Author: Georg v. Zimmermann
Date: 09:34:18 03/17/01
Go up one level in this thread
On March 16, 2001 at 23:54:10, Christophe Theron wrote: >On March 16, 2001 at 19:52:30, Tony Werten wrote: > >>On March 15, 2001 at 19:30:13, Olaf Jenkner wrote: >> >>>>>A look at the generated code shows some horrible things: >>>>> >>>>>Example: if(a[i]=x)or(a[i]=y)or(a[i]=z)then ... >>>>> Delphi does not know that it can load the value >>>>> of a[i] in a register only on once. >>>>> >>>>>I think many things could be done better without a great optimization. >>>> >>>>Or change the code to >>>> >>>>tmp:=a[i]; >>>>if (tmp=x) or (tmp=y) or (tmp=z) then ... >>>> >>>>BTW the behavour of the array a[] is different depending if it's a global,local >>>>or dynamic array. So is its speed. Global dynamic is fastest if the size of the >>>>elements is a multiple of 32 bit. >>>> >>>>That's what I mean with you have to know the compiler. >>>> >>>>cheers, >>>>Tony >>>> >>>>> >>>>>OJe >>> >>>Why do I have to program around compiler weaknesses? >>>Perhaps the variable tmp is not hold in a register. >>>What I mean: In simple cases, as shown above, I wish >>>a better behaviour of compilers. I know that there are >>>compilers which are extremely optimizing to minimize >>>RAM accesses or to shrink the code or to minimize the >>>number of clock ticks. All of them I can't see when I >>>look at the generated code of Delphi. It's a pity because >>>I don't know much about C++ and have no experience in it. >> >>I'll have to agree with you that it would be nice if the compiler would see this >>kind of stuff. But remember that it's made to work in general. Sometimes it's >>about speed sometimes about size. ( I would like that switch in Delphi ) >> >>Because you are the one who knows what you want, you have to send the compiler >>in the right direction. Learn some assembly and you'll find you can improve the >>compiler even more because you know what it should do. >> >>But these things are not the most important in chessprogramming, the algoritmes >>you use are. You can try a lot of things in C or Pascal, change them, and when >>you finally decide to stick with it, that's the time you can start to optimize. >> >>Oh, and BTW, if you think your program is too slow, just say you go for >>knowledge rather than speed. >> >>A countryman programmer of me mulptiplied his nps by 7 before showing it on >>screen just to stop people from saying it was very slow. It is * 9. When I found this code in Zzzzzz I had to laugh so loud everyone else in the room thought I'd gone crazy. : === procedure TSearchThread.SynchronizeNodes; begin //psychological warfare MainForm.NodesEdit.Text := IntToStr(9 * Nodes); end; ===
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