X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=a3d8781889a690e15e0b91c4044c0243245f90d1;hp=eeca97389fad2bf6b63a2a1436a0c18069f9148d;hb=189b6fc270f91f4111c1a8049c97455093f8be97;hpb=6008f6538e9c3912c88e89d77ef3e3d3351a6e55 diff --git a/src/search.cpp b/src/search.cpp index eeca9738..a3d87818 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -55,6 +55,9 @@ namespace { // Set to true to force running with one thread. Used for debugging const bool FakeSplit = false; + // This is the minimum interval in msec between two check_time() calls + const int TimerResolution = 5; + // Different node types, used as template parameter enum NodeType { Root, PV, NonPV, SplitPointRoot, SplitPointPV, SplitPointNonPV }; @@ -62,28 +65,9 @@ namespace { const bool Slidings[18] = { 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1 }; inline bool piece_is_slider(Piece p) { return Slidings[p]; } - // Maximum depth for razoring - const Depth RazorDepth = 4 * ONE_PLY; - // Dynamic razoring margin based on depth inline Value razor_margin(Depth d) { return Value(512 + 16 * int(d)); } - // Maximum depth for use of dynamic threat detection when null move fails low - const Depth ThreatDepth = 5 * ONE_PLY; - - // Minimum depth for use of internal iterative deepening - const Depth IIDDepth[] = { 8 * ONE_PLY, 5 * ONE_PLY }; - - // At Non-PV nodes we do an internal iterative deepening search - // when the static evaluation is bigger then beta - IIDMargin. - const Value IIDMargin = Value(256); - - // Minimum depth for use of singular extension - const Depth SingularExtensionDepth[] = { 8 * ONE_PLY, 6 * ONE_PLY }; - - // Futility margin for quiescence search - const Value FutilityMarginQS = Value(128); - // Futility lookup tables (initialized at startup) and their access functions Value FutilityMargins[16][64]; // [depth][moveNumber] int FutilityMoveCounts[32]; // [depth] @@ -94,11 +78,6 @@ namespace { : 2 * VALUE_INFINITE; } - inline int futility_move_count(Depth d) { - - return d < 16 * ONE_PLY ? FutilityMoveCounts[d] : MAX_MOVES; - } - // Reduction lookup tables (initialized at startup) and their access function int8_t Reductions[2][64][64]; // [pv][depth][moveNumber] @@ -107,14 +86,6 @@ namespace { return (Depth) Reductions[PvNode][std::min(int(d) / ONE_PLY, 63)][std::min(mn, 63)]; } - // Easy move margin. An easy move candidate must be at least this much better - // than the second best move. - const Value EasyMoveMargin = Value(0x150); - - // This is the minimum interval in msec between two check_time() calls - const int TimerResolution = 5; - - size_t MultiPV, UCIMultiPV, PVIdx; TimeManager TimeMgr; int BestMoveChanges; @@ -122,7 +93,6 @@ namespace { bool SkillLevelEnabled, Chess960; History H; - template Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth); @@ -134,36 +104,11 @@ namespace { bool connected_moves(const Position& pos, Move m1, Move m2); Value value_to_tt(Value v, int ply); Value value_from_tt(Value v, int ply); - bool can_return_tt(const TTEntry* tte, Depth depth, Value ttValue, Value beta); bool connected_threat(const Position& pos, Move m, Move threat); Value refine_eval(const TTEntry* tte, Value ttValue, Value defaultEval); Move do_skill_level(); string uci_pv(const Position& pos, int depth, Value alpha, Value beta); - // is_dangerous() checks whether a move belongs to some classes of known - // 'dangerous' moves so that we avoid to prune it. - FORCE_INLINE bool is_dangerous(const Position& pos, Move m, bool captureOrPromotion) { - - // Castle move? - if (type_of(m) == CASTLE) - return true; - - // Passed pawn move? - if ( type_of(pos.piece_moved(m)) == PAWN - && pos.pawn_is_passed(pos.side_to_move(), to_sq(m))) - return true; - - // Entering a pawn endgame? - if ( captureOrPromotion - && type_of(pos.piece_on(to_sq(m))) != PAWN - && type_of(m) == NORMAL - && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) - - PieceValue[Mg][pos.piece_on(to_sq(m))] == VALUE_ZERO)) - return true; - - return false; - } - } // namespace @@ -224,11 +169,14 @@ size_t Search::perft(Position& pos, Depth depth) { void Search::think() { - static Book book; // Defined static to initialize the PRNG only once + static PolyglotBook book; // Defined static to initialize the PRNG only once Position& pos = RootPosition; Chess960 = pos.is_chess960(); Eval::RootColor = pos.side_to_move(); + int scaledCF = Eval::ContemptFactor * MaterialTable::game_phase(pos) / PHASE_MIDGAME; + Eval::ValueDraw[ Eval::RootColor] = VALUE_DRAW - Value(scaledCF); + Eval::ValueDraw[~Eval::RootColor] = VALUE_DRAW + Value(scaledCF); TimeMgr.init(Limits, pos.startpos_ply_counter(), pos.side_to_move()); TT.new_search(); H.clear(); @@ -279,6 +227,8 @@ void Search::think() { // used to check for remaining available thinking time. if (Limits.use_time_management()) Threads.set_timer(std::min(100, std::max(TimeMgr.available_time() / 16, TimerResolution))); + else if (Limits.nodes) + Threads.set_timer(2 * TimerResolution); else Threads.set_timer(100); @@ -467,7 +417,7 @@ namespace { && ( (bestMoveNeverChanged && pos.captured_piece_type()) || Time::now() - SearchTime > (TimeMgr.available_time() * 40) / 100)) { - Value rBeta = bestValue - EasyMoveMargin; + Value rBeta = bestValue - 2 * PawnValueMg; (ss+1)->excludedMove = RootMoves[0].pv[0]; (ss+1)->skipNullMove = true; Value v = search(pos, ss+1, rBeta - 1, rBeta, (depth - 3) * ONE_PLY); @@ -516,75 +466,64 @@ namespace { const bool RootNode = (NT == Root || NT == SplitPointRoot); assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE); - assert((alpha == beta - 1) || PvNode); + assert(PvNode || (alpha == beta - 1)); assert(depth > DEPTH_ZERO); Move movesSearched[64]; StateInfo st; const TTEntry *tte; + SplitPoint* sp; Key posKey; Move ttMove, move, excludedMove, bestMove, threatMove; Depth ext, newDepth; - Bound bt; - Value bestValue, value, oldAlpha, ttValue; - Value refinedValue, nullValue, futilityBase, futilityValue; - bool isPvMove, inCheck, singularExtensionNode, givesCheck; + Value bestValue, value, ttValue; + Value refinedValue, nullValue, futilityValue; + bool inCheck, givesCheck, pvMove, singularExtensionNode; bool captureOrPromotion, dangerous, doFullDepthSearch; - int moveCount = 0, playedMoveCount = 0; - Thread* thisThread = pos.this_thread(); - SplitPoint* sp = NULL; + int moveCount, playedMoveCount; - refinedValue = bestValue = value = -VALUE_INFINITE; - oldAlpha = alpha; + // Step 1. Initialize node + Thread* thisThread = pos.this_thread(); + moveCount = playedMoveCount = 0; inCheck = pos.in_check(); - ss->ply = (ss-1)->ply + 1; - // Used to send selDepth info to GUI - if (PvNode && thisThread->maxPly < ss->ply) - thisThread->maxPly = ss->ply; - - // Step 1. Initialize node if (SpNode) { - tte = NULL; - ttMove = excludedMove = MOVE_NONE; - ttValue = VALUE_ZERO; sp = ss->sp; - bestMove = sp->bestMove; + bestMove = sp->bestMove; threatMove = sp->threatMove; - bestValue = sp->bestValue; - moveCount = sp->moveCount; // Lock must be held here + bestValue = sp->bestValue; + tte = NULL; + ttMove = excludedMove = MOVE_NONE; + ttValue = VALUE_NONE; - assert(bestValue > -VALUE_INFINITE && moveCount > 0); + assert(sp->bestValue > -VALUE_INFINITE && sp->moveCount > 0); goto split_point_start; } - else - { - ss->currentMove = threatMove = (ss+1)->excludedMove = bestMove = MOVE_NONE; - (ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO; - (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE; - } + bestValue = -VALUE_INFINITE; + ss->currentMove = threatMove = (ss+1)->excludedMove = bestMove = MOVE_NONE; + ss->ply = (ss-1)->ply + 1; + (ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO; + (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE; + + // Used to send selDepth info to GUI + if (PvNode && thisThread->maxPly < ss->ply) + thisThread->maxPly = ss->ply; - // Step 2. Check for aborted search and immediate draw - // Enforce node limit here. FIXME: This only works with 1 search thread. - if (Limits.nodes && pos.nodes_searched() >= Limits.nodes) - Signals.stop = true; - - if (( Signals.stop - || pos.is_draw() - || ss->ply > MAX_PLY) && !RootNode) - return VALUE_DRAW; - - // Step 3. Mate distance pruning. Even if we mate at the next move our score - // would be at best mate_in(ss->ply+1), but if alpha is already bigger because - // a shorter mate was found upward in the tree then there is no need to search - // further, we will never beat current alpha. Same logic but with reversed signs - // applies also in the opposite condition of being mated instead of giving mate, - // in this case return a fail-high score. if (!RootNode) { + // Step 2. Check for aborted search and immediate draw + if (Signals.stop || pos.is_draw() || ss->ply > MAX_PLY) + return Eval::ValueDraw[pos.side_to_move()]; + + // Step 3. Mate distance pruning. Even if we mate at the next move our score + // would be at best mate_in(ss->ply+1), but if alpha is already bigger because + // a shorter mate was found upward in the tree then there is no need to search + // further, we will never beat current alpha. Same logic but with reversed signs + // applies also in the opposite condition of being mated instead of giving mate, + // in this case return a fail-high score. alpha = std::max(mated_in(ss->ply), alpha); beta = std::min(mate_in(ss->ply+1), beta); if (alpha >= beta) @@ -598,14 +537,17 @@ namespace { posKey = excludedMove ? pos.exclusion_key() : pos.key(); tte = TT.probe(posKey); ttMove = RootNode ? RootMoves[PVIdx].pv[0] : tte ? tte->move() : MOVE_NONE; - ttValue = tte ? value_from_tt(tte->value(), ss->ply) : VALUE_ZERO; + ttValue = tte ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE; // At PV nodes we check for exact scores, while at non-PV nodes we check for // a fail high/low. Biggest advantage at probing at PV nodes is to have a // smooth experience in analysis mode. We don't probe at Root nodes otherwise // we should also update RootMoveList to avoid bogus output. - if (!RootNode && tte && (PvNode ? tte->depth() >= depth && tte->type() == BOUND_EXACT - : can_return_tt(tte, depth, ttValue, beta))) + if ( !RootNode + && tte && tte->depth() >= depth + && ( PvNode ? tte->type() == BOUND_EXACT + : ttValue >= beta ? (tte->type() & BOUND_LOWER) + : (tte->type() & BOUND_UPPER))) { TT.refresh(tte); ss->currentMove = ttMove; // Can be MOVE_NONE @@ -623,7 +565,7 @@ namespace { // Step 5. Evaluate the position statically and update parent's gain statistics if (inCheck) - ss->eval = ss->evalMargin = VALUE_NONE; + ss->eval = ss->evalMargin = refinedValue = VALUE_NONE; else if (tte) { assert(tte->static_value() != VALUE_NONE); @@ -652,7 +594,7 @@ namespace { // Step 6. Razoring (is omitted in PV nodes) if ( !PvNode - && depth < RazorDepth + && depth < 4 * ONE_PLY && !inCheck && refinedValue + razor_margin(depth) < beta && ttMove == MOVE_NONE @@ -672,12 +614,12 @@ namespace { // the score by more than futility_margin(depth) if we do a null move. if ( !PvNode && !ss->skipNullMove - && depth < RazorDepth + && depth < 4 * ONE_PLY && !inCheck - && refinedValue - futility_margin(depth, 0) >= beta + && refinedValue - FutilityMargins[depth][0] >= beta && abs(beta) < VALUE_MATE_IN_MAX_PLY && pos.non_pawn_material(pos.side_to_move())) - return refinedValue - futility_margin(depth, 0); + return refinedValue - FutilityMargins[depth][0]; // Step 8. Null move search with verification search (is omitted in PV nodes) if ( !PvNode @@ -731,7 +673,7 @@ namespace { // parent node, which will trigger a re-search with full depth). threatMove = (ss+1)->currentMove; - if ( depth < ThreatDepth + if ( depth < 5 * ONE_PLY && (ss-1)->reduction && threatMove != MOVE_NONE && connected_moves(pos, (ss-1)->currentMove, threatMove)) @@ -744,7 +686,7 @@ namespace { // and a reduced search returns a value much above beta, we can (almost) safely // prune the previous move. if ( !PvNode - && depth >= RazorDepth + ONE_PLY + && depth >= 5 * ONE_PLY && !inCheck && !ss->skipNullMove && excludedMove == MOVE_NONE @@ -773,9 +715,9 @@ namespace { } // Step 10. Internal iterative deepening - if ( depth >= IIDDepth[PvNode] + if ( depth >= (PvNode ? 5 * ONE_PLY : 8 * ONE_PLY) && ttMove == MOVE_NONE - && (PvNode || (!inCheck && ss->eval + IIDMargin >= beta))) + && (PvNode || (!inCheck && ss->eval + Value(256) >= beta))) { Depth d = (PvNode ? depth - 2 * ONE_PLY : depth / 2); @@ -791,10 +733,10 @@ split_point_start: // At split points actual search starts from here MovePicker mp(pos, ttMove, depth, H, ss, PvNode ? -VALUE_INFINITE : beta); CheckInfo ci(pos); - futilityBase = ss->eval + ss->evalMargin; + value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc singularExtensionNode = !RootNode && !SpNode - && depth >= SingularExtensionDepth[PvNode] + && depth >= (PvNode ? 6 * ONE_PLY : 8 * ONE_PLY) && ttMove != MOVE_NONE && !excludedMove // Recursive singular search is not allowed && (tte->type() & BOUND_LOWER) @@ -802,10 +744,7 @@ split_point_start: // At split points actual search starts from here // Step 11. Loop through moves // Loop through all pseudo-legal moves until no moves remain or a beta cutoff occurs - while ( bestValue < beta - && (move = mp.next_move()) != MOVE_NONE - && !thisThread->cutoff_occurred() - && !Signals.stop) + while ((move = mp.next_move()) != MOVE_NONE) { assert(is_ok(move)); @@ -818,12 +757,12 @@ split_point_start: // At split points actual search starts from here if (RootNode && !std::count(RootMoves.begin() + PVIdx, RootMoves.end(), move)) continue; - // At PV and SpNode nodes we want all moves to be legal since the beginning - if ((PvNode || SpNode) && !pos.pl_move_is_legal(move, ci.pinned)) - continue; - if (SpNode) { + // Shared counter cannot be decremented later if move turns out to be illegal + if (!pos.pl_move_is_legal(move, ci.pinned)) + continue; + moveCount = ++sp->moveCount; sp->mutex.unlock(); } @@ -840,11 +779,17 @@ split_point_start: // At split points actual search starts from here << " currmovenumber " << moveCount + PVIdx << sync_endl; } - isPvMove = (PvNode && moveCount <= 1); + ext = DEPTH_ZERO; captureOrPromotion = pos.is_capture_or_promotion(move); givesCheck = pos.move_gives_check(move, ci); - dangerous = givesCheck || is_dangerous(pos, move, captureOrPromotion); - ext = DEPTH_ZERO; + dangerous = givesCheck + || pos.is_passed_pawn_push(move) + || type_of(move) == CASTLE + || ( captureOrPromotion // Entering a pawn endgame? + && type_of(pos.piece_on(to_sq(move))) != PAWN + && type_of(move) == NORMAL + && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) + - PieceValue[Mg][pos.piece_on(to_sq(move))] == VALUE_ZERO)); // Step 12. Extend checks and, in PV nodes, also dangerous moves if (PvNode && dangerous) @@ -872,7 +817,7 @@ split_point_start: // At split points actual search starts from here ss->excludedMove = MOVE_NONE; if (value < rBeta) - ext = ONE_PLY; + ext = rBeta >= beta ? ONE_PLY + ONE_PLY / 2 : ONE_PLY; } // Update current move (this must be done after singular extension search) @@ -884,10 +829,12 @@ split_point_start: // At split points actual search starts from here && !inCheck && !dangerous && move != ttMove - && (bestValue > VALUE_MATED_IN_MAX_PLY || bestValue == -VALUE_INFINITE)) + && (bestValue > VALUE_MATED_IN_MAX_PLY || ( bestValue == -VALUE_INFINITE + && alpha > VALUE_MATED_IN_MAX_PLY))) { // Move count based pruning - if ( moveCount >= futility_move_count(depth) + if ( depth < 16 * ONE_PLY + && moveCount >= FutilityMoveCounts[depth] && (!threatMove || !connected_threat(pos, move, threatMove))) { if (SpNode) @@ -900,7 +847,7 @@ split_point_start: // At split points actual search starts from here // We illogically ignore reduction condition depth >= 3*ONE_PLY for predicted depth, // but fixing this made program slightly weaker. Depth predictedDepth = newDepth - reduction(depth, moveCount); - futilityValue = futilityBase + futility_margin(predictedDepth, moveCount) + futilityValue = ss->eval + ss->evalMargin + futility_margin(predictedDepth, moveCount) + H.gain(pos.piece_moved(move), to_sq(move)); if (futilityValue < beta) @@ -929,6 +876,7 @@ split_point_start: // At split points actual search starts from here continue; } + pvMove = PvNode ? moveCount == 1 : false; ss->currentMove = move; if (!SpNode && !captureOrPromotion && playedMoveCount < 64) movesSearched[playedMoveCount++] = move; @@ -939,7 +887,7 @@ split_point_start: // At split points actual search starts from here // Step 15. Reduced depth search (LMR). If the move fails high will be // re-searched at full depth. if ( depth > 3 * ONE_PLY - && !isPvMove + && !pvMove && !captureOrPromotion && !dangerous && ss->killers[0] != move @@ -955,7 +903,7 @@ split_point_start: // At split points actual search starts from here ss->reduction = DEPTH_ZERO; } else - doFullDepthSearch = !isPvMove; + doFullDepthSearch = !pvMove; // Step 16. Full depth search, when LMR is skipped or fails high if (doFullDepthSearch) @@ -968,7 +916,7 @@ split_point_start: // At split points actual search starts from here // Only for PV nodes do a full PV search on the first move or after a fail // high, in the latter case search only if value < beta, otherwise let the // parent node to fail low with value <= alpha and to try another move. - if (PvNode && (isPvMove || (value > alpha && (RootNode || value < beta)))) + if (PvNode && (pvMove || (value > alpha && (RootNode || value < beta)))) value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) : - search(pos, ss+1, -beta, -alpha, newDepth); @@ -989,12 +937,15 @@ split_point_start: // At split points actual search starts from here // was aborted because the user interrupted the search or because we // ran out of time. In this case, the return value of the search cannot // be trusted, and we don't update the best move and/or PV. - if (RootNode && !Signals.stop) + if (Signals.stop || thisThread->cutoff_occurred()) + return bestValue; + + if (RootNode) { RootMove& rm = *std::find(RootMoves.begin(), RootMoves.end(), move); // PV move or new best move ? - if (isPvMove || value > alpha) + if (pvMove || value > alpha) { rm.score = value; rm.extract_pv_from_tt(pos); @@ -1002,7 +953,7 @@ split_point_start: // At split points actual search starts from here // We record how often the best move has been changed in each // iteration. This information is used for time management: When // the best move changes frequently, we allocate some more time. - if (!isPvMove && MultiPV == 1) + if (!pvMove && MultiPV == 1) BestMoveChanges++; } else @@ -1010,82 +961,80 @@ split_point_start: // At split points actual search starts from here // is not a problem when sorting becuase sort is stable and move // position in the list is preserved, just the PV is pushed up. rm.score = -VALUE_INFINITE; - } if (value > bestValue) { bestValue = value; - bestMove = move; - - if ( PvNode - && value > alpha - && value < beta) // We want always alpha < beta - alpha = value; + if (SpNode) sp->bestValue = value; - if (SpNode && !thisThread->cutoff_occurred()) + if (value > alpha) { - sp->bestValue = value; - sp->bestMove = move; - sp->alpha = alpha; - - if (value >= beta) - sp->cutoff = true; + bestMove = move; + if (SpNode) sp->bestMove = move; + + if (PvNode && value < beta) + { + alpha = value; // Update alpha here! Always alpha < beta + if (SpNode) sp->alpha = value; + } + else // Fail high + { + if (SpNode) sp->cutoff = true; + break; + } } } - // Step 19. Check for split + // Step 19. Check for splitting the search if ( !SpNode && depth >= Threads.min_split_depth() && bestValue < beta - && Threads.available_slave_exists(thisThread) - && !Signals.stop - && !thisThread->cutoff_occurred()) + && Threads.available_slave_exists(thisThread)) + { bestValue = Threads.split(pos, ss, alpha, beta, bestValue, &bestMove, - depth, threatMove, moveCount, &mp, NT); + depth, threatMove, moveCount, mp, NT); + break; + } } + if (SpNode) + return bestValue; + // Step 20. Check for mate and stalemate // All legal moves have been searched and if there are no legal moves, it // must be mate or stalemate. Note that we can have a false positive in // case of Signals.stop or thread.cutoff_occurred() are set, but this is // harmless because return value is discarded anyhow in the parent nodes. // If we are in a singular extension search then return a fail low score. + // A split node has at least one move, the one tried before to be splitted. if (!moveCount) - return excludedMove ? oldAlpha : inCheck ? mated_in(ss->ply) : VALUE_DRAW; + return excludedMove ? alpha : inCheck ? mated_in(ss->ply) : VALUE_DRAW; // If we have pruned all the moves without searching return a fail-low score if (bestValue == -VALUE_INFINITE) { assert(!playedMoveCount); - bestValue = oldAlpha; + bestValue = alpha; } - // Step 21. Update tables - // Update transposition table entry, killers and history - if (!SpNode && !Signals.stop && !thisThread->cutoff_occurred()) + if (bestValue >= beta) // Failed high { - move = bestValue <= oldAlpha ? MOVE_NONE : bestMove; - bt = bestValue <= oldAlpha ? BOUND_UPPER - : bestValue >= beta ? BOUND_LOWER : BOUND_EXACT; - - TT.store(posKey, value_to_tt(bestValue, ss->ply), bt, depth, move, ss->eval, ss->evalMargin); + TT.store(posKey, value_to_tt(bestValue, ss->ply), BOUND_LOWER, depth, + bestMove, ss->eval, ss->evalMargin); - // Update killers and history for non capture cut-off moves - if ( bestValue >= beta - && !pos.is_capture_or_promotion(move) - && !inCheck) + if (!pos.is_capture_or_promotion(bestMove) && !inCheck) { - if (move != ss->killers[0]) + if (bestMove != ss->killers[0]) { ss->killers[1] = ss->killers[0]; - ss->killers[0] = move; + ss->killers[0] = bestMove; } // Increase history value of the cut-off move Value bonus = Value(int(depth) * int(depth)); - H.add(pos.piece_moved(move), to_sq(move), bonus); + H.add(pos.piece_moved(bestMove), to_sq(bestMove), bonus); // Decrease history of all the other played non-capture moves for (int i = 0; i < playedMoveCount - 1; i++) @@ -1095,6 +1044,10 @@ split_point_start: // At split points actual search starts from here } } } + else // Failed low or PV search + TT.store(posKey, value_to_tt(bestValue, ss->ply), + PvNode && bestMove != MOVE_NONE ? BOUND_EXACT : BOUND_UPPER, + depth, bestMove, ss->eval, ss->evalMargin); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1113,38 +1066,41 @@ split_point_start: // At split points actual search starts from here assert(NT == PV || NT == NonPV); assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE); - assert((alpha == beta - 1) || PvNode); + assert(PvNode || (alpha == beta - 1)); assert(depth <= DEPTH_ZERO); StateInfo st; - Move ttMove, move, bestMove; - Value ttValue, bestValue, value, evalMargin, futilityValue, futilityBase; - bool inCheck, enoughMaterial, givesCheck, evasionPrunable; const TTEntry* tte; + Key posKey; + Move ttMove, move, bestMove; + Value bestValue, value, ttValue, futilityValue, futilityBase; + bool inCheck, givesCheck, enoughMaterial, evasionPrunable; Depth ttDepth; - Bound bt; - Value oldAlpha = alpha; + inCheck = pos.in_check(); ss->currentMove = bestMove = MOVE_NONE; ss->ply = (ss-1)->ply + 1; // Check for an instant draw or maximum ply reached if (pos.is_draw() || ss->ply > MAX_PLY) - return VALUE_DRAW; + return Eval::ValueDraw[pos.side_to_move()]; + + // Transposition table lookup. At PV nodes, we don't use the TT for + // pruning, but only for move ordering. + posKey = pos.key(); + tte = TT.probe(posKey); + ttMove = tte ? tte->move() : MOVE_NONE; + ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_NONE; // 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. - inCheck = pos.in_check(); - ttDepth = (inCheck || 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.probe(pos.key()); - ttMove = (tte ? tte->move() : MOVE_NONE); - ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_ZERO; + ttDepth = inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS; - if (!PvNode && tte && can_return_tt(tte, ttDepth, ttValue, beta)) + if ( tte && tte->depth() >= ttDepth + && ( PvNode ? tte->type() == BOUND_EXACT + : ttValue >= beta ? (tte->type() & BOUND_LOWER) + : (tte->type() & BOUND_UPPER))) { ss->currentMove = ttMove; // Can be MOVE_NONE return ttValue; @@ -1153,8 +1109,8 @@ split_point_start: // At split points actual search starts from here // Evaluate the position statically if (inCheck) { + ss->eval = ss->evalMargin = VALUE_NONE; bestValue = futilityBase = -VALUE_INFINITE; - ss->eval = evalMargin = VALUE_NONE; enoughMaterial = false; } else @@ -1163,17 +1119,17 @@ split_point_start: // At split points actual search starts from here { assert(tte->static_value() != VALUE_NONE); - evalMargin = tte->static_value_margin(); ss->eval = bestValue = tte->static_value(); + ss->evalMargin = tte->static_value_margin(); } else - ss->eval = bestValue = evaluate(pos, evalMargin); + ss->eval = bestValue = evaluate(pos, ss->evalMargin); // Stand pat. Return immediately if static value is at least beta if (bestValue >= beta) { if (!tte) - TT.store(pos.key(), value_to_tt(bestValue, ss->ply), BOUND_LOWER, DEPTH_NONE, MOVE_NONE, ss->eval, evalMargin); + TT.store(pos.key(), value_to_tt(bestValue, ss->ply), BOUND_LOWER, DEPTH_NONE, MOVE_NONE, ss->eval, ss->evalMargin); return bestValue; } @@ -1181,7 +1137,7 @@ split_point_start: // At split points actual search starts from here if (PvNode && bestValue > alpha) alpha = bestValue; - futilityBase = ss->eval + evalMargin + FutilityMarginQS; + futilityBase = ss->eval + ss->evalMargin + Value(128); enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMg; } @@ -1193,8 +1149,7 @@ split_point_start: // At split points actual search starts from here CheckInfo ci(pos); // Loop through the moves until no moves remain or a beta cutoff occurs - while ( bestValue < beta - && (move = mp.next_move()) != MOVE_NONE) + while ((move = mp.next_move()) != MOVE_NONE) { assert(is_ok(move)); @@ -1261,21 +1216,31 @@ split_point_start: // At split points actual search starts from here // Make and search the move pos.do_move(move, st, ci, givesCheck); - value = -qsearch(pos, ss+1, -beta, -alpha, depth-ONE_PLY); + value = -qsearch(pos, ss+1, -beta, -alpha, depth - ONE_PLY); pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - // New best move? + // Check for new best move if (value > bestValue) { bestValue = value; - bestMove = move; - if ( PvNode - && value > alpha - && value < beta) // We want always alpha < beta - alpha = value; + if (value > alpha) + { + if (PvNode && value < beta) // Update alpha here! Always alpha < beta + { + alpha = value; + bestMove = move; + } + else // Fail high + { + TT.store(posKey, value_to_tt(value, ss->ply), BOUND_LOWER, + ttDepth, move, ss->eval, ss->evalMargin); + + return value; + } + } } } @@ -1284,12 +1249,9 @@ split_point_start: // At split points actual search starts from here if (inCheck && bestValue == -VALUE_INFINITE) return mated_in(ss->ply); // Plies to mate from the root - // Update transposition table - move = bestValue <= oldAlpha ? MOVE_NONE : bestMove; - bt = bestValue <= oldAlpha ? BOUND_UPPER - : bestValue >= beta ? BOUND_LOWER : BOUND_EXACT; - - TT.store(pos.key(), value_to_tt(bestValue, ss->ply), bt, ttDepth, move, ss->eval, evalMargin); + TT.store(posKey, value_to_tt(bestValue, ss->ply), + PvNode && bestMove != MOVE_NONE ? BOUND_EXACT : BOUND_UPPER, + ttDepth, bestMove, ss->eval, ss->evalMargin); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1462,20 +1424,6 @@ split_point_start: // At split points actual search starts from here } - // can_return_tt() returns true if a transposition table score can be used to - // cut-off at a given point in search. - - bool can_return_tt(const TTEntry* tte, Depth depth, Value v, Value beta) { - - return ( tte->depth() >= depth - || v >= std::max(VALUE_MATE_IN_MAX_PLY, beta) - || v < std::min(VALUE_MATED_IN_MAX_PLY, beta)) - - && ( ((tte->type() & BOUND_LOWER) && v >= beta) - || ((tte->type() & BOUND_UPPER) && v < beta)); - } - - // refine_eval() returns the transposition table score if possible, otherwise // falls back on static position evaluation. @@ -1519,7 +1467,7 @@ split_point_start: // At split points actual search starts from here int s = RootMoves[i].score; // Don't allow crazy blunders even at very low skills - if (i > 0 && RootMoves[i-1].score > s + EasyMoveMargin) + if (i > 0 && RootMoves[i-1].score > s + 2 * PawnValueMg) break; // This is our magic formula @@ -1715,6 +1663,10 @@ void Thread::idle_loop() { sp->mutex.lock(); + assert(sp->activePositions[idx] == NULL); + + sp->activePositions[idx] = &pos; + if (sp->nodeType == Root) search(pos, ss+1, sp->alpha, sp->beta, sp->depth); else if (sp->nodeType == PV) @@ -1727,6 +1679,7 @@ void Thread::idle_loop() { assert(is_searching); is_searching = false; + sp->activePositions[idx] = NULL; sp->slavesMask &= ~(1ULL << idx); sp->nodes += pos.nodes_searched(); @@ -1757,6 +1710,7 @@ void Thread::idle_loop() { void check_time() { static Time::point lastInfoTime = Time::now(); + int64_t nodes = 0; // Workaround silly 'uninitialized' gcc warning if (Time::now() - lastInfoTime >= 1000) { @@ -1767,6 +1721,35 @@ void check_time() { if (Limits.ponder) return; + if (Limits.nodes) + { + Threads.mutex.lock(); + + nodes = RootPosition.nodes_searched(); + + // Loop across all split points and sum accumulated SplitPoint nodes plus + // all the currently active slaves positions. + for (size_t i = 0; i < Threads.size(); i++) + for (int j = 0; j < Threads[i].splitPointsCnt; j++) + { + SplitPoint& sp = Threads[i].splitPoints[j]; + + sp.mutex.lock(); + + nodes += sp.nodes; + Bitboard sm = sp.slavesMask; + while (sm) + { + Position* pos = sp.activePositions[pop_lsb(&sm)]; + nodes += pos ? pos->nodes_searched() : 0; + } + + sp.mutex.unlock(); + } + + Threads.mutex.unlock(); + } + Time::point elapsed = Time::now() - SearchTime; bool stillAtFirstMove = Signals.firstRootMove && !Signals.failedLowAtRoot @@ -1776,6 +1759,7 @@ void check_time() { || stillAtFirstMove; if ( (Limits.use_time_management() && noMoreTime) - || (Limits.movetime && elapsed >= Limits.movetime)) + || (Limits.movetime && elapsed >= Limits.movetime) + || (Limits.nodes && nodes >= Limits.nodes)) Signals.stop = true; }