X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=47c89ed4c076c73d6be4647ba1cd16f960438cec;hp=ea0dffc72ba34c738537cedd18f6e3797540407c;hb=5935daf8a5b6925a6af2084f87e3831b3bb17dac;hpb=d2274e609c28e46a24deee55b05684197d369976 diff --git a/src/pawns.cpp b/src/pawns.cpp index ea0dffc7..47c89ed4 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) 2015-2018 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 @@ -35,9 +35,10 @@ namespace { constexpr Score Backward = S( 9, 24); constexpr Score Doubled = S(11, 56); constexpr Score Isolated = S( 5, 15); + constexpr Score WeakUnopposed = S( 13, 27); - // Connected pawn bonus by opposed, phalanx, #support and rank - Score Connected[2][2][3][RANK_NB]; + // 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. @@ -67,7 +68,7 @@ namespace { constexpr Color Them = (Us == WHITE ? BLACK : WHITE); constexpr Direction Up = (Us == WHITE ? NORTH : SOUTH); - Bitboard b, neighbours, stoppers, doubled, supported, phalanx; + Bitboard b, neighbours, stoppers, doubled, support, phalanx; Bitboard lever, leverPush; Square s; bool opposed, backward; @@ -77,12 +78,9 @@ namespace { Bitboard ourPawns = pos.pieces( Us, PAWN); Bitboard theirPawns = pos.pieces(Them, PAWN); - e->passedPawns[Us] = e->pawnAttacksSpan[Us] = e->weakUnopposed[Us] = 0; - e->semiopenFiles[Us] = 0xFF; + e->passedPawns[Us] = e->pawnAttacksSpan[Us] = 0; e->kingSquares[Us] = SQ_NONE; 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]; // Loop through all pawns of the current color and score each pawn while ((s = *pl++) != SQ_NONE) @@ -90,19 +88,19 @@ namespace { 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_file_bb(Us, s); - stoppers = theirPawns & passed_pawn_mask(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); phalanx = neighbours & rank_bb(s); - supported = neighbours & rank_bb(s - Up); + support = neighbours & rank_bb(s - Up); // A pawn is backward when it is behind all pawns of the same color // on the adjacent files and cannot be safely advanced. @@ -114,30 +112,33 @@ namespace { // which could become passed after one or two pawn pushes when are // not attacked more times than defended. if ( !(stoppers ^ lever ^ leverPush) - && popcount(supported) >= popcount(lever) - 1 - && popcount(phalanx) >= popcount(leverPush)) + && (support || !more_than_one(lever)) + && popcount(phalanx) >= popcount(leverPush)) e->passedPawns[Us] |= s; - else if ( stoppers == SquareBB[s + Up] - && relative_rank(Us, s) >= RANK_5) + else if (stoppers == square_bb(s + Up) && r >= RANK_5) { - b = shift(supported) & ~theirPawns; + b = shift(support) & ~theirPawns; while (b) if (!more_than_one(theirPawns & PawnAttacks[Us][pop_lsb(&b)])) e->passedPawns[Us] |= s; } // Score this pawn - if (supported | phalanx) - score += Connected[opposed][bool(phalanx)][popcount(supported)][relative_rank(Us, s)]; + if (support | phalanx) + { + int v = Connected[r] * (phalanx ? 3 : 2) / (opposed ? 2 : 1) + + 17 * popcount(support); + score += make_score(v, v * (r - 2) / 4); + } else if (!neighbours) - score -= Isolated, e->weakUnopposed[Us] += !opposed; + score -= Isolated + WeakUnopposed * int(!opposed); else if (backward) - score -= Backward, e->weakUnopposed[Us] += !opposed; + score -= Backward + WeakUnopposed * int(!opposed); - if (doubled && !supported) + if (doubled && !support) score -= Doubled; } @@ -148,27 +149,6 @@ 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 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 support = 0; support <= 2; ++support) - for (Rank r = RANK_2; r < RANK_8; ++r) - { - 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); - } -} - - /// 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 @@ -185,9 +165,6 @@ Entry* probe(const Position& pos) { e->key = key; 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; } @@ -197,35 +174,40 @@ Entry* probe(const Position& pos) { /// penalty for a king, looking at the king file and the two closest files. template -Value Entry::evaluate_shelter(const Position& pos, Square ksq) { +void Entry::evaluate_shelter(const Position& pos, Square ksq, Score& shelter) { constexpr Color Them = (Us == WHITE ? BLACK : WHITE); constexpr Direction Down = (Us == WHITE ? SOUTH : NORTH); - constexpr Bitboard BlockRanks = (Us == WHITE ? Rank1BB | Rank2BB : Rank8BB | Rank7BB); + constexpr Bitboard BlockSquares = (Rank1BB | Rank2BB | Rank7BB | Rank8BB) + & (FileABB | FileHBB); Bitboard b = pos.pieces(PAWN) & ~forward_ranks_bb(Them, ksq); Bitboard ourPawns = b & pos.pieces(Us); Bitboard theirPawns = b & pos.pieces(Them); - Value safety = (shift(theirPawns) & (FileABB | FileHBB) & BlockRanks & ksq) ? - Value(374) : Value(5); + Value bonus[] = { (shift(theirPawns) & BlockSquares & ksq) ? Value(374) : Value(5), + VALUE_ZERO }; - File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq))); + 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); - int ourRank = b ? relative_rank(Us, backmost_sq(Us, b)) : 0; + Rank ourRank = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1; b = theirPawns & file_bb(f); - int theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : 0; + Rank theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1; int d = std::min(f, ~f); - safety += ShelterStrength[d][ourRank]; - safety -= (ourRank && (ourRank == theirRank - 1)) ? 66 * (theirRank == RANK_3) - : UnblockedStorm[d][theirRank]; + bonus[MG] += ShelterStrength[d][ourRank]; + + if (ourRank && (ourRank == theirRank - 1)) + bonus[MG] -= 82 * (theirRank == RANK_3), bonus[EG] -= 82 * (theirRank == RANK_3); + else + bonus[MG] -= UnblockedStorm[d][theirRank]; } - return safety; + if (bonus[MG] > mg_value(shelter)) + shelter = make_score(bonus[MG], bonus[EG]); } @@ -237,23 +219,28 @@ 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 = evaluate_shelter(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(Us | KING_SIDE)) - bonus = std::max(bonus, evaluate_shelter(pos, relative_square(Us, SQ_G1))); + evaluate_shelter(pos, relative_square(Us, SQ_G1), shelter); if (pos.can_castle(Us | QUEEN_SIDE)) - bonus = std::max(bonus, evaluate_shelter(pos, relative_square(Us, SQ_C1))); + 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