X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=043c433a648cba38fb0bab2be01cf3a45b2d2385;hp=92d2eda61d188b007a9cc4f42e7cbb41c196bbee;hb=abae3c5678897be39fd7a082543937f846dcfbd5;hpb=1fc88071d1b982166de5af42e834e018ead80595 diff --git a/src/search.cpp b/src/search.cpp index 92d2eda6..043c433a 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -87,7 +87,7 @@ namespace { Depth depth, bool mateThreat, int* moves, MovePicker* mp, int master, bool pvNode); private: - friend void poll(SearchStack ss[], int ply); + friend void poll(); int ActiveThreads; volatile bool AllThreadsShouldExit, AllThreadsShouldSleep; @@ -104,6 +104,13 @@ namespace { }; + // FIXME: document me + + enum NullStatus { + ALLOW_NULLMOVE, + FORBID_NULLMOVE, + VERIFY_NULLMOVE + }; // RootMove struct is used for moves at the root at the tree. For each // root move, we store a score, a node count, and a PV (really a refutation @@ -215,14 +222,12 @@ namespace { // Step 14. Reduced search - int ReductionLevel = 2; // 0 = most aggressive reductions, 7 = minimum reductions - // Reduction lookup tables (initialized at startup) and their getter functions - int8_t PVReductionMatrix[8][64][64]; // [depth][moveNumber] - int8_t NonPVReductionMatrix[8][64][64]; // [depth][moveNumber] + int8_t PVReductionMatrix[64][64]; // [depth][moveNumber] + int8_t NonPVReductionMatrix[64][64]; // [depth][moveNumber] - inline Depth pv_reduction(Depth d, int mn) { return (Depth) PVReductionMatrix[ReductionLevel][Min(d / 2, 63)][Min(mn, 63)]; } - inline Depth nonpv_reduction(Depth d, int mn) { return (Depth) NonPVReductionMatrix[ReductionLevel][Min(d / 2, 63)][Min(mn, 63)]; } + inline Depth pv_reduction(Depth d, int mn) { return (Depth) PVReductionMatrix[Min(d / 2, 63)][Min(mn, 63)]; } + inline Depth nonpv_reduction(Depth d, int mn) { return (Depth) NonPVReductionMatrix[Min(d / 2, 63)][Min(mn, 63)]; } // Common adjustments @@ -261,9 +266,6 @@ namespace { bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit; bool FirstRootMove, AbortSearch, Quit, AspirationFailLow; - // Show current line? - bool ShowCurrentLine; - // Log file bool UseLogFile; std::ofstream LogFile; @@ -286,7 +288,7 @@ namespace { Value id_loop(const Position& pos, Move searchMoves[]); Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value* alphaPtr, Value* betaPtr); Value search_pv(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID); - Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID, Move excludedMove = MOVE_NONE); + Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, NullStatus nullStatus, int threadID, Move excludedMove = MOVE_NONE); Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID); void sp_search(SplitPoint* sp, int threadID); void sp_search_pv(SplitPoint* sp, int threadID); @@ -299,7 +301,7 @@ namespace { Depth extension(const Position&, Move, bool, bool, bool, bool, bool, bool*); 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); + bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply, bool allowNullmove); 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); @@ -307,7 +309,7 @@ namespace { int current_search_time(); int nps(); - void poll(SearchStack ss[], int ply); + void poll(); void ponderhit(); void wait_for_stop_or_ponderhit(); void init_ss_array(SearchStack ss[]); @@ -392,7 +394,7 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, if (get_option_value_string("Book File") != OpeningBook.file_name()) OpeningBook.open(get_option_value_string("Book File")); - Move bookMove = OpeningBook.get_move(pos); + Move bookMove = OpeningBook.get_move(pos, get_option_value_bool("Best Book Move")); if (bookMove != MOVE_NONE) { if (PonderSearch) @@ -427,7 +429,6 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, MinimumSplitDepth = get_option_value_int("Minimum Split Depth") * OnePly; MaxThreadsPerSplitPoint = get_option_value_int("Maximum Number of Threads per Split Point"); - ShowCurrentLine = get_option_value_bool("UCI_ShowCurrLine"); MultiPV = get_option_value_int("MultiPV"); Chess960 = get_option_value_bool("UCI_Chess960"); UseLogFile = get_option_value_bool("Use Search Log"); @@ -546,30 +547,20 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, return !Quit; } -// init_reduction_tables() is called by init_search() and initializes -// the tables used by LMR. -static void init_reduction_tables(int8_t pvTable[64][64], int8_t nonPvTable[64][64], int pvInhib, int nonPvInhib) -{ - double pvBase = 1.001 - log(3.0) * log(16.0) / pvInhib; - double nonPvBase = 1.001 - log(3.0) * log(4.0) / nonPvInhib; +/// init_search() is called during startup. It initializes various lookup tables + +void init_search() { + + // Init our reduction lookup tables for (int i = 1; i < 64; i++) // i == depth (OnePly = 1) for (int j = 1; j < 64; j++) // j == moveNumber { - double pvRed = pvBase + log(double(i)) * log(double(j)) / pvInhib; - double nonPVRed = nonPvBase + log(double(i)) * log(double(j)) / nonPvInhib; - - pvTable[i][j] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(OnePly)) : 0); - nonPvTable[i][j] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(OnePly)) : 0); + double pvRed = 0.5 + log(double(i)) * log(double(j)) / 6.0; + double nonPVRed = 0.5 + log(double(i)) * log(double(j)) / 3.0; + PVReductionMatrix[i][j] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(OnePly)) : 0); + NonPVReductionMatrix[i][j] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(OnePly)) : 0); } -} - -// init_search() is called during startup. It initializes various lookup tables -void init_search() { - - // Init reduction lookup tables - for (int i = 0; i < 8; i++) - init_reduction_tables(PVReductionMatrix[i], NonPVReductionMatrix[i], int(4 * pow(1.3, i)), int(2 * pow(1.3, i))); // Init futility margins array for (int i = 0; i < 16; i++) // i == depth (OnePly = 2) @@ -672,19 +663,6 @@ namespace { beta = Min(ValueByIteration[Iteration - 1] + AspirationDelta, VALUE_INFINITE); } - // Choose optimum reduction level - ReductionLevel = 2; - - if (UseTimeManagement) - { - int level = int(floor(log(float(MaxSearchTime) / current_search_time()) / log(2.0) + 1.0)); - ReductionLevel = Min(Max(level, 0), 7); - } - else - { - //FIXME - } - // Search to the current depth, rml is updated and sorted, alpha and beta could change value = root_search(p, ss, rml, &alpha, &beta); @@ -915,7 +893,7 @@ namespace { if (ss[0].reduction) { // Reduced depth non-pv search using alpha as upperbound - value = -search(pos, ss, -alpha, newDepth-ss[0].reduction, 1, true, 0); + value = -search(pos, ss, -alpha, newDepth-ss[0].reduction, 1, ALLOW_NULLMOVE, 0); doFullDepthSearch = (value > alpha); } } @@ -925,7 +903,7 @@ namespace { { // Full depth non-pv search using alpha as upperbound ss[0].reduction = Depth(0); - value = -search(pos, ss, -alpha, newDepth, 1, true, 0); + value = -search(pos, ss, -alpha, newDepth, 1, ALLOW_NULLMOVE, 0); // If we are above alpha then research at same depth but as PV // to get a correct score or eventually a fail high above beta. @@ -1126,14 +1104,13 @@ namespace { tte = TT.retrieve(pos.get_key()); } - // Step 10. Loop through moves - // Loop through all legal moves until no moves remain or a beta cutoff occurs - // Initialize a MovePicker object for the current position mateThreat = pos.has_mate_threat(opposite_color(pos.side_to_move())); MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]); CheckInfo ci(pos); + // Step 10. Loop through moves + // Loop through all legal moves until no moves remain or a beta cutoff occurs while ( alpha < beta && (move = mp.get_next_move()) != MOVE_NONE && !TM.thread_should_stop(threadID)) @@ -1161,7 +1138,7 @@ namespace { if (abs(ttValue) < VALUE_KNOWN_WIN) { - Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move); + Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, FORBID_NULLMOVE, threadID, move); if (excValue < ttValue - SingularExtensionMargin) ext = OnePly; @@ -1197,7 +1174,7 @@ namespace { ss[ply].reduction = pv_reduction(depth, moveCount); if (ss[ply].reduction) { - value = -search(pos, ss, -alpha, newDepth-ss[ply].reduction, ply+1, true, threadID); + value = -search(pos, ss, -alpha, newDepth-ss[ply].reduction, ply+1, ALLOW_NULLMOVE, threadID); doFullDepthSearch = (value > alpha); } } @@ -1206,7 +1183,7 @@ namespace { if (doFullDepthSearch) { ss[ply].reduction = Depth(0); - value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID); + value = -search(pos, ss, -alpha, newDepth, ply+1, ALLOW_NULLMOVE, threadID); // Step extra. pv search (only in PV nodes) if (value > alpha && value < beta) @@ -1281,7 +1258,7 @@ namespace { // search() is the search function for zero-width nodes. Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, - int ply, bool allowNullmove, int threadID, Move excludedMove) { + int ply, NullStatus nullStatus, int threadID, Move excludedMove) { assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); assert(ply >= 0 && ply < PLY_MAX); @@ -1329,7 +1306,7 @@ namespace { tte = TT.retrieve(posKey); ttMove = (tte ? tte->move() : MOVE_NONE); - if (tte && ok_to_use_TT(tte, depth, beta, ply)) + if (tte && ok_to_use_TT(tte, depth, beta, ply, nullStatus != VERIFY_NULLMOVE)) { ss[ply].currentMove = ttMove; // Can be MOVE_NONE return value_from_tt(tte->value(), ply); @@ -1350,12 +1327,12 @@ namespace { } // Step 6. Razoring - if ( !value_is_mate(beta) + if ( refinedValue < beta - razor_margin(depth) + && ttMove == MOVE_NONE + && ss[ply - 1].currentMove != MOVE_NULL + && depth < RazorDepth && !isCheck - && depth < RazorDepth - && refinedValue < beta - razor_margin(depth) - && ss[ply - 1].currentMove != MOVE_NULL - && ttMove == MOVE_NONE + && !value_is_mate(beta) && !pos.has_pawn_on_7th(pos.side_to_move())) { Value rbeta = beta - razor_margin(depth); @@ -1369,7 +1346,7 @@ namespace { // Step 7. Static null move pruning // We're betting that the opponent doesn't have a move that will reduce // the score by more than futility_margin(depth) if we do a null move. - if ( allowNullmove + if ( nullStatus == ALLOW_NULLMOVE && depth < RazorDepth && !isCheck && !value_is_mate(beta) @@ -1381,7 +1358,7 @@ namespace { // When we jump directly to qsearch() we do a null move only if static value is // at least beta. Otherwise we do a null move if static value is not more than // NullMoveMargin under beta. - if ( allowNullmove + if ( nullStatus == ALLOW_NULLMOVE && depth > OnePly && !isCheck && !value_is_mate(beta) @@ -1399,7 +1376,7 @@ namespace { pos.do_null_move(st); - nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID); + nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, FORBID_NULLMOVE, threadID); pos.undo_null_move(); @@ -1409,13 +1386,18 @@ namespace { if (nullValue >= value_mate_in(PLY_MAX)) nullValue = beta; - if (depth < 6 * OnePly) - return nullValue; + // Do zugzwang verification search for high depths, don't store in TT + // if search was stopped. + if ( ( depth < 6 * OnePly + || search(pos, ss, beta, depth-5*OnePly, ply, VERIFY_NULLMOVE, threadID) >= beta) + && !AbortSearch + && !TM.thread_should_stop(threadID)) + { + assert(value_to_tt(nullValue, ply) == nullValue); - // Do zugzwang verification search - Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID); - if (v >= beta) + TT.store(posKey, nullValue, VALUE_TYPE_NS_LO, depth, MOVE_NONE); return nullValue; + } } else { // The null move failed low, which means that we may be faced with // some kind of threat. If the previous move was reduced, check if @@ -1440,18 +1422,17 @@ namespace { && !isCheck && ss[ply].eval >= beta - IIDMargin) { - search(pos, ss, beta, depth/2, ply, false, threadID); + search(pos, ss, beta, depth/2, ply, FORBID_NULLMOVE, threadID); ttMove = ss[ply].pv[ply]; tte = TT.retrieve(posKey); } - // Step 10. Loop through moves - // Loop through all legal moves until no moves remain or a beta cutoff occurs - // Initialize a MovePicker object for the current position MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply], beta); CheckInfo ci(pos); + // Step 10. Loop through moves + // Loop through all legal moves until no moves remain or a beta cutoff occurs while ( bestValue < beta && (move = mp.get_next_move()) != MOVE_NONE && !TM.thread_should_stop(threadID)) @@ -1474,7 +1455,7 @@ namespace { if ( depth >= SingularExtensionDepthAtNonPVNodes && tte && move == tte->move() - && !excludedMove // Do not allow recursive single-reply search + && !excludedMove // Do not allow recursive singular extension search && ext < OnePly && is_lower_bound(tte->type()) && tte->depth() >= depth - 3 * OnePly) @@ -1483,7 +1464,7 @@ namespace { if (abs(ttValue) < VALUE_KNOWN_WIN) { - Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move); + Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, FORBID_NULLMOVE, threadID, move); if (excValue < ttValue - SingularExtensionMargin) ext = OnePly; @@ -1524,8 +1505,8 @@ namespace { // Step 13. Make the move pos.do_move(move, st, ci, moveIsCheck); - // Step 14. Reduced search - // if the move fails high will be re-searched at full depth. + // Step 14. Reduced search, if the move fails high + // will be re-searched at full depth. bool doFullDepthSearch = true; if ( depth >= 3*OnePly @@ -1537,7 +1518,7 @@ namespace { ss[ply].reduction = nonpv_reduction(depth, moveCount); if (ss[ply].reduction) { - value = -search(pos, ss, -(beta-1), newDepth-ss[ply].reduction, ply+1, true, threadID); + value = -search(pos, ss, -(beta-1), newDepth-ss[ply].reduction, ply+1, ALLOW_NULLMOVE, threadID); doFullDepthSearch = (value >= beta); } } @@ -1546,7 +1527,7 @@ namespace { if (doFullDepthSearch) { ss[ply].reduction = Depth(0); - value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID); + value = -search(pos, ss, -(beta-1), newDepth, ply+1, ALLOW_NULLMOVE, threadID); } // Step 16. Undo move @@ -1579,11 +1560,11 @@ namespace { } // Step 19. Check for mate and stalemate - // All legal moves have been searched and if there were + // All legal moves have been searched and if there are // no legal moves, it must be mate or stalemate. - // If one move was excluded return fail low. + // If one move was excluded return fail low score. if (!moveCount) - return excludedMove ? beta - 1 : (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW); + return excludedMove ? beta - 1 : (isCheck ? value_mated_in(ply) : VALUE_DRAW); // Step 20. Update tables // If the search is not aborted, update the transposition table, @@ -1651,7 +1632,7 @@ namespace { tte = TT.retrieve(pos.get_key()); ttMove = (tte ? tte->move() : MOVE_NONE); - if (!pvNode && tte && ok_to_use_TT(tte, depth, beta, ply)) + if (!pvNode && tte && ok_to_use_TT(tte, depth, beta, ply, true)) { assert(tte->type() != VALUE_TYPE_EVAL); @@ -1692,7 +1673,7 @@ namespace { alpha = bestValue; // If we are near beta then try to get a cutoff pushing checks a bit further - bool deepChecks = depth == -OnePly && staticValue >= beta - PawnValueMidgame / 8; + bool deepChecks = (depth == -OnePly && staticValue >= beta - PawnValueMidgame / 8); // Initialize a MovePicker object for the current position, and prepare // to search the moves. Because the depth is <= 0 here, only captures, @@ -1703,8 +1684,7 @@ namespace { enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame; futilityBase = staticValue + FutilityMarginQS + ei.futilityMargin[pos.side_to_move()]; - // Loop through the moves until no moves remain or a beta cutoff - // occurs. + // Loop through the moves until no moves remain or a beta cutoff occurs while ( alpha < beta && (move = mp.get_next_move()) != MOVE_NONE) { @@ -1739,7 +1719,7 @@ namespace { // Detect blocking evasions that are candidate to be pruned evasionPrunable = isCheck - && bestValue != -VALUE_INFINITE + && bestValue > value_mated_in(PLY_MAX) && !pos.move_is_capture(move) && pos.type_of_piece_on(move_from(move)) != KING && !pos.can_castle(pos.side_to_move()); @@ -1773,7 +1753,7 @@ namespace { // 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! + if (!moveCount && isCheck) // Mate! return value_mated_in(ply); // Update transposition table @@ -1897,7 +1877,7 @@ namespace { ss[sp->ply].reduction = nonpv_reduction(sp->depth, moveCount); if (ss[sp->ply].reduction) { - value = -search(pos, ss, -(sp->beta-1), newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID); + value = -search(pos, ss, -(sp->beta-1), newDepth-ss[sp->ply].reduction, sp->ply+1, ALLOW_NULLMOVE, threadID); doFullDepthSearch = (value >= sp->beta && !TM.thread_should_stop(threadID)); } } @@ -1906,7 +1886,7 @@ namespace { if (doFullDepthSearch) { ss[sp->ply].reduction = Depth(0); - value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, true, threadID); + value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, ALLOW_NULLMOVE, threadID); } // Step 16. Undo move @@ -2003,7 +1983,7 @@ namespace { if (ss[sp->ply].reduction) { Value localAlpha = sp->alpha; - value = -search(pos, ss, -localAlpha, newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID); + value = -search(pos, ss, -localAlpha, newDepth-ss[sp->ply].reduction, sp->ply+1, ALLOW_NULLMOVE, threadID); doFullDepthSearch = (value > localAlpha && !TM.thread_should_stop(threadID)); } } @@ -2013,7 +1993,7 @@ namespace { { Value localAlpha = sp->alpha; ss[sp->ply].reduction = Depth(0); - value = -search(pos, ss, -localAlpha, newDepth, sp->ply+1, true, threadID); + value = -search(pos, ss, -localAlpha, newDepth, sp->ply+1, ALLOW_NULLMOVE, threadID); if (value > localAlpha && value < sp->beta && !TM.thread_should_stop(threadID)) { @@ -2078,7 +2058,7 @@ namespace { NodesSincePoll++; if (NodesSincePoll >= NodesBetweenPolls) { - poll(ss, ply); + poll(); NodesSincePoll = 0; } } @@ -2333,14 +2313,18 @@ namespace { } - // ok_to_use_TT() returns true if a transposition table score - // can be used at a given point in search. + // ok_to_use_TT() returns true if a transposition table score can be used at a + // given point in search. To avoid zugzwang issues TT cutoffs at the root node + // of a null move verification search are not allowed if the TT value was found + // by a null search, this is implemented testing allowNullmove and TT entry type. - bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply) { + bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply, bool allowNullmove) { Value v = value_from_tt(tte->value(), ply); - return ( tte->depth() >= depth + return (allowNullmove || !(tte->type() & VALUE_TYPE_NULL)) + + && ( tte->depth() >= depth || v >= Max(value_mate_in(PLY_MAX), beta) || v < Min(value_mated_in(PLY_MAX), beta)) @@ -2441,7 +2425,7 @@ namespace { // looks at the time consumed so far and decides if it's time to abort the // search. - void poll(SearchStack ss[], int ply) { + void poll() { static int lastInfoTime; int t = current_search_time(); @@ -2492,16 +2476,6 @@ namespace { cout << "info nodes " << TM.nodes_searched() << " nps " << nps() << " time " << t << " hashfull " << TT.full() << endl; - - // We only support current line printing in single thread mode - if (ShowCurrentLine && TM.active_threads() == 1) - { - cout << "info currline"; - for (int p = 0; p < ply; p++) - cout << " " << ss[p].currentMove; - - cout << endl; - } } // Should we stop the search? @@ -2806,7 +2780,7 @@ namespace { } // Wait until the thread has finished launching and is gone to sleep - while (threads[i].state != THREAD_SLEEPING); + while (threads[i].state != THREAD_SLEEPING) {} } } @@ -2847,7 +2821,7 @@ namespace { SplitPoint* sp; - for (sp = threads[threadID].splitPoint; sp && !sp->stopRequest; sp = sp->parent); + for (sp = threads[threadID].splitPoint; sp && !sp->stopRequest; sp = sp->parent) {} return sp != NULL; }