};
EasyMoveManager EasyMove;
- double BestMoveChanges;
Value DrawValue[COLOR_NB];
CounterMovesHistoryStats CounterMovesHistory;
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);
+ void check_time();
} // namespace
}
-/// Search::reset() clears all search memory, to obtain reproducible search results
+/// Search::clear() resets to zero search state, to obtain reproducible results
-void Search::reset () {
+void Search::clear() {
TT.clear();
CounterMovesHistory.clear();
return nodes;
}
-template uint64_t Search::perft<true>(Position& pos, Depth depth);
+template uint64_t Search::perft<true>(Position&, Depth);
-/// MainThread::think() is called by the main thread when the program receives
+/// MainThread::search() is called by the main thread when the program receives
/// the UCI 'go' command. It searches from root position and at the end prints
/// the "bestmove" to output.
-void MainThread::think() {
+void MainThread::search() {
Color us = rootPos.side_to_move();
Time.init(Limits, us, rootPos.game_ply());
{
th->maxPly = 0;
th->rootDepth = DEPTH_ZERO;
- th->searching = true;
if (th != this)
{
th->rootPos = Position(rootPos, th);
th->rootMoves = rootMoves;
- th->notify_one(); // Wake up the thread and start searching
+ th->start_searching();
}
}
- Threads.timer->run = true;
- Threads.timer->notify_one(); // Start the recurring timer
-
- search(true); // Let's start searching!
-
- // Stop the threads and the timer
- Signals.stop = true;
- Threads.timer->run = false;
-
- // Wait until all threads have finished
- for (Thread* th : Threads)
- if (th != this)
- th->wait_while(th->searching);
+ Thread::search(); // Let's start searching!
}
// When playing in 'nodes as time' mode, subtract the searched nodes from
wait(Signals.stop);
}
- sync_cout << "bestmove " << UCI::move(rootMoves[0].pv[0], rootPos.is_chess960());
+ // Stop the threads if not already stopped
+ Signals.stop = true;
+
+ // Wait until all threads have finished
+ for (Thread* th : Threads)
+ if (th != this)
+ th->wait_for_search_finished();
+
+ // Check if there are threads with a better score than main thread
+ Thread* bestThread = this;
+ if ( !this->easyMovePlayed
+ && Options["MultiPV"] == 1
+ && !Skill(Options["Skill Level"]).enabled())
+ {
+ for (Thread* th : Threads)
+ if ( th->completedDepth > bestThread->completedDepth
+ && th->rootMoves[0].score > bestThread->rootMoves[0].score)
+ bestThread = th;
+ }
+
+ // Send new PV when needed
+ if (bestThread != this)
+ sync_cout << UCI::pv(bestThread->rootPos, bestThread->completedDepth, -VALUE_INFINITE, VALUE_INFINITE) << sync_endl;
+
+ sync_cout << "bestmove " << UCI::move(bestThread->rootMoves[0].pv[0], rootPos.is_chess960());
- if (rootMoves[0].pv.size() > 1 || rootMoves[0].extract_ponder_from_tt(rootPos))
- std::cout << " ponder " << UCI::move(rootMoves[0].pv[1], rootPos.is_chess960());
+ if (bestThread->rootMoves[0].pv.size() > 1 || bestThread->rootMoves[0].extract_ponder_from_tt(rootPos))
+ std::cout << " ponder " << UCI::move(bestThread->rootMoves[0].pv[1], rootPos.is_chess960());
std::cout << sync_endl;
}
// repeatedly with increasing depth until the allocated thinking time has been
// consumed, user stops the search, or the maximum search depth is reached.
-void Thread::search(bool isMainThread) {
+void Thread::search() {
- Stack* ss = stack + 2; // To allow referencing (ss-2) and (ss+2)
+ Stack stack[MAX_PLY+4], *ss = stack+2; // To allow referencing (ss-2) and (ss+2)
Value bestValue, alpha, beta, delta;
Move easyMove = MOVE_NONE;
+ MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr);
std::memset(ss-2, 0, 5 * sizeof(Stack));
bestValue = delta = alpha = -VALUE_INFINITE;
beta = VALUE_INFINITE;
+ completedDepth = DEPTH_ZERO;
- if (isMainThread)
+ if (mainThread)
{
easyMove = EasyMove.get(rootPos.key());
EasyMove.clear();
- BestMoveChanges = 0;
+ mainThread->easyMovePlayed = mainThread->failedLow = false;
+ mainThread->bestMoveChanges = 0;
TT.new_search();
}
// Iterative deepening loop until requested to stop or target depth reached
while (++rootDepth < DEPTH_MAX && !Signals.stop && (!Limits.depth || rootDepth <= Limits.depth))
{
- // Set up the new depth for the helper threads
- if (!isMainThread)
- rootDepth = Threads.main()->rootDepth + Depth(int(3 * log(1 + this->idx)));
+ // Set up the new depth for the helper threads skipping in average each
+ // 2nd ply (using a half density map similar to a Hadamard matrix).
+ if (!mainThread)
+ {
+ int d = rootDepth + rootPos.game_ply();
+
+ if (idx <= 6 || idx > 24)
+ {
+ if (((d + idx) >> (msb(idx + 1) - 1)) % 2)
+ continue;
+ }
+ else
+ {
+ // Table of values of 6 bits with 3 of them set
+ static const int HalfDensityMap[] = {
+ 0x07, 0x0b, 0x0d, 0x0e, 0x13, 0x16, 0x19, 0x1a, 0x1c,
+ 0x23, 0x25, 0x26, 0x29, 0x2c, 0x31, 0x32, 0x34, 0x38
+ };
+
+ if ((HalfDensityMap[idx - 7] >> (d % 6)) & 1)
+ continue;
+ }
+ }
// Age out PV variability metric
- if (isMainThread)
- BestMoveChanges *= 0.5;
+ if (mainThread)
+ mainThread->bestMoveChanges *= 0.505, mainThread->failedLow = false;
// Save the last iteration's scores before first PV line is searched and
// all the move scores except the (new) PV are set to -VALUE_INFINITE.
// When failing high/low give some update (without cluttering
// the UI) before a re-search.
- if ( isMainThread
+ if ( mainThread
&& multiPV == 1
&& (bestValue <= alpha || bestValue >= beta)
&& Time.elapsed() > 3000)
beta = (alpha + beta) / 2;
alpha = std::max(bestValue - delta, -VALUE_INFINITE);
- if (isMainThread)
+ if (mainThread)
{
- Signals.failedLowAtRoot = true;
+ mainThread->failedLow = true;
Signals.stopOnPonderhit = false;
}
}
// Sort the PV lines searched so far and update the GUI
std::stable_sort(rootMoves.begin(), rootMoves.begin() + PVIdx + 1);
- if (!isMainThread)
+ if (!mainThread)
break;
if (Signals.stop)
sync_cout << UCI::pv(rootPos, rootDepth, alpha, beta) << sync_endl;
}
- if (!isMainThread)
+ if (!Signals.stop)
+ completedDepth = rootDepth;
+
+ if (!mainThread)
continue;
// If skill level is enabled and time is up, pick a sub-optimal best move
{
// Take some extra time if the best move has changed
if (rootDepth > 4 * ONE_PLY && multiPV == 1)
- Time.pv_instability(BestMoveChanges);
+ Time.pv_instability(mainThread->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))
+ || Time.elapsed() > Time.available() * (mainThread->failedLow ? 641 : 315) / 640
+ || (mainThread->easyMovePlayed = ( rootMoves[0].pv[0] == easyMove
+ && mainThread->bestMoveChanges < 0.03
+ && Time.elapsed() > Time.available() / 8)))
{
// If we are allowed to ponder do not stop the search now but
// keep pondering until the GUI sends "ponderhit" or "stop".
}
}
- searching = false;
- notify_one(); // Wake up main thread if is sleeping waiting for us
-
- if (!isMainThread)
+ 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 || Time.elapsed() < Time.available())
+ if (EasyMove.stableCnt < 6 || mainThread->easyMovePlayed)
EasyMove.clear();
// If skill level is enabled, swap best PV line with the sub-optimal one
namespace {
- // search<>() is the main search function for both PV and non-PV nodes and for
- // normal and SplitPoint nodes. When called just after a split point the search
- // is simpler because we have already probed the hash table, done a null move
- // search, and searched the first move before splitting, so we don't have to
- // repeat all this work again. We also don't need to store anything to the hash
- // table here: This is taken care of after we return from the split point.
+ // search<>() is the main search function for both PV and non-PV nodes
template <NodeType NT>
Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode) {
assert(-VALUE_INFINITE <= alpha && alpha < beta && beta <= VALUE_INFINITE);
assert(PvNode || (alpha == beta - 1));
- assert(depth > DEPTH_ZERO);
+ assert(DEPTH_ZERO < depth && depth < DEPTH_MAX);
Move pv[MAX_PLY+1], quietsSearched[64];
StateInfo st;
bestValue = -VALUE_INFINITE;
ss->ply = (ss-1)->ply + 1;
+ // Check for available remaining time
+ if (thisThread->resetCalls.load(std::memory_order_relaxed))
+ {
+ thisThread->resetCalls = false;
+ thisThread->callsCnt = 0;
+ }
+ if (++thisThread->callsCnt > 4096)
+ {
+ for (Thread* th : Threads)
+ th->resetCalls = true;
+
+ check_time();
+ }
+
// Used to send selDepth info to GUI
if (PvNode && thisThread->maxPly < ss->ply)
thisThread->maxPly = ss->ply;
{
// Step 2. Check for aborted search and immediate draw
if (Signals.stop.load(std::memory_order_relaxed) || pos.is_draw() || ss->ply >= MAX_PLY)
- return ss->ply >= MAX_PLY && !inCheck ? evaluate(pos)
+ return ss->ply >= MAX_PLY && !inCheck ? evaluate(pos)
: DrawValue[pos.side_to_move()];
// Step 3. Mate distance pruning. Even if we mate at the next move our score
assert(0 <= ss->ply && ss->ply < MAX_PLY);
- ss->currentMove = ss->ttMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
- (ss+1)->skipEarlyPruning = false; (ss+1)->reduction = DEPTH_ZERO;
+ ss->currentMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
+ (ss+1)->skipEarlyPruning = false;
(ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
// Step 4. Transposition table lookup. We don't want the score of a partial
posKey = excludedMove ? pos.exclusion_key() : pos.key();
tte = TT.probe(posKey, ttHit);
ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
- ss->ttMove = ttMove = RootNode ? thisThread->rootMoves[thisThread->PVIdx].pv[0]
- : ttHit ? tte->move() : MOVE_NONE;
+ ttMove = RootNode ? thisThread->rootMoves[thisThread->PVIdx].pv[0]
+ : ttHit ? tte->move() : MOVE_NONE;
// At non-PV nodes we check for an early TT cutoff
if ( !PvNode
ss->moveCount = ++moveCount;
- if (RootNode && thisThread == Threads.main())
- {
- Signals.firstRootMove = moveCount == 1;
-
- if (Time.elapsed() > 3000)
- sync_cout << "info depth " << depth / ONE_PLY
- << " currmove " << UCI::move(move, pos.is_chess960())
- << " currmovenumber " << moveCount + thisThread->PVIdx << sync_endl;
- }
+ if (RootNode && thisThread == Threads.main() && Time.elapsed() > 3000)
+ sync_cout << "info depth " << depth / ONE_PLY
+ << " currmove " << UCI::move(move, pos.is_chess960())
+ << " currmovenumber " << moveCount + thisThread->PVIdx << sync_endl;
if (PvNode)
(ss+1)->pv = nullptr;
continue;
// History based pruning
- if ( depth <= 3 * ONE_PLY
+ if ( depth <= 4 * ONE_PLY
+ && move != ss->killers[0]
&& thisThread->history[pos.moved_piece(move)][to_sq(move)] < VALUE_ZERO
&& cmh[pos.moved_piece(move)][to_sq(move)] < VALUE_ZERO)
continue;
// re-searched at full depth.
if ( depth >= 3 * ONE_PLY
&& moveCount > 1
- && !captureOrPromotion
- && move != ss->killers[0]
- && move != ss->killers[1])
+ && !captureOrPromotion)
{
-
ss->reduction = reduction<PvNode>(improving, depth, moveCount);
+
Depth r = reduction<PvNode>(improving, depth, moveCount);
// Increase reduction for cut nodes and moves with a bad history
if ( (!PvNode && cutNode)
|| ( thisThread->history[pos.piece_on(to_sq(move))][to_sq(move)] < VALUE_ZERO
&& cmh[pos.piece_on(to_sq(move))][to_sq(move)] <= VALUE_ZERO))
- ss->reduction += ONE_PLY;
+ r += ONE_PLY;
// Decrease reduction for moves with a good history
if ( thisThread->history[pos.piece_on(to_sq(move))][to_sq(move)] > VALUE_ZERO
&& cmh[pos.piece_on(to_sq(move))][to_sq(move)] > VALUE_ZERO)
- ss->reduction = std::max(DEPTH_ZERO, ss->reduction - ONE_PLY);
+ r = std::max(DEPTH_ZERO, r - ONE_PLY);
// Decrease reduction for moves that escape a capture
- if ( ss->reduction
+ if ( r
&& type_of(move) == NORMAL
&& type_of(pos.piece_on(to_sq(move))) != PAWN
&& pos.see(make_move(to_sq(move), from_sq(move))) < VALUE_ZERO)
- ss->reduction = std::max(DEPTH_ZERO, ss->reduction - ONE_PLY);
+ r = std::max(DEPTH_ZERO, r - ONE_PLY);
- Depth d = std::max(newDepth - ss->reduction, ONE_PLY);
+ Depth d = std::max(newDepth - r, ONE_PLY);
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
- doFullDepthSearch = (value > alpha && ss->reduction != DEPTH_ZERO);
- ss->reduction = DEPTH_ZERO;
+ doFullDepthSearch = (value > alpha && r != DEPTH_ZERO);
}
else
doFullDepthSearch = !PvNode || moveCount > 1;
// iteration. This information is used for time management: When
// the best move changes frequently, we allocate some more time.
if (moveCount > 1 && thisThread == Threads.main())
- ++BestMoveChanges;
+ ++static_cast<MainThread*>(thisThread)->bestMoveChanges;
}
else
// All other moves but the PV are set to the lowest value: this is
&& is_ok((ss - 1)->currentMove)
&& is_ok((ss - 2)->currentMove))
{
- Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY));
+ Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY) + depth / ONE_PLY - 1);
Square prevPrevSq = to_sq((ss - 2)->currentMove);
CounterMovesStats& prevCmh = CounterMovesHistory[pos.piece_on(prevPrevSq)][prevPrevSq];
prevCmh.update(pos.piece_on(prevSq), prevSq, bonus);
}
- // update_stats() updates killers, history, countermove history and
- // countermoves stats for a quiet best move.
+ // update_stats() updates killers, history, countermove and countermove
+ // history when a new quiet best move is found.
void update_stats(const Position& pos, Stack* ss, Move move,
Depth depth, Move* quiets, int quietsCnt) {
ss->killers[0] = move;
}
- Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY));
+ Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY) + depth / ONE_PLY - 1);
Square prevSq = to_sq((ss-1)->currentMove);
CounterMovesStats& cmh = CounterMovesHistory[pos.piece_on(prevSq)][prevSq];
cmh.update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
}
- // Extra penalty for TT move in previous ply when it gets refuted
+ // Extra penalty for a quiet TT move in previous ply when it gets refuted
if ( (ss-1)->moveCount == 1
&& !pos.captured_piece_type()
&& is_ok((ss-2)->currentMove))
{
Square prevPrevSq = to_sq((ss-2)->currentMove);
CounterMovesStats& prevCmh = CounterMovesHistory[pos.piece_on(prevPrevSq)][prevPrevSq];
- prevCmh.update(pos.piece_on(prevSq), prevSq, -bonus - 2 * depth / ONE_PLY - 1);
+ prevCmh.update(pos.piece_on(prevSq), prevSq, -bonus - 2 * (depth + 1) / ONE_PLY);
}
}
Move Skill::pick_best(size_t multiPV) {
- // PRNG sequence should be non-deterministic, so we seed it with the time at init
const Search::RootMoveVector& rootMoves = Threads.main()->rootMoves;
- static PRNG rng(now());
+ static PRNG rng(now()); // PRNG sequence should be non-deterministic
// RootMoves are already sorted by score in descending order
- int variance = std::min(rootMoves[0].score - rootMoves[multiPV - 1].score, PawnValueMg);
+ Value topScore = rootMoves[0].score;
+ int delta = std::min(topScore - rootMoves[multiPV - 1].score, PawnValueMg);
int weakness = 120 - 2 * level;
int maxScore = -VALUE_INFINITE;
- // Choose best move. For each move score we add two terms both dependent on
+ // Choose best move. For each move score we add two terms, both dependent on
// weakness. One deterministic and bigger for weaker levels, and one random,
// then we choose the move with the resulting highest score.
for (size_t i = 0; i < multiPV; ++i)
{
// This is our magic formula
- int push = ( weakness * int(rootMoves[0].score - rootMoves[i].score)
- + variance * (rng.rand<unsigned>() % weakness)) / 128;
+ int push = ( weakness * int(topScore - rootMoves[i].score)
+ + delta * (rng.rand<unsigned>() % weakness)) / 128;
if (rootMoves[i].score + push > maxScore)
{
best = rootMoves[i].pv[0];
}
}
+
return best;
}
+
+ // check_time() is used to print debug info and, more importantly, to detect
+ // when we are out of available time and thus stop the search.
+
+ void check_time() {
+
+ static TimePoint lastInfoTime = now();
+
+ int elapsed = Time.elapsed();
+ TimePoint tick = Limits.startTime + elapsed;
+
+ if (tick - lastInfoTime >= 1000)
+ {
+ lastInfoTime = tick;
+ dbg_print();
+ }
+
+ // An engine may not stop pondering until told so by the GUI
+ if (Limits.ponder)
+ return;
+
+ if ( (Limits.use_time_management() && elapsed > Time.maximum() - 10)
+ || (Limits.movetime && elapsed >= Limits.movetime)
+ || (Limits.nodes && Threads.nodes_searched() >= Limits.nodes))
+ Signals.stop = true;
+ }
+
} // namespace
TTEntry* tte = TT.probe(pos.key(), ttHit);
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());
+ tte->save(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE,
+ m, VALUE_NONE, TT.generation());
pos.do_move(m, *st++, pos.gives_check(m, CheckInfo(pos)));
}
}
-/// RootMove::extract_ponder_from_tt() is called in case we have no ponder move before
-/// exiting the search, for instance in case we stop the search during a fail high at
-/// root. We try hard to have a ponder move to return to the GUI, otherwise in case of
-/// 'ponder on' we have nothing to think on.
+/// RootMove::extract_ponder_from_tt() is called in case we have no ponder move
+/// before exiting the search, for instance in case we stop the search during a
+/// fail high at root. We try hard to have a ponder move to return to the GUI,
+/// otherwise in case of 'ponder on' we have nothing to think on.
bool RootMove::extract_ponder_from_tt(Position& pos)
{
return false;
}
-
-
-/// check_time() is called by the timer thread when the timer triggers. It is
-/// used to print debug info and, more importantly, to detect when we are out of
-/// available time and thus stop the search.
-
-void check_time() {
-
- static TimePoint lastInfoTime = now();
- int elapsed = Time.elapsed();
-
- if (now() - lastInfoTime >= 1000)
- {
- lastInfoTime = now();
- dbg_print();
- }
-
- // 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
- && elapsed > Time.available() * 3 / 4;
-
- if ( stillAtFirstMove
- || elapsed > Time.maximum() - 2 * TimerThread::Resolution)
- Signals.stop = true;
- }
- else if (Limits.movetime && elapsed >= Limits.movetime)
- Signals.stop = true;
-
- else if (Limits.nodes && Threads.nodes_searched() >= Limits.nodes)
- Signals.stop = true;
-}
projects / stockfish / blobdiff