2021-09-16 14:24:06

by Paul Menzel

Subject: [PATCH] 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]>
---
lib/zlib_inflate/inffast.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/lib/zlib_inflate/inffast.c b/lib/zlib_inflate/inffast.c
index f19c4fbe1be7..444ad3c3ccd3 100644
--- a/lib/zlib_inflate/inffast.c
+++ b/lib/zlib_inflate/inffast.c
@@ -254,11 +254,7 @@ 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++ = CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS ? *sfrom++ : get_unaligned16(sfrom++);
while (--loops);
out = (unsigned char *)sout;
from = (unsigned char *)sfrom;
--
2.33.0

2021-09-16 18:56:53

by Nathan Chancellor

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

Hi Paul,

On 9/16/2021 7:22 AM, 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]>
> ---
> lib/zlib_inflate/inffast.c | 6 +-----
> 1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/lib/zlib_inflate/inffast.c b/lib/zlib_inflate/inffast.c
> index f19c4fbe1be7..444ad3c3ccd3 100644
> --- a/lib/zlib_inflate/inffast.c
> +++ b/lib/zlib_inflate/inffast.c
> @@ -254,11 +254,7 @@ 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++ = CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS ? *sfrom++ : get_unaligned16(sfrom++);
> while (--loops);
> out = (unsigned char *)sout;
> from = (unsigned char *)sfrom;
>

Thanks for the patch. This should probably be

IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) ? ...

which matches the rest of the kernel tree, as certain CONFIG_... values
are not guaranteed to always be defined.

Cheers,
Nathan

2021-09-17 12:25:53

by Christophe Leroy

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

Le 16/09/2021 à 16:22, 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 | 6 +-----
> 1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/lib/zlib_inflate/inffast.c b/lib/zlib_inflate/inffast.c
> index f19c4fbe1be7..444ad3c3ccd3 100644
> --- a/lib/zlib_inflate/inffast.c
> +++ b/lib/zlib_inflate/inffast.c
> @@ -254,11 +254,7 @@ 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++ = CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS ? *sfrom++ : get_unaligned16(sfrom++);

You can't do that, CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS is not
something that have value 0 or 1, it is something which is either
defined or not. You have to use IS_ENABLED() macro, so it should become
something like:

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;
>