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

[Christophe Leroy]

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 <pmen...@molgen.mpg.de>
---
  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;