X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=16b00ec2fa012cbf36e75001e3811e661bc91f1a;hp=6d90f6b5858f9fb314a8f2bf61092a7ef7142a23;hb=94dd204c3b10ebe0e6c8df5d7c98de5ba4906cad;hpb=45973245726d8ba62969891a15cf61fe46cc1f31 diff --git a/src/pawns.cpp b/src/pawns.cpp index 6d90f6b5..16b00ec2 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -49,16 +49,13 @@ namespace { { 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 file and rank (initialized by formula) - Score Connected[FILE_NB][RANK_NB]; + // Connected pawn bonus by opposed, phalanx flags and rank + Score Connected[2][2][RANK_NB]; - // Candidate passed pawn bonus by rank - const Score CandidatePassed[RANK_NB] = { - S( 0, 0), S( 6, 13), S(6,13), S(14,29), - S(34,68), S(83,166), S(0, 0), S( 0, 0) }; - - // Bonus for file distance of the two outermost pawns - const Score PawnsFileSpan = S(0, 15); + // 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); @@ -69,10 +66,10 @@ namespace { // Danger of enemy pawns moving toward our king indexed by // [no friendly pawn | pawn unblocked | pawn blocked][rank of enemy pawn] - const Value StormDanger[3][RANK_NB] = { + 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( 64), V(25), V(13) } }; + { V( 0), V( 0), V(160), V(25), V(13) } }; // 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. @@ -89,17 +86,17 @@ namespace { const Square Right = (Us == WHITE ? DELTA_NE : DELTA_SW); const Square Left = (Us == WHITE ? DELTA_NW : DELTA_SE); - Bitboard b, p, doubled; + Bitboard b, p, doubled, connected; Square s; - File f; - bool passed, isolated, opposed, connected, backward, candidate, unsupported; + 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)]; - Bitboard ourPawns = pos.pieces(Us, PAWN); + Bitboard ourPawns = pos.pieces(Us , PAWN); Bitboard theirPawns = pos.pieces(Them, PAWN); - e->passedPawns[Us] = e->candidatePawns[Us] = 0; + e->passedPawns[Us] = 0; e->kingSquares[Us] = SQ_NONE; e->semiopenFiles[Us] = 0xFF; e->pawnAttacks[Us] = shift_bb(ourPawns) | shift_bb(ourPawns); @@ -111,7 +108,7 @@ namespace { { assert(pos.piece_on(s) == make_piece(Us, PAWN)); - f = file_of(s); + File f = file_of(s); // This file cannot be semi-open e->semiopenFiles[Us] &= ~(1 << f); @@ -119,17 +116,16 @@ namespace { // Previous rank p = rank_bb(s - pawn_push(Us)); - // Our rank plus previous one - b = rank_bb(s) | p; - // Flag the pawn as passed, isolated, doubled, // unsupported or connected (but not the backward one). - connected = ourPawns & adjacent_files_bb(f) & b; + 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 @@ -155,14 +151,6 @@ namespace { assert(opposed | passed | (pawn_attack_span(Us, s) & theirPawns)); - // A not-passed pawn is a candidate to become passed, if it is free to - // advance and if the number of friendly pawns beside or behind this - // pawn on adjacent files is higher than or equal to the number of - // enemy pawns in the forward direction on the adjacent files. - candidate = !(opposed | passed | backward | isolated) - && (b = pawn_attack_span(Them, s + pawn_push(Us)) & ourPawns) != 0 - && popcount(b) >= popcount(pawn_attack_span(Us, s) & theirPawns); - // 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. @@ -177,30 +165,20 @@ namespace { value -= UnsupportedPawnPenalty; if (doubled) - value -= Doubled[f] / rank_distance(s, lsb(doubled)); + value -= Doubled[f] / distance(s, frontmost_sq(Us, doubled)); if (backward) value -= Backward[opposed][f]; if (connected) - value += Connected[f][relative_rank(Us, s)]; + value += Connected[opposed][phalanx][relative_rank(Us, s)]; - if (candidate) - { - value += CandidatePassed[relative_rank(Us, s)]; - - if (!doubled) - e->candidatePawns[Us] |= s; - } + if (lever) + value += Lever[relative_rank(Us, s)]; } - // In endgame it's better to have pawns on both wings. So give a bonus according - // to file distance between left and right outermost pawns. - if (pos.count(Us) > 1) - { - b = e->semiopenFiles[Us] ^ 0xFF; - value += PawnsFileSpan * int(msb(b) - lsb(b)); - } + b = e->semiopenFiles[Us] ^ 0xFF; + e->pawnSpan[Us] = b ? int(msb(b) - lsb(b)) : 0; return value; } @@ -209,24 +187,26 @@ namespace { namespace Pawns { -/// init() initializes some tables by formula instead of hard-coding their values - -void init() { - - const int bonusesByFile[8] = { 1, 3, 3, 4, 4, 3, 3, 1 }; - int bonus; - - for (Rank r = RANK_1; r < RANK_8; ++r) - for (File f = FILE_A; f <= FILE_H; ++f) - { - bonus = r * (r-1) * (r-2) + bonusesByFile[f] * (r/2 + 1); - Connected[f][r] = make_score(bonus, bonus); - } +/// 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. + +void init() +{ + static const int Seed[RANK_NB] = { 0, 6, 15, 10, 57, 75, 135, 258 }; + + 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); + } } -/// probe() takes a position object 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 +/// 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. Entry* probe(const Position& pos, Table& entries) { @@ -250,53 +230,52 @@ template Value Entry::shelter_storm(const Position& pos, Square ksq) { const Color Them = (Us == WHITE ? BLACK : WHITE); - static const Bitboard MiddleEdges = (FileABB | FileHBB) & (Rank2BB | Rank3BB); + const Bitboard Edges = (FileABB | FileHBB) & (Rank2BB | Rank3BB); - Value safety = MaxSafetyBonus; Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, rank_of(ksq)) | rank_bb(ksq)); Bitboard ourPawns = b & pos.pieces(Us); Bitboard theirPawns = b & pos.pieces(Them); - Rank rkUs, rkThem; + Value safety = MaxSafetyBonus; File kf = std::max(FILE_B, std::min(FILE_G, file_of(ksq))); for (File f = kf - File(1); f <= kf + File(1); ++f) { b = ourPawns & file_bb(f); - rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1; + Rank rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1; b = theirPawns & file_bb(f); - rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1; + Rank rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1; - if ( (MiddleEdges & make_square(f, rkThem)) + if ( (Edges & make_square(f, rkThem)) && file_of(ksq) == f && relative_rank(Us, ksq) == rkThem - 1) - safety += Value(200); + safety += 200; else - safety -= ShelterWeakness[rkUs] - + StormDanger[rkUs == RANK_1 ? 0 : rkThem == rkUs + 1 ? 2 : 1][rkThem]; + safety -= ShelterWeakness[rkUs] + + StormDanger[rkUs == RANK_1 ? 0 : + rkThem != rkUs + 1 ? 1 : 2][rkThem]; } return safety; } -/// Entry::update_safety() calculates and caches a bonus for king safety. -/// It is called only when king square changes, which is about 20% of total -/// king_safety() calls. +/// Entry::do_king_safety() calculates a bonus for king safety. It is called only +/// when king square changes, which is about 20% of total king_safety() calls. template -Score Entry::update_safety(const Position& pos, Square ksq) { +Score Entry::do_king_safety(const Position& pos, Square ksq) { kingSquares[Us] = ksq; castlingRights[Us] = pos.can_castle(Us); - minKPdistance[Us] = 0; + minKingPawnDistance[Us] = 0; Bitboard pawns = pos.pieces(Us, PAWN); if (pawns) - while (!(DistanceRingsBB[ksq][minKPdistance[Us]++] & pawns)) {} + while (!(DistanceRingsBB[ksq][minKingPawnDistance[Us]++] & pawns)) {} if (relative_rank(Us, ksq) > RANK_4) - return kingSafety[Us] = make_score(0, -16 * minKPdistance[Us]); + return make_score(0, -16 * minKingPawnDistance[Us]); Value bonus = shelter_storm(pos, ksq); @@ -307,11 +286,11 @@ Score Entry::update_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 kingSafety[Us] = make_score(bonus, -16 * minKPdistance[Us]); + return make_score(bonus, -16 * minKingPawnDistance[Us]); } // Explicit template instantiation -template Score Entry::update_safety(const Position& pos, Square ksq); -template Score Entry::update_safety(const Position& pos, Square ksq); +template Score Entry::do_king_safety(const Position& pos, Square ksq); +template Score Entry::do_king_safety(const Position& pos, Square ksq); } // namespace Pawns