Re: [PATCH] PR ld/16746: Don't issue a warning for reference in LTO IR

["H.J. Lu" <hjl.tools@gmail.com>]

On Tue, Mar 25, 2014 at 4:52 PM, Alan Modra <amodra@gmail.com> wrote:
> On Tue, Mar 25, 2014 at 03:50:05PM -0700, H.J. Lu wrote:
>> On Tue, Mar 25, 2014 at 3:39 PM, Alan Modra <amodra@gmail.com> wrote:
>> > On Tue, Mar 25, 2014 at 01:39:52PM -0700, H.J. Lu wrote:
>> >>       case WARNC:
>> >> -       /* Issue a warning and cycle.  */
>> >> -       if (h->u.i.warning != NULL)
>> >> +       /* Issue a warning and cycle.  Don't issue a warning for
>> >> +          reference in LTO IR which may be removed by LTO later. */
>> >> +       if (h->u.i.warning != NULL
>> >> +           && (abfd->flags & BFD_PLUGIN) == 0)
>> >
>> > So here you're handling references in LTO IR for warning symbols
>> > defined in real object files or other LTO IR files..
>>
>> Yes.
>>
>> >>       case WARN:
>> >> +       /* Don't issue a warning for reference in LTO IR which may be
>> >> +          removed by LTO later.  Make a warning symbol instead.  */
>> >> +       if ((hash_entry_bfd (h)->flags & BFD_PLUGIN) != 0)
>> >> +         goto mwarn;
>> >> +
>> >
>> > And here you have the case where the new symbol is a warning symbol,
>> > in either LTO IR or real object files, but the reference was in an LTO
>> > IR file.
>>
>> Yes.
>>
>> > What about the CWARN case, where you already have a definition that
>> > may have been referenced, and the new symbol is a warning symbol?
>> > You'll need to test h->non_ir_ref I think.
>>
>> It is:
>>
>> https://sourceware.org/bugzilla/show_bug.cgi?id=12760
>
> That's a different issue, isn't it?  I'm talking about the sequence
> 1a) symbol referenced,
> 2a) symbol defined,
> 3a) warning symbol defined.
> or
> 1b) symbol defined,
> 2b) symbol referenced,
> 3b) warning symbol defined.
>
> If (1a) or (2b) is an IR reference then we don't want to warn.

The symbol is referenced and used even if it has been inlined.
Testing h->non_ir_ref isn't sufficient.  We also want to know
if it is used in LTO.

-- 
H.J.