Re: Issue with debug symbols with garbage collector

[Michael Eager <eager@eagercon.com>]

On 4/21/22 00:27, Nagaraju Mekala via Gcc-help wrote:
>>   I meant instead of pointing to _start, Debug symbols were pointing to
> microblaze_register_handler.

Both symbols are at location 0.

> I have attached the elf, where we cannot find any symbols related to
> microblaze_register_handler function but the debug_loc is somehow showing
> up at _start address.

There are two places where symbols are defined.  One is in the ELF
symbol table:

    $ readelf -s kc705_hello.elf | grep " _start"
    277: 0000000000000000     0 FUNC    GLOBAL DEFAULT    1 _start

The other in the DWARF debug_info section:

    $ readelf -w kc705_hello.elf
<1><383>: Abbrev Number: 15 (DW_TAG_subprogram)
     <384>   DW_AT_external    : 1
     <384>   DW_AT_name        : (indirect string, offset: 0xf783): 
microblaze_register_handler
     <388>   DW_AT_decl_file   : 1
     <389>   DW_AT_decl_line   : 86
     <38a>   DW_AT_decl_column : 6
     <38b>   DW_AT_prototyped  : 1
     <38b>   DW_AT_low_pc      : 0x0              <=== Fun is at 0x0000
     <393>   DW_AT_high_pc     : 0x18
     <39b>   DW_AT_frame_base  : 1 byte block: 9c 
(DW_OP_call_frame_cfa)
     <39d>   DW_AT_call_all_calls: 1
     <39d>   DW_AT_sibling     : <0x3bc>

GDB uses the DWARF information before falling back to using the
ELF symbol table.

-- 
Michael Eager