X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=eda5ebc3f285ba02ebd53aea3d8c82a739da9f7f;hp=2b51a698b0de3e40c8208255251a92fc0149faf0;hb=d0d69a53584397085b9936e0b373347b70a86531;hpb=4e31c39a6494499ba85db0e0014bbbaac9770b1d diff --git a/src/search.cpp b/src/search.cpp index 2b51a698..eda5ebc3 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -96,12 +96,12 @@ namespace { template Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth); - template + template 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 connected_moves(const Position& pos, Move m1, Move m2); + 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); @@ -394,7 +394,7 @@ namespace { } // Sort the PV lines searched so far and update the GUI - sort(RootMoves.begin(), RootMoves.begin() + PVIdx); + sort(RootMoves.begin(), RootMoves.begin() + PVIdx + 1); sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl; } @@ -626,7 +626,7 @@ namespace { && !pos.pawn_on_7th(pos.side_to_move())) { Value rbeta = beta - razor_margin(depth); - Value v = qsearch(pos, ss, rbeta-1, rbeta, DEPTH_ZERO); + Value v = qsearch(pos, ss, rbeta-1, rbeta, DEPTH_ZERO); if (v < rbeta) // Logically we should return (v + razor_margin(depth)), but // surprisingly this did slightly weaker in tests. @@ -665,7 +665,7 @@ namespace { pos.do_null_move(st); (ss+1)->skipNullMove = true; - nullValue = depth-R < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + nullValue = depth-R < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) : - search(pos, ss+1, -beta, -alpha, depth-R); (ss+1)->skipNullMove = false; pos.do_null_move(st); @@ -700,7 +700,7 @@ namespace { if ( depth < 5 * ONE_PLY && (ss-1)->reduction && threatMove != MOVE_NONE - && connected_moves(pos, (ss-1)->currentMove, threatMove)) + && yields_to_threat(pos, (ss-1)->currentMove, threatMove)) return beta - 1; } } @@ -935,7 +935,9 @@ split_point_start: // At split points actual search starts from here if (doFullDepthSearch) { alpha = SpNode ? sp->alpha : alpha; - value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) + value = newDepth < ONE_PLY ? + givesCheck ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) + : -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) : - search(pos, ss+1, -(alpha+1), -alpha, newDepth); } @@ -943,9 +945,10 @@ split_point_start: // At split points actual search starts from here // high, in the latter case search only if value < beta, otherwise let the // parent node to fail low with value <= alpha and to try another move. if (PvNode && (pvMove || (value > alpha && (RootNode || value < beta)))) - value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + value = newDepth < ONE_PLY ? + givesCheck ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + : -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) : - search(pos, ss+1, -beta, -alpha, newDepth); - // Step 17. Undo move pos.undo_move(move); @@ -1086,12 +1089,13 @@ split_point_start: // At split points actual search starts from here // search function when the remaining depth is zero (or, to be more precise, // less than ONE_PLY). - template + template Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) { const bool PvNode = (NT == PV); assert(NT == PV || NT == NonPV); + assert(InCheck == pos.in_check()); assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE); assert(PvNode || (alpha == beta - 1)); assert(depth <= DEPTH_ZERO); @@ -1101,10 +1105,9 @@ split_point_start: // At split points actual search starts from here Key posKey; Move ttMove, move, bestMove; Value bestValue, value, ttValue, futilityValue, futilityBase; - bool inCheck, givesCheck, enoughMaterial, evasionPrunable; + bool givesCheck, enoughMaterial, evasionPrunable; Depth ttDepth; - inCheck = pos.in_check(); ss->currentMove = bestMove = MOVE_NONE; ss->ply = (ss-1)->ply + 1; @@ -1122,7 +1125,7 @@ split_point_start: // At split points actual search starts from here // 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 = InCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS; if ( tte && tte->depth() >= ttDepth @@ -1136,7 +1139,7 @@ split_point_start: // At split points actual search starts from here } // Evaluate the position statically - if (inCheck) + if (InCheck) { ss->staticEval = ss->evalMargin = VALUE_NONE; bestValue = futilityBase = -VALUE_INFINITE; @@ -1190,7 +1193,7 @@ split_point_start: // At split points actual search starts from here // Futility pruning if ( !PvNode - && !inCheck + && !InCheck && !givesCheck && move != ttMove && enoughMaterial @@ -1218,14 +1221,14 @@ split_point_start: // At split points actual search starts from here // Detect non-capture evasions that are candidate to be pruned evasionPrunable = !PvNode - && inCheck + && InCheck && bestValue > VALUE_MATED_IN_MAX_PLY && !pos.is_capture(move) && !pos.can_castle(pos.side_to_move()); // Don't search moves with negative SEE values if ( !PvNode - && (!inCheck || evasionPrunable) + && (!InCheck || evasionPrunable) && move != ttMove && type_of(move) != PROMOTION && pos.see_sign(move) < 0) @@ -1233,7 +1236,7 @@ split_point_start: // At split points actual search starts from here // Don't search useless checks if ( !PvNode - && !inCheck + && !InCheck && givesCheck && move != ttMove && !pos.is_capture_or_promotion(move) @@ -1249,7 +1252,8 @@ split_point_start: // At split points actual search starts from here // Make and search the move pos.do_move(move, st, ci, givesCheck); - value = -qsearch(pos, ss+1, -beta, -alpha, depth - ONE_PLY); + value = givesCheck ? -qsearch(pos, ss+1, -beta, -alpha, depth - ONE_PLY) + : -qsearch(pos, ss+1, -beta, -alpha, depth - ONE_PLY); pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); @@ -1279,7 +1283,7 @@ split_point_start: // At split points actual search starts from here // 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 (InCheck && bestValue == -VALUE_INFINITE) return mated_in(ss->ply); // Plies to mate from the root TT.store(posKey, value_to_tt(bestValue, ss->ply), @@ -1353,49 +1357,43 @@ split_point_start: // At split points actual search starts from here } - // connected_moves() tests whether two moves are 'connected' in the sense - // that the first move somehow made the second move possible (for instance - // if the moving piece is the same in both moves). The first move is assumed - // to be the move that was made to reach the current position, while the - // second move is assumed to be a move from the current position. + // 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. - bool connected_moves(const Position& pos, Move m1, Move m2) { + bool yields_to_threat(const Position& pos, Move move, Move threat) { - Square f1, t1, f2, t2; - Piece p1, p2; - Square ksq; + assert(is_ok(move)); + assert(is_ok(threat)); - assert(is_ok(m1)); - assert(is_ok(m2)); + Square t1 = to_sq(move); + Square f1 = from_sq(move); + Square t2 = to_sq(threat); + Square f2 = from_sq(threat); - // Case 1: The moving piece is the same in both moves - f2 = from_sq(m2); - t1 = to_sq(m1); - if (f2 == t1) - return true; + // We are suposed to be called upon returning from a null search + assert(color_of(pos.piece_on(f2)) == ~pos.side_to_move()); - // Case 2: The destination square for m2 was vacated by m1 - t2 = to_sq(m2); - f1 = from_sq(m1); - if (t2 == f1) + // The piece is the same or threat's destination was vacated by the move + if (t1 == f2 || t2 == f1) return true; - // Case 3: Moving through the vacated square - p2 = pos.piece_on(f2); - if (piece_is_slider(p2) && (between_bb(f2, t2) & f1)) + // Threat moves through the vacated square + if (between_bb(f2, t2) & f1) return true; - // Case 4: The destination square for m2 is defended by the moving piece in m1 - p1 = pos.piece_on(t1); - if (pos.attacks_from(p1, t1) & t2) + // 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) return true; - // Case 5: Discovered check, checking piece is the piece moved in m1 - ksq = pos.king_square(pos.side_to_move()); - if ( piece_is_slider(p1) - && (between_bb(t1, ksq) & f2) - && (pos.attacks_from(p1, t1, pos.pieces() ^ f2) & ksq)) + // Threat gives a discovered check through the move's checking piece + if (t1_att & pos.king_square(pos.side_to_move())) + { + assert(between_bb(t1, pos.king_square(pos.side_to_move())) & f2); return true; + } return false; } @@ -1426,8 +1424,8 @@ split_point_start: // At split points actual search starts from here && ( PieceValue[MG][pos.piece_on(tfrom)] >= PieceValue[MG][pos.piece_on(tto)] || type_of(pos.piece_on(tfrom)) == KING)) { - // Update occupancy as if the piece is moving - Bitboard occ = pos.pieces() ^ mfrom ^ mto; + // Update occupancy as if the piece and the threat are moving + Bitboard occ = pos.pieces() ^ mfrom ^ mto ^ tfrom; Piece piece = pos.piece_on(mfrom); // The moved piece attacks the square 'tto' ?