namespace Search {
- SignalsType Signals;
LimitsType Limits;
}
// Different node types, used as a template parameter
enum NodeType { NonPV, PV };
+ // Sizes and phases of the skip-blocks, used for distributing search depths across the threads
+ const int skipSize[] = { 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4 };
+ const int skipPhase[] = { 0, 1, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 6, 7 };
+
// Razoring and futility margin based on depth
- const int razor_margin[4] = { 483, 570, 603, 554 };
+ // razor_margin[0] is unused as long as depth >= ONE_PLY in search
+ const int razor_margin[] = { 0, 570, 603, 554 };
Value futility_margin(Depth d) { return Value(150 * d / ONE_PLY); }
// Futility and reductions lookup tables, initialized at startup
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 <bool PvNode> Depth reduction(bool i, Depth d, int mn) {
return Reductions[PvNode][i][std::min(d / ONE_PLY, 63)][std::min(mn, 63)] * ONE_PLY;
}
// History and stats update bonus, based on depth
- Value stat_bonus(Depth depth) {
- int d = depth / ONE_PLY ;
- return Value(d * d + 2 * d - 2);
+ int stat_bonus(Depth depth) {
+ int d = depth / ONE_PLY;
+ return d > 17 ? 0 : d * d + 2 * d - 2;
}
// Skill structure is used to implement strength limit
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.
+ // 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() {
Value value_to_tt(Value v, int ply);
Value value_from_tt(Value v, int ply);
void update_pv(Move* pv, Move move, Move* childPv);
- void update_cm_stats(Stack* ss, Piece pc, Square s, Value bonus);
- void update_stats(const Position& pos, Stack* ss, Move move, Move* quiets, int quietsCnt, Value bonus);
- void check_time();
+ 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);
} // namespace
for (int d = 1; d < 64; ++d)
for (int mc = 1; mc < 64; ++mc)
{
- double r = log(d) * log(mc) / 2;
+ double r = log(d) * log(mc) / 1.95;
Reductions[NonPV][imp][d][mc] = int(std::round(r));
Reductions[PV][imp][d][mc] = std::max(Reductions[NonPV][imp][d][mc] - 1, 0);
for (int d = 0; d < 16; ++d)
{
- FutilityMoveCounts[0][d] = int(2.4 + 0.773 * pow(d + 0.00, 1.8));
- FutilityMoveCounts[1][d] = int(2.9 + 1.045 * pow(d + 0.49, 1.8));
+ FutilityMoveCounts[0][d] = int(2.4 + 0.74 * pow(d, 1.78));
+ FutilityMoveCounts[1][d] = int(5.0 + 1.00 * pow(d, 2.00));
}
}
-/// Search::clear() resets search state to zero, to obtain reproducible results
+/// Search::clear() resets search state to its initial value, to obtain reproducible results
void Search::clear() {
for (Thread* th : Threads)
{
- th->counterMoves.clear();
- th->history.clear();
- th->counterMoveHistory.clear();
- th->resetCalls = true;
+ 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);
}
+ Threads.main()->callsCnt = 0;
Threads.main()->previousScore = VALUE_INFINITE;
}
Color us = rootPos.side_to_move();
Time.init(Limits, us, rootPos.game_ply());
+ TT.new_search();
int contempt = Options["Contempt"] * PawnValueEg / 100; // From centipawns
DrawValue[ us] = VALUE_DRAW - Value(contempt);
Time.availableNodes += Limits.inc[us] - Threads.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,
+ // 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
// GUI sends a "stop" or "ponderhit" command. We therefore simply wait here
- // until the GUI sends one of those commands (which also raises Signals.stop).
- if (!Signals.stop && (Limits.ponder || Limits.infinite))
+ // until the GUI sends one of those commands (which also raises Threads.stop).
+ if (!Threads.stop && (Limits.ponder || Limits.infinite))
{
- Signals.stopOnPonderhit = true;
- wait(Signals.stop);
+ Threads.stopOnPonderhit = true;
+ wait(Threads.stop);
}
// Stop the threads if not already stopped
- Signals.stop = true;
+ Threads.stop = true;
// Wait until all threads have finished
for (Thread* th : Threads)
std::cout << sync_endl;
}
-// Sizes and phases of the skip-blocks, used for distributing search depths across the threads.
-static int skipsize[20] = {1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4};
-static int phase [20] = {0, 1, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 6, 7};
-// Thread::search() is the main iterative deepening loop. It calls search()
-// repeatedly with increasing depth until the allocated thinking time has been
-// consumed, the user stops the search, or the maximum search depth is reached.
+/// Thread::search() is the main iterative deepening loop. It calls search()
+/// repeatedly with increasing depth until the allocated thinking time has been
+/// consumed, the user stops the search, or the maximum search depth is reached.
void Thread::search() {
MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr);
std::memset(ss-4, 0, 7 * sizeof(Stack));
- for(int i = -4; i < 0; i++)
- (ss+i)->counterMoves = &this->counterMoveHistory[NO_PIECE][0]; // use as sentinel.
+ for (int i = 4; i > 0; i--)
+ (ss-i)->contHistory = &this->contHistory[NO_PIECE][0]; // Use as sentinel
bestValue = delta = alpha = -VALUE_INFINITE;
beta = VALUE_INFINITE;
EasyMove.clear();
mainThread->easyMovePlayed = mainThread->failedLow = false;
mainThread->bestMoveChanges = 0;
- TT.new_search();
}
size_t multiPV = Options["MultiPV"];
multiPV = std::min(multiPV, rootMoves.size());
- int hIdx = (idx - 1) % 20; // helper index, cycle after 20 threads
-
// Iterative deepening loop until requested to stop or the target depth is reached
while ( (rootDepth += ONE_PLY) < DEPTH_MAX
- && !Signals.stop
- && (!Limits.depth || Threads.main()->rootDepth / ONE_PLY <= Limits.depth))
+ && !Threads.stop
+ && !(Limits.depth && mainThread && rootDepth / ONE_PLY > Limits.depth))
{
- // skip half of the plies in blocks depending on game ply and helper index.
- if (idx && ((rootDepth / ONE_PLY + rootPos.game_ply() + phase[hIdx]) / skipsize[hIdx]) % 2)
- continue;
+ // Distribute search depths across the threads
+ if (idx)
+ {
+ int i = (idx - 1) % 20;
+ if (((rootDepth / ONE_PLY + rootPos.game_ply() + skipPhase[i]) / skipSize[i]) % 2)
+ continue;
+ }
// Age out PV variability metric
if (mainThread)
rm.previousScore = rm.score;
// MultiPV loop. We perform a full root search for each PV line
- for (PVIdx = 0; PVIdx < multiPV && !Signals.stop; ++PVIdx)
+ for (PVIdx = 0; PVIdx < multiPV && !Threads.stop; ++PVIdx)
{
+ // Reset UCI info selDepth for each depth and each PV line
+ selDepth = 0;
+
// Reset aspiration window starting size
if (rootDepth >= 5 * ONE_PLY)
{
// If search has been stopped, we break immediately. Sorting and
// writing PV back to TT is safe because RootMoves is still
// valid, although it refers to the previous iteration.
- if (Signals.stop)
+ if (Threads.stop)
break;
// When failing high/low give some update (without cluttering
if (mainThread)
{
mainThread->failedLow = true;
- Signals.stopOnPonderhit = false;
+ Threads.stopOnPonderhit = false;
}
}
else if (bestValue >= beta)
- {
- alpha = (alpha + beta) / 2;
beta = std::min(bestValue + delta, VALUE_INFINITE);
- }
else
break;
if (!mainThread)
continue;
- if (Signals.stop || PVIdx + 1 == multiPV || Time.elapsed() > 3000)
+ if (Threads.stop || PVIdx + 1 == multiPV || Time.elapsed() > 3000)
sync_cout << UCI::pv(rootPos, rootDepth, alpha, beta) << sync_endl;
}
- if (!Signals.stop)
+ if (!Threads.stop)
completedDepth = rootDepth;
if (!mainThread)
if ( Limits.mate
&& bestValue >= VALUE_MATE_IN_MAX_PLY
&& VALUE_MATE - bestValue <= 2 * Limits.mate)
- Signals.stop = true;
+ Threads.stop = true;
// Do we have time for the next iteration? Can we stop searching now?
if (Limits.use_time_management())
{
- if (!Signals.stop && !Signals.stopOnPonderhit)
+ 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
// 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;
+ Threads.stopOnPonderhit = true;
else
- Signals.stop = true;
+ Threads.stop = true;
}
}
Depth extension, newDepth;
Value bestValue, value, ttValue, eval;
bool ttHit, inCheck, givesCheck, singularExtensionNode, improving;
- bool captureOrPromotion, doFullDepthSearch, moveCountPruning;
- Piece moved_piece;
+ bool captureOrPromotion, doFullDepthSearch, moveCountPruning, skipQuiets, ttCapture;
+ Piece movedPiece;
int moveCount, quietCount;
// Step 1. Initialize node
Thread* thisThread = pos.this_thread();
inCheck = pos.checkers();
- moveCount = quietCount = ss->moveCount = 0;
- ss->history = VALUE_ZERO;
+ 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->resetCalls.load(std::memory_order_relaxed))
- {
- thisThread->resetCalls = false;
- // At low node count increase the checking rate to about 0.1% of nodes
- // otherwise use a default value.
- thisThread->callsCnt = Limits.nodes ? std::min((int64_t)4096, Limits.nodes / 1024)
- : 4096;
- }
-
- if (--thisThread->callsCnt <= 0)
- {
- for (Thread* th : Threads)
- th->resetCalls = true;
-
- check_time();
- }
+ if (thisThread == Threads.main())
+ static_cast<MainThread*>(thisThread)->check_time();
// Used to send selDepth info to GUI
- if (PvNode && thisThread->maxPly < ss->ply)
- thisThread->maxPly = ss->ply;
+ if (PvNode && thisThread->selDepth < ss->ply)
+ thisThread->selDepth = ss->ply;
if (!rootNode)
{
// Step 2. Check for aborted search and immediate draw
- if (Signals.stop.load(std::memory_order_relaxed) || pos.is_draw(ss->ply) || ss->ply >= MAX_PLY)
+ if (Threads.stop.load(std::memory_order_relaxed) || pos.is_draw(ss->ply) || ss->ply >= MAX_PLY)
return ss->ply >= MAX_PLY && !inCheck ? evaluate(pos)
: DrawValue[pos.side_to_move()];
assert(0 <= ss->ply && ss->ply < MAX_PLY);
ss->currentMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
- ss->counterMoves = &thisThread->counterMoveHistory[NO_PIECE][0];
+ ss->contHistory = &thisThread->contHistory[NO_PIECE][0];
(ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
Square prevSq = to_sq((ss-1)->currentMove);
// Extra penalty for a quiet TT move in previous ply when it gets refuted
if ((ss-1)->moveCount == 1 && !pos.captured_piece())
- update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
+ update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
}
// Penalty for a quiet ttMove that fails low
else if (!pos.capture_or_promotion(ttMove))
{
- Value penalty = -stat_bonus(depth + ONE_PLY);
- thisThread->history.update(pos.side_to_move(), ttMove, penalty);
- update_cm_stats(ss, pos.moved_piece(ttMove), to_sq(ttMove), penalty);
+ int penalty = -stat_bonus(depth);
+ thisThread->mainHistory.update(pos.side_to_move(), ttMove, penalty);
+ update_continuation_histories(ss, pos.moved_piece(ttMove), to_sq(ttMove), penalty);
}
}
return ttValue;
if (err != TB::ProbeState::FAIL)
{
- thisThread->tbHits++;
+ thisThread->tbHits.fetch_add(1, std::memory_order_relaxed);
int drawScore = TB::UseRule50 ? 1 : 0;
eval = ss->staticEval = evaluate(pos);
// Can ttValue be used as a better position evaluation?
- if (ttValue != VALUE_NONE)
- if (tte->bound() & (ttValue > eval ? BOUND_LOWER : BOUND_UPPER))
- eval = ttValue;
+ if ( ttValue != VALUE_NONE
+ && (tte->bound() & (ttValue > eval ? BOUND_LOWER : BOUND_UPPER)))
+ eval = ttValue;
}
else
{
Depth R = ((823 + 67 * depth / ONE_PLY) / 256 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY;
ss->currentMove = MOVE_NULL;
- ss->counterMoves = &thisThread->counterMoveHistory[NO_PIECE][0];
+ ss->contHistory = &thisThread->contHistory[NO_PIECE][0];
pos.do_null_move(st);
Value nullValue = depth-R < ONE_PLY ? -qsearch<NonPV, false>(pos, ss+1, -beta, -beta+1)
&& abs(beta) < VALUE_MATE_IN_MAX_PLY)
{
Value rbeta = std::min(beta + 200, VALUE_INFINITE);
- Depth rdepth = depth - 4 * ONE_PLY;
- assert(rdepth >= ONE_PLY);
assert(is_ok((ss-1)->currentMove));
MovePicker mp(pos, ttMove, rbeta - ss->staticEval);
if (pos.legal(move))
{
ss->currentMove = move;
- ss->counterMoves = &thisThread->counterMoveHistory[pos.moved_piece(move)][to_sq(move)];
+ ss->contHistory = &thisThread->contHistory[pos.moved_piece(move)][to_sq(move)];
+ assert(depth >= 5 * ONE_PLY);
pos.do_move(move, st);
- value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, rdepth, !cutNode, false);
+ value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, depth - 4 * ONE_PLY, !cutNode, false);
pos.undo_move(move);
if (value >= rbeta)
return value;
moves_loop: // When in check search starts from here
- const CounterMoveStats* cmh = (ss-1)->counterMoves;
- const CounterMoveStats* fmh = (ss-2)->counterMoves;
- const CounterMoveStats* fmh2 = (ss-4)->counterMoves;
- const bool cm_ok = is_ok((ss-1)->currentMove);
- const bool fm_ok = is_ok((ss-2)->currentMove);
- const bool fm2_ok = is_ok((ss-4)->currentMove);
+ const PieceToHistory* contHist[] = { (ss-1)->contHistory, (ss-2)->contHistory, nullptr, (ss-4)->contHistory };
+ Move countermove = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq];
- MovePicker mp(pos, ttMove, depth, ss);
+ MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory, contHist, countermove, ss->killers);
value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
improving = ss->staticEval >= (ss-2)->staticEval
/* || ss->staticEval == VALUE_NONE Already implicit in the previous condition */
&& !excludedMove // Recursive singular search is not allowed
&& (tte->bound() & BOUND_LOWER)
&& tte->depth() >= depth - 3 * ONE_PLY;
+ skipQuiets = false;
+ ttCapture = false;
// Step 11. Loop through moves
// Loop through all pseudo-legal moves until no moves remain or a beta cutoff occurs
- while ((move = mp.next_move()) != MOVE_NONE)
+ while ((move = mp.next_move(skipQuiets)) != MOVE_NONE)
{
assert(is_ok(move));
extension = DEPTH_ZERO;
captureOrPromotion = pos.capture_or_promotion(move);
- moved_piece = pos.moved_piece(move);
+ movedPiece = pos.moved_piece(move);
givesCheck = type_of(move) == NORMAL && !pos.discovered_check_candidates()
? pos.check_squares(type_of(pos.piece_on(from_sq(move)))) & to_sq(move)
moveCountPruning = depth < 16 * ONE_PLY
&& moveCount >= FutilityMoveCounts[improving][depth / ONE_PLY];
- // Step 12. Extensions
- // Extend checks
- if ( givesCheck
- && !moveCountPruning
- && pos.see_ge(move, VALUE_ZERO))
- extension = ONE_PLY;
+ // Step 12. Singular and Gives Check Extensions
// Singular extension search. If all moves but one fail low on a search of
// (alpha-s, beta-s), and just one fails high on (alpha, beta), then that move
// is singular and should be extended. To verify this we do a reduced search
// on all the other moves but the ttMove and if the result is lower than
- // ttValue minus a margin then we extend the ttMove.
+ // ttValue minus a margin then we will extend the ttMove.
if ( singularExtensionNode
&& move == ttMove
- && !extension
&& pos.legal(move))
{
Value rBeta = std::max(ttValue - 2 * depth / ONE_PLY, -VALUE_MATE);
if (value < rBeta)
extension = ONE_PLY;
}
+ else if ( givesCheck
+ && !moveCountPruning
+ && pos.see_ge(move))
+ extension = ONE_PLY;
// Calculate new depth for this move
newDepth = depth - ONE_PLY + extension;
// Step 13. Pruning at shallow depth
if ( !rootNode
+ && pos.non_pawn_material(pos.side_to_move())
&& bestValue > VALUE_MATED_IN_MAX_PLY)
{
if ( !captureOrPromotion
&& !givesCheck
- && (!pos.advanced_pawn_push(move) || pos.non_pawn_material() >= 5000))
+ && (!pos.advanced_pawn_push(move) || pos.non_pawn_material() >= Value(5000)))
{
// Move count based pruning
if (moveCountPruning)
+ {
+ skipQuiets = true;
continue;
+ }
// Reduced depth of the next LMR search
int lmrDepth = std::max(newDepth - reduction<PvNode>(improving, depth, moveCount), DEPTH_ZERO) / ONE_PLY;
// Countermoves based pruning
if ( lmrDepth < 3
- && (((*cmh )[moved_piece][to_sq(move)] < VALUE_ZERO) || !cm_ok)
- && (((*fmh )[moved_piece][to_sq(move)] < VALUE_ZERO) || !fm_ok)
- && (((*fmh2)[moved_piece][to_sq(move)] < VALUE_ZERO) || !fm2_ok || (cm_ok && fm_ok)))
+ && (*contHist[0])[movedPiece][to_sq(move)] < CounterMovePruneThreshold
+ && (*contHist[1])[movedPiece][to_sq(move)] < CounterMovePruneThreshold)
continue;
// Futility pruning: parent node
continue;
}
+ if (move == ttMove && captureOrPromotion)
+ ttCapture = true;
+
// Update the current move (this must be done after singular extension search)
ss->currentMove = move;
- ss->counterMoves = &thisThread->counterMoveHistory[moved_piece][to_sq(move)];
+ ss->contHistory = &thisThread->contHistory[movedPiece][to_sq(move)];
// Step 14. Make the move
pos.do_move(move, st, givesCheck);
r -= r ? ONE_PLY : DEPTH_ZERO;
else
{
+ // Increase reduction if ttMove is a capture
+ if (ttCapture)
+ r += ONE_PLY;
+
// Increase reduction for cut nodes
if (cutNode)
r += 2 * ONE_PLY;
// Decrease reduction for moves that escape a capture. Filter out
// castling moves, because they are coded as "king captures rook" and
// hence break make_move().
- else if ( type_of(move) == NORMAL
- && !pos.see_ge(make_move(to_sq(move), from_sq(move)), VALUE_ZERO))
+ else if ( type_of(move) == NORMAL
+ && !pos.see_ge(make_move(to_sq(move), from_sq(move))))
r -= 2 * ONE_PLY;
- ss->history = (*cmh )[moved_piece][to_sq(move)]
- + (*fmh )[moved_piece][to_sq(move)]
- + (*fmh2)[moved_piece][to_sq(move)]
- + thisThread->history.get(~pos.side_to_move(), move)
- - 4000; // Correction factor
+ ss->statScore = thisThread->mainHistory[~pos.side_to_move()][from_to(move)]
+ + (*contHist[0])[movedPiece][to_sq(move)]
+ + (*contHist[1])[movedPiece][to_sq(move)]
+ + (*contHist[3])[movedPiece][to_sq(move)]
+ - 4000;
// Decrease/increase reduction by comparing opponent's stat score
- if (ss->history > VALUE_ZERO && (ss-1)->history < VALUE_ZERO)
+ if (ss->statScore > 0 && (ss-1)->statScore < 0)
r -= ONE_PLY;
- else if (ss->history < VALUE_ZERO && (ss-1)->history > VALUE_ZERO)
+ else if (ss->statScore < 0 && (ss-1)->statScore > 0)
r += ONE_PLY;
// Decrease/increase reduction for moves with a good/bad history
- r = std::max(DEPTH_ZERO, (r / ONE_PLY - ss->history / 20000) * ONE_PLY);
+ r = std::max(DEPTH_ZERO, (r / ONE_PLY - ss->statScore / 20000) * ONE_PLY);
}
Depth d = std::max(newDepth - r, ONE_PLY);
// Finished searching the move. If a stop occurred, the return value of
// the search cannot be trusted, and we return immediately without
// updating best move, PV and TT.
- if (Signals.stop.load(std::memory_order_relaxed))
+ if (Threads.stop.load(std::memory_order_relaxed))
return VALUE_ZERO;
if (rootNode)
if (moveCount == 1 || value > alpha)
{
rm.score = value;
+ rm.selDepth = thisThread->selDepth;
rm.pv.resize(1);
assert((ss+1)->pv);
++static_cast<MainThread*>(thisThread)->bestMoveChanges;
}
else
- // All other moves but the PV are set to the lowest value: this is
- // not a problem when sorting because the sort is stable and the
+ // All other moves but the PV are set to the lowest value: this
+ // is not a problem when sorting because the sort is stable and the
// move position in the list is preserved - just the PV is pushed up.
rm.score = -VALUE_INFINITE;
}
// completed. But in this case bestValue is valid because we have fully
// searched our subtree, and we can anyhow save the result in TT.
/*
- if (Signals.stop)
+ if (Threads.stop)
return VALUE_DRAW;
*/
: inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()];
else if (bestMove)
{
-
// Quiet best move: update move sorting heuristics
if (!pos.capture_or_promotion(bestMove))
update_stats(pos, ss, bestMove, quietsSearched, quietCount, stat_bonus(depth));
// Extra penalty for a quiet TT move in previous ply when it gets refuted
if ((ss-1)->moveCount == 1 && !pos.captured_piece())
- update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
+ update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
}
// Bonus for prior countermove that caused the fail low
else if ( depth >= 3 * ONE_PLY
&& !pos.captured_piece()
- && cm_ok)
- update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth));
+ && is_ok((ss-1)->currentMove))
+ update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth));
- tte->save(posKey, value_to_tt(bestValue, ss->ply),
- bestValue >= beta ? BOUND_LOWER :
- PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
- depth, bestMove, ss->staticEval, TT.generation());
+ if (!excludedMove)
+ tte->save(posKey, value_to_tt(bestValue, ss->ply),
+ bestValue >= beta ? BOUND_LOWER :
+ PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
+ depth, bestMove, ss->staticEval, TT.generation());
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha;
bool ttHit, givesCheck, evasionPrunable;
Depth ttDepth;
+ int moveCount;
if (PvNode)
{
ss->currentMove = bestMove = MOVE_NONE;
ss->ply = (ss-1)->ply + 1;
+ moveCount = 0;
// Check for an instant draw or if the maximum ply has been reached
if (pos.is_draw(ss->ply) || ss->ply >= MAX_PLY)
ss->staticEval = bestValue = evaluate(pos);
// Can ttValue be used as a better position evaluation?
- if (ttValue != VALUE_NONE)
- if (tte->bound() & (ttValue > bestValue ? BOUND_LOWER : BOUND_UPPER))
- bestValue = ttValue;
+ if ( ttValue != VALUE_NONE
+ && (tte->bound() & (ttValue > bestValue ? BOUND_LOWER : BOUND_UPPER)))
+ bestValue = ttValue;
}
else
ss->staticEval = bestValue =
// 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, to_sq((ss-1)->currentMove));
+ const PieceToHistory* contHist[4] = {};
+ MovePicker mp(pos, ttMove, depth, &pos.this_thread()->mainHistory, contHist, to_sq((ss-1)->currentMove));
// Loop through the moves until no moves remain or a beta cutoff occurs
while ((move = mp.next_move()) != MOVE_NONE)
? pos.check_squares(type_of(pos.piece_on(from_sq(move)))) & to_sq(move)
: pos.gives_check(move);
+ moveCount++;
+
// Futility pruning
if ( !InCheck
&& !givesCheck
// Detect non-capture evasions that are candidates to be pruned
evasionPrunable = InCheck
+ && (depth != DEPTH_ZERO || moveCount > 2)
&& bestValue > VALUE_MATED_IN_MAX_PLY
&& !pos.capture(move);
// Don't search moves with negative SEE values
if ( (!InCheck || evasionPrunable)
&& type_of(move) != PROMOTION
- && !pos.see_ge(move, VALUE_ZERO))
+ && !pos.see_ge(move))
continue;
// Speculative prefetch as early as possible
// Check for legality just before making the move
if (!pos.legal(move))
+ {
+ moveCount--;
continue;
+ }
ss->currentMove = move;
}
- // update_cm_stats() updates countermove and follow-up move history
+ // update_continuation_histories() updates histories of the move pairs formed
+ // by moves at ply -1, -2, and -4 with current move.
- void update_cm_stats(Stack* ss, Piece pc, Square s, Value bonus) {
+ void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus) {
for (int i : {1, 2, 4})
- if (is_ok((ss-i)->currentMove))
- (ss-i)->counterMoves->update(pc, s, bonus);
+ if (is_ok((ss-i)->currentMove))
+ (ss-i)->contHistory->update(pc, to, bonus);
}
// update_stats() updates move sorting heuristics when a new quiet best move is found
void update_stats(const Position& pos, Stack* ss, Move move,
- Move* quiets, int quietsCnt, Value bonus) {
+ Move* quiets, int quietsCnt, int bonus) {
if (ss->killers[0] != move)
{
Color c = pos.side_to_move();
Thread* thisThread = pos.this_thread();
- thisThread->history.update(c, move, bonus);
- update_cm_stats(ss, pos.moved_piece(move), to_sq(move), bonus);
+ thisThread->mainHistory.update(c, move, bonus);
+ update_continuation_histories(ss, pos.moved_piece(move), to_sq(move), bonus);
if (is_ok((ss-1)->currentMove))
{
Square prevSq = to_sq((ss-1)->currentMove);
- thisThread->counterMoves.update(pos.piece_on(prevSq), prevSq, move);
+ thisThread->counterMoves[pos.piece_on(prevSq)][prevSq] = move;
}
// Decrease all the other played quiet moves
for (int i = 0; i < quietsCnt; ++i)
{
- thisThread->history.update(c, quiets[i], -bonus);
- update_cm_stats(ss, pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
+ thisThread->mainHistory.update(c, quiets[i], -bonus);
+ update_continuation_histories(ss, pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
}
}
return best;
}
+} // namespace
// 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() {
+ void MainThread::check_time() {
+
+ if (--callsCnt > 0)
+ return;
+
+ // At low node count increase the checking rate to about 0.1% of nodes
+ // otherwise use a default value.
+ callsCnt = Limits.nodes ? std::min(4096, int(Limits.nodes / 1024)) : 4096;
static TimePoint lastInfoTime = now();
if ( (Limits.use_time_management() && elapsed > Time.maximum() - 10)
|| (Limits.movetime && elapsed >= Limits.movetime)
|| (Limits.nodes && Threads.nodes_searched() >= (uint64_t)Limits.nodes))
- Signals.stop = true;
+ Threads.stop = true;
}
-} // namespace
-
/// UCI::pv() formats PV information according to the UCI protocol. UCI requires
/// that all (if any) unsearched PV lines are sent using a previous search score.
for (size_t i = 0; i < multiPV; ++i)
{
- bool updated = (i <= PVIdx);
+ bool updated = (i <= PVIdx && rootMoves[i].score != -VALUE_INFINITE);
if (depth == ONE_PLY && !updated)
continue;
ss << "info"
<< " depth " << d / ONE_PLY
- << " seldepth " << pos.this_thread()->maxPly
+ << " seldepth " << rootMoves[i].selDepth
<< " multipv " << i + 1
<< " score " << UCI::value(v);
projects / stockfish / blobdiff