Re: [PATCH] wireless: iwlegacy: make const array static to shink object code size Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit

Julia Lawall
2017-09-22T07:23:20Z

On Thu, 21 Sep 2017, Colin King wrote:

> From: Colin Ian King <colin.king@canonical.com>
>
> Don't populate const array ac_to_fifo on the stack in an inlined
> function, instead make it static. Makes the object code smaller
> by over 800 bytes:
>
> text data bss dec hex filename
> 159029 33154 1216 193399 2f377 4965-mac.o
>
> text data bss dec hex filename
> 158122 33250 1216 192588 2f04c 4965-mac.o
>
> (gcc version 7.2.0 x86_64)

Gcc 7 must be much more aggressive about inlining than gcc 4. Here is the
change that I got on this file:

text data bss dec hex filename
- 76346 1494 152 77992 130a8 drivers/net/wireless/intel/iwlegacy/4965-mac.o
+ 76298 1494 152 77944 13078 drivers/net/wireless/intel/iwlegacy/4965-mac.o
decrease of 48

julia

>
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
> drivers/net/wireless/intel/iwlegacy/4965-mac.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/intel/iwlegacy/4965-mac.c b/drivers/net/wireless/intel/iwlegacy/4965-mac.c
> index de9b6522c43f..65eba2c24292 100644
> --- a/drivers/net/wireless/intel/iwlegacy/4965-mac.c
> +++ b/drivers/net/wireless/intel/iwlegacy/4965-mac.c
> @@ -1480,7 +1480,7 @@ il4965_get_ac_from_tid(u16 tid)
> static inline int
> il4965_get_fifo_from_tid(u16 tid)
> {
> - const u8 ac_to_fifo[] = {
> + static const u8 ac_to_fifo[] = {
> IL_TX_FIFO_VO,
> IL_TX_FIFO_VI,
> IL_TX_FIFO_BE,
> --
> 2.14.1
>
> --
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