Author: Landon Rabern
Date: 12:22:41 12/09/00
Go up one level in this thread
On December 08, 2000 at 05:57:37, Vincent Diepeveen wrote: >On December 07, 2000 at 15:20:02, Roy Eassa wrote: > >>But what impact, if any, does floating point have on such chess apps as Crafty, >>Chess Tiger, Fritz, Junior, Hiarcs, Shredder, et. al.? (E.g., which would help >>them more: a 50% boost in integer speed only, or a 200% boost in floating speed >>only?) > >First of all you need to be completely assembly to make usage of >floating point. secondly what INSTRUCTIONS from FPU do you plan >to use? > >I guess doing everything in FPU in C would slow down a >program 4 times or so? > >Just keeping hashing in the FPU casted to MMX is of course a >possibility. That would be the only possible usage of MMX/FPU as >far as i can see. > >But does 0.5% speedup makeup for rewriting your entire program? >Other instructions don't make sense simply from MMX. Some values >can sure be stored there, but that's basically interesting >for assembly programs, NOT for C compiled programs. I actually got about a 30% speedup using MMX registers and instructions for my move generation, and I did not have to rewrite much. > >I am writing in C, because i want to be able to easily read my >code. I could already speedup my code 5 to 10% by rewriting some >32 bits datastructures to 8 bits, i get again huge casting problems >etcetera etcetera, but i speed it up bigtime. > >But i chose to make my program 32 bits completely to get rid of >all those casting problems and just be busy with the most important: >improving the quality of the program, being busy algorithmically >and being busy with its evaluation, without worrying always about >the casting problems which sure get there if you have 2 mb >of C source code! > >> >>On December 07, 2000 at 15:11:55, Robert Hyatt wrote: >> >>>On December 07, 2000 at 14:53:11, Roy Eassa wrote: >>> >>>>5+ years ago, in another chess computer forum, I recall posting that computer >>>>chess makes essentially no use of floating point arithmetic. I.e., the >>>>performance of the CPU's integer arithmetic was overwhelmingly more important to >>>>its performance running chess software than its floating point performance. >>>> >>>>Is that correct in today's top programs? Was I even correct back then? >>> >>> >>>back then it depended on the architecture. IE Cray was no slouch at FP >>>arithmetic, and in many cases FP was a fast or faster than int math. In >>>today's PC, FP is slower, but with the multiple-pipe superscalar approach, >>>some FP could be beneficial as those operations could be done in parallel >>>with int operations.
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