/// Types
+ //The IterationInfoType is used to store search history
+ //iteration by iteration.
+ //
+ //Because we use relatively small (dynamic) aspiration window,
+ //there happens many fail highs and fail lows in root. And
+ //because we don't do researches in those cases, "value" stored
+ //here is not necessarily exact. Instead in case of fail high/low
+ //we guess what the right value might be and store our guess
+ //as "speculated value" and then move on...
+
+ class IterationInfoType {
+ private:
+ Value _value;
+ Value _speculatedValue;
+ bool _failHigh;
+ bool _failLow;
+ public:
+ IterationInfoType() {
+ clear();
+ }
+
+ inline void clear() {
+ set(Value(0));
+ }
+
+ inline void set(Value v) {
+ set(v, v, false, false);
+ }
+
+ inline void set(Value v, Value specV, bool fHigh, bool fLow) {
+ _value = v;
+ _speculatedValue = specV;
+ _failHigh = fHigh;
+ _failLow = fLow;
+ }
+
+ inline Value value() {
+ return _value;
+ }
+
+ inline Value speculated_value() {
+ return _speculatedValue;
+ }
+
+ inline bool fail_high() {
+ return _failHigh;
+ }
+
+ inline bool fail_low() {
+ return _failLow;
+ }
+ };
+
+
// 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
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(0x100), Value(0x200), Value(0x250),
+ Value(0x2A0), Value(0x340), Value(0x3A0) };
// Razoring
+ const bool RazorAtDepthOne = false;
Depth RazorDepth = 4*OnePly;
Value RazorMargin = Value(0x300);
// 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];
+ IterationInfoType IterationInfo[PLY_MAX_PLUS_2];
int BestMoveChangesByIteration[PLY_MAX_PLUS_2];
// MultiPV mode
// Time managment variables
int SearchStartTime;
int MaxNodes, MaxDepth;
- int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime;
- Move BestRootMove, PonderMove, EasyMove;
+ int MaxSearchTime, AbsoluteMaxSearchTime, EmergencyMaxSearchTime, ExtraSearchTime;
+ Move EasyMove;
int RootMoveNumber;
bool InfiniteSearch;
bool PonderSearch;
bool AbortSearch;
bool Quit;
bool FailHigh;
+ bool FailLow;
bool Problem;
bool PonderingEnabled;
int ExactMaxTime;
/// Functions
Value id_loop(const Position &pos, Move searchMoves[]);
- Value root_search(Position &pos, SearchStack ss[], RootMoveList &rml);
+ Value root_search(Position &pos, SearchStack ss[], RootMoveList &rml,
+ Value alpha, Value beta);
Value search_pv(Position &pos, SearchStack ss[], Value alpha, Value beta,
Depth depth, int ply, int threadID);
Value search(Position &pos, SearchStack ss[], Value beta,
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_node(const Position &pos, SearchStack ss[], int ply, int threadID);
+ void init_node(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, bool* dangerous);
+ Depth extension(const Position &pos, Move m, bool pvNode, bool capture, 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);
bool thread_is_available(int slave, int master);
bool idle_thread_exists(int master);
bool split(const Position &pos, SearchStack *ss, int ply,
- Value *alpha, Value *beta, Value *bestValue, Depth depth,
- int *moves, MovePicker *mp, Bitboard dcCandidates, int master,
- bool pvNode);
+ Value *alpha, Value *beta, Value *bestValue, Depth depth, int *moves,
+ MovePicker *mp, Bitboard dcCandidates, int master, bool pvNode);
void wake_sleeping_threads();
#if !defined(_MSC_VER)
SearchStack EmptySearchStack;
+// SearchStack::init() initializes a search stack. Used at the beginning of a
+// new search from the root.
+void SearchStack::init(int ply) {
+
+ pv[ply] = pv[ply + 1] = MOVE_NONE;
+ currentMove = threatMove = MOVE_NONE;
+ reduction = Depth(0);
+}
+
+void SearchStack::initKillers() {
+
+ mateKiller = MOVE_NONE;
+ for (int i = 0; i < KILLER_MAX; i++)
+ killers[i] = MOVE_NONE;
+}
+
+
////
//// Functions
////
// Initialize global search variables
Idle = false;
SearchStartTime = get_system_time();
- BestRootMove = MOVE_NONE;
- PonderMove = MOVE_NONE;
EasyMove = MOVE_NONE;
for (int i = 0; i < THREAD_MAX; i++)
{
AbortSearch = false;
Quit = false;
FailHigh = false;
+ FailLow = false;
Problem = false;
ExactMaxTime = maxTime;
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 Scale Factor (Main Search)");
+ 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"));
// Set thinking time:
int myTime = time[side_to_move];
int myIncrement = increment[side_to_move];
- int oppTime = time[1 - side_to_move];
if (!movesToGo) // Sudden death time control
{
{
MaxSearchTime = myTime / 30 + myIncrement;
AbsoluteMaxSearchTime = Max(myTime / 4, myIncrement - 100);
+ EmergencyMaxSearchTime = Max(myTime / 2, myIncrement - 100);
} else { // Blitz game without increment
MaxSearchTime = myTime / 30;
AbsoluteMaxSearchTime = myTime / 8;
+ EmergencyMaxSearchTime = myTime / 4;
}
}
else // (x moves) / (y minutes)
{
MaxSearchTime = myTime / 2;
AbsoluteMaxSearchTime = Min(myTime / 2, myTime - 500);
+ EmergencyMaxSearchTime = myTime - 500;
} else {
MaxSearchTime = myTime / Min(movesToGo, 20);
AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3);
+ EmergencyMaxSearchTime = Min((8 * myTime) / movesToGo, myTime / 2);
}
}
}
// Init also the empty search stack
- init_search_stack(EmptySearchStack);
+ EmptySearchStack.init(0);
+ EmptySearchStack.initKillers();
}
Position p(pos);
SearchStack ss[PLY_MAX_PLUS_2];
+ Value alpha;
+ Value beta;
+
// searchMoves are verified, copied, scored and sorted
RootMoveList rml(p, searchMoves);
// Initialize
TT.new_search();
H.clear();
- init_search_stack(ss);
-
- ValueByIteration[0] = Value(0);
- ValueByIteration[1] = rml.get_move_score(0);
+ for (int i = 0; i < 3; i++)
+ {
+ ss[i].init(i);
+ ss[i].initKillers();
+ }
+ IterationInfo[1].set(rml.get_move_score(0));
Iteration = 1;
- LastIterations = false;
EasyMove = rml.scan_for_easy_move();
// Iterative deepening loop
- while (!AbortSearch && Iteration < PLY_MAX)
+ while (Iteration < PLY_MAX)
{
// Initialize iteration
rml.sort();
std::cout << "info depth " << Iteration << std::endl;
+ //Calculate dynamic search window based on previous iterations.
+ if (MultiPV == 1 && Iteration >= 6) {
+ Value prevDelta1 = IterationInfo[Iteration - 1].speculated_value() - IterationInfo[Iteration - 2].speculated_value();
+ Value prevDelta2 = IterationInfo[Iteration - 2].speculated_value() - IterationInfo[Iteration - 3].speculated_value();
+
+ Value delta = Max((2 * Abs(prevDelta1) + Abs(prevDelta2)) , ProblemMargin);
+
+ alpha = IterationInfo[Iteration - 1].value() - delta;
+ beta = IterationInfo[Iteration - 1].value() + delta;
+ if (alpha < - VALUE_INFINITE) alpha = - VALUE_INFINITE;
+ if (beta > VALUE_INFINITE) beta = VALUE_INFINITE;
+
+ } else {
+ alpha = - VALUE_INFINITE;
+ beta = VALUE_INFINITE;
+ }
+
// Search to the current depth
- ValueByIteration[Iteration] = root_search(p, ss, rml);
+ Value value = root_search(p, ss, rml, alpha, beta);
+
+ // Write PV to transposition table, in case the relevant entries have
+ // been overwritten during the search:
+ TT.insert_pv(p, ss[0].pv);
+
+ if (AbortSearch)
+ break; //Value cannot be trusted. Break out immediately!
+
+ //Save info about search result
+ Value speculated_value = value;
+ bool fHigh = false;
+ bool fLow = false;
+
+ Value prev_value = IterationInfo[Iteration - 1].value();
+ Value delta = value - prev_value;
+
+ if (value >= beta) {
+ fHigh = true;
+ speculated_value = prev_value + 2 * delta;
+ BestMoveChangesByIteration[Iteration] += 2; //This is used to tell time management to allocate more time
+ } else if (value <= alpha) {
+ fLow = true;
+ speculated_value = prev_value + 2 * delta;
+ BestMoveChangesByIteration[Iteration] += 3; //This is used to tell time management to allocate more time
+ } else {
+ //nothing
+ }
+
+ if (speculated_value < - VALUE_INFINITE) speculated_value = - VALUE_INFINITE;
+ if (speculated_value > VALUE_INFINITE) speculated_value = VALUE_INFINITE;
+
+ IterationInfo[Iteration].set(value, speculated_value, fHigh, fLow);
// Erase the easy move if it differs from the new best move
if (ss[0].pv[0] != EasyMove)
// Stop search early when the last two iterations returned a mate score
if ( Iteration >= 6
- && abs(ValueByIteration[Iteration]) >= abs(VALUE_MATE) - 100
- && abs(ValueByIteration[Iteration-1]) >= abs(VALUE_MATE) - 100)
+ && abs(IterationInfo[Iteration].value()) >= abs(VALUE_MATE) - 100
+ && abs(IterationInfo[Iteration-1].value()) >= abs(VALUE_MATE) - 100)
stopSearch = true;
// Stop search early if one move seems to be much better than the rest
int64_t nodes = nodes_searched();
- if ( Iteration >= 8
+ if ( Iteration >= 8 && !fLow && !fHigh
&& EasyMove == ss[0].pv[0]
&& ( ( rml.get_move_cumulative_nodes(0) > (nodes * 85) / 100
&& current_search_time() > MaxSearchTime / 16)
ExtraSearchTime = BestMoveChangesByIteration[Iteration] * (MaxSearchTime / 2)
+ BestMoveChangesByIteration[Iteration-1] * (MaxSearchTime / 3);
- // Try to guess if the current iteration is the last one or the last two
- LastIterations = (current_search_time() > ((MaxSearchTime + ExtraSearchTime)*58) / 128);
-
// Stop search if most of MaxSearchTime is consumed at the end of the
// iteration. We probably don't have enough time to search the first
// move at the next iteration anyway.
StopOnPonderhit = true;
}
}
- // Write PV to transposition table, in case the relevant entries have
- // been overwritten during the search:
- TT.insert_pv(p, ss[0].pv);
if (MaxDepth && Iteration >= MaxDepth)
break;
}
+ if (FailLow)
+ {
+ //Here we face the rare, but extremely difficult case:
+ //Our aspiration search has failed low and we've run out of time!
+ //So we have no move to play!
+ //Now use the emergency time and try as quickly as possible to
+ //find even one playable move.
+
+ //FIXME: this is only for grepping logs purpose. Remove me when we are sure that this stuff really works!!
+ if (AbortSearch)
+ std::cout << "info depth " << 999 << std::endl;
+ else
+ std::cout << "info depth " << 998 << std::endl;
+
+ //Prepare variables for emergency search
+ AbortSearch = false;
+ FailLow = false;
+ AbsoluteMaxSearchTime = EmergencyMaxSearchTime;
+ MaxSearchTime = EmergencyMaxSearchTime;
+ ExtraSearchTime = 0;
+ rml.sort();
+
+ std::cout << "info depth " << Iteration << std::endl;
+
+ //Cause we failed low, it's _likely_ that we couldn't get over alpha anyway.
+ root_search(p, ss, rml, -VALUE_INFINITE, alpha);
+ }
+
rml.sort();
// If we are pondering, we shouldn't print the best move before we
<< " hashfull " << TT.full() << std::endl;
// Print the best move and the ponder move to the standard output
+ if (ss[0].pv[0] == MOVE_NONE)
+ {
+ ss[0].pv[0] = rml.get_move(0);
+ ss[0].pv[1] = MOVE_NONE;
+ }
std::cout << "bestmove " << ss[0].pv[0];
if (ss[0].pv[1] != MOVE_NONE)
std::cout << " ponder " << ss[0].pv[1];
if (dbg_show_hit_rate)
dbg_print_hit_rate(LogFile);
- UndoInfo u;
+ StateInfo st;
LogFile << "Nodes: " << nodes_searched() << std::endl
<< "Nodes/second: " << nps() << std::endl
<< "Best move: " << move_to_san(p, ss[0].pv[0]) << std::endl;
- p.do_move(ss[0].pv[0], u);
+ p.do_move(ss[0].pv[0], st);
LogFile << "Ponder move: " << move_to_san(p, ss[0].pv[1])
<< std::endl << std::endl;
}
// scheme (perhaps we should try to use this at internal PV nodes, too?)
// and prints some information to the standard output.
- Value root_search(Position &pos, SearchStack ss[], RootMoveList &rml) {
+ Value root_search(Position &pos, SearchStack ss[], RootMoveList &rml, Value alpha, Value beta) {
- Value alpha = -VALUE_INFINITE;
- Value beta = VALUE_INFINITE, value;
+ Value oldAlpha = alpha;
+ Value value;
Bitboard dcCandidates = pos.discovered_check_candidates(pos.side_to_move());
// Loop through all the moves in the root move list
for (int i = 0; i < rml.move_count() && !AbortSearch; i++)
{
+ if (alpha >= beta) {
+ rml.set_move_score(i, -VALUE_INFINITE);
+ //Leave node-counters and beta-counters as they are.
+ continue;
+ }
+
int64_t nodes;
Move move;
- UndoInfo u;
+ StateInfo st;
Depth ext, newDepth;
RootMoveNumber = i + 1;
// Decide search depth for this move
bool dangerous;
- ext = extension(pos, move, true, pos.move_is_check(move), false, false, &dangerous);
+ ext = extension(pos, move, true, pos.move_is_capture(move), pos.move_is_check(move), false, false, &dangerous);
newDepth = (Iteration - 2) * OnePly + ext + InitialDepth;
// Make the move, and search it
- pos.do_move(move, u, dcCandidates);
+ pos.do_move(move, st, dcCandidates);
if (i < MultiPV)
{
- value = -search_pv(pos, ss, -beta, VALUE_INFINITE, newDepth, 1, 0);
+ value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0);
// If the value has dropped a lot compared to the last iteration,
// set the boolean variable Problem to true. This variable is used
// for time managment: When Problem is true, we try to complete the
// current iteration before playing a move.
- Problem = (Iteration >= 2 && value <= ValueByIteration[Iteration-1] - ProblemMargin);
+ Problem = (Iteration >= 2 && value <= IterationInfo[Iteration-1].value() - ProblemMargin);
if (Problem && StopOnPonderhit)
StopOnPonderhit = false;
}
}
- pos.undo_move(move, u);
+ pos.undo_move(move);
// Finished searching the move. If AbortSearch is true, the search
// was aborted because the user interrupted the search or because we
LogFile << pretty_pv(pos, current_search_time(), Iteration, nodes_searched(), value, ss[0].pv)
<< std::endl;
- alpha = value;
+ if (value > alpha)
+ alpha = value;
// Reset the global variable Problem to false if the value isn't too
// far below the final value from the last iteration.
- if (value > ValueByIteration[Iteration - 1] - NoProblemMargin)
+ if (value > IterationInfo[Iteration - 1].value() - NoProblemMargin)
Problem = false;
}
else // MultiPV > 1
alpha = rml.get_move_score(Min(i, MultiPV-1));
}
}
+
+ if (alpha <= oldAlpha)
+ FailLow = true;
+ else
+ FailLow = false;
+
}
return alpha;
}
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
+ 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(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, alpha, beta, Depth(0), ply, threadID);
-
- init_node(pos, ss, ply, threadID);
-
if (pos.is_draw())
return VALUE_DRAW;
int moveCount = 0;
Value value, bestValue = -VALUE_INFINITE;
Bitboard dcCandidates = mp.discovered_check_candidates();
+ Color us = pos.side_to_move();
bool isCheck = pos.is_check();
- bool mateThreat = pos.has_mate_threat(opposite_color(pos.side_to_move()));
+ bool mateThreat = pos.has_mate_threat(opposite_color(us));
// Loop through all legal moves until no moves remain or a beta cutoff
// occurs.
movesSearched[moveCount++] = ss[ply].currentMove = move;
- if (moveIsCapture)
- 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
bool dangerous;
- Depth ext = extension(pos, move, true, moveIsCheck, singleReply, mateThreat, &dangerous);
+ Depth ext = extension(pos, move, true, moveIsCapture, moveIsCheck, singleReply, mateThreat, &dangerous);
Depth newDepth = depth - OnePly + ext;
// Make and search the move
- UndoInfo u;
- pos.do_move(move, u, dcCandidates);
+ StateInfo st;
+ pos.do_move(move, st, dcCandidates);
if (moveCount == 1) // The first move in list is the PV
value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID);
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);
}
}
}
- pos.undo_move(move, u);
+ pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
// 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 <= IterationInfo[Iteration-1].value() - ProblemMargin)
Problem = true;
}
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(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);
Value approximateEval = quick_evaluate(pos);
bool mateThreat = false;
- bool nullDrivenIID = false;
bool isCheck = pos.is_check();
// Null move search
{
ss[ply].currentMove = MOVE_NULL;
- UndoInfo u;
- pos.do_null_move(u);
- int R = (depth >= 4 * OnePly ? 4 : 3); // Null move dynamic reduction
+ StateInfo st;
+ pos.do_null_move(st);
+ int R = (depth >= 5 * 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 there is a good possibility that this is a cut-node.
- // We will do an IID later to find a ttMove.
- 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);
+ pos.undo_null_move();
if (value_is_mate(nullValue))
{
// 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 ( !isCheck
- && !value_is_mate(beta)
- && ( (approximateEval < beta - RazorMargin && depth < RazorDepth)
- ||(approximateEval < beta - PawnValueMidgame && depth <= OnePly)))
+ else if ( !value_is_mate(beta)
+ && approximateEval < beta - RazorMargin
+ && depth < RazorDepth
+ && (RazorAtDepthOne || 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 - RazorMargin / 4)
+ || (depth <= 2*OnePly && v < beta - RazorMargin)
+ || (depth <= OnePly && v < beta - RazorMargin / 2))
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 is a cut-node. So it's a good time to search for a ttMove.
- 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:
// Decide the new search depth
bool dangerous;
- Depth ext = extension(pos, move, false, moveIsCheck, singleReply, mateThreat, &dangerous);
+ Depth ext = extension(pos, move, false, moveIsCapture, moveIsCheck, singleReply, mateThreat, &dangerous);
Depth newDepth = depth - OnePly + ext;
// Futility pruning
&& !moveIsCapture
&& !move_promotion(move))
{
- // History pruning. See ok_to_prune() definition.
+ // History pruning. See ok_to_prune() definition
if ( moveCount >= 2 + int(depth)
&& ok_to_prune(pos, move, ss[ply].threatMove, depth))
continue;
- // Value based pruning.
- 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)
{
}
// Make and search the move
- UndoInfo u;
- pos.do_move(move, u, dcCandidates);
+ StateInfo st;
+ pos.do_move(move, st, dcCandidates);
// 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.
ss[ply].reduction = Depth(0);
value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID);
}
- pos.undo_move(move, u);
+ pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
}
TT.store(pos, value_to_tt(bestValue, ply), depth, m, VALUE_TYPE_LOWER);
}
+
+ assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
+
return bestValue;
}
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(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;
- // Transposition table lookup
- const TTEntry* tte = TT.retrieve(pos);
- if (tte && ok_to_use_TT(tte, depth, beta, ply))
- return value_from_tt(tte->value(), ply);
+ // Transposition table lookup, only when not in PV
+ TTEntry* tte = NULL;
+ bool pvNode = (beta - alpha != 1);
+ if (!pvNode)
+ {
+ tte = TT.retrieve(pos);
+ if (tte && ok_to_use_TT(tte, depth, beta, ply))
+ {
+ assert(tte->type() != VALUE_TYPE_EVAL);
+
+ return value_from_tt(tte->value(), ply);
+ }
+ }
// Evaluate the position statically
+ EvalInfo ei;
+ Value staticValue;
bool isCheck = pos.is_check();
- Value staticValue = (isCheck ? -VALUE_INFINITE : evaluate(pos, ei, threadID));
+ ei.futilityMargin = Value(0); // Manually initialize futilityMargin
+
+ if (isCheck)
+ staticValue = -VALUE_INFINITE;
+
+ else if (tte && tte->type() == VALUE_TYPE_EVAL)
+ {
+ // Use the cached evaluation score if possible
+ assert(tte->value() == evaluate(pos, ei, threadID));
+ assert(ei.futilityMargin == Value(0));
+
+ staticValue = tte->value();
+ }
+ else
+ staticValue = evaluate(pos, ei, threadID);
if (ply == PLY_MAX - 1)
return evaluate(pos, ei, threadID);
Value bestValue = staticValue;
if (bestValue >= beta)
+ {
+ // Store the score to avoid a future costly evaluation() call
+ if (!isCheck && !tte && ei.futilityMargin == 0)
+ TT.store(pos, value_to_tt(bestValue, ply), Depth(-127*OnePly), MOVE_NONE, VALUE_TYPE_EVAL);
+
return bestValue;
+ }
if (bestValue > alpha)
alpha = 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.
- bool pvNode = (beta - alpha != 1);
- MovePicker mp = MovePicker(pos, pvNode, MOVE_NONE, EmptySearchStack, depth, isCheck ? NULL : &ei);
+ MovePicker mp = MovePicker(pos, pvNode, MOVE_NONE, EmptySearchStack, depth);
Move move;
int moveCount = 0;
Bitboard dcCandidates = mp.discovered_check_candidates();
- bool enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame;
+ Color us = pos.side_to_move();
+ bool enoughMaterial = pos.non_pawn_material(us) > RookValueMidgame;
// Loop through the moves until no moves remain or a beta cutoff
// occurs.
+ Max(pos.midgame_value_of_piece_on(move_to(move)),
pos.endgame_value_of_piece_on(move_to(move)))
+ (move_is_ep(move) ? PawnValueEndgame : Value(0))
- + FutilityMargin0
+ + FutilityMarginQS
+ ei.futilityMargin;
if (futilityValue < alpha)
continue;
// Make and search the move.
- UndoInfo u;
- pos.do_move(move, u, dcCandidates);
+ StateInfo st;
+ pos.do_move(move, st, dcCandidates);
Value value = -qsearch(pos, ss, -beta, -alpha, depth-OnePly, ply+1, threadID);
- pos.undo_move(move, u);
+ pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
// Update transposition table
- TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE, VALUE_TYPE_EXACT);
+ if (!pvNode)
+ {
+ Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1));
+ if (bestValue < beta)
+ TT.store(pos, value_to_tt(bestValue, ply), d, MOVE_NONE, VALUE_TYPE_UPPER);
+ else
+ TT.store(pos, value_to_tt(bestValue, ply), d, MOVE_NONE, VALUE_TYPE_LOWER);
+ }
// Update killers only for good check moves
Move m = ss[ply].currentMove;
// Decide the new search depth.
bool dangerous;
- Depth ext = extension(pos, move, false, moveIsCheck, false, false, &dangerous);
+ Depth ext = extension(pos, move, false, moveIsCapture, moveIsCheck, false, false, &dangerous);
Depth newDepth = sp->depth - OnePly + ext;
// Prune?
continue;
// Make and search the move.
- UndoInfo u;
- pos.do_move(move, u, sp->dcCandidates);
+ StateInfo st;
+ pos.do_move(move, st, sp->dcCandidates);
// 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.
ss[sp->ply].reduction = Depth(0);
value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, true, threadID);
}
- pos.undo_move(move, u);
+ pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
assert(move_is_ok(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;
lock_release(&(sp->lock));
// Decide the new search depth.
bool dangerous;
- Depth ext = extension(pos, move, true, moveIsCheck, false, false, &dangerous);
+ Depth ext = extension(pos, move, true, moveIsCapture, moveIsCheck, false, false, &dangerous);
Depth newDepth = sp->depth - OnePly + ext;
// Make and search the move.
- UndoInfo u;
- pos.do_move(move, u, sp->dcCandidates);
+ StateInfo st;
+ pos.do_move(move, st, sp->dcCandidates);
// 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.
Threads[threadID].failHighPly1 = false;
}
}
- pos.undo_move(move, u);
+ pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
}
// 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 <= IterationInfo[Iteration-1].value() - 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])
if (includeMove)
{
// Find a quick score for the move
- UndoInfo u;
+ StateInfo st;
SearchStack ss[PLY_MAX_PLUS_2];
moves[count].move = mlist[i].move;
moves[count].nodes = 0ULL;
- pos.do_move(moves[count].move, u);
+ pos.do_move(moves[count].move, st);
moves[count].score = -qsearch(pos, ss, -VALUE_INFINITE, VALUE_INFINITE,
Depth(0), 1, 0);
- pos.undo_move(moves[count].move, u);
+ pos.undo_move(moves[count].move);
moves[count].pv[0] = moves[i].move;
moves[count].pv[1] = MOVE_NONE; // FIXME
count++;
}
- // init_search_stack() initializes a search stack at the beginning of a
- // new search from the root.
- void init_search_stack(SearchStack& ss) {
-
- ss.pv[0] = MOVE_NONE;
- ss.pv[1] = MOVE_NONE;
- ss.currentMove = MOVE_NONE;
- ss.threatMove = MOVE_NONE;
- ss.reduction = Depth(0);
- for (int j = 0; j < KILLER_MAX; j++)
- ss.killers[j] = MOVE_NONE;
- }
-
- void init_search_stack(SearchStack ss[]) {
-
- for (int i = 0; i < 3; i++)
- {
- ss[i].pv[i] = MOVE_NONE;
- ss[i].pv[i+1] = MOVE_NONE;
- ss[i].currentMove = MOVE_NONE;
- ss[i].threatMove = MOVE_NONE;
- ss[i].reduction = Depth(0);
- for (int j = 0; j < KILLER_MAX; j++)
- ss[i].killers[j] = MOVE_NONE;
- }
- }
-
-
// init_node() is called at the beginning of all the search functions
// (search(), search_pv(), qsearch(), and so on) and initializes the search
// stack object corresponding to the current node. Once every
// NodesBetweenPolls nodes, init_node() also calls poll(), which polls
// for user input and checks whether it is time to stop the search.
- void init_node(const Position &pos, SearchStack ss[], int ply, int threadID) {
+ void init_node(SearchStack ss[], int ply, int threadID) {
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
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;
- ss[ply].reduction = Depth(0);
- ss[ply].currentMoveCaptureValue = Value(0);
- for (int j = 0; j < KILLER_MAX; j++)
- ss[ply+2].killers[j] = MOVE_NONE;
+
+ ss[ply].init(ply);
+ ss[ply+2].initKillers();
if(Threads[threadID].printCurrentLine)
print_current_line(ss, ply, threadID);
// Case 4: The destination square for m2 is attacked by the moving piece
// in m1:
- if(pos.piece_attacks_square(t1, t2))
+ if(pos.piece_attacks_square(pos.piece_on(t1), t1, t2))
return true;
// Case 5: Discovered check, checking piece is the piece moved in m1:
// 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,
+ Depth extension(const Position& pos, Move m, bool pvNode, bool capture, bool check,
bool singleReply, bool mateThreat, bool* dangerous) {
assert(m != MOVE_NONE);
if (mateThreat)
result += MateThreatExtension[pvNode];
- if (pos.move_is_pawn_push_to_7th(m))
+ if (pos.type_of_piece_on(move_from(m)) == PAWN)
{
- result += PawnPushTo7thExtension[pvNode];
- *dangerous = true;
- }
- if (pos.move_is_passed_pawn_push(m))
- {
- result += PassedPawnExtension[pvNode];
- *dangerous = true;
+ 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 ( pos.move_is_capture(m)
+ if ( capture
&& 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))
}
if ( pvNode
- && pos.move_is_capture(m)
+ && capture
&& pos.type_of_piece_on(move_to(m)) != PAWN
&& pos.see(m) >= 0)
{
if ( !PruneBlockingMoves
&& threat != MOVE_NONE
&& piece_is_slider(pos.piece_on(tfrom))
- && bit_is_set(squares_between(tfrom, tto), mto) && pos.see(m) >= 0)
+ && bit_is_set(squares_between(tfrom, tto), mto)
+ && pos.see(m) >= 0)
return false;
return true;
return;
bool overTime = t > AbsoluteMaxSearchTime
- || (RootMoveNumber == 1 && t > MaxSearchTime + ExtraSearchTime)
- || ( !FailHigh && !fail_high_ply_1() && !Problem
+ || (RootMoveNumber == 1 && t > MaxSearchTime + ExtraSearchTime && !FailLow) //FIXME: BUG??
+ || ( !FailHigh && !FailLow && !fail_high_ply_1() && !Problem
&& t > 6*(MaxSearchTime + ExtraSearchTime));
- if ( (Iteration >= 2 && (!InfiniteSearch && overTime))
+ if ( (Iteration >= 3 && (!InfiniteSearch && overTime))
|| (ExactMaxTime && t >= ExactMaxTime)
|| (Iteration >= 3 && MaxNodes && nodes_searched() >= MaxNodes))
AbortSearch = true;
void ponderhit() {
int t = current_search_time();
PonderSearch = false;
- if(Iteration >= 2 &&
+ if(Iteration >= 3 &&
(!InfiniteSearch && (StopOnPonderhit ||
t > AbsoluteMaxSearchTime ||
(RootMoveNumber == 1 &&
- t > MaxSearchTime + ExtraSearchTime) ||
- (!FailHigh && !fail_high_ply_1() && !Problem &&
+ t > MaxSearchTime + ExtraSearchTime && !FailLow) ||
+ (!FailHigh && !FailLow && !fail_high_ply_1() && !Problem &&
t > 6*(MaxSearchTime + ExtraSearchTime)))))
AbortSearch = true;
}
// splitPoint->cpus becomes 0), split() returns true.
bool split(const Position &p, SearchStack *sstck, int ply,
- Value *alpha, Value *beta, Value *bestValue,
- Depth depth, int *moves,
+ Value *alpha, Value *beta, Value *bestValue, Depth depth, int *moves,
MovePicker *mp, Bitboard dcCandidates, int master, bool pvNode) {
+
assert(p.is_ok());
assert(sstck != NULL);
assert(ply >= 0 && ply < PLY_MAX);
projects / stockfish / blobdiff