#include <iostream>
#include <sstream>
-#include "bitcount.h"
#include "book.h"
#include "evaluate.h"
#include "history.h"
/// Variables initialized by UCI options
- // Adjustable playing strength
- int Slowdown = 0;
- const int SlowdownArray[32] = {
- 19, 41, 70, 110, 160, 230, 320, 430, 570, 756, 1000, 1300, 1690, 2197,
- 2834, 3600, 4573, 5809, 7700, 9863, 12633, 16181, 20726, 26584, 34005,
- 43557, 55792, 71463, 91536, 117247, 150180, 192363
- };
- int Strength;
- const int MaxStrength = 25;
-
// Minimum number of full depth (i.e. non-reduced) moves at PV and non-PV nodes
int LMRPVMoves, LMRNonPVMoves; // heavy SMP read access for the latter
Value qsearch(Position& pos, SearchStack ss[], Value alpha, 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_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 capture, bool check, bool singleReply, bool mateThreat, bool* dangerous);
+ Depth extension(const Position& pos, Move m, Depth depth, 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 ok_to_history(const Position& pos, Move m);
void update_history(const Position& pos, Move m, Depth depth, Move movesSearched[], int moveCount);
void update_killers(Move m, SearchStack& ss);
- void slowdown(const Position& pos);
bool fail_high_ply_1();
int current_search_time();
void ponderhit();
void print_current_line(SearchStack ss[], int ply, int threadID);
void wait_for_stop_or_ponderhit();
+ void init_ss_array(SearchStack ss[]);
void idle_loop(int threadID, SplitPoint* waitSp);
void init_split_point_stack();
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,
+ Value *alpha, Value *beta, Value *bestValue,
+ const Value futilityValue, const Value approximateValue,
+ Depth depth, int *moves,
MovePicker *mp, Bitboard dcCandidates, int master, bool pvNode);
void wake_sleeping_threads();
//// Functions
////
+
+/// perft() is our utility to verify move generation is bug free. All the
+/// legal moves up to given depth are generated and counted and the sum returned.
+
+int perft(Position& pos, Depth depth)
+{
+ Move move;
+ MovePicker mp = MovePicker(pos, MOVE_NONE, depth, H);
+ Bitboard dcCandidates = pos.discovered_check_candidates(pos.side_to_move());
+ int sum = 0;
+
+ // If we are at the last ply we don't need to do and undo
+ // the moves, just to count them.
+ if (depth <= OnePly) // Replace with '<' to test also qsearch
+ {
+ while ((move = mp.get_next_move()) != MOVE_NONE) sum++;
+ return sum;
+ }
+
+ // Loop through all legal moves
+ while ((move = mp.get_next_move()) != MOVE_NONE)
+ {
+ StateInfo st;
+ pos.do_move(move, st, dcCandidates);
+ sum += perft(pos, depth - OnePly);
+ pos.undo_move(move);
+ }
+ return sum;
+}
+
+
/// think() is the external interface to Stockfish's search, and is called when
/// the program receives the UCI 'go' command. It initializes various
/// search-related global variables, and calls root_search(). It returns false
read_weights(pos.side_to_move());
- // Set the number of active threads. If UCI_LimitStrength is enabled, never
- // use more than one thread.
- int newActiveThreads =
- get_option_value_bool("UCI_LimitStrength")? 1 : get_option_value_int("Threads");
+ // Set the number of active threads
+ int newActiveThreads = get_option_value_int("Threads");
if (newActiveThreads != ActiveThreads)
{
ActiveThreads = newActiveThreads;
for (int i = 1; i < ActiveThreads; i++)
assert(thread_is_available(i, 0));
- // Set playing strength
- if (get_option_value_bool("UCI_LimitStrength"))
- {
- Strength = (get_option_value_int("UCI_Elo") - 2100) / 25;
- Slowdown =
- (Strength == MaxStrength)? 0 : SlowdownArray[Max(0, 31-Strength)];
- }
- else
- {
- Strength = MaxStrength;
- Slowdown = 0;
- }
-
// Set thinking time
int myTime = time[side_to_move];
int myIncrement = increment[side_to_move];
if (movesToGo == 1)
{
MaxSearchTime = myTime / 2;
- AbsoluteMaxSearchTime = Min(myTime / 2, myTime - 500);
+ AbsoluteMaxSearchTime =
+ (myTime > 3000)? (myTime - 500) : ((myTime * 3) / 4);
} else {
MaxSearchTime = myTime / Min(movesToGo, 20);
AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3);
NodesBetweenPolls = Min(MaxNodes, 30000);
InfiniteSearch = true; // HACK
}
- else if (Slowdown) {
- if (Slowdown > 50000) NodesBetweenPolls = 30;
- else if (Slowdown > 10000) NodesBetweenPolls = 100;
- else if (Slowdown > 1000) NodesBetweenPolls = 500;
- else if (Slowdown > 100) NodesBetweenPolls = 3000;
- else NodesBetweenPolls = 15000;
- }
+ else if (myTime && myTime < 1000)
+ NodesBetweenPolls = 1000;
+ else if (myTime && myTime < 5000)
+ NodesBetweenPolls = 5000;
else
NodesBetweenPolls = 30000;
{
Value v = id_loop(pos, searchMoves);
loseOnTime = ( UseLSNFiltering
- && myTime < LSNTime
- && myIncrement == 0
- && v < -LSNValue);
+ && myTime < LSNTime
+ && myIncrement == 0
+ && v < -LSNValue);
}
else
{
// searchMoves are verified, copied, scored and sorted
RootMoveList rml(p, searchMoves);
+ // Print RootMoveList c'tor startup scoring to the standard output,
+ // so that we print information also for iteration 1.
+ std::cout << "info depth " << 1 << "\ninfo depth " << 1
+ << " score " << value_to_string(rml.get_move_score(0))
+ << " time " << current_search_time()
+ << " nodes " << nodes_searched()
+ << " nps " << nps()
+ << " pv " << rml.get_move(0) << "\n";
+
// Initialize
TT.new_search();
H.clear();
- for (int i = 0; i < 3; i++)
- {
- ss[i].init(i);
- ss[i].initKillers();
- }
+ init_ss_array(ss);
IterationInfo[1] = IterationInfoType(rml.get_move_score(0), rml.get_move_score(0));
Iteration = 1;
<< " currmovenumber " << i + 1 << std::endl;
// Decide search depth for this move
- bool moveIsCapture = pos.move_is_capture(move);
+ bool captureOrPromotion = pos.move_is_capture_or_promotion(move);
bool dangerous;
- ext = extension(pos, move, true, moveIsCapture, pos.move_is_check(move), false, false, &dangerous);
+ ext = extension(pos, move, Depth(100), true, captureOrPromotion, pos.move_is_check(move), false, false, &dangerous);
newDepth = (Iteration - 2) * OnePly + ext + InitialDepth;
// Make the move, and search it
else
{
if ( newDepth >= 3*OnePly
- && i >= MultiPV + LMRPVMoves - 2 // Remove -2 and decrease LMRPVMoves instead ?
+ && i >= MultiPV + LMRPVMoves
&& !dangerous
- && !moveIsCapture
- && !move_is_promotion(move)
+ && !captureOrPromotion
&& !move_is_castle(move))
{
ss[0].reduction = OnePly;
// Update PV
rml.set_move_score(i, value);
update_pv(ss, 0);
- TT.extract_pv(pos, ss[0].pv);
+ TT.extract_pv(pos, ss[0].pv, PLY_MAX);
rml.set_move_pv(i, ss[0].pv);
if (MultiPV == 1)
std::cout << std::endl;
if (UseLogFile)
- LogFile << pretty_pv(pos, current_search_time(), Iteration, nodes_searched(), value, ss[0].pv)
+ LogFile << pretty_pv(pos, current_search_time(), Iteration, nodes_searched(), value,
+ ((value >= beta)? VALUE_TYPE_LOWER
+ : ((value <= alpha)? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT)),
+ ss[0].pv)
<< std::endl;
if (value > alpha)
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
+ Move movesSearched[256];
+ EvalInfo ei;
+ StateInfo st;
+ Bitboard dcCandidates;
+ const TTEntry* tte;
+ Move ttMove, move;
+ Depth ext, newDepth;
+ Value oldAlpha, value;
+ bool isCheck, mateThreat, singleReply, moveIsCheck, captureOrPromotion, dangerous;
+ int moveCount = 0;
+ Value bestValue = -VALUE_INFINITE;
+
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);
+ init_node(ss, ply, threadID);
// After init_node() that calls poll()
if (AbortSearch || thread_should_stop(threadID))
if (pos.is_draw())
return VALUE_DRAW;
- EvalInfo ei;
-
if (ply >= PLY_MAX - 1)
- return evaluate(pos, ei, threadID);
+ return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
// Mate distance pruning
- Value oldAlpha = alpha;
+ oldAlpha = alpha;
alpha = Max(value_mated_in(ply), alpha);
beta = Min(value_mate_in(ply+1), beta);
if (alpha >= beta)
// Transposition table lookup. At PV nodes, we don't use the TT for
// pruning, but only for move ordering.
- const TTEntry* tte = TT.retrieve(pos.get_key());
- Move ttMove = (tte ? tte->move() : MOVE_NONE);
-
- // Go with internal iterative deepening if we don't have a TT move
- if (UseIIDAtPVNodes && ttMove == MOVE_NONE && depth >= 5*OnePly)
+ tte = TT.retrieve(pos.get_key());
+ ttMove = (tte ? tte->move() : MOVE_NONE);
+
+ // Go with internal iterative deepening if we don't have a TT move or
+ // if search depth is more then 4*OnePly higher then TT move depth.
+ if ( UseIIDAtPVNodes
+ && depth >= 5*OnePly
+ &&(!ttMove || depth > tte->depth() + 4*OnePly))
{
search_pv(pos, ss, alpha, beta, depth-2*OnePly, ply, threadID);
ttMove = ss[ply].pv[ply];
// Initialize a MovePicker object for the current position, and prepare
// to search all moves
+ isCheck = pos.is_check();
+ mateThreat = pos.has_mate_threat(opposite_color(pos.side_to_move()));
+ dcCandidates = pos.discovered_check_candidates(pos.side_to_move());
MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]);
- Move move, movesSearched[256];
- 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(us));
-
// Loop through all legal moves until no moves remain or a beta cutoff
// occurs.
while ( alpha < beta
{
assert(move_is_ok(move));
- bool singleReply = (isCheck && mp.number_of_moves() == 1);
- bool moveIsCheck = pos.move_is_check(move, dcCandidates);
- bool moveIsCapture = pos.move_is_capture(move);
+ singleReply = (isCheck && mp.number_of_evasions() == 1);
+ moveIsCheck = pos.move_is_check(move, dcCandidates);
+ captureOrPromotion = pos.move_is_capture_or_promotion(move);
movesSearched[moveCount++] = ss[ply].currentMove = move;
// Decide the new search depth
- bool dangerous;
- Depth ext = extension(pos, move, true, moveIsCapture, moveIsCheck, singleReply, mateThreat, &dangerous);
- Depth newDepth = depth - OnePly + ext;
+ ext = extension(pos, move, depth, true, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous);
+ newDepth = depth - OnePly + ext;
// Make and search the move
- StateInfo st;
pos.do_move(move, st, dcCandidates);
if (moveCount == 1) // The first move in list is the PV
if ( depth >= 3*OnePly
&& moveCount >= LMRPVMoves
&& !dangerous
- && !moveIsCapture
- && !move_is_promotion(move)
+ && !captureOrPromotion
&& !move_is_castle(move)
&& !move_is_killer(move, ss[ply]))
{
&& idle_thread_exists(threadID)
&& !AbortSearch
&& !thread_should_stop(threadID)
- && split(pos, ss, ply, &alpha, &beta, &bestValue, depth,
+ && split(pos, ss, ply, &alpha, &beta, &bestValue, VALUE_NONE, VALUE_NONE, depth,
&moveCount, &mp, dcCandidates, threadID, true))
break;
}
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
+ move = ss[ply].pv[ply];
+ if (!pos.move_is_capture_or_promotion(move))
{
- update_history(pos, m, depth, movesSearched, moveCount);
- update_killers(m, ss[ply]);
+ update_history(pos, move, depth, movesSearched, moveCount);
+ update_killers(move, ss[ply]);
}
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, m);
+ TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move);
}
else
TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, depth, ss[ply].pv[ply]);
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
+ Move movesSearched[256];
+ EvalInfo ei;
+ StateInfo st;
+ Bitboard dcCandidates;
+ const TTEntry* tte;
+ Move ttMove, move;
+ Depth ext, newDepth;
+ Value approximateEval, nullValue, value, futilityValue;
+ bool isCheck, useFutilityPruning, singleReply, moveIsCheck, captureOrPromotion, dangerous;
+ bool mateThreat = false;
+ int moveCount = 0;
+ Value bestValue = -VALUE_INFINITE;
+
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);
+ init_node(ss, ply, threadID);
// After init_node() that calls poll()
if (AbortSearch || thread_should_stop(threadID))
if (pos.is_draw())
return VALUE_DRAW;
- EvalInfo ei;
-
if (ply >= PLY_MAX - 1)
- return evaluate(pos, ei, threadID);
+ return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
// Mate distance pruning
if (value_mated_in(ply) >= beta)
return beta - 1;
// Transposition table lookup
- const TTEntry* tte = TT.retrieve(pos.get_key());
- Move ttMove = (tte ? tte->move() : MOVE_NONE);
+ tte = TT.retrieve(pos.get_key());
+ ttMove = (tte ? tte->move() : MOVE_NONE);
if (tte && ok_to_use_TT(tte, depth, beta, ply))
{
return value_from_tt(tte->value(), ply);
}
- Value approximateEval = quick_evaluate(pos);
- bool mateThreat = false;
- bool isCheck = pos.is_check();
+ approximateEval = quick_evaluate(pos);
+ isCheck = pos.is_check();
+
+ // Null move search
+ if ( allowNullmove
+ && depth > OnePly
+ && !isCheck
+ && !value_is_mate(beta)
+ && ok_to_do_nullmove(pos)
+ && approximateEval >= beta - NullMoveMargin)
+ {
+ ss[ply].currentMove = MOVE_NULL;
+
+ pos.do_null_move(st);
+ int R = (depth >= 5 * OnePly ? 4 : 3); // Null move dynamic reduction
- bool useNullMove = ( allowNullmove
- //&& depth > OnePly
- && !isCheck
- && !value_is_mate(beta)
- && ok_to_do_nullmove(pos)
- && approximateEval >= beta - NullMoveMargin);
+ nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
+ pos.undo_null_move();
+
+ if (nullValue >= beta)
+ {
+ if (depth < 6 * OnePly)
+ return beta;
+
+ // Do zugzwang verification search
+ Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID);
+ if (v >= 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
+ // the move that refuted the null move was somehow connected to the
+ // 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;
+
+ ss[ply].threatMove = ss[ply + 1].currentMove;
+ if ( depth < ThreatDepth
+ && ss[ply - 1].reduction
+ && connected_moves(pos, ss[ply - 1].currentMove, ss[ply].threatMove))
+ return beta - 1;
+ }
+ }
// Null move search not allowed, try razoring
- if ( !useNullMove
- && !value_is_mate(beta)
- && depth < RazorDepth
- && approximateEval < beta - RazorApprMargins[int(depth) - 2]
- && ss[ply - 1].currentMove != MOVE_NULL
- && ttMove == MOVE_NONE
- && !pos.has_pawn_on_7th(pos.side_to_move()))
+ else if ( !value_is_mate(beta)
+ && depth < RazorDepth
+ && approximateEval < beta - RazorApprMargins[int(depth) - 2]
+ && ss[ply - 1].currentMove != MOVE_NULL
+ && 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 - RazorMargins[int(depth) - 2])
// Initialize a MovePicker object for the current position, and prepare
// to search all moves.
- MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply], useNullMove);
+ MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]);
+ dcCandidates = pos.discovered_check_candidates(pos.side_to_move());
+ futilityValue = VALUE_NONE;
+ useFutilityPruning = depth < SelectiveDepth && !isCheck;
- Move move, movesSearched[256];
- int moveCount = 0;
- Value value, bestValue = -VALUE_INFINITE;
- Bitboard dcCandidates = mp.discovered_check_candidates();
- Value futilityValue = VALUE_NONE;
- bool useFutilityPruning = depth < SelectiveDepth
- && !isCheck;
+ // Avoid calling evaluate() if we already have the score in TT
+ if (tte && (tte->type() & VALUE_TYPE_EVAL))
+ futilityValue = value_from_tt(tte->value(), ply) + FutilityMargins[int(depth) - 2];
// Loop through all legal moves until no moves remain or a beta cutoff
// occurs.
&& (move = mp.get_next_move()) != MOVE_NONE
&& !thread_should_stop(threadID))
{
-
- // Null move search
- if (move == MOVE_NULL)
- {
- ss[ply].currentMove = MOVE_NULL;
-
- 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);
-
- pos.undo_null_move();
-
- if (nullValue >= beta)
- {
- if (depth < 6 * OnePly)
- return beta;
-
- // Do zugzwang verification search
- Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID);
- if (v >= 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
- // the move that refuted the null move was somehow connected to the
- // 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;
-
- ss[ply].threatMove = ss[ply + 1].currentMove;
- if ( depth < ThreatDepth
- && ss[ply - 1].reduction
- && connected_moves(pos, ss[ply - 1].currentMove, ss[ply].threatMove))
- return beta - 1;
- }
- continue;
- }
-
assert(move_is_ok(move));
- bool singleReply = (isCheck && mp.number_of_moves() == 1);
- bool moveIsCheck = pos.move_is_check(move, dcCandidates);
- bool moveIsCapture = pos.move_is_capture(move);
+ singleReply = (isCheck && mp.number_of_evasions() == 1);
+ moveIsCheck = pos.move_is_check(move, dcCandidates);
+ captureOrPromotion = pos.move_is_capture_or_promotion(move);
movesSearched[moveCount++] = ss[ply].currentMove = move;
// Decide the new search depth
- bool dangerous;
- Depth ext = extension(pos, move, false, moveIsCapture, moveIsCheck, singleReply, mateThreat, &dangerous);
- Depth newDepth = depth - OnePly + ext;
+ ext = extension(pos, move, depth, false, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous);
+ newDepth = depth - OnePly + ext;
// Futility pruning
if ( useFutilityPruning
&& !dangerous
- && !moveIsCapture
- && !move_is_promotion(move))
+ && !captureOrPromotion)
{
// History pruning. See ok_to_prune() definition
if ( moveCount >= 2 + int(depth)
- && ok_to_prune(pos, move, ss[ply].threatMove, depth))
+ && ok_to_prune(pos, move, ss[ply].threatMove, depth)
+ && bestValue > value_mated_in(PLY_MAX))
continue;
// Value based pruning
}
// Make and search the move
- StateInfo st;
pos.do_move(move, st, dcCandidates);
// Try to reduce non-pv search depth by one ply if move seems not problematic,
if ( depth >= 3*OnePly
&& moveCount >= LMRNonPVMoves
&& !dangerous
- && !moveIsCapture
- && !move_is_promotion(move)
+ && !captureOrPromotion
&& !move_is_castle(move)
&& !move_is_killer(move, ss[ply]))
{
&& idle_thread_exists(threadID)
&& !AbortSearch
&& !thread_should_stop(threadID)
- && split(pos, ss, ply, &beta, &beta, &bestValue, depth, &moveCount,
+ && split(pos, ss, ply, &beta, &beta, &bestValue, futilityValue, approximateEval, depth, &moveCount,
&mp, dcCandidates, threadID, false))
break;
}
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
+ move = ss[ply].pv[ply];
+ if (!pos.move_is_capture_or_promotion(move))
{
- update_history(pos, m, depth, movesSearched, moveCount);
- update_killers(m, ss[ply]);
+ update_history(pos, move, depth, movesSearched, moveCount);
+ update_killers(move, ss[ply]);
}
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, m);
+ TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move);
}
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
+ EvalInfo ei;
+ StateInfo st;
+ Bitboard dcCandidates;
+ Move ttMove, move;
+ Value staticValue, bestValue, value, futilityValue;
+ bool isCheck, enoughMaterial;
+ const TTEntry* tte = NULL;
+ int moveCount = 0;
+ bool pvNode = (beta - alpha != 1);
+
// 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);
+ init_node(ss, ply, threadID);
// After init_node() that calls poll()
if (AbortSearch || thread_should_stop(threadID))
return VALUE_DRAW;
// Transposition table lookup, only when not in PV
- TTEntry* tte = NULL;
- bool pvNode = (beta - alpha != 1);
if (!pvNode)
{
tte = TT.retrieve(pos.get_key());
return value_from_tt(tte->value(), ply);
}
}
- Move ttMove = (tte ? tte->move() : MOVE_NONE);
+ ttMove = (tte ? tte->move() : MOVE_NONE);
// Evaluate the position statically
- EvalInfo ei;
- Value staticValue;
- bool isCheck = pos.is_check();
+ isCheck = pos.is_check();
ei.futilityMargin = Value(0); // Manually initialize futilityMargin
if (isCheck)
staticValue = -VALUE_INFINITE;
- else if (tte && tte->type() == VALUE_TYPE_EVAL)
+ else if (tte && (tte->type() & VALUE_TYPE_EVAL))
{
// Use the cached evaluation score if possible
assert(ei.futilityMargin == Value(0));
else
staticValue = evaluate(pos, ei, threadID);
- if (ply == PLY_MAX - 1)
- return evaluate(pos, ei, threadID);
+ if (ply >= PLY_MAX - 1)
+ return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
// Initialize "stand pat score", and return it immediately if it is
// at least beta.
- Value bestValue = staticValue;
+ bestValue = staticValue;
if (bestValue >= beta)
{
// Store the score to avoid a future costly evaluation() call
if (!isCheck && !tte && ei.futilityMargin == 0)
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EVAL, Depth(-127*OnePly), MOVE_NONE);
+ TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EV_LO, Depth(-127*OnePly), MOVE_NONE);
return bestValue;
}
// 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, ttMove, depth, H);
- Move move;
- int moveCount = 0;
- Bitboard dcCandidates = mp.discovered_check_candidates();
- Color us = pos.side_to_move();
- bool enoughMaterial = pos.non_pawn_material(us) > RookValueMidgame;
+ dcCandidates = pos.discovered_check_candidates(pos.side_to_move());
+ enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame;
// Loop through the moves until no moves remain or a beta cutoff
// occurs.
&& !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)))
- + (move_is_ep(move) ? PawnValueEndgame : Value(0))
- + FutilityMarginQS
- + ei.futilityMargin;
+ futilityValue = staticValue
+ + 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))
+ + FutilityMarginQS
+ + ei.futilityMargin;
if (futilityValue < alpha)
{
// Don't search captures and checks with negative SEE values
if ( !isCheck
+ && move != ttMove
&& !move_is_promotion(move)
&& pos.see_sign(move) < 0)
continue;
- // Make and search the move.
- StateInfo st;
+ // Make and search the move
pos.do_move(move, st, dcCandidates);
- Value value = -qsearch(pos, ss, -beta, -alpha, depth-OnePly, ply+1, threadID);
+ value = -qsearch(pos, ss, -beta, -alpha, depth-OnePly, ply+1, threadID);
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 (pos.is_check() && moveCount == 0) // Mate!
+ if (!moveCount && pos.is_check()) // Mate!
return value_mated_in(ply);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
// Update transposition table
- Move m = ss[ply].pv[ply];
+ move = ss[ply].pv[ply];
if (!pvNode)
{
+ // If bestValue isn't changed it means it is still the static evaluation of
+ // the node, so keep this info to avoid a future costly evaluation() call.
+ ValueType type = (bestValue == staticValue && !ei.futilityMargin ? VALUE_TYPE_EV_UP : VALUE_TYPE_UPPER);
Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1));
+
if (bestValue < beta)
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, d, MOVE_NONE);
+ TT.store(pos.get_key(), value_to_tt(bestValue, ply), type, d, MOVE_NONE);
else
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, m);
+ TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move);
}
// Update killers only for good check moves
- if (alpha >= beta && ok_to_history(pos, m)) // Only non capture moves are considered
- update_killers(m, ss[ply]);
+ if (alpha >= beta && !pos.move_is_capture_or_promotion(move))
+ update_killers(move, ss[ply]);
return bestValue;
}
assert(move_is_ok(move));
bool moveIsCheck = pos.move_is_check(move, sp->dcCandidates);
- bool moveIsCapture = pos.move_is_capture(move);
+ bool captureOrPromotion = pos.move_is_capture_or_promotion(move);
lock_grab(&(sp->lock));
int moveCount = ++sp->moves;
// Decide the new search depth.
bool dangerous;
- Depth ext = extension(pos, move, false, moveIsCapture, moveIsCheck, false, false, &dangerous);
+ Depth ext = extension(pos, move, sp->depth, false, captureOrPromotion, moveIsCheck, false, false, &dangerous);
Depth newDepth = sp->depth - OnePly + ext;
// Prune?
if ( useFutilityPruning
&& !dangerous
- && !moveIsCapture
- && !move_is_promotion(move)
- && moveCount >= 2 + int(sp->depth)
- && ok_to_prune(pos, move, ss[sp->ply].threatMove, sp->depth))
- continue;
+ && !captureOrPromotion)
+ {
+ // History pruning. See ok_to_prune() definition
+ if ( moveCount >= 2 + int(sp->depth)
+ && ok_to_prune(pos, move, ss[sp->ply].threatMove, sp->depth)
+ && sp->bestValue > value_mated_in(PLY_MAX))
+ continue;
+
+ // Value based pruning
+ if (sp->approximateEval < sp->beta)
+ {
+ if (sp->futilityValue == VALUE_NONE)
+ {
+ EvalInfo ei;
+ sp->futilityValue = evaluate(pos, ei, threadID)
+ + FutilityMargins[int(sp->depth) - 2];
+ }
+
+ if (sp->futilityValue < sp->beta)
+ {
+ if (sp->futilityValue > sp->bestValue) // Less then 1% of cases
+ {
+ lock_grab(&(sp->lock));
+ if (sp->futilityValue > sp->bestValue)
+ sp->bestValue = sp->futilityValue;
+ lock_release(&(sp->lock));
+ }
+ continue;
+ }
+ }
+ }
// Make and search the move.
StateInfo st;
// if the move fails high will be re-searched at full depth.
if ( !dangerous
&& moveCount >= LMRNonPVMoves
- && !moveIsCapture
- && !move_is_promotion(move)
+ && !captureOrPromotion
&& !move_is_castle(move)
&& !move_is_killer(move, ss[sp->ply]))
{
break;
// New best move?
- lock_grab(&(sp->lock));
- if (value > sp->bestValue && !thread_should_stop(threadID))
+ if (value > sp->bestValue) // Less then 2% of cases
{
- sp->bestValue = value;
- if (sp->bestValue >= sp->beta)
+ lock_grab(&(sp->lock));
+ if (value > sp->bestValue && !thread_should_stop(threadID))
{
- sp_update_pv(sp->parentSstack, ss, sp->ply);
- for (int i = 0; i < ActiveThreads; i++)
- if (i != threadID && (i == sp->master || sp->slaves[i]))
- Threads[i].stop = true;
+ sp->bestValue = value;
+ if (sp->bestValue >= sp->beta)
+ {
+ sp_update_pv(sp->parentSstack, ss, sp->ply);
+ for (int i = 0; i < ActiveThreads; i++)
+ if (i != threadID && (i == sp->master || sp->slaves[i]))
+ Threads[i].stop = true;
- sp->finished = true;
- }
+ sp->finished = true;
+ }
+ }
+ lock_release(&(sp->lock));
}
- lock_release(&(sp->lock));
}
lock_grab(&(sp->lock));
&& (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE)
{
bool moveIsCheck = pos.move_is_check(move, sp->dcCandidates);
- bool moveIsCapture = pos.move_is_capture(move);
+ bool captureOrPromotion = pos.move_is_capture_or_promotion(move);
assert(move_is_ok(move));
// Decide the new search depth.
bool dangerous;
- Depth ext = extension(pos, move, true, moveIsCapture, moveIsCheck, false, false, &dangerous);
+ Depth ext = extension(pos, move, sp->depth, true, captureOrPromotion, moveIsCheck, false, false, &dangerous);
Depth newDepth = sp->depth - OnePly + ext;
// Make and search the move.
// if the move fails high will be re-searched at full depth.
if ( !dangerous
&& moveCount >= LMRPVMoves
- && !moveIsCapture
- && !move_is_promotion(move)
+ && !captureOrPromotion
&& !move_is_castle(move)
&& !move_is_killer(move, ss[sp->ply]))
{
bool includeAllMoves = (searchMoves[0] == MOVE_NONE);
// Generate all legal moves
- int lm_count = generate_legal_moves(pos, mlist);
+ MoveStack* last = generate_moves(pos, mlist);
// Add each move to the moves[] array
- for (int i = 0; i < lm_count; i++)
+ for (MoveStack* cur = mlist; cur != last; cur++)
{
bool includeMove = includeAllMoves;
for (int k = 0; !includeMove && searchMoves[k] != MOVE_NONE; k++)
- includeMove = (searchMoves[k] == mlist[i].move);
+ includeMove = (searchMoves[k] == cur->move);
if (!includeMove)
continue;
// Find a quick score for the move
StateInfo st;
SearchStack ss[PLY_MAX_PLUS_2];
+ init_ss_array(ss);
- moves[count].move = mlist[i].move;
+ moves[count].move = cur->move;
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);
// 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);
- if (Slowdown && Iteration >= 3)
- slowdown(pos);
-
Threads[threadID].nodes++;
if (threadID == 0)
// the second move is assumed to be a move from the current position.
bool connected_moves(const Position& pos, Move m1, Move m2) {
+
Square f1, t1, f2, t2;
+ Piece p;
assert(move_is_ok(m1));
assert(move_is_ok(m2));
return true;
// Case 4: The destination square for m2 is attacked by the moving piece in m1
- if (pos.piece_attacks_square(pos.piece_on(t1), t1, t2))
+ p = pos.piece_on(t1);
+ if (bit_is_set(pos.attacks_from(p, t1), t2))
return true;
// Case 5: Discovered check, checking piece is the piece moved in m1
- if ( piece_is_slider(pos.piece_on(t1))
+ if ( piece_is_slider(p)
&& bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), f2)
- && !bit_is_set(squares_between(t2, pos.king_square(pos.side_to_move())), t2))
+ && !bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), t2))
{
Bitboard occ = pos.occupied_squares();
Color us = pos.side_to_move();
Square ksq = pos.king_square(us);
clear_bit(&occ, f2);
- if (pos.type_of_piece_on(t1) == BISHOP)
+ if (type_of_piece(p) == BISHOP)
{
if (bit_is_set(bishop_attacks_bb(ksq, occ), t1))
return true;
}
- else if (pos.type_of_piece_on(t1) == ROOK)
+ else if (type_of_piece(p) == ROOK)
{
if (bit_is_set(rook_attacks_bb(ksq, occ), t1))
return true;
}
else
{
- assert(pos.type_of_piece_on(t1) == QUEEN);
+ assert(type_of_piece(p) == QUEEN);
if (bit_is_set(queen_attacks_bb(ksq, occ), t1))
return true;
}
// 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 capture, bool check,
- bool singleReply, bool mateThreat, bool* dangerous) {
+ Depth extension(const Position& pos, Move m, Depth depth, bool pvNode, bool captureOrPromotion,
+ bool check, bool singleReply, bool mateThreat, bool* dangerous) {
assert(m != MOVE_NONE);
result += MateThreatExtension[pvNode];
}
+ if ( pvNode
+ && captureOrPromotion
+ && pos.type_of_piece_on(move_to(m)) != PAWN
+ && pos.see_sign(m) >= 0)
+ {
+ result += OnePly/2;
+ *dangerous = true;
+ }
+
+ // Do not extend at low depths
+ if (!pvNode && depth < 4*OnePly)
+ return Min(result, OnePly); // Further test with Min(result, OnePly / 2)
+
if (pos.type_of_piece_on(move_from(m)) == PAWN)
{
Color c = pos.side_to_move();
}
}
- if ( capture
+ if ( captureOrPromotion
&& 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))
*dangerous = true;
}
- if ( pvNode
- && capture
- && pos.type_of_piece_on(move_to(m)) != PAWN
- && pos.see_sign(m) >= 0)
- {
- result += OnePly/2;
- *dangerous = true;
- }
-
return Min(result, OnePly);
}
assert(move_is_ok(m));
assert(threat == MOVE_NONE || move_is_ok(threat));
- assert(!move_is_promotion(m));
assert(!pos.move_is_check(m));
- assert(!pos.move_is_capture(m));
+ assert(!pos.move_is_capture_or_promotion(m));
assert(!pos.move_is_passed_pawn_push(m));
assert(d >= OnePly);
}
- // ok_to_history() returns true if a move m can be stored
- // in history. Should be a non capturing move nor a promotion.
-
- bool ok_to_history(const Position& pos, Move m) {
-
- return !pos.move_is_capture(m) && !move_is_promotion(m);
- }
-
-
// update_history() registers a good move that produced a beta-cutoff
// in history and marks as failures all the other moves of that ply.
for (int i = 0; i < moveCount - 1; i++)
{
assert(m != movesSearched[i]);
- if (ok_to_history(pos, movesSearched[i]))
+ if (!pos.move_is_capture_or_promotion(movesSearched[i]))
H.failure(pos.piece_on(move_from(movesSearched[i])), move_to(movesSearched[i]));
}
}
}
- // slowdown() simply wastes CPU cycles doing nothing useful. It's used
- // in strength handicap mode.
-
- void slowdown(const Position &pos) {
- int i, n;
- n = Slowdown;
- for (i = 0; i < n; i++) {
- Square s = Square(i&63);
- if (count_1s(pos.attacks_to(s)) > 63)
- std::cout << "This can't happen, but I put this string here anyway, in order to prevent the compiler from optimizing away the useless computation." << std::endl;
- }
- }
-
-
// fail_high_ply_1() checks if some thread is currently resolving a fail
// high at ply 1 at the node below the first root node. This information
// is used for time managment.
}
+ // init_ss_array() does a fast reset of the first entries of a SearchStack array
+
+ void init_ss_array(SearchStack ss[]) {
+
+ for (int i = 0; i < 3; i++)
+ {
+ ss[i].init(i);
+ ss[i].initKillers();
+ }
+ }
+
+
// wait_for_stop_or_ponderhit() is called when the maximum depth is reached
// while the program is pondering. The point is to work around a wrinkle in
// the UCI protocol: When pondering, the engine is not allowed to give a
// 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, const Value futilityValue,
+ const Value approximateEval, Depth depth, int* moves,
MovePicker* mp, Bitboard dcCandidates, int master, bool pvNode) {
assert(p.is_ok());
splitPoint->pvNode = pvNode;
splitPoint->dcCandidates = dcCandidates;
splitPoint->bestValue = *bestValue;
+ splitPoint->futilityValue = futilityValue;
+ splitPoint->approximateEval = approximateEval;
splitPoint->master = master;
splitPoint->mp = mp;
splitPoint->moves = *moves;
projects / stockfish / blobdiff