[Dwarf-Discuss] Decoding DW_FORM_block1
Fri Jul 27 14:50:14 GMT 2012
On Fri, 2012-07-27 at 19:32 +0530, Arun KS wrote:
> On Fri, Jul 27, 2012 at 6:31 PM, Mark Wielaard <mjw at redhat.com> wrote:
> > On Fri, 2012-07-27 at 15:14 +0530, Arun KS wrote:
> [ 31] member
> name "vinayak_i"
> decl_file 2
> decl_line 2
> type [ 4e]
> data_member_location [ 0] plus_uconst 0
> <Arun>Things were fine till this point,
> [ 3f] member
> name "vinayak_u"
> decl_file 2
> decl_line 3
> type [ 55]
> data_member_location [ 0] plus_uconst 4
Note that eu-readelf --debug-dump=info doesn't show you the abbrev
numbers. Most likely is that both members use the same abbrev number.
> .debug_abbrev follows:
> [ 2] offset: 19, children: yes, tag: structure_type
> attr: name, form: strp, offset: 0x13
> attr: byte_size, form: data1, offset: 0x15
> attr: decl_file, form: data1, offset: 0x17
> attr: decl_line, form: data1, offset: 0x19
> attr: sibling, form: ref4, offset: 0x1b
> [ 3] offset: 34, children: no, tag: member
> attr: name, form: strp, offset: 0x22
> attr: decl_file, form: data1, offset: 0x24
> attr: decl_line, form: data1, offset: 0x26
> attr: type, form: ref4, offset: 0x28
> attr: data_member_location, form: block1, offset: 0x2a
> >>>>>>Why no entry in .debug_abbrev for second member named "vinayak_u"?
> .debug_abbrev is directly going to base_type
The DIE tree in the .debug_info points to the abbrevs that describe
them. Most likely both point to  here. See "7.5.2 Debugging
Information Entry" in the DWARF4 spec.
You might want to use a library like libdw from elfutils or libdwarf to
parse DWARF if a tool like eu-readelf doesn't give you the information
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