X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fevaluate.cpp;h=fe964935c828282490b53a3927cc18c471f263d1;hp=e167bb6994f788ec4a81ae12b236d34b78d371c8;hb=3bb1ab34e4f007549fe9836aa167654f8fef39e6;hpb=85a7456bd7e8a1a01cdbfa8f4b6fb563d15a37c6 diff --git a/src/evaluate.cpp b/src/evaluate.cpp index e167bb69..fe964935 100644 --- a/src/evaluate.cpp +++ b/src/evaluate.cpp @@ -168,6 +168,11 @@ namespace { // right to castle. const Value TrappedRookPenalty = Value(180); + // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by + // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only + // happen in Chess960 games. + const Score TrappedBishopA1H1Penalty = make_score(100, 100); + // The SpaceMask[Color] contains the area of the board which is considered // by the space evaluation. In the middle game, each side is given a bonus // based on how many squares inside this area are safe and available for @@ -230,7 +235,7 @@ namespace { Score evaluate_pieces_of_color(const Position& pos, EvalInfo& ei, Score& mobility); template - Score evaluate_king(const Position& pos, EvalInfo& ei, Value& margin); + Score evaluate_king(const Position& pos, EvalInfo& ei, Value margins[]); template Score evaluate_threats(const Position& pos, EvalInfo& ei); @@ -241,6 +246,9 @@ namespace { template Score evaluate_passed_pawns(const Position& pos, EvalInfo& ei); + template + Score evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei); + inline Score apply_weight(Score v, Score weight); Value scale_by_game_phase(const Score& v, Phase ph, ScaleFactor sf); Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight); @@ -276,6 +284,7 @@ template Value do_evaluate(const Position& pos, Value& margin) { EvalInfo ei; + Value margins[2]; Score mobilityWhite, mobilityBlack; assert(pos.is_ok()); @@ -286,9 +295,9 @@ Value do_evaluate(const Position& pos, Value& margin) { // in the position object (material + piece square tables). Score bonus = pos.value(); - // margin is the uncertainty estimation of position's evaluation - // and typically is used by the search for pruning decisions. - margin = VALUE_ZERO; + // margins[] store the uncertainty estimation of position's evaluation + // that typically is used by the search for pruning decisions. + margins[WHITE] = margins[BLACK] = VALUE_ZERO; // Probe the material hash table MaterialInfo* mi = MaterialTable[pos.thread()]->get_material_info(pos); @@ -297,7 +306,10 @@ Value do_evaluate(const Position& pos, Value& margin) { // If we have a specialized evaluation function for the current material // configuration, call it and return. if (mi->specialized_eval_exists()) + { + margin = VALUE_ZERO; return mi->evaluate(pos); + } // Probe the pawn hash table ei.pi = PawnTable[pos.thread()]->get_pawn_info(pos); @@ -315,8 +327,8 @@ Value do_evaluate(const Position& pos, Value& margin) { // Evaluate kings after all other pieces because we need complete attack // information when computing the king safety evaluation. - bonus += evaluate_king(pos, ei, margin) - - evaluate_king(pos, ei, margin); + bonus += evaluate_king(pos, ei, margins) + - evaluate_king(pos, ei, margins); // Evaluate tactical threats, we need full attack information including king bonus += evaluate_threats(pos, ei) @@ -326,6 +338,10 @@ Value do_evaluate(const Position& pos, Value& margin) { bonus += evaluate_passed_pawns(pos, ei) - evaluate_passed_pawns(pos, ei); + // If one side has only a king, check whether exists any unstoppable passed pawn + if (!pos.non_pawn_material(WHITE) || !pos.non_pawn_material(BLACK)) + bonus += evaluate_unstoppable_pawns(pos, ei); + // Evaluate space for both sides, only in middle-game. if (mi->space_weight()) { @@ -360,6 +376,7 @@ Value do_evaluate(const Position& pos, Value& margin) { } // Interpolate between the middle game and the endgame score + margin = margins[pos.side_to_move()]; Value v = scale_by_game_phase(bonus, phase, sf); return pos.side_to_move() == WHITE ? v : -v; } @@ -402,7 +419,7 @@ void quit_eval() { /// read_weights() reads evaluation weights from the corresponding UCI parameters -void read_weights(Color us) { +void read_evaluation_uci_options(Color us) { // King safety is asymmetrical. Our king danger level is weighted by // "Cowardice" UCI parameter, instead the opponent one by "Aggressiveness". @@ -418,7 +435,7 @@ void read_weights(Color us) { // If running in analysis mode, make sure we use symmetrical king safety. We do this // by replacing both Weights[kingDangerUs] and Weights[kingDangerThem] by their average. - if (get_option_value_bool("UCI_AnalyseMode")) + if (Options["UCI_AnalyseMode"].value()) Weights[kingDangerUs] = Weights[kingDangerThem] = (Weights[kingDangerUs] + Weights[kingDangerThem]) / 2; init_safety(); @@ -544,6 +561,28 @@ namespace { bonus += (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus); } + // Special extra evaluation for bishops + if (Piece == BISHOP && pos.is_chess960()) + { + // An important Chess960 pattern: A cornered bishop blocked by + // a friendly pawn diagonally in front of it is a very serious + // problem, especially when that pawn is also blocked. + if (s == relative_square(Us, SQ_A1) || s == relative_square(Us, SQ_H1)) + { + SquareDelta d = pawn_push(Us) + + (square_file(s) == FILE_A ? DELTA_E : DELTA_W); + if (pos.piece_on(s + d) == piece_of_color_and_type(Us, PAWN)) + { + if (!pos.square_is_empty(s + d + pawn_push(Us))) + bonus -= 2*TrappedBishopA1H1Penalty; + else if (pos.piece_on(s + 2*d) == piece_of_color_and_type(Us, PAWN)) + bonus -= TrappedBishopA1H1Penalty; + else + bonus -= TrappedBishopA1H1Penalty / 2; + } + } + } + // Special extra evaluation for rooks if (Piece == ROOK) { @@ -650,7 +689,7 @@ namespace { // evaluate_king<>() assigns bonuses and penalties to a king of a given color template - Score evaluate_king(const Position& pos, EvalInfo& ei, Value& margin) { + Score evaluate_king(const Position& pos, EvalInfo& ei, Value margins[]) { const BitCountType Max15 = HasPopCnt ? CNT_POPCNT : CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15; const Color Them = (Us == WHITE ? BLACK : WHITE); @@ -751,8 +790,7 @@ namespace { // be very big, and so capturing a single attacking piece can therefore // result in a score change far bigger than the value of the captured piece. bonus -= KingDangerTable[Us][attackUnits]; - if (pos.side_to_move() == Us) - margin += mg_value(KingDangerTable[Us][attackUnits]); + margins[Us] += mg_value(KingDangerTable[Us][attackUnits]); } return bonus; } @@ -855,6 +893,168 @@ namespace { return apply_weight(bonus, Weights[PassedPawns]); } + // evaluate_unstoppable_pawns() evaluates the unstoppable passed pawns for both sides + template + Score evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei) { + + const BitCountType Max15 = HasPopCnt ? CNT_POPCNT : CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15; + + // Step 1. Hunt for unstoppable pawns. If we find at least one, record how many plies + // are required for promotion + int pliesToGo[2] = {256, 256}; + + for (Color c = WHITE; c <= BLACK; c++) + { + // Skip if other side has non-pawn pieces + if (pos.non_pawn_material(opposite_color(c))) + continue; + + Bitboard b = ei.pi->passed_pawns(c); + + while (b) + { + Square s = pop_1st_bit(&b); + Square queeningSquare = relative_square(c, make_square(square_file(s), RANK_8)); + + int mtg = RANK_8 - relative_rank(c, s) - int(relative_rank(c, s) == RANK_2); + int oppmtg = square_distance(pos.king_square(opposite_color(c)), queeningSquare) - int(c != pos.side_to_move()); + bool pathDefended = ((ei.attackedBy[c][0] & squares_in_front_of(c, s)) == squares_in_front_of(c, s)); + + if (mtg >= oppmtg && !pathDefended) + continue; + + int blockerCount = count_1s(squares_in_front_of(c, s) & pos.occupied_squares()); + mtg += blockerCount; + + if (mtg >= oppmtg && !pathDefended) + continue; + + int ptg = 2 * mtg - int(c == pos.side_to_move()); + + if (ptg < pliesToGo[c]) + pliesToGo[c] = ptg; + } + } + + // Step 2. If either side cannot promote at least three plies before the other side then + // situation becomes too complex and we give up. Otherwise we determine the possibly "winning side" + if (abs(pliesToGo[WHITE] - pliesToGo[BLACK]) < 3) + return make_score(0, 0); + + Color winnerSide = (pliesToGo[WHITE] < pliesToGo[BLACK] ? WHITE : BLACK); + Color loserSide = opposite_color(winnerSide); + + // Step 3. Can the losing side possibly create a new passed pawn and thus prevent the loss? + // We collect the potential candidates in potentialBB. + Bitboard pawnBB = pos.pieces(PAWN, loserSide); + Bitboard potentialBB = pawnBB; + const Bitboard passedBB = ei.pi->passed_pawns(loserSide); + + while(pawnBB) + { + Square psq = pop_1st_bit(&pawnBB); + + // Check direct advancement + int mtg = RANK_8 - relative_rank(loserSide, psq) - int(relative_rank(loserSide, psq) == RANK_2); + int ptg = 2 * mtg - int(loserSide == pos.side_to_move()); + + // Check if (without even considering any obstacles) we're too far away + if (pliesToGo[winnerSide] + 3 <= ptg) + { + clear_bit(&potentialBB, psq); + continue; + } + + // If this is passed pawn, then it _may_ promote in time. We give up. + if (bit_is_set(passedBB, psq)) + return make_score(0, 0); + + // Doubled pawn is worthless + if (squares_in_front_of(loserSide, psq) & (pos.pieces(PAWN, loserSide))) + { + clear_bit(&potentialBB, psq); + continue; + } + } + + // Step 4. Check new passed pawn creation through king capturing and sacrifises + pawnBB = potentialBB; + + while(pawnBB) + { + Square psq = pop_1st_bit(&pawnBB); + + int mtg = RANK_8 - relative_rank(loserSide, psq) - int(relative_rank(loserSide, psq) == RANK_2); + int ptg = 2 * mtg - int(loserSide == pos.side_to_move()); + + // Generate list of obstacles + Bitboard obsBB = passed_pawn_mask(loserSide, psq) & pos.pieces(PAWN, winnerSide); + const bool pawnIsOpposed = squares_in_front_of(loserSide, psq) & obsBB; + assert(obsBB); + + // How many plies does it take to remove all the obstacles? + int sacptg = 0; + int realObsCount = 0; + int minKingDist = 256; + + while(obsBB) + { + Square obSq = pop_1st_bit(&obsBB); + int minMoves = 256; + + // Check pawns that can give support to overcome obstacle (Eg. wp: a4,b4 bp: b2. b4 is giving support) + if (!pawnIsOpposed && square_file(psq) != square_file(obSq)) + { + Bitboard supBB = in_front_bb(winnerSide, Square(obSq + (winnerSide == WHITE ? 8 : -8))) + & neighboring_files_bb(psq) & potentialBB; + + while(supBB) // This while-loop could be replaced with supSq = LSB/MSB(supBB) (depending on color) + { + Square supSq = pop_1st_bit(&supBB); + int dist = square_distance(obSq, supSq); + minMoves = Min(minMoves, dist - 2); + } + + } + + // Check pawns that can be sacrifised + Bitboard sacBB = passed_pawn_mask(winnerSide, obSq) & neighboring_files_bb(obSq) & potentialBB & ~(1ULL << psq); + + while(sacBB) // This while-loop could be replaced with sacSq = LSB/MSB(sacBB) (depending on color) + { + Square sacSq = pop_1st_bit(&sacBB); + int dist = square_distance(obSq, sacSq); + minMoves = Min(minMoves, dist - 2); + } + + // If obstacle can be destroyed with immediate pawn sacrifise, it's not real obstacle + if (minMoves <= 0) + continue; + + // Pawn sac calculations + sacptg += minMoves * 2; + + // King capture calc + realObsCount++; + int kingDist = square_distance(pos.king_square(loserSide), obSq); + minKingDist = Min(minKingDist, kingDist); + } + + // Check if pawn sac plan _may_ save the day + if (pliesToGo[winnerSide] + 3 > ptg + sacptg) + return make_score(0, 0); + + // Check if king capture plan _may_ save the day (contains some false positives) + int kingptg = (minKingDist + realObsCount) * 2; + if (pliesToGo[winnerSide] + 3 > ptg + kingptg) + return make_score(0, 0); + } + + // Step 5. Assign bonus + const int Sign[2] = {1, -1}; + return Sign[winnerSide] * make_score(0, (Value) 0x500 - 0x20 * pliesToGo[winnerSide]); + } + // evaluate_space() computes the space evaluation for a given side. The // space evaluation is a simple bonus based on the number of safe squares @@ -916,8 +1116,8 @@ namespace { Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) { // Scale option value from 100 to 256 - int mg = get_option_value_int(mgOpt) * 256 / 100; - int eg = get_option_value_int(egOpt) * 256 / 100; + int mg = Options[mgOpt].value() * 256 / 100; + int eg = Options[egOpt].value() * 256 / 100; return apply_weight(make_score(mg, eg), internalWeight); }