X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=79046ad2007aedbc13ab8315b1805adc65a67ef9;hp=ed8aa777bee172e77be003d7770994d7cb7b1088;hb=a5ea3a202eacff75f97e866f51da3f703359eb89;hpb=fe1cbe26383085a44809d56493d29ce9c1815aa8 diff --git a/src/search.cpp b/src/search.cpp index ed8aa777..79046ad2 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -62,10 +62,6 @@ namespace { // 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)); } @@ -96,15 +92,15 @@ 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); 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 { @@ -222,7 +218,7 @@ void Search::think() { 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] @@ -394,8 +390,9 @@ namespace { } // Sort the PV lines searched so far and update the GUI - sort(RootMoves.begin(), RootMoves.begin() + PVIdx); - sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl; + sort(RootMoves.begin(), RootMoves.begin() + PVIdx + 1); + if (PVIdx + 1 == PVSize || Time::now() - SearchTime > 3000) + sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl; } // Do we need to pick now the sub-optimal best move ? @@ -577,31 +574,21 @@ namespace { // Step 5. Evaluate the position statically and update parent's gain statistics if (inCheck) ss->staticEval = ss->evalMargin = eval = VALUE_NONE; - - else if (tte) + else { - // Following asserts are valid only in single thread condition because - // TT access is always racy and its contents cannot be trusted. - assert(tte->static_value() != VALUE_NONE || Threads.size() > 1); - assert(ttValue != VALUE_NONE || tte->type() == BOUND_NONE || Threads.size() > 1); - - ss->staticEval = eval = tte->static_value(); - ss->evalMargin = tte->static_value_margin(); - - if (eval == VALUE_NONE || ss->evalMargin == VALUE_NONE) // Due to a race - eval = ss->staticEval = evaluate(pos, ss->evalMargin); + eval = ss->staticEval = evaluate(pos, ss->evalMargin); // Can ttValue be used as a better position evaluation? - if (ttValue != VALUE_NONE) + if (tte && 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); + } + + if (!tte) + 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 @@ -626,7 +613,7 @@ 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 +652,7 @@ 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 +687,7 @@ 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; } } @@ -797,7 +784,7 @@ split_point_start: // At split points actual search starts from here { Signals.firstRootMove = (moveCount == 1); - if (thisThread == Threads.main_thread() && Time::now() - SearchTime > 2000) + if (thisThread == Threads.main_thread() && Time::now() - SearchTime > 3000) sync_cout << "info depth " << depth / ONE_PLY << " currmove " << move_to_uci(move, pos.is_chess960()) << " currmovenumber " << moveCount + PVIdx << sync_endl; @@ -861,7 +848,7 @@ split_point_start: // At split points actual search starts from here // 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(); @@ -896,7 +883,7 @@ split_point_start: // At split points actual search starts from here } // Check for legality only before to do the move - if (!pos.pl_move_is_legal(move, ci.pinned)) + if (!RootNode && !SpNode && !pos.pl_move_is_legal(move, ci.pinned)) { moveCount--; continue; @@ -935,7 +922,9 @@ 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 +932,10 @@ 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); @@ -1004,8 +994,10 @@ split_point_start: // At split points actual search starts from here alpha = value; // Update alpha here! Always alpha < beta if (SpNode) sp->alpha = value; } - else // Fail high + else { + assert(value >= beta); // Fail high + if (SpNode) sp->cutoff = true; break; } @@ -1020,7 +1012,8 @@ split_point_start: // At split points actual search starts from here { bestValue = Threads.split(pos, ss, alpha, beta, bestValue, &bestMove, depth, threatMove, moveCount, mp, NT); - break; + if (bestValue >= beta) + break; } } @@ -1086,12 +1079,13 @@ 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); @@ -1100,11 +1094,14 @@ split_point_start: // At split points actual search starts from here const TTEntry* tte; Key posKey; Move ttMove, move, bestMove; - Value bestValue, value, ttValue, futilityValue, futilityBase; - bool inCheck, givesCheck, enoughMaterial, evasionPrunable; + Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha; + bool givesCheck, enoughMaterial, evasionPrunable; Depth ttDepth; - inCheck = pos.in_check(); + // 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; @@ -1122,7 +1119,7 @@ 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 +1133,7 @@ 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; @@ -1144,18 +1141,7 @@ split_point_start: // At split points actual search starts from here } else { - if (tte) - { - assert(tte->static_value() != VALUE_NONE || Threads.size() > 1); - - ss->staticEval = bestValue = tte->static_value(); - ss->evalMargin = tte->static_value_margin(); - - if (ss->staticEval == VALUE_NONE || ss->evalMargin == VALUE_NONE) // Due to a race - ss->staticEval = bestValue = evaluate(pos, ss->evalMargin); - } - else - ss->staticEval = bestValue = evaluate(pos, ss->evalMargin); + ss->staticEval = bestValue = evaluate(pos, ss->evalMargin); // Stand pat. Return immediately if static value is at least beta if (bestValue >= beta) @@ -1190,7 +1176,7 @@ split_point_start: // At split points actual search starts from here // Futility pruning if ( !PvNode - && !inCheck + && !InCheck && !givesCheck && move != ttMove && enoughMaterial @@ -1203,9 +1189,7 @@ split_point_start: // At split points actual search starts from here if (futilityValue < beta) { - if (futilityValue > bestValue) - bestValue = futilityValue; - + bestValue = std::max(bestValue, futilityValue); continue; } @@ -1213,19 +1197,22 @@ split_point_start: // At split points actual search starts from here if ( futilityBase < beta && depth < DEPTH_ZERO && pos.see(move) <= 0) + { + bestValue = std::max(bestValue, futilityBase); continue; + } } // 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 +1220,7 @@ 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 +1236,8 @@ 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); @@ -1279,11 +1267,11 @@ 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), - 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); @@ -1353,75 +1341,68 @@ 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(m1)); - assert(is_ok(m2)); + assert(is_ok(move)); + assert(is_ok(threat)); + assert(color_of(pos.piece_on(from_sq(threat))) == ~pos.side_to_move()); - // Case 1: The moving piece is the same in both moves - f2 = from_sq(m2); - t1 = to_sq(m1); - if (f2 == t1) - return true; + Square mfrom = from_sq(move); + Square mto = to_sq(move); + Square tfrom = from_sq(threat); + Square tto = to_sq(threat); - // 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 (mto == tfrom || tto == mfrom) 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(tfrom, tto) & mfrom) 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 matt = pos.attacks_from(pos.piece_on(mto), mto, pos.pieces() ^ tfrom); + if (matt & tto) 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 (matt & pos.king_square(pos.side_to_move())) + { + assert(between_bb(mto, pos.king_square(pos.side_to_move())) & tfrom); return true; + } return false; } - // 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)) @@ -1443,11 +1424,8 @@ split_point_start: // At split points actual search starts from here 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;