[PATCH] ld: Properly override the IR definition

[H.J. Lu]

On Tue, Jul 21, 2020 at 6:01 PM Alan Modra <amodra@gmail.com> wrote:
>
> On Tue, Jul 21, 2020 at 06:37:31AM -0700, H.J. Lu wrote:
> > After all LTO symbols have been read, a new definition in real object
> > overrides the previous definition in the IR object.  Before all LTO
> > symbols have been read, a new non-weak definition overrides the weak
> > definition in the IR object.
> >
> > OK for master?
>
> diff --git a/ld/plugin.c b/ld/plugin.c
> index b455af6d67..ff9f00e452 100644
> --- a/ld/plugin.c
> +++ b/ld/plugin.c
> @@ -1433,12 +1433,20 @@ plugin_notice (struct bfd_link_info *info,
>          new value from a real BFD.  Weak symbols are not normally
>          overridden by a new weak definition, and strong symbols
>          will normally cause multiple definition errors.  Avoid
> -        this by making the symbol appear to be undefined.  */
> -      else if (((h->type == bfd_link_hash_defweak
> -                || h->type == bfd_link_hash_defined)
> -               && is_ir_dummy_bfd (sym_bfd = h->u.def.section->owner))
> -              || (h->type == bfd_link_hash_common
> -                  && is_ir_dummy_bfd (sym_bfd = h->u.c.p->section->owner)))
> +        this by making the symbol appear to be undefined.
> +
> +        NB: After all LTO symbols have been read, a new definition in
> +        real object overrides the previous definition in the IR object.
> +        Before all LTO symbols have been read, a new non-weak definition
> +        overrides the weak definition in the IR object.  */
> +      else if ((((h->type == bfd_link_hash_defweak
> +                 || h->type == bfd_link_hash_defined)
> +                && is_ir_dummy_bfd (sym_bfd = h->u.def.section->owner))
> +               || (h->type == bfd_link_hash_common
> +                   && is_ir_dummy_bfd (sym_bfd = h->u.c.p->section->owner)))
> +              && (info->lto_all_symbols_read
> +                  || ((flags & BSF_WEAK) == 0
> +                      && h->type == bfd_link_hash_defweak)))
>         {
>           h->type = bfd_link_hash_undefweak;
>           h->u.undef.abfd = sym_bfd;
>
> Can't this just be the following, since non-weak will override weak
> without any changes to h->type here?
>
>       else if ((((h->type == bfd_link_hash_defweak
>                   || h->type == bfd_link_hash_defined)
>                  && is_ir_dummy_bfd (sym_bfd = h->u.def.section->owner))
>                 || (h->type == bfd_link_hash_common
>                     && is_ir_dummy_bfd (sym_bfd = h->u.c.p->section->owner)))
>                && info->lto_all_symbols_read)
>
> OK with that simplification, if you have tested your patch with a gcc
> regression test.

I am testing this patch with GCC regression test.  I will check it in if there
are no regressions.

Thanks.

-- 
H.J.
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