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Re: dw2gencfi.c DWARF2_FDE_RELOC_SIZE


On Mon, Mar 06, 2017 at 03:59:10AM -0700, Jan Beulich wrote:
> >>> On 06.03.17 at 11:33, <amodra@gmail.com> wrote:
> > @@ -1973,13 +1974,15 @@ output_fde (struct fde_entry *fde, struct cie_entry *cie,
> >      {
> >        bfd_reloc_code_real_type code
> >  	= tc_cfi_reloc_for_encoding (cie->fde_encoding);
> > +      addr_size = DWARF2_FDE_RELOC_SIZE;
> >        if (code != BFD_RELOC_NONE)
> >  	{
> >  	  reloc_howto_type *howto = bfd_reloc_type_lookup (stdoutput, code);
> > -	  char *p = frag_more (4);
> > -	  md_number_to_chars (p, 0, 4);
> > -	  fix_new (frag_now, p - frag_now->fr_literal, 4, fde->start_address,
> > -		   0, howto->pc_relative, code);
> > +	  char *p = frag_more (addr_size);
> > +	  gas_assert (addr_size == howto->bitsize / 8);
> > +	  md_number_to_chars (p, 0, addr_size);
> > +	  fix_new (frag_now, p - frag_now->fr_literal, addr_size,
> > +		   fde->start_address, 0, howto->pc_relative, code);
> >  	}
> 
> So I see you nevertheless decided to clean this up. However, is this
> a good approach? What if a target wants/needs to use different
> relocations for different encodings (which then may also be different
> size)? I would have thought that addr_size needs to be derived from
> the returned reloc type.

It would make even more sense to use
      addr_size = encoding_size (cie->fde_encoding);
deriving both reloc and size from the encoding.

I thought about doing that but got tired of running the testsuite.

-- 
Alan Modra
Australia Development Lab, IBM


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