#include "movepick.h"
#include "position.h"
#include "search.h"
-#include "timeman.h"
#include "thread.h"
+#include "timeman.h"
#include "tt.h"
#include "uci.h"
#include "syzygy/tbprobe.h"
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 };
+ constexpr int SkipSize[] = { 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4 };
+ constexpr 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 margins
- const int RazorMargin = 600;
- Value futility_margin(Depth d) { return Value(150 * d / ONE_PLY); }
+ // Razor and futility margins
+ constexpr int RazorMargin[] = {0, 590, 604};
+ Value futility_margin(Depth d, bool improving) {
+ return Value((175 - 50 * improving) * d / ONE_PLY);
+ }
+
+ // Margin for pruning capturing moves: almost linear in depth
+ constexpr int CapturePruneMargin[] = { 0,
+ 1 * PawnValueEg * 1055 / 1000,
+ 2 * PawnValueEg * 1042 / 1000,
+ 3 * PawnValueEg * 963 / 1000,
+ 4 * PawnValueEg * 1038 / 1000,
+ 5 * PawnValueEg * 950 / 1000,
+ 6 * PawnValueEg * 930 / 1000
+ };
// Futility and reductions lookup tables, initialized at startup
int FutilityMoveCounts[2][16]; // [improving][depth]
template <NodeType NT>
Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode, bool skipEarlyPruning);
- template <NodeType NT, bool InCheck>
+ template <NodeType NT>
Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth = DEPTH_ZERO);
Value value_to_tt(Value v, int ply);
void update_quiet_stats(const Position& pos, Stack* ss, Move move, Move* quiets, int quietsCnt, int bonus);
void update_capture_stats(const Position& pos, Move move, Move* captures, int captureCnt, int bonus);
+ inline bool gives_check(const Position& pos, Move move) {
+ Color us = pos.side_to_move();
+ return type_of(move) == NORMAL && !(pos.blockers_for_king(~us) & pos.pieces(us))
+ ? pos.check_squares(type_of(pos.moved_piece(move))) & to_sq(move)
+ : pos.gives_check(move);
+ }
+
// perft() is our utility to verify move generation. All the leaf nodes up
// to the given depth are generated and counted, and the sum is returned.
template<bool Root>
Reductions[PV][imp][d][mc] = std::max(Reductions[NonPV][imp][d][mc] - 1, 0);
// Increase reduction for non-PV nodes when eval is not improving
- if (!imp && Reductions[NonPV][imp][d][mc] >= 2)
+ if (!imp && r > 1.0)
Reductions[NonPV][imp][d][mc]++;
}
std::memset(ss-4, 0, 7 * sizeof(Stack));
for (int i = 4; i > 0; i--)
- (ss-i)->contHistory = &this->contHistory[NO_PIECE][0]; // Use as sentinel
+ (ss-i)->contHistory = this->contHistory[NO_PIECE][0].get(); // Use as sentinel
bestValue = delta = alpha = -VALUE_INFINITE;
beta = VALUE_INFINITE;
multiPV = std::min(multiPV, rootMoves.size());
int ct = Options["Contempt"] * PawnValueEg / 100; // From centipawns
- Eval::Contempt = (us == WHITE ? make_score(ct, ct / 2)
- : -make_score(ct, ct / 2));
+ contempt = (us == WHITE ? make_score(ct, ct / 2)
+ : -make_score(ct, ct / 2));
// Iterative deepening loop until requested to stop or the target depth is reached
while ( (rootDepth += ONE_PLY) < DEPTH_MAX
// Age out PV variability metric
if (mainThread)
- mainThread->bestMoveChanges *= 0.505, mainThread->failedLow = false;
+ mainThread->bestMoveChanges *= 0.517, 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.
// Reset aspiration window starting size
if (rootDepth >= 5 * ONE_PLY)
{
+ Value previousScore = rootMoves[PVIdx].previousScore;
delta = Value(18);
- alpha = std::max(rootMoves[PVIdx].previousScore - delta,-VALUE_INFINITE);
- beta = std::min(rootMoves[PVIdx].previousScore + delta, VALUE_INFINITE);
+ alpha = std::max(previousScore - delta,-VALUE_INFINITE);
+ beta = std::min(previousScore + delta, VALUE_INFINITE);
+
+ ct = Options["Contempt"] * PawnValueEg / 100; // From centipawns
- // Adjust contempt based on current bestValue
- ct = Options["Contempt"] * PawnValueEg / 100 // From centipawns
- + (bestValue > 500 ? 50: // Dynamic contempt
- bestValue < -500 ? -50:
- bestValue / 10);
+ // Adjust contempt based on root move's previousScore (dynamic contempt)
+ ct += int(std::round(48 * atan(float(previousScore) / 128)));
- Eval::Contempt = (us == WHITE ? make_score(ct, ct / 2)
- : -make_score(ct, ct / 2));
+ contempt = (us == WHITE ? make_score(ct, ct / 2)
+ : -make_score(ct, ct / 2));
}
// Start with a small aspiration window and, in the case of a fail
const int F[] = { mainThread->failedLow,
bestValue - mainThread->previousScore };
- int improvingFactor = std::max(229, std::min(715, 357 + 119 * F[0] - 6 * F[1]));
+ int improvingFactor = std::max(246, std::min(832, 306 + 119 * F[0] - 6 * F[1]));
// If the bestMove is stable over several iterations, reduce time accordingly
timeReduction = 1.0;
for (int i : {3, 4, 5})
if (lastBestMoveDepth * i < completedDepth)
- timeReduction *= 1.3;
+ timeReduction *= 1.25;
// Use part of the gained time from a previous stable move for the current move
- double unstablePvFactor = 1.0 + mainThread->bestMoveChanges;
- unstablePvFactor *= std::pow(mainThread->previousTimeReduction, 0.51) / timeReduction;
+ double bestMoveInstability = 1.0 + mainThread->bestMoveChanges;
+ bestMoveInstability *= std::pow(mainThread->previousTimeReduction, 0.528) / timeReduction;
// Stop the search if we have only one legal move, or if available time elapsed
if ( rootMoves.size() == 1
- || Time.elapsed() > Time.optimum() * unstablePvFactor * improvingFactor / 605)
+ || Time.elapsed() > Time.optimum() * bestMoveInstability * improvingFactor / 581)
{
// If we are allowed to ponder do not stop the search now but
// keep pondering until the GUI sends "ponderhit" or "stop".
template <NodeType NT>
Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode, bool skipEarlyPruning) {
- const bool PvNode = NT == PV;
+ // Use quiescence search when needed
+ if (depth < ONE_PLY)
+ return qsearch<NT>(pos, ss, alpha, beta);
+
+ constexpr bool PvNode = NT == PV;
const bool rootNode = PvNode && ss->ply == 0;
assert(-VALUE_INFINITE <= alpha && alpha < beta && beta <= VALUE_INFINITE);
Thread* thisThread = pos.this_thread();
inCheck = pos.checkers();
moveCount = captureCount = quietCount = ss->moveCount = 0;
- ss->statScore = 0;
bestValue = -VALUE_INFINITE;
maxValue = VALUE_INFINITE;
(ss+1)->ply = ss->ply + 1;
ss->currentMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
- ss->contHistory = &thisThread->contHistory[NO_PIECE][0];
+ ss->contHistory = thisThread->contHistory[NO_PIECE][0].get();
(ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
Square prevSq = to_sq((ss-1)->currentMove);
+ // Initialize statScore to zero for the grandchildren of the current position.
+ // So statScore is shared between all grandchildren and only the first grandchild
+ // starts with statScore = 0. Later grandchildren start with the last calculated
+ // statScore of the previous grandchild. This influences the reduction rules in
+ // LMR which are based on the statScore of parent position.
+ (ss+2)->statScore = 0;
+
// Step 4. Transposition table lookup. We don't want the score of a partial
// search to overwrite a previous full search TT value, so we use a different
// position key in case of an excluded move.
else if (!pos.capture_or_promotion(ttMove))
{
int penalty = -stat_bonus(depth);
- thisThread->mainHistory.update(pos.side_to_move(), ttMove, penalty);
+ thisThread->mainHistory[pos.side_to_move()][from_to(ttMove)] << penalty;
update_continuation_histories(ss, pos.moved_piece(ttMove), to_sq(ttMove), penalty);
}
}
if (inCheck)
{
ss->staticEval = eval = VALUE_NONE;
+ improving = false;
goto moves_loop;
}
else if (ttHit)
ss->staticEval, TT.generation());
}
+ improving = ss->staticEval >= (ss-2)->staticEval
+ ||(ss-2)->staticEval == VALUE_NONE;
+
if (skipEarlyPruning || !pos.non_pawn_material(pos.side_to_move()))
goto moves_loop;
// Step 7. Razoring (skipped when in check)
- if ( !PvNode
- && depth < 4 * ONE_PLY
- && eval + RazorMargin <= alpha)
+ if ( !PvNode
+ && depth < 3 * ONE_PLY
+ && eval <= alpha - RazorMargin[depth / ONE_PLY])
{
- if (depth <= ONE_PLY)
- return qsearch<NonPV, false>(pos, ss, alpha, alpha+1);
-
- Value ralpha = alpha - RazorMargin;
- Value v = qsearch<NonPV, false>(pos, ss, ralpha, ralpha+1);
- if (v <= ralpha)
+ Value ralpha = alpha - (depth >= 2 * ONE_PLY) * RazorMargin[depth / ONE_PLY];
+ Value v = qsearch<NonPV>(pos, ss, ralpha, ralpha+1);
+ if (depth < 2 * ONE_PLY || v <= ralpha)
return v;
}
// Step 8. Futility pruning: child node (skipped when in check)
if ( !rootNode
&& depth < 7 * ONE_PLY
- && eval - futility_margin(depth) >= beta
+ && eval - futility_margin(depth, improving) >= beta
&& eval < VALUE_KNOWN_WIN) // Do not return unproven wins
return eval;
Depth R = ((823 + 67 * depth / ONE_PLY) / 256 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY;
ss->currentMove = MOVE_NULL;
- ss->contHistory = &thisThread->contHistory[NO_PIECE][0];
+ ss->contHistory = thisThread->contHistory[NO_PIECE][0].get();
pos.do_null_move(st);
- Value nullValue = depth-R < ONE_PLY ? -qsearch<NonPV, false>(pos, ss+1, -beta, -beta+1)
- : - search<NonPV>(pos, ss+1, -beta, -beta+1, depth-R, !cutNode, true);
+
+ Value nullValue = -search<NonPV>(pos, ss+1, -beta, -beta+1, depth-R, !cutNode, true);
+
pos.undo_null_move();
if (nullValue >= beta)
thisThread->nmp_ply = ss->ply + 3 * (depth-R) / 4;
thisThread->nmp_odd = ss->ply % 2;
- Value v = depth-R < ONE_PLY ? qsearch<NonPV, false>(pos, ss, beta-1, beta)
- : search<NonPV>(pos, ss, beta-1, beta, depth-R, false, true);
+ Value v = search<NonPV>(pos, ss, beta-1, beta, depth-R, false, true);
thisThread->nmp_odd = thisThread->nmp_ply = 0;
{
assert(is_ok((ss-1)->currentMove));
- Value rbeta = std::min(beta + 200, VALUE_INFINITE);
+ Value rbeta = std::min(beta + 216 - 48 * improving, VALUE_INFINITE);
MovePicker mp(pos, ttMove, rbeta - ss->staticEval, &thisThread->captureHistory);
+ int probCutCount = 0;
- while ((move = mp.next_move()) != MOVE_NONE)
+ while ( (move = mp.next_move()) != MOVE_NONE
+ && probCutCount < 3)
if (pos.legal(move))
{
+ probCutCount++;
+
ss->currentMove = move;
- ss->contHistory = &thisThread->contHistory[pos.moved_piece(move)][to_sq(move)];
+ ss->contHistory = thisThread->contHistory[pos.moved_piece(move)][to_sq(move)].get();
assert(depth >= 5 * ONE_PLY);
pos.do_move(move, st);
- value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, depth - 4 * ONE_PLY, !cutNode, false);
+
+ // Perform a preliminary qsearch to verify that the move holds
+ value = -qsearch<NonPV>(pos, ss+1, -rbeta, -rbeta+1);
+
+ // If the qsearch held perform the regular search
+ if (value >= rbeta)
+ value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, depth - 4 * ONE_PLY, !cutNode, false);
+
pos.undo_move(move);
+
if (value >= rbeta)
return value;
}
// Step 11. Internal iterative deepening (skipped when in check)
if ( depth >= 6 * ONE_PLY
&& !ttMove
- && (PvNode || ss->staticEval + 256 >= beta))
+ && (PvNode || ss->staticEval + 128 >= beta))
{
Depth d = 3 * depth / 4 - 2 * ONE_PLY;
search<NT>(pos, ss, alpha, beta, d, cutNode, true);
tte = TT.probe(posKey, ttHit);
+ ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
ttMove = ttHit ? tte->move() : MOVE_NONE;
}
MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory, &thisThread->captureHistory, 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 */
- ||(ss-2)->staticEval == VALUE_NONE;
singularExtensionNode = !rootNode
&& depth >= 8 * ONE_PLY
extension = DEPTH_ZERO;
captureOrPromotion = pos.capture_or_promotion(move);
movedPiece = pos.moved_piece(move);
-
- givesCheck = type_of(move) == NORMAL && !pos.discovered_check_candidates()
- ? pos.check_squares(type_of(movedPiece)) & to_sq(move)
- : pos.gives_check(move);
+ givesCheck = gives_check(pos, move);
moveCountPruning = depth < 16 * ONE_PLY
&& moveCount >= FutilityMoveCounts[improving][depth / ONE_PLY];
}
else if ( depth < 7 * ONE_PLY
&& !extension
- && !pos.see_ge(move, -PawnValueEg * (depth / ONE_PLY)))
+ && !pos.see_ge(move, -Value(CapturePruneMargin[depth / ONE_PLY])))
continue;
}
// Update the current move (this must be done after singular extension search)
ss->currentMove = move;
- ss->contHistory = &thisThread->contHistory[movedPiece][to_sq(move)];
+ ss->contHistory = thisThread->contHistory[movedPiece][to_sq(move)].get();
// Step 15. Make the move
pos.do_move(move, st, givesCheck);
// Step 17. Full depth search when LMR is skipped or fails high
if (doFullDepthSearch)
- value = newDepth < ONE_PLY ?
- givesCheck ? -qsearch<NonPV, true>(pos, ss+1, -(alpha+1), -alpha)
- : -qsearch<NonPV, false>(pos, ss+1, -(alpha+1), -alpha)
- : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode, false);
+ value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode, false);
// For PV nodes only, do a full PV search on the first move or after a fail
// high (in the latter case search only if value < beta), otherwise let the
(ss+1)->pv = pv;
(ss+1)->pv[0] = MOVE_NONE;
- value = newDepth < ONE_PLY ?
- givesCheck ? -qsearch<PV, true>(pos, ss+1, -beta, -alpha)
- : -qsearch<PV, false>(pos, ss+1, -beta, -alpha)
- : - search<PV>(pos, ss+1, -beta, -alpha, newDepth, false, false);
+ value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, false, false);
}
// Step 18. Undo move
// qsearch() is the quiescence search function, which is called by the main
// search function with depth zero, or recursively with depth less than ONE_PLY.
-
- template <NodeType NT, bool InCheck>
+ template <NodeType NT>
Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
- const bool PvNode = NT == PV;
+ constexpr bool PvNode = NT == PV;
assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE);
assert(PvNode || (alpha == beta - 1));
assert(depth <= DEPTH_ZERO);
assert(depth / ONE_PLY * ONE_PLY == depth);
- assert(InCheck == bool(pos.checkers()));
Move pv[MAX_PLY+1];
StateInfo st;
Move ttMove, move, bestMove;
Depth ttDepth;
Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha;
- bool ttHit, givesCheck, evasionPrunable;
+ bool ttHit, inCheck, givesCheck, evasionPrunable;
int moveCount;
if (PvNode)
(ss+1)->ply = ss->ply + 1;
ss->currentMove = bestMove = MOVE_NONE;
+ inCheck = pos.checkers();
moveCount = 0;
// Check for an immediate draw or maximum ply reached
if ( pos.is_draw(ss->ply)
|| ss->ply >= MAX_PLY)
- return (ss->ply >= MAX_PLY && !InCheck) ? evaluate(pos) : VALUE_DRAW;
+ return (ss->ply >= MAX_PLY && !inCheck) ? evaluate(pos) : VALUE_DRAW;
assert(0 <= ss->ply && ss->ply < MAX_PLY);
// Decide whether or not to include checks: this fixes also the type of
// TT entry depth that we are going to use. Note that in qsearch we use
// only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS.
- ttDepth = InCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS
+ ttDepth = inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS
: DEPTH_QS_NO_CHECKS;
// Transposition table lookup
posKey = pos.key();
tte = TT.probe(posKey, ttHit);
- ttMove = ttHit ? tte->move() : MOVE_NONE;
ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
+ ttMove = ttHit ? tte->move() : MOVE_NONE;
if ( !PvNode
&& ttHit
return ttValue;
// Evaluate the position statically
- if (InCheck)
+ if (inCheck)
{
ss->staticEval = VALUE_NONE;
bestValue = futilityBase = -VALUE_INFINITE;
{
assert(is_ok(move));
- givesCheck = type_of(move) == NORMAL && !pos.discovered_check_candidates()
- ? pos.check_squares(type_of(pos.moved_piece(move))) & to_sq(move)
- : pos.gives_check(move);
+ givesCheck = gives_check(pos, move);
moveCount++;
// Futility pruning
- if ( !InCheck
+ if ( !inCheck
&& !givesCheck
&& futilityBase > -VALUE_KNOWN_WIN
&& !pos.advanced_pawn_push(move))
}
// Detect non-capture evasions that are candidates to be pruned
- evasionPrunable = InCheck
+ 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)
+ if ( (!inCheck || evasionPrunable)
&& !pos.see_ge(move))
continue;
// Make and search the move
pos.do_move(move, st, givesCheck);
- value = givesCheck ? -qsearch<NT, true>(pos, ss+1, -beta, -alpha, depth - ONE_PLY)
- : -qsearch<NT, false>(pos, ss+1, -beta, -alpha, depth - ONE_PLY);
+ value = -qsearch<NT>(pos, ss+1, -beta, -alpha, depth - ONE_PLY);
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
// All legal moves have been searched. A special case: If we're in check
// and no legal moves were found, it is checkmate.
- if (InCheck && bestValue == -VALUE_INFINITE)
+ if (inCheck && bestValue == -VALUE_INFINITE)
return mated_in(ss->ply); // Plies to mate from the root
tte->save(posKey, value_to_tt(bestValue, ss->ply),
for (int i : {1, 2, 4})
if (is_ok((ss-i)->currentMove))
- (ss-i)->contHistory->update(pc, to, bonus);
+ (*(ss-i)->contHistory)[pc][to] << bonus;
}
CapturePieceToHistory& captureHistory = pos.this_thread()->captureHistory;
Piece moved_piece = pos.moved_piece(move);
PieceType captured = type_of(pos.piece_on(to_sq(move)));
- captureHistory.update(moved_piece, to_sq(move), captured, bonus);
+ captureHistory[moved_piece][to_sq(move)][captured] << bonus;
// Decrease all the other played capture moves
for (int i = 0; i < captureCnt; ++i)
{
moved_piece = pos.moved_piece(captures[i]);
captured = type_of(pos.piece_on(to_sq(captures[i])));
- captureHistory.update(moved_piece, to_sq(captures[i]), captured, -bonus);
+ captureHistory[moved_piece][to_sq(captures[i])][captured] << -bonus;
}
}
Color us = pos.side_to_move();
Thread* thisThread = pos.this_thread();
- thisThread->mainHistory.update(us, move, bonus);
+ thisThread->mainHistory[us][from_to(move)] << bonus;
update_continuation_histories(ss, 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)
{
- thisThread->mainHistory.update(us, quiets[i], -bonus);
+ thisThread->mainHistory[us][from_to(quiets[i])] << -bonus;
update_continuation_histories(ss, pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
}
}
return;
// When using nodes, ensure checking rate is not lower than 0.1% of nodes
- callsCnt = Limits.nodes ? std::min(4096, int(Limits.nodes / 1024)) : 4096;
+ callsCnt = Limits.nodes ? std::min(1024, int(Limits.nodes / 1024)) : 1024;
static TimePoint lastInfoTime = now();
- int elapsed = Time.elapsed();
+ TimePoint elapsed = Time.elapsed();
TimePoint tick = Limits.startTime + elapsed;
if (tick - lastInfoTime >= 1000)
string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) {
std::stringstream ss;
- int elapsed = Time.elapsed() + 1;
+ TimePoint elapsed = Time.elapsed() + 1;
const RootMoves& rootMoves = pos.this_thread()->rootMoves;
size_t PVIdx = pos.this_thread()->PVIdx;
size_t multiPV = std::min((size_t)Options["MultiPV"], rootMoves.size());
projects / stockfish / blobdiff