• Andi Kleen's avatar
    [PATCH] optimize hweight64 for x86_64 · 0136611c
    Andi Kleen authored
    Based on patch from David Rientjes <rientjes@google.com>, but
    changed by AK.
    
    Optimizes the 64-bit hamming weight for x86_64 processors assuming they
    have fast multiplication.  Uses five fewer bitops than the generic
    hweight64.  Benchmark on one EMT64 showed ~25% speedup with 2^24
    consecutive calls.
    
    Define a new ARCH_HAS_FAST_MULTIPLIER that can be set by other
    architectures that can also multiply fast.
    Signed-off-by: default avatarAndi Kleen <ak@suse.de>
    0136611c
bitops.h 9.98 KB