X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=dd9e45b92e33b3ad606b6c10a40294fa77349058;hp=98bf24a828e7174e48d4687785b7579b81e3406f;hb=aa86d81f79a92a5a050f73e1443190e53aa9f2ed;hpb=77eec9f9cb50e742151273da6e4cd2847fe9ec1f diff --git a/src/search.cpp b/src/search.cpp index 98bf24a8..dd9e45b9 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -119,7 +119,6 @@ namespace { inline Move get_move_pv(int moveNum, int i) const; inline int64_t get_move_cumulative_nodes(int moveNum) const; inline int move_count() const; - Move scan_for_easy_move() const; inline void sort(); void sort_multipv(int n); @@ -140,7 +139,7 @@ namespace { // Use internal iterative deepening? const bool UseIIDAtPVNodes = true; - const bool UseIIDAtNonPVNodes = false; + const bool UseIIDAtNonPVNodes = true; // Internal iterative deepening margin. At Non-PV moves, when // UseIIDAtNonPVNodes is true, we do an internal iterative deepening @@ -172,6 +171,10 @@ namespace { const bool PruneDefendingMoves = false; const bool PruneBlockingMoves = false; + // If the TT move is at least SingleReplyMargin better then the + // remaining ones we will extend it. + const Value SingleReplyMargin = Value(0x20); + // Margins for futility pruning in the quiescence search, and at frontier // and near frontier nodes. const Value FutilityMarginQS = Value(0x80); @@ -179,10 +182,6 @@ namespace { // 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 - Value(0x2A0), Value(0x2C0), Value(0x340), Value(0x360), Value(0x3A0), Value(0x3C0) }; // Razoring const Depth RazorDepth = 4*OnePly; @@ -277,7 +276,7 @@ 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, Move forbiddenMove = MOVE_NONE); + Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID, Move excludedMove = 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); @@ -289,7 +288,7 @@ namespace { bool move_is_killer(Move m, const SearchStack& ss); Depth extension(const Position& pos, Move m, bool pvNode, bool capture, bool check, bool singleReply, bool mateThreat, bool* dangerous); bool ok_to_do_nullmove(const Position& pos); - bool ok_to_prune(const Position& pos, Move m, Move threat, Depth d); + bool ok_to_prune(const Position& pos, Move m, Move threat); bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply); void update_history(const Position& pos, Move m, Depth depth, Move movesSearched[], int moveCount); void update_killers(Move m, SearchStack& ss); @@ -374,7 +373,7 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, { Move bookMove; if (get_option_value_string("Book File") != OpeningBook.file_name()) - OpeningBook.open("book.bin"); + OpeningBook.open(get_option_value_string("Book File")); bookMove = OpeningBook.get_move(pos); if (bookMove != MOVE_NONE) @@ -403,13 +402,13 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, Problem = false; ExactMaxTime = maxTime; + if (button_was_pressed("New Game")) + loseOnTime = false; // reset at the beginning of a new game + // Read UCI option values TT.set_size(get_option_value_int("Hash")); if (button_was_pressed("Clear Hash")) - { TT.clear(); - loseOnTime = false; // reset at the beginning of a new game - } bool PonderingEnabled = get_option_value_bool("Ponder"); MultiPV = get_option_value_int("MultiPV"); @@ -523,23 +522,36 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, << " moves to go: " << movesToGo << std::endl; - // We're ready to start thinking. Call the iterative deepening loop function - // - // FIXME we really need to cleanup all this LSN ugliness - if (!loseOnTime) + // LSN filtering. Used only for developing purpose. Disabled by default. + if ( UseLSNFiltering + && loseOnTime) { - Value v = id_loop(pos, searchMoves); - loseOnTime = ( UseLSNFiltering - && myTime < LSNTime - && myIncrement == 0 - && v < -LSNValue); + // Step 2. If after last move we decided to lose on time, do it now! + while (SearchStartTime + myTime + 1000 > get_system_time()) + ; // wait here } - else + + // We're ready to start thinking. Call the iterative deepening loop function + Value v = id_loop(pos, searchMoves); + + // LSN filtering. Used only for developing purpose. Disabled by default. + if (UseLSNFiltering) { - loseOnTime = false; // reset for next match - while (SearchStartTime + myTime + 1000 > get_system_time()) - ; // wait here - id_loop(pos, searchMoves); // to fail gracefully + // Step 1. If this is sudden death game and our position is hopeless, + // decide to lose on time. + if ( !loseOnTime // If we already lost on time, go to step 3. + && myTime < LSNTime + && myIncrement == 0 + && movesToGo == 0 + && v < -LSNValue) + { + loseOnTime = true; + } + else if (loseOnTime) + { + // Step 3. Now after stepping over the time limit, reset flag for next match. + loseOnTime = false; + } } if (UseLogFile) @@ -665,6 +677,14 @@ namespace { // searchMoves are verified, copied, scored and sorted RootMoveList rml(p, searchMoves); + if (rml.move_count() == 0) + { + if (PonderSearch) + wait_for_stop_or_ponderhit(); + + return pos.is_check()? -VALUE_MATE : VALUE_DRAW; + } + // Print RootMoveList c'tor startup scoring to the standard output, // so that we print information also for iteration 1. std::cout << "info depth " << 1 << "\ninfo depth " << 1 @@ -681,7 +701,11 @@ namespace { IterationInfo[1] = IterationInfoType(rml.get_move_score(0), rml.get_move_score(0)); Iteration = 1; - Move EasyMove = rml.scan_for_easy_move(); + // Is one move significantly better than others after initial scoring ? + Move EasyMove = MOVE_NONE; + if ( rml.move_count() == 1 + || rml.get_move_score(0) > rml.get_move_score(1) + EasyMoveMargin) + EasyMove = rml.get_move(0); // Iterative deepening loop while (Iteration < PLY_MAX) @@ -798,7 +822,6 @@ namespace { if (stopSearch) { - //FIXME: Implement fail-low emergency measures if (!PonderSearch) break; else @@ -1102,7 +1125,14 @@ namespace { return alpha; // Transposition table lookup. At PV nodes, we don't use the TT for - // pruning, but only for move ordering. + // pruning, but only for move ordering. This is to avoid problems in + // the following areas: + // + // * Repetition draw detection + // * Fifty move rule detection + // * Searching for a mate + // * Printing of full PV line + // tte = TT.retrieve(pos.get_key()); ttMove = (tte ? tte->move() : MOVE_NONE); @@ -1111,6 +1141,7 @@ namespace { { search_pv(pos, ss, alpha, beta, depth-2*OnePly, ply, threadID); ttMove = ss[ply].pv[ply]; + tte = TT.retrieve(pos.get_key()); } // Initialize a MovePicker object for the current position, and prepare @@ -1132,12 +1163,38 @@ namespace { moveIsCheck = pos.move_is_check(move, ci); captureOrPromotion = pos.move_is_capture_or_promotion(move); - movesSearched[moveCount++] = ss[ply].currentMove = move; - // Decide the new search depth ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous); + + // We want to extend the TT move if it is much better then remaining ones. + // To verify this we do a reduced search on all the other moves but the ttMove, + // if result is lower then TT value minus a margin then we assume ttMove is the + // only one playable. It is a kind of relaxed single reply extension. + if ( depth >= 6 * OnePly + && tte + && move == tte->move() + && ext < OnePly + && is_lower_bound(tte->type()) + && 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 - SingleReplyMargin, depth / 2, ply, false, threadID, move); + + // If search result is well below the foreseen score of the ttMove then we + // assume ttMove is the only one realistically playable and we extend it. + if (excValue < ttValue - SingleReplyMargin) + ext = OnePly; + } + } + newDepth = depth - OnePly + ext; + // Update current move + movesSearched[moveCount++] = ss[ply].currentMove = move; + // Make and search the move pos.do_move(move, st, ci, moveIsCheck); @@ -1251,7 +1308,7 @@ 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, Move forbiddenMove) { + int ply, bool allowNullmove, int threadID, Move excludedMove) { assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); assert(ply >= 0 && ply < PLY_MAX); @@ -1293,11 +1350,9 @@ 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; + // We don't want the score of a partial search to overwrite a previous full search + // TT value, so we use a different position key in case of an excluded move exsists. + Key posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key(); // Transposition table lookup tte = TT.retrieve(posKey); @@ -1305,7 +1360,7 @@ namespace { if (tte && ok_to_use_TT(tte, depth, beta, ply)) { - ss[ply].currentMove = ttMove; // can be MOVE_NONE + ss[ply].currentMove = ttMove; // Can be MOVE_NONE return value_from_tt(tte->value(), ply); } @@ -1377,10 +1432,11 @@ namespace { // Go with internal iterative deepening if we don't have a TT move if (UseIIDAtNonPVNodes && ttMove == MOVE_NONE && depth >= 8*OnePly && - evaluate(pos, ei, threadID) >= beta - IIDMargin) + !isCheck && evaluate(pos, ei, threadID) >= beta - IIDMargin) { search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID); ttMove = ss[ply].pv[ply]; + tte = TT.retrieve(pos.get_key()); } // Initialize a MovePicker object for the current position, and prepare @@ -1390,108 +1446,84 @@ namespace { futilityValue = VALUE_NONE; useFutilityPruning = depth < SelectiveDepth && !isCheck; + // Calculate depth dependant futility pruning parameters + const int FutilityMoveCountMargin = 3 + (1 << (3 * int(depth) / 8)); + const int FutilityValueMargin = 112 * bitScanReverse32(int(depth) * int(depth) / 2); + // Avoid calling evaluate() if we already have the score in TT if (tte && (tte->type() & VALUE_TYPE_EVAL)) - futilityValue = value_from_tt(tte->value(), ply) + FutilityMargins[int(depth) - 2]; + futilityValue = value_from_tt(tte->value(), ply) + FutilityValueMargin; - // 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. + // Loop through all legal moves until no moves remain or a beta cutoff occurs while ( bestValue < beta && (move = mp.get_next_move()) != MOVE_NONE && !thread_should_stop(threadID)) { assert(move_is_ok(move)); - if (move == forbiddenMove) + if (move == excludedMove) 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; - // Decide the new search depth ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous); + + // We want to extend the TT move if it is much better then remaining ones. + // To verify this we do a reduced search on all the other moves but the ttMove, + // if result is lower then TT value minus a margin then we assume ttMove is the + // only one playable. It is a kind of relaxed single reply extension. + if ( depth >= 8 * OnePly + && tte + && move == tte->move() + && !excludedMove // Do not allow recursive single-reply search + && ext < OnePly + && is_lower_bound(tte->type()) + && 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 - SingleReplyMargin, depth / 2, ply, false, threadID, move); + + // If search result is well below the foreseen score of the ttMove then we + // assume ttMove is the only one realistically playable and we extend it. + if (excValue < ttValue - SingleReplyMargin) + ext = OnePly; + } + } + newDepth = depth - OnePly + ext; + // Update current move + movesSearched[moveCount++] = 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 >= MCLimit - && ok_to_prune(pos, move, ss[ply].threatMove, depth) + // Move count based pruning + if ( moveCount >= FutilityMoveCountMargin + && ok_to_prune(pos, move, ss[ply].threatMove) && bestValue > value_mated_in(PLY_MAX)) continue; // Value based pruning - if (approximateEval < beta) - { - if (futilityValue == VALUE_NONE) - futilityValue = evaluate(pos, ei, threadID) - + 64*(2+bitScanReverse32(int(depth) * int(depth))); + if (futilityValue == VALUE_NONE) + futilityValue = evaluate(pos, ei, threadID) + FutilityValueMargin; - futilityValueScaled = futilityValue - moveCount * IncrementalFutilityMargin; + futilityValueScaled = futilityValue - moveCount * IncrementalFutilityMargin; - if (futilityValueScaled < beta) - { - if (futilityValueScaled > bestValue) - bestValue = futilityValueScaled; - continue; - } + if (futilityValueScaled < beta) + { + if (futilityValueScaled > bestValue) + bestValue = futilityValueScaled; + continue; } } @@ -1511,7 +1543,7 @@ namespace { value = -search(pos, ss, -(beta-1), newDepth-OnePly, ply+1, true, threadID); } else - value = beta; // Just to trigger next condition + value = beta; // Just to trigger next condition if (value >= beta) // Go with full depth non-pv search { @@ -1525,12 +1557,12 @@ namespace { // New best move? if (value > bestValue) { - bestValue = value; - if (value >= beta) - update_pv(ss, ply); + bestValue = value; + if (value >= beta) + update_pv(ss, ply); - if (value == value_mate_in(ply + 1)) - ss[ply].mateKiller = move; + if (value == value_mate_in(ply + 1)) + ss[ply].mateKiller = move; } // Split? @@ -1543,13 +1575,13 @@ namespace { && !thread_should_stop(threadID) && split(pos, ss, ply, &beta, &beta, &bestValue, futilityValue, approximateEval, depth, &moveCount, &mp, threadID, false)) - break; + break; } // 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 (forbiddenMove == MOVE_NONE ? (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW) : beta - 1); + return excludedMove ? beta - 1 : (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW); // If the search is not aborted, update the transposition table, // history counters, and killer moves. @@ -1622,10 +1654,10 @@ namespace { } ttMove = (tte ? tte->move() : MOVE_NONE); - // Evaluate the position statically isCheck = pos.is_check(); ei.futilityMargin = Value(0); // Manually initialize futilityMargin + // Evaluate the position statically if (isCheck) staticValue = -VALUE_INFINITE; @@ -1634,7 +1666,7 @@ namespace { // Use the cached evaluation score if possible assert(ei.futilityMargin == Value(0)); - staticValue = tte->value(); + staticValue = value_from_tt(tte->value(), ply); } else staticValue = evaluate(pos, ei, threadID); @@ -1779,6 +1811,9 @@ namespace { bool useFutilityPruning = sp->depth < SelectiveDepth && !isCheck; + const int FutilityMoveCountMargin = 3 + (1 << (3 * int(sp->depth) / 8)); + const int FutilityValueMargin = 112 * bitScanReverse32(int(sp->depth) * int(sp->depth) / 2); + while ( sp->bestValue < sp->beta && !thread_should_stop(threadID) && (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE) @@ -1804,33 +1839,31 @@ namespace { && !dangerous && !captureOrPromotion) { - // History pruning. See ok_to_prune() definition - if ( moveCount >= 2 + int(sp->depth) - && ok_to_prune(pos, move, ss[sp->ply].threatMove, sp->depth) + // Move count based pruning + if ( moveCount >= FutilityMoveCountMargin + && ok_to_prune(pos, move, ss[sp->ply].threatMove) && sp->bestValue > value_mated_in(PLY_MAX)) continue; // Value based pruning - if (sp->approximateEval < sp->beta) + if (sp->futilityValue == VALUE_NONE) { - if (sp->futilityValue == VALUE_NONE) - { - EvalInfo ei; - sp->futilityValue = evaluate(pos, ei, threadID) - + FutilityMargins[int(sp->depth) - 2]; - } + EvalInfo ei; + sp->futilityValue = evaluate(pos, ei, threadID) + FutilityValueMargin; + } - if (sp->futilityValue < sp->beta) + Value futilityValueScaled = sp->futilityValue - moveCount * IncrementalFutilityMargin; + + if (futilityValueScaled < sp->beta) + { + if (futilityValueScaled > sp->bestValue) // Less then 1% of cases { - if (sp->futilityValue > sp->bestValue) // Less then 1% of cases - { - lock_grab(&(sp->lock)); - if (sp->futilityValue > sp->bestValue) - sp->bestValue = sp->futilityValue; - lock_release(&(sp->lock)); - } - continue; + lock_grab(&(sp->lock)); + if (futilityValueScaled > sp->bestValue) + sp->bestValue = futilityValueScaled; + lock_release(&(sp->lock)); } + continue; } } @@ -2112,7 +2145,7 @@ namespace { moves[count].score = -qsearch(pos, ss, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 1, 0); pos.undo_move(moves[count].move); moves[count].pv[0] = moves[count].move; - moves[count].pv[1] = MOVE_NONE; // FIXME + moves[count].pv[1] = MOVE_NONE; count++; } sort(); @@ -2163,28 +2196,6 @@ namespace { } - // RootMoveList::scan_for_easy_move() is called at the end of the first - // iteration, and is used to detect an "easy move", i.e. a move which appears - // to be much bester than all the rest. If an easy move is found, the move - // is returned, otherwise the function returns MOVE_NONE. It is very - // important that this function is called at the right moment: The code - // assumes that the first iteration has been completed and the moves have - // been sorted. This is done in RootMoveList c'tor. - - Move RootMoveList::scan_for_easy_move() const { - - assert(count); - - if (count == 1) - return get_move(0); - - // moves are sorted so just consider the best and the second one - if (get_move_score(0) > get_move_score(1) + EasyMoveMargin) - return get_move(0); - - return MOVE_NONE; - } - // RootMoveList::sort() sorts the root move list at the beginning of a new // iteration. @@ -2450,14 +2461,13 @@ namespace { // non-tactical moves late in the move list close to the leaves are // candidates for pruning. - bool ok_to_prune(const Position& pos, Move m, Move threat, Depth d) { + bool ok_to_prune(const Position& pos, Move m, Move threat) { assert(move_is_ok(m)); assert(threat == MOVE_NONE || move_is_ok(threat)); assert(!pos.move_is_check(m)); assert(!pos.move_is_capture_or_promotion(m)); assert(!pos.move_is_passed_pawn_push(m)); - assert(d >= OnePly); Square mfrom, mto, tfrom, tto; @@ -2484,11 +2494,7 @@ namespace { && pos.move_attacks_square(m, tto)) return false; - // Case 4: Don't prune moves with good history - if (!H.ok_to_prune(pos.piece_on(mfrom), mto, d)) - return false; - - // Case 5: If the moving piece in the threatened move is a slider, don't + // Case 4: If the moving piece in the threatened move is a slider, don't // prune safe moves which block its ray. if ( !PruneBlockingMoves && threat != MOVE_NONE @@ -2509,8 +2515,8 @@ namespace { Value v = value_from_tt(tte->value(), ply); return ( tte->depth() >= depth - || v >= Max(value_mate_in(100), beta) - || v < Min(value_mated_in(100), beta)) + || v >= Max(value_mate_in(PLY_MAX), beta) + || v < Min(value_mated_in(PLY_MAX), beta)) && ( (is_lower_bound(tte->type()) && v >= beta) || (is_upper_bound(tte->type()) && v < beta)); @@ -2529,7 +2535,7 @@ namespace { { assert(m != movesSearched[i]); if (!pos.move_is_capture_or_promotion(movesSearched[i])) - H.failure(pos.piece_on(move_from(movesSearched[i])), move_to(movesSearched[i])); + H.failure(pos.piece_on(move_from(movesSearched[i])), move_to(movesSearched[i]), depth); } }