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Subject: Re: IsiChessMMX without rotated BitBoards...

Author: Gerd Isenberg

Date: 15:09:04 10/14/02

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On October 14, 2002 at 16:01:22, Gian-Carlo Pascutto wrote:

>On October 14, 2002 at 12:46:55, Gerd Isenberg wrote:
>
>>Hi all,
>>
>>as proposed some weeks ago, first conclusions of using Kogge-Stone and dumb7fill
>>slideattack-generation with mmx-registers in IsiChess, which uses legal move
>>generation with a kind of an infinite machine.
>>
>>IsiChessMMX is slightly but considerable faster on Athlon XP (but sucks on P4).
>
>Two questions Gerd:
>

Hi Gian-Carlo,

>1) What was the slowdown after throwing out the rotated bitboards?

About 3% on average in some tactical middlegame positions like BTtest.

>
>2) What is the gain after all changes?

May be the same win after all changes, but in some positions more than 5%.
One interesting thing - when i start both versions of my program, let them
calculate on the same position, both heve the same CPU percentage of 50%.
Surprisingly the MMX-version is four times faster than the rotated lookup
version?!

>
>Looks fascinating, but I'll probably hold off until I get a 64 bit chip.

Good idea, hammer will make it a lot easier. Eight additional 64-bit
GP-registers, 16 128-bit XMM-registers and the eight MMX-registers. High time
for Kogge-Stone and dumb7fill.

See you in Leiden,
Gerd

>
>--
>GCP



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