X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=e29f54498e1ce3bfd322b493fc73e641a8c3d873;hp=89ddfef6397b471ef00b87207dd9daa9338a8d0e;hb=45b0aea875860e9f0fe2d0435ee6163906639194;hpb=11b1a76f35108316ee37d9d7056f4d621305a7ed diff --git a/src/search.cpp b/src/search.cpp index 89ddfef6..e29f5449 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -21,7 +21,6 @@ #include #include #include -#include #include #include @@ -85,7 +84,7 @@ namespace { size_t PVSize, PVIdx; TimeManager TimeMgr; - int BestMoveChanges; + float BestMoveChanges; Value DrawValue[COLOR_NB]; HistoryStats History; GainsStats Gains; @@ -100,13 +99,10 @@ namespace { void id_loop(Position& pos); Value value_to_tt(Value v, int ply); Value value_from_tt(Value v, int ply); - 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); - class stop : public std::exception {}; - struct Skill { Skill(int l) : level(l), best(MOVE_NONE) {} ~Skill() { @@ -156,9 +152,8 @@ void Search::init() { // Init futility move count array for (d = 0; d < 32; d++) { - FutilityMoveCounts[1][d] = int(3.001 + 0.3 * pow(double(d), 1.8)); - FutilityMoveCounts[0][d] = d < 5 ? FutilityMoveCounts[1][d] - : 3 * FutilityMoveCounts[1][d] / 4; + FutilityMoveCounts[0][d] = int(3 + 0.3 * pow(double(d ), 1.8)) * 3/4 + (2 < d && d < 5); + FutilityMoveCounts[1][d] = int(3 + 0.3 * pow(double(d + 0.98), 1.8)); } } @@ -307,14 +302,15 @@ namespace { void id_loop(Position& pos) { - Stack stack[MAX_PLY_PLUS_3], *ss = stack+2; // To allow referencing (ss-2) - int depth, prevBestMoveChanges; + Stack stack[MAX_PLY_PLUS_6], *ss = stack+2; // To allow referencing (ss-2) + int depth; Value bestValue, alpha, beta, delta; std::memset(ss-2, 0, 5 * sizeof(Stack)); (ss-1)->currentMove = MOVE_NULL; // Hack to skip update gains - depth = BestMoveChanges = 0; + depth = 0; + BestMoveChanges = 0; bestValue = delta = alpha = -VALUE_INFINITE; beta = VALUE_INFINITE; @@ -336,14 +332,14 @@ namespace { // Iterative deepening loop until requested to stop or target depth reached while (++depth <= MAX_PLY && !Signals.stop && (!Limits.depth || depth <= Limits.depth)) { + // Age out PV variability metric + BestMoveChanges *= 0.8f; + // Save last iteration's scores before first PV line is searched and all // the move scores but the (new) PV are set to -VALUE_INFINITE. for (size_t i = 0; i < RootMoves.size(); i++) RootMoves[i].prevScore = RootMoves[i].score; - prevBestMoveChanges = BestMoveChanges; // Only sensible when PVSize == 1 - BestMoveChanges = 0; - // MultiPV loop. We perform a full root search for each PV line for (PVIdx = 0; PVIdx < PVSize; PVIdx++) { @@ -359,9 +355,7 @@ namespace { // research with bigger window until not failing high/low anymore. while (true) { - try { - bestValue = search(pos, ss, alpha, beta, depth * ONE_PLY, false); - } catch (stop&) {} + bestValue = search(pos, ss, alpha, beta, depth * ONE_PLY, false); // Bring to front the best move. It is critical that sorting is // done with a stable algorithm because all the values but the first @@ -443,7 +437,7 @@ namespace { // Take in account some extra time if the best move has changed if (depth > 4 && depth < 50 && PVSize == 1) - TimeMgr.pv_instability(BestMoveChanges, prevBestMoveChanges); + TimeMgr.pv_instability(BestMoveChanges); // Stop search if most of available time is already consumed. We // probably don't have enough time to search the first move at the @@ -546,13 +540,10 @@ namespace { if (PvNode && thisThread->maxPly < ss->ply) thisThread->maxPly = ss->ply; - if (Signals.stop || thisThread->cutoff_occurred()) - throw stop(); - if (!RootNode) { // Step 2. Check for aborted search and immediate draw - if (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 @@ -672,7 +663,7 @@ namespace { // Step 8. Null move search with verification search (is omitted in PV nodes) if ( !PvNode && !ss->skipNullMove - && depth > ONE_PLY + && depth >= 2 * ONE_PLY && eval >= beta && abs(beta) < VALUE_MATE_IN_MAX_PLY && pos.non_pawn_material(pos.side_to_move())) @@ -789,7 +780,7 @@ moves_loop: // When in check and at SpNode search starts from here singularExtensionNode = !RootNode && !SpNode - && depth >= (PvNode ? 6 * ONE_PLY : 8 * ONE_PLY) + && depth >= 8 * ONE_PLY && ttMove != MOVE_NONE && !excludedMove // Recursive singular search is not allowed && (tte->bound() & BOUND_LOWER) @@ -844,7 +835,7 @@ moves_loop: // When in check and at SpNode search starts from here ext = ONE_PLY; else if (givesCheck && pos.see_sign(move) >= 0) - ext = ONE_PLY / 2; + ext = inCheck || ss->staticEval <= alpha ? ONE_PLY : ONE_PLY / 2; // 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 @@ -946,10 +937,9 @@ moves_loop: // When in check and at SpNode search starts from here // Step 15. Reduced depth search (LMR). If the move fails high will be // re-searched at full depth. - if ( depth > 3 * ONE_PLY + if ( depth >= 3 * ONE_PLY && !pvMove && !captureOrPromotion - && !dangerous && move != ttMove && move != ss->killers[0] && move != ss->killers[1]) @@ -1007,6 +997,13 @@ moves_loop: // When in check and at SpNode search starts from here alpha = splitPoint->alpha; } + // Finished searching the move. If Signals.stop is true, the search + // was aborted because the user interrupted the search or because we + // ran out of time. In this case, the return value of the search cannot + // be trusted, and we don't update the best move and/or PV. + if (Signals.stop || thisThread->cutoff_occurred()) + return value; // To avoid returning VALUE_INFINITE + if (RootNode) { RootMove& rm = *std::find(RootMoves.begin(), RootMoves.end(), move); @@ -1232,6 +1229,7 @@ moves_loop: // When in check and at SpNode search starts from here && !givesCheck && move != ttMove && type_of(move) != PROMOTION + && futilityBase > -VALUE_KNOWN_WIN && !pos.is_passed_pawn_push(move)) { futilityValue = futilityBase @@ -1268,16 +1266,6 @@ moves_loop: // When in check and at SpNode search starts from here && pos.see_sign(move) < 0) continue; - // Don't search useless checks - if ( !PvNode - && !InCheck - && givesCheck - && move != ttMove - && !pos.is_capture_or_promotion(move) - && ss->staticEval + PawnValueMg / 4 < beta - && !check_is_dangerous(pos, move, futilityBase, beta)) - continue; - // Check for legality only before to do the move if (!pos.pl_move_is_legal(move, ci.pinned)) continue; @@ -1355,42 +1343,6 @@ moves_loop: // When in check and at SpNode search starts from here } - // check_is_dangerous() tests if a checking move can be pruned in qsearch() - - bool check_is_dangerous(const Position& pos, Move move, Value futilityBase, Value beta) - { - 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; - - // Queen contact check is very dangerous - if (type_of(pc) == QUEEN && (kingAtt & to)) - return true; - - // Creating new double threats with checks is dangerous - Bitboard b = (enemies ^ ksq) & newAtt & ~oldAtt; - while (b) - { - // Note that here we generate illegal "double move"! - if (futilityBase + PieceValue[EG][pos.piece_on(pop_lsb(&b))] >= beta) - return true; - } - - return false; - } - - // 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 @@ -1401,7 +1353,7 @@ moves_loop: // When in check and at SpNode search starts from here 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(type_of(first) == CASTLE || color_of(pos.piece_on(to_sq(first))) == ~pos.side_to_move()); Square m1from = from_sq(first); Square m2from = from_sq(second); @@ -1409,7 +1361,10 @@ moves_loop: // When in check and at SpNode search starts from here Square m2to = to_sq(second); // The piece is the same or second's destination was vacated by the first move - if (m1to == m2from || m2to == m1from) + // We exclude the trivial case where a sliding piece does in two moves what + // it could do in one move: eg. Ra1a2, Ra2a3. + if ( m2to == m1from + || (m1to == m2from && !squares_aligned(m1from, m2from, m2to))) return true; // Second one moves through the square vacated by first one @@ -1577,7 +1532,7 @@ moves_loop: // When in check and at SpNode search starts from here void RootMove::extract_pv_from_tt(Position& pos) { - StateInfo state[MAX_PLY_PLUS_3], *st = state; + StateInfo state[MAX_PLY_PLUS_6], *st = state; const TTEntry* tte; int ply = 0; Move m = pv[0]; @@ -1610,7 +1565,7 @@ void RootMove::extract_pv_from_tt(Position& pos) { void RootMove::insert_pv_in_tt(Position& pos) { - StateInfo state[MAX_PLY_PLUS_3], *st = state; + StateInfo state[MAX_PLY_PLUS_6], *st = state; const TTEntry* tte; int ply = 0; @@ -1685,7 +1640,7 @@ void Thread::idle_loop() { Threads.mutex.unlock(); - Stack stack[MAX_PLY_PLUS_3], *ss = stack+2; // To allow referencing (ss-2) + Stack stack[MAX_PLY_PLUS_6], *ss = stack+2; // To allow referencing (ss-2) Position pos(*sp->pos, this); std::memcpy(ss-2, sp->ss-2, 5 * sizeof(Stack)); @@ -1697,27 +1652,22 @@ void Thread::idle_loop() { activePosition = &pos; - try { - switch (sp->nodeType) { - case Root: - search(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode); - break; - case PV: - search(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode); - break; - case NonPV: - search(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode); - break; - default: - assert(false); - } - - assert(searching); - } - catch (stop&) { - sp->mutex.lock(); // Exception is thrown out of lock + switch (sp->nodeType) { + case Root: + search(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode); + break; + case PV: + search(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode); + break; + case NonPV: + search(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode); + break; + default: + assert(false); } + assert(searching); + searching = false; activePosition = NULL; sp->slavesMask &= ~(1ULL << idx);