[PATCH] D30699: [ELF] - Stop producing broken output for R_386_GOT32X relocation.

[H.J. Lu via llvm-commits]

On Thu, Mar 30, 2017 at 3:01 PM, Rafael Espíndola
<rafael.espindola at gmail.com> wrote:
> On 30 March 2017 at 17:59, H.J. Lu <hjl.tools at gmail.com> wrote:
>> On Thu, Mar 30, 2017 at 2:52 PM, Rafael Espíndola
>> <rafael.espindola at gmail.com> wrote:
>>> On 30 March 2017 at 17:45, H.J. Lu <hjl.tools at gmail.com> wrote:
>>>> On Thu, Mar 30, 2017 at 2:40 PM, Rafael Espíndola
>>>> <rafael.espindola at gmail.com> wrote:
>>>>>>> 08048074 <_start>:
>>>>>>>  8048074: c7 c0 74 80 04 08     mov    $0x8048074,%eax
>>>>>>>
>>>>>>> as the GOT entry for _start contains the address of _start.
>>>>>>
>>>>>> Even with trunk I get
>>>>>>
>>>>>> 08048094 <_start>:
>>>>>>  8048094:       a1 fc ff ff ff          mov    0xfffffffc,%eax
>>>>>
>>>>> And I still get -4 with the head of the binutils-2_28-branch branch.
>>>>>
>>>>
>>>> The updated i386 psABI requires to encode "mov _start at GOT, %eax" with
>>>> 0x8b opcode with R_386_GOT32X instead of 0xa1 opcode.
>>>
>>> What about files produced by old assemblers?
>>
>> For the older .o files, G + A - GOT is used.
>
> Which is incorrect?
>
> The current ABI also lists  R_386_GOT32 with the same expression as
> R_386_GOT32X. When is a R_386_GOT32 required to be evaluated as G + A?
>

And it also says 0x8b opcode should be used.  For R_386_GOT32 without
a base register on a1 opcode, it is undefined.


-- 
H.J.