2021-09-20 09:57:28

by Christophe Leroy

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

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 <[email protected]>
> ---
> 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;
>

2021-09-20 13:15:57

by Paul Menzel

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

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 <[email protected]>
>> ---
>>   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