X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=c0e355b7522b4044a7f4c5d1ab89620abdfd5ed5;hp=d654fec9c414a75be3fd6d406fdaf8fc24053613;hb=93c9f342ca4f2230021ddbca83a991ff90a6a246;hpb=a530fc2b600da4e9247a0e0242dead246d824c68 diff --git a/src/search.cpp b/src/search.cpp index d654fec9..c0e355b7 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -172,10 +172,16 @@ namespace { const bool PruneDefendingMoves = false; const bool PruneBlockingMoves = false; + // Only move margin + const Value OnlyMoveMargin = Value(100); + // Margins for futility pruning in the quiescence search, and at frontier // and near frontier nodes. const Value FutilityMarginQS = Value(0x80); + // Each move futility margin is decreased + const Value IncrementalFutilityMargin = Value(0x8); + // Remaining depth: 1 ply 1.5 ply 2 ply 2.5 ply 3 ply 3.5 ply const Value FutilityMargins[12] = { Value(0x100), Value(0x120), Value(0x200), Value(0x220), Value(0x250), Value(0x270), // 4 ply 4.5 ply 5 ply 5.5 ply 6 ply 6.5 ply @@ -274,7 +280,7 @@ namespace { Value id_loop(const Position& pos, Move searchMoves[]); Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value alpha, Value beta); Value search_pv(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID); - Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID); + Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID, Move forbiddenMove = MOVE_NONE); Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID); void sp_search(SplitPoint* sp, int threadID); void sp_search_pv(SplitPoint* sp, int threadID); @@ -1129,12 +1135,34 @@ namespace { moveIsCheck = pos.move_is_check(move, ci); captureOrPromotion = pos.move_is_capture_or_promotion(move); - movesSearched[moveCount++] = ss[ply].currentMove = move; + movesSearched[moveCount++] = move; // Decide the new search depth ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous); + + // Only move extension + if ( moveCount == 1 + && ext < OnePly + && depth >= 8 * OnePly + && tte + && (tte->type() & VALUE_TYPE_LOWER) + && tte->move() != MOVE_NONE + && tte->depth() >= depth - 3 * OnePly) + { + Value ttValue = value_from_tt(tte->value(), ply); + if (abs(ttValue) < VALUE_KNOWN_WIN) + { + Value excValue = search(pos, ss, ttValue - OnlyMoveMargin, depth / 2, ply, false, threadID, tte->move()); + if (excValue < ttValue - OnlyMoveMargin) + ext = OnePly; + } + } + newDepth = depth - OnePly + ext; + // Update current move + ss[ply].currentMove = move; + // Make and search the move pos.do_move(move, st, ci, moveIsCheck); @@ -1248,7 +1276,7 @@ namespace { // search() is the search function for zero-width nodes. Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, - int ply, bool allowNullmove, int threadID) { + int ply, bool allowNullmove, int threadID, Move forbiddenMove) { assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); assert(ply >= 0 && ply < PLY_MAX); @@ -1260,7 +1288,7 @@ namespace { const TTEntry* tte; Move ttMove, move; Depth ext, newDepth; - Value approximateEval, nullValue, value, futilityValue; + Value approximateEval, nullValue, value, futilityValue, futilityValueScaled; bool isCheck, useFutilityPruning, singleReply, moveIsCheck, captureOrPromotion, dangerous; bool mateThreat = false; int moveCount = 0; @@ -1290,8 +1318,14 @@ namespace { if (value_mate_in(ply + 1) < beta) return beta - 1; + // Position key calculation + Key posKey = pos.get_key(); + + if (forbiddenMove != MOVE_NONE) + posKey ^= Position::zobExclusion; + // Transposition table lookup - tte = TT.retrieve(pos.get_key()); + tte = TT.retrieve(posKey); ttMove = (tte ? tte->move() : MOVE_NONE); if (tte && ok_to_use_TT(tte, depth, beta, ply)) @@ -1314,7 +1348,13 @@ namespace { ss[ply].currentMove = MOVE_NULL; pos.do_null_move(st); - int R = (depth >= 5 * OnePly ? 4 : 3); // Null move dynamic reduction + + // Null move dynamic reduction based on depth + int R = (depth >= 5 * OnePly ? 4 : 3); + + // Null move dynamic reduction based on value + if (approximateEval - beta > PawnValueMidgame) + R++; nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID); @@ -1354,8 +1394,9 @@ namespace { && ttMove == MOVE_NONE && !pos.has_pawn_on_7th(pos.side_to_move())) { - Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); - if (v < beta - RazorMargins[int(depth) - 2]) + Value rbeta = beta - RazorMargins[int(depth) - 2]; + Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), ply, threadID); + if (v < rbeta) return v; } @@ -1378,6 +1419,9 @@ namespace { if (tte && (tte->type() & VALUE_TYPE_EVAL)) futilityValue = value_from_tt(tte->value(), ply) + FutilityMargins[int(depth) - 2]; + // Move count pruning limit + const int MCLimit = 3 + (1 << (3*int(depth)/8)); + // Loop through all legal moves until no moves remain or a beta cutoff // occurs. while ( bestValue < beta @@ -1386,24 +1430,97 @@ namespace { { assert(move_is_ok(move)); + if (move == forbiddenMove) + continue; + singleReply = (isCheck && mp.number_of_evasions() == 1); moveIsCheck = pos.move_is_check(move, ci); captureOrPromotion = pos.move_is_capture_or_promotion(move); - movesSearched[moveCount++] = ss[ply].currentMove = move; + movesSearched[moveCount++] = move; // Decide the new search depth ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous); + + // Only move extension + if ( forbiddenMove == MOVE_NONE + && moveCount == 1 + && ext < OnePly + && depth >= 8 * OnePly + && tte + && (tte->type() & VALUE_TYPE_LOWER) + && tte->move() != MOVE_NONE + && tte->depth() >= depth - 3 * OnePly) + { + Value ttValue = value_from_tt(tte->value(), ply); + if (abs(ttValue) < VALUE_KNOWN_WIN) + { + Value excValue = search(pos, ss, ttValue - OnlyMoveMargin, depth / 2, ply, false, threadID, tte->move()); + if (excValue < ttValue - OnlyMoveMargin) + ext = OnePly; + } + } + newDepth = depth - OnePly + ext; + // Update current move + ss[ply].currentMove = move; + // Futility pruning if ( useFutilityPruning && !dangerous && !captureOrPromotion && move != ttMove) { + //std::cout << std::endl; + //for (int d = 2; d < 14; d++) + // std::cout << d << ", " << 64*(1+bitScanReverse32(d*d)) << std::endl; + + //std::cout << std::endl; +/* + 64*(1+bitScanReverse32(d*d)) + + 2 -> 256 - 256 + 3 -> 288 - 320 + 4 -> 512 - 384 + 5 -> 544 - 384 + 6 -> 592 - 448 + 7 -> 624 - 448 + 8 -> 672 - 512 + 9 -> 704 - 512 + 10 -> 832 - 512 + 11 -> 864 - 512 + 12 -> 928 - 576 + 13 -> 960 - 576 + + 300 + 2*(1 << (3*d/4)) + + 2 -> 256 - 304 + 3 -> 288 - 308 + 4 -> 512 - 316 + 5 -> 544 - 316 + 6 -> 592 - 332 + 7 -> 624 - 364 + 8 -> 672 - 428 + 9 -> 704 - 428 + 10 -> 832 - 556 + 11 -> 864 - 812 + 12 -> 928 - 1324 + 13 -> 960 - 1324 + + + 3 + (1 << (3*int(depth)/8)) + + 1 * onePly - > moveCount >= 4 + 2 * onePly - > moveCount >= 5 + 3 * onePly - > moveCount >= 7 + 4 * onePly - > moveCount >= 11 + 5 * onePly - > moveCount >= 11 + 6 * onePly - > moveCount >= 19 + 7 * onePly - > moveCount >= 35 +*/ // History pruning. See ok_to_prune() definition - if ( moveCount >= 2 + int(depth) + if ( moveCount >= MCLimit && ok_to_prune(pos, move, ss[ply].threatMove, depth) && bestValue > value_mated_in(PLY_MAX)) continue; @@ -1413,12 +1530,14 @@ namespace { { if (futilityValue == VALUE_NONE) futilityValue = evaluate(pos, ei, threadID) - + FutilityMargins[int(depth) - 2]; + + 64*(2+bitScanReverse32(int(depth) * int(depth))); + + futilityValueScaled = futilityValue - moveCount * IncrementalFutilityMargin; - if (futilityValue < beta) + if (futilityValueScaled < beta) { - if (futilityValue > bestValue) - bestValue = futilityValue; + if (futilityValueScaled > bestValue) + bestValue = futilityValueScaled; continue; } } @@ -1478,7 +1597,7 @@ namespace { // All legal moves have been searched. A special case: If there were // no legal moves, it must be mate or stalemate. if (moveCount == 0) - return (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW); + return (forbiddenMove == MOVE_NONE ? (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW) : beta - 1); // If the search is not aborted, update the transposition table, // history counters, and killer moves. @@ -1486,7 +1605,7 @@ namespace { return bestValue; if (bestValue < beta) - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE); + TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE); else { BetaCounter.add(pos.side_to_move(), depth, threadID); @@ -1496,7 +1615,7 @@ namespace { update_history(pos, move, depth, movesSearched, moveCount); update_killers(move, ss[ply]); } - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move); + TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move); } assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);