[arm] branches to weak symbols

[Daniel Jacobowitz]

On Thu, Apr 29, 2010 at 03:45:24PM +0100, Nick Clifton wrote:
> Hi Nathan,
> 
> >This patch fixes some arm cases where the assembler did not consider
> >that a weakly defined symbol might be overridden in the final link.
> 
> >2010-04-28  Nathan Sidwell  <nathan@codesourcery.com>
> >
> >	* write.c (fixup_segment): Do not assume we know the section a
> >	defined weak symbol is in.
> >	* config/tc-arm.c (relax_adr, relax_branch, md_apply_fix): Treat
> >	weak symbols as not known to be in the same section, even if they
> >	are defined.
> >
> >	testsuite/
> >	* gas/arm/weakdef-1.s: New.
> >	* gas/arm/weakdef-1.d: New.
> >	* gas/arm/weakdef-2.s: New.
> >	* gas/arm/weakdef-2.d: New.
> >	* gas/arm/weakdef-2.l: New.
> 
> Approved and applied.  Note - I made one small change which was to
> disable the new tests for non-ELF targeted ARM toolchains.

I have to agree with Alan that the write.c change is not correct
(specifically, I think it will not catch the other cases checked for
in generic_force_reloc, like IFUNC).  The current behavior is
deliberate:

  /* Resolve these relocations even if the symbol is extern or weak.  */
  if (fixp->fx_r_type == BFD_RELOC_ARM_IMMEDIATE
      || fixp->fx_r_type == BFD_RELOC_ARM_OFFSET_IMM
      || fixp->fx_r_type == BFD_RELOC_ARM_ADRL_IMMEDIATE
      || fixp->fx_r_type == BFD_RELOC_ARM_T32_ADD_IMM
      || fixp->fx_r_type == BFD_RELOC_ARM_T32_IMMEDIATE
      || fixp->fx_r_type == BFD_RELOC_ARM_T32_IMM12
      || fixp->fx_r_type == BFD_RELOC_ARM_T32_ADD_PC12)
    return 0;

I believe it's that last relocation type in this case?

This block was originally added for those first three relocations.  I
don't know why; it was part of the big Thumb-2 commit.  Paul extended
the list when implementing some relaxation.

Paul, do you know what this change was for?

-- 
Daniel Jacobowitz
CodeSourcery