/// Types
+ // The BetaCounterType class is used to order moves at ply one.
+ // Apart for the first one that has its score, following moves
+ // normally have score -VALUE_INFINITE, so are ordered according
+ // to the number of beta cutoffs occurred under their subtree during
+ // the last iteration.
+
+ struct BetaCounterType {
+
+ BetaCounterType();
+ void clear();
+ void add(Color us, Depth d, int threadID);
+ void read(Color us, int64_t& our, int64_t& their);
+
+ int64_t hits[THREAD_MAX][2];
+ };
+
+
// The RootMove class is used for moves at the root at the tree. For each
// root move, we store a score, a node count, and a PV (really a refutation
// in the case of moves which fail low).
Value score;
int64_t nodes, cumulativeNodes;
Move pv[PLY_MAX_PLUS_2];
+ int64_t ourBeta, theirBeta;
};
inline Value get_move_score(int moveNum) const;
inline void set_move_score(int moveNum, Value score);
inline void set_move_nodes(int moveNum, int64_t nodes);
+ inline void set_beta_counters(int moveNum, int64_t our, int64_t their);
void set_move_pv(int moveNum, const Move pv[]);
inline Move get_move_pv(int moveNum, int i) const;
inline int64_t get_move_cumulative_nodes(int moveNum) const;
const bool UseIIDAtPVNodes = true;
const bool UseIIDAtNonPVNodes = false;
+ // Use null move driven internal iterative deepening?
+ bool UseNullDrivenIID = false;
+
// Internal iterative deepening margin. At Non-PV moves, when
// UseIIDAtNonPVNodes is true, we do an internal iterative deepening search
// when the static evaluation is at most IIDMargin below beta.
const Value IIDMargin = Value(0x100);
- // Use easy moves?
- const bool UseEasyMove = true;
-
// Easy move margin. An easy move candidate must be at least this much
// better than the second best move.
const Value EasyMoveMargin = Value(0x200);
bool UseQSearchFutilityPruning = true;
bool UseFutilityPruning = true;
- // Margins for futility pruning in the quiescence search, at frontier
- // nodes, and at pre-frontier nodes
- Value FutilityMargin0 = Value(0x80);
- Value FutilityMargin1 = Value(0x100);
- Value FutilityMargin2 = Value(0x300);
+ // Margins for futility pruning in the quiescence search, and at frontier
+ // and near frontier nodes
+ Value FutilityMarginQS = Value(0x80);
+ Value FutilityMargins[6] = { Value(0x120), Value(0x220), Value(0x250),
+ Value(0x280), Value(0x320), Value(0x360) };
// Razoring
Depth RazorDepth = 4*OnePly;
int NodesSincePoll;
int NodesBetweenPolls = 30000;
- // Iteration counter
+ // Iteration counters
int Iteration;
bool LastIterations;
+ BetaCounterType BetaCounter;
// Scores and number of times the best move changed for each iteration:
Value ValueByIteration[PLY_MAX_PLUS_2];
// Time managment variables
int SearchStartTime;
int MaxNodes, MaxDepth;
- int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime, TimeAdvantage;
+ int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime;
Move BestRootMove, PonderMove, EasyMove;
int RootMoveNumber;
bool InfiniteSearch;
Depth depth, int ply, int threadID);
void sp_search(SplitPoint *sp, int threadID);
void sp_search_pv(SplitPoint *sp, int threadID);
- void init_search_stack(SearchStack ss);
+ void init_search_stack(SearchStack& ss);
void init_search_stack(SearchStack ss[]);
void init_node(const Position &pos, SearchStack ss[], int ply, int threadID);
void update_pv(SearchStack ss[], int ply);
void sp_update_pv(SearchStack *pss, SearchStack ss[], int ply);
bool connected_moves(const Position &pos, Move m1, Move m2);
+ bool value_is_mate(Value value);
bool move_is_killer(Move m, const SearchStack& ss);
- Depth extension(const Position &pos, Move m, bool pvNode, bool check, bool singleReply, bool mateThreat);
+ Depth extension(const Position &pos, Move m, bool pvNode, bool check, bool singleReply, bool mateThreat, bool* dangerous);
bool ok_to_do_nullmove(const Position &pos);
bool ok_to_prune(const Position &pos, Move m, Move threat, Depth d);
bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply);
if (UseLogFile)
LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app);
+ UseNullDrivenIID = get_option_value_bool("Null driven IID");
UseQSearchFutilityPruning = get_option_value_bool("Futility Pruning (Quiescence Search)");
UseFutilityPruning = get_option_value_bool("Futility Pruning (Main Search)");
- FutilityMargin0 = value_from_centipawns(get_option_value_int("Futility Margin 0"));
- FutilityMargin1 = value_from_centipawns(get_option_value_int("Futility Margin 1"));
- FutilityMargin2 = value_from_centipawns(get_option_value_int("Futility Margin 2"));
+ FutilityMarginQS = value_from_centipawns(get_option_value_int("Futility Margin (Quiescence Search)"));
+ int fmScale = get_option_value_int("Futility Margin (Main Serach)");
+ for (int i = 0; i < 6; i++)
+ FutilityMargins[i] = (FutilityMargins[i] * fmScale) / 100;
RazorDepth = (get_option_value_int("Maximum Razoring Depth") + 1) * OnePly;
RazorMargin = value_from_centipawns(get_option_value_int("Razoring Margin"));
int myIncrement = increment[side_to_move];
int oppTime = time[1 - side_to_move];
- TimeAdvantage = myTime - oppTime;
-
if (!movesToGo) // Sudden death time control
- {
- if (increment)
+ {
+ if (myIncrement)
{
MaxSearchTime = myTime / 30 + myIncrement;
AbsoluteMaxSearchTime = Max(myTime / 4, myIncrement - 100);
} else { // Blitz game without increment
- MaxSearchTime = myTime / 40;
+ MaxSearchTime = myTime / 30;
AbsoluteMaxSearchTime = myTime / 8;
}
}
ExtraSearchTime = BestMoveChangesByIteration[Iteration] * (MaxSearchTime / 2)
+ BestMoveChangesByIteration[Iteration-1] * (MaxSearchTime / 3);
- // If we need some more and we are in time advantage take it
- if (ExtraSearchTime > 0 && TimeAdvantage > 2 * MaxSearchTime)
- ExtraSearchTime += MaxSearchTime / 2;
-
// Try to guess if the current iteration is the last one or the last two
LastIterations = (current_search_time() > ((MaxSearchTime + ExtraSearchTime)*58) / 128);
if (UseLogFile)
{
+ if (dbg_show_mean)
+ dbg_print_mean(LogFile);
+
+ if (dbg_show_hit_rate)
+ dbg_print_hit_rate(LogFile);
+
UndoInfo u;
LogFile << "Nodes: " << nodes_searched() << std::endl
<< "Nodes/second: " << nps() << std::endl
// are used to sort the root moves at the next iteration.
nodes = nodes_searched();
+ // Reset beta cut-off counters
+ BetaCounter.clear();
+
// Pick the next root move, and print the move and the move number to
// the standard output.
move = ss[0].currentMove = rml.get_move(i);
<< " currmovenumber " << i + 1 << std::endl;
// Decide search depth for this move
- ext = extension(pos, move, true, pos.move_is_check(move), false, false);
+ bool dangerous;
+ ext = extension(pos, move, true, pos.move_is_check(move), false, false, &dangerous);
newDepth = (Iteration - 2) * OnePly + ext + InitialDepth;
// Make the move, and search it
if (Problem && StopOnPonderhit)
StopOnPonderhit = false;
- }
+ }
else
{
value = -search(pos, ss, -alpha, newDepth, 1, true, 0);
// sort the root moves at the next iteration.
rml.set_move_nodes(i, nodes_searched() - nodes);
+ // Remember the beta-cutoff statistics
+ int64_t our, their;
+ BetaCounter.read(pos.side_to_move(), our, their);
+ rml.set_beta_counters(i, our, their);
+
assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE);
if (value <= alpha && i >= MultiPV)
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
- // Initialize, and make an early exit in case of an aborted search,
- // an instant draw, maximum ply reached, etc.
- if (AbortSearch || thread_should_stop(threadID))
- return Value(0);
-
if (depth < OnePly)
return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID);
+ // Initialize, and make an early exit in case of an aborted search,
+ // an instant draw, maximum ply reached, etc.
init_node(pos, ss, ply, threadID);
+ // After init_node() that calls poll()
+ if (AbortSearch || thread_should_stop(threadID))
+ return Value(0);
+
if (pos.is_draw())
return VALUE_DRAW;
Value value, bestValue = -VALUE_INFINITE;
Bitboard dcCandidates = mp.discovered_check_candidates();
bool isCheck = pos.is_check();
- bool mateThreat = MateThreatExtension[1] > Depth(0)
- && pos.has_mate_threat(opposite_color(pos.side_to_move()));
+ bool mateThreat = pos.has_mate_threat(opposite_color(pos.side_to_move()));
// Loop through all legal moves until no moves remain or a beta cutoff
// occurs.
bool singleReply = (isCheck && mp.number_of_moves() == 1);
bool moveIsCheck = pos.move_is_check(move, dcCandidates);
bool moveIsCapture = pos.move_is_capture(move);
- bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move);
movesSearched[moveCount++] = ss[ply].currentMove = move;
if (moveIsCapture)
- ss[ply].currentMoveCaptureValue = pos.midgame_value_of_piece_on(move_to(move));
- else if (move_is_ep(move))
- ss[ply].currentMoveCaptureValue = PawnValueMidgame;
+ ss[ply].currentMoveCaptureValue =
+ move_is_ep(move)? PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move));
else
ss[ply].currentMoveCaptureValue = Value(0);
// Decide the new search depth
- Depth ext = extension(pos, move, true, moveIsCheck, singleReply, mateThreat);
+ bool dangerous;
+ Depth ext = extension(pos, move, true, moveIsCheck, singleReply, mateThreat, &dangerous);
Depth newDepth = depth - OnePly + ext;
// Make and search the move
// Try to reduce non-pv search depth by one ply if move seems not problematic,
// if the move fails high will be re-searched at full depth.
if ( depth >= 2*OnePly
- && ext == Depth(0)
&& moveCount >= LMRPVMoves
+ && !dangerous
&& !moveIsCapture
&& !move_promotion(move)
- && !moveIsPassedPawnPush
&& !move_is_castle(move)
&& !move_is_killer(move, ss[ply]))
{
else
value = alpha + 1; // Just to trigger next condition
- if (value > alpha) // Go with full depth pv search
+ if (value > alpha) // Go with full depth non-pv search
{
ss[ply].reduction = Depth(0);
value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID);
// If we are at ply 1, and we are searching the first root move at
// ply 0, set the 'Problem' variable if the score has dropped a lot
// (from the computer's point of view) since the previous iteration:
- if (Iteration >= 2 && -value <= ValueByIteration[Iteration-1] - ProblemMargin)
+ if ( ply == 1
+ && Iteration >= 2
+ && -value <= ValueByIteration[Iteration-1] - ProblemMargin)
Problem = true;
}
else if (bestValue >= beta)
{
+ BetaCounter.add(pos.side_to_move(), depth, threadID);
Move m = ss[ply].pv[ply];
if (ok_to_history(pos, m)) // Only non capture moves are considered
{
update_history(pos, m, depth, movesSearched, moveCount);
- update_killers(m, ss[ply]);
+ update_killers(m, ss[ply]);
}
TT.store(pos, value_to_tt(bestValue, ply), depth, m, VALUE_TYPE_LOWER);
}
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
- EvalInfo ei;
+ if (depth < OnePly)
+ return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
// Initialize, and make an early exit in case of an aborted search,
// an instant draw, maximum ply reached, etc.
+ init_node(pos, ss, ply, threadID);
+
+ // After init_node() that calls poll()
if (AbortSearch || thread_should_stop(threadID))
return Value(0);
- if (depth < OnePly)
- return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
-
- init_node(pos, ss, ply, threadID);
-
if (pos.is_draw())
return VALUE_DRAW;
+ EvalInfo ei;
+
if (ply >= PLY_MAX - 1)
return evaluate(pos, ei, threadID);
if (tte && ok_to_use_TT(tte, depth, beta, ply))
{
- ss[ply].currentMove = ttMove; // can be MOVE_NONE ?
+ ss[ply].currentMove = ttMove; // can be MOVE_NONE
return value_from_tt(tte->value(), ply);
}
Value approximateEval = quick_evaluate(pos);
bool mateThreat = false;
+ bool nullDrivenIID = false;
bool isCheck = pos.is_check();
// Null move search
if ( allowNullmove
+ && depth > OnePly
&& !isCheck
+ && !value_is_mate(beta)
&& ok_to_do_nullmove(pos)
&& approximateEval >= beta - NullMoveMargin)
{
UndoInfo u;
pos.do_null_move(u);
- int R = (depth > 7 ? 4 : 3);
+ int R = (depth >= 4 * OnePly ? 4 : 3); // Null move dynamic reduction
+
Value nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
+
+ // Check for a null capture artifact, if the value without the null capture
+ // is above beta then mark the node as a suspicious failed low. We will verify
+ // later if we are really under threat.
+ if ( UseNullDrivenIID
+ && nullValue < beta
+ && depth > 6 * OnePly
+ &&!value_is_mate(nullValue)
+ && ttMove == MOVE_NONE
+ && ss[ply + 1].currentMove != MOVE_NONE
+ && pos.move_is_capture(ss[ply + 1].currentMove)
+ && pos.see(ss[ply + 1].currentMove) + nullValue >= beta)
+ nullDrivenIID = true;
+
pos.undo_null_move(u);
- if (nullValue >= beta)
+ if (value_is_mate(nullValue))
+ {
+ /* Do not return unproven mates */
+ }
+ else if (nullValue >= beta)
{
if (depth < 6 * OnePly)
return beta;
return beta;
} else {
// The null move failed low, which means that we may be faced with
- // some kind of threat. If the previous move was reduced, check if
+ // some kind of threat. If the previous move was reduced, check if
// the move that refuted the null move was somehow connected to the
- // move which was reduced. If a connection is found, return a fail
+ // move which was reduced. If a connection is found, return a fail
// low score (which will cause the reduced move to fail high in the
// parent node, which will trigger a re-search with full depth).
if (nullValue == value_mated_in(ply + 2))
+ {
mateThreat = true;
-
+ nullDrivenIID = false;
+ }
ss[ply].threatMove = ss[ply + 1].currentMove;
if ( depth < ThreatDepth
&& ss[ply - 1].reduction
}
}
// Null move search not allowed, try razoring
- else if ( (approximateEval < beta - RazorMargin && depth < RazorDepth)
- ||(approximateEval < beta - PawnValueMidgame && depth <= OnePly))
+ else if ( !value_is_mate(beta)
+ && approximateEval < beta - RazorMargin
+ && depth < RazorDepth
+ && depth > OnePly
+ && ttMove == MOVE_NONE
+ && !pos.has_pawn_on_7th(pos.side_to_move()))
{
Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
- if (v < beta)
+ if (v < beta - RazorMargin / 2 - int(depth - OnePly) * RazorMargin / 8)
return v;
}
search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID);
ttMove = ss[ply].pv[ply];
}
+ else if (nullDrivenIID)
+ {
+ // The null move failed low due to a suspicious capture. Perhaps we
+ // are facing a null capture artifact due to the side to move change
+ // and this position should fail high. So do a normal search with a
+ // reduced depth to get a good ttMove to use in the following full
+ // depth search.
+ Move tm = ss[ply].threatMove;
+
+ assert(tm != MOVE_NONE);
+ assert(ttMove == MOVE_NONE);
+
+ search(pos, ss, beta, depth/2, ply, false, threadID);
+ ttMove = ss[ply].pv[ply];
+ ss[ply].threatMove = tm;
+ }
// Initialize a MovePicker object for the current position, and prepare
// to search all moves:
bool singleReply = (isCheck && mp.number_of_moves() == 1);
bool moveIsCheck = pos.move_is_check(move, dcCandidates);
bool moveIsCapture = pos.move_is_capture(move);
- bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move);
movesSearched[moveCount++] = ss[ply].currentMove = move;
// Decide the new search depth
- Depth ext = extension(pos, move, false, moveIsCheck, singleReply, mateThreat);
+ bool dangerous;
+ Depth ext = extension(pos, move, false, moveIsCheck, singleReply, mateThreat, &dangerous);
Depth newDepth = depth - OnePly + ext;
// Futility pruning
if ( useFutilityPruning
- && ext == Depth(0)
+ && !dangerous
&& !moveIsCapture
- && !moveIsPassedPawnPush
&& !move_promotion(move))
{
+ // History pruning. See ok_to_prune() definition
if ( moveCount >= 2 + int(depth)
&& ok_to_prune(pos, move, ss[ply].threatMove, depth))
continue;
- if (depth < 3 * OnePly && approximateEval < beta)
+ // Value based pruning
+ if (depth < 7 * OnePly && approximateEval < beta)
{
if (futilityValue == VALUE_NONE)
futilityValue = evaluate(pos, ei, threadID)
- + (depth < 2 * OnePly ? FutilityMargin1 : FutilityMargin2);
+ + FutilityMargins[int(depth)/2 - 1]
+ + 32 * (depth & 1);
if (futilityValue < beta)
{
// Try to reduce non-pv search depth by one ply if move seems not problematic,
// if the move fails high will be re-searched at full depth.
- if ( depth >= 2*OnePly
- && ext == Depth(0)
- && moveCount >= LMRNonPVMoves
+ if ( depth >= 2*OnePly
+ && moveCount >= LMRNonPVMoves
+ && !dangerous
&& !moveIsCapture
&& !move_promotion(move)
- && !moveIsPassedPawnPush
&& !move_is_castle(move)
&& !move_is_killer(move, ss[ply]))
{
TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE, VALUE_TYPE_UPPER);
else
{
+ BetaCounter.add(pos.side_to_move(), depth, threadID);
Move m = ss[ply].pv[ply];
if (ok_to_history(pos, m)) // Only non capture moves are considered
{
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
- EvalInfo ei;
-
// Initialize, and make an early exit in case of an aborted search,
// an instant draw, maximum ply reached, etc.
+ init_node(pos, ss, ply, threadID);
+
+ // After init_node() that calls poll()
if (AbortSearch || thread_should_stop(threadID))
return Value(0);
- init_node(pos, ss, ply, threadID);
-
if (pos.is_draw())
return VALUE_DRAW;
return value_from_tt(tte->value(), ply);
// Evaluate the position statically
- Value staticValue = evaluate(pos, ei, threadID);
+ EvalInfo ei;
+ bool isCheck = pos.is_check();
+ Value staticValue = (isCheck ? -VALUE_INFINITE : evaluate(pos, ei, threadID));
if (ply == PLY_MAX - 1)
- return staticValue;
+ return evaluate(pos, ei, threadID);
// Initialize "stand pat score", and return it immediately if it is
// at least beta.
- Value bestValue = (pos.is_check() ? -VALUE_INFINITE : staticValue);
+ Value bestValue = staticValue;
if (bestValue >= beta)
return bestValue;
// Initialize a MovePicker object for the current position, and prepare
// to search the moves. Because the depth is <= 0 here, only captures,
// queen promotions and checks (only if depth == 0) will be generated.
- MovePicker mp = MovePicker(pos, false, MOVE_NONE, EmptySearchStack, depth, &ei);
+ bool pvNode = (beta - alpha != 1);
+ MovePicker mp = MovePicker(pos, pvNode, MOVE_NONE, EmptySearchStack, depth, isCheck ? NULL : &ei);
Move move;
int moveCount = 0;
Bitboard dcCandidates = mp.discovered_check_candidates();
- bool isCheck = pos.is_check();
- bool pvNode = (beta - alpha != 1);
bool enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame;
// Loop through the moves until no moves remain or a beta cutoff
{
assert(move_is_ok(move));
- bool moveIsCheck = pos.move_is_check(move, dcCandidates);
- bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move);
-
moveCount++;
ss[ply].currentMove = move;
// Futility pruning
if ( UseQSearchFutilityPruning
+ && enoughMaterial
&& !isCheck
- && !moveIsCheck
- && !move_promotion(move)
- && !moveIsPassedPawnPush
&& !pvNode
- && enoughMaterial)
+ && !move_promotion(move)
+ && !pos.move_is_check(move, dcCandidates)
+ && !pos.move_is_passed_pawn_push(move))
{
Value futilityValue = staticValue
+ Max(pos.midgame_value_of_piece_on(move_to(move)),
pos.endgame_value_of_piece_on(move_to(move)))
- + FutilityMargin0
+ + (move_is_ep(move) ? PawnValueEndgame : Value(0))
+ + FutilityMarginQS
+ ei.futilityMargin;
if (futilityValue < alpha)
// Don't search captures and checks with negative SEE values
if ( !isCheck
&& !move_promotion(move)
- && !pvNode
&& (pos.midgame_value_of_piece_on(move_from(move)) >
pos.midgame_value_of_piece_on(move_to(move)))
&& pos.see(move) < 0)
bool moveIsCheck = pos.move_is_check(move, sp->dcCandidates);
bool moveIsCapture = pos.move_is_capture(move);
- bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move);
lock_grab(&(sp->lock));
int moveCount = ++sp->moves;
ss[sp->ply].currentMove = move;
// Decide the new search depth.
- Depth ext = extension(pos, move, false, moveIsCheck, false, false);
+ bool dangerous;
+ Depth ext = extension(pos, move, false, moveIsCheck, false, false, &dangerous);
Depth newDepth = sp->depth - OnePly + ext;
// Prune?
if ( useFutilityPruning
- && ext == Depth(0)
+ && !dangerous
&& !moveIsCapture
- && !moveIsPassedPawnPush
&& !move_promotion(move)
&& moveCount >= 2 + int(sp->depth)
&& ok_to_prune(pos, move, ss[sp->ply].threatMove, sp->depth))
// Try to reduce non-pv search depth by one ply if move seems not problematic,
// if the move fails high will be re-searched at full depth.
- if ( ext == Depth(0)
+ if ( !dangerous
&& moveCount >= LMRNonPVMoves
&& !moveIsCapture
- && !moveIsPassedPawnPush
&& !move_promotion(move)
&& !move_is_castle(move)
&& !move_is_killer(move, ss[sp->ply]))
{
bool moveIsCheck = pos.move_is_check(move, sp->dcCandidates);
bool moveIsCapture = pos.move_is_capture(move);
- bool moveIsPassedPawnPush = pos.move_is_passed_pawn_push(move);
assert(move_is_ok(move));
- ss[sp->ply].currentMoveCaptureValue = move_is_ep(move)?
- PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move));
+ if (moveIsCapture)
+ ss[sp->ply].currentMoveCaptureValue =
+ move_is_ep(move)? PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move));
+ else
+ ss[sp->ply].currentMoveCaptureValue = Value(0);
lock_grab(&(sp->lock));
int moveCount = ++sp->moves;
ss[sp->ply].currentMove = move;
// Decide the new search depth.
- Depth ext = extension(pos, move, true, moveIsCheck, false, false);
+ bool dangerous;
+ Depth ext = extension(pos, move, true, moveIsCheck, false, false, &dangerous);
Depth newDepth = sp->depth - OnePly + ext;
// Make and search the move.
// Try to reduce non-pv search depth by one ply if move seems not problematic,
// if the move fails high will be re-searched at full depth.
- if ( ext == Depth(0)
+ if ( !dangerous
&& moveCount >= LMRPVMoves
&& !moveIsCapture
- && !moveIsPassedPawnPush
&& !move_promotion(move)
&& !move_is_castle(move)
&& !move_is_killer(move, ss[sp->ply]))
}
// If we are at ply 1, and we are searching the first root move at
// ply 0, set the 'Problem' variable if the score has dropped a lot
- // (from the computer's point of view) since the previous iteration:
- if (Iteration >= 2 && -value <= ValueByIteration[Iteration-1] - ProblemMargin)
+ // (from the computer's point of view) since the previous iteration.
+ if ( sp->ply == 1
+ && Iteration >= 2
+ && -value <= ValueByIteration[Iteration-1] - ProblemMargin)
Problem = true;
}
lock_release(&(sp->lock));
lock_grab(&(sp->lock));
// If this is the master thread and we have been asked to stop because of
- // a beta cutoff higher up in the tree, stop all slave threads:
+ // a beta cutoff higher up in the tree, stop all slave threads.
if (sp->master == threadID && thread_should_stop(threadID))
for (int i = 0; i < ActiveThreads; i++)
if (sp->slaves[i])
lock_release(&(sp->lock));
}
+ /// The BetaCounterType class
+
+ BetaCounterType::BetaCounterType() { clear(); }
+
+ void BetaCounterType::clear() {
+
+ for (int i = 0; i < THREAD_MAX; i++)
+ hits[i][WHITE] = hits[i][BLACK] = 0ULL;
+ }
+
+ void BetaCounterType::add(Color us, Depth d, int threadID) {
+
+ // Weighted count based on depth
+ hits[threadID][us] += int(d);
+ }
+
+ void BetaCounterType::read(Color us, int64_t& our, int64_t& their) {
+
+ our = their = 0UL;
+ for (int i = 0; i < THREAD_MAX; i++)
+ {
+ our += hits[i][us];
+ their += hits[i][opposite_color(us)];
+ }
+ }
+
/// The RootMove class
if (score != m.score)
return (score < m.score);
- return nodes <= m.nodes;
+ return theirBeta <= m.theirBeta;
}
/// The RootMoveList class
moves[moveNum].cumulativeNodes += nodes;
}
+ inline void RootMoveList::set_beta_counters(int moveNum, int64_t our, int64_t their) {
+ moves[moveNum].ourBeta = our;
+ moves[moveNum].theirBeta = their;
+ }
+
void RootMoveList::set_move_pv(int moveNum, const Move pv[]) {
int j;
for(j = 0; pv[j] != MOVE_NONE; j++)
// init_search_stack() initializes a search stack at the beginning of a
// new search from the root.
- void init_search_stack(SearchStack ss) {
+ void init_search_stack(SearchStack& ss) {
ss.pv[0] = MOVE_NONE;
ss.pv[1] = MOVE_NONE;
ss.threatMove = MOVE_NONE;
ss.reduction = Depth(0);
for (int j = 0; j < KILLER_MAX; j++)
- ss.killers[j] = MOVE_NONE;
+ ss.killers[j] = MOVE_NONE;
}
void init_search_stack(SearchStack ss[]) {
NodesSincePoll = 0;
}
}
-
ss[ply].pv[ply] = ss[ply].pv[ply+1] = ss[ply].currentMove = MOVE_NONE;
ss[ply+2].mateKiller = MOVE_NONE;
ss[ply].threatMove = MOVE_NONE;
}
+ // value_is_mate() checks if the given value is a mate one
+ // eventually compensated for the ply.
+
+ bool value_is_mate(Value value) {
+
+ assert(abs(value) <= VALUE_INFINITE);
+
+ return value <= value_mated_in(PLY_MAX)
+ || value >= value_mate_in(PLY_MAX);
+ }
+
+
// move_is_killer() checks if the given move is among the
// killer moves of that ply.
bool move_is_killer(Move m, const SearchStack& ss) {
-
+
const Move* k = ss.killers;
for (int i = 0; i < KILLER_MAX; i++, k++)
if (*k == m)
// extension() decides whether a move should be searched with normal depth,
// or with extended depth. Certain classes of moves (checking moves, in
- // particular) are searched with bigger depth than ordinary moves.
+ // particular) are searched with bigger depth than ordinary moves and in
+ // any case are marked as 'dangerous'. Note that also if a move is not
+ // extended, as example because the corresponding UCI option is set to zero,
+ // the move is marked as 'dangerous' so, at least, we avoid to prune it.
- Depth extension(const Position &pos, Move m, bool pvNode,
- bool check, bool singleReply, bool mateThreat) {
+ Depth extension(const Position &pos, Move m, bool pvNode, bool check,
+ bool singleReply, bool mateThreat, bool* dangerous) {
+
+ assert(m != MOVE_NONE);
Depth result = Depth(0);
+ *dangerous = check || singleReply || mateThreat;
if (check)
result += CheckExtension[pvNode];
if (singleReply)
result += SingleReplyExtension[pvNode];
+ if (mateThreat)
+ result += MateThreatExtension[pvNode];
+
if (pos.move_is_pawn_push_to_7th(m))
+ {
result += PawnPushTo7thExtension[pvNode];
-
+ *dangerous = true;
+ }
if (pos.move_is_passed_pawn_push(m))
+ {
result += PassedPawnExtension[pvNode];
+ *dangerous = true;
+ }
- if (mateThreat)
- result += MateThreatExtension[pvNode];
-
- if ( pos.midgame_value_of_piece_on(move_to(m)) >= RookValueMidgame
+ if ( pos.move_is_capture(m)
+ && pos.type_of_piece_on(move_to(m)) != PAWN
&& ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK)
- pos.midgame_value_of_piece_on(move_to(m)) == Value(0))
- && !move_promotion(m))
+ && !move_promotion(m)
+ && !move_is_ep(m))
+ {
result += PawnEndgameExtension[pvNode];
-
+ *dangerous = true;
+ }
+
if ( pvNode
&& pos.move_is_capture(m)
&& pos.type_of_piece_on(move_to(m)) != PAWN
&& pos.see(m) >= 0)
+ {
result += OnePly/2;
+ *dangerous = true;
+ }
return Min(result, OnePly);
}
tto = move_to(threat);
// Case 1: Castling moves are never pruned.
- if(move_is_castle(m))
- return false;
+ if (move_is_castle(m))
+ return false;
// Case 2: Don't prune moves which move the threatened piece
- if(!PruneEscapeMoves && threat != MOVE_NONE && mfrom == tto)
- return false;
+ if (!PruneEscapeMoves && threat != MOVE_NONE && mfrom == tto)
+ return false;
// Case 3: If the threatened piece has value less than or equal to the
// value of the threatening piece, don't prune move which defend it.
- if(!PruneDefendingMoves && threat != MOVE_NONE
- && (piece_value_midgame(pos.piece_on(tfrom))
- >= piece_value_midgame(pos.piece_on(tto)))
- && pos.move_attacks_square(m, tto))
+ if ( !PruneDefendingMoves
+ && threat != MOVE_NONE
+ && pos.move_is_capture(threat)
+ && ( pos.midgame_value_of_piece_on(tfrom) >= pos.midgame_value_of_piece_on(tto)
+ || pos.type_of_piece_on(tfrom) == KING)
+ && pos.move_attacks_square(m, tto))
return false;
// Case 4: Don't prune moves with good history.
- if(!H.ok_to_prune(pos.piece_on(move_from(m)), m, d))
- return false;
+ if (!H.ok_to_prune(pos.piece_on(move_from(m)), m, d))
+ return false;
// Case 5: If the moving piece in the threatened move is a slider, don't
// prune safe moves which block its ray.
- if(!PruneBlockingMoves && threat != MOVE_NONE
- && piece_is_slider(pos.piece_on(tfrom))
- && bit_is_set(squares_between(tfrom, tto), mto) && pos.see(m) >= 0)
- return false;
+ if ( !PruneBlockingMoves
+ && threat != MOVE_NONE
+ && piece_is_slider(pos.piece_on(tfrom))
+ && bit_is_set(squares_between(tfrom, tto), mto)
+ && pos.see(m) >= 0)
+ return false;
return true;
}
return;
for (int i = KILLER_MAX - 1; i > 0; i--)
- ss.killers[i] = ss.killers[i - 1];
-
- ss.killers[0] = m;
+ ss.killers[i] = ss.killers[i - 1];
+
+ ss.killers[0] = m;
}
// fail_high_ply_1() checks if some thread is currently resolving a fail
projects / stockfish / blobdiff