2813 lines
91 KiB
C++
2813 lines
91 KiB
C++
/*
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Stockfish, a UCI chess playing engine derived from Glaurung 2.1
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Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
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Copyright (C) 2008 Marco Costalba
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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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////
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//// Includes
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////
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#include <cassert>
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#include <fstream>
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#include <iostream>
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#include <sstream>
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#include "book.h"
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#include "evaluate.h"
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#include "history.h"
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#include "misc.h"
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#include "movepick.h"
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#include "san.h"
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#include "search.h"
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#include "thread.h"
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#include "tt.h"
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#include "ucioption.h"
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////
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//// Local definitions
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////
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namespace {
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/// Types
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// The BetaCounterType class is used to order moves at ply one.
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// Apart for the first one that has its score, following moves
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// normally have score -VALUE_INFINITE, so are ordered according
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// to the number of beta cutoffs occurred under their subtree during
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// the last iteration.
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struct BetaCounterType {
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BetaCounterType();
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void clear();
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void add(Color us, Depth d, int threadID);
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void read(Color us, int64_t& our, int64_t& their);
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int64_t hits[THREAD_MAX][2];
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};
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// The RootMove class is used for moves at the root at the tree. For each
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// root move, we store a score, a node count, and a PV (really a refutation
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// in the case of moves which fail low).
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struct RootMove {
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RootMove();
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bool operator<(const RootMove&); // used to sort
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Move move;
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Value score;
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int64_t nodes, cumulativeNodes;
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Move pv[PLY_MAX_PLUS_2];
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int64_t ourBeta, theirBeta;
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};
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// The RootMoveList class is essentially an array of RootMove objects, with
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// a handful of methods for accessing the data in the individual moves.
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class RootMoveList {
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public:
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RootMoveList(Position &pos, Move searchMoves[]);
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inline Move get_move(int moveNum) const;
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inline Value get_move_score(int moveNum) const;
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inline void set_move_score(int moveNum, Value score);
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inline void set_move_nodes(int moveNum, int64_t nodes);
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inline void set_beta_counters(int moveNum, int64_t our, int64_t their);
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void set_move_pv(int moveNum, const Move pv[]);
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inline Move get_move_pv(int moveNum, int i) const;
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inline int64_t get_move_cumulative_nodes(int moveNum) const;
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inline int move_count() const;
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Move scan_for_easy_move() const;
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inline void sort();
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void sort_multipv(int n);
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private:
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static const int MaxRootMoves = 500;
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RootMove moves[MaxRootMoves];
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int count;
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};
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/// Constants and variables
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// Minimum number of full depth (i.e. non-reduced) moves at PV and non-PV
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// nodes:
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int LMRPVMoves = 15;
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int LMRNonPVMoves = 4;
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// Depth limit for use of dynamic threat detection:
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Depth ThreatDepth = 5*OnePly;
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// Depth limit for selective search:
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Depth SelectiveDepth = 7*OnePly;
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// Use internal iterative deepening?
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const bool UseIIDAtPVNodes = true;
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const bool UseIIDAtNonPVNodes = false;
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// Use null move driven internal iterative deepening?
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bool UseNullDrivenIID = false;
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// Internal iterative deepening margin. At Non-PV moves, when
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// UseIIDAtNonPVNodes is true, we do an internal iterative deepening search
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// when the static evaluation is at most IIDMargin below beta.
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const Value IIDMargin = Value(0x100);
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// Easy move margin. An easy move candidate must be at least this much
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// better than the second best move.
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const Value EasyMoveMargin = Value(0x200);
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// Problem margin. If the score of the first move at iteration N+1 has
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// dropped by more than this since iteration N, the boolean variable
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// "Problem" is set to true, which will make the program spend some extra
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// time looking for a better move.
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const Value ProblemMargin = Value(0x28);
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// No problem margin. If the boolean "Problem" is true, and a new move
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// is found at the root which is less than NoProblemMargin worse than the
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// best move from the previous iteration, Problem is set back to false.
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const Value NoProblemMargin = Value(0x14);
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// Null move margin. A null move search will not be done if the approximate
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// evaluation of the position is more than NullMoveMargin below beta.
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const Value NullMoveMargin = Value(0x300);
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// Pruning criterions. See the code and comments in ok_to_prune() to
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// understand their precise meaning.
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const bool PruneEscapeMoves = false;
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const bool PruneDefendingMoves = false;
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const bool PruneBlockingMoves = false;
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// Use futility pruning?
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bool UseQSearchFutilityPruning = true;
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bool UseFutilityPruning = true;
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// Margins for futility pruning in the quiescence search, and at frontier
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// and near frontier nodes
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Value FutilityMarginQS = Value(0x80);
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Value FutilityMargins[6] = { Value(0x100), Value(0x200), Value(0x250),
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Value(0x2A0), Value(0x340), Value(0x3A0) };
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// Razoring
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const bool RazorAtDepthOne = false;
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Depth RazorDepth = 4*OnePly;
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Value RazorMargin = Value(0x300);
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// Last seconds noise filtering (LSN)
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bool UseLSNFiltering = false;
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bool looseOnTime = false;
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int LSNTime = 4 * 1000; // In milliseconds
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Value LSNValue = Value(0x200);
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// Extensions. Array index 0 is used at non-PV nodes, index 1 at PV nodes.
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Depth CheckExtension[2] = {OnePly, OnePly};
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Depth SingleReplyExtension[2] = {OnePly / 2, OnePly / 2};
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Depth PawnPushTo7thExtension[2] = {OnePly / 2, OnePly / 2};
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Depth PassedPawnExtension[2] = {Depth(0), Depth(0)};
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Depth PawnEndgameExtension[2] = {OnePly, OnePly};
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Depth MateThreatExtension[2] = {Depth(0), Depth(0)};
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// Search depth at iteration 1
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const Depth InitialDepth = OnePly /*+ OnePly/2*/;
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// Node counters
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int NodesSincePoll;
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int NodesBetweenPolls = 30000;
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// Iteration counters
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int Iteration;
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bool LastIterations;
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BetaCounterType BetaCounter;
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// Scores and number of times the best move changed for each iteration:
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Value ValueByIteration[PLY_MAX_PLUS_2];
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int BestMoveChangesByIteration[PLY_MAX_PLUS_2];
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// MultiPV mode
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int MultiPV = 1;
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// Time managment variables
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int SearchStartTime;
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int MaxNodes, MaxDepth;
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int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime;
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Move BestRootMove, PonderMove, EasyMove;
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int RootMoveNumber;
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bool InfiniteSearch;
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bool PonderSearch;
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bool StopOnPonderhit;
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bool AbortSearch;
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bool Quit;
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bool FailHigh;
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bool Problem;
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bool PonderingEnabled;
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int ExactMaxTime;
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// Show current line?
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bool ShowCurrentLine = false;
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// Log file
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bool UseLogFile = false;
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std::ofstream LogFile;
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// MP related variables
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Depth MinimumSplitDepth = 4*OnePly;
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int MaxThreadsPerSplitPoint = 4;
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Thread Threads[THREAD_MAX];
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Lock MPLock;
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bool AllThreadsShouldExit = false;
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const int MaxActiveSplitPoints = 8;
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SplitPoint SplitPointStack[THREAD_MAX][MaxActiveSplitPoints];
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bool Idle = true;
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#if !defined(_MSC_VER)
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pthread_cond_t WaitCond;
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pthread_mutex_t WaitLock;
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#else
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HANDLE SitIdleEvent[THREAD_MAX];
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#endif
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/// Functions
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Value id_loop(const Position &pos, Move searchMoves[]);
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Value root_search(Position &pos, SearchStack ss[], RootMoveList &rml);
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Value search_pv(Position &pos, SearchStack ss[], Value alpha, Value beta,
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Depth depth, int ply, int threadID);
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Value search(Position &pos, SearchStack ss[], Value beta,
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Depth depth, int ply, bool allowNullmove, int threadID);
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Value qsearch(Position &pos, SearchStack ss[], Value alpha, Value beta,
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Depth depth, int ply, int threadID);
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void sp_search(SplitPoint *sp, int threadID);
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void sp_search_pv(SplitPoint *sp, int threadID);
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void init_search_stack(SearchStack& ss);
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void init_search_stack(SearchStack ss[]);
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void init_node(const Position &pos, SearchStack ss[], int ply, int threadID);
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void update_pv(SearchStack ss[], int ply);
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void sp_update_pv(SearchStack *pss, SearchStack ss[], int ply);
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bool connected_moves(const Position &pos, Move m1, Move m2);
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bool value_is_mate(Value value);
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bool move_is_killer(Move m, const SearchStack& ss);
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Depth extension(const Position &pos, Move m, bool pvNode, bool capture, bool check, bool singleReply, bool mateThreat, bool* dangerous);
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bool ok_to_do_nullmove(const Position &pos);
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bool ok_to_prune(const Position &pos, Move m, Move threat, Depth d);
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bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply);
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bool ok_to_history(const Position &pos, Move m);
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void update_history(const Position& pos, Move m, Depth depth, Move movesSearched[], int moveCount);
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void update_killers(Move m, SearchStack& ss);
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bool fail_high_ply_1();
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int current_search_time();
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int nps();
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void poll();
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void ponderhit();
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void print_current_line(SearchStack ss[], int ply, int threadID);
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void wait_for_stop_or_ponderhit();
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void idle_loop(int threadID, SplitPoint *waitSp);
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void init_split_point_stack();
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void destroy_split_point_stack();
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bool thread_should_stop(int threadID);
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bool thread_is_available(int slave, int master);
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bool idle_thread_exists(int master);
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bool split(const Position &pos, SearchStack *ss, int ply,
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Value *alpha, Value *beta, Value *bestValue, Depth depth,
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int *moves, MovePicker *mp, int master, bool pvNode);
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void wake_sleeping_threads();
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#if !defined(_MSC_VER)
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void *init_thread(void *threadID);
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#else
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DWORD WINAPI init_thread(LPVOID threadID);
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#endif
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}
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////
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//// Global variables
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////
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// The main transposition table
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TranspositionTable TT = TranspositionTable(TTDefaultSize);
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// Number of active threads:
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int ActiveThreads = 1;
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// Locks. In principle, there is no need for IOLock to be a global variable,
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// but it could turn out to be useful for debugging.
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Lock IOLock;
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History H; // Should be made local?
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// The empty search stack
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SearchStack EmptySearchStack;
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////
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//// Functions
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////
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/// think() is the external interface to Stockfish's search, and is called when
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/// the program receives the UCI 'go' command. It initializes various
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/// search-related global variables, and calls root_search()
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void think(const Position &pos, bool infinite, bool ponder, int side_to_move,
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int time[], int increment[], int movesToGo, int maxDepth,
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int maxNodes, int maxTime, Move searchMoves[]) {
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// Look for a book move
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if (!infinite && !ponder && get_option_value_bool("OwnBook"))
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{
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Move bookMove;
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if (get_option_value_string("Book File") != OpeningBook.file_name())
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{
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OpeningBook.close();
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OpeningBook.open("book.bin");
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}
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bookMove = OpeningBook.get_move(pos);
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if (bookMove != MOVE_NONE)
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{
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std::cout << "bestmove " << bookMove << std::endl;
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return;
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}
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}
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// Initialize global search variables
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Idle = false;
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SearchStartTime = get_system_time();
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BestRootMove = MOVE_NONE;
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PonderMove = MOVE_NONE;
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EasyMove = MOVE_NONE;
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for (int i = 0; i < THREAD_MAX; i++)
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{
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Threads[i].nodes = 0ULL;
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Threads[i].failHighPly1 = false;
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}
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NodesSincePoll = 0;
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InfiniteSearch = infinite;
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PonderSearch = ponder;
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StopOnPonderhit = false;
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AbortSearch = false;
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Quit = false;
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FailHigh = false;
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Problem = false;
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ExactMaxTime = maxTime;
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// Read UCI option values
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TT.set_size(get_option_value_int("Hash"));
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if (button_was_pressed("Clear Hash"))
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TT.clear();
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PonderingEnabled = get_option_value_bool("Ponder");
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MultiPV = get_option_value_int("MultiPV");
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CheckExtension[1] = Depth(get_option_value_int("Check Extension (PV nodes)"));
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CheckExtension[0] = Depth(get_option_value_int("Check Extension (non-PV nodes)"));
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SingleReplyExtension[1] = Depth(get_option_value_int("Single Reply Extension (PV nodes)"));
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SingleReplyExtension[0] = Depth(get_option_value_int("Single Reply Extension (non-PV nodes)"));
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PawnPushTo7thExtension[1] = Depth(get_option_value_int("Pawn Push to 7th Extension (PV nodes)"));
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PawnPushTo7thExtension[0] = Depth(get_option_value_int("Pawn Push to 7th Extension (non-PV nodes)"));
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PassedPawnExtension[1] = Depth(get_option_value_int("Passed Pawn Extension (PV nodes)"));
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PassedPawnExtension[0] = Depth(get_option_value_int("Passed Pawn Extension (non-PV nodes)"));
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PawnEndgameExtension[1] = Depth(get_option_value_int("Pawn Endgame Extension (PV nodes)"));
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PawnEndgameExtension[0] = Depth(get_option_value_int("Pawn Endgame Extension (non-PV nodes)"));
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MateThreatExtension[1] = Depth(get_option_value_int("Mate Threat Extension (PV nodes)"));
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MateThreatExtension[0] = Depth(get_option_value_int("Mate Threat Extension (non-PV nodes)"));
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LMRPVMoves = get_option_value_int("Full Depth Moves (PV nodes)") + 1;
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LMRNonPVMoves = get_option_value_int("Full Depth Moves (non-PV nodes)") + 1;
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ThreatDepth = get_option_value_int("Threat Depth") * OnePly;
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SelectiveDepth = get_option_value_int("Selective Plies") * OnePly;
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Chess960 = get_option_value_bool("UCI_Chess960");
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ShowCurrentLine = get_option_value_bool("UCI_ShowCurrLine");
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UseLogFile = get_option_value_bool("Use Search Log");
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if (UseLogFile)
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LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app);
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UseNullDrivenIID = get_option_value_bool("Null driven IID");
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UseQSearchFutilityPruning = get_option_value_bool("Futility Pruning (Quiescence Search)");
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UseFutilityPruning = get_option_value_bool("Futility Pruning (Main Search)");
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FutilityMarginQS = value_from_centipawns(get_option_value_int("Futility Margin (Quiescence Search)"));
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int fmScale = get_option_value_int("Futility Margin Scale Factor (Main Search)");
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for (int i = 0; i < 6; i++)
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FutilityMargins[i] = (FutilityMargins[i] * fmScale) / 100;
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RazorDepth = (get_option_value_int("Maximum Razoring Depth") + 1) * OnePly;
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RazorMargin = value_from_centipawns(get_option_value_int("Razoring Margin"));
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UseLSNFiltering = get_option_value_bool("LSN filtering");
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LSNTime = get_option_value_int("LSN Time Margin (sec)") * 1000;
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LSNValue = value_from_centipawns(get_option_value_int("LSN Value Margin"));
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MinimumSplitDepth = get_option_value_int("Minimum Split Depth") * OnePly;
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MaxThreadsPerSplitPoint = get_option_value_int("Maximum Number of Threads per Split Point");
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read_weights(pos.side_to_move());
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int newActiveThreads = get_option_value_int("Threads");
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if (newActiveThreads != ActiveThreads)
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{
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ActiveThreads = newActiveThreads;
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init_eval(ActiveThreads);
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}
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// Wake up sleeping threads:
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wake_sleeping_threads();
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for (int i = 1; i < ActiveThreads; i++)
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assert(thread_is_available(i, 0));
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// Set thinking time:
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int myTime = time[side_to_move];
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int myIncrement = increment[side_to_move];
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if (!movesToGo) // Sudden death time control
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{
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if (myIncrement)
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{
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MaxSearchTime = myTime / 30 + myIncrement;
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AbsoluteMaxSearchTime = Max(myTime / 4, myIncrement - 100);
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} else { // Blitz game without increment
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MaxSearchTime = myTime / 30;
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AbsoluteMaxSearchTime = myTime / 8;
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}
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}
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else // (x moves) / (y minutes)
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{
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if (movesToGo == 1)
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{
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MaxSearchTime = myTime / 2;
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AbsoluteMaxSearchTime = Min(myTime / 2, myTime - 500);
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} else {
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MaxSearchTime = myTime / Min(movesToGo, 20);
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AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3);
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}
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}
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if (PonderingEnabled)
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{
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MaxSearchTime += MaxSearchTime / 4;
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MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime);
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}
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// Fixed depth or fixed number of nodes?
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MaxDepth = maxDepth;
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if (MaxDepth)
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InfiniteSearch = true; // HACK
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MaxNodes = maxNodes;
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if (MaxNodes)
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{
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NodesBetweenPolls = Min(MaxNodes, 30000);
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InfiniteSearch = true; // HACK
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}
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else
|
|
NodesBetweenPolls = 30000;
|
|
|
|
|
|
// Write information to search log file:
|
|
if (UseLogFile)
|
|
LogFile << "Searching: " << pos.to_fen() << std::endl
|
|
<< "infinite: " << infinite
|
|
<< " ponder: " << ponder
|
|
<< " time: " << myTime
|
|
<< " increment: " << myIncrement
|
|
<< " moves to go: " << movesToGo << std::endl;
|
|
|
|
|
|
// We're ready to start thinking. Call the iterative deepening loop
|
|
// function:
|
|
if (!looseOnTime)
|
|
{
|
|
Value v = id_loop(pos, searchMoves);
|
|
looseOnTime = ( UseLSNFiltering
|
|
&& myTime < LSNTime
|
|
&& myIncrement == 0
|
|
&& v < -LSNValue);
|
|
}
|
|
else
|
|
{
|
|
looseOnTime = false; // reset for next match
|
|
while (SearchStartTime + myTime + 1000 > get_system_time())
|
|
; // wait here
|
|
id_loop(pos, searchMoves); // to fail gracefully
|
|
}
|
|
|
|
if (UseLogFile)
|
|
LogFile.close();
|
|
|
|
if (Quit)
|
|
{
|
|
OpeningBook.close();
|
|
stop_threads();
|
|
quit_eval();
|
|
exit(0);
|
|
}
|
|
Idle = true;
|
|
}
|
|
|
|
|
|
/// init_threads() is called during startup. It launches all helper threads,
|
|
/// and initializes the split point stack and the global locks and condition
|
|
/// objects.
|
|
|
|
void init_threads() {
|
|
|
|
volatile int i;
|
|
|
|
#if !defined(_MSC_VER)
|
|
pthread_t pthread[1];
|
|
#endif
|
|
|
|
for (i = 0; i < THREAD_MAX; i++)
|
|
Threads[i].activeSplitPoints = 0;
|
|
|
|
// Initialize global locks:
|
|
lock_init(&MPLock, NULL);
|
|
lock_init(&IOLock, NULL);
|
|
|
|
init_split_point_stack();
|
|
|
|
#if !defined(_MSC_VER)
|
|
pthread_mutex_init(&WaitLock, NULL);
|
|
pthread_cond_init(&WaitCond, NULL);
|
|
#else
|
|
for (i = 0; i < THREAD_MAX; i++)
|
|
SitIdleEvent[i] = CreateEvent(0, FALSE, FALSE, 0);
|
|
#endif
|
|
|
|
// All threads except the main thread should be initialized to idle state
|
|
for (i = 1; i < THREAD_MAX; i++)
|
|
{
|
|
Threads[i].stop = false;
|
|
Threads[i].workIsWaiting = false;
|
|
Threads[i].idle = true;
|
|
Threads[i].running = false;
|
|
}
|
|
|
|
// Launch the helper threads
|
|
for(i = 1; i < THREAD_MAX; i++)
|
|
{
|
|
#if !defined(_MSC_VER)
|
|
pthread_create(pthread, NULL, init_thread, (void*)(&i));
|
|
#else
|
|
DWORD iID[1];
|
|
CreateThread(NULL, 0, init_thread, (LPVOID)(&i), 0, iID);
|
|
#endif
|
|
|
|
// Wait until the thread has finished launching:
|
|
while (!Threads[i].running);
|
|
}
|
|
|
|
// Init also the empty search stack
|
|
init_search_stack(EmptySearchStack);
|
|
}
|
|
|
|
|
|
/// stop_threads() is called when the program exits. It makes all the
|
|
/// helper threads exit cleanly.
|
|
|
|
void stop_threads() {
|
|
|
|
ActiveThreads = THREAD_MAX; // HACK
|
|
Idle = false; // HACK
|
|
wake_sleeping_threads();
|
|
AllThreadsShouldExit = true;
|
|
for (int i = 1; i < THREAD_MAX; i++)
|
|
{
|
|
Threads[i].stop = true;
|
|
while(Threads[i].running);
|
|
}
|
|
destroy_split_point_stack();
|
|
}
|
|
|
|
|
|
/// nodes_searched() returns the total number of nodes searched so far in
|
|
/// the current search.
|
|
|
|
int64_t nodes_searched() {
|
|
|
|
int64_t result = 0ULL;
|
|
for (int i = 0; i < ActiveThreads; i++)
|
|
result += Threads[i].nodes;
|
|
return result;
|
|
}
|
|
|
|
|
|
namespace {
|
|
|
|
// id_loop() is the main iterative deepening loop. It calls root_search
|
|
// repeatedly with increasing depth until the allocated thinking time has
|
|
// been consumed, the user stops the search, or the maximum search depth is
|
|
// reached.
|
|
|
|
Value id_loop(const Position &pos, Move searchMoves[]) {
|
|
|
|
Position p(pos);
|
|
SearchStack ss[PLY_MAX_PLUS_2];
|
|
|
|
// searchMoves are verified, copied, scored and sorted
|
|
RootMoveList rml(p, searchMoves);
|
|
|
|
// Initialize
|
|
TT.new_search();
|
|
H.clear();
|
|
init_search_stack(ss);
|
|
|
|
ValueByIteration[0] = Value(0);
|
|
ValueByIteration[1] = rml.get_move_score(0);
|
|
Iteration = 1;
|
|
LastIterations = false;
|
|
|
|
EasyMove = rml.scan_for_easy_move();
|
|
|
|
// Iterative deepening loop
|
|
while (!AbortSearch && Iteration < PLY_MAX)
|
|
{
|
|
// Initialize iteration
|
|
rml.sort();
|
|
Iteration++;
|
|
BestMoveChangesByIteration[Iteration] = 0;
|
|
if (Iteration <= 5)
|
|
ExtraSearchTime = 0;
|
|
|
|
std::cout << "info depth " << Iteration << std::endl;
|
|
|
|
// Search to the current depth
|
|
ValueByIteration[Iteration] = root_search(p, ss, rml);
|
|
|
|
// Erase the easy move if it differs from the new best move
|
|
if (ss[0].pv[0] != EasyMove)
|
|
EasyMove = MOVE_NONE;
|
|
|
|
Problem = false;
|
|
|
|
if (!InfiniteSearch)
|
|
{
|
|
// Time to stop?
|
|
bool stopSearch = false;
|
|
|
|
// Stop search early if there is only a single legal move:
|
|
if (Iteration >= 6 && rml.move_count() == 1)
|
|
stopSearch = true;
|
|
|
|
// Stop search early when the last two iterations returned a mate score
|
|
if ( Iteration >= 6
|
|
&& abs(ValueByIteration[Iteration]) >= abs(VALUE_MATE) - 100
|
|
&& abs(ValueByIteration[Iteration-1]) >= abs(VALUE_MATE) - 100)
|
|
stopSearch = true;
|
|
|
|
// Stop search early if one move seems to be much better than the rest
|
|
int64_t nodes = nodes_searched();
|
|
if ( Iteration >= 8
|
|
&& EasyMove == ss[0].pv[0]
|
|
&& ( ( rml.get_move_cumulative_nodes(0) > (nodes * 85) / 100
|
|
&& current_search_time() > MaxSearchTime / 16)
|
|
||( rml.get_move_cumulative_nodes(0) > (nodes * 98) / 100
|
|
&& current_search_time() > MaxSearchTime / 32)))
|
|
stopSearch = true;
|
|
|
|
// Add some extra time if the best move has changed during the last two iterations
|
|
if (Iteration > 5 && Iteration <= 50)
|
|
ExtraSearchTime = BestMoveChangesByIteration[Iteration] * (MaxSearchTime / 2)
|
|
+ BestMoveChangesByIteration[Iteration-1] * (MaxSearchTime / 3);
|
|
|
|
// Try to guess if the current iteration is the last one or the last two
|
|
LastIterations = (current_search_time() > ((MaxSearchTime + ExtraSearchTime)*58) / 128);
|
|
|
|
// Stop search if most of MaxSearchTime is consumed at the end of the
|
|
// iteration. We probably don't have enough time to search the first
|
|
// move at the next iteration anyway.
|
|
if (current_search_time() > ((MaxSearchTime + ExtraSearchTime)*80) / 128)
|
|
stopSearch = true;
|
|
|
|
if (stopSearch)
|
|
{
|
|
if (!PonderSearch)
|
|
break;
|
|
else
|
|
StopOnPonderhit = true;
|
|
}
|
|
}
|
|
// Write PV to transposition table, in case the relevant entries have
|
|
// been overwritten during the search:
|
|
TT.insert_pv(p, ss[0].pv);
|
|
|
|
if (MaxDepth && Iteration >= MaxDepth)
|
|
break;
|
|
}
|
|
|
|
rml.sort();
|
|
|
|
// If we are pondering, we shouldn't print the best move before we
|
|
// are told to do so
|
|
if (PonderSearch)
|
|
wait_for_stop_or_ponderhit();
|
|
else
|
|
// Print final search statistics
|
|
std::cout << "info nodes " << nodes_searched()
|
|
<< " nps " << nps()
|
|
<< " time " << current_search_time()
|
|
<< " hashfull " << TT.full() << std::endl;
|
|
|
|
// Print the best move and the ponder move to the standard output
|
|
std::cout << "bestmove " << ss[0].pv[0];
|
|
if (ss[0].pv[1] != MOVE_NONE)
|
|
std::cout << " ponder " << ss[0].pv[1];
|
|
|
|
std::cout << std::endl;
|
|
|
|
if (UseLogFile)
|
|
{
|
|
if (dbg_show_mean)
|
|
dbg_print_mean(LogFile);
|
|
|
|
if (dbg_show_hit_rate)
|
|
dbg_print_hit_rate(LogFile);
|
|
|
|
UndoInfo u;
|
|
LogFile << "Nodes: " << nodes_searched() << std::endl
|
|
<< "Nodes/second: " << nps() << std::endl
|
|
<< "Best move: " << move_to_san(p, ss[0].pv[0]) << std::endl;
|
|
|
|
p.do_move(ss[0].pv[0], u);
|
|
LogFile << "Ponder move: " << move_to_san(p, ss[0].pv[1])
|
|
<< std::endl << std::endl;
|
|
}
|
|
return rml.get_move_score(0);
|
|
}
|
|
|
|
|
|
// root_search() is the function which searches the root node. It is
|
|
// similar to search_pv except that it uses a different move ordering
|
|
// scheme (perhaps we should try to use this at internal PV nodes, too?)
|
|
// and prints some information to the standard output.
|
|
|
|
Value root_search(Position &pos, SearchStack ss[], RootMoveList &rml) {
|
|
|
|
Value alpha = -VALUE_INFINITE;
|
|
Value beta = VALUE_INFINITE, value;
|
|
|
|
// Loop through all the moves in the root move list
|
|
for (int i = 0; i < rml.move_count() && !AbortSearch; i++)
|
|
{
|
|
int64_t nodes;
|
|
Move move;
|
|
UndoInfo u;
|
|
Depth ext, newDepth;
|
|
|
|
RootMoveNumber = i + 1;
|
|
FailHigh = false;
|
|
|
|
// Remember the node count before the move is searched. The node counts
|
|
// are used to sort the root moves at the next iteration.
|
|
nodes = nodes_searched();
|
|
|
|
// Reset beta cut-off counters
|
|
BetaCounter.clear();
|
|
|
|
// Pick the next root move, and print the move and the move number to
|
|
// the standard output.
|
|
move = ss[0].currentMove = rml.get_move(i);
|
|
if (current_search_time() >= 1000)
|
|
std::cout << "info currmove " << move
|
|
<< " currmovenumber " << i + 1 << std::endl;
|
|
|
|
// Decide search depth for this move
|
|
bool dangerous;
|
|
ext = extension(pos, move, true, pos.move_is_capture(move), pos.move_is_check(move), false, false, &dangerous);
|
|
newDepth = (Iteration - 2) * OnePly + ext + InitialDepth;
|
|
|
|
// Make the move, and search it
|
|
pos.do_move(move, u);
|
|
|
|
if (i < MultiPV)
|
|
{
|
|
value = -search_pv(pos, ss, -beta, VALUE_INFINITE, newDepth, 1, 0);
|
|
// If the value has dropped a lot compared to the last iteration,
|
|
// set the boolean variable Problem to true. This variable is used
|
|
// for time managment: When Problem is true, we try to complete the
|
|
// current iteration before playing a move.
|
|
Problem = (Iteration >= 2 && value <= ValueByIteration[Iteration-1] - ProblemMargin);
|
|
|
|
if (Problem && StopOnPonderhit)
|
|
StopOnPonderhit = false;
|
|
}
|
|
else
|
|
{
|
|
value = -search(pos, ss, -alpha, newDepth, 1, true, 0);
|
|
if (value > alpha)
|
|
{
|
|
// Fail high! Set the boolean variable FailHigh to true, and
|
|
// re-search the move with a big window. The variable FailHigh is
|
|
// used for time managment: We try to avoid aborting the search
|
|
// prematurely during a fail high research.
|
|
FailHigh = true;
|
|
value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0);
|
|
}
|
|
}
|
|
|
|
pos.undo_move(move);
|
|
|
|
// Finished searching the move. If AbortSearch is true, the search
|
|
// was aborted because the user interrupted the search or because we
|
|
// ran out of time. In this case, the return value of the search cannot
|
|
// be trusted, and we break out of the loop without updating the best
|
|
// move and/or PV:
|
|
if (AbortSearch)
|
|
break;
|
|
|
|
// Remember the node count for this move. The node counts are used to
|
|
// sort the root moves at the next iteration.
|
|
rml.set_move_nodes(i, nodes_searched() - nodes);
|
|
|
|
// Remember the beta-cutoff statistics
|
|
int64_t our, their;
|
|
BetaCounter.read(pos.side_to_move(), our, their);
|
|
rml.set_beta_counters(i, our, their);
|
|
|
|
assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE);
|
|
|
|
if (value <= alpha && i >= MultiPV)
|
|
rml.set_move_score(i, -VALUE_INFINITE);
|
|
else
|
|
{
|
|
// New best move!
|
|
|
|
// Update PV
|
|
rml.set_move_score(i, value);
|
|
update_pv(ss, 0);
|
|
rml.set_move_pv(i, ss[0].pv);
|
|
|
|
if (MultiPV == 1)
|
|
{
|
|
// We record how often the best move has been changed in each
|
|
// iteration. This information is used for time managment: When
|
|
// the best move changes frequently, we allocate some more time.
|
|
if (i > 0)
|
|
BestMoveChangesByIteration[Iteration]++;
|
|
|
|
// Print search information to the standard output:
|
|
std::cout << "info depth " << Iteration
|
|
<< " score " << value_to_string(value)
|
|
<< " time " << current_search_time()
|
|
<< " nodes " << nodes_searched()
|
|
<< " nps " << nps()
|
|
<< " pv ";
|
|
|
|
for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++)
|
|
std::cout << ss[0].pv[j] << " ";
|
|
|
|
std::cout << std::endl;
|
|
|
|
if (UseLogFile)
|
|
LogFile << pretty_pv(pos, current_search_time(), Iteration, nodes_searched(), value, ss[0].pv)
|
|
<< std::endl;
|
|
|
|
alpha = value;
|
|
|
|
// Reset the global variable Problem to false if the value isn't too
|
|
// far below the final value from the last iteration.
|
|
if (value > ValueByIteration[Iteration - 1] - NoProblemMargin)
|
|
Problem = false;
|
|
}
|
|
else // MultiPV > 1
|
|
{
|
|
rml.sort_multipv(i);
|
|
for (int j = 0; j < Min(MultiPV, rml.move_count()); j++)
|
|
{
|
|
int k;
|
|
std::cout << "info multipv " << j + 1
|
|
<< " score " << value_to_string(rml.get_move_score(j))
|
|
<< " depth " << ((j <= i)? Iteration : Iteration - 1)
|
|
<< " time " << current_search_time()
|
|
<< " nodes " << nodes_searched()
|
|
<< " nps " << nps()
|
|
<< " pv ";
|
|
|
|
for (k = 0; rml.get_move_pv(j, k) != MOVE_NONE && k < PLY_MAX; k++)
|
|
std::cout << rml.get_move_pv(j, k) << " ";
|
|
|
|
std::cout << std::endl;
|
|
}
|
|
alpha = rml.get_move_score(Min(i, MultiPV-1));
|
|
}
|
|
}
|
|
}
|
|
return alpha;
|
|
}
|
|
|
|
|
|
// search_pv() is the main search function for PV nodes.
|
|
|
|
Value search_pv(Position &pos, SearchStack ss[], Value alpha, Value beta,
|
|
Depth depth, int ply, int threadID) {
|
|
|
|
assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
|
|
assert(beta > alpha && beta <= VALUE_INFINITE);
|
|
assert(ply >= 0 && ply < PLY_MAX);
|
|
assert(threadID >= 0 && threadID < ActiveThreads);
|
|
|
|
if (depth < OnePly)
|
|
return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID);
|
|
|
|
// Initialize, and make an early exit in case of an aborted search,
|
|
// an instant draw, maximum ply reached, etc.
|
|
init_node(pos, ss, ply, threadID);
|
|
|
|
// After init_node() that calls poll()
|
|
if (AbortSearch || thread_should_stop(threadID))
|
|
return Value(0);
|
|
|
|
if (pos.is_draw())
|
|
return VALUE_DRAW;
|
|
|
|
EvalInfo ei;
|
|
|
|
if (ply >= PLY_MAX - 1)
|
|
return evaluate(pos, ei, threadID);
|
|
|
|
// Mate distance pruning
|
|
Value oldAlpha = alpha;
|
|
alpha = Max(value_mated_in(ply), alpha);
|
|
beta = Min(value_mate_in(ply+1), beta);
|
|
if (alpha >= beta)
|
|
return alpha;
|
|
|
|
// Transposition table lookup. At PV nodes, we don't use the TT for
|
|
// pruning, but only for move ordering.
|
|
const TTEntry* tte = TT.retrieve(pos);
|
|
Move ttMove = (tte ? tte->move() : MOVE_NONE);
|
|
|
|
// Go with internal iterative deepening if we don't have a TT move
|
|
if (UseIIDAtPVNodes && ttMove == MOVE_NONE && depth >= 5*OnePly)
|
|
{
|
|
search_pv(pos, ss, alpha, beta, depth-2*OnePly, ply, threadID);
|
|
ttMove = ss[ply].pv[ply];
|
|
}
|
|
|
|
// Initialize a MovePicker object for the current position, and prepare
|
|
// to search all moves
|
|
MovePicker mp = MovePicker(pos, true, ttMove, ss[ply], depth);
|
|
|
|
Move move, movesSearched[256];
|
|
int moveCount = 0;
|
|
Value value, bestValue = -VALUE_INFINITE;
|
|
Color us = pos.side_to_move();
|
|
bool isCheck = pos.is_check();
|
|
bool mateThreat = pos.has_mate_threat(opposite_color(us));
|
|
|
|
// Loop through all legal moves until no moves remain or a beta cutoff
|
|
// occurs.
|
|
while ( alpha < beta
|
|
&& (move = mp.get_next_move()) != MOVE_NONE
|
|
&& !thread_should_stop(threadID))
|
|
{
|
|
assert(move_is_ok(move));
|
|
|
|
bool singleReply = (isCheck && mp.number_of_moves() == 1);
|
|
bool moveIsCheck = pos.move_is_check(move);
|
|
bool moveIsCapture = pos.move_is_capture(move);
|
|
|
|
movesSearched[moveCount++] = ss[ply].currentMove = move;
|
|
|
|
if (moveIsCapture)
|
|
ss[ply].currentMoveCaptureValue =
|
|
move_is_ep(move)? PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move));
|
|
else
|
|
ss[ply].currentMoveCaptureValue = Value(0);
|
|
|
|
// Decide the new search depth
|
|
bool dangerous;
|
|
Depth ext = extension(pos, move, true, moveIsCapture, moveIsCheck, singleReply, mateThreat, &dangerous);
|
|
Depth newDepth = depth - OnePly + ext;
|
|
|
|
// Make and search the move
|
|
UndoInfo u;
|
|
pos.do_move(move, u);
|
|
|
|
if (moveCount == 1) // The first move in list is the PV
|
|
value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID);
|
|
else
|
|
{
|
|
// Try to reduce non-pv search depth by one ply if move seems not problematic,
|
|
// if the move fails high will be re-searched at full depth.
|
|
if ( depth >= 2*OnePly
|
|
&& moveCount >= LMRPVMoves
|
|
&& !dangerous
|
|
&& !moveIsCapture
|
|
&& !move_promotion(move)
|
|
&& !move_is_castle(move)
|
|
&& !move_is_killer(move, ss[ply]))
|
|
{
|
|
ss[ply].reduction = OnePly;
|
|
value = -search(pos, ss, -alpha, newDepth-OnePly, ply+1, true, threadID);
|
|
}
|
|
else
|
|
value = alpha + 1; // Just to trigger next condition
|
|
|
|
if (value > alpha) // Go with full depth non-pv search
|
|
{
|
|
ss[ply].reduction = Depth(0);
|
|
value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID);
|
|
if (value > alpha && value < beta)
|
|
{
|
|
// When the search fails high at ply 1 while searching the first
|
|
// move at the root, set the flag failHighPly1. This is used for
|
|
// time managment: We don't want to stop the search early in
|
|
// such cases, because resolving the fail high at ply 1 could
|
|
// result in a big drop in score at the root.
|
|
if (ply == 1 && RootMoveNumber == 1)
|
|
Threads[threadID].failHighPly1 = true;
|
|
|
|
// A fail high occurred. Re-search at full window (pv search)
|
|
value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID);
|
|
Threads[threadID].failHighPly1 = false;
|
|
}
|
|
}
|
|
}
|
|
pos.undo_move(move);
|
|
|
|
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
|
|
|
|
// New best move?
|
|
if (value > bestValue)
|
|
{
|
|
bestValue = value;
|
|
if (value > alpha)
|
|
{
|
|
alpha = value;
|
|
update_pv(ss, ply);
|
|
if (value == value_mate_in(ply + 1))
|
|
ss[ply].mateKiller = move;
|
|
}
|
|
// If we are at ply 1, and we are searching the first root move at
|
|
// ply 0, set the 'Problem' variable if the score has dropped a lot
|
|
// (from the computer's point of view) since the previous iteration:
|
|
if ( ply == 1
|
|
&& Iteration >= 2
|
|
&& -value <= ValueByIteration[Iteration-1] - ProblemMargin)
|
|
Problem = true;
|
|
}
|
|
|
|
// Split?
|
|
if ( ActiveThreads > 1
|
|
&& bestValue < beta
|
|
&& depth >= MinimumSplitDepth
|
|
&& Iteration <= 99
|
|
&& idle_thread_exists(threadID)
|
|
&& !AbortSearch
|
|
&& !thread_should_stop(threadID)
|
|
&& split(pos, ss, ply, &alpha, &beta, &bestValue, depth,
|
|
&moveCount, &mp, threadID, true))
|
|
break;
|
|
}
|
|
|
|
// All legal moves have been searched. A special case: If there were
|
|
// no legal moves, it must be mate or stalemate:
|
|
if (moveCount == 0)
|
|
return (isCheck ? value_mated_in(ply) : VALUE_DRAW);
|
|
|
|
// If the search is not aborted, update the transposition table,
|
|
// history counters, and killer moves.
|
|
if (AbortSearch || thread_should_stop(threadID))
|
|
return bestValue;
|
|
|
|
if (bestValue <= oldAlpha)
|
|
TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE, VALUE_TYPE_UPPER);
|
|
|
|
else if (bestValue >= beta)
|
|
{
|
|
BetaCounter.add(pos.side_to_move(), depth, threadID);
|
|
Move m = ss[ply].pv[ply];
|
|
if (ok_to_history(pos, m)) // Only non capture moves are considered
|
|
{
|
|
update_history(pos, m, depth, movesSearched, moveCount);
|
|
update_killers(m, ss[ply]);
|
|
}
|
|
TT.store(pos, value_to_tt(bestValue, ply), depth, m, VALUE_TYPE_LOWER);
|
|
}
|
|
else
|
|
TT.store(pos, value_to_tt(bestValue, ply), depth, ss[ply].pv[ply], VALUE_TYPE_EXACT);
|
|
|
|
return bestValue;
|
|
}
|
|
|
|
|
|
// search() is the search function for zero-width nodes.
|
|
|
|
Value search(Position &pos, SearchStack ss[], Value beta, Depth depth,
|
|
int ply, bool allowNullmove, int threadID) {
|
|
|
|
assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
|
|
assert(ply >= 0 && ply < PLY_MAX);
|
|
assert(threadID >= 0 && threadID < ActiveThreads);
|
|
|
|
if (depth < OnePly)
|
|
return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
|
|
|
|
// Initialize, and make an early exit in case of an aborted search,
|
|
// an instant draw, maximum ply reached, etc.
|
|
init_node(pos, ss, ply, threadID);
|
|
|
|
// After init_node() that calls poll()
|
|
if (AbortSearch || thread_should_stop(threadID))
|
|
return Value(0);
|
|
|
|
if (pos.is_draw())
|
|
return VALUE_DRAW;
|
|
|
|
EvalInfo ei;
|
|
|
|
if (ply >= PLY_MAX - 1)
|
|
return evaluate(pos, ei, threadID);
|
|
|
|
// Mate distance pruning
|
|
if (value_mated_in(ply) >= beta)
|
|
return beta;
|
|
|
|
if (value_mate_in(ply + 1) < beta)
|
|
return beta - 1;
|
|
|
|
// Transposition table lookup
|
|
const TTEntry* tte = TT.retrieve(pos);
|
|
Move ttMove = (tte ? tte->move() : MOVE_NONE);
|
|
|
|
if (tte && ok_to_use_TT(tte, depth, beta, ply))
|
|
{
|
|
ss[ply].currentMove = ttMove; // can be MOVE_NONE
|
|
return value_from_tt(tte->value(), ply);
|
|
}
|
|
|
|
Value approximateEval = quick_evaluate(pos);
|
|
bool mateThreat = false;
|
|
bool nullDrivenIID = false;
|
|
bool isCheck = pos.is_check();
|
|
|
|
// Null move search
|
|
if ( allowNullmove
|
|
&& depth > OnePly
|
|
&& !isCheck
|
|
&& !value_is_mate(beta)
|
|
&& ok_to_do_nullmove(pos)
|
|
&& approximateEval >= beta - NullMoveMargin)
|
|
{
|
|
ss[ply].currentMove = MOVE_NULL;
|
|
|
|
UndoInfo u;
|
|
pos.do_null_move(u);
|
|
int R = (depth >= 4 * OnePly ? 4 : 3); // Null move dynamic reduction
|
|
|
|
Value nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
|
|
|
|
// Check for a null capture artifact, if the value without the null capture
|
|
// is above beta then mark the node as a suspicious failed low. We will verify
|
|
// later if we are really under threat.
|
|
if ( UseNullDrivenIID
|
|
&& nullValue < beta
|
|
&& depth > 6 * OnePly
|
|
&&!value_is_mate(nullValue)
|
|
&& ttMove == MOVE_NONE
|
|
&& ss[ply + 1].currentMove != MOVE_NONE
|
|
&& pos.move_is_capture(ss[ply + 1].currentMove)
|
|
&& pos.see(ss[ply + 1].currentMove) + nullValue >= beta)
|
|
nullDrivenIID = true;
|
|
|
|
pos.undo_null_move(u);
|
|
|
|
if (value_is_mate(nullValue))
|
|
{
|
|
/* Do not return unproven mates */
|
|
}
|
|
else if (nullValue >= beta)
|
|
{
|
|
if (depth < 6 * OnePly)
|
|
return beta;
|
|
|
|
// Do zugzwang verification search
|
|
Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID);
|
|
if (v >= beta)
|
|
return beta;
|
|
} else {
|
|
// The null move failed low, which means that we may be faced with
|
|
// some kind of threat. If the previous move was reduced, check if
|
|
// the move that refuted the null move was somehow connected to the
|
|
// move which was reduced. If a connection is found, return a fail
|
|
// low score (which will cause the reduced move to fail high in the
|
|
// parent node, which will trigger a re-search with full depth).
|
|
if (nullValue == value_mated_in(ply + 2))
|
|
{
|
|
mateThreat = true;
|
|
nullDrivenIID = false;
|
|
}
|
|
ss[ply].threatMove = ss[ply + 1].currentMove;
|
|
if ( depth < ThreatDepth
|
|
&& ss[ply - 1].reduction
|
|
&& connected_moves(pos, ss[ply - 1].currentMove, ss[ply].threatMove))
|
|
return beta - 1;
|
|
}
|
|
}
|
|
// Null move search not allowed, try razoring
|
|
else if ( !value_is_mate(beta)
|
|
&& approximateEval < beta - RazorMargin
|
|
&& depth < RazorDepth
|
|
&& (RazorAtDepthOne || depth > OnePly)
|
|
&& ttMove == MOVE_NONE
|
|
&& !pos.has_pawn_on_7th(pos.side_to_move()))
|
|
{
|
|
Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
|
|
if ( (v < beta - RazorMargin - RazorMargin / 4)
|
|
|| (depth < 3*OnePly && v < beta - RazorMargin)
|
|
|| (depth < 2*OnePly && v < beta - RazorMargin / 2))
|
|
return v;
|
|
}
|
|
|
|
// Go with internal iterative deepening if we don't have a TT move
|
|
if (UseIIDAtNonPVNodes && ttMove == MOVE_NONE && depth >= 8*OnePly &&
|
|
evaluate(pos, ei, threadID) >= beta - IIDMargin)
|
|
{
|
|
search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID);
|
|
ttMove = ss[ply].pv[ply];
|
|
}
|
|
else if (nullDrivenIID)
|
|
{
|
|
// The null move failed low due to a suspicious capture. Perhaps we
|
|
// are facing a null capture artifact due to the side to move change
|
|
// and this position should fail high. So do a normal search with a
|
|
// reduced depth to get a good ttMove to use in the following full
|
|
// depth search.
|
|
Move tm = ss[ply].threatMove;
|
|
|
|
assert(tm != MOVE_NONE);
|
|
assert(ttMove == MOVE_NONE);
|
|
|
|
search(pos, ss, beta, depth/2, ply, false, threadID);
|
|
ttMove = ss[ply].pv[ply];
|
|
ss[ply].threatMove = tm;
|
|
}
|
|
|
|
// Initialize a MovePicker object for the current position, and prepare
|
|
// to search all moves:
|
|
MovePicker mp = MovePicker(pos, false, ttMove, ss[ply], depth);
|
|
|
|
Move move, movesSearched[256];
|
|
int moveCount = 0;
|
|
Value value, bestValue = -VALUE_INFINITE;
|
|
Value futilityValue = VALUE_NONE;
|
|
bool useFutilityPruning = UseFutilityPruning
|
|
&& depth < SelectiveDepth
|
|
&& !isCheck;
|
|
|
|
// Loop through all legal moves until no moves remain or a beta cutoff
|
|
// occurs.
|
|
while ( bestValue < beta
|
|
&& (move = mp.get_next_move()) != MOVE_NONE
|
|
&& !thread_should_stop(threadID))
|
|
{
|
|
assert(move_is_ok(move));
|
|
|
|
bool singleReply = (isCheck && mp.number_of_moves() == 1);
|
|
bool moveIsCheck = pos.move_is_check(move);
|
|
bool moveIsCapture = pos.move_is_capture(move);
|
|
|
|
movesSearched[moveCount++] = ss[ply].currentMove = move;
|
|
|
|
// Decide the new search depth
|
|
bool dangerous;
|
|
Depth ext = extension(pos, move, false, moveIsCapture, moveIsCheck, singleReply, mateThreat, &dangerous);
|
|
Depth newDepth = depth - OnePly + ext;
|
|
|
|
// Futility pruning
|
|
if ( useFutilityPruning
|
|
&& !dangerous
|
|
&& !moveIsCapture
|
|
&& !move_promotion(move))
|
|
{
|
|
// History pruning. See ok_to_prune() definition
|
|
if ( moveCount >= 2 + int(depth)
|
|
&& ok_to_prune(pos, move, ss[ply].threatMove, depth))
|
|
continue;
|
|
|
|
// Value based pruning
|
|
if (depth < 7 * OnePly && approximateEval < beta)
|
|
{
|
|
if (futilityValue == VALUE_NONE)
|
|
futilityValue = evaluate(pos, ei, threadID)
|
|
+ FutilityMargins[int(depth)/2 - 1]
|
|
+ 32 * (depth & 1);
|
|
|
|
if (futilityValue < beta)
|
|
{
|
|
if (futilityValue > bestValue)
|
|
bestValue = futilityValue;
|
|
continue;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Make and search the move
|
|
UndoInfo u;
|
|
pos.do_move(move, u);
|
|
|
|
// Try to reduce non-pv search depth by one ply if move seems not problematic,
|
|
// if the move fails high will be re-searched at full depth.
|
|
if ( depth >= 2*OnePly
|
|
&& moveCount >= LMRNonPVMoves
|
|
&& !dangerous
|
|
&& !moveIsCapture
|
|
&& !move_promotion(move)
|
|
&& !move_is_castle(move)
|
|
&& !move_is_killer(move, ss[ply]))
|
|
{
|
|
ss[ply].reduction = OnePly;
|
|
value = -search(pos, ss, -(beta-1), newDepth-OnePly, ply+1, true, threadID);
|
|
}
|
|
else
|
|
value = beta; // Just to trigger next condition
|
|
|
|
if (value >= beta) // Go with full depth non-pv search
|
|
{
|
|
ss[ply].reduction = Depth(0);
|
|
value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID);
|
|
}
|
|
pos.undo_move(move);
|
|
|
|
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
|
|
|
|
// New best move?
|
|
if (value > bestValue)
|
|
{
|
|
bestValue = value;
|
|
if (value >= beta)
|
|
update_pv(ss, ply);
|
|
|
|
if (value == value_mate_in(ply + 1))
|
|
ss[ply].mateKiller = move;
|
|
}
|
|
|
|
// Split?
|
|
if ( ActiveThreads > 1
|
|
&& bestValue < beta
|
|
&& depth >= MinimumSplitDepth
|
|
&& Iteration <= 99
|
|
&& idle_thread_exists(threadID)
|
|
&& !AbortSearch
|
|
&& !thread_should_stop(threadID)
|
|
&& split(pos, ss, ply, &beta, &beta, &bestValue, depth, &moveCount,
|
|
&mp, threadID, false))
|
|
break;
|
|
}
|
|
|
|
// All legal moves have been searched. A special case: If there were
|
|
// no legal moves, it must be mate or stalemate.
|
|
if (moveCount == 0)
|
|
return (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW);
|
|
|
|
// If the search is not aborted, update the transposition table,
|
|
// history counters, and killer moves.
|
|
if (AbortSearch || thread_should_stop(threadID))
|
|
return bestValue;
|
|
|
|
if (bestValue < beta)
|
|
TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE, VALUE_TYPE_UPPER);
|
|
else
|
|
{
|
|
BetaCounter.add(pos.side_to_move(), depth, threadID);
|
|
Move m = ss[ply].pv[ply];
|
|
if (ok_to_history(pos, m)) // Only non capture moves are considered
|
|
{
|
|
update_history(pos, m, depth, movesSearched, moveCount);
|
|
update_killers(m, ss[ply]);
|
|
}
|
|
TT.store(pos, value_to_tt(bestValue, ply), depth, m, VALUE_TYPE_LOWER);
|
|
}
|
|
return bestValue;
|
|
}
|
|
|
|
|
|
// qsearch() is the quiescence search function, which is called by the main
|
|
// search function when the remaining depth is zero (or, to be more precise,
|
|
// less than OnePly).
|
|
|
|
Value qsearch(Position &pos, SearchStack ss[], Value alpha, Value beta,
|
|
Depth depth, int ply, int threadID) {
|
|
|
|
assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
|
|
assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
|
|
assert(depth <= 0);
|
|
assert(ply >= 0 && ply < PLY_MAX);
|
|
assert(threadID >= 0 && threadID < ActiveThreads);
|
|
|
|
// Initialize, and make an early exit in case of an aborted search,
|
|
// an instant draw, maximum ply reached, etc.
|
|
init_node(pos, ss, ply, threadID);
|
|
|
|
// After init_node() that calls poll()
|
|
if (AbortSearch || thread_should_stop(threadID))
|
|
return Value(0);
|
|
|
|
if (pos.is_draw())
|
|
return VALUE_DRAW;
|
|
|
|
// Transposition table lookup
|
|
const TTEntry* tte = TT.retrieve(pos);
|
|
if (tte && ok_to_use_TT(tte, depth, beta, ply))
|
|
return value_from_tt(tte->value(), ply);
|
|
|
|
// Evaluate the position statically
|
|
EvalInfo ei;
|
|
bool isCheck = pos.is_check();
|
|
Value staticValue = (isCheck ? -VALUE_INFINITE : evaluate(pos, ei, threadID));
|
|
|
|
if (ply == PLY_MAX - 1)
|
|
return evaluate(pos, ei, threadID);
|
|
|
|
// Initialize "stand pat score", and return it immediately if it is
|
|
// at least beta.
|
|
Value bestValue = staticValue;
|
|
|
|
if (bestValue >= beta)
|
|
return bestValue;
|
|
|
|
if (bestValue > alpha)
|
|
alpha = bestValue;
|
|
|
|
// Initialize a MovePicker object for the current position, and prepare
|
|
// to search the moves. Because the depth is <= 0 here, only captures,
|
|
// queen promotions and checks (only if depth == 0) will be generated.
|
|
bool pvNode = (beta - alpha != 1);
|
|
MovePicker mp = MovePicker(pos, pvNode, MOVE_NONE, EmptySearchStack, depth, isCheck ? NULL : &ei);
|
|
Move move;
|
|
int moveCount = 0;
|
|
Color us = pos.side_to_move();
|
|
bool enoughMaterial = pos.non_pawn_material(us) > RookValueMidgame;
|
|
|
|
// Loop through the moves until no moves remain or a beta cutoff
|
|
// occurs.
|
|
while ( alpha < beta
|
|
&& (move = mp.get_next_move()) != MOVE_NONE)
|
|
{
|
|
assert(move_is_ok(move));
|
|
|
|
moveCount++;
|
|
ss[ply].currentMove = move;
|
|
|
|
// Futility pruning
|
|
if ( UseQSearchFutilityPruning
|
|
&& enoughMaterial
|
|
&& !isCheck
|
|
&& !pvNode
|
|
&& !move_promotion(move)
|
|
&& !pos.move_is_check(move)
|
|
&& !pos.move_is_passed_pawn_push(move))
|
|
{
|
|
Value futilityValue = staticValue
|
|
+ Max(pos.midgame_value_of_piece_on(move_to(move)),
|
|
pos.endgame_value_of_piece_on(move_to(move)))
|
|
+ (move_is_ep(move) ? PawnValueEndgame : Value(0))
|
|
+ FutilityMarginQS
|
|
+ ei.futilityMargin;
|
|
|
|
if (futilityValue < alpha)
|
|
{
|
|
if (futilityValue > bestValue)
|
|
bestValue = futilityValue;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
// Don't search captures and checks with negative SEE values
|
|
if ( !isCheck
|
|
&& !move_promotion(move)
|
|
&& (pos.midgame_value_of_piece_on(move_from(move)) >
|
|
pos.midgame_value_of_piece_on(move_to(move)))
|
|
&& pos.see(move) < 0)
|
|
continue;
|
|
|
|
// Make and search the move.
|
|
UndoInfo u;
|
|
pos.do_move(move, u);
|
|
Value value = -qsearch(pos, ss, -beta, -alpha, depth-OnePly, ply+1, threadID);
|
|
pos.undo_move(move);
|
|
|
|
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
|
|
|
|
// New best move?
|
|
if (value > bestValue)
|
|
{
|
|
bestValue = value;
|
|
if (value > alpha)
|
|
{
|
|
alpha = value;
|
|
update_pv(ss, ply);
|
|
}
|
|
}
|
|
}
|
|
|
|
// All legal moves have been searched. A special case: If we're in check
|
|
// and no legal moves were found, it is checkmate:
|
|
if (pos.is_check() && moveCount == 0) // Mate!
|
|
return value_mated_in(ply);
|
|
|
|
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
|
|
|
|
// Update transposition table
|
|
TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE, VALUE_TYPE_EXACT);
|
|
|
|
// Update killers only for good check moves
|
|
Move m = ss[ply].currentMove;
|
|
if (alpha >= beta && ok_to_history(pos, m)) // Only non capture moves are considered
|
|
{
|
|
// Wrong to update history when depth is <= 0
|
|
update_killers(m, ss[ply]);
|
|
}
|
|
return bestValue;
|
|
}
|
|
|
|
|
|
// sp_search() is used to search from a split point. This function is called
|
|
// by each thread working at the split point. It is similar to the normal
|
|
// search() function, but simpler. Because we have already probed the hash
|
|
// table, done a null move search, and searched the first move before
|
|
// splitting, we don't have to repeat all this work in sp_search(). We
|
|
// also don't need to store anything to the hash table here: This is taken
|
|
// care of after we return from the split point.
|
|
|
|
void sp_search(SplitPoint *sp, int threadID) {
|
|
|
|
assert(threadID >= 0 && threadID < ActiveThreads);
|
|
assert(ActiveThreads > 1);
|
|
|
|
Position pos = Position(sp->pos);
|
|
SearchStack *ss = sp->sstack[threadID];
|
|
Value value;
|
|
Move move;
|
|
bool isCheck = pos.is_check();
|
|
bool useFutilityPruning = UseFutilityPruning
|
|
&& sp->depth < SelectiveDepth
|
|
&& !isCheck;
|
|
|
|
while ( sp->bestValue < sp->beta
|
|
&& !thread_should_stop(threadID)
|
|
&& (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE)
|
|
{
|
|
assert(move_is_ok(move));
|
|
|
|
bool moveIsCheck = pos.move_is_check(move);
|
|
bool moveIsCapture = pos.move_is_capture(move);
|
|
|
|
lock_grab(&(sp->lock));
|
|
int moveCount = ++sp->moves;
|
|
lock_release(&(sp->lock));
|
|
|
|
ss[sp->ply].currentMove = move;
|
|
|
|
// Decide the new search depth.
|
|
bool dangerous;
|
|
Depth ext = extension(pos, move, false, moveIsCapture, moveIsCheck, false, false, &dangerous);
|
|
Depth newDepth = sp->depth - OnePly + ext;
|
|
|
|
// Prune?
|
|
if ( useFutilityPruning
|
|
&& !dangerous
|
|
&& !moveIsCapture
|
|
&& !move_promotion(move)
|
|
&& moveCount >= 2 + int(sp->depth)
|
|
&& ok_to_prune(pos, move, ss[sp->ply].threatMove, sp->depth))
|
|
continue;
|
|
|
|
// Make and search the move.
|
|
UndoInfo u;
|
|
pos.do_move(move, u);
|
|
|
|
// Try to reduce non-pv search depth by one ply if move seems not problematic,
|
|
// if the move fails high will be re-searched at full depth.
|
|
if ( !dangerous
|
|
&& moveCount >= LMRNonPVMoves
|
|
&& !moveIsCapture
|
|
&& !move_promotion(move)
|
|
&& !move_is_castle(move)
|
|
&& !move_is_killer(move, ss[sp->ply]))
|
|
{
|
|
ss[sp->ply].reduction = OnePly;
|
|
value = -search(pos, ss, -(sp->beta-1), newDepth - OnePly, sp->ply+1, true, threadID);
|
|
}
|
|
else
|
|
value = sp->beta; // Just to trigger next condition
|
|
|
|
if (value >= sp->beta) // Go with full depth non-pv search
|
|
{
|
|
ss[sp->ply].reduction = Depth(0);
|
|
value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, true, threadID);
|
|
}
|
|
pos.undo_move(move);
|
|
|
|
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
|
|
|
|
if (thread_should_stop(threadID))
|
|
break;
|
|
|
|
// New best move?
|
|
lock_grab(&(sp->lock));
|
|
if (value > sp->bestValue && !thread_should_stop(threadID))
|
|
{
|
|
sp->bestValue = value;
|
|
if (sp->bestValue >= sp->beta)
|
|
{
|
|
sp_update_pv(sp->parentSstack, ss, sp->ply);
|
|
for (int i = 0; i < ActiveThreads; i++)
|
|
if (i != threadID && (i == sp->master || sp->slaves[i]))
|
|
Threads[i].stop = true;
|
|
|
|
sp->finished = true;
|
|
}
|
|
}
|
|
lock_release(&(sp->lock));
|
|
}
|
|
|
|
lock_grab(&(sp->lock));
|
|
|
|
// If this is the master thread and we have been asked to stop because of
|
|
// a beta cutoff higher up in the tree, stop all slave threads:
|
|
if (sp->master == threadID && thread_should_stop(threadID))
|
|
for (int i = 0; i < ActiveThreads; i++)
|
|
if (sp->slaves[i])
|
|
Threads[i].stop = true;
|
|
|
|
sp->cpus--;
|
|
sp->slaves[threadID] = 0;
|
|
|
|
lock_release(&(sp->lock));
|
|
}
|
|
|
|
|
|
// sp_search_pv() is used to search from a PV split point. This function
|
|
// is called by each thread working at the split point. It is similar to
|
|
// the normal search_pv() function, but simpler. Because we have already
|
|
// probed the hash table and searched the first move before splitting, we
|
|
// don't have to repeat all this work in sp_search_pv(). We also don't
|
|
// need to store anything to the hash table here: This is taken care of
|
|
// after we return from the split point.
|
|
|
|
void sp_search_pv(SplitPoint *sp, int threadID) {
|
|
|
|
assert(threadID >= 0 && threadID < ActiveThreads);
|
|
assert(ActiveThreads > 1);
|
|
|
|
Position pos = Position(sp->pos);
|
|
SearchStack *ss = sp->sstack[threadID];
|
|
Value value;
|
|
Move move;
|
|
|
|
while ( sp->alpha < sp->beta
|
|
&& !thread_should_stop(threadID)
|
|
&& (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE)
|
|
{
|
|
bool moveIsCheck = pos.move_is_check(move);
|
|
bool moveIsCapture = pos.move_is_capture(move);
|
|
|
|
assert(move_is_ok(move));
|
|
|
|
if (moveIsCapture)
|
|
ss[sp->ply].currentMoveCaptureValue =
|
|
move_is_ep(move)? PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move));
|
|
else
|
|
ss[sp->ply].currentMoveCaptureValue = Value(0);
|
|
|
|
lock_grab(&(sp->lock));
|
|
int moveCount = ++sp->moves;
|
|
lock_release(&(sp->lock));
|
|
|
|
ss[sp->ply].currentMove = move;
|
|
|
|
// Decide the new search depth.
|
|
bool dangerous;
|
|
Depth ext = extension(pos, move, true, moveIsCapture, moveIsCheck, false, false, &dangerous);
|
|
Depth newDepth = sp->depth - OnePly + ext;
|
|
|
|
// Make and search the move.
|
|
UndoInfo u;
|
|
pos.do_move(move, u);
|
|
|
|
// Try to reduce non-pv search depth by one ply if move seems not problematic,
|
|
// if the move fails high will be re-searched at full depth.
|
|
if ( !dangerous
|
|
&& moveCount >= LMRPVMoves
|
|
&& !moveIsCapture
|
|
&& !move_promotion(move)
|
|
&& !move_is_castle(move)
|
|
&& !move_is_killer(move, ss[sp->ply]))
|
|
{
|
|
ss[sp->ply].reduction = OnePly;
|
|
value = -search(pos, ss, -sp->alpha, newDepth - OnePly, sp->ply+1, true, threadID);
|
|
}
|
|
else
|
|
value = sp->alpha + 1; // Just to trigger next condition
|
|
|
|
if (value > sp->alpha) // Go with full depth non-pv search
|
|
{
|
|
ss[sp->ply].reduction = Depth(0);
|
|
value = -search(pos, ss, -sp->alpha, newDepth, sp->ply+1, true, threadID);
|
|
|
|
if (value > sp->alpha && value < sp->beta)
|
|
{
|
|
// When the search fails high at ply 1 while searching the first
|
|
// move at the root, set the flag failHighPly1. This is used for
|
|
// time managment: We don't want to stop the search early in
|
|
// such cases, because resolving the fail high at ply 1 could
|
|
// result in a big drop in score at the root.
|
|
if (sp->ply == 1 && RootMoveNumber == 1)
|
|
Threads[threadID].failHighPly1 = true;
|
|
|
|
value = -search_pv(pos, ss, -sp->beta, -sp->alpha, newDepth, sp->ply+1, threadID);
|
|
Threads[threadID].failHighPly1 = false;
|
|
}
|
|
}
|
|
pos.undo_move(move);
|
|
|
|
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
|
|
|
|
if (thread_should_stop(threadID))
|
|
break;
|
|
|
|
// New best move?
|
|
lock_grab(&(sp->lock));
|
|
if (value > sp->bestValue && !thread_should_stop(threadID))
|
|
{
|
|
sp->bestValue = value;
|
|
if (value > sp->alpha)
|
|
{
|
|
sp->alpha = value;
|
|
sp_update_pv(sp->parentSstack, ss, sp->ply);
|
|
if (value == value_mate_in(sp->ply + 1))
|
|
ss[sp->ply].mateKiller = move;
|
|
|
|
if(value >= sp->beta)
|
|
{
|
|
for(int i = 0; i < ActiveThreads; i++)
|
|
if(i != threadID && (i == sp->master || sp->slaves[i]))
|
|
Threads[i].stop = true;
|
|
|
|
sp->finished = true;
|
|
}
|
|
}
|
|
// If we are at ply 1, and we are searching the first root move at
|
|
// ply 0, set the 'Problem' variable if the score has dropped a lot
|
|
// (from the computer's point of view) since the previous iteration.
|
|
if ( sp->ply == 1
|
|
&& Iteration >= 2
|
|
&& -value <= ValueByIteration[Iteration-1] - ProblemMargin)
|
|
Problem = true;
|
|
}
|
|
lock_release(&(sp->lock));
|
|
}
|
|
|
|
lock_grab(&(sp->lock));
|
|
|
|
// If this is the master thread and we have been asked to stop because of
|
|
// a beta cutoff higher up in the tree, stop all slave threads.
|
|
if (sp->master == threadID && thread_should_stop(threadID))
|
|
for (int i = 0; i < ActiveThreads; i++)
|
|
if (sp->slaves[i])
|
|
Threads[i].stop = true;
|
|
|
|
sp->cpus--;
|
|
sp->slaves[threadID] = 0;
|
|
|
|
lock_release(&(sp->lock));
|
|
}
|
|
|
|
/// The BetaCounterType class
|
|
|
|
BetaCounterType::BetaCounterType() { clear(); }
|
|
|
|
void BetaCounterType::clear() {
|
|
|
|
for (int i = 0; i < THREAD_MAX; i++)
|
|
hits[i][WHITE] = hits[i][BLACK] = 0ULL;
|
|
}
|
|
|
|
void BetaCounterType::add(Color us, Depth d, int threadID) {
|
|
|
|
// Weighted count based on depth
|
|
hits[threadID][us] += int(d);
|
|
}
|
|
|
|
void BetaCounterType::read(Color us, int64_t& our, int64_t& their) {
|
|
|
|
our = their = 0UL;
|
|
for (int i = 0; i < THREAD_MAX; i++)
|
|
{
|
|
our += hits[i][us];
|
|
their += hits[i][opposite_color(us)];
|
|
}
|
|
}
|
|
|
|
|
|
/// The RootMove class
|
|
|
|
// Constructor
|
|
|
|
RootMove::RootMove() {
|
|
nodes = cumulativeNodes = 0ULL;
|
|
}
|
|
|
|
// RootMove::operator<() is the comparison function used when
|
|
// sorting the moves. A move m1 is considered to be better
|
|
// than a move m2 if it has a higher score, or if the moves
|
|
// have equal score but m1 has the higher node count.
|
|
|
|
bool RootMove::operator<(const RootMove& m) {
|
|
|
|
if (score != m.score)
|
|
return (score < m.score);
|
|
|
|
return theirBeta <= m.theirBeta;
|
|
}
|
|
|
|
/// The RootMoveList class
|
|
|
|
// Constructor
|
|
|
|
RootMoveList::RootMoveList(Position& pos, Move searchMoves[]) : count(0) {
|
|
|
|
MoveStack mlist[MaxRootMoves];
|
|
bool includeAllMoves = (searchMoves[0] == MOVE_NONE);
|
|
|
|
// Generate all legal moves
|
|
int lm_count = generate_legal_moves(pos, mlist);
|
|
|
|
// Add each move to the moves[] array
|
|
for (int i = 0; i < lm_count; i++)
|
|
{
|
|
bool includeMove = includeAllMoves;
|
|
|
|
for (int k = 0; !includeMove && searchMoves[k] != MOVE_NONE; k++)
|
|
includeMove = (searchMoves[k] == mlist[i].move);
|
|
|
|
if (includeMove)
|
|
{
|
|
// Find a quick score for the move
|
|
UndoInfo u;
|
|
SearchStack ss[PLY_MAX_PLUS_2];
|
|
|
|
moves[count].move = mlist[i].move;
|
|
moves[count].nodes = 0ULL;
|
|
pos.do_move(moves[count].move, u);
|
|
moves[count].score = -qsearch(pos, ss, -VALUE_INFINITE, VALUE_INFINITE,
|
|
Depth(0), 1, 0);
|
|
pos.undo_move(moves[count].move);
|
|
moves[count].pv[0] = moves[i].move;
|
|
moves[count].pv[1] = MOVE_NONE; // FIXME
|
|
count++;
|
|
}
|
|
}
|
|
sort();
|
|
}
|
|
|
|
|
|
// Simple accessor methods for the RootMoveList class
|
|
|
|
inline Move RootMoveList::get_move(int moveNum) const {
|
|
return moves[moveNum].move;
|
|
}
|
|
|
|
inline Value RootMoveList::get_move_score(int moveNum) const {
|
|
return moves[moveNum].score;
|
|
}
|
|
|
|
inline void RootMoveList::set_move_score(int moveNum, Value score) {
|
|
moves[moveNum].score = score;
|
|
}
|
|
|
|
inline void RootMoveList::set_move_nodes(int moveNum, int64_t nodes) {
|
|
moves[moveNum].nodes = nodes;
|
|
moves[moveNum].cumulativeNodes += nodes;
|
|
}
|
|
|
|
inline void RootMoveList::set_beta_counters(int moveNum, int64_t our, int64_t their) {
|
|
moves[moveNum].ourBeta = our;
|
|
moves[moveNum].theirBeta = their;
|
|
}
|
|
|
|
void RootMoveList::set_move_pv(int moveNum, const Move pv[]) {
|
|
int j;
|
|
for(j = 0; pv[j] != MOVE_NONE; j++)
|
|
moves[moveNum].pv[j] = pv[j];
|
|
moves[moveNum].pv[j] = MOVE_NONE;
|
|
}
|
|
|
|
inline Move RootMoveList::get_move_pv(int moveNum, int i) const {
|
|
return moves[moveNum].pv[i];
|
|
}
|
|
|
|
inline int64_t RootMoveList::get_move_cumulative_nodes(int moveNum) const {
|
|
return moves[moveNum].cumulativeNodes;
|
|
}
|
|
|
|
inline int RootMoveList::move_count() const {
|
|
return count;
|
|
}
|
|
|
|
|
|
// RootMoveList::scan_for_easy_move() is called at the end of the first
|
|
// iteration, and is used to detect an "easy move", i.e. a move which appears
|
|
// to be much bester than all the rest. If an easy move is found, the move
|
|
// is returned, otherwise the function returns MOVE_NONE. It is very
|
|
// important that this function is called at the right moment: The code
|
|
// assumes that the first iteration has been completed and the moves have
|
|
// been sorted. This is done in RootMoveList c'tor.
|
|
|
|
Move RootMoveList::scan_for_easy_move() const {
|
|
|
|
assert(count);
|
|
|
|
if (count == 1)
|
|
return get_move(0);
|
|
|
|
// moves are sorted so just consider the best and the second one
|
|
if (get_move_score(0) > get_move_score(1) + EasyMoveMargin)
|
|
return get_move(0);
|
|
|
|
return MOVE_NONE;
|
|
}
|
|
|
|
// RootMoveList::sort() sorts the root move list at the beginning of a new
|
|
// iteration.
|
|
|
|
inline void RootMoveList::sort() {
|
|
|
|
sort_multipv(count - 1); // all items
|
|
}
|
|
|
|
|
|
// RootMoveList::sort_multipv() sorts the first few moves in the root move
|
|
// list by their scores and depths. It is used to order the different PVs
|
|
// correctly in MultiPV mode.
|
|
|
|
void RootMoveList::sort_multipv(int n) {
|
|
|
|
for (int i = 1; i <= n; i++)
|
|
{
|
|
RootMove rm = moves[i];
|
|
int j;
|
|
for (j = i; j > 0 && moves[j-1] < rm; j--)
|
|
moves[j] = moves[j-1];
|
|
moves[j] = rm;
|
|
}
|
|
}
|
|
|
|
|
|
// init_search_stack() initializes a search stack at the beginning of a
|
|
// new search from the root.
|
|
void init_search_stack(SearchStack& ss) {
|
|
|
|
ss.pv[0] = MOVE_NONE;
|
|
ss.pv[1] = MOVE_NONE;
|
|
ss.currentMove = MOVE_NONE;
|
|
ss.threatMove = MOVE_NONE;
|
|
ss.reduction = Depth(0);
|
|
for (int j = 0; j < KILLER_MAX; j++)
|
|
ss.killers[j] = MOVE_NONE;
|
|
}
|
|
|
|
void init_search_stack(SearchStack ss[]) {
|
|
|
|
for (int i = 0; i < 3; i++)
|
|
{
|
|
ss[i].pv[i] = MOVE_NONE;
|
|
ss[i].pv[i+1] = MOVE_NONE;
|
|
ss[i].currentMove = MOVE_NONE;
|
|
ss[i].threatMove = MOVE_NONE;
|
|
ss[i].reduction = Depth(0);
|
|
for (int j = 0; j < KILLER_MAX; j++)
|
|
ss[i].killers[j] = MOVE_NONE;
|
|
}
|
|
}
|
|
|
|
|
|
// init_node() is called at the beginning of all the search functions
|
|
// (search(), search_pv(), qsearch(), and so on) and initializes the search
|
|
// stack object corresponding to the current node. Once every
|
|
// NodesBetweenPolls nodes, init_node() also calls poll(), which polls
|
|
// for user input and checks whether it is time to stop the search.
|
|
|
|
void init_node(const Position &pos, SearchStack ss[], int ply, int threadID) {
|
|
assert(ply >= 0 && ply < PLY_MAX);
|
|
assert(threadID >= 0 && threadID < ActiveThreads);
|
|
|
|
Threads[threadID].nodes++;
|
|
|
|
if(threadID == 0) {
|
|
NodesSincePoll++;
|
|
if(NodesSincePoll >= NodesBetweenPolls) {
|
|
poll();
|
|
NodesSincePoll = 0;
|
|
}
|
|
}
|
|
ss[ply].pv[ply] = ss[ply].pv[ply+1] = ss[ply].currentMove = MOVE_NONE;
|
|
ss[ply+2].mateKiller = MOVE_NONE;
|
|
ss[ply].threatMove = MOVE_NONE;
|
|
ss[ply].reduction = Depth(0);
|
|
ss[ply].currentMoveCaptureValue = Value(0);
|
|
for (int j = 0; j < KILLER_MAX; j++)
|
|
ss[ply+2].killers[j] = MOVE_NONE;
|
|
|
|
if(Threads[threadID].printCurrentLine)
|
|
print_current_line(ss, ply, threadID);
|
|
}
|
|
|
|
|
|
// update_pv() is called whenever a search returns a value > alpha. It
|
|
// updates the PV in the SearchStack object corresponding to the current
|
|
// node.
|
|
|
|
void update_pv(SearchStack ss[], int ply) {
|
|
assert(ply >= 0 && ply < PLY_MAX);
|
|
|
|
ss[ply].pv[ply] = ss[ply].currentMove;
|
|
int p;
|
|
for(p = ply + 1; ss[ply+1].pv[p] != MOVE_NONE; p++)
|
|
ss[ply].pv[p] = ss[ply+1].pv[p];
|
|
ss[ply].pv[p] = MOVE_NONE;
|
|
}
|
|
|
|
|
|
// sp_update_pv() is a variant of update_pv for use at split points. The
|
|
// difference between the two functions is that sp_update_pv also updates
|
|
// the PV at the parent node.
|
|
|
|
void sp_update_pv(SearchStack *pss, SearchStack ss[], int ply) {
|
|
assert(ply >= 0 && ply < PLY_MAX);
|
|
|
|
ss[ply].pv[ply] = pss[ply].pv[ply] = ss[ply].currentMove;
|
|
int p;
|
|
for(p = ply + 1; ss[ply+1].pv[p] != MOVE_NONE; p++)
|
|
ss[ply].pv[p] = pss[ply].pv[p] = ss[ply+1].pv[p];
|
|
ss[ply].pv[p] = pss[ply].pv[p] = MOVE_NONE;
|
|
}
|
|
|
|
|
|
// connected_moves() tests whether two moves are 'connected' in the sense
|
|
// that the first move somehow made the second move possible (for instance
|
|
// if the moving piece is the same in both moves). The first move is
|
|
// assumed to be the move that was made to reach the current position, while
|
|
// the second move is assumed to be a move from the current position.
|
|
|
|
bool connected_moves(const Position &pos, Move m1, Move m2) {
|
|
Square f1, t1, f2, t2;
|
|
|
|
assert(move_is_ok(m1));
|
|
assert(move_is_ok(m2));
|
|
|
|
if(m2 == MOVE_NONE)
|
|
return false;
|
|
|
|
// Case 1: The moving piece is the same in both moves.
|
|
f2 = move_from(m2);
|
|
t1 = move_to(m1);
|
|
if(f2 == t1)
|
|
return true;
|
|
|
|
// Case 2: The destination square for m2 was vacated by m1.
|
|
t2 = move_to(m2);
|
|
f1 = move_from(m1);
|
|
if(t2 == f1)
|
|
return true;
|
|
|
|
// Case 3: Moving through the vacated square:
|
|
if(piece_is_slider(pos.piece_on(f2)) &&
|
|
bit_is_set(squares_between(f2, t2), f1))
|
|
return true;
|
|
|
|
// Case 4: The destination square for m2 is attacked by the moving piece
|
|
// in m1:
|
|
if(pos.piece_attacks_square(pos.piece_on(t1), t1, t2))
|
|
return true;
|
|
|
|
// Case 5: Discovered check, checking piece is the piece moved in m1:
|
|
if(piece_is_slider(pos.piece_on(t1)) &&
|
|
bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())),
|
|
f2) &&
|
|
!bit_is_set(squares_between(t2, pos.king_square(pos.side_to_move())),
|
|
t2)) {
|
|
Bitboard occ = pos.occupied_squares();
|
|
Color us = pos.side_to_move();
|
|
Square ksq = pos.king_square(us);
|
|
clear_bit(&occ, f2);
|
|
if(pos.type_of_piece_on(t1) == BISHOP) {
|
|
if(bit_is_set(bishop_attacks_bb(ksq, occ), t1))
|
|
return true;
|
|
}
|
|
else if(pos.type_of_piece_on(t1) == ROOK) {
|
|
if(bit_is_set(rook_attacks_bb(ksq, occ), t1))
|
|
return true;
|
|
}
|
|
else {
|
|
assert(pos.type_of_piece_on(t1) == QUEEN);
|
|
if(bit_is_set(queen_attacks_bb(ksq, occ), t1))
|
|
return true;
|
|
}
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
|
|
// value_is_mate() checks if the given value is a mate one
|
|
// eventually compensated for the ply.
|
|
|
|
bool value_is_mate(Value value) {
|
|
|
|
assert(abs(value) <= VALUE_INFINITE);
|
|
|
|
return value <= value_mated_in(PLY_MAX)
|
|
|| value >= value_mate_in(PLY_MAX);
|
|
}
|
|
|
|
|
|
// move_is_killer() checks if the given move is among the
|
|
// killer moves of that ply.
|
|
|
|
bool move_is_killer(Move m, const SearchStack& ss) {
|
|
|
|
const Move* k = ss.killers;
|
|
for (int i = 0; i < KILLER_MAX; i++, k++)
|
|
if (*k == m)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
|
|
// extension() decides whether a move should be searched with normal depth,
|
|
// or with extended depth. Certain classes of moves (checking moves, in
|
|
// particular) are searched with bigger depth than ordinary moves and in
|
|
// any case are marked as 'dangerous'. Note that also if a move is not
|
|
// extended, as example because the corresponding UCI option is set to zero,
|
|
// the move is marked as 'dangerous' so, at least, we avoid to prune it.
|
|
|
|
Depth extension(const Position& pos, Move m, bool pvNode, bool capture, bool check,
|
|
bool singleReply, bool mateThreat, bool* dangerous) {
|
|
|
|
assert(m != MOVE_NONE);
|
|
|
|
Depth result = Depth(0);
|
|
*dangerous = check || singleReply || mateThreat;
|
|
|
|
if (check)
|
|
result += CheckExtension[pvNode];
|
|
|
|
if (singleReply)
|
|
result += SingleReplyExtension[pvNode];
|
|
|
|
if (mateThreat)
|
|
result += MateThreatExtension[pvNode];
|
|
|
|
if (pos.type_of_piece_on(move_from(m)) == PAWN)
|
|
{
|
|
if (pos.move_is_pawn_push_to_7th(m))
|
|
{
|
|
result += PawnPushTo7thExtension[pvNode];
|
|
*dangerous = true;
|
|
}
|
|
if (pos.move_is_passed_pawn_push(m))
|
|
{
|
|
result += PassedPawnExtension[pvNode];
|
|
*dangerous = true;
|
|
}
|
|
}
|
|
|
|
if ( capture
|
|
&& pos.type_of_piece_on(move_to(m)) != PAWN
|
|
&& ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK)
|
|
- pos.midgame_value_of_piece_on(move_to(m)) == Value(0))
|
|
&& !move_promotion(m)
|
|
&& !move_is_ep(m))
|
|
{
|
|
result += PawnEndgameExtension[pvNode];
|
|
*dangerous = true;
|
|
}
|
|
|
|
if ( pvNode
|
|
&& capture
|
|
&& pos.type_of_piece_on(move_to(m)) != PAWN
|
|
&& pos.see(m) >= 0)
|
|
{
|
|
result += OnePly/2;
|
|
*dangerous = true;
|
|
}
|
|
|
|
return Min(result, OnePly);
|
|
}
|
|
|
|
|
|
// ok_to_do_nullmove() looks at the current position and decides whether
|
|
// doing a 'null move' should be allowed. In order to avoid zugzwang
|
|
// problems, null moves are not allowed when the side to move has very
|
|
// little material left. Currently, the test is a bit too simple: Null
|
|
// moves are avoided only when the side to move has only pawns left. It's
|
|
// probably a good idea to avoid null moves in at least some more
|
|
// complicated endgames, e.g. KQ vs KR. FIXME
|
|
|
|
bool ok_to_do_nullmove(const Position &pos) {
|
|
if(pos.non_pawn_material(pos.side_to_move()) == Value(0))
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
|
|
// ok_to_prune() tests whether it is safe to forward prune a move. Only
|
|
// non-tactical moves late in the move list close to the leaves are
|
|
// candidates for pruning.
|
|
|
|
bool ok_to_prune(const Position &pos, Move m, Move threat, Depth d) {
|
|
Square mfrom, mto, tfrom, tto;
|
|
|
|
assert(move_is_ok(m));
|
|
assert(threat == MOVE_NONE || move_is_ok(threat));
|
|
assert(!move_promotion(m));
|
|
assert(!pos.move_is_check(m));
|
|
assert(!pos.move_is_capture(m));
|
|
assert(!pos.move_is_passed_pawn_push(m));
|
|
assert(d >= OnePly);
|
|
|
|
mfrom = move_from(m);
|
|
mto = move_to(m);
|
|
tfrom = move_from(threat);
|
|
tto = move_to(threat);
|
|
|
|
// Case 1: Castling moves are never pruned.
|
|
if (move_is_castle(m))
|
|
return false;
|
|
|
|
// Case 2: Don't prune moves which move the threatened piece
|
|
if (!PruneEscapeMoves && threat != MOVE_NONE && mfrom == tto)
|
|
return false;
|
|
|
|
// Case 3: If the threatened piece has value less than or equal to the
|
|
// value of the threatening piece, don't prune move which defend it.
|
|
if ( !PruneDefendingMoves
|
|
&& threat != MOVE_NONE
|
|
&& pos.move_is_capture(threat)
|
|
&& ( pos.midgame_value_of_piece_on(tfrom) >= pos.midgame_value_of_piece_on(tto)
|
|
|| pos.type_of_piece_on(tfrom) == KING)
|
|
&& pos.move_attacks_square(m, tto))
|
|
return false;
|
|
|
|
// Case 4: Don't prune moves with good history.
|
|
if (!H.ok_to_prune(pos.piece_on(move_from(m)), m, d))
|
|
return false;
|
|
|
|
// Case 5: If the moving piece in the threatened move is a slider, don't
|
|
// prune safe moves which block its ray.
|
|
if ( !PruneBlockingMoves
|
|
&& threat != MOVE_NONE
|
|
&& piece_is_slider(pos.piece_on(tfrom))
|
|
&& bit_is_set(squares_between(tfrom, tto), mto)
|
|
&& pos.see(m) >= 0)
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
|
|
// ok_to_use_TT() returns true if a transposition table score
|
|
// can be used at a given point in search.
|
|
|
|
bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply) {
|
|
|
|
Value v = value_from_tt(tte->value(), ply);
|
|
|
|
return ( tte->depth() >= depth
|
|
|| v >= Max(value_mate_in(100), beta)
|
|
|| v < Min(value_mated_in(100), beta))
|
|
|
|
&& ( (is_lower_bound(tte->type()) && v >= beta)
|
|
|| (is_upper_bound(tte->type()) && v < beta));
|
|
}
|
|
|
|
|
|
// ok_to_history() returns true if a move m can be stored
|
|
// in history. Should be a non capturing move nor a promotion.
|
|
|
|
bool ok_to_history(const Position& pos, Move m) {
|
|
|
|
return !pos.move_is_capture(m) && !move_promotion(m);
|
|
}
|
|
|
|
|
|
// update_history() registers a good move that produced a beta-cutoff
|
|
// in history and marks as failures all the other moves of that ply.
|
|
|
|
void update_history(const Position& pos, Move m, Depth depth,
|
|
Move movesSearched[], int moveCount) {
|
|
|
|
H.success(pos.piece_on(move_from(m)), m, depth);
|
|
|
|
for (int i = 0; i < moveCount - 1; i++)
|
|
{
|
|
assert(m != movesSearched[i]);
|
|
if (ok_to_history(pos, movesSearched[i]))
|
|
H.failure(pos.piece_on(move_from(movesSearched[i])), movesSearched[i]);
|
|
}
|
|
}
|
|
|
|
|
|
// update_killers() add a good move that produced a beta-cutoff
|
|
// among the killer moves of that ply.
|
|
|
|
void update_killers(Move m, SearchStack& ss) {
|
|
|
|
if (m == ss.killers[0])
|
|
return;
|
|
|
|
for (int i = KILLER_MAX - 1; i > 0; i--)
|
|
ss.killers[i] = ss.killers[i - 1];
|
|
|
|
ss.killers[0] = m;
|
|
}
|
|
|
|
// fail_high_ply_1() checks if some thread is currently resolving a fail
|
|
// high at ply 1 at the node below the first root node. This information
|
|
// is used for time managment.
|
|
|
|
bool fail_high_ply_1() {
|
|
for(int i = 0; i < ActiveThreads; i++)
|
|
if(Threads[i].failHighPly1)
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
|
|
// current_search_time() returns the number of milliseconds which have passed
|
|
// since the beginning of the current search.
|
|
|
|
int current_search_time() {
|
|
return get_system_time() - SearchStartTime;
|
|
}
|
|
|
|
|
|
// nps() computes the current nodes/second count.
|
|
|
|
int nps() {
|
|
int t = current_search_time();
|
|
return (t > 0)? int((nodes_searched() * 1000) / t) : 0;
|
|
}
|
|
|
|
|
|
// poll() performs two different functions: It polls for user input, and it
|
|
// looks at the time consumed so far and decides if it's time to abort the
|
|
// search.
|
|
|
|
void poll() {
|
|
|
|
static int lastInfoTime;
|
|
int t = current_search_time();
|
|
|
|
// Poll for input
|
|
if (Bioskey())
|
|
{
|
|
// We are line oriented, don't read single chars
|
|
std::string command;
|
|
if (!std::getline(std::cin, command))
|
|
command = "quit";
|
|
|
|
if (command == "quit")
|
|
{
|
|
AbortSearch = true;
|
|
PonderSearch = false;
|
|
Quit = true;
|
|
}
|
|
else if(command == "stop")
|
|
{
|
|
AbortSearch = true;
|
|
PonderSearch = false;
|
|
}
|
|
else if(command == "ponderhit")
|
|
ponderhit();
|
|
}
|
|
// Print search information
|
|
if (t < 1000)
|
|
lastInfoTime = 0;
|
|
|
|
else if (lastInfoTime > t)
|
|
// HACK: Must be a new search where we searched less than
|
|
// NodesBetweenPolls nodes during the first second of search.
|
|
lastInfoTime = 0;
|
|
|
|
else if (t - lastInfoTime >= 1000)
|
|
{
|
|
lastInfoTime = t;
|
|
lock_grab(&IOLock);
|
|
if (dbg_show_mean)
|
|
dbg_print_mean();
|
|
|
|
if (dbg_show_hit_rate)
|
|
dbg_print_hit_rate();
|
|
|
|
std::cout << "info nodes " << nodes_searched() << " nps " << nps()
|
|
<< " time " << t << " hashfull " << TT.full() << std::endl;
|
|
lock_release(&IOLock);
|
|
if (ShowCurrentLine)
|
|
Threads[0].printCurrentLine = true;
|
|
}
|
|
// Should we stop the search?
|
|
if (PonderSearch)
|
|
return;
|
|
|
|
bool overTime = t > AbsoluteMaxSearchTime
|
|
|| (RootMoveNumber == 1 && t > MaxSearchTime + ExtraSearchTime)
|
|
|| ( !FailHigh && !fail_high_ply_1() && !Problem
|
|
&& t > 6*(MaxSearchTime + ExtraSearchTime));
|
|
|
|
if ( (Iteration >= 2 && (!InfiniteSearch && overTime))
|
|
|| (ExactMaxTime && t >= ExactMaxTime)
|
|
|| (Iteration >= 3 && MaxNodes && nodes_searched() >= MaxNodes))
|
|
AbortSearch = true;
|
|
}
|
|
|
|
|
|
// ponderhit() is called when the program is pondering (i.e. thinking while
|
|
// it's the opponent's turn to move) in order to let the engine know that
|
|
// it correctly predicted the opponent's move.
|
|
|
|
void ponderhit() {
|
|
int t = current_search_time();
|
|
PonderSearch = false;
|
|
if(Iteration >= 2 &&
|
|
(!InfiniteSearch && (StopOnPonderhit ||
|
|
t > AbsoluteMaxSearchTime ||
|
|
(RootMoveNumber == 1 &&
|
|
t > MaxSearchTime + ExtraSearchTime) ||
|
|
(!FailHigh && !fail_high_ply_1() && !Problem &&
|
|
t > 6*(MaxSearchTime + ExtraSearchTime)))))
|
|
AbortSearch = true;
|
|
}
|
|
|
|
|
|
// print_current_line() prints the current line of search for a given
|
|
// thread. Called when the UCI option UCI_ShowCurrLine is 'true'.
|
|
|
|
void print_current_line(SearchStack ss[], int ply, int threadID) {
|
|
assert(ply >= 0 && ply < PLY_MAX);
|
|
assert(threadID >= 0 && threadID < ActiveThreads);
|
|
|
|
if(!Threads[threadID].idle) {
|
|
lock_grab(&IOLock);
|
|
std::cout << "info currline " << (threadID + 1);
|
|
for(int p = 0; p < ply; p++)
|
|
std::cout << " " << ss[p].currentMove;
|
|
std::cout << std::endl;
|
|
lock_release(&IOLock);
|
|
}
|
|
Threads[threadID].printCurrentLine = false;
|
|
if(threadID + 1 < ActiveThreads)
|
|
Threads[threadID + 1].printCurrentLine = true;
|
|
}
|
|
|
|
|
|
// wait_for_stop_or_ponderhit() is called when the maximum depth is reached
|
|
// while the program is pondering. The point is to work around a wrinkle in
|
|
// the UCI protocol: When pondering, the engine is not allowed to give a
|
|
// "bestmove" before the GUI sends it a "stop" or "ponderhit" command.
|
|
// We simply wait here until one of these commands is sent, and return,
|
|
// after which the bestmove and pondermove will be printed (in id_loop()).
|
|
|
|
void wait_for_stop_or_ponderhit() {
|
|
std::string command;
|
|
|
|
while(true) {
|
|
if(!std::getline(std::cin, command))
|
|
command = "quit";
|
|
|
|
if(command == "quit") {
|
|
OpeningBook.close();
|
|
stop_threads();
|
|
quit_eval();
|
|
exit(0);
|
|
}
|
|
else if(command == "ponderhit" || command == "stop")
|
|
break;
|
|
}
|
|
}
|
|
|
|
|
|
// idle_loop() is where the threads are parked when they have no work to do.
|
|
// The parameter "waitSp", if non-NULL, is a pointer to an active SplitPoint
|
|
// object for which the current thread is the master.
|
|
|
|
void idle_loop(int threadID, SplitPoint *waitSp) {
|
|
assert(threadID >= 0 && threadID < THREAD_MAX);
|
|
|
|
Threads[threadID].running = true;
|
|
|
|
while(true) {
|
|
if(AllThreadsShouldExit && threadID != 0)
|
|
break;
|
|
|
|
// If we are not thinking, wait for a condition to be signaled instead
|
|
// of wasting CPU time polling for work:
|
|
while(threadID != 0 && (Idle || threadID >= ActiveThreads)) {
|
|
#if !defined(_MSC_VER)
|
|
pthread_mutex_lock(&WaitLock);
|
|
if(Idle || threadID >= ActiveThreads)
|
|
pthread_cond_wait(&WaitCond, &WaitLock);
|
|
pthread_mutex_unlock(&WaitLock);
|
|
#else
|
|
WaitForSingleObject(SitIdleEvent[threadID], INFINITE);
|
|
#endif
|
|
}
|
|
|
|
// If this thread has been assigned work, launch a search:
|
|
if(Threads[threadID].workIsWaiting) {
|
|
Threads[threadID].workIsWaiting = false;
|
|
if(Threads[threadID].splitPoint->pvNode)
|
|
sp_search_pv(Threads[threadID].splitPoint, threadID);
|
|
else
|
|
sp_search(Threads[threadID].splitPoint, threadID);
|
|
Threads[threadID].idle = true;
|
|
}
|
|
|
|
// If this thread is the master of a split point and all threads have
|
|
// finished their work at this split point, return from the idle loop:
|
|
if(waitSp != NULL && waitSp->cpus == 0)
|
|
return;
|
|
}
|
|
|
|
Threads[threadID].running = false;
|
|
}
|
|
|
|
|
|
// init_split_point_stack() is called during program initialization, and
|
|
// initializes all split point objects.
|
|
|
|
void init_split_point_stack() {
|
|
for(int i = 0; i < THREAD_MAX; i++)
|
|
for(int j = 0; j < MaxActiveSplitPoints; j++) {
|
|
SplitPointStack[i][j].parent = NULL;
|
|
lock_init(&(SplitPointStack[i][j].lock), NULL);
|
|
}
|
|
}
|
|
|
|
|
|
// destroy_split_point_stack() is called when the program exits, and
|
|
// destroys all locks in the precomputed split point objects.
|
|
|
|
void destroy_split_point_stack() {
|
|
for(int i = 0; i < THREAD_MAX; i++)
|
|
for(int j = 0; j < MaxActiveSplitPoints; j++)
|
|
lock_destroy(&(SplitPointStack[i][j].lock));
|
|
}
|
|
|
|
|
|
// thread_should_stop() checks whether the thread with a given threadID has
|
|
// been asked to stop, directly or indirectly. This can happen if a beta
|
|
// cutoff has occured in thre thread's currently active split point, or in
|
|
// some ancestor of the current split point.
|
|
|
|
bool thread_should_stop(int threadID) {
|
|
assert(threadID >= 0 && threadID < ActiveThreads);
|
|
|
|
SplitPoint *sp;
|
|
|
|
if(Threads[threadID].stop)
|
|
return true;
|
|
if(ActiveThreads <= 2)
|
|
return false;
|
|
for(sp = Threads[threadID].splitPoint; sp != NULL; sp = sp->parent)
|
|
if(sp->finished) {
|
|
Threads[threadID].stop = true;
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
|
|
// thread_is_available() checks whether the thread with threadID "slave" is
|
|
// available to help the thread with threadID "master" at a split point. An
|
|
// obvious requirement is that "slave" must be idle. With more than two
|
|
// threads, this is not by itself sufficient: If "slave" is the master of
|
|
// some active split point, it is only available as a slave to the other
|
|
// threads which are busy searching the split point at the top of "slave"'s
|
|
// split point stack (the "helpful master concept" in YBWC terminology).
|
|
|
|
bool thread_is_available(int slave, int master) {
|
|
assert(slave >= 0 && slave < ActiveThreads);
|
|
assert(master >= 0 && master < ActiveThreads);
|
|
assert(ActiveThreads > 1);
|
|
|
|
if(!Threads[slave].idle || slave == master)
|
|
return false;
|
|
|
|
if(Threads[slave].activeSplitPoints == 0)
|
|
// No active split points means that the thread is available as a slave
|
|
// for any other thread.
|
|
return true;
|
|
|
|
if(ActiveThreads == 2)
|
|
return true;
|
|
|
|
// Apply the "helpful master" concept if possible.
|
|
if(SplitPointStack[slave][Threads[slave].activeSplitPoints-1].slaves[master])
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
|
|
// idle_thread_exists() tries to find an idle thread which is available as
|
|
// a slave for the thread with threadID "master".
|
|
|
|
bool idle_thread_exists(int master) {
|
|
assert(master >= 0 && master < ActiveThreads);
|
|
assert(ActiveThreads > 1);
|
|
|
|
for(int i = 0; i < ActiveThreads; i++)
|
|
if(thread_is_available(i, master))
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
|
|
// split() does the actual work of distributing the work at a node between
|
|
// several threads at PV nodes. If it does not succeed in splitting the
|
|
// node (because no idle threads are available, or because we have no unused
|
|
// split point objects), the function immediately returns false. If
|
|
// splitting is possible, a SplitPoint object is initialized with all the
|
|
// data that must be copied to the helper threads (the current position and
|
|
// search stack, alpha, beta, the search depth, etc.), and we tell our
|
|
// helper threads that they have been assigned work. This will cause them
|
|
// to instantly leave their idle loops and call sp_search_pv(). When all
|
|
// threads have returned from sp_search_pv (or, equivalently, when
|
|
// splitPoint->cpus becomes 0), split() returns true.
|
|
|
|
bool split(const Position &p, SearchStack *sstck, int ply,
|
|
Value *alpha, Value *beta, Value *bestValue,
|
|
Depth depth, int *moves, MovePicker *mp, int master, bool pvNode) {
|
|
assert(p.is_ok());
|
|
assert(sstck != NULL);
|
|
assert(ply >= 0 && ply < PLY_MAX);
|
|
assert(*bestValue >= -VALUE_INFINITE && *bestValue <= *alpha);
|
|
assert(!pvNode || *alpha < *beta);
|
|
assert(*beta <= VALUE_INFINITE);
|
|
assert(depth > Depth(0));
|
|
assert(master >= 0 && master < ActiveThreads);
|
|
assert(ActiveThreads > 1);
|
|
|
|
SplitPoint *splitPoint;
|
|
int i;
|
|
|
|
lock_grab(&MPLock);
|
|
|
|
// If no other thread is available to help us, or if we have too many
|
|
// active split points, don't split:
|
|
if(!idle_thread_exists(master) ||
|
|
Threads[master].activeSplitPoints >= MaxActiveSplitPoints) {
|
|
lock_release(&MPLock);
|
|
return false;
|
|
}
|
|
|
|
// Pick the next available split point object from the split point stack:
|
|
splitPoint = SplitPointStack[master] + Threads[master].activeSplitPoints;
|
|
Threads[master].activeSplitPoints++;
|
|
|
|
// Initialize the split point object:
|
|
splitPoint->parent = Threads[master].splitPoint;
|
|
splitPoint->finished = false;
|
|
splitPoint->ply = ply;
|
|
splitPoint->depth = depth;
|
|
splitPoint->alpha = pvNode? *alpha : (*beta - 1);
|
|
splitPoint->beta = *beta;
|
|
splitPoint->pvNode = pvNode;
|
|
splitPoint->bestValue = *bestValue;
|
|
splitPoint->master = master;
|
|
splitPoint->mp = mp;
|
|
splitPoint->moves = *moves;
|
|
splitPoint->cpus = 1;
|
|
splitPoint->pos.copy(p);
|
|
splitPoint->parentSstack = sstck;
|
|
for(i = 0; i < ActiveThreads; i++)
|
|
splitPoint->slaves[i] = 0;
|
|
|
|
// Copy the current position and the search stack to the master thread:
|
|
memcpy(splitPoint->sstack[master], sstck, (ply+1)*sizeof(SearchStack));
|
|
Threads[master].splitPoint = splitPoint;
|
|
|
|
// Make copies of the current position and search stack for each thread:
|
|
for(i = 0; i < ActiveThreads && splitPoint->cpus < MaxThreadsPerSplitPoint;
|
|
i++)
|
|
if(thread_is_available(i, master)) {
|
|
memcpy(splitPoint->sstack[i], sstck, (ply+1)*sizeof(SearchStack));
|
|
Threads[i].splitPoint = splitPoint;
|
|
splitPoint->slaves[i] = 1;
|
|
splitPoint->cpus++;
|
|
}
|
|
|
|
// Tell the threads that they have work to do. This will make them leave
|
|
// their idle loop.
|
|
for(i = 0; i < ActiveThreads; i++)
|
|
if(i == master || splitPoint->slaves[i]) {
|
|
Threads[i].workIsWaiting = true;
|
|
Threads[i].idle = false;
|
|
Threads[i].stop = false;
|
|
}
|
|
|
|
lock_release(&MPLock);
|
|
|
|
// Everything is set up. The master thread enters the idle loop, from
|
|
// which it will instantly launch a search, because its workIsWaiting
|
|
// slot is 'true'. We send the split point as a second parameter to the
|
|
// idle loop, which means that the main thread will return from the idle
|
|
// loop when all threads have finished their work at this split point
|
|
// (i.e. when // splitPoint->cpus == 0).
|
|
idle_loop(master, splitPoint);
|
|
|
|
// We have returned from the idle loop, which means that all threads are
|
|
// finished. Update alpha, beta and bestvalue, and return:
|
|
lock_grab(&MPLock);
|
|
if(pvNode) *alpha = splitPoint->alpha;
|
|
*beta = splitPoint->beta;
|
|
*bestValue = splitPoint->bestValue;
|
|
Threads[master].stop = false;
|
|
Threads[master].idle = false;
|
|
Threads[master].activeSplitPoints--;
|
|
Threads[master].splitPoint = splitPoint->parent;
|
|
lock_release(&MPLock);
|
|
|
|
return true;
|
|
}
|
|
|
|
|
|
// wake_sleeping_threads() wakes up all sleeping threads when it is time
|
|
// to start a new search from the root.
|
|
|
|
void wake_sleeping_threads() {
|
|
if(ActiveThreads > 1) {
|
|
for(int i = 1; i < ActiveThreads; i++) {
|
|
Threads[i].idle = true;
|
|
Threads[i].workIsWaiting = false;
|
|
}
|
|
#if !defined(_MSC_VER)
|
|
pthread_mutex_lock(&WaitLock);
|
|
pthread_cond_broadcast(&WaitCond);
|
|
pthread_mutex_unlock(&WaitLock);
|
|
#else
|
|
for(int i = 1; i < THREAD_MAX; i++)
|
|
SetEvent(SitIdleEvent[i]);
|
|
#endif
|
|
}
|
|
}
|
|
|
|
|
|
// init_thread() is the function which is called when a new thread is
|
|
// launched. It simply calls the idle_loop() function with the supplied
|
|
// threadID. There are two versions of this function; one for POSIX threads
|
|
// and one for Windows threads.
|
|
|
|
#if !defined(_MSC_VER)
|
|
|
|
void *init_thread(void *threadID) {
|
|
idle_loop(*(int *)threadID, NULL);
|
|
return NULL;
|
|
}
|
|
|
|
#else
|
|
|
|
DWORD WINAPI init_thread(LPVOID threadID) {
|
|
idle_loop(*(int *)threadID, NULL);
|
|
return NULL;
|
|
}
|
|
|
|
#endif
|
|
|
|
}
|