X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=34c25959ab957e300a4857056f4ca5f23bc4efa2;hp=f06b1283d418a529e8196150a5de85e8b934bd02;hb=66c5835080c8c1dab6bf203d2b6d9db6ab9439cc;hpb=e4277c06bfb783b5ec78001eeef06fa9feae033f diff --git a/src/pawns.cpp b/src/pawns.cpp index f06b1283..34c25959 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) 2008-2009 Marco Costalba + Copyright (C) 2008-2010 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 @@ -38,64 +38,36 @@ namespace { /// Constants and variables - // Doubled pawn penalty by file, middle game - const Value DoubledPawnMidgamePenalty[8] = { - Value(13), Value(20), Value(23), Value(23), - Value(23), Value(23), Value(20), Value(13) - }; - - // Doubled pawn penalty by file, endgame - const Value DoubledPawnEndgamePenalty[8] = { - Value(43), Value(48), Value(48), Value(48), - Value(48), Value(48), Value(48), Value(43) - }; - - // Isolated pawn penalty by file, middle game - const Value IsolatedPawnMidgamePenalty[8] = { - Value(25), Value(36), Value(40), Value(40), - Value(40), Value(40), Value(36), Value(25) - }; - - // Isolated pawn penalty by file, endgame - const Value IsolatedPawnEndgamePenalty[8] = { - Value(30), Value(35), Value(35), Value(35), - Value(35), Value(35), Value(35), Value(30) - }; - - // Backward pawn penalty by file, middle game - const Value BackwardPawnMidgamePenalty[8] = { - Value(20), Value(29), Value(33), Value(33), - Value(33), Value(33), Value(29), Value(20) - }; + #define S(mg, eg) make_score(mg, eg) - // Backward pawn penalty by file, endgame - const Value BackwardPawnEndgamePenalty[8] = { - Value(28), Value(31), Value(31), Value(31), - Value(31), Value(31), Value(31), Value(28) + // 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) }; - // Pawn chain membership bonus by file, middle game - const Value ChainMidgameBonus[8] = { - Value(11), Value(13), Value(13), Value(14), - Value(14), Value(13), Value(13), Value(11) + // 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) }; - // Pawn chain membership bonus by file, endgame - const Value ChainEndgameBonus[8] = { - Value(-1), Value(-1), Value(-1), Value(-1), - Value(-1), Value(-1), Value(-1), Value(-1) + // 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) }; - // Candidate passed pawn bonus by rank, middle game - const Value CandidateMidgameBonus[8] = { - Value( 0), Value( 6), Value(6), Value(14), - Value(34), Value(83), Value(0), Value( 0) + // 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) }; - // Candidate passed pawn bonus by rank, endgame - const Value CandidateEndgameBonus[8] = { - Value( 0), Value( 13), Value(13), Value(29), - Value(68), Value(166), Value( 0), Value( 0) + // 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) }; // Pawn storm tables for positions with opposite castling @@ -122,12 +94,13 @@ namespace { }; // 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 }; + const int16_t QStormOpenFileBonus[8] = { 31, 31, 18, 0, 0, 0, 0, 0 }; + const int16_t KStormOpenFileBonus[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 }; + #undef S } @@ -135,11 +108,10 @@ namespace { //// Functions //// -/// Constructor +/// PawnInfoTable c'tor and d'tor instantiated one each thread -PawnInfoTable::PawnInfoTable(unsigned numOfEntries) { +PawnInfoTable::PawnInfoTable(unsigned numOfEntries) : size(numOfEntries) { - size = numOfEntries; entries = new PawnInfo[size]; if (!entries) { @@ -150,9 +122,8 @@ PawnInfoTable::PawnInfoTable(unsigned numOfEntries) { } -/// Destructor - PawnInfoTable::~PawnInfoTable() { + delete [] entries; } @@ -168,16 +139,16 @@ void PawnInfo::clear() { /// 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. +/// 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) { +PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const { assert(pos.is_ok()); Key key = pos.get_pawn_key(); - int index = int(key & (size - 1)); + unsigned index = unsigned(key & (size - 1)); PawnInfo* pi = entries + index; // If pi->key matches the position's pawn hash key, it means that we @@ -190,210 +161,183 @@ PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) { pi->clear(); pi->key = key; - Value mgValue[2] = {Value(0), Value(0)}; - Value egValue[2] = {Value(0), Value(0)}; + // 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); - // Loop through the pawns for both colors - for (Color us = WHITE; us <= BLACK; us++) - { - Color them = opposite_color(us); - Bitboard ourPawns = pos.pieces(PAWN, us); - Bitboard theirPawns = pos.pieces(PAWN, them); - Bitboard pawns = ourPawns; - - // Initialize pawn storm scores by giving bonuses for open files - for (File f = FILE_A; f <= FILE_H; f++) - if (!(pawns & 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 (pawns) - { - Square s = pop_1st_bit(&pawns); - File f = square_file(s); - Rank r = square_rank(s); - - assert(pos.piece_on(s) == piece_of_color_and_type(us, PAWN)); - - // Passed, isolated or doubled pawn? - bool passed = Position::pawn_is_passed(theirPawns, us, s); - bool isolated = Position::pawn_is_isolated(ourPawns, s); - bool doubled = Position::pawn_is_doubled(ourPawns, us, s); - - // 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 - int bonus = KStormTable[relative_square(us, s)]; - if (f >= FILE_F) - { - Bitboard b = outpost_mask(us, s) & theirPawns & (FileFBB | FileGBB | FileHBB); - while (b) - { - Square s2 = pop_1st_bit(&b); - if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2))) - { - // The enemy pawn has no pawn beside itself, which makes it - // particularly vulnerable. Big bonus, especially against a - // weakness on the rook file. - if (square_file(s2) == FILE_H) - bonus += 4*StormLeverBonus[f] - 8*square_distance(s, s2); - else - bonus += 2*StormLeverBonus[f] - 4*square_distance(s, s2); - } else - // There is at least one enemy pawn beside the enemy pawn we look - // at, which means that the pawn has somewhat better chances of - // defending itself by advancing. Smaller bonus. - bonus += StormLeverBonus[f] - 2*square_distance(s, s2); - } - } - 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) - { - Square s2 = pop_1st_bit(&b); - if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2))) - { - // The enemy pawn has no pawn beside itself, which makes it - // particularly vulnerable. Big bonus, especially against a - // weakness on the rook file. - if (square_file(s2) == FILE_A) - bonus += 4*StormLeverBonus[f] - 16*square_distance(s, s2); - else - bonus += 2*StormLeverBonus[f] - 8*square_distance(s, s2); - } else - // There is at least one enemy pawn beside the enemy pawn we look - // at, which means that the pawn has somewhat better chances of - // defending itself by advancing. Smaller bonus. - bonus += StormLeverBonus[f] - 4*square_distance(s, s2); - } - } - 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. - bool 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. - bool backward; - if ( passed - || isolated - || chain - || (pos.attacks_from(s, us) & theirPawns) - || (ourPawns & behind_bb(us, r) & neighboring_files_bb(f))) - 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); - if (us == WHITE) - { - for ( ; !(b & (ourPawns | theirPawns)); b <<= 8); - backward = (b | (b << 8)) & theirPawns; - } - else - { - for ( ; !(b & (ourPawns | theirPawns)); b >>= 8); - backward = (b | (b >> 8)) & theirPawns; - } - } - - // Test for candidate passed pawn - bool candidate; - candidate = !passed - && !(theirPawns & file_bb(f)) - && ( 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); - - // 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; - - // Score this pawn - if (passed) - set_bit(&(pi->passedPawns), s); - - if (isolated) - { - mgValue[us] -= IsolatedPawnMidgamePenalty[f]; - egValue[us] -= IsolatedPawnEndgamePenalty[f]; - if (!(theirPawns & file_bb(f))) - { - mgValue[us] -= IsolatedPawnMidgamePenalty[f] / 2; - egValue[us] -= IsolatedPawnEndgamePenalty[f] / 2; - } - } - if (doubled) - { - mgValue[us] -= DoubledPawnMidgamePenalty[f]; - egValue[us] -= DoubledPawnEndgamePenalty[f]; - } - if (backward) - { - mgValue[us] -= BackwardPawnMidgamePenalty[f]; - egValue[us] -= BackwardPawnEndgamePenalty[f]; - if (!(theirPawns & file_bb(f))) - { - mgValue[us] -= BackwardPawnMidgamePenalty[f] / 2; - egValue[us] -= BackwardPawnEndgamePenalty[f] / 2; - } - } - if (chain) - { - mgValue[us] += ChainMidgameBonus[f]; - egValue[us] += ChainEndgameBonus[f]; - } - if (candidate) - { - mgValue[us] += CandidateMidgameBonus[relative_rank(us, s)]; - egValue[us] += CandidateEndgameBonus[relative_rank(us, s)]; - } - } // while(pawns) - } // for(colors) - - pi->mgValue = int16_t(mgValue[WHITE] - mgValue[BLACK]); - pi->egValue = int16_t(egValue[WHITE] - egValue[BLACK]); + // Evaluate pawns for both colors + pi->value = evaluate_pawns(pos, whitePawns, blackPawns, pi) + - evaluate_pawns(pos, blackPawns, whitePawns, pi); return pi; } +/// PawnInfoTable::evaluate_pawns() evaluates each pawn of the given color + +template +Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, + Bitboard theirPawns, PawnInfo* pi) const { + Bitboard b; + Square s; + File f; + Rank r; + int bonus; + bool passed, isolated, doubled, opposed, chain, backward, candidate; + Score value = make_score(0, 0); + const Square* ptr = pos.piece_list_begin(Us, PAWN); + + // 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)); + + // Calculate kingside and queenside pawn storm scores for both colors to be + // used when evaluating middle game positions with opposite side castling. + bonus = (f >= FILE_F ? evaluate_pawn_storm(s, r, f, theirPawns) : 0); + pi->ksStormValue[Us] += KStormTable[relative_square(Us, s)] + bonus; + + bonus = (f <= FILE_C ? evaluate_pawn_storm(s, r, f, theirPawns) : 0); + pi->qsStormValue[Us] += QStormTable[relative_square(Us, s)] + bonus; + + // Our rank plus previous one. Used for chain detection. + b = rank_bb(r) | rank_bb(r + (Us == WHITE ? -1 : 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); + opposed = theirPawns & squares_in_front_of(Us, s); + isolated = !(ourPawns & neighboring_files_bb(f)); + chain = ourPawns & neighboring_files_bb(f) & b; + + // 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 & attack_span_mask(opposite_color(Us), 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 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. + 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(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_max_15(b) >= count_1s_max_15(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; + + // 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), s); + + // Score this pawn + if (isolated) + { + value -= IsolatedPawnPenalty[f]; + if (!opposed) + value -= IsolatedPawnPenalty[f] / 2; + } + if (doubled) + value -= DoubledPawnPenalty[f]; + + if (backward) + { + value -= BackwardPawnPenalty[f]; + if (!opposed) + value -= BackwardPawnPenalty[f] / 2; + } + if (chain) + value += ChainBonus[f]; + + if (candidate) + value += CandidateBonus[relative_rank(Us, s)]; + } + + return value; +} + + +/// PawnInfoTable::evaluate_pawn_storm() evaluates each pawn which seems +/// to have good chances of creating an open file by exchanging itself +/// against an enemy pawn on an adjacent file. + +template +int PawnInfoTable::evaluate_pawn_storm(Square s, Rank r, File f, Bitboard theirPawns) const { + + const Bitboard StormFilesBB = (Side == KingSide ? FileFBB | FileGBB | FileHBB + : FileABB | FileBBB | FileCBB); + const int K = (Side == KingSide ? 2 : 4); + const File RookFile = (Side == KingSide ? FILE_H : FILE_A); + + Bitboard b = attack_span_mask(Us, s) & theirPawns & StormFilesBB; + int bonus = 0; + + while (b) + { + // Give a bonus according to the distance of the nearest enemy pawn + Square s2 = pop_1st_bit(&b); + Rank r2 = square_rank(s2); + int v = StormLeverBonus[f] - K * rank_distance(r, r2); + + // 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) == RookFile ? 4 : 2); + + bonus += v; + } + return bonus; +} + + /// 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 shelter = 0; unsigned r = ksq & (7 << 3); + for (int i = 1, k = (c ? -8 : 8); i < 4; i++) { r += k;