v1.8.0

🔍 Search

• Improving: LMP (#1129)
• Improving: RFP (#1130, #1133)
• Improving: LMR (#1135)
• NMP, tweak reduction using eval - beta (#1139)
• NMP: Use the right score for TT condition (#1268)
• LMR: reduce more on cutnode (#1233)
• LMR: avoid when being checkmated (#1231)
• LMR: increase pv min moves 2 (#1230)
• History: History_BestScoreBetaMargin 80 -> 60 (#1118)
• History: increase bonus when best score is over beta by some margin (#1110)
• History: increase bonus when static eval is lower than alpha (#1123)
• Save static eval in TT (#1084, #1085)
• Aspiration windows: fail high reduction (#800, #1285)

⌛ Time management

• Add node time management (#1203, #1206)
• Add best move stability (#1211)
• Add score stability (#1223)
• Soft limit <= hard limit (#1210)

⚡ Speedups

• Move to .NET 9 (#1108)
• Don't attempt continuation history on root moves (#1065)
• Use Unsafe.Add for PSQT() (#1153)
• Make TaperedEvaluationTerm fields constant (#1174)
• Make TT (wrapper) a readonly struct (#1200)
• Flatten killer moves array (and stack-allocate it) (#1247)
• Minimal speedup in go UCI command parsing (#1264)

🐛 Bug fixes

• Clear PlyStackEntry shared array on return (#1182)
• Don't allow the search to stop if no best move is found (#1251)
• IDDFS finishes some depths with no moves (#1266)
• Incorrect (too negative) mate scores when being checkmated (#1271)
• Make sure staticEval var always gets initialized as part of the search (#1272)
• Prevent aspiration windows to go outside of [MinEval, MaxEval] after window overflow (#1275)

🟰 Multithreaded search

• Add support for multi-threaded search: basic lazy SMP implementation (#1263)

  Threads #	1	2	4	8
  ELO @ 8+0.08	-	+100.96	+195.65	+263.42
  ELO @ 40+0.4	-	+83.35	+167.44	+220.54
  NPS	1.21 Mnps	2.47 Mnps	4.88 Mnps	10.07 Mnps

  

  More detailed results can be found here.

Non strength-winning changes

• Allow non-power of two Hash sizes, implemented via 'fixed-point multiplication trick' (#1072)
• Improve and standardize nps reporting (#1081)
• Use the total max ply as selfdepth value instead of last search's max ply (#1289)
• Make bench quiet by default, and add verbosebench (#1286)
• Various big refactorings to accommodate multithreaded search (#1147, #1184, #1201, #1262)

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Full Changelog: v1.7.0...v1.8.0