[PATCH] ASoC: rsnd: remove unnecessary static in rsnd_ssiu_probe()

[PATCH] ASoC: rsnd: remove unnecessary static in rsnd_ssiu_probe()

[Gustavo A. R. Silva]

Remove unnecessary static on local variable ops.
Such variable is initialized before being used,
on every execution path throughout the function.
The static has no benefit and, removing it reduces
the code size.

This issue was detected using Coccinelle and the following semantic patch:

@bad exists@
position p;
identifier x;
type T;
@@

static T x@p;
...
x = <+...x...+>

@@
identifier x;
expression e;
type T;
position p != bad.p;
@@

-static
 T x@p;
 ... when != x
     when strict
?x = e;

In the following log you can see the difference in the code size. Also,
there is a significant difference in the bss segment. This log is the
output of the size command, before and after the code change:

before:
   text    data     bss     dec     hex filename
   3211     680      64    3955     f73 sound/soc/sh/rcar/ssiu.o

after:
   text    data     bss     dec     hex filename
   3207     592       0    3799     ed7 sound/soc/sh/rcar/ssiu.o

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 sound/soc/sh/rcar/ssiu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/soc/sh/rcar/ssiu.c b/sound/soc/sh/rcar/ssiu.c
index bed2c9c..4d94875 100644
--- a/sound/soc/sh/rcar/ssiu.c
+++ b/sound/soc/sh/rcar/ssiu.c
@@ -250,7 +250,7 @@ int rsnd_ssiu_probe(struct rsnd_priv *priv)
 {
 	struct device *dev = rsnd_priv_to_dev(priv);
 	struct rsnd_ssiu *ssiu;
-	static struct rsnd_mod_ops *ops;
+	struct rsnd_mod_ops *ops;
 	int i, nr, ret;
 
 	/* same number to SSI */
-- 
2.5.0

Re: [PATCH] ASoC: rsnd: remove unnecessary static in rsnd_ssiu_probe()

[Joe Perches]

On Mon, 2017-07-17 at 10:30 -0500, Gustavo A. R. Silva wrote:
> Remove unnecessary static on local variable ops.
> Such variable is initialized before being used,
> on every execution path throughout the function.
> The static has no benefit and, removing it reduces
> the code size.
[]
> In the following log you can see the difference in the code size. Also,
> there is a significant difference in the bss segment. This log is the
> output of the size command, before and after the code change:
> 
> before:
>    text    data     bss     dec     hex filename
>    3211     680      64    3955     f73 sound/soc/sh/rcar/ssiu.o
> 
> after:
>    text    data     bss     dec     hex filename
>    3207     592       0    3799     ed7 sound/soc/sh/rcar/ssiu.o
[]
> diff --git a/sound/soc/sh/rcar/ssiu.c b/sound/soc/sh/rcar/ssiu.c
[]
> @@ -250,7 +250,7 @@ int rsnd_ssiu_probe(struct rsnd_priv *priv)
>  {
>  	struct device *dev = rsnd_priv_to_dev(priv);
>  	struct rsnd_ssiu *ssiu;
> -	static struct rsnd_mod_ops *ops;
> +	struct rsnd_mod_ops *ops;
>  	int i, nr, ret;
>  
>  	/* same number to SSI */

I'm not an sh user anymore, but it's curious to me why
the static removal has such a large impact on data size.

Is this for an allyesconfig with debug symbols?

btw: this does compile for x86 and those sizes seem
     more sensible.

$ size sound/soc/sh/rcar/ssiu.o*   text	   data	    bss	    dec	    hex	filename
   1950	    248	      0	   2198	    896	sound/soc/sh/rcar/ssiu.o.defconfig.new
   1950	    248	      8	   2206	    89e	sound/soc/sh/rcar/ssiu.o.defconfig.old
   2692	    248	      0	   2940	    b7c	sound/soc/sh/rcar/ssiu.o.allyesconfig.new
   2692	    248	      8	   2948	    b84	sound/soc/sh/rcar/ssiu.o.allyesconfig.old