// Different node types, used as a template parameter
enum NodeType { NonPV, PV };
- constexpr uint64_t ttHitAverageWindow = 4096;
- constexpr uint64_t ttHitAverageResolution = 1024;
+ constexpr uint64_t TtHitAverageWindow = 4096;
+ constexpr uint64_t TtHitAverageResolution = 1024;
// Razor and futility margins
- constexpr int RazorMargin = 531;
+ constexpr int RazorMargin = 527;
Value futility_margin(Depth d, bool improving) {
- return Value(217 * (d - improving));
+ return Value(227 * (d - improving));
}
// Reductions lookup table, initialized at startup
Depth reduction(bool i, Depth d, int mn) {
int r = Reductions[d] * Reductions[mn];
- return (r + 511) / 1024 + (!i && r > 1007);
+ return (r + 570) / 1024 + (!i && r > 1018);
}
constexpr int futility_move_count(bool improving, Depth depth) {
- return (4 + depth * depth) / (2 - improving);
+ return (3 + depth * depth) / (2 - improving);
}
// History and stats update bonus, based on depth
int stat_bonus(Depth d) {
- return d > 15 ? -8 : 19 * d * d + 155 * d - 132;
+ return d > 15 ? 27 : 17 * d * d + 133 * 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()) / 2) * std::log(i));
+ Reductions[i] = int((24.8 + std::log(Threads.size())) * std::log(i));
}
}
else
{
- for (Thread* th : Threads)
- {
- th->bestMoveChanges = 0;
- if (th != this)
- th->start_searching();
- }
-
- Thread::search(); // Let's start searching!
+ Threads.start_searching(); // start non-main threads
+ Thread::search(); // main thread start searching
}
// When we reach the maximum depth, we can arrive here without a raise of
Threads.stop = true;
// Wait until all threads have finished
- for (Thread* th : Threads)
- if (th != this)
- th->wait_for_search_finished();
+ Threads.wait_for_search_finished();
// When playing in 'nodes as time' mode, subtract the searched nodes from
// the available ones before exiting.
Thread* bestThread = this;
- // Check if there are threads with a better score than main thread
- if ( Options["MultiPV"] == 1
+ if ( int(Options["MultiPV"]) == 1
&& !Limits.depth
- && !(Skill(Options["Skill Level"]).enabled() || Options["UCI_LimitStrength"])
- && rootMoves[0].pv[0] != MOVE_NONE)
- {
- std::map<Move, int64_t> votes;
- Value minScore = this->rootMoves[0].score;
+ && !(Skill(Options["Skill Level"]).enabled() || int(Options["UCI_LimitStrength"]))
+ && rootMoves[0].pv[0] != MOVE_NONE)
+ bestThread = Threads.get_best_thread();
- // Find out minimum score
- for (Thread* th: Threads)
- minScore = std::min(minScore, th->rootMoves[0].score);
-
- // Vote according to score and depth, and select the best thread
- for (Thread* th : Threads)
- {
- votes[th->rootMoves[0].pv[0]] +=
- (th->rootMoves[0].score - minScore + 14) * int(th->completedDepth);
-
- if (bestThread->rootMoves[0].score >= VALUE_TB_WIN_IN_MAX_PLY)
- {
- // Make sure we pick the shortest mate
- if (th->rootMoves[0].score > bestThread->rootMoves[0].score)
- bestThread = th;
- }
- else if ( th->rootMoves[0].score >= VALUE_TB_WIN_IN_MAX_PLY
- || votes[th->rootMoves[0].pv[0]] > votes[bestThread->rootMoves[0].pv[0]])
- bestThread = th;
- }
- }
-
- previousScore = bestThread->rootMoves[0].score;
+ bestPreviousScore = bestThread->rootMoves[0].score;
// Send again PV info if we have a new best thread
if (bestThread != this)
if (mainThread)
{
- if (mainThread->previousScore == VALUE_INFINITE)
- for (int i=0; i<4; ++i)
+ if (mainThread->bestPreviousScore == VALUE_INFINITE)
+ for (int i = 0; i < 4; ++i)
mainThread->iterValue[i] = VALUE_ZERO;
else
- for (int i=0; i<4; ++i)
- mainThread->iterValue[i] = mainThread->previousScore;
+ for (int i = 0; i < 4; ++i)
+ mainThread->iterValue[i] = mainThread->bestPreviousScore;
}
- size_t multiPV = Options["MultiPV"];
+ std::copy(&lowPlyHistory[2][0], &lowPlyHistory.back().back() + 1, &lowPlyHistory[0][0]);
+ std::fill(&lowPlyHistory[MAX_LPH - 2][0], &lowPlyHistory.back().back() + 1, 0);
+
+ size_t multiPV = size_t(Options["MultiPV"]);
// Pick integer skill levels, but non-deterministically round up or down
// such that the average integer skill corresponds to the input floating point one.
// for match (TC 60+0.6) results spanning a wide range of k values.
PRNG rng(now());
double floatLevel = Options["UCI_LimitStrength"] ?
- clamp(std::pow((Options["UCI_Elo"] - 1346.6) / 143.4, 1 / 0.806), 0.0, 20.0) :
+ Utility::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);
multiPV = std::max(multiPV, (size_t)4);
multiPV = std::min(multiPV, rootMoves.size());
- ttHitAverage = ttHitAverageWindow * ttHitAverageResolution / 2;
+ ttHitAverage = TtHitAverageWindow * TtHitAverageResolution / 2;
int ct = int(Options["Contempt"]) * PawnValueEg / 100; // From centipawns
// Reset aspiration window starting size
if (rootDepth >= 4)
{
- Value previousScore = rootMoves[pvIdx].previousScore;
- delta = Value(21 + abs(previousScore) / 256);
- alpha = std::max(previousScore - delta,-VALUE_INFINITE);
- beta = std::min(previousScore + delta, VALUE_INFINITE);
+ Value prev = rootMoves[pvIdx].previousScore;
+ delta = Value(19);
+ 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 + (102 - ct / 2) * previousScore / (abs(previousScore) + 157);
+ int dct = ct + (110 - ct / 2) * prev / (abs(prev) + 140);
contempt = (us == WHITE ? make_score(dct, dct / 2)
: -make_score(dct, dct / 2));
&& !Threads.stop
&& !mainThread->stopOnPonderhit)
{
- double fallingEval = (332 + 6 * (mainThread->previousScore - bestValue)
- + 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 704.0;
- fallingEval = clamp(fallingEval, 0.5, 1.5);
+ double fallingEval = (296 + 6 * (mainThread->bestPreviousScore - bestValue)
+ + 6 * (mainThread->iterValue[iterIdx] - bestValue)) / 725.0;
+ fallingEval = Utility::clamp(fallingEval, 0.5, 1.5);
// If the bestMove is stable over several iterations, reduce time accordingly
- timeReduction = lastBestMoveDepth + 9 < completedDepth ? 1.94 : 0.91;
- double reduction = (1.41 + mainThread->previousTimeReduction) / (2.27 * timeReduction);
+ timeReduction = lastBestMoveDepth + 10 < completedDepth ? 1.92 : 0.95;
+ double reduction = (1.47 + mainThread->previousTimeReduction) / (2.22 * timeReduction);
// Use part of the gained time from a previous stable move for the current move
for (Thread* th : Threads)
}
double bestMoveInstability = 1 + totBestMoveChanges / Threads.size();
- // Stop the search if we have only one legal move, or if available time elapsed
- if ( rootMoves.size() == 1
- || Time.elapsed() > Time.optimum() * fallingEval * reduction * bestMoveInstability)
+ double totalTime = rootMoves.size() == 1 ? 0 :
+ Time.optimum() * fallingEval * reduction * bestMoveInstability;
+
+ // Stop the search if we have exceeded the totalTime, at least 1ms search
+ if (Time.elapsed() > totalTime)
{
// If we are allowed to ponder do not stop the search now but
// keep pondering until the GUI sends "ponderhit" or "stop".
}
else if ( Threads.increaseDepth
&& !mainThread->ponder
- && Time.elapsed() > Time.optimum() * fallingEval * reduction * bestMoveInstability * 0.6)
+ && Time.elapsed() > totalTime * 0.56)
Threads.increaseDepth = false;
else
Threads.increaseDepth = true;
Move ttMove, move, excludedMove, bestMove;
Depth extension, newDepth;
Value bestValue, value, ttValue, eval, maxValue;
- bool ttHit, ttPv, inCheck, givesCheck, improving, didLMR, priorCapture;
- bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture, singularLMR;
+ bool ttHit, ttPv, formerPv, givesCheck, improving, didLMR, priorCapture;
+ bool captureOrPromotion, doFullDepthSearch, moveCountPruning,
+ ttCapture, singularQuietLMR;
Piece movedPiece;
int moveCount, captureCount, quietCount;
// Step 1. Initialize node
Thread* thisThread = pos.this_thread();
- inCheck = pos.checkers();
+ ss->inCheck = pos.checkers();
priorCapture = pos.captured_piece();
Color us = pos.side_to_move();
moveCount = captureCount = quietCount = ss->moveCount = 0;
if ( Threads.stop.load(std::memory_order_relaxed)
|| pos.is_draw(ss->ply)
|| ss->ply >= MAX_PLY)
- return (ss->ply >= MAX_PLY && !inCheck) ? evaluate(pos)
- : value_draw(pos.this_thread());
+ return (ss->ply >= MAX_PLY && !ss->inCheck) ? evaluate(pos)
+ : value_draw(pos.this_thread());
// 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
// 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 << 16); // Isn't a very good hash
+ posKey = excludedMove == MOVE_NONE ? pos.key() : pos.key() ^ make_key(excludedMove);
tte = TT.probe(posKey, ttHit);
ttValue = 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 && !pos.captured_piece() && is_ok((ss-1)->currentMove))
+ if ( 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;
+ thisThread->ttHitAverage = (TtHitAverageWindow - 1) * thisThread->ttHitAverage / TtHitAverageWindow
+ + TtHitAverageResolution * ttHit;
// At non-PV nodes we check for an early TT cutoff
if ( !PvNode
}
}
+ CapturePieceToHistory& captureHistory = thisThread->captureHistory;
+
// Step 6. Static evaluation of the position
- if (inCheck)
+ if (ss->inCheck)
{
+ // Skip early pruning when in check
ss->staticEval = eval = VALUE_NONE;
improving = false;
- goto moves_loop; // Skip early pruning when in check
+ goto moves_loop;
}
else if (ttHit)
{
ss->staticEval = eval = evaluate(pos) + bonus;
}
else
- ss->staticEval = eval = -(ss-1)->staticEval + 2 * Eval::Tempo;
+ ss->staticEval = eval = -(ss-1)->staticEval + 2 * Tempo;
tte->save(posKey, VALUE_NONE, ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval);
}
// Step 7. Razoring (~1 Elo)
if ( !rootNode // The required rootNode PV handling is not available in qsearch
- && depth < 2
+ && depth == 1
&& eval <= alpha - RazorMargin)
return qsearch<NT>(pos, ss, alpha, beta);
// Step 9. Null move search with verification search (~40 Elo)
if ( !PvNode
&& (ss-1)->currentMove != MOVE_NULL
- && (ss-1)->statScore < 23397
+ && (ss-1)->statScore < 23824
&& eval >= beta
&& eval >= ss->staticEval
- && ss->staticEval >= beta - 32 * depth - 30 * improving + 120 * ttPv + 292
+ && ss->staticEval >= beta - 33 * depth - 33 * improving + 112 * ttPv + 311
&& !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 = (854 + 68 * depth) / 258 + std::min(int(eval - beta) / 192, 3);
+ Depth R = (737 + 77 * depth) / 246 + std::min(int(eval - beta) / 192, 3);
ss->currentMove = MOVE_NULL;
ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0];
if (nullValue >= beta)
{
- // Do not return unproven mate scores
+ // Do not return unproven mate or TB scores
if (nullValue >= VALUE_TB_WIN_IN_MAX_PLY)
nullValue = beta;
// 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 >= 5
+ && depth > 4
&& abs(beta) < VALUE_TB_WIN_IN_MAX_PLY)
{
- Value raisedBeta = std::min(beta + 189 - 45 * improving, VALUE_INFINITE);
- MovePicker mp(pos, ttMove, raisedBeta - ss->staticEval, &thisThread->captureHistory);
+ Value raisedBeta = beta + 176 - 49 * improving;
+ assert(raisedBeta < VALUE_INFINITE);
+ MovePicker mp(pos, ttMove, raisedBeta - ss->staticEval, &captureHistory);
int probCutCount = 0;
- while ( (move = mp.next_move()) != MOVE_NONE
- && probCutCount < 2 + 2 * cutNode)
+ while ( (move = mp.next_move()) != MOVE_NONE
+ && probCutCount < 2 + 2 * cutNode
+ && !( move == ttMove
+ && tte->depth() >= depth - 4
+ && ttValue < raisedBeta))
if (move != excludedMove && pos.legal(move))
{
assert(pos.capture_or_promotion(move));
probCutCount++;
ss->currentMove = move;
- ss->continuationHistory = &thisThread->continuationHistory[inCheck]
+ ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck]
[captureOrPromotion]
[pos.moved_piece(move)]
[to_sq(move)];
MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory,
&thisThread->lowPlyHistory,
- &thisThread->captureHistory,
+ &captureHistory,
contHist,
countermove,
ss->killers,
- depth > 12 ? ss->ply : MAX_PLY);
+ ss->ply);
value = bestValue;
- singularLMR = moveCountPruning = false;
+ singularQuietLMR = moveCountPruning = false;
ttCapture = ttMove && pos.capture_or_promotion(ttMove);
// Mark this node as being searched
// Skip quiet moves if movecount exceeds our FutilityMoveCount threshold
moveCountPruning = moveCount >= futility_move_count(improving, depth);
+ // Reduced depth of the next LMR search
+ int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), 0);
+
if ( !captureOrPromotion
&& !givesCheck)
{
- // Reduced depth of the next LMR search
- int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), 0);
-
// Countermoves based pruning (~20 Elo)
if ( lmrDepth < 4 + ((ss-1)->statScore > 0 || (ss-1)->moveCount == 1)
&& (*contHist[0])[movedPiece][to_sq(move)] < CounterMovePruneThreshold
// Futility pruning: parent node (~5 Elo)
if ( lmrDepth < 6
- && !inCheck
- && ss->staticEval + 235 + 172 * lmrDepth <= alpha
- && thisThread->mainHistory[us][from_to(move)]
- + (*contHist[0])[movedPiece][to_sq(move)]
+ && !ss->inCheck
+ && ss->staticEval + 284 + 188 * lmrDepth <= alpha
+ && (*contHist[0])[movedPiece][to_sq(move)]
+ (*contHist[1])[movedPiece][to_sq(move)]
- + (*contHist[3])[movedPiece][to_sq(move)] < 25000)
+ + (*contHist[3])[movedPiece][to_sq(move)]
+ + (*contHist[5])[movedPiece][to_sq(move)] / 2 < 28388)
continue;
// Prune moves with negative SEE (~20 Elo)
- if (!pos.see_ge(move, Value(-(32 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth)))
+ if (!pos.see_ge(move, Value(-(29 - std::min(lmrDepth, 17)) * lmrDepth * lmrDepth)))
+ continue;
+ }
+ else
+ {
+ // Capture history based pruning when the move doesn't give check
+ if ( !givesCheck
+ && lmrDepth < 1
+ && captureHistory[movedPiece][to_sq(move)][type_of(pos.piece_on(to_sq(move)))] < 0)
+ continue;
+
+ // Futility pruning for captures
+ if ( !givesCheck
+ && lmrDepth < 6
+ && !(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
+ + 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)
continue;
}
- else if (!pos.see_ge(move, Value(-194) * depth)) // (~25 Elo)
- continue;
}
// Step 14. Extensions (~75 Elo)
&& tte->depth() >= depth - 3
&& pos.legal(move))
{
- Value singularBeta = ttValue - (((ttPv && !PvNode) + 4) * depth) / 2;
- Depth halfDepth = depth / 2;
+ Value singularBeta = ttValue - ((formerPv + 4) * depth) / 2;
+ Depth singularDepth = (depth - 1 + 3 * formerPv) / 2;
ss->excludedMove = move;
- value = search<NonPV>(pos, ss, singularBeta - 1, singularBeta, halfDepth, cutNode);
+ value = search<NonPV>(pos, ss, singularBeta - 1, singularBeta, singularDepth, cutNode);
ss->excludedMove = MOVE_NONE;
if (value < singularBeta)
{
extension = 1;
- singularLMR = true;
+ singularQuietLMR = !ttCapture;
}
// Multi-cut pruning
// a soft bound.
else if (singularBeta >= beta)
return singularBeta;
+
+ // If the eval of ttMove is greater than beta we try also if there is another
+ // move that pushes it over beta, if so also produce a cutoff.
+ else if (ttValue >= beta)
+ {
+ ss->excludedMove = move;
+ value = search<NonPV>(pos, ss, beta - 1, beta, (depth + 3) / 2, cutNode);
+ ss->excludedMove = MOVE_NONE;
+
+ if (value >= beta)
+ return beta;
+ }
}
// Check extension (~2 Elo)
if (type_of(move) == CASTLING)
extension = 1;
+ // Late irreversible move extension
+ if ( move == ttMove
+ && pos.rule50_count() > 80
+ && (captureOrPromotion || type_of(movedPiece) == PAWN))
+ extension = 2;
+
// Add extension to new depth
newDepth += extension;
// Update the current move (this must be done after singular extension search)
ss->currentMove = move;
- ss->continuationHistory = &thisThread->continuationHistory[inCheck]
+ ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck]
[captureOrPromotion]
[movedPiece]
[to_sq(move)];
|| moveCountPruning
|| ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha
|| cutNode
- || thisThread->ttHitAverage < 375 * ttHitAverageResolution * ttHitAverageWindow / 1024))
+ || thisThread->ttHitAverage < 415 * TtHitAverageResolution * TtHitAverageWindow / 1024))
{
Depth r = reduction(improving, depth, moveCount);
// Decrease reduction if the ttHit running average is large
- if (thisThread->ttHitAverage > 500 * ttHitAverageResolution * ttHitAverageWindow / 1024)
+ if (thisThread->ttHitAverage > 473 * TtHitAverageResolution * TtHitAverageWindow / 1024)
r--;
- // Reduction if other threads are searching this position.
+ // Reduction if other threads are searching this position
if (th.marked())
r++;
if (ttPv)
r -= 2;
+ if (moveCountPruning && !formerPv)
+ r++;
+
// Decrease reduction if opponent's move count is high (~5 Elo)
- if ((ss-1)->moveCount > 14)
+ if ((ss-1)->moveCount > 13)
r--;
// Decrease reduction if ttMove has been singularly extended (~3 Elo)
- if (singularLMR)
- r -= 2;
+ if (singularQuietLMR)
+ r -= 1 + formerPv;
if (!captureOrPromotion)
{
// hence break make_move(). (~2 Elo)
else if ( type_of(move) == NORMAL
&& !pos.see_ge(reverse_move(move)))
- r -= 2 + ttPv;
+ r -= 2 + 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)]
- - 4926;
-
- // Reset statScore to zero if negative and most stats shows >= 0
- if ( ss->statScore < 0
- && (*contHist[0])[movedPiece][to_sq(move)] >= 0
- && (*contHist[1])[movedPiece][to_sq(move)] >= 0
- && thisThread->mainHistory[us][from_to(move)] >= 0)
- ss->statScore = 0;
+ - 4826;
// Decrease/increase reduction by comparing opponent's stat score (~10 Elo)
- if (ss->statScore >= -102 && (ss-1)->statScore < -114)
+ if (ss->statScore >= -100 && (ss-1)->statScore < -112)
r--;
- else if ((ss-1)->statScore >= -116 && ss->statScore < -154)
+ else if ((ss-1)->statScore >= -125 && ss->statScore < -138)
r++;
// Decrease/increase reduction for moves with a good/bad history (~30 Elo)
- r -= ss->statScore / 16384;
+ r -= ss->statScore / 14615;
+ }
+ else
+ {
+ // Increase reduction for captures/promotions if late move and at low depth
+ if (depth < 8 && moveCount > 2)
+ r++;
+
+ // Unless giving check, this capture is likely bad
+ if ( !givesCheck
+ && ss->staticEval + PieceValue[EG][pos.captured_piece()] + 211 * depth <= alpha)
+ r++;
}
- // Increase reduction for captures/promotions if late move and at low depth
- else if (depth < 8 && moveCount > 2)
- r++;
-
- Depth d = clamp(newDepth - r, 1, newDepth);
+ Depth d = Utility::clamp(newDepth - r, 1, newDepth);
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
- doFullDepthSearch = (value > alpha && d != newDepth), didLMR = true;
+ doFullDepthSearch = value > alpha && d != newDepth;
+
+ didLMR = true;
}
else
- doFullDepthSearch = !PvNode || moveCount > 1, didLMR = false;
+ {
+ doFullDepthSearch = !PvNode || moveCount > 1;
+
+ didLMR = false;
+ }
// Step 17. Full depth search when LMR is skipped or fails high
if (doFullDepthSearch)
rm.pv.push_back(*m);
// We record how often the best move has been changed in each
- // iteration. This information is used for time management: When
+ // iteration. This information is used for time management: when
// the best move changes frequently, we allocate some more time.
if (moveCount > 1)
++thisThread->bestMoveChanges;
// must be a mate or a stalemate. If we are in a singular extension search then
// return a fail low score.
- assert(moveCount || !inCheck || excludedMove || !MoveList<LEGAL>(pos).size());
+ assert(moveCount || !ss->inCheck || excludedMove || !MoveList<LEGAL>(pos).size());
if (!moveCount)
bestValue = excludedMove ? alpha
- : inCheck ? mated_in(ss->ply) : VALUE_DRAW;
+ : ss->inCheck ? mated_in(ss->ply) : VALUE_DRAW;
else if (bestMove)
update_all_stats(pos, ss, bestMove, bestValue, beta, prevSq,
Move ttMove, move, bestMove;
Depth ttDepth;
Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha;
- bool ttHit, pvHit, inCheck, givesCheck, captureOrPromotion, evasionPrunable;
+ bool ttHit, pvHit, givesCheck, captureOrPromotion;
int moveCount;
if (PvNode)
Thread* thisThread = pos.this_thread();
(ss+1)->ply = ss->ply + 1;
bestMove = MOVE_NONE;
- inCheck = pos.checkers();
+ ss->inCheck = pos.checkers();
moveCount = 0;
// Check for an immediate draw or maximum ply reached
if ( pos.is_draw(ss->ply)
|| ss->ply >= MAX_PLY)
- return (ss->ply >= MAX_PLY && !inCheck) ? evaluate(pos) : VALUE_DRAW;
+ return (ss->ply >= MAX_PLY && !ss->inCheck) ? evaluate(pos) : VALUE_DRAW;
assert(0 <= ss->ply && ss->ply < MAX_PLY);
// Decide whether or not to include checks: this fixes also the type of
// TT entry depth that we are going to use. Note that in qsearch we use
// only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS.
- ttDepth = inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS
+ ttDepth = ss->inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS
: DEPTH_QS_NO_CHECKS;
// Transposition table lookup
posKey = pos.key();
return ttValue;
// Evaluate the position statically
- if (inCheck)
+ if (ss->inCheck)
{
ss->staticEval = VALUE_NONE;
bestValue = futilityBase = -VALUE_INFINITE;
else
ss->staticEval = bestValue =
(ss-1)->currentMove != MOVE_NULL ? evaluate(pos)
- : -(ss-1)->staticEval + 2 * Eval::Tempo;
+ : -(ss-1)->staticEval + 2 * Tempo;
// Stand pat. Return immediately if static value is at least beta
if (bestValue >= beta)
{
if (!ttHit)
- tte->save(posKey, value_to_tt(bestValue, ss->ply), pvHit, BOUND_LOWER,
+ tte->save(posKey, value_to_tt(bestValue, ss->ply), false, BOUND_LOWER,
DEPTH_NONE, MOVE_NONE, ss->staticEval);
return bestValue;
if (PvNode && bestValue > alpha)
alpha = bestValue;
- futilityBase = bestValue + 154;
+ futilityBase = bestValue + 141;
}
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,
moveCount++;
// Futility pruning
- if ( !inCheck
+ if ( !ss->inCheck
&& !givesCheck
&& futilityBase > -VALUE_KNOWN_WIN
&& !pos.advanced_pawn_push(move))
}
}
- // Detect non-capture evasions that are candidates to be pruned
- evasionPrunable = inCheck
- && (depth != 0 || moveCount > 2)
- && bestValue > VALUE_TB_LOSS_IN_MAX_PLY
- && !pos.capture(move);
-
- // Don't search moves with negative SEE values
- if ( (!inCheck || evasionPrunable) && !pos.see_ge(move))
+ // Do not search moves with negative SEE values
+ if ( !ss->inCheck && !pos.see_ge(move))
continue;
// Speculative prefetch as early as possible
}
ss->currentMove = move;
- ss->continuationHistory = &thisThread->continuationHistory[inCheck]
+ ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck]
[captureOrPromotion]
[pos.moved_piece(move)]
[to_sq(move)];
}
}
- // All legal moves have been searched. A special case: If we're in check
+ // 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)
+ if (ss->inCheck && bestValue == -VALUE_INFINITE)
return mated_in(ss->ply); // Plies to mate from the root
tte->save(posKey, value_to_tt(bestValue, ss->ply), pvHit,
// value_to_tt() adjusts a mate or TB score from "plies to mate from the root" to
- // "plies to mate from the current position". standard scores are unchanged.
+ // "plies to mate from the current position". Standard scores are unchanged.
// The function is called before storing a value in the transposition table.
Value value_to_tt(Value v, int ply) {
}
- // value_from_tt() is the inverse of value_to_tt(): It adjusts a mate or TB score
- // from the transposition table (which refers to the plies to mate/be mated
- // from current position) to "plies to mate/be mated (TB win/loss) from the root".
- // However, for mate scores, to avoid potentially false mate scores related to the 50 moves rule,
- // and the graph history interaction, return an optimal TB score instead.
+ // value_from_tt() is the inverse of value_to_tt(): it adjusts a mate or TB score
+ // from the transposition table (which refers to the plies to mate/be mated from
+ // current position) to "plies to mate/be mated (TB win/loss) from the root". However,
+ // for mate scores, to avoid potentially false mate scores related to the 50 moves rule
+ // and the graph history interaction, we return an optimal TB score instead.
Value value_from_tt(Value v, int ply, int r50c) {
// update_continuation_histories() updates histories of the move pairs formed
- // by moves at ply -1, -2, and -4 with current move.
+ // by moves at ply -1, -2, -4, and -6 with current move.
void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus) {
for (int i : {1, 2, 4, 6})
+ {
+ if (ss->inCheck && i > 2)
+ break;
if (is_ok((ss-i)->currentMove))
(*(ss-i)->continuationHistory)[pc][to] << bonus;
+ }
}
thisThread->counterMoves[pos.piece_on(prevSq)][prevSq] = move;
}
- if (depth > 12 && ss->ply < MAX_LPH)
- thisThread->lowPlyHistory[ss->ply][from_to(move)] << stat_bonus(depth - 7);
+ if (depth > 11 && ss->ply < MAX_LPH)
+ thisThread->lowPlyHistory[ss->ply][from_to(move)] << stat_bonus(depth - 6);
}
// When playing with strength handicap, choose best move among a set of RootMoves
} // namespace
+
/// MainThread::check_time() is used to print debug info and, more importantly,
/// to detect when we are out of available time and thus stop the search.
<< " 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" : "");
projects / stockfish / blobdiff