X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=0e3838371fe0bc95366462fd1b8d547a2e3bd079;hp=be324c16edff44b08a7450edbd8d016cf65fe351;hb=a9e55d43262d11a916bdfa68cd1de0174d884cd3;hpb=c8773c720af6fd5c3a8f84550ee36e5eb89f929e diff --git a/src/search.cpp b/src/search.cpp index be324c16..0e383837 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -125,9 +125,6 @@ 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. @@ -152,16 +149,6 @@ namespace { // evaluation of the position is more than NullMoveMargin below beta. const Value NullMoveMargin = Value(0x300); - //Null move search refutes move when Nullvalue >= Beta - Delta. Index is depth - //in full plies. Last index is 9+. - const Value NullMoveDeltaMidgame[] = - { Value(-8), Value( 6), Value(-15), Value( 9), Value(21), - Value(34), Value(54), Value( 59), Value(61), Value(61) }; - - const Value NullMoveDeltaEndgame[] = - { Value( 6), Value( 0), Value(-13), Value(-9), Value(-35), - Value(12), Value(24), Value( 9), Value( 5), Value( 5) }; - // Pruning criterions. See the code and comments in ok_to_prune() to // understand their precise meaning. const bool PruneEscapeMoves = false; @@ -206,7 +193,6 @@ namespace { // Iteration counters int Iteration; - bool LastIterations; BetaCounterType BetaCounter; // Scores and number of times the best move changed for each iteration: @@ -220,7 +206,7 @@ namespace { int SearchStartTime; int MaxNodes, MaxDepth; int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime; - Move BestRootMove, PonderMove, EasyMove; + Move EasyMove; int RootMoveNumber; bool InfiniteSearch; bool PonderSearch; @@ -382,8 +368,6 @@ void think(const Position &pos, bool infinite, bool ponder, int side_to_move, // Initialize global search variables Idle = false; SearchStartTime = get_system_time(); - BestRootMove = MOVE_NONE; - PonderMove = MOVE_NONE; EasyMove = MOVE_NONE; for (int i = 0; i < THREAD_MAX; i++) { @@ -437,7 +421,6 @@ 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)"); @@ -675,7 +658,6 @@ namespace { ValueByIteration[0] = Value(0); ValueByIteration[1] = rml.get_move_score(0); Iteration = 1; - LastIterations = false; EasyMove = rml.scan_for_easy_move(); @@ -730,9 +712,6 @@ namespace { ExtraSearchTime = BestMoveChangesByIteration[Iteration] * (MaxSearchTime / 2) + BestMoveChangesByIteration[Iteration-1] * (MaxSearchTime / 3); - // Try to guess if the current iteration is the last one or the last two - LastIterations = (current_search_time() > ((MaxSearchTime + ExtraSearchTime)*58) / 128); - // Stop search if most of MaxSearchTime is consumed at the end of the // iteration. We probably don't have enough time to search the first // move at the next iteration anyway. @@ -769,6 +748,11 @@ namespace { << " hashfull " << TT.full() << std::endl; // Print the best move and the ponder move to the standard output + if (ss[0].pv[0] == MOVE_NONE) + { + ss[0].pv[0] = rml.get_move(0); + ss[0].pv[1] = MOVE_NONE; + } std::cout << "bestmove " << ss[0].pv[0]; if (ss[0].pv[1] != MOVE_NONE) std::cout << " ponder " << ss[0].pv[1]; @@ -1201,7 +1185,6 @@ namespace { Value approximateEval = quick_evaluate(pos); bool mateThreat = false; - bool nullDrivenIID = false; bool isCheck = pos.is_check(); // Null move search @@ -1212,32 +1195,13 @@ namespace { && ok_to_do_nullmove(pos) && approximateEval >= beta - NullMoveMargin) { - //Calculate correct delta. Idea and tuning from Joona Kiiski. - ScaleFactor factor[2] = { SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL }; - Phase phase = pos.game_phase(); - int i = Min(depth / OnePly, 9); - Value delta = scale_by_game_phase(NullMoveDeltaMidgame[i], NullMoveDeltaEndgame[i], phase, factor); - ss[ply].currentMove = MOVE_NULL; StateInfo st; pos.do_null_move(st); int R = (depth >= 4 * OnePly ? 4 : 3); // Null move dynamic reduction - Value nullValue = -search(pos, ss, -(beta-delta-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 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) - && pos.see(ss[ply + 1].currentMove) + nullValue >= beta) - nullDrivenIID = true; + Value nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID); pos.undo_null_move(); @@ -1245,7 +1209,7 @@ namespace { { /* Do not return unproven mates */ } - else if (nullValue >= beta - delta) + else if (nullValue >= beta) { if (depth < 6 * OnePly) return beta; @@ -1262,10 +1226,8 @@ namespace { // 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 @@ -1283,8 +1245,8 @@ namespace { { Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); if ( (v < beta - RazorMargin - RazorMargin / 4) - || (depth < 3*OnePly && v < beta - RazorMargin) - || (depth < 2*OnePly && v < beta - RazorMargin / 2)) + || (depth <= 2*OnePly && v < beta - RazorMargin) + || (depth <= OnePly && v < beta - RazorMargin / 2)) return v; } @@ -1295,22 +1257,6 @@ 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 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); - 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: @@ -1386,8 +1332,11 @@ namespace { && !move_is_castle(move) && !move_is_killer(move, ss[ply])) { - ss[ply].reduction = OnePly; - value = -search(pos, ss, -(beta-1), newDepth-OnePly, ply+1, true, threadID); + // LMR dynamic reduction + Depth R = (moveCount >= 2 * LMRNonPVMoves && depth > 7*OnePly ? 2*OnePly : OnePly); + + ss[ply].reduction = R; + value = -search(pos, ss, -(beta-1), newDepth-R, ply+1, true, threadID); } else value = beta; // Just to trigger next condition @@ -1448,6 +1397,9 @@ namespace { } TT.store(pos, value_to_tt(bestValue, ply), depth, m, VALUE_TYPE_LOWER); } + + assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); + return bestValue; } @@ -1476,10 +1428,14 @@ namespace { if (pos.is_draw()) return VALUE_DRAW; - // Transposition table lookup - const TTEntry* tte = TT.retrieve(pos); - if (tte && ok_to_use_TT(tte, depth, beta, ply)) - return value_from_tt(tte->value(), ply); + // Transposition table lookup, only when not in PV + bool pvNode = (beta - alpha != 1); + if (!pvNode) + { + const TTEntry* tte = TT.retrieve(pos); + if (tte && ok_to_use_TT(tte, depth, beta, ply)) + return value_from_tt(tte->value(), ply); + } // Evaluate the position statically EvalInfo ei; @@ -1502,7 +1458,6 @@ 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. - bool pvNode = (beta - alpha != 1); MovePicker mp = MovePicker(pos, pvNode, MOVE_NONE, EmptySearchStack, depth, isCheck ? NULL : &ei); Move move; int moveCount = 0;