X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=3ce896309f530f057daeacf6320bb35d9eb26517;hp=1e5b4f43b9a6560b61d3f496e7b40ed226c8538d;hb=fb8095718bd0789d2743fa6216c6aa522555dc4b;hpb=328bdd0947ea7903ee1061c8eb60bc3121a4eb19 diff --git a/src/pawns.cpp b/src/pawns.cpp index 1e5b4f43..3ce89630 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -2,7 +2,7 @@ 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) 2015-2020 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 @@ -33,12 +33,13 @@ namespace { // 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 BlockedStorm[RANK_NB] = {S( 0, 0), S( 0, 0), S( 76, 78), S(-10, 15), S(-7, 10), S(-4, 6), S(-1, 2)}; + // Connected pawn bonus constexpr int Connected[RANK_NB] = { 0, 7, 8, 12, 29, 48, 86 }; @@ -56,10 +57,10 @@ 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( 85), V(-289), V(-166), V(97), V(50), V( 45), V( 50) }, + { V( 46), V( -25), V( 122), V(45), V(37), V(-10), V( 20) }, + { V( -6), V( 51), V( 168), V(34), V(-2), V(-22), V(-14) }, + { V(-15), V( -11), V( 101), V( 4), V(11), V(-15), V(-29) } }; #undef S @@ -68,11 +69,11 @@ namespace { 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; @@ -83,9 +84,10 @@ namespace { 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) @@ -96,6 +98,7 @@ namespace { // 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]; @@ -105,32 +108,27 @@ namespace { 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) @@ -139,16 +137,23 @@ namespace { // Score this pawn if (support | phalanx) { - int v = Connected[r] * (2 + bool(phalanx) - bool(opposed)) + int v = Connected[r] * (4 + 2 * bool(phalanx) - 2 * bool(opposed) - bool(blocked)) / 2 + 21 * popcount(support); score += make_score(v, v * (r - 2) / 4); } else if (!neighbours) + { score -= Isolated + WeakUnopposed * !opposed; + if ( (ourPawns & forward_file_bb(Them, s)) + && popcount(opposed) == 1 + && !(theirPawns & adjacent_files_bb(s))) + score -= Doubled; + } + else if (backward) score -= Backward + WeakUnopposed * !opposed; @@ -179,6 +184,7 @@ 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); @@ -192,15 +198,15 @@ Entry* probe(const Position& pos) { template Score Entry::evaluate_shelter(const Position& pos, Square ksq) { - 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 = Utility::clamp(file_of(ksq), FILE_B, FILE_G); for (File f = File(center - 1); f <= File(center + 1); ++f) { b = ourPawns & file_bb(f); @@ -209,11 +215,11 @@ 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); } @@ -245,7 +251,7 @@ 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]) minPawnDist = 1;