X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=43fb7067a4692a0ca8915c68316215125e109261;hp=03993be432a43ce24d496bc0b7bac92fd8d016a6;hb=c01af5676913cbb8a522bd080b6d8559c7450f3a;hpb=0e15b0f1d3837d9203b562fe698d223143882501 diff --git a/src/search.cpp b/src/search.cpp index 03993be4..43fb7067 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -94,8 +94,16 @@ namespace { struct RootMove { - RootMove(); - bool operator<(const RootMove&) const; // Used to sort + RootMove() { nodes = cumulativeNodes = ourBeta = theirBeta = 0ULL; } + + // RootMove::operator<() is the comparison function used when + // sorting the moves. A move m1 is considered to be better + // than a move m2 if it has a higher score, or if the moves + // have equal score but m1 has the higher node count. + bool operator<(const RootMove& m) const { + + return score != m.score ? score < m.score : theirBeta <= m.theirBeta; + } Move move; Value score; @@ -111,16 +119,18 @@ namespace { public: RootMoveList(Position& pos, Move searchMoves[]); - inline Move get_move(int moveNum) const; - 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); + + int move_count() const { return count; } + Move get_move(int moveNum) const { return moves[moveNum].move; } + Value get_move_score(int moveNum) const { return moves[moveNum].score; } + void set_move_score(int moveNum, Value score) { moves[moveNum].score = score; } + Move get_move_pv(int moveNum, int i) const { return moves[moveNum].pv[i]; } + int64_t get_move_cumulative_nodes(int moveNum) const { return moves[moveNum].cumulativeNodes; } + + void set_move_nodes(int moveNum, int64_t nodes); + 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; - inline int move_count() const; - inline void sort(); + void sort(); void sort_multipv(int n); private: @@ -162,15 +172,9 @@ namespace { // best move from the previous iteration, Problem is set back to false. const Value NoProblemMargin = Value(0x14); - // Null move margin. A null move search will not be done if the approximate + // Null move margin. A null move search will not be done if the static // evaluation of the position is more than NullMoveMargin below beta. - const Value NullMoveMargin = Value(0x300); - - // Pruning criterions. See the code and comments in ok_to_prune() to - // understand their precise meaning. - const bool PruneEscapeMoves = false; - const bool PruneDefendingMoves = false; - const bool PruneBlockingMoves = false; + const Value NullMoveMargin = Value(0x200); // If the TT move is at least SingleReplyMargin better then the // remaining ones we will extend it. @@ -186,13 +190,6 @@ namespace { // Depth limit for razoring const Depth RazorDepth = 4 * OnePly; - // Remaining depth: 1 ply 1.5 ply 2 ply 2.5 ply 3 ply 3.5 ply - const Value RazorMargins[6] = { Value(0x180), Value(0x300), Value(0x300), Value(0x3C0), Value(0x3C0), Value(0x3C0) }; - - // Remaining depth: 1 ply 1.5 ply 2 ply 2.5 ply 3 ply 3.5 ply - const Value RazorApprMargins[6] = { Value(0x520), Value(0x300), Value(0x300), Value(0x300), Value(0x300), Value(0x300) }; - - /// Variables initialized by UCI options // Minimum number of full depth (i.e. non-reduced) moves at PV and non-PV nodes @@ -227,7 +224,7 @@ namespace { int SearchStartTime; int MaxNodes, MaxDepth; int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime; - bool InfiniteSearch, PonderSearch, StopOnPonderhit; + bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit; bool AbortSearch, Quit; bool FailHigh, FailLow, Problem; @@ -284,7 +281,8 @@ namespace { bool ok_to_do_nullmove(const Position& pos); bool ok_to_prune(const Position& pos, Move m, Move threat); bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply); - void update_history(const Position& pos, Move m, Depth depth, Move movesSearched[], int moveCount); + Value refine_eval(const TTEntry* tte, Value defaultEval, int ply); + void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount); void update_killers(Move m, SearchStack& ss); bool fail_high_ply_1(); @@ -321,6 +319,13 @@ namespace { //// Functions //// +//FIXME: HACK +static double lnArray[512]; + +inline double ln(int i) +{ + return lnArray[i]; +} /// perft() is our utility to verify move generation is bug free. All the legal /// moves up to given depth are generated and counted and the sum returned. @@ -361,8 +366,20 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, int time[], int increment[], int movesToGo, int maxDepth, int maxNodes, int maxTime, Move searchMoves[]) { - // Look for a book move - if (!infinite && !ponder && get_option_value_bool("OwnBook")) + // Initialize global search variables + Idle = StopOnPonderhit = AbortSearch = Quit = false; + FailHigh = FailLow = Problem = false; + NodesSincePoll = 0; + SearchStartTime = get_system_time(); + ExactMaxTime = maxTime; + MaxDepth = maxDepth; + MaxNodes = maxNodes; + InfiniteSearch = infinite; + PonderSearch = ponder; + UseTimeManagement = !ExactMaxTime && !MaxDepth && !MaxNodes && !InfiniteSearch; + + // Look for a book move, only during games, not tests + if (UseTimeManagement && !ponder && get_option_value_bool("OwnBook")) { Move bookMove; if (get_option_value_string("Book File") != OpeningBook.file_name()) @@ -376,15 +393,6 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, } } - // Initialize global search variables - Idle = StopOnPonderhit = AbortSearch = Quit = false; - FailHigh = FailLow = Problem = false; - SearchStartTime = get_system_time(); - ExactMaxTime = maxTime; - NodesSincePoll = 0; - InfiniteSearch = infinite; - PonderSearch = ponder; - for (int i = 0; i < THREAD_MAX; i++) { Threads[i].nodes = 0ULL; @@ -452,51 +460,45 @@ bool 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]; - - if (!movesToGo) // Sudden death time control + if (UseTimeManagement) { - if (myIncrement) + if (!movesToGo) // Sudden death time control { - MaxSearchTime = myTime / 30 + myIncrement; - AbsoluteMaxSearchTime = Max(myTime / 4, myIncrement - 100); + if (myIncrement) + { + MaxSearchTime = myTime / 30 + myIncrement; + AbsoluteMaxSearchTime = Max(myTime / 4, myIncrement - 100); + } + else // Blitz game without increment + { + MaxSearchTime = myTime / 30; + AbsoluteMaxSearchTime = myTime / 8; + } } - else // Blitz game without increment + else // (x moves) / (y minutes) { - MaxSearchTime = myTime / 30; - AbsoluteMaxSearchTime = myTime / 8; - } - } - else // (x moves) / (y minutes) - { - if (movesToGo == 1) - { - MaxSearchTime = myTime / 2; - AbsoluteMaxSearchTime = (myTime > 3000)? (myTime - 500) : ((myTime * 3) / 4); + if (movesToGo == 1) + { + MaxSearchTime = myTime / 2; + AbsoluteMaxSearchTime = (myTime > 3000)? (myTime - 500) : ((myTime * 3) / 4); + } + else + { + MaxSearchTime = myTime / Min(movesToGo, 20); + AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3); + } } - else + + if (PonderingEnabled) { - MaxSearchTime = myTime / Min(movesToGo, 20); - AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3); + MaxSearchTime += MaxSearchTime / 4; + MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime); } } - if (PonderingEnabled) - { - MaxSearchTime += MaxSearchTime / 4; - MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime); - } - - // Fixed depth or fixed number of nodes? - MaxDepth = maxDepth; - if (MaxDepth) - InfiniteSearch = true; // HACK - - MaxNodes = maxNodes; + // Set best NodesBetweenPolls interval if (MaxNodes) - { NodesBetweenPolls = Min(MaxNodes, 30000); - InfiniteSearch = true; // HACK - } else if (myTime && myTime < 1000) NodesBetweenPolls = 1000; else if (myTime && myTime < 5000) @@ -557,8 +559,14 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, /// and initializes the split point stack and the global locks and condition /// objects. +#include //FIXME: HACK + void init_threads() { + // FIXME: HACK!! + for (int i = 0; i < 512; i++) + lnArray[i] = log(double(i)); + volatile int i; #if !defined(_MSC_VER) @@ -644,6 +652,8 @@ void SearchStack::init(int ply) { pv[ply] = pv[ply + 1] = MOVE_NONE; currentMove = threatMove = MOVE_NONE; reduction = Depth(0); + eval = VALUE_NONE; + evalInfo = NULL; } void SearchStack::initKillers() { @@ -773,7 +783,7 @@ namespace { Problem = false; - if (!InfiniteSearch) + if (UseTimeManagement) { // Time to stop? bool stopSearch = false; @@ -827,9 +837,9 @@ namespace { rml.sort(); - // If we are pondering, we shouldn't print the best move before we - // are told to do so - if (PonderSearch) + // If we are pondering or in infinite search, we shouldn't print the + // best move before we are told to do so. + if (!AbortSearch && (PonderSearch || InfiniteSearch)) wait_for_stop_or_ponderhit(); else // Print final search statistics @@ -877,7 +887,7 @@ namespace { Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value alpha, Value beta) { Value oldAlpha = alpha; - Value value; + Value value = -VALUE_INFINITE; CheckInfo ci(pos); // Loop through all the moves in the root move list @@ -894,7 +904,7 @@ namespace { int64_t nodes; Move move; StateInfo st; - Depth ext, newDepth; + Depth depth, ext, newDepth; RootMoveNumber = i + 1; FailHigh = false; @@ -917,8 +927,9 @@ namespace { bool moveIsCheck = pos.move_is_check(move); bool captureOrPromotion = pos.move_is_capture_or_promotion(move); bool dangerous; + depth = (Iteration - 2) * OnePly + InitialDepth; ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous); - newDepth = (Iteration - 2) * OnePly + ext + InitialDepth; + newDepth = depth + ext; // Make the move, and search it pos.do_move(move, st, ci, moveIsCheck); @@ -945,18 +956,23 @@ 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 ( newDepth >= 3*OnePly - && i >= MultiPV + LMRPVMoves + bool doFullDepthSearch = true; + + if ( depth >= 3*OnePly // FIXME was newDepth && !dangerous && !captureOrPromotion && !move_is_castle(move)) { - ss[0].reduction = OnePly; - value = -search(pos, ss, -alpha, newDepth-OnePly, 1, true, 0); - } else - value = alpha + 1; // Just to trigger next condition + double red = 0.5 + ln(RootMoveNumber - MultiPV + 1) * ln(depth / 2) / 6.0; + if (red >= 1.0) + { + ss[0].reduction = Depth(int(floor(red * int(OnePly)))); + value = -search(pos, ss, -alpha, newDepth-ss[0].reduction, 1, true, 0); + doFullDepthSearch = (value > alpha); + } + } - if (value > alpha) + if (doFullDepthSearch) { value = -search(pos, ss, -alpha, newDepth, 1, true, 0); @@ -1083,7 +1099,6 @@ namespace { assert(threadID >= 0 && threadID < ActiveThreads); Move movesSearched[256]; - EvalInfo ei; StateInfo st; const TTEntry* tte; Move ttMove, move; @@ -1091,7 +1106,7 @@ namespace { Value oldAlpha, value; bool isCheck, mateThreat, singleEvasion, moveIsCheck, captureOrPromotion, dangerous; int moveCount = 0; - Value bestValue = -VALUE_INFINITE; + Value bestValue = value = -VALUE_INFINITE; if (depth < OnePly) return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID); @@ -1104,12 +1119,9 @@ namespace { if (AbortSearch || thread_should_stop(threadID)) return Value(0); - if (pos.is_draw()) + if (pos.is_draw() || ply >= PLY_MAX - 1) return VALUE_DRAW; - if (ply >= PLY_MAX - 1) - return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID); - // Mate distance pruning oldAlpha = alpha; alpha = Max(value_mated_in(ply), alpha); @@ -1196,20 +1208,24 @@ 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. + bool doFullDepthSearch = true; + if ( depth >= 3*OnePly - && moveCount >= LMRPVMoves && !dangerous && !captureOrPromotion && !move_is_castle(move) && !move_is_killer(move, ss[ply])) { - ss[ply].reduction = OnePly; - value = -search(pos, ss, -alpha, newDepth-OnePly, ply+1, true, threadID); + double red = 0.5 + ln(moveCount) * ln(depth / 2) / 6.0; + if (red >= 1.0) + { + ss[ply].reduction = Depth(int(floor(red * int(OnePly)))); + value = -search(pos, ss, -alpha, newDepth-ss[ply].reduction, ply+1, true, threadID); + doFullDepthSearch = (value > alpha); + } } - else - value = alpha + 1; // Just to trigger next condition - if (value > alpha) // Go with full depth non-pv search + if (doFullDepthSearch) // Go with full depth non-pv search { ss[ply].reduction = Depth(0); value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID); @@ -1312,11 +1328,11 @@ namespace { const TTEntry* tte; Move ttMove, move; Depth ext, newDepth; - Value approximateEval, nullValue, value, futilityValue, futilityValueScaled; + Value bestValue, staticValue, nullValue, value, futilityValue, futilityValueScaled; bool isCheck, useFutilityPruning, singleEvasion, moveIsCheck, captureOrPromotion, dangerous; bool mateThreat = false; int moveCount = 0; - Value bestValue = -VALUE_INFINITE; + futilityValue = staticValue = bestValue = value = -VALUE_INFINITE; if (depth < OnePly) return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID); @@ -1329,12 +1345,9 @@ namespace { if (AbortSearch || thread_should_stop(threadID)) return Value(0); - if (pos.is_draw()) + if (pos.is_draw() || ply >= PLY_MAX - 1) return VALUE_DRAW; - if (ply >= PLY_MAX - 1) - return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID); - // Mate distance pruning if (value_mated_in(ply) >= beta) return beta; @@ -1356,26 +1369,45 @@ namespace { return value_from_tt(tte->value(), ply); } - approximateEval = quick_evaluate(pos); isCheck = pos.is_check(); + // Calculate depth dependant futility pruning parameters + const int FutilityMoveCountMargin = 3 + (1 << (3 * int(depth) / 8)); + const int FutilityValueMargin = 112 * bitScanReverse32(int(depth) * int(depth) / 2); + + // Evaluate the position statically + if (!isCheck) + { + if (tte && (tte->type() & VALUE_TYPE_EVAL)) + staticValue = value_from_tt(tte->value(), ply); + else + { + staticValue = evaluate(pos, ei, threadID); + ss[ply].evalInfo = &ei; + } + + ss[ply].eval = staticValue; + futilityValue = staticValue + FutilityValueMargin; + staticValue = refine_eval(tte, staticValue, ply); // Enhance accuracy with TT value if possible + } + // Null move search if ( allowNullmove && depth > OnePly && !isCheck && !value_is_mate(beta) && ok_to_do_nullmove(pos) - && approximateEval >= beta - NullMoveMargin) + && staticValue >= beta - NullMoveMargin) { ss[ply].currentMove = MOVE_NULL; pos.do_null_move(st); // Null move dynamic reduction based on depth - int R = (depth >= 5 * OnePly ? 4 : 3); + int R = 3 + (depth >= 5 * OnePly ? depth / 8 : 0); // Null move dynamic reduction based on value - if (approximateEval - beta > PawnValueMidgame) + if (staticValue - beta > PawnValueMidgame) R++; nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID); @@ -1410,13 +1442,14 @@ namespace { } // Null move search not allowed, try razoring else if ( !value_is_mate(beta) + && !isCheck && depth < RazorDepth - && approximateEval < beta - RazorApprMargins[int(depth) - 2] + && staticValue < beta - (NullMoveMargin + 16 * depth) && ss[ply - 1].currentMove != MOVE_NULL && ttMove == MOVE_NONE && !pos.has_pawn_on_7th(pos.side_to_move())) { - Value rbeta = beta - RazorMargins[int(depth) - 2]; + Value rbeta = beta - (NullMoveMargin + 16 * depth); Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), ply, threadID); if (v < rbeta) return v; @@ -1424,7 +1457,7 @@ namespace { // Go with internal iterative deepening if we don't have a TT move if (UseIIDAtNonPVNodes && ttMove == MOVE_NONE && depth >= 8*OnePly && - !isCheck && evaluate(pos, ei, threadID) >= beta - IIDMargin) + !isCheck && ss[ply].eval >= beta - IIDMargin) { search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID); ttMove = ss[ply].pv[ply]; @@ -1435,17 +1468,8 @@ namespace { // to search all moves. MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]); CheckInfo ci(pos); - futilityValue = VALUE_NONE; useFutilityPruning = depth < SelectiveDepth && !isCheck; - // Calculate depth dependant futility pruning parameters - const int FutilityMoveCountMargin = 3 + (1 << (3 * int(depth) / 8)); - const int FutilityValueMargin = 112 * bitScanReverse32(int(depth) * int(depth) / 2); - - // Avoid calling evaluate() if we already have the score in TT - if (tte && (tte->type() & VALUE_TYPE_EVAL)) - futilityValue = value_from_tt(tte->value(), ply) + FutilityValueMargin; - // Loop through all legal moves until no moves remain or a beta cutoff occurs while ( bestValue < beta && (move = mp.get_next_move()) != MOVE_NONE @@ -1456,8 +1480,8 @@ namespace { if (move == excludedMove) continue; - singleEvasion = (isCheck && mp.number_of_evasions() == 1); moveIsCheck = pos.move_is_check(move, ci); + singleEvasion = (isCheck && mp.number_of_evasions() == 1); captureOrPromotion = pos.move_is_capture_or_promotion(move); // Decide the new search depth @@ -1503,9 +1527,6 @@ namespace { continue; // Value based pruning - if (futilityValue == VALUE_NONE) - futilityValue = evaluate(pos, ei, threadID) + FutilityValueMargin; - futilityValueScaled = futilityValue - moveCount * IncrementalFutilityMargin; if (futilityValueScaled < beta) @@ -1521,20 +1542,25 @@ 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. + bool doFullDepthSearch = true; + if ( depth >= 3*OnePly - && moveCount >= LMRNonPVMoves && !dangerous && !captureOrPromotion && !move_is_castle(move) - && !move_is_killer(move, ss[ply])) + && !move_is_killer(move, ss[ply]) + /* && move != ttMove*/) { - ss[ply].reduction = OnePly; - value = -search(pos, ss, -(beta-1), newDepth-OnePly, ply+1, true, threadID); + double red = 0.5 + ln(moveCount) * ln(depth / 2) / 3.0; + if (red >= 1.0) + { + ss[ply].reduction = Depth(int(floor(red * int(OnePly)))); + value = -search(pos, ss, -(beta-1), newDepth-ss[ply].reduction, ply+1, true, threadID); + doFullDepthSearch = (value >= beta); + } } - else - value = beta; // Just to trigger next condition - if (value >= beta) // Go with full depth non-pv search + if (doFullDepthSearch) // Go with full depth non-pv search { ss[ply].reduction = Depth(0); value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID); @@ -1567,9 +1593,9 @@ namespace { break; } - // All legal moves have been searched. A special case: If there were + // All legal moves have been searched. A special case: If there were // no legal moves, it must be mate or stalemate. - if (moveCount == 0) + if (!moveCount) return excludedMove ? beta - 1 : (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW); // If the search is not aborted, update the transposition table, @@ -1583,12 +1609,13 @@ namespace { { BetaCounter.add(pos.side_to_move(), depth, threadID); move = ss[ply].pv[ply]; + TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move); if (!pos.move_is_capture_or_promotion(move)) { update_history(pos, move, depth, movesSearched, moveCount); update_killers(move, ss[ply]); } - TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move); + } assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); @@ -1613,7 +1640,7 @@ namespace { EvalInfo ei; StateInfo st; Move ttMove, move; - Value staticValue, bestValue, value, futilityValue; + Value staticValue, bestValue, value, futilityBase, futilityValue; bool isCheck, enoughMaterial, moveIsCheck; const TTEntry* tte = NULL; int moveCount = 0; @@ -1627,42 +1654,32 @@ namespace { if (AbortSearch || thread_should_stop(threadID)) return Value(0); - if (pos.is_draw()) + if (pos.is_draw() || ply >= PLY_MAX - 1) return VALUE_DRAW; - // Transposition table lookup, only when not in PV - if (!pvNode) + // Transposition table lookup. At PV nodes, we don't use the TT for + // pruning, but only for move ordering. + tte = TT.retrieve(pos.get_key()); + ttMove = (tte ? tte->move() : MOVE_NONE); + + if (!pvNode && tte && ok_to_use_TT(tte, depth, beta, ply)) { - tte = TT.retrieve(pos.get_key()); - if (tte && ok_to_use_TT(tte, depth, beta, ply)) - { - assert(tte->type() != VALUE_TYPE_EVAL); + assert(tte->type() != VALUE_TYPE_EVAL); - return value_from_tt(tte->value(), ply); - } + ss[ply].currentMove = ttMove; // Can be MOVE_NONE + return value_from_tt(tte->value(), ply); } - ttMove = (tte ? tte->move() : MOVE_NONE); isCheck = pos.is_check(); - ei.futilityMargin = Value(0); // Manually initialize futilityMargin // Evaluate the position statically if (isCheck) staticValue = -VALUE_INFINITE; - else if (tte && (tte->type() & VALUE_TYPE_EVAL)) - { - // Use the cached evaluation score if possible - assert(ei.futilityMargin == Value(0)); - staticValue = value_from_tt(tte->value(), ply); - } else staticValue = evaluate(pos, ei, threadID); - if (ply >= PLY_MAX - 1) - return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID); - // Initialize "stand pat score", and return it immediately if it is // at least beta. bestValue = staticValue; @@ -1685,6 +1702,7 @@ namespace { MovePicker mp = MovePicker(pos, ttMove, depth, H); CheckInfo ci(pos); enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame; + futilityBase = staticValue + FutilityMarginQS + ei.futilityMargin; // Loop through the moves until no moves remain or a beta cutoff // occurs. @@ -1693,11 +1711,12 @@ namespace { { assert(move_is_ok(move)); + moveIsCheck = pos.move_is_check(move, ci); + + // Update current move moveCount++; ss[ply].currentMove = move; - moveIsCheck = pos.move_is_check(move, ci); - // Futility pruning if ( enoughMaterial && !isCheck @@ -1707,12 +1726,9 @@ namespace { && !move_is_promotion(move) && !pos.move_is_passed_pawn_push(move)) { - futilityValue = staticValue - + Max(pos.midgame_value_of_piece_on(move_to(move)), - pos.endgame_value_of_piece_on(move_to(move))) - + (move_is_ep(move) ? PawnValueEndgame : Value(0)) - + FutilityMarginQS - + ei.futilityMargin; + futilityValue = futilityBase + + pos.endgame_value_of_piece_on(move_to(move)) + + (move_is_ep(move) ? PawnValueEndgame : Value(0)); if (futilityValue < alpha) { @@ -1748,31 +1764,31 @@ namespace { } } - // All legal moves have been searched. A special case: If we're in check + // All legal moves have been searched. A special case: If we're in check // and no legal moves were found, it is checkmate. if (!moveCount && pos.is_check()) // Mate! return value_mated_in(ply); - assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); - // Update transposition table - move = ss[ply].pv[ply]; - if (!pvNode) + Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1)); + if (bestValue < beta) { - // If bestValue isn't changed it means it is still the static evaluation of - // the node, so keep this info to avoid a future costly evaluation() call. + // If bestValue isn't changed it means it is still the static evaluation + // of the node, so keep this info to avoid a future evaluation() call. ValueType type = (bestValue == staticValue && !ei.futilityMargin ? VALUE_TYPE_EV_UP : VALUE_TYPE_UPPER); - Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1)); + TT.store(pos.get_key(), value_to_tt(bestValue, ply), type, d, MOVE_NONE); + } + else + { + move = ss[ply].pv[ply]; + TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move); - if (bestValue < beta) - TT.store(pos.get_key(), value_to_tt(bestValue, ply), type, d, MOVE_NONE); - else - TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move); + // Update killers only for good checking moves + if (!pos.move_is_capture_or_promotion(move)) + update_killers(move, ss[ply]); } - // Update killers only for good check moves - if (alpha >= beta && !pos.move_is_capture_or_promotion(move)) - update_killers(move, ss[ply]); + assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE); return bestValue; } @@ -1794,14 +1810,13 @@ namespace { Position pos = Position(sp->pos); CheckInfo ci(pos); SearchStack* ss = sp->sstack[threadID]; - Value value; + Value value = -VALUE_INFINITE; Move move; bool isCheck = pos.is_check(); bool useFutilityPruning = sp->depth < SelectiveDepth && !isCheck; const int FutilityMoveCountMargin = 3 + (1 << (3 * int(sp->depth) / 8)); - const int FutilityValueMargin = 112 * bitScanReverse32(int(sp->depth) * int(sp->depth) / 2); while ( sp->bestValue < sp->beta && !thread_should_stop(threadID) @@ -1835,12 +1850,6 @@ namespace { continue; // Value based pruning - if (sp->futilityValue == VALUE_NONE) - { - EvalInfo ei; - sp->futilityValue = evaluate(pos, ei, threadID) + FutilityValueMargin; - } - Value futilityValueScaled = sp->futilityValue - moveCount * IncrementalFutilityMargin; if (futilityValueScaled < sp->beta) @@ -1862,19 +1871,23 @@ 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. + bool doFullDepthSearch = true; + if ( !dangerous - && moveCount >= LMRNonPVMoves && !captureOrPromotion && !move_is_castle(move) && !move_is_killer(move, ss[sp->ply])) { - ss[sp->ply].reduction = OnePly; - value = -search(pos, ss, -(sp->beta-1), newDepth - OnePly, sp->ply+1, true, threadID); + double red = 0.5 + ln(moveCount) * ln(sp->depth / 2) / 3.0; + if (red >= 1.0) + { + ss[sp->ply].reduction = Depth(int(floor(red * int(OnePly)))); + value = -search(pos, ss, -(sp->beta-1), newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID); + doFullDepthSearch = (value >= sp->beta); + } } - else - value = sp->beta; // Just to trigger next condition - if (value >= sp->beta) // Go with full depth non-pv search + if (doFullDepthSearch) // Go with full depth non-pv search { ss[sp->ply].reduction = Depth(0); value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, true, threadID); @@ -1939,7 +1952,7 @@ namespace { Position pos = Position(sp->pos); CheckInfo ci(pos); SearchStack* ss = sp->sstack[threadID]; - Value value; + Value value = -VALUE_INFINITE; Move move; while ( sp->alpha < sp->beta @@ -1968,27 +1981,33 @@ 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. + bool doFullDepthSearch = true; + if ( !dangerous - && moveCount >= LMRPVMoves && !captureOrPromotion && !move_is_castle(move) && !move_is_killer(move, ss[sp->ply])) { - ss[sp->ply].reduction = OnePly; - value = -search(pos, ss, -sp->alpha, newDepth - OnePly, sp->ply+1, true, threadID); + double red = 0.5 + ln(moveCount) * ln(sp->depth / 2) / 6.0; + if (red >= 1.0) + { + Value localAlpha = sp->alpha; + ss[sp->ply].reduction = Depth(int(floor(red * int(OnePly)))); + value = -search(pos, ss, -localAlpha, newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID); + doFullDepthSearch = (value > localAlpha); + } } - else - value = sp->alpha + 1; // Just to trigger next condition - if (value > sp->alpha) // Go with full depth non-pv search + if (doFullDepthSearch) // Go with full depth non-pv search { + Value localAlpha = sp->alpha; ss[sp->ply].reduction = Depth(0); - value = -search(pos, ss, -sp->alpha, newDepth, sp->ply+1, true, threadID); + value = -search(pos, ss, -localAlpha, newDepth, sp->ply+1, true, threadID); - if (value > sp->alpha && value < sp->beta) + if (value > localAlpha && value < sp->beta) { // When the search fails high at ply 1 while searching the first - // move at the root, set the flag failHighPly1. This is used for + // move at the root, set the flag failHighPly1. This is used for // time managment: We don't want to stop the search early in // such cases, because resolving the fail high at ply 1 could // result in a big drop in score at the root. @@ -2080,30 +2099,9 @@ namespace { } - /// The RootMove class - - // Constructor - - RootMove::RootMove() { - nodes = cumulativeNodes = ourBeta = theirBeta = 0ULL; - } - - // RootMove::operator<() is the comparison function used when - // sorting the moves. A move m1 is considered to be better - // than a move m2 if it has a higher score, or if the moves - // have equal score but m1 has the higher node count. - - bool RootMove::operator<(const RootMove& m) const { - - if (score != m.score) - return (score < m.score); - - return theirBeta <= m.theirBeta; - } - /// The RootMoveList class - // Constructor + // RootMoveList c'tor RootMoveList::RootMoveList(Position& pos, Move searchMoves[]) : count(0) { @@ -2141,56 +2139,37 @@ namespace { } - // Simple accessor methods for the RootMoveList class - - inline Move RootMoveList::get_move(int moveNum) const { - return moves[moveNum].move; - } - - inline Value RootMoveList::get_move_score(int moveNum) const { - return moves[moveNum].score; - } + // RootMoveList simple methods definitions - inline void RootMoveList::set_move_score(int moveNum, Value score) { - moves[moveNum].score = score; - } + void RootMoveList::set_move_nodes(int moveNum, int64_t nodes) { - inline void RootMoveList::set_move_nodes(int moveNum, int64_t nodes) { moves[moveNum].nodes = nodes; moves[moveNum].cumulativeNodes += nodes; } - inline void RootMoveList::set_beta_counters(int moveNum, int64_t our, int64_t their) { + 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++) - moves[moveNum].pv[j] = pv[j]; - moves[moveNum].pv[j] = MOVE_NONE; - } - inline Move RootMoveList::get_move_pv(int moveNum, int i) const { - return moves[moveNum].pv[i]; - } + int j; - inline int64_t RootMoveList::get_move_cumulative_nodes(int moveNum) const { - return moves[moveNum].cumulativeNodes; - } + for (j = 0; pv[j] != MOVE_NONE; j++) + moves[moveNum].pv[j] = pv[j]; - inline int RootMoveList::move_count() const { - return count; + moves[moveNum].pv[j] = MOVE_NONE; } // RootMoveList::sort() sorts the root move list at the beginning of a new // iteration. - inline void RootMoveList::sort() { + void RootMoveList::sort() { - sort_multipv(count - 1); // all items + sort_multipv(count - 1); // Sort all items } @@ -2200,20 +2179,22 @@ namespace { void RootMoveList::sort_multipv(int n) { - for (int i = 1; i <= n; i++) + int i,j; + + for (i = 1; i <= n; i++) { - RootMove rm = moves[i]; - int j; - for (j = i; j > 0 && moves[j-1] < rm; j--) - moves[j] = moves[j-1]; - moves[j] = rm; + RootMove rm = moves[i]; + for (j = i; j > 0 && moves[j - 1] < rm; j--) + moves[j] = moves[j - 1]; + + moves[j] = rm; } } // init_node() is called at the beginning of all the search functions - // (search(), search_pv(), qsearch(), and so on) and initializes the search - // stack object corresponding to the current node. Once every + // (search(), search_pv(), qsearch(), and so on) and initializes the + // search stack object corresponding to the current node. Once every // NodesBetweenPolls nodes, init_node() also calls poll(), which polls // for user input and checks whether it is time to stop the search. @@ -2234,48 +2215,56 @@ namespace { } } ss[ply].init(ply); - ss[ply+2].initKillers(); + ss[ply + 2].initKillers(); if (Threads[threadID].printCurrentLine) print_current_line(ss, ply, threadID); } - // update_pv() is called whenever a search returns a value > alpha. It - // updates the PV in the SearchStack object corresponding to the current - // node. + // update_pv() is called whenever a search returns a value > alpha. + // It updates the PV in the SearchStack object corresponding to the + // current node. void update_pv(SearchStack ss[], int ply) { + assert(ply >= 0 && ply < PLY_MAX); - ss[ply].pv[ply] = ss[ply].currentMove; int p; - for (p = ply + 1; ss[ply+1].pv[p] != MOVE_NONE; p++) - ss[ply].pv[p] = ss[ply+1].pv[p]; + + ss[ply].pv[ply] = ss[ply].currentMove; + + for (p = ply + 1; ss[ply + 1].pv[p] != MOVE_NONE; p++) + ss[ply].pv[p] = ss[ply + 1].pv[p]; + ss[ply].pv[p] = MOVE_NONE; } - // sp_update_pv() is a variant of update_pv for use at split points. The + // sp_update_pv() is a variant of update_pv for use at split points. The // difference between the two functions is that sp_update_pv also updates // the PV at the parent node. void sp_update_pv(SearchStack* pss, SearchStack ss[], int ply) { + assert(ply >= 0 && ply < PLY_MAX); - ss[ply].pv[ply] = pss[ply].pv[ply] = ss[ply].currentMove; int p; - for (p = ply + 1; ss[ply+1].pv[p] != MOVE_NONE; p++) - ss[ply].pv[p] = pss[ply].pv[p] = ss[ply+1].pv[p]; + + ss[ply].pv[ply] = pss[ply].pv[ply] = ss[ply].currentMove; + + for (p = ply + 1; ss[ply + 1].pv[p] != MOVE_NONE; p++) + ss[ply].pv[p] = pss[ply].pv[p] = ss[ply + 1].pv[p]; + ss[ply].pv[p] = pss[ply].pv[p] = MOVE_NONE; } // connected_moves() tests whether two moves are 'connected' in the sense // that the first move somehow made the second move possible (for instance - // if the moving piece is the same in both moves). The first move is - // assumed to be the move that was made to reach the current position, while - // the second move is assumed to be a move from the current position. + // if the moving piece is the same in both moves). The first move is assumed + // to be the move that was made to reach the current position, while the + // second move is assumed to be a move from the current position. bool connected_moves(const Position& pos, Move m1, Move m2) { @@ -2305,36 +2294,23 @@ namespace { && bit_is_set(squares_between(f2, t2), f1)) return true; - // Case 4: The destination square for m2 is attacked by the moving piece in m1 + // Case 4: The destination square for m2 is defended by the moving piece in m1 p = pos.piece_on(t1); if (bit_is_set(pos.attacks_from(p, t1), t2)) return true; // Case 5: Discovered check, checking piece is the piece moved in m1 - if ( piece_is_slider(p) - && bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), f2) + if ( piece_is_slider(p) + && bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), f2) && !bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), t2)) { - Bitboard occ = pos.occupied_squares(); - Color us = pos.side_to_move(); - Square ksq = pos.king_square(us); - clear_bit(&occ, f2); - if (type_of_piece(p) == BISHOP) - { - if (bit_is_set(bishop_attacks_bb(ksq, occ), t1)) - return true; - } - else if (type_of_piece(p) == ROOK) - { - if (bit_is_set(rook_attacks_bb(ksq, occ), t1)) - return true; - } - else - { - assert(type_of_piece(p) == QUEEN); - if (bit_is_set(queen_attacks_bb(ksq, occ), t1)) - return true; - } + // discovered_check_candidates() works also if the Position's side to + // move is the opposite of the checking piece. + Color them = opposite_color(pos.side_to_move()); + Bitboard dcCandidates = pos.discovered_check_candidates(them); + + if (bit_is_set(dcCandidates, f2)) + return true; } return false; } @@ -2367,7 +2343,7 @@ namespace { // extension() decides whether a move should be searched with normal depth, - // or with extended depth. Certain classes of moves (checking moves, in + // or with extended depth. Certain classes of moves (checking moves, in // 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, @@ -2433,11 +2409,11 @@ namespace { // ok_to_do_nullmove() looks at the current position and decides whether - // doing a 'null move' should be allowed. In order to avoid zugzwang + // doing a 'null move' should be allowed. In order to avoid zugzwang // problems, null moves are not allowed when the side to move has very - // little material left. Currently, the test is a bit too simple: Null - // moves are avoided only when the side to move has only pawns left. It's - // probably a good idea to avoid null moves in at least some more + // little material left. Currently, the test is a bit too simple: Null + // moves are avoided only when the side to move has only pawns left. + // It's probably a good idea to avoid null moves in at least some more // complicated endgames, e.g. KQ vs KR. FIXME bool ok_to_do_nullmove(const Position& pos) { @@ -2446,7 +2422,7 @@ namespace { } - // ok_to_prune() tests whether it is safe to forward prune a move. Only + // ok_to_prune() tests whether it is safe to forward prune a move. Only // non-tactical moves late in the move list close to the leaves are // candidates for pruning. @@ -2460,6 +2436,11 @@ namespace { Square mfrom, mto, tfrom, tto; + // Prune if there isn't any threat move and + // is not a castling move (common case). + if (threat == MOVE_NONE && !move_is_castle(m)) + return true; + mfrom = move_from(m); mto = move_to(m); tfrom = move_from(threat); @@ -2470,14 +2451,12 @@ namespace { return false; // Case 2: Don't prune moves which move the threatened piece - if (!PruneEscapeMoves && threat != MOVE_NONE && mfrom == tto) + if (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 - && pos.move_is_capture(threat) + if ( 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)) @@ -2485,9 +2464,7 @@ namespace { // Case 4: 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)) + if ( piece_is_slider(pos.piece_on(tfrom)) && bit_is_set(squares_between(tfrom, tto), mto) && pos.see_sign(m) >= 0) return false; @@ -2512,19 +2489,41 @@ namespace { } + // refine_eval() returns the transposition table score if + // possible otherwise falls back on static position evaluation. + + Value refine_eval(const TTEntry* tte, Value defaultEval, int ply) { + + if (!tte) + return defaultEval; + + Value v = value_from_tt(tte->value(), ply); + + if ( (is_lower_bound(tte->type()) && v >= defaultEval) + || (is_upper_bound(tte->type()) && v < defaultEval)) + return v; + + return defaultEval; + } + // update_history() registers a good move that produced a beta-cutoff // in history and marks as failures all the other moves of that ply. - void update_history(const Position& pos, Move m, Depth depth, + void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount) { - H.success(pos.piece_on(move_from(m)), move_to(m), depth); + Move m; + + H.success(pos.piece_on(move_from(move)), move_to(move), depth); for (int i = 0; i < moveCount - 1; i++) { - assert(m != movesSearched[i]); - if (!pos.move_is_capture_or_promotion(movesSearched[i])) - H.failure(pos.piece_on(move_from(movesSearched[i])), move_to(movesSearched[i]), depth); + m = movesSearched[i]; + + assert(m != move); + + if (!pos.move_is_capture_or_promotion(m)) + H.failure(pos.piece_on(move_from(m)), move_to(m), depth); } } @@ -2546,7 +2545,7 @@ namespace { // fail_high_ply_1() checks if some thread is currently resolving a fail // high at ply 1 at the node below the first root node. This information - // is used for time managment. + // is used for time management. bool fail_high_ply_1() { @@ -2657,7 +2656,7 @@ namespace { || stillAtFirstMove //FIXME: We are not checking any problem flags, BUG? || noProblemFound; - if ( (Iteration >= 3 && !InfiniteSearch && noMoreTime) + if ( (Iteration >= 3 && UseTimeManagement && noMoreTime) || (ExactMaxTime && t >= ExactMaxTime) || (Iteration >= 3 && MaxNodes && nodes_searched() >= MaxNodes)) AbortSearch = true; @@ -2687,7 +2686,7 @@ namespace { || stillAtFirstMove || noProblemFound; - if (Iteration >= 3 && !InfiniteSearch && (noMoreTime || StopOnPonderhit)) + if (Iteration >= 3 && UseTimeManagement && (noMoreTime || StopOnPonderhit)) AbortSearch = true; } @@ -2770,8 +2769,8 @@ namespace { if (AllThreadsShouldExit && threadID != 0) break; - // If we are not thinking, wait for a condition to be signaled instead - // of wasting CPU time polling for work. + // If we are not thinking, wait for a condition to be signaled + // instead of wasting CPU time polling for work. while (threadID != 0 && (Idle || threadID >= ActiveThreads)) { @@ -2835,7 +2834,7 @@ namespace { // thread_should_stop() checks whether the thread with a given threadID has // been asked to stop, directly or indirectly. This can happen if a beta - // cutoff has occured in the thread's currently active split point, or in + // cutoff has occurred in the thread's currently active split point, or in // some ancestor of the current split point. bool thread_should_stop(int threadID) { @@ -2883,7 +2882,7 @@ namespace { if (ActiveThreads == 2) return true; - // Apply the "helpful master" concept if possible. + // Apply the "helpful master" concept if possible if (SplitPointStack[slave][Threads[slave].activeSplitPoints - 1].slaves[master]) return true;