X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=d3d2ea0f744c531f10eb216a8c817fb6e5e28483;hp=1e5b4f43b9a6560b61d3f496e7b40ed226c8538d;hb=d21e421ad74cff3b157d156d6ea8fdee3634e75b;hpb=328bdd0947ea7903ee1061c8eb60bc3121a4eb19 diff --git a/src/pawns.cpp b/src/pawns.cpp index 1e5b4f43..d3d2ea0f 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -1,8 +1,6 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 - Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad - Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad + Copyright (C) 2004-2020 The Stockfish developers (see AUTHORS file) Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -32,23 +30,29 @@ namespace { #define S(mg, eg) make_score(mg, eg) // Pawn penalties - constexpr Score Backward = S( 9, 24); - constexpr Score BlockedStorm = S(82, 82); - constexpr Score Doubled = S(11, 56); - constexpr Score Isolated = S( 5, 15); - constexpr Score WeakLever = S( 0, 56); - constexpr Score WeakUnopposed = S(13, 27); + constexpr Score Backward = S( 6, 23); + constexpr Score Doubled = S(13, 53); + constexpr Score Isolated = S( 2, 15); + constexpr Score WeakLever = S( 5, 57); + constexpr Score WeakUnopposed = S(16, 22); + + // Bonus for blocked pawns at 5th or 6th rank + constexpr Score BlockedPawn[2] = { S(-15, -3), S(-6, 3) }; + + constexpr Score BlockedStorm[RANK_NB] = { + S(0, 0), S(0, 0), S(75, 78), S(-8, 16), S(-6, 10), S(-6, 6), S(0, 2) + }; // Connected pawn bonus - constexpr int Connected[RANK_NB] = { 0, 7, 8, 12, 29, 48, 86 }; + constexpr int Connected[RANK_NB] = { 0, 5, 7, 11, 24, 48, 86 }; // 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( -6), V( 81), V( 93), V( 58), V( 39), V( 18), V( 25) }, - { V(-43), V( 61), V( 35), V(-49), V(-29), V(-11), V( -63) }, - { V(-10), V( 75), V( 23), V( -2), V( 32), V( 3), V( -45) }, - { V(-39), V(-13), V(-29), V(-52), V(-48), V(-67), V(-166) } + { V( -5), V( 82), V( 92), V( 54), V( 36), V( 22), V( 28) }, + { V(-44), V( 63), V( 33), V(-50), V(-30), V(-12), V( -62) }, + { V(-11), V( 77), V( 22), V( -6), V( 31), V( 8), V( -45) }, + { V(-39), V(-12), V(-29), V(-50), V(-43), V(-68), V(-164) } }; // Danger of enemy pawns moving toward our king by [distance from edge][rank]. @@ -56,81 +60,91 @@ namespace { // is behind our king. Note that UnblockedStorm[0][1-2] accommodate opponent pawn // on edge, likely blocked by our king. constexpr Value UnblockedStorm[int(FILE_NB) / 2][RANK_NB] = { - { V( 89), V(-285), V(-185), V(93), V(57), V( 45), V( 51) }, - { V( 44), V( -18), V( 123), V(46), V(39), V( -7), V( 23) }, - { V( 4), V( 52), V( 162), V(37), V( 7), V(-14), V( -2) }, - { V(-10), V( -14), V( 90), V(15), V( 2), V( -7), V(-16) } + { V( 87), V(-288), V(-168), V( 96), V( 47), V( 44), V( 46) }, + { V( 42), V( -25), V( 120), V( 45), V( 34), V( -9), V( 24) }, + { V( -8), V( 51), V( 167), V( 35), V( -4), V(-16), V(-12) }, + { V(-17), V( -13), V( 100), V( 4), V( 9), V(-16), V(-31) } }; + + // KingOnFile[semi-open Us][semi-open Them] contains bonuses/penalties + // for king when the king is on a semi-open or open file. + constexpr Score KingOnFile[2][2] = {{ S(-21,10), S(-7, 1) }, + { S( 0,-3), S( 9,-4) }}; + #undef S #undef V + + /// evaluate() calculates a score for the static pawn structure of the given position. + /// We cannot use the location of pieces or king in this function, as the evaluation + /// of the pawn structure will be stored in a small cache for speed reasons, and will + /// be re-used even when the pieces have moved. + template Score evaluate(const Position& pos, Pawns::Entry* e) { - constexpr Color Them = (Us == WHITE ? BLACK : WHITE); - constexpr Direction Up = (Us == WHITE ? NORTH : SOUTH); + constexpr Color Them = ~Us; + constexpr Direction Up = pawn_push(Us); Bitboard neighbours, stoppers, support, phalanx, opposed; - Bitboard lever, leverPush; + Bitboard lever, leverPush, blocked; Square s; bool backward, passed, doubled; Score score = SCORE_ZERO; - const Square* pl = pos.squares(Us); + Bitboard b = pos.pieces(Us, PAWN); Bitboard ourPawns = pos.pieces( Us, PAWN); Bitboard theirPawns = pos.pieces(Them, PAWN); Bitboard doubleAttackThem = pawn_double_attacks_bb(theirPawns); - e->passedPawns[Us] = e->pawnAttacksSpan[Us] = 0; + e->passedPawns[Us] = 0; e->kingSquares[Us] = SQ_NONE; - e->pawnAttacks[Us] = pawn_attacks_bb(ourPawns); + e->pawnAttacks[Us] = e->pawnAttacksSpan[Us] = pawn_attacks_bb(ourPawns); + e->blockedCount += popcount(shift(ourPawns) & (theirPawns | doubleAttackThem)); // Loop through all pawns of the current color and score each pawn - while ((s = *pl++) != SQ_NONE) - { + while (b) { + s = pop_lsb(&b); + assert(pos.piece_on(s) == make_piece(Us, PAWN)); Rank r = relative_rank(Us, s); // Flag the pawn opposed = theirPawns & forward_file_bb(Us, s); + blocked = theirPawns & (s + Up); stoppers = theirPawns & passed_pawn_span(Us, s); - lever = theirPawns & PawnAttacks[Us][s]; - leverPush = theirPawns & PawnAttacks[Us][s + Up]; + lever = theirPawns & pawn_attacks_bb(Us, s); + leverPush = theirPawns & pawn_attacks_bb(Us, s + Up); doubled = ourPawns & (s - Up); neighbours = ourPawns & adjacent_files_bb(s); phalanx = neighbours & rank_bb(s); support = 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 safely advance. Phalanx and isolated - // pawns will be excluded when the pawn is scored. - backward = !(neighbours & forward_ranks_bb(Them, s)) - && (stoppers & (leverPush | (s + Up))); - - // Span of backward pawns and span behind opposing pawns are not included - // in the pawnAttacksSpan bitboard. - if (!backward || phalanx) - { - if (opposed) - e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s) & - ~pawn_attack_span(Us, frontmost_sq(Them, opposed)); - else - e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s); - } + // the adjacent files and cannot safely advance. + backward = !(neighbours & forward_ranks_bb(Them, s + Up)) + && (leverPush | blocked); + + // Compute additional span if pawn is not backward nor blocked + if (!backward && !blocked) + e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s); // A pawn is passed if one of the three following conditions is true: // (a) there is no stoppers except some levers // (b) the only stoppers are the leverPush, but we outnumber them // (c) there is only one front stopper which can be levered. + // (Refined in Evaluation::passed) passed = !(stoppers ^ lever) || ( !(stoppers ^ leverPush) && popcount(phalanx) >= popcount(leverPush)) - || ( stoppers == square_bb(s + Up) && r >= RANK_5 + || ( stoppers == blocked && r >= RANK_5 && (shift(support) & ~(theirPawns | doubleAttackThem))); + passed &= !(forward_file_bb(Us, s) & ourPawns); + // Passed pawns will be properly scored later in evaluation when we have // full attack info. if (passed) @@ -140,22 +154,32 @@ namespace { if (support | phalanx) { int v = Connected[r] * (2 + bool(phalanx) - bool(opposed)) - + 21 * popcount(support); + + 22 * popcount(support); score += make_score(v, v * (r - 2) / 4); } else if (!neighbours) - score -= Isolated - + WeakUnopposed * !opposed; + { + if ( opposed + && (ourPawns & forward_file_bb(Them, s)) + && !(theirPawns & adjacent_files_bb(s))) + score -= Doubled; + else + score -= Isolated + + WeakUnopposed * !opposed; + } else if (backward) - score -= Backward - + WeakUnopposed * !opposed; + score -= Backward + + WeakUnopposed * !opposed * bool(~(FileABB | FileHBB) & s); if (!support) - score -= Doubled * doubled - + WeakLever * more_than_one(lever); + score -= Doubled * doubled + + WeakLever * more_than_one(lever); + + if (blocked && r >= RANK_5) + score += BlockedPawn[r - RANK_5]; } return score; @@ -165,6 +189,7 @@ namespace { namespace Pawns { + /// 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 @@ -179,6 +204,7 @@ Entry* probe(const Position& pos) { return e; e->key = key; + e->blockedCount = 0; e->scores[WHITE] = evaluate(pos, e); e->scores[BLACK] = evaluate(pos, e); @@ -190,17 +216,17 @@ Entry* probe(const Position& pos) { /// penalty for a king, looking at the king file and the two closest files. template -Score Entry::evaluate_shelter(const Position& pos, Square ksq) { +Score Entry::evaluate_shelter(const Position& pos, Square ksq) const { - constexpr Color Them = (Us == WHITE ? BLACK : WHITE); + constexpr Color Them = ~Us; Bitboard b = pos.pieces(PAWN) & ~forward_ranks_bb(Them, ksq); - Bitboard ourPawns = b & pos.pieces(Us); + Bitboard ourPawns = b & pos.pieces(Us) & ~pawnAttacks[Them]; Bitboard theirPawns = b & pos.pieces(Them); Score bonus = make_score(5, 5); - File center = clamp(file_of(ksq), FILE_B, FILE_G); + File center = std::clamp(file_of(ksq), FILE_B, FILE_G); for (File f = File(center - 1); f <= File(center + 1); ++f) { b = ourPawns & file_bb(f); @@ -209,15 +235,18 @@ Score Entry::evaluate_shelter(const Position& pos, Square ksq) { b = theirPawns & file_bb(f); int theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : 0; - File d = map_to_queenside(f); + int d = edge_distance(f); bonus += make_score(ShelterStrength[d][ourRank], 0); if (ourRank && (ourRank == theirRank - 1)) - bonus -= BlockedStorm * int(theirRank == RANK_3); + bonus -= BlockedStorm[theirRank]; else bonus -= make_score(UnblockedStorm[d][theirRank], 0); } + // King On File + bonus -= KingOnFile[pos.is_on_semiopen_file(Us, ksq)][pos.is_on_semiopen_file(Them, ksq)]; + return bonus; } @@ -245,9 +274,9 @@ Score Entry::do_king_safety(const Position& pos) { // In endgame we like to bring our king near our closest pawn Bitboard pawns = pos.pieces(Us, PAWN); - int minPawnDist = pawns ? 8 : 0; + int minPawnDist = 6; - if (pawns & PseudoAttacks[KING][ksq]) + if (pawns & attacks_bb(ksq)) minPawnDist = 1; else while (pawns) minPawnDist = std::min(minPawnDist, distance(ksq, pop_lsb(&pawns)));