LimitsType Limits;
RootMoveVector RootMoves;
Position RootPos;
- Time::point SearchTime;
+ TimePoint SearchTime;
StateStackPtr SetupStates;
}
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<Move>& 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 <NodeType NT, bool SpNode>
Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode);
}
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 !
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;
TT.new_search();
History.clear();
+ CounterMovesHistory.clear();
Gains.clear();
Countermoves.clear();
- Followupmoves.clear();
size_t multiPV = Options["MultiPV"];
Skill skill(Options["Skill Level"]);
// 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
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;
}
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 an easyMove
+ // from the previous search and just did a fast verification.
+ if ( RootMoves.size() == 1
+ || now() - SearchTime > TimeMgr.available_time()
+ || ( RootMoves[0].pv[0] == easyMove
+ && BestMoveChanges < 0.03
+ && now() - SearchTime > TimeMgr.available_time() / 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 || now() - SearchTime < TimeMgr.available_time())
+ 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(),
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
{
ss->currentMove = ttMove; // Can be MOVE_NONE
- // If ttMove is quiet, update killers, history, counter move and followup move on TT hit
+ // If ttMove is quiet, update killers, history, counter move on TT hit
if (ttValue >= beta && ttMove && !pos.capture_or_promotion(ttMove) && !inCheck)
update_stats(pos, ss, ttMove, depth, nullptr, 0);
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<false>()) != MOVE_NONE)
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 };
-
- MovePicker mp(pos, ttMove, depth, History, countermoves, followupmoves, ss);
+ MovePicker mp(pos, ttMove, depth, History, CounterMovesHistory, countermoves, ss);
CheckInfo ci(pos);
value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
improving = ss->staticEval >= (ss-2)->staticEval
continue;
moveCount = ++splitPoint->moveCount;
- splitPoint->mutex.unlock();
+ splitPoint->spinlock.release();
}
else
++moveCount;
{
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;
&& moveCount >= FutilityMoveCounts[improving][depth])
{
if (SpNode)
- splitPoint->mutex.lock();
+ splitPoint->spinlock.acquire();
continue;
}
if (SpNode)
{
- splitPoint->mutex.lock();
+ splitPoint->spinlock.acquire();
if (bestValue > splitPoint->bestValue)
splitPoint->bestValue = bestValue;
}
if (predictedDepth < 4 * ONE_PLY && pos.see_sign(move) < VALUE_ZERO)
{
if (SpNode)
- splitPoint->mutex.lock();
+ splitPoint->spinlock.acquire();
continue;
}
ss->reduction = reduction<PvNode>(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])
// Step 18. Check for new best move
if (SpNode)
{
- splitPoint->mutex.lock();
+ splitPoint->spinlock.acquire();
bestValue = splitPoint->bestValue;
alpha = splitPoint->alpha;
}
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();
+
bestMove = SpNode ? splitPoint->bestMove = move : move;
if (PvNode && !RootNode) // Update pv even in fail-high case
bestValue = excludedMove ? alpha
: inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()];
- // Quiet best move: update killers, history, countermoves and followupmoves
+ // Quiet best move: update killers, history and countermoves
else if (bestValue >= beta && !pos.capture_or_promotion(bestMove) && !inCheck)
update_stats(pos, ss, bestMove, depth, quietsSearched, quietCount - 1);
// 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
*pv = MOVE_NONE;
}
- // update_stats() updates killers, history, countermoves and followupmoves stats after a fail-high
+ // update_stats() updates killers, history and countermoves 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) {
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);
}
}
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);
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;
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)
{
- 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);
std::memcpy(ss-2, sp->ss-2, 5 * sizeof(Stack));
ss->splitPoint = sp;
- sp->mutex.lock();
+ sp->spinlock.acquire();
assert(activePosition == nullptr);
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.
if ( sp
&& sp->allSlavesSearching
&& sp->slavesMask.count() < MAX_SLAVES_PER_SPLITPOINT
- && available_to(th))
+ && can_join(sp))
{
assert(this != th);
assert(!(this_sp && this_sp->slavesMask.none()));
sp = bestSp;
// Recheck the conditions under lock protection
- Threads.mutex.lock();
- sp->mutex.lock();
+ sp->spinlock.acquire();
if ( sp->allSlavesSearching
- && sp->slavesMask.count() < MAX_SLAVES_PER_SPLITPOINT
- && available_to(sp->master))
+ && sp->slavesMask.count() < MAX_SLAVES_PER_SPLITPOINT)
{
- sp->slavesMask.set(idx);
- activeSplitPoint = sp;
- searching = true;
+ spinlock.acquire();
+
+ if (can_join(sp))
+ {
+ sp->slavesMask.set(idx);
+ activeSplitPoint = sp;
+ searching = true;
+ }
+
+ spinlock.release();
}
- sp->mutex.unlock();
- Threads.mutex.unlock();
+ sp->spinlock.release();
}
}
- // Avoid races with notify_one() fired from last slave of the split point
- std::unique_lock<std::mutex> 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<Mutex> 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
}
}
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();
}
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 (size_t i = 0; i < th->splitPointsSize; ++i)
{
SplitPoint& sp = th->splitPoints[i];
- sp.mutex.lock();
+ sp.spinlock.acquire();
nodes += sp.nodes;
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;
}
projects / stockfish / blobdiff