X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=791cbc6fb580901a567296d23a0eeed08f892969;hp=a3238a33f37c965874b3998bc1e42b24af75d03a;hb=b366c7dc38145278a00c51a560a4f7b6e03a0b2a;hpb=a8f457d4250a527f6b391f22a2f61f73272201fa diff --git a/src/search.cpp b/src/search.cpp index a3238a33..791cbc6f 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -203,8 +203,8 @@ namespace { // Extensions. Configurable UCI options // Array index 0 is used at non-PV nodes, index 1 at PV nodes. - Depth CheckExtension[2], SingleEvasionExtension[2], PawnPushTo7thExtension[2]; - Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2]; + Depth CheckExtension[2], PawnPushTo7thExtension[2], PassedPawnExtension[2]; + Depth PawnEndgameExtension[2], MateThreatExtension[2]; // Minimum depth for use of singular extension const Depth SingularExtensionDepth[2] = { 8 * ONE_PLY /* non-PV */, 6 * ONE_PLY /* PV */}; @@ -233,11 +233,6 @@ namespace { template inline Depth reduction(Depth d, int mn) { return (Depth) ReductionMatrix[PV][Min(d / 2, 63)][Min(mn, 63)]; } - // Common adjustments - - // Search depth at iteration 1 - const Depth InitialDepth = ONE_PLY; - // Easy move margin. An easy move candidate must be at least this much // better than the second best move. const Value EasyMoveMargin = Value(0x200); @@ -294,7 +289,7 @@ namespace { } template - Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool singleEvasion, bool mateThreat, bool* dangerous); + Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool mateThreat, bool* dangerous); bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bValue); bool connected_moves(const Position& pos, Move m1, Move m2); @@ -302,11 +297,13 @@ namespace { Value value_to_tt(Value v, int ply); Value value_from_tt(Value v, int ply); bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply); + bool ok_to_use_TT_PV(const TTEntry* tte, Depth depth, Value alpha, Value beta, int ply); bool connected_threat(const Position& pos, Move m, Move threat); Value refine_eval(const TTEntry* tte, Value defaultEval, int ply); void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount); void update_killers(Move m, Move killers[]); void update_gains(const Position& pos, Move move, Value before, Value after); + void qsearch_scoring(Position& pos, MoveStack* mlist, MoveStack* last); int current_search_time(); std::string value_to_uci(Value v); @@ -329,8 +326,8 @@ namespace { // before to search them. template<> struct MovePickerExt : public MovePicker { - MovePickerExt(const Position& p, Move, Depth d, const History& h, SearchStack* ss, Value b) - : MovePicker(p, Rml[0].pv[0], d, h, ss, b), firstCall(true) { + MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) + : MovePicker(p, ttm, d, h, ss, b), firstCall(true) { Move move; Value score = VALUE_ZERO; @@ -359,7 +356,6 @@ namespace { return rm != Rml.end() ? rm->pv[0] : MOVE_NONE; } - int number_of_evasions() const { return (int)Rml.size(); } RootMoveList::iterator rm; bool firstCall; @@ -505,8 +501,6 @@ bool think(Position& pos, bool infinite, bool ponder, int time[], int increment[ CheckExtension[1] = Options["Check Extension (PV nodes)"].value(); CheckExtension[0] = Options["Check Extension (non-PV nodes)"].value(); - SingleEvasionExtension[1] = Options["Single Evasion Extension (PV nodes)"].value(); - SingleEvasionExtension[0] = Options["Single Evasion Extension (non-PV nodes)"].value(); PawnPushTo7thExtension[1] = Options["Pawn Push to 7th Extension (PV nodes)"].value(); PawnPushTo7thExtension[0] = Options["Pawn Push to 7th Extension (non-PV nodes)"].value(); PassedPawnExtension[1] = Options["Passed Pawn Extension (PV nodes)"].value(); @@ -656,7 +650,7 @@ namespace { cout << "info depth " << iteration << endl; Rml.bestMoveChanges = researchCountFL = researchCountFH = 0; - depth = (iteration - 2) * ONE_PLY + InitialDepth; + depth = (iteration - 1) * ONE_PLY; // Calculate dynamic aspiration window based on previous iterations if (MultiPV == 1 && iteration >= 6 && abs(bestValues[iteration - 1]) < VALUE_KNOWN_WIN) @@ -791,7 +785,7 @@ namespace { ValueType vt; Value bestValue, value, oldAlpha; Value refinedValue, nullValue, futilityBase, futilityValueScaled; // Non-PV specific - bool isPvMove, isCheck, singleEvasion, singularExtensionNode, moveIsCheck, captureOrPromotion, dangerous; + bool isPvMove, isCheck, singularExtensionNode, moveIsCheck, captureOrPromotion, dangerous; bool mateThreat = false; int moveCount = 0, playedMoveCount = 0; int threadID = pos.thread(); @@ -845,14 +839,10 @@ namespace { tte = TT.retrieve(posKey); ttMove = tte ? tte->move() : MOVE_NONE; - // At PV nodes, we don't use the TT for 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 - if (!PvNode && tte && ok_to_use_TT(tte, depth, beta, ply)) + // At PV nodes we check for exact scores within (alha, beta) range, while + // at non-PV nodes we check for and return a fail high/low. Biggest advantage + // at probing at PV nodes is to have a smooth experience in analysis mode. + if (!Root && tte && (PvNode ? ok_to_use_TT_PV(tte, depth, alpha, beta, ply) : ok_to_use_TT(tte, depth, beta, ply))) { TT.refresh(tte); ss->bestMove = ttMove; // Can be MOVE_NONE @@ -995,7 +985,6 @@ split_point_start: // At split points actual search starts from here MovePickerExt mp(pos, ttMove, depth, H, ss, (PvNode ? -VALUE_INFINITE : beta)); CheckInfo ci(pos); ss->bestMove = MOVE_NONE; - singleEvasion = !SpNode && isCheck && mp.number_of_evasions() == 1; futilityBase = ss->eval + ss->evalMargin; singularExtensionNode = !Root && !SpNode @@ -1057,7 +1046,7 @@ split_point_start: // At split points actual search starts from here captureOrPromotion = pos.move_is_capture_or_promotion(move); // Step 11. Decide the new search depth - ext = extension(pos, move, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous); + ext = extension(pos, move, captureOrPromotion, moveIsCheck, mateThreat, &dangerous); // Singular extension search. If all moves but one fail low on a search of (alpha-s, beta-s), // and just one fails high on (alpha, beta), then that move is singular and should be extended. @@ -1527,6 +1516,26 @@ split_point_start: // At split points actual search starts from here } + // qsearch_scoring() scores each move of a list using a qsearch() evaluation, + // it is used in RootMoveList to get an initial scoring. + void qsearch_scoring(Position& pos, MoveStack* mlist, MoveStack* last) { + + SearchStack ss[PLY_MAX_PLUS_2]; + StateInfo st; + + memset(ss, 0, 4 * sizeof(SearchStack)); + ss[0].eval = ss[0].evalMargin = VALUE_NONE; + + for (MoveStack* cur = mlist; cur != last; cur++) + { + ss[0].currentMove = cur->move; + pos.do_move(cur->move, st); + cur->score = -qsearch(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, DEPTH_ZERO, 1); + pos.undo_move(cur->move); + } + } + + // check_is_dangerous() tests if a checking move can be pruned in qsearch(). // bestValue is updated only when returning false because in that case move // will be pruned. @@ -1687,22 +1696,19 @@ split_point_start: // At split points actual search starts from here // extended, as example because the corresponding UCI option is set to zero, // the move is marked as 'dangerous' so, at least, we avoid to prune it. template - Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, - bool singleEvasion, bool mateThreat, bool* dangerous) { + Depth extension(const Position& pos, Move m, bool captureOrPromotion, + bool moveIsCheck, bool mateThreat, bool* dangerous) { assert(m != MOVE_NONE); Depth result = DEPTH_ZERO; - *dangerous = moveIsCheck | singleEvasion | mateThreat; + *dangerous = moveIsCheck | mateThreat; if (*dangerous) { if (moveIsCheck && pos.see_sign(m) >= 0) result += CheckExtension[PvNode]; - if (singleEvasion) - result += SingleEvasionExtension[PvNode]; - if (mateThreat) result += MateThreatExtension[PvNode]; } @@ -1788,7 +1794,9 @@ split_point_start: // At split points actual search starts from here // ok_to_use_TT() returns true if a transposition table score - // can be used at a given point in search. + // can be used at a given point in search. There are two versions + // one to be used in non-PV nodes and one in PV nodes where we look + // for an exact score that falls between (alha, beta) boundaries. bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply) { @@ -1802,6 +1810,17 @@ split_point_start: // At split points actual search starts from here || ((tte->type() & VALUE_TYPE_UPPER) && v < beta)); } + bool ok_to_use_TT_PV(const TTEntry* tte, Depth depth, Value alpha, Value beta, int ply) { + + Value v = value_from_tt(tte->value(), ply); + + return tte->depth() >= depth + && tte->type() == VALUE_TYPE_EXACT + && tte->move() != MOVE_NONE + && v < beta + && v > alpha; + } + // refine_eval() returns the transposition table score if // possible otherwise falls back on static position evaluation. @@ -2564,19 +2583,15 @@ split_point_start: // At split points actual search starts from here void RootMoveList::init(Position& pos, Move searchMoves[]) { - SearchStack ss[PLY_MAX_PLUS_2]; MoveStack mlist[MOVES_MAX]; - StateInfo st; Move* sm; - // Initialize search stack - memset(ss, 0, PLY_MAX_PLUS_2 * sizeof(SearchStack)); - ss[0].eval = ss[0].evalMargin = VALUE_NONE; - bestMoveChanges = 0; clear(); + bestMoveChanges = 0; - // Generate all legal moves + // Generate all legal moves and score them MoveStack* last = generate(pos, mlist); + qsearch_scoring(pos, mlist, last); // Add each move to the RootMoveList's vector for (MoveStack* cur = mlist; cur != last; cur++) @@ -2588,16 +2603,11 @@ split_point_start: // At split points actual search starts from here if (searchMoves[0] && *sm != cur->move) continue; - // Find a quick score for the move and add to the list - pos.do_move(cur->move, st); - RootMove rm; - rm.pv[0] = ss[0].currentMove = cur->move; + rm.pv[0] = cur->move; rm.pv[1] = MOVE_NONE; - rm.pv_score = -qsearch(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, DEPTH_ZERO, 1); + rm.pv_score = Value(cur->score); push_back(rm); - - pos.undo_move(cur->move); } sort(); }