Author: José Carlos
Date: 23:58:48 03/14/01
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On March 15, 2001 at 00:18:44, Pham Minh Tri wrote: >Hi all, > >In MS DOS environment, I have written some pieces of code in assembly to speed >up program and I could double speed by that way. However, when I moved my code >into Windows and VC6.0 compiler, that method of speedup did not work. I have >tried several times and measured that the program with some assembly pieces of >code could be slightly slower than one without them (pure C++, option >optimization: maximize speed). An annoying result, isn’t it? At end I gave up >with some conclusions as following: > >1) My experience of writing and optimisation assembly is 16 bit one, not good >enough for 32 bit with many new instructions. However, I little doubt about this >conclusion because I designed all data structures suitable for 16 bit (I did not >use Bitboard structure), and many 16-bit instructions are not slower than 32 bit >(and some others may be quicker). > >2) MS VC6.0 compiler may do the best for optimisation of speed. It means we >could do very little more only. > >3) Many functions of chess, which we may convert into assembly code, are not >complicated, so that a good compiler as VC6.0 could make optimisation as good as >an expert. People could do better than program in more complicated and graphic >applications. > >4) Because of all above, if I insist, I could get a speedup of 3-5% after a huge >effort. It is much more expensive than speedup by other way. > >Just my thought and experience. Do you get better results or other experiences? >Pham I haven't written assembler pieces in my program, so I cannot say about how much can assembler speed up the program, but I think you should feel happy if the compiler does so good job that you don't need to write assembler code, because this way, you have a more portable and understandable (easy to modify) code. Don't you think? José C.
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