Re: FW: dwarf2 error(microblaze)

[naga raj <gnuuser dot raj at gmail dot com>]

On Fri, Jun 10, 2011 at 4:41 AM, Michael Eager <eager@eagerm.com> wrote:
> On 06/09/2011 01:47 AM, Nagaraju Mekala wrote:
>
>> ?I have compiled memorytest.c with default options using Gcc-4.6.0 as you
>> suggested.
>>
>> ? DWARF of ?main(),i and location list referenced are:
>>
>> ? <1><47a>: Abbrev Number: 13 (DW_TAG_subprogram)
>> ? ? <47b> ? ?DW_AT_external ? ?: 1
>> ? ? <47c> ? ?DW_AT_name ? ? ? ?: (indirect string, offset: 0xf4): main
>> ? ? <480> ? ?DW_AT_decl_file ? : 1
>> ? ? <481> ? ?DW_AT_decl_line ? : 59
>> ? ? <482> ? ?DW_AT_type ? ? ? ?:<0x390>
>> ? ? <486> ? ?DW_AT_low_pc ? ? ?: 0x3dc
>> ? ? <48a> ? ?DW_AT_high_pc ? ? : 0x490
>> ? ? <48e> ? ?DW_AT_frame_base ?: 0x2c ? ?(location list)
>> ? ? <492> ? ?DW_AT_sibling ? ? :<0x4a3>
>> ?<2><496>: Abbrev Number: 14 (DW_TAG_variable)
>> ? ? <497> ? ?DW_AT_name ? ? ? ?: i
>> ? ? <499> ? ?DW_AT_decl_file ? : 1
>> ? ? <49a> ? ?DW_AT_decl_line ? : 61
>> ? ? <49b> ? ?DW_AT_type ? ? ? ?:<0x390>
>> ? ? <49f> ? ?DW_AT_location ? ?: 2 byte block: 91 78 ? ? (DW_OP_fbreg: -8)
>>
>> Contents of the .debug_loc section:
>>
>> ? ? Offset ? Begin ? ?End ? ? ?Expression
>> ? ? 00000000 000001e4 000001e8 (DW_OP_breg1 (r1): 0)
>> ? ? 00000000 000001e8 000001f4 (DW_OP_breg1 (r1): 36)
>> ? ? 00000000 000001f4 0000048c (DW_OP_breg19 (r19): 36)
>> ? ? 00000000<End of list>
>> ? ? 0000002c 0000048c 00000490 (DW_OP_breg1 (r1): 0)
>> ? ? 0000002c 00000490 0000049c (DW_OP_breg1 (r1): 36)
>> ? ? 0000002c 0000049c 00000570 (DW_OP_breg19 (r19): 36)
>> ? ? 0000002c<End of list>
>>
>>
>> ? ?According to my observation .debug_loc at 0000002c Begin location
>> should be 000003dc for main but it is 0000048c is this correct??
>
> Yes.
>
> If you have compiled with -g -O0, the first few instructions for main
> should be something like this to set up r19 as the frame pointer:
>
> 000003dc <main>:
> ?3dc: ? 3021ffe0 ? ? ? ?addik ? r1, r1, -32
> ?3e0: ? f9e10000 ? ? ? ?swi ? ? r15, r1, 0
> ?3e4: ? fa61001c ? ? ? ?swi ? ? r19, r1, 28
> ?3e8: ? 12610000 ? ? ? ?addk ? ?r19, r1, r0
>
> You can verify this with mb-objdump -d.
>
> The assembly code for main should look something like this:
>
> ? ? ? .globl ?main
> $LFB1:
> $LM3:
> ? ? ? ?.ent ? ?main
> ? ? ? ?.type ? main, @function
> main:
> ? ? ? ?.frame ?r19,32,r15 ? ? ? ? ? ? ?# vars= 0, regs= 1, args= 24
> ? ? ? ?.mask ? 0x00088000
>
> ? ? ? ?addik ? r1,r1,-32
> $LCFI3:
> ? ? ? ?swi ? ? r15,r1,0
> $LCFI4:
> ? ? ? ?swi ? ? r19,r1,28
> $LCFI5:
> ? ? ? ?addk ? ?r19,r1,r0
> $LCFI6:
>
> The second entry in .debug_loc should start with this:
>
> $LLST1:
> ? ? ? ?.4byte ?$LFB1-$Ltext0
> ? ? ? ?.4byte ?$LCFI3-$Ltext0
> ? ? ? ?.2byte ?0x2
> ? ? ? ?.byte ? 0x71
>

Investigating the same issue further. I found that issue is in linker.

  My issue is that, after compiler generates assembly instructions,
  linker is relaxing few of the instruction and up to this part it is fine.
  But my linker is not decreasing relaxed instructions space as a
result debug_loc locations in the dwarf2 debugging information is
displaying  the address ranges that are generated by
compiler(including relaxed instruction spaces).
  So due to this my debugging information is getting corrupted with
wrong addresses.

  I know this is a known issue in linker relaxation, but as a newbie
to binutils I could not figure it out where to change in my code.

  I am using Xilinx Microblaze target with Binutils version 2.21.

 Please help in resolving this issue. Please point me to any material
or existing port(patch).


Thanks,
Nagaraju