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

Subsystems: library code, the rest

STALE1815d

3 messages, 2 authors, 2021-09-21 · open the first message on its own page

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

From: Paul Menzel <hidden>
Date: 2021-09-20 08:44:29

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 <redacted>
---
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

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

From: Nathan Chancellor <nathan@kernel.org>
Date: 2021-09-20 15:45:16

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 <redacted>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
quoted hunk
---
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

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

From: Paul Menzel <hidden>
Date: 2021-09-21 10:11:42

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:
quoted
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 <redacted>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
quoted
---
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
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