X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;ds=sidebyside;f=src%2Fsearch.cpp;h=276f2e6cc55f4af50ba938e008d4be7703886a19;hb=12eb27b6e92165c71ea93897d9068b0ca3c28081;hp=83d052bbeb54c5bb656c053913ab2f8ceb782e65;hpb=201e8d5f87a2bbd2d199b744cf8e92213c1e4bc4;p=stockfish diff --git a/src/search.cpp b/src/search.cpp index 83d052bb..276f2e6c 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -84,7 +84,7 @@ namespace { void read_uci_options(); bool available_thread_exists(int master) const; bool thread_is_available(int slave, int master) const; - bool thread_should_stop(int threadID) const; + bool cutoff_at_splitpoint(int threadID) const; void wake_sleeping_thread(int threadID); void idle_loop(int threadID, SplitPoint* sp); @@ -104,26 +104,28 @@ namespace { }; - // RootMove struct is used for moves at the root at the tree. For each - // root move, we store a score, a node count, and a PV (really a refutation - // in the case of moves which fail low). + // RootMove struct is used for moves at the root at the tree. For each root + // move, we store two scores, a node count, and a PV (really a refutation + // in the case of moves which fail low). Value pvScore is normally set at + // -VALUE_INFINITE for all non-pv moves, while nonPvScore is computed + // according to the order in which moves are returned by MovePicker. struct RootMove { - RootMove() : mp_score(0), nodes(0) {} + RootMove() : nodes(0) { pvScore = nonPvScore = -VALUE_INFINITE; } // RootMove::operator<() is the comparison function used when // sorting the moves. A move m1 is considered to be better - // than a move m2 if it has a higher score, or if the moves - // have equal score but m1 has the higher beta cut-off count. + // than a move m2 if it has an higher pvScore, or if it has + // equal pvScore but m1 has the higher nonPvScore. In this way + // we are guaranteed that PV moves are always sorted as first. bool operator<(const RootMove& m) const { - - return score != m.score ? score < m.score : mp_score <= m.mp_score; + return pvScore != m.pvScore ? pvScore < m.pvScore : nonPvScore <= m.nonPvScore; } Move move; - Value score; - int mp_score; + Value pvScore; + Value nonPvScore; int64_t nodes; Move pv[PLY_MAX_PLUS_2]; }; @@ -139,14 +141,14 @@ namespace { Move move(int moveNum) const { return moves[moveNum].move; } Move move_pv(int moveNum, int i) const { return moves[moveNum].pv[i]; } - int move_count() const { return count; } - Value move_score(int moveNum) const { return moves[moveNum].score; } - int64_t move_nodes(int moveNum) const { return moves[moveNum].nodes; } - void add_move_nodes(int moveNum, int64_t nodes) { moves[moveNum].nodes += nodes; } - void set_move_score(int moveNum, Value score) { moves[moveNum].score = score; } - - void set_move_pv(int moveNum, const Move pv[]); - void score_moves(const Position& pos); + int size() const { return count; } + Value pv_score(int moveNum) const { return moves[moveNum].pvScore; } + int64_t nodes(int moveNum) const { return moves[moveNum].nodes; } + void add_nodes(int moveNum, int64_t n) { moves[moveNum].nodes += n; } + void set_pv_score(int moveNum, Value v) { moves[moveNum].pvScore = v; } + + void set_pv(int moveNum, const Move pv[]); + void set_non_pv_scores(const Position& pos); void sort(); void sort_multipv(int n); @@ -527,7 +529,7 @@ namespace { RootMoveList rml(pos, searchMoves); // Handle special case of searching on a mate/stale position - if (rml.move_count() == 0) + if (rml.size() == 0) { if (PonderSearch) wait_for_stop_or_ponderhit(); @@ -540,7 +542,7 @@ namespace { cout << set960(pos.is_chess960()) // Is enough to set once at the beginning << "info depth " << 1 << "\ninfo depth " << 1 - << " score " << value_to_uci(rml.move_score(0)) + << " score " << value_to_uci(rml.pv_score(0)) << " time " << current_search_time() << " nodes " << pos.nodes_searched() << " nps " << nps(pos) @@ -551,12 +553,12 @@ namespace { H.clear(); init_ss_array(ss, PLY_MAX_PLUS_2); pv[0] = pv[1] = MOVE_NONE; - ValueByIteration[1] = rml.move_score(0); + ValueByIteration[1] = rml.pv_score(0); Iteration = 1; // Is one move significantly better than others after initial scoring ? - if ( rml.move_count() == 1 - || rml.move_score(0) > rml.move_score(1) + EasyMoveMargin) + if ( rml.size() == 1 + || rml.pv_score(0) > rml.pv_score(1) + EasyMoveMargin) EasyMove = rml.move(0); // Iterative deepening loop @@ -605,7 +607,7 @@ namespace { // Stop search early if there is only a single legal move, // we search up to Iteration 6 anyway to get a proper score. - if (Iteration >= 6 && rml.move_count() == 1) + if (Iteration >= 6 && rml.size() == 1) stopSearch = true; // Stop search early when the last two iterations returned a mate score @@ -617,9 +619,9 @@ namespace { // Stop search early if one move seems to be much better than the others if ( Iteration >= 8 && EasyMove == pv[0] - && ( ( rml.move_nodes(0) > (pos.nodes_searched() * 85) / 100 + && ( ( rml.nodes(0) > (pos.nodes_searched() * 85) / 100 && current_search_time() > TimeMgr.available_time() / 16) - ||( rml.move_nodes(0) > (pos.nodes_searched() * 98) / 100 + ||( rml.nodes(0) > (pos.nodes_searched() * 98) / 100 && current_search_time() > TimeMgr.available_time() / 32))) stopSearch = true; @@ -691,7 +693,7 @@ namespace { << move_to_san(pos, pv[1]) // Works also with MOVE_NONE << endl; } - return rml.move_score(0); + return rml.pv_score(0); } @@ -740,11 +742,11 @@ namespace { while (1) { // Sort the moves before to (re)search - rml.score_moves(pos); + rml.set_non_pv_scores(pos); rml.sort(); // Step 10. Loop through all moves in the root move list - for (int i = 0; i < rml.move_count() && !AbortSearch; i++) + for (int i = 0; i < rml.size() && !AbortSearch; i++) { // This is used by time management FirstRootMove = (i == 0); @@ -772,7 +774,7 @@ namespace { // Step extra. Fail high loop // If move fails high, we research with bigger window until we are not failing // high anymore. - value = - VALUE_INFINITE; + value = -VALUE_INFINITE; while (1) { @@ -848,10 +850,10 @@ 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); + rml.set_pv_score(i, value); ss->bestMove = move; extract_pv_from_tt(pos, move, pv); - rml.set_move_pv(i, pv); + rml.set_pv(i, pv); // Print information to the standard output print_pv_info(pos, pv, alpha, beta, value); @@ -871,23 +873,23 @@ namespace { break; // Remember searched nodes counts for this move - rml.add_move_nodes(i, pos.nodes_searched() - nodes); + rml.add_nodes(i, pos.nodes_searched() - nodes); assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE); assert(value < beta); // Step 17. Check for new best move if (value <= alpha && i >= MultiPV) - rml.set_move_score(i, -VALUE_INFINITE); + rml.set_pv_score(i, -VALUE_INFINITE); else { // PV move or new best move! // Update PV - rml.set_move_score(i, value); + rml.set_pv_score(i, value); ss->bestMove = move; extract_pv_from_tt(pos, move, pv); - rml.set_move_pv(i, pv); + rml.set_pv(i, pv); if (MultiPV == 1) { @@ -907,10 +909,10 @@ namespace { else // MultiPV > 1 { rml.sort_multipv(i); - for (int j = 0; j < Min(MultiPV, rml.move_count()); j++) + for (int j = 0; j < Min(MultiPV, rml.size()); j++) { cout << "info multipv " << j + 1 - << " score " << value_to_uci(rml.move_score(j)) + << " score " << value_to_uci(rml.pv_score(j)) << " depth " << (j <= i ? Iteration : Iteration - 1) << " time " << current_search_time() << " nodes " << pos.nodes_searched() @@ -922,7 +924,7 @@ namespace { cout << endl; } - alpha = rml.move_score(Min(i, MultiPV - 1)); + alpha = rml.pv_score(Min(i, MultiPV - 1)); } } // PV move or new best move @@ -993,7 +995,8 @@ namespace { threatMove = sp->threatMove; mateThreat = sp->mateThreat; goto split_point_start; - } else {} // Hack to fix icc's "statement is unreachable" warning + } + else {} // Hack to fix icc's "statement is unreachable" warning // Step 1. Initialize node and poll. Polling can abort search ss->currentMove = ss->bestMove = threatMove = MOVE_NONE; @@ -1006,8 +1009,10 @@ namespace { } // Step 2. Check for aborted search and immediate draw - if ( AbortSearch || ThreadsMgr.thread_should_stop(threadID) - || pos.is_draw() || ply >= PLY_MAX - 1) + if ( AbortSearch + || ThreadsMgr.cutoff_at_splitpoint(threadID) + || pos.is_draw() + || ply >= PLY_MAX - 1) return VALUE_DRAW; // Step 3. Mate distance pruning @@ -1145,6 +1150,7 @@ namespace { threatMove = (ss+1)->bestMove; if ( depth < ThreatDepth && (ss-1)->reduction + && threatMove != MOVE_NONE && connected_moves(pos, (ss-1)->currentMove, threatMove)) return beta - 1; } @@ -1196,7 +1202,7 @@ split_point_start: // At split points actual search starts from here // Loop through all legal moves until no moves remain or a beta cutoff occurs while ( bestValue < beta && (move = mp.get_next_move()) != MOVE_NONE - && !ThreadsMgr.thread_should_stop(threadID)) + && !ThreadsMgr.cutoff_at_splitpoint(threadID)) { assert(move_is_ok(move)); @@ -1284,7 +1290,7 @@ split_point_start: // At split points actual search starts from here continue; } - // Prune neg. see moves at low depths + // Prune moves with negative SEE at low depths if ( predictedDepth < 2 * ONE_PLY && bestValue > value_mated_in(PLY_MAX) && pos.see_sign(move) < 0) @@ -1301,7 +1307,7 @@ split_point_start: // At split points actual search starts from here // Step extra. pv search (only in PV nodes) // The first move in list is the expected PV - if (!SpNode && PvNode && moveCount == 1) + if (PvNode && moveCount == 1) value = -search(pos, ss+1, -beta, -alpha, newDepth, ply+1); else { @@ -1313,9 +1319,11 @@ split_point_start: // At split points actual search starts from here && !captureOrPromotion && !dangerous && !move_is_castle(move) - && !(ss->killers[0] == move || ss->killers[1] == move)) + && ss->killers[0] != move + && ss->killers[1] != move) { ss->reduction = reduction(depth, moveCount); + if (ss->reduction) { alpha = SpNode ? sp->alpha : alpha; @@ -1367,7 +1375,7 @@ split_point_start: // At split points actual search starts from here alpha = sp->alpha; } - if (value > bestValue && !(SpNode && ThreadsMgr.thread_should_stop(threadID))) + if (value > bestValue && !(SpNode && ThreadsMgr.cutoff_at_splitpoint(threadID))) { bestValue = value; @@ -1376,15 +1384,15 @@ split_point_start: // At split points actual search starts from here if (value > alpha) { - if (SpNode && (!PvNode || value >= beta)) - sp->stopRequest = true; - if (PvNode && value < beta) // We want always alpha < beta { alpha = value; + if (SpNode) sp->alpha = value; } + else if (SpNode) + sp->betaCutoff = true; if (value == value_mate_in(ply + 1)) ss->mateKiller = move; @@ -1403,7 +1411,7 @@ split_point_start: // At split points actual search starts from here && bestValue < beta && ThreadsMgr.available_thread_exists(threadID) && !AbortSearch - && !ThreadsMgr.thread_should_stop(threadID) + && !ThreadsMgr.cutoff_at_splitpoint(threadID) && Iteration <= 99) ThreadsMgr.split(pos, ss, ply, &alpha, beta, &bestValue, depth, threatMove, mateThreat, moveCount, &mp, PvNode); @@ -1419,7 +1427,7 @@ split_point_start: // At split points actual search starts from here // Step 20. Update tables // If the search is not aborted, update the transposition table, // history counters, and killer moves. - if (!SpNode && !AbortSearch && !ThreadsMgr.thread_should_stop(threadID)) + if (!SpNode && !AbortSearch && !ThreadsMgr.cutoff_at_splitpoint(threadID)) { move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove; vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER @@ -1468,6 +1476,7 @@ split_point_start: // At split points actual search starts from here Value bestValue, value, evalMargin, futilityValue, futilityBase; bool isCheck, enoughMaterial, moveIsCheck, evasionPrunable; const TTEntry* tte; + Depth ttDepth; Value oldAlpha = alpha; ss->bestMove = ss->currentMove = MOVE_NONE; @@ -1476,21 +1485,18 @@ split_point_start: // At split points actual search starts from here if (pos.is_draw() || ply >= PLY_MAX - 1) return VALUE_DRAW; - // Decide whether or not to include checks + // Decide whether or not to include checks, this fixes also the type of + // TT entry depth that we are going to use. Note that in qsearch we use + // only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS. isCheck = pos.is_check(); - - Depth d; - if (isCheck || depth >= -ONE_PLY) - d = DEPTH_ZERO; - else - d = DEPTH_ZERO - ONE_PLY; + ttDepth = (isCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS); // Transposition table lookup. At PV nodes, we don't use the TT for // pruning, but only for move ordering. tte = TT.retrieve(pos.get_key()); ttMove = (tte ? tte->move() : MOVE_NONE); - if (!PvNode && tte && ok_to_use_TT(tte, d, beta, ply)) + if (!PvNode && tte && ok_to_use_TT(tte, ttDepth, beta, ply)) { ss->bestMove = ttMove; // Can be MOVE_NONE return value_from_tt(tte->value(), ply); @@ -1536,9 +1542,9 @@ split_point_start: // At split points actual search starts from here // Initialize a MovePicker object for the current position, and prepare // to search the moves. Because the depth is <= 0 here, only captures, - // queen promotions and checks (only if depth == 0 or depth == -ONE_PLY - // and we are near beta) will be generated. - MovePicker mp = MovePicker(pos, ttMove, d, H); + // queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will + // be generated. + MovePicker mp(pos, ttMove, depth, H); CheckInfo ci(pos); // Loop through the moves until no moves remain or a beta cutoff occurs @@ -1628,7 +1634,7 @@ split_point_start: // At split points actual search starts from here // Update transposition table ValueType vt = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT); - TT.store(pos.get_key(), value_to_tt(bestValue, ply), vt, d, ss->bestMove, ss->eval, evalMargin); + TT.store(pos.get_key(), value_to_tt(bestValue, ply), vt, ttDepth, ss->bestMove, ss->eval, evalMargin); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1704,11 +1710,8 @@ split_point_start: // At split points actual search starts from here Square f1, t1, f2, t2; Piece p; - assert(move_is_ok(m1)); - assert(move_is_ok(m2)); - - if (m2 == MOVE_NONE) - return false; + assert(m1 && move_is_ok(m1)); + assert(m2 && move_is_ok(m2)); // Case 1: The moving piece is the same in both moves f2 = move_from(m2); @@ -2467,17 +2470,17 @@ split_point_start: // At split points actual search starts from here } - // thread_should_stop() checks whether the thread should stop its search. - // This can happen if a beta cutoff has occurred in the thread's currently - // active split point, or in some ancestor of the current split point. + // cutoff_at_splitpoint() checks whether a beta cutoff has occurred in + // the thread's currently active split point, or in some ancestor of + // the current split point. - bool ThreadsManager::thread_should_stop(int threadID) const { + bool ThreadsManager::cutoff_at_splitpoint(int threadID) const { assert(threadID >= 0 && threadID < activeThreads); SplitPoint* sp = threads[threadID].splitPoint; - for ( ; sp && !sp->stopRequest; sp = sp->parent) {} + for ( ; sp && !sp->betaCutoff; sp = sp->parent) {} return sp != NULL; } @@ -2576,7 +2579,7 @@ split_point_start: // At split points actual search starts from here // Initialize the split point object splitPoint.parent = masterThread.splitPoint; splitPoint.master = master; - splitPoint.stopRequest = false; + splitPoint.betaCutoff = false; splitPoint.ply = ply; splitPoint.depth = depth; splitPoint.threatMove = threatMove; @@ -2696,7 +2699,7 @@ split_point_start: // At split points actual search starts from here moves[count].move = ss[0].currentMove = moves[count].pv[0] = cur->move; moves[count].pv[1] = MOVE_NONE; pos.do_move(cur->move, st); - moves[count].score = -qsearch(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, DEPTH_ZERO, 1); + moves[count].pvScore = -qsearch(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, DEPTH_ZERO, 1); pos.undo_move(cur->move); count++; } @@ -2705,25 +2708,27 @@ split_point_start: // At split points actual search starts from here // Score root moves using the standard way used in main search, the moves // are scored according to the order in which are returned by MovePicker. + // This is the second order score that is used to compare the moves when + // the first order pv scores of both moves are equal. - void RootMoveList::score_moves(const Position& pos) + void RootMoveList::set_non_pv_scores(const Position& pos) { Move move; - int score = 1000; - MovePicker mp = MovePicker(pos, MOVE_NONE, ONE_PLY, H); + Value score = VALUE_ZERO; + MovePicker mp(pos, MOVE_NONE, ONE_PLY, H); while ((move = mp.get_next_move()) != MOVE_NONE) for (int i = 0; i < count; i++) if (moves[i].move == move) { - moves[i].mp_score = score--; + moves[i].nonPvScore = score--; break; } } // RootMoveList simple methods definitions - void RootMoveList::set_move_pv(int moveNum, const Move pv[]) { + void RootMoveList::set_pv(int moveNum, const Move pv[]) { int j;