forked from mirrors/linux
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>
38 lines
1.2 KiB
C
38 lines
1.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ASM_GENERIC_BITS_PER_LONG
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#define __ASM_GENERIC_BITS_PER_LONG
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#include <uapi/asm-generic/bitsperlong.h>
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#ifdef CONFIG_64BIT
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#define BITS_PER_LONG 64
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#else
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#define BITS_PER_LONG 32
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#endif /* CONFIG_64BIT */
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/*
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* FIXME: The check currently breaks x86-64 build, so it's
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* temporarily disabled. Please fix x86-64 and reenable
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*/
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#if 0 && BITS_PER_LONG != __BITS_PER_LONG
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#error Inconsistent word size. Check asm/bitsperlong.h
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#endif
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#ifndef BITS_PER_LONG_LONG
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#define BITS_PER_LONG_LONG 64
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#endif
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/*
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* small_const_nbits(n) is true precisely when it is known at compile-time
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* that BITMAP_SIZE(n) is 1, i.e. 1 <= n <= BITS_PER_LONG. This allows
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* various bit/bitmap APIs to provide a fast inline implementation. Bitmaps
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* of size 0 are very rare, and a compile-time-known-size 0 is most likely
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* a sign of error. They will be handled correctly by the bit/bitmap APIs,
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* but using the out-of-line functions, so that the inline implementations
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* can unconditionally dereference the pointer(s).
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*/
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#define small_const_nbits(nbits) \
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(__builtin_constant_p(nbits) && (nbits) <= BITS_PER_LONG && (nbits) > 0)
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#endif /* __ASM_GENERIC_BITS_PER_LONG */
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