X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=91f8ed752004cb7a48760f71fb0c4d0679617545;hp=587caf0d316c2275acb35db1208b0a29cd1bebd9;hb=ccdb634b7722a300707b9348ac30ae2c4152da8a;hpb=9005ea633962167374fa85821abb3e1731cc1c7c diff --git a/src/pawns.cpp b/src/pawns.cpp index 587caf0d..91f8ed75 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -23,6 +23,7 @@ //// #include +#include #include "bitcount.h" #include "pawns.h" @@ -37,95 +38,95 @@ namespace { /// Constants and variables - // Doubled pawn penalty by file, middle game. + // Doubled pawn penalty by file, middle game const Value DoubledPawnMidgamePenalty[8] = { - Value(20), Value(30), Value(34), Value(34), - Value(34), Value(34), Value(30), Value(20) + Value(13), Value(20), Value(23), Value(23), + Value(23), Value(23), Value(20), Value(13) }; - // Doubled pawn penalty by file, endgame. + // Doubled pawn penalty by file, endgame const Value DoubledPawnEndgamePenalty[8] = { - Value(35), Value(40), Value(40), Value(40), - Value(40), Value(40), Value(40), Value(35) + Value(43), Value(48), Value(48), Value(48), + Value(48), Value(48), Value(48), Value(43) }; - // Isolated pawn penalty by file, middle game. + // Isolated pawn penalty by file, middle game const Value IsolatedPawnMidgamePenalty[8] = { - Value(20), Value(30), Value(34), Value(34), - Value(34), Value(34), Value(30), Value(20) + Value(25), Value(36), Value(40), Value(40), + Value(40), Value(40), Value(36), Value(25) }; - // Isolated pawn penalty by file, endgame. + // Isolated pawn penalty by file, endgame const Value IsolatedPawnEndgamePenalty[8] = { - Value(35), Value(40), Value(40), Value(40), - Value(40), Value(40), Value(40), Value(35) + Value(30), Value(35), Value(35), Value(35), + Value(35), Value(35), Value(35), Value(30) }; - // Backward pawn penalty by file, middle game. + // Backward pawn penalty by file, middle game const Value BackwardPawnMidgamePenalty[8] = { - Value(16), Value(24), Value(27), Value(27), - Value(27), Value(27), Value(24), Value(16) + Value(20), Value(29), Value(33), Value(33), + Value(33), Value(33), Value(29), Value(20) }; - // Backward pawn penalty by file, endgame. + // Backward pawn penalty by file, endgame const Value BackwardPawnEndgamePenalty[8] = { - Value(28), Value(32), Value(32), Value(32), - Value(32), Value(32), Value(32), Value(28) + Value(28), Value(31), Value(31), Value(31), + Value(31), Value(31), Value(31), Value(28) }; - // Pawn chain membership bonus by file, middle game. + // Pawn chain membership bonus by file, middle game const Value ChainMidgameBonus[8] = { - Value(14), Value(16), Value(17), Value(18), - Value(18), Value(17), Value(16), Value(14) + Value(11), Value(13), Value(13), Value(14), + Value(14), Value(13), Value(13), Value(11) }; - // Pawn chain membership bonus by file, endgame. + // Pawn chain membership bonus by file, endgame const Value ChainEndgameBonus[8] = { - Value(16), Value(16), Value(16), Value(16), - Value(16), Value(16), Value(16), Value(16) + Value(-1), Value(-1), Value(-1), Value(-1), + Value(-1), Value(-1), Value(-1), Value(-1) }; - // Candidate passed pawn bonus by rank, middle game. + // Candidate passed pawn bonus by rank, middle game const Value CandidateMidgameBonus[8] = { - Value( 0), Value(12), Value(12), Value(20), - Value(40), Value(90), Value( 0), Value( 0) + Value( 0), Value( 6), Value(6), Value(14), + Value(34), Value(83), Value(0), Value( 0) }; - // Candidate passed pawn bonus by rank, endgame. + // Candidate passed pawn bonus by rank, endgame const Value CandidateEndgameBonus[8] = { - Value( 0), Value(24), Value(24), Value(40), - Value(80), Value(180), Value(0), Value( 0) + Value( 0), Value( 13), Value(13), Value(29), + Value(68), Value(166), Value( 0), Value( 0) }; - // Pawn storm tables for positions with opposite castling: + // Pawn storm tables for positions with opposite castling const int QStormTable[64] = { 0, 0, 0, 0, 0, 0, 0, 0, - -22,-22,-22,-13,-4, 0, 0, 0, - -4, -9, -9, -9,-4, 0, 0, 0, - 9, 18, 22, 18, 9, 0, 0, 0, - 22, 31, 31, 22, 0, 0, 0, 0, - 31, 40, 40, 31, 0, 0, 0, 0, - 31, 40, 40, 31, 0, 0, 0, 0, + -22,-22,-22,-14,-6, 0, 0, 0, + -6,-10,-10,-10,-6, 0, 0, 0, + 4, 12, 16, 12, 4, 0, 0, 0, + 16, 23, 23, 16, 0, 0, 0, 0, + 23, 31, 31, 23, 0, 0, 0, 0, + 23, 31, 31, 23, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; const int KStormTable[64] = { - 0, 0, 0, 0, 0, 0, 0, 0, - 0, 0, 0,-4,-13,-22,-27,-27, - 0, 0, 0,-4, -9,-13,-18,-18, - 0, 0, 0, 0, 9, 9, 9, 9, - 0, 0, 0, 0, 9, 18, 27, 27, - 0, 0, 0, 0, 9, 27, 40, 36, - 0, 0, 0, 0, 0, 31, 40, 31, - 0, 0, 0, 0, 0, 0, 0, 0 + 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0,-10,-19,-28,-33,-33, + 0, 0, 0,-10,-15,-19,-24,-24, + 0, 0, 0, 0, 1, 1, 1, 1, + 0, 0, 0, 0, 1, 10, 19, 19, + 0, 0, 0, 0, 1, 19, 31, 27, + 0, 0, 0, 0, 0, 22, 31, 22, + 0, 0, 0, 0, 0, 0, 0, 0 }; // Pawn storm open file bonuses by file - const int16_t KStormOpenFileBonus[8] = { 45, 45, 30, 0, 0, 0, 0, 0 }; - const int16_t QStormOpenFileBonus[8] = { 0, 0, 0, 0, 0, 30, 45, 30 }; + const int16_t KStormOpenFileBonus[8] = { 31, 31, 18, 0, 0, 0, 0, 0 }; + const int16_t QStormOpenFileBonus[8] = { 0, 0, 0, 0, 0, 26, 42, 26 }; // Pawn storm lever bonuses by file - const int StormLeverBonus[8] = { 20, 20, 10, 0, 0, 10, 20, 20 }; + const int StormLeverBonus[8] = { -8, -8, -13, 0, 0, -13, -8, -8 }; } @@ -140,7 +141,7 @@ PawnInfoTable::PawnInfoTable(unsigned numOfEntries) { size = numOfEntries; entries = new PawnInfo[size]; - if (entries == NULL) + if (!entries) { std::cerr << "Failed to allocate " << (numOfEntries * sizeof(PawnInfo)) << " bytes for pawn hash table." << std::endl; @@ -156,22 +157,32 @@ PawnInfoTable::~PawnInfoTable() { } +/// PawnInfo::clear() resets to zero the PawnInfo entry. Note that +/// kingSquares[] is initialized to SQ_NONE instead. + +void PawnInfo::clear() { + + memset(this, 0, sizeof(PawnInfo)); + kingSquares[WHITE] = kingSquares[BLACK] = SQ_NONE; +} + + /// PawnInfoTable::get_pawn_info() takes a position object as input, computes /// a PawnInfo 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. -PawnInfo *PawnInfoTable::get_pawn_info(const Position &pos) { +PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) { assert(pos.is_ok()); Key key = pos.get_pawn_key(); int index = int(key & (size - 1)); - PawnInfo *pi = entries + index; + PawnInfo* pi = entries + index; // If pi->key matches the position's pawn hash key, it means that we - // have analysed this pawn structure before, and we can simply return the - // information we found the last time instead of recomputing it + // have analysed this pawn structure before, and we can simply return + // the information we found the last time instead of recomputing it. if (pi->key == key) return pi; @@ -179,209 +190,227 @@ PawnInfo *PawnInfoTable::get_pawn_info(const Position &pos) { pi->clear(); pi->key = key; - Value mgValue[2] = {Value(0), Value(0)}; - Value egValue[2] = {Value(0), Value(0)}; + // Calculate pawn attacks + Bitboard whitePawns = pos.pieces(PAWN, WHITE); + Bitboard blackPawns = pos.pieces(PAWN, BLACK); + pi->pawnAttacks[WHITE] = ((whitePawns << 9) & ~FileABB) | ((whitePawns << 7) & ~FileHBB); + pi->pawnAttacks[BLACK] = ((blackPawns >> 7) & ~FileABB) | ((blackPawns >> 9) & ~FileHBB); - // Loop through the pawns for both colors - for (Color us = WHITE; us <= BLACK; us++) - { - Color them = opposite_color(us); - Bitboard ourPawns = pos.pawns(us); - Bitboard theirPawns = pos.pawns(them); - Bitboard pawns = ourPawns; - int bonus; - - // Initialize pawn storm scores by giving bonuses for open files - for (File f = FILE_A; f <= FILE_H; f++) - if (pos.file_is_half_open(us, f)) - { - pi->ksStormValue[us] += KStormOpenFileBonus[f]; - pi->qsStormValue[us] += QStormOpenFileBonus[f]; - } - - // Loop through all pawns of the current color and score each pawn - while (pawns) - { - bool passed, doubled, isolated, backward, chain, candidate; - Square s = pop_1st_bit(&pawns); - File f = square_file(s); - Rank r = square_rank(s); - - assert(pos.piece_on(s) == piece_of_color_and_type(us, PAWN)); - - // The file containing the pawn is not half open - pi->halfOpenFiles[us] &= ~(1 << f); - - // Passed, isolated or doubled pawn? - passed = pos.pawn_is_passed(us, s); - isolated = pos.pawn_is_isolated(us, s); - doubled = pos.pawn_is_doubled(us, s); - - // We calculate kingside and queenside pawn storm - // scores for both colors. These are used when evaluating - // middle game positions with opposite side castling. - // - // Each pawn is given a base score given by a piece square table - // (KStormTable[] or QStormTable[]). Pawns which seem to have good - // chances of creating an open file by exchanging itself against an - // enemy pawn on an adjacent file gets an additional bonus. - - // Kingside pawn storms - bonus = KStormTable[relative_square(us, s)]; - if (f >= FILE_F) - { - Bitboard b = outpost_mask(us, s) & theirPawns & (FileFBB | FileGBB | FileHBB); - while (b) - { - Square s2 = pop_1st_bit(&b); - if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2))) - { - // The enemy pawn has no pawn beside itself, which makes it - // particularly vulnerable. Big bonus, especially against a - // weakness on the rook file. - if (square_file(s2) == FILE_H) - bonus += 4*StormLeverBonus[f] - 8*square_distance(s, s2); - else - bonus += 2*StormLeverBonus[f] - 4*square_distance(s, s2); - } else - // There is at least one enemy pawn beside the enemy pawn we look - // at, which means that the pawn has somewhat better chances of - // defending itself by advancing. Smaller bonus. - bonus += StormLeverBonus[f] - 2*square_distance(s, s2); - } - } - pi->ksStormValue[us] += bonus; - - // Queenside pawn storms - bonus = QStormTable[relative_square(us, s)]; - if (f <= FILE_C) - { - Bitboard b = outpost_mask(us, s) & theirPawns & (FileABB | FileBBB | FileCBB); - while (b) - { - Square s2 = pop_1st_bit(&b); - if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2))) - { - // The enemy pawn has no pawn beside itself, which makes it - // particularly vulnerable. Big bonus, especially against a - // weakness on the rook file. - if (square_file(s2) == FILE_A) - bonus += 4*StormLeverBonus[f] - 16*square_distance(s, s2); - else - bonus += 2*StormLeverBonus[f] - 8*square_distance(s, s2); - } else - // There is at least one enemy pawn beside the enemy pawn we look - // at, which means that the pawn has somewhat better chances of - // defending itself by advancing. Smaller bonus. - bonus += StormLeverBonus[f] - 4*square_distance(s, s2); - } - } - pi->qsStormValue[us] += bonus; - - // Member of a pawn chain (but not the backward one)? We could speed up - // the test a little by introducing an array of masks indexed by color - // and square for doing the test, but because everything is hashed, - // it probably won't make any noticable difference. - chain = ourPawns - & neighboring_files_bb(f) - & (rank_bb(r) | rank_bb(r - (us == WHITE ? 1 : -1))); - - // Test for backward pawn - // - // If the pawn is passed, isolated, or member of a pawn chain - // it cannot be backward. If can capture an enemy pawn or if - // there are friendly pawns behind on neighboring files it cannot - // be backward either. - if ( passed - || isolated - || chain - || (pos.pawn_attacks(us, s) & theirPawns) - || (ourPawns & behind_bb(us, r) & neighboring_files_bb(f))) - backward = false; - else - { - // We now know that there are no friendly pawns beside or behind this - // pawn on neighboring files. We now check whether the pawn is - // backward by looking in the forward direction on the neighboring - // files, and seeing whether we meet a friendly or an enemy pawn first. - Bitboard b; - if (us == WHITE) - { - for (b = pos.pawn_attacks(us, s); !(b & (ourPawns | theirPawns)); b <<= 8); - backward = (b | (b << 8)) & theirPawns; - } - else - { - for (b = pos.pawn_attacks(us, s); !(b & (ourPawns | theirPawns)); b >>= 8); - backward = (b | (b >> 8)) & theirPawns; - } - } - - // Test for candidate passed pawn - candidate = !passed - && pos.file_is_half_open(them, f) - && ( count_1s_max_15(neighboring_files_bb(f) & (behind_bb(us, r) | rank_bb(r)) & ourPawns) - - count_1s_max_15(neighboring_files_bb(f) & in_front_bb(us, r) & theirPawns) - >= 0); - - // In order to prevent doubled passed pawns from receiving a too big - // bonus, only the frontmost passed pawn on each file is considered as - // a true passed pawn. - if (passed && (ourPawns & squares_in_front_of(us, s))) - { - // candidate = true; - passed = false; - } - - // Score this pawn - Value mv = Value(0), ev = Value(0); - if (isolated) - { - mv -= IsolatedPawnMidgamePenalty[f]; - ev -= IsolatedPawnEndgamePenalty[f]; - if (pos.file_is_half_open(them, f)) - { - mv -= IsolatedPawnMidgamePenalty[f] / 2; - ev -= IsolatedPawnEndgamePenalty[f] / 2; - } - } - if (doubled) - { - mv -= DoubledPawnMidgamePenalty[f]; - ev -= DoubledPawnEndgamePenalty[f]; - } - if (backward) - { - mv -= BackwardPawnMidgamePenalty[f]; - ev -= BackwardPawnEndgamePenalty[f]; - if (pos.file_is_half_open(them, f)) - { - mv -= BackwardPawnMidgamePenalty[f] / 2; - ev -= BackwardPawnEndgamePenalty[f] / 2; - } - } - if (chain) - { - mv += ChainMidgameBonus[f]; - ev += ChainEndgameBonus[f]; - } - if (candidate) - { - mv += CandidateMidgameBonus[relative_rank(us, s)]; - ev += CandidateEndgameBonus[relative_rank(us, s)]; - } - - mgValue[us] += mv; - egValue[us] += ev; - - // If the pawn is passed, set the square of the pawn in the passedPawns - // bitboard - if (passed) - set_bit(&(pi->passedPawns), s); - } // while(pawns) - } // for(colors) - - pi->mgValue = int16_t(mgValue[WHITE] - mgValue[BLACK]); - pi->egValue = int16_t(egValue[WHITE] - egValue[BLACK]); + // Evaluate pawns for both colors + Values whiteValues = evaluate_pawns(pos, whitePawns, blackPawns, pi); + Values blackValues = evaluate_pawns(pos, blackPawns, whitePawns, pi); + + pi->mgValue = int16_t(whiteValues.first - blackValues.first); + pi->egValue = int16_t(whiteValues.second - blackValues.second); return pi; } + + +/// PawnInfoTable::evaluate_pawns() evaluates each pawn of the given color + +template +PawnInfoTable::Values PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, + Bitboard theirPawns, PawnInfo* pi) { + Square s; + File f; + Rank r; + bool passed, isolated, doubled, chain, backward, candidate; + int bonus; + Value mgValue = Value(0); + Value egValue = Value(0); + Bitboard pawns = ourPawns; + + // Initialize pawn storm scores by giving bonuses for open files + for (File f = FILE_A; f <= FILE_H; f++) + if (!(ourPawns & file_bb(f))) + { + pi->ksStormValue[Us] += KStormOpenFileBonus[f]; + pi->qsStormValue[Us] += QStormOpenFileBonus[f]; + pi->halfOpenFiles[Us] |= (1 << f); + } + + // Loop through all pawns of the current color and score each pawn + while (pawns) + { + s = pop_1st_bit(&pawns); + f = square_file(s); + r = square_rank(s); + + assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN)); + + // Passed, isolated or doubled pawn? + passed = Position::pawn_is_passed(theirPawns, Us, s); + isolated = Position::pawn_is_isolated(ourPawns, s); + doubled = Position::pawn_is_doubled(ourPawns, Us, s); + + // We calculate kingside and queenside pawn storm + // scores for both colors. These are used when evaluating + // middle game positions with opposite side castling. + // + // Each pawn is given a base score given by a piece square table + // (KStormTable[] or QStormTable[]). Pawns which seem to have good + // chances of creating an open file by exchanging itself against an + // enemy pawn on an adjacent file gets an additional bonus. + + // Kingside pawn storms + bonus = KStormTable[relative_square(Us, s)]; + if (f >= FILE_F) + { + Bitboard b = outpost_mask(Us, s) & theirPawns & (FileFBB | FileGBB | FileHBB); + while (b) + { + Square s2 = pop_1st_bit(&b); + if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2))) + { + // The enemy pawn has no pawn beside itself, which makes it + // particularly vulnerable. Big bonus, especially against a + // weakness on the rook file. + if (square_file(s2) == FILE_H) + bonus += 4*StormLeverBonus[f] - 8*square_distance(s, s2); + else + bonus += 2*StormLeverBonus[f] - 4*square_distance(s, s2); + } else + // There is at least one enemy pawn beside the enemy pawn we look + // at, which means that the pawn has somewhat better chances of + // defending itself by advancing. Smaller bonus. + bonus += StormLeverBonus[f] - 2*square_distance(s, s2); + } + } + pi->ksStormValue[Us] += bonus; + + // Queenside pawn storms + bonus = QStormTable[relative_square(Us, s)]; + if (f <= FILE_C) + { + Bitboard b = outpost_mask(Us, s) & theirPawns & (FileABB | FileBBB | FileCBB); + while (b) + { + Square s2 = pop_1st_bit(&b); + if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2))) + { + // The enemy pawn has no pawn beside itself, which makes it + // particularly vulnerable. Big bonus, especially against a + // weakness on the rook file. + if (square_file(s2) == FILE_A) + bonus += 4*StormLeverBonus[f] - 16*square_distance(s, s2); + else + bonus += 2*StormLeverBonus[f] - 8*square_distance(s, s2); + } else + // There is at least one enemy pawn beside the enemy pawn we look + // at, which means that the pawn has somewhat better chances of + // defending itself by advancing. Smaller bonus. + bonus += StormLeverBonus[f] - 4*square_distance(s, s2); + } + } + pi->qsStormValue[Us] += bonus; + + // Member of a pawn chain (but not the backward one)? We could speed up + // the test a little by introducing an array of masks indexed by color + // and square for doing the test, but because everything is hashed, + // it probably won't make any noticable difference. + chain = ourPawns + & neighboring_files_bb(f) + & (rank_bb(r) | rank_bb(r - (Us == WHITE ? 1 : -1))); + + // Test for backward pawn + // + // If the pawn is passed, isolated, or member of a pawn chain + // it cannot be backward. If can capture an enemy pawn or if + // there are friendly pawns behind on neighboring files it cannot + // be backward either. + if ( (passed | isolated | chain) + || (ourPawns & behind_bb(Us, r) & neighboring_files_bb(f)) + || (pos.attacks_from(s, Us) & theirPawns)) + backward = false; + else + { + // We now know that there are no friendly pawns beside or behind this + // pawn on neighboring files. We now check whether the pawn is + // backward by looking in the forward direction on the neighboring + // files, and seeing whether we meet a friendly or an enemy pawn first. + Bitboard b = pos.attacks_from(s, Us); + + // Note that we are sure to find something because pawn is not passed + // nor isolated, so loop is potentially infinite, but it isn't. + while (!(b & (ourPawns | theirPawns))) + Us == WHITE ? b <<= 8 : b >>= 8; + + // The friendly pawn needs to be at least two ranks closer than the enemy + // pawn in order to help the potentially backward pawn advance. + backward = (b | (Us == WHITE ? b << 8 : b >> 8)) & theirPawns; + } + + // Test for candidate passed pawn + candidate = !passed + && !(theirPawns & file_bb(f)) + && ( count_1s_max_15(neighboring_files_bb(f) & (behind_bb(Us, r) | rank_bb(r)) & ourPawns) + - count_1s_max_15(neighboring_files_bb(f) & in_front_bb(Us, r) & theirPawns) + >= 0); + + // In order to prevent doubled passed pawns from receiving a too big + // bonus, only the frontmost passed pawn on each file is considered as + // a true passed pawn. + if (passed && (ourPawns & squares_in_front_of(Us, s))) + passed = false; + + // Score this pawn + if (passed) + set_bit(&(pi->passedPawns), s); + + if (isolated) + { + mgValue -= IsolatedPawnMidgamePenalty[f]; + egValue -= IsolatedPawnEndgamePenalty[f]; + if (!(theirPawns & file_bb(f))) + { + mgValue -= IsolatedPawnMidgamePenalty[f] / 2; + egValue -= IsolatedPawnEndgamePenalty[f] / 2; + } + } + if (doubled) + { + mgValue -= DoubledPawnMidgamePenalty[f]; + egValue -= DoubledPawnEndgamePenalty[f]; + } + if (backward) + { + mgValue -= BackwardPawnMidgamePenalty[f]; + egValue -= BackwardPawnEndgamePenalty[f]; + if (!(theirPawns & file_bb(f))) + { + mgValue -= BackwardPawnMidgamePenalty[f] / 2; + egValue -= BackwardPawnEndgamePenalty[f] / 2; + } + } + if (chain) + { + mgValue += ChainMidgameBonus[f]; + egValue += ChainEndgameBonus[f]; + } + if (candidate) + { + mgValue += CandidateMidgameBonus[relative_rank(Us, s)]; + egValue += CandidateEndgameBonus[relative_rank(Us, s)]; + } + } // while (pawns) + + return Values(mgValue, egValue); +} + + +/// PawnInfo::updateShelter calculates and caches king shelter. It is called +/// only when king square changes, about 20% of total get_king_shelter() calls. +int PawnInfo::updateShelter(const Position& pos, Color c, Square ksq) { + + unsigned shelter = 0; + Bitboard pawns = pos.pieces(PAWN, c) & this_and_neighboring_files_bb(ksq); + unsigned r = ksq & (7 << 3); + for (int i = 1, k = (c ? -8 : 8); i < 4; i++) + { + r += k; + shelter += BitCount8Bit[(pawns >> r) & 0xFF] * (128 >> i); + } + kingSquares[c] = ksq; + kingShelters[c] = shelter; + return shelter; +}