[tcf-dev] Unusual DWARF Information DW_AT_stmt_list + DW_FORM_addr

["Lillieskold, Claes" <claes.lillieskold@xxxxxxxxx>]

Hi,

When debugging ARC with an ELF file compiled with the Metaware Compiler, I found

that TCF considers the DWARF information invalid in this ELF file.

 

The invalid combo is the attribute DW_AT_stmt_list with the form DW_FORM_addr.

It seems like TCF expects attribute DW_AT_stmt_list to have DW_FORM_data* forms.

This is checked in dwarfcache.c:read_object_info(), see line 848 below where dio_ChkData() is called.

Below dwarfcache.c is an extract of ‘readelf –w’ for the ELF file that shows two examples of

DW_AT_stmt_list.

 

So my question is if the DWARF standard strictly forbids non-data FORMS in DW_AT_stmt_list

attributes or if the TCF Dwarf parsing is too restrictive?

 

Thanks,

Claes

 

dwarfcache.c (see line 848):

    837     if (Tag == TAG_compile_unit || Tag == TAG_partial_unit || Tag == TAG

    837 _type_unit) {

    838         CompUnit * Unit = Info->mCompUnit;

    839         switch (Attr) {

    840         case AT_low_pc:

    841             Unit->mTextSection = dio_gFormSection;

    842             break;

    843         case AT_comp_dir:

    844             dio_ChkString(Form);

    845             Unit->mDir = (char *)dio_gFormDataAddr;

    846             break;

    847         case AT_stmt_list:

    848             dio_ChkData(Form);

    849             Unit->mLineInfoOffs = dio_gFormData;

    850             break;

    851         case AT_base_types:

    852             Unit->mBaseTypes = add_comp_unit((ContextAddress)dio_gFormDa    852 ta);

    853             break;

    854         case AT_language:

    855             dio_ChkData(Form);

    856             Unit->mLanguage = (U2_T)dio_gFormData;

    857             break;

    858         }

    859     }

 

readelf –w (see line 9 and line 25):

1 Contents of the .debug_abbrev section:

2

3   Number TAG (0x0)

4    1      DW_TAG_compile_unit    [has children]

5     DW_AT_name         DW_FORM_string

6     DW_AT_comp_dir     DW_FORM_string

7     DW_AT_producer     DW_FORM_string

8     DW_AT_language     DW_FORM_data2

9     DW_AT_stmt_list    DW_FORM_data4

10     DW_AT_low_pc       DW_FORM_addr

11     DW_AT_high_pc      DW_FORM_addr

12     DW_AT_sibling      DW_FORM_ref4

13    2      DW_TAG_subprogram    [no children]

14     DW_AT_external     DW_FORM_flag

15     DW_AT_name         DW_FORM_string

16     DW_AT_low_pc       DW_FORM_addr

17     DW_AT_high_pc      DW_FORM_addr

18    3      DW_TAG_label    [no children]

19     DW_AT_name         DW_FORM_string

20     DW_AT_low_pc       DW_FORM_addr

21   Number TAG (0x2c)

22    1      DW_TAG_compile_unit    [has children]

23     DW_AT_sibling      DW_FORM_ref4

24     DW_AT_name         DW_FORM_string

25     DW_AT_stmt_list    DW_FORM_addr

26     DW_AT_low_pc       DW_FORM_addr

27     DW_AT_high_pc      DW_FORM_addr

28     DW_AT_language     DW_FORM_data1

29     DW_AT_comp_dir     DW_FORM_string

30     DW_AT_producer     DW_FORM_string

31    2      DW_TAG_base_type    [no children]

32     DW_AT_name         DW_FORM_string

33     DW_AT_byte_size    DW_FORM_data1

34     DW_AT_encoding     DW_FORM_data1

 

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