freepascal.compiler/compiler/dbgdwarf.pas

{
    Copyright (c) 2003-2006 by Peter Vreman and Florian Klaempfl

    This units contains support for DWARF debug info generation

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 ****************************************************************************
}
{
  This units contains support for DWARF debug info generation.

  Currently a lot of code looks like being mergable with dbgstabs. This might
  change however when improved dwarf info is generated, so the stuff shouldn't be
  merged yet. (FK)

  The easiest way to debug dwarf debug info generation is the usage of
  readelf --debug-dump <executable>
  This works only with elf targets though.

  There is a similar utility called dwarfdump which is not elf-specific and
  which has been ported to most systems.
}
unit dbgdwarf;

{$i fpcdefs.inc}

interface

    uses
      cclasses,globtype,
      aasmbase,aasmtai,aasmdata,
      symbase,symtype,symdef,symsym,
      finput,
      DbgBase;

    type
      { Tag names and codes.   }
      tdwarf_tag = (DW_TAG_padding := $00,DW_TAG_array_type := $01,
        DW_TAG_class_type := $02,DW_TAG_entry_point := $03,
        DW_TAG_enumeration_type := $04,DW_TAG_formal_parameter := $05,
        DW_TAG_imported_declaration := $08,DW_TAG_label := $0a,
        DW_TAG_lexical_block := $0b,DW_TAG_member := $0d,
        DW_TAG_pointer_type := $0f,DW_TAG_reference_type := $10,
        DW_TAG_compile_unit := $11,DW_TAG_stringtypee := $12,
        DW_TAG_structure_type := $13,DW_TAG_subroutine_type := $15,
        DW_TAG_typedef := $16,DW_TAG_union_type := $17,
        DW_TAG_unspecified_parameters := $18,
        DW_TAG_variant := $19,DW_TAG_common_block := $1a,
        DW_TAG_common_inclusion := $1b,DW_TAG_inheritance := $1c,
        DW_TAG_inlined_subroutine := $1d,DW_TAG_module := $1e,
        DW_TAG_ptr_to_member_type := $1f,DW_TAG_set_type := $20,
        DW_TAG_subrange_type := $21,DW_TAG_with_stmt := $22,
        DW_TAG_access_declaration := $23,DW_TAG_base_type := $24,
        DW_TAG_catch_block := $25,DW_TAG_const_type := $26,
        DW_TAG_constant := $27,DW_TAG_enumerator := $28,
        DW_TAG_file_type := $29,DW_TAG_friend := $2a,
        DW_TAG_namelist := $2b,DW_TAG_namelist_item := $2c,
        DW_TAG_packed_type := $2d,DW_TAG_subprogram := $2e,
        DW_TAG_template_type_param := $2f,DW_TAG_template_value_param := $30,
        DW_TAG_thrown_type := $31,DW_TAG_try_block := $32,
        DW_TAG_variant_part := $33,DW_TAG_variable := $34,
        DW_TAG_volatile_type := $35,
        { DWARF 3.   }
        DW_TAG_dwarf_procedure := $36,
        DW_TAG_restrict_type := $37,DW_TAG_interface_type := $38,
        DW_TAG_namespace := $39,DW_TAG_imported_module := $3a,
        DW_TAG_unspecified_type := $3b,DW_TAG_partial_unit := $3c,
        DW_TAG_imported_unit := $3d,

        { SGI/MIPS Extensions.   }
        DW_TAG_MIPS_loop := $4081,

        { HP extensions.  See: ftp://ftp.hp.com/pub/lang/tools/WDB/wdb-4.0.tar.gz .   }
        DW_TAG_HP_array_descriptor := $4090,

        { GNU extensions.   }
        { For FORTRAN 77 and Fortran 90.   }
        DW_TAG_format_label := $4101,
        { For C++.   }
        DW_TAG_function_template := $4102,DW_TAG_class_template := $4103,

        DW_TAG_GNU_BINCL := $4104,DW_TAG_GNU_EINCL := $4105,
        { Extensions for UPC.  See: http://upc.gwu.edu/~upc.   }
        DW_TAG_upc_shared_type := $8765,DW_TAG_upc_strict_type := $8766,
        DW_TAG_upc_relaxed_type := $8767,

        { PGI (STMicroelectronics) extensions.  No documentation available.   }
        DW_TAG_PGI_kanji_type := $A000,
        DW_TAG_PGI_interface_block := $A020);

{$notes off}
      { Attribute names and codes.   }
      tdwarf_attribute = (DW_AT_sibling := $01,DW_AT_location := $02,
        DW_AT_name := $03,DW_AT_ordering := $09,
        DW_AT_subscr_data := $0a,DW_AT_byte_size := $0b,
        DW_AT_bit_offset := $0c,DW_AT_bit_size := $0d,
        DW_AT_element_list := $0f,DW_AT_stmt_list := $10,
        DW_AT_low_pc := $11,DW_AT_high_pc := $12,
        DW_AT_language := $13,DW_AT_member := $14,
        DW_AT_discr := $15,DW_AT_discr_value := $16,
        DW_AT_visibility := $17,DW_AT_import := $18,
        DW_AT_string_length := $19,DW_AT_common_reference := $1a,
        DW_AT_comp_dir := $1b,DW_AT_const_value := $1c,
        DW_AT_containing_type := $1d,DW_AT_default_value := $1e,
        DW_AT_inline := $20,DW_AT_is_optional := $21,
        DW_AT_lower_bound := $22,DW_AT_producer := $25,
        DW_AT_prototyped := $27,DW_AT_return_addr := $2a,
        DW_AT_start_scope := $2c,DW_AT_stride_size := $2e,
        DW_AT_upper_bound := $2f,DW_AT_abstract_origin := $31,
        DW_AT_accessibility := $32,DW_AT_address_class := $33,
        DW_AT_artificial := $34,DW_AT_base_types := $35,
        DW_AT_calling_convention := $36,DW_AT_count := $37,
        DW_AT_data_member_location := $38,DW_AT_decl_column := $39,
        DW_AT_decl_file := $3a,DW_AT_decl_line := $3b,
        DW_AT_declaration := $3c,DW_AT_discr_list := $3d,
        DW_AT_encoding := $3e,DW_AT_external := $3f,
        DW_AT_frame_base := $40,DW_AT_friend := $41,
        DW_AT_identifier_case := $42,DW_AT_macro_info := $43,
        DW_AT_namelist_items := $44,DW_AT_priority := $45,
        DW_AT_segment := $46,DW_AT_specification := $47,
        DW_AT_static_link := $48,DW_AT_type := $49,
        DW_AT_use_location := $4a,DW_AT_variable_parameter := $4b,
        DW_AT_virtuality := $4c,DW_AT_vtable_elem_location := $4d,

        { DWARF 3 values.   }
        DW_AT_allocated := $4e,DW_AT_associated := $4f,
        DW_AT_data_location := $50,DW_AT_stride := $51,
        DW_AT_entry_pc := $52,DW_AT_use_UTF8 := $53,
        DW_AT_extension := $54,DW_AT_ranges := $55,
        DW_AT_trampoline := $56,DW_AT_call_column := $57,
        DW_AT_call_file := $58,DW_AT_call_line := $59,

        { SGI/MIPS extensions.   }
        DW_AT_MIPS_fde := $2001,DW_AT_MIPS_loop_begin := $2002,
        DW_AT_MIPS_tail_loop_begin := $2003,DW_AT_MIPS_epilog_begin := $2004,
        DW_AT_MIPS_loop_unroll_factor := $2005,
        DW_AT_MIPS_software_pipeline_depth := $2006,
        DW_AT_MIPS_linkage_name := $2007,DW_AT_MIPS_stride := $2008,
        DW_AT_MIPS_abstract_name := $2009,DW_AT_MIPS_clone_origin := $200a,
        DW_AT_MIPS_has_inlines := $200b,

        { HP extensions.   }
        DW_AT_HP_block_index := $2000,
        DW_AT_HP_unmodifiable := $2001,DW_AT_HP_actuals_stmt_list := $2010,
        DW_AT_HP_proc_per_section := $2011,DW_AT_HP_raw_data_ptr := $2012,
        DW_AT_HP_pass_by_reference := $2013,DW_AT_HP_opt_level := $2014,
        DW_AT_HP_prof_version_id := $2015,DW_AT_HP_opt_flags := $2016,
        DW_AT_HP_cold_region_low_pc := $2017,DW_AT_HP_cold_region_high_pc := $2018,
        DW_AT_HP_all_variables_modifiable := $2019,
        DW_AT_HP_linkage_name := $201a,DW_AT_HP_prof_flags := $201b,

        { GNU extensions.   }
        DW_AT_sf_names := $2101,DW_AT_src_info := $2102,
        DW_AT_mac_info := $2103,DW_AT_src_coords := $2104,
        DW_AT_body_begin := $2105,DW_AT_body_end := $2106,
        DW_AT_GNU_vector := $2107,

        { VMS extensions.  }
        DW_AT_VMS_rtnbeg_pd_address := $2201,

        { UPC extension.   }
        DW_AT_upc_threads_scaled := $3210,

        { PGI (STMicroelectronics) extensions.   }
        DW_AT_PGI_lbase := $3a00,
        DW_AT_PGI_soffset := $3a01,DW_AT_PGI_lstride := $3a02
      );
{$notes on}

      { Form names and codes.   }
      Tdwarf_form = (DW_FORM_addr := $01,DW_FORM_block2 := $03,
        DW_FORM_block4 := $04,DW_FORM_data2 := $05,
        DW_FORM_data4 := $06,DW_FORM_data8 := $07,
        DW_FORM_string := $08,DW_FORM_block := $09,
        DW_FORM_block1 := $0a,DW_FORM_data1 := $0b,
        DW_FORM_flag := $0c,DW_FORM_sdata := $0d,
        DW_FORM_strp := $0e,DW_FORM_udata := $0f,
        DW_FORM_ref_addr := $10,DW_FORM_ref1 := $11,
        DW_FORM_ref2 := $12,DW_FORM_ref4 := $13,
        DW_FORM_ref8 := $14,DW_FORM_ref_udata := $15,
        DW_FORM_indirect := $16);

      TDwarfFile = record
        Index: integer;
        Name: PChar;
      end;

      { TDebugInfoDwarf }

      TDebugInfoDwarf = class(TDebugInfo)
      private
        currabbrevnumber : longint;

        { collect all defs in one list so we can reset them easily }
        defnumberlist,
        deftowritelist   : TFPObjectList;

        { use this defs to create info for variants and file handles }
        { unused (MWE)
        filerecdef,
        textrecdef : tdef;
        }

        dirlist: TFPHashObjectList;
        filesequence: Integer;
        loclist: tdynamicarray;
        asmline: TAsmList;

        function def_dwarf_lab(def:tdef) : tasmsymbol;
        function def_dwarf_ref_lab(def:tdef) : tasmsymbol;
        function def_dwarf_class_struct_lab(def:tobjectdef) : tasmsymbol;
        function get_file_index(afile: tinputfile): Integer;
        function relative_dwarf_path(const s:tcmdstr):tcmdstr;
      protected
        // set if we should use 64bit headers (dwarf3 and up)
        _use_64bit_headers: Boolean;
        // set to ait_const32bit if use_64bit_headers is false, otherwise
        // to ait_const64bit
        offsetreltype,
        offsetabstype : taiconst_type;
        // set if we generated any lineinfo at all. If not, we have to terminate
        // when insertmoduleinfo is called.
        generated_lineinfo: boolean;

        vardatadef: trecorddef;

        procedure set_use_64bit_headers(state: boolean);
        property use_64bit_headers: Boolean read _use_64bit_headers write set_use_64bit_headers;

        procedure set_def_dwarf_labs(def:tdef);

        procedure append_entry(tag : tdwarf_tag;has_children : boolean;data : array of const);
        procedure append_block1(attr: tdwarf_attribute; size: aint);
        procedure append_labelentry(attr : tdwarf_attribute;sym : tasmsymbol);
        procedure append_labelentry_ref(attr : tdwarf_attribute;sym : tasmsymbol);
        procedure append_labelentry_dataptr_abs(attr : tdwarf_attribute;sym : tasmsymbol);
        procedure append_labelentry_dataptr_rel(attr : tdwarf_attribute;sym,endsym : tasmsymbol);
        procedure append_labelentry_dataptr_common(attr : tdwarf_attribute);

        procedure beforeappenddef(list:TAsmList;def:tdef);override;
        procedure afterappenddef(list:TAsmList;def:tdef);override;
        procedure appenddef_ord(list:TAsmList;def:torddef);override;
        procedure appenddef_float(list:TAsmList;def:tfloatdef);override;
        procedure appenddef_enum(list:TAsmList;def:tenumdef);override;
        procedure appenddef_array(list:TAsmList;def:tarraydef);override;
        procedure appenddef_record(list:TAsmList;def:trecorddef);override;
        procedure appenddef_pointer(list:TAsmList;def:tpointerdef);override;
        procedure appenddef_string(list:TAsmList;def:tstringdef);override;
        procedure appenddef_procvar(list:TAsmList;def:tprocvardef);override;
        procedure appendprocdef(list:TAsmList;def:tprocdef);override;

        function  get_symlist_sym_offset(symlist: ppropaccesslistitem; out sym: tabstractvarsym; out offset: pint): boolean;
        procedure appendsym_var(list:TAsmList;sym:tabstractnormalvarsym);
        { used for global/static variables, local variables, parameters and
          absolute variables
        }
        procedure appendsym_var_with_name_type_offset(list:TAsmList; sym:tabstractnormalvarsym; const name: string; def: tdef; offset: pint);
        { used for fields and properties mapped to fields }
        procedure appendsym_fieldvar_with_name_offset(list:TAsmList;sym: tfieldvarsym;const name: string; def: tdef; offset: pint);

        procedure beforeappendsym(list:TAsmList;sym:tsym);override;
        procedure appendsym_staticvar(list:TAsmList;sym:tstaticvarsym);override;
        procedure appendsym_paravar(list:TAsmList;sym:tparavarsym);override;
        procedure appendsym_localvar(list:TAsmList;sym:tlocalvarsym);override;
        procedure appendsym_fieldvar(list:TAsmList;sym:tfieldvarsym);override;
        procedure appendsym_const(list:TAsmList;sym:tconstsym);override;
        procedure appendsym_type(list:TAsmList;sym:ttypesym);override;
        procedure appendsym_label(list:TAsmList;sym:tlabelsym);override;
        procedure appendsym_absolute(list:TAsmList;sym:tabsolutevarsym);override;
        procedure appendsym_property(list:TAsmList;sym:tpropertysym);override;

        function symname(sym:tsym): String; virtual;

        procedure enum_membersyms_callback(p:TObject;arg:pointer);

        procedure finish_children;
        procedure finish_entry;
        procedure finish_lineinfo;
      public
        constructor Create;override;
        destructor Destroy;override;
        procedure insertmoduleinfo;override;
        procedure inserttypeinfo;override;
        procedure referencesections(list:TAsmList);override;
        procedure insertlineinfo(list:TAsmList);override;
        function  dwarf_version: Word; virtual; abstract;
      end;

      { TDebugInfoDwarf2 }

      TDebugInfoDwarf2 = class(TDebugInfoDwarf)
      private
      protected
        procedure appenddef_file(list:TAsmList;def:tfiledef); override;
        procedure appenddef_formal(list:TAsmList;def:tformaldef); override;
        procedure appenddef_object(list:TAsmList;def:tobjectdef); override;
        procedure appenddef_set(list:TAsmList;def:tsetdef); override;
        procedure appenddef_undefined(list:TAsmList;def:tundefineddef); override;
        procedure appenddef_variant(list:TAsmList;def:tvariantdef); override;
      public
        function  dwarf_version: Word; override;
      end;

      { TDebugInfoDwarf3 }

      TDebugInfoDwarf3 = class(TDebugInfoDwarf)
      private
      protected
        procedure appenddef_array(list:TAsmList;def:tarraydef); override;
        procedure appenddef_string(list:TAsmList;def:tstringdef);override;
        procedure appenddef_file(list:TAsmList;def:tfiledef); override;
        procedure appenddef_formal(list:TAsmList;def:tformaldef); override;
        procedure appenddef_object(list:TAsmList;def:tobjectdef); override;
        procedure appenddef_set(list:TAsmList;def: tsetdef); override;
        procedure appenddef_undefined(list:TAsmList;def:tundefineddef); override;
        procedure appenddef_variant(list:TAsmList;def:tvariantdef); override;

        function symname(sym:tsym): String; override;
      public
        function  dwarf_version: Word; override;
      end;

implementation

    uses
      sysutils,cutils,cfileutl,constexp,
      version,globals,verbose,systems,
      cpubase,cgbase,paramgr,
      fmodule,
      defutil,symconst,symtable
      ;

    const
      LINE_BASE   = 1;
      OPCODE_BASE = 13;

    const
      DW_TAG_lo_user = $4080;
      DW_TAG_hi_user = $ffff;

      { Flag that tells whether entry has a child or not.   }
      DW_children_no = 0;
      DW_children_yes = 1;

    const
      { Implementation-defined range start.   }
      DW_AT_lo_user = $2000;
      { Implementation-defined range end.   }
      DW_AT_hi_user = $3ff0;

    type
      { Source language names and codes.   }
      tdwarf_source_language = (DW_LANG_C89 := $0001,DW_LANG_C := $0002,DW_LANG_Ada83 := $0003,
        DW_LANG_C_plus_plus := $0004,DW_LANG_Cobol74 := $0005,
        DW_LANG_Cobol85 := $0006,DW_LANG_Fortran77 := $0007,
        DW_LANG_Fortran90 := $0008,DW_LANG_Pascal83 := $0009,
        DW_LANG_Modula2 := $000a,DW_LANG_Java := $000b,

        { DWARF 3.   }
        DW_LANG_C99 := $000c,DW_LANG_Ada95 := $000d,
        DW_LANG_Fortran95 := $000e,

        { MIPS.   }
        DW_LANG_Mips_Assembler := $8001,

        { UPC.   }
        DW_LANG_Upc := $8765
      );

    const
      { Implementation-defined range start.   }
      DW_LANG_lo_user = $8000;

      { Implementation-defined range start.   }
      DW_LANG_hi_user = $ffff;

    type
      { Names and codes for macro information.   }
      tdwarf_macinfo_record_type = (DW_MACINFO_define := 1,DW_MACINFO_undef := 2,
        DW_MACINFO_start_file := 3,DW_MACINFO_end_file := 4,
        DW_MACINFO_vendor_ext := 255);


    type
      { Type encodings.   }
      Tdwarf_type = (DW_ATE_void := $0,DW_ATE_address := $1,
        DW_ATE_boolean := $2,DW_ATE_complex_float := $3,
        DW_ATE_float := $4,DW_ATE_signed := $5,
        DW_ATE_signed_char := $6,DW_ATE_unsigned := $7,
        DW_ATE_unsigned_char := $8,DW_ATE_imaginary_float := $9,

        { HP extensions.   }
        DW_ATE_HP_float80 := $80,DW_ATE_HP_complex_float80 := $81,
        DW_ATE_HP_float128 := $82,DW_ATE_HP_complex_float128 := $83,
        DW_ATE_HP_floathpintel := $84,DW_ATE_HP_imaginary_float80 := $85,
        DW_ATE_HP_imaginary_float128 := $86
        );


    const
      DW_ATE_lo_user = $80;
      DW_ATE_hi_user = $ff;


    type
      Tdwarf_array_dim_ordering = (DW_ORD_row_major := 0,DW_ORD_col_major := 1
        );

      { Access attribute.   }
      Tdwarf_access_attribute = (DW_ACCESS_public := 1,DW_ACCESS_protected := 2,
        DW_ACCESS_private := 3);

      { Visibility.   }
      Tdwarf_visibility_attribute = (DW_VIS_local := 1,DW_VIS_exported := 2,
        DW_VIS_qualified := 3);

      { Virtuality.   }
      Tdwarf_virtuality_attribute = (DW_VIRTUALITY_none := 0,DW_VIRTUALITY_virtual := 1,
        DW_VIRTUALITY_pure_virtual := 2);

      { Case sensitivity.   }
      Tdwarf_id_case = (DW_ID_case_sensitive := 0,DW_ID_up_case := 1,
        DW_ID_down_case := 2,DW_ID_case_insensitive := 3
        );

      { Calling convention.   }
      Tdwarf_calling_convention = (DW_CC_normal := $1,DW_CC_program := $2,
        DW_CC_nocall := $3,DW_CC_GNU_renesas_sh := $40, DW_CC_GNU_borland_fastcall_i386 := $41
        );
{$notes off}
      { Location atom names and codes.   }
      Tdwarf_location_atom = (DW_OP_addr := $03,DW_OP_deref := $06,DW_OP_const1u := $08,
        DW_OP_const1s := $09,DW_OP_const2u := $0a,
        DW_OP_const2s := $0b,DW_OP_const4u := $0c,
        DW_OP_const4s := $0d,DW_OP_const8u := $0e,
        DW_OP_const8s := $0f,DW_OP_constu := $10,
        DW_OP_consts := $11,DW_OP_dup := $12,DW_OP_drop := $13,
        DW_OP_over := $14,DW_OP_pick := $15,DW_OP_swap := $16,
        DW_OP_rot := $17,DW_OP_xderef := $18,DW_OP_abs := $19,
        DW_OP_and := $1a,DW_OP_div := $1b,DW_OP_minus := $1c,
        DW_OP_mod := $1d,DW_OP_mul := $1e,DW_OP_neg := $1f,
        DW_OP_not := $20,DW_OP_or := $21,DW_OP_plus := $22,
        DW_OP_plus_uconst := $23,DW_OP_shl := $24,
        DW_OP_shr := $25,DW_OP_shra := $26,DW_OP_xor := $27,
        DW_OP_bra := $28,DW_OP_eq := $29,DW_OP_ge := $2a,
        DW_OP_gt := $2b,DW_OP_le := $2c,DW_OP_lt := $2d,
        DW_OP_ne := $2e,DW_OP_skip := $2f,DW_OP_lit0 := $30,
        DW_OP_lit1 := $31,DW_OP_lit2 := $32,DW_OP_lit3 := $33,
        DW_OP_lit4 := $34,DW_OP_lit5 := $35,DW_OP_lit6 := $36,
        DW_OP_lit7 := $37,DW_OP_lit8 := $38,DW_OP_lit9 := $39,
        DW_OP_lit10 := $3a,DW_OP_lit11 := $3b,
        DW_OP_lit12 := $3c,DW_OP_lit13 := $3d,
        DW_OP_lit14 := $3e,DW_OP_lit15 := $3f,
        DW_OP_lit16 := $40,DW_OP_lit17 := $41,
        DW_OP_lit18 := $42,DW_OP_lit19 := $43,
        DW_OP_lit20 := $44,DW_OP_lit21 := $45,
        DW_OP_lit22 := $46,DW_OP_lit23 := $47,
        DW_OP_lit24 := $48,DW_OP_lit25 := $49,
        DW_OP_lit26 := $4a,DW_OP_lit27 := $4b,
        DW_OP_lit28 := $4c,DW_OP_lit29 := $4d,
        DW_OP_lit30 := $4e,DW_OP_lit31 := $4f,
        DW_OP_reg0 := $50,DW_OP_reg1 := $51,DW_OP_reg2 := $52,
        DW_OP_reg3 := $53,DW_OP_reg4 := $54,DW_OP_reg5 := $55,
        DW_OP_reg6 := $56,DW_OP_reg7 := $57,DW_OP_reg8 := $58,
        DW_OP_reg9 := $59,DW_OP_reg10 := $5a,DW_OP_reg11 := $5b,
        DW_OP_reg12 := $5c,DW_OP_reg13 := $5d,
        DW_OP_reg14 := $5e,DW_OP_reg15 := $5f,
        DW_OP_reg16 := $60,DW_OP_reg17 := $61,
        DW_OP_reg18 := $62,DW_OP_reg19 := $63,
        DW_OP_reg20 := $64,DW_OP_reg21 := $65,
        DW_OP_reg22 := $66,DW_OP_reg23 := $67,
        DW_OP_reg24 := $68,DW_OP_reg25 := $69,
        DW_OP_reg26 := $6a,DW_OP_reg27 := $6b,
        DW_OP_reg28 := $6c,DW_OP_reg29 := $6d,
        DW_OP_reg30 := $6e,DW_OP_reg31 := $6f,
        DW_OP_breg0 := $70,DW_OP_breg1 := $71,
        DW_OP_breg2 := $72,DW_OP_breg3 := $73,
        DW_OP_breg4 := $74,DW_OP_breg5 := $75,
        DW_OP_breg6 := $76,DW_OP_breg7 := $77,
        DW_OP_breg8 := $78,DW_OP_breg9 := $79,
        DW_OP_breg10 := $7a,DW_OP_breg11 := $7b,
        DW_OP_breg12 := $7c,DW_OP_breg13 := $7d,
        DW_OP_breg14 := $7e,DW_OP_breg15 := $7f,
        DW_OP_breg16 := $80,DW_OP_breg17 := $81,
        DW_OP_breg18 := $82,DW_OP_breg19 := $83,
        DW_OP_breg20 := $84,DW_OP_breg21 := $85,
        DW_OP_breg22 := $86,DW_OP_breg23 := $87,
        DW_OP_breg24 := $88,DW_OP_breg25 := $89,
        DW_OP_breg26 := $8a,DW_OP_breg27 := $8b,
        DW_OP_breg28 := $8c,DW_OP_breg29 := $8d,
        DW_OP_breg30 := $8e,DW_OP_breg31 := $8f,
        DW_OP_regx := $90,DW_OP_fbreg := $91,DW_OP_bregx := $92,
        DW_OP_piece := $93,DW_OP_deref_size := $94,
        DW_OP_xderef_size := $95,DW_OP_nop := $96,

        { DWARF 3 extensions.   }
        DW_OP_push_object_address := $97,DW_OP_call2 := $98,
        DW_OP_call4 := $99,DW_OP_call_ref := $9a,

        { GNU extensions.   }
        DW_OP_GNU_push_tls_address := $e0,

        { HP extensions.   }
        DW_OP_HP_unknown := $e0,
        DW_OP_HP_is_value := $e1,DW_OP_HP_fltconst4 := $e2,
        DW_OP_HP_fltconst8 := $e3,DW_OP_HP_mod_range := $e4,
        DW_OP_HP_unmod_range := $e5,DW_OP_HP_tls := $e6
        );
{$notes on}

    const
      { Implementation-defined range start.   }
      DW_OP_lo_user = $e0;
      { Implementation-defined range end.   }
      DW_OP_hi_user = $ff;


    const
      DW_LNS_extended_op     = $00;

      { next copied from cfidwarf, need to go to something shared }
      DW_LNS_copy            = $01;
      DW_LNS_advance_pc      = $02;
      DW_LNS_advance_line    = $03;
      DW_LNS_set_file        = $04;
      DW_LNS_set_column      = $05;
      DW_LNS_negate_stmt     = $06;
      DW_LNS_set_basic_block = $07;
      DW_LNS_const_add_pc    = $08;

      DW_LNS_fixed_advance_pc   = $09;
      DW_LNS_set_prologue_end   = $0a;
      DW_LNS_set_epilogue_begin = $0b;
      DW_LNS_set_isa            = $0c;

      DW_LNE_end_sequence = $01;
      DW_LNE_set_address  = $02;
      DW_LNE_define_file  = $03;
      DW_LNE_lo_user      = $80;
      DW_LNE_hi_user      = $ff;

    type
      { TDirIndexItem }

      TDirIndexItem = class(TFPHashObject)
      private
        FFiles: TFPHashObjectList;
      public
        IndexNr : Integer;
        constructor Create(AList:TFPHashObjectList;const AName: String; AIndex: Integer);
        destructor  Destroy;override;
        property Files: TFPHashObjectList read FFiles;
      end;

      { TFileIndexItem }

      TFileIndexItem = class(TFPHashObject)
      private
        FDirIndex: Integer;
      public
        IndexNr : Integer;
        constructor Create(AList:TFPHashObjectList;const AName: String; ADirIndex, AIndex: Integer);
        property DirIndex: Integer read FDirIndex;
      end;


{****************************************************************************
                              procs
****************************************************************************}

    function DirListSortCompare(AItem1, AItem2: Pointer): Integer;
      begin
        Result := TDirIndexItem(AItem1).IndexNr - TDirIndexItem(AItem2).IndexNr;
      end;


    function FileListSortCompare(AItem1, AItem2: Pointer): Integer;
      begin
        Result := TFileIndexItem(AItem1).IndexNr - TFileIndexItem(AItem2).IndexNr;
      end;


{****************************************************************************
                              TDirIndexItem
****************************************************************************}

    constructor TDirIndexItem.Create(AList:TFPHashObjectList;const AName: String; AIndex: Integer);
      begin
        inherited Create(AList,AName);
        FFiles := TFPHashObjectList.Create;
        IndexNr := AIndex;
      end;


    destructor TDirIndexItem.Destroy;
      begin
        FFiles.Free;
        inherited Destroy;
      end;


{****************************************************************************
                              TFileIndexItem
****************************************************************************}

    constructor TFileIndexItem.Create(AList:TFPHashObjectList;const AName: String; ADirIndex, AIndex: Integer);
    begin
      inherited Create(AList,Aname);
      FDirIndex := ADirIndex;
      IndexNr := AIndex;
    end;


{****************************************************************************
                              TDebugInfoDwarf
****************************************************************************}

    function TDebugInfoDwarf.relative_dwarf_path(const s:tcmdstr):tcmdstr;
      begin
        { Make a clean path for gdb. Remove trailing / and ./ prefixes and
	      use always a / }
         result:=BsToSlash(ExcludeTrailingPathDelimiter(ExtractRelativePath(GetCurrentDir,FixFileName(ExpandFileName(s)))));
      end;


    procedure TDebugInfoDwarf.set_use_64bit_headers(state: boolean);
      begin
         _use_64bit_headers:=state;
         if not(state) then
           begin
             if (target_info.system in system_windows+system_wince) then
               offsetabstype:=aitconst_secrel32_symbol
             else
               offsetabstype:=aitconst_32bit;
             if (target_info.system in systems_darwin) then
                offsetreltype:=aitconst_darwin_dwarf_delta32
              else
                offsetreltype:=aitconst_32bit;
           end
         else
           begin
             if (target_info.system in systems_darwin) then
                offsetreltype:=aitconst_darwin_dwarf_delta64
             else
               offsetreltype:=aitconst_64bit;
             offsetabstype:=aitconst_64bit;
           end;
      end;


    procedure TDebugInfoDwarf.set_def_dwarf_labs(def:tdef);
      begin
        { Keep track of used dwarf entries, this info is only usefull for dwarf entries
          referenced by the symbols. Definitions will always include all
          required stabs }
        if def.dbg_state=dbg_state_unused then
          def.dbg_state:=dbg_state_used;
        { Need a new label? }
        if not assigned(def.dwarf_lab) then
          begin
            if not(tf_dwarf_only_local_labels in target_info.flags) then
              begin
                if (ds_dwarf_dbg_info_written in def.defstates) then
                  begin
                    if not assigned(def.typesym) then
                      internalerror(200610011);
                    def.dwarf_lab:=current_asmdata.RefAsmSymbol(make_mangledname('DBG',def.owner,symname(def.typesym)));
                    def.dwarf_ref_lab:=current_asmdata.RefAsmSymbol(make_mangledname('DBGREF',def.owner,symname(def.typesym)));
                    if is_class_or_interface_or_dispinterface(def) then
                      tobjectdef(def).dwarf_struct_lab:=current_asmdata.RefAsmSymbol(make_mangledname('DBG2',def.owner,symname(def.typesym)));
                    def.dbg_state:=dbg_state_written;
                  end
                else
                  begin
                    { Create an exported DBG symbol if we are generating a def defined in the
                      globalsymtable of the current unit }
                    if assigned(def.typesym) and
                       (def.owner.symtabletype=globalsymtable) and
                       (def.owner.iscurrentunit) then
                      begin
                        def.dwarf_lab:=current_asmdata.DefineAsmSymbol(make_mangledname('DBG',def.owner,symname(def.typesym)),AB_GLOBAL,AT_DATA);
                        def.dwarf_ref_lab:=current_asmdata.DefineAsmSymbol(make_mangledname('DBGREF',def.owner,symname(def.typesym)),AB_GLOBAL,AT_DATA);
                        if is_class_or_interface_or_dispinterface(def) then
                          tobjectdef(def).dwarf_struct_lab:=current_asmdata.DefineAsmSymbol(make_mangledname('DBG2',def.owner,symname(def.typesym)),AB_GLOBAL,AT_DATA);
                        include(def.defstates,ds_dwarf_dbg_info_written);
                      end
                    else
                      begin
                        { The pointer typecast is needed to prevent a problem with range checking
                          on when the typecast is changed to 'as' }
                        current_asmdata.getdatalabel(TAsmLabel(pointer(def.dwarf_lab)));
                        current_asmdata.getdatalabel(TAsmLabel(pointer(def.dwarf_ref_lab)));
                        if is_class_or_interface_or_dispinterface(def) then
                          current_asmdata.getdatalabel(TAsmLabel(pointer(tobjectdef(def).dwarf_struct_lab)));
                      end;
                  end;
              end
            else
              begin
                { The pointer typecast is needed to prevent a problem with range checking
                  on when the typecast is changed to 'as' }
                { addrlabel instead of datalabel because it must be a local one }
                current_asmdata.getaddrlabel(TAsmLabel(pointer(def.dwarf_lab)));
                current_asmdata.getaddrlabel(TAsmLabel(pointer(def.dwarf_ref_lab)));
                if is_class_or_interface_or_dispinterface(def) then
                  current_asmdata.getaddrlabel(TAsmLabel(pointer(tobjectdef(def).dwarf_struct_lab)));
              end;
            if def.dbg_state=dbg_state_used then
              deftowritelist.Add(def);
            defnumberlist.Add(def);
          end;
      end;

    function TDebugInfoDwarf.def_dwarf_lab(def: tdef): tasmsymbol;
      begin
        set_def_dwarf_labs(def);
        result:=def.dwarf_lab;
      end;

    function TDebugInfoDwarf.def_dwarf_class_struct_lab(def: tobjectdef): tasmsymbol;
      begin
        set_def_dwarf_labs(def);
        result:=def.dwarf_struct_lab;
      end;

    function TDebugInfoDwarf.def_dwarf_ref_lab(def: tdef): tasmsymbol;
      begin
        set_def_dwarf_labs(def);
        result:=def.dwarf_ref_lab;
      end;

    constructor TDebugInfoDwarf.Create;
      begin
        inherited Create;
        { 64bit headers are only supported for dwarf3 and up, so default off }
        use_64bit_headers := false;
        { we haven't generated any lineinfo yet }
        generated_lineinfo := false;

        dirlist := TFPHashObjectList.Create;
        { add current dir as first item (index=0) }
        TDirIndexItem.Create(dirlist,'.', 0);
        asmline := TAsmList.create;
        loclist := tdynamicarray.Create(4096);
      end;


    destructor TDebugInfoDwarf.Destroy;
      begin
        dirlist.Free;
        dirlist := nil;
        asmline.free;
        asmline:=nil;
        loclist.Free;
        loclist := nil;
        inherited Destroy;
      end;


    procedure TDebugInfoDwarf.enum_membersyms_callback(p:TObject; arg: pointer);
      begin
        case tsym(p).typ of
          fieldvarsym:
            appendsym_fieldvar(TAsmList(arg),tfieldvarsym(p));
          propertysym:
            appendsym_property(TAsmList(arg),tpropertysym(p));
        end;
      end;


    function TDebugInfoDwarf.get_file_index(afile: tinputfile): Integer;
      var
        dirname: String;
        diritem: TDirIndexItem;
        diridx: Integer;
        fileitem: TFileIndexItem;
      begin
        if afile.path^ = '' then
          dirname := '.'
        else
          begin
            { add the canonical form here already to avoid problems with }
            { paths such as './' etc                                     }
            dirname := relative_dwarf_path(afile.path^);
            if dirname = '' then
              dirname := '.';
          end;
        diritem := TDirIndexItem(dirlist.Find(dirname));
        if diritem = nil then
          diritem := TDirIndexItem.Create(dirlist,dirname, dirlist.Count);
        diridx := diritem.IndexNr;

        fileitem := TFileIndexItem(diritem.files.Find(afile.name^));
        if fileitem = nil then
          begin
            Inc(filesequence);
            fileitem := TFileIndexItem.Create(diritem.files,afile.name^, diridx, filesequence);
          end;
        Result := fileitem.IndexNr;
      end;


    { writing the data through a few simply procedures allows to create easily extra information
      for debugging of debug info }
    procedure TDebugInfoDwarf.append_entry(tag : tdwarf_tag;has_children : boolean;data : array of const);
      var
        i : longint;
      begin
        { todo: store defined abbrevs, so you have to define tehm only once (for this unit) (MWE) }
        inc(currabbrevnumber);

        current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_comment.Create(strpnew('Abbrev '+tostr(currabbrevnumber))));

        { abbrev number }
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_uleb128bit(currabbrevnumber));
        current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(currabbrevnumber));
        { tag }
        current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(tag)));

        { children? }
        current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_8bit(ord(has_children)));

        i:=0;
        while i<=high(data) do
          begin
            { attribute }
            if data[i].VType=vtInteger then
              begin
                current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(data[i].VInteger));
              end
            else
              internalerror(200601261);
            inc(i);

            { form }
            if data[i].VType=vtInteger then
              begin
                current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(data[i].VInteger));
              end
            else
              internalerror(200601262);
            inc(i);

            { info itself }
            case tdwarf_form(data[i-1].VInteger) of
              DW_FORM_string:
                case data[i].VType of
                  vtChar:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_string.create(data[i].VChar));
                  vtString:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_string.create(data[i].VString^));
                  vtAnsistring:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_string.create(Ansistring(data[i].VAnsiString)));
                  else
                    internalerror(200601264);
                end;


              DW_FORM_flag:
                current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(byte(data[i].VBoolean)));

              DW_FORM_data1:
                 case data[i].VType of
                  vtInteger:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(data[i].VInteger));
                  vtInt64:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(data[i].VInt64^));
                  vtQWord:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(data[i].VQWord^));
                  else
                    internalerror(200602143);
                end;

              DW_FORM_data2:
                 case data[i].VType of
                  vtInteger:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_16bit(data[i].VInteger));
                  vtInt64:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_16bit(data[i].VInt64^));
                  vtQWord:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_16bit(data[i].VQWord^));
                  else
                    internalerror(200602144);
                end;

              DW_FORM_data4:
                 case data[i].VType of
                  vtInteger:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_32bit(data[i].VInteger));
                  vtInt64:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_32bit(data[i].VInt64^));
                  vtQWord:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_32bit(data[i].VQWord^));
                  else
                    internalerror(200602145);
                end;

              DW_FORM_data8:
                 case data[i].VType of
                  vtInteger:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_64bit(data[i].VInteger));
                  vtInt64:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_64bit(data[i].VInt64^));
                  vtQWord:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_64bit(data[i].VQWord^));
                  else
                    internalerror(200602146);
                end;

              DW_FORM_sdata:
                case data[i].VType of
                  vtInteger:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_sleb128bit(data[i].VInteger));
                  vtInt64:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_sleb128bit(data[i].VInt64^));
                  vtQWord:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_sleb128bit(data[i].VQWord^));
                  else
                    internalerror(200601285);
                end;

              DW_FORM_udata:
                case data[i].VType of
                  vtInteger:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_uleb128bit(data[i].VInteger));
                  vtInt64:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_uleb128bit(data[i].VInt64^));
                  vtQWord:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_uleb128bit(data[i].VQWord^));
                  else
                    internalerror(200601284);
                end;

              { block gets only the size, the rest is appended manually by the caller }
              DW_FORM_block1:
                 case data[i].VType of
                  vtInteger:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(data[i].VInteger));
                  vtInt64:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(data[i].VInt64^));
                  vtQWord:
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(data[i].VQWord^));
                  else
                    internalerror(200602141);
                end;
              else
                internalerror(200601263);
            end;
            inc(i);
          end;
      end;


    procedure TDebugInfoDwarf.append_block1(attr: tdwarf_attribute; size: aint);
      begin
        current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(attr)));
        current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(DW_FORM_block1)));
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(size));
      end;


    procedure TDebugInfoDwarf.append_labelentry(attr : tdwarf_attribute;sym : tasmsymbol);
      begin
        current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(attr)));
        current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(DW_FORM_addr)));
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_sym(sym));
      end;


    procedure TDebugInfoDwarf.append_labelentry_ref(attr : tdwarf_attribute;sym : tasmsymbol);
      begin
        current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(attr)));
        if not(tf_dwarf_only_local_labels in target_info.flags) then
          begin
            current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(DW_FORM_ref_addr)));
            current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_sym(sym))
          end
        else
          begin
            current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(DW_FORM_ref4)));
            current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_rel_sym(offsetreltype,current_asmdata.RefAsmSymbol(target_asm.labelprefix+'debug_info0'),sym));
          end;
      end;


    procedure TDebugInfoDwarf.append_labelentry_dataptr_common(attr : tdwarf_attribute);
      begin
        current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(attr)));
        if use_64bit_headers then
          current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(DW_FORM_data8)))
        else
          current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(DW_FORM_data4)));
      end;


    procedure TDebugInfoDwarf.append_labelentry_dataptr_abs(attr : tdwarf_attribute;sym : tasmsymbol);
      begin
        {
          used for writing dwarf lineptr, loclistptr, macptr and rangelistptr classes as FORM_dataN
          The size of these depend on the header format
          Must be relative to another symbol on tf_dwarf_relative_addresses
          targets
        }
        if (tf_dwarf_relative_addresses in target_info.flags) then
          { use append_labelentry_dataptr_rel instead }
          internalerror(2007020210);
        append_labelentry_dataptr_common(attr);
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_type_sym(offsetabstype,sym))
      end;


    procedure TDebugInfoDwarf.append_labelentry_dataptr_rel(attr : tdwarf_attribute;sym,endsym : tasmsymbol);
      begin
        {
          used for writing dwarf lineptr, loclistptr, macptr and rangelistptr classes as FORM_dataN
          The size of these depend on the header format
          Must be relative to another symbol on tf_dwarf_relative_addresses
          targets
        }
        append_labelentry_dataptr_common(attr);
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_rel_sym(offsetreltype,sym,endsym));
      end;


    procedure TDebugInfoDwarf.finish_entry;
      begin
        current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_8bit(0));
        current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_8bit(0));
      end;


    procedure TDebugInfoDwarf.finish_children;
      begin
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(0));
      end;

    procedure TDebugInfoDwarf.appenddef_ord(list:TAsmList;def:torddef);
      var
        basedef      : tdef;
        sign         : tdwarf_type;
        signform     : tdwarf_form;
        fullbytesize : byte;
      begin
        case def.ordtype of
          s8bit,
          s16bit,
          s32bit,
          u8bit,
          u16bit,
          u32bit :
            begin
              { generate proper signed/unsigned info for types like 0..3 }
              { these are s8bit, but should be identified as unsigned    }
              { because otherwise they are interpreted wrongly when used }
              { in a bitpacked record                                    }
              if (def.low<0) then
                begin
                  sign:=DW_ATE_signed;
                  signform:=DW_FORM_sdata
                end
              else
                begin
                  sign:=DW_ATE_unsigned;
                  signform:=DW_FORM_udata
                end;
              fullbytesize:=def.size;
              case fullbytesize of
                1:
                  if (sign=DW_ATE_signed) then
                    basedef:=s8inttype
                  else
                    basedef:=u8inttype;
                2:
                  if (sign=DW_ATE_signed) then
                    basedef:=s16inttype
                  else
                    basedef:=u16inttype;
                4:
                  if (sign=DW_ATE_signed) then
                    basedef:=s32inttype
                  else
                    basedef:=u32inttype;
                else
                  internalerror(2008032201);
              end;

              if (def.low=torddef(basedef).low) and
                 (def.high=torddef(basedef).high) then
                { base type such as byte/shortint/word/... }
                if assigned(def.typesym) then
                  append_entry(DW_TAG_base_type,false,[
                    DW_AT_name,DW_FORM_string,symname(def.typesym)+#0,
                    DW_AT_encoding,DW_FORM_data1,sign,
                    DW_AT_byte_size,DW_FORM_data1,fullbytesize])
                else
                  append_entry(DW_TAG_base_type,false,[
                    DW_AT_encoding,DW_FORM_data1,sign,
                    DW_AT_byte_size,DW_FORM_data1,fullbytesize])
              else
                begin
                  { subrange type }
                  { note: don't do this 64 bit int types, they appear    }
                  {       to be always clipped to s32bit for some reason }
                  if assigned(def.typesym) then
                    append_entry(DW_TAG_subrange_type,false,[
                      DW_AT_name,DW_FORM_string,symname(def.typesym)+#0,
                      DW_AT_lower_bound,signform,int64(def.low),
                      DW_AT_upper_bound,signform,int64(def.high)
                      ])
                  else
                    append_entry(DW_TAG_subrange_type,false,[
                      DW_AT_lower_bound,signform,int64(def.low),
                      DW_AT_upper_bound,signform,int64(def.high)
                      ]);
                  append_labelentry_ref(DW_AT_type,def_dwarf_lab(basedef));
                end;
                
              finish_entry;
            end;
          uvoid :
            begin
              { gdb 6.4 doesn't support DW_TAG_unspecified_type so we
                replace it with a unsigned type with size 0 (FK)
              }
              append_entry(DW_TAG_base_type,false,[
                DW_AT_name,DW_FORM_string,'Void'#0,
                DW_AT_encoding,DW_FORM_data1,DW_ATE_unsigned,
                DW_AT_byte_size,DW_FORM_data1,0
              ]);
              finish_entry;
            end;
          uchar :
            begin
              append_entry(DW_TAG_base_type,false,[
                DW_AT_name,DW_FORM_string,'Char'#0,
                DW_AT_encoding,DW_FORM_data1,DW_ATE_unsigned_char,
                DW_AT_byte_size,DW_FORM_data1,1
                ]);
              finish_entry;
            end;
          uwidechar :
            begin
              append_entry(DW_TAG_base_type,false,[
                DW_AT_name,DW_FORM_string,'WideChar'#0,
                DW_AT_encoding,DW_FORM_data1,DW_ATE_unsigned_char,
                DW_AT_byte_size,DW_FORM_data1,2
                ]);
              finish_entry;
            end;
          pasbool,
          bool8bit :
            begin
              append_entry(DW_TAG_base_type,false,[
                DW_AT_name,DW_FORM_string,'Boolean'#0,
                DW_AT_encoding,DW_FORM_data1,DW_ATE_boolean,
                DW_AT_byte_size,DW_FORM_data1,1
                ]);
              finish_entry;
            end;
          bool16bit :
            begin
              append_entry(DW_TAG_base_type,false,[
                DW_AT_name,DW_FORM_string,'WordBool'#0,
                DW_AT_encoding,DW_FORM_data1,DW_ATE_boolean,
                DW_AT_byte_size,DW_FORM_data1,2
                ]);
              finish_entry;
            end;
          bool32bit :
            begin
              append_entry(DW_TAG_base_type,false,[
                DW_AT_name,DW_FORM_string,'LongBool'#0,
                DW_AT_encoding,DW_FORM_data1,DW_ATE_boolean,
                DW_AT_byte_size,DW_FORM_data1,4
                ]);
              finish_entry;
            end;
          bool64bit :
            begin
              append_entry(DW_TAG_base_type,false,[
                DW_AT_name,DW_FORM_string,'QWordBool'#0,
                DW_AT_encoding,DW_FORM_data1,DW_ATE_boolean,
                DW_AT_byte_size,DW_FORM_data1,8
                ]);
              finish_entry;
            end;
          u64bit :
            begin
              append_entry(DW_TAG_base_type,false,[
                DW_AT_name,DW_FORM_string,'QWord'#0,
                DW_AT_encoding,DW_FORM_data1,DW_ATE_unsigned,
                DW_AT_byte_size,DW_FORM_data1,8
                ]);
              finish_entry;
            end;
          scurrency :
            begin
              { we should use DW_ATE_signed_fixed, however it isn't supported yet by GDB (FK) }
              append_entry(DW_TAG_base_type,false,[
                DW_AT_name,DW_FORM_string,'Currency'#0,
                DW_AT_encoding,DW_FORM_data1,DW_ATE_signed,
                DW_AT_byte_size,DW_FORM_data1,8
                ]);
              finish_entry;
            end;
          s64bit :
            begin
              append_entry(DW_TAG_base_type,false,[
                DW_AT_name,DW_FORM_string,'Int64'#0,
                DW_AT_encoding,DW_FORM_data1,DW_ATE_signed,
                DW_AT_byte_size,DW_FORM_data1,8
                ]);
              finish_entry;
            end;
          else
            internalerror(200601287);
        end;
      end;

    procedure TDebugInfoDwarf.appenddef_float(list:TAsmList;def:tfloatdef);
      begin
        case def.floattype of
          s32real,
          s64real,
          s80real:
            if assigned(def.typesym) then
              append_entry(DW_TAG_base_type,false,[
                DW_AT_name,DW_FORM_string,symname(def.typesym)+#0,
                DW_AT_encoding,DW_FORM_data1,DW_ATE_float,
                DW_AT_byte_size,DW_FORM_data1,def.size
                ])
            else
              append_entry(DW_TAG_base_type,false,[
                DW_AT_encoding,DW_FORM_data1,DW_ATE_float,
                DW_AT_byte_size,DW_FORM_data1,def.size
                ]);
          s64currency:
            { we should use DW_ATE_signed_fixed, however it isn't supported yet by GDB (FK) }
            if assigned(def.typesym) then
              append_entry(DW_TAG_base_type,false,[
                DW_AT_name,DW_FORM_string,symname(def.typesym)+#0,
                DW_AT_encoding,DW_FORM_data1,DW_ATE_signed,
                DW_AT_byte_size,DW_FORM_data1,8
                ])
            else
              append_entry(DW_TAG_base_type,false,[
                DW_AT_encoding,DW_FORM_data1,DW_ATE_signed,
                DW_AT_byte_size,DW_FORM_data1,8
                ]);
          s64comp:
            if assigned(def.typesym) then
              append_entry(DW_TAG_base_type,false,[
                DW_AT_name,DW_FORM_string,symname(def.typesym)+#0,
                DW_AT_encoding,DW_FORM_data1,DW_ATE_signed,
                DW_AT_byte_size,DW_FORM_data1,8
                ])
            else
              append_entry(DW_TAG_base_type,false,[
                DW_AT_encoding,DW_FORM_data1,DW_ATE_signed,
                DW_AT_byte_size,DW_FORM_data1,8
                ]);
          else
            internalerror(200601289);
        end;
        finish_entry;
      end;


    procedure TDebugInfoDwarf.appenddef_enum(list:TAsmList;def:tenumdef);
      var
        hp : tenumsym;
      begin
        if assigned(def.typesym) then
          append_entry(DW_TAG_enumeration_type,true,[
            DW_AT_name,DW_FORM_string,symname(def.typesym)+#0,
            DW_AT_byte_size,DW_FORM_data1,def.size
            ])
        else
          append_entry(DW_TAG_enumeration_type,true,[
            DW_AT_byte_size,DW_FORM_data1,def.size
            ]);
        if assigned(def.basedef) then
          append_labelentry_ref(DW_AT_type,def_dwarf_lab(def.basedef));
        finish_entry;

        { write enum symbols }
        hp:=tenumsym(def.firstenum);
        while assigned(hp) do
          begin
            append_entry(DW_TAG_enumerator,false,[
              DW_AT_name,DW_FORM_string,symname(hp)+#0,
              DW_AT_const_value,DW_FORM_data4,hp.value
            ]);
            finish_entry;
            hp:=tenumsym(hp).nextenum;
          end;

        finish_children;
      end;


    procedure TDebugInfoDwarf.appenddef_array(list:TAsmList;def:tarraydef);
      var
        size : aint;
        elesize : aint;
        labsym: tasmlabel;
      begin
        if is_dynamic_array(def) then
          begin
            { It's a pointer to the actual array }
            current_asmdata.getaddrlabel(labsym);
            append_entry(DW_TAG_pointer_type,false,[]);
            append_labelentry_ref(DW_AT_type,labsym);
            finish_entry;
            current_asmdata.asmlists[al_dwarf_info].concat(tai_symbol.create(labsym,0));
          end;

        if not is_packed_array(def) then
          elesize := def.elesize*8
        else
          elesize := def.elepackedbitsize;

        if is_special_array(def) then
          begin
            { no known size, no known upper bound }
            if assigned(def.typesym) then
              append_entry(DW_TAG_array_type,true,[
                DW_AT_name,DW_FORM_string,symname(def.typesym)+#0,
                DW_AT_stride_size,DW_FORM_udata,elesize
                ])
            else
              append_entry(DW_TAG_array_type,true,[
                DW_AT_stride_size,DW_FORM_udata,elesize
                ]);
            append_labelentry_ref(DW_AT_type,def_dwarf_lab(def.elementdef));
            finish_entry;
            { a missing upper bound means "unknown"/default }
            append_entry(DW_TAG_subrange_type,false,[
              DW_AT_lower_bound,DW_FORM_sdata,def.lowrange
              ]);
          end
        else
          begin
            size:=def.size;
            if assigned(def.typesym) then
              append_entry(DW_TAG_array_type,true,[
                DW_AT_name,DW_FORM_string,symname(def.typesym)+#0,
                DW_AT_byte_size,DW_FORM_udata,size,
                DW_AT_stride_size,DW_FORM_udata,elesize
                ])
            else
              append_entry(DW_TAG_array_type,true,[
                DW_AT_byte_size,DW_FORM_udata,size,
                DW_AT_stride_size,DW_FORM_udata,elesize
                ]);
            append_labelentry_ref(DW_AT_type,def_dwarf_lab(def.elementdef));
            finish_entry;
            { to simplify things, we don't write a multidimensional array here }
            append_entry(DW_TAG_subrange_type,false,[
              DW_AT_lower_bound,DW_FORM_sdata,def.lowrange,
              DW_AT_upper_bound,DW_FORM_sdata,def.highrange
              ]);
          end;
        append_labelentry_ref(DW_AT_type,def_dwarf_lab(def.rangedef));
        finish_entry;
        finish_children;
      end;


    procedure TDebugInfoDwarf.appenddef_record(list:TAsmList;def:trecorddef);
      begin
        if assigned(def.typesym) then
          append_entry(DW_TAG_structure_type,true,[
            DW_AT_name,DW_FORM_string,symname(def.typesym)+#0,
            DW_AT_byte_size,DW_FORM_udata,def.size
            ])
        else
          append_entry(DW_TAG_structure_type,true,[
            DW_AT_byte_size,DW_FORM_udata,def.size
            ]);
        finish_entry;
        def.symtable.symList.ForEachCall(@enum_membersyms_callback,nil);
        finish_children;
      end;


    procedure TDebugInfoDwarf.appenddef_pointer(list:TAsmList;def:tpointerdef);
      begin
        append_entry(DW_TAG_pointer_type,false,[]);
        if not(is_voidpointer(def)) then
          append_labelentry_ref(DW_AT_type,def_dwarf_lab(def.pointeddef));
        finish_entry;
      end;


    procedure TDebugInfoDwarf.appenddef_string(list:TAsmList;def:tstringdef);

      procedure addnormalstringdef(const name: shortstring; lendef: tdef; maxlen: aword);
        var
          { maxlen can be > high(int64) }
          slen : aword;
          arr : tasmlabel;
        begin
          { fix length of openshortstring }
          slen:=aword(def.len);
          if slen=0 then
            slen:=maxlen;

          { create a structure with two elements }
          if not(tf_dwarf_only_local_labels in target_info.flags) then
            current_asmdata.getdatalabel(arr)
          else
            current_asmdata.getaddrlabel(arr);
          append_entry(DW_TAG_structure_type,true,[
            DW_AT_name,DW_FORM_string,name+#0,
            DW_AT_byte_size,DW_FORM_data1,2*sizeof(pint)
            ]);
          finish_entry;

          { length entry }
          append_entry(DW_TAG_member,false,[
            DW_AT_name,DW_FORM_string,'length'#0,
            DW_AT_data_member_location,DW_FORM_block1,1+lengthuleb128(0)
            ]);
          current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_plus_uconst)));
          current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_uleb128bit(0));
          append_labelentry_ref(DW_AT_type,def_dwarf_lab(lendef));
          finish_entry;

          { string data entry }
          append_entry(DW_TAG_member,false,[
            DW_AT_name,DW_FORM_string,'st'#0,
            DW_AT_data_member_location,DW_FORM_block1,1+lengthuleb128(1)
            ]);
          current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_plus_uconst)));
          current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_uleb128bit(lendef.size));
          append_labelentry_ref(DW_AT_type,arr);
          finish_entry;

          finish_children;

          { now the data array }
          current_asmdata.asmlists[al_dwarf_info].concat(tai_symbol.create(arr,0));
          append_entry(DW_TAG_array_type,true,[
            DW_AT_byte_size,DW_FORM_udata,def.size,
            DW_AT_stride_size,DW_FORM_udata,1*8
            ]);
          append_labelentry_ref(DW_AT_type,def_dwarf_lab(cchartype));
          finish_entry;
          append_entry(DW_TAG_subrange_type,false,[
            DW_AT_lower_bound,DW_FORM_udata,0,
            DW_AT_upper_bound,DW_FORM_udata,qword(slen)
            ]);
          append_labelentry_ref(DW_AT_type,def_dwarf_lab(lendef));
          finish_entry;
          finish_children;
        end;

      begin
        case def.stringtype of
          st_shortstring:
            begin
              addnormalstringdef('ShortString',u8inttype,255);
            end;
          st_longstring:
            begin
{$ifdef cpu64bitaddr}
              addnormalstringdef('LongString',u64inttype,qword(-1));
{$else cpu64bitaddr}
              addnormalstringdef('LongString',u32inttype,cardinal(-1));
{$endif cpu64bitaddr}
           end;
         st_ansistring:
           begin
             { looks like a pchar }
             append_entry(DW_TAG_pointer_type,false,[]);
             append_labelentry_ref(DW_AT_type,def_dwarf_lab(cchartype));
             finish_entry;
           end;
         st_unicodestring,
         st_widestring:
           begin
             { looks like a pwidechar }
             append_entry(DW_TAG_pointer_type,false,[]);
             append_labelentry_ref(DW_AT_type,def_dwarf_lab(cwidechartype));
             finish_entry;
           end;
        end;
      end;

    procedure TDebugInfoDwarf.appenddef_procvar(list:TAsmList;def:tprocvardef);

      procedure doappend;
        var
          i : longint;
        begin
          if assigned(def.typesym) then
            append_entry(DW_TAG_subroutine_type,true,[
              DW_AT_name,DW_FORM_string,symname(def.typesym)+#0,
              DW_AT_prototyped,DW_FORM_flag,true
            ])
          else
            append_entry(DW_TAG_subroutine_type,true,[
              DW_AT_prototyped,DW_FORM_flag,true
            ]);
          if not(is_void(tprocvardef(def).returndef)) then
            append_labelentry_ref(DW_AT_type,def_dwarf_lab(tprocvardef(def).returndef));
          finish_entry;

          { write parameters }
          for i:=0 to def.paras.count-1 do
            begin
              append_entry(DW_TAG_formal_parameter,false,[
                DW_AT_name,DW_FORM_string,symname(tsym(def.paras[i]))+#0
              ]);
              append_labelentry_ref(DW_AT_type,def_dwarf_lab(tparavarsym(def.paras[i]).vardef));
              finish_entry;
            end;

          finish_children;
        end;

      var
        proc : tasmlabel;

      begin
        if def.is_methodpointer then
          begin
            { create a structure with two elements }
            if not(tf_dwarf_only_local_labels in target_info.flags) then
              current_asmdata.getdatalabel(proc)
            else
              current_asmdata.getaddrlabel(proc);
            append_entry(DW_TAG_structure_type,true,[
              DW_AT_byte_size,DW_FORM_data1,2*sizeof(pint)
            ]);
            finish_entry;

            { proc entry }
            append_entry(DW_TAG_member,false,[
              DW_AT_name,DW_FORM_string,'Proc'#0,
              DW_AT_data_member_location,DW_FORM_block1,1+lengthuleb128(0)
              ]);
            current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_plus_uconst)));
            current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_uleb128bit(0));
            append_labelentry_ref(DW_AT_type,proc);
            finish_entry;

            { self entry }
            append_entry(DW_TAG_member,false,[
              DW_AT_name,DW_FORM_string,'Self'#0,
              DW_AT_data_member_location,DW_FORM_block1,1+lengthuleb128(sizeof(pint))
              ]);
            current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_plus_uconst)));
            current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_uleb128bit(sizeof(pint)));
            append_labelentry_ref(DW_AT_type,def_dwarf_lab(class_tobject));
            finish_entry;

            finish_children;

            current_asmdata.asmlists[al_dwarf_info].concat(tai_symbol.create(proc,0));
            doappend;
          end
        else
          doappend;
      end;


    procedure TDebugInfoDwarf.beforeappenddef(list:TAsmList;def:tdef);
      var
        labsym : tasmsymbol;
      begin
        current_asmdata.asmlists[al_dwarf_info].concat(tai_comment.Create(strpnew('Definition '+def.typename)));

        labsym:=def_dwarf_lab(def);
        if ds_dwarf_dbg_info_written in def.defstates then
          current_asmdata.asmlists[al_dwarf_info].concat(tai_symbol.create_global(labsym,0))
        else
          current_asmdata.asmlists[al_dwarf_info].concat(tai_symbol.create(labsym,0));

        if (target_info.system in systems_darwin) then
          begin
            { On Darwin, dwarf info is not linked in the final binary,
              but kept in the individual object files. This allows for
              faster linking, but means that you have to keep the object
              files for debugging and also that gdb only loads in the
              debug info of a particular object file once you step into
              or over a procedure in it.

              To solve this, there is a tool called dsymutil which can
              extract all the dwarf info from a program's object files.
              This utility however performs "smart linking" on the dwarf
              info and throws away all unreferenced dwarf entries. Since
              variables' types always point to the dwarfino for a tdef
              and never to that for a typesym, this means all debug
              entries generated for typesyms are thrown away.

              The problem with that is that we translate typesyms into
              DW_TAG_typedef, and gdb's dwarf-2 reader only makes types
              globally visibly if they are defined using a DW_TAG_typedef.
              So as a result, before running dsymutil types only become
              available once you stepped into/over a function in the object
              file where they are declared, and after running dsymutil they
              are all gone (printng variables still works because the
              tdef dwarf info is still available, but you cannot typecast
              anything outside the declaring units because the type names
              are not known there).

              The solution: if a tdef has an associated typesym, let the
              debug label for the tdef point to a DW_TAG_typedef instead
              of directly to the tdef itself. And don't write anything
              special for the typesym itself.
            }
          if assigned(def.typesym) and
             not(df_generic in def.defoptions) then
            begin
              current_asmdata.getaddrlabel(TAsmLabel(pointer(labsym)));
              append_entry(DW_TAG_typedef,false,[
                DW_AT_name,DW_FORM_string,symname(def.typesym)+#0
              ]);
              append_labelentry_ref(DW_AT_type,labsym);
              finish_entry;
              current_asmdata.asmlists[al_dwarf_info].concat(tai_symbol.create(labsym,0));
            end;
          end;
      end;


    procedure TDebugInfoDwarf.afterappenddef(list:TAsmList;def:tdef);
      var
        labsym : tasmsymbol;
      begin
        { create a derived reference type for pass-by-reference parameters }
        { (gdb doesn't support DW_AT_variable_parameter yet)               }
        labsym:=def_dwarf_ref_lab(def);
        if ds_dwarf_dbg_info_written in def.defstates then
          current_asmdata.asmlists[al_dwarf_info].concat(tai_symbol.create_global(labsym,0))
        else
          current_asmdata.asmlists[al_dwarf_info].concat(tai_symbol.create(labsym,0));
        append_entry(DW_TAG_reference_type,false,[]);
        append_labelentry_ref(DW_AT_type,def_dwarf_lab(def));
        finish_entry;
      end;


    procedure TDebugInfoDwarf.appendprocdef(list:TAsmList;def:tprocdef);

      function dwarf_calling_convention(def: tprocdef): Tdwarf_calling_convention;
        begin
          case def.proccalloption of
            pocall_register:
              result:=DW_CC_GNU_borland_fastcall_i386;
            pocall_cdecl,
            pocall_stdcall,
            pocall_cppdecl,
            pocall_mwpascal:
              result:=DW_CC_normal;
            else
              result:=DW_CC_nocall;
          end
        end;

      var
        procendlabel   : tasmlabel;
        funcrettype    : tasmsymbol;
        procentry      : string;
        dreg           : byte;
      begin
        if not assigned(def.procstarttai) then
          exit;

        current_asmdata.asmlists[al_dwarf_info].concat(tai_comment.Create(strpnew('Procdef '+def.fullprocname(true))));
        append_entry(DW_TAG_subprogram,true,
          [DW_AT_name,DW_FORM_string,symname(def.procsym)+#0,
           DW_AT_calling_convention,DW_FORM_data1,dwarf_calling_convention(def),
           DW_AT_external,DW_FORM_flag,po_global in def.procoptions
          { data continues below }
          { problem: base reg isn't known here
            DW_AT_frame_base,DW_FORM_block1,1
          }
          ]);
        { append block data }
        { current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(dwarf_reg(def.))); }

        if not(is_void(tprocdef(def).returndef)) then
          append_labelentry_ref(DW_AT_type,def_dwarf_lab(tprocdef(def).returndef));

        { mark end of procedure }
        current_asmdata.getlabel(procendlabel,alt_dbgtype);
        current_asmdata.asmlists[al_procedures].insertbefore(tai_label.create(procendlabel),def.procendtai);

        if (target_info.system = system_powerpc64_linux) then
          procentry := '.' + def.mangledname
        else
          procentry := def.mangledname;

        append_labelentry(DW_AT_low_pc,current_asmdata.RefAsmSymbol(procentry));
        append_labelentry(DW_AT_high_pc,procendlabel);

        { Don't write the funcretsym explicitly, it's also in the
          localsymtable and/or parasymtable.
        }
        finish_entry;

        if assigned(def.parast) then
          write_symtable_syms(current_asmdata.asmlists[al_dwarf_info],def.parast);
        { local type defs and vars should not be written
          inside the main proc }
        if assigned(def.localst) and
           (def.localst.symtabletype=localsymtable) then
          write_symtable_syms(current_asmdata.asmlists[al_dwarf_info],def.localst);

        { last write the types from this procdef }
        if assigned(def.parast) then
          write_symtable_defs(current_asmdata.asmlists[al_dwarf_info],def.parast);
        if assigned(def.localst) and
           (def.localst.symtabletype=localsymtable) then
          write_symtable_defs(current_asmdata.asmlists[al_dwarf_info],def.localst);

        finish_children;
      end;


    function TDebugInfoDwarf.get_symlist_sym_offset(symlist: ppropaccesslistitem; out sym: tabstractvarsym; out offset: pint): boolean;
      var
        elesize : pint;
        currdef : tdef;
      begin
        result:=false;
        if not assigned(symlist) then
          exit;
        sym:=nil;
        offset:=0;
        currdef:=nil;
        repeat
          case symlist^.sltype of
            sl_load:
              begin
                if assigned(sym) then
                  internalerror(2009031203);
                if not(symlist^.sym.typ in [paravarsym,localvarsym,staticvarsym,fieldvarsym]) then
                  { can't handle... }
                  exit;
                sym:=tabstractvarsym(symlist^.sym);
                currdef:=tabstractvarsym(sym).vardef;
              end;
            sl_subscript:
              begin
                if not assigned(currdef) then
                  internalerror(2009031301);
                if (symlist^.sym.typ<>fieldvarsym) then
                  internalerror(2009031202);
                if is_packed_record_or_object(currdef) then
                  begin
                    { can't calculate the address of a non-byte aligned field }
                    if (tfieldvarsym(symlist^.sym).fieldoffset mod 8) <> 0 then
                      exit;
                    inc(offset,tfieldvarsym(symlist^.sym).fieldoffset div 8)
                  end
                else
                  inc(offset,tfieldvarsym(symlist^.sym).fieldoffset);
                currdef:=tfieldvarsym(symlist^.sym).vardef;
              end;
            sl_absolutetype,
            sl_typeconv:
              begin
                currdef:=tfieldvarsym(symlist^.sym).vardef;
                { ignore, these don't change the address }
              end;
            sl_vec:
              begin
                if not assigned(currdef) or
                   (currdef.typ<>arraydef) then
                  internalerror(2009031201);
                if not is_packed_array(currdef) then
                  elesize:=tarraydef(currdef).elesize
                else
                  begin
                    elesize:=tarraydef(currdef).elepackedbitsize;
                    { can't calculate the address of a non-byte aligned element }
                    if (elesize mod 8)<>0 then
                      exit;
                    elesize:=elesize div 8;
                  end;
                inc(offset,(symlist^.value.svalue-tarraydef(currdef).lowrange)*elesize);
                currdef:=tarraydef(currdef).elementdef;
              end;
            else
              internalerror(2009031401);
          end;
          symlist:=symlist^.next;
        until not assigned(symlist);
        if not assigned(sym) then
          internalerror(2009031205);
        result:=true;
      end;


    procedure TDebugInfoDwarf.appendsym_var(list:TAsmList;sym:tabstractnormalvarsym);
      begin
        appendsym_var_with_name_type_offset(list,sym,symname(sym),sym.vardef,0);
      end;


    procedure TDebugInfoDwarf.appendsym_var_with_name_type_offset(list:TAsmList; sym:tabstractnormalvarsym; const name: string; def: tdef; offset: pint);
      var
        templist : TAsmList;
        blocksize : longint;
        tag : tdwarf_tag;
        dreg : byte;
      begin
        { external symbols can't be resolved at link time, so we
          can't generate stabs for them

          not sure if this applies to dwarf as well (FK)
        }
        if vo_is_external in sym.varoptions then
          exit;

        { There is no space allocated for not referenced locals }
        if (sym.owner.symtabletype=localsymtable) and (sym.refs=0) then
          exit;

        templist:=TAsmList.create;

        case sym.localloc.loc of
          LOC_REGISTER,
          LOC_CREGISTER,
          LOC_MMREGISTER,
          LOC_CMMREGISTER,
          LOC_FPUREGISTER,
          LOC_CFPUREGISTER :
            begin
              templist.concat(tai_const.create_8bit(ord(DW_OP_regx)));
              dreg:=dwarf_reg(sym.localloc.register);
              templist.concat(tai_const.create_uleb128bit(dreg));
              blocksize:=1+Lengthuleb128(dreg);
            end;
          else
            begin
              case sym.typ of
                staticvarsym:
                  begin
                    if (vo_is_thread_var in sym.varoptions) then
                      begin
{ TODO: !!! FIXME: dwarf for thread vars !!!}
                        blocksize:=0;
                      end
                    else
                      begin
                        templist.concat(tai_const.create_8bit(ord(DW_OP_addr)));
                        templist.concat(tai_const.createname(sym.mangledname,offset));
                        blocksize:=1+sizeof(puint);
                      end;
                  end;
                paravarsym,
                localvarsym:
                  begin
                    dreg:=dwarf_reg(sym.localloc.reference.base);
                    templist.concat(tai_const.create_8bit(ord(DW_OP_breg0)+dreg));
                    templist.concat(tai_const.create_sleb128bit(sym.localloc.reference.offset+offset));
                    blocksize:=1+Lengthsleb128(sym.localloc.reference.offset);
                  end
                else
                  internalerror(200601288);
              end;
            end;
        end;

        { function results must not be added to the parameter list,
          as they are not part of the signature of the function
          (gdb automatically adds them according to the ABI specifications
           when calling the function)
        }
        if (sym.typ=paravarsym) and
           not(vo_is_funcret in sym.varoptions) then
          tag:=DW_TAG_formal_parameter
        else
          tag:=DW_TAG_variable;

        if not(sym.localloc.loc in [LOC_REGISTER,LOC_CREGISTER,LOC_MMREGISTER,
                                 LOC_CMMREGISTER,LOC_FPUREGISTER,LOC_CFPUREGISTER]) and
           ((sym.owner.symtabletype = globalsymtable) or
            (sp_static in sym.symoptions) or
            (vo_is_public in sym.varoptions)) then
          append_entry(tag,false,[
            DW_AT_name,DW_FORM_string,name+#0,
            {
            DW_AT_decl_file,DW_FORM_data1,0,
            DW_AT_decl_line,DW_FORM_data1,
            }
            DW_AT_external,DW_FORM_flag,true,
            { data continues below }
            DW_AT_location,DW_FORM_block1,blocksize
            ])
{$ifdef gdb_supports_DW_AT_variable_parameter}
        else if (sym.typ=paravarsym) and
            paramanager.push_addr_param(sym.varspez,sym.vardef,tprocdef(sym.owner.defowner).proccalloption) and
            not(vo_has_local_copy in sym.varoptions) and
            not is_open_string(sym.vardef) then
          append_entry(tag,false,[
            DW_AT_name,DW_FORM_string,name+#0,
            DW_AT_variable_parameter,DW_FORM_flag,true,
            {
            DW_AT_decl_file,DW_FORM_data1,0,
            DW_AT_decl_line,DW_FORM_data1,
            }
            { data continues below }
            DW_AT_location,DW_FORM_block1,blocksize
            ])
{$endif gdb_supports_DW_AT_variable_parameter}
        else
          append_entry(tag,false,[
            DW_AT_name,DW_FORM_string,name+#0,
            {
            DW_AT_decl_file,DW_FORM_data1,0,
            DW_AT_decl_line,DW_FORM_data1,
            }
            { data continues below }
            DW_AT_location,DW_FORM_block1,blocksize
            ]);
        { append block data }
        current_asmdata.asmlists[al_dwarf_info].concatlist(templist);
{$ifndef gdb_supports_DW_AT_variable_parameter}
        if (sym.typ=paravarsym) and
            paramanager.push_addr_param(sym.varspez,sym.vardef,tprocdef(sym.owner.defowner).proccalloption) and
            not(vo_has_local_copy in sym.varoptions) and
            not is_open_string(sym.vardef) then
          append_labelentry_ref(DW_AT_type,def_dwarf_ref_lab(def))
        else
{$endif not gdb_supports_DW_AT_variable_parameter}
          append_labelentry_ref(DW_AT_type,def_dwarf_lab(def));

        templist.free;

        finish_entry;
      end;


    procedure TDebugInfoDwarf.appendsym_staticvar(list:TAsmList;sym:tstaticvarsym);
      begin
        appendsym_var(list,sym);
      end;


    procedure TDebugInfoDwarf.appendsym_localvar(list:TAsmList;sym:tlocalvarsym);
      begin
        appendsym_var(list,sym);
      end;


    procedure TDebugInfoDwarf.appendsym_paravar(list:TAsmList;sym:tparavarsym);
      begin
        appendsym_var(list,sym);
      end;


    procedure TDebugInfoDwarf.appendsym_fieldvar(list:TAsmList;sym: tfieldvarsym);
      begin
        appendsym_fieldvar_with_name_offset(list,sym,symname(sym),sym.vardef,0);
      end;


    procedure TDebugInfoDwarf.appendsym_fieldvar_with_name_offset(list:TAsmList;sym: tfieldvarsym;const name: string; def: tdef; offset: pint);
      var
        bitoffset,
        fieldoffset,
        fieldnatsize: aint;
      begin
        if (sp_static in sym.symoptions) or
           (sym.visibility=vis_hidden) then
          exit;

        if (tabstractrecordsymtable(sym.owner).usefieldalignment<>bit_alignment) or
           { only ordinals are bitpacked }
           not is_ordinal(sym.vardef) then
          begin
            { other kinds of fields can however also appear in a bitpacked   }
            { record, and then their offset is also specified in bits rather }
            { than in bytes                                                  }
            if (tabstractrecordsymtable(sym.owner).usefieldalignment<>bit_alignment) then
              fieldoffset:=sym.fieldoffset
            else
              fieldoffset:=sym.fieldoffset div 8;
            inc(fieldoffset,offset);
            append_entry(DW_TAG_member,false,[
              DW_AT_name,DW_FORM_string,name+#0,
              DW_AT_data_member_location,DW_FORM_block1,1+lengthuleb128(fieldoffset)
              ]);
          end
        else
          begin
            if (sym.vardef.packedbitsize > 255) then
              internalerror(2007061201);

            { we don't bitpack according to the ABI, but as close as }
            { possible, i.e., equivalent to gcc's                    }
            { __attribute__((__packed__)), which is also what gpc    }
            { does.                                                  }
            fieldnatsize:=max(sizeof(pint),sym.vardef.size);
            fieldoffset:=(sym.fieldoffset div (fieldnatsize*8)) * fieldnatsize;
            inc(fieldoffset,offset);
            bitoffset:=sym.fieldoffset mod (fieldnatsize*8);
            if (target_info.endian=endian_little) then
              bitoffset:=(fieldnatsize*8)-bitoffset-sym.vardef.packedbitsize;
            append_entry(DW_TAG_member,false,[
              DW_AT_name,DW_FORM_string,symname(sym)+#0,
              { gcc also generates both a bit and byte size attribute }
              { we don't support ordinals >= 256 bits }
              DW_AT_byte_size,DW_FORM_data1,fieldnatsize,
              { nor >= 256 bits (not yet, anyway, see IE above) }
              DW_AT_bit_size,DW_FORM_data1,sym.vardef.packedbitsize,
              { data1 and data2 are unsigned, bitoffset can also be negative }
              DW_AT_bit_offset,DW_FORM_data4,bitoffset,
              DW_AT_data_member_location,DW_FORM_block1,1+lengthuleb128(fieldoffset)
              ]);
          end;
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_plus_uconst)));
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_uleb128bit(fieldoffset));

        append_labelentry_ref(DW_AT_type,def_dwarf_lab(def));
        finish_entry;
      end;


    procedure TDebugInfoDwarf.appendsym_const(list:TAsmList;sym:tconstsym);
      begin
        append_entry(DW_TAG_constant,false,[
          DW_AT_name,DW_FORM_string,symname(sym)+#0
          ]);
        { for string constants, constdef isn't set because they have no real type }
        if not(sym.consttyp in [conststring,constresourcestring,constwstring]) then
          append_labelentry_ref(DW_AT_type,def_dwarf_lab(sym.constdef));
        current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(DW_AT_const_value)));
        case sym.consttyp of
          conststring:
            begin
              current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(DW_FORM_string)));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_string.create(strpas(pchar(sym.value.valueptr))));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(0));
            end;
          constset,
          constwstring,
          constguid,
          constresourcestring:
            begin
              { write dummy for now }
              current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(DW_FORM_string)));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_string.create(''));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(0));
            end;
          constord:
            begin
              current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(DW_FORM_sdata)));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_sleb128bit(sym.value.valueord.svalue));
            end;
          constnil:
            begin
{$ifdef cpu64bitaddr}
              current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(DW_FORM_data8)));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_64bit(0));
{$else cpu64bitaddr}
              current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(DW_FORM_data4)));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_32bit(0));
{$endif cpu64bitaddr}
            end;
          constpointer:
            begin
{$ifdef cpu64bitaddr}
              current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(DW_FORM_data8)));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_64bit(int64(sym.value.valueordptr)));
{$else cpu64bitaddr}
              current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(DW_FORM_data4)));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_32bit(longint(sym.value.valueordptr)));
{$endif cpu64bitaddr}
            end;
          constreal:
            begin
              current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_uleb128bit(ord(DW_FORM_block1)));
              case tfloatdef(sym.constdef).floattype of
                s32real:
                  begin
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(4));
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_real_32bit.create(psingle(sym.value.valueptr)^));
                  end;
                s64comp,
                s64currency,
                s64real:
                  begin
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(8));
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_real_64bit.create(pdouble(sym.value.valueptr)^));
                  end;
                s80real:
                  begin
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(10));
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_real_80bit.create(pextended(sym.value.valueptr)^));
                  end;
                else
                  internalerror(200601291);
              end;
            end;
          else
            internalerror(200601292);
        end;
        finish_entry;
      end;


    procedure TDebugInfoDwarf.appendsym_label(list:TAsmList;sym: tlabelsym);
      begin
        { ignore label syms for now, the problem is that a label sym
          can have more than one label associated e.g. in case of
          an inline procedure expansion }
      end;


    procedure TDebugInfoDwarf.appendsym_property(list:TAsmList;sym: tpropertysym);
      var
        symlist: ppropaccesslistitem;
        tosym: tabstractvarsym;
        offset: pint;
      begin
        if assigned(sym.propaccesslist[palt_read]) and
           not assigned(sym.propaccesslist[palt_read].procdef) then
          symlist:=sym.propaccesslist[palt_read].firstsym
        else
          { can't handle }
          exit;

        if not get_symlist_sym_offset(symlist,tosym,offset) then
          exit;

        if (tosym.owner.symtabletype<>objectsymtable) then
          begin
            if (tosym.typ=fieldvarsym) then
              internalerror(2009031404);
            appendsym_var_with_name_type_offset(list,tabstractnormalvarsym(tosym),symname(sym),sym.propdef,offset)
          end
        else
          appendsym_fieldvar_with_name_offset(list,tfieldvarsym(tosym),symname(sym),sym.propdef,offset)
      end;


    procedure TDebugInfoDwarf.appendsym_type(list:TAsmList;sym: ttypesym);
      begin
        if not (target_info.system in systems_darwin) then
          begin
            if not(df_generic in sym.typedef.defoptions) then
              begin
                append_entry(DW_TAG_typedef,false,[
                  DW_AT_name,DW_FORM_string,symname(sym)+#0
                ]);
                append_labelentry_ref(DW_AT_type,def_dwarf_lab(sym.typedef));
              end;
            finish_entry;
          end
        else
          { just queue the def if needed }
          def_dwarf_lab(sym.typedef);
      end;


    procedure TDebugInfoDwarf.appendsym_absolute(list:TAsmList;sym:tabsolutevarsym);
      var
        templist : TAsmList;
        blocksize : longint;
        symlist : ppropaccesslistitem;
        tosym: tabstractvarsym;
        offset: pint;
      begin
        templist:=TAsmList.create;
        case tabsolutevarsym(sym).abstyp of
          toaddr :
            begin
               { MWE: replaced ifdef i368 }
               (*
               if target_cpu = cpu_i386 then
                 begin
                  { in theory, we could write a DW_AT_segment entry here for sym.absseg,
                    however I doubt that gdb supports this (FK) }
                 end;
               *)
               templist.concat(tai_const.create_8bit(3));
               templist.concat(tai_const.create_pint(sym.addroffset));
               blocksize:=1+sizeof(puint);
            end;
          toasm :
            begin
              templist.concat(tai_const.create_8bit(3));
              templist.concat(tai_const.createname(sym.mangledname,0));
              blocksize:=1+sizeof(puint);
            end;
          tovar:
            begin
              symlist:=tabsolutevarsym(sym).ref.firstsym;
              get_symlist_sym_offset(symlist,tosym,offset);
              if (tosym.typ=fieldvarsym) then
                internalerror(2009031402);
              appendsym_var_with_name_type_offset(list,tabstractnormalvarsym(tosym),symname(sym),tabstractvarsym(sym).vardef,offset);
              templist.free;
              exit;
            end;
        end;

        append_entry(DW_TAG_variable,false,[
          DW_AT_name,DW_FORM_string,symname(sym)+#0,
          {
          DW_AT_decl_file,DW_FORM_data1,0,
          DW_AT_decl_line,DW_FORM_data1,
          }
          DW_AT_external,DW_FORM_flag,true,
          { data continues below }
          DW_AT_location,DW_FORM_block1,blocksize
          ]);
        { append block data }
        current_asmdata.asmlists[al_dwarf_info].concatlist(templist);
        append_labelentry_ref(DW_AT_type,def_dwarf_lab(sym.vardef));

        templist.free;

        finish_entry;
      end;


    procedure TDebugInfoDwarf.beforeappendsym(list:TAsmList;sym:tsym);
      begin
        current_asmdata.asmlists[al_dwarf_info].concat(tai_comment.Create(strpnew('Symbol '+symname(sym))));
      end;


    procedure TDebugInfoDwarf.insertmoduleinfo;
      var
        templist: TAsmList;
        linelist: TAsmList;
        lbl   : tasmlabel;
        n,m   : Integer;
        ditem : TDirIndexItem;
        fitem : TFileIndexItem;
        flist : TFPList;
      begin
        { doesn't work for windows, because it puts no code per module in the .text section }
        if not(target_info.system in system_all_windows) then
          begin
            { insert .Ltext0 label }
            templist:=TAsmList.create;
            new_section(templist,sec_code,'',0);
            templist.concat(tai_symbol.createname(target_asm.labelprefix+'text0',AT_DATA,0));
            current_asmdata.asmlists[al_start].insertlist(templist);
            templist.free;
    
            { insert .Letext0 label }
            templist:=TAsmList.create;
            new_section(templist,sec_code,'',0);
            templist.concat(tai_symbol.createname(target_asm.labelprefix+'etext0',AT_DATA,0));
            current_asmdata.asmlists[al_end].insertlist(templist);
            templist.free;
          end;

        { insert .Ldebug_abbrev0 label }
        templist:=TAsmList.create;
        new_section(templist,sec_debug_abbrev,'',0);
        templist.concat(tai_symbol.createname(target_asm.labelprefix+'debug_abbrevsection0',AT_DATA,0));
        { add any extra stuff which needs to be in the abbrev section, but before    }
        { the actual abbreviations, in between the symbol above and below, i.e. here }
        templist.concat(tai_symbol.createname(target_asm.labelprefix+'debug_abbrev0',AT_DATA,0));
        current_asmdata.asmlists[al_start].insertlist(templist);
        templist.free;

        { insert .Ldebug_line0 label }
        templist:=TAsmList.create;
        new_section(templist,sec_debug_line,'',0);
        templist.concat(tai_symbol.createname(target_asm.labelprefix+'debug_linesection0',AT_DATA,0));
        { add any extra stuff which needs to be in the line section, but before  }
        { the actual line info, in between the symbol above and below, i.e. here }
        templist.concat(tai_symbol.createname(target_asm.labelprefix+'debug_line0',AT_DATA,0));
        current_asmdata.asmlists[al_start].insertlist(templist);
        templist.free;

        { finalize line info if the unit doesn't contain any function/ }
        { procedure/init/final code                                    }
        finish_lineinfo;

        { debug line header }
        linelist := current_asmdata.asmlists[al_dwarf_line];
        new_section(linelist,sec_debug_line,'',0);
        linelist.concat(tai_comment.Create(strpnew('=== header start ===')));

        { size }
        current_asmdata.getlabel(lbl,alt_dbgfile);
        if use_64bit_headers then
          linelist.concat(tai_const.create_32bit(longint($FFFFFFFF)));
        linelist.concat(tai_const.create_rel_sym(offsetreltype,
          lbl,current_asmdata.RefAsmSymbol(target_asm.labelprefix+'edebug_line0')));
        linelist.concat(tai_label.create(lbl));

        { version }
        linelist.concat(tai_const.create_16bit(dwarf_version));

        { header length }
        current_asmdata.getlabel(lbl,alt_dbgfile);
        linelist.concat(tai_const.create_rel_sym(offsetreltype,
          lbl,current_asmdata.RefAsmSymbol(target_asm.labelprefix+'ehdebug_line0')));
        linelist.concat(tai_label.create(lbl));

        { minimum_instruction_length }
        linelist.concat(tai_const.create_8bit(1));

        { default_is_stmt }
        linelist.concat(tai_const.create_8bit(1));

        { line_base }
        linelist.concat(tai_const.create_8bit(LINE_BASE));

        { line_range }
        { only line increase, no adress }
        linelist.concat(tai_const.create_8bit(255));

        { opcode_base }
        linelist.concat(tai_const.create_8bit(OPCODE_BASE));

        { standard_opcode_lengths }
        { MWE: sigh... why adding the default lengths (and make those sizes sense with LEB encoding) }
          { DW_LNS_copy }
        linelist.concat(tai_const.create_8bit(0));
          { DW_LNS_advance_pc }
        linelist.concat(tai_const.create_8bit(1));
          { DW_LNS_advance_line }
        linelist.concat(tai_const.create_8bit(1));
          { DW_LNS_set_file }
        linelist.concat(tai_const.create_8bit(1));
          { DW_LNS_set_column }
        linelist.concat(tai_const.create_8bit(1));
          { DW_LNS_negate_stmt }
        linelist.concat(tai_const.create_8bit(0));
          { DW_LNS_set_basic_block }
        linelist.concat(tai_const.create_8bit(0));
          { DW_LNS_const_add_pc }
        linelist.concat(tai_const.create_8bit(0));
          { DW_LNS_fixed_advance_pc }
        linelist.concat(tai_const.create_8bit(1));
          { DW_LNS_set_prologue_end }
        linelist.concat(tai_const.create_8bit(0));
          { DW_LNS_set_epilogue_begin }
        linelist.concat(tai_const.create_8bit(0));
          { DW_LNS_set_isa }
        linelist.concat(tai_const.create_8bit(1));

        { Create single list of filenames sorted in IndexNr }
        flist:=TFPList.Create;
        for n := 0 to dirlist.Count - 1 do
          begin
            ditem := TDirIndexItem(dirlist[n]);
            for m := 0 to ditem.Files.Count - 1 do
              flist.Add(ditem.Files[m]);
          end;
        flist.Sort(@FileListSortCompare);

        { include_directories }
        linelist.concat(tai_comment.Create(strpnew('include_directories')));
        for n := 0 to dirlist.Count - 1 do
          begin
            ditem := TDirIndexItem(dirlist[n]);
            if ditem.Name = '.' then
              Continue;
            { Write without trailing path delimiter and also don't prefix with ./ for current dir (already done while adding to dirlist }

            linelist.concat(tai_string.create(ditem.Name+#0));
          end;
        linelist.concat(tai_const.create_8bit(0));

        { file_names }
        linelist.concat(tai_comment.Create(strpnew('file_names')));
        for n := 0 to flist.Count - 1 do
          begin
            fitem := TFileIndexItem(flist[n]);
            { file name }
            linelist.concat(tai_string.create(fitem.Name+#0));
            { directory index }
            linelist.concat(tai_const.create_uleb128bit(fitem.DirIndex));
            { last modification }
            linelist.concat(tai_const.create_uleb128bit(0));
            { file length }
            linelist.concat(tai_const.create_uleb128bit(0));
          end;
        linelist.concat(tai_const.create_8bit(0));

        { end of debug line header }
        linelist.concat(tai_symbol.createname(target_asm.labelprefix+'ehdebug_line0',AT_DATA,0));
        linelist.concat(tai_comment.Create(strpnew('=== header end ===')));

        { add line program }
        linelist.concatList(asmline);

        { end of debug line table }
        linelist.concat(tai_symbol.createname(target_asm.labelprefix+'edebug_line0',AT_DATA,0));

        flist.free;
      end;


    procedure TDebugInfoDwarf.inserttypeinfo;

      procedure write_defs_to_write;
        var
          n       : integer;
          looplist,
          templist: TFPObjectList;
          def     : tdef;
        begin
          templist := TFPObjectList.Create(False);
          looplist := deftowritelist;
          while looplist.count > 0 do
            begin
              deftowritelist := templist;
              for n := 0 to looplist.count - 1 do
                begin
                  def := tdef(looplist[n]);
                  case def.dbg_state of
                    dbg_state_written:
                      continue;
                    dbg_state_writing:
                      internalerror(200610052);
                    dbg_state_unused:
                      internalerror(200610053);
                    dbg_state_used:
                      appenddef(nil,def)
                  else
                    internalerror(200610054);
                  end;
                end;
              looplist.clear;
              templist := looplist;
              looplist := deftowritelist;
            end;
          templist.free;
        end;


      var
        storefilepos  : tfileposinfo;
        lenstartlabel : tasmlabel;
        i : longint;
        def: tdef;
      begin
        storefilepos:=current_filepos;
        current_filepos:=current_module.mainfilepos;

        currabbrevnumber:=0;

        defnumberlist:=TFPObjectList.create(false);
        deftowritelist:=TFPObjectList.create(false);

        { not exported (FK)
            FILEREC
            TEXTREC
        }
        vardatadef:=trecorddef(search_system_type('TVARDATA').typedef);

        { write start labels }
        current_asmdata.asmlists[al_dwarf_info].concat(tai_section.create(sec_debug_info,'',0));
        current_asmdata.asmlists[al_dwarf_info].concat(tai_symbol.createname(target_asm.labelprefix+'debug_info0',AT_DATA,0));

        { start abbrev section }
        new_section(current_asmdata.asmlists[al_dwarf_abbrev],sec_debug_abbrev,'',0);

        { debug info header }
        current_asmdata.getlabel(lenstartlabel,alt_dbgfile);
        { size }
        if use_64bit_headers then
          current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_32bit(longint($FFFFFFFF)));
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_rel_sym(offsetreltype,
          lenstartlabel,current_asmdata.RefAsmSymbol(target_asm.labelprefix+'edebug_info0')));

        current_asmdata.asmlists[al_dwarf_info].concat(tai_label.create(lenstartlabel));
        { version }
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_16bit(dwarf_version));
        { abbrev table (=relative from section start)}
        if not(tf_dwarf_relative_addresses in target_info.flags) then
          current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_type_sym(offsetabstype,
            current_asmdata.RefAsmSymbol(target_asm.labelprefix+'debug_abbrev0')))
        else
          current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_rel_sym(offsetreltype,
            current_asmdata.RefAsmSymbol(target_asm.labelprefix+'debug_abbrevsection0'),
            current_asmdata.RefAsmSymbol(target_asm.labelprefix+'debug_abbrev0')));

        { address size }
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(sizeof(pint)));

        { first manadatory compilation unit TAG }
        append_entry(DW_TAG_compile_unit,true,[
          DW_AT_name,DW_FORM_string,relative_dwarf_path(current_module.sourcefiles.get_file(1).path^+current_module.sourcefiles.get_file(1).name^)+#0,
          DW_AT_producer,DW_FORM_string,'Free Pascal '+full_version_string+' '+date_string+#0,
          DW_AT_comp_dir,DW_FORM_string,BSToSlash(FixPath(GetCurrentDir,false))+#0,
          DW_AT_language,DW_FORM_data1,DW_LANG_Pascal83,
          DW_AT_identifier_case,DW_FORM_data1,DW_ID_case_insensitive]);

        { reference to line info section }
        if not(tf_dwarf_relative_addresses in target_info.flags) then
          append_labelentry_dataptr_abs(DW_AT_stmt_list,current_asmdata.RefAsmSymbol(target_asm.labelprefix+'debug_line0'))
        else
          append_labelentry_dataptr_rel(DW_AT_stmt_list,
            current_asmdata.RefAsmSymbol(target_asm.labelprefix+'debug_linesection0'),
            current_asmdata.RefAsmSymbol(target_asm.labelprefix+'debug_line0'));

        { see comments above where these labels are created and inserted }
        if not(target_info.system in system_all_windows) then
          begin
            append_labelentry(DW_AT_low_pc,current_asmdata.RefAsmSymbol(target_asm.labelprefix+'text0'));
            append_labelentry(DW_AT_high_pc,current_asmdata.RefAsmSymbol(target_asm.labelprefix+'etext0'));
          end;

        finish_entry;

        { write all global/local variables. This will flag all required tdefs  }
        if assigned(current_module.globalsymtable) then
          write_symtable_syms(current_asmdata.asmlists[al_dwarf_info],current_module.globalsymtable);
        if assigned(current_module.localsymtable) then
          write_symtable_syms(current_asmdata.asmlists[al_dwarf_info],current_module.localsymtable);

        { write all procedures and methods. This will flag all required tdefs }
        if assigned(current_module.globalsymtable) then
          write_symtable_procdefs(current_asmdata.asmlists[al_dwarf_info],current_module.globalsymtable);
        if assigned(current_module.localsymtable) then
          write_symtable_procdefs(current_asmdata.asmlists[al_dwarf_info],current_module.localsymtable);

        { reset unit type info flag }
        reset_unit_type_info;

        { write used types from the used units }
        write_used_unit_type_info(current_asmdata.asmlists[al_dwarf_info],current_module);

        { last write the types from this unit }
        if assigned(current_module.globalsymtable) then
          write_symtable_defs(current_asmdata.asmlists[al_dwarf_info],current_module.globalsymtable);
        if assigned(current_module.localsymtable) then
          write_symtable_defs(current_asmdata.asmlists[al_dwarf_info],current_module.localsymtable);

        { write defs not written yet }
        write_defs_to_write;

        { close compilation unit entry }
        finish_children;

        { end of debug info table }
        current_asmdata.asmlists[al_dwarf_info].concat(tai_symbol.createname(target_asm.labelprefix+'edebug_info0',AT_DATA,0));

        { end of abbrev table }
        current_asmdata.asmlists[al_dwarf_abbrev].concat(tai_const.create_8bit(0));

        { reset all def labels }
        for i:=0 to defnumberlist.count-1 do
          begin
            def := tdef(defnumberlist[i]);
            if assigned(def) then
              begin
                def.dwarf_lab:=nil;
                def.dbg_state:=dbg_state_unused;
              end;
          end;

        defnumberlist.free;
        defnumberlist:=nil;
        deftowritelist.free;
        deftowritelist:=nil;

        current_filepos:=storefilepos;
      end;


    procedure TDebugInfoDwarf.referencesections(list:TAsmList);
      begin
      end;


    function TDebugInfoDwarf.symname(sym: tsym): String;
      begin
        if (sym.typ=paravarsym) and
           (vo_is_self in tparavarsym(sym).varoptions) then
          result:='this'
        else
          result := sym.Name;
      end;


    procedure TDebugInfoDwarf.insertlineinfo(list:TAsmList);
      var
        currfileinfo,
        lastfileinfo : tfileposinfo;
        currfuncname : pshortstring;
        currsectype  : TAsmSectiontype;
        hp, hpend : tai;
        infile : tinputfile;
        prevcolumn,
        diffline,
        prevline,
        prevfileidx,
        currfileidx: Integer;
        prevlabel,
        currlabel     : tasmlabel;
      begin
        { this function will always terminate the lineinfo block }
        generated_lineinfo := true;
        FillChar(lastfileinfo,sizeof(lastfileinfo),0);
        currfuncname:=nil;
        currsectype:=sec_code;
        hp:=Tai(list.first);
        prevcolumn := 0;
        prevline := 1;
        prevfileidx := 1;
        prevlabel := nil;
        while assigned(hp) do
          begin
            case hp.typ of
              ait_section :
                currsectype:=tai_section(hp).sectype;
              ait_function_name :
                begin
                  currfuncname:=tai_function_name(hp).funcname;
                  asmline.concat(tai_comment.Create(strpnew('function: '+currfuncname^)));
                end;
              ait_force_line : begin
                lastfileinfo.line:=-1;
              end;
            end;

            if (currsectype=sec_code) and
               (hp.typ=ait_instruction) then
              begin
                currfileinfo:=tailineinfo(hp).fileinfo;
                { file changed ? (must be before line info) }
                if (currfileinfo.fileindex<>0) and
                   ((lastfileinfo.fileindex<>currfileinfo.fileindex) or
                    (lastfileinfo.moduleindex<>currfileinfo.moduleindex)) then
                  begin
                    infile:=get_module(currfileinfo.moduleindex).sourcefiles.get_file(currfileinfo.fileindex);
                    if assigned(infile) then
                      begin
                        currfileidx := get_file_index(infile);
                        if prevfileidx <> currfileidx then
                          begin
                            list.insertbefore(tai_comment.Create(strpnew('path: '+infile.path^)), hp);
                            list.insertbefore(tai_comment.Create(strpnew('file: '+infile.name^)), hp);
                            list.insertbefore(tai_comment.Create(strpnew('indx: '+tostr(currfileidx))), hp);

                            { set file }
                            asmline.concat(tai_comment.Create(strpnew('path: '+infile.path^)));
                            asmline.concat(tai_comment.Create(strpnew('file: '+infile.name^)));
                            asmline.concat(tai_const.create_8bit(DW_LNS_set_file));
                            asmline.concat(tai_const.create_uleb128bit(currfileidx));

                            prevfileidx := currfileidx;
                          end;
                        { force new line info }
                        lastfileinfo.line:=-1;
                      end;
                  end;

                { line changed ? }
                if (lastfileinfo.line<>currfileinfo.line) and (currfileinfo.line<>0) then
                  begin
                    { set address }
                    current_asmdata.getlabel(currlabel, alt_dbgline);
                    list.insertbefore(tai_label.create(currlabel), hp);

                    asmline.concat(tai_comment.Create(strpnew('['+tostr(currfileinfo.line)+':'+tostr(currfileinfo.column)+']')));

                    if (prevlabel = nil) or
                       { darwin's assembler cannot create an uleb128 of the difference }
                       { between to symbols                                            }
                       (target_info.system in systems_darwin) then
                      begin
                        asmline.concat(tai_const.create_8bit(DW_LNS_extended_op));
                        asmline.concat(tai_const.create_uleb128bit(1+sizeof(pint)));
                        asmline.concat(tai_const.create_8bit(DW_LNE_set_address));
                        asmline.concat(tai_const.create_sym(currlabel));
                      end
                    else
                      begin
                        asmline.concat(tai_const.create_8bit(DW_LNS_advance_pc));
                        asmline.concat(tai_const.create_rel_sym(aitconst_uleb128bit, prevlabel, currlabel));
                      end;
                    prevlabel := currlabel;

                    { set column }
                    if prevcolumn <> currfileinfo.column then
                      begin
                        asmline.concat(tai_const.create_8bit(DW_LNS_set_column));
                        asmline.concat(tai_const.create_uleb128bit(currfileinfo.column));
                        prevcolumn := currfileinfo.column;
                      end;

                    { set line }
                    diffline := currfileinfo.line - prevline;
                    if (diffline >= LINE_BASE) and (OPCODE_BASE + diffline - LINE_BASE <= 255) then
                      begin
                        { use special opcode, this also adds a row }
                        asmline.concat(tai_const.create_8bit(OPCODE_BASE + diffline - LINE_BASE));
                      end
                    else
                      begin
                        if diffline <> 0 then
                          begin
                            asmline.concat(tai_const.create_8bit(DW_LNS_advance_line));
                            asmline.concat(tai_const.create_sleb128bit(diffline));
                          end;
                        { no row added yet, do it manually }
                        asmline.concat(tai_const.create_8bit(DW_LNS_copy));
                      end;
                    prevline := currfileinfo.line;
                  end;

                lastfileinfo:=currfileinfo;
              end;

            hpend:=hp;
            hp:=tai(hp.next);
          end;

        if assigned(hpend) then
          begin
           { set address for end (see appendix 3 of dwarf 2 specs) }
            current_asmdata.getlabel(currlabel, alt_dbgline);
            list.insertafter(tai_label.create(currlabel), hpend);
            asmline.concat(tai_const.create_8bit(DW_LNS_extended_op));
            asmline.concat(tai_const.create_uleb128bit(1+sizeof(pint)));
            asmline.concat(tai_const.create_8bit(DW_LNE_set_address));
            asmline.concat(tai_const.create_sym(currlabel));
          end;

        { end sequence }
        asmline.concat(tai_const.Create_8bit(DW_LNS_extended_op));
        asmline.concat(tai_const.Create_8bit(1));
        asmline.concat(tai_const.Create_8bit(DW_LNE_end_sequence));
        asmline.concat(tai_comment.Create(strpnew('###################')));
      end;


    procedure TDebugInfoDwarf.finish_lineinfo;
      var
        infile: tinputfile;
      begin
        { only needed if no line info at all has been generated }
        if generated_lineinfo then
          begin
            { reset for next module compilation }
            generated_lineinfo:=false;
            exit;
          end;
        { at least the Darwin linker is annoyed if you do not }
        { finish the lineinfo section, or if it doesn't       }
        { contain at least one file name and set_address      }
        infile:=current_module.sourcefiles.get_file(1);
        if not assigned(infile) then
          internalerror(2006020211);
        asmline.concat(tai_const.create_8bit(DW_LNS_set_file));
        asmline.concat(tai_const.create_uleb128bit(get_file_index(infile)));

        asmline.concat(tai_const.create_8bit(DW_LNS_extended_op));
        asmline.concat(tai_const.create_uleb128bit(1+sizeof(pint)));
        asmline.concat(tai_const.create_8bit(DW_LNE_set_address));
        asmline.concat(tai_const.create_sym(nil));
        asmline.concat(tai_const.create_8bit(DW_LNS_extended_op));
        asmline.concat(tai_const.Create_8bit(1));
        asmline.concat(tai_const.Create_8bit(DW_LNE_end_sequence));
        asmline.concat(tai_comment.Create(strpnew('###################')));
      end;

{****************************************************************************
                              TDebugInfoDwarf2
****************************************************************************}

    procedure TDebugInfoDwarf2.appenddef_file(list:TAsmList;def: tfiledef);
      begin
        { gdb 6.4 doesn't support files so far so we use some fake recorddef
          file recs. are less than 1k so using data2 is enough }
        if assigned(def.typesym) then
          append_entry(DW_TAG_structure_type,false,[
           DW_AT_name,DW_FORM_string,symname(def.typesym)+#0,
           DW_AT_byte_size,DW_FORM_udata,def.size
          ])
        else
          append_entry(DW_TAG_structure_type,false,[
           DW_AT_byte_size,DW_FORM_udata,def.size
          ]);
        finish_entry;
      end;

    procedure TDebugInfoDwarf2.appenddef_formal(list:TAsmList;def: tformaldef);
      begin
        { gdb 6.4 doesn't support DW_TAG_unspecified_type so we
          replace it with a unsigned type with size 0 (FK)
        }
        append_entry(DW_TAG_base_type,false,[
          DW_AT_name,DW_FORM_string,'FormalDef'#0,
          DW_AT_encoding,DW_FORM_data1,DW_ATE_unsigned,
          DW_AT_byte_size,DW_FORM_data1,0
        ]);
        finish_entry;
      end;

    procedure TDebugInfoDwarf2.appenddef_object(list:TAsmList;def: tobjectdef);
      procedure doappend;
        begin
          if assigned(def.objname) then
            append_entry(DW_TAG_structure_type,true,[
              DW_AT_name,DW_FORM_string,def.objname^+#0,
              DW_AT_byte_size,DW_FORM_udata,tobjectsymtable(def.symtable).datasize
              ])
          else
            append_entry(DW_TAG_structure_type,true,[
              DW_AT_byte_size,DW_FORM_udata,tobjectsymtable(def.symtable).datasize
              ]);
          finish_entry;
          if assigned(def.childof) then
            begin
              append_entry(DW_TAG_inheritance,false,[
                DW_AT_accessibility,DW_FORM_data1,DW_ACCESS_public,
                DW_AT_data_member_location,DW_FORM_block1,1+lengthuleb128(0)
              ]);
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_plus_uconst)));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_uleb128bit(0));
              if (def.childof.dbg_state=dbg_state_unused) then
                def.childof.dbg_state:=dbg_state_used;
              if is_class_or_interface_or_dispinterface(def) then
                append_labelentry_ref(DW_AT_type,def_dwarf_class_struct_lab(def.childof))
              else
                append_labelentry_ref(DW_AT_type,def_dwarf_lab(def.childof));
              finish_entry;
            end;
          if (oo_has_vmt in def.objectoptions) and
             (not assigned(def.childof) or
              not(oo_has_vmt in def.childof.objectoptions)) then
            begin
              { vmt field }
              append_entry(DW_TAG_member,false,[
                  DW_AT_artificial,DW_FORM_flag,true,
                  DW_AT_name,DW_FORM_string,'_vptr$'+def.objname^+#0,
                  DW_AT_data_member_location,DW_FORM_block1,1+lengthuleb128(def.vmt_offset)
              ]);
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_plus_uconst)));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_uleb128bit(def.vmt_offset));
              { should be changed into a pointer to a function returning an }
              { int and with TAG_unspecified_parameters                     }
              if (voidpointertype.dbg_state=dbg_state_unused) then
                voidpointertype.dbg_state:=dbg_state_used;
              append_labelentry_ref(DW_AT_type,def_dwarf_lab(voidpointertype));
              finish_entry;
            end;

          def.symtable.symList.ForEachCall(@enum_membersyms_callback,nil);
          finish_children;
        end;


      begin
        case def.objecttype of
          odt_cppclass,
          odt_object:
            doappend;
          odt_interfacecom,
          odt_interfacecorba,
          odt_dispinterface,
          odt_class:
            begin
              { implicit pointer }
              append_entry(DW_TAG_pointer_type,false,[]);
              append_labelentry_ref(DW_AT_type,def_dwarf_class_struct_lab(def));
              finish_entry;

              if not(tf_dwarf_only_local_labels in target_info.flags) then
                current_asmdata.asmlists[al_dwarf_info].concat(tai_symbol.create_global(def_dwarf_class_struct_lab(def),0))
              else
                current_asmdata.asmlists[al_dwarf_info].concat(tai_symbol.create(def_dwarf_class_struct_lab(def),0));
              doappend;
            end;
          else
            internalerror(200602041);
        end;
      end;

    procedure TDebugInfoDwarf2.appenddef_set(list:TAsmList;def: tsetdef);
      var
        lab: tasmlabel;
      begin
        if (ds_dwarf_sets in current_settings.debugswitches) then
          begin
            { current (20070704 -- patch was committed on 20060513) gdb cvs supports set types }

            if assigned(def.typesym) then
              append_entry(DW_TAG_set_type,false,[
                DW_AT_name,DW_FORM_string,symname(def.typesym)+#0,
                DW_AT_byte_size,DW_FORM_data2,def.size
                ])
            else
              append_entry(DW_TAG_set_type,false,[
                DW_AT_byte_size,DW_FORM_data2,def.size
                ]);
            if assigned(def.elementdef) then
              begin
                if (def.elementdef.typ=enumdef) then
                  begin
                    { gdb 6.7 - 6.8 is broken for regular enum sets }
                    if not(tf_dwarf_only_local_labels in target_info.flags) then
                      current_asmdata.getdatalabel(lab)
                    else
                      current_asmdata.getaddrlabel(lab);
                    append_labelentry_ref(DW_AT_type,lab);
                    finish_entry;
                    current_asmdata.asmlists[al_dwarf_info].concat(tai_symbol.create(lab,0));
                    append_entry(DW_TAG_subrange_type,false,[
                      DW_AT_lower_bound,DW_FORM_sdata,tenumdef(def.elementdef).minval,
                      DW_AT_upper_bound,DW_FORM_sdata,tenumdef(def.elementdef).maxval
                      ]);
                  end;
                append_labelentry_ref(DW_AT_type,def_dwarf_lab(def.elementdef))
              end
          end
        else
          begin
            { gdb versions which don't support sets refuse to load the debug }
            { info of modules that contain set tags                          }
            if assigned(def.typesym) then
              append_entry(DW_TAG_base_type,false,[
                DW_AT_name,DW_FORM_string,symname(def.typesym)+#0,
                DW_AT_encoding,DW_FORM_data1,DW_ATE_unsigned,
                DW_AT_byte_size,DW_FORM_data2,def.size
                ])
            else
              append_entry(DW_TAG_base_type,false,[
                DW_AT_encoding,DW_FORM_data1,DW_ATE_unsigned,
                DW_AT_byte_size,DW_FORM_data2,def.size
                ]);
          end;
        finish_entry;
      end;

    procedure TDebugInfoDwarf2.appenddef_undefined(list:TAsmList;def: tundefineddef);
      begin
        { gdb 6.4 doesn't support DW_TAG_unspecified_type so we
          replace it with a unsigned type with size 0 (FK)
        }
        append_entry(DW_TAG_base_type,false,[
          DW_AT_name,DW_FORM_string,'FormalDef'#0,
          DW_AT_encoding,DW_FORM_data1,DW_ATE_unsigned,
          DW_AT_byte_size,DW_FORM_data1,0
        ]);
        finish_entry;
      end;

    procedure TDebugInfoDwarf2.appenddef_variant(list:TAsmList;def: tvariantdef);
      begin
        { variants aren't known to dwarf2 but writting tvardata should be enough }
        appenddef_record(list,trecorddef(vardatadef));
      end;

    function TDebugInfoDwarf2.dwarf_version: Word;
      begin
        Result:=2;
      end;

{****************************************************************************
                              TDebugInfoDwarf3
****************************************************************************}

    procedure tdebuginfodwarf3.appenddef_array(list: tasmlist; def: tarraydef);
      begin
        if not is_dynamic_array(def) then
          begin
            inherited appenddef_array(list,def);
            exit;
          end;

        if assigned(def.typesym) then
          append_entry(DW_TAG_array_type,true,[
            DW_AT_name,DW_FORM_string,symname(def.typesym)+#0,
            DW_AT_data_location,DW_FORM_block1,2
            ])
        else
          append_entry(DW_TAG_array_type,true,[
            DW_AT_data_location,DW_FORM_block1,2
            ]);
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_push_object_address)));
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_deref)));
        append_block1(DW_AT_allocated,2);
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_push_object_address)));
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_deref)));

        append_labelentry_ref(DW_AT_type,def_dwarf_lab(def.elementdef));
        finish_entry;
        { to simplify things, we don't write a multidimensional array here }
        append_entry(DW_TAG_subrange_type,false,[
          DW_AT_lower_bound,DW_FORM_udata,0,
          DW_AT_upper_bound,DW_FORM_block1,5
          ]);
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_push_object_address)));
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_deref)));
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_lit0)+sizeof(ptrint)));
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_minus)));
        current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_deref)));
        append_labelentry_ref(DW_AT_type,def_dwarf_lab(def.rangedef));
        finish_entry;

        finish_children;
      end;


    procedure tdebuginfodwarf3.appenddef_string(list: tasmlist; def: tstringdef);

      procedure addstringdef(const name: shortstring; chardef: tdef; deref: boolean; lensize: aint);
        var
          upperopcodes: longint;
        begin
          { deref=true -> ansi/unicde/widestring; deref = false -> short/longstring }
          if assigned(def.typesym) then
            append_entry(DW_TAG_array_type,true,[
              DW_AT_name,DW_FORM_string,name+#0,
              DW_AT_data_location,DW_FORM_block1,2+ord(not(deref))
              ])
          else
            append_entry(DW_TAG_array_type,true,[
              DW_AT_data_location,DW_FORM_block1,2+ord(not(deref))
              ]);

          { in all cases we start with the address of the string }
          current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_push_object_address)));
          if deref then
            begin
              { ansi/unicode/widestring -> dereference the address of the string, and then
                we point to address of the string
              }
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_deref)));

              { also add how to detect whether or not the string is allocated: if the pointer is 0
                then it isn't, otherwise it is
              }
              append_block1(DW_AT_allocated,2);
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_push_object_address)));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_deref)));
            end
          else
            begin
              { shortstring characters begin at string[1], so add one to the string's address }
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_lit0)+lensize));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_plus)))
            end;

          { reference to the element type of the string }
          append_labelentry_ref(DW_AT_type,def_dwarf_lab(chardef));
          finish_entry;

          { now the information about the length of the string }
          if deref then
            begin
              if (chardef.size=1) then
                upperopcodes:=5
              else
                upperopcodes:=7;
              { lower bound is always 1, upper bound (length) needs to be calculated }
              append_entry(DW_TAG_subrange_type,false,[
                DW_AT_lower_bound,DW_FORM_udata,1,
                DW_AT_upper_bound,DW_FORM_block1,upperopcodes
                ]);

              { high(string) is stored sizeof(ptrint) bytes before the string data }
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_push_object_address)));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_deref)));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_lit0)+sizeof(ptrint)));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_minus)));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_deref)));
              { for widestrings, the length is specified in bytes, so divide by two }
              if (upperopcodes=7) then
                begin
                  current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_lit1)));
                  current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_shra)));
                end;
            end
          else
            begin
              append_entry(DW_TAG_subrange_type,false,[
                DW_AT_lower_bound,DW_FORM_udata,1,
                DW_AT_upper_bound,DW_FORM_block1,3
                ]);
              { for shortstrings, the length is the first byte of the string }
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_push_object_address)));
              { load 1 byte }
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_deref_size)));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(lensize));
            end;
          finish_entry;

          finish_children;
        end;

      begin
        case def.stringtype of
          st_shortstring:
            begin
              addstringdef('ShortString',cchartype,false,1);
            end;
          st_longstring:
            begin
{$ifdef cpu64bitaddr}
              addstringdef('LongString',cchartype,false,8);
{$else cpu64bitaddr}
              addstringdef('LongString',cchartype,false,4);
{$endif cpu64bitaddr}
           end;
         st_ansistring:
           begin
             addstringdef('AnsiString',cchartype,true,-1);
           end;
         st_unicodestring:
           begin
             addstringdef('UnicodeString',cwidechartype,true,-1);
           end;
         st_widestring:
           begin
             if not(tf_winlikewidestring in target_info.flags) then
               addstringdef('WideString',cwidechartype,true,-1)
             else
               begin
                 { looks like a pwidechar (no idea about length location) }
                 append_entry(DW_TAG_pointer_type,false,[]);
                 append_labelentry_ref(DW_AT_type,def_dwarf_lab(cwidechartype));
                 finish_entry;
              end;
           end;
        end;
      end;

    procedure TDebugInfoDwarf3.appenddef_file(list:TAsmList;def: tfiledef);
      begin
        if assigned(def.typesym) then
          append_entry(DW_TAG_file_type,false,[
            DW_AT_name,DW_FORM_string,symname(def.typesym)+#0,
            DW_AT_byte_size,DW_FORM_data2,def.size
            ])
        else
          append_entry(DW_TAG_file_type,false,[
            DW_AT_byte_size,DW_FORM_data2,def.size
            ]);
        if tfiledef(def).filetyp=ft_typed then
          append_labelentry_ref(DW_AT_type,def_dwarf_lab(tfiledef(def).typedfiledef));
        finish_entry;
      end;

    procedure TDebugInfoDwarf3.appenddef_formal(list:TAsmList;def: tformaldef);
      begin
        append_entry(DW_TAG_unspecified_type,false,[
          ]);
        finish_entry;
      end;

    procedure TDebugInfoDwarf3.appenddef_object(list:TAsmList;def: tobjectdef);

      procedure dostruct(tag: tdwarf_tag);
        begin
          if assigned(def.objname) then
            append_entry(tag,true,[
              DW_AT_name,DW_FORM_string,def.objrealname^+#0,
              DW_AT_byte_size,DW_FORM_udata,def.size
              ])
          else
            append_entry(DW_TAG_structure_type,true,[
              DW_AT_byte_size,DW_FORM_udata,def.size
              ]);
          finish_entry;
        end;

      procedure doimplicitpointer;
        var
          obj : tasmlabel;
        begin
          if not(tf_dwarf_only_local_labels in target_info.flags) then
            current_asmdata.getdatalabel(obj)
          else
            current_asmdata.getaddrlabel(obj);
          { implicit pointer }
          append_entry(DW_TAG_pointer_type,false,[]);
          append_labelentry_ref(DW_AT_type,obj);
          finish_entry;

          current_asmdata.asmlists[al_dwarf_info].concat(tai_symbol.create(obj,0));
        end;

      procedure doparent(isinterface: boolean);
        begin
          if not assigned(def.childof) then
            exit;

          if isinterface then
            begin
              append_entry(DW_TAG_inheritance,false,[]);
            end
          else
            begin
              append_entry(DW_TAG_inheritance,false,[
                DW_AT_accessibility,DW_FORM_data1,DW_ACCESS_public,
                DW_AT_data_member_location,DW_FORM_block1,1+lengthuleb128(0)
              ]);
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_8bit(ord(DW_OP_plus_uconst)));
              current_asmdata.asmlists[al_dwarf_info].concat(tai_const.create_uleb128bit(0));
            end;
          append_labelentry_ref(DW_AT_type,def_dwarf_lab(def.childof));
          finish_entry;
        end;

      var
        n: integer;

      begin
        case def.objecttype of
          odt_cppclass,
          odt_object:
            begin
              dostruct(DW_TAG_structure_type);
              doparent(false);
            end;
          odt_interfacecom,
          odt_interfacecorba,
          odt_dispinterface:
            begin
              dostruct(DW_TAG_interface_type);
              doparent(true);
            end;
          odt_class:
            begin
              { not sure if the implicit pointer is needed for tag_class (MWE)}
              {
              doimplicitpointer;
              }
              dostruct(DW_TAG_class_type);
              doparent(false);
            end;
        else
          internalerror(200609171);
        end;

        { add implemented interfaces }
        if assigned(def.ImplementedInterfaces) then
          for n := 0 to def.ImplementedInterfaces.count-1 do
            begin
              append_entry(DW_TAG_inheritance,false,[]);
              append_labelentry_ref(DW_AT_type,def_dwarf_lab(TImplementedInterface(def.ImplementedInterfaces[n]).IntfDef));
              finish_entry;
            end;

        { add members }
        def.symtable.symList.ForEachCall(@enum_membersyms_callback,nil);
        finish_children;
      end;

    procedure TDebugInfoDwarf3.appenddef_set(list:TAsmList;def: tsetdef);
      begin
        if assigned(def.typesym) then
          append_entry(DW_TAG_set_type,false,[
            DW_AT_name,DW_FORM_string,symname(def.typesym)+#0,
            DW_AT_byte_size,DW_FORM_data2,def.size
            ])
        else
          append_entry(DW_TAG_set_type,false,[
            DW_AT_byte_size,DW_FORM_data2,def.size
            ]);
        if assigned(tsetdef(def).elementdef) then
          append_labelentry_ref(DW_AT_type,def_dwarf_lab(tsetdef(def).elementdef));
        finish_entry;
      end;

    procedure TDebugInfoDwarf3.appenddef_undefined(list:TAsmList;def: tundefineddef);
      begin
        { ??? can a undefined def have a typename ? }
        if assigned(def.typesym) then
          append_entry(DW_TAG_unspecified_type,false,[
            DW_AT_name,DW_FORM_string,symname(def.typesym)+#0
            ])
        else
          append_entry(DW_TAG_unspecified_type,false,[
            ]);
        finish_entry;
      end;

    procedure TDebugInfoDwarf3.appenddef_variant(list:TAsmList;def: tvariantdef);
      const
        VARIANTS: array[1..27] of record Value: Word; Name: String end = (
          (value:0;     name:''),
          (value:1;     name:''),
          (value:2;     name:'VSMALLINT'),
          (value:3;     name:'VINTEGER'),
          (value:4;     name:'VSINGLE'),
          (value:5;     name:'VDOUBLE'),
          (value:6;     name:'VCURRENCY'),
          (value:7;     name:'VDATE'),
          (value:8;     name:'VOLESTR'),
          (value:9;     name:'VDISPATCH'),
          (value:10;    name:'VERROR'),
          (value:11;    name:'VBOOLEAN'),
          (value:12;    name:''),
          (value:13;    name:'VUNKNOWN'),
          (value:14;    name:''),
          (value:16;    name:'VSHORTINT'),
          (value:17;    name:'VBYTE'),
          (value:18;    name:'VWORD'),
          (value:19;    name:'VLONGWORD'),
          (value:20;    name:'VINT64'),
          (value:21;    name:'VQWORD'),
          (value:36;    name:'VRECORD'),
          (value:$48;   name:''),
          (value:$100;  name:'VSTRING'),
          (value:$101;  name:'VANY'),
          (value:$2000; name:'VARRAY'),
          (value:$4000; name:'VPOINTER')
        );
      var
        fs: tfieldvarsym;
        lbl: tasmlabel;
        idx: integer;
      begin
        { it could be done with DW_TAG_variant for the union part (if that info was available)
          now we do it manually for variants (MWE) }

        { struct }
        append_entry(DW_TAG_structure_type,true,[
          DW_AT_name,DW_FORM_string,'Variant'#0,
          DW_AT_byte_size,DW_FORM_udata,vardatadef.size
          ]);
        finish_entry;

        append_entry(DW_TAG_variant_part,true,[
          ]);
        current_asmdata.getaddrlabel(lbl);
        append_labelentry_ref(DW_AT_discr,lbl);
        finish_entry;

        { discriminant }
        fs := tfieldvarsym(vardatadef.symtable.Find('VTYPE'));
        if (fs = nil) or (fs.typ <> fieldvarsym) then
          internalerror(200609271);
        current_asmdata.asmlists[al_dwarf_info].concat(tai_symbol.create(lbl,0));
        appendsym_fieldvar(list,fs);

        { variants }
        for idx := Low(VARIANTS) to High(VARIANTS) do
          begin
            append_entry(DW_TAG_variant,true,[
              DW_AT_discr_value,DW_FORM_udata,VARIANTS[idx].value
              ]);
            finish_entry;

            if VARIANTS[idx].name <> '' then
              begin
                fs := tfieldvarsym(vardatadef.symtable.Find(VARIANTS[idx].name));
                if (fs = nil) or (fs.typ <> fieldvarsym) then
                  internalerror(20060927200+idx);
                appendsym_fieldvar(list,fs);
              end;

            finish_children; { variant }
          end;


        finish_children; { variant part }

        finish_children; { struct }
      end;

    function TDebugInfoDwarf3.dwarf_version: Word;
      begin
        Result:=3;
      end;

    function TDebugInfoDwarf3.symname(sym: tsym): String;
      begin
        Result:=sym.realname;
      end;



{****************************************************************************
****************************************************************************}
    const
      dbg_dwarf2_info : tdbginfo =
         (
           id     : dbg_dwarf2;
           idtxt  : 'DWARF2';
         );

      dbg_dwarf3_info : tdbginfo =
         (
           id     : dbg_dwarf3;
           idtxt  : 'DWARF3';
         );

initialization
  RegisterDebugInfo(dbg_dwarf2_info,TDebugInfoDwarf2);
  RegisterDebugInfo(dbg_dwarf3_info,TDebugInfoDwarf3);
end.