[PATCH v2] lib/zlib_inflate/inffast: Check config in C to avoid unused function warning

[PATCH v2] lib/zlib_inflate/inffast: Check config in C to avoid unused function warning

[Paul Menzel]

Building Linux for ppc64le with Ubuntu clang version 12.0.0-3ubuntu1~21.04.1
shows the warning below.

    arch/powerpc/boot/inffast.c:20:1: warning: unused function 'get_unaligned16' [-Wunused-function]
    get_unaligned16(const unsigned short *p)
    ^
    1 warning generated.

Fix it, by moving the check from the preprocessor to C, so the compiler
sees the use.

Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
---
 lib/zlib_inflate/inffast.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/lib/zlib_inflate/inffast.c b/lib/zlib_inflate/inffast.c
index f19c4fbe1be7..fb87a3120f0f 100644
--- a/lib/zlib_inflate/inffast.c
+++ b/lib/zlib_inflate/inffast.c
@@ -254,11 +254,8 @@ void inflate_fast(z_streamp strm, unsigned start)
 			sfrom = (unsigned short *)(from);
 			loops = len >> 1;
 			do
-#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
-			    *sout++ = *sfrom++;
-#else
-			    *sout++ = get_unaligned16(sfrom++);
-#endif
+			    *sout++ = IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) ?
+				*sfrom++ : get_unaligned16(sfrom++);
 			while (--loops);
 			out = (unsigned char *)sout;
 			from = (unsigned char *)sfrom;
-- 
2.33.0

Re: [PATCH v2] lib/zlib_inflate/inffast: Check config in C to avoid unused function warning

[Christophe Leroy]

Le 20/09/2021 à 09:46, Paul Menzel a écrit :
> Building Linux for ppc64le with Ubuntu clang version 12.0.0-3ubuntu1~21.04.1
> shows the warning below.
> 
>      arch/powerpc/boot/inffast.c:20:1: warning: unused function 'get_unaligned16' [-Wunused-function]
>      get_unaligned16(const unsigned short *p)
>      ^
>      1 warning generated.
> 
> Fix it, by moving the check from the preprocessor to C, so the compiler
> sees the use.
> 
> Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
> ---
>   lib/zlib_inflate/inffast.c | 7 ++-----
>   1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/lib/zlib_inflate/inffast.c b/lib/zlib_inflate/inffast.c
> index f19c4fbe1be7..fb87a3120f0f 100644
> --- a/lib/zlib_inflate/inffast.c
> +++ b/lib/zlib_inflate/inffast.c
> @@ -254,11 +254,8 @@ void inflate_fast(z_streamp strm, unsigned start)
>   			sfrom = (unsigned short *)(from);
>   			loops = len >> 1;
>   			do
> -#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
> -			    *sout++ = *sfrom++;
> -#else
> -			    *sout++ = get_unaligned16(sfrom++);
> -#endif
> +			    *sout++ = IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) ?
> +				*sfrom++ : get_unaligned16(sfrom++);

I think it would be more readable as

do {
         if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
                 *sout++ = *sfrom++;
         else
                 *sout++ = get_unaligned16(sfrom++);
} while (--loops);



>   			while (--loops);
>   			out = (unsigned char *)sout;
>   			from = (unsigned char *)sfrom;
> 

Re: [PATCH v2] lib/zlib_inflate/inffast: Check config in C to avoid unused function warning

[Paul Menzel]

Dear Christophe,


Thank you for the review.

Am 20.09.21 um 10:36 schrieb Christophe Leroy:
> 
> 
> Le 20/09/2021 à 09:46, Paul Menzel a écrit :
>> Building Linux for ppc64le with Ubuntu clang version 12.0.0-3ubuntu1~21.04.1
>> shows the warning below.
>>
>>      arch/powerpc/boot/inffast.c:20:1: warning: unused function 'get_unaligned16' [-Wunused-function]
>>      get_unaligned16(const unsigned short *p)
>>      ^
>>      1 warning generated.
>>
>> Fix it, by moving the check from the preprocessor to C, so the compiler
>> sees the use.
>>
>> Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
>> ---
>>   lib/zlib_inflate/inffast.c | 7 ++-----
>>   1 file changed, 2 insertions(+), 5 deletions(-)
>>
>> diff --git a/lib/zlib_inflate/inffast.c b/lib/zlib_inflate/inffast.c
>> index f19c4fbe1be7..fb87a3120f0f 100644
>> --- a/lib/zlib_inflate/inffast.c
>> +++ b/lib/zlib_inflate/inffast.c
>> @@ -254,11 +254,8 @@ void inflate_fast(z_streamp strm, unsigned start)
>>               sfrom = (unsigned short *)(from);
>>               loops = len >> 1;
>>               do
>> -#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
>> -                *sout++ = *sfrom++;
>> -#else
>> -                *sout++ = get_unaligned16(sfrom++);
>> -#endif
>> +                *sout++ = 
>> IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) ?
>> +                *sfrom++ : get_unaligned16(sfrom++);
> 
> I think it would be more readable as
> 
> do {
>          if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
>                  *sout++ = *sfrom++;
>          else
>                  *sout++ = get_unaligned16(sfrom++);
> } while (--loops);

I prefer the ternary operator, as it’s less lines, and it’s clear, that 
only the variable assignment is affected by the condition. But as style 
is subjective, I sent v3.

>>               while (--loops);
>>               out = (unsigned char *)sout;
>>               from = (unsigned char *)sfrom;


Kind regards,

Paul