X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=8410f73bbf8ee8ad49f45f1e1777cb200e745759;hp=5cdc01698f2425462fdb7ff8929fb29d55c7dcbd;hb=a67c22611aea4b643e8278fa6007da316bd06b13;hpb=ad1167c482bdda850a83c28d3938553d813e46b9 diff --git a/src/search.cpp b/src/search.cpp index 5cdc0169..8410f73b 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -52,9 +52,6 @@ using namespace Search; namespace { - // Set to true to force running with one thread. Used for debugging - const bool FakeSplit = false; - // Different node types, used as template parameter enum NodeType { Root, PV, NonPV }; @@ -76,7 +73,7 @@ namespace { return (Depth) Reductions[PvNode][i][std::min(int(d) / ONE_PLY, 63)][std::min(mn, 63)]; } - size_t MultiPV, PVIdx; + size_t PVIdx; TimeManager TimeMgr; double BestMoveChanges; Value DrawValue[COLOR_NB]; @@ -97,18 +94,21 @@ namespace { string uci_pv(const Position& pos, int depth, Value alpha, Value beta); struct Skill { - Skill(int l) : level(l), best(MOVE_NONE) {} + Skill(int l, size_t rootSize) : level(l), + candidates(l < 20 ? std::min(4, (int)rootSize) : 0), + best(MOVE_NONE) {} ~Skill() { - if (enabled()) // Swap best PV line with the sub-optimal one + if (candidates) // Swap best PV line with the sub-optimal one std::swap(RootMoves[0], *std::find(RootMoves.begin(), RootMoves.end(), best ? best : pick_move())); } - bool enabled() const { return level < 20; } + size_t candidates_size() const { return candidates; } bool time_to_pick(int depth) const { return depth == 1 + level; } Move pick_move(); int level; + size_t candidates; Move best; }; @@ -152,26 +152,33 @@ void Search::init() { /// Search::perft() is our utility to verify move generation. All the leaf nodes /// up to the given depth are generated and counted and the sum returned. - -static uint64_t perft(Position& pos, Depth depth) { +template +uint64_t Search::perft(Position& pos, Depth depth) { StateInfo st; - uint64_t cnt = 0; + uint64_t cnt, nodes = 0; CheckInfo ci(pos); const bool leaf = depth == 2 * ONE_PLY; for (MoveList it(pos); *it; ++it) { - pos.do_move(*it, st, ci, pos.gives_check(*it, ci)); - cnt += leaf ? MoveList(pos).size() : ::perft(pos, depth - ONE_PLY); - pos.undo_move(*it); + if (Root && depth <= ONE_PLY) + cnt = 1; + else + { + pos.do_move(*it, st, ci, pos.gives_check(*it, ci)); + cnt = leaf ? MoveList(pos).size() : perft(pos, depth - ONE_PLY); + nodes += cnt; + pos.undo_move(*it); + } + if (Root) + sync_cout << move_to_uci(*it, pos.is_chess960()) << ": " << cnt << sync_endl; } - return cnt; + return nodes; } -uint64_t Search::perft(Position& pos, Depth depth) { - return depth > ONE_PLY ? ::perft(pos, depth) : MoveList(pos).size(); -} +template uint64_t Search::perft(Position& pos, Depth depth); + /// Search::think() is the external interface to Stockfish's search, and is /// called by the main thread when the program receives the UCI 'go' command. It @@ -282,15 +289,12 @@ namespace { Countermoves.clear(); Followupmoves.clear(); - MultiPV = Options["MultiPV"]; - Skill skill(Options["Skill Level"]); + size_t multiPV = Options["MultiPV"]; + Skill skill(Options["Skill Level"], RootMoves.size()); // Do we have to play with skill handicap? In this case enable MultiPV search // that we will use behind the scenes to retrieve a set of possible moves. - if (skill.enabled() && MultiPV < 4) - MultiPV = 4; - - MultiPV = std::min(MultiPV, RootMoves.size()); + multiPV = std::max(multiPV, skill.candidates_size()); // Iterative deepening loop until requested to stop or target depth reached while (++depth <= MAX_PLY && !Signals.stop && (!Limits.depth || depth <= Limits.depth)) @@ -304,7 +308,7 @@ namespace { RootMoves[i].prevScore = RootMoves[i].score; // MultiPV loop. We perform a full root search for each PV line - for (PVIdx = 0; PVIdx < MultiPV && !Signals.stop; ++PVIdx) + for (PVIdx = 0; PVIdx < std::min(multiPV, RootMoves.size()) && !Signals.stop; ++PVIdx) { // Reset aspiration window starting size if (depth >= 5) @@ -361,7 +365,7 @@ namespace { else break; - delta += delta / 2; + delta += 3 * delta / 8; assert(alpha >= -VALUE_INFINITE && beta <= VALUE_INFINITE); } @@ -369,12 +373,12 @@ namespace { // Sort the PV lines searched so far and update the GUI std::stable_sort(RootMoves.begin(), RootMoves.begin() + PVIdx + 1); - if (PVIdx + 1 == MultiPV || Time::now() - SearchTime > 3000) + if (PVIdx + 1 == std::min(multiPV, RootMoves.size()) || Time::now() - SearchTime > 3000) sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl; } // If skill levels are enabled and time is up, pick a sub-optimal best move - if (skill.enabled() && skill.time_to_pick(depth)) + if (skill.candidates_size() && skill.time_to_pick(depth)) skill.pick_move(); if (Options["Write Search Log"]) @@ -398,7 +402,7 @@ namespace { if (Limits.use_time_management() && !Signals.stop && !Signals.stopOnPonderhit) { // Take some extra time if the best move has changed - if (depth > 4 && depth < 50 && MultiPV == 1) + if (depth > 4 && multiPV == 1) TimeMgr.pv_instability(BestMoveChanges); // Stop the search if only one legal move is available or all @@ -566,7 +570,6 @@ namespace { && depth < 4 * ONE_PLY && eval + razor_margin(depth) <= alpha && ttMove == MOVE_NONE - && abs(beta) < VALUE_MATE_IN_MAX_PLY && !pos.pawn_on_7th(pos.side_to_move())) { if ( depth <= ONE_PLY @@ -594,7 +597,6 @@ namespace { && !ss->skipNullMove && depth >= 2 * ONE_PLY && eval >= beta - && abs(beta) < VALUE_MATE_IN_MAX_PLY && pos.non_pawn_material(pos.side_to_move())) { ss->currentMove = MOVE_NULL; @@ -604,7 +606,8 @@ namespace { // Null move dynamic reduction based on depth and value Depth R = 3 * ONE_PLY + depth / 4 - + int(eval - beta) / PawnValueMg * ONE_PLY; + + (abs(beta) < VALUE_KNOWN_WIN ? int(eval - beta) / PawnValueMg * ONE_PLY + : DEPTH_ZERO); pos.do_null_move(st); (ss+1)->skipNullMove = true; @@ -619,7 +622,7 @@ namespace { if (nullValue >= VALUE_MATE_IN_MAX_PLY) nullValue = beta; - if (depth < 12 * ONE_PLY) + if (depth < 12 * ONE_PLY && abs(beta) < VALUE_KNOWN_WIN) return nullValue; // Do verification search at high depths @@ -699,7 +702,10 @@ moves_loop: // When in check and at SpNode search starts from here singularExtensionNode = !RootNode && !SpNode && depth >= 8 * ONE_PLY + && abs(beta) < VALUE_KNOWN_WIN && ttMove != MOVE_NONE + /* && ttValue != VALUE_NONE Already implicit in the next condition */ + && abs(ttValue) < VALUE_KNOWN_WIN && !excludedMove // Recursive singular search is not allowed && (tte->bound() & BOUND_LOWER) && tte->depth() >= depth - 3 * ONE_PLY; @@ -764,11 +770,8 @@ moves_loop: // When in check and at SpNode search starts from here if ( singularExtensionNode && move == ttMove && !ext - && pos.legal(move, ci.pinned) - && abs(ttValue) < VALUE_KNOWN_WIN) + && pos.legal(move, ci.pinned)) { - assert(ttValue != VALUE_NONE); - Value rBeta = ttValue - int(depth); ss->excludedMove = move; ss->skipNullMove = true; @@ -988,8 +991,8 @@ moves_loop: // When in check and at SpNode search starts from here { assert(bestValue > -VALUE_INFINITE && bestValue < beta); - thisThread->split(pos, ss, alpha, beta, &bestValue, &bestMove, - depth, moveCount, &mp, NT, cutNode); + thisThread->split(pos, ss, alpha, beta, &bestValue, &bestMove, + depth, moveCount, &mp, NT, cutNode); if (Signals.stop || thisThread->cutoff_occurred()) return VALUE_ZERO; @@ -1296,8 +1299,8 @@ moves_loop: // When in check and at SpNode search starts from here } - // When playing with a strength handicap, choose best move among the MultiPV - // set using a statistical rule dependent on 'level'. Idea by Heinz van Saanen. + // When playing with a strength handicap, choose best move among the first 'candidates' + // RootMoves using a statistical rule dependent on 'level'. Idea by Heinz van Saanen. Move Skill::pick_move() { @@ -1308,7 +1311,7 @@ moves_loop: // When in check and at SpNode search starts from here rk.rand(); // RootMoves are already sorted by score in descending order - int variance = std::min(RootMoves[0].score - RootMoves[MultiPV - 1].score, PawnValueMg); + int variance = std::min(RootMoves[0].score - RootMoves[candidates - 1].score, PawnValueMg); int weakness = 120 - 2 * level; int max_s = -VALUE_INFINITE; best = MOVE_NONE; @@ -1316,12 +1319,12 @@ moves_loop: // When in check and at SpNode search starts from here // Choose best move. For each move score we add two terms both dependent on // weakness. One deterministic and bigger for weaker moves, and one random, // then we choose the move with the resulting highest score. - for (size_t i = 0; i < MultiPV; ++i) + for (size_t i = 0; i < candidates; ++i) { int s = RootMoves[i].score; // Don't allow crazy blunders even at very low skills - if (i > 0 && RootMoves[i-1].score > s + 2 * PawnValueMg) + if (i > 0 && RootMoves[i - 1].score > s + 2 * PawnValueMg) break; // This is our magic formula