mirror of
https://github.com/torvalds/linux.git
synced 2024-12-12 06:02:38 +00:00
586eaebea5
find_bit would also benefit from small_const_nbits() optimizations. The detailed comment is provided by Rasmus Villemoes. Link: https://lkml.kernel.org/r/20210401003153.97325-6-yury.norov@gmail.com Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Yury Norov <yury.norov@gmail.com> Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com> Cc: Alexey Klimov <aklimov@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: David Sterba <dsterba@suse.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Jianpeng Ma <jianpeng.ma@intel.com> Cc: Joe Perches <joe@perches.com> Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Rich Felker <dalias@libc.org> Cc: Stefano Brivio <sbrivio@redhat.com> Cc: Wei Yang <richard.weiyang@linux.alibaba.com> Cc: Wolfram Sang <wsa+renesas@sang-engineering.com> Cc: Yoshinori Sato <ysato@users.osdn.me> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
39 lines
1.2 KiB
C
39 lines
1.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef __ASM_GENERIC_BITS_PER_LONG
|
|
#define __ASM_GENERIC_BITS_PER_LONG
|
|
|
|
#include <uapi/asm-generic/bitsperlong.h>
|
|
|
|
|
|
#ifdef CONFIG_64BIT
|
|
#define BITS_PER_LONG 64
|
|
#else
|
|
#define BITS_PER_LONG 32
|
|
#endif /* CONFIG_64BIT */
|
|
|
|
/*
|
|
* FIXME: The check currently breaks x86-64 build, so it's
|
|
* temporarily disabled. Please fix x86-64 and reenable
|
|
*/
|
|
#if 0 && BITS_PER_LONG != __BITS_PER_LONG
|
|
#error Inconsistent word size. Check asm/bitsperlong.h
|
|
#endif
|
|
|
|
#ifndef BITS_PER_LONG_LONG
|
|
#define BITS_PER_LONG_LONG 64
|
|
#endif
|
|
|
|
/*
|
|
* small_const_nbits(n) is true precisely when it is known at compile-time
|
|
* that BITMAP_SIZE(n) is 1, i.e. 1 <= n <= BITS_PER_LONG. This allows
|
|
* various bit/bitmap APIs to provide a fast inline implementation. Bitmaps
|
|
* of size 0 are very rare, and a compile-time-known-size 0 is most likely
|
|
* a sign of error. They will be handled correctly by the bit/bitmap APIs,
|
|
* but using the out-of-line functions, so that the inline implementations
|
|
* can unconditionally dereference the pointer(s).
|
|
*/
|
|
#define small_const_nbits(nbits) \
|
|
(__builtin_constant_p(nbits) && (nbits) <= BITS_PER_LONG && (nbits) > 0)
|
|
|
|
#endif /* __ASM_GENERIC_BITS_PER_LONG */
|