gpio: 104-dio-48e: make array 'ports' static, shrinks object size

Message ID 20180405120012.7671-1-colin.king@canonical.com
State New
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  • gpio: 104-dio-48e: make array 'ports' static, shrinks object size
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Commit Message

Colin King April 5, 2018, noon
From: Colin Ian King <colin.king@canonical.com>

Don't populate the const read-only array 'ports' on the stack but instead
make it static. Makes the object code smaller by over 100 buytes:

Before:
   text	   data	    bss	    dec	    hex	filename
  10959	   4952	    832	  16743	   4167	drivers/gpio/gpio-104-dio-48e.o

After:
   text	   data	    bss	    dec	    hex	filename
  10790	   5008	    832	  16630	   40f6	drivers/gpio/gpio-104-dio-48e.o

(gcc version 7.2.0 x86_64)

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/gpio/gpio-104-dio-48e.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

William Breathitt Gray April 5, 2018, 12:19 p.m. | #1
On Thu, Apr 05, 2018 at 01:00:12PM +0100, Colin King wrote:
>From: Colin Ian King <colin.king@canonical.com>
>
>Don't populate the const read-only array 'ports' on the stack but instead
>make it static. Makes the object code smaller by over 100 buytes:
>
>Before:
>   text	   data	    bss	    dec	    hex	filename
>  10959	   4952	    832	  16743	   4167	drivers/gpio/gpio-104-dio-48e.o
>
>After:
>   text	   data	    bss	    dec	    hex	filename
>  10790	   5008	    832	  16630	   40f6	drivers/gpio/gpio-104-dio-48e.o
>
>(gcc version 7.2.0 x86_64)
>
>Signed-off-by: Colin Ian King <colin.king@canonical.com>
>---
> drivers/gpio/gpio-104-dio-48e.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/drivers/gpio/gpio-104-dio-48e.c b/drivers/gpio/gpio-104-dio-48e.c
>index 31e22c93e844..9c4e07fcb74b 100644
>--- a/drivers/gpio/gpio-104-dio-48e.c
>+++ b/drivers/gpio/gpio-104-dio-48e.c
>@@ -188,7 +188,7 @@ static int dio48e_gpio_get_multiple(struct gpio_chip *chip, unsigned long *mask,
> {
> 	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
> 	size_t i;
>-	const size_t ports[] = { 0, 1, 2, 4, 5, 6 };
>+	static const size_t ports[] = { 0, 1, 2, 4, 5, 6 };
> 	const unsigned int gpio_reg_size = 8;
> 	unsigned int bits_offset;
> 	size_t word_index;
>-- 
>2.15.1
>

If this makes gpio-104-dio-48e.o smaller, then it may be worthwhile to
apply similar changes to gpio-104-idi-48.c and gpio-gpio-mm.c which have
similar get_multiple callback implementations.

Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
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Linus Walleij April 26, 2018, 9:06 a.m. | #2
On Thu, Apr 5, 2018 at 2:00 PM, Colin King <colin.king@canonical.com> wrote:

> From: Colin Ian King <colin.king@canonical.com>
>
> Don't populate the const read-only array 'ports' on the stack but instead
> make it static. Makes the object code smaller by over 100 buytes:
>
> Before:
>    text    data     bss     dec     hex filename
>   10959    4952     832   16743    4167 drivers/gpio/gpio-104-dio-48e.o
>
> After:
>    text    data     bss     dec     hex filename
>   10790    5008     832   16630    40f6 drivers/gpio/gpio-104-dio-48e.o
>
> (gcc version 7.2.0 x86_64)
>
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

Patch applied with William's ACK.

Yours,
Linus Walleij
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William Breathitt Gray April 26, 2018, 1:02 p.m. | #3
On Thu, Apr 26, 2018 at 11:06:05AM +0200, Linus Walleij wrote:
>On Thu, Apr 5, 2018 at 2:00 PM, Colin King <colin.king@canonical.com> wrote:
>
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> Don't populate the const read-only array 'ports' on the stack but instead
>> make it static. Makes the object code smaller by over 100 buytes:
>>
>> Before:
>>    text    data     bss     dec     hex filename
>>   10959    4952     832   16743    4167 drivers/gpio/gpio-104-dio-48e.o
>>
>> After:
>>    text    data     bss     dec     hex filename
>>   10790    5008     832   16630    40f6 drivers/gpio/gpio-104-dio-48e.o
>>
>> (gcc version 7.2.0 x86_64)
>>
>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>
>Patch applied with William's ACK.
>
>Yours,
>Linus Walleij

Hi Linus,

A more recent version of this patch including similar changes to
gpio-gpio-mm.c and gpio-104-idi-48.c is located here:
https://lkml.org/lkml/2018/4/18/613

William Breathitt Gray
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Patch

diff --git a/drivers/gpio/gpio-104-dio-48e.c b/drivers/gpio/gpio-104-dio-48e.c
index 31e22c93e844..9c4e07fcb74b 100644
--- a/drivers/gpio/gpio-104-dio-48e.c
+++ b/drivers/gpio/gpio-104-dio-48e.c
@@ -188,7 +188,7 @@  static int dio48e_gpio_get_multiple(struct gpio_chip *chip, unsigned long *mask,
 {
 	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
 	size_t i;
-	const size_t ports[] = { 0, 1, 2, 4, 5, 6 };
+	static const size_t ports[] = { 0, 1, 2, 4, 5, 6 };
 	const unsigned int gpio_reg_size = 8;
 	unsigned int bits_offset;
 	size_t word_index;