Author: Russell Reagan
Date: 18:04:46 02/02/04
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On February 02, 2004 at 20:06:29, David Rasmussen wrote: >Does the Opteron have firstBit, lastBit and popCount instructions? Or at least >something that makes calculating them easier than on x86-32? > >/David I have the impression that there is no new magic bullet that will make these things any easier or faster on the Opteron (well, faster than their 32-bit counterparts, of course). You might find this post interesting: http://chessprogramming.org/cccsearch/ccc.php?art_id=333679 Basically, the fastest approaches on 32-bit hardware seemed to be the fastest on 64-bit hardware. I think Eugene's bitscan (or some slight variant) is the fastest one written in C/C++, but if you're willing to do assembly, I think Bob has some faster stuff. I think Bob's FirstOne() uses bsrq on the Opteron, IIRC, and he said it was the fastest in real code for Crafty.
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