X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=6146bdf6b5ae9ac24f48cb2e3e3ca831bf8f7618;hp=57316d85613b955cc14d3daedaffabc0887bc62f;hb=114ddb789bed2d74d6a786f5da6c9ce63d44de27;hpb=56d5504f6548b69ce6faaa271a8b55f3773db70c diff --git a/src/search.cpp b/src/search.cpp index 57316d85..6146bdf6 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -2,7 +2,7 @@ Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad - Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad + Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -716,7 +716,9 @@ namespace { update_continuation_histories(ss, pos.moved_piece(ttMove), to_sq(ttMove), penalty); } } - return ttValue; + + if (pos.rule50_count() < 90) + return ttValue; } // Step 5. Tablebases probe @@ -806,7 +808,7 @@ namespace { tte->save(posKey, VALUE_NONE, ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval); } - // Step 7. Razoring (~2 Elo) + // Step 7. Razoring (~1 Elo) if ( !rootNode // The required rootNode PV handling is not available in qsearch && depth < 2 && eval <= alpha - RazorMargin) @@ -815,7 +817,7 @@ namespace { improving = (ss-2)->staticEval == VALUE_NONE ? (ss->staticEval >= (ss-4)->staticEval || (ss-4)->staticEval == VALUE_NONE) : ss->staticEval >= (ss-2)->staticEval; - // Step 8. Futility pruning: child node (~30 Elo) + // Step 8. Futility pruning: child node (~50 Elo) if ( !PvNode && depth < 6 && eval - futility_margin(depth, improving) >= beta @@ -825,10 +827,10 @@ namespace { // Step 9. Null move search with verification search (~40 Elo) if ( !PvNode && (ss-1)->currentMove != MOVE_NULL - && (ss-1)->statScore < 23405 + && (ss-1)->statScore < 23397 && eval >= beta && eval >= ss->staticEval - && ss->staticEval >= beta - 32 * depth + 317 - improving * 30 + && ss->staticEval >= beta - 32 * depth + 292 - improving * 30 && !excludedMove && pos.non_pawn_material(us) && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor)) @@ -915,7 +917,7 @@ namespace { } } - // Step 11. Internal iterative deepening (~2 Elo) + // Step 11. Internal iterative deepening (~1 Elo) if (depth >= 7 && !ttMove) { search(pos, ss, alpha, beta, depth - 7, cutNode); @@ -980,7 +982,7 @@ moves_loop: // When in check, search starts from here // Calculate new depth for this move newDepth = depth - 1; - // Step 13. Pruning at shallow depth (~170 Elo) + // Step 13. Pruning at shallow depth (~200 Elo) if ( !rootNode && pos.non_pawn_material(us) && bestValue > VALUE_MATED_IN_MAX_PLY) @@ -1000,7 +1002,7 @@ moves_loop: // When in check, search starts from here && (*contHist[1])[movedPiece][to_sq(move)] < CounterMovePruneThreshold) continue; - // Futility pruning: parent node (~2 Elo) + // Futility pruning: parent node (~5 Elo) if ( lmrDepth < 6 && !inCheck && ss->staticEval + 255 + 182 * lmrDepth <= alpha @@ -1010,17 +1012,17 @@ moves_loop: // When in check, search starts from here + (*contHist[3])[movedPiece][to_sq(move)] < 30000) continue; - // Prune moves with negative SEE (~10 Elo) + // Prune moves with negative SEE (~20 Elo) if (!pos.see_ge(move, Value(-(32 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth))) continue; } - else if (!pos.see_ge(move, Value(-194) * depth)) // (~20 Elo) + else if (!pos.see_ge(move, Value(-194) * depth)) // (~25 Elo) continue; } - // Step 14. Extensions (~70 Elo) + // Step 14. Extensions (~75 Elo) - // Singular extension search (~60 Elo). If all moves but one fail low on a + // Singular extension search (~70 Elo). If all moves but one fail low on a // search of (alpha-s, beta-s), and just one fails high on (alpha, beta), // then that move is singular and should be extended. To verify this we do // a reduced search on all the other moves but the ttMove and if the @@ -1099,7 +1101,7 @@ moves_loop: // When in check, search starts from here // Step 15. Make the move pos.do_move(move, st, givesCheck); - // Step 16. Reduced depth search (LMR). If the move fails high it will be + // Step 16. Reduced depth search (LMR, ~200 Elo). If the move fails high it will be // re-searched at full depth. if ( depth >= 3 && moveCount > 1 + 2 * rootNode @@ -1120,31 +1122,31 @@ moves_loop: // When in check, search starts from here if (th.marked()) r++; - // Decrease reduction if position is or has been on the PV + // Decrease reduction if position is or has been on the PV (~10 Elo) if (ttPv) r -= 2; - // Decrease reduction if opponent's move count is high (~10 Elo) + // Decrease reduction if opponent's move count is high (~5 Elo) if ((ss-1)->moveCount > 14) r--; - // Decrease reduction if ttMove has been singularly extended + // Decrease reduction if ttMove has been singularly extended (~3 Elo) if (singularLMR) r -= 2; if (!captureOrPromotion) { - // Increase reduction if ttMove is a capture (~0 Elo) + // Increase reduction if ttMove is a capture (~5 Elo) if (ttCapture) r++; - // Increase reduction for cut nodes (~5 Elo) + // Increase reduction for cut nodes (~10 Elo) if (cutNode) r += 2; // Decrease reduction for moves that escape a capture. Filter out // castling moves, because they are coded as "king captures rook" and - // hence break make_move(). (~5 Elo) + // hence break make_move(). (~2 Elo) else if ( type_of(move) == NORMAL && !pos.see_ge(reverse_move(move))) r -= 2;