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https://github.com/sockspls/badfish
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559942d64d
Double extensions can lead to search explosions, for specific positions. Currently, however, these double extensions are worth about 10Elo and cannot be removed. This patch instead limits the number of double extensions given to a maximum of 3. This fixes https://github.com/official-stockfish/Stockfish/issues/3532 where the following testcase was shown to be problematic: ``` uci setoption name Hash value 4 setoption name Contempt value 0 ucinewgame position fen 8/Pk6/8/1p6/8/P1K5/8/6B1 w - - 37 130 go depth 20 ``` passed STC: https://tests.stockfishchess.org/tests/view/60c13161457376eb8bcaaa0f LLR: 2.95 (-2.94,2.94) <-2.50,0.50> Total: 73256 W: 6114 L: 6062 D: 61080 Ptnml(0-2): 222, 4912, 26306, 4968, 220 passed LTC: https://tests.stockfishchess.org/tests/view/60c196fb457376eb8bcaaa6b LLR: 2.94 (-2.94,2.94) <-2.50,0.50> Total: 166440 W: 5559 L: 5594 D: 155287 Ptnml(0-2): 106, 4921, 73197, 4894, 102 closes https://github.com/official-stockfish/Stockfish/pull/3544 Bench: 5067605
114 lines
3.1 KiB
C++
114 lines
3.1 KiB
C++
/*
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Stockfish, a UCI chess playing engine derived from Glaurung 2.1
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Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
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Stockfish is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Stockfish is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef SEARCH_H_INCLUDED
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#define SEARCH_H_INCLUDED
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#include <vector>
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#include "misc.h"
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#include "movepick.h"
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#include "types.h"
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namespace Stockfish {
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class Position;
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namespace Search {
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/// Threshold used for countermoves based pruning
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constexpr int CounterMovePruneThreshold = 0;
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/// Stack struct keeps track of the information we need to remember from nodes
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/// shallower and deeper in the tree during the search. Each search thread has
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/// its own array of Stack objects, indexed by the current ply.
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struct Stack {
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Move* pv;
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PieceToHistory* continuationHistory;
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int ply;
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Move currentMove;
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Move excludedMove;
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Move killers[2];
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Value staticEval;
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int statScore;
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int moveCount;
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bool inCheck;
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bool ttPv;
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bool ttHit;
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int doubleExtensions;
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};
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/// RootMove struct is used for moves at the root of the tree. For each root move
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/// we store a score and a PV (really a refutation in the case of moves which
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/// fail low). Score is normally set at -VALUE_INFINITE for all non-pv moves.
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struct RootMove {
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explicit RootMove(Move m) : pv(1, m) {}
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bool extract_ponder_from_tt(Position& pos);
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bool operator==(const Move& m) const { return pv[0] == m; }
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bool operator<(const RootMove& m) const { // Sort in descending order
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return m.score != score ? m.score < score
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: m.previousScore < previousScore;
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}
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Value score = -VALUE_INFINITE;
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Value previousScore = -VALUE_INFINITE;
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int selDepth = 0;
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int tbRank = 0;
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Value tbScore;
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std::vector<Move> pv;
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};
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typedef std::vector<RootMove> RootMoves;
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/// LimitsType struct stores information sent by GUI about available time to
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/// search the current move, maximum depth/time, or if we are in analysis mode.
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struct LimitsType {
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LimitsType() { // Init explicitly due to broken value-initialization of non POD in MSVC
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time[WHITE] = time[BLACK] = inc[WHITE] = inc[BLACK] = npmsec = movetime = TimePoint(0);
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movestogo = depth = mate = perft = infinite = 0;
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nodes = 0;
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}
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bool use_time_management() const {
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return time[WHITE] || time[BLACK];
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}
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std::vector<Move> searchmoves;
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TimePoint time[COLOR_NB], inc[COLOR_NB], npmsec, movetime, startTime;
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int movestogo, depth, mate, perft, infinite;
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int64_t nodes;
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};
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extern LimitsType Limits;
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void init();
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void clear();
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} // namespace Search
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} // namespace Stockfish
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#endif // #ifndef SEARCH_H_INCLUDED
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