1. 18 5月, 2010 1 次提交
    • H
      x86, hweight: Use a 32-bit popcnt for __arch_hweight32() · c59bd568
      H. Peter Anvin 提交于
      Use a 32-bit popcnt instruction for __arch_hweight32(), even on
      x86-64.  Even though the input register will *usually* be
      zero-extended due to the standard operation of the hardware, it isn't
      necessarily so if the input value was the result of truncating a
      64-bit operation.
      
      Note: the POPCNT32 variant used on x86-64 has a technically
      unnecessary REX prefix to make it five bytes long, the same as a CALL
      instruction, therefore avoiding an unnecessary NOP.
      Reported-by: NLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
      Cc: Borislav Petkov <borislav.petkov@amd.com>
      LKML-Reference: <alpine.LFD.2.00.1005171443060.4195@i5.linux-foundation.org>
      c59bd568
  2. 05 5月, 2010 1 次提交
  3. 07 4月, 2010 5 次提交
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  5. 05 4月, 2010 10 次提交