const int SkipSize[] = { 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4 };
const int SkipPhase[] = { 0, 1, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 6, 7 };
- // Razoring and futility margins
- const int RazorMargin = 590;
+ // Razor and futility margins
+ const int RazorMargin1 = 590;
+ const int RazorMargin2 = 604;
Value futility_margin(Depth d) { return Value(150 * d / ONE_PLY); }
// Futility and reductions lookup tables, initialized at startup
void update_quiet_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);
+ inline bool gives_check(const Position& pos, Move move) {
+ Color us = pos.side_to_move();
+ return type_of(move) == NORMAL && !(pos.blockers_for_king(~us) & pos.pieces(us))
+ ? pos.check_squares(type_of(pos.moved_piece(move))) & to_sq(move)
+ : pos.gives_check(move);
+ }
+
// 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.
template<bool Root>
std::memset(ss-4, 0, 7 * sizeof(Stack));
for (int i = 4; i > 0; i--)
- (ss-i)->contHistory = &this->contHistory[NO_PIECE][0]; // Use as sentinel
+ (ss-i)->contHistory = this->contHistory[NO_PIECE][0].get(); // Use as sentinel
bestValue = delta = alpha = -VALUE_INFINITE;
beta = VALUE_INFINITE;
// Age out PV variability metric
if (mainThread)
- mainThread->bestMoveChanges *= 0.505, mainThread->failedLow = false;
+ mainThread->bestMoveChanges *= 0.517, mainThread->failedLow = false;
// Save the last iteration's scores before first PV line is searched and
// all the move scores except the (new) PV are set to -VALUE_INFINITE.
const int F[] = { mainThread->failedLow,
bestValue - mainThread->previousScore };
- int improvingFactor = std::max(229, std::min(715, 357 + 119 * F[0] - 6 * F[1]));
+ int improvingFactor = std::max(246, std::min(832, 306 + 119 * F[0] - 6 * F[1]));
// If the bestMove is stable over several iterations, reduce time accordingly
timeReduction = 1.0;
for (int i : {3, 4, 5})
if (lastBestMoveDepth * i < completedDepth)
- timeReduction *= 1.3;
+ timeReduction *= 1.25;
// Use part of the gained time from a previous stable move for the current move
double unstablePvFactor = 1.0 + mainThread->bestMoveChanges;
- unstablePvFactor *= std::pow(mainThread->previousTimeReduction, 0.51) / timeReduction;
+ unstablePvFactor *= std::pow(mainThread->previousTimeReduction, 0.528) / timeReduction;
// Stop the search if we have only one legal move, or if available time elapsed
if ( rootMoves.size() == 1
- || Time.elapsed() > Time.optimum() * unstablePvFactor * improvingFactor / 605)
+ || Time.elapsed() > Time.optimum() * unstablePvFactor * improvingFactor / 581)
{
// If we are allowed to ponder do not stop the search now but
// keep pondering until the GUI sends "ponderhit" or "stop".
Thread* thisThread = pos.this_thread();
inCheck = pos.checkers();
moveCount = captureCount = quietCount = ss->moveCount = 0;
- ss->statScore = 0;
bestValue = -VALUE_INFINITE;
maxValue = VALUE_INFINITE;
(ss+1)->ply = ss->ply + 1;
ss->currentMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
- ss->contHistory = &thisThread->contHistory[NO_PIECE][0];
+ ss->contHistory = thisThread->contHistory[NO_PIECE][0].get();
(ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
Square prevSq = to_sq((ss-1)->currentMove);
+ // Initialize statScore to zero for the grandchildren of the current position.
+ // So statScore is shared between all grandchildren and only the first grandchild
+ // 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.
+ (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.
else if (!pos.capture_or_promotion(ttMove))
{
int penalty = -stat_bonus(depth);
- thisThread->mainHistory.update(pos.side_to_move(), ttMove, penalty);
+ thisThread->mainHistory[pos.side_to_move()][from_to(ttMove)] << penalty;
update_continuation_histories(ss, pos.moved_piece(ttMove), to_sq(ttMove), penalty);
}
}
// Step 7. Razoring (skipped when in check)
if ( !PvNode
- && depth < 3 * ONE_PLY
- && eval + RazorMargin <= alpha)
+ && depth <= ONE_PLY)
{
- if (depth <= ONE_PLY)
+ if (eval + RazorMargin1 <= alpha)
return qsearch<NonPV, false>(pos, ss, alpha, alpha+1);
-
- Value ralpha = alpha - RazorMargin;
+ }
+ else if ( !PvNode
+ && depth <= 2 * ONE_PLY
+ && eval + RazorMargin2 <= alpha)
+ {
+ Value ralpha = alpha - RazorMargin2;
Value v = qsearch<NonPV, false>(pos, ss, ralpha, ralpha+1);
if (v <= ralpha)
return v;
Depth R = ((823 + 67 * depth / ONE_PLY) / 256 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY;
ss->currentMove = MOVE_NULL;
- ss->contHistory = &thisThread->contHistory[NO_PIECE][0];
+ ss->contHistory = thisThread->contHistory[NO_PIECE][0].get();
pos.do_null_move(st);
Value nullValue = depth-R < ONE_PLY ? -qsearch<NonPV, false>(pos, ss+1, -beta, -beta+1)
Value rbeta = std::min(beta + 200, VALUE_INFINITE);
MovePicker mp(pos, ttMove, rbeta - ss->staticEval, &thisThread->captureHistory);
-
- while ((move = mp.next_move()) != MOVE_NONE)
+ int probCutCount = 0;
+ while ( (move = mp.next_move()) != MOVE_NONE
+ && probCutCount < depth / ONE_PLY - 3)
if (pos.legal(move))
{
+ probCutCount++;
+
ss->currentMove = move;
- ss->contHistory = &thisThread->contHistory[pos.moved_piece(move)][to_sq(move)];
+ ss->contHistory = thisThread->contHistory[pos.moved_piece(move)][to_sq(move)].get();
assert(depth >= 5 * ONE_PLY);
pos.do_move(move, st);
- value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, depth - 4 * ONE_PLY, !cutNode, false);
+
+ // Perform a preliminary search at depth 1 to verify that the move holds.
+ // We will only do this search if the depth is not 5, thus avoiding two
+ // searches at depth 1 in a row.
+ if (depth != 5 * ONE_PLY)
+ value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, ONE_PLY, !cutNode, true);
+
+ // If the first search was skipped or was performed and held, perform
+ // the regular search.
+ if (depth == 5 * ONE_PLY || value >= rbeta)
+ value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, depth - 4 * ONE_PLY, !cutNode, false);
+
pos.undo_move(move);
if (value >= rbeta)
return value;
search<NT>(pos, ss, alpha, beta, d, cutNode, true);
tte = TT.probe(posKey, ttHit);
+ ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
ttMove = ttHit ? tte->move() : MOVE_NONE;
}
extension = DEPTH_ZERO;
captureOrPromotion = pos.capture_or_promotion(move);
movedPiece = pos.moved_piece(move);
-
- givesCheck = type_of(move) == NORMAL && !pos.discovered_check_candidates()
- ? pos.check_squares(type_of(movedPiece)) & to_sq(move)
- : pos.gives_check(move);
+ givesCheck = gives_check(pos, move);
moveCountPruning = depth < 16 * ONE_PLY
&& moveCount >= FutilityMoveCounts[improving][depth / ONE_PLY];
// Update the current move (this must be done after singular extension search)
ss->currentMove = move;
- ss->contHistory = &thisThread->contHistory[movedPiece][to_sq(move)];
+ ss->contHistory = thisThread->contHistory[movedPiece][to_sq(move)].get();
// Step 15. Make the move
pos.do_move(move, st, givesCheck);
// Transposition table lookup
posKey = pos.key();
tte = TT.probe(posKey, ttHit);
- ttMove = ttHit ? tte->move() : MOVE_NONE;
ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
+ ttMove = ttHit ? tte->move() : MOVE_NONE;
if ( !PvNode
&& ttHit
{
assert(is_ok(move));
- givesCheck = type_of(move) == NORMAL && !pos.discovered_check_candidates()
- ? pos.check_squares(type_of(pos.moved_piece(move))) & to_sq(move)
- : pos.gives_check(move);
+ givesCheck = gives_check(pos, move);
moveCount++;
for (int i : {1, 2, 4})
if (is_ok((ss-i)->currentMove))
- (ss-i)->contHistory->update(pc, to, bonus);
+ (*(ss-i)->contHistory)[pc][to] << 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);
+ captureHistory[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);
+ captureHistory[moved_piece][to_sq(captures[i])][captured] << -bonus;
}
}
Color us = pos.side_to_move();
Thread* thisThread = pos.this_thread();
- thisThread->mainHistory.update(us, move, bonus);
+ thisThread->mainHistory[us][from_to(move)] << bonus;
update_continuation_histories(ss, pos.moved_piece(move), to_sq(move), bonus);
if (is_ok((ss-1)->currentMove))
// Decrease all the other played quiet moves
for (int i = 0; i < quietsCnt; ++i)
{
- thisThread->mainHistory.update(us, quiets[i], -bonus);
+ thisThread->mainHistory[us][from_to(quiets[i])] << -bonus;
update_continuation_histories(ss, pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
}
}