X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=401977bdf52980975576ece727f5fe824140bc4d;hp=73a9b904b347757fda1ba601344dfd69f913259b;hb=6d8f583af26daa1c158324d5c13cf01b17c746a5;hpb=4f5680950a4e4c55da2877e1be91efd2be1c76ba diff --git a/src/pawns.cpp b/src/pawns.cpp index 73a9b904..67bf59d1 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -1,7 +1,8 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, 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 @@ -17,271 +18,294 @@ along with this program. If not, see . */ +#include #include #include "bitboard.h" -#include "bitcount.h" #include "pawns.h" #include "position.h" +#include "thread.h" namespace { #define V Value #define S(mg, eg) make_score(mg, eg) - // Doubled pawn penalty by opposed flag and file - const Score DoubledPawnPenalty[2][8] = { - { S(13, 43), S(20, 48), S(23, 48), S(23, 48), - S(23, 48), S(23, 48), S(20, 48), S(13, 43) }, - { S(13, 43), S(20, 48), S(23, 48), S(23, 48), - S(23, 48), S(23, 48), S(20, 48), S(13, 43) }}; - - // Isolated pawn penalty by opposed flag and file - const Score IsolatedPawnPenalty[2][8] = { - { S(37, 45), S(54, 52), S(60, 52), S(60, 52), - S(60, 52), S(60, 52), S(54, 52), S(37, 45) }, - { S(25, 30), S(36, 35), S(40, 35), S(40, 35), - S(40, 35), S(40, 35), S(36, 35), S(25, 30) }}; - - // Backward pawn penalty by opposed flag and file - const Score BackwardPawnPenalty[2][8] = { - { S(30, 42), S(43, 46), S(49, 46), S(49, 46), - S(49, 46), S(49, 46), S(43, 46), S(30, 42) }, - { S(20, 28), S(29, 31), S(33, 31), S(33, 31), - S(33, 31), S(33, 31), S(29, 31), S(20, 28) }}; - - // Pawn chain membership bonus by file - const Score ChainBonus[8] = { - S(11,-1), S(13,-1), S(13,-1), S(14,-1), - S(14,-1), S(13,-1), S(13,-1), S(11,-1) + // Isolated pawn penalty + const Score Isolated = S(13, 18); + + // Backward pawn penalty + const Score Backward = S(24, 12); + + // Connected pawn bonus by opposed, phalanx, #support and rank + Score Connected[2][2][3][RANK_NB]; + + // Doubled pawn penalty + const Score Doubled = S(18, 38); + + // Weakness of our pawn shelter in front of the king by [isKingFile][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[][int(FILE_NB) / 2][RANK_NB] = { + { { V( 98), V(20), V(11), V(42), V( 83), V( 84), V(101) }, // Not On King file + { V(103), V( 8), V(33), V(86), V( 87), V(105), V(113) }, + { V(100), V( 2), V(65), V(95), V( 59), V( 89), V(115) }, + { V( 72), V( 6), V(52), V(74), V( 83), V( 84), V(112) } }, + { { V(105), V(19), V( 3), V(27), V( 85), V( 93), V( 84) }, // On King file + { V(121), V( 7), V(33), V(95), V(112), V( 86), V( 72) }, + { V(121), V(26), V(65), V(90), V( 65), V( 76), V(117) }, + { V( 79), V( 0), V(45), V(65), V( 94), V( 92), V(105) } } }; - // Candidate passed pawn bonus by rank - const Score CandidateBonus[8] = { - S( 0, 0), S( 6, 13), S(6,13), S(14,29), - S(34,68), S(83,166), S(0, 0), S( 0, 0) + // 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) } } }; - const Score PawnStructureWeight = S(233, 201); - - // Weakness of our pawn shelter in front of the king indexed by [king pawn][rank] - const Value ShelterWeakness[2][8] = - { { V(141), V(0), V(38), V(102), V(128), V(141), V(141) }, - { V( 61), V(0), V(16), V( 44), V( 56), V( 61), V( 61) } }; - - // Danger of enemy pawns moving toward our king indexed by [pawn blocked][rank] - const Value StormDanger[2][8] = - { { V(26), V(0), V(128), V(51), V(26) }, - { V(13), V(0), V( 64), V(25), V(13) } }; - // Max bonus for king safety. Corresponds to start position with all the pawns - // in front of the king and no enemy pawn on the horizont. - const Value MaxSafetyBonus = V(263); + // 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 Direction Up = (Us == WHITE ? NORTH : SOUTH); + + Bitboard b, neighbours, stoppers, doubled, supported, 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 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]; + + // 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); + + // Flag the pawn + opposed = theirPawns & forward_file_bb(Us, s); + stoppers = theirPawns & passed_pawn_mask(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); + + // 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 && (forward_ranks_bb(Them, s + Up) & neighbours))); + } + + // 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) + && 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)])) + e->passedPawns[Us] |= s; + } + + // Score this pawn + if (supported | phalanx) + score += Connected[opposed][bool(phalanx)][popcount(supported)][relative_rank(Us, s)]; + + else if (!neighbours) + score -= Isolated, e->weakUnopposed[Us] += !opposed; + + else if (backward) + score -= Backward, e->weakUnopposed[Us] += !opposed; + + if (doubled && !supported) + score -= Doubled; + } + + return score; + } -/// PawnTable::probe() takes a position object as input, computes a PawnEntry -/// object, and returns a pointer to it. The result is also stored in a hash -/// table, so we don't have to recompute everything when the same pawn structure -/// occurs again. +} // namespace -PawnEntry* PawnTable::probe(const Position& pos) { +namespace Pawns { - Key key = pos.pawn_key(); - PawnEntry* e = entries[key]; +/// 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. - // If e->key matches the position's pawn hash key, it means that we - // have analysed this pawn structure before, and we can simply return - // the information we found the last time instead of recomputing it. - if (e->key == key) - return e; +void init() { - e->key = key; - e->passedPawns[WHITE] = e->passedPawns[BLACK] = 0; - e->kingSquares[WHITE] = e->kingSquares[BLACK] = SQ_NONE; - e->halfOpenFiles[WHITE] = e->halfOpenFiles[BLACK] = 0xFF; - - Bitboard wPawns = pos.pieces(WHITE, PAWN); - Bitboard bPawns = pos.pieces(BLACK, PAWN); - e->pawnAttacks[WHITE] = ((wPawns & ~FileHBB) << 9) | ((wPawns & ~FileABB) << 7); - e->pawnAttacks[BLACK] = ((bPawns & ~FileHBB) >> 7) | ((bPawns & ~FileABB) >> 9); + static const int Seed[RANK_NB] = { 0, 13, 24, 18, 76, 100, 175, 330 }; - e->value = evaluate_pawns(pos, wPawns, bPawns, e) - - evaluate_pawns(pos, bPawns, wPawns, e); - - e->value = apply_weight(e->value, PawnStructureWeight); + 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; - return e; + Connected[opposed][phalanx][support][r] = make_score(v, v * (r - 2) / 4); + } } -/// PawnTable::evaluate_pawns() evaluates each pawn of the given color +/// 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 +/// have to recompute all when the same pawns configuration occurs again. -template -Score PawnTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, - Bitboard theirPawns, PawnEntry* e) { +Entry* probe(const Position& pos) { - const Color Them = (Us == WHITE ? BLACK : WHITE); + Key key = pos.pawn_key(); + Entry* e = pos.this_thread()->pawnsTable[key]; - Bitboard b; - Square s; - File f; - Rank r; - bool passed, isolated, doubled, opposed, chain, backward, candidate; - Score value = SCORE_ZERO; - const Square* pl = pos.piece_list(Us, PAWN); + if (e->key == key) + return e; - // 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)); - - f = file_of(s); - r = rank_of(s); - - // This file cannot be half open - e->halfOpenFiles[Us] &= ~(1 << f); - - // Our rank plus previous one. Used for chain detection - b = rank_bb(r) | rank_bb(Us == WHITE ? r - Rank(1) : r + Rank(1)); - - // Flag the pawn as passed, isolated, doubled or member of a pawn - // chain (but not the backward one). - chain = ourPawns & adjacent_files_bb(f) & b; - isolated = !(ourPawns & adjacent_files_bb(f)); - doubled = ourPawns & forward_bb(Us, s); - opposed = theirPawns & forward_bb(Us, s); - passed = !(theirPawns & passed_pawn_mask(Us, s)); - - // Test for backward pawn - backward = false; - - // If the pawn is passed, isolated, or member of a pawn chain it cannot - // be backward. If there are friendly pawns behind on adjacent files - // or if can capture an enemy pawn it cannot be backward either. - if ( !(passed | isolated | chain) - && !(ourPawns & attack_span_mask(Them, s)) - && !(pos.attacks_from(s, Us) & theirPawns)) - { - // We now know that there are no friendly pawns beside or behind this - // pawn on adjacent files. We now check whether the pawn is - // backward by looking in the forward direction on the adjacent - // files, and seeing whether we meet a friendly or an enemy pawn first. - b = pos.attacks_from(s, Us); - - // Note that we are sure to find something because pawn is not passed - // nor isolated, so loop is potentially infinite, but it isn't. - while (!(b & (ourPawns | theirPawns))) - Us == WHITE ? b <<= 8 : b >>= 8; - - // The friendly pawn needs to be at least two ranks closer than the - // enemy pawn in order to help the potentially backward pawn advance. - backward = (b | (Us == WHITE ? b << 8 : b >> 8)) & theirPawns; - } - - assert(opposed | passed | (attack_span_mask(Us, s) & theirPawns)); - - // A not passed pawn is a candidate to become passed if it is free to - // advance and if the number of friendly pawns beside or behind this - // pawn on adjacent files is higher or equal than the number of - // enemy pawns in the forward direction on the adjacent files. - candidate = !(opposed | passed | backward | isolated) - && (b = attack_span_mask(Them, s + pawn_push(Us)) & ourPawns) != 0 - && popcount(b) >= popcount(attack_span_mask(Us, s) & theirPawns); - - // Passed pawns will be properly scored in evaluation because we need - // full attack info to evaluate passed pawns. Only the frontmost passed - // pawn on each file is considered a true passed pawn. - if (passed && !doubled) - e->passedPawns[Us] |= s; - - // Score this pawn - if (isolated) - value -= IsolatedPawnPenalty[opposed][f]; - - if (doubled) - value -= DoubledPawnPenalty[opposed][f]; - - if (backward) - value -= BackwardPawnPenalty[opposed][f]; - - if (chain) - value += ChainBonus[f]; - - if (candidate) - value += CandidateBonus[relative_rank(Us, s)]; - } + 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 value; + return e; } -/// PawnEntry::shelter_storm() calculates shelter and storm penalties for the file -/// the king is on, as well as the two adjacent files. +/// Entry::shelter_storm() calculates shelter and storm penalties for the file +/// the king is on, as well as the two closest files. template -Value PawnEntry::shelter_storm(const Position& pos, Square ksq) { - - const Color Them = (Us == WHITE ? BLACK : WHITE); - - Value safety = MaxSafetyBonus; - Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, ksq) | rank_bb(ksq)); - Bitboard ourPawns = b & pos.pieces(Us) & ~rank_bb(ksq); +Value Entry::shelter_storm(const Position& pos, Square ksq) { + + constexpr Color Them = (Us == WHITE ? BLACK : WHITE); + constexpr Bitboard ShelterMask = + Us == WHITE ? make_bitboard(SQ_A2, SQ_B3, SQ_C2, SQ_F2, SQ_G3, SQ_H2) + : make_bitboard(SQ_A7, SQ_B6, SQ_C7, SQ_F7, SQ_G6, SQ_H7); + constexpr Bitboard StormMask = + Us == WHITE ? make_bitboard(SQ_A3, SQ_C3, SQ_F3, SQ_H3) + : make_bitboard(SQ_A6, SQ_C6, SQ_F6, SQ_H6); + + enum { BlockedByKing, Unopposed, BlockedByPawn, Unblocked }; + + File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq))); + Bitboard b = pos.pieces(PAWN) + & (forward_ranks_bb(Us, ksq) | rank_bb(ksq)) + & (adjacent_files_bb(center) | file_bb(center)); + Bitboard ourPawns = b & pos.pieces(Us); Bitboard theirPawns = b & pos.pieces(Them); - Rank rkUs, rkThem; - File kf = file_of(ksq); - - kf = (kf == FILE_A) ? kf++ : (kf == FILE_H) ? kf-- : kf; + Value safety = MaxSafetyBonus; - for (int f = kf - 1; f <= kf + 1; f++) + for (File f = File(center - 1); f <= File(center + 1); ++f) { - // Shelter penalty is higher for the pawn in front of the king - b = ourPawns & FileBB[f]; - rkUs = b ? rank_of(Us == WHITE ? first_1(b) : ~last_1(b)) : RANK_1; - safety -= ShelterWeakness[f != kf][rkUs]; - - // Storm danger is smaller if enemy pawn is blocked - b = theirPawns & FileBB[f]; - rkThem = b ? rank_of(Us == WHITE ? first_1(b) : ~last_1(b)) : RANK_1; - safety -= StormDanger[rkThem == rkUs + 1][rkThem]; + 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, ~f); + safety -= ShelterWeakness[f == file_of(ksq)][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]; } + if (popcount((ourPawns & ShelterMask) | (theirPawns & StormMask)) == 5) + safety += Value(300); + return safety; } -/// PawnEntry::update_safety() calculates and caches a bonus for king safety. It is -/// called only when king square changes, about 20% of total king_safety() calls. +/// Entry::do_king_safety() calculates a bonus for king safety. It is called only +/// when king square changes, which is about 20% of total king_safety() calls. template -Score PawnEntry::update_safety(const Position& pos, Square ksq) { +Score Entry::do_king_safety(const Position& pos, Square ksq) { kingSquares[Us] = ksq; - castleRights[Us] = pos.can_castle(Us); - minKPdistance[Us] = 0; + castlingRights[Us] = pos.can_castle(Us); + int minKingPawnDistance = 0; Bitboard pawns = pos.pieces(Us, PAWN); if (pawns) - while (!(DistanceRingsBB[ksq][minKPdistance[Us]++] & pawns)) {} - - if (relative_rank(Us, ksq) > RANK_4) - return kingSafety[Us] = make_score(0, -16 * minKPdistance[Us]); + while (!(DistanceRingBB[ksq][minKingPawnDistance++] & pawns)) {} Value bonus = shelter_storm(pos, ksq); - // If we can castle use the bonus after the castle if is bigger - if (pos.can_castle(make_castle_right(Us, KING_SIDE))) + // 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(make_castle_right(Us, QUEEN_SIDE))) + if (pos.can_castle(MakeCastling::right)) bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_C1))); - return kingSafety[Us] = make_score(bonus, -16 * minKPdistance[Us]); + return make_score(bonus, -16 * minKingPawnDistance); } // Explicit template instantiation -template Score PawnEntry::update_safety(const Position& pos, Square ksq); -template Score PawnEntry::update_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, Square ksq); + +} // namespace Pawns