X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=5c33577445dc22e6e1e8a69c4ae9a081e6b77f22;hp=3634f95746796afef7ab904856629b59d2c970fa;hb=2e21aba8d937bdf5eb0eedeac99ac2c2553e9d0d;hpb=79fa72f392343fb93c16c133dedc3dbdf795e746 diff --git a/src/pawns.cpp b/src/pawns.cpp index 3634f957..5c335774 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -1,7 +1,8 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad + 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 @@ -21,59 +22,65 @@ #include #include "bitboard.h" -#include "bitcount.h" #include "pawns.h" #include "position.h" +#include "thread.h" namespace { #define V Value #define S(mg, eg) make_score(mg, eg) - // Doubled pawn penalty by file - 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 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 opposed, phalanx flags and rank - Score Connected[2][2][RANK_NB]; - - // Levers bonus by rank - const Score Lever[RANK_NB] = { - S( 0, 0), S( 0, 0), S(0, 0), S(0, 0), - S(20,20), S(40,40), S(0, 0), S(0, 0) }; - - // Unsupported pawn penalty - const Score UnsupportedPawnPenalty = S(20, 10); - - // 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[][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(160), V(25), V(13) } }; + // Isolated pawn penalty + const Score Isolated = S(13, 18); + + // Backward pawn penalty + const Score Backward = S(24, 12); + + // Connected pawn bonus by opposed, phalanx, #support and rank + Score Connected[2][2][3][RANK_NB]; + + // Doubled pawn penalty + const Score Doubled = S(18, 38); + + // Weakness of our pawn shelter in front of the king by [isKingFile][distance from edge][rank]. + // RANK_1 = 0 is used for files where we have no pawns or our pawn is behind our king. + const Value ShelterWeakness[][int(FILE_NB) / 2][RANK_NB] = { + { { V( 98), V(20), V(11), V(42), V( 83), V( 84), V(101) }, // Not On King file + { V(103), V( 8), V(33), V(86), V( 87), V(105), V(113) }, + { V(100), V( 2), V(65), V(95), V( 59), V( 89), V(115) }, + { V( 72), V( 6), V(52), V(74), V( 83), V( 84), V(112) } }, + { { V(105), V(19), V( 3), V(27), V( 85), V( 93), V( 84) }, // On King file + { V(121), V( 7), V(33), V(95), V(112), V( 86), V( 72) }, + { V(121), V(26), V(65), V(90), V( 65), V( 76), V(117) }, + { V( 79), V( 0), V(45), V(65), V( 94), V( 92), V(105) } } + }; + + // Danger of enemy pawns moving toward our king by [type][distance from edge][rank]. + // For the unopposed and unblocked cases, RANK_1 = 0 is used when opponent has + // no pawn on the given file, or their pawn is behind our king. + const Value StormDanger[][4][RANK_NB] = { + { { V( 0), V(-290), V(-274), V(57), V(41) }, // BlockedByKing + { V( 0), V( 60), V( 144), V(39), V(13) }, + { V( 0), V( 65), V( 141), V(41), V(34) }, + { V( 0), V( 53), V( 127), V(56), V(14) } }, + { { V( 4), V( 73), V( 132), V(46), V(31) }, // Unopposed + { V( 1), V( 64), V( 143), V(26), V(13) }, + { V( 1), V( 47), V( 110), V(44), V(24) }, + { V( 0), V( 72), V( 127), V(50), V(31) } }, + { { V( 0), V( 0), V( 79), V(23), V( 1) }, // BlockedByPawn + { V( 0), V( 0), V( 148), V(27), V( 2) }, + { V( 0), V( 0), V( 161), V(16), V( 1) }, + { V( 0), V( 0), V( 171), V(22), V(15) } }, + { { V(22), V( 45), V( 104), V(62), V( 6) }, // Unblocked + { V(31), V( 30), V( 99), V(39), V(19) }, + { V(23), V( 29), V( 96), V(41), V(15) }, + { V(21), V( 23), V( 116), V(41), V(15) } } + }; // 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); + const Value MaxSafetyBonus = V(258); #undef S #undef V @@ -81,26 +88,24 @@ namespace { 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); + const Color Them = (Us == WHITE ? BLACK : WHITE); + const Direction Up = (Us == WHITE ? NORTH : SOUTH); - Bitboard b, p, doubled, connected; + Bitboard b, neighbours, stoppers, doubled, supported, phalanx; + Bitboard lever, leverPush; Square s; - bool passed, isolated, opposed, phalanx, backward, unsupported, lever; - Score value = SCORE_ZERO; - const Square* pl = pos.list(Us); - const Bitboard* pawnAttacksBB = StepAttacksBB[make_piece(Us, PAWN)]; + bool opposed, backward; + Score score = SCORE_ZERO; + const Square* pl = pos.squares(Us); - Bitboard ourPawns = pos.pieces(Us , PAWN); + Bitboard ourPawns = pos.pieces( Us, PAWN); Bitboard theirPawns = pos.pieces(Them, PAWN); - e->passedPawns[Us] = 0; - e->kingSquares[Us] = SQ_NONE; + e->passedPawns[Us] = e->pawnAttacksSpan[Us] = e->weakUnopposed[Us] = 0; e->semiopenFiles[Us] = 0xFF; - e->pawnAttacks[Us] = shift_bb(ourPawns) | shift_bb(ourPawns); - e->pawnsOnSquares[Us][BLACK] = popcount(ourPawns & DarkSquares); + 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]; // Loop through all pawns of the current color and score each pawn @@ -110,150 +115,155 @@ namespace { File f = file_of(s); - // This file cannot be semi-open - e->semiopenFiles[Us] &= ~(1 << f); - - // Previous rank - p = rank_bb(s - pawn_push(Us)); - - // Flag the pawn as passed, isolated, doubled, - // unsupported or connected (but not the backward one). - connected = ourPawns & adjacent_files_bb(f) & (rank_bb(s) | p); - phalanx = connected & rank_bb(s); - unsupported = !(ourPawns & adjacent_files_bb(f) & p); - 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)); - lever = theirPawns & pawnAttacksBB[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)) + 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. + if (!neighbours || lever || relative_rank(Us, s) >= RANK_5) 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; - } + // Find the backmost rank with neighbours or stoppers + b = rank_bb(backmost_sq(Us, neighbours | stoppers)); + + // The pawn is backward when it cannot safely progress to that rank: + // either there is a stopper in the way on this rank, or there is a + // stopper on adjacent file which controls the way to that rank. + backward = (b | shift(b & adjacent_files_bb(f))) & stoppers; - assert(opposed | passed | (pawn_attack_span(Us, s) & theirPawns)); + assert(!(backward && (forward_ranks_bb(Them, s + Up) & neighbours))); + } // 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) + // 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) + && popcount(phalanx) >= popcount(leverPush)) e->passedPawns[Us] |= s; - // Score this pawn - if (isolated) - value -= Isolated[opposed][f]; + 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; + } - if (unsupported && !isolated) - value -= UnsupportedPawnPenalty; + if (e->passedPawns[Us] & s) + e->asymmetry++; - if (doubled) - value -= Doubled[f] / rank_distance(s, lsb(doubled)); + // Score this pawn + if (supported | phalanx) + score += Connected[opposed][bool(phalanx)][popcount(supported)][relative_rank(Us, s)]; - if (backward) - value -= Backward[opposed][f]; + else if (!neighbours) + score -= Isolated, e->weakUnopposed[Us] += !opposed; - if (connected) - value += Connected[opposed][phalanx][relative_rank(Us, s)]; + else if (backward) + score -= Backward, e->weakUnopposed[Us] += !opposed; - if (lever) - value += Lever[relative_rank(Us, s)]; + if (doubled && !supported) + score -= Doubled; } - b = e->semiopenFiles[Us] ^ 0xFF; - e->pawnSpan[Us] = b ? int(msb(b) - lsb(b)) : 0; - - return value; + return score; } } // namespace namespace Pawns { -/// init() initializes some tables used by evaluation. Instead of 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. +/// 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. -void init() -{ - static const int Seed[RANK_NB] = { 0, 6, 15, 10, 57, 75, 135, 258 }; +void init() { + + static const int Seed[RANK_NB] = { 0, 13, 24, 18, 76, 100, 175, 330 }; for (int opposed = 0; opposed <= 1; ++opposed) for (int phalanx = 0; phalanx <= 1; ++phalanx) - for (Rank r = RANK_2; r < RANK_8; ++r) - { - int bonus = Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0); - Connected[opposed][phalanx][r] = make_score(bonus / 2, bonus >> opposed); - } + for (int support = 0; support <= 2; ++support) + for (Rank r = RANK_2; r < RANK_8; ++r) + { + 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); + } } -/// probe() takes a position 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. +/// 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. -Entry* probe(const Position& pos, Table& entries) { +Entry* probe(const Position& pos) { Key key = pos.pawn_key(); - Entry* e = entries[key]; + Entry* e = pos.this_thread()->pawnsTable[key]; if (e->key == key) return e; e->key = key; - e->value = evaluate(pos, e) - evaluate(pos, e); + e->asymmetry = 0; + e->scores[WHITE] = evaluate(pos, e); + e->scores[BLACK] = evaluate(pos, e); + e->asymmetry += popcount(e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK]); + e->openFiles = popcount(e->semiopenFiles[WHITE] & e->semiopenFiles[BLACK]); + return e; } /// Entry::shelter_storm() calculates shelter and storm penalties for the file -/// the king is on, as well as the two adjacent files. +/// the king is on, as well as the two closest files. template Value Entry::shelter_storm(const Position& pos, Square ksq) { const Color Them = (Us == WHITE ? BLACK : WHITE); - const Bitboard Edges = (FileABB | FileHBB) & (Rank2BB | Rank3BB); - Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, rank_of(ksq)) | rank_bb(ksq)); + enum { BlockedByKing, Unopposed, BlockedByPawn, Unblocked }; + + 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); Value safety = MaxSafetyBonus; - File kf = std::max(FILE_B, std::min(FILE_G, file_of(ksq))); + File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq))); - for (File f = kf - File(1); f <= kf + File(1); ++f) + for (File f = File(center - 1); f <= File(center + 1); ++f) { b = ourPawns & file_bb(f); Rank rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1; - b = theirPawns & file_bb(f); + b = theirPawns & file_bb(f); Rank rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1; - if ( (Edges & make_square(f, rkThem)) - && file_of(ksq) == f - && relative_rank(Us, ksq) == rkThem - 1) - safety += 200; - else - safety -= ShelterWeakness[rkUs] - + StormDanger[rkUs == RANK_1 ? 0 : - rkThem != rkUs + 1 ? 1 : 2][rkThem]; + int d = std::min(f, ~f); + safety -= ShelterWeakness[f == file_of(ksq)][d][rkUs] + + StormDanger + [f == file_of(ksq) && rkThem == relative_rank(Us, ksq) + 1 ? BlockedByKing : + rkUs == RANK_1 ? Unopposed : + rkThem == rkUs + 1 ? BlockedByPawn : Unblocked] + [d][rkThem]; } return safety; @@ -268,14 +278,11 @@ Score Entry::do_king_safety(const Position& pos, Square ksq) { kingSquares[Us] = ksq; castlingRights[Us] = pos.can_castle(Us); - minKPdistance[Us] = 0; + int minKingPawnDistance = 0; Bitboard pawns = pos.pieces(Us, PAWN); if (pawns) - while (!(DistanceRingsBB[ksq][minKPdistance[Us]++] & pawns)) {} - - if (relative_rank(Us, ksq) > RANK_4) - return make_score(0, -16 * minKPdistance[Us]); + while (!(DistanceRingBB[ksq][minKingPawnDistance++] & pawns)) {} Value bonus = shelter_storm(pos, ksq); @@ -286,7 +293,7 @@ Score Entry::do_king_safety(const Position& pos, Square ksq) { if (pos.can_castle(MakeCastling::right)) bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_C1))); - return make_score(bonus, -16 * minKPdistance[Us]); + return make_score(bonus, -16 * minKingPawnDistance); } // Explicit template instantiation