TimeManager TimeMgr;
int BestMoveChanges;
Value DrawValue[COLOR_NB];
- History Hist;
- Gains Gain;
+ HistoryStats History;
+ GainsStats Gains;
+ CountermovesStats Countermoves;
template <NodeType NT>
- Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
+ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode);
template <NodeType NT, bool InCheck>
Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
// Init futility move count array
for (d = 0; d < 32; d++)
- FutilityMoveCounts[d] = int(3.001 + 0.25 * pow(double(d), 2.0));
+ FutilityMoveCounts[d] = int(3.001 + 0.3 * pow(double(d), 1.8));
}
size_t cnt = 0;
CheckInfo ci(pos);
- for (MoveList<LEGAL> ml(pos); !ml.end(); ++ml)
+ for (MoveList<LEGAL> it(pos); *it; ++it)
{
- pos.do_move(ml.move(), st, ci, pos.move_gives_check(ml.move(), ci));
+ pos.do_move(*it, st, ci, pos.move_gives_check(*it, ci));
cnt += perft(pos, depth - ONE_PLY);
- pos.undo_move(ml.move());
+ pos.undo_move(*it);
}
return cnt;
finalize:
+ // When search is stopped this info is not printed
+ sync_cout << "info nodes " << RootPos.nodes_searched()
+ << " time " << Time::now() - SearchTime + 1 << sync_endl;
+
// When we reach max depth we arrive here even without Signals.stop is raised,
// but if we are pondering or in infinite search, according to UCI protocol,
// we shouldn't print the best move before the GUI sends a "stop" or "ponderhit"
void id_loop(Position& pos) {
- Stack ss[MAX_PLY_PLUS_2];
+ Stack stack[MAX_PLY_PLUS_2], *ss = stack+1; // To allow referencing (ss-1)
int depth, prevBestMoveChanges;
Value bestValue, alpha, beta, delta;
- bool triedEasyMove = false;
- memset(ss, 0, 4 * sizeof(Stack));
+ memset(ss-1, 0, 4 * sizeof(Stack));
depth = BestMoveChanges = 0;
bestValue = delta = -VALUE_INFINITE;
- ss->currentMove = MOVE_NULL; // Hack to skip update gains
+ (ss-1)->currentMove = MOVE_NULL; // Hack to skip update gains
TT.new_search();
- Hist.clear();
- Gain.clear();
+ History.clear();
+ Gains.clear();
+ Countermoves.clear();
PVSize = Options["MultiPV"];
Skill skill(Options["Skill Level"]);
// research with bigger window until not failing high/low anymore.
while (true)
{
- // Search starts from ss+1 to allow referencing (ss-1). This is
- // needed by update gains and ss copy when splitting at Root.
- bestValue = search<Root>(pos, ss+1, alpha, beta, depth * ONE_PLY);
+ bestValue = search<Root>(pos, ss, alpha, beta, depth * ONE_PLY, false);
// Bring to front the best move. It is critical that sorting is
// done with a stable algorithm because all the values but the first
if (Options["Use Search Log"])
{
+ RootMove& rm = RootMoves[0];
+ if (skill.best != MOVE_NONE)
+ rm = *std::find(RootMoves.begin(), RootMoves.end(), skill.best);
+
Log log(Options["Search Log Filename"]);
- log << pretty_pv(pos, depth, bestValue, Time::now() - SearchTime, &RootMoves[0].pv[0])
+ log << pretty_pv(pos, depth, rm.score, Time::now() - SearchTime, &rm.pv[0])
<< std::endl;
}
// Stop search early if one move seems to be much better than others
if ( depth >= 12
&& !stop
- && !triedEasyMove
&& PVSize == 1
+ && bestValue > VALUE_MATED_IN_MAX_PLY
&& ( RootMoves.size() == 1
|| Time::now() - SearchTime > (TimeMgr.available_time() * 20) / 100))
{
- triedEasyMove = true;
Value rBeta = bestValue - 2 * PawnValueMg;
- (ss+1)->excludedMove = RootMoves[0].pv[0];
- (ss+1)->skipNullMove = true;
- Value v = search<NonPV>(pos, ss+1, rBeta - 1, rBeta, (depth - 3) * ONE_PLY);
- (ss+1)->skipNullMove = false;
- (ss+1)->excludedMove = MOVE_NONE;
+ ss->excludedMove = RootMoves[0].pv[0];
+ ss->skipNullMove = true;
+ Value v = search<NonPV>(pos, ss, rBeta - 1, rBeta, (depth - 3) * ONE_PLY, true);
+ ss->skipNullMove = false;
+ ss->excludedMove = MOVE_NONE;
if (v < rBeta)
stop = true;
// here: This is taken care of after we return from the split point.
template <NodeType NT>
- Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
+ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode) {
const bool PvNode = (NT == PV || NT == Root || NT == SplitPointPV || NT == SplitPointRoot);
const bool SpNode = (NT == SplitPointPV || NT == SplitPointNonPV || NT == SplitPointRoot);
bestValue = -VALUE_INFINITE;
ss->currentMove = threatMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
ss->ply = (ss-1)->ply + 1;
+ ss->futilityMoveCount = 0;
(ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO;
(ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
if (!RootNode)
{
// Step 2. Check for aborted search and immediate draw
- if (Signals.stop || pos.is_draw<false>() || ss->ply > MAX_PLY)
+ if (Signals.stop || pos.is_draw() || ss->ply > MAX_PLY)
return DrawValue[pos.side_to_move()];
// Step 3. Mate distance pruning. Even if we mate at the next move our score
&& type_of(move) == NORMAL)
{
Square to = to_sq(move);
- Gain.update(pos.piece_on(to), to, -(ss-1)->staticEval - ss->staticEval);
+ Gains.update(pos.piece_on(to), to, -(ss-1)->staticEval - ss->staticEval);
}
// Step 6. Razoring (is omitted in PV nodes)
&& !ss->skipNullMove
&& depth < 4 * ONE_PLY
&& !inCheck
- && eval - FutilityMargins[depth][0] >= beta
+ && eval - futility_margin(depth, (ss-1)->futilityMoveCount) >= beta
&& abs(beta) < VALUE_MATE_IN_MAX_PLY
+ && abs(eval) < VALUE_KNOWN_WIN
&& pos.non_pawn_material(pos.side_to_move()))
- return eval - FutilityMargins[depth][0];
+ return eval - futility_margin(depth, (ss-1)->futilityMoveCount);
// Step 8. Null move search with verification search (is omitted in PV nodes)
if ( !PvNode
pos.do_null_move(st);
(ss+1)->skipNullMove = true;
nullValue = depth-R < ONE_PLY ? -qsearch<NonPV, false>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
- : - search<NonPV>(pos, ss+1, -beta, -alpha, depth-R);
+ : - search<NonPV>(pos, ss+1, -beta, -alpha, depth-R, !cutNode);
(ss+1)->skipNullMove = false;
pos.undo_null_move();
if (nullValue >= VALUE_MATE_IN_MAX_PLY)
nullValue = beta;
- if (depth < 6 * ONE_PLY)
+ if (depth < 12 * ONE_PLY)
return nullValue;
// Do verification search at high depths
ss->skipNullMove = true;
- Value v = search<NonPV>(pos, ss, alpha, beta, depth-R);
+ Value v = search<NonPV>(pos, ss, alpha, beta, depth-R, false);
ss->skipNullMove = false;
if (v >= beta)
&& (ss-1)->reduction
&& threatMove != MOVE_NONE
&& allows(pos, (ss-1)->currentMove, threatMove))
- return beta - 1;
+ return alpha;
}
}
assert((ss-1)->currentMove != MOVE_NONE);
assert((ss-1)->currentMove != MOVE_NULL);
- MovePicker mp(pos, ttMove, Hist, pos.captured_piece_type());
+ MovePicker mp(pos, ttMove, History, pos.captured_piece_type());
CheckInfo ci(pos);
while ((move = mp.next_move<false>()) != MOVE_NONE)
{
ss->currentMove = move;
pos.do_move(move, st, ci, pos.move_gives_check(move, ci));
- value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, rdepth);
+ value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, rdepth, !cutNode);
pos.undo_move(move);
if (value >= rbeta)
return value;
&& ttMove == MOVE_NONE
&& (PvNode || (!inCheck && ss->staticEval + Value(256) >= beta)))
{
- Depth d = (PvNode ? depth - 2 * ONE_PLY : depth / 2);
+ Depth d = depth - 2 * ONE_PLY - (PvNode ? DEPTH_ZERO : depth / 4);
ss->skipNullMove = true;
- search<PvNode ? PV : NonPV>(pos, ss, alpha, beta, d);
+ search<PvNode ? PV : NonPV>(pos, ss, alpha, beta, d, true);
ss->skipNullMove = false;
tte = TT.probe(posKey);
split_point_start: // At split points actual search starts from here
- MovePicker mp(pos, ttMove, depth, Hist, ss, PvNode ? -VALUE_INFINITE : beta);
+ Square prevMoveSq = to_sq((ss-1)->currentMove);
+ Move countermoves[] = { Countermoves[pos.piece_on(prevMoveSq)][prevMoveSq].first,
+ Countermoves[pos.piece_on(prevMoveSq)][prevMoveSq].second };
+
+ MovePicker mp(pos, ttMove, depth, History, countermoves, ss, PvNode ? -VALUE_INFINITE : beta);
CheckInfo ci(pos);
value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
singularExtensionNode = !RootNode
Value rBeta = ttValue - int(depth);
ss->excludedMove = move;
ss->skipNullMove = true;
- value = search<NonPV>(pos, ss, rBeta - 1, rBeta, depth / 2);
+ value = search<NonPV>(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode);
ss->skipNullMove = false;
ss->excludedMove = MOVE_NONE;
&& !captureOrPromotion
&& !inCheck
&& !dangerous
- && move != ttMove)
+ /* && move != ttMove Already implicit in the next condition */
+ && bestValue > VALUE_MATED_IN_MAX_PLY)
{
// Move count based pruning
if ( depth < 16 * ONE_PLY
// but fixing this made program slightly weaker.
Depth predictedDepth = newDepth - reduction<PvNode>(depth, moveCount);
futilityValue = ss->staticEval + ss->evalMargin + futility_margin(predictedDepth, moveCount)
- + Gain[pos.piece_moved(move)][to_sq(move)];
+ + Gains[pos.piece_moved(move)][to_sq(move)];
if (futilityValue < beta)
{
+ bestValue = std::max(bestValue, futilityValue);
+
if (SpNode)
+ {
splitPoint->mutex.lock();
-
+ if (bestValue > splitPoint->bestValue)
+ splitPoint->bestValue = bestValue;
+ }
continue;
}
// Prune moves with negative SEE at low depths
- if ( predictedDepth < 3 * ONE_PLY
+ if ( predictedDepth < 4 * ONE_PLY
&& pos.see_sign(move) < 0)
{
if (SpNode)
continue;
}
+
+ // We have not pruned the move that will be searched, but remember how
+ // far in the move list we are to be more aggressive in the child node.
+ ss->futilityMoveCount = moveCount;
}
+ else
+ ss->futilityMoveCount = 0;
// Check for legality only before to do the move
if (!RootNode && !SpNode && !pos.pl_move_is_legal(move, ci.pinned))
&& move != ss->killers[1])
{
ss->reduction = reduction<PvNode>(depth, moveCount);
+
+ if (!PvNode && cutNode)
+ ss->reduction += ONE_PLY;
+
+ if (move == countermoves[0] || move == countermoves[1])
+ ss->reduction = std::max(DEPTH_ZERO, ss->reduction-ONE_PLY);
+
Depth d = std::max(newDepth - ss->reduction, ONE_PLY);
if (SpNode)
alpha = splitPoint->alpha;
- value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d);
+ value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
doFullDepthSearch = (value > alpha && ss->reduction != DEPTH_ZERO);
ss->reduction = DEPTH_ZERO;
value = newDepth < ONE_PLY ?
givesCheck ? -qsearch<NonPV, true>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
: -qsearch<NonPV, false>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
- : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth);
+ : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode);
}
// Only for PV nodes do a full PV search on the first move or after a fail
value = newDepth < ONE_PLY ?
givesCheck ? -qsearch<PV, true>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
: -qsearch<PV, false>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
- : - search<PV>(pos, ss+1, -beta, -alpha, newDepth);
+ : - search<PV>(pos, ss+1, -beta, -alpha, newDepth, false);
// Step 17. Undo move
pos.undo_move(move);
assert(bestValue < beta);
thisThread->split<FakeSplit>(pos, ss, alpha, beta, &bestValue, &bestMove,
- depth, threatMove, moveCount, &mp, NT);
+ depth, threatMove, moveCount, &mp, NT, cutNode);
if (bestValue >= beta)
break;
}
// Increase history value of the cut-off move
Value bonus = Value(int(depth) * int(depth));
- Hist.update(pos.piece_moved(bestMove), to_sq(bestMove), bonus);
+ History.update(pos.piece_moved(bestMove), to_sq(bestMove), bonus);
+ if (is_ok((ss-1)->currentMove))
+ Countermoves.update(pos.piece_on(prevMoveSq), prevMoveSq, bestMove);
// Decrease history of all the other played non-capture moves
for (int i = 0; i < playedMoveCount - 1; i++)
{
Move m = movesSearched[i];
- Hist.update(pos.piece_moved(m), to_sq(m), -bonus);
+ History.update(pos.piece_moved(m), to_sq(m), -bonus);
}
}
}
ss->ply = (ss-1)->ply + 1;
// Check for an instant draw or maximum ply reached
- if (pos.is_draw<true>() || ss->ply > MAX_PLY)
+ if (pos.is_draw() || ss->ply > MAX_PLY)
return DrawValue[pos.side_to_move()];
// Decide whether or not to include checks, this fixes also the type of
// 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, Hist, to_sq((ss-1)->currentMove));
+ MovePicker mp(pos, ttMove, depth, History, to_sq((ss-1)->currentMove));
CheckInfo ci(pos);
// Loop through the moves until no moves remain or a beta cutoff occurs
continue;
}
- // Prune moves with negative or equal SEE
+ // Prune moves with negative or equal SEE and also moves with positive
+ // SEE where capturing piece loses a tempo and SEE < beta - futilityBase.
if ( futilityBase < beta
- && depth < DEPTH_ZERO
- && pos.see(move) <= 0)
+ && pos.see(move, beta - futilityBase) <= 0)
{
bestValue = std::max(bestValue, futilityBase);
continue;
{
// Update occupancy as if the piece and the threat are moving
Bitboard occ = pos.pieces() ^ m1from ^ m1to ^ m2from;
- Piece piece = pos.piece_on(m1from);
+ Piece pc = pos.piece_on(m1from);
// The moved piece attacks the square 'tto' ?
- if (pos.attacks_from(piece, m1to, occ) & m2to)
+ if (pos.attacks_from(pc, m1to, occ) & m2to)
return true;
// Scan for possible X-ray attackers behind the moved piece
- Bitboard xray = (attacks_bb< ROOK>(m2to, occ) & pos.pieces(color_of(piece), QUEEN, ROOK))
- | (attacks_bb<BISHOP>(m2to, occ) & pos.pieces(color_of(piece), QUEEN, BISHOP));
+ Bitboard xray = (attacks_bb< ROOK>(m2to, occ) & pos.pieces(color_of(pc), QUEEN, ROOK))
+ | (attacks_bb<BISHOP>(m2to, occ) & pos.pieces(color_of(pc), QUEEN, BISHOP));
// Verify attackers are triggered by our move and not already existing
if (xray && (xray ^ (xray & pos.attacks_from<QUEEN>(m2to))))
string uci_pv(const Position& pos, int depth, Value alpha, Value beta) {
std::stringstream s;
- Time::point elaspsed = Time::now() - SearchTime + 1;
+ Time::point elapsed = Time::now() - SearchTime + 1;
size_t uciPVSize = std::min((size_t)Options["MultiPV"], RootMoves.size());
int selDepth = 0;
<< " seldepth " << selDepth
<< " score " << (i == PVIdx ? score_to_uci(v, alpha, beta) : score_to_uci(v))
<< " nodes " << pos.nodes_searched()
- << " nps " << pos.nodes_searched() * 1000 / elaspsed
- << " time " << elaspsed
+ << " nps " << pos.nodes_searched() * 1000 / elapsed
+ << " time " << elapsed
<< " multipv " << i + 1
<< " pv";
&& pos.is_pseudo_legal(m = tte->move()) // Local copy, TT could change
&& pos.pl_move_is_legal(m, pos.pinned_pieces())
&& ply < MAX_PLY
- && (!pos.is_draw<false>() || ply < 2));
+ && (!pos.is_draw() || ply < 2));
pv.push_back(MOVE_NONE); // Must be zero-terminating
Threads.mutex.unlock();
- Stack ss[MAX_PLY_PLUS_2];
+ Stack stack[MAX_PLY_PLUS_2], *ss = stack+1; // To allow referencing (ss-1)
Position pos(*sp->pos, this);
- memcpy(ss, sp->ss - 1, 4 * sizeof(Stack));
- (ss+1)->splitPoint = sp;
+ memcpy(ss-1, sp->ss-1, 4 * sizeof(Stack));
+ ss->splitPoint = sp;
sp->mutex.lock();
switch (sp->nodeType) {
case Root:
- search<SplitPointRoot>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
+ search<SplitPointRoot>(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode);
break;
case PV:
- search<SplitPointPV>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
+ search<SplitPointPV>(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode);
break;
case NonPV:
- search<SplitPointNonPV>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
+ search<SplitPointNonPV>(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode);
break;
default:
assert(false);
projects / stockfish / blobdiff