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bitops: Change function return types from long to int

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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>
This commit is contained in:
Thorsten Blum 2024-04-21 00:38:37 +02:00 committed by Arnd Bergmann
parent e67572cd22
commit 9c313ccdfc
No known key found for this signature in database
GPG Key ID: 60AB47FFC9095227
8 changed files with 14 additions and 14 deletions
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4
include/asm-generic/bitops/__ffs.h
View File

@ -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) {

4
include/asm-generic/bitops/__fls.h
View File

@ -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))) {

2
include/asm-generic/bitops/builtin-__ffs.h
View File

@ -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);
}

2
include/asm-generic/bitops/builtin-__fls.h
View File

@ -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);
}

6
include/linux/bitops.h
View File

@ -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;

4
tools/include/asm-generic/bitops/__ffs.h
View File

@ -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) {

4
tools/include/asm-generic/bitops/__fls.h
View File

@ -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))) {

2
tools/include/linux/bitops.h
View File

@ -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);