From: protonspring Date: Mon, 9 Mar 2020 21:11:08 +0000 (+0100) Subject: Equations for edges and corners. X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=47be966d3028ca9b5c4d095f266663eb205c0c07 Equations for edges and corners. This is a functional simplification that removes the large arrays in endgames.cpp. It also fixes a recently introduced bug (960d59d54143d84aab26deae65279a611fc989f4) in KNBvK, now using flip_file() instead of ~. One fen added to bench to increase endgame coverage. STC LLR: 2.94 (-2.94,2.94) {-1.50,0.50} Total: 174724 W: 33325 L: 33404 D: 107995 Ptnml(0-2): 2503, 19607, 43181, 19608, 2463 http://tests.stockfishchess.org/tests/view/5e6448ffe42a5c3b3ca2e287 LTC LLR: 2.95 (-2.94,2.94) {-1.50,0.50} Total: 35640 W: 4679 L: 4621 D: 26340 Ptnml(0-2): 189, 2991, 11424, 3005, 211 http://tests.stockfishchess.org/tests/view/5e650b24e42a5c3b3ca2e2d8 closes https://github.com/official-stockfish/Stockfish/pull/2577 Bench: 5527957 --- diff --git a/src/benchmark.cpp b/src/benchmark.cpp index f906e731..f338cdda 100644 --- a/src/benchmark.cpp +++ b/src/benchmark.cpp @@ -65,6 +65,7 @@ const vector Defaults = { "4rrk1/1p1nq3/p7/2p1P1pp/3P2bp/3Q1Bn1/PPPB4/1K2R1NR w - - 40 21", "r3k2r/3nnpbp/q2pp1p1/p7/Pp1PPPP1/4BNN1/1P5P/R2Q1RK1 w kq - 0 16", "3Qb1k1/1r2ppb1/pN1n2q1/Pp1Pp1Pr/4P2p/4BP2/4B1R1/1R5K b - - 11 40", + "4k3/3q1r2/1N2r1b1/3ppN2/2nPP3/1B1R2n1/2R1Q3/3K4 w - - 5 1", // 5-man positions "8/8/8/8/5kp1/P7/8/1K1N4 w - - 0 1", // Kc2 - mate diff --git a/src/bitboard.h b/src/bitboard.h index 3ea18dd8..f1d14603 100644 --- a/src/bitboard.h +++ b/src/bitboard.h @@ -255,6 +255,8 @@ template<> inline int distance(Square x, Square y) { return std::abs(file_ template<> inline int distance(Square x, Square y) { return std::abs(rank_of(x) - rank_of(y)); } template<> inline int distance(Square x, Square y) { return SquareDistance[x][y]; } +inline File edge_distance(File f) { return std::min(f, File(FILE_H - f)); } +inline Rank edge_distance(Rank r) { return std::min(r, Rank(RANK_8 - r)); } /// attacks_bb() returns a bitboard representing all the squares attacked by a /// piece of type Pt (bishop or rook) placed on 's'. diff --git a/src/endgame.cpp b/src/endgame.cpp index 53c9ec83..0a2b02ad 100644 --- a/src/endgame.cpp +++ b/src/endgame.cpp @@ -28,31 +28,17 @@ using std::string; namespace { - // Table used to drive the king towards the edge of the board + // Used to drive the king towards the edge of the board // in KX vs K and KQ vs KR endgames. - constexpr int PushToEdges[SQUARE_NB] = { - 100, 90, 80, 70, 70, 80, 90, 100, - 90, 70, 60, 50, 50, 60, 70, 90, - 80, 60, 40, 30, 30, 40, 60, 80, - 70, 50, 30, 20, 20, 30, 50, 70, - 70, 50, 30, 20, 20, 30, 50, 70, - 80, 60, 40, 30, 30, 40, 60, 80, - 90, 70, 60, 50, 50, 60, 70, 90, - 100, 90, 80, 70, 70, 80, 90, 100 - }; - - // Table used to drive the king towards a corner square of the - // right color in KBN vs K endgames. - constexpr int PushToCorners[SQUARE_NB] = { - 6400, 6080, 5760, 5440, 5120, 4800, 4480, 4160, - 6080, 5760, 5440, 5120, 4800, 4480, 4160, 4480, - 5760, 5440, 4960, 4480, 4480, 4000, 4480, 4800, - 5440, 5120, 4480, 3840, 3520, 4480, 4800, 5120, - 5120, 4800, 4480, 3520, 3840, 4480, 5120, 5440, - 4800, 4480, 4000, 4480, 4480, 4960, 5440, 5760, - 4480, 4160, 4480, 4800, 5120, 5440, 5760, 6080, - 4160, 4480, 4800, 5120, 5440, 5760, 6080, 6400 - }; + inline int push_to_edge(Square s) { + int rd = edge_distance(rank_of(s)), fd = edge_distance(file_of(s)); + return 90 - (7 * fd * fd / 2 + 7 * rd * rd / 2); + } + + // Used to drive the king towards A1H8 corners in KBN vs K endgames. + inline int push_to_corner(Square s) { + return abs(7 - rank_of(s) - file_of(s)); + } // Drive a piece close to or away from another piece inline int push_close(Square s1, Square s2) { return 140 - 20 * distance(s1, s2); } @@ -126,7 +112,7 @@ Value Endgame::operator()(const Position& pos) const { Value result = pos.non_pawn_material(strongSide) + pos.count(strongSide) * PawnValueEg - + PushToEdges[loserKSq] + + push_to_edge(loserKSq) + push_close(winnerKSq, loserKSq); if ( pos.count(strongSide) @@ -155,9 +141,9 @@ Value Endgame::operator()(const Position& pos) const { // If our bishop does not attack A1/H8, we flip the enemy king square // to drive to opposite corners (A8/H1). - Value result = VALUE_KNOWN_WIN + Value result = (VALUE_KNOWN_WIN + 3520) + push_close(winnerKSq, loserKSq) - + PushToCorners[opposite_colors(bishopSq, SQ_A1) ? ~loserKSq : loserKSq]; + + 420 * push_to_corner(opposite_colors(bishopSq, SQ_A1) ? flip_file(loserKSq) : loserKSq); assert(abs(result) < VALUE_TB_WIN_IN_MAX_PLY); return strongSide == pos.side_to_move() ? result : -result; @@ -240,7 +226,7 @@ Value Endgame::operator()(const Position& pos) const { assert(verify_material(pos, strongSide, RookValueMg, 0)); assert(verify_material(pos, weakSide, BishopValueMg, 0)); - Value result = Value(PushToEdges[pos.square(weakSide)]); + Value result = Value(push_to_edge(pos.square(weakSide))); return strongSide == pos.side_to_move() ? result : -result; } @@ -255,7 +241,7 @@ Value Endgame::operator()(const Position& pos) const { Square bksq = pos.square(weakSide); Square bnsq = pos.square(weakSide); - Value result = Value(PushToEdges[bksq] + push_away(bksq, bnsq)); + Value result = Value(push_to_edge(bksq) + push_away(bksq, bnsq)); return strongSide == pos.side_to_move() ? result : -result; } @@ -300,7 +286,7 @@ Value Endgame::operator()(const Position& pos) const { Value result = QueenValueEg - RookValueEg - + PushToEdges[loserKSq] + + push_to_edge(loserKSq) + push_close(winnerKSq, loserKSq); return strongSide == pos.side_to_move() ? result : -result; @@ -316,7 +302,7 @@ Value Endgame::operator()(const Position& pos) const { assert(verify_material(pos, weakSide, VALUE_ZERO, 1)); Value result = PawnValueEg - + 2 * PushToEdges[pos.square(weakSide)] + + 2 * push_to_edge(pos.square(weakSide)) - 10 * relative_rank(weakSide, pos.square(weakSide)); return strongSide == pos.side_to_move() ? result : -result; diff --git a/src/evaluate.cpp b/src/evaluate.cpp index 5d073b15..40630d22 100644 --- a/src/evaluate.cpp +++ b/src/evaluate.cpp @@ -643,7 +643,7 @@ namespace { || (pos.pieces(PAWN) & (s + Up))) bonus = bonus / 2; - score += bonus - PassedFile * map_to_queenside(file_of(s)); + score += bonus - PassedFile * edge_distance(file_of(s)); } if (T) diff --git a/src/pawns.cpp b/src/pawns.cpp index 9981ac01..560fd76b 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -202,7 +202,7 @@ 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); + File d = edge_distance(f); bonus += make_score(ShelterStrength[d][ourRank], 0); if (ourRank && (ourRank == theirRank - 1)) diff --git a/src/psqt.cpp b/src/psqt.cpp index f6f5933c..d86e98e4 100644 --- a/src/psqt.cpp +++ b/src/psqt.cpp @@ -21,6 +21,7 @@ #include #include "types.h" +#include "bitboard.h" namespace PSQT { @@ -111,7 +112,7 @@ void init() { for (Square s = SQ_A1; s <= SQ_H8; ++s) { - File f = map_to_queenside(file_of(s)); + File f = edge_distance(file_of(s)); psq[ pc][ s] = score + (type_of(pc) == PAWN ? PBonus[rank_of(s)][file_of(s)] : Bonus[pc][rank_of(s)][f]); psq[~pc][flip_rank(s)] = -psq[pc][s]; diff --git a/src/syzygy/tbprobe.cpp b/src/syzygy/tbprobe.cpp index 6f369455..2532bbd3 100644 --- a/src/syzygy/tbprobe.cpp +++ b/src/syzygy/tbprobe.cpp @@ -705,7 +705,7 @@ Ret do_probe_table(const Position& pos, T* entry, WDLScore wdl, ProbeState* resu std::swap(squares[0], *std::max_element(squares, squares + leadPawnsCnt, pawns_comp)); - tbFile = map_to_queenside(file_of(squares[0])); + tbFile = edge_distance(file_of(squares[0])); } // DTZ tables are one-sided, i.e. they store positions only for white to diff --git a/src/types.h b/src/types.h index d4937fd6..71893c0f 100644 --- a/src/types.h +++ b/src/types.h @@ -370,10 +370,6 @@ constexpr Piece operator~(Piece pc) { return Piece(pc ^ 8); // Swap color of piece B_KNIGHT -> W_KNIGHT } -inline File map_to_queenside(File f) { - return std::min(f, File(FILE_H - f)); // Map files ABCDEFGH to files ABCDDCBA -} - constexpr CastlingRights operator&(Color c, CastlingRights cr) { return CastlingRights((c == WHITE ? WHITE_CASTLING : BLACK_CASTLING) & cr); }