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

[Takashi Sakamoto]

On Nov 28 2017 04:51, Takashi Iwai wrote:
> 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@xxxxxxxxxxxxx>
> > >
> > > 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@xxxxxxxxxxxxx>
> > > ---
> > >    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 :)

Ah, yes. The state of my local build tree is not good to calculate it... 
In fact, the relocatable object decreases its size when built with a 
header package from Ubuntu repository.


Thanks

Takashi Sakamoto