X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=17a221110462c6173f4d83602881a7031e9b8ab9;hp=a50b639ae49283dbec0b2f3e6fb2aa4eb768602d;hb=91b919fd1de3fc36df7bc2769f4d1e6196d7ce51;hpb=09d01ee9dc16f20962d5f5ffcb61ade56d4fa579 diff --git a/src/search.cpp b/src/search.cpp index a50b639a..17a22111 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -43,22 +43,17 @@ using std::endl; namespace { - // Different node types, used as template parameter - enum NodeType { NonPV, PV }; - - // Set to true to force running with one thread. Used for debugging. + // Set to true to force running with one thread. Used for debugging const bool FakeSplit = false; - // Lookup table to check if a Piece is a slider and its access function - const bool Slidings[18] = { 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1 }; - inline bool piece_is_slider(Piece p) { return Slidings[p]; } + // Different node types, used as template parameter + enum NodeType { Root, PV, NonPV, SplitPointPV, SplitPointNonPV }; // RootMove struct is used for moves at the root of the tree. For each root // move, we store two scores, a node count, and a PV (really a refutation // in the case of moves which fail low). Value pv_score is normally set at // -VALUE_INFINITE for all non-pv moves, while non_pv_score is computed // according to the order in which moves are returned by MovePicker. - struct RootMove { RootMove(); @@ -85,10 +80,8 @@ namespace { Move pv[PLY_MAX_PLUS_2]; }; - // RootMoveList struct is just a vector of RootMove objects, // with an handful of methods above the standard ones. - struct RootMoveList : public std::vector { typedef std::vector Base; @@ -100,32 +93,49 @@ namespace { int bestMoveChanges; }; + // MovePickerExt template class extends MovePicker and allows to choose at compile + // time the proper moves source according to the type of node. In the default case + // we simply create and use a standard MovePicker object. + template struct MovePickerExt : public MovePicker { - // Overload operator<<() to make it easier to print moves in a coordinate - // notation compatible with UCI protocol. - std::ostream& operator<<(std::ostream& os, Move m) { + MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) + : MovePicker(p, ttm, d, h, ss, b) {} - bool chess960 = (os.iword(0) != 0); // See set960() - return os << move_to_uci(m, chess960); - } + RootMoveList::iterator rm; // Dummy, needed to compile + }; + // In case of a SpNode we use split point's shared MovePicker object as moves source + template<> struct MovePickerExt : public MovePickerExt { - // When formatting a move for std::cout we must know if we are in Chess960 - // or not. To keep using the handy operator<<() on the move the trick is to - // embed this flag in the stream itself. Function-like named enum set960 is - // used as a custom manipulator and the stream internal general-purpose array, - // accessed through ios_base::iword(), is used to pass the flag to the move's - // operator<<() that will read it to properly format castling moves. - enum set960 {}; + MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) + : MovePickerExt(p, ttm, d, h, ss, b), mp(ss->sp->mp) {} - std::ostream& operator<< (std::ostream& os, const set960& f) { + Move get_next_move() { return mp->get_next_move(); } + MovePicker* mp; + }; - os.iword(0) = int(f); - return os; - } + template<> struct MovePickerExt : public MovePickerExt { + MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) + : MovePickerExt(p, ttm, d, h, ss, b) {} + }; - /// Adjustments + // In case of a Root node we use RootMoveList as moves source + template<> struct MovePickerExt : public MovePicker { + + MovePickerExt(const Position&, Move, Depth, const History&, SearchStack*, Value); + Move get_next_move(); + + RootMoveList::iterator rm; + bool firstCall; + }; + + + /// Constants + + // Lookup table to check if a Piece is a slider and its access function + const bool Slidings[18] = { 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1 }; + inline bool piece_is_slider(Piece p) { return Slidings[p]; } // Step 6. Razoring @@ -183,9 +193,9 @@ namespace { // Reduction lookup tables (initialized at startup) and their access function int8_t Reductions[2][64][64]; // [pv][depth][moveNumber] - template inline Depth reduction(Depth d, int mn) { + template inline Depth reduction(Depth d, int mn) { - return (Depth) Reductions[PV][Min(d / ONE_PLY, 63)][Min(mn, 63)]; + return (Depth) Reductions[PvNode][Min(d / ONE_PLY, 63)][Min(mn, 63)]; } // Easy move margin. An easy move candidate must be at least this much @@ -195,9 +205,6 @@ namespace { /// Namespace variables - // Book - Book OpeningBook; - // Root move list RootMoveList Rml; @@ -215,7 +222,6 @@ namespace { // Skill level adjustment int SkillLevel; bool SkillLevelEnabled; - RKISS RK; // Node counters, used only by thread[0] but try to keep in different cache // lines (64 bytes each) from the heavy multi-thread read accessed variables. @@ -231,20 +237,13 @@ namespace { Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove); - template + template Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth); - template + template Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth); - template - inline Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) { - - return depth < ONE_PLY ? qsearch(pos, ss, alpha, beta, DEPTH_ZERO) - : search(pos, ss, alpha, beta, depth); - } - - template + template Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool* dangerous); bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bValue); @@ -264,70 +263,27 @@ namespace { void poll(const Position& pos); void wait_for_stop_or_ponderhit(); + // Overload operator<<() to make it easier to print moves in a coordinate + // notation compatible with UCI protocol. + std::ostream& operator<<(std::ostream& os, Move m) { - // MovePickerExt is an extended MovePicker class used to choose at compile time - // the proper move source according to the type of node. - template struct MovePickerExt; - - // In Root nodes use RootMoveList as source. Score and sort the root moves - // before to search them. - template<> struct MovePickerExt : public MovePicker { - - 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; - - // Score root moves using standard ordering used in main search, the moves - // are scored according to the order in which they are returned by MovePicker. - // This is the second order score that is used to compare the moves when - // the first orders pv_score of both moves are equal. - while ((move = MovePicker::get_next_move()) != MOVE_NONE) - for (rm = Rml.begin(); rm != Rml.end(); ++rm) - if (rm->pv[0] == move) - { - rm->non_pv_score = score--; - break; - } - - Rml.sort(); - rm = Rml.begin(); - } - - Move get_next_move() { - - if (!firstCall) - ++rm; - else - firstCall = false; - - return rm != Rml.end() ? rm->pv[0] : MOVE_NONE; - } - - RootMoveList::iterator rm; - bool firstCall; - }; - - // In SpNodes use split point's shared MovePicker object as move source - template<> struct MovePickerExt : public MovePicker { - - MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) - : MovePicker(p, ttm, d, h, ss, b), mp(ss->sp->mp) {} - - Move get_next_move() { return mp->get_next_move(); } - - RootMoveList::iterator rm; // Dummy, needed to compile - MovePicker* mp; - }; + bool chess960 = (os.iword(0) != 0); // See set960() + return os << move_to_uci(m, chess960); + } - // Default case, create and use a MovePicker object as source - template<> struct MovePickerExt : public MovePicker { + // When formatting a move for std::cout we must know if we are in Chess960 + // or not. To keep using the handy operator<<() on the move the trick is to + // embed this flag in the stream itself. Function-like named enum set960 is + // used as a custom manipulator and the stream internal general-purpose array, + // accessed through ios_base::iword(), is used to pass the flag to the move's + // operator<<() that will read it to properly format castling moves. + enum set960 {}; - MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) - : MovePicker(p, ttm, d, h, ss, b) {} + std::ostream& operator<< (std::ostream& os, const set960& f) { - RootMoveList::iterator rm; // Dummy, needed to compile - }; + os.iword(0) = int(f); + return os; + } } // namespace @@ -345,8 +301,8 @@ void init_search() { { double pvRed = log(double(hd)) * log(double(mc)) / 3.0; double nonPVRed = 0.33 + log(double(hd)) * log(double(mc)) / 2.25; - Reductions[PV][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(ONE_PLY)) : 0); - Reductions[NonPV][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(ONE_PLY)) : 0); + Reductions[1][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(ONE_PLY)) : 0); + Reductions[0][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(ONE_PLY)) : 0); } // Init futility margins array @@ -359,8 +315,8 @@ void init_search() { } -/// perft() is our utility to verify move generation. All the legal moves up to -/// given depth are generated and counted and the sum returned. +/// perft() is our utility to verify move generation. All the leaf nodes up to +/// the given depth are generated and counted and the sum returned. int64_t perft(Position& pos, Depth depth) { @@ -382,7 +338,7 @@ int64_t perft(Position& pos, Depth depth) { for (MoveStack* cur = mlist; cur != last; cur++) { m = cur->move; - pos.do_move(m, st, ci, pos.move_is_check(m, ci)); + pos.do_move(m, st, ci, pos.move_gives_check(m, ci)); sum += perft(pos, depth - ONE_PLY); pos.undo_move(m); } @@ -397,6 +353,8 @@ int64_t perft(Position& pos, Depth depth) { bool think(Position& pos, const SearchLimits& limits, Move searchMoves[]) { + static Book book; + // Initialize global search-related variables StopOnPonderhit = StopRequest = QuitRequest = AspirationFailLow = SendSearchedNodes = false; NodesSincePoll = 0; @@ -417,10 +375,10 @@ bool think(Position& pos, const SearchLimits& limits, Move searchMoves[]) { // Look for a book move if (Options["OwnBook"].value()) { - if (Options["Book File"].value() != OpeningBook.name()) - OpeningBook.open(Options["Book File"].value()); + if (Options["Book File"].value() != book.name()) + book.open(Options["Book File"].value()); - Move bookMove = OpeningBook.get_move(pos, Options["Best Book Move"].value()); + Move bookMove = book.get_move(pos, Options["Best Book Move"].value()); if (bookMove != MOVE_NONE) { if (Limits.ponder) @@ -433,7 +391,7 @@ bool think(Position& pos, const SearchLimits& limits, Move searchMoves[]) { // Read UCI options UCIMultiPV = Options["MultiPV"].value(); - SkillLevel = Options["Skill level"].value(); + SkillLevel = Options["Skill Level"].value(); read_evaluation_uci_options(pos.side_to_move()); Threads.read_uci_options(); @@ -551,7 +509,7 @@ namespace { if (Rml.size() == 0) { cout << "info depth 0 score " - << value_to_uci(pos.is_check() ? -VALUE_MATE : VALUE_DRAW) + << value_to_uci(pos.in_check() ? -VALUE_MATE : VALUE_DRAW) << endl; return MOVE_NONE; @@ -580,7 +538,7 @@ namespace { // research with bigger window until not failing high/low anymore. do { // Search starting from ss+1 to allow calling update_gains() - value = search(pos, ss+1, alpha, beta, depth * ONE_PLY); + value = search(pos, ss+1, alpha, beta, depth * ONE_PLY); // Write PV back to transposition table in case the relevant entries // have been overwritten during the search. @@ -702,9 +660,13 @@ namespace { // all this work again. We also don't need to store anything to the hash table // here: This is taken care of after we return from the split point. - template + template Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) { + const bool PvNode = (NT == PV || NT == Root || NT == SplitPointPV); + const bool SpNode = (NT == SplitPointPV || NT == SplitPointNonPV); + const bool RootNode = (NT == Root); + assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta > alpha && beta <= VALUE_INFINITE); assert(PvNode || alpha == beta - 1); @@ -715,24 +677,25 @@ namespace { StateInfo st; const TTEntry *tte; Key posKey; + Bitboard pinned; Move ttMove, move, excludedMove, threatMove; Depth ext, newDepth; ValueType vt; Value bestValue, value, oldAlpha; Value refinedValue, nullValue, futilityBase, futilityValueScaled; // Non-PV specific - bool isPvMove, isCheck, singularExtensionNode, moveIsCheck, captureOrPromotion, dangerous, isBadCap; + bool isPvMove, inCheck, singularExtensionNode, givesCheck, captureOrPromotion, dangerous; int moveCount = 0, playedMoveCount = 0; - int threadID = pos.thread(); + Thread& thread = Threads[pos.thread()]; SplitPoint* sp = NULL; refinedValue = bestValue = value = -VALUE_INFINITE; oldAlpha = alpha; - isCheck = pos.is_check(); + inCheck = pos.in_check(); ss->ply = (ss-1)->ply + 1; // Used to send selDepth info to GUI - if (PvNode && Threads[threadID].maxPly < ss->ply) - Threads[threadID].maxPly = ss->ply; + if (PvNode && thread.maxPly < ss->ply) + thread.maxPly = ss->ply; if (SpNode) { @@ -742,15 +705,15 @@ namespace { threatMove = sp->threatMove; goto split_point_start; } - else if (Root) + else if (RootNode) bestValue = alpha; // Step 1. Initialize node and poll. Polling can abort search ss->currentMove = ss->bestMove = threatMove = (ss+1)->excludedMove = MOVE_NONE; (ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO; - (ss+2)->killers[0] = (ss+2)->killers[1] = (ss+2)->mateKiller = MOVE_NONE; + (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE; - if (threadID == 0 && ++NodesSincePoll > NodesBetweenPolls) + if (pos.thread() == 0 && ++NodesSincePoll > NodesBetweenPolls) { NodesSincePoll = 0; poll(pos); @@ -758,9 +721,8 @@ namespace { // Step 2. Check for aborted search and immediate draw if (( StopRequest - || Threads[threadID].cutoff_occurred() || pos.is_draw() - || ss->ply > PLY_MAX) && !Root) + || ss->ply > PLY_MAX) && !RootNode) return VALUE_DRAW; // Step 3. Mate distance pruning @@ -775,16 +737,14 @@ namespace { excludedMove = ss->excludedMove; posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key(); - tte = TT.retrieve(posKey); + tte = TT.probe(posKey); ttMove = tte ? tte->move() : MOVE_NONE; // At PV nodes we check for exact scores, while at non-PV nodes we check for // a fail high/low. Biggest advantage at probing at PV nodes is to have a // smooth experience in analysis mode. - if ( !Root - && tte - && (PvNode ? tte->depth() >= depth && tte->type() == VALUE_TYPE_EXACT - : ok_to_use_TT(tte, depth, beta, ss->ply))) + if (tte && (PvNode ? tte->depth() >= depth && tte->type() == VALUE_TYPE_EXACT + : ok_to_use_TT(tte, depth, beta, ss->ply))) { TT.refresh(tte); ss->bestMove = ttMove; // Can be MOVE_NONE @@ -792,7 +752,7 @@ namespace { } // Step 5. Evaluate the position statically and update parent's gain statistics - if (isCheck) + if (inCheck) ss->eval = ss->evalMargin = VALUE_NONE; else if (tte) { @@ -814,7 +774,7 @@ namespace { // Step 6. Razoring (is omitted in PV nodes) if ( !PvNode && depth < RazorDepth - && !isCheck + && !inCheck && refinedValue + razor_margin(depth) < beta && ttMove == MOVE_NONE && abs(beta) < VALUE_MATE_IN_PLY_MAX @@ -834,7 +794,7 @@ namespace { if ( !PvNode && !ss->skipNullMove && depth < RazorDepth - && !isCheck + && !inCheck && refinedValue - futility_margin(depth, 0) >= beta && abs(beta) < VALUE_MATE_IN_PLY_MAX && pos.non_pawn_material(pos.side_to_move())) @@ -844,7 +804,7 @@ namespace { if ( !PvNode && !ss->skipNullMove && depth > ONE_PLY - && !isCheck + && !inCheck && refinedValue >= beta && abs(beta) < VALUE_MATE_IN_PLY_MAX && pos.non_pawn_material(pos.side_to_move())) @@ -860,7 +820,8 @@ namespace { pos.do_null_move(st); (ss+1)->skipNullMove = true; - nullValue = -search(pos, ss+1, -beta, -alpha, depth-R*ONE_PLY); + nullValue = depth-R*ONE_PLY < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -beta, -alpha, depth-R*ONE_PLY); (ss+1)->skipNullMove = false; pos.undo_null_move(); @@ -899,33 +860,63 @@ namespace { } } - // Step 9. Internal iterative deepening + // Step 9. ProbCut (is omitted in PV nodes) + // If we have a very good capture (i.e. SEE > seeValues[captured_piece_type]) + // and a reduced search returns a value much above beta, we can (almost) safely + // prune the previous move. + if ( !PvNode + && depth >= RazorDepth + ONE_PLY + && !inCheck + && !ss->skipNullMove + && excludedMove == MOVE_NONE + && abs(beta) < VALUE_MATE_IN_PLY_MAX) + { + Value rbeta = beta + 200; + Depth rdepth = depth - ONE_PLY - 3 * ONE_PLY; + + assert(rdepth >= ONE_PLY); + + MovePicker mp(pos, ttMove, H, Position::see_value(pos.captured_piece_type())); + pinned = pos.pinned_pieces(pos.side_to_move()); + + while ((move = mp.get_next_move()) != MOVE_NONE) + if (pos.pl_move_is_legal(move, pinned)) + { + pos.do_move(move, st); + value = -search(pos, ss+1, -rbeta, -rbeta+1, rdepth); + pos.undo_move(move); + if (value >= rbeta) + return value; + } + } + + // Step 10. Internal iterative deepening if ( depth >= IIDDepth[PvNode] && ttMove == MOVE_NONE - && (PvNode || (!isCheck && ss->eval + IIDMargin >= beta))) + && (PvNode || (!inCheck && ss->eval + IIDMargin >= beta))) { Depth d = (PvNode ? depth - 2 * ONE_PLY : depth / 2); ss->skipNullMove = true; - search(pos, ss, alpha, beta, d); + search(pos, ss, alpha, beta, d); ss->skipNullMove = false; - ttMove = ss->bestMove; - tte = TT.retrieve(posKey); + tte = TT.probe(posKey); + ttMove = tte ? tte->move() : MOVE_NONE; } split_point_start: // At split points actual search starts from here // Initialize a MovePicker object for the current position - MovePickerExt mp(pos, ttMove, depth, H, ss, (PvNode ? -VALUE_INFINITE : beta)); + MovePickerExt mp(pos, ttMove, depth, H, ss, PvNode ? -VALUE_INFINITE : beta); CheckInfo ci(pos); + pinned = pos.pinned_pieces(pos.side_to_move()); ss->bestMove = MOVE_NONE; futilityBase = ss->eval + ss->evalMargin; - singularExtensionNode = !Root + singularExtensionNode = !RootNode && !SpNode && depth >= SingularExtensionDepth[PvNode] - && tte - && tte->move() + && ttMove != MOVE_NONE && !excludedMove // Do not allow recursive singular extension search && (tte->type() & VALUE_TYPE_LOWER) && tte->depth() >= depth - 3 * ONE_PLY; @@ -935,25 +926,30 @@ split_point_start: // At split points actual search starts from here bestValue = sp->bestValue; } - // Step 10. Loop through moves - // Loop through all legal moves until no moves remain or a beta cutoff occurs + // Step 11. Loop through moves + // Loop through all pseudo-legal moves until no moves remain or a beta cutoff occurs while ( bestValue < beta && (move = mp.get_next_move()) != MOVE_NONE - && !Threads[threadID].cutoff_occurred()) + && !thread.cutoff_occurred()) { assert(move_is_ok(move)); + if (move == excludedMove) + continue; + + // At PV and SpNode nodes we want the moves to be legal + if ((PvNode || SpNode) && !pos.pl_move_is_legal(move, pinned)) + continue; + if (SpNode) { moveCount = ++sp->moveCount; lock_release(&(sp->lock)); } - else if (move == excludedMove) - continue; else moveCount++; - if (Root) + if (RootNode) { // This is used by time management FirstRootMove = (moveCount == 1); @@ -975,12 +971,12 @@ split_point_start: // At split points actual search starts from here } // At Root and at first iteration do a PV search on all the moves to score root moves - isPvMove = (PvNode && moveCount <= (Root ? depth <= ONE_PLY ? 1000 : MultiPV : 1)); - moveIsCheck = pos.move_is_check(move, ci); - captureOrPromotion = pos.move_is_capture_or_promotion(move); + isPvMove = (PvNode && moveCount <= (RootNode ? depth <= ONE_PLY ? 1000 : MultiPV : 1)); + givesCheck = pos.move_gives_check(move, ci); + captureOrPromotion = pos.move_is_capture(move) || move_is_promotion(move); - // Step 11. Decide the new search depth - ext = extension(pos, move, captureOrPromotion, moveIsCheck, &dangerous); + // Step 12. Decide the new search depth + ext = extension(pos, move, captureOrPromotion, givesCheck, &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 @@ -988,7 +984,8 @@ split_point_start: // At split points actual search starts from here // on all the other moves but the ttMove, if result is lower than ttValue minus // a margin then we extend ttMove. if ( singularExtensionNode - && move == tte->move() + && move == ttMove + && pos.pl_move_is_legal(move, pinned) && ext < ONE_PLY) { Value ttValue = value_from_tt(tte->value(), ss->ply); @@ -1008,13 +1005,12 @@ split_point_start: // At split points actual search starts from here } // Update current move (this must be done after singular extension search) - ss->currentMove = move; newDepth = depth - ONE_PLY + ext; - // Step 12. Futility pruning (is omitted in PV nodes) + // Step 13. Futility pruning (is omitted in PV nodes) if ( !PvNode && !captureOrPromotion - && !isCheck + && !inCheck && !dangerous && move != ttMove && !move_is_castle(move)) @@ -1033,7 +1029,7 @@ split_point_start: // At split points actual search starts from here // Value based pruning // We illogically ignore reduction condition depth >= 3*ONE_PLY for predicted depth, // but fixing this made program slightly weaker. - Depth predictedDepth = newDepth - reduction(depth, moveCount); + Depth predictedDepth = newDepth - reduction(depth, moveCount); futilityValueScaled = futilityBase + futility_margin(predictedDepth, moveCount) + H.gain(pos.piece_on(move_from(move)), move_to(move)); @@ -1063,18 +1059,17 @@ split_point_start: // At split points actual search starts from here } } - // Bad capture detection. Will be used by prob-cut search - isBadCap = depth >= 3 * ONE_PLY - && depth < 8 * ONE_PLY - && captureOrPromotion - && move != ttMove - && !dangerous - && !move_is_promotion(move) - && abs(alpha) < VALUE_MATE_IN_PLY_MAX - && pos.see_sign(move) < 0; + // Check for legality only before to do the move + if (!pos.pl_move_is_legal(move, pinned)) + { + moveCount--; + continue; + } + + ss->currentMove = move; - // Step 13. Make the move - pos.do_move(move, st, ci, moveIsCheck); + // Step 14. Make the move + pos.do_move(move, st, ci, givesCheck); if (!SpNode && !captureOrPromotion) movesSearched[playedMoveCount++] = move; @@ -1084,14 +1079,15 @@ split_point_start: // At split points actual search starts from here if (isPvMove) { // Aspiration window is disabled in multi-pv case - if (Root && MultiPV > 1) + if (RootNode && MultiPV > 1) alpha = -VALUE_INFINITE; - value = -search(pos, ss+1, -beta, -alpha, newDepth); + value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -beta, -alpha, newDepth); } else { - // Step 14. Reduced depth search + // Step 15. Reduced depth search // If the move fails high will be re-searched at full depth. bool doFullDepthSearch = true; alpha = SpNode ? sp->alpha : alpha; @@ -1106,47 +1102,36 @@ split_point_start: // At split points actual search starts from here ss->reduction = reduction(depth, moveCount); if (ss->reduction) { - alpha = SpNode ? sp->alpha : alpha; Depth d = newDepth - ss->reduction; - value = -search(pos, ss+1, -(alpha+1), -alpha, d); - + value = d < ONE_PLY ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -(alpha+1), -alpha, d); doFullDepthSearch = (value > alpha); } ss->reduction = DEPTH_ZERO; // Restore original reduction } - // Probcut search for bad captures. If a reduced search returns a value - // very below beta then we can (almost) safely prune the bad capture. - if (isBadCap) - { - ss->reduction = 3 * ONE_PLY; - Value rAlpha = alpha - 300; - Depth d = newDepth - ss->reduction; - value = -search(pos, ss+1, -(rAlpha+1), -rAlpha, d); - doFullDepthSearch = (value > rAlpha); - ss->reduction = DEPTH_ZERO; // Restore original reduction - } - - // Step 15. Full depth search + // Step 16. Full depth search if (doFullDepthSearch) { alpha = SpNode ? sp->alpha : alpha; - value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth); + value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -(alpha+1), -alpha, newDepth); // Step extra. pv search (only in PV nodes) // Search only for possible new PV nodes, if instead value >= beta then // parent node fails low with value <= alpha and tries another move. - if (PvNode && value > alpha && (Root || value < beta)) - value = -search(pos, ss+1, -beta, -alpha, newDepth); + if (PvNode && value > alpha && (RootNode || value < beta)) + value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -beta, -alpha, newDepth); } } - // Step 16. Undo move + // Step 17. Undo move pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - // Step 17. Check for new best move + // Step 18. Check for new best move if (SpNode) { lock_grab(&(sp->lock)); @@ -1154,14 +1139,14 @@ split_point_start: // At split points actual search starts from here alpha = sp->alpha; } - if (value > bestValue && !(SpNode && Threads[threadID].cutoff_occurred())) + if (value > bestValue && !(SpNode && thread.cutoff_occurred())) { bestValue = value; if (SpNode) sp->bestValue = value; - if (!Root && value > alpha) + if (!RootNode && value > alpha) { if (PvNode && value < beta) // We want always alpha < beta { @@ -1173,9 +1158,6 @@ split_point_start: // At split points actual search starts from here else if (SpNode) sp->is_betaCutoff = true; - if (value == value_mate_in(ss->ply + 1)) - ss->mateKiller = move; - ss->bestMove = move; if (SpNode) @@ -1183,7 +1165,7 @@ split_point_start: // At split points actual search starts from here } } - if (Root) + if (RootNode) { // Finished searching the move. If StopRequest is true, the search // was aborted because the user interrupted the search or because we @@ -1222,31 +1204,31 @@ split_point_start: // At split points actual search starts from here else mp.rm->pv_score = -VALUE_INFINITE; - } // Root + } // RootNode - // Step 18. Check for split - if ( !Root + // Step 19. Check for split + if ( !RootNode && !SpNode && depth >= Threads.min_split_depth() && bestValue < beta - && Threads.available_slave_exists(threadID) + && Threads.available_slave_exists(pos.thread()) && !StopRequest - && !Threads[threadID].cutoff_occurred()) + && !thread.cutoff_occurred()) Threads.split(pos, ss, &alpha, beta, &bestValue, depth, threatMove, moveCount, &mp, PvNode); } - // Step 19. Check for mate and stalemate + // Step 20. Check for mate and stalemate // All legal moves have been searched and if there are // no legal moves, it must be mate or stalemate. // If one move was excluded return fail low score. if (!SpNode && !moveCount) - return excludedMove ? oldAlpha : isCheck ? value_mated_in(ss->ply) : VALUE_DRAW; + return excludedMove ? oldAlpha : inCheck ? value_mated_in(ss->ply) : VALUE_DRAW; - // Step 20. Update tables + // Step 21. Update tables // If the search is not aborted, update the transposition table, // history counters, and killer moves. - if (!SpNode && !StopRequest && !Threads[threadID].cutoff_occurred()) + if (!SpNode && !StopRequest && !thread.cutoff_occurred()) { move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove; vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER @@ -1256,7 +1238,8 @@ split_point_start: // At split points actual search starts from here // Update killers and history only for non capture moves that fails high if ( bestValue >= beta - && !pos.move_is_capture_or_promotion(move)) + && !pos.move_is_capture(move) + && !move_is_promotion(move)) { if (move != ss->killers[0]) { @@ -1270,7 +1253,7 @@ split_point_start: // At split points actual search starts from here if (SpNode) { // Here we have the lock still grabbed - sp->is_slave[threadID] = false; + sp->is_slave[pos.thread()] = false; sp->nodes += pos.nodes_searched(); lock_release(&(sp->lock)); } @@ -1284,9 +1267,12 @@ split_point_start: // At split points actual search starts from here // search function when the remaining depth is zero (or, to be more precise, // less than ONE_PLY). - template + template Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) { + const bool PvNode = (NT == PV); + + assert(NT == PV || NT == NonPV); assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); assert(PvNode || alpha == beta - 1); @@ -1296,7 +1282,7 @@ split_point_start: // At split points actual search starts from here StateInfo st; Move ttMove, move; Value bestValue, value, evalMargin, futilityValue, futilityBase; - bool isCheck, enoughMaterial, moveIsCheck, evasionPrunable; + bool inCheck, enoughMaterial, givesCheck, evasionPrunable; const TTEntry* tte; Depth ttDepth; Value oldAlpha = alpha; @@ -1311,12 +1297,12 @@ split_point_start: // At split points actual search starts from here // Decide whether or not to include checks, this fixes also the type of // TT entry depth that we are going to use. Note that in qsearch we use // only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS. - isCheck = pos.is_check(); - ttDepth = (isCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS); + inCheck = pos.in_check(); + ttDepth = (inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS); // Transposition table lookup. At PV nodes, we don't use the TT for // pruning, but only for move ordering. - tte = TT.retrieve(pos.get_key()); + tte = TT.probe(pos.get_key()); ttMove = (tte ? tte->move() : MOVE_NONE); if (!PvNode && tte && ok_to_use_TT(tte, ttDepth, beta, ss->ply)) @@ -1326,7 +1312,7 @@ split_point_start: // At split points actual search starts from here } // Evaluate the position statically - if (isCheck) + if (inCheck) { bestValue = futilityBase = -VALUE_INFINITE; ss->eval = evalMargin = VALUE_NONE; @@ -1369,6 +1355,7 @@ split_point_start: // At split points actual search starts from here // be generated. MovePicker mp(pos, ttMove, depth, H); CheckInfo ci(pos); + Bitboard pinned = pos.pinned_pieces(pos.side_to_move()); // Loop through the moves until no moves remain or a beta cutoff occurs while ( alpha < beta @@ -1376,12 +1363,12 @@ split_point_start: // At split points actual search starts from here { assert(move_is_ok(move)); - moveIsCheck = pos.move_is_check(move, ci); + givesCheck = pos.move_gives_check(move, ci); // Futility pruning if ( !PvNode - && !isCheck - && !moveIsCheck + && !inCheck + && !givesCheck && move != ttMove && enoughMaterial && !move_is_promotion(move) @@ -1406,14 +1393,15 @@ split_point_start: // At split points actual search starts from here } // Detect non-capture evasions that are candidate to be pruned - evasionPrunable = isCheck + evasionPrunable = !PvNode + && inCheck && bestValue > VALUE_MATED_IN_PLY_MAX && !pos.move_is_capture(move) && !pos.can_castle(pos.side_to_move()); // Don't search moves with negative SEE values if ( !PvNode - && (!isCheck || evasionPrunable) + && (!inCheck || evasionPrunable) && move != ttMove && !move_is_promotion(move) && pos.see_sign(move) < 0) @@ -1421,10 +1409,11 @@ split_point_start: // At split points actual search starts from here // Don't search useless checks if ( !PvNode - && !isCheck - && moveIsCheck + && !inCheck + && givesCheck && move != ttMove - && !pos.move_is_capture_or_promotion(move) + && !pos.move_is_capture(move) + && !move_is_promotion(move) && ss->eval + PawnValueMidgame / 4 < beta && !check_is_dangerous(pos, move, futilityBase, beta, &bestValue)) { @@ -1434,12 +1423,16 @@ split_point_start: // At split points actual search starts from here continue; } + // Check for legality only before to do the move + if (!pos.pl_move_is_legal(move, pinned)) + continue; + // Update current move ss->currentMove = move; // Make and search the move - pos.do_move(move, st, ci, moveIsCheck); - value = -qsearch(pos, ss+1, -beta, -alpha, depth-ONE_PLY); + pos.do_move(move, st, ci, givesCheck); + value = -qsearch(pos, ss+1, -beta, -alpha, depth-ONE_PLY); pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); @@ -1458,7 +1451,7 @@ split_point_start: // At split points actual search starts from here // All legal moves have been searched. A special case: If we're in check // and no legal moves were found, it is checkmate. - if (isCheck && bestValue == -VALUE_INFINITE) + if (inCheck && bestValue == -VALUE_INFINITE) return value_mated_in(ss->ply); // Update transposition table @@ -1618,7 +1611,7 @@ split_point_start: // At split points actual search starts from here // any case are marked as 'dangerous'. Note that also if a move is not // 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 + template Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool* dangerous) { @@ -1666,8 +1659,8 @@ split_point_start: // At split points actual search starts from here assert(move_is_ok(m)); assert(threat && move_is_ok(threat)); - assert(!pos.move_is_check(m)); - assert(!pos.move_is_capture_or_promotion(m)); + assert(!pos.move_gives_check(m)); + assert(!pos.move_is_capture(m) && !move_is_promotion(m)); assert(!pos.move_is_passed_pawn_push(m)); Square mfrom, mto, tfrom, tto; @@ -1923,6 +1916,8 @@ split_point_start: // At split points actual search starts from here assert(MultiPV > 1); + static RKISS rk; + // Rml list is already sorted by pv_score in descending order int s; int max_s = -VALUE_INFINITE; @@ -1933,7 +1928,7 @@ split_point_start: // At split points actual search starts from here // PRNG sequence should be non deterministic for (int i = abs(get_system_time() % 50); i > 0; i--) - RK.rand(); + rk.rand(); // Choose best move. For each move's score we add two terms both dependent // on wk, one deterministic and bigger for weaker moves, and one random, @@ -1947,7 +1942,7 @@ split_point_start: // At split points actual search starts from here break; // This is our magical formula - s += ((max - s) * wk + var * (RK.rand() % wk)) / 128; + s += ((max - s) * wk + var * (rk.rand() % wk)) / 128; if (s > max_s) { @@ -2020,13 +2015,14 @@ split_point_start: // At split points actual search starts from here TTEntry* tte; int ply = 1; - assert(pv[0] != MOVE_NONE && pos.move_is_legal(pv[0])); + assert(pv[0] != MOVE_NONE && pos.move_is_pl(pv[0])); pos.do_move(pv[0], *st++); - while ( (tte = TT.retrieve(pos.get_key())) != NULL + while ( (tte = TT.probe(pos.get_key())) != NULL && tte->move() != MOVE_NONE - && pos.move_is_legal(tte->move()) + && pos.move_is_pl(tte->move()) + && pos.pl_move_is_legal(tte->move(), pos.pinned_pieces(pos.side_to_move())) && ply < PLY_MAX && (!pos.is_draw() || ply < 2)) { @@ -2050,16 +2046,16 @@ split_point_start: // At split points actual search starts from here Value v, m = VALUE_NONE; int ply = 0; - assert(pv[0] != MOVE_NONE && pos.move_is_legal(pv[0])); + assert(pv[0] != MOVE_NONE && pos.move_is_pl(pv[0])); do { k = pos.get_key(); - tte = TT.retrieve(k); + tte = TT.probe(k); // Don't overwrite existing correct entries if (!tte || tte->move() != pv[ply]) { - v = (pos.is_check() ? VALUE_NONE : evaluate(pos, m)); + v = (pos.in_check() ? VALUE_NONE : evaluate(pos, m)); TT.store(k, VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, pv[ply], v, m); } pos.do_move(pv[ply], *st++); @@ -2090,6 +2086,39 @@ split_point_start: // At split points actual search starts from here return s.str(); } + // Specializations for MovePickerExt in case of Root node + MovePickerExt::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; + + // Score root moves using standard ordering used in main search, the moves + // are scored according to the order in which they are returned by MovePicker. + // This is the second order score that is used to compare the moves when + // the first orders pv_score of both moves are equal. + while ((move = MovePicker::get_next_move()) != MOVE_NONE) + for (rm = Rml.begin(); rm != Rml.end(); ++rm) + if (rm->pv[0] == move) + { + rm->non_pv_score = score--; + break; + } + + Rml.sort(); + rm = Rml.begin(); + } + + Move MovePickerExt::get_next_move() { + + if (!firstCall) + ++rm; + else + firstCall = false; + + return rm != Rml.end() ? rm->pv[0] : MOVE_NONE; + } + } // namespace @@ -2164,9 +2193,9 @@ void ThreadsManager::idle_loop(int threadID, SplitPoint* sp) { (ss+1)->sp = tsp; if (tsp->pvNode) - search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); + search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); else - search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); + search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); assert(threads[threadID].state == Thread::SEARCHING);