X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fpawns.cpp;h=997aa2148815142da303cab5acb499bd78d0d6e9;hb=255df4ffae29f4a038c9881c1f2f675e2f21f71e;hp=e01062d67ee6244c68cb440228a28aff432987ab;hpb=23490bd825d60564b1368b6a7e3df7d86a772bf0;p=stockfish diff --git a/src/pawns.cpp b/src/pawns.cpp index e01062d6..2378b532 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -1,384 +1,275 @@ /* 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) 2008-2015 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 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 -#include +#include "bitboard.h" #include "pawns.h" +#include "position.h" +#include "thread.h" +namespace { -//// -//// Local definitions -//// + #define V Value + #define S(mg, eg) make_score(mg, eg) -namespace { + // Isolated pawn penalty + constexpr Score Isolated = S(13, 16); - /// Constants and variables + // Backward pawn penalty + constexpr Score Backward = S(17, 11); - // 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) - }; + // Connected pawn bonus by opposed, phalanx, #support and rank + Score Connected[2][2][3][RANK_NB]; - // 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) - }; + // Doubled pawn penalty + constexpr Score Doubled = S(13, 40); - // 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) + // Strength of pawn shelter for our king by [distance from edge][rank]. + // RANK_1 = 0 is used for files where we have no pawn, or pawn is behind our king. + constexpr Value ShelterStrength[int(FILE_NB) / 2][RANK_NB] = { + { V( 7), V(76), V(84), V( 38), V( 7), V( 30), V(-19) }, + { V(-3), V(93), V(52), V(-17), V(12), V(-22), V(-35) }, + { V(-6), V(83), V(25), V(-24), V(15), V( 22), V(-39) }, + { V(11), V(83), V(19), V( 8), V(18), V(-21), V(-30) } }; - // 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) + // Danger of enemy pawns moving toward our king by [type][distance from edge][rank]. + // For the unblocked case, RANK_1 = 0 is used when opponent has no pawn on the + // given file, or their pawn is behind our king. + constexpr Value StormDanger[][4][RANK_NB] = { + { { V(25), V( 79), V(107), V( 51), V( 27) }, // UnBlocked + { V(15), V( 45), V(131), V( 8), V( 25) }, + { V( 0), V( 42), V(118), V( 56), V( 27) }, + { V( 3), V( 54), V(110), V( 55), V( 26) } }, + { { V( 0), V( 0), V( 37), V( 5), V(-48) }, // BlockedByPawn + { V( 0), V( 0), V( 68), V(-12), V( 13) }, + { V( 0), V( 0), V(111), V(-25), V( -3) }, + { V( 0), V( 0), V(108), V( 14), V( 21) } } }; - // 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) - }; + #undef S + #undef V - // 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) - }; + template + Score evaluate(const Position& pos, Pawns::Entry* e) { - // 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) - }; + constexpr Color Them = (Us == WHITE ? BLACK : WHITE); + constexpr Direction Up = (Us == WHITE ? NORTH : SOUTH); - // 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) - }; + 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); - // 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) - }; + Bitboard ourPawns = pos.pieces( Us, PAWN); + Bitboard theirPawns = pos.pieces(Them, PAWN); - // 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) - }; + 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]; - // 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)); + + 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. + backward = !(ourPawns & pawn_attack_span(Them, s + Up)) + && (stoppers & (leverPush | (s + Up))); + + // 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) - 1 + && 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; + } - // Pawn storm open file bonuses by file: - const int KStormOpenFileBonus[8] = { - 45, 45, 30, 0, 0, 0, 0, 0 - }; + // Score this pawn + if (supported | phalanx) + score += Connected[opposed][bool(phalanx)][popcount(supported)][relative_rank(Us, s)]; - const int QStormOpenFileBonus[8] = { - 0, 0, 0, 0, 0, 30, 45, 30 - }; + 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; + } + +} // namespace -//// -//// Functions -//// +namespace Pawns { -/// Constructor +/// 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. -PawnInfoTable::PawnInfoTable(unsigned numOfEntries) { +void init() { - size = numOfEntries; - entries = new PawnInfo[size]; - if (entries == NULL) + static constexpr int Seed[RANK_NB] = { 0, 13, 24, 18, 65, 100, 175, 330 }; + + 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) { - std::cerr << "Failed to allocate " << (numOfEntries * sizeof(PawnInfo)) - << " bytes for pawn hash table." << std::endl; - exit(EXIT_FAILURE); + int v = 17 * support; + v += (Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0)) >> opposed; + + Connected[opposed][phalanx][support][r] = make_score(v, v * (r - 2) / 4); } - clear(); } -/// Destructor +/// 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. -PawnInfoTable::~PawnInfoTable() { - delete [] entries; -} +Entry* probe(const Position& pos) { + Key key = pos.pawn_key(); + Entry* e = pos.this_thread()->pawnsTable[key]; -/// PawnInfoTable::clear() clears the pawn hash table by setting all -/// entries to 0. + if (e->key == key) + return e; -void PawnInfoTable::clear() { - memset(entries, 0, size * sizeof(PawnInfo)); -} + 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 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) { +/// Entry::evaluate_shelter() calculates the shelter bonus and the storm +/// penalty for a king, looking at the king file and the two closest files. - assert(pos.is_ok()); +template +Value Entry::evaluate_shelter(const Position& pos, Square ksq) { - Key key = pos.get_pawn_key(); - int index = int(key & (size - 1)); - PawnInfo *pi = entries + index; + enum { UnBlocked, BlockedByPawn }; + constexpr Color Them = (Us == WHITE ? BLACK : WHITE); + constexpr Direction Down = (Us == WHITE ? SOUTH : NORTH); + constexpr Bitboard BlockRanks = (Us == WHITE ? Rank1BB | Rank2BB : Rank8BB | Rank7BB); - // 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; + Bitboard b = pos.pieces(PAWN) & (forward_ranks_bb(Us, ksq) | rank_bb(ksq)); + Bitboard ourPawns = b & pos.pieces(Us); + Bitboard theirPawns = b & pos.pieces(Them); - // Clear the PawnInfo object, and set the key - pi->clear(); - pi->key = key; + Value safety = (ourPawns & file_bb(ksq)) ? Value(5) : Value(-5); - Value mgValue[2] = {Value(0), Value(0)}; - Value egValue[2] = {Value(0), Value(0)}; + if (shift(theirPawns) & (FileABB | FileHBB) & BlockRanks & ksq) + safety += Value(374); - // Loop through the pawns for both colors - for (Color us = WHITE; us <= BLACK; us++) + File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq))); + for (File f = File(center - 1); f <= File(center + 1); ++f) { - 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 - 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]; - } + b = ourPawns & file_bb(f); + int ourRank = b ? relative_rank(Us, backmost_sq(Us, b)) : 0; - // Loop through all pawns of the current color and score each pawn - while (pawns) - { - bool passed, doubled, isolated, backward, chain, candidate; - Square s = pop_1st_bit(&pawns); - File f = square_file(s); - Rank r = square_rank(s); - - 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); - - // 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 and queenside pawn storms - int KBonus = KStormTable[relative_square(us, s)]; - int QBonus = QStormTable[relative_square(us, s)]; - bool outPostFlag = (KBonus > 0 && (outpost_mask(us, s) & theirPawns)); - bool passedFlag = (QBonus > 0 && (passed_pawn_mask(us, s) & theirPawns)); - - switch (f) { - - case FILE_A: - QBonus += passedFlag * QBonus / 2; - break; - - case FILE_B: - QBonus += passedFlag * (QBonus / 2 + QBonus / 4); - break; - - case FILE_C: - QBonus += passedFlag * QBonus / 2; - break; - - case FILE_F: - KBonus += outPostFlag * KBonus / 4; - break; - - case FILE_G: - KBonus += outPostFlag * (KBonus / 2 + KBonus / 4); - break; - - case FILE_H: - KBonus += outPostFlag * KBonus / 2; - break; - - default: - break; - } - pi->ksStormValue[us] += KBonus; - pi->qsStormValue[us] += QBonus; - - // 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 - || (pos.pawn_attacks(us, s) & 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; - 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; - } - } + b = theirPawns & file_bb(f); + int theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : 0; - // Test for candidate passed pawn - candidate = !passed - && pos.file_is_half_open(them, 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))) - { - // candidate = true; - passed = false; - } + int d = std::min(f, ~f); - // 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)]; - } + safety += ShelterStrength[d][ourRank]; + if (ourRank || theirRank) + safety -= StormDanger[ourRank && (ourRank == theirRank - 1) ? BlockedByPawn : UnBlocked][d][theirRank]; + } + + return safety; +} + + +/// 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. - 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); - } // while(pawns) - } // for(colors) - - pi->mgValue = int16_t(mgValue[WHITE] - mgValue[BLACK]); - pi->egValue = int16_t(egValue[WHITE] - egValue[BLACK]); - return pi; +template +Score Entry::do_king_safety(const Position& pos, Square ksq) { + + kingSquares[Us] = ksq; + castlingRights[Us] = pos.can_castle(Us); + int minKingPawnDistance = 0; + + Bitboard pawns = pos.pieces(Us, PAWN); + if (pawns) + while (!(DistanceRingBB[ksq][minKingPawnDistance++] & pawns)) {} + + Value bonus = evaluate_shelter(pos, ksq); + + // If we can castle use the bonus after the castling if it is bigger + if (pos.can_castle(MakeCastling::right)) + bonus = std::max(bonus, evaluate_shelter(pos, relative_square(Us, SQ_G1))); + + if (pos.can_castle(MakeCastling::right)) + bonus = std::max(bonus, evaluate_shelter(pos, relative_square(Us, SQ_C1))); + + return make_score(bonus, -16 * minKingPawnDistance); } + +// Explicit template instantiation +template Score Entry::do_king_safety(const Position& pos, Square ksq); +template Score Entry::do_king_safety(const Position& pos, Square ksq); + +} // namespace Pawns