Hi, Richard
> "Hu, Jiangping" <hujiangp...@cn.fujitsu.com> writes:
> > Hi,
> >
> > I find there are many "ATTRIBUTE_UNUSED" macros in the function
> parameter lists,
> > but some of the parameters are used in the function bodies in fact. E.g.
> >
> > @@gcc/final.c
> > void
> > output_operand (rtx x, int code ATTRIBUTE_UNUSED)
> > {
> > if (x && GET_CODE (x) == SUBREG)
> > x = alter_subreg (&x, true);
> >
> > /* X must not be a pseudo reg. */
> > if (!targetm.no_register_allocation)
> > gcc_assert (!x || !REG_P (x) || REGNO (x) <
> FIRST_PSEUDO_REGISTER);
> >
> > targetm.asm_out.print_operand (asm_out_file, x, code);
> >
> > if (x == NULL_RTX)
> > return;
> >
> > mark_symbol_refs_as_used (x);
> > }
> >
> > I know there are no compile issues for the code above, and if we read
> the body,
> > it will not cause too much trouble to readers.
>
> Agreed.
>
> > So I don't know if can I make a patch to remove that? If it is approved,
> > can I just firstly change the files I encountered, because I think many
> files
> > may have this situation, it's hard to address all of them in 1 patch.
>
> Yeah, small numbers of changes per patch are better. There's certainly
> no requirement to do everything at once, incremental improvements are
> better.
Understood.
>
> Uses of ATTRIBUTE_UNUSED in code like the above come from cases where
> a target hook (here asm_out.print_operand) was previously a target macro.
> When it was a target macro, there was no requirement for the macro to use
> every parameter, and so the ATTRIBUTE_UNUSEDs were added to suppress
> warnings for the targets that didn't use particular parameters.
>
> Since converting macros to hooks is a mostly mechanical (and boring)
> process, it's natural to miss cases in which an ATTRIBUTE_UNUSED
> is no longer required.
Thanks for detailed explanation.
Regards!
Hujp
>
> FWIW, there will probably still be uses of ATTRIBUTE_UNUSED for values
> that
> are used in macro arguments, and those ATTRIBUTE_UNUSEDs are still needed.
>
> Thanks,
> Richard
>
