[llvm-dev] Debug symbols are missing in elf

[David Blaikie via llvm-dev]

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?


> 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)


> 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
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