/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
- Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2004-2020 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
constexpr uint64_t TtHitAverageResolution = 1024;
// Razor and futility margins
- constexpr int RazorMargin = 527;
+ constexpr int RazorMargin = 510;
Value futility_margin(Depth d, bool improving) {
- return Value(227 * (d - improving));
+ return Value(223 * (d - improving));
}
// Reductions lookup table, initialized at startup
Depth reduction(bool i, Depth d, int mn) {
int r = Reductions[d] * Reductions[mn];
- return (r + 570) / 1024 + (!i && r > 1018);
+ return (r + 509) / 1024 + (!i && r > 894);
}
constexpr int futility_move_count(bool improving, Depth depth) {
// History and stats update bonus, based on depth
int stat_bonus(Depth d) {
- return d > 15 ? 27 : 17 * d * d + 133 * d - 134;
+ return d > 13 ? 29 : 17 * d * d + 134 * d - 134;
}
// Add a small random component to draw evaluations to avoid 3fold-blindness
void Search::init() {
for (int i = 1; i < MAX_MOVES; ++i)
- Reductions[i] = int((24.8 + std::log(Threads.size())) * std::log(i));
+ Reductions[i] = int((22.0 + std::log(Threads.size())) * std::log(i));
}
Time.init(Limits, us, rootPos.game_ply());
TT.new_search();
+ Eval::verify_NNUE();
+
if (rootMoves.empty())
{
rootMoves.emplace_back(MOVE_NONE);
Thread* bestThread = this;
- if (int(Options["MultiPV"]) == 1 &&
- !Limits.depth &&
- !(Skill(Options["Skill Level"]).enabled() || int(Options["UCI_LimitStrength"])) &&
- rootMoves[0].pv[0] != MOVE_NONE)
+ if ( int(Options["MultiPV"]) == 1
+ && !Limits.depth
+ && !(Skill(Options["Skill Level"]).enabled() || int(Options["UCI_LimitStrength"]))
+ && rootMoves[0].pv[0] != MOVE_NONE)
bestThread = Threads.get_best_thread();
bestPreviousScore = bestThread->rootMoves[0].score;
// for match (TC 60+0.6) results spanning a wide range of k values.
PRNG rng(now());
double floatLevel = Options["UCI_LimitStrength"] ?
- Utility::clamp(std::pow((Options["UCI_Elo"] - 1346.6) / 143.4, 1 / 0.806), 0.0, 20.0) :
+ std::clamp(std::pow((Options["UCI_Elo"] - 1346.6) / 143.4, 1 / 0.806), 0.0, 20.0) :
double(Options["Skill Level"]);
int intLevel = int(floatLevel) +
((floatLevel - int(floatLevel)) * 1024 > rng.rand<unsigned>() % 1024 ? 1 : 0);
if (rootDepth >= 4)
{
Value prev = rootMoves[pvIdx].previousScore;
- delta = Value(19);
+ delta = Value(17);
alpha = std::max(prev - delta,-VALUE_INFINITE);
beta = std::min(prev + delta, VALUE_INFINITE);
// Adjust contempt based on root move's previousScore (dynamic contempt)
- int dct = ct + (110 - ct / 2) * prev / (abs(prev) + 140);
+ int dct = ct + (105 - ct / 2) * prev / (abs(prev) + 149);
contempt = (us == WHITE ? make_score(dct, dct / 2)
: -make_score(dct, dct / 2));
&& !Threads.stop
&& !mainThread->stopOnPonderhit)
{
- double fallingEval = (296 + 6 * (mainThread->bestPreviousScore - bestValue)
- + 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 725.0;
- fallingEval = Utility::clamp(fallingEval, 0.5, 1.5);
+ double fallingEval = (318 + 6 * (mainThread->bestPreviousScore - bestValue)
+ + 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 825.0;
+ fallingEval = std::clamp(fallingEval, 0.5, 1.5);
// If the bestMove is stable over several iterations, reduce time accordingly
- timeReduction = lastBestMoveDepth + 10 < completedDepth ? 1.92 : 0.95;
- double reduction = (1.47 + mainThread->previousTimeReduction) / (2.22 * timeReduction);
+ timeReduction = lastBestMoveDepth + 9 < completedDepth ? 1.92 : 0.95;
+ double reduction = (1.47 + mainThread->previousTimeReduction) / (2.32 * timeReduction);
// Use part of the gained time from a previous stable move for the current move
for (Thread* th : Threads)
totBestMoveChanges += th->bestMoveChanges;
th->bestMoveChanges = 0;
}
- double bestMoveInstability = 1 + totBestMoveChanges / Threads.size();
+ double bestMoveInstability = 1 + 2 * totBestMoveChanges / Threads.size();
double totalTime = rootMoves.size() == 1 ? 0 :
Time.optimum() * fallingEval * reduction * bestMoveInstability;
}
else if ( Threads.increaseDepth
&& !mainThread->ponder
- && Time.elapsed() > totalTime * 0.56)
+ && Time.elapsed() > totalTime * 0.58)
Threads.increaseDepth = false;
else
Threads.increaseDepth = true;
Key posKey;
Move ttMove, move, excludedMove, bestMove;
Depth extension, newDepth;
- Value bestValue, value, ttValue, eval, maxValue;
- bool ttHit, ttPv, formerPv, givesCheck, improving, didLMR, priorCapture;
+ Value bestValue, value, ttValue, eval, maxValue, probCutBeta;
+ bool formerPv, givesCheck, improving, didLMR, priorCapture;
bool captureOrPromotion, doFullDepthSearch, moveCountPruning,
ttCapture, singularQuietLMR;
Piece movedPiece;
assert(0 <= ss->ply && ss->ply < MAX_PLY);
(ss+1)->ply = ss->ply + 1;
+ (ss+1)->ttPv = false;
(ss+1)->excludedMove = bestMove = MOVE_NONE;
(ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
Square prevSq = to_sq((ss-1)->currentMove);
// starts with statScore = 0. Later grandchildren start with the last calculated
// statScore of the previous grandchild. This influences the reduction rules in
// LMR which are based on the statScore of parent position.
- if (rootNode)
- (ss+4)->statScore = 0;
- else
+ if (!rootNode)
(ss+2)->statScore = 0;
// Step 4. Transposition table lookup. 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 = pos.key() ^ (Key(excludedMove) << 48); // Isn't a very good hash
- tte = TT.probe(posKey, ttHit);
- ttValue = ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE;
+ posKey = excludedMove == MOVE_NONE ? pos.key() : pos.key() ^ make_key(excludedMove);
+ tte = TT.probe(posKey, ss->ttHit);
+ ttValue = ss->ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE;
ttMove = rootNode ? thisThread->rootMoves[thisThread->pvIdx].pv[0]
- : ttHit ? tte->move() : MOVE_NONE;
- ttPv = PvNode || (ttHit && tte->is_pv());
- formerPv = ttPv && !PvNode;
-
- if (ttPv && depth > 12 && ss->ply - 1 < MAX_LPH && !priorCapture && is_ok((ss-1)->currentMove))
+ : ss->ttHit ? tte->move() : MOVE_NONE;
+ if (!excludedMove)
+ ss->ttPv = PvNode || (ss->ttHit && tte->is_pv());
+ formerPv = ss->ttPv && !PvNode;
+
+ if ( ss->ttPv
+ && depth > 12
+ && ss->ply - 1 < MAX_LPH
+ && !priorCapture
+ && is_ok((ss-1)->currentMove))
thisThread->lowPlyHistory[ss->ply - 1][from_to((ss-1)->currentMove)] << stat_bonus(depth - 5);
// thisThread->ttHitAverage can be used to approximate the running average of ttHit
thisThread->ttHitAverage = (TtHitAverageWindow - 1) * thisThread->ttHitAverage / TtHitAverageWindow
- + TtHitAverageResolution * ttHit;
+ + TtHitAverageResolution * ss->ttHit;
// At non-PV nodes we check for an early TT cutoff
if ( !PvNode
- && ttHit
+ && ss->ttHit
&& tte->depth() >= depth
&& ttValue != VALUE_NONE // Possible in case of TT access race
&& (ttValue >= beta ? (tte->bound() & BOUND_LOWER)
if ( b == BOUND_EXACT
|| (b == BOUND_LOWER ? value >= beta : value <= alpha))
{
- tte->save(posKey, value_to_tt(value, ss->ply), ttPv, b,
+ tte->save(posKey, value_to_tt(value, ss->ply), ss->ttPv, b,
std::min(MAX_PLY - 1, depth + 6),
MOVE_NONE, VALUE_NONE);
improving = false;
goto moves_loop;
}
- else if (ttHit)
+ else if (ss->ttHit)
{
// Never assume anything about values stored in TT
ss->staticEval = eval = tte->eval();
else
{
if ((ss-1)->currentMove != MOVE_NULL)
- {
- int bonus = -(ss-1)->statScore / 512;
-
- ss->staticEval = eval = evaluate(pos) + bonus;
- }
+ ss->staticEval = eval = evaluate(pos);
else
ss->staticEval = eval = -(ss-1)->staticEval + 2 * Tempo;
- tte->save(posKey, VALUE_NONE, ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval);
+ tte->save(posKey, VALUE_NONE, ss->ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval);
}
// Step 7. Razoring (~1 Elo)
&& eval <= alpha - RazorMargin)
return qsearch<NT>(pos, ss, alpha, beta);
- improving = (ss-2)->staticEval == VALUE_NONE ? (ss->staticEval > (ss-4)->staticEval
- || (ss-4)->staticEval == VALUE_NONE) : ss->staticEval > (ss-2)->staticEval;
+ improving = (ss-2)->staticEval == VALUE_NONE
+ ? ss->staticEval > (ss-4)->staticEval || (ss-4)->staticEval == VALUE_NONE
+ : ss->staticEval > (ss-2)->staticEval;
// Step 8. Futility pruning: child node (~50 Elo)
if ( !PvNode
- && depth < 6
+ && depth < 8
&& eval - futility_margin(depth, improving) >= beta
&& eval < VALUE_KNOWN_WIN) // Do not return unproven wins
return eval;
// Step 9. Null move search with verification search (~40 Elo)
if ( !PvNode
&& (ss-1)->currentMove != MOVE_NULL
- && (ss-1)->statScore < 23824
+ && (ss-1)->statScore < 22977
&& eval >= beta
&& eval >= ss->staticEval
- && ss->staticEval >= beta - 33 * depth - 33 * improving + 112 * ttPv + 311
+ && ss->staticEval >= beta - 30 * depth - 28 * improving + 84 * ss->ttPv + 182
&& !excludedMove
&& pos.non_pawn_material(us)
&& (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
assert(eval - beta >= 0);
// Null move dynamic reduction based on depth and value
- Depth R = (737 + 77 * depth) / 246 + std::min(int(eval - beta) / 192, 3);
+ Depth R = (817 + 71 * depth) / 213 + std::min(int(eval - beta) / 192, 3);
ss->currentMove = MOVE_NULL;
ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0];
}
}
+ probCutBeta = beta + 176 - 49 * improving;
+
// Step 10. ProbCut (~10 Elo)
// If we have a good enough capture and a reduced search returns a value
// much above beta, we can (almost) safely prune the previous move.
if ( !PvNode
&& depth > 4
- && abs(beta) < VALUE_TB_WIN_IN_MAX_PLY)
+ && abs(beta) < VALUE_TB_WIN_IN_MAX_PLY
+ // if value from transposition table is lower than probCutBeta, don't attempt probCut
+ // there and in further interactions with transposition table cutoff depth is set to depth - 3
+ // because probCut search has depth set to depth - 4 but we also do a move before it
+ // so effective depth is equal to depth - 3
+ && !( ss->ttHit
+ && tte->depth() >= depth - 3
+ && ttValue != VALUE_NONE
+ && ttValue < probCutBeta))
{
- Value raisedBeta = beta + 176 - 49 * improving;
- assert(raisedBeta < VALUE_INFINITE);
- MovePicker mp(pos, ttMove, raisedBeta - ss->staticEval, &captureHistory);
+ // if ttMove is a capture and value from transposition table is good enough produce probCut
+ // cutoff without digging into actual probCut search
+ if ( ss->ttHit
+ && tte->depth() >= depth - 3
+ && ttValue != VALUE_NONE
+ && ttValue >= probCutBeta
+ && ttMove
+ && pos.capture_or_promotion(ttMove))
+ return probCutBeta;
+
+ assert(probCutBeta < VALUE_INFINITE);
+ MovePicker mp(pos, ttMove, probCutBeta - ss->staticEval, &captureHistory);
int probCutCount = 0;
+ bool ttPv = ss->ttPv;
+ ss->ttPv = false;
while ( (move = mp.next_move()) != MOVE_NONE
- && probCutCount < 2 + 2 * cutNode
- && !( move == ttMove
- && tte->depth() >= depth - 4
- && ttValue < raisedBeta))
+ && probCutCount < 2 + 2 * cutNode)
if (move != excludedMove && pos.legal(move))
{
assert(pos.capture_or_promotion(move));
pos.do_move(move, st);
// Perform a preliminary qsearch to verify that the move holds
- value = -qsearch<NonPV>(pos, ss+1, -raisedBeta, -raisedBeta+1);
+ value = -qsearch<NonPV>(pos, ss+1, -probCutBeta, -probCutBeta+1);
// If the qsearch held, perform the regular search
- if (value >= raisedBeta)
- value = -search<NonPV>(pos, ss+1, -raisedBeta, -raisedBeta+1, depth - 4, !cutNode);
+ if (value >= probCutBeta)
+ value = -search<NonPV>(pos, ss+1, -probCutBeta, -probCutBeta+1, depth - 4, !cutNode);
pos.undo_move(move);
- if (value >= raisedBeta)
+ if (value >= probCutBeta)
+ {
+ // if transposition table doesn't have equal or more deep info write probCut data into it
+ if ( !(ss->ttHit
+ && tte->depth() >= depth - 3
+ && ttValue != VALUE_NONE))
+ tte->save(posKey, value_to_tt(value, ss->ply), ttPv,
+ BOUND_LOWER,
+ depth - 3, move, ss->staticEval);
return value;
+ }
}
+ ss->ttPv = ttPv;
}
- // Step 11. Internal iterative deepening (~1 Elo)
- if (depth >= 7 && !ttMove)
- {
- search<NT>(pos, ss, alpha, beta, depth - 7, cutNode);
-
- tte = TT.probe(posKey, ttHit);
- ttValue = ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE;
- ttMove = ttHit ? tte->move() : MOVE_NONE;
- }
+ // Step 11. If the position is not in TT, decrease depth by 2
+ if ( PvNode
+ && depth >= 6
+ && !ttMove)
+ depth -= 2;
moves_loop: // When in check, search starts from here
thisThread->rootMoves.begin() + thisThread->pvLast, move))
continue;
+ // Check for legality
+ if (!rootNode && !pos.legal(move))
+ continue;
+
ss->moveCount = ++moveCount;
if (rootNode && thisThread == Threads.main() && Time.elapsed() > 3000)
continue;
// Futility pruning: parent node (~5 Elo)
- if ( lmrDepth < 6
+ if ( lmrDepth < 7
&& !ss->inCheck
- && ss->staticEval + 284 + 188 * lmrDepth <= alpha
+ && ss->staticEval + 283 + 170 * lmrDepth <= alpha
&& (*contHist[0])[movedPiece][to_sq(move)]
+ (*contHist[1])[movedPiece][to_sq(move)]
+ (*contHist[3])[movedPiece][to_sq(move)]
- + (*contHist[5])[movedPiece][to_sq(move)] / 2 < 28388)
+ + (*contHist[5])[movedPiece][to_sq(move)] / 2 < 27376)
continue;
// Prune moves with negative SEE (~20 Elo)
- if (!pos.see_ge(move, Value(-(29 - std::min(lmrDepth, 17)) * lmrDepth * lmrDepth)))
+ if (!pos.see_ge(move, Value(-(29 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth)))
continue;
}
else
&& !(PvNode && abs(bestValue) < 2)
&& PieceValue[MG][type_of(movedPiece)] >= PieceValue[MG][type_of(pos.piece_on(to_sq(move)))]
&& !ss->inCheck
- && ss->staticEval + 267 + 391 * lmrDepth
+ && ss->staticEval + 169 + 244 * lmrDepth
+ PieceValue[MG][type_of(pos.piece_on(to_sq(move)))] <= alpha)
continue;
// See based pruning
- if (!pos.see_ge(move, Value(-202) * depth)) // (~25 Elo)
+ if (!pos.see_ge(move, Value(-221) * depth)) // (~25 Elo)
continue;
}
}
// search of (alpha-s, beta-s), and just one fails high on (alpha, beta),
// then that move is singular and should be extended. To verify this we do
// a reduced search on all the other moves but the ttMove and if the
- // result is lower than ttValue minus a margin then we will extend the ttMove.
- if ( depth >= 6
+ // result is lower than ttValue minus a margin, then we will extend the ttMove.
+ if ( depth >= 7
&& move == ttMove
&& !rootNode
&& !excludedMove // Avoid recursive singular search
/* && ttValue != VALUE_NONE Already implicit in the next condition */
&& abs(ttValue) < VALUE_KNOWN_WIN
&& (tte->bound() & BOUND_LOWER)
- && tte->depth() >= depth - 3
- && pos.legal(move))
+ && tte->depth() >= depth - 3)
{
Value singularBeta = ttValue - ((formerPv + 4) * depth) / 2;
Depth singularDepth = (depth - 1 + 3 * formerPv) / 2;
&& (pos.is_discovery_check_on_king(~us, move) || pos.see_ge(move)))
extension = 1;
- // Passed pawn extension
- else if ( move == ss->killers[0]
- && pos.advanced_pawn_push(move)
- && pos.pawn_passed(us, to_sq(move)))
- extension = 1;
-
// Last captures extension
else if ( PieceValue[EG][pos.captured_piece()] > PawnValueEg
&& pos.non_pawn_material() <= 2 * RookValueMg)
extension = 1;
// Castling extension
- if (type_of(move) == CASTLING)
+ if ( type_of(move) == CASTLING
+ && popcount(pos.pieces(us) & ~pos.pieces(PAWN) & (to_sq(move) & KingSide ? KingSide : QueenSide)) <= 2)
extension = 1;
// Late irreversible move extension
// Speculative prefetch as early as possible
prefetch(TT.first_entry(pos.key_after(move)));
- // Check for legality just before making the move
- if (!rootNode && !pos.legal(move))
- {
- ss->moveCount = --moveCount;
- continue;
- }
-
// Update the current move (this must be done after singular extension search)
ss->currentMove = move;
ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck]
// Step 16. Reduced depth search (LMR, ~200 Elo). If the move fails high it will be
// re-searched at full depth.
if ( depth >= 3
- && moveCount > 1 + 2 * rootNode
- && (!rootNode || thisThread->best_move_count(move) == 0)
+ && moveCount > 1 + 2 * rootNode + 2 * (PvNode && abs(bestValue) < 2)
&& ( !captureOrPromotion
|| moveCountPruning
|| ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha
|| cutNode
- || thisThread->ttHitAverage < 415 * TtHitAverageResolution * TtHitAverageWindow / 1024))
+ || thisThread->ttHitAverage < 427 * TtHitAverageResolution * TtHitAverageWindow / 1024))
{
Depth r = reduction(improving, depth, moveCount);
// Decrease reduction if the ttHit running average is large
- if (thisThread->ttHitAverage > 473 * TtHitAverageResolution * TtHitAverageWindow / 1024)
+ if (thisThread->ttHitAverage > 509 * TtHitAverageResolution * TtHitAverageWindow / 1024)
r--;
// Reduction if other threads are searching this position
r++;
// Decrease reduction if position is or has been on the PV (~10 Elo)
- if (ttPv)
+ if (ss->ttPv)
r -= 2;
if (moveCountPruning && !formerPv)
// Decrease reduction if ttMove has been singularly extended (~3 Elo)
if (singularQuietLMR)
- r -= 1 + formerPv;
+ r--;
if (!captureOrPromotion)
{
// hence break make_move(). (~2 Elo)
else if ( type_of(move) == NORMAL
&& !pos.see_ge(reverse_move(move)))
- r -= 2 + ttPv - (type_of(movedPiece) == PAWN);
+ r -= 2 + ss->ttPv - (type_of(movedPiece) == PAWN);
ss->statScore = thisThread->mainHistory[us][from_to(move)]
+ (*contHist[0])[movedPiece][to_sq(move)]
+ (*contHist[1])[movedPiece][to_sq(move)]
+ (*contHist[3])[movedPiece][to_sq(move)]
- - 4826;
+ - 5287;
// Decrease/increase reduction by comparing opponent's stat score (~10 Elo)
- if (ss->statScore >= -100 && (ss-1)->statScore < -112)
+ if (ss->statScore >= -106 && (ss-1)->statScore < -104)
r--;
- else if ((ss-1)->statScore >= -125 && ss->statScore < -138)
+ else if ((ss-1)->statScore >= -119 && ss->statScore < -140)
r++;
// Decrease/increase reduction for moves with a good/bad history (~30 Elo)
- r -= ss->statScore / 14615;
+ r -= ss->statScore / 14884;
}
else
{
// Unless giving check, this capture is likely bad
if ( !givesCheck
- && ss->staticEval + PieceValue[EG][pos.captured_piece()] + 211 * depth <= alpha)
+ && ss->staticEval + PieceValue[EG][pos.captured_piece()] + 213 * depth <= alpha)
r++;
}
- Depth d = Utility::clamp(newDepth - r, 1, newDepth);
+ Depth d = std::clamp(newDepth - r, 1, newDepth);
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
if (PvNode)
bestValue = std::min(bestValue, maxValue);
+ // If no good move is found and the previous position was ttPv, then the previous
+ // opponent move is probably good and the new position is added to the search tree.
+ if (bestValue <= alpha)
+ ss->ttPv = ss->ttPv || ((ss-1)->ttPv && depth > 3);
+ // Otherwise, a counter move has been found and if the position is the last leaf
+ // in the search tree, remove the position from the search tree.
+ else if (depth > 3)
+ ss->ttPv = ss->ttPv && (ss+1)->ttPv;
+
if (!excludedMove && !(rootNode && thisThread->pvIdx))
- tte->save(posKey, value_to_tt(bestValue, ss->ply), ttPv,
+ tte->save(posKey, value_to_tt(bestValue, ss->ply), ss->ttPv,
bestValue >= beta ? BOUND_LOWER :
PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
depth, bestMove, ss->staticEval);
Move ttMove, move, bestMove;
Depth ttDepth;
Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha;
- bool ttHit, pvHit, givesCheck, captureOrPromotion;
+ bool pvHit, givesCheck, captureOrPromotion;
int moveCount;
if (PvNode)
: DEPTH_QS_NO_CHECKS;
// Transposition table lookup
posKey = pos.key();
- tte = TT.probe(posKey, ttHit);
- ttValue = ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE;
- ttMove = ttHit ? tte->move() : MOVE_NONE;
- pvHit = ttHit && tte->is_pv();
+ tte = TT.probe(posKey, ss->ttHit);
+ ttValue = ss->ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE;
+ ttMove = ss->ttHit ? tte->move() : MOVE_NONE;
+ pvHit = ss->ttHit && tte->is_pv();
if ( !PvNode
- && ttHit
+ && ss->ttHit
&& tte->depth() >= ttDepth
&& ttValue != VALUE_NONE // Only in case of TT access race
&& (ttValue >= beta ? (tte->bound() & BOUND_LOWER)
}
else
{
- if (ttHit)
+ if (ss->ttHit)
{
// Never assume anything about values stored in TT
if ((ss->staticEval = bestValue = tte->eval()) == VALUE_NONE)
// Stand pat. Return immediately if static value is at least beta
if (bestValue >= beta)
{
- if (!ttHit)
+ if (!ss->ttHit)
tte->save(posKey, value_to_tt(bestValue, ss->ply), false, BOUND_LOWER,
DEPTH_NONE, MOVE_NONE, ss->staticEval);
if (PvNode && bestValue > alpha)
alpha = bestValue;
- futilityBase = bestValue + 141;
+ futilityBase = bestValue + 145;
}
const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory,
// Initialize a MovePicker object for the current position, and prepare
// to search the moves. Because the depth is <= 0 here, only captures,
- // queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will
- // be generated.
+ // queen and checking knight promotions, and other checks(only if depth >= DEPTH_QS_CHECKS)
+ // will be generated.
MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory,
&thisThread->captureHistory,
contHist,
{
assert(type_of(move) != ENPASSANT); // Due to !pos.advanced_pawn_push
+ // moveCount pruning
+ if (moveCount > 2)
+ continue;
+
futilityValue = futilityBase + PieceValue[EG][pos.piece_on(to_sq(move))];
if (futilityValue <= alpha)
}
// Do not search moves with negative SEE values
- if ( !ss->inCheck && !pos.see_ge(move))
+ if ( !ss->inCheck
+ && !(givesCheck && pos.is_discovery_check_on_king(~pos.side_to_move(), move))
+ && !pos.see_ge(move))
continue;
// Speculative prefetch as early as possible
[pos.moved_piece(move)]
[to_sq(move)];
+ if ( !captureOrPromotion
+ && moveCount
+ && (*contHist[0])[pos.moved_piece(move)][to_sq(move)] < CounterMovePruneThreshold
+ && (*contHist[1])[pos.moved_piece(move)][to_sq(move)] < CounterMovePruneThreshold)
+ continue;
+
// Make and search the move
pos.do_move(move, st, givesCheck);
value = -qsearch<NT>(pos, ss+1, -beta, -alpha, depth - 1);
else
captureHistory[moved_piece][to_sq(bestMove)][captured] << bonus1;
- // Extra penalty for a quiet TT or main killer move in previous ply when it gets refuted
- if ( ((ss-1)->moveCount == 1 || ((ss-1)->currentMove == (ss-1)->killers[0]))
+ // Extra penalty for a quiet early move that was not a TT move or main killer move in previous ply when it gets refuted
+ if ( ((ss-1)->moveCount == 1 + (ss-1)->ttHit || ((ss-1)->currentMove == (ss-1)->killers[0]))
&& !pos.captured_piece())
update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -bonus1);
}
if (depth > 11 && ss->ply < MAX_LPH)
- thisThread->lowPlyHistory[ss->ply][from_to(move)] << stat_bonus(depth - 6);
+ thisThread->lowPlyHistory[ss->ply][from_to(move)] << stat_bonus(depth - 7);
}
// When playing with strength handicap, choose best move among a set of RootMoves
{
bool updated = rootMoves[i].score != -VALUE_INFINITE;
- if (depth == 1 && !updated)
+ if (depth == 1 && !updated && i > 0)
continue;
- Depth d = updated ? depth : depth - 1;
+ Depth d = updated ? depth : std::max(1, depth - 1);
Value v = updated ? rootMoves[i].score : rootMoves[i].previousScore;
+ if (v == -VALUE_INFINITE)
+ v = VALUE_ZERO;
+
bool tb = TB::RootInTB && abs(v) < VALUE_MATE_IN_MAX_PLY;
v = tb ? rootMoves[i].tbScore : v;
<< " multipv " << i + 1
<< " score " << UCI::value(v);
+ if (Options["UCI_ShowWDL"])
+ ss << UCI::wdl(v, pos.game_ply());
+
if (!tb && i == pvIdx)
ss << (v >= beta ? " lowerbound" : v <= alpha ? " upperbound" : "");
if (RootInTB)
{
// Sort moves according to TB rank
- std::sort(rootMoves.begin(), rootMoves.end(),
+ std::stable_sort(rootMoves.begin(), rootMoves.end(),
[](const RootMove &a, const RootMove &b) { return a.tbRank > b.tbRank; } );
// Probe during search only if DTZ is not available and we are winning
projects / stockfish / blobdiff