X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=5ea00331b9bd85b012f66f473295c092e0808066;hp=376705d1d4118e97ed3af675c5c243f5629dc0b5;hb=ba1464751d1186f723a2d2a5d18c06ddfc9a4cb3;hpb=4739037f967ac3c818907e89cc88c7b97021d027 diff --git a/src/search.cpp b/src/search.cpp index 376705d1..5ea00331 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -33,17 +33,30 @@ #include "thread.h" #include "tt.h" #include "uci.h" +#include "syzygy/tbprobe.h" namespace Search { volatile SignalsType Signals; LimitsType Limits; - std::vector RootMoves; + RootMoveVector RootMoves; Position RootPos; Time::point SearchTime; StateStackPtr SetupStates; } +namespace Tablebases { + + int Cardinality; + uint64_t Hits; + bool RootInTB; + bool UseRule50; + Depth ProbeDepth; + Value Score; +} + +namespace TB = Tablebases; + using std::string; using Eval::evaluate; using namespace Search; @@ -87,6 +100,7 @@ namespace { void id_loop(Position& pos); Value value_to_tt(Value v, int ply); Value value_from_tt(Value v, int ply); + void update_pv(Move* pv, Move move, Move* childPv); void update_stats(const Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt); string uci_pv(const Position& pos, Depth depth, Value alpha, Value beta); @@ -101,7 +115,7 @@ namespace { } size_t candidates_size() const { return candidates; } - bool time_to_pick(Depth depth) const { return depth == 1 + level; } + bool time_to_pick(Depth depth) const { return depth / ONE_PLY == 1 + level; } Move pick_move(); int level; @@ -185,6 +199,19 @@ void Search::think() { DrawValue[ RootPos.side_to_move()] = VALUE_DRAW - Value(cf); DrawValue[~RootPos.side_to_move()] = VALUE_DRAW + Value(cf); + TB::Hits = 0; + TB::RootInTB = false; + TB::UseRule50 = Options["Syzygy50MoveRule"]; + TB::ProbeDepth = Options["SyzygyProbeDepth"] * ONE_PLY; + TB::Cardinality = Options["SyzygyProbeLimit"]; + + // Skip TB probing when no TB found: !TBLargest -> !TB::Cardinality + if (TB::Cardinality > TB::MaxCardinality) + { + TB::Cardinality = TB::MaxCardinality; + TB::ProbeDepth = DEPTH_ZERO; + } + if (RootMoves.empty()) { RootMoves.push_back(MOVE_NONE); @@ -194,6 +221,37 @@ void Search::think() { } else { + if (TB::Cardinality >= RootPos.count(WHITE) + + RootPos.count(BLACK)) + { + // If the current root position is in the tablebases then RootMoves + // contains only moves that preserve the draw or win. + TB::RootInTB = Tablebases::root_probe(RootPos, RootMoves, TB::Score); + + if (TB::RootInTB) + TB::Cardinality = 0; // Do not probe tablebases during the search + + else // If DTZ tables are missing, use WDL tables as a fallback + { + // Filter out moves that do not preserve a draw or win + TB::RootInTB = Tablebases::root_probe_wdl(RootPos, RootMoves, TB::Score); + + // Only probe during search if winning + if (TB::Score <= VALUE_DRAW) + TB::Cardinality = 0; + } + + if (TB::RootInTB) + { + TB::Hits = RootMoves.size(); + + if (!TB::UseRule50) + TB::Score = TB::Score > VALUE_DRAW ? VALUE_MATE - MAX_PLY - 1 + : TB::Score < VALUE_DRAW ? -VALUE_MATE + MAX_PLY + 1 + : VALUE_DRAW; + } + } + for (size_t i = 0; i < Threads.size(); ++i) Threads[i]->maxPly = 0; @@ -216,9 +274,12 @@ void Search::think() { RootPos.this_thread()->wait_for(Signals.stop); } - sync_cout << "bestmove " << UCI::format_move(RootMoves[0].pv[0], RootPos.is_chess960()) - << " ponder " << UCI::format_move(RootMoves[0].pv[1], RootPos.is_chess960()) - << sync_endl; + sync_cout << "bestmove " << UCI::format_move(RootMoves[0].pv[0], RootPos.is_chess960()); + + if (RootMoves[0].pv.size() > 1) + std::cout << " ponder " << UCI::format_move(RootMoves[0].pv[1], RootPos.is_chess960()); + + std::cout << sync_endl; } @@ -255,7 +316,7 @@ namespace { multiPV = std::max(multiPV, skill.candidates_size()); // Iterative deepening loop until requested to stop or target depth reached - while (++depth < MAX_PLY && !Signals.stop && (!Limits.depth || depth <= Limits.depth)) + while (++depth < DEPTH_MAX && !Signals.stop && (!Limits.depth || depth <= Limits.depth)) { // Age out PV variability metric BestMoveChanges *= 0.5; @@ -394,8 +455,7 @@ namespace { assert(PvNode || (alpha == beta - 1)); assert(depth > DEPTH_ZERO); - PVEntry pv; - Move quietsSearched[64]; + Move pv[MAX_PLY+1], quietsSearched[64]; StateInfo st; const TTEntry *tte; SplitPoint* splitPoint; @@ -466,11 +526,8 @@ namespace { ss->ttMove = ttMove = RootNode ? RootMoves[PVIdx].pv[0] : tte ? tte->move() : MOVE_NONE; ttValue = tte ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE; - // At PV nodes we check for exact scores, whilst at non-PV nodes we check for - // a fail high/low. The biggest advantage to probing at PV nodes is to have a - // smooth experience in analysis mode. We don't probe at Root nodes otherwise - // we should also update RootMoveList to avoid bogus output. - if ( !PvNode + // At non-PV nodes we check for a fail high/low. We don't probe at PV nodes + if ( !PvNode && tte && tte->depth() >= depth && ttValue != VALUE_NONE // Only in case of TT access race @@ -486,6 +543,36 @@ namespace { return ttValue; } + // Step 4a. Tablebase probe + if (!RootNode && TB::Cardinality) + { + int piecesCnt = pos.count(WHITE) + pos.count(BLACK); + + if ( piecesCnt <= TB::Cardinality + && (piecesCnt < TB::Cardinality || depth >= TB::ProbeDepth) + && pos.rule50_count() == 0) + { + int found, v = Tablebases::probe_wdl(pos, &found); + + if (found) + { + TB::Hits++; + + int drawScore = TB::UseRule50 ? 1 : 0; + + value = v < -drawScore ? -VALUE_MATE + MAX_PLY + ss->ply + : v > drawScore ? VALUE_MATE - MAX_PLY - ss->ply + : VALUE_DRAW + 2 * v * drawScore; + + TT.store(posKey, value_to_tt(value, ss->ply), BOUND_EXACT, + std::min(DEPTH_MAX - ONE_PLY, depth + 6 * ONE_PLY), + MOVE_NONE, VALUE_NONE); + + return value; + } + } + } + // Step 5. Evaluate the position statically and update parent's gain statistics if (inCheck) { @@ -561,7 +648,7 @@ namespace { assert(eval - beta >= 0); // Null move dynamic reduction based on depth and value - Depth R = (3 + depth / 4 + std::min(int(eval - beta) / PawnValueMg, 3)) * ONE_PLY; + Depth R = (3 + depth / 4 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY; pos.do_null_move(st); (ss+1)->skipNullMove = true; @@ -694,7 +781,7 @@ moves_loop: // When in check and at SpNode search starts from here Signals.firstRootMove = (moveCount == 1); if (thisThread == Threads.main() && Time::now() - SearchTime > 3000) - sync_cout << "info depth " << depth + sync_cout << "info depth " << depth / ONE_PLY << " currmove " << UCI::format_move(move, pos.is_chess960()) << " currmovenumber " << moveCount + PVIdx << sync_endl; } @@ -727,7 +814,7 @@ moves_loop: // When in check and at SpNode search starts from here && !ext && pos.legal(move, ci.pinned)) { - Value rBeta = ttValue - int(2 * depth); + Value rBeta = ttValue - 2 * depth / ONE_PLY; ss->excludedMove = move; ss->skipNullMove = true; value = search(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode); @@ -865,14 +952,17 @@ moves_loop: // When in check and at SpNode search starts from here // For PV nodes only, do a full PV search on the first move or after a fail // high (in the latter case search only if value < beta), otherwise let the // parent node fail low with value <= alpha and to try another move. - if (PvNode && (moveCount == 1 || (value > alpha && (RootNode || value < beta)))) { - pv.pv[0] = MOVE_NONE; - (ss+1)->pv = &pv; + if (PvNode && (moveCount == 1 || (value > alpha && (RootNode || value < beta)))) + { + (ss+1)->pv = pv; + (ss+1)->pv[0] = MOVE_NONE; + value = newDepth < ONE_PLY ? givesCheck ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) : -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) : - search(pos, ss+1, -beta, -alpha, newDepth, false); } + // Step 17. Undo move pos.undo_move(move); @@ -901,8 +991,11 @@ moves_loop: // When in check and at SpNode search starts from here { rm.score = value; rm.pv.resize(1); - for (int i = 0; (ss+1)->pv && i < MAX_PLY && (ss+1)->pv->pv[i] != MOVE_NONE; ++i) - rm.pv.push_back((ss+1)->pv->pv[i]); + + assert((ss+1)->pv); + + for (Move* m = (ss+1)->pv; *m != MOVE_NONE; ++m) + rm.pv.push_back(*m); // We record how often the best move has been changed in each // iteration. This information is used for time management: When @@ -925,11 +1018,8 @@ moves_loop: // When in check and at SpNode search starts from here { bestMove = SpNode ? splitPoint->bestMove = move : move; - if (NT == PV) { - ss->pv->update(move, (ss+1)->pv); - if (SpNode) - splitPoint->ss->pv->update(move, (ss+1)->pv); - } + if (PvNode && !RootNode) // Update pv even in fail-high case + update_pv(SpNode ? splitPoint->ss->pv : ss->pv, move, (ss+1)->pv); if (PvNode && value < beta) // Update alpha! Always alpha < beta alpha = SpNode ? splitPoint->alpha = value : value; @@ -1015,7 +1105,7 @@ moves_loop: // When in check and at SpNode search starts from here assert(PvNode || (alpha == beta - 1)); assert(depth <= DEPTH_ZERO); - PVEntry pv; + Move pv[MAX_PLY+1]; StateInfo st; const TTEntry* tte; Key posKey; @@ -1024,12 +1114,11 @@ moves_loop: // When in check and at SpNode search starts from here bool givesCheck, evasionPrunable; Depth ttDepth; - if (PvNode) { - // To flag BOUND_EXACT a node with eval above alpha and no available moves - oldAlpha = alpha; - - (ss+1)->pv = &pv; - ss->pv->pv[0] = MOVE_NONE; + if (PvNode) + { + oldAlpha = alpha; // To flag BOUND_EXACT when eval above alpha and no available moves + (ss+1)->pv = pv; + ss->pv[0] = MOVE_NONE; } ss->currentMove = bestMove = MOVE_NONE; @@ -1053,7 +1142,7 @@ moves_loop: // When in check and at SpNode search starts from here ttMove = tte ? tte->move() : MOVE_NONE; ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_NONE; - if ( !PvNode + if ( !PvNode && tte && tte->depth() >= ttDepth && ttValue != VALUE_NONE // Only in case of TT access race @@ -1180,8 +1269,8 @@ moves_loop: // When in check and at SpNode search starts from here if (value > alpha) { - if (PvNode) - ss->pv->update(move, &pv); + if (PvNode) // Update pv even in fail-high case + update_pv(ss->pv, move, (ss+1)->pv); if (PvNode && value < beta) // Update alpha here! Always alpha < beta { @@ -1239,6 +1328,15 @@ moves_loop: // When in check and at SpNode search starts from here } + // update_pv() adds current move and appends child pv[] + + void update_pv(Move* pv, Move move, Move* childPv) { + + for (*pv++ = move; childPv && *childPv != MOVE_NONE; ) + *pv++ = *childPv++; + *pv = MOVE_NONE; + } + // update_stats() updates killers, history, countermoves and followupmoves stats after a fail-high // of a quiet move. @@ -1252,7 +1350,7 @@ moves_loop: // When in check and at SpNode search starts from here // Increase history value of the cut-off move and decrease all the other // played quiet moves. - Value bonus = Value(4 * int(depth) * int(depth)); + Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY)); History.update(pos.moved_piece(move), to_sq(move), bonus); for (int i = 0; i < quietsCnt; ++i) { @@ -1335,21 +1433,25 @@ moves_loop: // When in check and at SpNode search starts from here { bool updated = (i <= PVIdx); - if (depth == 1 && !updated) + if (depth == ONE_PLY && !updated) continue; Depth d = updated ? depth : depth - ONE_PLY; Value v = updated ? RootMoves[i].score : RootMoves[i].prevScore; + bool tb = TB::RootInTB && abs(v) < VALUE_MATE - MAX_PLY; + v = tb ? TB::Score : v; + if (ss.rdbuf()->in_avail()) // Not at first line ss << "\n"; ss << "info depth " << d / ONE_PLY << " seldepth " << selDepth << " multipv " << i + 1 - << " score " << (i == PVIdx ? UCI::format_value(v, alpha, beta) : UCI::format_value(v)) + << " score " << ((!tb && i == PVIdx) ? UCI::format_value(v, alpha, beta) : UCI::format_value(v)) << " nodes " << pos.nodes_searched() << " nps " << pos.nodes_searched() * 1000 / elapsed + << " tbhits " << TB::Hits << " time " << elapsed << " pv"; @@ -1371,15 +1473,17 @@ void RootMove::insert_pv_in_tt(Position& pos) { StateInfo state[MAX_PLY], *st = state; const TTEntry* tte; - int idx = 0; + size_t idx = 0; - for (; idx < int(pv.size()); ++idx) { + for ( ; idx < pv.size(); ++idx) + { tte = TT.probe(pos.key()); if (!tte || tte->move() != pv[idx]) // Don't overwrite correct entries TT.store(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE, pv[idx], VALUE_NONE); assert(MoveList(pos).contains(pv[idx])); + pos.do_move(pv[idx], *st++); } @@ -1523,7 +1627,11 @@ void check_time() { dbg_print(); } - if (Limits.use_time_management() && !Limits.ponder) + // An engine may not stop pondering until told so by the GUI + if (Limits.ponder) + return; + + if (Limits.use_time_management()) { bool stillAtFirstMove = Signals.firstRootMove && !Signals.failedLowAtRoot