[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <CAMuHMdUUq0FLmsRPw122My7tOUyRLJxsEKOSFgtfG3ec5OiyKQ@mail.gmail.com>
Date: Tue, 24 Jan 2023 14:07:54 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Randy Dunlap <rdunlap@...radead.org>
Cc: Michael Karcher <kernel@...rcher.dialup.fu-berlin.de>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Linux-sh list <linux-sh@...r.kernel.org>,
Segher Boessenkool <segher@...nel.crashing.org>,
Rich Felker <dalias@...c.org>,
Yoshinori Sato <ysato@...rs.sourceforge.jp>,
John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
Subject: Re: [PATCH v4 1/1] arch/sh: avoid spurious sizeof-pointer-div warning
On Mon, Jan 23, 2023 at 8:40 PM Randy Dunlap <rdunlap@...radead.org> wrote:
> I'm curious how you generated this patch.
> 'patch' complains:
>
> patch: **** malformed patch at line 53: prio_regs, sense_regs, ack_regs) \
>
> (more below)
>
> On 1/23/23 10:48, Michael Karcher wrote:
> > Gcc warns about the pattern sizeof(void*)/sizeof(void), as it looks like
> > the abuse of a pattern to calculate the array size. This pattern appears
> > in the unevaluated part of the ternary operator in _INTC_ARRAY if the
> > parameter is NULL.
> >
> > The replacement uses an alternate approach to return 0 in case of NULL
> > which does not generate the pattern sizeof(void*)/sizeof(void), but still
> > emits the warning if _INTC_ARRAY is called with a nonarray parameter.
> >
> > This patch is required for successful compilation with -Werror enabled.
> >
> > The idea to use _Generic for type distinction is taken from Comment #7
> > in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108483 by Jakub Jelinek
> >
> > Signed-off-by: Michael Karcher <kernel@...rcher.dialup.fu-berlin.de>
> > ---
> > This edition of the mail has the correct "v4" designation in the subject.
> >
> > History:
> > v4:
> > - Put the case distinction into the numerator instead of the denominator
> > - Refactor the case disctinction into a second macro
> > v3:
> > - I had a stern discussion with Thunderbird about not mangling the
> > space characters in my email, and I hope spaces get sent as standard
> > spaces now
> > v2:
> > - improve title and remove mostly redundant first sentence of the
> > description
> > - adjust formatting of the _Generic construction
> >
> > diff --git a/include/linux/sh_intc.h b/include/linux/sh_intc.h
> > index c255273b0281..98d1da0d8e36 100644
> > --- a/include/linux/sh_intc.h
> > +++ b/include/linux/sh_intc.h
> > @@ -97,7 +97,9 @@ struct intc_hw_desc {
>
> That ,9 should be ,10.
Indeed.
Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
Tested-by: Geert Uytterhoeven <geert+renesas@...der.be>
Note that I didn't receive v5 (neither did lore), only Adrian's reply.
> > -#define _INTC_ARRAY(a) a, __same_type(a, NULL) ? 0 : sizeof(a)/sizeof(*a)
> > +#define _INTC_SIZEOF_OR_ZERO(a) (_Generic(a, \
> > + typeof(NULL): 0, \
> > + default: sizeof(a)))
_INTC_SIZEOF_OR_ZERO() might be useful in general.
> > +#define _INTC_ARRAY(a) a, _INTC_SIZEOF_OR_ZERO(a)/sizeof(*a)
> >
> > #define INTC_HW_DESC(vectors, groups, mask_regs, \
> > prio_regs, sense_regs, ack_regs) \
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
Powered by blists - more mailing lists