X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=a5102db8aeb5b383c4ebe26b7ecf92462833a79f;hp=63bc596fcba4cbb9b280c243af89fccc7fc7bff3;hb=767b4f4fbe5ab2e63aceabd9005f4e1eb7cbcb51;hpb=d7a2d5a44588676abf9b49e35a5a567fd57ec3b0 diff --git a/src/pawns.cpp b/src/pawns.cpp index 63bc596f..a5102db8 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) 2015-2020 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 @@ -32,15 +30,21 @@ 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( 8, 25); + constexpr Score Doubled = S(10, 55); + constexpr Score Isolated = S( 3, 15); + constexpr Score WeakLever = S( 3, 55); + constexpr Score WeakUnopposed = S(13, 25); + + // Bonus for blocked pawns at 5th or 6th rank + constexpr Score BlockedPawn[2] = { S(-13, -4), S(-5, 2) }; + + 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 }; + 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. @@ -65,6 +69,12 @@ namespace { #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) { @@ -86,6 +96,7 @@ namespace { e->passedPawns[Us] = 0; e->kingSquares[Us] = SQ_NONE; 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) @@ -98,8 +109,8 @@ namespace { 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); @@ -136,22 +147,32 @@ 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; if (!support) - score -= Doubled * doubled - + WeakLever * more_than_one(lever); + score -= Doubled * doubled + + WeakLever * more_than_one(lever); + + if (blocked && r > RANK_4) + score += BlockedPawn[r-4]; } return score; @@ -161,6 +182,7 @@ 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 @@ -175,6 +197,7 @@ 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); @@ -186,17 +209,17 @@ 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; 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 = Utility::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); @@ -205,11 +228,11 @@ 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 = File(edge_distance(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); } @@ -241,9 +264,9 @@ 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)));