X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=17a96670911dc414b351ca7f2197dada32a510a7;hp=5bf0e82ea98434aee57b171d5604b9ddf3055781;hb=e06a117d5e78ec4edc051f2b161d36559f784d37;hpb=8fb45caadef67fb2ccc27857c15ade987d9f5e2f diff --git a/src/pawns.cpp b/src/pawns.cpp index 5bf0e82e..17a96670 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) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad + Copyright (C) 2015-2017 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 @@ -31,58 +31,57 @@ namespace { #define V Value #define S(mg, eg) make_score(mg, eg) - // Isolated pawn penalty by opposed flag and file - const Score Isolated[2][FILE_NB] = { - { S(31, 36), S(45, 41), S(50, 41), S(50, 41), - S(50, 41), S(50, 41), S(45, 41), S(31, 36) }, - { S(21, 24), S(30, 28), S(33, 28), S(33, 28), - S(33, 28), S(33, 28), S(30, 28), S(21, 24) } }; + // Isolated pawn penalty by opposed flag + const Score Isolated[] = { S(45, 40), S(30, 27) }; // Backward pawn penalty by opposed flag - const Score Backward[2] = { S(56, 33), S(41, 19) }; + const Score Backward[] = { S(56, 33), S(41, 19) }; - // Unsupported pawn penalty for pawns which are neither isolated or backward, - // by number of pawns it supports [less than 2 / exactly 2]. - const Score Unsupported[2] = { S(17, 8), S(21, 12) }; + // Unsupported pawn penalty for pawns which are neither isolated or backward + const Score Unsupported = S(17, 8); // Connected pawn bonus by opposed, phalanx, twice supported and rank Score Connected[2][2][2][RANK_NB]; - // Doubled pawn penalty by file - const Score Doubled[FILE_NB] = { - S(11, 34), S(17, 38), S(19, 38), S(19, 38), - S(19, 38), S(19, 38), S(17, 38), S(11, 34) }; + // Doubled pawn penalty + const Score Doubled = S(18, 38); // Lever bonus by rank const Score Lever[RANK_NB] = { S( 0, 0), S( 0, 0), S(0, 0), S(0, 0), - S(17, 16), S(33, 32), S(0, 0), S(0, 0) }; + S(17, 16), S(33, 32), S(0, 0), S(0, 0) + }; - // Weakness of our pawn shelter in front of the king by [distance from edge][rank] + // Weakness of our pawn shelter in front of the king by [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[][RANK_NB] = { - { V( 97), V(21), V(26), V(51), V(87), V( 89), V( 99) }, - { V(120), V( 0), V(28), V(76), V(88), V(103), V(104) }, - { V(101), V( 7), V(54), V(78), V(77), V( 92), V(101) }, - { V( 80), V(11), V(44), V(68), V(87), V( 90), V(119) } }; - - // Danger of enemy pawns moving toward our king by [type][distance from edge][rank] + { V(100), V(20), V(10), V(46), V(82), V( 86), V( 98) }, + { V(116), V( 4), V(28), V(87), V(94), V(108), V(104) }, + { V(109), V( 1), V(59), V(87), V(62), V( 91), V(116) }, + { V( 75), V(12), V(43), V(59), V(90), V( 84), V(112) } + }; + + // 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( 67), V( 134), V(38), V(32) }, - { V( 0), V( 57), V( 139), V(37), V(22) }, - { V( 0), V( 43), V( 115), V(43), V(27) }, - { V( 0), V( 68), V( 124), V(57), V(32) } }, - { { V(20), V( 43), V( 100), V(56), V(20) }, - { V(23), V( 20), V( 98), V(40), V(15) }, - { V(23), V( 39), V( 103), V(36), V(18) }, - { V(28), V( 19), V( 108), V(42), V(26) } }, - { { V( 0), V( 0), V( 75), V(14), V( 2) }, - { V( 0), V( 0), V( 150), V(30), V( 4) }, - { V( 0), V( 0), V( 160), V(22), V( 5) }, - { V( 0), V( 0), V( 166), V(24), V(13) } }, - { { V( 0), V(-283), V(-281), V(57), V(31) }, - { V( 0), V( 58), V( 141), V(39), V(18) }, - { V( 0), V( 65), V( 142), V(48), V(32) }, - { V( 0), V( 60), V( 126), V(51), V(19) } } }; + { { 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. @@ -94,25 +93,25 @@ 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 Square Up = (Us == WHITE ? NORTH : SOUTH); + const Square Right = (Us == WHITE ? NORTH_EAST : SOUTH_WEST); + const Square Left = (Us == WHITE ? NORTH_WEST : SOUTH_EAST); - Bitboard b, neighbours, doubled, supported, phalanx; + Bitboard b, neighbours, stoppers, doubled, supported, phalanx; + Bitboard lever, leverPush, connected; Square s; - bool passed, isolated, opposed, backward, lever, connected; + bool opposed, backward; Score score = SCORE_ZERO; const Square* pl = pos.squares(Us); - const Bitboard* pawnAttacksBB = StepAttacksBB[make_piece(Us, PAWN)]; Bitboard ourPawns = pos.pieces(Us , PAWN); Bitboard theirPawns = pos.pieces(Them, PAWN); - e->passedPawns[Us] = e->pawnAttacksSpan[Us] = 0; - e->kingSquares[Us] = SQ_NONE; + e->passedPawns[Us] = e->pawnAttacksSpan[Us] = 0; e->semiopenFiles[Us] = 0xFF; - e->pawnAttacks[Us] = shift_bb(ourPawns) | shift_bb(ourPawns); + e->kingSquares[Us] = SQ_NONE; + e->pawnAttacks[Us] = shift(ourPawns) | shift(ourPawns); e->pawnsOnSquares[Us][BLACK] = popcount(ourPawns & DarkSquares); e->pawnsOnSquares[Us][WHITE] = pos.count(Us) - e->pawnsOnSquares[Us][BLACK]; @@ -123,73 +122,67 @@ namespace { File f = file_of(s); - e->semiopenFiles[Us] &= ~(1 << f); + e->semiopenFiles[Us] &= ~(1 << f); e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s); // Flag the pawn - neighbours = 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]; - phalanx = neighbours & rank_bb(s); - supported = neighbours & rank_bb(s - Up); - connected = supported | phalanx; - isolated = !neighbours; - - // Test for backward pawn. - // If the pawn is passed, isolated, lever or connected it cannot be - // backward. If there are friendly pawns behind on adjacent files - // or if it is sufficiently advanced, it cannot be backward either. - if ( (passed | isolated | lever | connected) - || (ourPawns & pawn_attack_span(Them, s)) - || (relative_rank(Us, s) >= RANK_5)) + opposed = theirPawns & forward_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); + connected = supported | phalanx; + + // 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 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 || !(pawn_attack_span(Them, s + Up) & neighbours)); + } // Passed pawns will be properly scored in evaluation because we need - // full attack info to evaluate them. 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_bb(Us, s)) + && popcount(supported) >= popcount(lever) + && popcount(phalanx) >= popcount(leverPush)) e->passedPawns[Us] |= s; // Score this pawn - if (isolated) - score -= Isolated[opposed][f]; + if (!neighbours) + score -= Isolated[opposed]; else if (backward) score -= Backward[opposed]; else if (!supported) - score -= Unsupported[more_than_one(neighbours & rank_bb(s + Up))]; + score -= Unsupported; if (connected) score += Connected[opposed][!!phalanx][more_than_one(supported)][relative_rank(Us, s)]; - if (doubled) - score -= Doubled[f] / distance(s, frontmost_sq(Us, doubled)); + if (doubled && !supported) + score -= Doubled; if (lever) score += Lever[relative_rank(Us, s)]; } - b = e->semiopenFiles[Us] ^ 0xFF; - e->pawnSpan[Us] = b ? int(msb(b) - lsb(b)) : 0; - return score; } @@ -201,8 +194,8 @@ namespace Pawns { /// 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() -{ +void init() { + static const int Seed[RANK_NB] = { 0, 8, 19, 13, 71, 94, 169, 324 }; for (int opposed = 0; opposed <= 1; ++opposed) @@ -212,7 +205,7 @@ void init() { int v = (Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0)) >> opposed; v += (apex ? v / 2 : 0); - Connected[opposed][phalanx][apex][r] = make_score(v, v * 5 / 8); + Connected[opposed][phalanx][apex][r] = make_score(v, v * (r-2) / 4); } } @@ -233,19 +226,20 @@ Entry* probe(const Position& pos) { e->key = key; e->score = evaluate(pos, e) - 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); - enum { NoFriendlyPawn, Unblocked, BlockedByPawn, BlockedByKing }; + enum { BlockedByKing, Unopposed, BlockedByPawn, Unblocked }; Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, rank_of(ksq)) | rank_bb(ksq)); Bitboard ourPawns = b & pos.pieces(Us); @@ -261,12 +255,13 @@ Value Entry::shelter_storm(const Position& pos, Square ksq) { b = theirPawns & file_bb(f); Rank rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1; - safety -= ShelterWeakness[std::min(f, FILE_H - f)][rkUs] + int d = std::min(f, FILE_H - f); + safety -= ShelterWeakness[d][rkUs] + StormDanger [f == file_of(ksq) && rkThem == relative_rank(Us, ksq) + 1 ? BlockedByKing : - rkUs == RANK_1 ? NoFriendlyPawn : + rkUs == RANK_1 ? Unopposed : rkThem == rkUs + 1 ? BlockedByPawn : Unblocked] - [std::min(f, FILE_H - f)][rkThem]; + [d][rkThem]; } return safety;