X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=4c90db53d93619a3a34cf0c3a9f0e6876a507ef8;hp=6715d6808f3f26dc28261108247203b62eb1823f;hb=e9eea873418775aec7eba786ec30c0b706f12656;hpb=5f3c660d5d768ea5132439c5a8916673b909c0c9 diff --git a/src/search.cpp b/src/search.cpp index 6715d680..4c90db53 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -236,7 +236,7 @@ namespace { // Last seconds noise filtering (LSN) const bool UseLSNFiltering = true; - const int LSNTime = 4000; // In milliseconds + const int LSNTime = 100; // In milliseconds const Value LSNValue = value_from_centipawns(200); bool loseOnTime = false; @@ -296,8 +296,8 @@ 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); + void update_pv(SearchStack* ss); + void sp_update_pv(SearchStack* pss, SearchStack* ss); bool connected_moves(const Position& pos, Move m1, Move m2); bool value_is_mate(Value value); bool move_is_killer(Move m, SearchStack* ss); @@ -366,9 +366,9 @@ 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) { +void SearchStack::init() { - pv[ply] = pv[ply + 1] = MOVE_NONE; + pv[0] = pv[1] = MOVE_NONE; currentMove = threatMove = MOVE_NONE; reduction = Depth(0); eval = VALUE_NONE; @@ -892,17 +892,31 @@ 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); 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); + 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); // If we are above alpha then research at same depth but as PV @@ -922,7 +936,7 @@ 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); + update_pv(ss); TT.extract_pv(pos, ss->pv, PLY_MAX); rml.set_move_pv(i, ss->pv); @@ -962,7 +976,7 @@ namespace { // Update PV rml.set_move_score(i, value); - update_pv(ss, 0); + update_pv(ss); TT.extract_pv(pos, ss->pv, PLY_MAX); rml.set_move_pv(i, ss->pv); @@ -1058,8 +1072,8 @@ namespace { // 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) { @@ -1134,6 +1148,10 @@ 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)); if (v < rbeta) @@ -1230,7 +1248,7 @@ namespace { search(pos, ss, alpha, beta, d); ss->skipNullMove = false; - ttMove = ss->pv[ply]; + ttMove = ss->pv[0]; tte = TT.retrieve(posKey); } @@ -1395,7 +1413,7 @@ namespace { if (PvNode && value < beta) // This guarantees that always: alpha < beta alpha = value; - update_pv(ss, ply); + update_pv(ss); if (value == value_mate_in(ply + 1)) ss->mateKiller = move; @@ -1433,7 +1451,7 @@ namespace { else if (bestValue >= beta) { TM.incrementBetaCounter(pos.side_to_move(), depth, threadID); - move = ss->pv[ply]; + move = ss->pv[0]; 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)) { @@ -1442,7 +1460,7 @@ namespace { } } else - TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, depth, ss->pv[ply], ss->eval, ei.kingDanger[pos.side_to_move()]); + TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, depth, ss->pv[0], ss->eval, ei.kingDanger[pos.side_to_move()]); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1467,16 +1485,15 @@ namespace { EvalInfo ei; StateInfo st; Move ttMove, move; - Value staticValue, bestValue, value, futilityBase; - 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; - Value futilityValue = VALUE_INFINITE; + int ply = pos.ply(); TM.incrementNodeCounter(pos.thread()); - ss->init(ply); + ss->pv[0] = ss->pv[1] = 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) @@ -1497,39 +1514,42 @@ 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); - - 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 (PvNode && 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, @@ -1537,8 +1557,6 @@ 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 @@ -1548,24 +1566,15 @@ 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)) { - // Can only decrease from previous move because of - // MVV ordering so we don't need to recheck. - if (futilityValue < alpha) - continue; - futilityValue = futilityBase + pos.endgame_value_of_piece_on(move_to(move)) + (move_is_ep(move) ? PawnValueEndgame : Value(0)); @@ -1593,6 +1602,9 @@ 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); @@ -1607,27 +1619,23 @@ namespace { if (value > alpha) { alpha = value; - update_pv(ss, ply); + update_pv(ss); } } } // 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]; + move = ss->pv[0]; TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move, ss->eval, ei.kingDanger[pos.side_to_move()]); // Update killers only for good checking moves @@ -1635,7 +1643,7 @@ namespace { 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()]); + TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, d, ss->pv[0], ss->eval, ei.kingDanger[pos.side_to_move()]); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1668,7 +1676,6 @@ namespace { Position pos(*sp->pos, threadID); CheckInfo ci(pos); - int ply = pos.ply(); SearchStack* ss = sp->sstack[threadID] + 1; isCheck = pos.is_check(); @@ -1798,7 +1805,7 @@ 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_update_pv(sp->parentSstack, ss); } } } @@ -1814,18 +1821,16 @@ namespace { // 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; + void update_pv(SearchStack* ss) { - ss->pv[ply] = ss->currentMove; + Move* src = (ss+1)->pv; + Move* dst = ss->pv; - for (p = ply + 1; (ss+1)->pv[p] != MOVE_NONE; p++) - ss->pv[p] = (ss+1)->pv[p]; + *dst = ss->currentMove; - ss->pv[p] = MOVE_NONE; + do + *++dst = *src; + while (*src++ != MOVE_NONE); } @@ -1833,18 +1838,17 @@ namespace { // 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; + void sp_update_pv(SearchStack* pss, SearchStack* ss) { - ss->pv[ply] = pss->pv[ply] = ss->currentMove; + Move* src = (ss+1)->pv; + Move* dst = ss->pv; + Move* pdst = pss->pv; - for (p = ply + 1; (ss+1)->pv[p] != MOVE_NONE; p++) - ss->pv[p] = pss->pv[p] = (ss+1)->pv[p]; + *dst = *pdst = ss->currentMove; - ss->pv[p] = pss->pv[p] = MOVE_NONE; + do + *++dst = *++pdst = *src; + while (*src++ != MOVE_NONE); } @@ -2249,7 +2253,7 @@ namespace { if (i < 3) { - ss->init(i); + ss->init(); ss->initKillers(); } }