[llvm-dev] Debug symbols are missing in elf

[David Blaikie via llvm-dev]

Yeah, not sure - you mention the linker produces errors, but the errors you
showed looked like objdump errors? Were those errors from trying to dump
the linked executable, and not errors that were produced by the linker
itself?

But yeah, don't really know what's happening there. Might be you need to
debug the linker & see what it's reading/being confused by.

On Sat, Apr 18, 2020 at 10:05 AM Nagaraju Mekala <
nagaraju.mekala87 at gmail.com> wrote:

>
>
> On Saturday, April 18, 2020, David Blaikie <dblaikie at gmail.com> wrote:
>
>>
>>
>> On Sat, Apr 18, 2020 at 3:02 AM Nagaraju Mekala via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>>> Hello All,
>>>
>>> I was trying to add Microblaze  target to LLVM backend. I was able to
>>> generate object file with relocations. and debug symbols.
>>>
>>> When I try to link this object file with microblaze GCC linker I am
>>> getting below errors and debug symbols are missing in it.
>>>
>>> mb-objdump: DWARF error: found dwarf version '15877', this reader only
>>> handles version 2, 3, 4 and 5 information
>>> mb--objdump: DWARF error: found dwarf version '3328', this reader only
>>> handles version 2, 3, 4 and 5 information
>>> mb--objdump: DWARF error: found dwarf version '1280', this reader only
>>> handles version 2, 3, 4 and 5 information
>>>
>>> Any idea when does the above errors will come?
>>> The llvm generated object file has debug symbols,
>>
>>
>> When you say "has debug symbols" what do you mean? What tools have you
>> used to observe these symbols/information?
>>
>
> I have observed the debug sections with mb-objdump with -xSD flag
> (binutils based objdump which we use it with mb-gcc compiler). Even with
> readelf I was able to get the dwarf sections.
> Attached is the dwarf dump generated with readelf --debug-dump
> helloworld.o command..
>
> where as elf doesn't have.
>>>
>>
>> I take it you mean the linked executable? (the "ELF" file format is used
>> for both the object files and the linked executable)
>>
>>
>>
>  Sorry for the confusion. You are correct, I meant the linked executable.
>
> I tried modifying MCTarget layer a lot but not able to find the root-cause.
>>> Any clue is much appreciated.
>>>
>>> ex:
>>> hello.c
>>> int main()
>>> {
>>>     printf("Hello World\n\r");
>>>     printf("Successfully ran Hello World application");
>>>     return 0;
>>> }
>>>
>>> hello.o objdump:
>>> int main()
>>> {
>>>    0:   10a00000        addk    r5, r0, r0
>>>    4:   f8a1002c        swi     r5, r1, 44
>>>
>>>     printf("Hello World\n\r");
>>>    8:   b0000000        imm     0
>>>                         8: R_MICROBLAZE_64      .rodata.str1.1
>>>    c:   a0c00000        ori     r6, r0, 0
>>>   10:   f8a10028        swi     r5, r1, 40
>>>   14:   b0000000        imm     0
>>>                         14: R_MICROBLAZE_64_PCREL       printf
>>>   18:   b9f40000        brlid   r15, 0
>>>   1c:   10a60000        addk    r5, r6, r0
>>>     printf("Successfully ran Hello World application");
>>>   20:   b0000000        imm     0
>>>                         20: R_MICROBLAZE_64     .rodata.str1.1+0xe
>>>   24:   a0a00000        ori     r5, r0, 0
>>>   28:   b0000000        imm     0
>>>                         28: R_MICROBLAZE_64_PCREL       printf
>>>   2c:   b9f40000        brlid   r15, 0
>>>   30:   f8610024        swi     r3, r1, 36
>>>     return 0;
>>>   34:   e8a10028        lwi     r5, r1, 40
>>>   38:   f8610020        swi     r3, r1, 32
>>>   3c:   10650000        addk    r3, r5, r0
>>>   40:   b60f0008        rtsd    r15, 8
>>>   44:   80000000        or      r0, r0, r0
>>>   ....
>>>   ...
>>>
>>> hello.elf objdump
>>> 8000021c <main>:
>>> 8000021c:       10a00000        addk    r5, r0, r0
>>> 80000220:       f8a1002c        swi     r5, r1, 44
>>> 80000224:       b0008000        imm     -32768
>>> 80000228:       a0c0f418        ori     r6, r0, -3048
>>> 8000022c:       f8a10028        swi     r5, r1, 40
>>> 80000230:       b9f400ec        brlid   r15, 236
>>> 80000234:       10a60000        addk    r5, r6, r0
>>> 80000238:       b0008000        imm     -32768
>>> 8000023c:       a0a0f426        ori     r5, r0, -3034
>>> 80000240:       b9f400dc        brlid   r15, 220
>>> 80000244:       f8610024        swi     r3, r1, 36
>>> 80000248:       e8a10028        lwi     r5, r1, 40
>>> 8000024c:       f8610020        swi     r3, r1, 32
>>> 80000250:       10650000        addk    r3, r5, r0
>>> 80000254:       b60f0008        rtsd    r15, 8
>>> 80000258:       80000000        or      r0, r0, r0
>>>
>>> Thanks in Advance,
>>> Nagaraju
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> llvm-dev at lists.llvm.org
>>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>
>>
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