2021-09-20 13:15:56

by Paul Menzel

Subject: [PATCH v3] lib/zlib_inflate/inffast: Check config in C to avoid unused function warning

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]>
---
v2: Use IS_ENABLED
v3: Use if statement over ternary operator as requested by Christophe

lib/zlib_inflate/inffast.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/lib/zlib_inflate/inffast.c b/lib/zlib_inflate/inffast.c
index f19c4fbe1be7..2843f9bb42ac 100644
--- a/lib/zlib_inflate/inffast.c
+++ b/lib/zlib_inflate/inffast.c
@@ -253,13 +253,12 @@ 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
- while (--loops);
+ do {
+ if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
+ *sout++ = *sfrom++;
+ else
+ *sout++ = get_unaligned16(sfrom++);
+ } while (--loops);
out = (unsigned char *)sout;
from = (unsigned char *)sfrom;
} else { /* dist == 1 or dist == 2 */
--
2.33.0

2021-09-21 01:37:10

by Nathan Chancellor

Subject: Re: [PATCH v3] lib/zlib_inflate/inffast: Check config in C to avoid unused function warning

On Mon, Sep 20, 2021 at 10:43:33AM +0200, Paul Menzel wrote:
> 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]>

Reviewed-by: Nathan Chancellor <[email protected]>
Tested-by: Nathan Chancellor <[email protected]>

> ---
> v2: Use IS_ENABLED
> v3: Use if statement over ternary operator as requested by Christophe
>
> lib/zlib_inflate/inffast.c | 13 ++++++-------
> 1 file changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/lib/zlib_inflate/inffast.c b/lib/zlib_inflate/inffast.c
> index f19c4fbe1be7..2843f9bb42ac 100644
> --- a/lib/zlib_inflate/inffast.c
> +++ b/lib/zlib_inflate/inffast.c
> @@ -253,13 +253,12 @@ 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
> - while (--loops);
> + do {
> + if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
> + *sout++ = *sfrom++;
> + else
> + *sout++ = get_unaligned16(sfrom++);
> + } while (--loops);
> out = (unsigned char *)sout;
> from = (unsigned char *)sfrom;
> } else { /* dist == 1 or dist == 2 */
> --
> 2.33.0
>

2021-09-21 10:16:06

by Paul Menzel

Subject: Re: [PATCH v3] lib/zlib_inflate/inffast: Check config in C to avoid unused function warning

Dear Linux folks,


Am 20.09.21 um 17:45 schrieb Nathan Chancellor:
> On Mon, Sep 20, 2021 at 10:43:33AM +0200, Paul Menzel wrote:
>> 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]>
>
> Reviewed-by: Nathan Chancellor <[email protected]>
> Tested-by: Nathan Chancellor <[email protected]>
>
>> ---
>> v2: Use IS_ENABLED
>> v3: Use if statement over ternary operator as requested by Christophe
>>
>> lib/zlib_inflate/inffast.c | 13 ++++++-------
>> 1 file changed, 6 insertions(+), 7 deletions(-)
>>
>> diff --git a/lib/zlib_inflate/inffast.c b/lib/zlib_inflate/inffast.c
>> index f19c4fbe1be7..2843f9bb42ac 100644
>> --- a/lib/zlib_inflate/inffast.c
>> +++ b/lib/zlib_inflate/inffast.c
>> @@ -253,13 +253,12 @@ 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
>> - while (--loops);
>> + do {
>> + if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
>> + *sout++ = *sfrom++;
>> + else
>> + *sout++ = get_unaligned16(sfrom++);
>> + } while (--loops);
>> out = (unsigned char *)sout;
>> from = (unsigned char *)sfrom;
>> } else { /* dist == 1 or dist == 2 */
>> --
>> 2.33.0

Just for the record,

I compared both object files by running `objdump -d`, and the result is
the same.

The binary differed (`vbindiff`), but I guess this is due to the
increased revision (`make bindeb-pkg`).

without a change (Linus’ current master):

0000 0B50: 00 00 00 00 00 00 00 00 1F 01 00 00 36 00 00 00 ........
....6...
^
0000 0B60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ........
........
0000 0B70: 00 00 00 00 00 00 00 00 29 01 00 00 32 00 00 00 ........
)...2...
^

v2 (ternary operator):

0000 0B50: 00 00 00 00 00 00 00 00 1C 01 00 00 36 00 00 00 ........
....6...
0000 0B60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ........
........
0000 0B70: 00 00 00 00 00 00 00 00 26 01 00 00 32 00 00 00 ........
&...2...

v3 (if-else statement):

0000 0B50: 00 00 00 00 00 00 00 00 1E 01 00 00 36 00 00 00 ........
....6...
0000 0B60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ........
........
0000 0B70: 00 00 00 00 00 00 00 00 28 01 00 00 32 00 00 00 ........
(...2...


Kind regards,

Paul