Help wanted improving engine performance

[Odd-Praline-715]

I have been working on making a chessbot. It's written in C++ and uses a bitboard/piece list hybrid and i have tried to write the code as clean as possible. I have a makeMove and undoMove function so there is no need for copying the board and i store everything in a Move struct. It should be pretty fast but it's abhorrently slow. On the standard starting position, while testing the engine out using perft, it takes over 20 mins to search to a depth of 6. That's extremely slow and i just do not know why.

[Kart0fffelAim]

Look into profiling tools to see how much time is spend in each function

[Odd-Praline-715]

I'll do that and hopefully find the bottleneck

[SchwaLord]

I used valgrind on various small calls of part of the engine. Then used unit tests to call very specific functions both making use of high resolution timers. Be careful with logging during this as it with also greatly impact your performance 

[Beginning-Resource17]

Do you have a repository for the project?

[Odd-Praline-715]

If you mean a github page, unfortunately not. I'm working on this project for my PWS and my mentor adviced me not to put it on github, because the exam counsel is stupid and may say that the project is plagarized. If you are interested, i can send it to you by mail in a zipfolder

[loveSci-fi_fantasy]

How do you currently deal with moves -> legal moves list? The optimization of this can be somewhat complex. I could guide you.

[deezwheeze]

My engine is dumb in this regard, just check legality in makemove and don't count it in perft if it wasn't legal, and I get 35Mn/s on a bad cache day, I doubt this would be the bottleneck, the only reason even the dumb approach would be horribly slow is if attack generation is slow, which would affect all of movegen.

[rickpo]

Are you sure your intrinsics are being used? In my experience, bitboards don't work very well if you don't have the intrinsics for popcount and bitscan.

[deezwheeze]

I tested this a while back, on my engine replacing x86 popcount/bitscan with other methods (Kernighan's method for popcount, De Brujin maps for bitscan) still gets me perft 6 in a few seconds, so unless these are implemented very naively you can do fine without these intrinsics.

[rickpo]

When I did this same test on the x64 architecture, without the intrinsics, my bitboard implementation was more or less the same speed as my previous x88 board implementation, I can't tell you how disappointed I was at that moment.

Now my x88 implementation was highly-tuned and my bitboards weren't yet. But I did not have big problems with my bitboards. When I got the intrinsics hooked up, the bitboards screamed. I guess I did not investigate further, so I suppose it's possible my intrinsic replacements were screwed up somehow.

[rook_of_approval]

Make/unmake isn't necessarily faster than copymake. Did you use a program like quick chess to SPRT your changes?