X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=ec884b3c145afc20dbcdff887e056ba671552827;hp=4c7e1e463dc553ae53c2efee850c215fb5f24223;hb=80f5ca88f6eaead0c5460c4bc13c1c7d9477c2be;hpb=ec0a650dff9ad78eff89e0c7fb04491f79fa7945 diff --git a/src/search.cpp b/src/search.cpp index 4c7e1e46..ec884b3c 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -104,13 +104,6 @@ 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 @@ -288,7 +281,7 @@ 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, NullStatus nullStatus, int threadID, Move excludedMove = MOVE_NONE); + Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, 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); @@ -301,7 +294,7 @@ 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 allowNullmove); + bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply); 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); @@ -567,7 +560,7 @@ void init_search() { for (int j = 0; j < 64; j++) // j == moveNumber { // FIXME: test using log instead of BSR - FutilityMarginsMatrix[i][j] = (i < 2 ? 0 : 112 * bitScanReverse32(i * i / 2)) - 8 * j; + FutilityMarginsMatrix[i][j] = (i < 2 ? 0 : 112 * bitScanReverse32(i * i / 2)) - 8 * j + 45; } // Init futility move count array @@ -893,7 +886,7 @@ namespace { if (ss[0].reduction) { // Reduced depth non-pv search using alpha as upperbound - value = -search(pos, ss, -alpha, newDepth-ss[0].reduction, 1, ALLOW_NULLMOVE, 0); + value = -search(pos, ss, -alpha, newDepth-ss[0].reduction, 1, true, 0); doFullDepthSearch = (value > alpha); } } @@ -903,7 +896,7 @@ namespace { { // Full depth non-pv search using alpha as upperbound ss[0].reduction = Depth(0); - value = -search(pos, ss, -alpha, newDepth, 1, ALLOW_NULLMOVE, 0); + value = -search(pos, ss, -alpha, newDepth, 1, true, 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. @@ -1138,7 +1131,7 @@ namespace { if (abs(ttValue) < VALUE_KNOWN_WIN) { - Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, FORBID_NULLMOVE, threadID, move); + Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move); if (excValue < ttValue - SingularExtensionMargin) ext = OnePly; @@ -1174,7 +1167,7 @@ namespace { ss[ply].reduction = pv_reduction(depth, moveCount); if (ss[ply].reduction) { - value = -search(pos, ss, -alpha, newDepth-ss[ply].reduction, ply+1, ALLOW_NULLMOVE, threadID); + value = -search(pos, ss, -alpha, newDepth-ss[ply].reduction, ply+1, true, threadID); doFullDepthSearch = (value > alpha); } } @@ -1183,7 +1176,7 @@ namespace { if (doFullDepthSearch) { ss[ply].reduction = Depth(0); - value = -search(pos, ss, -alpha, newDepth, ply+1, ALLOW_NULLMOVE, threadID); + value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID); // Step extra. pv search (only in PV nodes) if (value > alpha && value < beta) @@ -1258,7 +1251,7 @@ namespace { // search() is the search function for zero-width nodes. Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, - int ply, NullStatus nullStatus, int threadID, Move excludedMove) { + int ply, bool allowNullmove, int threadID, Move excludedMove) { assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); assert(ply >= 0 && ply < PLY_MAX); @@ -1306,8 +1299,11 @@ namespace { tte = TT.retrieve(posKey); ttMove = (tte ? tte->move() : MOVE_NONE); - if (tte && ok_to_use_TT(tte, depth, beta, ply, nullStatus != VERIFY_NULLMOVE)) + if (tte && ok_to_use_TT(tte, depth, beta, ply)) { + // Refresh tte entry to avoid aging + TT.store(posKey, tte->value(), tte->type(), tte->depth(), ttMove); + ss[ply].currentMove = ttMove; // Can be MOVE_NONE return value_from_tt(tte->value(), ply); } @@ -1346,7 +1342,7 @@ 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 ( nullStatus == ALLOW_NULLMOVE + if ( allowNullmove && depth < RazorDepth && !isCheck && !value_is_mate(beta) @@ -1358,7 +1354,7 @@ 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 ( nullStatus == ALLOW_NULLMOVE + if ( allowNullmove && depth > OnePly && !isCheck && !value_is_mate(beta) @@ -1376,7 +1372,7 @@ namespace { pos.do_null_move(st); - nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, FORBID_NULLMOVE, threadID); + nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID); pos.undo_null_move(); @@ -1386,20 +1382,13 @@ namespace { if (nullValue >= value_mate_in(PLY_MAX)) nullValue = beta; - // 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); - - if (!tte) - TT.store(posKey, nullValue, VALUE_TYPE_NS_LO, depth, MOVE_NONE); + if (depth < 6 * OnePly) + return nullValue; + // Do zugzwang verification search + Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID); + if (v >= beta) 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 @@ -1424,7 +1413,7 @@ namespace { && !isCheck && ss[ply].eval >= beta - IIDMargin) { - search(pos, ss, beta, depth/2, ply, FORBID_NULLMOVE, threadID); + search(pos, ss, beta, depth/2, ply, false, threadID); ttMove = ss[ply].pv[ply]; tte = TT.retrieve(posKey); } @@ -1466,7 +1455,7 @@ namespace { if (abs(ttValue) < VALUE_KNOWN_WIN) { - Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, FORBID_NULLMOVE, threadID, move); + Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move); if (excValue < ttValue - SingularExtensionMargin) ext = OnePly; @@ -1494,7 +1483,7 @@ namespace { // Value based pruning Depth predictedDepth = newDepth - nonpv_reduction(depth, moveCount); // We illogically ignore reduction condition depth >= 3*OnePly futilityValueScaled = ss[ply].eval + futility_margin(predictedDepth, moveCount) - + H.gain(pos.piece_on(move_from(move)), move_to(move)) + 45; + + H.gain(pos.piece_on(move_from(move)), move_to(move)); if (futilityValueScaled < beta) { @@ -1520,7 +1509,7 @@ namespace { ss[ply].reduction = nonpv_reduction(depth, moveCount); if (ss[ply].reduction) { - value = -search(pos, ss, -(beta-1), newDepth-ss[ply].reduction, ply+1, ALLOW_NULLMOVE, threadID); + value = -search(pos, ss, -(beta-1), newDepth-ss[ply].reduction, ply+1, true, threadID); doFullDepthSearch = (value >= beta); } } @@ -1529,7 +1518,7 @@ namespace { if (doFullDepthSearch) { ss[ply].reduction = Depth(0); - value = -search(pos, ss, -(beta-1), newDepth, ply+1, ALLOW_NULLMOVE, threadID); + value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID); } // Step 16. Undo move @@ -1634,7 +1623,7 @@ namespace { tte = TT.retrieve(pos.get_key()); ttMove = (tte ? tte->move() : MOVE_NONE); - if (!pvNode && tte && ok_to_use_TT(tte, depth, beta, ply, true)) + if (!pvNode && tte && ok_to_use_TT(tte, depth, beta, ply)) { assert(tte->type() != VALUE_TYPE_EVAL); @@ -1852,7 +1841,7 @@ namespace { // Value based pruning Depth predictedDepth = newDepth - nonpv_reduction(sp->depth, moveCount); futilityValueScaled = ss[sp->ply].eval + futility_margin(predictedDepth, moveCount) - + H.gain(pos.piece_on(move_from(move)), move_to(move)) + 45; + + H.gain(pos.piece_on(move_from(move)), move_to(move)); if (futilityValueScaled < sp->beta) { @@ -1879,7 +1868,7 @@ 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, ALLOW_NULLMOVE, threadID); + value = -search(pos, ss, -(sp->beta-1), newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID); doFullDepthSearch = (value >= sp->beta && !TM.thread_should_stop(threadID)); } } @@ -1888,7 +1877,7 @@ namespace { if (doFullDepthSearch) { ss[sp->ply].reduction = Depth(0); - value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, ALLOW_NULLMOVE, threadID); + value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, true, threadID); } // Step 16. Undo move @@ -1985,7 +1974,7 @@ namespace { if (ss[sp->ply].reduction) { Value localAlpha = sp->alpha; - value = -search(pos, ss, -localAlpha, newDepth-ss[sp->ply].reduction, sp->ply+1, ALLOW_NULLMOVE, threadID); + value = -search(pos, ss, -localAlpha, newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID); doFullDepthSearch = (value > localAlpha && !TM.thread_should_stop(threadID)); } } @@ -1995,7 +1984,7 @@ namespace { { Value localAlpha = sp->alpha; ss[sp->ply].reduction = Depth(0); - value = -search(pos, ss, -localAlpha, newDepth, sp->ply+1, ALLOW_NULLMOVE, threadID); + value = -search(pos, ss, -localAlpha, newDepth, sp->ply+1, true, threadID); if (value > localAlpha && value < sp->beta && !TM.thread_should_stop(threadID)) { @@ -2315,18 +2304,14 @@ namespace { } - // 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. + // ok_to_use_TT() returns true if a transposition table score + // can be used at a given point in search. - bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply, bool allowNullmove) { + bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply) { Value v = value_from_tt(tte->value(), ply); - return (allowNullmove || !(tte->type() & VALUE_TYPE_NULL)) - - && ( tte->depth() >= depth + return ( tte->depth() >= depth || v >= Max(value_mate_in(PLY_MAX), beta) || v < Min(value_mated_in(PLY_MAX), beta))