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Subject: Re: Any idea's on how long it takes to learn C++, then create a chessmonster

Author: David Hanley

Date: 16:49:19 12/10/01

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On December 10, 2001 at 19:31:10, Gareth McCaughan wrote:

>On December 10, 2001 at 18:27:39, David Hanley wrote:
>
>> I've actually used both acl 4.3 and the latest CMUCL.  Mostly ACL4.3
>> for the diagnostics, though CMUCL makes considerably faster code.
>
>Its "notes" are also very helpful once you get to the stage of
>speeding up your code. At least for the declaration-insertion
>part.

Yep.  I have written one medium size program with CMUCL before, and i
had to turn off the notes on non-critical parts of the code, because i got
buried in optimization notes.

>
>> I haven't tossed in (speed 3)(safety 0) or any type declarations yet;
>> I'll wait until it plays decently first, and i've reduced the consing.
>
>Is consing really making a big difference to your speed?
>(Hazy memory says this is less likely with ACL than with
>CMUCL; mostly because ACL's GC is very good, though the
>excellence of CMU's code generation may also have something
>to do with it.)

My expereince is that making my code run in-place ( in CMUCL ) and not using
functions like (mapcar) and (remove) and (reduce) resulted in a speedup of
between 50% to 80%, though this depends on your code.  I bet that part of this
is simply improved memory locality.  In a chess program it would probably be
less.  So maybe you're right, and it wouldn't be worth bothering with.  In some
cases it would be a cheap fix, though.  I push captured pieces onto a regulat
list stack, and i expect using an array and a index would give a good speedup
without a lot of code.

Still, i bet i could get to 2000+ just by putting in the right hueristics, and
leaving the "easy" things alone.   I think that approach is more interesting.

dave



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