Author: Robert Hyatt
Date: 19:13:18 06/08/02
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On June 08, 2002 at 02:06:15, Uri Blass wrote: >On June 08, 2002 at 00:30:13, Robert Hyatt wrote: > >>On June 06, 2002 at 20:54:41, Vincent Diepeveen wrote: >> >>>On June 05, 2002 at 22:01:30, Robert Hyatt wrote: >>> >>>PERHAPS IT IS TIME YOU PROFILE CRAFTY AGAIN. >> >>So the profile from _last week_ was too old for you? I haven't changed one >>line of code since that profile run was done... >> >>remember that I am doing profile-based optimizations so I _must_ profile >>every time I change a line to get the fastest crafty version. > >How do you do a profile based optimizations? >What do you change after changing a line in Crafty? Most compilers do this if you tell them to. IE for the Intel c compiler, I use the -prof_gen option to compile the first time. I then run the program over a variety of positions to produce the profile output. I then re-compile the entire source code with the -prof_use option and the compiler looks at the profile results to notice which branches are predicted well and which are predicted badly, which blocks of code are rarele executed, and so forth. It then uses this to further optimize during the second compile to make the program even faster... > >I never did profile-based optimizations in movei and I have no idea how to do >it. > >I think that it will be productive to see a program before profile-based >optimization and explanation of the changes that were done after profile-based >optimization. The compiler really doesn't "tell you" what it did. It just rearranges the instructions to make them more efficient, after having a profile run to show it what was going on.. > >It does not have to be a chess program and may be something more simple. >Is there a place when I can download some simple programs before and after >profile-based optimizations together with explanation of the exact steps that >were done in the profile-based optimization? > >Uri
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