&& !Skill(Options["Skill Level"]).enabled()
&& rootMoves[0].pv[0] != MOVE_NONE)
{
- std::map<Move, int> votes;
+ std::map<Move, int64_t> votes;
Value minScore = this->rootMoves[0].score;
// Find out minimum score and reset votes for moves which can be voted
}
// Vote according to score and depth
+ auto square = [](int64_t x) { return x * x; };
for (Thread* th : Threads)
- votes[th->rootMoves[0].pv[0]] += int(th->rootMoves[0].score - minScore)
- + int(th->completedDepth);
+ votes[th->rootMoves[0].pv[0]] += 200 + (square(th->rootMoves[0].score - minScore + 1)
+ * int64_t(th->completedDepth));
// Select best thread
- int bestVote = votes[this->rootMoves[0].pv[0]];
+ int64_t bestVote = votes[this->rootMoves[0].pv[0]];
for (Thread* th : Threads)
{
if (votes[th->rootMoves[0].pv[0]] > bestVote)
void Thread::search() {
Stack stack[MAX_PLY+7], *ss = stack+4; // To reference from (ss-4) to (ss+2)
+ Move pv[MAX_PLY+1];
Value bestValue, alpha, beta, delta;
Move lastBestMove = MOVE_NONE;
Depth lastBestMoveDepth = DEPTH_ZERO;
std::memset(ss-4, 0, 7 * sizeof(Stack));
for (int i = 4; i > 0; i--)
(ss-i)->continuationHistory = &this->continuationHistory[NO_PIECE][0]; // Use as sentinel
+ ss->pv = pv;
bestValue = delta = alpha = -VALUE_INFINITE;
beta = VALUE_INFINITE;
{
beta = std::min(bestValue + delta, VALUE_INFINITE);
if (mainThread)
- ++failedHighCnt;
+ ++failedHighCnt;
}
else
break;
&& !Threads.stop
&& !Threads.stopOnPonderhit)
{
- const int F[] = { failedLow,
- bestValue - mainThread->previousScore };
-
- int improvingFactor = std::max(246, std::min(832, 306 + 119 * F[0] - 6 * F[1]));
+ double fallingEval = (306 + 119 * failedLow + 6 * (mainThread->previousScore - bestValue)) / 581.0;
+ fallingEval = std::max(0.5, std::min(1.5, fallingEval));
// If the bestMove is stable over several iterations, reduce time accordingly
timeReduction = 1.0;
// Stop the search if we have only one legal move, or if available time elapsed
if ( rootMoves.size() == 1
- || Time.elapsed() > Time.optimum() * bestMoveInstability * improvingFactor / 581)
+ || Time.elapsed() > Time.optimum() * bestMoveInstability * fallingEval)
{
// If we are allowed to ponder do not stop the search now but
// keep pondering until the GUI sends "ponderhit" or "stop".
if (!pos.capture_or_promotion(ttMove))
update_quiet_stats(pos, ss, ttMove, nullptr, 0, 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())
- update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
+ // 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] && (ss-1)->killers[0]))
+ if (!pos.captured_piece())
+ update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
}
// Penalty for a quiet ttMove that fails low
else if (!pos.capture_or_promotion(ttMove))
TB::ProbeState err;
TB::WDLScore wdl = Tablebases::probe_wdl(pos, &err);
+ // Force check of time on the next occasion
+ if (thisThread == Threads.main())
+ static_cast<MainThread*>(thisThread)->callsCnt = 0;
+
if (err != TB::ProbeState::FAIL)
{
thisThread->tbHits.fetch_add(1, std::memory_order_relaxed);
}
// Step 7. Razoring (~2 Elo)
- if ( depth < 2 * ONE_PLY
- && eval <= alpha - RazorMargin)
+ if ( !rootNode // The required rootNode PV handling is not available in qsearch
+ && depth < 2 * ONE_PLY
+ && eval <= alpha - RazorMargin)
return qsearch<NT>(pos, ss, alpha, beta);
improving = ss->staticEval >= (ss-2)->staticEval
|| (ss-2)->staticEval == VALUE_NONE;
// Step 8. Futility pruning: child node (~30 Elo)
- if ( !rootNode
+ if ( !PvNode
&& depth < 7 * ONE_PLY
&& eval - futility_margin(depth, improving) >= beta
&& eval < VALUE_KNOWN_WIN) // Do not return unproven wins
&& depth >= 5 * ONE_PLY
&& abs(beta) < VALUE_MATE_IN_MAX_PLY)
{
- Value rbeta = std::min(beta + 216 - 48 * improving, VALUE_INFINITE);
- MovePicker mp(pos, ttMove, rbeta - ss->staticEval, &thisThread->captureHistory);
+ Value raisedBeta = std::min(beta + 216 - 48 * improving, VALUE_INFINITE);
+ MovePicker mp(pos, ttMove, raisedBeta - ss->staticEval, &thisThread->captureHistory);
int probCutCount = 0;
while ( (move = mp.next_move()) != MOVE_NONE
pos.do_move(move, st);
// Perform a preliminary qsearch to verify that the move holds
- value = -qsearch<NonPV>(pos, ss+1, -rbeta, -rbeta+1);
+ value = -qsearch<NonPV>(pos, ss+1, -raisedBeta, -raisedBeta+1);
// If the qsearch held perform the regular search
- if (value >= rbeta)
- value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, depth - 4 * ONE_PLY, !cutNode);
+ if (value >= raisedBeta)
+ value = -search<NonPV>(pos, ss+1, -raisedBeta, -raisedBeta+1, depth - 4 * ONE_PLY, !cutNode);
pos.undo_move(move);
- if (value >= rbeta)
+ if (value >= raisedBeta)
return value;
}
}
if ( depth >= 8 * ONE_PLY
&& move == ttMove
&& !rootNode
- && !excludedMove // Recursive singular search is not allowed
+ && !excludedMove // Avoid recursive singular search
&& ttValue != VALUE_NONE
&& (tte->bound() & BOUND_LOWER)
&& tte->depth() >= depth - 3 * ONE_PLY
&& pos.legal(move))
{
- Value rBeta = std::max(ttValue - 2 * depth / ONE_PLY, -VALUE_MATE);
+ Value reducedBeta = std::max(ttValue - 2 * depth / ONE_PLY, -VALUE_MATE);
ss->excludedMove = move;
- value = search<NonPV>(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode);
+ value = search<NonPV>(pos, ss, reducedBeta - 1, reducedBeta, depth / 2, cutNode);
ss->excludedMove = MOVE_NONE;
- if (value < rBeta)
+ if (value < reducedBeta)
extension = ONE_PLY;
}
else if ( givesCheck // Check extension (~2 Elo)
&& pos.see_ge(move))
extension = ONE_PLY;
- else if ( pos.can_castle(us) // Extension for king moves that change castling rights
- && type_of(movedPiece) == KING)
+ // Extension if castling
+ else if (type_of(move) == CASTLING)
extension = ONE_PLY;
// Calculate new depth for this move
{
if ( !captureOrPromotion
&& !givesCheck
- && (!pos.advanced_pawn_push(move) || pos.non_pawn_material() >= Value(5000)))
+ && !pos.advanced_pawn_push(move))
{
// Move count based pruning (~30 Elo)
if (moveCountPruning)
int lmrDepth = std::max(newDepth - reduction<PvNode>(improving, depth, moveCount), DEPTH_ZERO) / ONE_PLY;
// Countermoves based pruning (~20 Elo)
- if ( lmrDepth < 3 + ((ss-1)->statScore > 0)
+ if ( lmrDepth < 3 + ((ss-1)->statScore > 0 || (ss-1)->moveCount == 1)
&& (*contHist[0])[movedPiece][to_sq(move)] < CounterMovePruneThreshold
&& (*contHist[1])[movedPiece][to_sq(move)] < CounterMovePruneThreshold)
continue;
update_capture_stats(pos, bestMove, capturesSearched, captureCount, stat_bonus(depth + ONE_PLY));
- // Extra penalty for a quiet TT move in previous ply when it gets refuted
- if ((ss-1)->moveCount == 1 && !pos.captured_piece())
- update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
+ // 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] && (ss-1)->killers[0]))
+ if (!pos.captured_piece())
+ update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
+
}
// Bonus for prior countermove that caused the fail low
else if ( (depth >= 3 * ONE_PLY || PvNode)
if (value > alpha)
{
+ bestMove = move;
+
if (PvNode) // Update pv even in fail-high case
update_pv(ss->pv, move, (ss+1)->pv);
if (PvNode && value < beta) // Update alpha here!
- {
alpha = value;
- bestMove = move;
- }
- else // Fail high
- {
- tte->save(posKey, value_to_tt(value, ss->ply), BOUND_LOWER,
- ttDepth, move, ss->staticEval);
-
- return value;
- }
+ else
+ break; // Fail high
}
}
}
return mated_in(ss->ply); // Plies to mate from the root
tte->save(posKey, value_to_tt(bestValue, ss->ply),
- PvNode && bestValue > oldAlpha ? BOUND_EXACT : BOUND_UPPER,
+ bestValue >= beta ? BOUND_LOWER :
+ PvNode && bestValue > oldAlpha ? BOUND_EXACT : BOUND_UPPER,
ttDepth, bestMove, ss->staticEval);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
projects / stockfish / blobdiff