Messages in this thread | | | Date | Mon, 24 Jan 2005 13:20:37 -0800 | From | Matt Mackall <> | Subject | Re: [patch 1/13] Qsort |
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On Sun, Jan 23, 2005 at 05:58:00AM +0100, Felipe Alfaro Solana wrote: > On 23 Jan 2005, at 03:39, Andi Kleen wrote: > > >Felipe Alfaro Solana <lkml@mac.com> writes: > >> > >>AFAIK, XOR is quite expensive on IA32 when compared to simple MOV > >>operatings. Also, since the original patch uses 3 MOVs to perform the > >>swapping, and your version uses 3 XOR operations, I don't see any > >>gains. > > > >Both are one cycle latency for register<->register on all x86 cores > >I've looked at. What makes you think differently? > > I thought XOR was more expensie. Anyways, I still don't see any > advantage in replacing 3 MOVs with 3 XORs.
Again, no temporaries needed.
But I benched it and it was quite a bit slower.
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