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

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Message-ID: <YUishGbHeaDMJDj+@archlinux-ax161>
Date:   Mon, 20 Sep 2021 08:45:08 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     Paul Menzel <pmenzel@...gen.mpg.de>
Cc:     Nick Desaulniers <ndesaulniers@...gle.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Zhen Lei <thunder.leizhen@...wei.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev
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 <pmenzel@...gen.mpg.de>

Reviewed-by: Nathan Chancellor <nathan@...nel.org>
Tested-by: Nathan Chancellor <nathan@...nel.org>

> ---
> 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
>