X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=8ea1b718825dc1fc684c156235718e412fb49f64;hp=5e04dbb7b696cc874f63641c2643f9ca34f9653d;hb=62c68c2d2174ee5158cf3282c7429b15483f3d51;hpb=c6ba14b7c939fd212d002d5f4385219c5ffec53f diff --git a/src/search.cpp b/src/search.cpp index 5e04dbb7..8ea1b718 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -89,8 +89,8 @@ namespace { void idle_loop(int threadID, SplitPoint* sp); template - void split(const Position& pos, SearchStack* ss, Value* alpha, const Value beta, Value* bestValue, - Depth depth, bool mateThreat, int* moveCount, MovePicker* mp, int master, bool pvNode); + void split(const Position& pos, SearchStack* ss, int ply, Value* alpha, const Value beta, Value* bestValue, + Depth depth, bool mateThreat, int* moveCount, MovePicker* mp, bool pvNode); private: friend void poll(); @@ -235,8 +235,8 @@ namespace { const Value EasyMoveMargin = Value(0x200); // Last seconds noise filtering (LSN) - const bool UseLSNFiltering = true; - const int LSNTime = 4000; // In milliseconds + const bool UseLSNFiltering = false; + const int LSNTime = 100; // In milliseconds const Value LSNValue = value_from_centipawns(200); bool loseOnTime = false; @@ -282,13 +282,13 @@ namespace { /// Local functions Value id_loop(const Position& pos, Move searchMoves[]); - Value root_search(Position& pos, SearchStack* ss, RootMoveList& rml, Value* alphaPtr, Value* betaPtr); + Value root_search(Position& pos, SearchStack* ss, Move* pv, RootMoveList& rml, Value* alphaPtr, Value* betaPtr); template - Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, bool allowNullmove, int threadID, Move excludedMove = MOVE_NONE); + Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply); template - Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID); + Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply); template void sp_search(SplitPoint* sp, int threadID); @@ -296,8 +296,6 @@ namespace { template Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool singleEvasion, bool mateThreat, bool* dangerous); - void update_pv(SearchStack* ss, int ply); - void sp_update_pv(SearchStack* pss, SearchStack* ss, int ply); bool connected_moves(const Position& pos, Move m1, Move m2); bool value_is_mate(Value value); bool move_is_killer(Move m, SearchStack* ss); @@ -313,8 +311,8 @@ namespace { void poll(); void ponderhit(); void wait_for_stop_or_ponderhit(); - void init_ss_array(SearchStack* ss); - void print_pv_info(const Position& pos, SearchStack* ss, Value alpha, Value beta, Value value); + void init_ss_array(SearchStack* ss, int size); + void print_pv_info(const Position& pos, Move* ss, Value alpha, Value beta, Value value); #if !defined(_MSC_VER) void *init_thread(void *threadID); @@ -356,7 +354,7 @@ void init_search() { // Init futility margins array for (d = 0; d < 16; d++) for (mc = 0; mc < 64; mc++) - FutilityMarginsMatrix[d][mc] = 112 * int(log(double(d * d) / 2) / log(2.0) + 1) - 8 * mc + 45; + FutilityMarginsMatrix[d][mc] = 112 * int(log(double(d * d) / 2) / log(2.0) + 1.001) - 8 * mc + 45; // Init futility move count array for (d = 0; d < 32; d++) @@ -364,16 +362,16 @@ void init_search() { } -// SearchStack::init() initializes a search stack. Used at the beginning of a -// new search from the root. -void SearchStack::init(int ply) { +// SearchStack::init() initializes a search stack entry. +// Called at the beginning of search() when starting to examine a new node. +void SearchStack::init() { - pv[ply] = pv[ply + 1] = MOVE_NONE; - currentMove = threatMove = MOVE_NONE; + currentMove = threatMove = bestMove = MOVE_NONE; reduction = Depth(0); eval = VALUE_NONE; } +// SearchStack::initKillers() initializes killers for a search stack entry void SearchStack::initKillers() { mateKiller = MOVE_NONE; @@ -603,8 +601,9 @@ namespace { Value id_loop(const Position& pos, Move searchMoves[]) { - Position p(pos); + Position p(pos, pos.thread()); SearchStack ss[PLY_MAX_PLUS_2]; + Move pv[PLY_MAX_PLUS_2]; Move EasyMove = MOVE_NONE; Value value, alpha = -VALUE_INFINITE, beta = VALUE_INFINITE; @@ -633,9 +632,9 @@ namespace { // Initialize TT.new_search(); H.clear(); - init_ss_array(ss); + init_ss_array(ss, PLY_MAX_PLUS_2); + pv[0] = pv[1] = MOVE_NONE; ValueByIteration[1] = rml.get_move_score(0); - p.reset_ply(); Iteration = 1; // Is one move significantly better than others after initial scoring ? @@ -666,11 +665,11 @@ namespace { } // Search to the current depth, rml is updated and sorted, alpha and beta could change - value = root_search(p, ss, rml, &alpha, &beta); + value = root_search(p, ss, pv, rml, &alpha, &beta); // Write PV to transposition table, in case the relevant entries have // been overwritten during the search. - TT.insert_pv(p, ss->pv); + TT.insert_pv(p, pv); if (AbortSearch) break; // Value cannot be trusted. Break out immediately! @@ -679,7 +678,7 @@ namespace { ValueByIteration[Iteration] = value; // Drop the easy move if differs from the new best move - if (ss->pv[0] != EasyMove) + if (pv[0] != EasyMove) EasyMove = MOVE_NONE; if (UseTimeManagement) @@ -701,7 +700,7 @@ namespace { // Stop search early if one move seems to be much better than the others int64_t nodes = TM.nodes_searched(); if ( Iteration >= 8 - && EasyMove == ss->pv[0] + && EasyMove == pv[0] && ( ( rml.get_move_cumulative_nodes(0) > (nodes * 85) / 100 && current_search_time() > MaxSearchTime / 16) ||( rml.get_move_cumulative_nodes(0) > (nodes * 98) / 100 @@ -744,18 +743,18 @@ namespace { << " hashfull " << TT.full() << endl; // Print the best move and the ponder move to the standard output - if (ss->pv[0] == MOVE_NONE) + if (pv[0] == MOVE_NONE) { - ss->pv[0] = rml.get_move(0); - ss->pv[1] = MOVE_NONE; + pv[0] = rml.get_move(0); + pv[1] = MOVE_NONE; } - assert(ss->pv[0] != MOVE_NONE); + assert(pv[0] != MOVE_NONE); - cout << "bestmove " << ss->pv[0]; + cout << "bestmove " << pv[0]; - if (ss->pv[1] != MOVE_NONE) - cout << " ponder " << ss->pv[1]; + if (pv[1] != MOVE_NONE) + cout << " ponder " << pv[1]; cout << endl; @@ -769,12 +768,12 @@ namespace { LogFile << "\nNodes: " << TM.nodes_searched() << "\nNodes/second: " << nps() - << "\nBest move: " << move_to_san(p, ss->pv[0]); + << "\nBest move: " << move_to_san(p, pv[0]); StateInfo st; - p.do_move(ss->pv[0], st); + p.do_move(pv[0], st); LogFile << "\nPonder move: " - << move_to_san(p, ss->pv[1]) // Works also with MOVE_NONE + << move_to_san(p, pv[1]) // Works also with MOVE_NONE << endl; } return rml.get_move_score(0); @@ -786,7 +785,7 @@ namespace { // scheme, prints some information to the standard output and handles // the fail low/high loops. - Value root_search(Position& pos, SearchStack* ss, RootMoveList& rml, Value* alphaPtr, Value* betaPtr) { + Value root_search(Position& pos, SearchStack* ss, Move* pv, RootMoveList& rml, Value* alphaPtr, Value* betaPtr) { EvalInfo ei; StateInfo st; @@ -811,7 +810,7 @@ namespace { // Step 5. Evaluate the position statically // At root we do this only to get reference value for child nodes if (!isCheck) - ss->eval = evaluate(pos, ei, 0); + ss->eval = evaluate(pos, ei); // Step 6. Razoring (omitted at root) // Step 7. Static null move pruning (omitted at root) @@ -876,7 +875,7 @@ namespace { alpha = -VALUE_INFINITE; // Full depth PV search, done on first move or after a fail high - value = -search(pos, ss+1, -beta, -alpha, newDepth, false, 0); + value = -search(pos, ss+1, -beta, -alpha, newDepth, 1); } else { @@ -892,23 +891,37 @@ namespace { ss->reduction = reduction(depth, i - MultiPV + 2); if (ss->reduction) { + assert(newDepth-ss->reduction >= OnePly); + // Reduced depth non-pv search using alpha as upperbound - value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, true, 0); + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, 1); doFullDepthSearch = (value > alpha); } + + // The move failed high, but if reduction is very big we could + // face a false positive, retry with a less aggressive reduction, + // if the move fails high again then go with full depth search. + if (doFullDepthSearch && ss->reduction > 2 * OnePly) + { + assert(newDepth - OnePly >= OnePly); + + ss->reduction = OnePly; + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, 1); + doFullDepthSearch = (value > alpha); + } + ss->reduction = Depth(0); // Restore original reduction } // Step 15. Full depth search if (doFullDepthSearch) { // Full depth non-pv search using alpha as upperbound - ss->reduction = Depth(0); - value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth, true, 0); + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth, 1); // If we are above alpha then research at same depth but as PV // to get a correct score or eventually a fail high above beta. if (value > alpha) - value = -search(pos, ss+1, -beta, -alpha, newDepth, false, 0); + value = -search(pos, ss+1, -beta, -alpha, newDepth, 1); } } @@ -922,12 +935,12 @@ namespace { // We are failing high and going to do a research. It's important to update // the score before research in case we run out of time while researching. rml.set_move_score(i, value); - update_pv(ss, 0); - TT.extract_pv(pos, ss->pv, PLY_MAX); - rml.set_move_pv(i, ss->pv); + ss->bestMove = move; + TT.extract_pv(pos, move, pv, PLY_MAX); + rml.set_move_pv(i, pv); // Print information to the standard output - print_pv_info(pos, ss, alpha, beta, value); + print_pv_info(pos, pv, alpha, beta, value); // Prepare for a research after a fail high, each time with a wider window *betaPtr = beta = Min(beta + AspirationDelta * (1 << researchCountFH), VALUE_INFINITE); @@ -962,9 +975,9 @@ namespace { // Update PV rml.set_move_score(i, value); - update_pv(ss, 0); - TT.extract_pv(pos, ss->pv, PLY_MAX); - rml.set_move_pv(i, ss->pv); + ss->bestMove = move; + TT.extract_pv(pos, move, pv, PLY_MAX); + rml.set_move_pv(i, pv); if (MultiPV == 1) { @@ -975,7 +988,7 @@ namespace { BestMoveChangesByIteration[Iteration]++; // Print information to the standard output - print_pv_info(pos, ss, alpha, beta, value); + print_pv_info(pos, pv, alpha, beta, value); // Raise alpha to setup proper non-pv search upper bound if (value > alpha) @@ -1031,34 +1044,34 @@ namespace { // search<>() is the main search function for both PV and non-PV nodes template - Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, - bool allowNullmove, int threadID, Move excludedMove) { + Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply) { assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta > alpha && beta <= VALUE_INFINITE); assert(PvNode || alpha == beta - 1); - assert(pos.ply() > 0 && pos.ply() < PLY_MAX); - assert(threadID >= 0 && threadID < TM.active_threads()); + assert(ply > 0 && ply < PLY_MAX); + assert(pos.thread() >= 0 && pos.thread() < TM.active_threads()); Move movesSearched[256]; EvalInfo ei; StateInfo st; const TTEntry* tte; - Move ttMove, move; + Key posKey; + Move ttMove, move, excludedMove; Depth ext, newDepth; Value bestValue, value, oldAlpha; Value refinedValue, nullValue, futilityValueScaled; // Non-PV specific bool isCheck, singleEvasion, moveIsCheck, captureOrPromotion, dangerous; bool mateThreat = false; int moveCount = 0; - int ply = pos.ply(); + int threadID = pos.thread(); refinedValue = bestValue = value = -VALUE_INFINITE; oldAlpha = alpha; // Step 1. Initialize node and poll. Polling can abort search TM.incrementNodeCounter(threadID); - ss->init(ply); - (ss + 2)->initKillers(); + ss->init(); + (ss+2)->initKillers(); if (threadID == 0 && ++NodesSincePoll > NodesBetweenPolls) { @@ -1083,7 +1096,8 @@ namespace { // We don't want the score of a partial search to overwrite a previous full search // TT value, so we use a different position key in case of an excluded move exists. - Key posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key(); + excludedMove = ss->excludedMove; + posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key(); tte = TT.retrieve(posKey); ttMove = (tte ? tte->move() : MOVE_NONE); @@ -1116,7 +1130,7 @@ namespace { ei.kingDanger[pos.side_to_move()] = tte->king_danger(); } else - ss->eval = evaluate(pos, ei, threadID); + ss->eval = evaluate(pos, ei); refinedValue = refine_eval(tte, ss->eval, ply); // Enhance accuracy with TT value if possible update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval); @@ -1132,8 +1146,12 @@ namespace { && !value_is_mate(beta) && !pos.has_pawn_on_7th(pos.side_to_move())) { + // Pass ss->eval to qsearch() and avoid an evaluate call + if (!tte || tte->static_value() == VALUE_NONE) + TT.store(posKey, ss->eval, VALUE_TYPE_EXACT, Depth(-127*OnePly), MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]); + Value rbeta = beta - razor_margin(depth); - Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), threadID); + Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), ply); if (v < rbeta) // Logically we should return (v + razor_margin(depth)), but // surprisingly this did slightly weaker in tests. @@ -1144,7 +1162,7 @@ namespace { // We're betting that the opponent doesn't have a move that will reduce // the score by more than futility_margin(depth) if we do a null move. if ( !PvNode - && allowNullmove + && !ss->skipNullMove && depth < RazorDepth && refinedValue >= beta + futility_margin(depth, 0) && !isCheck @@ -1157,7 +1175,7 @@ namespace { // at least beta. Otherwise we do a null move if static value is not more than // NullMoveMargin under beta. if ( !PvNode - && allowNullmove + && !ss->skipNullMove && depth > OnePly && refinedValue >= beta - (depth >= 4 * OnePly ? NullMoveMargin : 0) && !isCheck @@ -1174,9 +1192,11 @@ namespace { R++; pos.do_null_move(st); + (ss+1)->skipNullMove = true; - nullValue = depth-R*OnePly < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), threadID) - : - search(pos, ss+1, -beta, -alpha, depth-R*OnePly, false, threadID); + nullValue = depth-R*OnePly < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), ply+1) + : - search(pos, ss+1, -beta, -alpha, depth-R*OnePly, ply+1); + (ss+1)->skipNullMove = false; pos.undo_null_move(); if (nullValue >= beta) @@ -1186,8 +1206,14 @@ namespace { nullValue = beta; // Do zugzwang verification search at high depths - if ( depth < 6 * OnePly - || search(pos, ss, alpha, beta, depth-5*OnePly, false, threadID) >= beta) + if (depth < 6 * OnePly) + return nullValue; + + ss->skipNullMove = true; + Value v = search(pos, ss, alpha, beta, depth-5*OnePly, ply); + ss->skipNullMove = false; + + if (v >= beta) return nullValue; } else @@ -1211,12 +1237,16 @@ namespace { // Step 9. Internal iterative deepening if ( depth >= IIDDepth[PvNode] - && (ttMove == MOVE_NONE || (PvNode && tte->depth() <= depth - 4 * OnePly)) + && ttMove == MOVE_NONE && (PvNode || (!isCheck && ss->eval >= beta - IIDMargin))) { Depth d = (PvNode ? depth - 2 * OnePly : depth / 2); - search(pos, ss, alpha, beta, d, false, threadID); - ttMove = ss->pv[ply]; + + ss->skipNullMove = true; + search(pos, ss, alpha, beta, d, ply); + ss->skipNullMove = false; + + ttMove = ss->bestMove; tte = TT.retrieve(posKey); } @@ -1263,8 +1293,11 @@ namespace { if (abs(ttValue) < VALUE_KNOWN_WIN) { Value b = ttValue - SingularExtensionMargin; - Value v = search(pos, ss, b - 1, b, depth / 2, false, threadID, move); - + ss->excludedMove = move; + ss->skipNullMove = true; + Value v = search(pos, ss, b - 1, b, depth / 2, ply); + ss->skipNullMove = false; + ss->excludedMove = MOVE_NONE; if (v < ttValue - SingularExtensionMargin) ext = OnePly; } @@ -1310,8 +1343,8 @@ namespace { // Step extra. pv search (only in PV nodes) // The first move in list is the expected PV if (PvNode && moveCount == 1) - value = newDepth < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), threadID) - : - search(pos, ss+1, -beta, -alpha, newDepth, false, threadID); + value = newDepth < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), ply+1) + : - search(pos, ss+1, -beta, -alpha, newDepth, ply+1); else { // Step 14. Reduced depth search @@ -1328,8 +1361,8 @@ namespace { if (ss->reduction) { Depth d = newDepth - ss->reduction; - value = d < OnePly ? -qsearch(pos, ss+1, -(alpha+1), -alpha, Depth(0), threadID) - : - search(pos, ss+1, -(alpha+1), -alpha, d, true, threadID); + value = d < OnePly ? -qsearch(pos, ss+1, -(alpha+1), -alpha, Depth(0), ply+1) + : - search(pos, ss+1, -(alpha+1), -alpha, d, ply+1); doFullDepthSearch = (value > alpha); } @@ -1342,7 +1375,7 @@ namespace { assert(newDepth - OnePly >= OnePly); ss->reduction = OnePly; - value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, true, threadID); + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, ply+1); doFullDepthSearch = (value > alpha); } ss->reduction = Depth(0); // Restore original reduction @@ -1351,15 +1384,15 @@ namespace { // Step 15. Full depth search if (doFullDepthSearch) { - value = newDepth < OnePly ? -qsearch(pos, ss+1, -(alpha+1), -alpha, Depth(0), threadID) - : - search(pos, ss+1, -(alpha+1), -alpha, newDepth, true, threadID); + value = newDepth < OnePly ? -qsearch(pos, ss+1, -(alpha+1), -alpha, Depth(0), ply+1) + : - search(pos, ss+1, -(alpha+1), -alpha, newDepth, ply+1); // 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 && value < beta) - value = newDepth < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), threadID) - : - search(pos, ss+1, -beta, -alpha, newDepth, false, threadID); + value = newDepth < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), ply+1) + : - search(pos, ss+1, -beta, -alpha, newDepth, ply+1); } } @@ -1377,10 +1410,10 @@ namespace { if (PvNode && value < beta) // This guarantees that always: alpha < beta alpha = value; - update_pv(ss, ply); - if (value == value_mate_in(ply + 1)) ss->mateKiller = move; + + ss->bestMove = move; } } @@ -1392,8 +1425,8 @@ namespace { && !AbortSearch && !TM.thread_should_stop(threadID) && Iteration <= 99) - TM.split(pos, ss, &alpha, beta, &bestValue, depth, - mateThreat, &moveCount, &mp, threadID, PvNode); + TM.split(pos, ss, ply, &alpha, beta, &bestValue, depth, + mateThreat, &moveCount, &mp, PvNode); } // Step 19. Check for mate and stalemate @@ -1409,22 +1442,20 @@ namespace { if (AbortSearch || TM.thread_should_stop(threadID)) return bestValue; - if (bestValue <= oldAlpha) - TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]); + ValueType f = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT); + move = (bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove); + TT.store(posKey, value_to_tt(bestValue, ply), f, depth, move, ss->eval, ei.kingDanger[pos.side_to_move()]); - else if (bestValue >= beta) + // Update killers and history only for non capture moves that fails high + if (bestValue >= beta) { TM.incrementBetaCounter(pos.side_to_move(), depth, threadID); - move = ss->pv[ply]; - TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move, ss->eval, ei.kingDanger[pos.side_to_move()]); if (!pos.move_is_capture_or_promotion(move)) { update_history(pos, move, depth, movesSearched, moveCount); update_killers(move, ss); } } - else - TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, depth, ss->pv[ply], ss->eval, ei.kingDanger[pos.side_to_move()]); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1437,27 +1468,26 @@ namespace { // less than OnePly). template - Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID) { + Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply) { assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); assert(PvNode || alpha == beta - 1); assert(depth <= 0); - assert(pos.ply() > 0 && pos.ply() < PLY_MAX); - assert(threadID >= 0 && threadID < TM.active_threads()); + assert(ply > 0 && ply < PLY_MAX); + assert(pos.thread() >= 0 && pos.thread() < TM.active_threads()); EvalInfo ei; StateInfo st; Move ttMove, move; - Value staticValue, bestValue, value, futilityBase, futilityValue; - bool isCheck, enoughMaterial, moveIsCheck, evasionPrunable; - const TTEntry* tte = NULL; - int moveCount = 0; - int ply = pos.ply(); + Value bestValue, value, futilityValue, futilityBase; + bool isCheck, deepChecks, enoughMaterial, moveIsCheck, evasionPrunable; + const TTEntry* tte; Value oldAlpha = alpha; - TM.incrementNodeCounter(threadID); - ss->init(ply); + TM.incrementNodeCounter(pos.thread()); + ss->bestMove = ss->currentMove = MOVE_NONE; + ss->eval = VALUE_NONE; // Check for an instant draw or maximum ply reached if (pos.is_draw() || ply >= PLY_MAX - 1) @@ -1478,39 +1508,42 @@ namespace { // Evaluate the position statically if (isCheck) - staticValue = -VALUE_INFINITE; - else if (tte && tte->static_value() != VALUE_NONE) { - staticValue = tte->static_value(); - ei.kingDanger[pos.side_to_move()] = tte->king_danger(); + bestValue = futilityBase = -VALUE_INFINITE; + deepChecks = enoughMaterial = false; } else - staticValue = evaluate(pos, ei, threadID); - - if (!isCheck) { - ss->eval = staticValue; + if (tte && tte->static_value() != VALUE_NONE) + { + ei.kingDanger[pos.side_to_move()] = tte->king_danger(); + bestValue = tte->static_value(); + } + else + bestValue = evaluate(pos, ei); + + ss->eval = bestValue; update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval); - } - // Initialize "stand pat score", and return it immediately if it is - // at least beta. - bestValue = staticValue; + // Stand pat. Return immediately if static value is at least beta + if (bestValue >= beta) + { + if (!tte) + TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, Depth(-127*OnePly), MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]); - if (bestValue >= beta) - { - // Store the score to avoid a future costly evaluation() call - if (!isCheck && !tte) - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, Depth(-127*OnePly), MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]); + return bestValue; + } - return bestValue; - } + if (PvNode && bestValue > alpha) + alpha = bestValue; - if (bestValue > alpha) - alpha = bestValue; + // If we are near beta then try to get a cutoff pushing checks a bit further + deepChecks = (depth == -OnePly && bestValue >= beta - PawnValueMidgame / 8); - // If we are near beta then try to get a cutoff pushing checks a bit further - bool deepChecks = (depth == -OnePly && staticValue >= beta - PawnValueMidgame / 8); + // Futility pruning parameters, not needed when in check + futilityBase = bestValue + FutilityMarginQS + ei.kingDanger[pos.side_to_move()]; + enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame; + } // Initialize a MovePicker object for the current position, and prepare // to search the moves. Because the depth is <= 0 here, only captures, @@ -1518,8 +1551,6 @@ namespace { // and we are near beta) will be generated. MovePicker mp = MovePicker(pos, ttMove, deepChecks ? Depth(0) : depth, H); CheckInfo ci(pos); - enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame; - futilityBase = staticValue + FutilityMarginQS + ei.kingDanger[pos.side_to_move()]; // Loop through the moves until no moves remain or a beta cutoff occurs while ( alpha < beta @@ -1529,16 +1560,12 @@ namespace { moveIsCheck = pos.move_is_check(move, ci); - // Update current move - moveCount++; - ss->currentMove = move; - // Futility pruning if ( !PvNode - && enoughMaterial && !isCheck && !moveIsCheck && move != ttMove + && enoughMaterial && !move_is_promotion(move) && !pos.move_is_passed_pawn_push(move)) { @@ -1569,9 +1596,12 @@ namespace { && pos.see_sign(move) < 0) 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-OnePly, threadID); + value = -qsearch(pos, ss+1, -beta, -alpha, depth-OnePly, ply+1); pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); @@ -1583,35 +1613,25 @@ namespace { if (value > alpha) { alpha = value; - update_pv(ss, ply); + ss->bestMove = move; } } } // All legal moves have been searched. A special case: If we're in check // and no legal moves were found, it is checkmate. - if (!moveCount && isCheck) // Mate! + if (isCheck && bestValue == -VALUE_INFINITE) return value_mated_in(ply); // Update transposition table Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1)); - if (bestValue <= oldAlpha) - { - // If bestValue isn't changed it means it is still the static evaluation - // of the node, so keep this info to avoid a future evaluation() call. - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, d, MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]); - } - else if (bestValue >= beta) - { - move = ss->pv[ply]; - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move, ss->eval, ei.kingDanger[pos.side_to_move()]); + ValueType f = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT); + TT.store(pos.get_key(), value_to_tt(bestValue, ply), f, d, ss->bestMove, ss->eval, ei.kingDanger[pos.side_to_move()]); - // Update killers only for good checking moves - if (!pos.move_is_capture_or_promotion(move)) - update_killers(move, ss); - } - else - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, d, ss->pv[ply], ss->eval, ei.kingDanger[pos.side_to_move()]); + // Update killers only for checking moves that fails high + if ( bestValue >= beta + && !pos.move_is_capture_or_promotion(ss->bestMove)) + update_killers(ss->bestMove, ss); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1642,9 +1662,8 @@ namespace { int moveCount; value = -VALUE_INFINITE; - Position pos(*sp->pos); + Position pos(*sp->pos, threadID); CheckInfo ci(pos); - int ply = pos.ply(); SearchStack* ss = sp->sstack[threadID] + 1; isCheck = pos.is_check(); @@ -1675,7 +1694,7 @@ namespace { if ( !PvNode && !captureOrPromotion && !isCheck - && !dangerous + && !dangerous && !move_is_castle(move)) { // Move count based pruning @@ -1717,10 +1736,11 @@ namespace { ss->reduction = reduction(sp->depth, moveCount); if (ss->reduction) { - Value localAlpha = sp->alpha; + Value localAlpha = sp->alpha; Depth d = newDepth - ss->reduction; - value = d < OnePly ? -qsearch(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0), threadID) - : - search(pos, ss+1, -(localAlpha+1), -localAlpha, d, true, threadID); + value = d < OnePly ? -qsearch(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0), sp->ply+1) + : - search(pos, ss+1, -(localAlpha+1), -localAlpha, d, sp->ply+1); + doFullDepthSearch = (value > localAlpha); } @@ -1733,25 +1753,25 @@ namespace { ss->reduction = OnePly; Value localAlpha = sp->alpha; - value = -search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, true, threadID); + value = -search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, sp->ply+1); doFullDepthSearch = (value > localAlpha); } + ss->reduction = Depth(0); // Restore original reduction } // Step 15. Full depth search if (doFullDepthSearch) { - ss->reduction = Depth(0); Value localAlpha = sp->alpha; - value = newDepth < OnePly ? -qsearch(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0), threadID) - : - search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth, true, threadID); + value = newDepth < OnePly ? -qsearch(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0), sp->ply+1) + : - search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth, sp->ply+1); // 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 > localAlpha && value < sp->beta) - value = newDepth < OnePly ? -qsearch(pos, ss+1, -sp->beta, -sp->alpha, Depth(0), threadID) - : - search(pos, ss+1, -sp->beta, -sp->alpha, newDepth, false, threadID); + value = newDepth < OnePly ? -qsearch(pos, ss+1, -sp->beta, -sp->alpha, Depth(0), sp->ply+1) + : - search(pos, ss+1, -sp->beta, -sp->alpha, newDepth, sp->ply+1); } // Step 16. Undo move @@ -1774,7 +1794,7 @@ namespace { if (PvNode && value < sp->beta) // This guarantees that always: sp->alpha < sp->beta sp->alpha = value; - sp_update_pv(sp->parentSstack, ss, ply); + sp->parentSstack->bestMove = ss->bestMove = move; } } } @@ -1786,43 +1806,6 @@ namespace { lock_release(&(sp->lock)); } - // update_pv() is called whenever a search returns a value > alpha. - // It updates the PV in the SearchStack object corresponding to the - // current node. - - void update_pv(SearchStack* ss, int ply) { - - assert(ply >= 0 && ply < PLY_MAX); - - int p; - - ss->pv[ply] = ss->currentMove; - - for (p = ply + 1; (ss+1)->pv[p] != MOVE_NONE; p++) - ss->pv[p] = (ss+1)->pv[p]; - - ss->pv[p] = MOVE_NONE; - } - - - // sp_update_pv() is a variant of update_pv for use at split points. The - // difference between the two functions is that sp_update_pv also updates - // the PV at the parent node. - - void sp_update_pv(SearchStack* pss, SearchStack* ss, int ply) { - - assert(ply >= 0 && ply < PLY_MAX); - - int p; - - ss->pv[ply] = pss->pv[ply] = ss->currentMove; - - for (p = ply + 1; (ss+1)->pv[p] != MOVE_NONE; p++) - ss->pv[p] = pss->pv[p] = (ss+1)->pv[p]; - - ss->pv[p] = pss->pv[p] = MOVE_NONE; - } - // connected_moves() tests whether two moves are 'connected' in the sense // that the first move somehow made the second move possible (for instance @@ -1923,7 +1906,7 @@ namespace { if (*dangerous) { - if (moveIsCheck) + if (moveIsCheck && pos.see_sign(m) >= 0) result += CheckExtension[PvNode]; if (singleEvasion) @@ -2213,14 +2196,21 @@ namespace { } - // init_ss_array() does a fast reset of the first entries of a SearchStack array + // init_ss_array() does a fast reset of the first entries of a SearchStack + // array and of all the excludedMove and skipNullMove entries. - void init_ss_array(SearchStack* ss) { + void init_ss_array(SearchStack* ss, int size) { - for (int i = 0; i < 3; i++, ss++) + for (int i = 0; i < size; i++, ss++) { - ss->init(i); - ss->initKillers(); + ss->excludedMove = MOVE_NONE; + ss->skipNullMove = false; + + if (i < 3) + { + ss->init(); + ss->initKillers(); + } } } @@ -2255,7 +2245,7 @@ namespace { // print_pv_info() prints to standard output and eventually to log file information on // the current PV line. It is called at each iteration or after a new pv is found. - void print_pv_info(const Position& pos, SearchStack* ss, Value alpha, Value beta, Value value) { + void print_pv_info(const Position& pos, Move* pv, Value alpha, Value beta, Value value) { cout << "info depth " << Iteration << " score " << value_to_string(value) @@ -2266,8 +2256,8 @@ namespace { << " nps " << nps() << " pv "; - for (int j = 0; ss->pv[j] != MOVE_NONE && j < PLY_MAX; j++) - cout << ss->pv[j] << " "; + for (int j = 0; pv[j] != MOVE_NONE && j < PLY_MAX; j++) + cout << pv[j] << " "; cout << endl; @@ -2277,7 +2267,7 @@ namespace { : (value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT)); LogFile << pretty_pv(pos, current_search_time(), Iteration, - TM.nodes_searched(), value, type, ss->pv) << endl; + TM.nodes_searched(), value, type, pv) << endl; } } @@ -2592,18 +2582,21 @@ namespace { // split() returns. template - void ThreadsManager::split(const Position& p, SearchStack* ss, Value* alpha, const Value beta, - Value* bestValue, Depth depth, bool mateThreat, int* moveCount, - MovePicker* mp, int master, bool pvNode) { + void ThreadsManager::split(const Position& p, SearchStack* ss, int ply, Value* alpha, + const Value beta, Value* bestValue, Depth depth, bool mateThreat, + int* moveCount, MovePicker* mp, bool pvNode) { assert(p.is_ok()); + assert(ply > 0 && ply < PLY_MAX); assert(*bestValue >= -VALUE_INFINITE); assert(*bestValue <= *alpha); assert(*alpha < beta); assert(beta <= VALUE_INFINITE); assert(depth > Depth(0)); - assert(master >= 0 && master < ActiveThreads); + assert(p.thread() >= 0 && p.thread() < ActiveThreads); assert(ActiveThreads > 1); + int master = p.thread(); + lock_grab(&MPLock); // If no other thread is available to help us, or if we have too many @@ -2621,6 +2614,7 @@ namespace { // Initialize the split point object splitPoint->parent = threads[master].splitPoint; splitPoint->stopRequest = false; + splitPoint->ply = ply; splitPoint->depth = depth; splitPoint->mateThreat = mateThreat; splitPoint->alpha = *alpha; @@ -2752,10 +2746,10 @@ namespace { continue; // Find a quick score for the move - init_ss_array(ss); + init_ss_array(ss, PLY_MAX_PLUS_2); pos.do_move(cur->move, st); moves[count].move = cur->move; - moves[count].score = -qsearch(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 0); + moves[count].score = -qsearch(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 1); moves[count].pv[0] = cur->move; moves[count].pv[1] = MOVE_NONE; pos.undo_move(cur->move);