Re: [PATCH v3] lib/zlib_inflate/inffast: Check config in C to avoid unused function warning
From: Paul Menzel
Date: Tue Sep 21 2021 - 06:11:42 EST
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 <pmenzel@xxxxxxxxxxxxx>
Reviewed-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Tested-by: Nathan Chancellor <nathan@xxxxxxxxxx>
---
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