Messages in this thread | | | Subject | Re: [tip:x86/asm] x86, bitops: Change bitops to be native operand size | From | Joe Perches <> | Date | Mon, 11 Nov 2013 18:54:43 -0800 |
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On Mon, 2013-11-11 at 15:34 -0800, H. Peter Anvin wrote: > 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.
Really? I don't think so.
How does the use of signed long for an index where no negative values are possible or the use of a negative int for BIT_MASK make sense?
> x86 has instructions that operate on signed bitindicies.
indices.
> 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.
That doesn't mean x86 is the ideal implementation.
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