X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=043c433a648cba38fb0bab2be01cf3a45b2d2385;hp=efdb287fa740a3325c73771f6b43492345b5dd5e;hb=abae3c5678897be39fd7a082543937f846dcfbd5;hpb=a4a0ffce711962c0b04b35998c3c06491be373bf diff --git a/src/search.cpp b/src/search.cpp index efdb287f..043c433a 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -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 @@ -257,7 +264,7 @@ namespace { int SearchStartTime, MaxNodes, MaxDepth, MaxSearchTime; int AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime; bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit; - bool FirstRootMove, AbortSearch, Quit, AspirationFailLow, ZugDetection; + bool FirstRootMove, AbortSearch, Quit, AspirationFailLow; // Log file bool UseLogFile; @@ -281,7 +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); @@ -387,7 +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) @@ -425,7 +432,6 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, MultiPV = get_option_value_int("MultiPV"); Chess960 = get_option_value_bool("UCI_Chess960"); UseLogFile = get_option_value_bool("Use Search Log"); - ZugDetection = get_option_value_bool("Zugzwang detection"); // To be removed after 1.7.1 if (UseLogFile) LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app); @@ -887,7 +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); } } @@ -897,7 +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. @@ -1132,7 +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; @@ -1168,7 +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); } } @@ -1177,7 +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) @@ -1252,7 +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); @@ -1300,7 +1306,7 @@ namespace { tte = TT.retrieve(posKey); ttMove = (tte ? tte->move() : MOVE_NONE); - if (tte && ok_to_use_TT(tte, depth, beta, ply, allowNullmove)) + 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); @@ -1340,7 +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) @@ -1352,7 +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) @@ -1370,7 +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(); @@ -1383,7 +1389,7 @@ namespace { // 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, false, threadID) >= beta) + || search(pos, ss, beta, depth-5*OnePly, ply, VERIFY_NULLMOVE, threadID) >= beta) && !AbortSearch && !TM.thread_should_stop(threadID)) { @@ -1416,7 +1422,7 @@ 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); } @@ -1458,7 +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; @@ -1512,7 +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); } } @@ -1521,7 +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 @@ -1713,7 +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()); @@ -1871,7 +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)); } } @@ -1880,7 +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 @@ -1977,7 +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)); } } @@ -1987,7 +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)) { @@ -2316,7 +2322,7 @@ namespace { Value v = value_from_tt(tte->value(), ply); - return (allowNullmove || !(tte->type() & VALUE_TYPE_NULL) || !ZugDetection) + return (allowNullmove || !(tte->type() & VALUE_TYPE_NULL)) && ( tte->depth() >= depth || v >= Max(value_mate_in(PLY_MAX), beta)