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@xxxxxxxxxxxxx>
> > ---
> >   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