Author: Bruce Moreland
Date: 15:26:44 12/01/98
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On December 01, 1998 at 18:02:47, Bruce Moreland wrote: > >On November 30, 1998 at 12:01:05, Tom Kerrigan wrote: > >>This is all fine and good for larger arrays that you don't access a lot, but if >>you're talking about your representation of the board, >> >>int chess_board[64]; >> >>will be a serious win over >> >>char chess_board[64]; > >I don't know why you are saying this in the face of at least two people saying >that they tried this exact thing and it was slow. > >On an Intel machine you have to do an extra instruction to read a char into EAX, >unless you use movzx or movsx, which suck. > >On an Alpha you have to deal with the alpha (21164) not even having an >instruction that will read a byte. > >These are reasons why I intuit that it might go slower, but if I used this data >structure I would surely test it and know for sure. > >I think that discussions of which implementation will go faster, that are based >upon predicted instruction timing or cache behavior, are almost always useless. I realized about fifteen minutes of lag ago that I am arguing the opposite side of this argument than I'd intended to. I think that this doesn't matter very much. This all has to be solvable with experiments. If there isn't an easily measured difference, then there is no practical difference, so why conjecture about this, it's better just to do the experiment. bruce
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