lib/zlib_inflate/inffast: Check config in C to avoid unused function warning

Started by Paul Menzel on Sep 20, 2021 · 3 messages from 2 authors · Last reply Sep 21, 2021

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STALE1874d

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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

Nathan Chancellor replied to Paul Menzel Sep 20, 15:45 #

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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

Paul Menzel replied to Nathan Chancellor Sep 21, 10:11 #

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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 {

10 more quoted lines

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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