// Different node types, used as template parameter
enum NodeType { Root, PV, NonPV, SplitPointRoot, SplitPointPV, SplitPointNonPV };
- // Lookup table to check if a Piece is a slider and its access function
- const bool Slidings[18] = { 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1 };
- inline bool piece_is_slider(Piece p) { return Slidings[p]; }
-
// Dynamic razoring margin based on depth
inline Value razor_margin(Depth d) { return Value(512 + 16 * int(d)); }
Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
void id_loop(Position& pos);
- bool check_is_dangerous(Position& pos, Move move, Value futilityBase, Value beta);
- bool yields_to_threat(const Position& pos, Move move, Move threat);
Value value_to_tt(Value v, int ply);
Value value_from_tt(Value v, int ply);
- bool connected_threat(const Position& pos, Move m, Move threat);
+ 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);
string uci_pv(const Position& pos, int depth, Value alpha, Value beta);
struct Skill {
if (Options["Use Search Log"])
{
Log log(Options["Search Log Filename"]);
- log << "\nSearching: " << RootPos.to_fen()
+ log << "\nSearching: " << RootPos.fen()
<< "\ninfinite: " << Limits.infinite
<< " ponder: " << Limits.ponder
<< " time: " << Limits.time[RootColor]
// Move count based pruning
if ( depth < 16 * ONE_PLY
&& moveCount >= FutilityMoveCounts[depth]
- && (!threatMove || !connected_threat(pos, move, threatMove)))
+ && (!threatMove || !prevents_threat(pos, move, threatMove)))
{
if (SpNode)
sp->mutex.lock();
{
bestValue = Threads.split<FakeSplit>(pos, ss, alpha, beta, bestValue, &bestMove,
depth, threatMove, moveCount, mp, NT);
- break;
+ if (bestValue >= beta)
+ break;
}
}
const TTEntry* tte;
Key posKey;
Move ttMove, move, bestMove;
- Value bestValue, value, ttValue, futilityValue, futilityBase;
- bool givesCheck, enoughMaterial, evasionPrunable;
+ Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha;
+ bool givesCheck, enoughMaterial, evasionPrunable, fromNull;
Depth ttDepth;
+ // To flag BOUND_EXACT a node with eval above alpha and no available moves
+ if (PvNode)
+ oldAlpha = alpha;
+
ss->currentMove = bestMove = MOVE_NONE;
ss->ply = (ss-1)->ply + 1;
+ fromNull = (ss-1)->currentMove == MOVE_NULL;
// Check for an instant draw or maximum ply reached
if (pos.is_draw<false, false>() || ss->ply > MAX_PLY)
}
else
{
- if (tte)
+ if (fromNull)
+ {
+ ss->staticEval = bestValue = -(ss-1)->staticEval;
+ ss->evalMargin = VALUE_ZERO;
+ }
+ else if (tte)
{
assert(tte->static_value() != VALUE_NONE || Threads.size() > 1);
if ( !PvNode
&& !InCheck
&& !givesCheck
+ && !fromNull
&& move != ttMove
&& enoughMaterial
&& type_of(move) != PROMOTION
return mated_in(ss->ply); // Plies to mate from the root
TT.store(posKey, value_to_tt(bestValue, ss->ply),
- PvNode && bestMove != MOVE_NONE ? BOUND_EXACT : BOUND_UPPER,
+ PvNode && bestValue > oldAlpha ? BOUND_EXACT : BOUND_UPPER,
ttDepth, bestMove, ss->staticEval, ss->evalMargin);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
assert(is_ok(move));
assert(is_ok(threat));
+ assert(color_of(pos.piece_on(from_sq(threat))) == ~pos.side_to_move());
- Square t1 = to_sq(move);
- Square f1 = from_sq(move);
- Square t2 = to_sq(threat);
- Square f2 = from_sq(threat);
-
- // We are suposed to be called upon returning from a null search
- assert(color_of(pos.piece_on(f2)) == ~pos.side_to_move());
+ Square mfrom = from_sq(move);
+ Square mto = to_sq(move);
+ Square tfrom = from_sq(threat);
+ Square tto = to_sq(threat);
// The piece is the same or threat's destination was vacated by the move
- if (t1 == f2 || t2 == f1)
+ if (mto == tfrom || tto == mfrom)
return true;
// Threat moves through the vacated square
- if (between_bb(f2, t2) & f1)
+ if (between_bb(tfrom, tto) & mfrom)
return true;
// Threat's destination is defended by the move's piece
- Bitboard t1_att = pos.attacks_from(pos.piece_on(t1), t1, pos.pieces() ^ f2);
- if (t1_att & t2)
+ Bitboard matt = pos.attacks_from(pos.piece_on(mto), mto, pos.pieces() ^ tfrom);
+ if (matt & tto)
return true;
// Threat gives a discovered check through the move's checking piece
- if (t1_att & pos.king_square(pos.side_to_move()))
+ if (matt & pos.king_square(pos.side_to_move()))
{
- assert(between_bb(t1, pos.king_square(pos.side_to_move())) & f2);
+ assert(between_bb(mto, pos.king_square(pos.side_to_move())) & tfrom);
return true;
}
}
- // connected_threat() tests whether it is safe to forward prune a move or if
- // is somehow connected to the threat move returned by null search.
+ // 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.
- bool connected_threat(const Position& pos, Move m, Move threat) {
+ bool prevents_threat(const Position& pos, Move move, Move threat) {
- assert(is_ok(m));
+ assert(is_ok(move));
assert(is_ok(threat));
- assert(!pos.is_capture_or_promotion(m));
- assert(!pos.is_passed_pawn_push(m));
+ assert(!pos.is_capture_or_promotion(move));
+ assert(!pos.is_passed_pawn_push(move));
- Square mfrom = from_sq(m);
- Square mto = to_sq(m);
+ Square mfrom = from_sq(move);
+ Square mto = to_sq(move);
Square tfrom = from_sq(threat);
Square tto = to_sq(threat);
- // Case 1: Don't prune moves which move the threatened piece
+ // Don't prune moves of the threatened piece
if (mfrom == tto)
return true;
- // Case 2: If the threatened piece has value less than or equal to the
- // value of the threatening piece, don't prune moves which defend it.
+ // 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))
return true;
}
- // Case 3: If the moving piece in the threatened move is a slider, don't
- // prune safe moves which block its ray.
- if ( piece_is_slider(pos.piece_on(tfrom))
- && (between_bb(tfrom, tto) & mto)
- && pos.see_sign(m) >= 0)
+ // Don't prune safe moves which block the threat path
+ if ((between_bb(tfrom, tto) & mto) && pos.see_sign(move) >= 0)
return true;
return false;
projects / stockfish / blobdiff