mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-12-01 17:10:11 +00:00
726a802fda
Since ARMv5, the clz instruction allows for efficient implementation of ffs/fls with builtins. Until ARMv7 (with Thumb-2), this instruction is only available in ARM mode. LTO makes it difficult to force specific functions to be in ARM mode, as it is effectively a form of very aggressive inlining. To work around this, fls/ffs are implemented in assembly for ARMv5 and ARMv6 when compiling U-Boot in Thumb mode. Overall, this saves around 75 bytes per call. This code is synced with v5.15 of the Linux kernel. Signed-off-by: Sean Anderson <sean.anderson@seco.com> Reviewed-by: Tom Rini <trini@konsulko.com>
15 lines
364 B
C
15 lines
364 B
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef _ASM_GENERIC_BITOPS_BUILTIN_FFS_H_
|
|
#define _ASM_GENERIC_BITOPS_BUILTIN_FFS_H_
|
|
|
|
/**
|
|
* ffs - find first bit set
|
|
* @x: the word to search
|
|
*
|
|
* This is defined the same way as
|
|
* the libc and compiler builtin ffs routines, therefore
|
|
* differs in spirit from ffz (man ffs).
|
|
*/
|
|
#define ffs(x) __builtin_ffs(x)
|
|
|
|
#endif
|