X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=7ab74998295aa864750a2643a9bd56a5cb6e3bd5;hp=f11388c595a162a1d77ddddb046d192bfd01945e;hb=f148a8f6ccbb57c440910ecfd4845c7f497b5404;hpb=50e094ef8db36ba1c1020b12594506f62532df17 diff --git a/src/search.cpp b/src/search.cpp index f11388c5..7ab74998 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -285,7 +285,7 @@ namespace { Value root_search(Position& pos, SearchStack* ss, RootMoveList& rml, Value* alphaPtr, Value* betaPtr); template - Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, bool allowNullmove, int threadID, Move excludedMove = MOVE_NONE); + Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID); template Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID); @@ -313,7 +313,7 @@ namespace { void poll(); void ponderhit(); void wait_for_stop_or_ponderhit(); - void init_ss_array(SearchStack* ss); + void init_ss_array(SearchStack* ss, int size); void print_pv_info(const Position& pos, SearchStack* ss, Value alpha, Value beta, Value value); #if !defined(_MSC_VER) @@ -337,6 +337,51 @@ void exit_threads() { TM.exit_threads(); } int64_t nodes_searched() { return TM.nodes_searched(); } +/// init_search() is called during startup. It initializes various lookup tables + +void init_search() { + + int d; // depth (OnePly == 2) + int hd; // half depth (OnePly == 1) + int mc; // moveCount + + // Init reductions array + for (hd = 1; hd < 64; hd++) for (mc = 1; mc < 64; mc++) + { + double pvRed = log(double(hd)) * log(double(mc)) / 3.0; + double nonPVRed = log(double(hd)) * log(double(mc)) / 1.5; + ReductionMatrix[PV][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(OnePly)) : 0); + ReductionMatrix[NonPV][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(OnePly)) : 0); + } + + // Init futility margins array + for (d = 0; d < 16; d++) for (mc = 0; mc < 64; mc++) + FutilityMarginsMatrix[d][mc] = 112 * int(log(double(d * d) / 2) / log(2.0) + 1) - 8 * mc + 45; + + // Init futility move count array + for (d = 0; d < 32; d++) + FutilityMoveCountArray[d] = 3 + (1 << (3 * d / 8)); +} + + +// SearchStack::init() initializes a search stack. Used at the beginning of a +// new search from the root. +void SearchStack::init(int ply) { + + pv[ply] = pv[ply + 1] = MOVE_NONE; + currentMove = threatMove = MOVE_NONE; + reduction = Depth(0); + eval = VALUE_NONE; +} + +void SearchStack::initKillers() { + + mateKiller = MOVE_NONE; + for (int i = 0; i < KILLER_MAX; i++) + killers[i] = MOVE_NONE; +} + + /// 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. @@ -549,51 +594,6 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move, } -/// 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 = log(double(i)) * log(double(j)) / 3.0; - double nonPVRed = log(double(i)) * log(double(j)) / 1.5; - ReductionMatrix[PV][i][j] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(OnePly)) : 0); - ReductionMatrix[NonPV][i][j] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(OnePly)) : 0); - } - - // Init futility margins array - for (int i = 0; i < 16; i++) // i == depth (OnePly = 2) - 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 + 45; - } - - // Init futility move count array - for (int i = 0; i < 32; i++) // i == depth (OnePly = 2) - FutilityMoveCountArray[i] = 3 + (1 << (3 * i / 8)); -} - - -// SearchStack::init() initializes a search stack. Used at the beginning of a -// new search from the root. -void SearchStack::init(int ply) { - - pv[ply] = pv[ply + 1] = MOVE_NONE; - currentMove = threatMove = MOVE_NONE; - reduction = Depth(0); - eval = VALUE_NONE; -} - -void SearchStack::initKillers() { - - mateKiller = MOVE_NONE; - for (int i = 0; i < KILLER_MAX; i++) - killers[i] = MOVE_NONE; -} - namespace { // id_loop() is the main iterative deepening loop. It calls root_search @@ -633,7 +633,7 @@ namespace { // Initialize TT.new_search(); H.clear(); - init_ss_array(ss); + init_ss_array(ss, PLY_MAX_PLUS_2); ValueByIteration[1] = rml.get_move_score(0); p.reset_ply(); Iteration = 1; @@ -876,7 +876,7 @@ namespace { alpha = -VALUE_INFINITE; // Full depth PV search, done on first move or after a fail high - value = -search(pos, ss+1, -beta, -alpha, newDepth, false, 0); + value = -search(pos, ss+1, -beta, -alpha, newDepth, 0); } else { @@ -893,7 +893,7 @@ namespace { if (ss->reduction) { // Reduced depth non-pv search using alpha as upperbound - value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, true, 0); + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, 0); doFullDepthSearch = (value > alpha); } } @@ -903,12 +903,12 @@ namespace { { // Full depth non-pv search using alpha as upperbound ss->reduction = Depth(0); - value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth, true, 0); + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth, 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. if (value > alpha) - value = -search(pos, ss+1, -beta, -alpha, newDepth, false, 0); + value = -search(pos, ss+1, -beta, -alpha, newDepth, 0); } } @@ -1031,8 +1031,7 @@ namespace { // search<>() is the main search function for both PV and non-PV nodes template - Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, - bool allowNullmove, int threadID, Move excludedMove) { + Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int threadID) { assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta > alpha && beta <= VALUE_INFINITE); @@ -1044,7 +1043,8 @@ namespace { EvalInfo ei; StateInfo st; const TTEntry* tte; - Move ttMove, move; + Key posKey; + Move ttMove, move, excludedMove; Depth ext, newDepth; Value bestValue, value, oldAlpha; Value refinedValue, nullValue, futilityValueScaled; // Non-PV specific @@ -1083,7 +1083,8 @@ namespace { // We don't want the score of a partial search to overwrite a previous full search // TT value, so we use a different position key in case of an excluded move exists. - Key posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key(); + excludedMove = ss->excludedMove; + posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key(); tte = TT.retrieve(posKey); ttMove = (tte ? tte->move() : MOVE_NONE); @@ -1144,7 +1145,7 @@ namespace { // 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 ( !PvNode - && allowNullmove + && !ss->skipNullMove && depth < RazorDepth && refinedValue >= beta + futility_margin(depth, 0) && !isCheck @@ -1157,7 +1158,7 @@ namespace { // at least beta. Otherwise we do a null move if static value is not more than // NullMoveMargin under beta. if ( !PvNode - && allowNullmove + && !ss->skipNullMove && depth > OnePly && refinedValue >= beta - (depth >= 4 * OnePly ? NullMoveMargin : 0) && !isCheck @@ -1175,8 +1176,13 @@ namespace { pos.do_null_move(st); + (ss+1)->skipNullMove = true; + nullValue = depth-R*OnePly < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), threadID) - : - search(pos, ss+1, -beta, -alpha, depth-R*OnePly, false, threadID); + : - search(pos, ss+1, -beta, -alpha, depth-R*OnePly, threadID); + + (ss+1)->skipNullMove = false; + pos.undo_null_move(); if (nullValue >= beta) @@ -1186,8 +1192,14 @@ namespace { nullValue = beta; // Do zugzwang verification search at high depths - if ( depth < 6 * OnePly - || search(pos, ss, alpha, beta, depth-5*OnePly, false, threadID) >= beta) + if (depth < 6 * OnePly) + return nullValue; + + ss->skipNullMove = true; + Value v = search(pos, ss, alpha, beta, depth-5*OnePly, threadID); + ss->skipNullMove = false; + + if (v >= beta) return nullValue; } else @@ -1215,7 +1227,11 @@ namespace { && (PvNode || (!isCheck && ss->eval >= beta - IIDMargin))) { Depth d = (PvNode ? depth - 2 * OnePly : depth / 2); - search(pos, ss, alpha, beta, d, false, threadID); + + ss->skipNullMove = true; + search(pos, ss, alpha, beta, d, threadID); + ss->skipNullMove = false; + ttMove = ss->pv[ply]; tte = TT.retrieve(posKey); } @@ -1263,7 +1279,11 @@ namespace { if (abs(ttValue) < VALUE_KNOWN_WIN) { Value b = ttValue - SingularExtensionMargin; - Value v = search(pos, ss, b - 1, b, depth / 2, false, threadID, move); + ss->excludedMove = move; + ss->skipNullMove = true; + Value v = search(pos, ss, b - 1, b, depth / 2, threadID); + ss->skipNullMove = false; + ss->excludedMove = MOVE_NONE; if (v < ttValue - SingularExtensionMargin) ext = OnePly; @@ -1311,7 +1331,7 @@ namespace { // The first move in list is the expected PV if (PvNode && moveCount == 1) value = newDepth < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), threadID) - : - search(pos, ss+1, -beta, -alpha, newDepth, false, threadID); + : - search(pos, ss+1, -beta, -alpha, newDepth, threadID); else { // Step 14. Reduced depth search @@ -1329,7 +1349,7 @@ namespace { { Depth d = newDepth - ss->reduction; value = d < OnePly ? -qsearch(pos, ss+1, -(alpha+1), -alpha, Depth(0), threadID) - : - search(pos, ss+1, -(alpha+1), -alpha, d, true, threadID); + : - search(pos, ss+1, -(alpha+1), -alpha, d, threadID); doFullDepthSearch = (value > alpha); } @@ -1342,7 +1362,7 @@ namespace { assert(newDepth - OnePly >= OnePly); ss->reduction = OnePly; - value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, true, threadID); + value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction, threadID); doFullDepthSearch = (value > alpha); } ss->reduction = Depth(0); // Restore original reduction @@ -1352,14 +1372,14 @@ namespace { if (doFullDepthSearch) { value = newDepth < OnePly ? -qsearch(pos, ss+1, -(alpha+1), -alpha, Depth(0), threadID) - : - search(pos, ss+1, -(alpha+1), -alpha, newDepth, true, threadID); + : - search(pos, ss+1, -(alpha+1), -alpha, newDepth, threadID); // Step extra. pv search (only in PV nodes) // Search only for possible new PV nodes, if instead value >= beta then // parent node fails low with value <= alpha and tries another move. if (PvNode && value > alpha && value < beta) value = newDepth < OnePly ? -qsearch(pos, ss+1, -beta, -alpha, Depth(0), threadID) - : - search(pos, ss+1, -beta, -alpha, newDepth, false, threadID); + : - search(pos, ss+1, -beta, -alpha, newDepth, threadID); } } @@ -1673,9 +1693,9 @@ namespace { // Step 12. Futility pruning (is omitted in PV nodes) if ( !PvNode + && !captureOrPromotion && !isCheck && !dangerous - && !captureOrPromotion && !move_is_castle(move)) { // Move count based pruning @@ -1709,8 +1729,8 @@ namespace { // If the move fails high will be re-searched at full depth. bool doFullDepthSearch = true; - if ( !dangerous - && !captureOrPromotion + if ( !captureOrPromotion + && !dangerous && !move_is_castle(move) && !move_is_killer(move, ss)) { @@ -1718,7 +1738,9 @@ namespace { if (ss->reduction) { Value localAlpha = sp->alpha; - value = -search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, true, threadID); + Depth d = newDepth - ss->reduction; + value = d < OnePly ? -qsearch(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0), threadID) + : - search(pos, ss+1, -(localAlpha+1), -localAlpha, d, threadID); doFullDepthSearch = (value > localAlpha); } @@ -1727,22 +1749,29 @@ namespace { // if the move fails high again then go with full depth search. if (doFullDepthSearch && ss->reduction > 2 * OnePly) { + assert(newDepth - OnePly >= OnePly); + ss->reduction = OnePly; Value localAlpha = sp->alpha; - value = -search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, true, threadID); + value = -search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth-ss->reduction, threadID); doFullDepthSearch = (value > localAlpha); } + ss->reduction = Depth(0); // Restore original reduction } // Step 15. Full depth search if (doFullDepthSearch) { - ss->reduction = Depth(0); Value localAlpha = sp->alpha; - value = -search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth, true, threadID); + value = newDepth < OnePly ? -qsearch(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0), threadID) + : - search(pos, ss+1, -(localAlpha+1), -localAlpha, newDepth, threadID); + // Step extra. pv search (only in PV nodes) + // Search only for possible new PV nodes, if instead value >= beta then + // parent node fails low with value <= alpha and tries another move. if (PvNode && value > localAlpha && value < sp->beta) - value = -search(pos, ss+1, -sp->beta, -sp->alpha, newDepth, false, threadID); + value = newDepth < OnePly ? -qsearch(pos, ss+1, -sp->beta, -sp->alpha, Depth(0), threadID) + : - search(pos, ss+1, -sp->beta, -sp->alpha, newDepth, threadID); } // Step 16. Undo move @@ -2204,14 +2233,21 @@ namespace { } - // init_ss_array() does a fast reset of the first entries of a SearchStack array + // init_ss_array() does a fast reset of the first entries of a SearchStack + // array and of all the excludedMove and skipNullMove entries. - void init_ss_array(SearchStack* ss) { + void init_ss_array(SearchStack* ss, int size) { - for (int i = 0; i < 3; i++, ss++) + for (int i = 0; i < size; i++, ss++) { - ss->init(i); - ss->initKillers(); + ss->excludedMove = MOVE_NONE; + ss->skipNullMove = false; + + if (i < 3) + { + ss->init(i); + ss->initKillers(); + } } } @@ -2743,7 +2779,7 @@ namespace { continue; // Find a quick score for the move - init_ss_array(ss); + init_ss_array(ss, PLY_MAX_PLUS_2); pos.do_move(cur->move, st); moves[count].move = cur->move; moves[count].score = -qsearch(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 0);