X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=acc3d77096dd10f79742c4be15e69d2baa76fa9c;hp=95d5fb4cfeb5af4da52552430224b3622470d3cc;hb=93349d0dbd22f063b39e6815c02835a4748fffbc;hpb=69ec09bd4b5bdf61f3f49f12d88224e1d656020c diff --git a/src/pawns.cpp b/src/pawns.cpp index 95d5fb4c..acc3d770 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -2,7 +2,7 @@ Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad - Copyright (C) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad + Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -31,163 +31,120 @@ namespace { #define V Value #define S(mg, eg) make_score(mg, eg) - // Isolated pawn penalty by opposed flag - const Score Isolated[] = { S(45, 40), S(30, 27) }; - - // Backward pawn penalty by opposed flag - const Score Backward[] = { S(56, 33), S(41, 19) }; - - // Unsupported pawn penalty for pawns which are neither isolated or backward - const Score Unsupported = S(17, 8); - - // Connected pawn bonus by opposed, phalanx, twice supported and rank - Score Connected[2][2][2][RANK_NB]; - - // Doubled pawn penalty - const Score Doubled = S(18, 38); - - // Lever bonus by rank - const Score Lever[RANK_NB] = { - S( 0, 0), S( 0, 0), S(0, 0), S(0, 0), - S(17, 16), S(33, 32), S(0, 0), S(0, 0) + // Pawn penalties + constexpr Score Backward = S( 9, 24); + constexpr Score Doubled = S(11, 56); + constexpr Score Isolated = S( 5, 15); + constexpr Score WeakUnopposed = S( 13, 27); + constexpr Score Attacked2Unsupported = S( 0, 20); + + // Connected pawn bonus + constexpr int Connected[RANK_NB] = { 0, 7, 8, 12, 29, 48, 86 }; + + // Strength of pawn shelter for our king by [distance from edge][rank]. + // RANK_1 = 0 is used for files where we have no pawn, or pawn is behind our king. + constexpr Value ShelterStrength[int(FILE_NB) / 2][RANK_NB] = { + { V( -6), V( 81), V( 93), V( 58), V( 39), V( 18), V( 25) }, + { V(-43), V( 61), V( 35), V(-49), V(-29), V(-11), V( -63) }, + { V(-10), V( 75), V( 23), V( -2), V( 32), V( 3), V( -45) }, + { V(-39), V(-13), V(-29), V(-52), V(-48), V(-67), V(-166) } }; - // Weakness of our pawn shelter in front of the king by [distance from edge][rank]. - // RANK_1 = 0 is used for files where we have no pawns or our pawn is behind our king. - const Value ShelterWeakness[][RANK_NB] = { - { V(100), V(20), V(10), V(46), V(82), V( 86), V( 98) }, - { V(116), V( 4), V(28), V(87), V(94), V(108), V(104) }, - { V(109), V( 1), V(59), V(87), V(62), V( 91), V(116) }, - { V( 75), V(12), V(43), V(59), V(90), V( 84), V(112) } + // Danger of enemy pawns moving toward our king by [distance from edge][rank]. + // RANK_1 = 0 is used for files where the enemy has no pawn, or their pawn + // is behind our king. + // [0][1-2] accommodate opponent pawn on edge (likely blocked by our king) + constexpr Value UnblockedStorm[int(FILE_NB) / 2][RANK_NB] = { + { V( 89), V(-285), V(-185), V(93), V(57), V( 45), V( 51) }, + { V( 44), V( -18), V( 123), V(46), V(39), V( -7), V( 23) }, + { V( 4), V( 52), V( 162), V(37), V( 7), V(-14), V( -2) }, + { V(-10), V( -14), V( 90), V(15), V( 2), V( -7), V(-16) } }; - // Danger of enemy pawns moving toward our king by [type][distance from edge][rank]. - // For the unopposed and unblocked cases, RANK_1 = 0 is used when opponent has no pawn - // on the given file, or their pawn is behind our king. - const Value StormDanger[][4][RANK_NB] = { - { { V( 0), V(-290), V(-274), V(57), V(41) }, //BlockedByKing - { V( 0), V( 60), V( 144), V(39), V(13) }, - { V( 0), V( 65), V( 141), V(41), V(34) }, - { V( 0), V( 53), V( 127), V(56), V(14) } }, - { { V( 4), V( 73), V( 132), V(46), V(31) }, //Unopposed - { V( 1), V( 64), V( 143), V(26), V(13) }, - { V( 1), V( 47), V( 110), V(44), V(24) }, - { V( 0), V( 72), V( 127), V(50), V(31) } }, - { { V( 0), V( 0), V( 79), V(23), V( 1) }, //BlockedByPawn - { V( 0), V( 0), V( 148), V(27), V( 2) }, - { V( 0), V( 0), V( 161), V(16), V( 1) }, - { V( 0), V( 0), V( 171), V(22), V(15) } }, - { { V(22), V( 45), V( 104), V(62), V( 6) }, //Unblocked - { V(31), V( 30), V( 99), V(39), V(19) }, - { V(23), V( 29), V( 96), V(41), V(15) }, - { V(21), V( 23), V( 116), V(41), V(15) } } - }; - - // Max bonus for king safety. Corresponds to start position with all the pawns - // in front of the king and no enemy pawn on the horizon. - const Value MaxSafetyBonus = V(258); - #undef S #undef V template Score evaluate(const Position& pos, Pawns::Entry* e) { - const Color Them = (Us == WHITE ? BLACK : WHITE); - const Square Up = (Us == WHITE ? NORTH : SOUTH); - const Square Right = (Us == WHITE ? NORTH_EAST : SOUTH_WEST); - const Square Left = (Us == WHITE ? NORTH_WEST : SOUTH_EAST); + constexpr Color Them = (Us == WHITE ? BLACK : WHITE); + constexpr Direction Up = (Us == WHITE ? NORTH : SOUTH); - Bitboard b, neighbours, stoppers, doubled, supported, phalanx; - Bitboard lever, leverPush, connected; + Bitboard b, neighbours, stoppers, doubled, support, phalanx; + Bitboard lever, leverPush; Square s; bool opposed, backward; Score score = SCORE_ZERO; const Square* pl = pos.squares(Us); - Bitboard ourPawns = pos.pieces(Us , PAWN); + Bitboard ourPawns = pos.pieces( Us, PAWN); Bitboard theirPawns = pos.pieces(Them, PAWN); - e->passedPawns[Us] = e->pawnAttacksSpan[Us] = 0; - e->semiopenFiles[Us] = 0xFF; - e->kingSquares[Us] = SQ_NONE; - e->pawnAttacks[Us] = shift(ourPawns) | shift(ourPawns); - e->pawnsOnSquares[Us][BLACK] = popcount(ourPawns & DarkSquares); - e->pawnsOnSquares[Us][WHITE] = pos.count(Us) - e->pawnsOnSquares[Us][BLACK]; + e->passedPawns[Us] = e->pawnAttacksSpan[Us] = 0; + e->kingSquares[Us] = SQ_NONE; + e->pawnAttacks[Us] = pawn_attacks_bb(ourPawns); + + // Unsupported enemy pawns attacked twice by us + score += Attacked2Unsupported * popcount( theirPawns + & pawn_double_attacks_bb(ourPawns) + & ~pawn_attacks_bb(theirPawns)); // Loop through all pawns of the current color and score each pawn while ((s = *pl++) != SQ_NONE) { assert(pos.piece_on(s) == make_piece(Us, PAWN)); - File f = file_of(s); + Rank r = relative_rank(Us, s); - e->semiopenFiles[Us] &= ~(1 << f); e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s); // Flag the pawn - opposed = theirPawns & forward_bb(Us, s); - stoppers = theirPawns & passed_pawn_mask(Us, s); + opposed = theirPawns & forward_file_bb(Us, s); + stoppers = theirPawns & passed_pawn_span(Us, s); lever = theirPawns & PawnAttacks[Us][s]; leverPush = theirPawns & PawnAttacks[Us][s + Up]; doubled = ourPawns & (s - Up); - neighbours = ourPawns & adjacent_files_bb(f); + neighbours = ourPawns & adjacent_files_bb(s); phalanx = neighbours & rank_bb(s); - supported = neighbours & rank_bb(s - Up); - connected = supported | phalanx; - - // A pawn is backward when it is behind all pawns of the same color on the - // adjacent files and cannot be safely advanced. - if (!neighbours || lever || relative_rank(Us, s) >= RANK_5) - backward = false; - else - { - // Find the backmost rank with neighbours or stoppers - b = rank_bb(backmost_sq(Us, neighbours | stoppers)); - - // The pawn is backward when it cannot safely progress to that rank: - // either there is a stopper in the way on this rank, or there is a - // stopper on adjacent file which controls the way to that rank. - backward = (b | shift(b & adjacent_files_bb(f))) & stoppers; + support = neighbours & rank_bb(s - Up); - assert(!backward || !(pawn_attack_span(Them, s + Up) & neighbours)); - } + // A pawn is backward when it is behind all pawns of the same color + // on the adjacent files and cannot be safely advanced. + backward = !(ourPawns & pawn_attack_span(Them, s + Up)) + && (stoppers & (leverPush | (s + Up))); // Passed pawns will be properly scored in evaluation because we need // full attack info to evaluate them. Include also not passed pawns // which could become passed after one or two pawn pushes when are // not attacked more times than defended. - if ( !(stoppers ^ lever ^ leverPush) - && !(ourPawns & forward_bb(Us, s)) - && popcount(supported) >= popcount(lever) - && popcount(phalanx) >= popcount(leverPush)) + if ( !(stoppers ^ lever) || + (!(stoppers ^ leverPush) && popcount(phalanx) >= popcount(leverPush))) e->passedPawns[Us] |= s; - else if ( stoppers == SquareBB[s + Up] - && relative_rank(Us, s) >= RANK_5 - && (b = (shift(supported) & ~theirPawns))) - while(b) - if(!more_than_one(theirPawns & PawnAttacks[Us][pop_lsb(&b)])) + else if (stoppers == square_bb(s + Up) && r >= RANK_5) + { + b = shift(support) & ~theirPawns; + while (b) + if (!more_than_one(theirPawns & PawnAttacks[Us][pop_lsb(&b)])) e->passedPawns[Us] |= s; + } // Score this pawn - if (!neighbours) - score -= Isolated[opposed]; - - else if (backward) - score -= Backward[opposed]; - - else if (!supported) - score -= Unsupported; + if (support | phalanx) + { + int v = Connected[r] * (phalanx ? 3 : 2) / (opposed ? 2 : 1) + + 17 * popcount(support); - if (connected) - score += Connected[opposed][!!phalanx][more_than_one(supported)][relative_rank(Us, s)]; + score += make_score(v, v * (r - 2) / 4); + } + else if (!neighbours) + score -= Isolated + WeakUnopposed * int(!opposed); - if (doubled && !supported) - score -= Doubled; + else if (backward) + score -= Backward + WeakUnopposed * int(!opposed); - if (lever) - score += Lever[relative_rank(Us, s)]; + if (doubled && !support) + score -= Doubled; } return score; @@ -197,26 +154,6 @@ namespace { namespace Pawns { -/// Pawns::init() initializes some tables needed by evaluation. Instead of using -/// hard-coded tables, when makes sense, we prefer to calculate them with a formula -/// to reduce independent parameters and to allow easier tuning and better insight. - -void init() { - - static const int Seed[RANK_NB] = { 0, 8, 19, 13, 71, 94, 169, 324 }; - - for (int opposed = 0; opposed <= 1; ++opposed) - for (int phalanx = 0; phalanx <= 1; ++phalanx) - for (int apex = 0; apex <= 1; ++apex) - for (Rank r = RANK_2; r < RANK_8; ++r) - { - int v = (Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0)) >> opposed; - v += (apex ? v / 2 : 0); - Connected[opposed][phalanx][apex][r] = make_score(v, v * (r-2) / 4); - } -} - - /// Pawns::probe() looks up the current position's pawns configuration in /// the pawns hash table. It returns a pointer to the Entry if the position /// is found. Otherwise a new Entry is computed and stored there, so we don't @@ -231,47 +168,47 @@ Entry* probe(const Position& pos) { return e; e->key = key; - e->score = evaluate(pos, e) - evaluate(pos, e); - e->asymmetry = popcount(e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK]); - e->openFiles = popcount(e->semiopenFiles[WHITE] & e->semiopenFiles[BLACK]); + e->scores[WHITE] = evaluate(pos, e); + e->scores[BLACK] = evaluate(pos, e); + return e; } -/// Entry::shelter_storm() calculates shelter and storm penalties for the file -/// the king is on, as well as the two closest files. +/// Entry::evaluate_shelter() calculates the shelter bonus and the storm +/// penalty for a king, looking at the king file and the two closest files. template -Value Entry::shelter_storm(const Position& pos, Square ksq) { - - const Color Them = (Us == WHITE ? BLACK : WHITE); +void Entry::evaluate_shelter(const Position& pos, Square ksq, Score& shelter) { - enum { BlockedByKing, Unopposed, BlockedByPawn, Unblocked }; + constexpr Color Them = (Us == WHITE ? BLACK : WHITE); - Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, rank_of(ksq)) | rank_bb(ksq)); + Bitboard b = pos.pieces(PAWN) & ~forward_ranks_bb(Them, ksq); Bitboard ourPawns = b & pos.pieces(Us); Bitboard theirPawns = b & pos.pieces(Them); - Value safety = MaxSafetyBonus; - File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq))); - for (File f = center - File(1); f <= center + File(1); ++f) + Score bonus = make_score(5, 5); + + File center = clamp(file_of(ksq), FILE_B, FILE_G); + for (File f = File(center - 1); f <= File(center + 1); ++f) { b = ourPawns & file_bb(f); - Rank rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1; - - b = theirPawns & file_bb(f); - Rank rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1; - - int d = std::min(f, FILE_H - f); - safety -= ShelterWeakness[d][rkUs] - + StormDanger - [f == file_of(ksq) && rkThem == relative_rank(Us, ksq) + 1 ? BlockedByKing : - rkUs == RANK_1 ? Unopposed : - rkThem == rkUs + 1 ? BlockedByPawn : Unblocked] - [d][rkThem]; + Rank ourRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1; + + b = theirPawns & file_bb(f); + Rank theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1; + + int d = std::min(f, ~f); + bonus += make_score(ShelterStrength[d][ourRank], 0); + + if (ourRank && (ourRank == theirRank - 1)) + bonus -= make_score(82 * (theirRank == RANK_3), 82 * (theirRank == RANK_3)); + else + bonus -= make_score(UnblockedStorm[d][theirRank], 0); } - return safety; + if (mg_value(bonus) > mg_value(shelter)) + shelter = bonus; } @@ -279,30 +216,36 @@ Value Entry::shelter_storm(const Position& pos, Square ksq) { /// when king square changes, which is about 20% of total king_safety() calls. template -Score Entry::do_king_safety(const Position& pos, Square ksq) { +Score Entry::do_king_safety(const Position& pos) { + Square ksq = pos.square(Us); kingSquares[Us] = ksq; - castlingRights[Us] = pos.can_castle(Us); - int minKingPawnDistance = 0; + castlingRights[Us] = pos.castling_rights(Us); Bitboard pawns = pos.pieces(Us, PAWN); - if (pawns) - while (!(DistanceRingBB[ksq][minKingPawnDistance++] & pawns)) {} + int minPawnDist = pawns ? 8 : 0; + + if (pawns & PseudoAttacks[KING][ksq]) + minPawnDist = 1; + + else while (pawns) + minPawnDist = std::min(minPawnDist, distance(ksq, pop_lsb(&pawns))); - Value bonus = shelter_storm(pos, ksq); + Score shelter = make_score(-VALUE_INFINITE, VALUE_ZERO); + evaluate_shelter(pos, ksq, shelter); // If we can castle use the bonus after the castling if it is bigger - if (pos.can_castle(MakeCastling::right)) - bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_G1))); + if (pos.can_castle(Us | KING_SIDE)) + evaluate_shelter(pos, relative_square(Us, SQ_G1), shelter); - if (pos.can_castle(MakeCastling::right)) - bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_C1))); + if (pos.can_castle(Us | QUEEN_SIDE)) + evaluate_shelter(pos, relative_square(Us, SQ_C1), shelter); - return make_score(bonus, -16 * minKingPawnDistance); + return shelter - make_score(VALUE_ZERO, 16 * minPawnDist); } // Explicit template instantiation -template Score Entry::do_king_safety(const Position& pos, Square ksq); -template Score Entry::do_king_safety(const Position& pos, Square ksq); +template Score Entry::do_king_safety(const Position& pos); +template Score Entry::do_king_safety(const Position& pos); } // namespace Pawns