X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=1e88652e154be205ee9a9008450f1ebc4bd53641;hp=65bb3dbaa38d1dcc9224639f6d0c5bf4ae860313;hb=c9dcda6ac488c0058ebd567e1f52e30b8cd0db20;hpb=97f5d19bdc0439f297ad11dd59997aba9342ce93 diff --git a/src/pawns.cpp b/src/pawns.cpp index 65bb3dba..1e88652e 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -1,7 +1,7 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2014 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 @@ -17,358 +17,284 @@ along with this program. If not, see . */ - -//// -//// Includes -//// - +#include #include -#include +#include "bitboard.h" #include "bitcount.h" #include "pawns.h" #include "position.h" - -//// -//// Local definitions -//// - namespace { - /// Constants and variables - + #define V Value #define S(mg, eg) make_score(mg, eg) // Doubled pawn penalty by file - const Score DoubledPawnPenalty[8] = { + const Score Doubled[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) - }; - - // Isolated pawn penalty by file - const Score IsolatedPawnPenalty[8] = { - 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 file - const Score BackwardPawnPenalty[8] = { - 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) - }; + S(23, 48), S(23, 48), S(20, 48), S(13, 43) }; + + // Isolated pawn penalty by opposed flag and file + const Score Isolated[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 Backward[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) } }; + + // Connected pawn bonus by file and rank (initialized by formula) + Score Connected[FILE_NB][RANK_NB]; // Candidate passed pawn bonus by rank - const Score CandidateBonus[8] = { + const Score CandidatePassed[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) - }; - - // UnpairedPawnsTable[] gives a score according to the number - // of panws that do not have an enemy pawn in front of them. - const int UnpairedPawnsTable[16] = { 32, 48, 64, 80, 96, 112, 128, 128, 128 }; - - // PawnsQtyTable[] gives a score according to the number of panws - const int PawnsQtyTable[16] = { 16, 16, 16, 16, 16, 16, 16, 16, 16 }; - - // Pawn storm tables for positions with opposite castling - const int QStormTable[64] = { - 0, 0, 0, 0, 0, 0, 0, 0, - -22,-22,-22,-14,-6, 0, 0, 0, - -6,-10,-10,-10,-6, 0, 0, 0, - 4, 12, 16, 12, 4, 0, 0, 0, - 16, 23, 23, 16, 0, 0, 0, 0, - 23, 31, 31, 23, 0, 0, 0, 0, - 23, 31, 31, 23, 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,-10,-19,-28,-33,-33, - 0, 0, 0,-10,-15,-19,-24,-24, - 0, 0, 0, 0, 1, 1, 1, 1, - 0, 0, 0, 0, 1, 10, 19, 19, - 0, 0, 0, 0, 1, 19, 31, 27, - 0, 0, 0, 0, 0, 22, 31, 22, - 0, 0, 0, 0, 0, 0, 0, 0 - }; - - // Pawn storm open file bonuses by file - const int16_t KStormOpenFileBonus[8] = { 31, 31, 18, 0, 0, 0, 0, 0 }; - const int16_t QStormOpenFileBonus[8] = { 0, 0, 0, 0, 0, 26, 42, 26 }; - - // Pawn storm lever bonuses by file - const int StormLeverBonus[8] = { -8, -8, -13, 0, 0, -13, -8, -8 }; + S(34,68), S(83,166), S(0, 0), S( 0, 0) }; + + // Bonus for file distance of the two outermost pawns + const Score PawnsFileSpan = S(0, 15); + + // Weakness of our pawn shelter in front of the king indexed by [rank] + const Value ShelterWeakness[RANK_NB] = + { V(100), V(0), V(27), V(73), V(92), V(101), V(101) }; + + // Danger of enemy pawns moving toward our king indexed by + // [no friendly pawn | pawn unblocked | pawn blocked][rank of enemy pawn] + const Value StormDanger[3][RANK_NB] = { + { V( 0), V(64), V(128), V(51), V(26) }, + { V(26), V(32), V( 96), V(38), V(20) }, + { V( 0), 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 horizon. + const Value MaxSafetyBonus = V(263); + + #undef S + #undef V + + template + Score evaluate(const Position& pos, Pawns::Entry* e) { + + const Color Them = (Us == WHITE ? BLACK : WHITE); + const Square Up = (Us == WHITE ? DELTA_N : DELTA_S); + const Square Right = (Us == WHITE ? DELTA_NE : DELTA_SW); + const Square Left = (Us == WHITE ? DELTA_NW : DELTA_SE); + + Bitboard b; + Square s; + File f; + bool passed, isolated, doubled, opposed, connected, backward, candidate; + Score value = SCORE_ZERO; + const Square* pl = pos.list(Us); + + Bitboard ourPawns = pos.pieces(Us, PAWN); + Bitboard theirPawns = pos.pieces(Them, PAWN); + + e->passedPawns[Us] = e->candidatePawns[Us] = 0; + e->kingSquares[Us] = SQ_NONE; + e->semiopenFiles[Us] = 0xFF; + e->pawnAttacks[Us] = shift_bb(ourPawns) | shift_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)); + + f = file_of(s); + + // This file cannot be semi-open + e->semiopenFiles[Us] &= ~(1 << f); + + // Our rank plus previous one + b = rank_bb(s) | rank_bb(s - pawn_push(Us)); + + // Flag the pawn as passed, isolated, doubled or + // connected (but not the backward one). + connected = 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. + // If the pawn is passed, isolated, or connected it cannot be + // backward. If there are friendly pawns behind on adjacent files + // or if it can capture an enemy pawn it cannot be backward either. + if ( (passed | isolated | connected) + || (ourPawns & pawn_attack_span(Them, s)) + || (pos.attacks_from(s, Us) & theirPawns)) + backward = false; + else + { + // 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 picking the closest pawn there. + b = pawn_attack_span(Us, s) & (ourPawns | theirPawns); + b = pawn_attack_span(Us, s) & rank_bb(backmost_sq(Us, b)); + + // If we have an enemy pawn in the same or next rank, the pawn is + // backward because it cannot advance without being captured. + backward = (b | shift_bb(b)) & theirPawns; + } + + assert(opposed | passed | (pawn_attack_span(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 than or equal to the number of + // enemy pawns in the forward direction on the adjacent files. + candidate = !(opposed | passed | backward | isolated) + && (b = pawn_attack_span(Them, s + pawn_push(Us)) & ourPawns) != 0 + && popcount(b) >= popcount(pawn_attack_span(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 -= Isolated[opposed][f]; + + if (doubled) + value -= Doubled[f]; + + if (backward) + value -= Backward[opposed][f]; + + if (connected) + value += Connected[f][relative_rank(Us, s)]; + + if (candidate) + { + value += CandidatePassed[relative_rank(Us, s)]; + + if (!doubled) + e->candidatePawns[Us] |= s; + } + } + + // In endgame it's better to have pawns on both wings. So give a bonus according + // to file distance between left and right outermost pawns. + if (pos.count(Us) > 1) + { + b = e->semiopenFiles[Us] ^ 0xFF; + value += PawnsFileSpan * int(msb(b) - lsb(b)); + } + + return value; + } -} +} // namespace +namespace Pawns { -//// -//// Functions -//// +/// init() initializes some tables by formula instead of hard-coding their values -/// Constructor +void init() { -PawnInfoTable::PawnInfoTable(unsigned numOfEntries) { + const int bonusesByFile[8] = { 1, 3, 3, 4, 4, 3, 3, 1 }; + int bonus; - size = numOfEntries; - entries = new PawnInfo[size]; - if (!entries) - { - std::cerr << "Failed to allocate " << (numOfEntries * sizeof(PawnInfo)) - << " bytes for pawn hash table." << std::endl; - Application::exit_with_failure(); - } + for (Rank r = RANK_1; r < RANK_8; ++r) + for (File f = FILE_A; f <= FILE_H; ++f) + { + bonus = r * (r-1) * (r-2) + bonusesByFile[f] * (r/2 + 1); + Connected[f][r] = make_score(bonus, bonus); + } } -/// Destructor - -PawnInfoTable::~PawnInfoTable() { - delete [] entries; -} +/// 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. +Entry* probe(const Position& pos, Table& entries) { -/// PawnInfo::clear() resets to zero the PawnInfo entry. Note that -/// kingSquares[] is initialized to SQ_NONE instead. + Key key = pos.pawn_key(); + Entry* e = entries[key]; -void PawnInfo::clear() { + if (e->key == key) + return e; - memset(this, 0, sizeof(PawnInfo)); - kingSquares[WHITE] = kingSquares[BLACK] = SQ_NONE; + e->key = key; + e->value = evaluate(pos, e) - evaluate(pos, e); + 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. +/// Entry::shelter_storm() calculates shelter and storm penalties for the file +/// the king is on, as well as the two adjacent files. -PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) { - - assert(pos.is_ok()); +template +Value Entry::shelter_storm(const Position& pos, Square ksq) { - Key key = pos.get_pawn_key(); - int index = int(key & (size - 1)); - PawnInfo* pi = entries + index; + const Color Them = (Us == WHITE ? BLACK : WHITE); - // 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; + Value safety = MaxSafetyBonus; + Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, rank_of(ksq)) | rank_bb(ksq)); + Bitboard ourPawns = b & pos.pieces(Us); + Bitboard theirPawns = b & pos.pieces(Them); + Rank rkUs, rkThem; + File kf = std::max(FILE_B, std::min(FILE_G, file_of(ksq))); - // Clear the PawnInfo object, and set the key - pi->clear(); - pi->key = key; + for (File f = kf - File(1); f <= kf + File(1); ++f) + { + b = ourPawns & file_bb(f); + rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1; + safety -= ShelterWeakness[rkUs]; - // Calculate pawn attacks - Bitboard whitePawns = pos.pieces(PAWN, WHITE); - Bitboard blackPawns = pos.pieces(PAWN, BLACK); - pi->pawnAttacks[WHITE] = ((whitePawns << 9) & ~FileABB) | ((whitePawns << 7) & ~FileHBB); - pi->pawnAttacks[BLACK] = ((blackPawns >> 7) & ~FileABB) | ((blackPawns >> 9) & ~FileHBB); + b = theirPawns & file_bb(f); + rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1; + safety -= StormDanger[rkUs == RANK_1 ? 0 : rkThem == rkUs + 1 ? 2 : 1][rkThem]; + } - // Evaluate pawns for both colors - pi->value = evaluate_pawns(pos, whitePawns, blackPawns, pi) - - evaluate_pawns(pos, blackPawns, whitePawns, pi); - return pi; + return safety; } -/// PawnInfoTable::evaluate_pawns() evaluates each pawn of the given color +/// Entry::update_safety() calculates and caches a bonus for king safety. +/// It is called only when king square changes, which is about 20% of total +/// king_safety() calls. template -Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, - Bitboard theirPawns, PawnInfo* pi) { - Square s; - File f; - Rank r; - bool passed, isolated, doubled, opposed, chain, backward, candidate; - int bonus; - Score value = make_score(0, 0); - const Square* ptr = pos.piece_list_begin(Us, PAWN); - int unpairedPawnsNum = pos.piece_count(Us, PAWN); +Score Entry::update_safety(const Position& pos, Square ksq) { - // Initialize pawn storm scores by giving bonuses for open files - for (f = FILE_A; f <= FILE_H; f++) - if (!(ourPawns & file_bb(f))) - { - pi->ksStormValue[Us] += KStormOpenFileBonus[f]; - pi->qsStormValue[Us] += QStormOpenFileBonus[f]; - pi->halfOpenFiles[Us] |= (1 << f); - } - - // Loop through all pawns of the current color and score each pawn - while ((s = *ptr++) != SQ_NONE) - { - f = square_file(s); - r = square_rank(s); - - assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN)); - - // Passed, isolated or doubled pawn? - passed = !(theirPawns & passed_pawn_mask(Us, s)); - isolated = !(ourPawns & neighboring_files_bb(s)); - doubled = ourPawns & squares_behind(Us, s); - opposed = theirPawns & squares_in_front_of(Us, s); - - // Decrease number of unpaired pawns - if (opposed) - unpairedPawnsNum--; - - // 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[]). Pawns which seem to have good - // chances of creating an open file by exchanging itself against an - // enemy pawn on an adjacent file gets an additional bonus. - - // Kingside pawn storms - bonus = KStormTable[relative_square(Us, s)]; - if (f >= FILE_F) - { - Bitboard b = outpost_mask(Us, s) & theirPawns & (FileFBB | FileGBB | FileHBB); - while (b) - { - // Give a bonus according to the distance of the nearest enemy pawn - Square s2 = pop_1st_bit(&b); - int v = StormLeverBonus[f] - 2 * square_distance(s, s2); - - // If enemy pawn has no pawn beside itself is particularly vulnerable. - // Big bonus, especially against a weakness on the rook file - if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2))) - v *= (square_file(s2) == FILE_H ? 4 : 2); - - bonus += v; - } - } - pi->ksStormValue[Us] += bonus; - - // Queenside pawn storms - bonus = QStormTable[relative_square(Us, s)]; - if (f <= FILE_C) - { - Bitboard b = outpost_mask(Us, s) & theirPawns & (FileABB | FileBBB | FileCBB); - while (b) - { - // Give a bonus according to the distance of the nearest enemy pawn - Square s2 = pop_1st_bit(&b); - int v = StormLeverBonus[f] - 4 * square_distance(s, s2); - - // If enemy pawn has no pawn beside itself is particularly vulnerable. - // Big bonus, especially against a weakness on the rook file - if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2))) - v *= (square_file(s2) == FILE_A ? 4 : 2); - - bonus += v; - } - } - pi->qsStormValue[Us] += bonus; - - // Member of a pawn chain (but not the backward one)? 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 = ourPawns - & neighboring_files_bb(f) - & (rank_bb(r) | rank_bb(r - (Us == WHITE ? 1 : -1))); - - // Test for backward pawn - // - // If the pawn is passed, isolated, or member of a pawn chain - // it cannot be backward. If can capture an enemy pawn or if - // there are friendly pawns behind on neighboring files it cannot - // be backward either. - if ( (passed | isolated | chain) - || (ourPawns & behind_bb(Us, r) & neighboring_files_bb(f)) - || (pos.attacks_from(s, Us) & theirPawns)) - backward = false; - else - { - // We now know that there are 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 = 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; - } + kingSquares[Us] = ksq; + castlingFlags[Us] = pos.can_castle(Us); + minKPdistance[Us] = 0; - // Test for candidate passed pawn - candidate = !passed - && !opposed - && ( count_1s_max_15(neighboring_files_bb(f) & (behind_bb(Us, r) | rank_bb(r)) & ourPawns) - - count_1s_max_15(neighboring_files_bb(f) & in_front_bb(Us, r) & theirPawns) - >= 0); + Bitboard pawns = pos.pieces(Us, PAWN); + if (pawns) + while (!(DistanceRingsBB[ksq][minKPdistance[Us]++] & pawns)) {} - // 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))) - passed = false; + if (relative_rank(Us, ksq) > RANK_4) + return kingSafety[Us] = make_score(0, -16 * minKPdistance[Us]); - // Score this pawn - if (passed) - set_bit(&(pi->passedPawns), s); + Value bonus = shelter_storm(pos, ksq); - if (isolated) - { - value -= IsolatedPawnPenalty[f]; - if (!(theirPawns & file_bb(f))) - value -= IsolatedPawnPenalty[f] / 2; - } - if (doubled) - value -= DoubledPawnPenalty[f]; - - if (backward) - { - value -= BackwardPawnPenalty[f]; - if (!(theirPawns & file_bb(f))) - value -= BackwardPawnPenalty[f] / 2; - } - if (chain) - value += ChainBonus[f]; + // If we can castle use the bonus after the castling if it is bigger + if (pos.can_castle(make_castling_flag(Us, KING_SIDE))) + bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_G1))); - if (candidate) - value += CandidateBonus[relative_rank(Us, s)]; - } + if (pos.can_castle(make_castling_flag(Us, QUEEN_SIDE))) + bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_C1))); - // Calculate a scale factor to be used to evaluate if position is drawish - pi->factor[Us] = UnpairedPawnsTable[unpairedPawnsNum] * PawnsQtyTable[pos.piece_count(Us, PAWN)] / 16; - - return value; + 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); -/// PawnInfo::updateShelter calculates and caches king shelter. It is called -/// only when king square changes, about 20% of total get_king_shelter() calls. -int PawnInfo::updateShelter(const Position& pos, Color c, Square ksq) { - - unsigned shelter = 0; - Bitboard pawns = pos.pieces(PAWN, c) & this_and_neighboring_files_bb(ksq); - unsigned r = ksq & (7 << 3); - for (int i = 1, k = (c ? -8 : 8); i < 4; i++) - { - r += k; - shelter += BitCount8Bit[(pawns >> r) & 0xFF] * (128 >> i); - } - kingSquares[c] = ksq; - kingShelters[c] = shelter; - return shelter; -} +} // namespace Pawns