Move best = MOVE_NONE;
};
- // EasyMoveManager structure is used to detect an 'easy move'. When the PV is stable
- // across multiple search iterations, we can quickly return the best move.
- struct EasyMoveManager {
-
- void clear() {
- stableCnt = 0;
- expectedPosKey = 0;
- pv[0] = pv[1] = pv[2] = MOVE_NONE;
- }
-
- Move get(Key key) const {
- return expectedPosKey == key ? pv[2] : MOVE_NONE;
- }
-
- void update(Position& pos, const std::vector<Move>& newPv) {
-
- assert(newPv.size() >= 3);
-
- // Keep track of how many times in a row the 3rd ply remains stable
- stableCnt = (newPv[2] == pv[2]) ? stableCnt + 1 : 0;
-
- if (!std::equal(newPv.begin(), newPv.begin() + 3, pv))
- {
- std::copy(newPv.begin(), newPv.begin() + 3, pv);
-
- StateInfo st[2];
- pos.do_move(newPv[0], st[0]);
- pos.do_move(newPv[1], st[1]);
- expectedPosKey = pos.key();
- pos.undo_move(newPv[1]);
- pos.undo_move(newPv[0]);
- }
- }
-
- Key expectedPosKey;
- int stableCnt;
- Move pv[3];
- };
-
- EasyMoveManager EasyMove;
Value DrawValue[COLOR_NB];
template <NodeType NT>
void update_pv(Move* pv, Move move, Move* childPv);
void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus);
void update_stats(const Position& pos, Stack* ss, Move move, Move* quiets, int quietsCnt, int bonus);
+ void update_capture_stats(const Position& pos, Move move, Move* captures, int captureCnt, int bonus);
+ bool pv_is_draw(Position& pos);
// perft() is our utility to verify move generation. All the leaf nodes up
// to the given depth are generated and counted, and the sum is returned.
Threads.main()->callsCnt = 0;
Threads.main()->previousScore = VALUE_INFINITE;
+ Threads.main()->previousTimeReduction = 1;
}
// Check if there are threads with a better score than main thread
Thread* bestThread = this;
- if ( !this->easyMovePlayed
- && Options["MultiPV"] == 1
+ if ( Options["MultiPV"] == 1
&& !Limits.depth
&& !Skill(Options["Skill Level"]).enabled()
&& rootMoves[0].pv[0] != MOVE_NONE)
Stack stack[MAX_PLY+7], *ss = stack+4; // To reference from (ss-4) to (ss+2)
Value bestValue, alpha, beta, delta;
- Move easyMove = MOVE_NONE;
+ Move lastBestMove = MOVE_NONE;
+ Depth lastBestMoveDepth = DEPTH_ZERO;
MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr);
+ double timeReduction = 1.0;
std::memset(ss-4, 0, 7 * sizeof(Stack));
for (int i = 4; i > 0; i--)
if (mainThread)
{
- easyMove = EasyMove.get(rootPos.key());
- EasyMove.clear();
- mainThread->easyMovePlayed = mainThread->failedLow = false;
+ mainThread->failedLow = false;
mainThread->bestMoveChanges = 0;
}
if (!Threads.stop)
completedDepth = rootDepth;
+ if (rootMoves[0].pv[0] != lastBestMove) {
+ lastBestMove = rootMoves[0].pv[0];
+ lastBestMoveDepth = rootDepth;
+ }
+
// Have we found a "mate in x"?
if ( Limits.mate
&& bestValue >= VALUE_MATE_IN_MAX_PLY
if (!Threads.stop && !Threads.stopOnPonderhit)
{
// Stop the search if only one legal move is available, or if all
- // of the available time has been used, or if we matched an easyMove
- // from the previous search and just did a fast verification.
+ // of the available time has been used
const int F[] = { mainThread->failedLow,
bestValue - mainThread->previousScore };
-
int improvingFactor = std::max(229, std::min(715, 357 + 119 * F[0] - 6 * F[1]));
- double unstablePvFactor = 1 + mainThread->bestMoveChanges;
- bool doEasyMove = rootMoves[0].pv[0] == easyMove
- && mainThread->bestMoveChanges < 0.03
- && Time.elapsed() > Time.optimum() * 5 / 44;
+ Color us = rootPos.side_to_move();
+ bool thinkHard = DrawValue[us] == bestValue
+ && Limits.time[us] - Time.elapsed() > Limits.time[~us]
+ && ::pv_is_draw(rootPos);
+
+ double unstablePvFactor = 1 + mainThread->bestMoveChanges + thinkHard;
+
+ // if the bestMove is stable over several iterations, reduce time for this move,
+ // the longer the move has been stable, the more.
+ // Use part of the gained time from a previous stable move for the current move.
+ timeReduction = 1;
+ for (int i : {3, 4, 5})
+ if (lastBestMoveDepth * i < completedDepth && !thinkHard)
+ timeReduction *= 1.3;
+ unstablePvFactor *= std::pow(mainThread->previousTimeReduction, 0.51) / timeReduction;
if ( rootMoves.size() == 1
- || Time.elapsed() > Time.optimum() * unstablePvFactor * improvingFactor / 628
- || (mainThread->easyMovePlayed = doEasyMove, doEasyMove))
+ || Time.elapsed() > Time.optimum() * unstablePvFactor * improvingFactor / 628)
{
// If we are allowed to ponder do not stop the search now but
// keep pondering until the GUI sends "ponderhit" or "stop".
Threads.stop = true;
}
}
-
- if (rootMoves[0].pv.size() >= 3)
- EasyMove.update(rootPos, rootMoves[0].pv);
- else
- EasyMove.clear();
}
}
if (!mainThread)
return;
- // Clear any candidate easy move that wasn't stable for the last search
- // iterations; the second condition prevents consecutive fast moves.
- if (EasyMove.stableCnt < 6 || mainThread->easyMovePlayed)
- EasyMove.clear();
+ mainThread->previousTimeReduction = timeReduction;
// If skill level is enabled, swap best PV line with the sub-optimal one
if (skill.enabled())
assert(!(PvNode && cutNode));
assert(depth / ONE_PLY * ONE_PLY == depth);
- Move pv[MAX_PLY+1], quietsSearched[64];
+ Move pv[MAX_PLY+1], capturesSearched[32], quietsSearched[64];
StateInfo st;
TTEntry* tte;
Key posKey;
bool ttHit, inCheck, givesCheck, singularExtensionNode, improving;
bool captureOrPromotion, doFullDepthSearch, moveCountPruning, skipQuiets, ttCapture, pvExact;
Piece movedPiece;
- int moveCount, quietCount;
+ int moveCount, captureCount, quietCount;
// Step 1. Initialize node
Thread* thisThread = pos.this_thread();
inCheck = pos.checkers();
- moveCount = quietCount = ss->moveCount = 0;
+ moveCount = captureCount = quietCount = ss->moveCount = 0;
ss->statScore = 0;
bestValue = -VALUE_INFINITE;
// Step 8. Null move search with verification search (is omitted in PV nodes)
if ( !PvNode
&& eval >= beta
- && (ss->staticEval >= beta - 35 * (depth / ONE_PLY - 6) || depth >= 13 * ONE_PLY)
+ && ss->staticEval >= beta - 36 * depth / ONE_PLY + 225
&& pos.non_pawn_material(pos.side_to_move()))
{
assert(is_ok((ss-1)->currentMove));
- MovePicker mp(pos, ttMove, rbeta - ss->staticEval);
+ MovePicker mp(pos, ttMove, rbeta - ss->staticEval, &thisThread->captureHistory);
while ((move = mp.next_move()) != MOVE_NONE)
if (pos.legal(move))
const PieceToHistory* contHist[] = { (ss-1)->contHistory, (ss-2)->contHistory, nullptr, (ss-4)->contHistory };
Move countermove = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq];
- MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory, contHist, countermove, ss->killers);
+ MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory, &thisThread->captureHistory, contHist, countermove, ss->killers);
value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
improving = ss->staticEval >= (ss-2)->staticEval
/* || ss->staticEval == VALUE_NONE Already implicit in the previous condition */
if (!captureOrPromotion && move != bestMove && quietCount < 64)
quietsSearched[quietCount++] = move;
+ else if (captureOrPromotion && move != bestMove && captureCount < 32)
+ capturesSearched[captureCount++] = move;
}
// The following condition would detect a stop only after move loop has been
// Quiet best move: update move sorting heuristics
if (!pos.capture_or_promotion(bestMove))
update_stats(pos, ss, bestMove, quietsSearched, quietCount, stat_bonus(depth));
+ else
+ update_capture_stats(pos, bestMove, capturesSearched, captureCount, stat_bonus(depth));
// Extra penalty for a quiet TT move in previous ply when it gets refuted
if ((ss-1)->moveCount == 1 && !pos.captured_piece())
// 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, &pos.this_thread()->mainHistory, to_sq((ss-1)->currentMove));
+ MovePicker mp(pos, ttMove, depth, &pos.this_thread()->mainHistory, &pos.this_thread()->captureHistory, to_sq((ss-1)->currentMove));
// Loop through the moves until no moves remain or a beta cutoff occurs
while ((move = mp.next_move()) != MOVE_NONE)
}
+ // update_capture_stats() updates move sorting heuristics when a new capture best move is found
+
+ void update_capture_stats(const Position& pos, Move move,
+ Move* captures, int captureCnt, int bonus) {
+
+ CapturePieceToHistory& captureHistory = pos.this_thread()->captureHistory;
+ Piece moved_piece = pos.moved_piece(move);
+ PieceType captured = type_of(pos.piece_on(to_sq(move)));
+ captureHistory.update(moved_piece,to_sq(move), captured, bonus);
+
+ // Decrease all the other played capture moves
+ for (int i = 0; i < captureCnt; ++i)
+ {
+ moved_piece = pos.moved_piece(captures[i]);
+ captured = type_of(pos.piece_on(to_sq(captures[i])));
+ captureHistory.update(moved_piece, to_sq(captures[i]), captured, -bonus);
+ }
+ }
+
+
// update_stats() updates move sorting heuristics when a new quiet best move is found
void update_stats(const Position& pos, Stack* ss, Move move,
}
+ // Is the PV leading to a draw position? Assumes all pv moves are legal
+ bool pv_is_draw(Position& pos) {
+
+ StateInfo st[MAX_PLY];
+ auto& pv = pos.this_thread()->rootMoves[0].pv;
+
+ for (size_t i = 0; i < pv.size(); ++i)
+ pos.do_move(pv[i], st[i]);
+
+ bool isDraw = pos.is_draw(pv.size());
+
+ for (size_t i = pv.size(); i > 0; --i)
+ pos.undo_move(pv[i-1]);
+
+ return isDraw;
+ }
+
+
// When playing with strength handicap, choose best move among a set of RootMoves
// using a statistical rule dependent on 'level'. Idea by Heinz van Saanen.
ProbeDepth = Options["SyzygyProbeDepth"] * ONE_PLY;
Cardinality = Options["SyzygyProbeLimit"];
- // Don't filter any moves if the user requested analysis on multiple
- if (Options["MultiPV"] != 1)
- return;
-
// Skip TB probing when no TB found: !TBLargest -> !TB::Cardinality
if (Cardinality > MaxCardinality)
{
if (Cardinality < popcount(pos.pieces()) || pos.can_castle(ANY_CASTLING))
return;
+ // Don't filter any moves if the user requested analysis on multiple
+ if (Options["MultiPV"] != 1)
+ return;
+
// If the current root position is in the tablebases, then RootMoves
// contains only moves that preserve the draw or the win.
RootInTB = root_probe(pos, rootMoves, TB::Score);
projects / stockfish / blobdiff