compute the number of bytes required for a signed leb128
+    /// value.
+    static unsigned SizeSLEB128(int Value);
+    
+    /// EmitByte - Emit a byte directive and value.
+    ///
+    void EmitByte(int Value) const;
+
+    /// EmitShort - Emit a short directive and value.
+    ///
+    void EmitShort(int Value) const;
+
+    /// EmitLong - Emit a long directive and value.
+    ///
+    void EmitLong(int Value) const;
+    
+    /// EmitString - Emit a string with quotes and a null terminator.
+    /// Special characters are emitted properly. (Eg. '\t')
+    void DwarfWriter::EmitString(const std::string &String) const;
+
+    /// PrintLabelName - Print label name in form used by Dwarf writer.
+    ///
+    void PrintLabelName(DWLabel Label) const {
+      PrintLabelName(Label.Tag, Label.Number);
+    }
+    void PrintLabelName(const char *Tag, unsigned Number) const;
+    
+    /// EmitLabel - Emit location label for internal use by Dwarf.
+    ///
+    void EmitLabel(DWLabel Label) const {
+      EmitLabel(Label.Tag, Label.Number);
+    }
+    void EmitLabel(const char *Tag, unsigned Number) const;
+    
+    /// EmitLabelReference - Emit a reference to a label.
+    ///
+    void EmitLabelReference(DWLabel Label) const {
+      EmitLabelReference(Label.Tag, Label.Number);
+    }
+    void EmitLabelReference(const char *Tag, unsigned Number) const;
+
+    /// EmitDifference - Emit the difference between two labels.  Some
+    /// assemblers do not behave with absolute expressions with data directives,
+    /// so there is an option (needsSet) to use an intermediary set expression.
+    void EmitDifference(DWLabel Label1, DWLabel Label2) const {
+      EmitDifference(Label1.Tag, Label1.Number, Label2.Tag, Label2.Number);
+    }
+    void EmitDifference(const char *Tag1, unsigned Number1,
+                        const char *Tag2, unsigned Number2) const;
+                                   
+private:
+    /// NewDIE - Construct a new structured debug information entry.
+    ///  
+    DIE *NewDIE(const unsigned char *AbbrevData);
+
+    /// NewCompileUnit - Create new compile unit information.
+    ///
+    DIE *NewCompileUnit(const std::string &Directory,
+                        const std::string &SourceName);
+
+    /// EmitInitial - Emit initial Dwarf declarations.
     ///
     void EmitInitial() const;
     
-    /// ShouldEmitDwarf - Returns true if dwarf declarations should be made.
-    /// When called it also checks to see if debug info is newly available.  if
-    /// so the initial dwarf headers are emitted.
-    bool ShouldEmitDwarf();
+    /// EmitDIE - Recusively Emits a debug information entry.
+    ///
+    void EmitDIE(DIE *Die) const;
+    
+    /// SizeAndOffsetDie - Compute the size and offset of a DIE.
+    ///
+    unsigned SizeAndOffsetDie(DIE *Die, unsigned Offset) const;
 
-    /// BeginModule - Emit all dwarf sections that should come prior to the
+    /// SizeAndOffsets - Compute the size and offset of all the DIEs.
+    ///
+    void SizeAndOffsets();
+    
+    /// EmitDebugInfo - Emit the debug info section.
+    ///
+    void EmitDebugInfo() const;
+    
+    /// EmitAbbreviations - Emit the abbreviation section.
+    ///
+    void EmitAbbreviations() const;
+    
+    /// EmitDebugLines - Emit source line information.
+    ///
+    void EmitDebugLines() const;
+
+    /// ShouldEmitDwarf - Returns true if Dwarf declarations should be made.
+    /// When called it also checks to see if debug info is newly available.  if
+    /// so the initial Dwarf headers are emitted.
+    bool ShouldEmitDwarf();
+    
+  public:
+    
+    DwarfWriter(std::ostream &o, AsmPrinter *ap);
+    virtual ~DwarfWriter();
+    
+    /// SetDebugInfo - Set DebugInfo when it's known that pass manager has
+    /// created it.  Set by the target AsmPrinter.
+    void SetDebugInfo(MachineDebugInfo *di) { DebugInfo = di; }
+    
+    //===------------------------------------------------------------------===//
+    // Main enties.
+    //
+    
+    /// BeginModule - Emit all Dwarf sections that should come prior to the
     /// content.
     void BeginModule();
     
-    /// EndModule - Emit all dwarf sections that should come after the content.
+    /// EndModule - Emit all Dwarf sections that should come after the content.
     ///
     void EndModule();
     
@@ -571,7 +906,6 @@
     ///
     void EndFunction();
   };
-  
 
 } // end llvm namespace
 
diff --git a/include/llvm/CodeGen/MachineDebugInfo.h b/include/llvm/CodeGen/MachineDebugInfo.h
index 039bdbc..5846748 100644
--- a/include/llvm/CodeGen/MachineDebugInfo.h
+++ b/include/llvm/CodeGen/MachineDebugInfo.h
@@ -10,17 +10,83 @@
 // Collect debug information for a module.  This information should be in a
 // neutral form that can be used by different debugging schemes.
 //
+// The organization of information is primarily clustered around the source
+// compile units.  The main exception is source line coorespondence where
+// inlining may interleave code from various compile units.
+//
+// The following information can be retrieved from the MachineDebugInfo.
+//
+//  -- Source directories - Directories are uniqued based on their canonical
+//     string and assigned a sequential numeric ID (base 1.)  A directory ID - 1
+//     provides the index of directory information in a queried directory list.
+//  -- Source files - Files are also uniqued based on their name and directory
+//     ID.  A file ID is sequential number (base 1.)  A file ID - 1 provides the
+//     index of source information in a queried file list.
+//  -- Source line coorespondence - A vector of file ID, line#, column# triples.
+//     A DEBUG_LOCATION instruction is generated  by the DAG Legalizer
+//     corresponding to each entry in the source line list.  This allows a debug
+//     information emitter to generate labels to map code addressed to debug
+//     tables.
+//
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CODEGEN_MACHINEDEBUGINFO_H
 #define LLVM_CODEGEN_MACHINEDEBUGINFO_H
 
 #include "llvm/Pass.h"
+#include "llvm/ADT/UniqueVector.h"
 #include <string>
-#include <map>
-#include <vector>
 
 namespace llvm {
+
+//===----------------------------------------------------------------------===//
+/// SourceLineInfo - This class is used to record source line correspondence.
+///
+class SourceLineInfo {
+private:
+  unsigned Line;                        // Source line number.
+  unsigned Column;                      // Source column.
+  unsigned SourceID;                    // Source ID number.
+
+public:
+  SourceLineInfo(unsigned L, unsigned C, unsigned S)
+  : Line(L), Column(C), SourceID(S) {}
+  
+  // Accessors
+  unsigned getLine()     const { return Line; }
+  unsigned getColumn()   const { return Column; }
+  unsigned getSourceID() const { return SourceID; }
+};
+
+//===----------------------------------------------------------------------===//
+/// SourceFileInfo - This class is used to track source information.
+///
+class SourceFileInfo {
+private:
+  unsigned DirectoryID;                 // Directory ID number.
+  std::string Name;                     // File name (not including directory.)
+  
+public:
+  SourceFileInfo(unsigned D, const std::string &N) : DirectoryID(D), Name(N) {}
+            
+  // Accessors
+  unsigned getDirectoryID()    const { return DirectoryID; }
+  const std::string &getName() const { return Name; }
+
+  /// operator== - Used by UniqueVector to locate entry.
+  ///
+  bool operator==(const SourceFileInfo &SI) const {
+    return getDirectoryID() == SI.getDirectoryID() && getName() == SI.getName();
+  }
+
+  /// operator< - Used by UniqueVector to locate entry.
+  ///
+  bool operator<(const SourceFileInfo &SI) const {
+    return getDirectoryID() < SI.getDirectoryID() ||
+          (getDirectoryID() == SI.getDirectoryID() && getName() < SI.getName());
+  }
+};
+
 //===----------------------------------------------------------------------===//
 /// MachineDebugInfo - This class contains debug information specific to a
 /// module.  Queries can be made by different debugging schemes and reformated
@@ -28,48 +94,70 @@
 ///
 class MachineDebugInfo : public ImmutablePass {
 private:
-  std::map<std::string, unsigned> SourceMap; // Map of source file path to id
-  unsigned SourceCount;                 // Number of source files (used to
-                                        // generate id)
-  unsigned UniqueID;                    // Number used to unique labels used
-                                        // by debugger.
+  // DirectoryMap - UniqueVector for directories.
+  UniqueVector<std::string> Directories;
+                                         
+  // SourceMap - UniqueVector for source files.
+  UniqueVector<SourceFileInfo> SourceFiles;
+
+  // Lines - List of of source line correspondence.
+  std::vector<SourceLineInfo *> Lines;
 
 public:
-  // Ctor.
   MachineDebugInfo()
-  : SourceMap()
-  , SourceCount(0)
-  , UniqueID(1)
+  : Directories()
+  , SourceFiles()
+  , Lines()
   {}
   ~MachineDebugInfo() { }
   
-  /// hasInfo - Returns true if debug info is present.
+  /// doInitialization - Initialize the debug state for a new module.
   ///
-  // FIXME - need scheme to suppress debug output.
-  bool hasInfo() const { return SourceCount != 0; }
-  
-  /// getNextUniqueID - Returns a unique number for labels used by debugger.
-  ///
-  unsigned getNextUniqueID() { return UniqueID++; }
-  
-  /// RecordLabel - Records location information and associates it with a
-  /// debug label.  Returns unique label id.
-  unsigned RecordLabel(unsigned Line, unsigned Col, unsigned SrcFile) {
-    // FIXME - actually record.
-    return getNextUniqueID();
-  }
-  
   bool doInitialization();
+  
+  
+  /// doFinalization - Tear down the debug state after completion of a module.
+  ///
   bool doFinalization();
   
-  /// getUniqueSourceID - Register a source file with debug info. Returns an id.
+  /// hasInfo - Returns true if debug info is present.
   ///
-  unsigned getUniqueSourceID(const std::string &fname, 
-                             const std::string &dirname);
+  // FIXME - need proper scheme to suppress debug output.
+  bool hasInfo() const { return !SourceFiles.empty(); }
   
-  /// getSourceFiles - Return a vector of files.  Vector index + 1 equals id.
+  /// RecordLabel - Records location information and associates it with a
+  /// debug label.  Returns a unique label ID used to generate a label and 
+  /// provide correspondence to the source line list.
+  unsigned RecordLabel(unsigned Line, unsigned Column, unsigned Source) {
+    Lines.push_back(new SourceLineInfo(Line, Column, Source));
+    return Lines.size();
+  }
+  
+  /// RecordSource - Register a source file with debug info. Returns an source
+  /// ID.
+  unsigned RecordSource(const std::string &Directory,
+                               const std::string &Source) {
+    unsigned DirectoryID = Directories.insert(Directory);
+    return SourceFiles.insert(SourceFileInfo(DirectoryID, Source));
+  }
+  
+  /// getDirectories - Return the UniqueVector of std::string representing
+  /// directories.
+  const UniqueVector<std::string> &getDirectories() const {
+    return Directories;
+  }
+  
+  /// getSourceFiles - Return the UniqueVector of source files. 
   ///
-  std::vector<std::string> getSourceFiles() const;
+  const UniqueVector<SourceFileInfo> &getSourceFiles() const {
+    return SourceFiles;
+  }
+  
+  /// getSourceLines - Return a vector of source lines.  Vector index + 1
+  /// equals label ID.
+  const std::vector<SourceLineInfo *> &getSourceLines() const {
+    return Lines;
+  }
   
 }; // End class MachineDebugInfo
 
diff --git a/lib/CodeGen/DwarfWriter.cpp b/lib/CodeGen/DwarfWriter.cpp
index b44b1aa..67a6464 100644
--- a/lib/CodeGen/DwarfWriter.cpp
+++ b/lib/CodeGen/DwarfWriter.cpp
@@ -13,6 +13,7 @@
 
 #include "llvm/CodeGen/DwarfWriter.h"
 
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/CodeGen/AsmPrinter.h"
 #include "llvm/CodeGen/MachineDebugInfo.h"
 #include "llvm/Support/CommandLine.h"
@@ -23,90 +24,776 @@
 
 static cl::opt<bool>
 DwarfVerbose("dwarf-verbose", cl::Hidden,
-                                cl::desc("Add comments to dwarf directives."));
+                                cl::desc("Add comments to Dwarf directives."));
+
+//===----------------------------------------------------------------------===//
+// Dwarf abbreviations used by this emitter.
+//
+
+static const unsigned char AbbrevTAG_compile_unit[] = {
+  DW_TAG_compile_unit,     DW_CHILDREN_yes,
+  DW_AT_stmt_list,         DW_FORM_data4,
+  DW_AT_high_pc,           DW_FORM_addr,
+  DW_AT_low_pc,            DW_FORM_addr,
+  DW_AT_producer,          DW_FORM_string,
+  DW_AT_language,          DW_FORM_data1,
+  DW_AT_name,              DW_FORM_string,
+  DW_AT_comp_dir,          DW_FORM_string,
+  0,                       0
+};
+  
+static const unsigned char AbbrevTAG_subprogram[] = {
+  DW_TAG_subprogram,       DW_CHILDREN_yes,
+  DW_AT_sibling,           DW_FORM_ref4,
+  DW_AT_external,          DW_FORM_flag,
+  DW_AT_name,              DW_FORM_string,
+  DW_AT_decl_file,         DW_FORM_data1,
+  DW_AT_decl_line,         DW_FORM_data1,
+  DW_AT_prototyped,        DW_FORM_flag,
+  DW_AT_type,              DW_FORM_ref4,
+  DW_AT_low_pc,            DW_FORM_addr,
+  DW_AT_high_pc,           DW_FORM_addr,
+  DW_AT_frame_base,        DW_FORM_block1,
+  0,                       0
+};
+  
+static const unsigned char AbbrevTAG_formal_parameter[] = {
+  DW_TAG_formal_parameter, DW_CHILDREN_no,
+  DW_AT_name,              DW_FORM_string,
+  DW_AT_decl_file,         DW_FORM_data1,
+  DW_AT_decl_line,         DW_FORM_data1,
+  DW_AT_type,              DW_FORM_ref4,
+  DW_AT_location,          DW_FORM_block1,
+  0,                       0
+};
+  
+static const unsigned char AbbrevTAG_base_type[] = {
+  DW_TAG_base_type,        DW_CHILDREN_no,
+  DW_AT_name,              DW_FORM_string,
+  DW_AT_byte_size,         DW_FORM_data1,
+  DW_AT_encoding,          DW_FORM_data1,
+  0,                       0
+};
+  
+static const unsigned char AbbrevTAG_pointer_type[] = {
+  DW_TAG_pointer_type,     DW_CHILDREN_no,
+  DW_AT_byte_size,         DW_FORM_data1,
+  DW_AT_type,              DW_FORM_ref4,
+  0,                       0
+};
+  
+static const unsigned char AbbrevTAG_array_type[] = {
+  DW_TAG_array_type,       DW_CHILDREN_yes,
+  DW_AT_sibling,           DW_FORM_ref4,
+  DW_AT_type,              DW_FORM_ref4,
+  0,                       0
+};
+  
+static const unsigned char AbbrevTAG_subrange_type[] = {
+  DW_TAG_subrange_type,    DW_CHILDREN_no,
+  0,                       0
+};
+  
+static const unsigned char AbbrevTAG_variable[] = {
+  DW_TAG_variable,         DW_CHILDREN_no,
+  DW_AT_name,              DW_FORM_string,
+  DW_AT_type,              DW_FORM_ref4,
+  DW_AT_external,          DW_FORM_flag,
+  DW_AT_artificial,        DW_FORM_flag,
+  DW_AT_declaration,       DW_FORM_flag,
+  0,                       0
+};
+
+//===----------------------------------------------------------------------===//
+
+/// TagString - Return the string for the specified tag.
+///
+static const char *TagString(unsigned Tag) {
+  switch(Tag) {
+    case DW_TAG_array_type:                return "TAG_array_type";
+    case DW_TAG_class_type:                return "TAG_class_type";
+    case DW_TAG_entry_point:               return "TAG_entry_point";
+    case DW_TAG_enumeration_type:          return "TAG_enumeration_type";
+    case DW_TAG_formal_parameter:          return "TAG_formal_parameter";
+    case DW_TAG_imported_declaration:      return "TAG_imported_declaration";
+    case DW_TAG_label:                     return "TAG_label";
+    case DW_TAG_lexical_block:             return "TAG_lexical_block";
+    case DW_TAG_member:                    return "TAG_member";
+    case DW_TAG_pointer_type:              return "TAG_pointer_type";
+    case DW_TAG_reference_type:            return "TAG_reference_type";
+    case DW_TAG_compile_unit:              return "TAG_compile_unit";
+    case DW_TAG_string_type:               return "TAG_string_type";
+    case DW_TAG_structure_type:            return "TAG_structure_type";
+    case DW_TAG_subroutine_type:           return "TAG_subroutine_type";
+    case DW_TAG_typedef:                   return "TAG_typedef";
+    case DW_TAG_union_type:                return "TAG_union_type";
+    case DW_TAG_unspecified_parameters:    return "TAG_unspecified_parameters";
+    case DW_TAG_variant:                   return "TAG_variant";
+    case DW_TAG_common_block:              return "TAG_common_block";
+    case DW_TAG_common_inclusion:          return "TAG_common_inclusion";
+    case DW_TAG_inheritance:               return "TAG_inheritance";
+    case DW_TAG_inlined_subroutine:        return "TAG_inlined_subroutine";
+    case DW_TAG_module:                    return "TAG_module";
+    case DW_TAG_ptr_to_member_type:        return "TAG_ptr_to_member_type";
+    case DW_TAG_set_type:                  return "TAG_set_type";
+    case DW_TAG_subrange_type:             return "TAG_subrange_type";
+    case DW_TAG_with_stmt:                 return "TAG_with_stmt";
+    case DW_TAG_access_declaration:        return "TAG_access_declaration";
+    case DW_TAG_base_type:                 return "TAG_base_type";
+    case DW_TAG_catch_block:               return "TAG_catch_block";
+    case DW_TAG_const_type:                return "TAG_const_type";
+    case DW_TAG_constant:                  return "TAG_constant";
+    case DW_TAG_enumerator:                return "TAG_enumerator";
+    case DW_TAG_file_type:                 return "TAG_file_type";
+    case DW_TAG_friend:                    return "TAG_friend";
+    case DW_TAG_namelist:                  return "TAG_namelist";
+    case DW_TAG_namelist_item:             return "TAG_namelist_item";
+    case DW_TAG_packed_type:               return "TAG_packed_type";
+    case DW_TAG_subprogram:                return "TAG_subprogram";
+    case DW_TAG_template_type_parameter:   return "TAG_template_type_parameter";
+    case DW_TAG_template_value_parameter: return "TAG_template_value_parameter";
+    case DW_TAG_thrown_type:               return "TAG_thrown_type";
+    case DW_TAG_try_block:                 return "TAG_try_block";
+    case DW_TAG_variant_part:              return "TAG_variant_part";
+    case DW_TAG_variable:                  return "TAG_variable";
+    case DW_TAG_volatile_type:             return "TAG_volatile_type";
+    case DW_TAG_dwarf_procedure:           return "TAG_dwarf_procedure";
+    case DW_TAG_restrict_type:             return "TAG_restrict_type";
+    case DW_TAG_interface_type:            return "TAG_interface_type";
+    case DW_TAG_namespace:                 return "TAG_namespace";
+    case DW_TAG_imported_module:           return "TAG_imported_module";
+    case DW_TAG_unspecified_type:          return "TAG_unspecified_type";
+    case DW_TAG_partial_unit:              return "TAG_partial_unit";
+    case DW_TAG_imported_unit:             return "TAG_imported_unit";
+    case DW_TAG_condition:                 return "TAG_condition";
+    case DW_TAG_shared_type:               return "TAG_shared_type";
+    case DW_TAG_lo_user:                   return "TAG_lo_user";
+    case DW_TAG_hi_user:                   return "TAG_hi_user";
+  }
+  assert(0 && "Unknown Dwarf Tag");
+  return "";
+}
+
+/// ChildrenString - Return the string for the specified children flag.
+///
+static const char *ChildrenString(unsigned Children) {
+  switch(Children) {
+    case DW_CHILDREN_no:                   return "CHILDREN_no";
+    case DW_CHILDREN_yes:                  return "CHILDREN_yes";
+  }
+  assert(0 && "Unknown Dwarf ChildrenFlag");
+  return "";
+}
+
+/// AttributeString - Return the string for the specified attribute.
+///
+static const char *AttributeString(unsigned Attribute) {
+  switch(Attribute) {
+    case DW_AT_sibling:                    return "AT_sibling";
+    case DW_AT_location:                   return "AT_location";
+    case DW_AT_name:                       return "AT_name";
+    case DW_AT_ordering:                   return "AT_ordering";
+    case DW_AT_byte_size:                  return "AT_byte_size";
+    case DW_AT_bit_offset:                 return "AT_bit_offset";
+    case DW_AT_bit_size:                   return "AT_bit_size";
+    case DW_AT_stmt_list:                  return "AT_stmt_list";
+    case DW_AT_low_pc:                     return "AT_low_pc";
+    case DW_AT_high_pc:                    return "AT_high_pc";
+    case DW_AT_language:                   return "AT_language";
+    case DW_AT_discr:                      return "AT_discr";
+    case DW_AT_discr_value:                return "AT_discr_value";
+    case DW_AT_visibility:                 return "AT_visibility";
+    case DW_AT_import:                     return "AT_import";
+    case DW_AT_string_length:              return "AT_string_length";
+    case DW_AT_common_reference:           return "AT_common_reference";
+    case DW_AT_comp_dir:                   return "AT_comp_dir";
+    case DW_AT_const_value:                return "AT_const_value";
+    case DW_AT_containing_type:            return "AT_containing_type";
+    case DW_AT_default_value:              return "AT_default_value";
+    case DW_AT_inline:                     return "AT_inline";
+    case DW_AT_is_optional:                return "AT_is_optional";
+    case DW_AT_lower_bound:                return "AT_lower_bound";
+    case DW_AT_producer:                   return "AT_producer";
+    case DW_AT_prototyped:                 return "AT_prototyped";
+    case DW_AT_return_addr:                return "AT_return_addr";
+    case DW_AT_start_scope:                return "AT_start_scope";
+    case DW_AT_bit_stride:                 return "AT_bit_stride";
+    case DW_AT_upper_bound:                return "AT_upper_bound";
+    case DW_AT_abstract_origin:            return "AT_abstract_origin";
+    case DW_AT_accessibility:              return "AT_accessibility";
+    case DW_AT_address_class:              return "AT_address_class";
+    case DW_AT_artificial:                 return "AT_artificial";
+    case DW_AT_base_types:                 return "AT_base_types";
+    case DW_AT_calling_convention:         return "AT_calling_convention";
+    case DW_AT_count:                      return "AT_count";
+    case DW_AT_data_member_location:       return "AT_data_member_location";
+    case DW_AT_decl_column:                return "AT_decl_column";
+    case DW_AT_decl_file:                  return "AT_decl_file";
+    case DW_AT_decl_line:                  return "AT_decl_line";
+    case DW_AT_declaration:                return "AT_declaration";
+    case DW_AT_discr_list:                 return "AT_discr_list";
+    case DW_AT_encoding:                   return "AT_encoding";
+    case DW_AT_external:                   return "AT_external";
+    case DW_AT_frame_base:                 return "AT_frame_base";
+    case DW_AT_friend:                     return "AT_friend";
+    case DW_AT_identifier_case:            return "AT_identifier_case";
+    case DW_AT_macro_info:                 return "AT_macro_info";
+    case DW_AT_namelist_item:              return "AT_namelist_item";
+    case DW_AT_priority:                   return "AT_priority";
+    case DW_AT_segment:                    return "AT_segment";
+    case DW_AT_specification:              return "AT_specification";
+    case DW_AT_static_link:                return "AT_static_link";
+    case DW_AT_type:                       return "AT_type";
+    case DW_AT_use_location:               return "AT_use_location";
+    case DW_AT_variable_parameter:         return "AT_variable_parameter";
+    case DW_AT_virtuality:                 return "AT_virtuality";
+    case DW_AT_vtable_elem_location:       return "AT_vtable_elem_location";
+    case DW_AT_allocated:                  return "AT_allocated";
+    case DW_AT_associated:                 return "AT_associated";
+    case DW_AT_data_location:              return "AT_data_location";
+    case DW_AT_byte_stride:                return "AT_byte_stride";
+    case DW_AT_entry_pc:                   return "AT_entry_pc";
+    case DW_AT_use_UTF8:                   return "AT_use_UTF8";
+    case DW_AT_extension:                  return "AT_extension";
+    case DW_AT_ranges:                     return "AT_ranges";
+    case DW_AT_trampoline:                 return "AT_trampoline";
+    case DW_AT_call_column:                return "AT_call_column";
+    case DW_AT_call_file:                  return "AT_call_file";
+    case DW_AT_call_line:                  return "AT_call_line";
+    case DW_AT_description:                return "AT_description";
+    case DW_AT_binary_scale:               return "AT_binary_scale";
+    case DW_AT_decimal_scale:              return "AT_decimal_scale";
+    case DW_AT_small:                      return "AT_small";
+    case DW_AT_decimal_sign:               return "AT_decimal_sign";
+    case DW_AT_digit_count:                return "AT_digit_count";
+    case DW_AT_picture_string:             return "AT_picture_string";
+    case DW_AT_mutable:                    return "AT_mutable";
+    case DW_AT_threads_scaled:             return "AT_threads_scaled";
+    case DW_AT_explicit:                   return "AT_explicit";
+    case DW_AT_object_pointer:             return "AT_object_pointer";
+    case DW_AT_endianity:                  return "AT_endianity";
+    case DW_AT_elemental:                  return "AT_elemental";
+    case DW_AT_pure:                       return "AT_pure";
+    case DW_AT_recursive:                  return "AT_recursive";
+    case DW_AT_lo_user:                    return "AT_lo_user";
+    case DW_AT_hi_user:                    return "AT_hi_user";
+  }
+  assert(0 && "Unknown Dwarf Attribute");
+  return "";
+}
+
+/// FormEncodingString - Return the string for the specified form encoding.
+///
+static const char *FormEncodingString(unsigned Encoding) {
+  switch(Encoding) {
+    case DW_FORM_addr:                     return "FORM_addr";
+    case DW_FORM_block2:                   return "FORM_block2";
+    case DW_FORM_block4:                   return "FORM_block4";
+    case DW_FORM_data2:                    return "FORM_data2";
+    case DW_FORM_data4:                    return "FORM_data4";
+    case DW_FORM_data8:                    return "FORM_data8";
+    case DW_FORM_string:                   return "FORM_string";
+    case DW_FORM_block:                    return "FORM_block";
+    case DW_FORM_block1:                   return "FORM_block1";
+    case DW_FORM_data1:                    return "FORM_data1";
+    case DW_FORM_flag:                     return "FORM_flag";
+    case DW_FORM_sdata:                    return "FORM_sdata";
+    case DW_FORM_strp:                     return "FORM_strp";
+    case DW_FORM_udata:                    return "FORM_udata";
+    case DW_FORM_ref_addr:                 return "FORM_ref_addr";
+    case DW_FORM_ref1:                     return "FORM_ref1";
+    case DW_FORM_ref2:                     return "FORM_ref2";
+    case DW_FORM_ref4:                     return "FORM_ref4";
+    case DW_FORM_ref8:                     return "FORM_ref8";
+    case DW_FORM_ref_udata:                return "FORM_ref_udata";
+    case DW_FORM_indirect:                 return "FORM_indirect";
+  }
+  assert(0 && "Unknown Dwarf Form Encoding");
+  return "";
+}
+
+/// OperationEncodingString - Return the string for the specified operation
+/// encoding.
+static const char *OperationEncodingString(unsigned Encoding) {
+  switch(Encoding) {
+    case DW_OP_addr:                       return "OP_addr";
+    case DW_OP_deref:                      return "OP_deref";
+    case DW_OP_const1u:                    return "OP_const1u";
+    case DW_OP_const1s:                    return "OP_const1s";
+    case DW_OP_const2u:                    return "OP_const2u";
+    case DW_OP_const2s:                    return "OP_const2s";
+    case DW_OP_const4u:                    return "OP_const4u";
+    case DW_OP_const4s:                    return "OP_const4s";
+    case DW_OP_const8u:                    return "OP_const8u";
+    case DW_OP_const8s:                    return "OP_const8s";
+    case DW_OP_constu:                     return "OP_constu";
+    case DW_OP_consts:                     return "OP_consts";
+    case DW_OP_dup:                        return "OP_dup";
+    case DW_OP_drop:                       return "OP_drop";
+    case DW_OP_over:                       return "OP_over";
+    case DW_OP_pick:                       return "OP_pick";
+    case DW_OP_swap:                       return "OP_swap";
+    case DW_OP_rot:                        return "OP_rot";
+    case DW_OP_xderef:                     return "OP_xderef";
+    case DW_OP_abs:                        return "OP_abs";
+    case DW_OP_and:                        return "OP_and";
+    case DW_OP_div:                        return "OP_div";
+    case DW_OP_minus:                      return "OP_minus";
+    case DW_OP_mod:                        return "OP_mod";
+    case DW_OP_mul:                        return "OP_mul";
+    case DW_OP_neg:                        return "OP_neg";
+    case DW_OP_not:                        return "OP_not";
+    case DW_OP_or:                         return "OP_or";
+    case DW_OP_plus:                       return "OP_plus";
+    case DW_OP_plus_uconst:                return "OP_plus_uconst";
+    case DW_OP_shl:                        return "OP_shl";
+    case DW_OP_shr:                        return "OP_shr";
+    case DW_OP_shra:                       return "OP_shra";
+    case DW_OP_xor:                        return "OP_xor";
+    case DW_OP_skip:                       return "OP_skip";
+    case DW_OP_bra:                        return "OP_bra";
+    case DW_OP_eq:                         return "OP_eq";
+    case DW_OP_ge:                         return "OP_ge";
+    case DW_OP_gt:                         return "OP_gt";
+    case DW_OP_le:                         return "OP_le";
+    case DW_OP_lt:                         return "OP_lt";
+    case DW_OP_ne:                         return "OP_ne";
+    case DW_OP_lit0:                       return "OP_lit0";
+    case DW_OP_lit1:                       return "OP_lit1";
+    case DW_OP_lit31:                      return "OP_lit31";
+    case DW_OP_reg0:                       return "OP_reg0";
+    case DW_OP_reg1:                       return "OP_reg1";
+    case DW_OP_reg31:                      return "OP_reg31";
+    case DW_OP_breg0:                      return "OP_breg0";
+    case DW_OP_breg1:                      return "OP_breg1";
+    case DW_OP_breg31:                     return "OP_breg31";
+    case DW_OP_regx:                       return "OP_regx";
+    case DW_OP_fbreg:                      return "OP_fbreg";
+    case DW_OP_bregx:                      return "OP_bregx";
+    case DW_OP_piece:                      return "OP_piece";
+    case DW_OP_deref_size:                 return "OP_deref_size";
+    case DW_OP_xderef_size:                return "OP_xderef_size";
+    case DW_OP_nop:                        return "OP_nop";
+    case DW_OP_push_object_address:        return "OP_push_object_address";
+    case DW_OP_call2:                      return "OP_call2";
+    case DW_OP_call4:                      return "OP_call4";
+    case DW_OP_call_ref:                   return "OP_call_ref";
+    case DW_OP_form_tls_address:           return "OP_form_tls_address";
+    case DW_OP_call_frame_cfa:             return "OP_call_frame_cfa";
+    case DW_OP_lo_user:                    return "OP_lo_user";
+    case DW_OP_hi_user:                    return "OP_hi_user";
+  }
+  assert(0 && "Unknown Dwarf Operation Encoding");
+  return "";
+}
+
+/// AttributeEncodingString - Return the string for the specified attribute
+/// encoding.
+static const char *AttributeEncodingString(unsigned Encoding) {
+  switch(Encoding) {
+    case DW_ATE_address:                   return "ATE_address";
+    case DW_ATE_boolean:                   return "ATE_boolean";
+    case DW_ATE_complex_float:             return "ATE_complex_float";
+    case DW_ATE_float:                     return "ATE_float";
+    case DW_ATE_signed:                    return "ATE_signed";
+    case DW_ATE_signed_char:               return "ATE_signed_char";
+    case DW_ATE_unsigned:                  return "ATE_unsigned";
+    case DW_ATE_unsigned_char:             return "ATE_unsigned_char";
+    case DW_ATE_imaginary_float:           return "ATE_imaginary_float";
+    case DW_ATE_packed_decimal:            return "ATE_packed_decimal";
+    case DW_ATE_numeric_string:            return "ATE_numeric_string";
+    case DW_ATE_edited:                    return "ATE_edited";
+    case DW_ATE_signed_fixed:              return "ATE_signed_fixed";
+    case DW_ATE_unsigned_fixed:            return "ATE_unsigned_fixed";
+    case DW_ATE_decimal_float:             return "ATE_decimal_float";
+    case DW_ATE_lo_user:                   return "ATE_lo_user";
+    case DW_ATE_hi_user:                   return "ATE_hi_user";
+  }
+  assert(0 && "Unknown Dwarf Attribute Encoding");
+  return "";
+}
+
+/// DecimalSignString - Return the string for the specified decimal sign
+/// attribute.
+static const char *DecimalSignString(unsigned Sign) {
+  switch(Sign) {
+    case DW_DS_unsigned:                   return "DS_unsigned";
+    case DW_DS_leading_overpunch:          return "DS_leading_overpunch";
+    case DW_DS_trailing_overpunch:         return "DS_trailing_overpunch";
+    case DW_DS_leading_separate:           return "DS_leading_separate";
+    case DW_DS_trailing_separate:          return "DS_trailing_separate";
+  }
+  assert(0 && "Unknown Dwarf Decimal Sign Attribute");
+  return "";
+}
+
+/// EndianityString - Return the string for the specified endianity.
+///
+static const char *EndianityString(unsigned Endian) {
+  switch(Endian) {
+    case DW_END_default:                   return "END_default";
+    case DW_END_big:                       return "END_big";
+    case DW_END_little:                    return "END_little";
+    case DW_END_lo_user:                   return "END_lo_user";
+    case DW_END_hi_user:                   return "END_hi_user";
+  }
+  assert(0 && "Unknown Dwarf Endianity");
+  return "";
+}
+
+/// AccessibilityString - Return the string for the specified accessibility.
+///
+static const char *AccessibilityString(unsigned Access) {
+  switch(Access) {
+    // Accessibility codes
+    case DW_ACCESS_public:                 return "ACCESS_public";
+    case DW_ACCESS_protected:              return "ACCESS_protected";
+    case DW_ACCESS_private:                return "ACCESS_private";
+  }
+  assert(0 && "Unknown Dwarf Accessibility");
+  return "";
+}
+
+/// VisibilityString - Return the string for the specified visibility.
+///
+static const char *VisibilityString(unsigned Visibility) {
+  switch(Visibility) {
+    case DW_VIS_local:                     return "VIS_local";
+    case DW_VIS_exported:                  return "VIS_exported";
+    case DW_VIS_qualified:                 return "VIS_qualified";
+  }
+  assert(0 && "Unknown Dwarf Visibility");
+  return "";
+}
+
+/// VirtualityString - Return the string for the specified virtuality.
+///
+static const char *VirtualityString(unsigned Virtuality) {
+  switch(Virtuality) {
+    case DW_VIRTUALITY_none:               return "VIRTUALITY_none";
+    case DW_VIRTUALITY_virtual:            return "VIRTUALITY_virtual";
+    case DW_VIRTUALITY_pure_virtual:       return "VIRTUALITY_pure_virtual";
+  }
+  assert(0 && "Unknown Dwarf Virtuality");
+  return "";
+}
+
+/// LanguageString - Return the string for the specified language.
+///
+static const char *LanguageString(unsigned Language) {
+  switch(Language) {
+    case DW_LANG_C89:                      return "LANG_C89";
+    case DW_LANG_C:                        return "LANG_C";
+    case DW_LANG_Ada83:                    return "LANG_Ada83";
+    case DW_LANG_C_plus_plus:              return "LANG_C_plus_plus";
+    case DW_LANG_Cobol74:                  return "LANG_Cobol74";
+    case DW_LANG_Cobol85:                  return "LANG_Cobol85";
+    case DW_LANG_Fortran77:                return "LANG_Fortran77";
+    case DW_LANG_Fortran90:                return "LANG_Fortran90";
+    case DW_LANG_Pascal83:                 return "LANG_Pascal83";
+    case DW_LANG_Modula2:                  return "LANG_Modula2";
+    case DW_LANG_Java:                     return "LANG_Java";
+    case DW_LANG_C99:                      return "LANG_C99";
+    case DW_LANG_Ada95:                    return "LANG_Ada95";
+    case DW_LANG_Fortran95:                return "LANG_Fortran95";
+    case DW_LANG_PLI:                      return "LANG_PLI";
+    case DW_LANG_ObjC:                     return "LANG_ObjC";
+    case DW_LANG_ObjC_plus_plus:           return "LANG_ObjC_plus_plus";
+    case DW_LANG_UPC:                      return "LANG_UPC";
+    case DW_LANG_D:                        return "LANG_D";
+    case DW_LANG_lo_user:                  return "LANG_lo_user";
+    case DW_LANG_hi_user:                  return "LANG_hi_user";
+  }
+  assert(0 && "Unknown Dwarf Language");
+  return "";
+}
+
+/// CaseString - Return the string for the specified identifier case.
+///
+static const char *CaseString(unsigned Case) {
+   switch(Case) {
+    case DW_ID_case_sensitive:             return "ID_case_sensitive";
+    case DW_ID_up_case:                    return "ID_up_case";
+    case DW_ID_down_case:                  return "ID_down_case";
+    case DW_ID_case_insensitive:           return "ID_case_insensitive";
+  }
+  assert(0 && "Unknown Dwarf Identifier Case");
+  return "";
+}
+
+/// ConventionString - Return the string for the specified calling convention.
+///
+static const char *ConventionString(unsigned Convention) {
+   switch(Convention) {
+    case DW_CC_normal:                     return "CC_normal";
+    case DW_CC_program:                    return "CC_program";
+    case DW_CC_nocall:                     return "CC_nocall";
+    case DW_CC_lo_user:                    return "CC_lo_user";
+    case DW_CC_hi_user:                    return "CC_hi_user";
+  }
+  assert(0 && "Unknown Dwarf Calling Convention");
+  return "";
+}
+
+/// InlineCodeString - Return the string for the specified inline code.
+///
+static const char *InlineCodeString(unsigned Code) {
+   switch(Code) {
+    case DW_INL_not_inlined:               return "INL_not_inlined";
+    case DW_INL_inlined:                   return "INL_inlined";
+    case DW_INL_declared_not_inlined:      return "INL_declared_not_inlined";
+    case DW_INL_declared_inlined:          return "INL_declared_inlined";
+  }
+  assert(0 && "Unknown Dwarf Inline Code");
+  return "";
+}
+
+/// ArrayOrderString - Return the string for the specified array order.
+///
+static const char *ArrayOrderString(unsigned Order) {
+   switch(Order) {
+    case DW_ORD_row_major:                 return "ORD_row_major";
+    case DW_ORD_col_major:                 return "ORD_col_major";
+  }
+  assert(0 && "Unknown Dwarf Array Order");
+  return "";
+}
+
+/// DiscriminantString - Return the string for the specified discriminant
+/// descriptor.
+static const char *DiscriminantString(unsigned Discriminant) {
+   switch(Discriminant) {
+    case DW_DSC_label:                     return "DSC_label";
+    case DW_DSC_range:                     return "DSC_range";
+  }
+  assert(0 && "Unknown Dwarf Discriminant Descriptor");
+  return "";
+}
+
+/// LNStandardString - Return the string for the specified line number standard.
+///
+static const char *LNStandardString(unsigned Standard) {
+   switch(Standard) {
+    case DW_LNS_copy:                      return "LNS_copy";
+    case DW_LNS_advance_pc:                return "LNS_advance_pc";
+    case DW_LNS_advance_line:              return "LNS_advance_line";
+    case DW_LNS_set_file:                  return "LNS_set_file";
+    case DW_LNS_set_column:                return "LNS_set_column";
+    case DW_LNS_negate_stmt:               return "LNS_negate_stmt";
+    case DW_LNS_set_basic_block:           return "LNS_set_basic_block";
+    case DW_LNS_const_add_pc:              return "LNS_const_add_pc";
+    case DW_LNS_fixed_advance_pc:          return "LNS_fixed_advance_pc";
+    case DW_LNS_set_prologue_end:          return "LNS_set_prologue_end";
+    case DW_LNS_set_epilogue_begin:        return "LNS_set_epilogue_begin";
+    case DW_LNS_set_isa:                   return "LNS_set_isa";
+  }
+  assert(0 && "Unknown Dwarf Line Number Standard");
+  return "";
+}
+
+/// LNExtendedString - Return the string for the specified line number extended
+/// opcode encodings.
+static const char *LNExtendedString(unsigned Encoding) {
+   switch(Encoding) {
+    // Line Number Extended Opcode Encodings
+    case DW_LNE_end_sequence:              return "LNE_end_sequence";
+    case DW_LNE_set_address:               return "LNE_set_address";
+    case DW_LNE_define_file:               return "LNE_define_file";
+    case DW_LNE_lo_user:                   return "LNE_lo_user";
+    case DW_LNE_hi_user:                   return "LNE_hi_user";
+  }
+  assert(0 && "Unknown Dwarf Line Number Extended Opcode Encoding");
+  return "";
+}
+
+/// MacinfoString - Return the string for the specified macinfo type encodings.
+///
+static const char *MacinfoString(unsigned Encoding) {
+   switch(Encoding) {
+    // Macinfo Type Encodings
+    case DW_MACINFO_define:                return "MACINFO_define";
+    case DW_MACINFO_undef:                 return "MACINFO_undef";
+    case DW_MACINFO_start_file:            return "MACINFO_start_file";
+    case DW_MACINFO_end_file:              return "MACINFO_end_file";
+    case DW_MACINFO_vendor_ext:            return "MACINFO_vendor_ext";
+  }
+  assert(0 && "Unknown Dwarf Macinfo Type Encodings");
+  return "";
+}
+
+/// CallFrameString - Return the string for the specified call frame instruction
+/// encodings.
+static const char *CallFrameString(unsigned Encoding) {
+   switch(Encoding) {
+    case DW_CFA_advance_loc:               return "CFA_advance_loc";
+    case DW_CFA_offset:                    return "CFA_offset";
+    case DW_CFA_restore:                   return "CFA_restore";
+    case DW_CFA_set_loc:                   return "CFA_set_loc";
+    case DW_CFA_advance_loc1:              return "CFA_advance_loc1";
+    case DW_CFA_advance_loc2:              return "CFA_advance_loc2";
+    case DW_CFA_advance_loc4:              return "CFA_advance_loc4";
+    case DW_CFA_offset_extended:           return "CFA_offset_extended";
+    case DW_CFA_restore_extended:          return "CFA_restore_extended";
+    case DW_CFA_undefined:                 return "CFA_undefined";
+    case DW_CFA_same_value:                return "CFA_same_value";
+    case DW_CFA_register:                  return "CFA_register";
+    case DW_CFA_remember_state:            return "CFA_remember_state";
+    case DW_CFA_restore_state:             return "CFA_restore_state";
+    case DW_CFA_def_cfa:                   return "CFA_def_cfa";
+    case DW_CFA_def_cfa_register:          return "CFA_def_cfa_register";
+    case DW_CFA_def_cfa_offset:            return "CFA_def_cfa_offset";
+    case DW_CFA_def_cfa_expression:        return "CFA_def_cfa_expression";
+    case DW_CFA_expression:                return "CFA_expression";
+    case DW_CFA_offset_extended_sf:        return "CFA_offset_extended_sf";
+    case DW_CFA_def_cfa_sf:                return "CFA_def_cfa_sf";
+    case DW_CFA_def_cfa_offset_sf:         return "CFA_def_cfa_offset_sf";
+    case DW_CFA_val_offset:                return "CFA_val_offset";
+    case DW_CFA_val_offset_sf:             return "CFA_val_offset_sf";
+    case DW_CFA_val_expression:            return "CFA_val_expression";
+    case DW_CFA_lo_user:                   return "CFA_lo_user";
+    case DW_CFA_hi_user:                   return "CFA_hi_user";
+  }
+  assert(0 && "Unknown Dwarf Call Frame Instruction Encodings");
+  return "";
+}
+
+//===----------------------------------------------------------------------===//
+
+/// EmitValue - Emit integer of appropriate size.
+///
+void DIEInteger::EmitValue(const DwarfWriter &DW, unsigned Form) const {
+  switch (Form) {
+  case DW_FORM_data1: DW.EmitByte(Value);  break;
+  case DW_FORM_data2: DW.EmitShort(Value); break;
+  case DW_FORM_data4: DW.EmitLong(Value);  break;
+  default: assert(0 && "DIE Value form not supported yet"); break;
+  }
+}
+
+/// SizeOf - Determine size of integer value in bytes.
+///
+unsigned DIEInteger::SizeOf(const DwarfWriter &DW, unsigned Form) const {
+  switch (Form) {
+  case DW_FORM_data1: return sizeof(int8_t);
+  case DW_FORM_data2: return sizeof(int16_t);
+  case DW_FORM_data4: return sizeof(int32_t);
+  default: assert(0 && "DIE Value form not supported yet"); break;
+  }
+  return 0;
+}
+
+//===----------------------------------------------------------------------===//
+
+/// EmitValue - Emit string value.
+///
+void DIEString::EmitValue(const DwarfWriter &DW, unsigned Form) const {
+  DW.EmitString(Value);
+}
+
+/// SizeOf - Determine size of string value in bytes.
+///
+unsigned DIEString::SizeOf(const DwarfWriter &DW, unsigned Form) const {
+  return Value.size() + sizeof(int8_t);
+}
+
+//===----------------------------------------------------------------------===//
+
+/// EmitValue - Emit label value.
+///
+void DIELabel::EmitValue(const DwarfWriter &DW, unsigned Form) const {
+  DW.EmitLabelReference(Value);
+}
+
+/// SizeOf - Determine size of label value in bytes.
+///
+unsigned DIELabel::SizeOf(const DwarfWriter &DW, unsigned Form) const {
+  return DW.getAddressSize();
+}
+    
+//===----------------------------------------------------------------------===//
+
+/// EmitValue - Emit delta value.
+///
+void DIEDelta::EmitValue(const DwarfWriter &DW, unsigned Form) const {
+  DW.EmitDifference(Value1, Value2);
+}
+
+/// SizeOf - Determine size of delta value in bytes.
+///
+unsigned DIEDelta::SizeOf(const DwarfWriter &DW, unsigned Form) const {
+  return DW.getAddressSize();
+}
+
+//===----------------------------------------------------------------------===//
+
+/// PrintHex - Print a value as a hexidecimal value.
+///
+void DwarfWriter::PrintHex(int Value) const { 
+  O << "0x" << std::hex << Value << std::dec;
+}
+
+/// EOL - Print a newline character to asm stream.  If a comment is present
+/// then it will be printed first.  Comments should not contain '\n'.
+void DwarfWriter::EOL(const std::string &Comment) const {
+  if (DwarfVerbose) {
+    O << "\t"
+      << Asm->CommentString
+      << " "
+      << Comment;
+  }
+  O << "\n";
+}
 
 /// EmitULEB128Bytes - Emit an assembler byte data directive to compose an
-/// unsigned leb128 value.  Comment is added to the end of the directive if
-/// DwarfVerbose is true (should not contain any newlines.)
-///
-void DwarfWriter::EmitULEB128Bytes(unsigned Value, const char *Comment) const {
+/// unsigned leb128 value.
+void DwarfWriter::EmitULEB128Bytes(unsigned Value) const {
   if (hasLEB128) {
     O << "\t.uleb128\t"
       << Value;
   } else {
     O << Asm->Data8bitsDirective;
-    EmitULEB128(Value);
+    PrintULEB128(Value);
   }
-  if (DwarfVerbose) {
-    O << "\t"
-      << Asm->CommentString
-      << " "
-      << Comment
-      << " "
-      << Value;
-  }
-  O << "\n";
 }
 
 /// EmitSLEB128Bytes - Emit an assembler byte data directive to compose a
-/// signed leb128 value.  Comment is added to the end of the directive if
-/// DwarfVerbose is true (should not contain any newlines.)
-///
-void DwarfWriter::EmitSLEB128Bytes(int Value, const char *Comment) const {
+/// signed leb128 value.
+void DwarfWriter::EmitSLEB128Bytes(int Value) const {
   if (hasLEB128) {
     O << "\t.sleb128\t"
       << Value;
   } else {
     O << Asm->Data8bitsDirective;
-    EmitSLEB128(Value);
+    PrintSLEB128(Value);
   }
-  if (DwarfVerbose) {
-    O << "\t"
-      << Asm->CommentString
-      << " "
-      << Comment
-      << " "
-      << Value;
-  }
-  O << "\n";
 }
 
-/// EmitHex - Emit a hexidecimal string to the output stream.
-///
-void DwarfWriter::EmitHex(unsigned Value) const {
-  O << "0x"
-    << std::hex
-    << Value
-    << std::dec;
-}
-
-/// EmitComment - Emit a simple string comment.
-///
-void DwarfWriter::EmitComment(const char *Comment) const {
-  O << "\t"
-    << Asm->CommentString
-    << " "
-    << Comment
-    << "\n";
-}
-
-/// EmitULEB128 - Emit a series of hexidecimal values (separated by commas)
+/// PrintULEB128 - Print a series of hexidecimal values (separated by commas)
 /// representing an unsigned leb128 value.
-///
-void DwarfWriter::EmitULEB128(unsigned Value) const {
+void DwarfWriter::PrintULEB128(unsigned Value) const {
   do {
     unsigned Byte = Value & 0x7f;
     Value >>= 7;
     if (Value) Byte |= 0x80;
-    EmitHex(Byte);
+    PrintHex(Byte);
     if (Value) O << ", ";
   } while (Value);
 }
 
-/// EmitSLEB128 - Emit a series of hexidecimal values (separated by commas)
+/// SizeULEB128 - Compute the number of bytes required for an unsigned leb128
+/// value.
+unsigned DwarfWriter::SizeULEB128(unsigned Value) {
+  unsigned Size = 0;
+  do {
+    Value >>= 7;
+    Size += sizeof(int8_t);
+  } while (Value);
+  return Size;
+}
+
+/// PrintSLEB128 - Print a series of hexidecimal values (separated by commas)
 /// representing a signed leb128 value.
-///
-void DwarfWriter::EmitSLEB128(int Value) const {
+void DwarfWriter::PrintSLEB128(int Value) const {
   int Sign = Value >> (8 * sizeof(Value) - 1);
   bool IsMore;
   
@@ -115,40 +802,499 @@
     Value >>= 7;
     IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0;
     if (IsMore) Byte |= 0x80;
-    EmitHex(Byte);
+    PrintHex(Byte);
     if (IsMore) O << ", ";
   } while (IsMore);
 }
 
-/// EmitLabelName - Emit label name for internal use by dwarf.
+/// SizeSLEB128 - Compute the number of bytes required for a signed leb128
+/// value.
+unsigned DwarfWriter::SizeSLEB128(int Value) {
+  unsigned Size = 0;
+  int Sign = Value >> (8 * sizeof(Value) - 1);
+  bool IsMore;
+  
+  do {
+    unsigned Byte = Value & 0x7f;
+    Value >>= 7;
+    IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0;
+    Size += sizeof(int8_t);
+  } while (IsMore);
+  return Size;
+}
+
+/// EmitByte - Emit a byte directive and value.
 ///
-void DwarfWriter::EmitLabelName(const char *Tag, int Num) const {
+void DwarfWriter::EmitByte(int Value) const {
+  O << Asm->Data8bitsDirective;
+  PrintHex(Value);
+}
+
+/// EmitShort - Emit a short directive and value.
+///
+void DwarfWriter::EmitShort(int Value) const {
+  O << Asm->Data16bitsDirective;
+  PrintHex(Value);
+}
+
+/// EmitLong - Emit a long directive and value.
+///
+void DwarfWriter::EmitLong(int Value) const {
+  O << Asm->Data32bitsDirective;
+  PrintHex(Value);
+}
+
+/// EmitString - Emit a string with quotes and a null terminator.
+/// Special characters are emitted properly. (Eg. '\t')
+void DwarfWriter::EmitString(const std::string &String) const {
+  O << Asm->AsciiDirective
+    << "\"";
+  for (unsigned i = 0, N = String.size(); i < N; i++) {
+    unsigned char C = String[i];
+    
+    if (!isascii(C) || iscntrl(C)) {
+      switch(C) {
+      case '\b': O << "\\b"; break;
+      case '\f': O << "\\f"; break;
+      case '\n': O << "\\n"; break;
+      case '\r': O << "\\r"; break;
+      case '\t': O << "\\t"; break;
+      default:
+        O << '\\';
+        O << char('0' + (C >> 6));
+        O << char('0' + (C >> 3));
+        O << char('0' + (C >> 0));
+        break;
+      }
+    } else if (C == '\"') {
+      O << "\\\"";
+    } else if (C == '\'') {
+      O << "\\\'";
+    } else {
+     O << C;
+    }
+  }
+  O << "\\0\"";
+}
+
+/// PrintLabelName - Print label name in form used by Dwarf writer.
+///
+void DwarfWriter::PrintLabelName(const char *Tag, unsigned Number) const {
   O << Asm->PrivateGlobalPrefix
     << "debug_"
     << Tag
-    << Num;
+    << Number;
 }
 
-/// EmitLabel - Emit location label for internal use by dwarf.
+/// EmitLabel - Emit location label for internal use by Dwarf.
 ///
-void DwarfWriter::EmitLabel(const char *Tag, int Num) const {
-  EmitLabelName(Tag, Num);
+void DwarfWriter::EmitLabel(const char *Tag, unsigned Number) const {
+  PrintLabelName(Tag, Number);
   O << ":\n";
 }
 
-/// EmitInitial -Emit initial dwarf declarations.
+/// EmitLabelReference - Emit a reference to a label.
+///
+void DwarfWriter::EmitLabelReference(const char *Tag, unsigned Number) const {
+  if (AddressSize == 4)
+    O << Asm->Data32bitsDirective;
+  else
+    O << Asm->Data64bitsDirective;
+    
+  PrintLabelName(Tag, Number);
+}
+
+/// EmitDifference - Emit an label difference as sizeof(pointer) value.  Some
+/// assemblers do not accept absolute expressions with data directives, so there 
+/// is an option (needsSet) to use an intermediary 'set' expression.
+void DwarfWriter::EmitDifference(const char *Tag1, unsigned Number1,
+                                 const char *Tag2, unsigned Number2) const {
+  if (needsSet) {
+    static unsigned SetCounter = 0;
+    O << "\t.set\t";
+    PrintLabelName("set", SetCounter);
+    O << ",";
+    PrintLabelName(Tag1, Number1);
+    O << "-";
+    PrintLabelName(Tag2, Number2);
+    O << "\n";
+    
+    if (AddressSize == sizeof(int32_t))
+      O << Asm->Data32bitsDirective;
+    else
+      O << Asm->Data64bitsDirective;
+      
+    PrintLabelName("set", SetCounter);
+    
+    SetCounter++;
+  } else {
+    if (AddressSize == sizeof(int32_t))
+      O << Asm->Data32bitsDirective;
+    else
+      O << Asm->Data64bitsDirective;
+      
+    PrintLabelName(Tag1, Number1);
+    O << "-";
+    PrintLabelName(Tag2, Number2);
+  }
+}
+
+/// NewDIE - Construct a new structured debug information entry.
+///  
+DIE *DwarfWriter::NewDIE(const unsigned char *AbbrevData) {
+  // Get the abbreviation ID.
+  unsigned AbbrevID = Abbreviations.insert(DIEAbbrev(AbbrevData));
+  // Allocate new new structured DIE.
+  DIE *Die = new DIE(AbbrevID);
+  // Return  structured DIE.
+  return Die;
+}
+
+/// NewCompileUnit - Create new compile unit information.
+///
+DIE *DwarfWriter::NewCompileUnit(const std::string &Directory,
+                                 const std::string &SourceName) {
+  DIE *Die = NewDIE(AbbrevTAG_compile_unit);
+  // FIXME - use the correct line set.
+  Die->AddValue(DWLabel("line", 0));
+  Die->AddValue(DWLabel("text_end", 0));
+  Die->AddValue(DWLabel("text_begin", 0));
+  // FIXME - The producer needs to be in this form, but should come from
+  // an appropriate source.
+  Die->AddValue("llvm 3.4.x (LLVM Research Group)");
+  Die->AddValue(DW_LANG_C89);
+  Die->AddValue(SourceName);
+  Die->AddValue(Directory);
+  
+  return Die;
+}
+
+/// EmitInitial - Emit initial Dwarf declarations.  This is necessary for cc
+/// tools to recognize the object file contains Dwarf information.
 ///
 void DwarfWriter::EmitInitial() const {
-  // Dwarf section's base addresses.
+  // Dwarf sections base addresses.
   Asm->SwitchSection(DwarfAbbrevSection, 0);
   EmitLabel("abbrev", 0);
   Asm->SwitchSection(DwarfInfoSection, 0);
   EmitLabel("info", 0);
   Asm->SwitchSection(DwarfLineSection, 0);
   EmitLabel("line", 0);
+  
+  // Standard sections base addresses.
+  Asm->SwitchSection(TextSection, 0);
+  EmitLabel("text_begin", 0);
+  Asm->SwitchSection(DataSection, 0);
+  EmitLabel("data_begin", 0);
 }
 
-/// ShouldEmitDwarf - Determine if dwarf declarations should be made.
+/// EmitDIE - Recusively Emits a debug information entry.
+///
+void DwarfWriter::EmitDIE(DIE *Die) const {
+  // Get the abbreviation for this DIE.
+  unsigned AbbrevID = Die->getAbbrevID();
+  const DIEAbbrev &Abbrev = Abbreviations[AbbrevID];
+
+  // Emit the code (index) for the abbreviation.
+  EmitULEB128Bytes(AbbrevID);
+  EOL(std::string("Abbrev [" +
+      utostr(AbbrevID) +
+      TagString(Abbrev.getTag())) +
+      " ");
+  
+  const std::vector<DIEValue *> &Values = Die->getValues();
+  
+  // Emit the DIE attribute values.
+  for (unsigned i = 0, N = Values.size(); i < N; i++) {
+    unsigned Attr = Abbrev.getAttribute(i);
+    unsigned Form = Abbrev.getForm(i);
+    assert(Form && "Too many attributes for DIE (check abbreviation)");
+    
+    switch (Attr) {
+    case DW_AT_sibling: {
+      EmitLong(Die->SiblingOffset());
+      break;
+    }
+    default: {
+      // Emit an attribute using the defined form.
+      Values[i]->EmitValue(*this, Form);
+      break;
+    }
+    }
+    
+    EOL(AttributeString(Attr));
+  }
+  
+  // Emit the DIE children if any.
+  if (Abbrev.getChildrenFlag() == DW_CHILDREN_yes) {
+    const std::vector<DIE *> &Children = Die->getChildren();
+    
+    for (unsigned j = 0, M = Children.size(); j < M; j++) {
+      // FIXME - handle sibling offsets.
+      // FIXME - handle all DIE types.
+      EmitDIE(Children[j]);
+    }
+    
+    EmitByte(0); EOL("End Of Children Mark");
+  }
+}
+
+/// SizeAndOffsetDie - Compute the size and offset of a DIE.
+///
+unsigned DwarfWriter::SizeAndOffsetDie(DIE *Die, unsigned Offset) const {
+  // Get the abbreviation for this DIE.
+  unsigned AbbrevID = Die->getAbbrevID();
+  const DIEAbbrev &Abbrev = Abbreviations[AbbrevID];
+
+  // Set DIE offset
+  Die->setOffset(Offset);
+  
+  // Start the size with the size of abbreviation code.
+  Offset += SizeULEB128(AbbrevID);
+  
+  const std::vector<DIEValue *> &Values = Die->getValues();
+
+  // Emit the DIE attribute values.
+  for (unsigned i = 0, N = Values.size(); i < N; i++) {
+    // Size attribute value.
+    Offset += Values[i]->SizeOf(*this, Abbrev.getForm(i));
+  }
+  
+  // Emit the DIE children if any.
+  if (Abbrev.getChildrenFlag() == DW_CHILDREN_yes) {
+    const std::vector<DIE *> &Children = Die->getChildren();
+    
+    for (unsigned j = 0, M = Children.size(); j < M; j++) {
+      // FIXME - handle sibling offsets.
+      // FIXME - handle all DIE types.
+      Offset = SizeAndOffsetDie(Children[j], Offset);
+    }
+    
+    // End of children marker.
+    Offset += sizeof(int8_t);
+  }
+
+  Die->setSize(Offset - Die->getOffset());
+  return Offset;
+}
+
+/// SizeAndOffsets - Compute the size and offset of all the DIEs.
+///
+void DwarfWriter::SizeAndOffsets() {
+  // Compute size of debug unit header
+  unsigned Offset = sizeof(int32_t) + // Length of Compilation Unit Info
+                    sizeof(int16_t) + // DWARF version number
+                    sizeof(int32_t) + // Offset Into Abbrev. Section
+                    sizeof(int8_t);  // Pointer Size (in bytes)
+  
+  // Process each compile unit.
+  for (unsigned i = 0, N = CompileUnits.size(); i < N; i++) {
+    Offset = SizeAndOffsetDie(CompileUnits[i], Offset);
+  }
+}
+
+/// EmitDebugInfo - Emit the debug info section.
+///
+void DwarfWriter::EmitDebugInfo() const {
+  // Start debug info section.
+  Asm->SwitchSection(DwarfInfoSection, 0);
+  
+  // Get the number of compile units.
+  unsigned N = CompileUnits.size();
+  
+  // If there are any compile units.
+  if (N) {
+    // Emit the compile units header.
+
+    // Emit size of content not including length itself
+    unsigned ContentSize = CompileUnits[N - 1]->SiblingOffset();
+    EmitLong(ContentSize - sizeof(int32_t));
+    EOL("Length of Compilation Unit Info");
+    
+    EmitShort(DWARF_VERSION); EOL("DWARF version number");
+
+    EmitLabelReference("abbrev", 0); EOL("Offset Into Abbrev. Section");
+
+    EmitByte(AddressSize); EOL("Address Size (in bytes)");
+    
+    // Process each compile unit.
+    for (unsigned i = 0; i < N; i++) {
+      EmitDIE(CompileUnits[i]);
+    }
+  }
+}
+
+/// EmitAbbreviations - Emit the abbreviation section.
+///
+void DwarfWriter::EmitAbbreviations() const {
+  // Start the debug abbrev section.
+  Asm->SwitchSection(DwarfAbbrevSection, 0);
+  
+  // For each abbrevation.
+  for (unsigned AbbrevID = 1, NAID = Abbreviations.size();
+                AbbrevID <= NAID; AbbrevID++) {
+    // Get abbreviation data
+    const DIEAbbrev &Abbrev = Abbreviations[AbbrevID];
+    
+    // Emit the abbrevations code (base 1 index.)
+    EmitULEB128Bytes(AbbrevID); EOL("Abbreviation Code");
+    
+    // Emit its Dwarf tag type.
+    EmitULEB128Bytes(Abbrev.getTag());
+    EOL(TagString(Abbrev.getTag()));
+    
+    // Emit whether it has children DIEs.
+    EmitULEB128Bytes(Abbrev.getChildrenFlag());
+    EOL(ChildrenString(Abbrev.getChildrenFlag()));
+    
+    // For each attribute description.
+    for (unsigned i = 0; ; i++) {
+      unsigned Attr = Abbrev.getAttribute(i);
+      unsigned Form = Abbrev.getForm(i);
+      
+      // Attributes are null terminated.
+      if (!Attr) break;
+      
+      // Emit attribute type.
+      EmitULEB128Bytes(Attr);
+      EOL(AttributeString(Attr));
+      
+      // Emit form type.
+      EmitULEB128Bytes(Form);
+      EOL(FormEncodingString(Form));
+    }
+
+    // Mark end of abbreviation.
+    EmitULEB128Bytes(0); EOL("EOM(1)");
+    EmitULEB128Bytes(0); EOL("EOM(2)");
+  }
+}
+
+/// EmitDebugLines - Emit source line information.
+///
+void DwarfWriter::EmitDebugLines() const {
+  // Minimum line delta, thus ranging from -10..(255-10).
+  const int MinLineDelta = -(DW_LNS_fixed_advance_pc + 1);
+  // Maximum line delta, thus ranging from -10..(255-10).
+  const int MaxLineDelta = 255 + MinLineDelta;
+
+  // Start the dwarf line section.
+  Asm->SwitchSection(DwarfLineSection, 0);
+  
+  // Construct the section header.
+  
+  EmitDifference("line_end", 0, "line_begin", 0);
+  EOL("Length of Source Line Info");
+  EmitLabel("line_begin", 0);
+  
+  EmitShort(DWARF_VERSION); EOL("DWARF version number");
+  
+  EmitDifference("line_prolog_end", 0, "line_prolog_begin", 0);
+  EOL("Prolog Length");
+  EmitLabel("line_prolog_begin", 0);
+  
+  EmitByte(1); EOL("Minimum Instruction Length");
+
+  EmitByte(1); EOL("Default is_stmt_start flag");
+
+  EmitByte(MinLineDelta);  EOL("Line Base Value (Special Opcodes)");
+  
+  EmitByte(MaxLineDelta); EOL("Line Range Value (Special Opcodes)");
+
+  EmitByte(-MinLineDelta); EOL("Special Opcode Base");
+  
+  // Line number standard opcode encodings argument count
+  EmitByte(0); EOL("DW_LNS_copy arg count");
+  EmitByte(1); EOL("DW_LNS_advance_pc arg count");
+  EmitByte(1); EOL("DW_LNS_advance_line arg count");
+  EmitByte(1); EOL("DW_LNS_set_file arg count");
+  EmitByte(1); EOL("DW_LNS_set_column arg count");
+  EmitByte(0); EOL("DW_LNS_negate_stmt arg count");
+  EmitByte(0); EOL("DW_LNS_set_basic_block arg count");
+  EmitByte(0); EOL("DW_LNS_const_add_pc arg count");
+  EmitByte(1); EOL("DW_LNS_fixed_advance_pc arg count");
+
+  const UniqueVector<std::string> &Directories = DebugInfo->getDirectories();
+  const UniqueVector<SourceFileInfo> &SourceFiles = DebugInfo->getSourceFiles();
+
+  // Emit directories.
+  for (unsigned DirectoryID = 1, NDID = Directories.size();
+                DirectoryID <= NDID; DirectoryID++) {
+    EmitString(Directories[DirectoryID]); EOL("Directory");
+  }
+  EmitByte(0); EOL("End of directories");
+  
+  // Emit files.
+  for (unsigned SourceID = 1, NSID = SourceFiles.size();
+               SourceID <= NSID; SourceID++) {
+    const SourceFileInfo &SourceFile = SourceFiles[SourceID];
+    EmitString(SourceFile.getName()); EOL("Source");
+    EmitULEB128Bytes(SourceFile.getDirectoryID());  EOL("Directory #");
+    EmitULEB128Bytes(0);  EOL("Mod date");
+    EmitULEB128Bytes(0);  EOL("File size");
+  }
+  EmitByte(0); EOL("End of files");
+  
+  EmitLabel("line_prolog_end", 0);
+  
+  // Emit line information
+  const std::vector<SourceLineInfo *> &LineInfos = DebugInfo->getSourceLines();
+  
+  // Dwarf assumes we start with first line of first source file.
+  unsigned Source = 1;
+  unsigned Line = 1;
+  
+  // Construct rows of the address, source, line, column matrix.
+  for (unsigned i = 0, N = LineInfos.size(); i < N; i++) {
+    SourceLineInfo *LineInfo = LineInfos[i];
+
+    // Define the line address.
+    EmitByte(0); EOL("Extended Op");
+    EmitByte(4 + 1); EOL("Op size");
+    EmitByte(DW_LNE_set_address); EOL("DW_LNE_set_address");
+    EmitLabelReference("loc", i + 1); EOL("Location label");
+    
+    // If change of source, then switch to the new source.
+    if (Source != LineInfo->getSourceID()) {
+      Source = LineInfo->getSourceID();
+      EmitByte(DW_LNS_set_file); EOL("DW_LNS_set_file");
+      EmitULEB128Bytes(0); EOL("New Source");
+    }
+    
+    // If change of line.
+    if (Line != LineInfo->getLine()) {
+      // Determine offset.
+      int Offset = LineInfo->getLine() - Line;
+      int Delta = Offset - MinLineDelta;
+      
+      // Update line.
+      Line = LineInfo->getLine();
+      
+      // If delta is small enough and in range...
+      if (Delta >= 0 && Delta < (MaxLineDelta - 1)) {
+        // ... then use fast opcode.
+        EmitByte(Delta - MinLineDelta); EOL("Line Delta");
+      } else {
+        // ... otherwise use long hand.
+        EmitByte(DW_LNS_advance_line); EOL("DW_LNS_advance_line");
+        EmitSLEB128Bytes(Offset); EOL("Line Offset");
+        EmitByte(DW_LNS_copy); EOL("DW_LNS_copy");
+      }
+    } else {
+      // Copy the previous row (different address or source)
+      EmitByte(DW_LNS_copy); EOL("DW_LNS_copy");
+    }
+  }
+
+  // Mark end of matrix.
+  EmitByte(0); EOL("DW_LNE_end_sequence");
+  EmitULEB128Bytes(1);  O << "\n";
+  EmitByte(1); O << "\n";
+  
+  EmitLabel("line_end", 0);
+}
+
+/// ShouldEmitDwarf - Determine if Dwarf declarations should be made.
 ///
 bool DwarfWriter::ShouldEmitDwarf() {
   // Check if debug info is present.
@@ -164,35 +1310,85 @@
   return true;
 }
 
-/// BeginModule - Emit all dwarf sections that should come prior to the content.
+//===----------------------------------------------------------------------===//
+// Main enties.
+//
+    
+  DwarfWriter::DwarfWriter(std::ostream &o, AsmPrinter *ap)
+  : O(o)
+  , Asm(ap)
+  , DebugInfo(NULL)
+  , didInitial(false)
+  , CompileUnits()
+  , Abbreviations()
+  , AddressSize(sizeof(int32_t))
+  , hasLEB128(false)
+  , hasDotLoc(false)
+  , hasDotFile(false)
+  , needsSet(false)
+  , DwarfAbbrevSection(".debug_abbrev")
+  , DwarfInfoSection(".debug_info")
+  , DwarfLineSection(".debug_line")
+  , TextSection(".text")
+  , DataSection(".data")
+  {}
+  DwarfWriter::~DwarfWriter() {
+  }
+
+/// BeginModule - Emit all Dwarf sections that should come prior to the content.
 ///
 void DwarfWriter::BeginModule() {
   if (!ShouldEmitDwarf()) return;
-  EmitComment("Dwarf Begin Module");
+  EOL("Dwarf Begin Module");
 }
 
-/// EndModule - Emit all dwarf sections that should come after the content.
+/// EndModule - Emit all Dwarf sections that should come after the content.
 ///
 void DwarfWriter::EndModule() {
   if (!ShouldEmitDwarf()) return;
-  EmitComment("Dwarf End Module");
-  // Print out dwarf file info
-  std::vector<std::string> Sources = DebugInfo->getSourceFiles();
-  for (unsigned i = 0, N = Sources.size(); i < N; i++) {
-    O << "\t; .file\t" << (i + 1) << "," << "\"" << Sources[i]  << "\"" << "\n";
+  EOL("Dwarf End Module");
+  
+  // Standard sections final addresses.
+  EmitLabel("text_end", 0);
+  EmitLabel("data_end", 0);
+
+  // Get directory and source information.
+  const UniqueVector<std::string> &Directories = DebugInfo->getDirectories();
+  const UniqueVector<SourceFileInfo> &SourceFiles = DebugInfo->getSourceFiles();
+
+  // Construct compile unit DIEs for each source.
+  for (unsigned SourceID = 1, NSID = SourceFiles.size();
+                SourceID <=  NSID; SourceID++) {
+    const SourceFileInfo &SourceFile = SourceFiles[SourceID];
+    const std::string &Directory = Directories[SourceFile.getDirectoryID()];
+    const std::string &SourceName = SourceFile.getName();
+    DIE *CompileUnit = NewCompileUnit(Directory, SourceName);
+    CompileUnits.push_back(CompileUnit);
   }
+
+  // Compute DIE offsets and sizes.
+  SizeAndOffsets();
+  
+  // Emit all the DIEs into a debug info section
+  EmitDebugInfo();
+  
+  // Corresponding abbreviations into a abbrev section.
+  EmitAbbreviations();
+  
+  // Emit source line correspondence into a debug line section.
+  EmitDebugLines();
 }
 
 /// BeginFunction - Emit pre-function debug information.
 ///
 void DwarfWriter::BeginFunction() {
   if (!ShouldEmitDwarf()) return;
-  EmitComment("Dwarf Begin Function");
+  EOL("Dwarf Begin Function");
 }
 
 /// EndFunction - Emit post-function debug information.
 ///
 void DwarfWriter::EndFunction() {
   if (!ShouldEmitDwarf()) return;
-  EmitComment("Dwarf End Function");
+  EOL("Dwarf End Function");
 }
diff --git a/lib/CodeGen/MachineDebugInfo.cpp b/lib/CodeGen/MachineDebugInfo.cpp
index d2a5fd5..5464686 100644
--- a/lib/CodeGen/MachineDebugInfo.cpp
+++ b/lib/CodeGen/MachineDebugInfo.cpp
@@ -6,11 +6,6 @@
 // the University of Illinois Open Source License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
-//
-// Collect debug information for a module.  This information should be in a
-// neutral form that can be used by different debugging schemes.
-//
-//===----------------------------------------------------------------------===//
 
 #include "llvm/CodeGen/MachineDebugInfo.h"
 
@@ -20,7 +15,9 @@
 namespace {
   RegisterPass<MachineDebugInfo> X("machinedebuginfo", "Debug Information");
 }
+
   
+//===----------------------------------------------------------------------===//
 /// doInitialization - Initialize the debug state for a new module.
 ///
 bool MachineDebugInfo::doInitialization() {
@@ -32,38 +29,3 @@
 bool MachineDebugInfo::doFinalization() {
   return false;
 }
-
-/// getUniqueSourceID - Register a source file with debug info.  Returns an id.
-///
-unsigned MachineDebugInfo::getUniqueSourceID(const std::string &fname,
-                                             const std::string &dirname) {
-  // Compose a key
-  const std::string path = dirname + "/" + fname;
-  // Check if the source file is already recorded
-  std::map<std::string, unsigned>::iterator
-      SMI = SourceMap.lower_bound(path);
-  // If already there return existing id
-  if (SMI != SourceMap.end() && SMI->first == path) return SMI->second;
-  // Bump up the count
-  ++SourceCount;
-  // Record the count
-  SourceMap.insert(SMI, std::make_pair(path, SourceCount));
-  // Return id
-  return SourceCount;
-}
-
-/// getSourceFiles - Return a vector of files.  Vector index + 1 equals id.
-///
-std::vector<std::string> MachineDebugInfo::getSourceFiles() const {
-  std::vector<std::string> Sources(SourceCount);
-  
-  for (std::map<std::string, unsigned>::const_iterator SMI = SourceMap.begin(),
-                                                       E = SourceMap.end();
-                                                       SMI != E; SMI++) {
-    unsigned Index = SMI->second - 1;
-    const std::string &Path = SMI->first;
-    Sources[Index] = Path;
-  }
-  return Sources;
-}
-
diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index fcc3a95..a53be0a 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -627,7 +627,7 @@
           cast<StringSDNode>(Node->getOperand(3))->getValue();
         const std::string &DirName = 
           cast<StringSDNode>(Node->getOperand(4))->getValue();
-        unsigned SrcFile = DebugInfo->getUniqueSourceID(FName, DirName);
+        unsigned SrcFile = DebugInfo->RecordSource(DirName, FName);
 
         std::vector<SDOperand> Ops;
         Ops.push_back(Tmp1);  // chain
diff --git a/lib/Target/PowerPC/PPCAsmPrinter.cpp b/lib/Target/PowerPC/PPCAsmPrinter.cpp
index de865db..55f54c4 100644
--- a/lib/Target/PowerPC/PPCAsmPrinter.cpp
+++ b/lib/Target/PowerPC/PPCAsmPrinter.cpp
@@ -215,9 +215,11 @@
     : DwarfWriter(o, ap)
     {
       needsSet = true;
-      DwarfAbbrevSection = ".section __DWARFA,__debug_abbrev,regular,debug";
-      DwarfInfoSection = ".section __DWARFA,__debug_info,regular,debug";
-      DwarfLineSection = ".section __DWARFA,__debug_line,regular,debug";
+      DwarfAbbrevSection = ".section __DWARF,__debug_abbrev,regular,debug";
+      DwarfInfoSection = ".section __DWARF,__debug_info,regular,debug";
+      DwarfLineSection = ".section __DWARF,__debug_line,regular,debug";
+      TextSection = ".text";
+      DataSection = ".data";
     }
   };
 
@@ -607,6 +609,9 @@
     }
   }
 
+  // Emit initial debug information.
+  DW.EndModule();
+
   // Funny Darwin hack: This flag tells the linker that no global symbols
   // contain code that falls through to other global symbols (e.g. the obvious
   // implementation of multiple entry points).  If this doesn't occur, the
@@ -614,9 +619,6 @@
   // code that does this, it is always safe to set.
   O << "\t.subsections_via_symbols\n";
 
-  // Emit initial debug information.
-  DW.EndModule();
-
   AsmPrinter::doFinalization(M);
   return false; // success
 }