X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;ds=sidebyside;f=src%2Fsearch.cpp;h=711680818a2ba4cbb61c7ee3a8d25338a34af07f;hb=7caa6cd3383cf90189a1947c9bdf9c6fea1172a6;hp=376705d1d4118e97ed3af675c5c243f5629dc0b5;hpb=4739037f967ac3c818907e89cc88c7b97021d027;p=stockfish diff --git a/src/search.cpp b/src/search.cpp index 376705d1..71168081 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -34,6 +34,10 @@ #include "tt.h" #include "uci.h" +#ifdef SYZYGY +#include "syzygy/tbprobe.h" +#endif + namespace Search { volatile SignalsType Signals; @@ -42,6 +46,12 @@ namespace Search { Position RootPos; Time::point SearchTime; StateStackPtr SetupStates; + int TBCardinality; + uint64_t TBHits; + bool RootInTB; + bool TB50MoveRule; + Depth TBProbeDepth; + Value TBScore; } using std::string; @@ -87,6 +97,7 @@ 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); @@ -180,6 +191,8 @@ template uint64_t Search::perft(Position& pos, Depth depth); void Search::think() { TimeMgr.init(Limits, RootPos.game_ply(), RootPos.side_to_move()); + TBHits = TBCardinality = 0; + RootInTB = false; int cf = Options["Contempt"] * PawnValueEg / 100; // From centipawns DrawValue[ RootPos.side_to_move()] = VALUE_DRAW - Value(cf); @@ -194,6 +207,60 @@ void Search::think() { } else { +#ifdef SYZYGY + // Check Tablebases at root + int piecesCnt = RootPos.total_piece_count(); + TBCardinality = Options["SyzygyProbeLimit"]; + TBProbeDepth = Options["SyzygyProbeDepth"] * ONE_PLY; + if (TBCardinality > Tablebases::TBLargest) + { + TBCardinality = Tablebases::TBLargest; + TBProbeDepth = 0 * ONE_PLY; + } + TB50MoveRule = Options["Syzygy50MoveRule"]; + + if (piecesCnt <= TBCardinality) + { + TBHits = RootMoves.size(); + + // If the current root position is in the tablebases then RootMoves + // contains only moves that preserve the draw or win. + RootInTB = Tablebases::root_probe(RootPos, TBScore); + + if (RootInTB) + { + TBCardinality = 0; // Do not probe tablebases during the search + + // It might be a good idea to mangle the hash key (xor it + // with a fixed value) in order to "clear" the hash table of + // the results of previous probes. However, that would have to + // be done from within the Position class, so we skip it for now. + + // Optional: decrease target time. + } + else // If DTZ tables are missing, use WDL tables as a fallback + { + // Filter out moves that do not preserve a draw or win + RootInTB = Tablebases::root_probe_wdl(RootPos, TBScore); + + // Only probe during search if winning + if (TBScore <= VALUE_DRAW) + TBCardinality = 0; + } + + if (!RootInTB) + { + TBHits = 0; + } + else if (!TB50MoveRule) + { + TBScore = TBScore > VALUE_DRAW ? VALUE_MATE - MAX_PLY - 1 + : TBScore < VALUE_DRAW ? -VALUE_MATE + MAX_PLY + 1 + : TBScore; + } + } +#endif + for (size_t i = 0; i < Threads.size(); ++i) Threads[i]->maxPly = 0; @@ -216,9 +283,12 @@ 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 +325,7 @@ 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 +464,7 @@ 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 +535,8 @@ 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 +552,39 @@ namespace { return ttValue; } +#ifdef SYZYGY + // Step 4a. Tablebase probe + if ( !RootNode + && pos.total_piece_count() <= TBCardinality + && ( pos.total_piece_count() < TBCardinality || depth >= TBProbeDepth ) + && pos.rule50_count() == 0) + { + int found, v = Tablebases::probe_wdl(pos, &found); + + if (found) + { + TBHits++; + + if (TB50MoveRule) { + value = v < -1 ? -VALUE_MATE + MAX_PLY + ss->ply + : v > 1 ? VALUE_MATE - MAX_PLY - ss->ply + : VALUE_DRAW + 2 * v; + } + else + { + value = v < 0 ? -VALUE_MATE + MAX_PLY + ss->ply + : v > 0 ? VALUE_MATE - MAX_PLY - ss->ply + : VALUE_DRAW; + } + + 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; + } + } +#endif + // Step 5. Evaluate the position statically and update parent's gain statistics if (inCheck) { @@ -865,14 +964,17 @@ 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 +1003,11 @@ 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 +1030,8 @@ 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 +1117,7 @@ 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 +1126,11 @@ 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 +1154,7 @@ 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 +1281,8 @@ 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 +1340,15 @@ 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 +1362,7 @@ 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(int(depth) * int(depth)); History.update(pos.moved_piece(move), to_sq(move), bonus); for (int i = 0; i < quietsCnt; ++i) { @@ -1341,15 +1451,25 @@ moves_loop: // When in check and at SpNode search starts from here Depth d = updated ? depth : depth - ONE_PLY; Value v = updated ? RootMoves[i].score : RootMoves[i].prevScore; + bool tb = RootInTB; + if (tb) + { + if (abs(v) >= VALUE_MATE - MAX_PLY) + tb = false; + else + v = TBScore; + } + 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 " << TBHits << " time " << elapsed << " pv"; @@ -1371,15 +1491,17 @@ 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 +1645,11 @@ 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