X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=ab3e6f66cdcf9d7988c4dd7e167216bc90b90751;hp=c463ec393e42c98ed54880fc533f4fe0370b4210;hb=4c294932e7b4a6ee3604f0c176dd01124524456f;hpb=1d525bb45fcfb7f456a9bc9a02d402fa1dd80db1 diff --git a/src/search.cpp b/src/search.cpp index c463ec39..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; @@ -245,7 +268,7 @@ namespace { void sp_update_pv(SearchStack *pss, SearchStack ss[], int ply); bool connected_moves(const Position &pos, Move m1, Move m2); bool move_is_killer(Move m, const SearchStack& ss); - Depth extension(const Position &pos, Move m, bool pvNode, bool check, bool singleReply, bool mateThreat); + Depth extension(const Position &pos, Move m, bool pvNode, bool check, bool singleReply, bool mateThreat, bool* dangerous); bool ok_to_do_nullmove(const Position &pos); bool ok_to_prune(const Position &pos, Move m, Move threat, Depth d); bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply); @@ -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)"); @@ -427,16 +451,14 @@ 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 (increment) + if (myIncrement) { MaxSearchTime = myTime / 30 + myIncrement; AbsoluteMaxSearchTime = Max(myTime / 4, myIncrement - 100); } else { // Blitz game without increment - MaxSearchTime = myTime / 40; + MaxSearchTime = myTime / 30; AbsoluteMaxSearchTime = myTime / 8; } } @@ -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); @@ -778,7 +805,8 @@ namespace { << " currmovenumber " << i + 1 << std::endl; // Decide search depth for this move - ext = extension(pos, move, true, pos.move_is_check(move), false, false); + bool dangerous; + ext = extension(pos, move, true, pos.move_is_check(move), false, false, &dangerous); newDepth = (Iteration - 2) * OnePly + ext + InitialDepth; // Make the move, and search it @@ -824,6 +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) @@ -952,8 +985,7 @@ namespace { Value value, bestValue = -VALUE_INFINITE; Bitboard dcCandidates = mp.discovered_check_candidates(); bool isCheck = pos.is_check(); - bool mateThreat = MateThreatExtension[1] > Depth(0) - && pos.has_mate_threat(opposite_color(pos.side_to_move())); + bool mateThreat = pos.has_mate_threat(opposite_color(pos.side_to_move())); // Loop through all legal moves until no moves remain or a beta cutoff // occurs. @@ -966,7 +998,6 @@ namespace { bool singleReply = (isCheck && mp.number_of_moves() == 1); bool moveIsCheck = pos.move_is_check(move, dcCandidates); bool moveIsCapture = pos.move_is_capture(move); - bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move); movesSearched[moveCount++] = ss[ply].currentMove = move; @@ -978,7 +1009,8 @@ namespace { ss[ply].currentMoveCaptureValue = Value(0); // Decide the new search depth - Depth ext = extension(pos, move, true, moveIsCheck, singleReply, mateThreat); + bool dangerous; + Depth ext = extension(pos, move, true, moveIsCheck, singleReply, mateThreat, &dangerous); Depth newDepth = depth - OnePly + ext; // Make and search the move @@ -992,11 +1024,10 @@ namespace { // Try to reduce non-pv search depth by one ply if move seems not problematic, // if the move fails high will be re-searched at full depth. if ( depth >= 2*OnePly - && ext == Depth(0) && moveCount >= LMRPVMoves + && !dangerous && !moveIsCapture && !move_promotion(move) - && !moveIsPassedPawnPush && !move_is_castle(move) && !move_is_killer(move, ss[ply])) { @@ -1076,6 +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 { @@ -1131,16 +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) @@ -1149,8 +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) @@ -1164,14 +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 @@ -1195,6 +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: @@ -1220,19 +1284,18 @@ namespace { bool singleReply = (isCheck && mp.number_of_moves() == 1); bool moveIsCheck = pos.move_is_check(move, dcCandidates); bool moveIsCapture = pos.move_is_capture(move); - bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move); movesSearched[moveCount++] = ss[ply].currentMove = move; // Decide the new search depth - Depth ext = extension(pos, move, false, moveIsCheck, singleReply, mateThreat); + bool dangerous; + Depth ext = extension(pos, move, false, moveIsCheck, singleReply, mateThreat, &dangerous); Depth newDepth = depth - OnePly + ext; // Futility pruning if ( useFutilityPruning - && ext == Depth(0) + && !dangerous && !moveIsCapture - && !moveIsPassedPawnPush && !move_promotion(move)) { if ( moveCount >= 2 + int(depth) @@ -1260,12 +1323,11 @@ namespace { // Try to reduce non-pv search depth by one ply if move seems not problematic, // if the move fails high will be re-searched at full depth. - if ( depth >= 2*OnePly - && ext == Depth(0) - && moveCount >= LMRNonPVMoves + if ( depth >= 2*OnePly + && moveCount >= LMRNonPVMoves + && !dangerous && !moveIsCapture && !move_promotion(move) - && !moveIsPassedPawnPush && !move_is_castle(move) && !move_is_killer(move, ss[ply])) { @@ -1322,6 +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 { @@ -1398,20 +1461,17 @@ namespace { { assert(move_is_ok(move)); - bool moveIsCheck = pos.move_is_check(move, dcCandidates); - bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move); - moveCount++; ss[ply].currentMove = move; // Futility pruning if ( UseQSearchFutilityPruning + && enoughMaterial && !isCheck - && !moveIsCheck - && !move_promotion(move) - && !moveIsPassedPawnPush && !pvNode - && enoughMaterial) + && !move_promotion(move) + && !pos.move_is_check(move, dcCandidates) + && !pos.move_is_passed_pawn_push(move)) { Value futilityValue = staticValue + Max(pos.midgame_value_of_piece_on(move_to(move)), @@ -1506,7 +1566,6 @@ namespace { bool moveIsCheck = pos.move_is_check(move, sp->dcCandidates); bool moveIsCapture = pos.move_is_capture(move); - bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move); lock_grab(&(sp->lock)); int moveCount = ++sp->moves; @@ -1515,14 +1574,14 @@ namespace { ss[sp->ply].currentMove = move; // Decide the new search depth. - Depth ext = extension(pos, move, false, moveIsCheck, false, false); + bool dangerous; + Depth ext = extension(pos, move, false, moveIsCheck, false, false, &dangerous); Depth newDepth = sp->depth - OnePly + ext; // Prune? if ( useFutilityPruning - && ext == Depth(0) + && !dangerous && !moveIsCapture - && !moveIsPassedPawnPush && !move_promotion(move) && moveCount >= 2 + int(sp->depth) && ok_to_prune(pos, move, ss[sp->ply].threatMove, sp->depth)) @@ -1534,10 +1593,9 @@ namespace { // Try to reduce non-pv search depth by one ply if move seems not problematic, // if the move fails high will be re-searched at full depth. - if ( ext == Depth(0) + if ( !dangerous && moveCount >= LMRNonPVMoves && !moveIsCapture - && !moveIsPassedPawnPush && !move_promotion(move) && !move_is_castle(move) && !move_is_killer(move, ss[sp->ply])) @@ -1618,7 +1676,6 @@ namespace { { bool moveIsCheck = pos.move_is_check(move, sp->dcCandidates); bool moveIsCapture = pos.move_is_capture(move); - bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move); assert(move_is_ok(move)); @@ -1632,7 +1689,8 @@ namespace { ss[sp->ply].currentMove = move; // Decide the new search depth. - Depth ext = extension(pos, move, true, moveIsCheck, false, false); + bool dangerous; + Depth ext = extension(pos, move, true, moveIsCheck, false, false, &dangerous); Depth newDepth = sp->depth - OnePly + ext; // Make and search the move. @@ -1641,10 +1699,9 @@ namespace { // Try to reduce non-pv search depth by one ply if move seems not problematic, // if the move fails high will be re-searched at full depth. - if ( ext == Depth(0) + if ( !dangerous && moveCount >= LMRPVMoves && !moveIsCapture - && !moveIsPassedPawnPush && !move_promotion(move) && !move_is_castle(move) && !move_is_killer(move, ss[sp->ply])) @@ -1726,6 +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 @@ -1745,7 +1828,7 @@ namespace { if (score != m.score) return (score < m.score); - return nodes <= m.nodes; + return theirBeta <= m.theirBeta; } /// The RootMoveList class @@ -1808,6 +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++) @@ -1923,7 +2011,6 @@ namespace { NodesSincePoll = 0; } } - ss[ply].pv[ply] = ss[ply].pv[ply+1] = ss[ply].currentMove = MOVE_NONE; ss[ply+2].mateKiller = MOVE_NONE; ss[ply].threatMove = MOVE_NONE; @@ -2049,12 +2136,16 @@ namespace { // extension() decides whether a move should be searched with normal depth, // or with extended depth. Certain classes of moves (checking moves, in - // particular) are searched with bigger depth than ordinary moves. + // particular) are searched with bigger depth than ordinary moves and in + // any case are marked as 'dangerous'. Note that also if a move is not + // extended, as example because the corresponding UCI option is set to zero, + // the move is marked as 'dangerous' so, at least, we avoid to prune it. - Depth extension(const Position &pos, Move m, bool pvNode, - bool check, bool singleReply, bool mateThreat) { + Depth extension(const Position &pos, Move m, bool pvNode, bool check, + bool singleReply, bool mateThreat, bool* dangerous) { Depth result = Depth(0); + *dangerous = check || singleReply || mateThreat; if (check) result += CheckExtension[pvNode]; @@ -2062,26 +2153,37 @@ namespace { if (singleReply) result += SingleReplyExtension[pvNode]; + if (mateThreat) + result += MateThreatExtension[pvNode]; + if (pos.move_is_pawn_push_to_7th(m)) + { result += PawnPushTo7thExtension[pvNode]; - + *dangerous = true; + } if (pos.move_is_passed_pawn_push(m)) + { result += PassedPawnExtension[pvNode]; - - if (mateThreat) - result += MateThreatExtension[pvNode]; + *dangerous = true; + } if ( pos.midgame_value_of_piece_on(move_to(m)) >= RookValueMidgame && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) - pos.midgame_value_of_piece_on(move_to(m)) == Value(0)) && !move_promotion(m)) + { result += PawnEndgameExtension[pvNode]; + *dangerous = true; + } if ( pvNode && pos.move_is_capture(m) && pos.type_of_piece_on(move_to(m)) != PAWN && pos.see(m) >= 0) + { result += OnePly/2; + *dangerous = true; + } return Min(result, OnePly); } @@ -2123,31 +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; }