/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <algorithm>
#include <cassert>
#include <cmath>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <sstream>
-#include <vector>
-#include <algorithm>
#include "book.h"
#include "evaluate.h"
#include "history.h"
-#include "misc.h"
-#include "move.h"
#include "movegen.h"
#include "movepick.h"
#include "search.h"
#include "tt.h"
#include "ucioption.h"
+namespace Search {
+
+ volatile SignalsType Signals;
+ LimitsType Limits;
+ std::vector<RootMove> RootMoves;
+ Position RootPosition;
+ Time SearchTime;
+}
+
+using std::string;
using std::cout;
using std::endl;
-using std::string;
+using Eval::evaluate;
+using namespace Search;
namespace {
// Different node types, used as template parameter
enum NodeType { Root, PV, NonPV, SplitPointRoot, SplitPointPV, SplitPointNonPV };
- // RootMove struct is used for moves at the root of the tree. For each root
- // move, we store a score, a node count, and a PV (really a refutation
- // in the case of moves which fail low). Score is normally set at
- // -VALUE_INFINITE for all non-pv moves.
- struct RootMove {
-
- // 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 an higher score
- bool operator<(const RootMove& m) const { return score < m.score; }
-
- void extract_pv_from_tt(Position& pos);
- void insert_pv_in_tt(Position& pos);
-
- int64_t nodes;
- Value score;
- Value prevScore;
- std::vector<Move> pv;
- };
-
- // RootMoveList struct is mainly a std::vector of RootMove objects
- struct RootMoveList : public std::vector<RootMove> {
-
- void init(Position& pos, Move searchMoves[]);
- RootMove* find(const Move& m, int startIndex = 0);
-
- int bestMoveChanges;
- };
-
-
- /// Constants
-
// Lookup table to check if a Piece is a slider and its access function
const bool Slidings[18] = { 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1 };
inline bool piece_is_slider(Piece p) { return Slidings[p]; }
- // Step 6. Razoring
-
// Maximum depth for razoring
const Depth RazorDepth = 4 * ONE_PLY;
// Maximum depth for use of dynamic threat detection when null move fails low
const Depth ThreatDepth = 5 * ONE_PLY;
- // Step 9. Internal iterative deepening
-
// Minimum depth for use of internal iterative deepening
const Depth IIDDepth[] = { 8 * ONE_PLY, 5 * ONE_PLY };
// when the static evaluation is bigger then beta - IIDMargin.
const Value IIDMargin = Value(0x100);
- // Step 11. Decide the new search depth
-
- // Extensions. Array index 0 is used for non-PV nodes, index 1 for PV nodes
- const Depth CheckExtension[] = { ONE_PLY / 2, ONE_PLY / 1 };
- const Depth PawnEndgameExtension[] = { ONE_PLY / 1, ONE_PLY / 1 };
- const Depth PawnPushTo7thExtension[] = { ONE_PLY / 2, ONE_PLY / 2 };
- const Depth PassedPawnExtension[] = { DEPTH_ZERO, ONE_PLY / 2 };
-
// Minimum depth for use of singular extension
const Depth SingularExtensionDepth[] = { 8 * ONE_PLY, 6 * ONE_PLY };
- // Step 12. Futility pruning
-
// Futility margin for quiescence search
const Value FutilityMarginQS = Value(0x80);
return d < 16 * ONE_PLY ? FutilityMoveCounts[d] : MAX_MOVES;
}
- // Step 14. Reduced search
-
// Reduction lookup tables (initialized at startup) and their access function
int8_t Reductions[2][64][64]; // [pv][depth][moveNumber]
return (Depth) Reductions[PvNode][std::min(int(d) / ONE_PLY, 63)][std::min(mn, 63)];
}
- // Easy move margin. An easy move candidate must be at least this much
- // better than the second best move.
- const Value EasyMoveMargin = Value(0x200);
-
+ // Easy move margin. An easy move candidate must be at least this much better
+ // than the second best move.
+ const Value EasyMoveMargin = Value(0x150);
- /// Namespace variables
+ // This is the minimum interval in msec between two check_time() calls
+ const int TimerResolution = 5;
- // Root move list
- RootMoveList Rml;
- // MultiPV mode
- int MultiPV, UCIMultiPV, MultiPVIdx;
-
- // Time management variables
- bool StopOnPonderhit, FirstRootMove, StopRequest, QuitRequest, AspirationFailLow;
+ size_t MultiPV, UCIMultiPV, PVIdx;
TimeManager TimeMgr;
- SearchLimits Limits;
-
- // Skill level adjustment
+ int BestMoveChanges;
int SkillLevel;
- bool SkillLevelEnabled;
-
- // History table
+ bool SkillLevelEnabled, Chess960;
History H;
- /// Local functions
-
- Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove);
-
template <NodeType NT>
- Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth);
+ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
template <NodeType NT>
- Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth);
+ Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
- bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bValue);
+ void id_loop(Position& pos);
+ bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta);
bool connected_moves(const Position& pos, Move m1, Move m2);
Value value_to_tt(Value v, int ply);
Value value_from_tt(Value v, int ply);
- bool can_return_tt(const TTEntry* tte, Depth depth, Value beta, int ply);
+ bool can_return_tt(const TTEntry* tte, Depth depth, Value ttValue, Value beta);
bool connected_threat(const Position& pos, Move m, Move threat);
- Value refine_eval(const TTEntry* tte, Value defaultEval, int ply);
- void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount);
- void do_skill_level(Move* best, Move* ponder);
-
- int elapsed_search_time(int set = 0);
+ Value refine_eval(const TTEntry* tte, Value ttValue, Value defaultEval);
+ Move do_skill_level();
string score_to_uci(Value v, Value alpha = -VALUE_INFINITE, Value beta = VALUE_INFINITE);
- string speed_to_uci(int64_t nodes);
- string pv_to_uci(const Move pv[], int pvNum, bool chess960);
- string pretty_pv(Position& pos, int depth, Value score, int time, Move pv[]);
- string depth_to_uci(Depth depth);
- void wait_for_stop_or_ponderhit();
-
- // MovePickerExt template class extends MovePicker and allows to choose at compile
- // time the proper moves source according to the type of node. In the default case
- // we simply create and use a standard MovePicker object.
+ void pv_info_to_log(Position& pos, int depth, Value score, int time, Move pv[]);
+ void pv_info_to_uci(const Position& pos, int depth, Value alpha, Value beta);
+
+ // MovePickerExt class template extends MovePicker and allows to choose at
+ // compile time the proper moves source according to the type of node. In the
+ // default case we simply create and use a standard MovePicker object.
template<bool SpNode> struct MovePickerExt : public MovePicker {
- MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
+ MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, Stack* ss, Value b)
: MovePicker(p, ttm, d, h, ss, b) {}
};
// In case of a SpNode we use split point's shared MovePicker object as moves source
template<> struct MovePickerExt<true> : public MovePicker {
- MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
+ MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, Stack* ss, Value b)
: MovePicker(p, ttm, d, h, ss, b), mp(ss->sp->mp) {}
- Move get_next_move() { return mp->get_next_move(); }
+ Move next_move() { return mp->next_move(); }
MovePicker* mp;
};
- // Overload operator<<() to make it easier to print moves in a coordinate
- // notation compatible with UCI protocol.
- std::ostream& operator<<(std::ostream& os, Move m) {
-
- bool chess960 = (os.iword(0) != 0); // See set960()
- return os << move_to_uci(m, chess960);
- }
-
- // When formatting a move for std::cout we must know if we are in Chess960
- // or not. To keep using the handy operator<<() on the move the trick is to
- // embed this flag in the stream itself. Function-like named enum set960 is
- // used as a custom manipulator and the stream internal general-purpose array,
- // accessed through ios_base::iword(), is used to pass the flag to the move's
- // operator<<() that will read it to properly format castling moves.
- enum set960 {};
+ // is_dangerous() checks whether a move belongs to some classes of known
+ // 'dangerous' moves so that we avoid to prune it.
+ FORCE_INLINE bool is_dangerous(const Position& pos, Move m, bool captureOrPromotion) {
- std::ostream& operator<< (std::ostream& os, const set960& f) {
-
- os.iword(0) = int(f);
- return os;
- }
-
- // 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.
- template <bool PvNode>
- FORCE_INLINE Depth extension(const Position& pos, Move m, bool captureOrPromotion,
- bool moveIsCheck, bool* dangerous) {
- assert(m != MOVE_NONE);
-
- Depth result = DEPTH_ZERO;
- *dangerous = moveIsCheck;
-
- if (moveIsCheck && pos.see_sign(m) >= 0)
- result += CheckExtension[PvNode];
-
- if (type_of(pos.piece_on(move_from(m))) == PAWN)
+ // Test for a pawn pushed to 7th or a passed pawn move
+ if (type_of(pos.piece_moved(m)) == PAWN)
{
Color c = pos.side_to_move();
- if (relative_rank(c, move_to(m)) == RANK_7)
- {
- result += PawnPushTo7thExtension[PvNode];
- *dangerous = true;
- }
- if (pos.pawn_is_passed(c, move_to(m)))
- {
- result += PassedPawnExtension[PvNode];
- *dangerous = true;
- }
+ if ( relative_rank(c, to_sq(m)) == RANK_7
+ || pos.pawn_is_passed(c, to_sq(m)))
+ return true;
}
+ // Test for a capture that triggers a pawn endgame
if ( captureOrPromotion
- && type_of(pos.piece_on(move_to(m))) != PAWN
+ && type_of(pos.piece_on(to_sq(m))) != PAWN
&& ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK)
- - PieceValueMidgame[pos.piece_on(move_to(m))] == VALUE_ZERO)
+ - PieceValueMidgame[pos.piece_on(to_sq(m))] == VALUE_ZERO)
&& !is_special(m))
- {
- result += PawnEndgameExtension[PvNode];
- *dangerous = true;
- }
+ return true;
- return std::min(result, ONE_PLY);
+ return false;
}
} // namespace
-/// init_search() is called during startup to initialize various lookup tables
+/// Search::init() is called during startup to initialize various lookup tables
-void init_search() {
+void Search::init() {
int d; // depth (ONE_PLY == 2)
int hd; // half depth (ONE_PLY == 1)
}
-/// perft() is our utility to verify move generation. All the leaf nodes up to
-/// the given depth are generated and counted and the sum returned.
+/// Search::perft() is our utility to verify move generation. All the leaf nodes
+/// up to the given depth are generated and counted and the sum returned.
-int64_t perft(Position& pos, Depth depth) {
+int64_t Search::perft(Position& pos, Depth depth) {
StateInfo st;
- int64_t sum = 0;
+ int64_t cnt = 0;
- // Generate all legal moves
MoveList<MV_LEGAL> ml(pos);
- // If we are at the last ply we don't need to do and undo
- // the moves, just to count them.
- if (depth <= ONE_PLY)
+ // At the last ply just return the number of moves (leaf nodes)
+ if (depth == ONE_PLY)
return ml.size();
- // Loop through all legal moves
CheckInfo ci(pos);
for ( ; !ml.end(); ++ml)
{
pos.do_move(ml.move(), st, ci, pos.move_gives_check(ml.move(), ci));
- sum += perft(pos, depth - ONE_PLY);
+ cnt += perft(pos, depth - ONE_PLY);
pos.undo_move(ml.move());
}
- return sum;
+ return cnt;
}
-/// think() is the external interface to Stockfish's search, and is called when
-/// the program receives the UCI 'go' command. It initializes various global
-/// variables, and calls id_loop(). It returns false when a "quit" command is
-/// received during the search.
+/// Search::think() is the external interface to Stockfish's search, and is
+/// called by the main thread when the program receives the UCI 'go' command. It
+/// searches from RootPosition and at the end prints the "bestmove" to output.
+
+void Search::think() {
-bool think(Position& pos, const SearchLimits& limits, Move searchMoves[]) {
+ static Book book; // Defined static to initialize the PRNG only once
- static Book book; // Define static to initialize the PRNG only once
+ Position& pos = RootPosition;
+ Chess960 = pos.is_chess960();
+ Eval::RootColor = pos.side_to_move();
+ TimeMgr.init(Limits, pos.startpos_ply_counter(), pos.side_to_move());
+ TT.new_search();
+ H.clear();
- // Initialize global search-related variables
- StopOnPonderhit = StopRequest = QuitRequest = AspirationFailLow = false;
- elapsed_search_time(get_system_time());
- Limits = limits;
- TimeMgr.init(Limits, pos.startpos_ply_counter());
+ if (RootMoves.empty())
+ {
+ cout << "info depth 0 score "
+ << score_to_uci(pos.in_check() ? -VALUE_MATE : VALUE_DRAW) << endl;
- // Set output steram in normal or chess960 mode
- cout << set960(pos.is_chess960());
+ RootMoves.push_back(MOVE_NONE);
+ goto finalize;
+ }
- // Look for a book move
- if (Options["OwnBook"].value<bool>())
+ if (Options["OwnBook"])
{
- if (Options["Book File"].value<string>() != book.name())
- book.open(Options["Book File"].value<string>());
+ Move bookMove = book.probe(pos, Options["Book File"], Options["Best Book Move"]);
- Move bookMove = book.probe(pos, Options["Best Book Move"].value<bool>());
- if (bookMove != MOVE_NONE)
+ if (bookMove && count(RootMoves.begin(), RootMoves.end(), bookMove))
{
- if (Limits.ponder)
- wait_for_stop_or_ponderhit();
-
- cout << "bestmove " << bookMove << endl;
- return !QuitRequest;
+ std::swap(RootMoves[0], *find(RootMoves.begin(), RootMoves.end(), bookMove));
+ goto finalize;
}
}
- // Set best timer interval to avoid lagging under time pressure
- if (TimeMgr.available_time())
- Threads.set_timer(std::min(100, std::max(TimeMgr.available_time() / 8, 20)));
- else
- Threads.set_timer(100);
-
- // Read UCI options
- UCIMultiPV = Options["MultiPV"].value<int>();
- SkillLevel = Options["Skill Level"].value<int>();
-
- read_evaluation_uci_options(pos.side_to_move());
- Threads.read_uci_options();
-
- // Set a new TT size if changed
- TT.set_size(Options["Hash"].value<int>());
-
- if (Options["Clear Hash"].value<bool>())
- {
- Options["Clear Hash"].set_value("false");
- TT.clear();
- }
+ UCIMultiPV = Options["MultiPV"];
+ SkillLevel = Options["Skill Level"];
// Do we have to play with skill handicap? In this case enable MultiPV that
// we will use behind the scenes to retrieve a set of possible moves.
SkillLevelEnabled = (SkillLevel < 20);
- MultiPV = (SkillLevelEnabled ? std::max(UCIMultiPV, 4) : UCIMultiPV);
+ MultiPV = (SkillLevelEnabled ? std::max(UCIMultiPV, (size_t)4) : UCIMultiPV);
- // Wake up needed threads and reset maxPly counter
- for (int i = 0; i < Threads.size(); i++)
+ if (Options["Use Search Log"])
{
- Threads[i].wake_up();
- Threads[i].maxPly = 0;
- }
-
- // Write to log file and keep it open to be accessed during the search
- if (Options["Use Search Log"].value<bool>())
- {
- Log log(Options["Search Log Filename"].value<string>());
+ Log log(Options["Search Log Filename"]);
log << "\nSearching: " << pos.to_fen()
<< "\ninfinite: " << Limits.infinite
<< " ponder: " << Limits.ponder
- << " time: " << Limits.time
- << " increment: " << Limits.increment
- << " moves to go: " << Limits.movesToGo
+ << " time: " << Limits.time[pos.side_to_move()]
+ << " increment: " << Limits.inc[pos.side_to_move()]
+ << " moves to go: " << Limits.movestogo
<< endl;
}
- // Start async mode to catch UCI commands sent to us while searching,
- // like "quit", "stop", etc.
- Threads.start_listener();
+ Threads.wake_up();
+
+ // Set best timer interval to avoid lagging under time pressure. Timer is
+ // used to check for remaining available thinking time.
+ if (Limits.use_time_management())
+ Threads.set_timer(std::min(100, std::max(TimeMgr.available_time() / 16, TimerResolution)));
+ else
+ Threads.set_timer(100);
- // We're ready to start thinking. Call the iterative deepening loop function
- Move ponderMove = MOVE_NONE;
- Move bestMove = id_loop(pos, searchMoves, &ponderMove);
+ // We're ready to start searching. Call the iterative deepening loop function
+ id_loop(pos);
- Threads.set_timer(0);
+ Threads.set_timer(0); // Stop timer
+ Threads.sleep();
- // Write final search statistics and close log file
- if (Options["Use Search Log"].value<bool>())
+ if (Options["Use Search Log"])
{
- int e = elapsed_search_time();
+ int e = SearchTime.elapsed();
- Log log(Options["Search Log Filename"].value<string>());
+ Log log(Options["Search Log Filename"]);
log << "Nodes: " << pos.nodes_searched()
<< "\nNodes/second: " << (e > 0 ? pos.nodes_searched() * 1000 / e : 0)
- << "\nBest move: " << move_to_san(pos, bestMove);
+ << "\nBest move: " << move_to_san(pos, RootMoves[0].pv[0]);
StateInfo st;
- pos.do_move(bestMove, st);
- log << "\nPonder move: " << move_to_san(pos, ponderMove) << endl;
- pos.undo_move(bestMove); // Return from think() with unchanged position
+ pos.do_move(RootMoves[0].pv[0], st);
+ log << "\nPonder move: " << move_to_san(pos, RootMoves[0].pv[1]) << endl;
+ pos.undo_move(RootMoves[0].pv[0]);
}
- // This makes all the threads to go to sleep
- Threads.set_size(1);
-
- // From now on any UCI command will be read in-sync with Threads.getline()
- Threads.stop_listener();
-
- // If we are pondering or in infinite search, we shouldn't print the
- // best move before we are told to do so.
- if (!StopRequest && (Limits.ponder || Limits.infinite))
- wait_for_stop_or_ponderhit();
+finalize:
- // Could be MOVE_NONE when searching on a stalemate position
- cout << "bestmove " << bestMove;
+ // When we reach max depth we arrive here even without Signals.stop is raised,
+ // but if we are pondering or in infinite search, we shouldn't print the best
+ // move before we are told to do so.
+ if (!Signals.stop && (Limits.ponder || Limits.infinite))
+ Threads[pos.this_thread()].wait_for_stop_or_ponderhit();
- // UCI protol is not clear on allowing sending an empty ponder move, instead
- // it is clear that ponder move is optional. So skip it if empty.
- if (ponderMove != MOVE_NONE)
- cout << " ponder " << ponderMove;
-
- cout << endl;
-
- return !QuitRequest;
+ // Best move could be MOVE_NONE when searching on a stalemate position
+ cout << "bestmove " << move_to_uci(RootMoves[0].pv[0], Chess960)
+ << " ponder " << move_to_uci(RootMoves[0].pv[1], Chess960) << endl;
}
// with increasing depth until the allocated thinking time has been consumed,
// user stops the search, or the maximum search depth is reached.
- Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove) {
-
- SearchStack ss[PLY_MAX_PLUS_2];
- Value bestValues[PLY_MAX_PLUS_2];
- int bestMoveChanges[PLY_MAX_PLUS_2];
- int depth, aspirationDelta;
- Value value, alpha, beta;
- Move bestMove, easyMove, skillBest, skillPonder;
-
- // Initialize stuff before a new search
- memset(ss, 0, 4 * sizeof(SearchStack));
- TT.new_search();
- H.clear();
- *ponderMove = bestMove = easyMove = skillBest = skillPonder = MOVE_NONE;
- depth = aspirationDelta = 0;
- value = alpha = -VALUE_INFINITE, beta = VALUE_INFINITE;
- ss->currentMove = MOVE_NULL; // Hack to skip update gains
+ void id_loop(Position& pos) {
- // Moves to search are verified and copied
- Rml.init(pos, searchMoves);
-
- // Handle special case of searching on a mate/stalemate position
- if (!Rml.size())
- {
- cout << "info" << depth_to_uci(DEPTH_ZERO)
- << score_to_uci(pos.in_check() ? -VALUE_MATE : VALUE_DRAW, alpha, beta) << endl;
+ Stack ss[MAX_PLY_PLUS_2];
+ int depth, prevBestMoveChanges;
+ Value bestValue, alpha, beta, delta;
+ bool bestMoveNeverChanged = true;
+ Move skillBest = MOVE_NONE;
- return MOVE_NONE;
- }
+ memset(ss, 0, 4 * sizeof(Stack));
+ depth = BestMoveChanges = 0;
+ bestValue = delta = -VALUE_INFINITE;
+ ss->currentMove = MOVE_NULL; // Hack to skip update gains
// Iterative deepening loop until requested to stop or target depth reached
- while (!StopRequest && ++depth <= PLY_MAX && (!Limits.maxDepth || depth <= Limits.maxDepth))
+ while (!Signals.stop && ++depth <= MAX_PLY && (!Limits.depth || depth <= Limits.depth))
{
- // Save now last iteration's scores, before Rml moves are reordered
- for (size_t i = 0; i < Rml.size(); i++)
- Rml[i].prevScore = Rml[i].score;
+ // Save last iteration's scores before first PV line is searched and all
+ // the move scores but the (new) PV are set to -VALUE_INFINITE.
+ for (size_t i = 0; i < RootMoves.size(); i++)
+ RootMoves[i].prevScore = RootMoves[i].score;
- Rml.bestMoveChanges = 0;
+ prevBestMoveChanges = BestMoveChanges;
+ BestMoveChanges = 0;
// MultiPV loop. We perform a full root search for each PV line
- for (MultiPVIdx = 0; MultiPVIdx < std::min(MultiPV, (int)Rml.size()); MultiPVIdx++)
+ for (PVIdx = 0; PVIdx < std::min(MultiPV, RootMoves.size()); PVIdx++)
{
- // Calculate dynamic aspiration window based on previous iterations
- if (depth >= 5 && abs(Rml[MultiPVIdx].prevScore) < VALUE_KNOWN_WIN)
+ // Set aspiration window default width
+ if (depth >= 5 && abs(RootMoves[PVIdx].prevScore) < VALUE_KNOWN_WIN)
{
- int prevDelta1 = bestValues[depth - 1] - bestValues[depth - 2];
- int prevDelta2 = bestValues[depth - 2] - bestValues[depth - 3];
-
- aspirationDelta = std::min(std::max(abs(prevDelta1) + abs(prevDelta2) / 2, 16), 24);
- aspirationDelta = (aspirationDelta + 7) / 8 * 8; // Round to match grainSize
-
- alpha = std::max(Rml[MultiPVIdx].prevScore - aspirationDelta, -VALUE_INFINITE);
- beta = std::min(Rml[MultiPVIdx].prevScore + aspirationDelta, VALUE_INFINITE);
+ delta = Value(16);
+ alpha = RootMoves[PVIdx].prevScore - delta;
+ beta = RootMoves[PVIdx].prevScore + delta;
}
else
{
do {
// Search starts from ss+1 to allow referencing (ss-1). This is
// needed by update gains and ss copy when splitting at Root.
- value = search<Root>(pos, ss+1, alpha, beta, depth * ONE_PLY);
+ bestValue = search<Root>(pos, ss+1, alpha, beta, depth * ONE_PLY);
// Bring to front the best move. It is critical that sorting is
// done with a stable algorithm because all the values but the first
// we want to keep the same order for all the moves but the new
// PV that goes to the front. Note that in case of MultiPV search
// the already searched PV lines are preserved.
- sort<RootMove>(Rml.begin() + MultiPVIdx, Rml.end());
+ sort<RootMove>(RootMoves.begin() + PVIdx, RootMoves.end());
// In case we have found an exact score and we are going to leave
// the fail high/low loop then reorder the PV moves, otherwise
// leave the last PV move in its position so to be searched again.
// Of course this is needed only in MultiPV search.
- if (MultiPVIdx && value > alpha && value < beta)
- sort<RootMove>(Rml.begin(), Rml.begin() + MultiPVIdx);
-
- // Write PV back to transposition table in case the relevant entries
- // have been overwritten during the search.
- for (int i = 0; i <= MultiPVIdx; i++)
- Rml[i].insert_pv_in_tt(pos);
-
- // If search has been stopped exit the aspiration window loop,
- // note that sorting and writing PV back to TT is safe becuase
- // Rml is still valid, although refers to the previous iteration.
- if (StopRequest)
+ if (PVIdx && bestValue > alpha && bestValue < beta)
+ sort<RootMove>(RootMoves.begin(), RootMoves.begin() + PVIdx);
+
+ // Write PV back to transposition table in case the relevant
+ // entries have been overwritten during the search.
+ for (size_t i = 0; i <= PVIdx; i++)
+ RootMoves[i].insert_pv_in_tt(pos);
+
+ // If search has been stopped exit the aspiration window loop.
+ // Sorting and writing PV back to TT is safe becuase RootMoves
+ // is still valid, although refers to previous iteration.
+ if (Signals.stop)
break;
// Send full PV info to GUI if we are going to leave the loop or
- // if we have a fail high/low and we are deep in the search. UCI
- // protocol requires to send all the PV lines also if are still
- // to be searched and so refer to the previous search's score.
- if ((value > alpha && value < beta) || elapsed_search_time() > 2000)
- for (int i = 0; i < std::min(UCIMultiPV, (int)Rml.size()); i++)
- {
- bool updated = (i <= MultiPVIdx);
-
- if (depth == 1 && !updated)
- continue;
-
- Depth d = (updated ? depth : depth - 1) * ONE_PLY;
- Value s = (updated ? Rml[i].score : Rml[i].prevScore);
-
- cout << "info"
- << depth_to_uci(d)
- << (i == MultiPVIdx ? score_to_uci(s, alpha, beta) : score_to_uci(s))
- << speed_to_uci(pos.nodes_searched())
- << pv_to_uci(&Rml[i].pv[0], i + 1, pos.is_chess960())
- << endl;
- }
+ // if we have a fail high/low and we are deep in the search.
+ if ((bestValue > alpha && bestValue < beta) || SearchTime.elapsed() > 2000)
+ pv_info_to_uci(pos, depth, alpha, beta);
// In case of failing high/low increase aspiration window and
// research, otherwise exit the fail high/low loop.
- if (value >= beta)
+ if (bestValue >= beta)
{
- beta = std::min(beta + aspirationDelta, VALUE_INFINITE);
- aspirationDelta += aspirationDelta / 2;
+ beta += delta;
+ delta += delta / 2;
}
- else if (value <= alpha)
+ else if (bestValue <= alpha)
{
- AspirationFailLow = true;
- StopOnPonderhit = false;
+ Signals.failedLowAtRoot = true;
+ Signals.stopOnPonderhit = false;
- alpha = std::max(alpha - aspirationDelta, -VALUE_INFINITE);
- aspirationDelta += aspirationDelta / 2;
+ alpha -= delta;
+ delta += delta / 2;
}
else
break;
- } while (abs(value) < VALUE_KNOWN_WIN);
- }
+ assert(alpha >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
- // Collect info about search result
- bestMove = Rml[0].pv[0];
- *ponderMove = Rml[0].pv[1];
- bestValues[depth] = value;
- bestMoveChanges[depth] = Rml.bestMoveChanges;
+ } while (abs(bestValue) < VALUE_KNOWN_WIN);
+ }
- // Skills: Do we need to pick now the best and the ponder moves ?
+ // Skills: Do we need to pick now the best move ?
if (SkillLevelEnabled && depth == 1 + SkillLevel)
- do_skill_level(&skillBest, &skillPonder);
+ skillBest = do_skill_level();
- if (Options["Use Search Log"].value<bool>())
- {
- Log log(Options["Search Log Filename"].value<string>());
- log << pretty_pv(pos, depth, value, elapsed_search_time(), &Rml[0].pv[0]) << endl;
- }
+ if (!Signals.stop && Options["Use Search Log"])
+ pv_info_to_log(pos, depth, bestValue, SearchTime.elapsed(), &RootMoves[0].pv[0]);
- // Init easyMove at first iteration or drop it if differs from the best move
- if (depth == 1 && (Rml.size() == 1 || Rml[0].score > Rml[1].score + EasyMoveMargin))
- easyMove = bestMove;
- else if (bestMove != easyMove)
- easyMove = MOVE_NONE;
+ // Filter out startup noise when monitoring best move stability
+ if (depth > 2 && BestMoveChanges)
+ bestMoveNeverChanged = false;
- // Check for some early stop condition
- if (!StopRequest && Limits.useTimeManagement())
+ // Do we have time for the next iteration? Can we stop searching now?
+ if (!Signals.stop && !Signals.stopOnPonderhit && Limits.use_time_management())
{
- // Easy move: Stop search early if one move seems to be much better
- // than the others or if there is only a single legal move. Also in
- // the latter case search to some depth anyway to get a proper score.
- if ( depth >= 7
- && easyMove == bestMove
- && ( Rml.size() == 1
- ||( Rml[0].nodes > (pos.nodes_searched() * 85) / 100
- && elapsed_search_time() > TimeMgr.available_time() / 16)
- ||( Rml[0].nodes > (pos.nodes_searched() * 98) / 100
- && elapsed_search_time() > TimeMgr.available_time() / 32)))
- StopRequest = true;
+ bool stop = false; // Local variable, not the volatile Signals.stop
// Take in account some extra time if the best move has changed
if (depth > 4 && depth < 50)
- TimeMgr.pv_instability(bestMoveChanges[depth], bestMoveChanges[depth - 1]);
-
- // Stop search if most of available time is already consumed. We probably don't
- // have enough time to search the first move at the next iteration anyway.
- if (elapsed_search_time() > (TimeMgr.available_time() * 62) / 100)
- StopRequest = true;
+ TimeMgr.pv_instability(BestMoveChanges, prevBestMoveChanges);
+
+ // Stop search if most of available time is already consumed. We
+ // probably don't have enough time to search the first move at the
+ // next iteration anyway.
+ if (SearchTime.elapsed() > (TimeMgr.available_time() * 62) / 100)
+ stop = true;
+
+ // Stop search early if one move seems to be much better than others
+ if ( depth >= 12
+ && !stop
+ && ( (bestMoveNeverChanged && pos.captured_piece_type())
+ || SearchTime.elapsed() > (TimeMgr.available_time() * 40) / 100))
+ {
+ Value rBeta = bestValue - EasyMoveMargin;
+ (ss+1)->excludedMove = RootMoves[0].pv[0];
+ (ss+1)->skipNullMove = true;
+ Value v = search<NonPV>(pos, ss+1, rBeta - 1, rBeta, (depth - 3) * ONE_PLY);
+ (ss+1)->skipNullMove = false;
+ (ss+1)->excludedMove = MOVE_NONE;
+
+ if (v < rBeta)
+ stop = true;
+ }
- // If we are allowed to ponder do not stop the search now but keep pondering
- if (StopRequest && Limits.ponder)
+ if (stop)
{
- StopRequest = false;
- StopOnPonderhit = true;
+ // If we are allowed to ponder do not stop the search now but
+ // keep pondering until GUI sends "ponderhit" or "stop".
+ if (Limits.ponder)
+ Signals.stopOnPonderhit = true;
+ else
+ Signals.stop = true;
}
}
}
- // When using skills overwrite best and ponder moves with the sub-optimal ones
+ // When using skills swap best PV line with the sub-optimal one
if (SkillLevelEnabled)
{
if (skillBest == MOVE_NONE) // Still unassigned ?
- do_skill_level(&skillBest, &skillPonder);
+ skillBest = do_skill_level();
- bestMove = skillBest;
- *ponderMove = skillPonder;
+ std::swap(RootMoves[0], *find(RootMoves.begin(), RootMoves.end(), skillBest));
}
-
- return bestMove;
}
// here: This is taken care of after we return from the split point.
template <NodeType NT>
- Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) {
+ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
const bool PvNode = (NT == PV || NT == Root || NT == SplitPointPV || NT == SplitPointRoot);
const bool SpNode = (NT == SplitPointPV || NT == SplitPointNonPV || NT == SplitPointRoot);
const bool RootNode = (NT == Root || NT == SplitPointRoot);
- assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
- assert(beta > alpha && beta <= VALUE_INFINITE);
- assert(PvNode || alpha == beta - 1);
- assert(pos.thread() >= 0 && pos.thread() < Threads.size());
+ assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE);
+ assert((alpha == beta - 1) || PvNode);
+ assert(depth > DEPTH_ZERO);
+ assert(pos.this_thread() >= 0 && pos.this_thread() < Threads.size());
Move movesSearched[MAX_MOVES];
- int64_t nodes;
StateInfo st;
const TTEntry *tte;
Key posKey;
- Move ttMove, move, excludedMove, threatMove;
+ Move ttMove, move, excludedMove, bestMove, threatMove;
Depth ext, newDepth;
- ValueType vt;
- Value bestValue, value, oldAlpha;
+ Bound bt;
+ Value bestValue, value, oldAlpha, ttValue;
Value refinedValue, nullValue, futilityBase, futilityValue;
- bool isPvMove, inCheck, singularExtensionNode, givesCheck, captureOrPromotion, dangerous;
+ bool isPvMove, inCheck, singularExtensionNode, givesCheck;
+ bool captureOrPromotion, dangerous, doFullDepthSearch;
int moveCount = 0, playedMoveCount = 0;
- Thread& thread = Threads[pos.thread()];
+ Thread& thread = Threads[pos.this_thread()];
SplitPoint* sp = NULL;
refinedValue = bestValue = value = -VALUE_INFINITE;
thread.maxPly = ss->ply;
// Step 1. Initialize node
- if (!SpNode)
- {
- ss->currentMove = ss->bestMove = threatMove = (ss+1)->excludedMove = MOVE_NONE;
- (ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO;
- (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
- }
- else
+ if (SpNode)
{
- sp = ss->sp;
tte = NULL;
ttMove = excludedMove = MOVE_NONE;
+ ttValue = VALUE_ZERO;
+ sp = ss->sp;
+ bestMove = sp->bestMove;
threatMove = sp->threatMove;
+ bestValue = sp->bestValue;
+ moveCount = sp->moveCount; // Lock must be held here
+
+ assert(bestValue > -VALUE_INFINITE && moveCount > 0);
+
goto split_point_start;
}
+ else
+ {
+ ss->currentMove = threatMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
+ (ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO;
+ (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
+
+ }
// Step 2. Check for aborted search and immediate draw
- if (( StopRequest
+ // Enforce node limit here. FIXME: This only works with 1 search thread.
+ if (Limits.nodes && pos.nodes_searched() >= Limits.nodes)
+ Signals.stop = true;
+
+ if (( Signals.stop
|| pos.is_draw<false>()
- || ss->ply > PLY_MAX) && !RootNode)
+ || ss->ply > MAX_PLY) && !RootNode)
return VALUE_DRAW;
- // Step 3. Mate distance pruning
+ // Step 3. Mate distance pruning. Even if we mate at the next move our score
+ // would be at best mate_in(ss->ply+1), but if alpha is already bigger because
+ // a shorter mate was found upward in the tree then there is no need to search
+ // further, we will never beat current alpha. Same logic but with reversed signs
+ // applies also in the opposite condition of being mated instead of giving mate,
+ // in this case return a fail-high score.
if (!RootNode)
{
- alpha = std::max(value_mated_in(ss->ply), alpha);
- beta = std::min(value_mate_in(ss->ply+1), beta);
+ alpha = std::max(mated_in(ss->ply), alpha);
+ beta = std::min(mate_in(ss->ply+1), beta);
if (alpha >= beta)
return alpha;
}
// We don't want the score of a partial search to overwrite a previous full search
// TT value, so we use a different position key in case of an excluded move.
excludedMove = ss->excludedMove;
- posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key();
+ posKey = excludedMove ? pos.exclusion_key() : pos.key();
tte = TT.probe(posKey);
- ttMove = RootNode ? Rml[MultiPVIdx].pv[0] : tte ? tte->move() : MOVE_NONE;
+ ttMove = RootNode ? RootMoves[PVIdx].pv[0] : tte ? tte->move() : MOVE_NONE;
+ ttValue = tte ? value_from_tt(tte->value(), ss->ply) : VALUE_ZERO;
// At PV nodes we check for exact scores, while at non-PV nodes we check for
// a fail high/low. Biggest advantage at probing at PV nodes is to have a
// smooth experience in analysis mode. We don't probe at Root nodes otherwise
// we should also update RootMoveList to avoid bogus output.
- if (!RootNode && tte && (PvNode ? tte->depth() >= depth && tte->type() == VALUE_TYPE_EXACT
- : can_return_tt(tte, depth, beta, ss->ply)))
+ if (!RootNode && tte && (PvNode ? tte->depth() >= depth && tte->type() == BOUND_EXACT
+ : can_return_tt(tte, depth, ttValue, beta)))
{
TT.refresh(tte);
- ss->bestMove = move = ttMove; // Can be MOVE_NONE
- value = value_from_tt(tte->value(), ss->ply);
+ ss->currentMove = ttMove; // Can be MOVE_NONE
- if ( value >= beta
- && move
- && !pos.is_capture_or_promotion(move)
- && move != ss->killers[0])
+ if ( ttValue >= beta
+ && ttMove
+ && !pos.is_capture_or_promotion(ttMove)
+ && ttMove != ss->killers[0])
{
ss->killers[1] = ss->killers[0];
- ss->killers[0] = move;
+ ss->killers[0] = ttMove;
}
- return value;
+ return ttValue;
}
// Step 5. Evaluate the position statically and update parent's gain statistics
ss->eval = tte->static_value();
ss->evalMargin = tte->static_value_margin();
- refinedValue = refine_eval(tte, ss->eval, ss->ply);
+ refinedValue = refine_eval(tte, ttValue, ss->eval);
}
else
{
refinedValue = ss->eval = evaluate(pos, ss->evalMargin);
- TT.store(posKey, VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, MOVE_NONE, ss->eval, ss->evalMargin);
+ TT.store(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE, ss->eval, ss->evalMargin);
}
// Update gain for the parent non-capture move given the static position
if ( (move = (ss-1)->currentMove) != MOVE_NULL
&& (ss-1)->eval != VALUE_NONE
&& ss->eval != VALUE_NONE
- && pos.captured_piece_type() == PIECE_TYPE_NONE
+ && !pos.captured_piece_type()
&& !is_special(move))
{
- Square to = move_to(move);
+ Square to = to_sq(move);
H.update_gain(pos.piece_on(to), to, -(ss-1)->eval - ss->eval);
}
&& !inCheck
&& refinedValue + razor_margin(depth) < beta
&& ttMove == MOVE_NONE
- && abs(beta) < VALUE_MATE_IN_PLY_MAX
- && !pos.has_pawn_on_7th(pos.side_to_move()))
+ && abs(beta) < VALUE_MATE_IN_MAX_PLY
+ && !pos.pawn_on_7th(pos.side_to_move()))
{
Value rbeta = beta - razor_margin(depth);
Value v = qsearch<NonPV>(pos, ss, rbeta-1, rbeta, DEPTH_ZERO);
&& depth < RazorDepth
&& !inCheck
&& refinedValue - futility_margin(depth, 0) >= beta
- && abs(beta) < VALUE_MATE_IN_PLY_MAX
+ && abs(beta) < VALUE_MATE_IN_MAX_PLY
&& pos.non_pawn_material(pos.side_to_move()))
return refinedValue - futility_margin(depth, 0);
&& depth > ONE_PLY
&& !inCheck
&& refinedValue >= beta
- && abs(beta) < VALUE_MATE_IN_PLY_MAX
+ && abs(beta) < VALUE_MATE_IN_MAX_PLY
&& pos.non_pawn_material(pos.side_to_move()))
{
ss->currentMove = MOVE_NULL;
if (nullValue >= beta)
{
// Do not return unproven mate scores
- if (nullValue >= VALUE_MATE_IN_PLY_MAX)
+ if (nullValue >= VALUE_MATE_IN_MAX_PLY)
nullValue = beta;
if (depth < 6 * ONE_PLY)
// 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).
- threatMove = (ss+1)->bestMove;
+ threatMove = (ss+1)->currentMove;
if ( depth < ThreatDepth
&& (ss-1)->reduction
&& !inCheck
&& !ss->skipNullMove
&& excludedMove == MOVE_NONE
- && abs(beta) < VALUE_MATE_IN_PLY_MAX)
+ && abs(beta) < VALUE_MATE_IN_MAX_PLY)
{
Value rbeta = beta + 200;
Depth rdepth = depth - ONE_PLY - 3 * ONE_PLY;
assert(rdepth >= ONE_PLY);
+ assert((ss-1)->currentMove != MOVE_NONE);
+ assert((ss-1)->currentMove != MOVE_NULL);
MovePicker mp(pos, ttMove, H, pos.captured_piece_type());
CheckInfo ci(pos);
- while ((move = mp.get_next_move()) != MOVE_NONE)
+ while ((move = mp.next_move()) != MOVE_NONE)
if (pos.pl_move_is_legal(move, ci.pinned))
{
+ ss->currentMove = move;
pos.do_move(move, st, ci, pos.move_gives_check(move, ci));
value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, rdepth);
pos.undo_move(move);
split_point_start: // At split points actual search starts from here
- // Initialize a MovePicker object for the current position
MovePickerExt<SpNode> mp(pos, ttMove, depth, H, ss, PvNode ? -VALUE_INFINITE : beta);
CheckInfo ci(pos);
- ss->bestMove = MOVE_NONE;
futilityBase = ss->eval + ss->evalMargin;
singularExtensionNode = !RootNode
&& !SpNode
&& depth >= SingularExtensionDepth[PvNode]
&& ttMove != MOVE_NONE
- && !excludedMove // Do not allow recursive singular extension search
- && (tte->type() & VALUE_TYPE_LOWER)
+ && !excludedMove // Recursive singular search is not allowed
+ && (tte->type() & BOUND_LOWER)
&& tte->depth() >= depth - 3 * ONE_PLY;
- if (SpNode)
- {
- lock_grab(&(sp->lock));
- bestValue = sp->bestValue;
- }
// Step 11. Loop through moves
// Loop through all pseudo-legal moves until no moves remain or a beta cutoff occurs
while ( bestValue < beta
- && (move = mp.get_next_move()) != MOVE_NONE
- && !thread.cutoff_occurred())
+ && (move = mp.next_move()) != MOVE_NONE
+ && !thread.cutoff_occurred()
+ && !Signals.stop)
{
assert(is_ok(move));
// At root obey the "searchmoves" option and skip moves not listed in Root
// Move List, as a consequence any illegal move is also skipped. In MultiPV
// mode we also skip PV moves which have been already searched.
- if (RootNode && !Rml.find(move, MultiPVIdx))
+ if (RootNode && !count(RootMoves.begin() + PVIdx, RootMoves.end(), move))
continue;
// At PV and SpNode nodes we want all moves to be legal since the beginning
if (SpNode)
{
moveCount = ++sp->moveCount;
- lock_release(&(sp->lock));
+ lock_release(sp->lock);
}
else
moveCount++;
if (RootNode)
{
- // This is used by time management
- FirstRootMove = (moveCount == 1);
-
- // Save the current node count before the move is searched
- nodes = pos.nodes_searched();
+ Signals.firstRootMove = (moveCount == 1);
- // For long searches send current move info to GUI
- if (pos.thread() == 0 && elapsed_search_time() > 2000)
- cout << "info" << depth_to_uci(depth)
- << " currmove " << move
- << " currmovenumber " << moveCount + MultiPVIdx << endl;
+ if (pos.this_thread() == 0 && SearchTime.elapsed() > 2000)
+ cout << "info depth " << depth / ONE_PLY
+ << " currmove " << move_to_uci(move, Chess960)
+ << " currmovenumber " << moveCount + PVIdx << endl;
}
- // At Root and at first iteration do a PV search on all the moves to score root moves
- isPvMove = (PvNode && moveCount <= (RootNode && depth <= ONE_PLY ? MAX_MOVES : 1));
- givesCheck = pos.move_gives_check(move, ci);
+ isPvMove = (PvNode && moveCount <= 1);
captureOrPromotion = pos.is_capture_or_promotion(move);
+ givesCheck = pos.move_gives_check(move, ci);
+ dangerous = givesCheck || is_dangerous(pos, move, captureOrPromotion);
+ ext = DEPTH_ZERO;
- // Step 12. Decide the new search depth
- ext = extension<PvNode>(pos, move, captureOrPromotion, givesCheck, &dangerous);
+ // Step 12. Extend checks and, in PV nodes, also dangerous moves
+ if (PvNode && dangerous)
+ ext = ONE_PLY;
+
+ else if (givesCheck && pos.see_sign(move) >= 0)
+ ext = PvNode ? ONE_PLY : ONE_PLY / 2;
// Singular extension search. If all moves but one fail low on a search of
// (alpha-s, beta-s), and just one fails high on (alpha, beta), then that move
// on all the other moves but the ttMove, if result is lower than ttValue minus
// a margin then we extend ttMove.
if ( singularExtensionNode
+ && !ext
&& move == ttMove
- && pos.pl_move_is_legal(move, ci.pinned)
- && ext < ONE_PLY)
+ && pos.pl_move_is_legal(move, ci.pinned))
{
- Value ttValue = value_from_tt(tte->value(), ss->ply);
-
if (abs(ttValue) < VALUE_KNOWN_WIN)
{
Value rBeta = ttValue - int(depth);
ss->excludedMove = move;
ss->skipNullMove = true;
- Value v = search<NonPV>(pos, ss, rBeta - 1, rBeta, depth / 2);
+ value = search<NonPV>(pos, ss, rBeta - 1, rBeta, depth / 2);
ss->skipNullMove = false;
ss->excludedMove = MOVE_NONE;
- ss->bestMove = MOVE_NONE;
- if (v < rBeta)
+ if (value < rBeta)
ext = ONE_PLY;
}
}
&& !inCheck
&& !dangerous
&& move != ttMove
- && !is_castle(move))
+ && !is_castle(move)
+ && (bestValue > VALUE_MATED_IN_MAX_PLY || bestValue == -VALUE_INFINITE))
{
// Move count based pruning
if ( moveCount >= futility_move_count(depth)
- && (!threatMove || !connected_threat(pos, move, threatMove))
- && bestValue > VALUE_MATED_IN_PLY_MAX) // FIXME bestValue is racy
+ && (!threatMove || !connected_threat(pos, move, threatMove)))
{
if (SpNode)
- lock_grab(&(sp->lock));
+ lock_grab(sp->lock);
continue;
}
// but fixing this made program slightly weaker.
Depth predictedDepth = newDepth - reduction<PvNode>(depth, moveCount);
futilityValue = futilityBase + futility_margin(predictedDepth, moveCount)
- + H.gain(pos.piece_on(move_from(move)), move_to(move));
+ + H.gain(pos.piece_moved(move), to_sq(move));
if (futilityValue < beta)
{
if (SpNode)
- {
- lock_grab(&(sp->lock));
- if (futilityValue > sp->bestValue)
- sp->bestValue = bestValue = futilityValue;
- }
- else if (futilityValue > bestValue)
- bestValue = futilityValue;
+ lock_grab(sp->lock);
continue;
}
// Prune moves with negative SEE at low depths
if ( predictedDepth < 2 * ONE_PLY
- && bestValue > VALUE_MATED_IN_PLY_MAX
&& pos.see_sign(move) < 0)
{
if (SpNode)
- lock_grab(&(sp->lock));
+ lock_grab(sp->lock);
continue;
}
// Step 14. Make the move
pos.do_move(move, st, ci, givesCheck);
- // Step extra. pv search (only in PV nodes)
- // The first move in list is the expected PV
- if (isPvMove)
- value = newDepth < ONE_PLY ? -qsearch<PV>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
- : - search<PV>(pos, ss+1, -beta, -alpha, newDepth);
- else
+ // Step 15. Reduced depth search (LMR). If the move fails high will be
+ // re-searched at full depth.
+ if ( depth > 3 * ONE_PLY
+ && !isPvMove
+ && !captureOrPromotion
+ && !dangerous
+ && !is_castle(move)
+ && ss->killers[0] != move
+ && ss->killers[1] != move)
{
- // Step 15. Reduced depth search
- // If the move fails high will be re-searched at full depth.
- bool doFullDepthSearch = true;
-
- if ( depth > 3 * ONE_PLY
- && !captureOrPromotion
- && !dangerous
- && !is_castle(move)
- && ss->killers[0] != move
- && ss->killers[1] != move
- && (ss->reduction = reduction<PvNode>(depth, moveCount)) != DEPTH_ZERO)
- {
- Depth d = newDepth - ss->reduction;
- alpha = SpNode ? sp->alpha : alpha;
+ ss->reduction = reduction<PvNode>(depth, moveCount);
+ Depth d = std::max(newDepth - ss->reduction, ONE_PLY);
+ alpha = SpNode ? sp->alpha : alpha;
- value = d < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
- : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d);
+ value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d);
- ss->reduction = DEPTH_ZERO;
- doFullDepthSearch = (value > alpha);
- }
+ doFullDepthSearch = (value > alpha && ss->reduction != DEPTH_ZERO);
+ ss->reduction = DEPTH_ZERO;
+ }
+ else
+ doFullDepthSearch = !isPvMove;
- // Step 16. Full depth search
- if (doFullDepthSearch)
- {
- alpha = SpNode ? sp->alpha : alpha;
- value = newDepth < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
- : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth);
-
- // Step extra. pv search (only in PV nodes)
- // Search only for possible new PV nodes, if instead value >= beta then
- // parent node fails low with value <= alpha and tries another move.
- if (PvNode && value > alpha && (RootNode || value < beta))
- value = newDepth < ONE_PLY ? -qsearch<PV>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
- : - search<PV>(pos, ss+1, -beta, -alpha, newDepth);
- }
+ // Step 16. Full depth search, when LMR is skipped or fails high
+ if (doFullDepthSearch)
+ {
+ alpha = SpNode ? sp->alpha : alpha;
+ value = newDepth < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
+ : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth);
}
+ // Only for PV nodes do a full PV search on the first move or after a fail
+ // high, in the latter case search only if value < beta, otherwise let the
+ // parent node to fail low with value <= alpha and to try another move.
+ if (PvNode && (isPvMove || (value > alpha && (RootNode || value < beta))))
+ value = newDepth < ONE_PLY ? -qsearch<PV>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
+ : - search<PV>(pos, ss+1, -beta, -alpha, newDepth);
+
// Step 17. Undo move
pos.undo_move(move);
// Step 18. Check for new best move
if (SpNode)
{
- lock_grab(&(sp->lock));
+ lock_grab(sp->lock);
bestValue = sp->bestValue;
alpha = sp->alpha;
}
- // Finished searching the move. If StopRequest is true, the search
+ // Finished searching the move. If Signals.stop 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 don't update the best move and/or PV.
- if (RootNode && !StopRequest)
+ if (RootNode && !Signals.stop)
{
- // Remember searched nodes counts for this move
- RootMove* rm = Rml.find(move);
- rm->nodes += pos.nodes_searched() - nodes;
+ RootMove& rm = *find(RootMoves.begin(), RootMoves.end(), move);
// PV move or new best move ?
if (isPvMove || value > alpha)
{
- // Update PV
- rm->score = value;
- rm->extract_pv_from_tt(pos);
+ rm.score = value;
+ rm.extract_pv_from_tt(pos);
// We record how often the best move has been changed in each
// iteration. This information is used for time management: When
// the best move changes frequently, we allocate some more time.
if (!isPvMove && MultiPV == 1)
- Rml.bestMoveChanges++;
+ BestMoveChanges++;
}
else
// All other moves but the PV are set to the lowest value, this
// is not a problem when sorting becuase sort is stable and move
// position in the list is preserved, just the PV is pushed up.
- rm->score = -VALUE_INFINITE;
+ rm.score = -VALUE_INFINITE;
- } // RootNode
+ }
if (value > bestValue)
{
bestValue = value;
- ss->bestMove = move;
+ bestMove = move;
if ( PvNode
&& value > alpha
if (SpNode && !thread.cutoff_occurred())
{
sp->bestValue = value;
- sp->ss->bestMove = move;
+ sp->bestMove = move;
sp->alpha = alpha;
- sp->is_betaCutoff = (value >= beta);
+
+ if (value >= beta)
+ sp->cutoff = true;
}
}
if ( !SpNode
&& depth >= Threads.min_split_depth()
&& bestValue < beta
- && Threads.available_slave_exists(pos.thread())
- && !StopRequest
+ && Threads.available_slave_exists(pos.this_thread())
+ && !Signals.stop
&& !thread.cutoff_occurred())
- bestValue = Threads.split<FakeSplit>(pos, ss, alpha, beta, bestValue, depth,
- threatMove, moveCount, &mp, NT);
+ bestValue = Threads.split<FakeSplit>(pos, ss, alpha, beta, bestValue, &bestMove,
+ depth, threatMove, moveCount, &mp, NT);
}
// Step 20. Check for mate and stalemate
// All legal moves have been searched and if there are no legal moves, it
// must be mate or stalemate. Note that we can have a false positive in
- // case of StopRequest or thread.cutoff_occurred() are set, but this is
+ // case of Signals.stop or thread.cutoff_occurred() are set, but this is
// harmless because return value is discarded anyhow in the parent nodes.
// If we are in a singular extension search then return a fail low score.
- if (!SpNode && !moveCount)
- return excludedMove ? oldAlpha : inCheck ? value_mated_in(ss->ply) : VALUE_DRAW;
+ if (!moveCount)
+ return excludedMove ? oldAlpha : inCheck ? mated_in(ss->ply) : VALUE_DRAW;
+
+ // If we have pruned all the moves without searching return a fail-low score
+ if (bestValue == -VALUE_INFINITE)
+ {
+ assert(!playedMoveCount);
+
+ bestValue = oldAlpha;
+ }
// Step 21. Update tables
- // If the search is not aborted, update the transposition table,
- // history counters, and killer moves.
- if (!SpNode && !StopRequest && !thread.cutoff_occurred())
+ // Update transposition table entry, killers and history
+ if (!SpNode && !Signals.stop && !thread.cutoff_occurred())
{
- move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove;
- vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER
- : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT;
+ move = bestValue <= oldAlpha ? MOVE_NONE : bestMove;
+ bt = bestValue <= oldAlpha ? BOUND_UPPER
+ : bestValue >= beta ? BOUND_LOWER : BOUND_EXACT;
- TT.store(posKey, value_to_tt(bestValue, ss->ply), vt, depth, move, ss->eval, ss->evalMargin);
+ TT.store(posKey, value_to_tt(bestValue, ss->ply), bt, depth, move, ss->eval, ss->evalMargin);
- // Update killers and history only for non capture moves that fails high
+ // Update killers and history for non capture cut-off moves
if ( bestValue >= beta
- && !pos.is_capture_or_promotion(move))
+ && !pos.is_capture_or_promotion(move)
+ && !inCheck)
{
if (move != ss->killers[0])
{
ss->killers[1] = ss->killers[0];
ss->killers[0] = move;
}
- update_history(pos, move, depth, movesSearched, playedMoveCount);
- }
- }
- if (SpNode)
- {
- // Here we have the lock still grabbed
- sp->is_slave[pos.thread()] = false;
- sp->nodes += pos.nodes_searched();
- lock_release(&(sp->lock));
+ // Increase history value of the cut-off move
+ Value bonus = Value(int(depth) * int(depth));
+ H.add(pos.piece_moved(move), to_sq(move), bonus);
+
+ // Decrease history of all the other played non-capture moves
+ for (int i = 0; i < playedMoveCount - 1; i++)
+ {
+ Move m = movesSearched[i];
+ H.add(pos.piece_moved(m), to_sq(m), -bonus);
+ }
+ }
}
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
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 ONE_PLY).
template <NodeType NT>
- Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) {
+ Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
const bool PvNode = (NT == PV);
assert(NT == PV || NT == NonPV);
- assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
- assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
- assert(PvNode || alpha == beta - 1);
- assert(depth <= 0);
- assert(pos.thread() >= 0 && pos.thread() < Threads.size());
+ assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE);
+ assert((alpha == beta - 1) || PvNode);
+ assert(depth <= DEPTH_ZERO);
+ assert(pos.this_thread() >= 0 && pos.this_thread() < Threads.size());
StateInfo st;
- Move ttMove, move;
- Value bestValue, value, evalMargin, futilityValue, futilityBase;
+ Move ttMove, move, bestMove;
+ Value ttValue, bestValue, value, evalMargin, futilityValue, futilityBase;
bool inCheck, enoughMaterial, givesCheck, evasionPrunable;
const TTEntry* tte;
Depth ttDepth;
- ValueType vt;
+ Bound bt;
Value oldAlpha = alpha;
- ss->bestMove = ss->currentMove = MOVE_NONE;
+ ss->currentMove = bestMove = MOVE_NONE;
ss->ply = (ss-1)->ply + 1;
// Check for an instant draw or maximum ply reached
- if (pos.is_draw<true>() || ss->ply > PLY_MAX)
+ if (pos.is_draw<true>() || ss->ply > MAX_PLY)
return VALUE_DRAW;
// Decide whether or not to include checks, this fixes also the type of
// Transposition table lookup. At PV nodes, we don't use the TT for
// pruning, but only for move ordering.
- tte = TT.probe(pos.get_key());
+ tte = TT.probe(pos.key());
ttMove = (tte ? tte->move() : MOVE_NONE);
+ ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_ZERO;
- if (!PvNode && tte && can_return_tt(tte, ttDepth, beta, ss->ply))
+ if (!PvNode && tte && can_return_tt(tte, ttDepth, ttValue, beta))
{
- ss->bestMove = ttMove; // Can be MOVE_NONE
- return value_from_tt(tte->value(), ss->ply);
+ ss->currentMove = ttMove; // Can be MOVE_NONE
+ return ttValue;
}
// Evaluate the position statically
if (bestValue >= beta)
{
if (!tte)
- TT.store(pos.get_key(), value_to_tt(bestValue, ss->ply), VALUE_TYPE_LOWER, DEPTH_NONE, MOVE_NONE, ss->eval, evalMargin);
+ TT.store(pos.key(), value_to_tt(bestValue, ss->ply), BOUND_LOWER, DEPTH_NONE, MOVE_NONE, ss->eval, evalMargin);
return bestValue;
}
if (PvNode && bestValue > alpha)
alpha = bestValue;
- // Futility pruning parameters, not needed when in check
futilityBase = ss->eval + evalMargin + FutilityMarginQS;
enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame;
}
// to search the moves. Because the depth is <= 0 here, only captures,
// queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will
// be generated.
- MovePicker mp(pos, ttMove, depth, H, move_to((ss-1)->currentMove));
+ MovePicker mp(pos, ttMove, depth, H, to_sq((ss-1)->currentMove));
CheckInfo ci(pos);
// Loop through the moves until no moves remain or a beta cutoff occurs
while ( bestValue < beta
- && (move = mp.get_next_move()) != MOVE_NONE)
+ && (move = mp.next_move()) != MOVE_NONE)
{
assert(is_ok(move));
&& !pos.is_passed_pawn_push(move))
{
futilityValue = futilityBase
- + PieceValueEndgame[pos.piece_on(move_to(move))]
+ + PieceValueEndgame[pos.piece_on(to_sq(move))]
+ (is_enpassant(move) ? PawnValueEndgame : VALUE_ZERO);
if (futilityValue < beta)
// Detect non-capture evasions that are candidate to be pruned
evasionPrunable = !PvNode
&& inCheck
- && bestValue > VALUE_MATED_IN_PLY_MAX
+ && bestValue > VALUE_MATED_IN_MAX_PLY
&& !pos.is_capture(move)
&& !pos.can_castle(pos.side_to_move());
&& move != ttMove
&& !pos.is_capture_or_promotion(move)
&& ss->eval + PawnValueMidgame / 4 < beta
- && !check_is_dangerous(pos, move, futilityBase, beta, &bestValue))
- {
- if (ss->eval + PawnValueMidgame / 4 > bestValue)
- bestValue = ss->eval + PawnValueMidgame / 4;
-
+ && !check_is_dangerous(pos, move, futilityBase, beta))
continue;
- }
// Check for legality only before to do the move
if (!pos.pl_move_is_legal(move, ci.pinned))
continue;
- // Update current move
ss->currentMove = move;
// Make and search the move
if (value > bestValue)
{
bestValue = value;
- ss->bestMove = move;
+ bestMove = move;
if ( PvNode
&& value > alpha
// All legal moves have been searched. A special case: If we're in check
// and no legal moves were found, it is checkmate.
if (inCheck && bestValue == -VALUE_INFINITE)
- return value_mated_in(ss->ply);
+ return mated_in(ss->ply); // Plies to mate from the root
// Update transposition table
- move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove;
- vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER
- : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT;
+ move = bestValue <= oldAlpha ? MOVE_NONE : bestMove;
+ bt = bestValue <= oldAlpha ? BOUND_UPPER
+ : bestValue >= beta ? BOUND_LOWER : BOUND_EXACT;
- TT.store(pos.get_key(), value_to_tt(bestValue, ss->ply), vt, ttDepth, move, ss->eval, evalMargin);
+ TT.store(pos.key(), value_to_tt(bestValue, ss->ply), bt, ttDepth, move, ss->eval, evalMargin);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
// bestValue is updated only when returning false because in that case move
// will be pruned.
- bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bestValue)
+ bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta)
{
Bitboard b, occ, oldAtt, newAtt, kingAtt;
- Square from, to, ksq, victimSq;
+ Square from, to, ksq;
Piece pc;
Color them;
- Value futilityValue, bv = *bestValue;
- from = move_from(move);
- to = move_to(move);
- them = flip(pos.side_to_move());
+ from = from_sq(move);
+ to = to_sq(move);
+ them = ~pos.side_to_move();
ksq = pos.king_square(them);
kingAtt = pos.attacks_from<KING>(ksq);
- pc = pos.piece_on(from);
+ pc = pos.piece_moved(move);
- occ = pos.occupied_squares() & ~(1ULL << from) & ~(1ULL << ksq);
+ occ = pos.pieces() ^ from ^ ksq;
oldAtt = pos.attacks_from(pc, from, occ);
newAtt = pos.attacks_from(pc, to, occ);
// Rule 1. Checks which give opponent's king at most one escape square are dangerous
b = kingAtt & ~pos.pieces(them) & ~newAtt & ~(1ULL << to);
- if (!(b && (b & (b - 1))))
+ if (single_bit(b)) // Catches also !b
return true;
// Rule 2. Queen contact check is very dangerous
- if ( type_of(pc) == QUEEN
- && bit_is_set(kingAtt, to))
+ if (type_of(pc) == QUEEN && (kingAtt & to))
return true;
// Rule 3. Creating new double threats with checks
b = pos.pieces(them) & newAtt & ~oldAtt & ~(1ULL << ksq);
-
while (b)
{
- victimSq = pop_1st_bit(&b);
- futilityValue = futilityBase + PieceValueEndgame[pos.piece_on(victimSq)];
-
// Note that here we generate illegal "double move"!
- if ( futilityValue >= beta
- && pos.see_sign(make_move(from, victimSq)) >= 0)
+ if (futilityBase + PieceValueEndgame[pos.piece_on(pop_1st_bit(&b))] >= beta)
return true;
-
- if (futilityValue > bv)
- bv = futilityValue;
}
- // Update bestValue only if check is not dangerous (because we will prune the move)
- *bestValue = bv;
return false;
}
assert(is_ok(m2));
// Case 1: The moving piece is the same in both moves
- f2 = move_from(m2);
- t1 = move_to(m1);
+ f2 = from_sq(m2);
+ t1 = to_sq(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);
+ t2 = to_sq(m2);
+ f1 = from_sq(m1);
if (t2 == f1)
return true;
// Case 3: Moving through the vacated square
p2 = pos.piece_on(f2);
- if ( piece_is_slider(p2)
- && bit_is_set(squares_between(f2, t2), f1))
+ if (piece_is_slider(p2) && (squares_between(f2, t2) & f1))
return true;
// Case 4: The destination square for m2 is defended by the moving piece in m1
p1 = pos.piece_on(t1);
- if (bit_is_set(pos.attacks_from(p1, t1), t2))
+ if (pos.attacks_from(p1, t1) & t2)
return true;
// Case 5: Discovered check, checking piece is the piece moved in m1
ksq = pos.king_square(pos.side_to_move());
if ( piece_is_slider(p1)
- && bit_is_set(squares_between(t1, ksq), f2))
- {
- Bitboard occ = pos.occupied_squares();
- clear_bit(&occ, f2);
- if (bit_is_set(pos.attacks_from(p1, t1, occ), ksq))
- return true;
- }
+ && (squares_between(t1, ksq) & f2)
+ && (pos.attacks_from(p1, t1, pos.pieces() ^ f2) & ksq))
+ return true;
+
return false;
}
// value_to_tt() adjusts a mate score from "plies to mate from the root" to
- // "plies to mate from the current ply". Non-mate scores are unchanged.
+ // "plies to mate from the current position". Non-mate scores are unchanged.
// The function is called before storing a value to the transposition table.
Value value_to_tt(Value v, int ply) {
- if (v >= VALUE_MATE_IN_PLY_MAX)
+ if (v >= VALUE_MATE_IN_MAX_PLY)
return v + ply;
- if (v <= VALUE_MATED_IN_PLY_MAX)
+ if (v <= VALUE_MATED_IN_MAX_PLY)
return v - ply;
return v;
}
- // value_from_tt() is the inverse of value_to_tt(): It adjusts a mate score from
- // the transposition table to a mate score corrected for the current ply.
+ // value_from_tt() is the inverse of value_to_tt(): It adjusts a mate score
+ // from the transposition table (where refers to the plies to mate/be mated
+ // from current position) to "plies to mate/be mated from the root".
Value value_from_tt(Value v, int ply) {
- if (v >= VALUE_MATE_IN_PLY_MAX)
+ if (v >= VALUE_MATE_IN_MAX_PLY)
return v - ply;
- if (v <= VALUE_MATED_IN_PLY_MAX)
+ if (v <= VALUE_MATED_IN_MAX_PLY)
return v + ply;
return v;
Square mfrom, mto, tfrom, tto;
- mfrom = move_from(m);
- mto = move_to(m);
- tfrom = move_from(threat);
- tto = move_to(threat);
+ mfrom = from_sq(m);
+ mto = to_sq(m);
+ tfrom = from_sq(threat);
+ tto = to_sq(threat);
// Case 1: Don't prune moves which move the threatened piece
if (mfrom == tto)
// Case 3: If the moving piece in the threatened move is a slider, don't
// prune safe moves which block its ray.
- if ( piece_is_slider(pos.piece_on(tfrom))
- && bit_is_set(squares_between(tfrom, tto), mto)
- && pos.see_sign(m) >= 0)
+ if ( piece_is_slider(pos.piece_on(tfrom))
+ && (squares_between(tfrom, tto) & mto)
+ && pos.see_sign(m) >= 0)
return true;
return false;
}
- // can_return_tt() returns true if a transposition table score
- // can be used to cut-off at a given point in search.
-
- bool can_return_tt(const TTEntry* tte, Depth depth, Value beta, int ply) {
+ // can_return_tt() returns true if a transposition table score can be used to
+ // cut-off at a given point in search.
- Value v = value_from_tt(tte->value(), ply);
+ bool can_return_tt(const TTEntry* tte, Depth depth, Value v, Value beta) {
return ( tte->depth() >= depth
- || v >= std::max(VALUE_MATE_IN_PLY_MAX, beta)
- || v < std::min(VALUE_MATED_IN_PLY_MAX, beta))
+ || v >= std::max(VALUE_MATE_IN_MAX_PLY, beta)
+ || v < std::min(VALUE_MATED_IN_MAX_PLY, beta))
- && ( ((tte->type() & VALUE_TYPE_LOWER) && v >= beta)
- || ((tte->type() & VALUE_TYPE_UPPER) && v < beta));
+ && ( ((tte->type() & BOUND_LOWER) && v >= beta)
+ || ((tte->type() & BOUND_UPPER) && v < beta));
}
- // refine_eval() returns the transposition table score if
- // possible otherwise falls back on static position evaluation.
+ // refine_eval() returns the transposition table score if possible, otherwise
+ // falls back on static position evaluation.
- Value refine_eval(const TTEntry* tte, Value defaultEval, int ply) {
+ Value refine_eval(const TTEntry* tte, Value v, Value defaultEval) {
assert(tte);
- Value v = value_from_tt(tte->value(), ply);
-
- if ( ((tte->type() & VALUE_TYPE_LOWER) && v >= defaultEval)
- || ((tte->type() & VALUE_TYPE_UPPER) && v < defaultEval))
+ if ( ((tte->type() & BOUND_LOWER) && v >= defaultEval)
+ || ((tte->type() & BOUND_UPPER) && v < defaultEval))
return v;
return defaultEval;
}
- // 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 move, Depth depth,
- Move movesSearched[], int moveCount) {
- Move m;
- Value bonus = Value(int(depth) * int(depth));
-
- H.update(pos.piece_on(move_from(move)), move_to(move), bonus);
-
- for (int i = 0; i < moveCount - 1; i++)
- {
- m = movesSearched[i];
-
- assert(m != move);
-
- H.update(pos.piece_on(move_from(m)), move_to(m), -bonus);
- }
- }
-
-
- // current_search_time() returns the number of milliseconds which have passed
- // since the beginning of the current search.
-
- int elapsed_search_time(int set) {
-
- static int searchStartTime;
-
- if (set)
- searchStartTime = set;
-
- return get_system_time() - searchStartTime;
- }
-
-
// score_to_uci() converts a value to a string suitable for use with the UCI
// protocol specifications:
//
std::stringstream s;
- if (abs(v) < VALUE_MATE - PLY_MAX * ONE_PLY)
- s << " score cp " << int(v) * 100 / int(PawnValueMidgame); // Scale to centipawns
+ if (abs(v) < VALUE_MATE_IN_MAX_PLY)
+ s << "cp " << v * 100 / int(PawnValueMidgame);
else
- s << " score mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2;
+ s << "mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2;
s << (v >= beta ? " lowerbound" : v <= alpha ? " upperbound" : "");
}
- // speed_to_uci() returns a string with time stats of current search suitable
- // to be sent to UCI gui.
-
- string speed_to_uci(int64_t nodes) {
-
- std::stringstream s;
- int t = elapsed_search_time();
-
- s << " nodes " << nodes
- << " nps " << (t > 0 ? int(nodes * 1000 / t) : 0)
- << " time " << t;
-
- return s.str();
- }
-
- // pv_to_uci() returns a string with information on the current PV line
- // formatted according to UCI specification.
-
- string pv_to_uci(const Move pv[], int pvNum, bool chess960) {
-
- std::stringstream s;
+ // pv_info_to_uci() sends search info to GUI. UCI protocol requires to send all
+ // the PV lines also if are still to be searched and so refer to the previous
+ // search score.
- s << " multipv " << pvNum << " pv " << set960(chess960);
-
- for ( ; *pv != MOVE_NONE; pv++)
- s << *pv << " ";
-
- return s.str();
- }
+ void pv_info_to_uci(const Position& pos, int depth, Value alpha, Value beta) {
- // depth_to_uci() returns a string with information on the current depth and
- // seldepth formatted according to UCI specification.
-
- string depth_to_uci(Depth depth) {
-
- std::stringstream s;
-
- // Retrieve max searched depth among threads
+ int t = SearchTime.elapsed();
int selDepth = 0;
+
for (int i = 0; i < Threads.size(); i++)
if (Threads[i].maxPly > selDepth)
selDepth = Threads[i].maxPly;
- s << " depth " << depth / ONE_PLY << " seldepth " << selDepth;
+ for (size_t i = 0; i < std::min(UCIMultiPV, RootMoves.size()); i++)
+ {
+ bool updated = (i <= PVIdx);
- return s.str();
+ if (depth == 1 && !updated)
+ continue;
+
+ int d = (updated ? depth : depth - 1);
+ Value v = (updated ? RootMoves[i].score : RootMoves[i].prevScore);
+ std::stringstream s;
+
+ for (int j = 0; RootMoves[i].pv[j] != MOVE_NONE; j++)
+ s << " " << move_to_uci(RootMoves[i].pv[j], Chess960);
+
+ cout << "info depth " << d
+ << " seldepth " << selDepth
+ << " score " << (i == PVIdx ? score_to_uci(v, alpha, beta) : score_to_uci(v))
+ << " nodes " << pos.nodes_searched()
+ << " nps " << (t > 0 ? pos.nodes_searched() * 1000 / t : 0)
+ << " time " << t
+ << " multipv " << i + 1
+ << " pv" << s.str() << endl;
+ }
}
+
+ // pv_info_to_log() writes human-readable search information to the log file
+ // (which is created when the UCI parameter "Use Search Log" is "true"). It
+ // uses the two below helpers to pretty format time and score respectively.
+
string time_to_string(int millisecs) {
const int MSecMinute = 1000 * 60;
if (hours)
s << hours << ':';
- s << std::setfill('0') << std::setw(2) << minutes << ':' << std::setw(2) << seconds;
+ s << std::setfill('0') << std::setw(2) << minutes << ':'
+ << std::setw(2) << seconds;
return s.str();
}
std::stringstream s;
- if (v >= VALUE_MATE_IN_PLY_MAX)
+ if (v >= VALUE_MATE_IN_MAX_PLY)
s << "#" << (VALUE_MATE - v + 1) / 2;
- else if (v <= VALUE_MATED_IN_PLY_MAX)
+ else if (v <= VALUE_MATED_IN_MAX_PLY)
s << "-#" << (VALUE_MATE + v) / 2;
else
- s << std::setprecision(2) << std::fixed << std::showpos << float(v) / PawnValueMidgame;
+ s << std::setprecision(2) << std::fixed << std::showpos
+ << float(v) / PawnValueMidgame;
return s.str();
}
- // pretty_pv() creates a human-readable string from a position and a PV.
- // It is used to write search information to the log file (which is created
- // when the UCI parameter "Use Search Log" is "true").
-
- string pretty_pv(Position& pos, int depth, Value value, int time, Move pv[]) {
+ void pv_info_to_log(Position& pos, int depth, Value value, int time, Move pv[]) {
const int64_t K = 1000;
const int64_t M = 1000000;
- const int startColumn = 28;
- const size_t maxLength = 80 - startColumn;
- StateInfo state[PLY_MAX_PLUS_2], *st = state;
+ StateInfo state[MAX_PLY_PLUS_2], *st = state;
Move* m = pv;
- string san;
+ string san, padding;
+ size_t length;
std::stringstream s;
- size_t length = 0;
- // First print depth, score, time and searched nodes...
- s << set960(pos.is_chess960())
- << std::setw(2) << depth
+ s << std::setw(2) << depth
<< std::setw(8) << score_to_string(value)
<< std::setw(8) << time_to_string(time);
if (pos.nodes_searched() < M)
s << std::setw(8) << pos.nodes_searched() / 1 << " ";
+
else if (pos.nodes_searched() < K * M)
s << std::setw(7) << pos.nodes_searched() / K << "K ";
+
else
s << std::setw(7) << pos.nodes_searched() / M << "M ";
- // ...then print the full PV line in short algebraic notation
+ padding = string(s.str().length(), ' ');
+ length = padding.length();
+
while (*m != MOVE_NONE)
{
san = move_to_san(pos, *m);
- length += san.length() + 1;
- if (length > maxLength)
+ if (length + san.length() > 80)
{
- length = san.length() + 1;
- s << "\n" + string(startColumn, ' ');
+ s << "\n" + padding;
+ length = padding.length();
}
+
s << san << ' ';
+ length += san.length() + 1;
pos.do_move(*m++, *st++);
}
- // Restore original position before to leave
- while (m != pv) pos.undo_move(*--m);
-
- return s.str();
- }
-
-
- // 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.
-
- void wait_for_stop_or_ponderhit() {
-
- string cmd;
+ while (m != pv)
+ pos.undo_move(*--m);
- // Wait for a command from stdin
- while (cmd != "ponderhit" && cmd != "stop" && cmd != "quit")
- Threads.getline(cmd);
-
- if (cmd == "quit")
- QuitRequest = true;
+ Log l(Options["Search Log Filename"]);
+ l << s.str() << endl;
}
// When playing with strength handicap choose best move among the MultiPV set
// using a statistical rule dependent on SkillLevel. Idea by Heinz van Saanen.
- void do_skill_level(Move* best, Move* ponder) {
+
+ Move do_skill_level() {
assert(MultiPV > 1);
static RKISS rk;
- // Rml list is already sorted by score in descending order
- int s;
- int max_s = -VALUE_INFINITE;
- int size = std::min(MultiPV, (int)Rml.size());
- int max = Rml[0].score;
- int var = std::min(max - Rml[size - 1].score, int(PawnValueMidgame));
- int wk = 120 - 2 * SkillLevel;
-
- // PRNG sequence should be non deterministic
- for (int i = abs(get_system_time() % 50); i > 0; i--)
+ // PRNG sequence should be not deterministic
+ for (int i = Time::current_time().msec() % 50; i > 0; i--)
rk.rand<unsigned>();
- // Choose best move. For each move's score we add two terms both dependent
- // on wk, one deterministic and bigger for weaker moves, and one random,
+ // RootMoves are already sorted by score in descending order
+ size_t size = std::min(MultiPV, RootMoves.size());
+ int variance = std::min(RootMoves[0].score - RootMoves[size - 1].score, PawnValueMidgame);
+ int weakness = 120 - 2 * SkillLevel;
+ int max_s = -VALUE_INFINITE;
+ Move best = MOVE_NONE;
+
+ // Choose best move. For each move score we add two terms both dependent on
+ // weakness, one deterministic and bigger for weaker moves, and one random,
// then we choose the move with the resulting highest score.
- for (int i = 0; i < size; i++)
+ for (size_t i = 0; i < size; i++)
{
- s = Rml[i].score;
+ int s = RootMoves[i].score;
// Don't allow crazy blunders even at very low skills
- if (i > 0 && Rml[i-1].score > s + EasyMoveMargin)
+ if (i > 0 && RootMoves[i-1].score > s + EasyMoveMargin)
break;
- // This is our magical formula
- s += ((max - s) * wk + var * (rk.rand<unsigned>() % wk)) / 128;
+ // This is our magic formula
+ s += ( weakness * int(RootMoves[0].score - s)
+ + variance * (rk.rand<unsigned>() % weakness)) / 128;
if (s > max_s)
{
max_s = s;
- *best = Rml[i].pv[0];
- *ponder = Rml[i].pv[1];
+ best = RootMoves[i].pv[0];
}
}
+ return best;
}
+} // namespace
- /// RootMove and RootMoveList method's definitions
-
- void RootMoveList::init(Position& pos, Move searchMoves[]) {
-
- Move* sm;
- bestMoveChanges = 0;
- clear();
-
- // Generate all legal moves and add them to RootMoveList
- for (MoveList<MV_LEGAL> ml(pos); !ml.end(); ++ml)
- {
- // If we have a searchMoves[] list then verify the move
- // is in the list before to add it.
- for (sm = searchMoves; *sm && *sm != ml.move(); sm++) {}
-
- if (sm != searchMoves && *sm != ml.move())
- continue;
-
- RootMove rm;
- rm.pv.push_back(ml.move());
- rm.pv.push_back(MOVE_NONE);
- rm.score = rm.prevScore = -VALUE_INFINITE;
- rm.nodes = 0;
- push_back(rm);
- }
- }
-
- RootMove* RootMoveList::find(const Move& m, int startIndex) {
-
- for (size_t i = startIndex; i < size(); i++)
- if ((*this)[i].pv[0] == m)
- return &(*this)[i];
-
- return NULL;
- }
-
- // extract_pv_from_tt() builds a PV by adding moves from the transposition table.
- // We consider also failing high nodes and not only VALUE_TYPE_EXACT nodes. This
- // allow to always have a ponder move even when we fail high at root and also a
- // long PV to print that is important for position analysis.
- void RootMove::extract_pv_from_tt(Position& pos) {
+/// RootMove::extract_pv_from_tt() builds a PV by adding moves from the TT table.
+/// We consider also failing high nodes and not only BOUND_EXACT nodes so to
+/// allow to always have a ponder move even when we fail high at root, and a
+/// long PV to print that is important for position analysis.
- StateInfo state[PLY_MAX_PLUS_2], *st = state;
- TTEntry* tte;
- int ply = 1;
- Move m = pv[0];
+void RootMove::extract_pv_from_tt(Position& pos) {
- assert(m != MOVE_NONE && pos.is_pseudo_legal(m));
+ StateInfo state[MAX_PLY_PLUS_2], *st = state;
+ TTEntry* tte;
+ int ply = 1;
+ Move m = pv[0];
- pv.clear();
- pv.push_back(m);
- pos.do_move(m, *st++);
+ assert(m != MOVE_NONE && pos.is_pseudo_legal(m));
- while ( (tte = TT.probe(pos.get_key())) != NULL
- && tte->move() != MOVE_NONE
- && pos.is_pseudo_legal(tte->move())
- && pos.pl_move_is_legal(tte->move(), pos.pinned_pieces())
- && ply < PLY_MAX
- && (!pos.is_draw<false>() || ply < 2))
- {
- pv.push_back(tte->move());
- pos.do_move(tte->move(), *st++);
- ply++;
- }
- pv.push_back(MOVE_NONE);
+ pv.clear();
+ pv.push_back(m);
+ pos.do_move(m, *st++);
- do pos.undo_move(pv[--ply]); while (ply);
+ while ( (tte = TT.probe(pos.key())) != NULL
+ && (m = tte->move()) != MOVE_NONE // Local copy, TT entry could change
+ && pos.is_pseudo_legal(m)
+ && pos.pl_move_is_legal(m, pos.pinned_pieces())
+ && ply < MAX_PLY
+ && (!pos.is_draw<false>() || ply < 2))
+ {
+ pv.push_back(m);
+ pos.do_move(m, *st++);
+ ply++;
}
+ pv.push_back(MOVE_NONE);
- // insert_pv_in_tt() is called at the end of a search iteration, and inserts
- // the PV back into the TT. This makes sure the old PV moves are searched
- // first, even if the old TT entries have been overwritten.
-
- void RootMove::insert_pv_in_tt(Position& pos) {
-
- StateInfo state[PLY_MAX_PLUS_2], *st = state;
- TTEntry* tte;
- Key k;
- Value v, m = VALUE_NONE;
- int ply = 0;
+ do pos.undo_move(pv[--ply]); while (ply);
+}
- assert(pv[0] != MOVE_NONE && pos.is_pseudo_legal(pv[0]));
- do {
- k = pos.get_key();
- tte = TT.probe(k);
+/// RootMove::insert_pv_in_tt() is called at the end of a search iteration, and
+/// inserts the PV back into the TT. This makes sure the old PV moves are searched
+/// first, even if the old TT entries have been overwritten.
- // Don't overwrite existing correct entries
- if (!tte || tte->move() != pv[ply])
- {
- v = (pos.in_check() ? VALUE_NONE : evaluate(pos, m));
- TT.store(k, VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, pv[ply], v, m);
- }
- pos.do_move(pv[ply], *st++);
+void RootMove::insert_pv_in_tt(Position& pos) {
- } while (pv[++ply] != MOVE_NONE);
+ StateInfo state[MAX_PLY_PLUS_2], *st = state;
+ TTEntry* tte;
+ Key k;
+ Value v, m = VALUE_NONE;
+ int ply = 0;
- do pos.undo_move(pv[--ply]); while (ply);
- }
-} // namespace
+ assert(pv[ply] != MOVE_NONE && pos.is_pseudo_legal(pv[ply]));
+ do {
+ k = pos.key();
+ tte = TT.probe(k);
-// Little helper used by idle_loop() to check that all the slave threads of a
-// split point have finished searching.
-
-static bool all_slaves_finished(SplitPoint* sp) {
+ // Don't overwrite existing correct entries
+ if (!tte || tte->move() != pv[ply])
+ {
+ v = (pos.in_check() ? VALUE_NONE : evaluate(pos, m));
+ TT.store(k, VALUE_NONE, BOUND_NONE, DEPTH_NONE, pv[ply], v, m);
+ }
+ pos.do_move(pv[ply], *st++);
- for (int i = 0; i < Threads.size(); i++)
- if (sp->is_slave[i])
- return false;
+ } while (pv[++ply] != MOVE_NONE);
- return true;
+ do pos.undo_move(pv[--ply]); while (ply);
}
-// Thread::idle_loop() is where the thread is parked when it has no work to do.
-// The parameter 'sp', if non-NULL, is a pointer to an active SplitPoint object
-// for which the thread is the master.
+/// Thread::idle_loop() is where the thread is parked when it has no work to do.
+/// The parameter 'master_sp', if non-NULL, is a pointer to an active SplitPoint
+/// object for which the thread is the master.
-void Thread::idle_loop(SplitPoint* sp) {
+void Thread::idle_loop(SplitPoint* sp_master) {
- while (true)
+ // If this thread is the master of a split point and all slaves have
+ // finished their work at this split point, return from the idle loop.
+ while (!sp_master || sp_master->slavesMask)
{
// If we are not searching, wait for a condition to be signaled
// instead of wasting CPU time polling for work.
while ( do_sleep
- || do_terminate
- || (Threads.use_sleeping_threads() && !is_searching))
+ || do_exit
+ || (!is_searching && Threads.use_sleeping_threads()))
{
- assert((!sp && threadID) || Threads.use_sleeping_threads());
-
- // Slave thread should exit as soon as do_terminate flag raises
- if (do_terminate)
+ if (do_exit)
{
- assert(!sp);
+ assert(!sp_master);
return;
}
// Grab the lock to avoid races with Thread::wake_up()
- lock_grab(&sleepLock);
+ lock_grab(sleepLock);
// If we are master and all slaves have finished don't go to sleep
- if (sp && all_slaves_finished(sp))
+ if (sp_master && !sp_master->slavesMask)
{
- lock_release(&sleepLock);
+ lock_release(sleepLock);
break;
}
// in the meanwhile, allocated us and sent the wake_up() call before we
// had the chance to grab the lock.
if (do_sleep || !is_searching)
- cond_wait(&sleepCond, &sleepLock);
+ cond_wait(sleepCond, sleepLock);
- lock_release(&sleepLock);
+ lock_release(sleepLock);
}
// If this thread has been assigned work, launch a search
if (is_searching)
{
- assert(!do_terminate);
-
- // Copy split point position and search stack and call search()
- SearchStack ss[PLY_MAX_PLUS_2];
- SplitPoint* tsp = splitPoint;
- Position pos(*tsp->pos, threadID);
-
- memcpy(ss, tsp->ss - 1, 4 * sizeof(SearchStack));
- (ss+1)->sp = tsp;
-
- if (tsp->nodeType == Root)
- search<SplitPointRoot>(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth);
- else if (tsp->nodeType == PV)
- search<SplitPointPV>(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth);
- else if (tsp->nodeType == NonPV)
- search<SplitPointNonPV>(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth);
+ assert(!do_sleep && !do_exit);
+
+ lock_grab(Threads.splitLock);
+
+ assert(is_searching);
+ SplitPoint* sp = curSplitPoint;
+
+ lock_release(Threads.splitLock);
+
+ Stack ss[MAX_PLY_PLUS_2];
+ Position pos(*sp->pos, threadID);
+ int master = sp->master;
+
+ memcpy(ss, sp->ss - 1, 4 * sizeof(Stack));
+ (ss+1)->sp = sp;
+
+ lock_grab(sp->lock);
+
+ if (sp->nodeType == Root)
+ search<SplitPointRoot>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
+ else if (sp->nodeType == PV)
+ search<SplitPointPV>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
+ else if (sp->nodeType == NonPV)
+ search<SplitPointNonPV>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
else
assert(false);
assert(is_searching);
is_searching = false;
+ sp->slavesMask &= ~(1ULL << threadID);
+ sp->nodes += pos.nodes_searched();
+
+ // After releasing the lock we cannot access anymore any SplitPoint
+ // related data in a reliably way becuase it could have been released
+ // under our feet by the sp master.
+ lock_release(sp->lock);
// Wake up master thread so to allow it to return from the idle loop in
// case we are the last slave of the split point.
if ( Threads.use_sleeping_threads()
- && threadID != tsp->master
- && !Threads[tsp->master].is_searching)
- Threads[tsp->master].wake_up();
- }
-
- // If this thread is the master of a split point and all slaves have
- // finished their work at this split point, return from the idle loop.
- if (sp && all_slaves_finished(sp))
- {
- // Because sp->is_slave[] is reset under lock protection,
- // be sure sp->lock has been released before to return.
- lock_grab(&(sp->lock));
- lock_release(&(sp->lock));
- return;
+ && threadID != master
+ && !Threads[master].is_searching)
+ Threads[master].wake_up();
}
}
}
-// do_uci_async_cmd() is called by listener thread when in async mode and 'cmd'
-// input line is received from the GUI.
+/// check_time() is called by the timer thread when the timer triggers. It is
+/// used to print debug info and, more important, to detect when we are out of
+/// available time and so stop the search.
-void do_uci_async_cmd(const std::string& cmd) {
+void check_time() {
- if (cmd == "quit")
- {
- // Quit the program as soon as possible
- Limits.ponder = false;
- QuitRequest = StopRequest = true;
- }
- else if (cmd == "stop")
- {
- // Stop calculating as soon as possible, but still send the "bestmove"
- // and possibly the "ponder" token when finishing the search.
- Limits.ponder = false;
- StopRequest = true;
- }
- else if (cmd == "ponderhit")
- {
- // The opponent has played the expected move. GUI sends "ponderhit" if
- // we were told to ponder on the same move the opponent has played. We
- // should continue searching but switching from pondering to normal search.
- Limits.ponder = false;
+ static Time lastInfoTime = Time::current_time();
- if (StopOnPonderhit)
- StopRequest = true;
- }
-}
-
-
-// do_timer_event() is called by the timer thread when the timer triggers
-
-void do_timer_event() {
-
- static int lastInfoTime;
- int e = elapsed_search_time();
-
- // Print debug information every second
- if (get_system_time() - lastInfoTime >= 1000)
+ if (lastInfoTime.elapsed() >= 1000)
{
- lastInfoTime = get_system_time();
-
- dbg_print_mean();
- dbg_print_hit_rate();
+ lastInfoTime.restart();
+ dbg_print();
}
- // Should we stop the search?
if (Limits.ponder)
return;
- bool stillAtFirstMove = FirstRootMove
- && !AspirationFailLow
+ int e = SearchTime.elapsed();
+ bool stillAtFirstMove = Signals.firstRootMove
+ && !Signals.failedLowAtRoot
&& e > TimeMgr.available_time();
- bool noMoreTime = e > TimeMgr.maximum_time()
+ bool noMoreTime = e > TimeMgr.maximum_time() - 2 * TimerResolution
|| stillAtFirstMove;
- if ( (Limits.useTimeManagement() && noMoreTime)
- || (Limits.maxTime && e >= Limits.maxTime)
- /* missing nodes limit */ ) // FIXME
- StopRequest = true;
+ if ( (Limits.use_time_management() && noMoreTime)
+ || (Limits.movetime && e >= Limits.movetime))
+ Signals.stop = true;
}
projects / stockfish / blobdiff