On 4/21/2024 12:38 AM, Thorsten Blum wrote:
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@xxxxxxxxxx> --- include/asm-generic/bitops/__ffs.h | 4 ++-- include/asm-generic/bitops/__fls.h | 4 ++-- include/asm-generic/bitops/builtin-__ffs.h | 2 +- include/asm-generic/bitops/builtin-__fls.h | 2 +- include/linux/bitops.h | 6 +++--- tools/include/asm-generic/bitops/__ffs.h | 4 ++-- tools/include/asm-generic/bitops/__fls.h | 4 ++-- tools/include/linux/bitops.h | 2 +- 8 files changed, 14 insertions(+), 14 deletions(-)
I don't mind the idea, but in the past I've send some patches trying to align some arch specific implementations with asm-generic ones. Now you are changing only asm-generic implementation and leaving arch specific ones untouched (that's probably why you see no size change on some of them).
For example on x86, there is: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/x86/include/asm/bitops.h?id=ed30a4a51bb196781c8058073ea720133a65596f#n293 and you probably need to check all architectures for those implementations. Thanks, Amadeusz
