X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=45e0888d5efbfb58493075fb0b1c6699615046f6;hp=8e6efb7a1bd9bdc50e041194f9a8c97b35fade5f;hb=c97104e8540b72ee2c6c9c13d3773d2c0f9ec32f;hpb=8ee3124487bdfd871f587bdb46f007ff24fc8303 diff --git a/src/search.cpp b/src/search.cpp index 8e6efb7a..45e0888d 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; @@ -114,9 +133,6 @@ namespace { // when the static evaluation is at most IIDMargin below beta. const Value IIDMargin = Value(0x100); - // Use easy moves? - const bool UseEasyMove = true; - // Easy move margin. An easy move candidate must be at least this much // better than the second best move. const Value EasyMoveMargin = Value(0x200); @@ -146,13 +162,14 @@ namespace { bool UseQSearchFutilityPruning = true; bool UseFutilityPruning = true; - // Margins for futility pruning in the quiescence search, at frontier - // nodes, and at pre-frontier nodes - Value FutilityMargin0 = Value(0x80); - Value FutilityMargin1 = Value(0x100); - Value FutilityMargin2 = Value(0x300); + // Margins for futility pruning in the quiescence search, and at frontier + // and near frontier nodes + Value FutilityMarginQS = Value(0x80); + Value FutilityMargins[6] = { Value(0x100), Value(0x200), Value(0x250), + Value(0x2A0), Value(0x340), Value(0x3A0) }; // Razoring + const bool RazorAtDepthOne = false; Depth RazorDepth = 4*OnePly; Value RazorMargin = Value(0x300); @@ -177,9 +194,10 @@ 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]; @@ -247,6 +265,7 @@ namespace { void update_pv(SearchStack ss[], int ply); void sp_update_pv(SearchStack *pss, SearchStack ss[], int ply); bool connected_moves(const Position &pos, Move m1, Move m2); + bool value_is_mate(Value value); bool move_is_killer(Move m, const SearchStack& ss); 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); @@ -397,9 +416,10 @@ void think(const Position &pos, bool infinite, bool ponder, int side_to_move, UseQSearchFutilityPruning = get_option_value_bool("Futility Pruning (Quiescence Search)"); UseFutilityPruning = get_option_value_bool("Futility Pruning (Main Search)"); - FutilityMargin0 = value_from_centipawns(get_option_value_int("Futility Margin 0")); - FutilityMargin1 = value_from_centipawns(get_option_value_int("Futility Margin 1")); - FutilityMargin2 = value_from_centipawns(get_option_value_int("Futility Margin 2")); + FutilityMarginQS = value_from_centipawns(get_option_value_int("Futility Margin (Quiescence Search)")); + int fmScale = get_option_value_int("Futility Margin Scale Factor (Main Search)"); + for (int i = 0; i < 6; i++) + FutilityMargins[i] = (FutilityMargins[i] * fmScale) / 100; RazorDepth = (get_option_value_int("Maximum Razoring Depth") + 1) * OnePly; RazorMargin = value_from_centipawns(get_option_value_int("Razoring Margin")); @@ -429,7 +449,6 @@ void think(const Position &pos, bool infinite, bool ponder, int side_to_move, // Set thinking time: int myTime = time[side_to_move]; int myIncrement = increment[side_to_move]; - int oppTime = time[1 - side_to_move]; if (!movesToGo) // Sudden death time control { @@ -729,6 +748,12 @@ 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 @@ -768,6 +793,9 @@ 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); @@ -823,6 +851,11 @@ 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) @@ -905,16 +938,17 @@ namespace { assert(ply >= 0 && ply < PLY_MAX); assert(threadID >= 0 && threadID < ActiveThreads); - // Initialize, and make an early exit in case of an aborted search, - // an instant draw, maximum ply reached, etc. - if (AbortSearch || thread_should_stop(threadID)) - return Value(0); - if (depth < OnePly) return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID); + // Initialize, and make an early exit in case of an aborted search, + // an instant draw, maximum ply reached, etc. init_node(pos, ss, ply, threadID); + // After init_node() that calls poll() + if (AbortSearch || thread_should_stop(threadID)) + return Value(0); + if (pos.is_draw()) return VALUE_DRAW; @@ -968,9 +1002,8 @@ namespace { movesSearched[moveCount++] = ss[ply].currentMove = move; if (moveIsCapture) - ss[ply].currentMoveCaptureValue = pos.midgame_value_of_piece_on(move_to(move)); - else if (move_is_ep(move)) - ss[ply].currentMoveCaptureValue = PawnValueMidgame; + ss[ply].currentMoveCaptureValue = + move_is_ep(move)? PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move)); else ss[ply].currentMoveCaptureValue = Value(0); @@ -1003,7 +1036,7 @@ namespace { else value = alpha + 1; // Just to trigger next condition - if (value > alpha) // Go with full depth pv search + if (value > alpha) // Go with full depth non-pv search { ss[ply].reduction = Depth(0); value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID); @@ -1041,7 +1074,9 @@ namespace { // If we are at ply 1, and we are searching the first root move at // ply 0, set the 'Problem' variable if the score has dropped a lot // (from the computer's point of view) since the previous iteration: - if (Iteration >= 2 && -value <= ValueByIteration[Iteration-1] - ProblemMargin) + if ( ply == 1 + && Iteration >= 2 + && -value <= ValueByIteration[Iteration-1] - ProblemMargin) Problem = true; } @@ -1073,6 +1108,7 @@ 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 { @@ -1097,21 +1133,22 @@ namespace { assert(ply >= 0 && ply < PLY_MAX); assert(threadID >= 0 && threadID < ActiveThreads); - EvalInfo ei; + if (depth < OnePly) + return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); // Initialize, and make an early exit in case of an aborted search, // an instant draw, maximum ply reached, etc. + init_node(pos, ss, ply, threadID); + + // After init_node() that calls poll() if (AbortSearch || thread_should_stop(threadID)) return Value(0); - if (depth < OnePly) - return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); - - init_node(pos, ss, ply, threadID); - if (pos.is_draw()) return VALUE_DRAW; + EvalInfo ei; + if (ply >= PLY_MAX - 1) return evaluate(pos, ei, threadID); @@ -1141,6 +1178,7 @@ namespace { if ( allowNullmove && depth > OnePly && !isCheck + && !value_is_mate(beta) && ok_to_do_nullmove(pos) && approximateEval >= beta - NullMoveMargin) { @@ -1148,16 +1186,17 @@ 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. + // is above beta then mark the node as a suspicious failed low. We will verify + // later if we are really under threat. if ( UseNullDrivenIID && nullValue < beta && depth > 6 * OnePly + &&!value_is_mate(nullValue) && ttMove == MOVE_NONE && ss[ply + 1].currentMove != MOVE_NONE && pos.move_is_capture(ss[ply + 1].currentMove) @@ -1166,7 +1205,11 @@ namespace { pos.undo_null_move(u); - if (nullValue >= beta) + if (value_is_mate(nullValue)) + { + /* Do not return unproven mates */ + } + else if (nullValue >= beta) { if (depth < 6 * OnePly) return beta; @@ -1195,11 +1238,17 @@ namespace { } } // Null move search not allowed, try razoring - else if ( (approximateEval < beta - RazorMargin && depth < RazorDepth) - ||(approximateEval < beta - PawnValueMidgame && depth <= OnePly)) + else if ( !value_is_mate(beta) + && approximateEval < beta - RazorMargin + && depth < RazorDepth + && (RazorAtDepthOne || depth > OnePly) + && ttMove == MOVE_NONE + && !pos.has_pawn_on_7th(pos.side_to_move())) { Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); - if (v < beta) + if ( (v < beta - RazorMargin - RazorMargin / 4) + || (depth < 3*OnePly && v < beta - RazorMargin) + || (depth < 2*OnePly && v < beta - RazorMargin / 2)) return v; } @@ -1214,7 +1263,9 @@ namespace { { // 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. + // and this position should fail high. So do a normal search with a + // reduced depth to get a good ttMove to use in the following full + // depth search. Move tm = ss[ply].threatMove; assert(tm != MOVE_NONE); @@ -1263,15 +1314,18 @@ namespace { && !moveIsCapture && !move_promotion(move)) { + // History pruning. See ok_to_prune() definition if ( moveCount >= 2 + int(depth) && ok_to_prune(pos, move, ss[ply].threatMove, depth)) continue; - if (depth < 3 * OnePly && approximateEval < beta) + // Value based pruning + if (depth < 7 * OnePly && approximateEval < beta) { if (futilityValue == VALUE_NONE) futilityValue = evaluate(pos, ei, threadID) - + (depth < 2 * OnePly ? FutilityMargin1 : FutilityMargin2); + + FutilityMargins[int(depth)/2 - 1] + + 32 * (depth & 1); if (futilityValue < beta) { @@ -1349,6 +1403,7 @@ 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 { @@ -1374,15 +1429,14 @@ namespace { assert(ply >= 0 && ply < PLY_MAX); assert(threadID >= 0 && threadID < ActiveThreads); - EvalInfo ei; - // Initialize, and make an early exit in case of an aborted search, // an instant draw, maximum ply reached, etc. + init_node(pos, ss, ply, threadID); + + // After init_node() that calls poll() if (AbortSearch || thread_should_stop(threadID)) return Value(0); - init_node(pos, ss, ply, threadID); - if (pos.is_draw()) return VALUE_DRAW; @@ -1392,14 +1446,16 @@ namespace { return value_from_tt(tte->value(), ply); // Evaluate the position statically - Value staticValue = evaluate(pos, ei, threadID); + EvalInfo ei; + bool isCheck = pos.is_check(); + Value staticValue = (isCheck ? -VALUE_INFINITE : evaluate(pos, ei, threadID)); if (ply == PLY_MAX - 1) - return staticValue; + return evaluate(pos, ei, threadID); // Initialize "stand pat score", and return it immediately if it is // at least beta. - Value bestValue = (pos.is_check() ? -VALUE_INFINITE : staticValue); + Value bestValue = staticValue; if (bestValue >= beta) return bestValue; @@ -1410,12 +1466,11 @@ namespace { // 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) will be generated. - MovePicker mp = MovePicker(pos, false, MOVE_NONE, EmptySearchStack, depth, &ei); + bool pvNode = (beta - alpha != 1); + MovePicker mp = MovePicker(pos, pvNode, MOVE_NONE, EmptySearchStack, depth, isCheck ? NULL : &ei); Move move; int moveCount = 0; Bitboard dcCandidates = mp.discovered_check_candidates(); - bool isCheck = pos.is_check(); - bool pvNode = (beta - alpha != 1); bool enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame; // Loop through the moves until no moves remain or a beta cutoff @@ -1440,7 +1495,8 @@ namespace { Value futilityValue = staticValue + Max(pos.midgame_value_of_piece_on(move_to(move)), pos.endgame_value_of_piece_on(move_to(move))) - + FutilityMargin0 + + (move_is_ep(move) ? PawnValueEndgame : Value(0)) + + FutilityMarginQS + ei.futilityMargin; if (futilityValue < alpha) @@ -1643,8 +1699,11 @@ namespace { assert(move_is_ok(move)); - ss[sp->ply].currentMoveCaptureValue = move_is_ep(move)? - PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move)); + if (moveIsCapture) + ss[sp->ply].currentMoveCaptureValue = + move_is_ep(move)? PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move)); + else + ss[sp->ply].currentMoveCaptureValue = Value(0); lock_grab(&(sp->lock)); int moveCount = ++sp->moves; @@ -1725,8 +1784,10 @@ namespace { } // If we are at ply 1, and we are searching the first root move at // ply 0, set the 'Problem' variable if the score has dropped a lot - // (from the computer's point of view) since the previous iteration: - if (Iteration >= 2 && -value <= ValueByIteration[Iteration-1] - ProblemMargin) + // (from the computer's point of view) since the previous iteration. + if ( sp->ply == 1 + && Iteration >= 2 + && -value <= ValueByIteration[Iteration-1] - ProblemMargin) Problem = true; } lock_release(&(sp->lock)); @@ -1735,7 +1796,7 @@ namespace { lock_grab(&(sp->lock)); // If this is the master thread and we have been asked to stop because of - // a beta cutoff higher up in the tree, stop all slave threads: + // a beta cutoff higher up in the tree, stop all slave threads. if (sp->master == threadID && thread_should_stop(threadID)) for (int i = 0; i < ActiveThreads; i++) if (sp->slaves[i]) @@ -1747,6 +1808,32 @@ 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 @@ -1766,7 +1853,7 @@ namespace { if (score != m.score) return (score < m.score); - return nodes <= m.nodes; + return theirBeta <= m.theirBeta; } /// The RootMoveList class @@ -1829,6 +1916,11 @@ 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++) @@ -2053,6 +2145,18 @@ namespace { } + // value_is_mate() checks if the given value is a mate one + // eventually compensated for the ply. + + bool value_is_mate(Value value) { + + assert(abs(value) <= VALUE_INFINITE); + + return value <= value_mated_in(PLY_MAX) + || value >= value_mate_in(PLY_MAX); + } + + // move_is_killer() checks if the given move is among the // killer moves of that ply. @@ -2077,6 +2181,8 @@ namespace { Depth extension(const Position &pos, Move m, bool pvNode, bool check, bool singleReply, bool mateThreat, bool* dangerous) { + assert(m != MOVE_NONE); + Depth result = Depth(0); *dangerous = check || singleReply || mateThreat; @@ -2089,21 +2195,26 @@ namespace { if (mateThreat) result += MateThreatExtension[pvNode]; - if (pos.move_is_pawn_push_to_7th(m)) + if (pos.type_of_piece_on(move_from(m)) == PAWN) { - result += PawnPushTo7thExtension[pvNode]; - *dangerous = true; - } - if (pos.move_is_passed_pawn_push(m)) - { - result += PassedPawnExtension[pvNode]; - *dangerous = true; + 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]; + *dangerous = true; + } } - if ( pos.midgame_value_of_piece_on(move_to(m)) >= RookValueMidgame + if ( pos.move_is_capture(m) + && pos.type_of_piece_on(move_to(m)) != PAWN && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) - pos.midgame_value_of_piece_on(move_to(m)) == Value(0)) - && !move_promotion(m)) + && !move_promotion(m) + && !move_is_ep(m)) { result += PawnEndgameExtension[pvNode]; *dangerous = true; @@ -2169,7 +2280,7 @@ namespace { // value of the threatening piece, don't prune move which defend it. if ( !PruneDefendingMoves && threat != MOVE_NONE - && pos.type_of_piece_on(tto) != NO_PIECE_TYPE + && pos.move_is_capture(threat) && ( 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)) @@ -2184,7 +2295,8 @@ namespace { if ( !PruneBlockingMoves && threat != MOVE_NONE && piece_is_slider(pos.piece_on(tfrom)) - && bit_is_set(squares_between(tfrom, tto), mto) && pos.see(m) >= 0) + && bit_is_set(squares_between(tfrom, tto), mto) + && pos.see(m) >= 0) return false; return true;