linux-kernel - Re: [PATCH] ALSA: drivers: make array 'names' const, reduces object code size

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Date:   Mon, 27 Nov 2017 20:51:20 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     "Takashi Sakamoto" <o-takashi@...amocchi.jp>
Cc:     <alsa-devel@...a-project.org>,
        "Colin King" <colin.king@...onical.com>,
        "Jaroslav Kysela" <perex@...ex.cz>, <wharms@....de>,
        <kernel-janitors@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ALSA: drivers: make array 'names' const, reduces object code size

On Mon, 27 Nov 2017 18:34:17 +0100,
Takashi Sakamoto wrote:
> 
> Hi,
> 
> On Nov 27 2017 21:58, Colin King wrote:
> > From: Colin Ian King <colin.king@...onical.com>
> >
> > Don't populate array 'names' on the stack but instead make them static.
> > Makes the object code smaller by 50 bytes:
> >
> > Before:
> >     text	   data	    bss	    dec	    hex	filename
> >    21237	   9192	   1120	  31549	   7b3d	linux/sound/drivers/dummy.o
> >
> > After:
> >     text	   data	    bss	    dec	    hex	filename
> >    21095	   9280	   1120	  31495	   7b07	linux/sound/drivers/dummy.o
> >
> > (gcc version 7.2.0 x86_64)
> >
> > Signed-off-by: Colin Ian King <colin.king@...onical.com>
> > ---
> >   sound/drivers/dummy.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/sound/drivers/dummy.c b/sound/drivers/dummy.c
> > index 7b2b1f766b00..69db45bc0197 100644
> > --- a/sound/drivers/dummy.c
> > +++ b/sound/drivers/dummy.c
> > @@ -830,7 +830,7 @@ static int snd_dummy_capsrc_put(struct snd_kcontrol *kcontrol, struct snd_ctl_el
> >   static int snd_dummy_iobox_info(struct snd_kcontrol *kcontrol,
> >   				struct snd_ctl_elem_info *info)
> >   {
> > -	const char *const names[] = { "None", "CD Player" };
> > +	static const char *const names[] = { "None", "CD Player" };
> >     	return snd_ctl_enum_info(info, 1, 2, names);
> >   }
> 
> Total size of snd-dummy.ko increases but this patch has an advantage
> to have the symbol in read-only section.

The total size decreases :)


Takashi