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Retire pawn storm evaluation
More then 100 lines of almost useless evaluations. Prefer code semplification to a very small and dubious advantage. After 7457 games on russian cluster: Mod - Orig: 1285 - 1334 - 4838 ELO -2 (+- 3.2) Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Joona Kiiski
Marco Costalba
parent
5b5b496a6d
commit
fa2478a81f
3 changed files with 7 additions and 112 deletions
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@ -336,26 +336,11 @@ Value do_evaluate(const Position& pos, Value margins[]) {
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Phase phase = mi->game_phase();
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// Middle-game specific evaluation terms
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if (phase > PHASE_ENDGAME)
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// Evaluate space for both sides, only in middle-game.
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if (phase > PHASE_ENDGAME && mi->space_weight() > 0)
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{
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// Evaluate pawn storms in positions with opposite castling
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if ( square_file(pos.king_square(WHITE)) >= FILE_E
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&& square_file(pos.king_square(BLACK)) <= FILE_D)
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bonus += make_score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
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else if ( square_file(pos.king_square(WHITE)) <= FILE_D
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&& square_file(pos.king_square(BLACK)) >= FILE_E)
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bonus += make_score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
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// Evaluate space for both sides
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if (mi->space_weight() > 0)
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{
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int s = evaluate_space<WHITE, HasPopCnt>(pos, ei) - evaluate_space<BLACK, HasPopCnt>(pos, ei);
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bonus += apply_weight(make_score(s * mi->space_weight(), 0), Weights[Space]);
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}
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int s = evaluate_space<WHITE, HasPopCnt>(pos, ei) - evaluate_space<BLACK, HasPopCnt>(pos, ei);
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bonus += apply_weight(make_score(s * mi->space_weight(), 0), Weights[Space]);
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}
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// If we don't already have an unusual scale factor, check for opposite
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@ -70,36 +70,6 @@ namespace {
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S(34,68), S(83,166), S(0, 0), S( 0, 0)
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};
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// Pawn storm tables for positions with opposite castling
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const int QStormTable[64] = {
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0, 0, 0, 0, 0, 0, 0, 0,
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-22,-22,-22,-14,-6, 0, 0, 0,
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-6,-10,-10,-10,-6, 0, 0, 0,
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4, 12, 16, 12, 4, 0, 0, 0,
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16, 23, 23, 16, 0, 0, 0, 0,
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23, 31, 31, 23, 0, 0, 0, 0,
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23, 31, 31, 23, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0
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};
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const int KStormTable[64] = {
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0,-10,-19,-28,-33,-33,
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0, 0, 0,-10,-15,-19,-24,-24,
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0, 0, 0, 0, 1, 1, 1, 1,
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0, 0, 0, 0, 1, 10, 19, 19,
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0, 0, 0, 0, 1, 19, 31, 27,
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0, 0, 0, 0, 0, 22, 31, 22,
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0, 0, 0, 0, 0, 0, 0, 0
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};
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// Pawn storm open file bonuses by file
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const int16_t QStormOpenFileBonus[8] = { 31, 31, 18, 0, 0, 0, 0, 0 };
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const int16_t KStormOpenFileBonus[8] = { 0, 0, 0, 0, 0, 26, 42, 26 };
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// Pawn storm lever bonuses by file
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const int StormLeverBonus[8] = { -8, -8, -13, 0, 0, -13, -8, -8 };
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#undef S
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}
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@ -175,35 +145,22 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
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Square s;
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File f;
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Rank r;
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int bonus;
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bool passed, isolated, doubled, opposed, chain, backward, candidate;
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Score value = SCORE_ZERO;
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const Square* ptr = pos.piece_list_begin(Us, PAWN);
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// Initialize pawn storm scores by giving bonuses for open files
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// Initialize halfOpenFiles[]
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for (f = FILE_A; f <= FILE_H; f++)
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if (!(ourPawns & file_bb(f)))
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{
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pi->ksStormValue[Us] += KStormOpenFileBonus[f];
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pi->qsStormValue[Us] += QStormOpenFileBonus[f];
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pi->halfOpenFiles[Us] |= (1 << f);
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}
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// Loop through all pawns of the current color and score each pawn
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while ((s = *ptr++) != SQ_NONE)
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{
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f = square_file(s);
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r = square_rank(s);
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assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
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// Calculate kingside and queenside pawn storm scores for both colors to be
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// used when evaluating middle game positions with opposite side castling.
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bonus = (f >= FILE_F ? evaluate_pawn_storm<Us, KingSide>(s, r, f, theirPawns) : 0);
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pi->ksStormValue[Us] += KStormTable[relative_square(Us, s)] + bonus;
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bonus = (f <= FILE_C ? evaluate_pawn_storm<Us, QueenSide>(s, r, f, theirPawns) : 0);
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pi->qsStormValue[Us] += QStormTable[relative_square(Us, s)] + bonus;
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f = square_file(s);
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r = square_rank(s);
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// Our rank plus previous one. Used for chain detection.
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b = rank_bb(r) | rank_bb(Us == WHITE ? r - Rank(1) : r + Rank(1));
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@ -288,35 +245,3 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
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return value;
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}
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/// PawnInfoTable::evaluate_pawn_storm() evaluates each pawn which seems
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/// to have good chances of creating an open file by exchanging itself
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/// against an enemy pawn on an adjacent file.
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template<Color Us, PawnInfoTable::SideType Side>
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int PawnInfoTable::evaluate_pawn_storm(Square s, Rank r, File f, Bitboard theirPawns) const {
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const Bitboard StormFilesBB = (Side == KingSide ? FileFBB | FileGBB | FileHBB
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: FileABB | FileBBB | FileCBB);
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const int K = (Side == KingSide ? 2 : 4);
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const File RookFile = (Side == KingSide ? FILE_H : FILE_A);
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Bitboard b = attack_span_mask(Us, s) & theirPawns & StormFilesBB;
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int bonus = 0;
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while (b)
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{
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// Give a bonus according to the distance of the nearest enemy pawn
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Square s2 = pop_1st_bit(&b);
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Rank r2 = square_rank(s2);
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int v = StormLeverBonus[f] - K * rank_distance(r, r2);
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// If enemy pawn has no pawn beside itself is particularly vulnerable.
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// Big bonus, especially against a weakness on the rook file
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if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2)))
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v *= (square_file(s2) == RookFile ? 4 : 2);
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bonus += v;
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}
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return bonus;
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}
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15
src/pawns.h
15
src/pawns.h
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@ -47,8 +47,6 @@ class PawnInfo {
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public:
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Score pawns_value() const;
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Value kingside_storm_value(Color c) const;
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Value queenside_storm_value(Color c) const;
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Bitboard pawn_attacks(Color c) const;
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Bitboard passed_pawns(Color c) const;
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int file_is_half_open(Color c, File f) const;
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@ -67,8 +65,6 @@ private:
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Bitboard pawnAttacks[2];
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Square kingSquares[2];
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Score value;
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int ksStormValue[2];
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int qsStormValue[2];
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int halfOpenFiles[2];
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Score kingShelters[2];
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};
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@ -92,9 +88,6 @@ private:
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template<Color Us>
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Score evaluate_pawns(const Position& pos, Bitboard ourPawns, Bitboard theirPawns, PawnInfo* pi) const;
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template<Color Us, SideType Side>
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int evaluate_pawn_storm(Square s, Rank r, File f, Bitboard theirPawns) const;
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PawnInfo* entries;
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};
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@ -118,14 +111,6 @@ inline Bitboard PawnInfo::pawn_attacks(Color c) const {
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return pawnAttacks[c];
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}
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inline Value PawnInfo::kingside_storm_value(Color c) const {
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return Value(ksStormValue[c]);
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}
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inline Value PawnInfo::queenside_storm_value(Color c) const {
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return Value(qsStormValue[c]);
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}
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inline Bitboard PawnInfo::passed_pawns(Color c) const {
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return passedPawns[c];
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}
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