Messages in this thread | | | Date | Mon, 11 Nov 2013 15:34:39 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [tip:x86/asm] x86, bitops: Change bitops to be native operand size |
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On 11/10/2013 06:22 PM, Joe Perches wrote: > > Perhaps the current x86 bitops asm code is being conflated > with the ideal implementation? >
Yes, by you.
x86 has instructions that operate on signed bitindicies. It doesn't have instructions that operate on unsigned bitindicies. Unless someone is willing to do the work to prove that shift and mask is actually faster than using the hardware instructions (which I doubt, but it is always a possibility), that's what we have.
-hpa
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