bitops: Change function return types from long to int

Change the return types of bitops functions (ffs, fls, and fns) from
long to int. The expected return values are in the range [0, 64], for
which int is sufficient.

Additionally, int aligns well with the return types of the corresponding
__builtin_* functions, potentially reducing overall type conversions.

Many of the existing bitops functions already return an int and don't
need to be changed. The bitops functions in arch/ should be considered
separately.

Adjust some return variables to match the function return types.

With GCC 13 and defconfig, these changes reduced the size of a test
kernel image by 5,432 bytes on arm64 and by 248 bytes on riscv; there
were no changes in size on x86_64, powerpc, or m68k.

Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/include/asm-generic/bitops/__ffs.h b/include/asm-generic/bitops/__ffs.h
index 446fea6dda78b97953d363945a1599712e371b39..2d08c750c8a730057e4d274df495b56973b6b0c3 100644 (file)
--- a/include/asm-generic/bitops/__ffs.h
+++ b/include/asm-generic/bitops/__ffs.h
@@ -10,9 +10,9 @@
  *
  * Undefined if no bit exists, so code should check against 0 first.
  */
-static __always_inline unsigned long generic___ffs(unsigned long word)
+static __always_inline unsigned int generic___ffs(unsigned long word)
 {
-       int num = 0;
+       unsigned int num = 0;
 
 #if BITS_PER_LONG == 64
        if ((word & 0xffffffff) == 0) {

diff --git a/include/asm-generic/bitops/__fls.h b/include/asm-generic/bitops/__fls.h
index 54ccccf96e21eaad9cf4a681d304ad8ac689f371..e974ec932ec189f9d88e3043ac76fe79b7a8568e 100644 (file)
--- a/include/asm-generic/bitops/__fls.h
+++ b/include/asm-generic/bitops/__fls.h
@@ -10,9 +10,9 @@
  *
  * Undefined if no set bit exists, so code should check against 0 first.
  */
-static __always_inline unsigned long generic___fls(unsigned long word)
+static __always_inline unsigned int generic___fls(unsigned long word)
 {
-       int num = BITS_PER_LONG - 1;
+       unsigned int num = BITS_PER_LONG - 1;
 
 #if BITS_PER_LONG == 64
        if (!(word & (~0ul << 32))) {

diff --git a/include/asm-generic/bitops/builtin-__ffs.h b/include/asm-generic/bitops/builtin-__ffs.h
index 87024da44d10c8625113502766f410beaa1f48cd..cf4b3d33bf961e9c37ab329c52ac2e957bbead1d 100644 (file)
--- a/include/asm-generic/bitops/builtin-__ffs.h
+++ b/include/asm-generic/bitops/builtin-__ffs.h
@@ -8,7 +8,7 @@
  *
  * Undefined if no bit exists, so code should check against 0 first.
  */
-static __always_inline unsigned long __ffs(unsigned long word)
+static __always_inline unsigned int __ffs(unsigned long word)
 {
        return __builtin_ctzl(word);
 }

diff --git a/include/asm-generic/bitops/builtin-__fls.h b/include/asm-generic/bitops/builtin-__fls.h
index 43a5aa9afbdb7247f136f13fa2d0a1efcdfe0ebf..6d72fc8a52595304c8c9b41b54ecc790db7cd57a 100644 (file)
--- a/include/asm-generic/bitops/builtin-__fls.h
+++ b/include/asm-generic/bitops/builtin-__fls.h
@@ -8,7 +8,7 @@
  *
  * Undefined if no set bit exists, so code should check against 0 first.
  */
-static __always_inline unsigned long __fls(unsigned long word)
+static __always_inline unsigned int __fls(unsigned long word)
 {
        return (sizeof(word) * 8) - 1 - __builtin_clzl(word);
 }

diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index 2ba557e067fe69d4d96b5472721001e87a6535cc..f60220f119e255471c0bf5284b23c227eb9dc189 100644 (file)
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -200,7 +200,7 @@ static __always_inline __s64 sign_extend64(__u64 value, int index)
        return (__s64)(value << shift) >> shift;
 }
 
-static inline unsigned fls_long(unsigned long l)
+static inline unsigned int fls_long(unsigned long l)
 {
        if (sizeof(l) == 4)
                return fls(l);
@@ -236,7 +236,7 @@ static inline int get_count_order_long(unsigned long l)
  * The result is not defined if no bits are set, so check that @word
  * is non-zero before calling this.
  */
-static inline unsigned long __ffs64(u64 word)
+static inline unsigned int __ffs64(u64 word)
 {
 #if BITS_PER_LONG == 32
        if (((u32)word) == 0UL)
@@ -252,7 +252,7 @@ static inline unsigned long __ffs64(u64 word)
  * @word: The word to search
  * @n: Bit to find
  */
-static inline unsigned long fns(unsigned long word, unsigned int n)
+static inline unsigned int fns(unsigned long word, unsigned int n)
 {
        unsigned int bit;
 

diff --git a/tools/include/asm-generic/bitops/__ffs.h b/tools/include/asm-generic/bitops/__ffs.h
index 9d131051949709e65ae87f1ac156ce52d58ccbbd..2d94c1e9b2f3e1dfe00504051c2974c88e2c8b0e 100644 (file)
--- a/tools/include/asm-generic/bitops/__ffs.h
+++ b/tools/include/asm-generic/bitops/__ffs.h
@@ -11,9 +11,9 @@
  *
  * Undefined if no bit exists, so code should check against 0 first.
  */
-static __always_inline unsigned long __ffs(unsigned long word)
+static __always_inline unsigned int __ffs(unsigned long word)
 {
-       int num = 0;
+       unsigned int num = 0;
 
 #if __BITS_PER_LONG == 64
        if ((word & 0xffffffff) == 0) {

diff --git a/tools/include/asm-generic/bitops/__fls.h b/tools/include/asm-generic/bitops/__fls.h
index 54ccccf96e21eaad9cf4a681d304ad8ac689f371..e974ec932ec189f9d88e3043ac76fe79b7a8568e 100644 (file)
--- a/tools/include/asm-generic/bitops/__fls.h
+++ b/tools/include/asm-generic/bitops/__fls.h
@@ -10,9 +10,9 @@
  *
  * Undefined if no set bit exists, so code should check against 0 first.
  */
-static __always_inline unsigned long generic___fls(unsigned long word)
+static __always_inline unsigned int generic___fls(unsigned long word)
 {
-       int num = BITS_PER_LONG - 1;
+       unsigned int num = BITS_PER_LONG - 1;
 
 #if BITS_PER_LONG == 64
        if (!(word & (~0ul << 32))) {

diff --git a/tools/include/linux/bitops.h b/tools/include/linux/bitops.h
index 7319f6ced10860e3f0c30c599086384a5268740f..8e073a111d2addbeda0bbfe7ef505d0184bfb514 100644 (file)
--- a/tools/include/linux/bitops.h
+++ b/tools/include/linux/bitops.h
@@ -70,7 +70,7 @@ static inline unsigned long hweight_long(unsigned long w)
        return sizeof(w) == 4 ? hweight32(w) : hweight64(w);
 }
 
-static inline unsigned fls_long(unsigned long l)
+static inline unsigned int fls_long(unsigned long l)
 {
        if (sizeof(l) == 4)
                return fls(l);