X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=7fd4ac071490dea47b3dc812bf968cc0d15e94b9;hp=07decab1fd4c52e9c490f5468c5f4c94d9d73b31;hb=d549497144ee2a704057e005d2bbe1fbc666ca7e;hpb=d4876dc96395f5592bfbc25b2eca2360db0655e6 diff --git a/src/pawns.cpp b/src/pawns.cpp index 07decab1..7fd4ac07 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) 2008-2012 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 @@ -17,46 +17,38 @@ along with this program. If not, see . */ - -//// -//// Includes -//// - #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] = { - 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) - }; + // 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] = { @@ -70,125 +62,113 @@ namespace { S(34,68), S(83,166), S(0, 0), S( 0, 0) }; - #undef S -} + 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) } }; -//// -//// Functions -//// + // 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) } }; -/// PawnInfoTable c'tor and d'tor instantiated one each thread + // 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); -PawnInfoTable::PawnInfoTable() { - - entries = new PawnInfo[PawnTableSize]; - - if (!entries) - { - std::cerr << "Failed to allocate " << (PawnTableSize * sizeof(PawnInfo)) - << " bytes for pawn hash table." << std::endl; - Application::exit_with_failure(); - } + #undef S + #undef V } -PawnInfoTable::~PawnInfoTable() { +/// 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. - delete [] entries; -} +PawnEntry* PawnTable::probe(const Position& pos) { + + Key key = pos.pawn_key(); + PawnEntry* 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::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. + 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; -PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const { + Bitboard wPawns = pos.pieces(PAWN, WHITE); + Bitboard bPawns = pos.pieces(PAWN, BLACK); + e->pawnAttacks[WHITE] = ((wPawns & ~FileHBB) << 9) | ((wPawns & ~FileABB) << 7); + e->pawnAttacks[BLACK] = ((bPawns & ~FileHBB) >> 7) | ((bPawns & ~FileABB) >> 9); - assert(pos.is_ok()); + e->value = evaluate_pawns(pos, wPawns, bPawns, e) + - evaluate_pawns(pos, bPawns, wPawns, e); - Key key = pos.get_pawn_key(); - unsigned index = unsigned(key & (PawnTableSize - 1)); - PawnInfo* pi = entries + index; + e->value = apply_weight(e->value, PawnStructureWeight); - // 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 - memset(pi, 0, sizeof(PawnInfo)); - pi->kingSquares[WHITE] = pi->kingSquares[BLACK] = SQ_NONE; - pi->key = key; - - // 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); - - // Evaluate pawns for both colors - pi->value = evaluate_pawns(pos, whitePawns, blackPawns, pi) - - evaluate_pawns(pos, blackPawns, whitePawns, pi); - return pi; + return e; } -/// PawnInfoTable::evaluate_pawns() evaluates each pawn of the given color +/// PawnTable::evaluate_pawns() evaluates each pawn of the given color template -Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, - Bitboard theirPawns, PawnInfo* pi) const { +Score PawnTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, + Bitboard theirPawns, PawnEntry* e) { + + const Color Them = (Us == WHITE ? BLACK : WHITE); + Bitboard b; Square s; File f; Rank r; bool passed, isolated, doubled, opposed, chain, backward, candidate; Score value = SCORE_ZERO; - const BitCountType Max15 = CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15; - const Square* ptr = pos.piece_list_begin(Us, PAWN); - - // Initialize halfOpenFiles[] - for (f = FILE_A; f <= FILE_H; f++) - if (!(ourPawns & file_bb(f))) - pi->halfOpenFiles[Us] |= (1 << f); + const Square* pl = pos.piece_list(Us, PAWN); // Loop through all pawns of the current color and score each pawn - while ((s = *ptr++) != SQ_NONE) + while ((s = *pl++) != SQ_NONE) { - assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN)); + assert(pos.piece_on(s) == make_piece(Us, PAWN)); + + f = file_of(s); + r = rank_of(s); - f = square_file(s); - r = square_rank(s); + // This file cannot be half open + e->halfOpenFiles[Us] &= ~(1 << f); - // Our rank plus previous one. Used for chain detection. + // Our rank plus previous one. Used for chain detection b = rank_bb(r) | rank_bb(Us == WHITE ? r - Rank(1) : r + Rank(1)); - // Passed, isolated, doubled or member of a pawn - // chain (but not the backward one) ? - passed = !(theirPawns & passed_pawn_mask(Us, s)); - doubled = ourPawns & squares_behind(Us, s); + // 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 & squares_in_front_of(Us, s); opposed = theirPawns & squares_in_front_of(Us, s); - isolated = !(ourPawns & neighboring_files_bb(f)); - chain = ourPawns & neighboring_files_bb(f) & b; + 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 can capture an enemy pawn or if - // there are friendly pawns behind on neighboring files it cannot - // be backward either. + // 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(opposite_color(Us), s)) + && !(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 neighboring files. We now check whether the pawn is - // backward by looking in the forward direction on the neighboring + // 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); @@ -197,45 +177,37 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, 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. + // 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(passed | opposed | (attack_span_mask(Us, s) & theirPawns)); - - // Test for candidate passed pawn - candidate = !(opposed | passed) - && (b = attack_span_mask(opposite_color(Us), s + pawn_push(Us)) & ourPawns) != EmptyBoardBB - && count_1s(b) >= count_1s(attack_span_mask(Us, s) & theirPawns); + assert(opposed | passed | (attack_span_mask(Us, s) & theirPawns)); - // 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; + // 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); - // Mark the pawn as passed. Pawn will be properly scored in evaluation - // because we need full attack info to evaluate passed pawns. - if (passed) - set_bit(&(pi->passedPawns[Us]), s); + // 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[f]; - if (!opposed) - value -= IsolatedPawnPenalty[f] / 2; - } + value -= IsolatedPawnPenalty[opposed][f]; + if (doubled) - value -= DoubledPawnPenalty[f]; + value -= DoubledPawnPenalty[opposed][f]; if (backward) - { - value -= BackwardPawnPenalty[f]; - if (!opposed) - value -= BackwardPawnPenalty[f] / 2; - } + value -= BackwardPawnPenalty[opposed][f]; + if (chain) value += ChainBonus[f]; @@ -246,3 +218,64 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, return value; } + +/// PawnEntry::shelter_storm() calculates shelter and storm penalties for the file +/// the king is on, as well as the two adjacent 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); + Bitboard theirPawns = b & pos.pieces(Them); + Rank rkUs, rkThem; + File kf = file_of(ksq); + + kf = (kf == FILE_A) ? kf++ : (kf == FILE_H) ? kf-- : kf; + + 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 ? 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]; + } + + 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. + +template +Score PawnEntry::update_safety(const Position& pos, Square ksq) { + + kingSquares[Us] = ksq; + + if (relative_rank(Us, ksq) > RANK_4) + return kingSafety[Us] = SCORE_ZERO; + + 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, 0); +} + +// Explicit template instantiation +template Score PawnEntry::update_safety(const Position& pos, Square ksq); +template Score PawnEntry::update_safety(const Position& pos, Square ksq);