Question about one offst check in x86-64 bfd code

[Jiong Wang <jiong dot wang at arm dot com>]

Hi HJ,

  I see you added the initial IFUNC support for x86-64, I have one
  question about the following code:

  at the function "elf_x86_64_relocate_section:"

  inside IFUNC handling code:

  /* Since STT_GNU_IFUNC symbol must go through PLT, we handle
     it here if it is defined in a non-shared object.  */
  if (h != NULL
      && h->type == STT_GNU_IFUNC
      && h->def_regular)
    {

     ...
     ...
     
     case R_X86_64_GOTPCREL:
     case R_X86_64_GOTPCREL64:
       base_got = htab->elf.sgot;
       off = h->got.offset;

       if (base_got == NULL)
         abort ();

       if (off == (bfd_vma) -1)
         {
           /* We can't use h->got.offset here to save state, or
              even just remember the offset, as finish_dynamic_symbol
              would use that as offset into .got.  */

           if (htab->elf.splt != NULL)
        ...
        ...

  I am not quite understanding what's the meaning of "off == (bfd_vma)
  -1", in what situation can "off" be -1? I am just wondering the global
  symbol should always be recorded and thus with a positive offset, at
  least on AArch64.

  Thanks.
  
-- 
Regards,
Jiong