X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=912e7be0dfa0dd2548e69f01e8775d4ace81edd0;hp=3f5be1a38efe7fb8f823fcf2bda610aa211f64b7;hb=9c2b3faec4f4bbc44f4fb8cd1cae52ad642e3ab6;hpb=6b909b2343190f2989d21c8f69f40e9f09c530c0 diff --git a/src/search.cpp b/src/search.cpp index 3f5be1a3..912e7be0 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -91,8 +91,9 @@ namespace { TimeManager TimeMgr; int BestMoveChanges; int SkillLevel; + Move skillBest; bool SkillLevelEnabled, Chess960; - Value DrawValue[2]; + Value DrawValue[COLOR_NB]; History H; template @@ -107,7 +108,6 @@ namespace { Value value_to_tt(Value v, int ply); Value value_from_tt(Value v, int ply); 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); @@ -216,6 +216,7 @@ void Search::think() { // Do we have to play with skill handicap? In this case enable MultiPV that // we will use behind the scenes to retrieve a set of possible moves. SkillLevelEnabled = (SkillLevel < 20); + skillBest = MOVE_NONE; MultiPV = (SkillLevelEnabled ? std::max(UCIMultiPV, (size_t)4) : UCIMultiPV); if (Options["Use Search Log"]) @@ -247,6 +248,15 @@ void Search::think() { Threads.set_timer(0); // Stop timer Threads.sleep(); + // When using skills swap best PV line with the sub-optimal one + if (SkillLevelEnabled) + { + if (skillBest == MOVE_NONE) // Still unassigned ? + skillBest = do_skill_level(); + + std::swap(RootMoves[0], *std::find(RootMoves.begin(), RootMoves.end(), skillBest)); + } + if (Options["Use Search Log"]) { Time::point elapsed = Time::now() - SearchTime + 1; @@ -288,7 +298,6 @@ namespace { int depth, prevBestMoveChanges; Value bestValue, alpha, beta, delta; bool bestMoveNeverChanged = true; - Move skillBest = MOVE_NONE; memset(ss, 0, 4 * sizeof(Stack)); depth = BestMoveChanges = 0; @@ -296,7 +305,7 @@ namespace { ss->currentMove = MOVE_NULL; // Hack to skip update gains // Iterative deepening loop until requested to stop or target depth reached - while (!Signals.stop && ++depth <= MAX_PLY && (!Limits.depth || depth <= Limits.depth)) + while (++depth <= MAX_PLY && !Signals.stop && (!Limits.depth || depth <= Limits.depth)) { // Save last iteration's scores before first PV line is searched and all // the move scores but the (new) PV are set to -VALUE_INFINITE. @@ -338,37 +347,41 @@ namespace { // the already searched PV lines are preserved. sort(RootMoves.begin() + PVIdx, RootMoves.end()); - // In case we have found an exact score and we are going to leave - // the fail high/low loop then reorder the PV moves, otherwise - // leave the last PV move in its position so to be searched again. - // Of course this is needed only in MultiPV search. - if (PVIdx && bestValue > alpha && bestValue < beta) - sort(RootMoves.begin(), RootMoves.begin() + PVIdx); - // Write PV back to transposition table in case the relevant // entries have been overwritten during the search. for (size_t i = 0; i <= PVIdx; i++) RootMoves[i].insert_pv_in_tt(pos); - // If search has been stopped exit the aspiration window loop. - // Sorting and writing PV back to TT is safe becuase RootMoves - // is still valid, although refers to previous iteration. + // If search has been stopped return immediately. Sorting and + // writing PV back to TT is safe becuase RootMoves is still + // valid, although refers to previous iteration. if (Signals.stop) + return; + + // In case of failing high/low increase aspiration window and + // research, otherwise sort multi-PV lines and exit the loop. + if (bestValue > alpha && bestValue < beta) + { + sort(RootMoves.begin(), RootMoves.begin() + PVIdx); + sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl; break; + } - // Send full PV info to GUI if we are going to leave the loop or - // if we have a fail high/low and we are deep in the search. - if ((bestValue > alpha && bestValue < beta) || Time::now() - SearchTime > 2000) + // Give some update (without cluttering the UI) before to research + if (Time::now() - SearchTime > 3000) sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl; - // In case of failing high/low increase aspiration window and - // research, otherwise exit the fail high/low loop. - if (bestValue >= beta) + if (abs(bestValue) >= VALUE_KNOWN_WIN) + { + alpha = -VALUE_INFINITE; + beta = VALUE_INFINITE; + } + else if (bestValue >= beta) { beta += delta; delta += delta / 2; } - else if (bestValue <= alpha) + else { Signals.failedLowAtRoot = true; Signals.stopOnPonderhit = false; @@ -376,15 +389,6 @@ namespace { alpha -= delta; delta += delta / 2; } - else - break; - - // Search with full window in case we have a win/mate score - if (abs(bestValue) >= VALUE_KNOWN_WIN) - { - alpha = -VALUE_INFINITE; - beta = VALUE_INFINITE; - } assert(alpha >= -VALUE_INFINITE && beta <= VALUE_INFINITE); } @@ -394,7 +398,7 @@ namespace { if (SkillLevelEnabled && depth == 1 + SkillLevel) skillBest = do_skill_level(); - if (!Signals.stop && Options["Use Search Log"]) + if (Options["Use Search Log"]) { Log log(Options["Search Log Filename"]); log << pretty_pv(pos, depth, bestValue, Time::now() - SearchTime, &RootMoves[0].pv[0]) @@ -406,7 +410,7 @@ namespace { bestMoveNeverChanged = false; // Do we have time for the next iteration? Can we stop searching now? - if (!Signals.stop && !Signals.stopOnPonderhit && Limits.use_time_management()) + if (Limits.use_time_management() && !Signals.stopOnPonderhit) { bool stop = false; // Local variable, not the volatile Signals.stop @@ -448,15 +452,6 @@ namespace { } } } - - // When using skills swap best PV line with the sub-optimal one - if (SkillLevelEnabled) - { - if (skillBest == MOVE_NONE) // Still unassigned ? - skillBest = do_skill_level(); - - std::swap(RootMoves[0], *std::find(RootMoves.begin(), RootMoves.end(), skillBest)); - } } @@ -486,7 +481,7 @@ namespace { Move ttMove, move, excludedMove, bestMove, threatMove; Depth ext, newDepth; Value bestValue, value, ttValue; - Value refinedValue, nullValue, futilityValue; + Value eval, nullValue, futilityValue; bool inCheck, givesCheck, pvMove, singularExtensionNode; bool captureOrPromotion, dangerous, doFullDepthSearch; int moveCount, playedMoveCount; @@ -576,40 +571,45 @@ namespace { // Step 5. Evaluate the position statically and update parent's gain statistics if (inCheck) - ss->eval = ss->evalMargin = refinedValue = VALUE_NONE; + ss->staticEval = ss->evalMargin = eval = VALUE_NONE; else if (tte) { assert(tte->static_value() != VALUE_NONE); + assert(ttValue != VALUE_NONE || tte->type() == BOUND_NONE); - ss->eval = tte->static_value(); + ss->staticEval = eval = tte->static_value(); ss->evalMargin = tte->static_value_margin(); - refinedValue = refine_eval(tte, ttValue, ss->eval); + + // Can ttValue be used as a better position evaluation? + if ( ((tte->type() & BOUND_LOWER) && ttValue > eval) + || ((tte->type() & BOUND_UPPER) && ttValue < eval)) + eval = ttValue; } else { - refinedValue = ss->eval = evaluate(pos, ss->evalMargin); + eval = ss->staticEval = evaluate(pos, ss->evalMargin); TT.store(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE, - ss->eval, ss->evalMargin); + ss->staticEval, ss->evalMargin); } // Update gain for the parent non-capture move given the static position // evaluation before and after the move. - if ( (move = (ss-1)->currentMove) != MOVE_NULL - && (ss-1)->eval != VALUE_NONE - && ss->eval != VALUE_NONE + if ( (move = (ss-1)->currentMove) != MOVE_NULL + && (ss-1)->staticEval != VALUE_NONE + && ss->staticEval != VALUE_NONE && !pos.captured_piece_type() && type_of(move) == NORMAL) { Square to = to_sq(move); - H.update_gain(pos.piece_on(to), to, -(ss-1)->eval - ss->eval); + H.update_gain(pos.piece_on(to), to, -(ss-1)->staticEval - ss->staticEval); } // Step 6. Razoring (is omitted in PV nodes) if ( !PvNode && depth < 4 * ONE_PLY && !inCheck - && refinedValue + razor_margin(depth) < beta + && eval + razor_margin(depth) < beta && ttMove == MOVE_NONE && abs(beta) < VALUE_MATE_IN_MAX_PLY && !pos.pawn_on_7th(pos.side_to_move())) @@ -629,17 +629,17 @@ namespace { && !ss->skipNullMove && depth < 4 * ONE_PLY && !inCheck - && refinedValue - FutilityMargins[depth][0] >= beta + && eval - FutilityMargins[depth][0] >= beta && abs(beta) < VALUE_MATE_IN_MAX_PLY && pos.non_pawn_material(pos.side_to_move())) - return refinedValue - FutilityMargins[depth][0]; + return eval - FutilityMargins[depth][0]; // Step 8. Null move search with verification search (is omitted in PV nodes) if ( !PvNode && !ss->skipNullMove && depth > ONE_PLY && !inCheck - && refinedValue >= beta + && eval >= beta && abs(beta) < VALUE_MATE_IN_MAX_PLY && pos.non_pawn_material(pos.side_to_move())) { @@ -649,7 +649,7 @@ namespace { Depth R = 3 * ONE_PLY + depth / 4; // Null move dynamic reduction based on value - if (refinedValue - PawnValueMg > beta) + if (eval - PawnValueMg > beta) R += ONE_PLY; pos.do_null_move(st); @@ -730,7 +730,7 @@ namespace { // Step 10. Internal iterative deepening if ( depth >= (PvNode ? 5 * ONE_PLY : 8 * ONE_PLY) && ttMove == MOVE_NONE - && (PvNode || (!inCheck && ss->eval + Value(256) >= beta))) + && (PvNode || (!inCheck && ss->staticEval + Value(256) >= beta))) { Depth d = (PvNode ? depth - 2 * ONE_PLY : depth / 2); @@ -802,7 +802,7 @@ split_point_start: // At split points actual search starts from here && 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)); + - PieceValue[MG][pos.piece_on(to_sq(move))] == VALUE_ZERO)); // Step 12. Extend checks and, in PV nodes, also dangerous moves if (PvNode && dangerous) @@ -817,8 +817,8 @@ split_point_start: // At split points actual search starts from here // on all the other moves but the ttMove, if result is lower than ttValue minus // a margin then we extend ttMove. if ( singularExtensionNode - && !ext && move == ttMove + && !ext && pos.pl_move_is_legal(move, ci.pinned) && abs(ttValue) < VALUE_KNOWN_WIN) { @@ -862,7 +862,7 @@ 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 = ss->eval + ss->evalMargin + futility_margin(predictedDepth, moveCount) + futilityValue = ss->staticEval + ss->evalMargin + futility_margin(predictedDepth, moveCount) + H.gain(pos.piece_moved(move), to_sq(move)); if (futilityValue < beta) @@ -1038,7 +1038,7 @@ split_point_start: // At split points actual search starts from here if (bestValue >= beta) // Failed high { TT.store(posKey, value_to_tt(bestValue, ss->ply), BOUND_LOWER, depth, - bestMove, ss->eval, ss->evalMargin); + bestMove, ss->staticEval, ss->evalMargin); if (!pos.is_capture_or_promotion(bestMove) && !inCheck) { @@ -1063,7 +1063,7 @@ 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); + depth, bestMove, ss->staticEval, ss->evalMargin); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1127,7 +1127,7 @@ split_point_start: // At split points actual search starts from here // Evaluate the position statically if (inCheck) { - ss->eval = ss->evalMargin = VALUE_NONE; + ss->staticEval = ss->evalMargin = VALUE_NONE; bestValue = futilityBase = -VALUE_INFINITE; enoughMaterial = false; } @@ -1137,18 +1137,18 @@ split_point_start: // At split points actual search starts from here { assert(tte->static_value() != VALUE_NONE); - ss->eval = bestValue = tte->static_value(); + ss->staticEval = bestValue = tte->static_value(); ss->evalMargin = tte->static_value_margin(); } else - ss->eval = bestValue = evaluate(pos, ss->evalMargin); + ss->staticEval = 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, ss->evalMargin); + DEPTH_NONE, MOVE_NONE, ss->staticEval, ss->evalMargin); return bestValue; } @@ -1156,7 +1156,7 @@ split_point_start: // At split points actual search starts from here if (PvNode && bestValue > alpha) alpha = bestValue; - futilityBase = ss->eval + ss->evalMargin + Value(128); + futilityBase = ss->staticEval + ss->evalMargin + Value(128); enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMg; } @@ -1184,7 +1184,7 @@ split_point_start: // At split points actual search starts from here && !pos.is_passed_pawn_push(move)) { futilityValue = futilityBase - + PieceValue[Eg][pos.piece_on(to_sq(move))] + + PieceValue[EG][pos.piece_on(to_sq(move))] + (type_of(move) == ENPASSANT ? PawnValueEg : VALUE_ZERO); if (futilityValue < beta) @@ -1223,7 +1223,7 @@ split_point_start: // At split points actual search starts from here && givesCheck && move != ttMove && !pos.is_capture_or_promotion(move) - && ss->eval + PawnValueMg / 4 < beta + && ss->staticEval + PawnValueMg / 4 < beta && !check_is_dangerous(pos, move, futilityBase, beta)) continue; @@ -1255,7 +1255,7 @@ split_point_start: // At split points actual search starts from here else // Fail high { TT.store(posKey, value_to_tt(value, ss->ply), BOUND_LOWER, - ttDepth, move, ss->eval, ss->evalMargin); + ttDepth, move, ss->staticEval, ss->evalMargin); return value; } @@ -1270,7 +1270,7 @@ split_point_start: // At split points actual search starts from here TT.store(posKey, value_to_tt(bestValue, ss->ply), PvNode && bestMove != MOVE_NONE ? BOUND_EXACT : BOUND_UPPER, - ttDepth, bestMove, ss->eval, ss->evalMargin); + ttDepth, bestMove, ss->staticEval, ss->evalMargin); assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1315,7 +1315,7 @@ split_point_start: // At split points actual search starts from here while (b) { // Note that here we generate illegal "double move"! - if (futilityBase + PieceValue[Eg][pos.piece_on(pop_lsb(&b))] >= beta) + if (futilityBase + PieceValue[EG][pos.piece_on(pop_lsb(&b))] >= beta) return true; } @@ -1420,7 +1420,7 @@ split_point_start: // At split points actual search starts from here // Case 2: If the threatened piece has value less than or equal to the // value of the threatening piece, don't prune moves which defend it. if ( pos.is_capture(threat) - && ( PieceValue[Mg][pos.piece_on(tfrom)] >= PieceValue[Mg][pos.piece_on(tto)] + && ( PieceValue[MG][pos.piece_on(tfrom)] >= PieceValue[MG][pos.piece_on(tto)] || type_of(pos.piece_on(tfrom)) == KING) && pos.move_attacks_square(m, tto)) return true; @@ -1436,23 +1436,6 @@ split_point_start: // At split points actual search starts from here } - // refine_eval() returns the transposition table score if possible, otherwise - // falls back on static position evaluation. Note that we never return VALUE_NONE - // even if v == VALUE_NONE. - - Value refine_eval(const TTEntry* tte, Value v, Value defaultEval) { - - assert(tte); - assert(v != VALUE_NONE || !tte->type()); - - if ( ((tte->type() & BOUND_LOWER) && v >= defaultEval) - || ((tte->type() & BOUND_UPPER) && v < defaultEval)) - return v; - - return defaultEval; - } - - // When playing with strength handicap choose best move among the MultiPV set // using a statistical rule dependent on SkillLevel. Idea by Heinz van Saanen.