llvm dev - Apr 2013 - [LLVMdev] How to prevent LLVM from emitting R_X86_64_32 ELF relocations?

ELF module of type ET_REL (Relocable module), generated by LLVM, always 
has some R_X86_64_32 in debug information sections.
This happens with Reloc models Default,Static,PIC_ and with CodeModel 
set to Large.

What is the way to prevent R_X86_64_32 ELF from ever appearing in ELF?

Yuri

On 04/27/2013 08:07 AM, Yuri wrote:
> ELF module of type ET_REL (Relocable module), generated by LLVM, 
> always has some R_X86_64_32 in debug information sections.
> This happens with Reloc models Default,Static,PIC_ and with CodeModel 
> set to Large.
>
> What is the way to prevent R_X86_64_32 ELF from ever appearing in ELF?
Hi Yuri,

   why do you want to prevent R_X86_64_32 generation? for 32bit dwarf, I 
think generation of R_X86_64_32 is reasonable.

   you can check http://dwarfstd.org/doc/DWARF4.pdf.

>
> Yuri
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-- 
Regards,
Jiong. Wang
Tilera Corporation.

On 04/26/2013 19:50, Jiong Wang wrote:
>
>
>   why do you want to prevent R_X86_64_32 generation? for 32bit dwarf, 
> I think generation of R_X86_64_32 is reasonable.
>
>   you can check http://dwarfstd.org/doc/DWARF4.pdf. 
Because R_X86_64_32 elements are 4-byte addresses and can't be relocated 
for the 64-bit address space over 32-bit limit.

Dwarf2 actually allows for both 32bit and 64-bit relocations. The 
document, mentioned by you, explains this in section 7.5.1.1 on page 
143. If the first DWORD of .debug_info section is 0xffffffff, then this 
is 64-bit format.

But LLVM for some reason always chooses DWARF 32-bit format. This is why 
I asked the question. Resulting relocable 64-bit objects can't be loaded 
into addresses that are over 32-bit limit.

Yuri