X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=04222a2aa4ee98544afd22d193850c5012fa5ba4;hp=02c584e61aa2edd28e17641dd8a8dd82571b6c08;hb=44f79bdf5a092c3acec0a8bf8f2c1440e5a9da90;hpb=d2d4e85f25061aacd65a8b458b79cad15b74a5bb diff --git a/src/pawns.cpp b/src/pawns.cpp index 02c584e6..04222a2a 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 @@ -32,36 +32,36 @@ namespace { #define S(mg, eg) make_score(mg, eg) // Pawn penalties - constexpr Score Isolated = S( 5, 15); - constexpr Score Backward = S(9, 24); - constexpr Score Doubled = S(11, 56); + constexpr Score Backward = S( 9, 24); + constexpr Score BlockedStorm = S(82, 82); + constexpr Score Doubled = S(11, 56); + constexpr Score Isolated = S( 5, 15); + constexpr Score WeakLever = S( 0, 56); + 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. - constexpr Value ShelterStrength[int(FILE_NB) / 2][RANK_NB] = { - { V( -3), V(81), V( 93), V( 58), V( 39), V( 18), V( 25) }, - { V(-40), V(61), V( 35), V(-49), V(-29), V(-11), V(-63) }, - { V(-7), V(75), V( 23), V(-2), V( 32), V( 3), V(-45) }, - { V(-36), V(-13), V(-29), V(-52), V(-48), V(-67), V(-166) } + 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) } }; // 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. + // is behind our king. Note that UnblockedStorm[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( 107), V( 123), 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) } + { V( 85), V(-289), V(-166), V(97), V(50), V( 45), V( 50) }, + { V( 46), V( -25), V( 122), V(45), V(37), V(-10), V( 20) }, + { V( -6), V( 51), V( 168), V(34), V(-2), V(-22), V(-14) }, + { V(-15), V( -11), V( 101), V( 4), V(11), V(-15), V(-29) } }; - // Danger of blocked enemy pawns storming our king, by rank - constexpr Value BlockedStorm[RANK_NB] = - { V(0), V(0), V( 66), V(6), V(5), V(1), V(15) }; - #undef S #undef V @@ -69,81 +69,86 @@ namespace { Score evaluate(const Position& pos, Pawns::Entry* e) { constexpr Color Them = (Us == WHITE ? BLACK : WHITE); - constexpr Direction Up = (Us == WHITE ? NORTH : SOUTH); + constexpr Direction Up = pawn_push(Us); - Bitboard b, neighbours, stoppers, doubled, supported, phalanx; - Bitboard lever, leverPush; + Bitboard neighbours, stoppers, support, phalanx, opposed; + Bitboard lever, leverPush, blocked; Square s; - bool opposed, backward; + bool backward, passed, doubled; Score score = SCORE_ZERO; const Square* pl = pos.squares(Us); 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->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]; + Bitboard doubleAttackThem = pawn_double_attacks_bb(theirPawns); + + e->passedPawns[Us] = 0; + e->kingSquares[Us] = SQ_NONE; + e->pawnAttacks[Us] = e->pawnAttacksSpan[Us] = pawn_attacks_bb(ourPawns); // 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); - - e->semiopenFiles[Us] &= ~(1 << f); - e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s); + Rank r = relative_rank(Us, s); // Flag the pawn opposed = theirPawns & forward_file_bb(Us, s); - stoppers = theirPawns & passed_pawn_mask(Us, s); + blocked = theirPawns & (s + Up); + 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); - - // 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_file_bb(Us, s)) - && popcount(supported) >= popcount(lever) - 1 - && popcount(phalanx) >= popcount(leverPush)) + 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 safely advance. + backward = !(neighbours & forward_ranks_bb(Them, s + Up)) + && (leverPush | blocked); + + // Compute additional span if pawn is not backward nor blocked + if (!backward && !blocked) + e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s); + + // A pawn is passed if one of the three following conditions is true: + // (a) there is no stoppers except some levers + // (b) the only stoppers are the leverPush, but we outnumber them + // (c) there is only one front stopper which can be levered. + passed = !(stoppers ^ lever) + || ( !(stoppers ^ leverPush) + && popcount(phalanx) >= popcount(leverPush)) + || ( stoppers == blocked && r >= RANK_5 + && (shift(support) & ~(theirPawns | doubleAttackThem))); + + // Passed pawns will be properly scored later in evaluation when we have + // full attack info. + if (passed) e->passedPawns[Us] |= s; - else if ( stoppers == SquareBB[s + Up] - && relative_rank(Us, s) >= RANK_5) + // Score this pawn + if (support | phalanx) { - b = shift(supported) & ~theirPawns; - while (b) - if (!more_than_one(theirPawns & PawnAttacks[Us][pop_lsb(&b)])) - e->passedPawns[Us] |= s; - } + int v = Connected[r] * (2 + bool(phalanx) - bool(opposed)) + + 21 * popcount(support); - // Score this pawn - if (supported | phalanx) - score += Connected[opposed][bool(phalanx)][popcount(supported)][relative_rank(Us, s)]; + score += make_score(v, v * (r - 2) / 4); + } else if (!neighbours) - score -= Isolated, e->weakUnopposed[Us] += !opposed; + score -= Isolated + + WeakUnopposed * !opposed; else if (backward) - score -= Backward, e->weakUnopposed[Us] += !opposed; + score -= Backward + + WeakUnopposed * !opposed; - if (doubled && !supported) - score -= Doubled; + if (!support) + score -= Doubled * doubled + + WeakLever * more_than_one(lever); } return score; @@ -153,27 +158,6 @@ 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 @@ -190,9 +174,6 @@ 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; } @@ -202,37 +183,35 @@ 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) { +Score Entry::evaluate_shelter(const Position& pos, Square ksq) { - constexpr Color Them = (Us == WHITE ? BLACK : WHITE); - constexpr Direction Down = (Us == WHITE ? SOUTH : NORTH); - constexpr Bitboard BlockRanks = (Us == WHITE ? Rank1BB | Rank2BB : Rank8BB | Rank7BB); + constexpr Color Them = (Us == WHITE ? BLACK : WHITE); - Bitboard b = pos.pieces(PAWN) & (forward_ranks_bb(Us, 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 = (ourPawns & file_bb(ksq)) ? Value(5) : Value(-5); - - if (shift(theirPawns) & (FileABB | FileHBB) & BlockRanks & ksq) - safety += Value(374); + Score bonus = make_score(5, 5); - 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; + int ourRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : 0; b = theirPawns & file_bb(f); 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]; + File d = map_to_queenside(f); + bonus += make_score(ShelterStrength[d][ourRank], 0); + + if (ourRank && (ourRank == theirRank - 1)) + bonus -= BlockedStorm * int(theirRank == RANK_3); + else + bonus -= make_score(UnblockedStorm[d][theirRank], 0); } - return safety; + return bonus; } @@ -240,30 +219,37 @@ Value Entry::evaluate_shelter(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); + auto compare = [](Score a, Score b) { return mg_value(a) < mg_value(b); }; - Bitboard pawns = pos.pieces(Us, PAWN); - if (pawns) - while (!(DistanceRingBB[ksq][minKingPawnDistance++] & pawns)) {} + Score shelter = evaluate_shelter(pos, ksq); + + // If we can castle use the bonus after castling if it is bigger - Value bonus = evaluate_shelter(pos, ksq); + if (pos.can_castle(Us & KING_SIDE)) + shelter = std::max(shelter, evaluate_shelter(pos, relative_square(Us, SQ_G1)), compare); - // If we can castle use the bonus after the castling if it is bigger - if (pos.can_castle(MakeCastling::right)) - bonus = std::max(bonus, evaluate_shelter(pos, relative_square(Us, SQ_G1))); + if (pos.can_castle(Us & QUEEN_SIDE)) + shelter = std::max(shelter, evaluate_shelter(pos, relative_square(Us, SQ_C1)), compare); + + // In endgame we like to bring our king near our closest pawn + Bitboard pawns = pos.pieces(Us, PAWN); + int minPawnDist = pawns ? 8 : 0; - if (pos.can_castle(MakeCastling::right)) - bonus = std::max(bonus, evaluate_shelter(pos, relative_square(Us, SQ_C1))); + if (pawns & PseudoAttacks[KING][ksq]) + minPawnDist = 1; + else while (pawns) + minPawnDist = std::min(minPawnDist, distance(ksq, pop_lsb(&pawns))); - return make_score(bonus, -16 * minKingPawnDistance); + return shelter - make_score(0, 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