Value value_to_tt(Value v, int ply);
Value value_from_tt(Value v, int ply);
bool check_is_dangerous(Position& pos, Move move, Value futilityBase, Value beta);
- bool yields_to_threat(const Position& pos, Move move, Move threat);
- bool prevents_threat(const Position& pos, Move move, Move threat);
+ bool allows_move(const Position& pos, Move first, Move second);
+ bool prevents_move(const Position& pos, Move first, Move second);
string uci_pv(const Position& pos, int depth, Value alpha, Value beta);
struct Skill {
{
RootMoves.push_back(MOVE_NONE);
sync_cout << "info depth 0 score "
- << score_to_uci(RootPos.in_check() ? -VALUE_MATE : VALUE_DRAW)
+ << score_to_uci(RootPos.checkers() ? -VALUE_MATE : VALUE_DRAW)
<< sync_endl;
goto finalize;
}
- if (Options["OwnBook"] && !Limits.infinite)
+ if (Options["OwnBook"] && !Limits.infinite && !Limits.mate)
{
Move bookMove = book.probe(RootPos, Options["Book File"], Options["Best Book Move"]);
if (Options["Contempt Factor"] && !Options["UCI_AnalyseMode"])
{
int cf = Options["Contempt Factor"] * PawnValueMg / 100; // From centipawns
- cf = cf * MaterialTable::game_phase(RootPos) / PHASE_MIDGAME; // Scale down with phase
+ cf = cf * Material::game_phase(RootPos) / PHASE_MIDGAME; // Scale down with phase
DrawValue[ RootColor] = VALUE_DRAW - Value(cf);
DrawValue[~RootColor] = VALUE_DRAW + Value(cf);
}
if (depth > 2 && BestMoveChanges)
bestMoveNeverChanged = false;
+ // Do we have found a "mate in x"?
+ if ( Limits.mate
+ && bestValue >= VALUE_MATE_IN_MAX_PLY
+ && VALUE_MATE - bestValue <= 2 * Limits.mate)
+ Signals.stop = true;
+
// Do we have time for the next iteration? Can we stop searching now?
if (Limits.use_time_management() && !Signals.stopOnPonderhit)
{
Key posKey;
Move ttMove, move, excludedMove, bestMove, threatMove;
Depth ext, newDepth;
- Value bestValue, value, ttValue, ttValueUpper;
+ Value bestValue, value, ttValue;
Value eval, nullValue, futilityValue;
bool inCheck, givesCheck, pvMove, singularExtensionNode;
- bool captureOrPromotion, dangerous, doFullDepthSearch;
+ bool captureOrPromotion, dangerous, doFullDepthSearch, threatExtension;
int moveCount, playedMoveCount;
// Step 1. Initialize node
Thread* thisThread = pos.this_thread();
moveCount = playedMoveCount = 0;
- inCheck = pos.in_check();
+ threatExtension = false;
+ inCheck = pos.checkers();
if (SpNode)
{
tte = TT.probe(posKey);
ttMove = RootNode ? RootMoves[PVIdx].pv[0] : tte ? tte->move() : MOVE_NONE;
ttValue = tte ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
- ttValueUpper = tte ? value_from_tt(tte->value_upper(), ss->ply) : VALUE_NONE;
// At PV nodes we check for exact scores, while at non-PV nodes we check for
// a fail high/low. Biggest advantage at probing at PV nodes is to have a
// smooth experience in analysis mode. We don't probe at Root nodes otherwise
// we should also update RootMoveList to avoid bogus output.
- if (!RootNode && tte)
+ if ( !RootNode
+ && tte
+ && tte->depth() >= depth
+ && ttValue != VALUE_NONE // Only in case of TT access race
+ && ( PvNode ? tte->type() == BOUND_EXACT
+ : ttValue >= beta ? (tte->type() & BOUND_LOWER)
+ : (tte->type() & BOUND_UPPER)))
{
- // Fail High
- if ( (tte->type() & BOUND_LOWER)
- && ttValue >= beta
- && tte->depth() >= depth
- && ttValue != VALUE_NONE) // Only in case of TT access race
- {
- // Update killers, we assume ttMove caused a cut-off
- if ( ttMove
- && !pos.is_capture_or_promotion(ttMove)
- && ttMove != ss->killers[0])
- {
- ss->killers[1] = ss->killers[0];
- ss->killers[0] = ttMove;
- }
- TT.refresh(tte);
- ss->currentMove = ttMove; // Can be MOVE_NONE
- return ttValue;
- }
+ TT.refresh(tte);
+ ss->currentMove = ttMove; // Can be MOVE_NONE
- // Fail Low
- if ( (tte->type() & BOUND_UPPER)
- && ttValueUpper <= alpha
- && tte->depth_upper() >= depth
- && ttValueUpper != VALUE_NONE) // Only in case of TT access race
+ if ( ttValue >= beta
+ && ttMove
+ && !pos.is_capture_or_promotion(ttMove)
+ && ttMove != ss->killers[0])
{
- TT.refresh(tte);
- ss->currentMove = ttMove; // Can be MOVE_NONE
- return ttValueUpper;
+ ss->killers[1] = ss->killers[0];
+ ss->killers[0] = ttMove;
}
+ return ttValue;
}
// Step 5. Evaluate the position statically and update parent's gain statistics
if (inCheck)
ss->staticEval = ss->evalMargin = eval = VALUE_NONE;
- else
+
+ else if (tte)
{
- eval = ss->staticEval = evaluate(pos, ss->evalMargin);
+ // Never assume anything on values stored in TT
+ if ( (ss->staticEval = eval = tte->static_value()) == VALUE_NONE
+ ||(ss->evalMargin = tte->static_value_margin()) == VALUE_NONE)
+ eval = ss->staticEval = evaluate(pos, ss->evalMargin);
// Can ttValue be used as a better position evaluation?
- if (tte && ttValue != VALUE_NONE)
- {
+ if (ttValue != VALUE_NONE)
if ( ((tte->type() & BOUND_LOWER) && ttValue > eval)
|| ((tte->type() & BOUND_UPPER) && ttValue < eval))
eval = ttValue;
- }
+ }
+ else
+ {
+ eval = ss->staticEval = evaluate(pos, ss->evalMargin);
+ TT.store(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE,
+ ss->staticEval, ss->evalMargin);
}
// Update gain for the parent non-capture move given the static position
// The null move failed low, which means that we may be faced with
// some kind of threat. If the previous move was reduced, check if
// the move that refuted the null move was somehow connected to the
- // move which was reduced. If a connection is found, return a fail
- // low score (which will cause the reduced move to fail high in the
- // parent node, which will trigger a re-search with full depth).
+ // move which was reduced. If a connection is found extend moves that
+ // defend against threat.
threatMove = (ss+1)->currentMove;
if ( depth < 5 * ONE_PLY
&& (ss-1)->reduction
&& threatMove != MOVE_NONE
- && yields_to_threat(pos, (ss-1)->currentMove, threatMove))
- return beta - 1;
+ && allows_move(pos, (ss-1)->currentMove, threatMove))
+ threatExtension = true;
}
}
if (PvNode && dangerous)
ext = ONE_PLY;
+ else if (threatExtension && prevents_move(pos, move, threatMove))
+ ext = ONE_PLY;
+
else if (givesCheck && pos.see_sign(move) >= 0)
ext = ONE_PLY / 2;
// Move count based pruning
if ( depth < 16 * ONE_PLY
&& moveCount >= FutilityMoveCounts[depth]
- && (!threatMove || !prevents_threat(pos, move, threatMove)))
+ && (!threatMove || !prevents_move(pos, move, threatMove)))
{
if (SpNode)
sp->mutex.lock();
// Step 19. Check for splitting the search
if ( !SpNode
&& depth >= Threads.min_split_depth()
- && bestValue < beta
&& Threads.available_slave_exists(thisThread))
{
+ assert(bestValue < beta);
+
bestValue = Threads.split<FakeSplit>(pos, ss, alpha, beta, bestValue, &bestMove,
depth, threatMove, moveCount, mp, NT);
if (bestValue >= beta)
if (bestValue >= beta) // Failed high
{
- TT.store(posKey, value_to_tt(bestValue, ss->ply), BOUND_LOWER, depth, bestMove);
+ TT.store(posKey, value_to_tt(bestValue, ss->ply), BOUND_LOWER, depth,
+ bestMove, ss->staticEval, ss->evalMargin);
if (!pos.is_capture_or_promotion(bestMove) && !inCheck)
{
else // Failed low or PV search
TT.store(posKey, value_to_tt(bestValue, ss->ply),
PvNode && bestMove != MOVE_NONE ? BOUND_EXACT : BOUND_UPPER,
- depth, bestMove);
+ depth, bestMove, ss->staticEval, ss->evalMargin);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
const bool PvNode = (NT == PV);
assert(NT == PV || NT == NonPV);
- assert(InCheck == pos.in_check());
+ assert(InCheck == !!pos.checkers());
assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE);
assert(PvNode || (alpha == beta - 1));
assert(depth <= DEPTH_ZERO);
const TTEntry* tte;
Key posKey;
Move ttMove, move, bestMove;
- Value bestValue, value, ttValue, ttValueUpper, futilityValue, futilityBase, oldAlpha;
+ Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha;
bool givesCheck, enoughMaterial, evasionPrunable, fromNull;
Depth ttDepth;
tte = TT.probe(posKey);
ttMove = tte ? tte->move() : MOVE_NONE;
ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_NONE;
- ttValueUpper = tte ? value_from_tt(tte->value_upper(),ss->ply) : VALUE_NONE;
// 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
: DEPTH_QS_NO_CHECKS;
- if (tte)
+ if ( tte
+ && tte->depth() >= ttDepth
+ && ttValue != VALUE_NONE // Only in case of TT access race
+ && ( PvNode ? tte->type() == BOUND_EXACT
+ : ttValue >= beta ? (tte->type() & BOUND_LOWER)
+ : (tte->type() & BOUND_UPPER)))
{
- // Fail High
- if ( (tte->type() & BOUND_LOWER)
- && ttValue >= beta
- && tte->depth() >= ttDepth
- && ttValue != VALUE_NONE) // Only in case of TT access race
- {
- ss->currentMove = ttMove; // Can be MOVE_NONE
- return ttValue;
- }
-
- // Fail Low
- if ( (tte->type() & BOUND_UPPER)
- && ttValueUpper <= alpha
- && tte->depth_upper() >= ttDepth
- && ttValueUpper != VALUE_NONE) // Only in case of TT access race
- {
- ss->currentMove = ttMove; // Can be MOVE_NONE
- return ttValueUpper;
- }
+ ss->currentMove = ttMove; // Can be MOVE_NONE
+ return ttValue;
}
// Evaluate the position statically
ss->staticEval = bestValue = -(ss-1)->staticEval;
ss->evalMargin = VALUE_ZERO;
}
+ else if (tte)
+ {
+ // Never assume anything on values stored in TT
+ if ( (ss->staticEval = bestValue = tte->static_value()) == VALUE_NONE
+ ||(ss->evalMargin = tte->static_value_margin()) == VALUE_NONE)
+ ss->staticEval = bestValue = evaluate(pos, ss->evalMargin);
+ }
else
ss->staticEval = bestValue = evaluate(pos, ss->evalMargin);
if (bestValue >= beta)
{
if (!tte)
- TT.store(pos.key(), value_to_tt(bestValue, ss->ply), BOUND_LOWER, DEPTH_NONE, MOVE_NONE);
+ TT.store(pos.key(), value_to_tt(bestValue, ss->ply), BOUND_LOWER,
+ DEPTH_NONE, MOVE_NONE, ss->staticEval, ss->evalMargin);
return bestValue;
}
}
else // Fail high
{
- TT.store(posKey, value_to_tt(value, ss->ply), BOUND_LOWER, ttDepth, move);
+ TT.store(posKey, value_to_tt(value, ss->ply), BOUND_LOWER,
+ ttDepth, move, ss->staticEval, ss->evalMargin);
+
return value;
}
}
TT.store(posKey, value_to_tt(bestValue, ss->ply),
PvNode && bestValue > oldAlpha ? BOUND_EXACT : BOUND_UPPER,
- ttDepth, bestMove);
+ ttDepth, bestMove, ss->staticEval, ss->evalMargin);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
}
- // yields_to_threat() tests whether the move at previous ply yields to the so
- // called threat move (the best move returned from a null search that fails
- // low). Here 'yields to' means that the move somehow made the threat possible
- // for instance if the moving piece is the same in both moves.
+ // allows_move() tests whether the move at previous ply (first) somehow makes a
+ // second move possible, for instance if the moving piece is the same in both
+ // moves. Normally the second move is the threat move (the best move returned
+ // from a null search that fails low).
- bool yields_to_threat(const Position& pos, Move move, Move threat) {
+ bool allows_move(const Position& pos, Move first, Move second) {
- assert(is_ok(move));
- assert(is_ok(threat));
- assert(color_of(pos.piece_on(from_sq(threat))) == ~pos.side_to_move());
+ assert(is_ok(first));
+ assert(is_ok(second));
+ assert(color_of(pos.piece_on(from_sq(second))) == ~pos.side_to_move());
+ assert(color_of(pos.piece_on(to_sq(first))) == ~pos.side_to_move());
- Square mfrom = from_sq(move);
- Square mto = to_sq(move);
- Square tfrom = from_sq(threat);
- Square tto = to_sq(threat);
+ Square m1from = from_sq(first);
+ Square m2from = from_sq(second);
+ Square m1to = to_sq(first);
+ Square m2to = to_sq(second);
- // The piece is the same or threat's destination was vacated by the move
- if (mto == tfrom || tto == mfrom)
+ // The piece is the same or second's destination was vacated by the first move
+ if (m1to == m2from || m2to == m1from)
return true;
- // Threat moves through the vacated square
- if (between_bb(tfrom, tto) & mfrom)
+ // Second one moves through the square vacated by first one
+ if (between_bb(m2from, m2to) & m1from)
return true;
- // Threat's destination is defended by the move's piece
- Bitboard matt = pos.attacks_from(pos.piece_on(mto), mto, pos.pieces() ^ tfrom);
- if (matt & tto)
+ // Second's destination is defended by the first move's piece
+ Bitboard m1att = pos.attacks_from(pos.piece_on(m1to), m1to, pos.pieces() ^ m2from);
+ if (m1att & m2to)
return true;
- // Threat gives a discovered check through the move's checking piece
- if (matt & pos.king_square(pos.side_to_move()))
+ // Second move gives a discovered check through the first's checking piece
+ if (m1att & pos.king_square(pos.side_to_move()))
{
- assert(between_bb(mto, pos.king_square(pos.side_to_move())) & tfrom);
+ assert(between_bb(m1to, pos.king_square(pos.side_to_move())) & m2from);
return true;
}
}
- // prevents_threat() tests whether a move is able to defend against the so
- // called threat move (the best move returned from a null search that fails
- // low). In this case will not be pruned.
+ // prevents_move() tests whether a move (first) is able to defend against an
+ // opponent's move (second). In this case will not be pruned. Normally the
+ // second move is the threat move (the best move returned from a null search
+ // that fails low).
- bool prevents_threat(const Position& pos, Move move, Move threat) {
+ bool prevents_move(const Position& pos, Move first, Move second) {
- assert(is_ok(move));
- assert(is_ok(threat));
- assert(!pos.is_capture_or_promotion(move));
- assert(!pos.is_passed_pawn_push(move));
+ assert(is_ok(first));
+ assert(is_ok(second));
- Square mfrom = from_sq(move);
- Square mto = to_sq(move);
- Square tfrom = from_sq(threat);
- Square tto = to_sq(threat);
+ Square m1from = from_sq(first);
+ Square m2from = from_sq(second);
+ Square m1to = to_sq(first);
+ Square m2to = to_sq(second);
// Don't prune moves of the threatened piece
- if (mfrom == tto)
+ if (m1from == m2to)
return true;
// If the threatened piece has value less than or equal to the value of the
// threat piece, don't prune moves which defend it.
- if ( pos.is_capture(threat)
- && ( PieceValue[MG][pos.piece_on(tfrom)] >= PieceValue[MG][pos.piece_on(tto)]
- || type_of(pos.piece_on(tfrom)) == KING))
+ if ( pos.is_capture(second)
+ && ( PieceValue[MG][pos.piece_on(m2from)] >= PieceValue[MG][pos.piece_on(m2to)]
+ || type_of(pos.piece_on(m2from)) == KING))
{
// Update occupancy as if the piece and the threat are moving
- Bitboard occ = pos.pieces() ^ mfrom ^ mto ^ tfrom;
- Piece piece = pos.piece_on(mfrom);
+ Bitboard occ = pos.pieces() ^ m1from ^ m1to ^ m2from;
+ Piece piece = pos.piece_on(m1from);
// The moved piece attacks the square 'tto' ?
- if (pos.attacks_from(piece, mto, occ) & tto)
+ if (pos.attacks_from(piece, m1to, occ) & m2to)
return true;
// Scan for possible X-ray attackers behind the moved piece
- Bitboard xray = (attacks_bb< ROOK>(tto, occ) & pos.pieces(color_of(piece), QUEEN, ROOK))
- | (attacks_bb<BISHOP>(tto, occ) & pos.pieces(color_of(piece), QUEEN, BISHOP));
+ Bitboard xray = (attacks_bb< ROOK>(m2to, occ) & pos.pieces(color_of(piece), QUEEN, ROOK))
+ | (attacks_bb<BISHOP>(m2to, occ) & pos.pieces(color_of(piece), QUEEN, BISHOP));
// Verify attackers are triggered by our move and not already existing
- if (xray && (xray ^ (xray & pos.attacks_from<QUEEN>(tto))))
+ if (xray && (xray ^ (xray & pos.attacks_from<QUEEN>(m2to))))
return true;
}
// Don't prune safe moves which block the threat path
- if ((between_bb(tfrom, tto) & mto) && pos.see_sign(move) >= 0)
+ if ((between_bb(m2from, m2to) & m1to) && pos.see_sign(first) >= 0)
return true;
return false;
do {
pv.push_back(m);
- assert(pos.move_is_legal(pv[ply]));
+ assert(MoveList<LEGAL>(pos).contains(pv[ply]));
+
pos.do_move(pv[ply++], *st++);
tte = TT.probe(pos.key());
tte = TT.probe(pos.key());
if (!tte || tte->move() != pv[ply]) // Don't overwrite correct entries
- TT.store(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE, pv[ply]);
+ TT.store(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE, pv[ply], VALUE_NONE, VALUE_NONE);
+
+ assert(MoveList<LEGAL>(pos).contains(pv[ply]));
- assert(pos.move_is_legal(pv[ply]));
pos.do_move(pv[ply++], *st++);
} while (pv[ply] != MOVE_NONE);