X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=1131b5e81a77cc4a02fc2133ef2221ea97fdf873;hp=b8f82cff4a6718eae4813201191009330e9c30c9;hb=efd4ca27c4d7abad41e0469aa9b3b26b12068914;hpb=6d24ef8585c2ed5618eb9b4ab1d8ee35a05ce2cd diff --git a/src/pawns.cpp b/src/pawns.cpp index b8f82cff..1131b5e8 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) 2015-2018 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 @@ -31,61 +31,36 @@ 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) - }; - - // 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) } + // Pawn penalties + constexpr Score Isolated = S( 4, 20); + constexpr Score Backward = S(21, 22); + constexpr Score Doubled = S(12, 54); + + // Connected pawn bonus by opposed, phalanx, #support and rank + Score Connected[2][2][3][RANK_NB]; + + // 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( 16), V(82), V( 83), V( 47), V( 19), V( 44), V( 4) }, + { V(-51), V(56), V( 33), V(-58), V(-57), V(-50), V(-39) }, + { V(-20), V(71), V( 16), V(-10), V( 13), V( 19), V(-30) }, + { V(-29), V(12), V(-21), V(-40), V(-15), V(-77), V(-91) } }; - // 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) } } + // 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. + constexpr Value UnblockedStorm[int(FILE_NB) / 2][RANK_NB] = { + { V(54), V( 48), V( 99), V(91), V(42), V( 32), V( 31) }, + { V(34), V( 27), V(105), V(38), V(32), V(-19), V( 3) }, + { V(-4), V( 28), V( 87), V(18), V(-3), V(-14), V(-11) }, + { V(-5), V( 22), V( 75), V(14), V( 2), V( -5), V(-19) } }; - // 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); + // Danger of blocked enemy pawns storming our king, by rank + constexpr Value BlockedStorm[RANK_NB] = + { V(0), V(0), V( 81), V(-9), V(-5), V(-1), V(26) }; #undef S #undef V @@ -93,13 +68,11 @@ namespace { 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 lever, leverPush; Square s; bool opposed, backward; Score score = SCORE_ZERO; @@ -108,10 +81,10 @@ namespace { Bitboard ourPawns = pos.pieces( Us, PAWN); Bitboard theirPawns = pos.pieces(Them, PAWN); - e->passedPawns[Us] = e->pawnAttacksSpan[Us] = 0; + e->passedPawns[Us] = e->pawnAttacksSpan[Us] = e->weakUnopposed[Us] = 0; e->semiopenFiles[Us] = 0xFF; e->kingSquares[Us] = SQ_NONE; - e->pawnAttacks[Us] = shift(ourPawns) | shift(ourPawns); + e->pawnAttacks[Us] = pawn_attacks_bb(ourPawns); e->pawnsOnSquares[Us][BLACK] = popcount(ourPawns & DarkSquares); e->pawnsOnSquares[Us][WHITE] = pos.count(Us) - e->pawnsOnSquares[Us][BLACK]; @@ -134,24 +107,11 @@ namespace { neighbours = ourPawns & adjacent_files_bb(f); 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; - - 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 @@ -159,7 +119,7 @@ namespace { // not attacked more times than defended. if ( !(stoppers ^ lever ^ leverPush) && !(ourPawns & forward_file_bb(Us, s)) - && popcount(supported) >= popcount(lever) + && popcount(supported) >= popcount(lever) - 1 && popcount(phalanx) >= popcount(leverPush)) e->passedPawns[Us] |= s; @@ -173,23 +133,17 @@ namespace { } // Score this pawn - if (!neighbours) - score -= Isolated[opposed]; + if (supported | phalanx) + score += Connected[opposed][bool(phalanx)][popcount(supported)][relative_rank(Us, s)]; - else if (backward) - score -= Backward[opposed]; + else if (!neighbours) + score -= Isolated, e->weakUnopposed[Us] += !opposed; - else if (!supported) - score -= Unsupported; - - if (connected) - score += Connected[opposed][!!phalanx][more_than_one(supported)][relative_rank(Us, s)]; + else if (backward) + score -= Backward, e->weakUnopposed[Us] += !opposed; if (doubled && !supported) score -= Doubled; - - if (lever) - score += Lever[relative_rank(Us, s)]; } return score; @@ -205,16 +159,17 @@ namespace Pawns { void init() { - static const int Seed[RANK_NB] = { 0, 8, 19, 13, 71, 94, 169, 324 }; + static constexpr int Seed[RANK_NB] = { 0, 13, 24, 18, 65, 100, 175, 330 }; for (int opposed = 0; opposed <= 1; ++opposed) for (int phalanx = 0; phalanx <= 1; ++phalanx) - for (int apex = 0; apex <= 1; ++apex) + for (int support = 0; support <= 2; ++support) 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); + int v = 17 * support; + v += (Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0)) >> opposed; + + Connected[opposed][phalanx][support][r] = make_score(v, v * (r - 2) / 4); } } @@ -233,44 +188,48 @@ 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->scores[WHITE] = evaluate(pos, e); + e->scores[BLACK] = evaluate(pos, e); e->openFiles = popcount(e->semiopenFiles[WHITE] & e->semiopenFiles[BLACK]); + e->asymmetry = popcount( (e->passedPawns[WHITE] | e->passedPawns[BLACK]) + | (e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK])); + 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); +Value Entry::evaluate_shelter(const Position& pos, Square ksq) { - enum { BlockedByKing, Unopposed, BlockedByPawn, Unblocked }; + constexpr Color Them = (Us == WHITE ? BLACK : WHITE); + constexpr Direction Down = (Us == WHITE ? SOUTH : NORTH); + constexpr Bitboard BlockRanks = (Us == WHITE ? Rank1BB | Rank2BB : Rank8BB | Rank7BB); Bitboard b = pos.pieces(PAWN) & (forward_ranks_bb(Us, ksq) | rank_bb(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) + Value safety = (ourPawns & file_bb(ksq)) ? Value(5) : Value(-5); + + if (shift(theirPawns) & (FileABB | FileHBB) & BlockRanks & ksq) + safety += Value(374); + + File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq))); + 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; + int ourRank = b ? relative_rank(Us, backmost_sq(Us, b)) : 0; 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]; + int theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : 0; + + int d = std::min(f, ~f); + safety += ShelterStrength[d][ourRank]; + safety -= (ourRank && (ourRank == theirRank - 1)) ? BlockedStorm[theirRank] + : UnblockedStorm[d][theirRank]; } return safety; @@ -291,14 +250,14 @@ Score Entry::do_king_safety(const Position& pos, Square ksq) { if (pawns) while (!(DistanceRingBB[ksq][minKingPawnDistance++] & pawns)) {} - Value bonus = shelter_storm(pos, ksq); + Value bonus = evaluate_shelter(pos, ksq); // 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))); + bonus = std::max(bonus, evaluate_shelter(pos, relative_square(Us, SQ_G1))); if (pos.can_castle(MakeCastling::right)) - bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_C1))); + bonus = std::max(bonus, evaluate_shelter(pos, relative_square(Us, SQ_C1))); return make_score(bonus, -16 * minKingPawnDistance); }