X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=b9cbb956d823b9cb7bb30605bdd3524f46d608c2;hp=bf227d1fb9d2ac034797cfbdb62d380dd65dd034;hb=76caef8ba1fb4ca0520a8e2b42815d626484e93c;hpb=cd80762c13961eb8fe0a89c0bb19d58e2808a1cf diff --git a/src/search.cpp b/src/search.cpp index bf227d1f..b9cbb956 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -26,7 +26,6 @@ #include "book.h" #include "evaluate.h" -#include "history.h" #include "movegen.h" #include "movepick.h" #include "notation.h" @@ -62,10 +61,6 @@ namespace { // Different node types, used as template parameter enum NodeType { Root, PV, NonPV, SplitPointRoot, SplitPointPV, SplitPointNonPV }; - // 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]; } - // Dynamic razoring margin based on depth inline Value razor_margin(Depth d) { return Value(512 + 16 * int(d)); } @@ -91,20 +86,21 @@ namespace { TimeManager TimeMgr; int BestMoveChanges; Value DrawValue[COLOR_NB]; - History H; + History Hist; + Gains Gain; template Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth); - template + template Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth); void id_loop(Position& pos); - bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta); - bool connected_moves(const Position& pos, Move m1, Move m2); Value value_to_tt(Value v, int ply); Value value_from_tt(Value v, int ply); - bool connected_threat(const Position& pos, Move m, Move threat); + bool check_is_dangerous(const Position& pos, Move move, Value futilityBase, Value beta); + bool allows(const Position& pos, Move first, Move second); + bool refutes(const Position& pos, Move first, Move second); string uci_pv(const Position& pos, int depth, Value alpha, Value beta); struct Skill { @@ -186,19 +182,19 @@ void Search::think() { static PolyglotBook book; // Defined static to initialize the PRNG only once RootColor = RootPos.side_to_move(); - TimeMgr.init(Limits, RootPos.startpos_ply_counter(), RootColor); + TimeMgr.init(Limits, RootPos.game_ply(), RootColor); if (RootMoves.empty()) { RootMoves.push_back(MOVE_NONE); sync_cout << "info depth 0 score " - << score_to_uci(RootPos.in_check() ? -VALUE_MATE : VALUE_DRAW) + << score_to_uci(RootPos.checkers() ? -VALUE_MATE : VALUE_DRAW) << sync_endl; goto finalize; } - if (Options["OwnBook"] && !Limits.infinite) + if (Options["OwnBook"] && !Limits.infinite && !Limits.mate) { Move bookMove = book.probe(RootPos, Options["Book File"], Options["Best Book Move"]); @@ -212,7 +208,7 @@ void Search::think() { if (Options["Contempt Factor"] && !Options["UCI_AnalyseMode"]) { int cf = Options["Contempt Factor"] * PawnValueMg / 100; // From centipawns - cf = cf * MaterialTable::game_phase(RootPos) / PHASE_MIDGAME; // Scale down with phase + cf = cf * Material::game_phase(RootPos) / PHASE_MIDGAME; // Scale down with phase DrawValue[ RootColor] = VALUE_DRAW - Value(cf); DrawValue[~RootColor] = VALUE_DRAW + Value(cf); } @@ -222,7 +218,7 @@ void Search::think() { if (Options["Use Search Log"]) { Log log(Options["Search Log Filename"]); - log << "\nSearching: " << RootPos.to_fen() + log << "\nSearching: " << RootPos.fen() << "\ninfinite: " << Limits.infinite << " ponder: " << Limits.ponder << " time: " << Limits.time[RootColor] @@ -231,22 +227,25 @@ void Search::think() { << std::endl; } - Threads.wake_up(); + // Reset the threads, still sleeping: will be wake up at split time + for (size_t i = 0; i < Threads.size(); i++) + Threads[i]->maxPly = 0; + + Threads.sleepWhileIdle = Options["Use Sleeping Threads"]; // Set best timer interval to avoid lagging under time pressure. Timer is // used to check for remaining available thinking time. - if (Limits.use_time_management()) - Threads.set_timer(std::min(100, std::max(TimeMgr.available_time() / 16, - TimerResolution))); - else if (Limits.nodes) - Threads.set_timer(2 * TimerResolution); - else - Threads.set_timer(100); + Threads.timer->msec = + Limits.use_time_management() ? std::min(100, std::max(TimeMgr.available_time() / 16, TimerResolution)) : + Limits.nodes ? 2 * TimerResolution + : 100; + + Threads.timer->notify_one(); // Wake up the recurring timer id_loop(RootPos); // Let's start searching ! - Threads.set_timer(0); // Stop timer - Threads.sleep(); + Threads.timer->msec = 0; // Stop the timer + Threads.sleepWhileIdle = true; // Send idle threads to sleep if (Options["Use Search Log"]) { @@ -266,10 +265,15 @@ void Search::think() { finalize: // When we reach max depth we arrive here even without Signals.stop is raised, - // but if we are pondering or in infinite search, we shouldn't print the best - // move before we are told to do so. + // but if we are pondering or in infinite search, according to UCI protocol, + // we shouldn't print the best move before the GUI sends a "stop" or "ponderhit" + // command. We simply wait here until GUI sends one of those commands (that + // raise Signals.stop). if (!Signals.stop && (Limits.ponder || Limits.infinite)) - RootPos.this_thread()->wait_for_stop_or_ponderhit(); + { + Signals.stopOnPonderhit = true; + RootPos.this_thread()->wait_for(Signals.stop); + } // Best move could be MOVE_NONE when searching on a stalemate position sync_cout << "bestmove " << move_to_uci(RootMoves[0].pv[0], RootPos.is_chess960()) @@ -296,7 +300,8 @@ namespace { bestValue = delta = -VALUE_INFINITE; ss->currentMove = MOVE_NULL; // Hack to skip update gains TT.new_search(); - H.clear(); + Hist.clear(); + Gain.clear(); PVSize = Options["MultiPV"]; Skill skill(Options["Skill Level"]); @@ -349,7 +354,7 @@ namespace { // we want to keep the same order for all the moves but the new // PV that goes to the front. Note that in case of MultiPV search // the already searched PV lines are preserved. - sort(RootMoves.begin() + PVIdx, RootMoves.end()); + std::stable_sort(RootMoves.begin() + PVIdx, RootMoves.end()); // Write PV back to transposition table in case the relevant // entries have been overwritten during the search. @@ -394,8 +399,10 @@ namespace { } // Sort the PV lines searched so far and update the GUI - sort(RootMoves.begin(), RootMoves.begin() + PVIdx); - sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl; + std::stable_sort(RootMoves.begin(), RootMoves.begin() + PVIdx + 1); + + if (PVIdx + 1 == PVSize || Time::now() - SearchTime > 3000) + sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl; } // Do we need to pick now the sub-optimal best move ? @@ -413,6 +420,12 @@ namespace { if (depth > 2 && BestMoveChanges) bestMoveNeverChanged = false; + // Do we have found a "mate in x"? + if ( Limits.mate + && bestValue >= VALUE_MATE_IN_MAX_PLY + && VALUE_MATE - bestValue <= 2 * Limits.mate) + Signals.stop = true; + // Do we have time for the next iteration? Can we stop searching now? if (Limits.use_time_management() && !Signals.stopOnPonderhit) { @@ -494,7 +507,7 @@ namespace { // Step 1. Initialize node Thread* thisThread = pos.this_thread(); moveCount = playedMoveCount = 0; - inCheck = pos.in_check(); + inCheck = pos.checkers(); if (SpNode) { @@ -524,7 +537,7 @@ namespace { if (!RootNode) { // Step 2. Check for aborted search and immediate draw - if (Signals.stop || pos.is_draw() || ss->ply > MAX_PLY) + if (Signals.stop || pos.is_draw() || ss->ply > MAX_PLY) return DrawValue[pos.side_to_move()]; // Step 3. Mate distance pruning. Even if we mate at the next move our score @@ -580,15 +593,9 @@ namespace { else if (tte) { - // Following asserts are valid only in single thread condition because - // TT access is always racy and its contents cannot be trusted. - assert(tte->static_value() != VALUE_NONE || Threads.size() > 1); - assert(ttValue != VALUE_NONE || tte->type() == BOUND_NONE || Threads.size() > 1); - - ss->staticEval = eval = tte->static_value(); - ss->evalMargin = tte->static_value_margin(); - - if (eval == VALUE_NONE || ss->evalMargin == VALUE_NONE) // Due to a race + // Never assume anything on values stored in TT + if ( (ss->staticEval = eval = tte->eval_value()) == VALUE_NONE + ||(ss->evalMargin = tte->eval_margin()) == VALUE_NONE) eval = ss->staticEval = evaluate(pos, ss->evalMargin); // Can ttValue be used as a better position evaluation? @@ -613,7 +620,7 @@ namespace { && type_of(move) == NORMAL) { Square to = to_sq(move); - H.update_gain(pos.piece_on(to), to, -(ss-1)->staticEval - ss->staticEval); + Gain.update(pos.piece_on(to), to, -(ss-1)->staticEval - ss->staticEval); } // Step 6. Razoring (is omitted in PV nodes) @@ -626,7 +633,7 @@ namespace { && !pos.pawn_on_7th(pos.side_to_move())) { Value rbeta = beta - razor_margin(depth); - Value v = qsearch(pos, ss, rbeta-1, rbeta, DEPTH_ZERO); + Value v = qsearch(pos, ss, rbeta-1, rbeta, DEPTH_ZERO); if (v < rbeta) // Logically we should return (v + razor_margin(depth)), but // surprisingly this did slightly weaker in tests. @@ -663,12 +670,12 @@ namespace { if (eval - PawnValueMg > beta) R += ONE_PLY; - pos.do_null_move(st); + pos.do_null_move(st); (ss+1)->skipNullMove = true; - nullValue = depth-R < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + nullValue = depth-R < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) : - search(pos, ss+1, -beta, -alpha, depth-R); (ss+1)->skipNullMove = false; - pos.do_null_move(st); + pos.undo_null_move(); if (nullValue >= beta) { @@ -700,7 +707,7 @@ namespace { if ( depth < 5 * ONE_PLY && (ss-1)->reduction && threatMove != MOVE_NONE - && connected_moves(pos, (ss-1)->currentMove, threatMove)) + && allows(pos, (ss-1)->currentMove, threatMove)) return beta - 1; } } @@ -723,7 +730,7 @@ namespace { assert((ss-1)->currentMove != MOVE_NONE); assert((ss-1)->currentMove != MOVE_NULL); - MovePicker mp(pos, ttMove, H, pos.captured_piece_type()); + MovePicker mp(pos, ttMove, Hist, pos.captured_piece_type()); CheckInfo ci(pos); while ((move = mp.next_move()) != MOVE_NONE) @@ -755,7 +762,7 @@ namespace { split_point_start: // At split points actual search starts from here - MovePicker mp(pos, ttMove, depth, H, ss, PvNode ? -VALUE_INFINITE : beta); + MovePicker mp(pos, ttMove, depth, Hist, ss, PvNode ? -VALUE_INFINITE : beta); CheckInfo ci(pos); value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc singularExtensionNode = !RootNode @@ -797,7 +804,7 @@ split_point_start: // At split points actual search starts from here { Signals.firstRootMove = (moveCount == 1); - if (thisThread == Threads.main_thread() && Time::now() - SearchTime > 2000) + if (thisThread == Threads.main_thread() && Time::now() - SearchTime > 3000) sync_cout << "info depth " << depth / ONE_PLY << " currmove " << move_to_uci(move, pos.is_chess960()) << " currmovenumber " << moveCount + PVIdx << sync_endl; @@ -843,7 +850,7 @@ split_point_start: // At split points actual search starts from here ss->excludedMove = MOVE_NONE; if (value < rBeta) - ext = rBeta >= beta ? ONE_PLY + ONE_PLY / 2 : ONE_PLY; + ext = ONE_PLY; } // Update current move (this must be done after singular extension search) @@ -861,7 +868,7 @@ split_point_start: // At split points actual search starts from here // Move count based pruning if ( depth < 16 * ONE_PLY && moveCount >= FutilityMoveCounts[depth] - && (!threatMove || !connected_threat(pos, move, threatMove))) + && (!threatMove || !refutes(pos, move, threatMove))) { if (SpNode) sp->mutex.lock(); @@ -874,7 +881,7 @@ split_point_start: // At split points actual search starts from here // but fixing this made program slightly weaker. Depth predictedDepth = newDepth - reduction(depth, moveCount); futilityValue = ss->staticEval + ss->evalMargin + futility_margin(predictedDepth, moveCount) - + H.gain(pos.piece_moved(move), to_sq(move)); + + Gain[pos.piece_moved(move)][to_sq(move)]; if (futilityValue < beta) { @@ -896,13 +903,13 @@ split_point_start: // At split points actual search starts from here } // Check for legality only before to do the move - if (!pos.pl_move_is_legal(move, ci.pinned)) + if (!RootNode && !SpNode && !pos.pl_move_is_legal(move, ci.pinned)) { moveCount--; continue; } - pvMove = PvNode ? moveCount == 1 : false; + pvMove = PvNode && moveCount == 1; ss->currentMove = move; if (!SpNode && !captureOrPromotion && playedMoveCount < 64) movesSearched[playedMoveCount++] = move; @@ -916,8 +923,9 @@ split_point_start: // At split points actual search starts from here && !pvMove && !captureOrPromotion && !dangerous - && ss->killers[0] != move - && ss->killers[1] != move) + && move != ttMove + && move != ss->killers[0] + && move != ss->killers[1]) { ss->reduction = reduction(depth, moveCount); Depth d = std::max(newDepth - ss->reduction, ONE_PLY); @@ -935,7 +943,9 @@ split_point_start: // At split points actual search starts from here if (doFullDepthSearch) { alpha = SpNode ? sp->alpha : alpha; - value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) + value = newDepth < ONE_PLY ? + givesCheck ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) + : -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) : - search(pos, ss+1, -(alpha+1), -alpha, newDepth); } @@ -943,9 +953,10 @@ split_point_start: // At split points actual search starts from here // high, in the latter case search only if value < beta, otherwise let the // parent node to fail low with value <= alpha and to try another move. if (PvNode && (pvMove || (value > alpha && (RootNode || value < beta)))) - value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + value = newDepth < ONE_PLY ? + givesCheck ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + : -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) : - search(pos, ss+1, -beta, -alpha, newDepth); - // Step 17. Undo move pos.undo_move(move); @@ -991,22 +1002,21 @@ split_point_start: // At split points actual search starts from here if (value > bestValue) { - bestValue = value; - if (SpNode) sp->bestValue = value; + bestValue = SpNode ? sp->bestValue = value : value; if (value > alpha) { - bestMove = move; - if (SpNode) sp->bestMove = move; + bestMove = SpNode ? sp->bestMove = move : move; - if (PvNode && value < beta) - { - alpha = value; // Update alpha here! Always alpha < beta - if (SpNode) sp->alpha = value; - } - else // Fail high + if (PvNode && value < beta) // Update alpha! Always alpha < beta + alpha = SpNode ? sp->alpha = value : value; + else { - if (SpNode) sp->cutoff = true; + assert(value >= beta); // Fail high + + if (SpNode) + sp->cutoff = true; + break; } } @@ -1014,13 +1024,16 @@ split_point_start: // At split points actual search starts from here // Step 19. Check for splitting the search if ( !SpNode - && depth >= Threads.min_split_depth() - && bestValue < beta - && Threads.available_slave_exists(thisThread)) + && depth >= Threads.minimumSplitDepth + && Threads.available_slave(thisThread) + && thisThread->splitPointsSize < MAX_SPLITPOINTS_PER_THREAD) { - bestValue = Threads.split(pos, ss, alpha, beta, bestValue, &bestMove, - depth, threatMove, moveCount, mp, NT); - break; + assert(bestValue < beta); + + thisThread->split(pos, ss, alpha, beta, &bestValue, &bestMove, + depth, threatMove, moveCount, &mp, NT); + if (bestValue >= beta) + break; } } @@ -1061,13 +1074,13 @@ split_point_start: // At split points actual search starts from here // Increase history value of the cut-off move Value bonus = Value(int(depth) * int(depth)); - H.add(pos.piece_moved(bestMove), to_sq(bestMove), bonus); + Hist.update(pos.piece_moved(bestMove), to_sq(bestMove), bonus); // Decrease history of all the other played non-capture moves for (int i = 0; i < playedMoveCount - 1; i++) { Move m = movesSearched[i]; - H.add(pos.piece_moved(m), to_sq(m), -bonus); + Hist.update(pos.piece_moved(m), to_sq(m), -bonus); } } } @@ -1086,12 +1099,13 @@ 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, Stack* ss, Value alpha, Value beta, Depth depth) { const bool PvNode = (NT == PV); assert(NT == PV || NT == NonPV); + assert(InCheck == !!pos.checkers()); assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE); assert(PvNode || (alpha == beta - 1)); assert(depth <= DEPTH_ZERO); @@ -1100,16 +1114,19 @@ split_point_start: // At split points actual search starts from here const TTEntry* tte; Key posKey; Move ttMove, move, bestMove; - Value bestValue, value, ttValue, futilityValue, futilityBase; - bool inCheck, givesCheck, enoughMaterial, evasionPrunable; + Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha; + bool givesCheck, enoughMaterial, evasionPrunable; Depth ttDepth; - inCheck = pos.in_check(); + // To flag BOUND_EXACT a node with eval above alpha and no available moves + if (PvNode) + oldAlpha = alpha; + ss->currentMove = bestMove = MOVE_NONE; ss->ply = (ss-1)->ply + 1; // Check for an instant draw or maximum ply reached - if (pos.is_draw() || ss->ply > MAX_PLY) + if (pos.is_draw() || ss->ply > MAX_PLY) return DrawValue[pos.side_to_move()]; // Transposition table lookup. At PV nodes, we don't use the TT for @@ -1122,7 +1139,7 @@ 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. - ttDepth = inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS + ttDepth = InCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS; if ( tte && tte->depth() >= ttDepth @@ -1136,7 +1153,7 @@ split_point_start: // At split points actual search starts from here } // Evaluate the position statically - if (inCheck) + if (InCheck) { ss->staticEval = ss->evalMargin = VALUE_NONE; bestValue = futilityBase = -VALUE_INFINITE; @@ -1146,12 +1163,9 @@ split_point_start: // At split points actual search starts from here { if (tte) { - assert(tte->static_value() != VALUE_NONE || Threads.size() > 1); - - ss->staticEval = bestValue = tte->static_value(); - ss->evalMargin = tte->static_value_margin(); - - if (ss->staticEval == VALUE_NONE || ss->evalMargin == VALUE_NONE) // Due to a race + // Never assume anything on values stored in TT + if ( (ss->staticEval = bestValue = tte->eval_value()) == VALUE_NONE + ||(ss->evalMargin = tte->eval_margin()) == VALUE_NONE) ss->staticEval = bestValue = evaluate(pos, ss->evalMargin); } else @@ -1178,7 +1192,7 @@ split_point_start: // At split points actual search starts from here // to search the moves. Because the depth is <= 0 here, only captures, // queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will // be generated. - MovePicker mp(pos, ttMove, depth, H, to_sq((ss-1)->currentMove)); + MovePicker mp(pos, ttMove, depth, Hist, to_sq((ss-1)->currentMove)); CheckInfo ci(pos); // Loop through the moves until no moves remain or a beta cutoff occurs @@ -1190,7 +1204,7 @@ split_point_start: // At split points actual search starts from here // Futility pruning if ( !PvNode - && !inCheck + && !InCheck && !givesCheck && move != ttMove && enoughMaterial @@ -1203,9 +1217,7 @@ split_point_start: // At split points actual search starts from here if (futilityValue < beta) { - if (futilityValue > bestValue) - bestValue = futilityValue; - + bestValue = std::max(bestValue, futilityValue); continue; } @@ -1213,19 +1225,22 @@ split_point_start: // At split points actual search starts from here if ( futilityBase < beta && depth < DEPTH_ZERO && pos.see(move) <= 0) + { + bestValue = std::max(bestValue, futilityBase); continue; + } } // Detect non-capture evasions that are candidate to be pruned evasionPrunable = !PvNode - && inCheck + && InCheck && bestValue > VALUE_MATED_IN_MAX_PLY && !pos.is_capture(move) && !pos.can_castle(pos.side_to_move()); // Don't search moves with negative SEE values if ( !PvNode - && (!inCheck || evasionPrunable) + && (!InCheck || evasionPrunable) && move != ttMove && type_of(move) != PROMOTION && pos.see_sign(move) < 0) @@ -1233,7 +1248,7 @@ split_point_start: // At split points actual search starts from here // Don't search useless checks if ( !PvNode - && !inCheck + && !InCheck && givesCheck && move != ttMove && !pos.is_capture_or_promotion(move) @@ -1249,7 +1264,8 @@ split_point_start: // At split points actual search starts from here // Make and search the move pos.do_move(move, st, ci, givesCheck); - value = -qsearch(pos, ss+1, -beta, -alpha, depth - ONE_PLY); + value = givesCheck ? -qsearch(pos, ss+1, -beta, -alpha, depth - ONE_PLY) + : -qsearch(pos, ss+1, -beta, -alpha, depth - ONE_PLY); pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); @@ -1279,11 +1295,11 @@ 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 (inCheck && bestValue == -VALUE_INFINITE) + if (InCheck && bestValue == -VALUE_INFINITE) return mated_in(ss->ply); // Plies to mate from the root TT.store(posKey, value_to_tt(bestValue, ss->ply), - PvNode && bestMove != MOVE_NONE ? BOUND_EXACT : BOUND_UPPER, + PvNode && bestValue > oldAlpha ? BOUND_EXACT : BOUND_UPPER, ttDepth, bestMove, ss->staticEval, ss->evalMargin); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1292,40 +1308,56 @@ split_point_start: // At split points actual search starts from here } - // 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. + // value_to_tt() adjusts a mate score from "plies to mate from the root" to + // "plies to mate from the current position". Non-mate scores are unchanged. + // The function is called before storing a value to the transposition table. + + Value value_to_tt(Value v, int ply) { + + assert(v != VALUE_NONE); + + return v >= VALUE_MATE_IN_MAX_PLY ? v + ply + : v <= VALUE_MATED_IN_MAX_PLY ? v - ply : v; + } + + + // value_from_tt() is the inverse of value_to_tt(): It adjusts a mate score + // from the transposition table (where refers to the plies to mate/be mated + // from current position) to "plies to mate/be mated from the root". + + Value value_from_tt(Value v, int ply) { + + return v == VALUE_NONE ? VALUE_NONE + : v >= VALUE_MATE_IN_MAX_PLY ? v - ply + : v <= VALUE_MATED_IN_MAX_PLY ? v + ply : v; + } + + + // check_is_dangerous() tests if a checking move can be pruned in qsearch() - bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta) + bool check_is_dangerous(const Position& pos, Move move, Value futilityBase, Value beta) { - Bitboard b, occ, oldAtt, newAtt, kingAtt; - Square from, to, ksq; - Piece pc; - Color them; - - from = from_sq(move); - to = to_sq(move); - them = ~pos.side_to_move(); - ksq = pos.king_square(them); - kingAtt = pos.attacks_from(ksq); - pc = pos.piece_moved(move); - - occ = pos.pieces() ^ from ^ ksq; - oldAtt = pos.attacks_from(pc, from, occ); - newAtt = pos.attacks_from(pc, to, occ); - - // Rule 1. Checks which give opponent's king at most one escape square are dangerous - b = kingAtt & ~pos.pieces(them) & ~newAtt & ~(1ULL << to); - - if (!more_than_one(b)) + Piece pc = pos.piece_moved(move); + Square from = from_sq(move); + Square to = to_sq(move); + Color them = ~pos.side_to_move(); + Square ksq = pos.king_square(them); + Bitboard enemies = pos.pieces(them); + Bitboard kingAtt = pos.attacks_from(ksq); + Bitboard occ = pos.pieces() ^ from ^ ksq; + Bitboard oldAtt = pos.attacks_from(pc, from, occ); + Bitboard newAtt = pos.attacks_from(pc, to, occ); + + // Checks which give opponent's king at most one escape square are dangerous + if (!more_than_one(kingAtt & ~(enemies | newAtt | to))) return true; - // Rule 2. Queen contact check is very dangerous + // Queen contact check is very dangerous if (type_of(pc) == QUEEN && (kingAtt & to)) return true; - // Rule 3. Creating new double threats with checks - b = pos.pieces(them) & newAtt & ~oldAtt & ~(1ULL << ksq); + // Creating new double threats with checks is dangerous + Bitboard b = (enemies ^ ksq) & newAtt & ~oldAtt; while (b) { // Note that here we generate illegal "double move"! @@ -1337,113 +1369,90 @@ split_point_start: // At split points actual search starts from here } - // connected_moves() tests whether two moves are 'connected' in the sense - // that the first move somehow made the second move possible (for instance - // if the moving piece is the same in both moves). The first move is assumed - // to be the move that was made to reach the current position, while the - // second move is assumed to be a move from the current position. + // allows() tests whether the 'first' move at previous ply somehow makes the + // 'second' move possible, for instance if the moving piece is the same in + // both moves. Normally the second move is the threat (the best move returned + // from a null search that fails low). - bool connected_moves(const Position& pos, Move m1, Move m2) { + bool allows(const Position& pos, Move first, Move second) { - Square f1, t1, f2, t2; - Piece p1, p2; - Square ksq; + assert(is_ok(first)); + assert(is_ok(second)); + assert(color_of(pos.piece_on(from_sq(second))) == ~pos.side_to_move()); + assert(color_of(pos.piece_on(to_sq(first))) == ~pos.side_to_move()); - assert(is_ok(m1)); - assert(is_ok(m2)); + Square m1from = from_sq(first); + Square m2from = from_sq(second); + Square m1to = to_sq(first); + Square m2to = to_sq(second); - // Case 1: The moving piece is the same in both moves - f2 = from_sq(m2); - t1 = to_sq(m1); - if (f2 == t1) + // The piece is the same or second's destination was vacated by the first move + if (m1to == m2from || m2to == m1from) return true; - // Case 2: The destination square for m2 was vacated by m1 - t2 = to_sq(m2); - f1 = from_sq(m1); - if (t2 == f1) - return true; - - // Case 3: Moving through the vacated square - p2 = pos.piece_on(f2); - if (piece_is_slider(p2) && (between_bb(f2, t2) & f1)) + // Second one moves through the square vacated by first one + if (between_bb(m2from, m2to) & m1from) return true; - // Case 4: The destination square for m2 is defended by the moving piece in m1 - p1 = pos.piece_on(t1); - if (pos.attacks_from(p1, t1) & t2) + // Second's destination is defended by the first move's piece + Bitboard m1att = pos.attacks_from(pos.piece_on(m1to), m1to, pos.pieces() ^ m2from); + if (m1att & m2to) return true; - // Case 5: Discovered check, checking piece is the piece moved in m1 - ksq = pos.king_square(pos.side_to_move()); - if ( piece_is_slider(p1) - && (between_bb(t1, ksq) & f2) - && (pos.attacks_from(p1, t1, pos.pieces() ^ f2) & ksq)) + // Second move gives a discovered check through the first's checking piece + if (m1att & pos.king_square(pos.side_to_move())) + { + assert(between_bb(m1to, pos.king_square(pos.side_to_move())) & m2from); return true; + } return false; } - // value_to_tt() adjusts a mate score from "plies to mate from the root" to - // "plies to mate from the current position". Non-mate scores are unchanged. - // The function is called before storing a value to the transposition table. - - Value value_to_tt(Value v, int ply) { - - assert(v != VALUE_NONE); - - return v >= VALUE_MATE_IN_MAX_PLY ? v + ply - : v <= VALUE_MATED_IN_MAX_PLY ? v - ply : v; - } - - - // value_from_tt() is the inverse of value_to_tt(): It adjusts a mate score - // from the transposition table (where refers to the plies to mate/be mated - // from current position) to "plies to mate/be mated from the root". - - Value value_from_tt(Value v, int ply) { - - return v == VALUE_NONE ? VALUE_NONE - : v >= VALUE_MATE_IN_MAX_PLY ? v - ply - : v <= VALUE_MATED_IN_MAX_PLY ? v + ply : v; - } + // refutes() tests whether a 'first' move is able to defend against a 'second' + // opponent's move. In this case will not be pruned. Normally the second move + // is the threat (the best move returned from a null search that fails low). + bool refutes(const Position& pos, Move first, Move second) { - // connected_threat() tests whether it is safe to forward prune a move or if - // is somehow connected to the threat move returned by null search. + assert(is_ok(first)); + assert(is_ok(second)); - bool connected_threat(const Position& pos, Move m, Move threat) { + Square m1from = from_sq(first); + Square m2from = from_sq(second); + Square m1to = to_sq(first); + Square m2to = to_sq(second); - assert(is_ok(m)); - assert(is_ok(threat)); - assert(!pos.is_capture_or_promotion(m)); - assert(!pos.is_passed_pawn_push(m)); + // Don't prune moves of the threatened piece + if (m1from == m2to) + return true; - Square mfrom, mto, tfrom, tto; + // If the threatened piece has value less than or equal to the value of the + // threat piece, don't prune moves which defend it. + if ( pos.is_capture(second) + && ( PieceValue[MG][pos.piece_on(m2from)] >= PieceValue[MG][pos.piece_on(m2to)] + || type_of(pos.piece_on(m2from)) == KING)) + { + // Update occupancy as if the piece and the threat are moving + Bitboard occ = pos.pieces() ^ m1from ^ m1to ^ m2from; + Piece piece = pos.piece_on(m1from); - mfrom = from_sq(m); - mto = to_sq(m); - tfrom = from_sq(threat); - tto = to_sq(threat); + // The moved piece attacks the square 'tto' ? + if (pos.attacks_from(piece, m1to, occ) & m2to) + return true; - // Case 1: Don't prune moves which move the threatened piece - if (mfrom == tto) - return true; + // Scan for possible X-ray attackers behind the moved piece + Bitboard xray = (attacks_bb< ROOK>(m2to, occ) & pos.pieces(color_of(piece), QUEEN, ROOK)) + | (attacks_bb(m2to, occ) & pos.pieces(color_of(piece), QUEEN, BISHOP)); - // Case 2: If the threatened piece has value less than or equal to the - // value of the threatening piece, don't prune moves which defend it. - if ( pos.is_capture(threat) - && ( PieceValue[MG][pos.piece_on(tfrom)] >= PieceValue[MG][pos.piece_on(tto)] - || type_of(pos.piece_on(tfrom)) == KING) - && pos.move_attacks_square(m, tto)) - return true; + // Verify attackers are triggered by our move and not already existing + if (xray && (xray ^ (xray & pos.attacks_from(m2to)))) + return true; + } - // Case 3: If the moving piece in the threatened move is a slider, don't - // prune safe moves which block its ray. - if ( piece_is_slider(pos.piece_on(tfrom)) - && (between_bb(tfrom, tto) & mto) - && pos.see_sign(m) >= 0) + // Don't prune safe moves which block the threat path + if ((between_bb(m2from, m2to) & m1to) && pos.see_sign(first) >= 0) return true; return false; @@ -1500,23 +1509,24 @@ split_point_start: // At split points actual search starts from here std::stringstream s; Time::point elaspsed = Time::now() - SearchTime + 1; + size_t uciPVSize = std::min((size_t)Options["MultiPV"], RootMoves.size()); int selDepth = 0; for (size_t i = 0; i < Threads.size(); i++) - if (Threads[i].maxPly > selDepth) - selDepth = Threads[i].maxPly; + if (Threads[i]->maxPly > selDepth) + selDepth = Threads[i]->maxPly; - for (size_t i = 0; i < std::min((size_t)Options["MultiPV"], RootMoves.size()); i++) + for (size_t i = 0; i < uciPVSize; i++) { bool updated = (i <= PVIdx); if (depth == 1 && !updated) continue; - int d = (updated ? depth : depth - 1); - Value v = (updated ? RootMoves[i].score : RootMoves[i].prevScore); + int d = updated ? depth : depth - 1; + Value v = updated ? RootMoves[i].score : RootMoves[i].prevScore; - if (s.rdbuf()->in_avail()) + if (s.rdbuf()->in_avail()) // Not at first line s << "\n"; s << "info depth " << d @@ -1555,7 +1565,8 @@ void RootMove::extract_pv_from_tt(Position& pos) { do { pv.push_back(m); - assert(pos.move_is_legal(pv[ply])); + assert(MoveList(pos).contains(pv[ply])); + pos.do_move(pv[ply++], *st++); tte = TT.probe(pos.key()); @@ -1563,7 +1574,7 @@ void RootMove::extract_pv_from_tt(Position& pos) { && pos.is_pseudo_legal(m = tte->move()) // Local copy, TT could change && pos.pl_move_is_legal(m, pos.pinned_pieces()) && ply < MAX_PLY - && (!pos.is_draw() || ply < 2)); + && (!pos.is_draw() || ply < 2)); pv.push_back(MOVE_NONE); // Must be zero-terminating @@ -1580,22 +1591,15 @@ void RootMove::insert_pv_in_tt(Position& pos) { StateInfo state[MAX_PLY_PLUS_2], *st = state; TTEntry* tte; int ply = 0; - Value v, m; do { tte = TT.probe(pos.key()); if (!tte || tte->move() != pv[ply]) // Don't overwrite correct entries - { - if (pos.in_check()) - v = m = VALUE_NONE; - else - v = evaluate(pos, m); + TT.store(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE, pv[ply], VALUE_NONE, VALUE_NONE); - TT.store(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE, pv[ply], v, m); - } + assert(MoveList(pos).contains(pv[ply])); - assert(pos.move_is_legal(pv[ply])); pos.do_move(pv[ply++], *st++); } while (pv[ply] != MOVE_NONE); @@ -1608,33 +1612,31 @@ void RootMove::insert_pv_in_tt(Position& pos) { void Thread::idle_loop() { - // Pointer 'sp_master', if non-NULL, points to the active SplitPoint - // object for which the thread is the master. - const SplitPoint* sp_master = splitPointsCnt ? curSplitPoint : NULL; + // Pointer 'this_sp' is not null only if we are called from split(), and not + // at the thread creation. So it means we are the split point's master. + const SplitPoint* this_sp = splitPointsSize ? activeSplitPoint : NULL; - assert(!sp_master || (sp_master->master == this && is_searching)); + assert(!this_sp || (this_sp->masterThread == this && searching)); - // If this thread is the master of a split point and all slaves have - // finished their work at this split point, return from the idle loop. - while (!sp_master || sp_master->slavesMask) + // If this thread is the master of a split point and all slaves have finished + // their work at this split point, return from the idle loop. + while (!this_sp || this_sp->slavesMask) { - // If we are not searching, wait for a condition to be signaled - // instead of wasting CPU time polling for work. - while ( do_sleep - || do_exit - || (!is_searching && Threads.use_sleeping_threads())) + // If we are not searching, wait for a condition to be signaled instead of + // wasting CPU time polling for work. + while ((!searching && Threads.sleepWhileIdle) || exit) { - if (do_exit) + if (exit) { - assert(!sp_master); + assert(!this_sp); return; } - // Grab the lock to avoid races with Thread::wake_up() + // Grab the lock to avoid races with Thread::notify_one() mutex.lock(); - // If we are master and all slaves have finished don't go to sleep - if (sp_master && !sp_master->slavesMask) + // If we are master and all slaves have finished then exit idle_loop + if (this_sp && !this_sp->slavesMask) { mutex.unlock(); break; @@ -1642,23 +1644,23 @@ void Thread::idle_loop() { // Do sleep after retesting sleep conditions under lock protection, in // particular we need to avoid a deadlock in case a master thread has, - // in the meanwhile, allocated us and sent the wake_up() call before we - // had the chance to grab the lock. - if (do_sleep || !is_searching) + // in the meanwhile, allocated us and sent the notify_one() call before + // we had the chance to grab the lock. + if (!searching && !exit) sleepCondition.wait(mutex); mutex.unlock(); } // If this thread has been assigned work, launch a search - if (is_searching) + if (searching) { - assert(!do_sleep && !do_exit); + assert(!exit); Threads.mutex.lock(); - assert(is_searching); - SplitPoint* sp = curSplitPoint; + assert(searching); + SplitPoint* sp = activeSplitPoint; Threads.mutex.unlock(); @@ -1670,34 +1672,39 @@ void Thread::idle_loop() { sp->mutex.lock(); - assert(sp->activePositions[idx] == NULL); + assert(activePosition == NULL); - sp->activePositions[idx] = &pos; + activePosition = &pos; - if (sp->nodeType == Root) + switch (sp->nodeType) { + case Root: search(pos, ss+1, sp->alpha, sp->beta, sp->depth); - else if (sp->nodeType == PV) + break; + case PV: search(pos, ss+1, sp->alpha, sp->beta, sp->depth); - else if (sp->nodeType == NonPV) + break; + case NonPV: search(pos, ss+1, sp->alpha, sp->beta, sp->depth); - else + break; + default: assert(false); + } - assert(is_searching); + assert(searching); - is_searching = false; - sp->activePositions[idx] = NULL; + searching = false; + activePosition = NULL; sp->slavesMask &= ~(1ULL << idx); sp->nodes += pos.nodes_searched(); - // Wake up master thread so to allow it to return from the idle loop in - // case we are the last slave of the split point. - if ( Threads.use_sleeping_threads() - && this != sp->master + // Wake up master thread so to allow it to return from the idle loop + // in case we are the last slave of the split point. + if ( Threads.sleepWhileIdle + && this != sp->masterThread && !sp->slavesMask) { - assert(!sp->master->is_searching); - sp->master->wake_up(); + assert(!sp->masterThread->searching); + sp->masterThread->notify_one(); } // After releasing the lock we cannot access anymore any SplitPoint @@ -1735,11 +1742,11 @@ void check_time() { nodes = RootPos.nodes_searched(); // Loop across all split points and sum accumulated SplitPoint nodes plus - // all the currently active slaves positions. + // all the currently active positions nodes. for (size_t i = 0; i < Threads.size(); i++) - for (int j = 0; j < Threads[i].splitPointsCnt; j++) + for (int j = 0; j < Threads[i]->splitPointsSize; j++) { - SplitPoint& sp = Threads[i].splitPoints[j]; + SplitPoint& sp = Threads[i]->splitPoints[j]; sp.mutex.lock(); @@ -1747,8 +1754,9 @@ void check_time() { Bitboard sm = sp.slavesMask; while (sm) { - Position* pos = sp.activePositions[pop_lsb(&sm)]; - nodes += pos ? pos->nodes_searched() : 0; + Position* pos = Threads[pop_lsb(&sm)]->activePosition; + if (pos) + nodes += pos->nodes_searched(); } sp.mutex.unlock();