X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=3d99bfc68645a3e327554eef3fc2e067755a1297;hp=0089c42da28a818ec3ae0bca16331e2c1bb45c0d;hb=3e4dfb49a747be902d25ae06783f98ba29fb5030;hpb=d3600c39a745179ed6b094b305d0645e83a1ee86 diff --git a/src/pawns.cpp b/src/pawns.cpp index 0089c42d..3d99bfc6 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -1,386 +1,292 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008 Marco Costalba + Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, 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 the Free Software Foundation, either version 3 of the License, or (at your option) any later version. - + Stockfish is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. - + You should have received a copy of the GNU General Public License along with this program. If not, see . */ - -//// -//// Includes -//// - #include +#include "bitboard.h" +#include "bitcount.h" #include "pawns.h" - - -//// -//// Local definitions -//// +#include "position.h" namespace { - /// Constants and variables - - // Doubled pawn penalty by file, middle game. - const Value DoubledPawnMidgamePenalty[8] = { - Value(20), Value(30), Value(34), Value(34), - Value(34), Value(34), Value(30), Value(20) + #define V Value + #define S(mg, eg) make_score(mg, eg) + + // Doubled pawn penalty by opposed flag and file + const Score DoubledPawnPenalty[2][FILE_NB] = { + { 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][FILE_NB] = { + { 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][FILE_NB] = { + { 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[FILE_NB] = { + S(11,-1), S(13,-1), S(13,-1), S(14,-1), + S(14,-1), S(13,-1), S(13,-1), S(11,-1) }; - // Doubled pawn penalty by file, endgame. - const Value DoubledPawnEndgamePenalty[8] = { - Value(35), Value(40), Value(40), Value(40), - Value(40), Value(40), Value(40), Value(35) + // Candidate passed pawn bonus by rank + const Score CandidateBonus[RANK_NB] = { + S( 0, 0), S( 6, 13), S(6,13), S(14,29), + S(34,68), S(83,166), S(0, 0), S( 0, 0) }; - // Isolated pawn penalty by file, middle game. - const Value IsolatedPawnMidgamePenalty[8] = { - Value(20), Value(30), Value(34), Value(34), - Value(34), Value(34), Value(30), Value(20) - }; + const Score PawnStructureWeight = S(233, 201); - // Isolated pawn penalty by file, endgame. - const Value IsolatedPawnEndgamePenalty[8] = { - Value(35), Value(40), Value(40), Value(40), - Value(40), Value(40), Value(40), Value(35) - }; + // Weakness of our pawn shelter in front of the king indexed by [king pawn][rank] + const Value ShelterWeakness[2][RANK_NB] = + { { 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) } }; - // Backward pawn penalty by file, middle game. - const Value BackwardPawnMidgamePenalty[8] = { - Value(16), Value(24), Value(27), Value(27), - Value(27), Value(27), Value(24), Value(16) - }; + // Danger of enemy pawns moving toward our king indexed by [pawn blocked][rank] + const Value StormDanger[2][RANK_NB] = + { { V(26), V(0), V(128), V(51), V(26) }, + { V(13), V(0), V( 64), V(25), V(13) } }; - // Backward pawn penalty by file, endgame. - const Value BackwardPawnEndgamePenalty[8] = { - Value(28), Value(32), Value(32), Value(32), - Value(32), Value(32), Value(32), Value(28) - }; + // 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); - // Pawn chain membership bonus by file, middle game. - const Value ChainMidgameBonus[8] = { - Value(14), Value(16), Value(17), Value(18), - Value(18), Value(17), Value(16), Value(14) - }; + #undef S + #undef V - // Pawn chain membership bonus by file, endgame. - const Value ChainEndgameBonus[8] = { - Value(16), Value(16), Value(16), Value(16), - Value(16), Value(16), Value(16), Value(16) - }; + template + Score evaluate_pawns(const Position& pos, Bitboard ourPawns, + Bitboard theirPawns, Pawns::Entry* e) { - // Candidate passed pawn bonus by rank, middle game. - const Value CandidateMidgameBonus[8] = { - Value(0), Value(12), Value(12), Value(20), - Value(40), Value(90), Value(0), Value(0) - }; + const Color Them = (Us == WHITE ? BLACK : WHITE); - // Candidate passed pawn bonus by rank, endgame. - const Value CandidateEndgameBonus[8] = { - Value(0), Value(24), Value(24), Value(40), - Value(80), Value(180), Value(0), Value(0) - }; + 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); - // Evaluate pawn storms? - const bool EvaluatePawnStorms = true; - - // Pawn storm tables for positions with opposite castling: - const int QStormTable[64] = { - 0, 0, 0, 0, 0, 0, 0, 0, - -22, -22, -22, -13, -4, 0, 0, 0, - -4, -9, -9, -9, -4, 0, 0, 0, - 9, 18, 22, 18, 9, 0, 0, 0, - 22, 31, 31, 22, 0, 0, 0, 0, - 31, 40, 40, 31, 0, 0, 0, 0, - 31, 40, 40, 31, 0, 0, 0, 0, - 0, 0, 0, 0, 0, 0, 0, 0 - }; - - const int KStormTable[64] = { - 0, 0, 0, 0, 0, 0, 0, 0, - 0, 0, 0, -4, -13, -22, -27, -27, - 0, 0, 0, -4, -9, -13, -18, -18, - 0, 0, 0, 0, 9, 9, 9, 9, - 0, 0, 0, 0, 9, 18, 27, 27, - 0, 0, 0, 0, 9, 27, 40, 36, - 0, 0, 0, 0, 0, 31, 40, 31, - 0, 0, 0, 0, 0, 0, 0, 0 - }; + // 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)); - // Pawn storm open file bonuses by file: - const int KStormOpenFileBonus[8] = { - 45, 45, 30, 0, 0, 0, 0, 0 - }; + f = file_of(s); + r = rank_of(s); - const int QStormOpenFileBonus[8] = { - 0, 0, 0, 0, 0, 30, 45, 30 - }; + // 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; + } -//// -//// Functions -//// + assert(opposed | passed | (attack_span_mask(Us, s) & theirPawns)); -/// Constructor + // 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)]; + } -PawnInfoTable::PawnInfoTable(unsigned numOfEntries) { - size = numOfEntries; - entries = new PawnInfo[size]; - if(entries == NULL) { - std::cerr << "Failed to allocate " << (numOfEntries * sizeof(PawnInfo)) - << " bytes for pawn hash table." << std::endl; - exit(EXIT_FAILURE); + e->pawnsOnWhiteSquaresCount[Us] = popcount(ourPawns & WhiteSquares); + e->pawnsOnWhiteSquaresCount[Them] = popcount(theirPawns & WhiteSquares); + + e->pawnsOnBlackSquaresCount[Us] = popcount(ourPawns & BlackSquares); + e->pawnsOnBlackSquaresCount[Them] = popcount(theirPawns & BlackSquares); + + return value; } - this->clear(); } +namespace Pawns { -/// Destructor +/// probe() takes a position object as input, computes a Entry 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. -PawnInfoTable::~PawnInfoTable() { - delete [] entries; -} +Entry* probe(const Position& pos, Table& entries) { + + Key key = pos.pawn_key(); + Entry* e = entries[key]; + // 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; -/// PawnInfoTable::clear() clears the pawn hash table by setting all -/// entries to 0. + 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; -void PawnInfoTable::clear() { - memset(entries, 0, size * sizeof(PawnInfo)); + 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); + + e->value = evaluate_pawns(pos, wPawns, bPawns, e) + - evaluate_pawns(pos, bPawns, wPawns, e); + + e->value = apply_weight(e->value, PawnStructureWeight); + + return e; } -/// PawnInfoTable::get_pawn_info() takes a position object as input, computes -/// a PawnInfo 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. - -PawnInfo *PawnInfoTable::get_pawn_info(const Position &pos) { - assert(pos.is_ok()); - - Key key = pos.get_pawn_key(); - int index = int(key & (size - 1)); - PawnInfo *pi = entries + index; - - // If pi->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(pi->key == key) - return pi; - - // Clear the PawnInfo object, and set the key: - pi->clear(); - pi->key = key; - - Value mgValue[2] = {Value(0), Value(0)}; - Value egValue[2] = {Value(0), Value(0)}; - - // Loop through the pawns for both colors: - for(Color us = WHITE; us <= BLACK; us++) { - Color them = opposite_color(us); - Bitboard ourPawns = pos.pawns(us); - Bitboard theirPawns = pos.pawns(them); - Bitboard pawns = ourPawns; - - // Initialize pawn storm scores by giving bonuses for open files: - if(EvaluatePawnStorms) - for(File f = FILE_A; f <= FILE_H; f++) - if(pos.file_is_half_open(us, f)) { - pi->ksStormValue[us] += KStormOpenFileBonus[f]; - pi->qsStormValue[us] += QStormOpenFileBonus[f]; - } +/// Entry::shelter_storm() calculates shelter and storm penalties for the file +/// the king is on, as well as the two adjacent files. - // Loop through all pawns of the current color and score each pawn: - while(pawns) { - Square s = pop_1st_bit(&pawns); - File f = square_file(s); - Rank r = square_rank(s); - bool passed, doubled, isolated, backward, chain, candidate; - int bonus; - - assert(pos.piece_on(s) == pawn_of_color(us)); - - // The file containing the pawn is not half open: - pi->halfOpenFiles[us] &= ~(1 << f); - - // Passed, isolated or doubled pawn? - passed = pos.pawn_is_passed(us, s); - isolated = pos.pawn_is_isolated(us, s); - doubled = pos.pawn_is_doubled(us, s); - - if(EvaluatePawnStorms) { - // We calculate kingside and queenside pawn storm - // scores for both colors. These are used when evaluating - // middle game positions with opposite side castling. - // - // Each pawn is given a base score given by a piece square table - // (KStormTable[] or QStormTable[]). This score is increased if - // there are enemy pawns on adjacent files in front of the pawn. - // This is because we want to be able to open files against the - // enemy king, and to avoid blocking the pawn structure (e.g. white - // pawns on h6, g5, black pawns on h7, g6, f7). - - // Kingside pawn storms: - bonus = KStormTable[relative_square(us, s)]; - if(bonus > 0 && outpost_mask(us, s) & theirPawns) { - switch(f) { - - case FILE_F: - bonus += bonus / 4; - break; - - case FILE_G: - bonus += bonus / 2 + bonus / 4; - break; - - case FILE_H: - bonus += bonus / 2; - break; - - default: - break; - } - } - pi->ksStormValue[us] += bonus; +template +Value Entry::shelter_storm(const Position& pos, Square ksq) { - // Queenside pawn storms: - bonus = QStormTable[relative_square(us, s)]; - if(bonus > 0 && passed_pawn_mask(us, s) & theirPawns) { - switch(f) { + const Color Them = (Us == WHITE ? BLACK : WHITE); - case FILE_A: - bonus += bonus / 2; - break; + 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); + Bitboard theirPawns = b & pos.pieces(Them); + Rank rkUs, rkThem; + File kf = file_of(ksq); - case FILE_B: - bonus += bonus / 2 + bonus / 4; - break; + kf = (kf == FILE_A) ? FILE_B : (kf == FILE_H) ? FILE_G : kf; - case FILE_C: - bonus += bonus / 2; - break; + for (int f = kf - 1; f <= kf + 1; f++) + { + // Shelter penalty is higher for the pawn in front of the king + b = ourPawns & FileBB[f]; + rkUs = b ? rank_of(Us == WHITE ? lsb(b) : ~msb(b)) : RANK_1; + safety -= ShelterWeakness[f != kf][rkUs]; - default: - break; - } - } - pi->qsStormValue[us] += bonus; - } - - // Member of a pawn chain? We could speed up the test a little by - // introducing an array of masks indexed by color and square for doing - // the test, but because everything is hashed, it probably won't make - // any noticable difference. - chain = (us == WHITE)? - (ourPawns & neighboring_files_bb(f) & (rank_bb(r) | rank_bb(r-1))) : - (ourPawns & neighboring_files_bb(f) & (rank_bb(r) | rank_bb(r+1))); - - - // Test for backward pawn. - - // If the pawn is isolated, passed, or member of a pawn chain, it cannot - // be backward: - if(passed || isolated || chain) - backward = false; - // If the pawn can capture an enemy pawn, it's not backward: - else if(pos.pawn_attacks(us, s) & theirPawns) - backward = false; - // Check for friendly pawns behind on neighboring files: - else if(ourPawns & in_front_bb(them, r) & neighboring_files_bb(f)) - backward = false; - else { - // We now know that there is no friendly pawns beside or behind this - // pawn on neighboring files. We now check whether the pawn is - // backward by looking in the forward direction on the neighboring - // files, and seeing whether we meet a friendly or an enemy pawn first. - Bitboard b; - if(us == WHITE) { - for(b=pos.pawn_attacks(us, s); !(b&(ourPawns|theirPawns)); b<<=8); - backward = (b | (b << 8)) & theirPawns; - } - else { - for(b=pos.pawn_attacks(us, s); !(b&(ourPawns|theirPawns)); b>>=8); - backward = (b | (b >> 8)) & theirPawns; - } - } - - // Test for candidate passed pawn. - candidate = - (!passed && pos.file_is_half_open(them, f) && - count_1s_max_15(neighboring_files_bb(f) - & (in_front_bb(them, r) | rank_bb(r)) - & ourPawns) - - count_1s_max_15(neighboring_files_bb(f) & in_front_bb(us, r) - & theirPawns) - >= 0); - - // In order to prevent doubled passed pawns from receiving a too big - // bonus, only the frontmost passed pawn on each file is considered as - // a true passed pawn. - if(passed && (ourPawns & squares_in_front_of(us, s))) { - // candidate = true; - passed = false; - } - - // Score this pawn: - Value mv = Value(0), ev = Value(0); - if(isolated) { - mv -= IsolatedPawnMidgamePenalty[f]; - ev -= IsolatedPawnEndgamePenalty[f]; - if(pos.file_is_half_open(them, f)) { - mv -= IsolatedPawnMidgamePenalty[f] / 2; - ev -= IsolatedPawnEndgamePenalty[f] / 2; - } - } - if(doubled) { - mv -= DoubledPawnMidgamePenalty[f]; - ev -= DoubledPawnEndgamePenalty[f]; - } - if(backward) { - mv -= BackwardPawnMidgamePenalty[f]; - ev -= BackwardPawnEndgamePenalty[f]; - if(pos.file_is_half_open(them, f)) { - mv -= BackwardPawnMidgamePenalty[f] / 2; - ev -= BackwardPawnEndgamePenalty[f] / 2; - } - } - if(chain) { - mv += ChainMidgameBonus[f]; - ev += ChainEndgameBonus[f]; - } - if(candidate) { - mv += CandidateMidgameBonus[relative_rank(us, s)]; - ev += CandidateEndgameBonus[relative_rank(us, s)]; - } - - mgValue[us] += mv; - egValue[us] += ev; - - // If the pawn is passed, set the square of the pawn in the passedPawns - // bitboard: - if(passed) - set_bit(&(pi->passedPawns), s); - } + // Storm danger is smaller if enemy pawn is blocked + b = theirPawns & FileBB[f]; + rkThem = b ? rank_of(Us == WHITE ? lsb(b) : ~msb(b)) : RANK_1; + safety -= StormDanger[rkThem == rkUs + 1][rkThem]; } - pi->mgValue = int16_t(mgValue[WHITE] - mgValue[BLACK]); - pi->egValue = int16_t(egValue[WHITE] - egValue[BLACK]); + return safety; +} + + +/// Entry::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. + +template +Score Entry::update_safety(const Position& pos, Square ksq) { + + kingSquares[Us] = ksq; + castleRights[Us] = pos.can_castle(Us); + minKPdistance[Us] = 0; - return pi; + 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]); + + 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))) + bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_G1))); + + if (pos.can_castle(make_castle_right(Us, QUEEN_SIDE))) + bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_C1))); + + return kingSafety[Us] = make_score(bonus, -16 * minKPdistance[Us]); } + +// Explicit template instantiation +template Score Entry::update_safety(const Position& pos, Square ksq); +template Score Entry::update_safety(const Position& pos, Square ksq); + +} // namespace Pawns