// Last seconds noise filtering (LSN)
const bool UseLSNFiltering = true;
- const int LSNTime = 4000; // In milliseconds
+ const int LSNTime = 100; // In milliseconds
const Value LSNValue = value_from_centipawns(200);
bool loseOnTime = false;
template <NodeType PvNode>
Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool singleEvasion, bool mateThreat, bool* dangerous);
- void update_pv(SearchStack* ss, int ply);
- void sp_update_pv(SearchStack* pss, SearchStack* ss, int ply);
+ void update_pv(SearchStack* ss);
+ void sp_update_pv(SearchStack* pss, SearchStack* ss);
bool connected_moves(const Position& pos, Move m1, Move m2);
bool value_is_mate(Value value);
bool move_is_killer(Move m, SearchStack* ss);
// SearchStack::init() initializes a search stack. Used at the beginning of a
// new search from the root.
-void SearchStack::init(int ply) {
+void SearchStack::init() {
- pv[ply] = pv[ply + 1] = MOVE_NONE;
+ pv[0] = pv[1] = MOVE_NONE;
currentMove = threatMove = MOVE_NONE;
reduction = Depth(0);
eval = VALUE_NONE;
ss->reduction = reduction<PV>(depth, i - MultiPV + 2);
if (ss->reduction)
{
+ assert(newDepth-ss->reduction >= OnePly);
+
// Reduced depth non-pv search using alpha as upperbound
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction);
doFullDepthSearch = (value > alpha);
}
+
+ // The move failed high, but if reduction is very big we could
+ // face a false positive, retry with a less aggressive reduction,
+ // if the move fails high again then go with full depth search.
+ if (doFullDepthSearch && ss->reduction > 2 * OnePly)
+ {
+ assert(newDepth - OnePly >= OnePly);
+
+ ss->reduction = OnePly;
+ value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth-ss->reduction);
+ doFullDepthSearch = (value > alpha);
+ }
+ ss->reduction = Depth(0); // Restore original reduction
}
// Step 15. Full depth search
if (doFullDepthSearch)
{
// Full depth non-pv search using alpha as upperbound
- ss->reduction = Depth(0);
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth);
// If we are above alpha then research at same depth but as PV
// We are failing high and going to do a research. It's important to update
// the score before research in case we run out of time while researching.
rml.set_move_score(i, value);
- update_pv(ss, 0);
+ update_pv(ss);
TT.extract_pv(pos, ss->pv, PLY_MAX);
rml.set_move_pv(i, ss->pv);
// Update PV
rml.set_move_score(i, value);
- update_pv(ss, 0);
+ update_pv(ss);
TT.extract_pv(pos, ss->pv, PLY_MAX);
rml.set_move_pv(i, ss->pv);
// Step 1. Initialize node and poll. Polling can abort search
TM.incrementNodeCounter(threadID);
- ss->init(ply);
- (ss + 2)->initKillers();
+ ss->init();
+ (ss+2)->initKillers();
if (threadID == 0 && ++NodesSincePoll > NodesBetweenPolls)
{
&& !value_is_mate(beta)
&& !pos.has_pawn_on_7th(pos.side_to_move()))
{
+ // Pass ss->eval to qsearch() and avoid an evaluate call
+ if (!tte || tte->static_value() == VALUE_NONE)
+ TT.store(posKey, ss->eval, VALUE_TYPE_EXACT, Depth(-127*OnePly), MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]);
+
Value rbeta = beta - razor_margin(depth);
Value v = qsearch<NonPV>(pos, ss, rbeta-1, rbeta, Depth(0));
if (v < rbeta)
search<PvNode>(pos, ss, alpha, beta, d);
ss->skipNullMove = false;
- ttMove = ss->pv[ply];
+ ttMove = ss->pv[0];
tte = TT.retrieve(posKey);
}
if (PvNode && value < beta) // This guarantees that always: alpha < beta
alpha = value;
- update_pv(ss, ply);
+ update_pv(ss);
if (value == value_mate_in(ply + 1))
ss->mateKiller = move;
else if (bestValue >= beta)
{
TM.incrementBetaCounter(pos.side_to_move(), depth, threadID);
- move = ss->pv[ply];
+ move = ss->pv[0];
TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move, ss->eval, ei.kingDanger[pos.side_to_move()]);
if (!pos.move_is_capture_or_promotion(move))
{
}
}
else
- TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, depth, ss->pv[ply], ss->eval, ei.kingDanger[pos.side_to_move()]);
+ TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, depth, ss->pv[0], ss->eval, ei.kingDanger[pos.side_to_move()]);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
EvalInfo ei;
StateInfo st;
Move ttMove, move;
- Value staticValue, bestValue, value, futilityBase, futilityValue;
- bool isCheck, enoughMaterial, moveIsCheck, evasionPrunable;
- const TTEntry* tte = NULL;
- int moveCount = 0;
- int ply = pos.ply();
+ Value bestValue, value, futilityValue, futilityBase;
+ bool isCheck, deepChecks, enoughMaterial, moveIsCheck, evasionPrunable;
+ const TTEntry* tte;
Value oldAlpha = alpha;
+ int ply = pos.ply();
TM.incrementNodeCounter(pos.thread());
- ss->init(ply);
+ ss->pv[0] = ss->pv[1] = ss->currentMove = MOVE_NONE;
+ ss->eval = VALUE_NONE;
// Check for an instant draw or maximum ply reached
if (pos.is_draw() || ply >= PLY_MAX - 1)
// Evaluate the position statically
if (isCheck)
- staticValue = -VALUE_INFINITE;
- else if (tte && tte->static_value() != VALUE_NONE)
{
- staticValue = tte->static_value();
- ei.kingDanger[pos.side_to_move()] = tte->king_danger();
+ bestValue = futilityBase = -VALUE_INFINITE;
+ deepChecks = enoughMaterial = false;
}
else
- staticValue = evaluate(pos, ei);
-
- if (!isCheck)
{
- ss->eval = staticValue;
+ if (tte && tte->static_value() != VALUE_NONE)
+ {
+ ei.kingDanger[pos.side_to_move()] = tte->king_danger();
+ bestValue = tte->static_value();
+ }
+ else
+ bestValue = evaluate(pos, ei);
+
+ ss->eval = bestValue;
update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval);
- }
- // Initialize "stand pat score", and return it immediately if it is
- // at least beta.
- bestValue = staticValue;
+ // Stand pat. Return immediately if static value is at least beta
+ if (bestValue >= beta)
+ {
+ if (!tte)
+ TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, Depth(-127*OnePly), MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]);
- if (bestValue >= beta)
- {
- // Store the score to avoid a future costly evaluation() call
- if (!isCheck && !tte)
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, Depth(-127*OnePly), MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]);
+ return bestValue;
+ }
- return bestValue;
- }
+ if (PvNode && bestValue > alpha)
+ alpha = bestValue;
- if (bestValue > alpha)
- alpha = bestValue;
+ // If we are near beta then try to get a cutoff pushing checks a bit further
+ deepChecks = (depth == -OnePly && bestValue >= beta - PawnValueMidgame / 8);
- // If we are near beta then try to get a cutoff pushing checks a bit further
- bool deepChecks = (depth == -OnePly && staticValue >= beta - PawnValueMidgame / 8);
+ // Futility pruning parameters, not needed when in check
+ futilityBase = bestValue + FutilityMarginQS + ei.kingDanger[pos.side_to_move()];
+ enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame;
+ }
// Initialize a MovePicker object for the current position, and prepare
// to search the moves. Because the depth is <= 0 here, only captures,
// and we are near beta) will be generated.
MovePicker mp = MovePicker(pos, ttMove, deepChecks ? Depth(0) : depth, H);
CheckInfo ci(pos);
- enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame;
- futilityBase = staticValue + FutilityMarginQS + ei.kingDanger[pos.side_to_move()];
// Loop through the moves until no moves remain or a beta cutoff occurs
while ( alpha < beta
moveIsCheck = pos.move_is_check(move, ci);
- // Update current move
- moveCount++;
- ss->currentMove = move;
-
// Futility pruning
if ( !PvNode
- && enoughMaterial
&& !isCheck
&& !moveIsCheck
&& move != ttMove
+ && enoughMaterial
&& !move_is_promotion(move)
&& !pos.move_is_passed_pawn_push(move))
{
&& pos.see_sign(move) < 0)
continue;
+ // Update current move
+ ss->currentMove = move;
+
// Make and search the move
pos.do_move(move, st, ci, moveIsCheck);
value = -qsearch<PvNode>(pos, ss+1, -beta, -alpha, depth-OnePly);
if (value > alpha)
{
alpha = value;
- update_pv(ss, ply);
+ update_pv(ss);
}
}
}
// All legal moves have been searched. A special case: If we're in check
// and no legal moves were found, it is checkmate.
- if (!moveCount && isCheck) // Mate!
+ if (isCheck && bestValue == -VALUE_INFINITE)
return value_mated_in(ply);
// Update transposition table
Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1));
if (bestValue <= oldAlpha)
- {
- // If bestValue isn't changed it means it is still the static evaluation
- // of the node, so keep this info to avoid a future evaluation() call.
TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, d, MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]);
- }
else if (bestValue >= beta)
{
- move = ss->pv[ply];
+ move = ss->pv[0];
TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move, ss->eval, ei.kingDanger[pos.side_to_move()]);
// Update killers only for good checking moves
update_killers(move, ss);
}
else
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, d, ss->pv[ply], ss->eval, ei.kingDanger[pos.side_to_move()]);
+ TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, d, ss->pv[0], ss->eval, ei.kingDanger[pos.side_to_move()]);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
Position pos(*sp->pos, threadID);
CheckInfo ci(pos);
- int ply = pos.ply();
SearchStack* ss = sp->sstack[threadID] + 1;
isCheck = pos.is_check();
if (PvNode && value < sp->beta) // This guarantees that always: sp->alpha < sp->beta
sp->alpha = value;
- sp_update_pv(sp->parentSstack, ss, ply);
+ sp_update_pv(sp->parentSstack, ss);
}
}
}
// It updates the PV in the SearchStack object corresponding to the
// current node.
- void update_pv(SearchStack* ss, int ply) {
-
- assert(ply >= 0 && ply < PLY_MAX);
-
- int p;
+ void update_pv(SearchStack* ss) {
- ss->pv[ply] = ss->currentMove;
+ Move* src = (ss+1)->pv;
+ Move* dst = ss->pv;
- for (p = ply + 1; (ss+1)->pv[p] != MOVE_NONE; p++)
- ss->pv[p] = (ss+1)->pv[p];
+ *dst = ss->currentMove;
- ss->pv[p] = MOVE_NONE;
+ do
+ *++dst = *src;
+ while (*src++ != MOVE_NONE);
}
// difference between the two functions is that sp_update_pv also updates
// the PV at the parent node.
- void sp_update_pv(SearchStack* pss, SearchStack* ss, int ply) {
-
- assert(ply >= 0 && ply < PLY_MAX);
-
- int p;
+ void sp_update_pv(SearchStack* pss, SearchStack* ss) {
- ss->pv[ply] = pss->pv[ply] = ss->currentMove;
+ Move* src = (ss+1)->pv;
+ Move* dst = ss->pv;
+ Move* pdst = pss->pv;
- for (p = ply + 1; (ss+1)->pv[p] != MOVE_NONE; p++)
- ss->pv[p] = pss->pv[p] = (ss+1)->pv[p];
+ *dst = *pdst = ss->currentMove;
- ss->pv[p] = pss->pv[p] = MOVE_NONE;
+ do
+ *++dst = *++pdst = *src;
+ while (*src++ != MOVE_NONE);
}
if (i < 3)
{
- ss->init(i);
+ ss->init();
ss->initKillers();
}
}
projects / stockfish / blobdiff