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Merge branch 'core-hweight-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

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* 'core-hweight-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, hweight: Use a 32-bit popcnt for __arch_hweight32()
  arch, hweight: Fix compilation errors
  x86: Add optimized popcnt variants
  bitops: Optimize hweight() by making use of compile-time evaluation
This commit is contained in:
Linus Torvalds
2010-05-18 09:17:01 -07:00
parent 98f01720cb c59bd56882
commit cb41838bbc
14 changed files with 188 additions and 62 deletions
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30
include/linux/bitops.h
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@@ -10,6 +10,11 @@
#define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
#endif
extern unsigned int __sw_hweight8(unsigned int w);
extern unsigned int __sw_hweight16(unsigned int w);
extern unsigned int __sw_hweight32(unsigned int w);
extern unsigned long __sw_hweight64(__u64 w);
/*
* Include this here because some architectures need generic_ffs/fls in
* scope
@@ -44,31 +49,6 @@ static inline unsigned long hweight_long(unsigned long w)
return sizeof(w) == 4 ? hweight32(w) : hweight64(w);
}
/*
* Clearly slow versions of the hweightN() functions, their benefit is
* of course compile time evaluation of constant arguments.
*/
#define HWEIGHT8(w) \
( BUILD_BUG_ON_ZERO(!__builtin_constant_p(w)) + \
(!!((w) & (1ULL << 0))) + \
(!!((w) & (1ULL << 1))) + \
(!!((w) & (1ULL << 2))) + \
(!!((w) & (1ULL << 3))) + \
(!!((w) & (1ULL << 4))) + \
(!!((w) & (1ULL << 5))) + \
(!!((w) & (1ULL << 6))) + \
(!!((w) & (1ULL << 7))) )
#define HWEIGHT16(w) (HWEIGHT8(w) + HWEIGHT8((w) >> 8))
#define HWEIGHT32(w) (HWEIGHT16(w) + HWEIGHT16((w) >> 16))
#define HWEIGHT64(w) (HWEIGHT32(w) + HWEIGHT32((w) >> 32))
/*
* Type invariant version that simply casts things to the
* largest type.
*/
#define HWEIGHT(w) HWEIGHT64((u64)(w))
/**
* rol32 - rotate a 32-bit value left
* @word: value to rotate