[RFC][PATCH] Check ELF relocs after opening all all input files

[Alan Modra]

On Thu, Apr 28, 2016 at 05:49:57AM -0700, H.J. Lu wrote:
> On Wed, Apr 27, 2016 at 6:11 PM, Alan Modra <amodra@gmail.com> wrote:
> > On Wed, Apr 27, 2016 at 03:24:48PM -0700, H.J. Lu wrote:
> >> bfd_elf_record_link_assignment
> >> is called after check_relocs.  bfd_elf_record_link_assignment sets non_elf,
> >> def_regular and  forced_local.   For PROVIDE, it also updates root.type. They
> >> are needed in reloc_checks.
> >
> > My guess is that symbol twiddling done in before_allocation should be
> > moved to a new ldemul hook called at the start of lang_do_assignments.
> > The idea being to stabilize symbols earlier.
> >
> > The hook would twiddle __ehdr_start and call find_statement_assignment
> > when lang_mark_phase_enum.  Reversing the __ehdr_start twiddle stays
> > in before_allocation.
> >
> 
> I tried this.  But it doesn't work with __start/__stop symbols.  I
> need to know if they are defined and referenced local in check_relocs.
[snip]

> --- a/ld/ldlang.c
> +++ b/ld/ldlang.c
> @@ -6930,6 +6930,8 @@ lang_process (void)
>       collection in order to make sure that all symbol aliases are resolved.  */
>    lang_do_assignments (lang_mark_phase_enum);
>  
> +  ldemul_record_link_assignments (lang_mark_phase_enum);
> +
>    lang_do_memory_regions();
>    expld.phase = lang_first_phase_enum;

You'll need to run ldemul_record_link_assignments before
lang_do_assignments if you want provided symbols to be defined.

I suggest renaming to ldemul_do_assignments and putting
  ldemul_do_assignments (phase);
inside lang_do_assignments just before the call to
lang_do_assignments_1.

-- 
Alan Modra
Australia Development Lab, IBM