X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=ab3e6f66cdcf9d7988c4dd7e167216bc90b90751;hp=bc66ebad15751eefb3b037ea9f446e455f11b4ef;hb=4c294932e7b4a6ee3604f0c176dd01124524456f;hpb=20a2ca366f81d61cc0043cc68f4109f6f70c2716 diff --git a/src/search.cpp b/src/search.cpp index bc66ebad..ab3e6f66 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -47,6 +47,23 @@ namespace { /// Types + // The BetaCounterType class is used to order moves at ply one. + // Apart for the first one that has its score, following moves + // normally have score -VALUE_INFINITE, so are ordered according + // to the number of beta cutoffs occurred under their subtree during + // the last iteration. + + struct BetaCounterType { + + BetaCounterType(); + void clear(); + void add(Color us, Depth d, int threadID); + void read(Color us, int64_t& our, int64_t& their); + + int64_t hits[THREAD_MAX][2]; + }; + + // The RootMove class 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). @@ -60,6 +77,7 @@ namespace { Value score; int64_t nodes, cumulativeNodes; Move pv[PLY_MAX_PLUS_2]; + int64_t ourBeta, theirBeta; }; @@ -74,6 +92,7 @@ namespace { inline Value get_move_score(int moveNum) const; inline void set_move_score(int moveNum, Value score); inline void set_move_nodes(int moveNum, int64_t nodes); + inline void set_beta_counters(int moveNum, int64_t our, int64_t their); void set_move_pv(int moveNum, const Move pv[]); inline Move get_move_pv(int moveNum, int i) const; inline int64_t get_move_cumulative_nodes(int moveNum) const; @@ -106,6 +125,9 @@ namespace { const bool UseIIDAtPVNodes = true; const bool UseIIDAtNonPVNodes = false; + // Use null move driven internal iterative deepening? + bool UseNullDrivenIID = false; + // Internal iterative deepening margin. At Non-PV moves, when // UseIIDAtNonPVNodes is true, we do an internal iterative deepening search // when the static evaluation is at most IIDMargin below beta. @@ -174,9 +196,10 @@ namespace { int NodesSincePoll; int NodesBetweenPolls = 30000; - // Iteration counter + // Iteration counters int Iteration; bool LastIterations; + BetaCounterType BetaCounter; // Scores and number of times the best move changed for each iteration: Value ValueByIteration[PLY_MAX_PLUS_2]; @@ -188,7 +211,7 @@ namespace { // Time managment variables int SearchStartTime; int MaxNodes, MaxDepth; - int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime, TimeAdvantage; + int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime; Move BestRootMove, PonderMove, EasyMove; int RootMoveNumber; bool InfiniteSearch; @@ -390,6 +413,7 @@ void think(const Position &pos, bool infinite, bool ponder, int side_to_move, if (UseLogFile) LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app); + UseNullDrivenIID = get_option_value_bool("Null driven IID"); UseQSearchFutilityPruning = get_option_value_bool("Futility Pruning (Quiescence Search)"); UseFutilityPruning = get_option_value_bool("Futility Pruning (Main Search)"); @@ -427,8 +451,6 @@ void think(const Position &pos, bool infinite, bool ponder, int side_to_move, int myIncrement = increment[side_to_move]; int oppTime = time[1 - side_to_move]; - TimeAdvantage = myTime - oppTime; - if (!movesToGo) // Sudden death time control { if (myIncrement) @@ -680,10 +702,6 @@ namespace { ExtraSearchTime = BestMoveChangesByIteration[Iteration] * (MaxSearchTime / 2) + BestMoveChangesByIteration[Iteration-1] * (MaxSearchTime / 3); - // If we need some more and we are in time advantage take it - if (ExtraSearchTime > 0 && TimeAdvantage > 2 * MaxSearchTime) - ExtraSearchTime += MaxSearchTime / 2; - // Try to guess if the current iteration is the last one or the last two LastIterations = (current_search_time() > ((MaxSearchTime + ExtraSearchTime)*58) / 128); @@ -731,6 +749,12 @@ namespace { if (UseLogFile) { + if (dbg_show_mean) + dbg_print_mean(LogFile); + + if (dbg_show_hit_rate) + dbg_print_hit_rate(LogFile); + UndoInfo u; LogFile << "Nodes: " << nodes_searched() << std::endl << "Nodes/second: " << nps() << std::endl @@ -770,6 +794,9 @@ namespace { // are used to sort the root moves at the next iteration. nodes = nodes_searched(); + // Reset beta cut-off counters + BetaCounter.clear(); + // Pick the next root move, and print the move and the move number to // the standard output. move = ss[0].currentMove = rml.get_move(i); @@ -825,6 +852,11 @@ namespace { // sort the root moves at the next iteration. rml.set_move_nodes(i, nodes_searched() - nodes); + // Remember the beta-cutoff statistics + int64_t our, their; + BetaCounter.read(pos.side_to_move(), our, their); + rml.set_beta_counters(i, our, their); + assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE); if (value <= alpha && i >= MultiPV) @@ -1075,6 +1107,7 @@ namespace { else if (bestValue >= beta) { + BetaCounter.add(pos.side_to_move(), depth, threadID); Move m = ss[ply].pv[ply]; if (ok_to_history(pos, m)) // Only non capture moves are considered { @@ -1130,16 +1163,18 @@ namespace { if (tte && ok_to_use_TT(tte, depth, beta, ply)) { - ss[ply].currentMove = ttMove; // can be MOVE_NONE ? + ss[ply].currentMove = ttMove; // can be MOVE_NONE return value_from_tt(tte->value(), ply); } Value approximateEval = quick_evaluate(pos); bool mateThreat = false; + bool nullDrivenIID = false; bool isCheck = pos.is_check(); // Null move search if ( allowNullmove + && depth > OnePly && !isCheck && ok_to_do_nullmove(pos) && approximateEval >= beta - NullMoveMargin) @@ -1148,8 +1183,22 @@ namespace { UndoInfo u; pos.do_null_move(u); - int R = (depth > 7 ? 4 : 3); + int R = (depth >= 4 * OnePly ? 4 : 3); // Null move dynamic reduction + Value nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID); + + // Check for a null capture artifact, if the value without the null capture + // is above beta then there is a good possibility that this is a cut-node. + // We will do an IID later to find a ttMove. + if ( UseNullDrivenIID + && nullValue < beta + && depth > 6 * OnePly + && ttMove == MOVE_NONE + && ss[ply + 1].currentMove != MOVE_NONE + && pos.move_is_capture(ss[ply + 1].currentMove) + && pos.see(ss[ply + 1].currentMove) + nullValue >= beta) + nullDrivenIID = true; + pos.undo_null_move(u); if (nullValue >= beta) @@ -1163,14 +1212,16 @@ namespace { return beta; } else { // The null move failed low, which means that we may be faced with - // some kind of threat. If the previous move was reduced, check if + // some kind of threat. If the previous move was reduced, check if // the move that refuted the null move was somehow connected to the - // move which was reduced. If a connection is found, return a fail + // move which was reduced. If a connection is found, return a fail // low score (which will cause the reduced move to fail high in the // parent node, which will trigger a re-search with full depth). if (nullValue == value_mated_in(ply + 2)) + { mateThreat = true; - + nullDrivenIID = false; + } ss[ply].threatMove = ss[ply + 1].currentMove; if ( depth < ThreatDepth && ss[ply - 1].reduction @@ -1194,6 +1245,20 @@ namespace { search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID); ttMove = ss[ply].pv[ply]; } + else if (nullDrivenIID) + { + // The null move failed low due to a suspicious capture. Perhaps we + // are facing a null capture artifact due to the side to move change + // and this is a cut-node. So it's a good time to search for a ttMove. + Move tm = ss[ply].threatMove; + + assert(tm != MOVE_NONE); + assert(ttMove == MOVE_NONE); + + search(pos, ss, beta, depth/2, ply, false, threadID); + ttMove = ss[ply].pv[ply]; + ss[ply].threatMove = tm; + } // Initialize a MovePicker object for the current position, and prepare // to search all moves: @@ -1319,6 +1384,7 @@ namespace { TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE, VALUE_TYPE_UPPER); else { + BetaCounter.add(pos.side_to_move(), depth, threadID); Move m = ss[ply].pv[ply]; if (ok_to_history(pos, m)) // Only non capture moves are considered { @@ -1717,6 +1783,32 @@ namespace { lock_release(&(sp->lock)); } + /// The BetaCounterType class + + BetaCounterType::BetaCounterType() { clear(); } + + void BetaCounterType::clear() { + + for (int i = 0; i < THREAD_MAX; i++) + hits[i][WHITE] = hits[i][BLACK] = 0ULL; + } + + void BetaCounterType::add(Color us, Depth d, int threadID) { + + // Weighted count based on depth + hits[threadID][us] += int(d); + } + + void BetaCounterType::read(Color us, int64_t& our, int64_t& their) { + + our = their = 0UL; + for (int i = 0; i < THREAD_MAX; i++) + { + our += hits[i][us]; + their += hits[i][opposite_color(us)]; + } + } + /// The RootMove class @@ -1736,7 +1828,7 @@ namespace { if (score != m.score) return (score < m.score); - return nodes <= m.nodes; + return theirBeta <= m.theirBeta; } /// The RootMoveList class @@ -1799,6 +1891,11 @@ namespace { moves[moveNum].cumulativeNodes += nodes; } + inline void RootMoveList::set_beta_counters(int moveNum, int64_t our, int64_t their) { + moves[moveNum].ourBeta = our; + moves[moveNum].theirBeta = their; + } + void RootMoveList::set_move_pv(int moveNum, const Move pv[]) { int j; for(j = 0; pv[j] != MOVE_NONE; j++) @@ -2128,31 +2225,34 @@ namespace { tto = move_to(threat); // Case 1: Castling moves are never pruned. - if(move_is_castle(m)) - return false; + if (move_is_castle(m)) + return false; // Case 2: Don't prune moves which move the threatened piece - if(!PruneEscapeMoves && threat != MOVE_NONE && mfrom == tto) - return false; + if (!PruneEscapeMoves && threat != MOVE_NONE && mfrom == tto) + return false; // Case 3: If the threatened piece has value less than or equal to the // value of the threatening piece, don't prune move which defend it. - if(!PruneDefendingMoves && threat != MOVE_NONE - && (piece_value_midgame(pos.piece_on(tfrom)) - >= piece_value_midgame(pos.piece_on(tto))) - && pos.move_attacks_square(m, tto)) + if ( !PruneDefendingMoves + && threat != MOVE_NONE + && pos.type_of_piece_on(tto) != NO_PIECE_TYPE + && ( pos.midgame_value_of_piece_on(tfrom) >= pos.midgame_value_of_piece_on(tto) + || pos.type_of_piece_on(tfrom) == KING) + && pos.move_attacks_square(m, tto)) return false; // Case 4: Don't prune moves with good history. - if(!H.ok_to_prune(pos.piece_on(move_from(m)), m, d)) - return false; + if (!H.ok_to_prune(pos.piece_on(move_from(m)), m, d)) + return false; // Case 5: If the moving piece in the threatened move is a slider, don't // prune safe moves which block its ray. - if(!PruneBlockingMoves && threat != MOVE_NONE - && piece_is_slider(pos.piece_on(tfrom)) - && bit_is_set(squares_between(tfrom, tto), mto) && pos.see(m) >= 0) - return false; + if ( !PruneBlockingMoves + && threat != MOVE_NONE + && piece_is_slider(pos.piece_on(tfrom)) + && bit_is_set(squares_between(tfrom, tto), mto) && pos.see(m) >= 0) + return false; return true; }