X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fevaluate.cpp;h=9c2b70a7acb90509200b56c42f1a287bb44155a2;hp=c86af7803db8a3e6861ee81c2d45b6c200f0261a;hb=18c9b5ee863bf4764ddb426b7d3b060683ff4710;hpb=33bd67e052e26079cbb7e5e03c93f518f25701c3 diff --git a/src/evaluate.cpp b/src/evaluate.cpp index c86af780..9c2b70a7 100644 --- a/src/evaluate.cpp +++ b/src/evaluate.cpp @@ -343,13 +343,8 @@ Value do_evaluate(const Position& pos, Value& margin) { // If one side has only a king, check whether exists any unstoppable passed pawn if (!pos.non_pawn_material(WHITE) || !pos.non_pawn_material(BLACK)) - { bonus += evaluate_unstoppable_pawns(pos, ei); - if (Trace) - trace_add(UNSTOPPABLE, evaluate_unstoppable_pawns(pos, ei)); - } - // Evaluate space for both sides, only in middle-game. if (mi->space_weight()) { @@ -400,6 +395,7 @@ Value do_evaluate(const Position& pos, Value& margin) { trace_add(MOBILITY, apply_weight(mobilityWhite, Weights[Mobility]), apply_weight(mobilityBlack, Weights[Mobility])); trace_add(THREAT, evaluate_threats(pos, ei), evaluate_threats(pos, ei)); trace_add(PASSED, evaluate_passed_pawns(pos, ei), evaluate_passed_pawns(pos, ei)); + trace_add(UNSTOPPABLE, evaluate_unstoppable_pawns(pos, ei)); trace_add(TOTAL, bonus); TraceStream << "\nUncertainty margin: White: " << to_cp(margins[WHITE]) << ", Black: " << to_cp(margins[BLACK]) @@ -899,166 +895,171 @@ namespace { return apply_weight(bonus, Weights[PassedPawns]); } + // evaluate_unstoppable_pawns() evaluates the unstoppable passed pawns for both sides + template Score evaluate_unstoppable_pawns(const Position& pos, EvalInfo& ei) { const BitCountType Max15 = HasPopCnt ? CNT_POPCNT : CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15; + Bitboard b1, b2, queeningPath, candidates, supBB, sacBB; + Square s1, s2, queeningSquare, supSq, sacSq; + Color c, winnerSide, loserSide; + bool pathDefended, opposed; + int pliesToGo, movesToGo, oppMovesToGo; + int pliesToQueen[] = { 256, 256 }; + // Step 1. Hunt for unstoppable pawns. If we find at least one, record how many plies // are required for promotion - int pliesToGo[2] = {256, 256}; - - for (Color c = WHITE; c <= BLACK; c++) + for (c = WHITE; c <= BLACK; c++) { // Skip if other side has non-pawn pieces if (pos.non_pawn_material(opposite_color(c))) continue; - Bitboard b = ei.pi->passed_pawns(c); + b1 = ei.pi->passed_pawns(c); - while (b) + while (b1) { - Square s = pop_1st_bit(&b); - Square queeningSquare = relative_square(c, make_square(square_file(s), RANK_8)); + s1 = pop_1st_bit(&b1); + queeningSquare = relative_square(c, make_square(square_file(s1), RANK_8)); + queeningPath = squares_in_front_of(c, s1); - int mtg = RANK_8 - relative_rank(c, s) - int(relative_rank(c, s) == RANK_2); - int oppmtg = square_distance(pos.king_square(opposite_color(c)), queeningSquare) - int(c != pos.side_to_move()); - bool pathDefended = ((ei.attackedBy[c][0] & squares_in_front_of(c, s)) == squares_in_front_of(c, s)); + // Compute plies from queening and check direct advancement + movesToGo = rank_distance(s1, queeningSquare) - int(relative_rank(c, s1) == RANK_2); + oppMovesToGo = square_distance(pos.king_square(opposite_color(c)), queeningSquare) - int(c != pos.side_to_move()); + pathDefended = ((ei.attackedBy[c][0] & queeningPath) == queeningPath); - if (mtg >= oppmtg && !pathDefended) + if (movesToGo >= oppMovesToGo && !pathDefended) continue; - int blockerCount = count_1s(squares_in_front_of(c, s) & pos.occupied_squares()); - mtg += blockerCount; + // Opponent king cannot block because path is defended and position + // is not in check. So only friendly pieces can be blockers. + assert(!pos.in_check()); + assert(queeningPath & pos.occupied_squares() == queeningPath & pos.pieces_of_color(c)); + + // Add moves needed to free the path from friendly pieces and retest condition + movesToGo += count_1s(queeningPath & pos.pieces_of_color(c)); - if (mtg >= oppmtg && !pathDefended) + if (movesToGo >= oppMovesToGo && !pathDefended) continue; - int ptg = 2 * mtg - int(c == pos.side_to_move()); + pliesToGo = 2 * movesToGo - int(c == pos.side_to_move()); - if (ptg < pliesToGo[c]) - pliesToGo[c] = ptg; + if (pliesToGo < pliesToQueen[c]) + pliesToQueen[c] = pliesToGo; } } - // Step 2. If either side cannot promote at least three plies before the other side then - // situation becomes too complex and we give up. Otherwise we determine the possibly "winning side" - if (abs(pliesToGo[WHITE] - pliesToGo[BLACK]) < 3) - return make_score(0, 0); + // Step 2. If either side cannot promote at least three plies before the other side then situation + // becomes too complex and we give up. Otherwise we determine the possibly "winning side" + if (abs(pliesToQueen[WHITE] - pliesToQueen[BLACK]) < 3) + return SCORE_ZERO; - Color winnerSide = (pliesToGo[WHITE] < pliesToGo[BLACK] ? WHITE : BLACK); - Color loserSide = opposite_color(winnerSide); + winnerSide = (pliesToQueen[WHITE] < pliesToQueen[BLACK] ? WHITE : BLACK); + loserSide = opposite_color(winnerSide); // Step 3. Can the losing side possibly create a new passed pawn and thus prevent the loss? // We collect the potential candidates in potentialBB. - Bitboard pawnBB = pos.pieces(PAWN, loserSide); - Bitboard potentialBB = pawnBB; - const Bitboard passedBB = ei.pi->passed_pawns(loserSide); + b1 = candidates = pos.pieces(PAWN, loserSide); - while(pawnBB) + while (b1) { - Square psq = pop_1st_bit(&pawnBB); + s1 = pop_1st_bit(&b1); - // Check direct advancement - int mtg = RANK_8 - relative_rank(loserSide, psq) - int(relative_rank(loserSide, psq) == RANK_2); - int ptg = 2 * mtg - int(loserSide == pos.side_to_move()); + // Compute plies from queening + queeningSquare = relative_square(loserSide, make_square(square_file(s1), RANK_8)); + movesToGo = rank_distance(s1, queeningSquare) - int(relative_rank(loserSide, s1) == RANK_2); + pliesToGo = 2 * movesToGo - int(loserSide == pos.side_to_move()); - // Check if (without even considering any obstacles) we're too far away - if (pliesToGo[winnerSide] + 3 <= ptg) - { - clear_bit(&potentialBB, psq); - continue; - } - - // If this is passed pawn, then it _may_ promote in time. We give up. - if (bit_is_set(passedBB, psq)) - return make_score(0, 0); - - // Doubled pawn is worthless - if (squares_in_front_of(loserSide, psq) & (pos.pieces(PAWN, loserSide))) - { - clear_bit(&potentialBB, psq); - continue; - } + // Check if (without even considering any obstacles) we're too far away or doubled + if ( pliesToQueen[winnerSide] + 3 <= pliesToGo + || (squares_in_front_of(loserSide, s1) & pos.pieces(PAWN, loserSide))) + clear_bit(&candidates, s1); } - // Step 4. Check new passed pawn creation through king capturing and sacrifises - pawnBB = potentialBB; + // If any candidate is already a passed pawn it _may_ promote in time. We give up. + if (candidates & ei.pi->passed_pawns(loserSide)) + return SCORE_ZERO; + + // Step 4. Check new passed pawn creation through king capturing and sacrifices + b1 = candidates; - while(pawnBB) + while (b1) { - Square psq = pop_1st_bit(&pawnBB); + s1 = pop_1st_bit(&b1); - int mtg = RANK_8 - relative_rank(loserSide, psq) - int(relative_rank(loserSide, psq) == RANK_2); - int ptg = 2 * mtg - int(loserSide == pos.side_to_move()); + // Compute plies from queening + queeningSquare = relative_square(loserSide, make_square(square_file(s1), RANK_8)); + movesToGo = rank_distance(s1, queeningSquare) - int(relative_rank(loserSide, s1) == RANK_2); + pliesToGo = 2 * movesToGo - int(loserSide == pos.side_to_move()); // Generate list of obstacles - Bitboard obsBB = passed_pawn_mask(loserSide, psq) & pos.pieces(PAWN, winnerSide); - const bool pawnIsOpposed = squares_in_front_of(loserSide, psq) & obsBB; - assert(obsBB); + opposed = squares_in_front_of(loserSide, s1) & pos.pieces(PAWN, winnerSide); + b2 = passed_pawn_mask(loserSide, s1) & pos.pieces(PAWN, winnerSide); + + assert(b2); // How many plies does it take to remove all the obstacles? int sacptg = 0; int realObsCount = 0; int minKingDist = 256; + int kingptg = 256; - while(obsBB) + while (b2) { - Square obSq = pop_1st_bit(&obsBB); - int minMoves = 256; + s2 = pop_1st_bit(&b2); + movesToGo = 256; - // Check pawns that can give support to overcome obstacle (Eg. wp: a4,b4 bp: b2. b4 is giving support) - if (!pawnIsOpposed && square_file(psq) != square_file(obSq)) + // Check pawns that can give support to overcome obstacle, for instance + // black pawns: a4, b4 white: b2 then pawn in b4 is giving support. + if (!opposed && square_file(s1) != square_file(s2)) { - Bitboard supBB = in_front_bb(winnerSide, Square(obSq + (winnerSide == WHITE ? 8 : -8))) - & neighboring_files_bb(psq) & potentialBB; + supBB = in_front_bb(winnerSide, s2 + pawn_push(winnerSide)) & neighboring_files_bb(s1) & candidates; - while(supBB) // This while-loop could be replaced with supSq = LSB/MSB(supBB) (depending on color) + while (supBB) // This while-loop could be replaced with supSq = LSB/MSB(supBB) (depending on color) { - Square supSq = pop_1st_bit(&supBB); - int dist = square_distance(obSq, supSq); - minMoves = Min(minMoves, dist - 2); + supSq = pop_1st_bit(&supBB); + movesToGo = Min(movesToGo, square_distance(s2, supSq) - 2); } - } - // Check pawns that can be sacrifised - Bitboard sacBB = passed_pawn_mask(winnerSide, obSq) & neighboring_files_bb(obSq) & potentialBB & ~(1ULL << psq); + // Check pawns that can be sacrificed + sacBB = passed_pawn_mask(winnerSide, s2) & neighboring_files_bb(s2) & candidates & ~(1ULL << s1); - while(sacBB) // This while-loop could be replaced with sacSq = LSB/MSB(sacBB) (depending on color) + while (sacBB) // This while-loop could be replaced with sacSq = LSB/MSB(sacBB) (depending on color) { - Square sacSq = pop_1st_bit(&sacBB); - int dist = square_distance(obSq, sacSq); - minMoves = Min(minMoves, dist - 2); + sacSq = pop_1st_bit(&sacBB); + movesToGo = Min(movesToGo, square_distance(s2, sacSq) - 2); } - // If obstacle can be destroyed with immediate pawn sacrifise, it's not real obstacle - if (minMoves <= 0) + // Good, obstacle can be destroyed with an immediate pawn sacrifice, + // it's not a real obstacle and we have nothing to add to pliesToGo. + if (movesToGo <= 0) continue; - // Pawn sac calculations - sacptg += minMoves * 2; - - // King capture calc + // Plies needed to sacrifice the pawn + sacptg += movesToGo * 2; realObsCount++; - int kingDist = square_distance(pos.king_square(loserSide), obSq); - minKingDist = Min(minKingDist, kingDist); + + // Plies needed for the king to capture opposing pawn + minKingDist = Min(minKingDist, square_distance(pos.king_square(loserSide), s2)); + kingptg = (minKingDist + realObsCount) * 2; } - // Check if pawn sac plan _may_ save the day - if (pliesToGo[winnerSide] + 3 > ptg + sacptg) - return make_score(0, 0); + // Check if pawn sacrifice plan _may_ save the day + if (pliesToQueen[winnerSide] + 3 > pliesToGo + sacptg) + return SCORE_ZERO; // Check if king capture plan _may_ save the day (contains some false positives) - int kingptg = (minKingDist + realObsCount) * 2; - if (pliesToGo[winnerSide] + 3 > ptg + kingptg) - return make_score(0, 0); + if (pliesToQueen[winnerSide] + 3 > pliesToGo + kingptg) + return SCORE_ZERO; } - // Step 5. Assign bonus - const int Sign[2] = {1, -1}; - return Sign[winnerSide] * make_score(0, (Value) 0x500 - 0x20 * pliesToGo[winnerSide]); + // Winning pawn is unstoppable and will promote as first, return big score + Score score = make_score(0, (Value) 0x500 - 0x20 * pliesToQueen[winnerSide]); + return winnerSide == WHITE ? score : -score; }