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Optimize hweight32 by using the same technique in hweight64. The proof of this technique can be found in the commit log for f9b4192 ("bitops: hweight() speedup"). The userspace benchmark on x86_32 showed 20% speedup with bitmap_weight() which uses hweight32 to count bits for each unsigned long on 32bit architectures. int main(void) { #define SZ (1024 * 1024 * 512) static DECLARE_BITMAP(bitmap, SZ) = { [0 ... 100] = 1, }; return bitmap_weight(bitmap, SZ); } Signed-off-by: Akinobu Mita <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Cc: Linus Torvalds <[email protected]> LKML-Reference: <[email protected]> [ only x86 sets ARCH_HAS_FAST_MULTIPLIER so we do this via the x86 tree] Signed-off-by: Ingo Molnar <[email protected]>
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