X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=34a478c54d33a7dc380d9a0c8505ef949a730915;hp=3a54bf01b0d4e9ac41632c8f03c40a1f2ce723b7;hb=486c8175c4f48381b137e3d914d38d9bb8c39ba2;hpb=002bf4d8dbf804ce8303e01733341a0922af2e71 diff --git a/src/search.cpp b/src/search.cpp index 3a54bf01..34a478c5 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -75,9 +75,6 @@ namespace { int FutilityMoveCounts[2][16]; // [improving][depth] int Reductions[2][2][64][64]; // [pv][improving][depth][moveNumber] - // Threshold used for countermoves based pruning - const int CounterMovePruneThreshold = 0; - template Depth reduction(bool i, Depth d, int mn) { return Reductions[PvNode][i][std::min(d / ONE_PLY, 63)][std::min(mn, 63)] * ONE_PLY; } @@ -90,56 +87,15 @@ namespace { // Skill structure is used to implement strength limit struct Skill { - Skill(int l) : level(l) {} + explicit Skill(int l) : level(l) {} bool enabled() const { return level < 20; } bool time_to_pick(Depth depth) const { return depth / ONE_PLY == 1 + level; } - Move best_move(size_t multiPV) { return best ? best : pick_best(multiPV); } Move pick_best(size_t multiPV); int level; Move best = MOVE_NONE; }; - // EasyMoveManager structure is used to detect an 'easy move'. When the PV is stable - // across multiple search iterations, we can quickly return the best move. - struct EasyMoveManager { - - void clear() { - stableCnt = 0; - expectedPosKey = 0; - pv[0] = pv[1] = pv[2] = MOVE_NONE; - } - - Move get(Key key) const { - return expectedPosKey == key ? pv[2] : MOVE_NONE; - } - - void update(Position& pos, const std::vector& newPv) { - - assert(newPv.size() >= 3); - - // Keep track of how many times in a row the 3rd ply remains stable - stableCnt = (newPv[2] == pv[2]) ? stableCnt + 1 : 0; - - if (!std::equal(newPv.begin(), newPv.begin() + 3, pv)) - { - std::copy(newPv.begin(), newPv.begin() + 3, pv); - - StateInfo st[2]; - pos.do_move(newPv[0], st[0]); - pos.do_move(newPv[1], st[1]); - expectedPosKey = pos.key(); - pos.undo_move(newPv[1]); - pos.undo_move(newPv[0]); - } - } - - Key expectedPosKey; - int stableCnt; - Move pv[3]; - }; - - EasyMoveManager EasyMove; Value DrawValue[COLOR_NB]; template @@ -153,6 +109,7 @@ namespace { void update_pv(Move* pv, Move move, Move* childPv); void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus); void update_stats(const Position& pos, Stack* ss, Move move, Move* quiets, int quietsCnt, int bonus); + bool pv_is_draw(Position& pos); // perft() is our utility to verify move generation. All the leaf nodes up // to the given depth are generated and counted, and the sum is returned. @@ -219,19 +176,11 @@ void Search::clear() { TT.clear(); for (Thread* th : Threads) - { - th->counterMoves.fill(MOVE_NONE); - th->mainHistory.fill(0); - - for (auto& to : th->contHistory) - for (auto& h : to) - h.fill(0); - - th->contHistory[NO_PIECE][0].fill(CounterMovePruneThreshold - 1); - } + th->clear(); Threads.main()->callsCnt = 0; Threads.main()->previousScore = VALUE_INFINITE; + Threads.main()->previousTimeReduction = 1; } @@ -271,11 +220,6 @@ void MainThread::search() { Thread::search(); // Let's start searching! } - // When playing in 'nodes as time' mode, subtract the searched nodes from - // the available ones before exiting. - if (Limits.npmsec) - Time.availableNodes += Limits.inc[us] - Threads.nodes_searched(); - // When we reach the maximum depth, we can arrive here without a raise of // Threads.stop. However, if we are pondering or in an infinite search, // the UCI protocol states that we shouldn't print the best move before the @@ -295,10 +239,14 @@ void MainThread::search() { if (th != this) th->wait_for_search_finished(); + // When playing in 'nodes as time' mode, subtract the searched nodes from + // the available ones before exiting. + if (Limits.npmsec) + Time.availableNodes += Limits.inc[us] - Threads.nodes_searched(); + // Check if there are threads with a better score than main thread Thread* bestThread = this; - if ( !this->easyMovePlayed - && Options["MultiPV"] == 1 + if ( Options["MultiPV"] == 1 && !Limits.depth && !Skill(Options["Skill Level"]).enabled() && rootMoves[0].pv[0] != MOVE_NONE) @@ -308,7 +256,9 @@ void MainThread::search() { Depth depthDiff = th->completedDepth - bestThread->completedDepth; Value scoreDiff = th->rootMoves[0].score - bestThread->rootMoves[0].score; - if (scoreDiff > 0 && depthDiff >= 0) + // Select the thread with the best score, always if it is a mate + if ( scoreDiff > 0 + && (depthDiff >= 0 || th->rootMoves[0].score >= VALUE_MATE_IN_MAX_PLY)) bestThread = th; } } @@ -334,10 +284,12 @@ void MainThread::search() { void Thread::search() { - Stack stack[MAX_PLY+7], *ss = stack+4; // To allow referencing (ss-4) and (ss+2) + Stack stack[MAX_PLY+7], *ss = stack+4; // To reference from (ss-4) to (ss+2) Value bestValue, alpha, beta, delta; - Move easyMove = MOVE_NONE; + Move lastBestMove = MOVE_NONE; + Depth lastBestMoveDepth = DEPTH_ZERO; MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr); + double timeReduction = 1.0; std::memset(ss-4, 0, 7 * sizeof(Stack)); for (int i = 4; i > 0; i--) @@ -348,9 +300,7 @@ void Thread::search() { if (mainThread) { - easyMove = EasyMove.get(rootPos.key()); - EasyMove.clear(); - mainThread->easyMovePlayed = mainThread->failedLow = false; + mainThread->failedLow = false; mainThread->bestMoveChanges = 0; } @@ -455,22 +405,18 @@ void Thread::search() { // Sort the PV lines searched so far and update the GUI std::stable_sort(rootMoves.begin(), rootMoves.begin() + PVIdx + 1); - if (!mainThread) - continue; - - if (Threads.stop || PVIdx + 1 == multiPV || Time.elapsed() > 3000) + if ( mainThread + && (Threads.stop || PVIdx + 1 == multiPV || Time.elapsed() > 3000)) sync_cout << UCI::pv(rootPos, rootDepth, alpha, beta) << sync_endl; } if (!Threads.stop) completedDepth = rootDepth; - if (!mainThread) - continue; - - // If skill level is enabled and time is up, pick a sub-optimal best move - if (skill.enabled() && skill.time_to_pick(rootDepth)) - skill.pick_best(multiPV); + if (rootMoves[0].pv[0] != lastBestMove) { + lastBestMove = rootMoves[0].pv[0]; + lastBestMoveDepth = rootDepth; + } // Have we found a "mate in x"? if ( Limits.mate @@ -478,27 +424,42 @@ void Thread::search() { && VALUE_MATE - bestValue <= 2 * Limits.mate) Threads.stop = true; + if (!mainThread) + continue; + + // If skill level is enabled and time is up, pick a sub-optimal best move + if (skill.enabled() && skill.time_to_pick(rootDepth)) + skill.pick_best(multiPV); + // Do we have time for the next iteration? Can we stop searching now? if (Limits.use_time_management()) { if (!Threads.stop && !Threads.stopOnPonderhit) { // Stop the search if only one legal move is available, or if all - // of the available time has been used, or if we matched an easyMove - // from the previous search and just did a fast verification. + // of the available time has been used const int F[] = { mainThread->failedLow, bestValue - mainThread->previousScore }; - int improvingFactor = std::max(229, std::min(715, 357 + 119 * F[0] - 6 * F[1])); - double unstablePvFactor = 1 + mainThread->bestMoveChanges; - bool doEasyMove = rootMoves[0].pv[0] == easyMove - && mainThread->bestMoveChanges < 0.03 - && Time.elapsed() > Time.optimum() * 5 / 44; + Color us = rootPos.side_to_move(); + bool thinkHard = DrawValue[us] == bestValue + && Limits.time[us] - Time.elapsed() > Limits.time[~us] + && ::pv_is_draw(rootPos); + + double unstablePvFactor = 1 + mainThread->bestMoveChanges + thinkHard; + + // if the bestMove is stable over several iterations, reduce time for this move, + // the longer the move has been stable, the more. + // Use part of the gained time from a previous stable move for the current move. + timeReduction = 1; + for (int i : {3, 4, 5}) + if (lastBestMoveDepth * i < completedDepth && !thinkHard) + timeReduction *= 1.3; + unstablePvFactor *= std::pow(mainThread->previousTimeReduction, 0.51) / timeReduction; if ( rootMoves.size() == 1 - || Time.elapsed() > Time.optimum() * unstablePvFactor * improvingFactor / 628 - || (mainThread->easyMovePlayed = doEasyMove, doEasyMove)) + || Time.elapsed() > Time.optimum() * unstablePvFactor * improvingFactor / 628) { // If we are allowed to ponder do not stop the search now but // keep pondering until the GUI sends "ponderhit" or "stop". @@ -508,26 +469,18 @@ void Thread::search() { Threads.stop = true; } } - - if (rootMoves[0].pv.size() >= 3) - EasyMove.update(rootPos, rootMoves[0].pv); - else - EasyMove.clear(); } } if (!mainThread) return; - // Clear any candidate easy move that wasn't stable for the last search - // iterations; the second condition prevents consecutive fast moves. - if (EasyMove.stableCnt < 6 || mainThread->easyMovePlayed) - EasyMove.clear(); + mainThread->previousTimeReduction = timeReduction; // If skill level is enabled, swap best PV line with the sub-optimal one if (skill.enabled()) - std::swap(rootMoves[0], *std::find(rootMoves.begin(), - rootMoves.end(), skill.best_move(multiPV))); + std::swap(rootMoves[0], *std::find(rootMoves.begin(), rootMoves.end(), + skill.best ? skill.best : skill.pick_best(multiPV))); } @@ -539,7 +492,7 @@ namespace { Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode, bool skipEarlyPruning) { const bool PvNode = NT == PV; - const bool rootNode = PvNode && (ss-1)->ply == 0; + const bool rootNode = PvNode && ss->ply == 0; assert(-VALUE_INFINITE <= alpha && alpha < beta && beta <= VALUE_INFINITE); assert(PvNode || (alpha == beta - 1)); @@ -555,7 +508,7 @@ namespace { Depth extension, newDepth; Value bestValue, value, ttValue, eval; bool ttHit, inCheck, givesCheck, singularExtensionNode, improving; - bool captureOrPromotion, doFullDepthSearch, moveCountPruning, skipQuiets, ttCapture; + bool captureOrPromotion, doFullDepthSearch, moveCountPruning, skipQuiets, ttCapture, pvExact; Piece movedPiece; int moveCount, quietCount; @@ -565,15 +518,14 @@ namespace { moveCount = quietCount = ss->moveCount = 0; ss->statScore = 0; bestValue = -VALUE_INFINITE; - ss->ply = (ss-1)->ply + 1; // Check for the available remaining time if (thisThread == Threads.main()) static_cast(thisThread)->check_time(); - // Used to send selDepth info to GUI - if (PvNode && thisThread->selDepth < ss->ply) - thisThread->selDepth = ss->ply; + // Used to send selDepth info to GUI (selDepth counts from 1, ply from 0) + if (PvNode && thisThread->selDepth < ss->ply + 1) + thisThread->selDepth = ss->ply + 1; if (!rootNode) { @@ -596,6 +548,7 @@ namespace { assert(0 <= ss->ply && ss->ply < MAX_PLY); + (ss+1)->ply = ss->ply + 1; ss->currentMove = (ss+1)->excludedMove = bestMove = MOVE_NONE; ss->contHistory = &thisThread->contHistory[NO_PIECE][0]; (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE; @@ -661,8 +614,8 @@ namespace { int drawScore = TB::UseRule50 ? 1 : 0; - value = v < -drawScore ? -VALUE_MATE + MAX_PLY + ss->ply - : v > drawScore ? VALUE_MATE - MAX_PLY - ss->ply + value = v < -drawScore ? -VALUE_MATE + MAX_PLY + ss->ply + 1 + : v > drawScore ? VALUE_MATE - MAX_PLY - ss->ply - 1 : VALUE_DRAW + 2 * v * drawScore; tte->save(posKey, value_to_tt(value, ss->ply), BOUND_EXACT, @@ -825,6 +778,7 @@ moves_loop: // When in check search starts from here && tte->depth() >= depth - 3 * ONE_PLY; skipQuiets = false; ttCapture = false; + pvExact = PvNode && ttHit && tte->bound() == BOUND_EXACT; // Step 11. Loop through moves // Loop through all pseudo-legal moves until no moves remain or a beta cutoff occurs @@ -965,6 +919,14 @@ moves_loop: // When in check search starts from here r -= r ? ONE_PLY : DEPTH_ZERO; else { + // Decrease reduction if opponent's move count is high + if ((ss-1)->moveCount > 15) + r -= ONE_PLY; + + // Decrease reduction for exact PV nodes + if (pvExact) + r -= ONE_PLY; + // Increase reduction if ttMove is a capture if (ttCapture) r += ONE_PLY; @@ -987,10 +949,10 @@ moves_loop: // When in check search starts from here - 4000; // Decrease/increase reduction by comparing opponent's stat score - if (ss->statScore > 0 && (ss-1)->statScore < 0) + if (ss->statScore >= 0 && (ss-1)->statScore < 0) r -= ONE_PLY; - else if (ss->statScore < 0 && (ss-1)->statScore > 0) + else if ((ss-1)->statScore >= 0 && ss->statScore < 0) r += ONE_PLY; // Decrease/increase reduction for moves with a good/bad history @@ -1172,7 +1134,7 @@ moves_loop: // When in check search starts from here } ss->currentMove = bestMove = MOVE_NONE; - ss->ply = (ss-1)->ply + 1; + (ss+1)->ply = ss->ply + 1; moveCount = 0; // Check for an instant draw or if the maximum ply has been reached @@ -1187,7 +1149,6 @@ moves_loop: // When in check search starts from here // only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS. ttDepth = InCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS; - // Transposition table lookup posKey = pos.key(); tte = TT.probe(posKey, ttHit); @@ -1432,6 +1393,24 @@ moves_loop: // When in check search starts from here } + // Is the PV leading to a draw position? Assumes all pv moves are legal + bool pv_is_draw(Position& pos) { + + StateInfo st[MAX_PLY]; + auto& pv = pos.this_thread()->rootMoves[0].pv; + + for (size_t i = 0; i < pv.size(); ++i) + pos.do_move(pv[i], st[i]); + + bool isDraw = pos.is_draw(pv.size()); + + for (size_t i = pv.size(); i > 0; --i) + pos.undo_move(pv[i-1]); + + return isDraw; + } + + // When playing with strength handicap, choose best move among a set of RootMoves // using a statistical rule dependent on 'level'. Idea by Heinz van Saanen. @@ -1455,7 +1434,7 @@ moves_loop: // When in check search starts from here int push = ( weakness * int(topScore - rootMoves[i].score) + delta * (rng.rand() % weakness)) / 128; - if (rootMoves[i].score + push > maxScore) + if (rootMoves[i].score + push >= maxScore) { maxScore = rootMoves[i].score + push; best = rootMoves[i].pv[0]; @@ -1593,6 +1572,10 @@ void Tablebases::filter_root_moves(Position& pos, Search::RootMoves& rootMoves) ProbeDepth = Options["SyzygyProbeDepth"] * ONE_PLY; Cardinality = Options["SyzygyProbeLimit"]; + // Don't filter any moves if the user requested analysis on multiple + if (Options["MultiPV"] != 1) + return; + // Skip TB probing when no TB found: !TBLargest -> !TB::Cardinality if (Cardinality > MaxCardinality) {