X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=b08b687af2408f55d3690645963ae899db907fdd;hp=34fcc17637211029366f6868bb0bcf8d392cb971;hb=2e8552db76092a7e4fa8f7278231d66e26a756d9;hpb=1277a428237eec3299c6606951fac014bb3ef851 diff --git a/src/search.cpp b/src/search.cpp index 34fcc176..b08b687a 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -41,7 +41,7 @@ namespace Search { LimitsType Limits; RootMoveVector RootMoves; Position RootPos; - Time::point SearchTime; + TimePoint SearchTime; StateStackPtr SetupStates; } @@ -90,11 +90,51 @@ namespace { Move best = MOVE_NONE; }; + struct FastMove { + FastMove() { clear(); } + + inline void clear() { + expectedPosKey = 0; + pv3[0] = pv3[1] = pv3[2] = MOVE_NONE; + stableCnt = 0; + } + + void update(Position& pos) { + // Keep track how many times in a row the PV stays stable 3 ply deep. + const std::vector& RMpv = RootMoves[0].pv; + if (RMpv.size() >= 3) + { + if (pv3[2] == RMpv[2]) + stableCnt++; + else + stableCnt = 0, pv3[2] = RMpv[2]; + + if (!expectedPosKey || pv3[0] != RMpv[0] || pv3[1] != RMpv[1]) + { + pv3[0] = RMpv[0], pv3[1] = RMpv[1]; + StateInfo st[2]; + pos.do_move(RMpv[0], st[0], pos.gives_check(RMpv[0], CheckInfo(pos))); + pos.do_move(RMpv[1], st[1], pos.gives_check(RMpv[1], CheckInfo(pos))); + expectedPosKey = pos.key(); + pos.undo_move(RMpv[1]); + pos.undo_move(RMpv[0]); + } + } + else + clear(); + } + + Key expectedPosKey; + Move pv3[3]; + int stableCnt; + } FM; + size_t PVIdx; TimeManager TimeMgr; double BestMoveChanges; Value DrawValue[COLOR_NB]; HistoryStats History; + CounterMovesHistoryStats CounterMovesHistory; GainsStats Gains; MovesStats Countermoves, Followupmoves; @@ -158,7 +198,7 @@ uint64_t Search::perft(Position& pos, Depth depth) { cnt = 1, nodes++; else { - pos.do_move(m, st, ci, pos.gives_check(m, ci)); + pos.do_move(m, st, pos.gives_check(m, ci)); cnt = leaf ? MoveList(pos).size() : perft(pos, depth - ONE_PLY); nodes += cnt; pos.undo_move(m); @@ -280,6 +320,10 @@ namespace { Depth depth; Value bestValue, alpha, beta, delta; + // Init fastMove if the previous search generated a candidate and we now got the predicted position. + const Move fastMove = (FM.expectedPosKey == pos.key()) ? FM.pv3[2] : MOVE_NONE; + FM.clear(); + std::memset(ss-2, 0, 5 * sizeof(Stack)); depth = DEPTH_ZERO; @@ -289,6 +333,7 @@ namespace { TT.new_search(); History.clear(); + CounterMovesHistory.clear(); Gains.clear(); Countermoves.clear(); Followupmoves.clear(); @@ -355,7 +400,7 @@ namespace { // the UI) before a re-search. if ( multiPV == 1 && (bestValue <= alpha || bestValue >= beta) - && Time::now() - SearchTime > 3000) + && now() - SearchTime > 3000) sync_cout << UCI::pv(pos, depth, alpha, beta) << sync_endl; // In case of failing low/high increase aspiration window and @@ -386,9 +431,9 @@ namespace { if (Signals.stop) sync_cout << "info nodes " << RootPos.nodes_searched() - << " time " << Time::now() - SearchTime << sync_endl; + << " time " << now() - SearchTime << sync_endl; - else if (PVIdx + 1 == multiPV || Time::now() - SearchTime > 3000) + else if (PVIdx + 1 == multiPV || now() - SearchTime > 3000) sync_cout << UCI::pv(pos, depth, alpha, beta) << sync_endl; } @@ -403,27 +448,43 @@ 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 - || Time::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) + TimeMgr.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 a fastMove + // from the previous search and just did a fast verification. + if ( RootMoves.size() == 1 + || now() - SearchTime > TimeMgr.available_time() + || ( fastMove == RootMoves[0].pv[0] + && BestMoveChanges < 0.03 + && 10 * (now() - SearchTime) > TimeMgr.available_time())) + { + // 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; + } } + + // Update fast move stats. + FM.update(pos); } } + // Clear any candidate fast move that wasn't completely stable for at least + // the 6 final search iterations. (Independent of actual depth and thus TC.) + // Time condition prevents consecutive fast moves. + if (FM.stableCnt < 6 || now() - SearchTime < TimeMgr.available_time()) + FM.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(), @@ -687,14 +748,14 @@ 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) if (pos.legal(move, ci.pinned)) { ss->currentMove = move; - pos.do_move(move, st, ci, pos.gives_check(move, ci)); + pos.do_move(move, st, pos.gives_check(move, ci)); value = -search(pos, ss+1, -rbeta, -rbeta+1, rdepth, !cutNode); pos.undo_move(move); if (value >= rbeta) @@ -726,7 +787,7 @@ moves_loop: // When in check and at SpNode search starts from here Move followupmoves[] = { Followupmoves[pos.piece_on(prevOwnMoveSq)][prevOwnMoveSq].first, Followupmoves[pos.piece_on(prevOwnMoveSq)][prevOwnMoveSq].second }; - MovePicker mp(pos, ttMove, depth, History, countermoves, followupmoves, ss); + MovePicker mp(pos, ttMove, depth, History, CounterMovesHistory, countermoves, followupmoves, ss); CheckInfo ci(pos); value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc improving = ss->staticEval >= (ss-2)->staticEval @@ -765,7 +826,7 @@ 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 +835,7 @@ moves_loop: // When in check and at SpNode search starts from here { Signals.firstRootMove = (moveCount == 1); - if (thisThread == Threads.main() && Time::now() - SearchTime > 3000) + if (thisThread == Threads.main() && now() - SearchTime > 3000) sync_cout << "info depth " << depth / ONE_PLY << " currmove " << UCI::move(move, pos.is_chess960()) << " currmovenumber " << moveCount + PVIdx << sync_endl; @@ -834,7 +895,7 @@ 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 +914,7 @@ 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; } @@ -865,14 +926,14 @@ 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; } } // Speculative prefetch as early as possible - prefetch((char*)TT.first_entry(pos.key_after(move))); + prefetch(TT.first_entry(pos.key_after(move))); // Check for legality just before making the move if (!RootNode && !SpNode && !pos.legal(move, ci.pinned)) @@ -886,7 +947,7 @@ moves_loop: // When in check and at SpNode search starts from here quietsSearched[quietCount++] = move; // Step 14. Make the move - pos.do_move(move, st, ci, givesCheck); + pos.do_move(move, st, givesCheck); // Step 15. Reduced depth search (LMR). If the move fails high it will be // re-searched at full depth. @@ -965,7 +1026,7 @@ 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; } @@ -1010,6 +1071,10 @@ moves_loop: // When in check and at SpNode search starts from here if (value > alpha) { + // Clear fast move if unstable. + if (PvNode && pos.key() == FM.expectedPosKey && (move != FM.pv3[2] || moveCount > 1)) + FM.clear(); + bestMove = SpNode ? splitPoint->bestMove = move : move; if (PvNode && !RootNode) // Update pv even in fail-high case @@ -1034,7 +1099,9 @@ moves_loop: // When in check and at SpNode search starts from here && Threads.size() >= 2 && depth >= Threads.minimumSplitDepth && ( !thisThread->activeSplitPoint - || !thisThread->activeSplitPoint->allSlavesSearching) + || !thisThread->activeSplitPoint->allSlavesSearching + || ( Threads.size() > MAX_SLAVES_PER_SPLITPOINT + && thisThread->activeSplitPoint->slavesMask.count() == MAX_SLAVES_PER_SPLITPOINT)) && thisThread->splitPointsSize < MAX_SPLITPOINTS_PER_THREAD) { assert(bestValue > -VALUE_INFINITE && bestValue < beta); @@ -1190,7 +1257,7 @@ 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 @@ -1238,7 +1305,7 @@ moves_loop: // When in check and at SpNode search starts from here continue; // Speculative prefetch as early as possible - prefetch((char*)TT.first_entry(pos.key_after(move))); + prefetch(TT.first_entry(pos.key_after(move))); // Check for legality just before making the move if (!pos.legal(move, ci.pinned)) @@ -1247,7 +1314,7 @@ moves_loop: // When in check and at SpNode search starts from here ss->currentMove = move; // Make and search the move - pos.do_move(move, st, ci, givesCheck); + pos.do_move(move, st, givesCheck); value = givesCheck ? -qsearch(pos, ss+1, -beta, -alpha, depth - ONE_PLY) : -qsearch(pos, ss+1, -beta, -alpha, depth - ONE_PLY); pos.undo_move(move); @@ -1329,8 +1396,8 @@ 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, countermoves and followupmoves + // stats after a fail-high of a quiet move. void update_stats(const Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt) { @@ -1340,27 +1407,32 @@ 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); } 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); + Followupmoves.update(pos.piece_on(prevPrevSq), prevPrevSq, move); } } @@ -1371,7 +1443,7 @@ moves_loop: // When in check and at SpNode search starts from here Move Skill::pick_best(size_t multiPV) { // PRNG sequence should be non-deterministic, so we seed it with the time at init - static PRNG rng(Time::now()); + static PRNG rng(now()); // RootMoves are already sorted by score in descending order int variance = std::min(RootMoves[0].score - RootMoves[multiPV - 1].score, PawnValueMg); @@ -1405,7 +1477,7 @@ 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; - Time::point elapsed = Time::now() - SearchTime + 1; + TimePoint elapsed = now() - SearchTime + 1; size_t multiPV = std::min((size_t)Options["MultiPV"], RootMoves.size()); int selDepth = 0; @@ -1474,7 +1546,7 @@ void RootMove::insert_pv_in_tt(Position& pos) { if (!ttHit || tte->move() != m) // Don't overwrite correct entries tte->save(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE, m, VALUE_NONE, TT.generation()); - pos.do_move(m, *st++); + pos.do_move(m, *st++, pos.gives_check(m, CheckInfo(pos))); } for (size_t i = pv.size(); i > 0; ) @@ -1494,7 +1566,7 @@ bool RootMove::extract_ponder_from_tt(Position& pos) assert(pv.size() == 1); - pos.do_move(pv[0], st); + pos.do_move(pv[0], st, pos.gives_check(pv[0], CheckInfo(pos))); TTEntry* tte = TT.probe(pos.key(), ttHit); pos.undo_move(pv[0]); @@ -1515,21 +1587,38 @@ void Thread::idle_loop() { // Pointer 'this_sp' is not null only if we are called from split(), and not // at the thread creation. This means we are the split point's master. - SplitPoint* this_sp = splitPointsSize ? activeSplitPoint : nullptr; + SplitPoint* this_sp = activeSplitPoint; - assert(!this_sp || (this_sp->masterThread == this && searching)); + assert(!this_sp || (this_sp->master == this && searching)); - while (!exit) + while ( !exit + && !(this_sp && this_sp->slavesMask.none())) { + // If there is nothing to do, sleep. + while( !exit + && !(this_sp && this_sp->slavesMask.none()) + && !searching) + { + if ( !this_sp + && !Threads.main()->thinking) + { + std::unique_lock lk(mutex); + while (!exit && !Threads.main()->thinking) + sleepCondition.wait(lk); + } + else + std::this_thread::yield(); + } + // If this thread has been assigned work, launch a search while (searching) { - Threads.mutex.lock(); + spinlock.acquire(); assert(activeSplitPoint); SplitPoint* sp = activeSplitPoint; - Threads.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); @@ -1537,7 +1626,7 @@ 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); @@ -1563,66 +1652,69 @@ 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->masterThread - && sp->slavesMask.none()) - { - assert(!sp->masterThread->searching); - sp->masterThread->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. - if (Threads.size() > 2) - for (size_t i = 0; i < Threads.size(); ++i) + SplitPoint* bestSp = NULL; + int minLevel = INT_MAX; + + for (Thread* th : Threads) + { + const size_t size = th->splitPointsSize; // Local copy + sp = size ? &th->splitPoints[size - 1] : nullptr; + + if ( sp + && sp->allSlavesSearching + && sp->slavesMask.count() < MAX_SLAVES_PER_SPLITPOINT + && can_join(sp)) { - const int size = Threads[i]->splitPointsSize; // Local copy - sp = size ? &Threads[i]->splitPoints[size - 1] : nullptr; + assert(this != th); + assert(!(this_sp && this_sp->slavesMask.none())); + assert(Threads.size() > 2); - if ( sp - && sp->allSlavesSearching - && available_to(Threads[i])) + // Prefer to join to SP with few parents to reduce the probability + // that a cut-off occurs above us, and hence we waste our work. + int level = 0; + for (SplitPoint* p = th->activeSplitPoint; p; p = p->parentSplitPoint) + level++; + + if (level < minLevel) { - // Recheck the conditions under lock protection - Threads.mutex.lock(); - sp->mutex.lock(); - - if ( sp->allSlavesSearching - && available_to(Threads[i])) - { - sp->slavesMask.set(idx); - activeSplitPoint = sp; - searching = true; - } - - sp->mutex.unlock(); - Threads.mutex.unlock(); - - break; // Just a single attempt + bestSp = sp; + minLevel = level; } } - } + } - // Grab the lock to avoid races with Thread::notify_one() - std::unique_lock lk(mutex); + if (bestSp) + { + sp = bestSp; - // If we are master and all slaves have finished then exit idle_loop - if (this_sp && this_sp->slavesMask.none()) - { - assert(!searching); - break; - } + // Recheck the conditions under lock protection + sp->spinlock.acquire(); + + if ( sp->allSlavesSearching + && sp->slavesMask.count() < MAX_SLAVES_PER_SPLITPOINT) + { + spinlock.acquire(); + + if (can_join(sp)) + { + sp->slavesMask.set(idx); + activeSplitPoint = sp; + searching = true; + } + + spinlock.release(); + } - // 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); + sp->spinlock.release(); + } + } } } @@ -1633,12 +1725,12 @@ void Thread::idle_loop() { void check_time() { - static Time::point lastInfoTime = Time::now(); - Time::point elapsed = Time::now() - SearchTime; + static TimePoint lastInfoTime = now(); + TimePoint elapsed = now() - SearchTime; - if (Time::now() - lastInfoTime >= 1000) + if (now() - lastInfoTime >= 1000) { - lastInfoTime = Time::now(); + lastInfoTime = now(); dbg_print(); } @@ -1661,18 +1753,17 @@ void check_time() { else if (Limits.nodes) { - Threads.mutex.lock(); - int64_t nodes = RootPos.nodes_searched(); // Loop across all split points and sum accumulated SplitPoint nodes plus // all the currently active positions nodes. + // FIXME: Racy... for (Thread* th : Threads) - for (int i = 0; i < th->splitPointsSize; ++i) + for (size_t i = 0; i < th->splitPointsSize; ++i) { SplitPoint& sp = th->splitPoints[i]; - sp.mutex.lock(); + sp.spinlock.acquire(); nodes += sp.nodes; @@ -1680,11 +1771,9 @@ void check_time() { if (sp.slavesMask.test(idx) && Threads[idx]->activePosition) nodes += Threads[idx]->activePosition->nodes_searched(); - sp.mutex.unlock(); + sp.spinlock.release(); } - Threads.mutex.unlock(); - if (nodes >= Limits.nodes) Signals.stop = true; }