X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=8f074ca6923c6c21e68ceef098dd55dd5f63fa76;hp=501d6c60b447f5b132ddcc6ef3a307b47d8235dd;hb=27efc5ac996ffc679395317c8bbb16aca996296c;hpb=81c7975dcdf37ec96d308f800c2a40f6cb08907e diff --git a/src/search.cpp b/src/search.cpp index 501d6c60..8f074ca6 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -41,7 +41,6 @@ namespace Search { LimitsType Limits; RootMoveVector RootMoves; Position RootPos; - TimePoint SearchTime; StateStackPtr SetupStates; } @@ -90,13 +89,53 @@ namespace { Move best = MOVE_NONE; }; + // EasyMoveManager struct is used to detect a so called 'easy move'; when PV is + // stable across multiple search iterations we can fast 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 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.gives_check(newPv[0], CheckInfo(pos))); + pos.do_move(newPv[1], st[1], pos.gives_check(newPv[1], CheckInfo(pos))); + expectedPosKey = pos.key(); + pos.undo_move(newPv[1]); + pos.undo_move(newPv[0]); + } + } + + int stableCnt; + Key expectedPosKey; + Move pv[3]; + }; + size_t PVIdx; - TimeManager TimeMgr; + EasyMoveManager EasyMove; double BestMoveChanges; Value DrawValue[COLOR_NB]; HistoryStats History; + CounterMovesHistoryStats CounterMovesHistory; GainsStats Gains; - MovesStats Countermoves, Followupmoves; + MovesStats Countermoves; template Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode); @@ -178,11 +217,12 @@ template uint64_t Search::perft(Position& pos, Depth depth); void Search::think() { - TimeMgr.init(Limits, RootPos.side_to_move(), RootPos.game_ply()); + Color us = RootPos.side_to_move(); + Time.init(Limits, us, RootPos.game_ply(), now()); int contempt = Options["Contempt"] * PawnValueEg / 100; // From centipawns - DrawValue[ RootPos.side_to_move()] = VALUE_DRAW - Value(contempt); - DrawValue[~RootPos.side_to_move()] = VALUE_DRAW + Value(contempt); + DrawValue[ us] = VALUE_DRAW - Value(contempt); + DrawValue[~us] = VALUE_DRAW + Value(contempt); TB::Hits = 0; TB::RootInTB = false; @@ -238,16 +278,24 @@ void Search::think() { } for (Thread* th : Threads) + { th->maxPly = 0; + th->notify_one(); // Wake up all the threads + } Threads.timer->run = true; - Threads.timer->notify_one(); // Wake up the recurring timer + Threads.timer->notify_one(); // Start the recurring timer id_loop(RootPos); // Let's start searching ! Threads.timer->run = false; } + // When playing in 'nodes as time' mode, subtract the searched nodes from + // the available ones before to exit. + if (Limits.npmsec) + Time.availableNodes += Limits.inc[us] - RootPos.nodes_searched(); + // When we reach the maximum depth, we can arrive here without a raise of // Signals.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 @@ -280,6 +328,9 @@ namespace { Depth depth; Value bestValue, alpha, beta, delta; + Move easyMove = EasyMove.get(pos.key()); + EasyMove.clear(); + std::memset(ss-2, 0, 5 * sizeof(Stack)); depth = DEPTH_ZERO; @@ -289,9 +340,9 @@ namespace { TT.new_search(); History.clear(); + CounterMovesHistory.clear(); Gains.clear(); Countermoves.clear(); - Followupmoves.clear(); size_t multiPV = Options["MultiPV"]; Skill skill(Options["Skill Level"]); @@ -355,7 +406,7 @@ namespace { // the UI) before a re-search. if ( multiPV == 1 && (bestValue <= alpha || bestValue >= beta) - && now() - SearchTime > 3000) + && Time.elapsed() > 3000) sync_cout << UCI::pv(pos, depth, alpha, beta) << sync_endl; // In case of failing low/high increase aspiration window and @@ -386,9 +437,9 @@ namespace { if (Signals.stop) sync_cout << "info nodes " << RootPos.nodes_searched() - << " time " << now() - SearchTime << sync_endl; + << " time " << Time.elapsed() << sync_endl; - else if (PVIdx + 1 == multiPV || now() - SearchTime > 3000) + else if (PVIdx + 1 == multiPV || Time.elapsed() > 3000) sync_cout << UCI::pv(pos, depth, alpha, beta) << sync_endl; } @@ -403,27 +454,44 @@ namespace { Signals.stop = true; // Do we have time for the next iteration? Can we stop searching now? - if (Limits.use_time_management() && !Signals.stop && !Signals.stopOnPonderhit) + if (Limits.use_time_management()) { - // Take some extra time if the best move has changed - if (depth > 4 * ONE_PLY && multiPV == 1) - TimeMgr.pv_instability(BestMoveChanges); - - // Stop the search if only one legal move is available or all - // of the available time has been used. - if ( RootMoves.size() == 1 - || now() - SearchTime > TimeMgr.available_time()) + if (!Signals.stop && !Signals.stopOnPonderhit) { - // If we are allowed to ponder do not stop the search now but - // keep pondering until the GUI sends "ponderhit" or "stop". - if (Limits.ponder) - Signals.stopOnPonderhit = true; - else - Signals.stop = true; + // Take some extra time if the best move has changed + if (depth > 4 * ONE_PLY && multiPV == 1) + Time.pv_instability(BestMoveChanges); + + // Stop the search if only one legal move is available or all + // of the available time has been used or we matched an easyMove + // from the previous search and just did a fast verification. + if ( RootMoves.size() == 1 + || Time.elapsed() > Time.available() + || ( RootMoves[0].pv[0] == easyMove + && BestMoveChanges < 0.03 + && Time.elapsed() > Time.available() / 10)) + { + // If we are allowed to ponder do not stop the search now but + // keep pondering until the GUI sends "ponderhit" or "stop". + if (Limits.ponder) + Signals.stopOnPonderhit = true; + else + Signals.stop = true; + } } + + if (RootMoves[0].pv.size() >= 3) + EasyMove.update(pos, RootMoves[0].pv); + else + EasyMove.clear(); } } + // 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 || Time.elapsed() < Time.available()) + EasyMove.clear(); + // 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(), @@ -520,7 +588,7 @@ namespace { ss->ttMove = ttMove = RootNode ? RootMoves[PVIdx].pv[0] : ttHit ? tte->move() : MOVE_NONE; ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE; - // At non-PV nodes we check for a fail high/low. We don't probe at PV nodes + // At non-PV nodes we check for a fail high/low. We don't prune at PV nodes if ( !PvNode && ttHit && tte->depth() >= depth @@ -530,8 +598,8 @@ namespace { { ss->currentMove = ttMove; // Can be MOVE_NONE - // If ttMove is quiet, update killers, history, counter move and followup move on TT hit - if (ttValue >= beta && ttMove && !pos.capture_or_promotion(ttMove) && !inCheck) + // If ttMove is quiet, update killers, history, counter move on TT hit + if (ttValue >= beta && ttMove && !pos.capture_or_promotion(ttMove)) update_stats(pos, ss, ttMove, depth, nullptr, 0); return ttValue; @@ -687,7 +755,7 @@ namespace { assert((ss-1)->currentMove != MOVE_NONE); assert((ss-1)->currentMove != MOVE_NULL); - MovePicker mp(pos, ttMove, History, pos.captured_piece_type()); + MovePicker mp(pos, ttMove, History, CounterMovesHistory, pos.captured_piece_type()); CheckInfo ci(pos); while ((move = mp.next_move()) != MOVE_NONE) @@ -719,14 +787,9 @@ namespace { moves_loop: // When in check and at SpNode search starts from here Square prevMoveSq = to_sq((ss-1)->currentMove); - Move countermoves[] = { Countermoves[pos.piece_on(prevMoveSq)][prevMoveSq].first, - Countermoves[pos.piece_on(prevMoveSq)][prevMoveSq].second }; - - Square prevOwnMoveSq = to_sq((ss-2)->currentMove); - Move followupmoves[] = { Followupmoves[pos.piece_on(prevOwnMoveSq)][prevOwnMoveSq].first, - Followupmoves[pos.piece_on(prevOwnMoveSq)][prevOwnMoveSq].second }; + Move countermove = Countermoves[pos.piece_on(prevMoveSq)][prevMoveSq]; - MovePicker mp(pos, ttMove, depth, History, countermoves, followupmoves, ss); + MovePicker mp(pos, ttMove, depth, History, CounterMovesHistory, countermove, ss); CheckInfo ci(pos); value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc improving = ss->staticEval >= (ss-2)->staticEval @@ -765,7 +828,7 @@ moves_loop: // When in check and at SpNode search starts from here continue; moveCount = ++splitPoint->moveCount; - splitPoint->mutex.unlock(); + splitPoint->spinlock.release(); } else ++moveCount; @@ -774,7 +837,7 @@ moves_loop: // When in check and at SpNode search starts from here { Signals.firstRootMove = (moveCount == 1); - if (thisThread == Threads.main() && now() - SearchTime > 3000) + if (thisThread == Threads.main() && Time.elapsed() > 3000) sync_cout << "info depth " << depth / ONE_PLY << " currmove " << UCI::move(move, pos.is_chess960()) << " currmovenumber " << moveCount + PVIdx << sync_endl; @@ -834,7 +897,7 @@ moves_loop: // When in check and at SpNode search starts from here && moveCount >= FutilityMoveCounts[improving][depth]) { if (SpNode) - splitPoint->mutex.lock(); + splitPoint->spinlock.acquire(); continue; } @@ -853,7 +916,7 @@ moves_loop: // When in check and at SpNode search starts from here if (SpNode) { - splitPoint->mutex.lock(); + splitPoint->spinlock.acquire(); if (bestValue > splitPoint->bestValue) splitPoint->bestValue = bestValue; } @@ -865,7 +928,7 @@ moves_loop: // When in check and at SpNode search starts from here if (predictedDepth < 4 * ONE_PLY && pos.see_sign(move) < VALUE_ZERO) { if (SpNode) - splitPoint->mutex.lock(); + splitPoint->spinlock.acquire(); continue; } @@ -882,8 +945,6 @@ moves_loop: // When in check and at SpNode search starts from here } ss->currentMove = move; - if (!SpNode && !captureOrPromotion && quietCount < 64) - quietsSearched[quietCount++] = move; // Step 14. Make the move pos.do_move(move, st, givesCheck); @@ -899,10 +960,13 @@ moves_loop: // When in check and at SpNode search starts from here ss->reduction = reduction(improving, depth, moveCount); if ( (!PvNode && cutNode) - || History[pos.piece_on(to_sq(move))][to_sq(move)] < VALUE_ZERO) + || History[pos.piece_on(to_sq(move))][to_sq(move)] < VALUE_ZERO + || ( History[pos.piece_on(to_sq(move))][to_sq(move)] + + CounterMovesHistory[pos.piece_on(prevMoveSq)][prevMoveSq] + [pos.piece_on(to_sq(move))][to_sq(move)] < VALUE_ZERO)) ss->reduction += ONE_PLY; - if (move == countermoves[0] || move == countermoves[1]) + if (move == countermove) ss->reduction = std::max(DEPTH_ZERO, ss->reduction - ONE_PLY); // Decrease reduction for moves that escape a capture @@ -965,7 +1029,7 @@ moves_loop: // When in check and at SpNode search starts from here // Step 18. Check for new best move if (SpNode) { - splitPoint->mutex.lock(); + splitPoint->spinlock.acquire(); bestValue = splitPoint->bestValue; alpha = splitPoint->alpha; } @@ -1004,12 +1068,20 @@ moves_loop: // When in check and at SpNode search starts from here rm.score = -VALUE_INFINITE; } + bool newBestMove = false; if (value > bestValue) { bestValue = SpNode ? splitPoint->bestValue = value : value; if (value > alpha) { + // If there is an easy move for this position, clear it if unstable + if ( PvNode + && EasyMove.get(pos.key()) + && (move != EasyMove.get(pos.key()) || moveCount > 1)) + EasyMove.clear(); + + newBestMove = true; bestMove = SpNode ? splitPoint->bestMove = move : move; if (PvNode && !RootNode) // Update pv even in fail-high case @@ -1029,6 +1101,9 @@ moves_loop: // When in check and at SpNode search starts from here } } + if (!SpNode && !captureOrPromotion && !newBestMove && quietCount < 64) + quietsSearched[quietCount++] = move; + // Step 19. Check for splitting the search if ( !SpNode && Threads.size() >= 2 @@ -1071,9 +1146,9 @@ moves_loop: // When in check and at SpNode search starts from here bestValue = excludedMove ? alpha : inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()]; - // Quiet best move: update killers, history, countermoves and followupmoves - else if (bestValue >= beta && !pos.capture_or_promotion(bestMove) && !inCheck) - update_stats(pos, ss, bestMove, depth, quietsSearched, quietCount - 1); + // Quiet best move: update killers, history and countermoves + else if (bestMove != MOVE_NONE && !pos.capture_or_promotion(bestMove)) + update_stats(pos, ss, bestMove, depth, quietsSearched, quietCount); tte->save(posKey, value_to_tt(bestValue, ss->ply), bestValue >= beta ? BOUND_LOWER : @@ -1192,7 +1267,7 @@ moves_loop: // When in check and at SpNode search starts from here // to search the moves. Because the depth is <= 0 here, only captures, // queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will // be generated. - MovePicker mp(pos, ttMove, depth, History, to_sq((ss-1)->currentMove)); + MovePicker mp(pos, ttMove, depth, History, CounterMovesHistory, to_sq((ss-1)->currentMove)); CheckInfo ci(pos); // Loop through the moves until no moves remain or a beta cutoff occurs @@ -1230,8 +1305,7 @@ moves_loop: // When in check and at SpNode search starts from here // Detect non-capture evasions that are candidates to be pruned evasionPrunable = InCheck && bestValue > VALUE_MATED_IN_MAX_PLY - && !pos.capture(move) - && !pos.can_castle(pos.side_to_move()); + && !pos.capture(move); // Don't search moves with negative SEE values if ( (!InCheck || evasionPrunable) @@ -1331,8 +1405,7 @@ moves_loop: // When in check and at SpNode search starts from here *pv = MOVE_NONE; } - // update_stats() updates killers, history, countermoves and followupmoves stats after a fail-high - // of a quiet move. + // update_stats() updates killers, history, countermove history and countermoves stats for a quiet best move. void update_stats(const Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt) { @@ -1342,27 +1415,34 @@ moves_loop: // When in check and at SpNode search starts from here ss->killers[0] = move; } - // Increase history value of the cut-off move and decrease all the other - // played quiet moves. Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY)); + + Square prevSq = to_sq((ss-1)->currentMove); + HistoryStats& cmh = CounterMovesHistory[pos.piece_on(prevSq)][prevSq]; + History.update(pos.moved_piece(move), to_sq(move), bonus); - for (int i = 0; i < quietsCnt; ++i) + if (is_ok((ss-1)->currentMove)) { - Move m = quiets[i]; - History.update(pos.moved_piece(m), to_sq(m), -bonus); + Countermoves.update(pos.piece_on(prevSq), prevSq, move); + cmh.update(pos.moved_piece(move), to_sq(move), bonus); } - if (is_ok((ss-1)->currentMove)) + // Decrease all the other played quiet moves + for (int i = 0; i < quietsCnt; ++i) { - Square prevMoveSq = to_sq((ss-1)->currentMove); - Countermoves.update(pos.piece_on(prevMoveSq), prevMoveSq, move); + History.update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus); + + if (is_ok((ss-1)->currentMove)) + cmh.update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus); } + // Extra penalty for TT move in previous ply when it gets refuted if (is_ok((ss-2)->currentMove) && (ss-1)->currentMove == (ss-1)->ttMove) { - Square prevOwnMoveSq = to_sq((ss-2)->currentMove); - Followupmoves.update(pos.piece_on(prevOwnMoveSq), prevOwnMoveSq, move); + Square prevPrevSq = to_sq((ss-2)->currentMove); + HistoryStats& ttMoveCmh = CounterMovesHistory[pos.piece_on(prevPrevSq)][prevPrevSq]; + ttMoveCmh.update(pos.piece_on(prevSq), prevSq, -bonus - 2 * depth / ONE_PLY - 1); } } @@ -1407,7 +1487,7 @@ moves_loop: // When in check and at SpNode search starts from here string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) { std::stringstream ss; - TimePoint elapsed = now() - SearchTime + 1; + int elapsed = Time.elapsed() + 1; size_t multiPV = std::min((size_t)Options["MultiPV"], RootMoves.size()); int selDepth = 0; @@ -1521,17 +1601,17 @@ void Thread::idle_loop() { assert(!this_sp || (this_sp->master == this && searching)); - while (!exit) + while (!exit && !(this_sp && this_sp->slavesMask.none())) { // If this thread has been assigned work, launch a search while (searching) { - mutex.lock(); + spinlock.acquire(); assert(activeSplitPoint); SplitPoint* sp = activeSplitPoint; - mutex.unlock(); + spinlock.release(); Stack stack[MAX_PLY+4], *ss = stack+2; // To allow referencing (ss-2) and (ss+2) Position pos(*sp->pos, this); @@ -1539,7 +1619,7 @@ void Thread::idle_loop() { std::memcpy(ss-2, sp->ss-2, 5 * sizeof(Stack)); ss->splitPoint = sp; - sp->mutex.lock(); + sp->spinlock.acquire(); assert(activePosition == nullptr); @@ -1565,19 +1645,10 @@ void Thread::idle_loop() { sp->allSlavesSearching = false; sp->nodes += pos.nodes_searched(); - // Wake up the master thread so to allow it to return from the idle - // loop in case we are the last slave of the split point. - if (this != sp->master && sp->slavesMask.none()) - { - assert(!sp->master->searching); - - sp->master->notify_one(); - } - // After releasing the lock we can't access any SplitPoint related data // in a safe way because it could have been released under our feet by // the sp master. - sp->mutex.unlock(); + sp->spinlock.release(); // Try to late join to another split point if none of its slaves has // already finished. @@ -1617,12 +1688,12 @@ void Thread::idle_loop() { sp = bestSp; // Recheck the conditions under lock protection - sp->mutex.lock(); + sp->spinlock.acquire(); if ( sp->allSlavesSearching && sp->slavesMask.count() < MAX_SLAVES_PER_SPLITPOINT) { - mutex.lock(); + spinlock.acquire(); if (can_join(sp)) { @@ -1631,27 +1702,24 @@ void Thread::idle_loop() { searching = true; } - mutex.unlock(); + spinlock.release(); } - sp->mutex.unlock(); + sp->spinlock.release(); } } - // Avoid races with notify_one() fired from last slave of the split point - std::unique_lock lk(mutex); - - // If we are master and all slaves have finished then exit idle_loop - if (this_sp && this_sp->slavesMask.none()) + // If search is finished then sleep, otherwise just yield + if (!Threads.main()->thinking) { - assert(!searching); - break; - } + assert(!this_sp); - // If we are not searching, wait for a condition to be signaled instead of - // wasting CPU time polling for work. - if (!searching && !exit) - sleepCondition.wait(lk); + std::unique_lock lk(mutex); + while (!exit && !Threads.main()->thinking) + sleepCondition.wait(lk); + } + else + std::this_thread::yield(); // Wait for a new job or for our slaves to finish } } @@ -1663,7 +1731,7 @@ void Thread::idle_loop() { void check_time() { static TimePoint lastInfoTime = now(); - TimePoint elapsed = now() - SearchTime; + int elapsed = Time.elapsed(); if (now() - lastInfoTime >= 1000) { @@ -1679,10 +1747,10 @@ void check_time() { { bool stillAtFirstMove = Signals.firstRootMove && !Signals.failedLowAtRoot - && elapsed > TimeMgr.available_time() * 75 / 100; + && elapsed > Time.available() * 75 / 100; if ( stillAtFirstMove - || elapsed > TimeMgr.maximum_time() - 2 * TimerThread::Resolution) + || elapsed > Time.maximum() - 2 * TimerThread::Resolution) Signals.stop = true; } else if (Limits.movetime && elapsed >= Limits.movetime) @@ -1700,7 +1768,7 @@ void check_time() { { SplitPoint& sp = th->splitPoints[i]; - sp.mutex.lock(); + sp.spinlock.acquire(); nodes += sp.nodes; @@ -1708,7 +1776,7 @@ void check_time() { if (sp.slavesMask.test(idx) && Threads[idx]->activePosition) nodes += Threads[idx]->activePosition->nodes_searched(); - sp.mutex.unlock(); + sp.spinlock.release(); } if (nodes >= Limits.nodes)