More verbose debug printer.

Like, for example the clang, CompCert now prints a more detailed
descriptions of the debug information in the assembler file. For
each abbreviation and debug entry the dwarf attributes and their encodings
are added.
Bug 17392.

3 files changed, 273 insertions, 226 deletions

diff --git a/debug/DwarfPrinter.ml b/debug/DwarfPrinter.ml
index b7ecb62c..abed6a91 100644
--- a/debug/DwarfPrinter.ml
+++ b/debug/DwarfPrinter.ml
@@ -27,51 +27,57 @@ module DwarfPrinter(Target: DWARF_TARGET):
 
     open Target
 
+    let print_comment oc s =
+      if s <> "" then
+        fprintf oc "	%s %s" comment s
+
+    let string_of_comment s = sprintf "	%s %s" comment s
+
+    let add_comment buf s =
+      Buffer.add_string buf (sprintf "	%s %s" comment s)
+
     (* Byte value to string *)
-    let string_of_byte value =
-      sprintf "	.byte		%s\n" (if value then "0x1" else "0x0")
+    let string_of_byte value ct =
+      sprintf "	.byte		%s%s\n" (if value then "0x1" else "0x0") (string_of_comment ct)
 
     (* Print a label *)
     let print_label oc lbl =
       fprintf oc "%a:\n" label lbl
 
-    (* Print a positive label *)
-    let print_plabel oc lbl =
-      print_label oc (transl_label lbl)
-
     (* Helper functions for abbreviation printing *)
-    let add_byte buf value =
-      Buffer.add_string buf (string_of_byte value)
+    let add_byte buf value ct =
+      Buffer.add_string buf (string_of_byte value ct)
 
-    let add_abbr_uleb v buf =
-      Buffer.add_string buf (Printf.sprintf "	.uleb128	%d\n" v)
+    let add_abbr_uleb v ct buf =
+      Buffer.add_string buf (sprintf "	.uleb128	%d%s\n" v (string_of_comment ct))
+
+     let add_abbr_entry (v1,c1,v2) buf =
+       add_abbr_uleb v1 c1 buf;
+       let v2,c2 = code_of_dw_form v2 in
+       Buffer.add_string buf (sprintf "	.uleb128	%d%s\n" v2 (string_of_comment c2))
 
-    let add_abbr_entry (v1,v2) buf =
-      add_abbr_uleb v1 buf;
-      add_abbr_uleb v2 buf
 
     let add_file_loc buf =
-      let file,line = file_loc_type_abbr in
-      add_abbr_entry (0x3a,file) buf;
-      add_abbr_entry (0x3b,line) buf
+      add_abbr_entry (0x3a,"DW_AT_decl_file",DW_FORM_data4) buf;
+      add_abbr_entry (0x3b,"DW_AT_decl_line",DW_FORM_udata) buf
 
-    let add_type = add_abbr_entry (0x49,type_abbr)
+    let add_type = add_abbr_entry (0x49,"DW_AT_type",DW_FORM_ref_addr)
 
-    let add_byte_size = add_abbr_entry (0xb,byte_size_type_abbr)
+    let add_byte_size = add_abbr_entry (0x0b,"DW_AT_byte_size",DW_FORM_data1)
 
-    let add_member_size = add_abbr_entry (0xb,member_size_abbr)
+    let add_member_size = add_abbr_entry (0x0b,"DW_AT_byte_size",DW_FORM_udata)
 
-    let add_high_pc = add_abbr_entry (0x12,high_pc_type_abbr)
+    let add_high_pc = add_abbr_entry (0x12,"DW_AT_high_pc",DW_FORM_addr)
 
-    let add_low_pc = add_abbr_entry (0x11,low_pc_type_abbr)
+    let add_low_pc = add_abbr_entry (0x11,"DW_AT_low_pc",DW_FORM_addr)
 
-    let add_declaration = add_abbr_entry (0x3c,declaration_type_abbr)
+    let add_declaration = add_abbr_entry (0x3c,"DW_AT_declaration",DW_FORM_flag)
 
-    let add_string buf id = function
-      | Simple_string _ -> add_abbr_entry (id,dw_form_string) buf
-      | Offset_string _ -> add_abbr_entry (id,dw_form_strp) buf
+    let add_string buf id c = function
+      | Simple_string _ -> add_abbr_entry (id,c,DW_FORM_string) buf
+      | Offset_string _ -> add_abbr_entry (id,c,DW_FORM_strp) buf
 
-    let add_name buf = add_string buf 0x3
+    let add_name buf = add_string buf 0x3 "DW_AT_name"
 
     let add_name_opt buf = function
       | None -> ()
@@ -80,10 +86,10 @@ module DwarfPrinter(Target: DWARF_TARGET):
     let add_location loc buf =
       match loc with
       | None -> ()
-      | Some (LocRef _) -> add_abbr_entry (0x2,location_ref_type_abbr) buf
+      | Some (LocRef _) -> add_abbr_entry (0x2,"DW_AT_location",DW_FORM_data4) buf
       | Some (LocList _ )
       | Some (LocSymbol _)
-      | Some (LocSimple _) -> add_abbr_entry (0x2,location_block_type_abbr) buf
+      | Some (LocSimple _) -> add_abbr_entry (0x2,"DW_AT_location",DW_FORM_block) buf
 
 
 
@@ -94,125 +100,125 @@ module DwarfPrinter(Target: DWARF_TARGET):
         match v with
         | None -> ()
         | Some _ -> f buf in
-      let prologue id =
+      let prologue id c =
         let has_child = match entity.children with
         | [] -> false
         | _ -> true in
-        add_abbr_uleb id buf;
-        add_byte buf has_child;
-        if has_sibling then add_abbr_entry (0x1,sibling_type_abbr) buf;
+        add_abbr_uleb id c buf;
+        add_byte buf has_child (if has_child then "DW_CHILDREN_yes" else "DW_CHILDREN_no");
+        if has_sibling then add_abbr_entry (0x1,"DW_AT_sibling",DW_FORM_ref4) buf;
       in
       (match entity.tag with
       | DW_TAG_array_type e ->
-          prologue 0x1;
+          prologue 0x1 "DW_TAG_array_type";
           add_type buf
       | DW_TAG_base_type b ->
-          prologue 0x24;
+          prologue 0x24 "DW_TAG_base_type";
           add_byte_size buf;
-          add_attr_some b.base_type_encoding (add_abbr_entry (0x3e,encoding_type_abbr));
+          add_attr_some b.base_type_encoding (add_abbr_entry (0x3e,"DW_AT_encoding",DW_FORM_data1));
           add_name buf b.base_type_name;
       | DW_TAG_compile_unit e ->
-          prologue 0x11;
-          add_string buf 0x1b e.compile_unit_dir;
+          prologue 0x11 "DW_TAG_compile_unit";
+          add_string buf 0x1b "DW_AT_comp_dir" e.compile_unit_dir;
           add_low_pc buf;
           add_high_pc buf;
-          add_abbr_entry (0x13,language_type_abbr) buf;
+          add_abbr_entry (0x13,"DW_AT_language",DW_FORM_udata) buf;
           add_name buf e.compile_unit_name;
-          add_string buf 0x25 e.compile_unit_prod_name;
-          add_abbr_entry (0x10,stmt_list_type_abbr) buf;
+          add_string buf 0x25 "DW_AT_producer" e.compile_unit_prod_name;
+          add_abbr_entry (0x10,"DW_AT_stmt_list",DW_FORM_data4) buf;
       | DW_TAG_const_type _ ->
-          prologue 0x26;
+          prologue 0x26 "DW_TAG_const_type";
           add_type buf
       | DW_TAG_enumeration_type e ->
-          prologue 0x4;
+          prologue 0x4 "DW_TAG_enumeration_type";
           add_attr_some e.enumeration_file_loc add_file_loc;
           add_byte_size buf;
           add_attr_some e.enumeration_declaration add_declaration;
           add_name buf e.enumeration_name
       | DW_TAG_enumerator e ->
-          prologue 0x28;
-          add_abbr_entry (0x1c,value_type_abbr) buf;
+          prologue 0x28 "DW_TAG_enumerator";
+          add_abbr_entry (0x1c,"DW_AT_const_value",DW_FORM_sdata) buf;
           add_name buf e.enumerator_name
       | DW_TAG_formal_parameter e ->
-          prologue 0x5;
-          add_attr_some e.formal_parameter_artificial (add_abbr_entry (0x34,artificial_type_abbr));
+          prologue 0x5 "DW_TAG_formal_parameter";
+          add_attr_some e.formal_parameter_artificial (add_abbr_entry (0x34,"DW_AT_artificial",DW_FORM_flag));
           add_name_opt buf e.formal_parameter_name;
           add_type buf;
-          add_attr_some e.formal_parameter_variable_parameter (add_abbr_entry (0x4b,variable_parameter_type_abbr));
+          add_attr_some e.formal_parameter_variable_parameter (add_abbr_entry (0x4b,"DW_AT_variable_parameter",DW_FORM_flag));
           add_location  e.formal_parameter_location buf
       | DW_TAG_label e ->
-          prologue 0xa;
+          prologue 0xa "DW_TAG_label";
           add_low_pc buf;
           add_name buf e.label_name;
       | DW_TAG_lexical_block a ->
-          prologue 0xb;
+          prologue 0xb "DW_TAG_lexical_block";
           add_attr_some a.lexical_block_high_pc add_high_pc;
           add_attr_some a.lexical_block_low_pc add_low_pc
       | DW_TAG_member e ->
-          prologue 0xd;
+          prologue 0xd "DW_TAG_member";
           add_attr_some e.member_byte_size add_byte_size;
-          add_attr_some e.member_bit_offset (add_abbr_entry (0xc,bit_offset_type_abbr));
-          add_attr_some e.member_bit_size (add_abbr_entry (0xd,bit_size_type_abbr));
+          add_attr_some e.member_bit_offset (add_abbr_entry (0xc,"DW_AT_bit_offset",DW_FORM_data1));
+          add_attr_some e.member_bit_size (add_abbr_entry (0xd,"DW_AT_bit_size",DW_FORM_data1));
           add_attr_some e.member_declaration add_declaration;
           add_name buf e.member_name;
           add_type buf;
           (match e.member_data_member_location with
           | None -> ()
-          | Some (DataLocBlock __) -> add_abbr_entry (0x38,data_location_block_type_abbr) buf
-          | Some (DataLocRef _) -> add_abbr_entry (0x38,data_location_ref_type_abbr) buf)
+          | Some (DataLocBlock __) -> add_abbr_entry (0x38,"DW_AT_data_member_location",DW_FORM_block) buf
+          | Some (DataLocRef _) -> add_abbr_entry (0x38,"DW_AT_data_member_location",DW_FORM_ref4) buf)
       | DW_TAG_pointer_type _ ->
-          prologue 0xf;
+          prologue 0xf "DW_TAG_pointer_type";
           add_type buf
       | DW_TAG_structure_type e ->
-          prologue 0x13;
+          prologue 0x13 "DW_TAG_structure_type";
           add_attr_some e.structure_file_loc add_file_loc;
           add_attr_some e.structure_byte_size add_member_size;
           add_attr_some e.structure_declaration add_declaration;
           add_name_opt buf e.structure_name
       | DW_TAG_subprogram e ->
-          prologue 0x2e;
+          prologue 0x2e "DW_TAG_subprogram";
           add_file_loc buf;
-          add_attr_some e.subprogram_external (add_abbr_entry (0x3f,external_type_abbr));
-          add_attr_some e.subprogram_high_pc add_high_pc;
+          add_attr_some e.subprogram_external (add_abbr_entry (0x3f,"DW_AT_external",DW_FORM_flag));
           add_attr_some e.subprogram_low_pc add_low_pc;
+          add_attr_some e.subprogram_high_pc add_high_pc;
           add_name buf e.subprogram_name;
-          add_abbr_entry (0x27,prototyped_type_abbr) buf;
+          add_abbr_entry (0x27,"DW_AT_prototyped",DW_FORM_flag) buf;
           add_attr_some e.subprogram_type add_type;
       | DW_TAG_subrange_type e ->
-          prologue 0x21;
+          prologue 0x21 "DW_TAG_subrange_type";
           add_attr_some e.subrange_type add_type;
           (match e.subrange_upper_bound with
           | None -> ()
-          | Some (BoundConst _) -> add_abbr_entry (0x2f,bound_const_type_abbr) buf
-          | Some (BoundRef _) -> add_abbr_entry (0x2f,bound_ref_type_abbr) buf)
+          | Some (BoundConst _) -> add_abbr_entry (0x2f,"DW_AT_upper_bound",DW_FORM_udata) buf
+          | Some (BoundRef _) -> add_abbr_entry (0x2f,"DW_AT_upper_bound",DW_FORM_ref4) buf)
       | DW_TAG_subroutine_type e ->
-          prologue 0x15;
+          prologue 0x15 "DW_TAG_subroutine_type";
           add_attr_some e.subroutine_type add_type;
-          add_abbr_entry (0x27,prototyped_type_abbr) buf
+          add_abbr_entry (0x27,"DW_AT_prototyped",DW_FORM_flag) buf
       | DW_TAG_typedef e ->
-          prologue 0x16;
+          prologue 0x16 "DW_TAG_typedef";
           add_attr_some e.typedef_file_loc add_file_loc;
           add_name buf e.typedef_name;
           add_type buf
       | DW_TAG_union_type e ->
-          prologue 0x17;
+          prologue 0x17 "DW_TAG_union_type";
           add_attr_some e.union_file_loc add_file_loc;
           add_attr_some e.union_byte_size add_member_size;
           add_attr_some e.union_declaration add_declaration;
           add_name_opt buf e.union_name
       | DW_TAG_unspecified_parameter e ->
-          prologue 0x18;
-          add_attr_some e.unspecified_parameter_artificial (add_abbr_entry (0x34,artificial_type_abbr))
+          prologue 0x18 "DW_TAG_unspecified_parameter";
+          add_attr_some e.unspecified_parameter_artificial (add_abbr_entry (0x34,"DW_AT_artificial",DW_FORM_flag))
       | DW_TAG_variable e ->
-          prologue 0x34;
+          prologue 0x34 "DW_TAG_variable";
           add_file_loc buf;
           add_attr_some e.variable_declaration add_declaration;
-          add_attr_some e.variable_external (add_abbr_entry (0x3f,external_type_abbr));
-          add_location  e.variable_location buf;
+          add_attr_some e.variable_external (add_abbr_entry (0x3f,"DW_AT_external",DW_FORM_flag));
+          add_location e.variable_location buf;
           add_name buf e.variable_name;
           add_type buf
       | DW_TAG_volatile_type _ ->
-          prologue 0x35;
+          prologue 0x35 "DW_TAG_volatile_type";
           add_type buf);
       Buffer.contents buf
 
@@ -253,11 +259,11 @@ module DwarfPrinter(Target: DWARF_TARGET):
       section oc Section_debug_abbrev;
       print_label oc !abbrev_start_addr;
       List.iter (fun (s,id) ->
-        fprintf oc "	.uleb128	%d\n" id;
+        fprintf oc "	.uleb128	%d%a\n" id print_comment "Abbreviation Code";
         output_string oc s;
-        fprintf oc "	.uleb128	0\n";
-        fprintf oc "	.uleb128	0\n\n")  abbrevs;
-      fprintf oc "	.sleb128	0\n"
+        fprintf oc "	.uleb128	0%a\n" print_comment "EOM(1)";
+        fprintf oc "	.uleb128	0%a\n" print_comment "EOM(2)")  abbrevs;
+      fprintf oc "	.sleb128	0%a\n" print_comment "EOM(3)"
 
     let debug_start_addr = ref (-1)
 
@@ -285,117 +291,117 @@ module DwarfPrinter(Target: DWARF_TARGET):
         Hashtbl.add loc_labels id label;
         label
 
-    let print_loc_ref oc r =
+    let print_loc_ref oc c r =
       let ref = loc_to_label r in
-      fprintf oc "	.4byte		%a\n" label ref
+      fprintf oc "	.4byte		%a%a\n" label ref print_comment c
 
 
     (* Helper functions for debug printing *)
-    let print_opt_value oc o f =
+    let print_opt_value oc c o f =
       match o with
       | None -> ()
-      | Some o -> f oc o
+      | Some o -> f oc c o
 
-    let print_flag oc b =
-      output_string oc (string_of_byte b)
+    let print_flag oc c b =
+      output_string oc (string_of_byte b c)
 
-    let print_string oc = function
+    let print_string oc c = function
       | Simple_string s ->
-          fprintf oc "	.asciz		\"%s\"\n" s
-      | Offset_string o ->  print_loc_ref oc o
+          fprintf oc "	.asciz		\"%s\"%a\n" s print_comment c
+      | Offset_string o ->  print_loc_ref oc c o
 
-    let print_uleb128 oc d =
-      fprintf oc "	.uleb128	%d\n" d
+    let print_uleb128 oc c d =
+      fprintf oc "	.uleb128	%d%a\n" d print_comment c
 
-    let print_sleb128 oc d =
-      fprintf oc "	.sleb128	%d\n" d
+    let print_sleb128 oc c d =
+      fprintf oc "	.sleb128	%d%a\n" d print_comment c
 
-    let print_byte oc b =
-      fprintf oc "	.byte		0x%X\n" b
+    let print_byte oc c b =
+      fprintf oc "	.byte		0x%X%a\n" b print_comment c
 
-    let print_2byte oc b =
-      fprintf oc "	.2byte		0x%X\n" b
+    let print_2byte oc c b =
+      fprintf oc "	.2byte		0x%X%a\n" b print_comment c
 
-    let print_ref oc r =
+    let print_ref oc c r =
       let ref = entry_to_label r in
-      fprintf oc "	.4byte		%a\n" label ref
+      fprintf oc "	.4byte		%a%a\n" label ref print_comment c
 
     let print_file_loc oc = function
       | Some (Diab_file_loc (file,col)) ->
-          fprintf oc "	.4byte		%a\n" label file;
-          print_uleb128 oc col
+          fprintf oc "	.4byte		%a%a\n" label file print_comment "DW_AT_decl_file";
+          print_uleb128 oc "DW_AT_decl_line" col
       | Some (Gnu_file_loc (file,col)) ->
-          fprintf oc "	.4byte		%l\n" file;
-          print_uleb128 oc col
+          fprintf oc "	.4byte		%l%a\n" file print_comment "DW_AT_decl_file";
+          print_uleb128 oc "DW_AT_decl_line"  col
      | None -> ()
 
     let print_loc_expr oc = function
       | DW_OP_bregx (a,b) ->
-          print_byte oc dw_op_bregx;
-          print_uleb128 oc a;
-          fprintf oc "	.sleb128	%ld\n" b
+          print_byte oc "" dw_op_bregx;
+          print_uleb128 oc "" a;
+          fprintf oc "	.sleb128	%ld\n" b;
       | DW_OP_plus_uconst i ->
-          print_byte oc dw_op_plus_uconst;
-          print_uleb128 oc i
+          print_byte oc "" dw_op_plus_uconst;
+          print_uleb128 oc "" i
       | DW_OP_piece i ->
-          print_byte oc dw_op_piece;
-          print_uleb128 oc i
+          print_byte oc "" dw_op_piece;
+          print_uleb128 oc "" i
       | DW_OP_reg i ->
           if i < 32 then
-            print_byte oc (dw_op_reg0 + i)
+            print_byte oc "" (dw_op_reg0 + i)
           else begin
-            print_byte oc dw_op_regx;
-            print_uleb128 oc i
+            print_byte oc "" dw_op_regx;
+            print_uleb128 oc "" i
           end
 
-    let print_loc oc loc =
+    let print_loc oc c loc =
       match loc with
       | LocSymbol s ->
-          print_sleb128 oc 5;
-          print_byte oc dw_op_addr;
+          print_sleb128 oc c 5;
+          print_byte oc "" dw_op_addr;
           fprintf oc "	.4byte		%a\n" symbol s
       | LocSimple e ->
-          print_sleb128 oc (size_of_loc_expr e);
+          print_sleb128 oc c (size_of_loc_expr e);
           print_loc_expr oc e
       | LocList e ->
           let size = List.fold_left (fun acc a -> acc + size_of_loc_expr a) 0 e in
-          print_sleb128 oc size;
+          print_sleb128 oc "" size;
           List.iter (print_loc_expr oc) e
-      | LocRef f ->  print_loc_ref oc f
+      | LocRef f ->  print_loc_ref oc c f
 
     let print_list_loc oc = function
       | LocSymbol s ->
-          print_2byte oc 5;
-          print_byte oc dw_op_addr;
+          print_2byte oc "" 5;
+          print_byte oc "" dw_op_addr;
           fprintf oc "	.4byte		%a\n" symbol s
       | LocSimple e ->
-          print_2byte oc (size_of_loc_expr e);
+          print_2byte oc "" (size_of_loc_expr e);
           print_loc_expr oc e
       | LocList e ->
           let size = List.fold_left (fun acc a -> acc + size_of_loc_expr a) 0 e in
-          print_2byte oc size;
+          print_2byte oc "" size;
           List.iter (print_loc_expr oc) e
-      | LocRef f ->  print_loc_ref oc f
+      | LocRef f ->  print_loc_ref oc ""  f
 
-    let print_data_location oc dl =
+    let print_data_location oc c dl =
       match dl with
       | DataLocBlock e ->
-          print_sleb128 oc (size_of_loc_expr e);
+          print_sleb128 oc c  (size_of_loc_expr e);
           print_loc_expr oc e
       | _ -> ()
 
-    let print_addr oc a =
-      fprintf oc "	.4byte		%a\n" label a
+    let print_addr oc c a =
+      fprintf oc "	.4byte		%a%a\n" label a print_comment c
 
     let print_array_type oc at =
-      print_ref oc at.array_type
+      print_ref oc "DW_AT_type" at.array_type
 
-    let print_bound_value oc = function
-      | BoundConst bc -> print_uleb128 oc bc
-      | BoundRef br -> print_ref oc br
+    let print_bound_value oc c = function
+      | BoundConst bc -> print_uleb128 oc c bc
+      | BoundRef br -> print_ref oc c br
 
     let print_base_type oc bt =
-      print_byte oc bt.base_type_byte_size;
+      print_byte oc "DW_AT_byte_size" bt.base_type_byte_size;
       (match bt.base_type_encoding with
       | Some e ->
           let encoding = match e with
@@ -408,66 +414,66 @@ module DwarfPrinter(Target: DWARF_TARGET):
           | DW_ATE_unsigned -> 0x7
           | DW_ATE_unsigned_char -> 0x8
           in
-          print_byte oc encoding;
+          print_byte oc "DW_AT_encoding" encoding;
       | None -> ());
-      print_string oc bt.base_type_name
+      print_string oc "DW_AT_name" bt.base_type_name
 
     let print_compilation_unit oc tag =
-      print_string oc tag.compile_unit_dir;
-      print_addr oc tag.compile_unit_low_pc;
-      print_addr oc tag.compile_unit_high_pc;
-      print_uleb128 oc 1;
-      print_string oc tag.compile_unit_name;
-      print_string oc tag.compile_unit_prod_name;
-      print_addr oc !debug_stmt_list
+      print_string oc "DW_AT_comp_dir" tag.compile_unit_dir;
+      print_addr oc "DW_AT_low_pc" tag.compile_unit_low_pc;
+      print_addr oc "DW_AT_high_pc" tag.compile_unit_high_pc;
+      print_uleb128 oc "DW_AT_language" 1;
+      print_string oc "DW_AT_name" tag.compile_unit_name;
+      print_string oc "DW_AT_producer" tag.compile_unit_prod_name;
+      print_addr oc "DW_AT_stmt_list" !debug_stmt_list
 
     let print_const_type oc ct =
-      print_ref oc ct.const_type
+      print_ref oc "DW_AT_type" ct.const_type
 
     let print_enumeration_type oc et =
       print_file_loc oc et.enumeration_file_loc;
-      print_uleb128 oc et.enumeration_byte_size;
-      print_opt_value oc et.enumeration_declaration print_flag;
-      print_string oc et.enumeration_name
+      print_uleb128 oc "DW_AT_byte_size" et.enumeration_byte_size;
+      print_opt_value oc "DW_AT_declaration" et.enumeration_declaration print_flag;
+      print_string oc "DW_AT_name" et.enumeration_name
 
     let print_enumerator oc en =
-      print_sleb128 oc en.enumerator_value;
-      print_string oc en.enumerator_name
+      print_sleb128 oc "DW_AT_const_value" en.enumerator_value;
+      print_string oc "DW_AT_name" en.enumerator_name
 
     let print_formal_parameter oc fp =
-      print_opt_value oc fp.formal_parameter_artificial print_flag;
-      print_opt_value oc fp.formal_parameter_name print_string;
-      print_ref oc fp.formal_parameter_type;
-      print_opt_value oc fp.formal_parameter_variable_parameter print_flag;
-      print_opt_value oc fp.formal_parameter_location print_loc
+      print_opt_value oc "DW_AT_artificial" fp.formal_parameter_artificial print_flag;
+      print_opt_value oc "DW_AT_name" fp.formal_parameter_name print_string;
+      print_ref oc "DW_AT_type" fp.formal_parameter_type;
+      print_opt_value oc "DW_AT_variable_parameter" fp.formal_parameter_variable_parameter print_flag;
+      print_opt_value oc "DW_AT_location" fp.formal_parameter_location print_loc
 
     let print_tag_label oc tl =
-      print_ref oc tl.label_low_pc;
-      print_string oc tl.label_name
+      print_ref oc "DW_AT_low_pc" tl.label_low_pc;
+      print_string oc "DW_AT_name" tl.label_name
 
 
     let print_lexical_block oc lb =
-      print_opt_value oc lb.lexical_block_high_pc print_addr;
-      print_opt_value oc lb.lexical_block_low_pc print_addr
+      print_opt_value oc "DW_AT_high_pc" lb.lexical_block_high_pc print_addr;
+      print_opt_value oc "DW_AT_low_pc" lb.lexical_block_low_pc print_addr
 
     let print_member oc mb =
-      print_opt_value oc mb.member_byte_size print_byte;
-      print_opt_value oc mb.member_bit_offset print_byte;
-      print_opt_value oc mb.member_bit_size print_byte;
-      print_opt_value oc mb.member_declaration print_flag;
-      print_string oc mb.member_name;
-      print_ref oc mb.member_type;
-      print_opt_value oc mb.member_data_member_location print_data_location
+      print_opt_value oc "DW_AT_byte_size" mb.member_byte_size print_byte;
+      print_opt_value oc "DW_AT_bit_offset" mb.member_bit_offset print_byte;
+      print_opt_value oc "DW_AT_bit_size" mb.member_bit_size print_byte;
+      print_opt_value oc  "DW_AT_declaration" mb.member_declaration print_flag;
+      print_string oc "DW_AT_name" mb.member_name;
+      print_ref oc "DW_AT_type" mb.member_type;
+      print_opt_value oc "DW_AT_data_member_location" mb.member_data_member_location print_data_location
 
 
     let print_pointer oc pt =
-      print_ref oc pt.pointer_type
+      print_ref oc "DW_AT_type" pt.pointer_type
 
     let print_structure oc st =
       print_file_loc oc st.structure_file_loc;
-      print_opt_value oc st.structure_byte_size print_uleb128;
-      print_opt_value oc st.structure_declaration print_flag;
-      print_opt_value oc st.structure_name print_string
+      print_opt_value oc "DW_AT_byte_size" st.structure_byte_size print_uleb128;
+      print_opt_value oc "DW_AT_declaration" st.structure_declaration print_flag;
+      print_opt_value oc "DW_AT_name" st.structure_name print_string
 
     let print_subprogram_addr oc (s,e) =
       fprintf oc "	.4byte		%a\n" label e;
@@ -475,45 +481,45 @@ module DwarfPrinter(Target: DWARF_TARGET):
 
     let print_subprogram oc sp =
       print_file_loc oc (Some sp.subprogram_file_loc);
-      print_opt_value oc sp.subprogram_external print_flag;
-      print_opt_value oc sp.subprogram_high_pc print_addr;
-      print_opt_value oc sp.subprogram_low_pc print_addr;
-      print_string oc sp.subprogram_name;
-      print_flag oc sp.subprogram_prototyped;
-      print_opt_value oc sp.subprogram_type print_ref
+      print_opt_value oc "DW_AT_external" sp.subprogram_external print_flag;
+      print_opt_value oc "DW_AT_low_pc" sp.subprogram_low_pc print_addr;
+      print_opt_value oc "DW_AT_high_pc" sp.subprogram_high_pc print_addr;
+      print_string oc "DW_AT_name" sp.subprogram_name;
+      print_flag oc "DW_AT_prototyped" sp.subprogram_prototyped;
+      print_opt_value oc "DW_AT_type" sp.subprogram_type print_ref
 
     let print_subrange oc sr =
-      print_opt_value oc sr.subrange_type print_ref;
-      print_opt_value oc sr.subrange_upper_bound print_bound_value
+      print_opt_value oc "DW_AT_type" sr.subrange_type print_ref;
+      print_opt_value oc  "DW_AT_upper_bound" sr.subrange_upper_bound print_bound_value
 
     let print_subroutine oc st =
-      print_opt_value oc st.subroutine_type print_ref;
-      print_flag oc st.subroutine_prototyped
+      print_opt_value oc "DW_AT_type" st.subroutine_type print_ref;
+      print_flag oc "DW_AT_prototyped" st.subroutine_prototyped
 
     let print_typedef oc td =
       print_file_loc oc td.typedef_file_loc;
-      print_string oc td.typedef_name;
-      print_ref oc td.typedef_type
+      print_string oc "DW_AT_name" td.typedef_name;
+      print_ref oc "DW_AT_type" td.typedef_type
 
     let print_union_type oc ut =
       print_file_loc oc ut.union_file_loc;
-      print_opt_value oc ut.union_byte_size print_uleb128;
-      print_opt_value oc ut.union_declaration print_flag;
-      print_opt_value oc ut.union_name print_string
+      print_opt_value oc "DW_AT_byte_size" ut.union_byte_size print_uleb128;
+      print_opt_value oc "DW_AT_declaration" ut.union_declaration print_flag;
+      print_opt_value oc "DW_AT_name" ut.union_name print_string
 
     let print_unspecified_parameter oc up =
-      print_opt_value oc up.unspecified_parameter_artificial print_flag
+      print_opt_value oc "DW_AT_artificial" up.unspecified_parameter_artificial print_flag
 
     let print_variable oc var =
       print_file_loc oc (Some var.variable_file_loc);
-      print_opt_value oc var.variable_declaration print_flag;
-      print_opt_value oc var.variable_external print_flag;
-      print_opt_value oc var.variable_location print_loc;
-      print_string oc var.variable_name;
-      print_ref oc var.variable_type
+      print_opt_value oc "DW_AT_declaration" var.variable_declaration print_flag;
+      print_opt_value oc "DW_AT_external" var.variable_external print_flag;
+      print_opt_value oc "DW_AT_location" var.variable_location print_loc;
+      print_string oc "DW_AT_name" var.variable_name;
+      print_ref oc "DW_AT_type" var.variable_type
 
     let print_volatile_type oc vt =
-      print_ref oc vt.volatile_type
+      print_ref oc "DW_AT_type" vt.volatile_type
 
     (* Print an debug entry *)
     let  print_entry oc entry =
@@ -523,11 +529,11 @@ module DwarfPrinter(Target: DWARF_TARGET):
         | None -> false
         | Some _ -> true in
         let id = get_abbrev entry has_sib in
-        print_sleb128 oc id;
+        print_sleb128 oc (sprintf "Abbrev [%d] %s" id (string_of_dw_tag entry.tag)) id;
         (match sib with
         | None -> ()
         | Some s -> let lbl = entry_to_label s in
-          fprintf oc "	.4byte		%a-%a\n" label lbl label !debug_start_addr);
+          fprintf oc "	.4byte		%a-%a%a\n" label lbl label !debug_start_addr print_comment "DW_AT_sibling");
         begin
           match entry.tag with
           | DW_TAG_array_type arr_type -> print_array_type oc arr_type
@@ -552,7 +558,7 @@ module DwarfPrinter(Target: DWARF_TARGET):
           | DW_TAG_volatile_type vt -> print_volatile_type oc vt
         end) (fun e ->
           if e.children <> [] then
-          print_sleb128 oc 0) entry
+          print_sleb128 oc "End Of Children Mark" 0) entry
 
     (* Print the debug info section *)
     let print_debug_info oc start line_start entry  =
@@ -562,13 +568,13 @@ module DwarfPrinter(Target: DWARF_TARGET):
       print_label oc start;
       let debug_length_start = new_label ()  (* Address used for length calculation *)
       and debug_end = new_label () in
-      fprintf oc "	.4byte		%a-%a\n" label debug_end label debug_length_start;
+      fprintf oc "	.4byte		%a-%a%a\n" label debug_end label debug_length_start print_comment "Length of Unit";
       print_label oc debug_length_start;
-      fprintf oc "	.2byte		0x2\n"; (* Dwarf version *)
-      print_addr oc !abbrev_start_addr; (* Offset into the abbreviation *)
-      print_byte oc !Machine.config.Machine.sizeof_ptr; (* Sizeof pointer type *)
+      fprintf oc "	.2byte		0x2%a\n" print_comment "DWARF version number"; (* Dwarf version *)
+      print_addr oc "Offset Into Abbrev. Section" !abbrev_start_addr; (* Offset into the abbreviation *)
+      print_byte oc "Address Size (in bytes)" !Machine.config.Machine.sizeof_ptr; (* Sizeof pointer type *)
       print_entry oc entry;
-      print_sleb128 oc 0;
+      print_sleb128 oc "" 0;
       print_label oc debug_end (* End of the debug section *)
 
     let print_location_entry oc c_low l =
diff --git a/debug/DwarfTypes.mli b/debug/DwarfTypes.mli
index 7048d8d3..fb1725d9 100644
--- a/debug/DwarfTypes.mli
+++ b/debug/DwarfTypes.mli
@@ -60,12 +60,35 @@ type string_const =
   | Simple_string of string
   | Offset_string of reference
 
-(* Types representing the attribute information per tag value *)
-
 type file_loc =
   | Diab_file_loc of constant * constant
   | Gnu_file_loc of constant * constant
 
+type dw_form =
+  | DW_FORM_addr
+  | DW_FORM_block2
+  | DW_FORM_block4
+  | DW_FORM_data2
+  | DW_FORM_data4
+  | DW_FORM_data8
+  | DW_FORM_string
+  | DW_FORM_block
+  | DW_FORM_block1
+  | DW_FORM_data1
+  | DW_FORM_flag
+  | DW_FORM_sdata
+  | DW_FORM_strp
+  | DW_FORM_udata
+  | DW_FORM_ref_addr
+  | DW_FORM_ref1
+  | DW_FORM_ref2
+  | DW_FORM_ref4
+  | DW_FORM_ref8
+  | DW_FORM_ref_udata
+  | DW_FORM_ref_indirect
+
+(* Types representing the attribute information per tag value *)
+
 type dw_tag_array_type =
     {
      array_type:          reference;
@@ -273,4 +296,5 @@ module type DWARF_TARGET=
     val label: out_channel -> int -> unit
     val section: out_channel -> section_name -> unit
     val symbol: out_channel -> atom -> unit
+    val comment: string
   end
diff --git a/debug/DwarfUtil.ml b/debug/DwarfUtil.ml
index 16e446ee..3e252dd2 100644
--- a/debug/DwarfUtil.ml
+++ b/debug/DwarfUtil.ml
@@ -53,6 +53,30 @@ let rec entry_fold f acc entry =
   let acc = f acc entry.tag in
   List.fold_left (entry_fold f) acc entry.children
 
+(* Return the code and the corresponding comment for a DW_FORM *)
+let code_of_dw_form = function
+  | DW_FORM_addr -> 0x01,"DW_FORM_addr"
+  | DW_FORM_block2 -> 0x03,"DW_FORM_block2"
+  | DW_FORM_block4 -> 0x04,"DW_FORM_block4"
+  | DW_FORM_data2 -> 0x05,"DW_FORM_data2"
+  | DW_FORM_data4 -> 0x06,"DW_FORM_data4"
+  | DW_FORM_data8 -> 0x07,"DW_FORM_data8"
+  | DW_FORM_string -> 0x08,"DW_FORM_string"
+  | DW_FORM_block -> 0x09,"DW_FORM_block"
+  | DW_FORM_block1 -> 0x0a,"DW_FORM_block1"
+  | DW_FORM_data1 -> 0x0b,"DW_FORM_data1"
+  | DW_FORM_flag -> 0x0c,"DW_FORM_flag"
+  | DW_FORM_sdata -> 0x0d,"DW_FORM_sdata"
+  | DW_FORM_strp -> 0x0e,"DW_FORM_strp"
+  | DW_FORM_udata -> 0x0f,"DW_FORM_udata"
+  | DW_FORM_ref_addr -> 0x10,"DW_FORM_ref_addr"
+  | DW_FORM_ref1 -> 0x11,"DW_FORM_ref1"
+  | DW_FORM_ref2 -> 0x12,"DW_FORM_ref2"
+  | DW_FORM_ref4 -> 0x13,"DW_FORM_ref4"
+  | DW_FORM_ref8 -> 0x14,"DW_FORM_ref8"
+  | DW_FORM_ref_udata -> 0x15,"DW_FORM_ref_udata"
+  | DW_FORM_ref_indirect -> 0x16,"DW_FORM_ref_indirect"
+
 (* Attribute form encoding *)
 let dw_form_addr     = 0x01
 let dw_form_block2   = 0x03
@@ -84,35 +108,28 @@ let dw_op_regx = 0x90
 let dw_op_bregx = 0x92
 let dw_op_piece = 0x93
 
-
-(* Default corresponding encoding for the different abbreviations *)
-let sibling_type_abbr = dw_form_ref4
-let file_loc_type_abbr = dw_form_data4,dw_form_udata
-let type_abbr = dw_form_ref_addr
-let name_type_abbr = dw_form_string
-let encoding_type_abbr = dw_form_data1
-let byte_size_type_abbr = dw_form_data1
-let member_size_abbr = dw_form_udata
-let high_pc_type_abbr = dw_form_addr
-let low_pc_type_abbr = dw_form_addr
-let stmt_list_type_abbr = dw_form_data4
-let declaration_type_abbr = dw_form_flag
-let external_type_abbr = dw_form_flag
-let prototyped_type_abbr = dw_form_flag
-let bit_offset_type_abbr = dw_form_data1
-let comp_dir_type_abbr = dw_form_string
-let language_type_abbr = dw_form_udata
-let producer_type_abbr = dw_form_string
-let value_type_abbr = dw_form_sdata
-let artificial_type_abbr = dw_form_flag
-let variable_parameter_type_abbr = dw_form_flag
-let bit_size_type_abbr = dw_form_data1
-let location_ref_type_abbr = dw_form_data4
-let location_block_type_abbr = dw_form_block
-let data_location_block_type_abbr = dw_form_block
-let data_location_ref_type_abbr = dw_form_ref4
-let bound_const_type_abbr = dw_form_udata
-let bound_ref_type_abbr=dw_form_ref4
+(* Tag to string function *)
+let string_of_dw_tag = function
+  | DW_TAG_array_type _ -> "DW_TAG_array_type"
+  | DW_TAG_compile_unit _ -> "DW_TAG_compile_unit"
+  | DW_TAG_base_type _ -> "DW_TAG_base_type"
+  | DW_TAG_const_type _ -> "DW_TAG_const_type"
+  | DW_TAG_enumeration_type _ -> "DW_TAG_enumeration_type"
+  | DW_TAG_enumerator _ -> "DW_TAG_enumerator"
+  | DW_TAG_formal_parameter _ -> "DW_TAG_formal_parameter"
+  | DW_TAG_label _ -> "DW_TAG_label"
+  | DW_TAG_lexical_block _ -> "DW_TAG_lexical_block"
+  | DW_TAG_member _ -> "DW_TAG_member"
+  | DW_TAG_pointer_type _ -> "DW_TAG_pointer_type"
+  | DW_TAG_structure_type _ -> "DW_TAG_structure_type"
+  | DW_TAG_subprogram _ -> "DW_TAG_subprogram"
+  | DW_TAG_subrange_type _ -> "DW_TAG_subrange_type"
+  | DW_TAG_subroutine_type _ -> "DW_TAG_subroutine_type"
+  | DW_TAG_typedef _ -> "DW_TAG_typedef"
+  | DW_TAG_union_type _ -> "DW_TAG_union_type"
+  | DW_TAG_unspecified_parameter _ -> "DW_TAG_unspecified_parameter"
+  | DW_TAG_variable _ -> "DW_TAG_variable"
+  | DW_TAG_volatile_type _ -> "DW_TAG_volatile_type"
 
 (* Sizeof functions for the encoding of uleb128 and sleb128 *)
 let sizeof_uleb128 value =