#include "evaluate.h"
#include "history.h"
#include "misc.h"
-#include "move.h"
#include "movegen.h"
#include "movepick.h"
#include "search.h"
#include "tt.h"
#include "ucioption.h"
-using std::cout;
-using std::endl;
-using std::string;
-using Search::Signals;
-using Search::Limits;
-
namespace Search {
volatile SignalsType Signals;
LimitsType Limits;
std::vector<Move> RootMoves;
- Position* RootPosition;
+ Position RootPosition;
}
+using std::cout;
+using std::endl;
+using std::string;
+using namespace Search;
+
namespace {
// Set to true to force running with one thread. Used for debugging
const bool Slidings[18] = { 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1 };
inline bool piece_is_slider(Piece p) { return Slidings[p]; }
- // Step 6. Razoring
-
// Maximum depth for razoring
const Depth RazorDepth = 4 * ONE_PLY;
// Maximum depth for use of dynamic threat detection when null move fails low
const Depth ThreatDepth = 5 * ONE_PLY;
- // Step 9. Internal iterative deepening
-
// Minimum depth for use of internal iterative deepening
const Depth IIDDepth[] = { 8 * ONE_PLY, 5 * ONE_PLY };
// when the static evaluation is bigger then beta - IIDMargin.
const Value IIDMargin = Value(0x100);
- // Step 11. Decide the new search depth
-
- // Extensions. Array index 0 is used for non-PV nodes, index 1 for PV nodes
- const Depth CheckExtension[] = { ONE_PLY / 2, ONE_PLY / 1 };
- const Depth PawnEndgameExtension[] = { ONE_PLY / 1, ONE_PLY / 1 };
- const Depth PawnPushTo7thExtension[] = { ONE_PLY / 2, ONE_PLY / 2 };
- const Depth PassedPawnExtension[] = { DEPTH_ZERO, ONE_PLY / 2 };
-
// Minimum depth for use of singular extension
const Depth SingularExtensionDepth[] = { 8 * ONE_PLY, 6 * ONE_PLY };
- // Step 12. Futility pruning
-
// Futility margin for quiescence search
const Value FutilityMarginQS = Value(0x80);
return d < 16 * ONE_PLY ? FutilityMoveCounts[d] : MAX_MOVES;
}
- // Step 14. Reduced search
-
// Reduction lookup tables (initialized at startup) and their access function
int8_t Reductions[2][64][64]; // [pv][depth][moveNumber]
RootMoveList Rml;
// MultiPV mode
- int MultiPV, UCIMultiPV, MultiPVIdx;
+ size_t MultiPV, UCIMultiPV, MultiPVIdx;
// Time management variables
TimeManager TimeMgr;
Move id_loop(Position& pos, Move rootMoves[], Move* ponderMove);
template <NodeType NT>
- Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth);
+ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
template <NodeType NT>
- Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth);
+ Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bValue);
bool connected_moves(const Position& pos, Move m1, Move m2);
void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount);
void do_skill_level(Move* best, Move* ponder);
- int elapsed_search_time(int set = 0);
+ int elapsed_time(bool reset = false);
string score_to_uci(Value v, Value alpha = -VALUE_INFINITE, Value beta = VALUE_INFINITE);
string speed_to_uci(int64_t nodes);
string pv_to_uci(const Move pv[], int pvNum, bool chess960);
// we simply create and use a standard MovePicker object.
template<bool SpNode> struct MovePickerExt : public MovePicker {
- MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
+ MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, Stack* ss, Value b)
: MovePicker(p, ttm, d, h, ss, b) {}
};
// In case of a SpNode we use split point's shared MovePicker object as moves source
template<> struct MovePickerExt<true> : public MovePicker {
- MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
+ MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, Stack* ss, Value b)
: MovePicker(p, ttm, d, h, ss, b), mp(ss->sp->mp) {}
Move get_next_move() { return mp->get_next_move(); }
return os;
}
- // 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 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.
- template <bool PvNode>
- FORCE_INLINE Depth extension(const Position& pos, Move m, bool captureOrPromotion,
- bool moveIsCheck, bool* dangerous) {
- assert(m != MOVE_NONE);
-
- Depth result = DEPTH_ZERO;
- *dangerous = moveIsCheck;
-
- if (moveIsCheck && pos.see_sign(m) >= 0)
- result += CheckExtension[PvNode];
+ // is_dangerous() checks whether a move belongs to some classes of known
+ // 'dangerous' moves so that we avoid to prune it.
+ FORCE_INLINE bool is_dangerous(const Position& pos, Move m, bool captureOrPromotion) {
+ // Test for a pawn pushed to 7th or a passed pawn move
if (type_of(pos.piece_on(move_from(m))) == PAWN)
{
Color c = pos.side_to_move();
- if (relative_rank(c, move_to(m)) == RANK_7)
- {
- result += PawnPushTo7thExtension[PvNode];
- *dangerous = true;
- }
- if (pos.pawn_is_passed(c, move_to(m)))
- {
- result += PassedPawnExtension[PvNode];
- *dangerous = true;
- }
+ if ( relative_rank(c, move_to(m)) == RANK_7
+ || pos.pawn_is_passed(c, move_to(m)))
+ return true;
}
+ // Test for a capture that triggers a pawn endgame
if ( captureOrPromotion
&& type_of(pos.piece_on(move_to(m))) != PAWN
&& ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK)
- PieceValueMidgame[pos.piece_on(move_to(m))] == VALUE_ZERO)
&& !is_special(m))
- {
- result += PawnEndgameExtension[PvNode];
- *dangerous = true;
- }
+ return true;
- return std::min(result, ONE_PLY);
+ return false;
}
} // namespace
}
-/// think() is the external interface to Stockfish's search, and is called when
-/// the program receives the UCI 'go' command. It initializes various global
-/// variables, and calls id_loop(). It returns false when a "quit" command is
-/// received during the search.
+/// think() is the external interface to Stockfish's search, and is called by the
+/// main thread when the program receives the UCI 'go' command. It searches from
+/// RootPosition and at the end prints the "bestmove" to output.
void Search::think() {
static Book book; // Defined static to initialize the PRNG only once
- Position& pos = *RootPosition;
+ Position& pos = RootPosition;
- // Save "search start" time and reset elapsed time to zero
- elapsed_search_time(get_system_time());
-
- // Reset global search signals
- memset((void*)&Signals, 0, sizeof(Signals));
+ // Reset elapsed search time
+ elapsed_time(true);
// Set output stream mode: normal or chess960. Castling notation is different
cout << set960(pos.is_chess960());
TT.clear();
}
- UCIMultiPV = Options["MultiPV"].value<int>();
- SkillLevel = Options["Skill Level"].value<int>();
+ UCIMultiPV = Options["MultiPV"].value<size_t>();
+ SkillLevel = Options["Skill Level"].value<size_t>();
// Do we have to play with skill handicap? In this case enable MultiPV that
// we will use behind the scenes to retrieve a set of possible moves.
SkillLevelEnabled = (SkillLevel < 20);
- MultiPV = (SkillLevelEnabled ? std::max(UCIMultiPV, 4) : UCIMultiPV);
+ MultiPV = (SkillLevelEnabled ? std::max(UCIMultiPV, (size_t)4) : UCIMultiPV);
// Write current search header to log file
if (Options["Use Search Log"].value<bool>())
// Write current search final statistics to log file
if (Options["Use Search Log"].value<bool>())
{
- int e = elapsed_search_time();
+ int e = elapsed_time();
Log log(Options["Search Log Filename"].value<string>());
log << "Nodes: " << pos.nodes_searched()
Move id_loop(Position& pos, Move rootMoves[], Move* ponderMove) {
- SearchStack ss[PLY_MAX_PLUS_2];
+ Stack ss[PLY_MAX_PLUS_2];
Value bestValues[PLY_MAX_PLUS_2];
int bestMoveChanges[PLY_MAX_PLUS_2];
int depth, aspirationDelta;
bool bestMoveNeverChanged = true;
// Initialize stuff before a new search
- memset(ss, 0, 4 * sizeof(SearchStack));
+ memset(ss, 0, 4 * sizeof(Stack));
TT.new_search();
H.clear();
*ponderMove = bestMove = skillBest = skillPonder = MOVE_NONE;
Rml.init(pos, rootMoves);
// Handle special case of searching on a mate/stalemate position
- if (!Rml.size())
+ if (Rml.empty())
{
cout << "info" << depth_to_uci(DEPTH_ZERO)
<< score_to_uci(pos.in_check() ? -VALUE_MATE : VALUE_DRAW, alpha, beta) << endl;
Rml.bestMoveChanges = 0;
// MultiPV loop. We perform a full root search for each PV line
- for (MultiPVIdx = 0; MultiPVIdx < std::min(MultiPV, (int)Rml.size()); MultiPVIdx++)
+ for (MultiPVIdx = 0; MultiPVIdx < std::min(MultiPV, Rml.size()); MultiPVIdx++)
{
// Calculate dynamic aspiration window based on previous iterations
if (depth >= 5 && abs(Rml[MultiPVIdx].prevScore) < VALUE_KNOWN_WIN)
// Write PV back to transposition table in case the relevant entries
// have been overwritten during the search.
- for (int i = 0; i <= MultiPVIdx; i++)
+ for (size_t i = 0; i <= MultiPVIdx; i++)
Rml[i].insert_pv_in_tt(pos);
// If search has been stopped exit the aspiration window loop,
// if we have a fail high/low and we are deep in the search. UCI
// protocol requires to send all the PV lines also if are still
// to be searched and so refer to the previous search's score.
- if ((bestValue > alpha && bestValue < beta) || elapsed_search_time() > 2000)
- for (int i = 0; i < std::min(UCIMultiPV, (int)Rml.size()); i++)
+ if ((bestValue > alpha && bestValue < beta) || elapsed_time() > 2000)
+ for (size_t i = 0; i < std::min(UCIMultiPV, Rml.size()); i++)
{
bool updated = (i <= MultiPVIdx);
if (Options["Use Search Log"].value<bool>())
{
Log log(Options["Search Log Filename"].value<string>());
- log << pretty_pv(pos, depth, bestValue, elapsed_search_time(), &Rml[0].pv[0]) << endl;
+ log << pretty_pv(pos, depth, bestValue, elapsed_time(), &Rml[0].pv[0]) << endl;
}
// Filter out startup noise when monitoring best move stability
// Do we have time for the next iteration? Can we stop searching now?
if (!Signals.stop && !Signals.stopOnPonderhit && Limits.useTimeManagement())
{
+ bool stop = false; // Local variable instead of the volatile Signals.stop
+
// Take in account some extra time if the best move has changed
if (depth > 4 && depth < 50)
TimeMgr.pv_instability(bestMoveChanges[depth], bestMoveChanges[depth - 1]);
// Stop search if most of available time is already consumed. We probably don't
// have enough time to search the first move at the next iteration anyway.
- if (elapsed_search_time() > (TimeMgr.available_time() * 62) / 100)
- Signals.stop = true;
+ if (elapsed_time() > (TimeMgr.available_time() * 62) / 100)
+ stop = true;
// Stop search early if one move seems to be much better than others
if ( depth >= 10
- && !Signals.stop
+ && !stop
&& ( bestMoveNeverChanged
- || elapsed_search_time() > (TimeMgr.available_time() * 40) / 100))
+ || elapsed_time() > (TimeMgr.available_time() * 40) / 100))
{
Value rBeta = bestValue - EasyMoveMargin;
(ss+1)->excludedMove = bestMove;
(ss+1)->excludedMove = MOVE_NONE;
if (v < rBeta)
- Signals.stop = true;
+ stop = true;
}
- // If we are allowed to ponder do not stop the search now but keep pondering
- if (Signals.stop && Limits.ponder) // FIXME Limits.ponder is racy
+ if (stop)
{
- Signals.stop = false;
- Signals.stopOnPonderhit = true;
+ // If we are allowed to ponder do not stop the search now but
+ // keep pondering until GUI sends "ponderhit" or "stop".
+ if (Limits.ponder)
+ Signals.stopOnPonderhit = true;
+ else
+ Signals.stop = true;
}
}
}
// here: This is taken care of after we return from the split point.
template <NodeType NT>
- Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) {
+ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
const bool PvNode = (NT == PV || NT == Root || NT == SplitPointPV || NT == SplitPointRoot);
const bool SpNode = (NT == SplitPointPV || NT == SplitPointNonPV || NT == SplitPointRoot);
nodes = pos.nodes_searched();
// For long searches send current move info to GUI
- if (pos.thread() == 0 && elapsed_search_time() > 2000)
+ if (pos.thread() == 0 && elapsed_time() > 2000)
cout << "info" << depth_to_uci(depth)
<< " currmove " << move
<< " currmovenumber " << moveCount + MultiPVIdx << endl;
}
isPvMove = (PvNode && moveCount <= 1);
- givesCheck = pos.move_gives_check(move, ci);
captureOrPromotion = pos.is_capture_or_promotion(move);
+ givesCheck = pos.move_gives_check(move, ci);
+ dangerous = givesCheck || is_dangerous(pos, move, captureOrPromotion);
+ ext = DEPTH_ZERO;
+
+ // Step 12. Extend checks and, in PV nodes, also dangerous moves
+ if (PvNode && dangerous)
+ ext = ONE_PLY;
- // Step 12. Decide the new search depth
- ext = extension<PvNode>(pos, move, captureOrPromotion, givesCheck, &dangerous);
+ else if (givesCheck && pos.see_sign(move) >= 0)
+ ext = PvNode ? ONE_PLY : ONE_PLY / 2;
// Singular extension search. If all moves but one fail low on a search of
// (alpha-s, beta-s), and just one fails high on (alpha, beta), then that move
// on all the other moves but the ttMove, if result is lower than ttValue minus
// a margin then we extend ttMove.
if ( singularExtensionNode
+ && !ext
&& move == ttMove
- && pos.pl_move_is_legal(move, ci.pinned)
- && ext < ONE_PLY)
+ && pos.pl_move_is_legal(move, ci.pinned))
{
Value ttValue = value_from_tt(tte->value(), ss->ply);
// less than ONE_PLY).
template <NodeType NT>
- Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) {
+ Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
const bool PvNode = (NT == PV);
// current_search_time() returns the number of milliseconds which have passed
// since the beginning of the current search.
- int elapsed_search_time(int set) {
+ int elapsed_time(bool reset) {
static int searchStartTime;
- if (set)
- searchStartTime = set;
+ if (reset)
+ searchStartTime = get_system_time();
return get_system_time() - searchStartTime;
}
string speed_to_uci(int64_t nodes) {
std::stringstream s;
- int t = elapsed_search_time();
+ int t = elapsed_time();
s << " nodes " << nodes
<< " nps " << (t > 0 ? int(nodes * 1000 / t) : 0)
// Rml list is already sorted by score in descending order
int s;
+ size_t size = std::min(MultiPV, Rml.size());
int max_s = -VALUE_INFINITE;
- int size = std::min(MultiPV, (int)Rml.size());
int max = Rml[0].score;
int var = std::min(max - Rml[size - 1].score, int(PawnValueMidgame));
int wk = 120 - 2 * SkillLevel;
// Choose best move. For each move's score we add two terms both dependent
// on wk, one deterministic and bigger for weaker moves, and one random,
// then we choose the move with the resulting highest score.
- for (int i = 0; i < size; i++)
+ for (size_t i = 0; i < size; i++)
{
s = Rml[i].score;
assert(!do_terminate);
// Copy split point position and search stack and call search()
- SearchStack ss[PLY_MAX_PLUS_2];
+ Stack ss[PLY_MAX_PLUS_2];
SplitPoint* tsp = splitPoint;
Position pos(*tsp->pos, threadID);
- memcpy(ss, tsp->ss - 1, 4 * sizeof(SearchStack));
+ memcpy(ss, tsp->ss - 1, 4 * sizeof(Stack));
(ss+1)->sp = tsp;
if (tsp->nodeType == Root)
void do_timer_event() {
static int lastInfoTime;
- int e = elapsed_search_time();
+ int e = elapsed_time();
// Print debug information every one second
if (!lastInfoTime || get_system_time() - lastInfoTime >= 1000)
projects / stockfish / blobdiff