X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fsearch.cpp;h=5a12ec7e672419aca09d0ec78d742eaa3d8d8c28;hb=452f0d16966e0ec48385442362c94a810feaacd9;hp=7f885f7a3337d9904d9cc24b2fda2fbb49b5a0ca;hpb=c51e12200a70ba91433181819ac5321f55c49f70;p=stockfish diff --git a/src/search.cpp b/src/search.cpp index 7f885f7a..5a12ec7e 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -90,7 +90,7 @@ namespace { 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); + Depth depth, bool mateThreat, int* moveCount, MovePicker* mp, bool pvNode); private: friend void poll(); @@ -285,10 +285,10 @@ namespace { Value root_search(Position& pos, SearchStack* ss, RootMoveList& rml, Value* alphaPtr, Value* betaPtr); template - Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID); + Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth); 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); template void sp_search(SplitPoint* sp, int threadID); @@ -313,7 +313,7 @@ namespace { void poll(); void ponderhit(); void wait_for_stop_or_ponderhit(); - void init_ss_array(SearchStack* ss); + void init_ss_array(SearchStack* ss, int size); void print_pv_info(const Position& pos, SearchStack* ss, Value alpha, Value beta, Value value); #if !defined(_MSC_VER) @@ -603,7 +603,7 @@ namespace { Value id_loop(const Position& pos, Move searchMoves[]) { - Position p(pos); + Position p(pos, pos.thread()); SearchStack ss[PLY_MAX_PLUS_2]; Move EasyMove = MOVE_NONE; Value value, alpha = -VALUE_INFINITE, beta = VALUE_INFINITE; @@ -633,7 +633,7 @@ namespace { // Initialize TT.new_search(); H.clear(); - init_ss_array(ss); + init_ss_array(ss, PLY_MAX_PLUS_2); ValueByIteration[1] = rml.get_move_score(0); p.reset_ply(); Iteration = 1; @@ -811,7 +811,7 @@ 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 +876,7 @@ 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, 0); + value = -search(pos, ss+1, -beta, -alpha, newDepth); } else { @@ -892,23 +892,37 @@ 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, 0); + 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, 0); + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth); // 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, 0); + value = -search(pos, ss+1, -beta, -alpha, newDepth); } } @@ -1031,13 +1045,13 @@ 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, int threadID) { + Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) { 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(pos.thread() >= 0 && pos.thread() < TM.active_threads()); Move movesSearched[256]; EvalInfo ei; @@ -1051,6 +1065,7 @@ namespace { bool isCheck, singleEvasion, moveIsCheck, captureOrPromotion, dangerous; bool mateThreat = false; int moveCount = 0; + int threadID = pos.thread(); int ply = pos.ply(); refinedValue = bestValue = value = -VALUE_INFINITE; oldAlpha = alpha; @@ -1058,8 +1073,6 @@ namespace { // Step 1. Initialize node and poll. Polling can abort search TM.incrementNodeCounter(threadID); ss->init(ply); - (ss + 1)->excludedMove = MOVE_NONE; - (ss + 1)->skipNullMove = false; (ss + 2)->initKillers(); if (threadID == 0 && ++NodesSincePoll > NodesBetweenPolls) @@ -1119,7 +1132,7 @@ 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); @@ -1136,7 +1149,7 @@ namespace { && !pos.has_pawn_on_7th(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)); if (v < rbeta) // Logically we should return (v + razor_margin(depth)), but // surprisingly this did slightly weaker in tests. @@ -1177,14 +1190,11 @@ 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, threadID); - + nullValue = depth-R*OnePly < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0)) + : - search(pos, ss+1, -beta, -alpha, depth-R*OnePly); (ss+1)->skipNullMove = false; - pos.undo_null_move(); if (nullValue >= beta) @@ -1198,10 +1208,10 @@ namespace { return nullValue; ss->skipNullMove = true; - Value v = search(pos, ss, alpha, beta, depth-5*OnePly, threadID); + Value v = search(pos, ss, alpha, beta, depth-5*OnePly); ss->skipNullMove = false; - if (v >= beta) + if (v >= beta) return nullValue; } else @@ -1231,7 +1241,7 @@ namespace { Depth d = (PvNode ? depth - 2 * OnePly : depth / 2); ss->skipNullMove = true; - search(pos, ss, alpha, beta, d, threadID); + search(pos, ss, alpha, beta, d); ss->skipNullMove = false; ttMove = ss->pv[ply]; @@ -1283,7 +1293,7 @@ namespace { Value b = ttValue - SingularExtensionMargin; ss->excludedMove = move; ss->skipNullMove = true; - Value v = search(pos, ss, b - 1, b, depth / 2, threadID); + Value v = search(pos, ss, b - 1, b, depth / 2); ss->skipNullMove = false; ss->excludedMove = MOVE_NONE; @@ -1332,8 +1342,8 @@ 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, threadID); + value = newDepth < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0)) + : - search(pos, ss+1, -beta, -alpha, newDepth); else { // Step 14. Reduced depth search @@ -1350,8 +1360,8 @@ 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, threadID); + value = d < OnePly ? -qsearch(pos, ss+1, -(alpha+1), -alpha, Depth(0)) + : - search(pos, ss+1, -(alpha+1), -alpha, d); doFullDepthSearch = (value > alpha); } @@ -1364,7 +1374,7 @@ namespace { assert(newDepth - OnePly >= OnePly); ss->reduction = OnePly; - value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, threadID); + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction); doFullDepthSearch = (value > alpha); } ss->reduction = Depth(0); // Restore original reduction @@ -1373,15 +1383,15 @@ 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, threadID); + value = newDepth < OnePly ? -qsearch(pos, ss+1, -(alpha+1), -alpha, Depth(0)) + : - search(pos, ss+1, -(alpha+1), -alpha, newDepth); // Step extra. pv search (only in PV nodes) // Search only for possible new PV nodes, if instead value >= beta then // parent node fails low with value <= alpha and tries another move. if (PvNode && value > alpha && value < beta) - value = newDepth < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), threadID) - : - search(pos, ss+1, -beta, -alpha, newDepth, threadID); + value = newDepth < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0)) + : - search(pos, ss+1, -beta, -alpha, newDepth); } } @@ -1415,7 +1425,7 @@ namespace { && !TM.thread_should_stop(threadID) && Iteration <= 99) TM.split(pos, ss, &alpha, beta, &bestValue, depth, - mateThreat, &moveCount, &mp, threadID, PvNode); + mateThreat, &moveCount, &mp, PvNode); } // Step 19. Check for mate and stalemate @@ -1459,27 +1469,27 @@ 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) { 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(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; + int ply = pos.ply(); - TM.incrementNodeCounter(threadID); - ss->init(ply); + TM.incrementNodeCounter(pos.thread()); + ss->pv[ply] = ss->pv[ply + 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) @@ -1500,39 +1510,42 @@ 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; - update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval); - } + 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); - // Initialize "stand pat score", and return it immediately if it is - // at least beta. - bestValue = staticValue; + ss->eval = bestValue; + update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval); - 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()]); + // Stand pat. Return immediately if static value is at least beta + if (bestValue >= beta) + { + if (!tte) // FIXME, remove condition + 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, @@ -1540,8 +1553,6 @@ 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 @@ -1551,16 +1562,12 @@ 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)) { @@ -1591,9 +1598,12 @@ 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); pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); @@ -1612,17 +1622,13 @@ namespace { // 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]; @@ -1664,7 +1670,7 @@ 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; @@ -1741,8 +1747,8 @@ namespace { { 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, threadID); + value = d < OnePly ? -qsearch(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0)) + : - search(pos, ss+1, -(localAlpha+1), -localAlpha, d); doFullDepthSearch = (value > localAlpha); } @@ -1755,7 +1761,7 @@ namespace { ss->reduction = OnePly; Value localAlpha = sp->alpha; - value = -search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, threadID); + value = -search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction); doFullDepthSearch = (value > localAlpha); } ss->reduction = Depth(0); // Restore original reduction @@ -1765,15 +1771,15 @@ namespace { if (doFullDepthSearch) { 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, threadID); + value = newDepth < OnePly ? -qsearch(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0)) + : - search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth); // Step extra. pv search (only in PV nodes) // Search only for possible new PV nodes, if instead value >= beta then // parent node fails low with value <= alpha and tries another move. if (PvNode && value > 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, threadID); + value = newDepth < OnePly ? -qsearch(pos, ss+1, -sp->beta, -sp->alpha, Depth(0)) + : - search(pos, ss+1, -sp->beta, -sp->alpha, newDepth); } // Step 16. Undo move @@ -2235,16 +2241,21 @@ 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(i); + ss->initKillers(); + } } } @@ -2618,16 +2629,18 @@ namespace { 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) { + MovePicker* mp, bool pvNode) { assert(p.is_ok()); 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 @@ -2776,10 +2789,10 @@ 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)); moves[count].pv[0] = cur->move; moves[count].pv[1] = MOVE_NONE; pos.undo_move(cur->move);