//// Includes
////
-#include <algorithm>
#include <cassert>
#include "history.h"
-#include "evaluate.h"
#include "movegen.h"
#include "movepick.h"
#include "search.h"
namespace {
- /// Variables
+ enum MovegenPhase {
+ PH_TT_MOVES, // Transposition table move and mate killer
+ PH_GOOD_CAPTURES, // Queen promotions and captures with SEE values >= 0
+ PH_KILLERS, // Killer moves from the current ply
+ PH_NONCAPTURES, // Non-captures and underpromotions
+ PH_BAD_CAPTURES, // Queen promotions and captures with SEE values < 0
+ PH_EVASIONS, // Check evasions
+ PH_QCAPTURES, // Captures in quiescence search
+ PH_QCHECKS, // Non-capture checks in quiescence search
+ PH_STOP
+ };
CACHE_LINE_ALIGNMENT
- const MovegenPhaseT MainSearchPhaseTable[] = { PH_NULL_MOVE, PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP};
- const MovegenPhaseT MainSearchNoNullPhaseTable[] = { PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP};
- const MovegenPhaseT LowSearchPhaseTable[] = { PH_TT_MOVES, PH_GOOD_CAPTURES, PH_NULL_MOVE, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP};
- const MovegenPhaseT EvasionsPhaseTable[] = { PH_EVASIONS, PH_STOP};
- const MovegenPhaseT QsearchWithChecksPhaseTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_QCHECKS, PH_STOP};
- const MovegenPhaseT QsearchWithoutChecksPhaseTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_STOP};
+ const uint8_t MainSearchPhaseTable[] = { PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP};
+ const uint8_t EvasionsPhaseTable[] = { PH_TT_MOVES, PH_EVASIONS, PH_STOP};
+ const uint8_t QsearchWithChecksPhaseTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_QCHECKS, PH_STOP};
+ const uint8_t QsearchWithoutChecksPhaseTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_STOP};
}
////
-/// Constructor for the MovePicker class. Apart from the position for which
+/// Constructor for the MovePicker class. Apart from the position for which
/// it is asked to pick legal moves, MovePicker also wants some information
/// to help it to return the presumably good moves first, to decide which
/// moves to return (in the quiescence search, for instance, we only want to
/// move ordering is at the current node.
MovePicker::MovePicker(const Position& p, Move ttm, Depth d,
- const History& h, SearchStack* ss, bool useNullMove) : pos(p), H(h) {
- ttMoves[0] = ttm;
- if (ss)
- {
- ttMoves[1] = (ss->mateKiller == ttm)? MOVE_NONE : ss->mateKiller;
- killers[0] = ss->killers[0];
- killers[1] = ss->killers[1];
- } else
- ttMoves[1] = killers[0] = killers[1] = MOVE_NONE;
-
- numOfBadCaptures = 0;
- finished = false;
+ const History& h, SearchStack* ss) : pos(p), H(h) {
+ int searchTT = ttm;
+ ttMoves[0].move = ttm;
+ lastBadCapture = badCaptures;
- Color us = pos.side_to_move();
+ pinned = p.pinned_pieces(pos.side_to_move());
- dc = p.discovered_check_candidates(us);
- pinned = p.pinned_pieces(us);
+ if (ss && !p.is_check())
+ {
+ ttMoves[1].move = (ss->mateKiller == ttm)? MOVE_NONE : ss->mateKiller;
+ searchTT |= ttMoves[1].move;
+ killers[0].move = ss->killers[0];
+ killers[1].move = ss->killers[1];
+ } else
+ ttMoves[1].move = killers[0].move = killers[1].move = MOVE_NONE;
if (p.is_check())
phasePtr = EvasionsPhaseTable;
- else if (d >= Depth(3 * OnePly))
- phasePtr = useNullMove ? MainSearchPhaseTable : MainSearchNoNullPhaseTable;
else if (d > Depth(0))
- phasePtr = useNullMove ? LowSearchPhaseTable : MainSearchNoNullPhaseTable;
+ phasePtr = MainSearchPhaseTable;
else if (d == Depth(0))
phasePtr = QsearchWithChecksPhaseTable;
else
+ {
phasePtr = QsearchWithoutChecksPhaseTable;
- phasePtr--;
+ // Skip TT move if is not a capture or a promotion, this avoids
+ // qsearch tree explosion due to a possible perpetual check or
+ // similar rare cases when TT table is full.
+ if (ttm != MOVE_NONE && !pos.move_is_capture_or_promotion(ttm))
+ searchTT = ttMoves[0].move = MOVE_NONE;
+ }
+
+ phasePtr += !searchTT - 1;
go_next_phase();
}
/// MovePicker::go_next_phase() generates, scores and sorts the next bunch
-/// of moves when there are no more moves to try for the currrent phase.
+/// of moves when there are no more moves to try for the current phase.
void MovePicker::go_next_phase() {
- movesPicked = 0;
+ curMove = moves;
phase = *(++phasePtr);
switch (phase) {
- case PH_NULL_MOVE:
case PH_TT_MOVES:
+ curMove = ttMoves;
+ lastMove = curMove + 2;
return;
case PH_GOOD_CAPTURES:
- numOfMoves = generate_captures(pos, moves);
+ lastMove = generate_captures(pos, moves);
score_captures();
- std::sort(moves, moves + numOfMoves);
return;
case PH_KILLERS:
+ curMove = killers;
+ lastMove = curMove + 2;
return;
case PH_NONCAPTURES:
- numOfMoves = generate_noncaptures(pos, moves);
+ lastMove = generate_noncaptures(pos, moves);
score_noncaptures();
- std::sort(moves, moves + numOfMoves);
+ sort_moves(moves, lastMove);
return;
case PH_BAD_CAPTURES:
// Bad captures SEE value is already calculated so just sort them
// to get SEE move ordering.
- std::sort(badCaptures, badCaptures + numOfBadCaptures);
+ curMove = badCaptures;
+ lastMove = lastBadCapture;
return;
case PH_EVASIONS:
assert(pos.is_check());
- numOfMoves = generate_evasions(pos, moves, pinned);
- score_evasions();
- std::sort(moves, moves + numOfMoves);
+ lastMove = generate_evasions(pos, moves);
+ score_evasions_or_checks();
return;
case PH_QCAPTURES:
- numOfMoves = generate_captures(pos, moves);
+ lastMove = generate_captures(pos, moves);
score_captures();
- std::sort(moves, moves + numOfMoves);
return;
case PH_QCHECKS:
- // Perhaps we should order moves move here? FIXME
- numOfMoves = generate_non_capture_checks(pos, moves, dc);
+ lastMove = generate_non_capture_checks(pos, moves);
+ score_evasions_or_checks();
return;
case PH_STOP:
+ lastMove = curMove + 1; // Avoids another go_next_phase() call
return;
default:
}
-/// MovePicker::score_captures(), MovePicker::score_noncaptures(),
-/// MovePicker::score_evasions() and MovePicker::score_qcaptures() assign a
-/// numerical move ordering score to each move in a move list. The moves
-/// with highest scores will be picked first by pick_move_from_list().
+/// MovePicker::score_captures(), MovePicker::score_noncaptures() and
+/// MovePicker::score_evasions() assign a numerical move ordering score
+/// to each move in a move list. The moves with highest scores will be
+/// picked first by get_next_move().
void MovePicker::score_captures() {
// Winning and equal captures in the main search are ordered by MVV/LVA.
Move m;
// Use MVV/LVA ordering
- for (int i = 0; i < numOfMoves; i++)
+ for (MoveStack* cur = moves; cur != lastMove; cur++)
{
- m = moves[i].move;
+ m = cur->move;
if (move_is_promotion(m))
- moves[i].score = QueenValueMidgame;
+ cur->score = QueenValueMidgame;
else
- moves[i].score = int(pos.midgame_value_of_piece_on(move_to(m)))
- -int(pos.type_of_piece_on(move_from(m)));
+ cur->score = pos.midgame_value_of_piece_on(move_to(m))
+ - pos.type_of_piece_on(move_from(m));
}
}
// First score by history, when no history is available then use
// piece/square tables values. This seems to be better then a
// random choice when we don't have an history for any move.
+ Move m;
Piece piece;
Square from, to;
- int hs;
- for (int i = 0; i < numOfMoves; i++)
+ for (MoveStack* cur = moves; cur != lastMove; cur++)
{
- from = move_from(moves[i].move);
- to = move_to(moves[i].move);
+ m = cur->move;
+ from = move_from(m);
+ to = move_to(m);
piece = pos.piece_on(from);
- hs = H.move_ordering_score(piece, to);
-
- // Ensure history is always preferred to pst
- if (hs > 0)
- hs += 1000;
-
- // pst based scoring
- moves[i].score = hs + pos.pst_delta<Position::MidGame>(piece, from, to);
+ cur->score = H.move_ordering_score(piece, to);
}
}
-void MovePicker::score_evasions() {
+void MovePicker::score_evasions_or_checks() {
+ // Try good captures ordered by MVV/LVA, then non-captures if
+ // destination square is not under attack, ordered by history
+ // value, and at the end bad-captures and non-captures with a
+ // negative SEE. This last group is ordered by the SEE score.
+ Move m;
+ int seeScore;
+
+ // Skip if we don't have at least two moves to order
+ if (lastMove < moves + 2)
+ return;
- for (int i = 0; i < numOfMoves; i++)
+ for (MoveStack* cur = moves; cur != lastMove; cur++)
{
- Move m = moves[i].move;
- if (m == ttMoves[0])
- moves[i].score = 2*HistoryMax;
- else if (!pos.square_is_empty(move_to(m)))
- {
- int seeScore = pos.see(m);
- moves[i].score = (seeScore >= 0)? seeScore + HistoryMax : seeScore;
- } else
- moves[i].score = H.move_ordering_score(pos.piece_on(move_from(m)), move_to(m));
+ m = cur->move;
+ if ((seeScore = pos.see_sign(m)) < 0)
+ cur->score = seeScore;
+ else if (pos.move_is_capture(m))
+ cur->score = pos.midgame_value_of_piece_on(move_to(m))
+ - pos.type_of_piece_on(move_from(m)) + HistoryMax;
+ else
+ cur->score = H.move_ordering_score(pos.piece_on(move_from(m)), move_to(m));
}
}
/// class. It returns a new legal move every time it is called, until there
/// are no more moves left.
/// It picks the move with the biggest score from a list of generated moves taking
-/// care not to return the tt move if that has already been serched previously.
+/// care not to return the tt move if has already been searched previously.
+/// Note that this function is not thread safe so should be lock protected by
+/// caller when accessed through a shared MovePicker object.
Move MovePicker::get_next_move() {
- assert(movesPicked >= 0);
- assert(!pos.is_check() || *phasePtr == PH_EVASIONS || *phasePtr == PH_STOP);
- assert( pos.is_check() || *phasePtr != PH_EVASIONS);
+ Move move;
while (true)
{
- switch (phase) {
-
- case PH_NULL_MOVE:
- go_next_phase();
- return MOVE_NULL;
-
- case PH_TT_MOVES:
- while (movesPicked < 2) {
- Move move = ttMoves[movesPicked++];
- if ( move != MOVE_NONE
- && move_is_legal(pos, move, pinned))
- return move;
- }
- break;
-
- case PH_GOOD_CAPTURES:
- while (movesPicked < numOfMoves)
- {
- Move move = moves[movesPicked++].move;
- if ( move != ttMoves[0]
- && move != ttMoves[1]
+ while (curMove != lastMove)
+ {
+ switch (phase) {
+
+ case PH_TT_MOVES:
+ move = (curMove++)->move;
+ if ( move != MOVE_NONE
+ && move_is_legal(pos, move, pinned))
+ return move;
+ break;
+
+ case PH_GOOD_CAPTURES:
+ move = pick_best(curMove++, lastMove).move;
+ if ( move != ttMoves[0].move
+ && move != ttMoves[1].move
&& pos.pl_move_is_legal(move, pinned))
{
// Check for a non negative SEE now
// Losing capture, move it to the badCaptures[] array, note
// that move has now been already checked for legality.
- assert(numOfBadCaptures < 63);
- badCaptures[numOfBadCaptures].move = move;
- badCaptures[numOfBadCaptures++].score = seeValue;
+ assert(int(lastBadCapture - badCaptures) < 63);
+ lastBadCapture->move = move;
+ lastBadCapture->score = seeValue;
+ lastBadCapture++;
}
- }
- break;
-
- case PH_KILLERS:
- while (movesPicked < 2) {
- Move move = killers[movesPicked++];
- if ( move != MOVE_NONE
- && move != ttMoves[0]
- && move != ttMoves[1]
- && move_is_legal(pos, move, pinned)
- && !pos.move_is_capture(move))
- return move;
- }
- break;
-
- case PH_NONCAPTURES:
- while (movesPicked < numOfMoves)
- {
- Move move = moves[movesPicked++].move;
- if ( move != ttMoves[0]
- && move != ttMoves[1]
- && move != killers[0]
- && move != killers[1]
+ break;
+
+ case PH_KILLERS:
+ move = (curMove++)->move;
+ if ( move != MOVE_NONE
+ && move != ttMoves[0].move
+ && move != ttMoves[1].move
+ && move_is_legal(pos, move, pinned)
+ && !pos.move_is_capture(move))
+ return move;
+ break;
+
+ case PH_NONCAPTURES:
+ move = (curMove++)->move;
+ if ( move != ttMoves[0].move
+ && move != ttMoves[1].move
+ && move != killers[0].move
+ && move != killers[1].move
&& pos.pl_move_is_legal(move, pinned))
return move;
- }
- break;
-
- case PH_EVASIONS:
- if (movesPicked < numOfMoves)
- return moves[movesPicked++].move;
- break;
-
- case PH_BAD_CAPTURES:
- if (movesPicked < numOfBadCaptures)
- return badCaptures[movesPicked++].move;
- break;
-
- case PH_QCAPTURES:
- case PH_QCHECKS:
- while (movesPicked < numOfMoves)
- {
- Move move = moves[movesPicked++].move;
- // Maybe postpone the legality check until after futility pruning?
- if ( move != ttMoves[0]
+ break;
+
+ case PH_BAD_CAPTURES:
+ move = pick_best(curMove++, lastMove).move;
+ return move;
+
+ case PH_EVASIONS:
+ case PH_QCAPTURES:
+ move = pick_best(curMove++, lastMove).move;
+ if ( move != ttMoves[0].move
&& pos.pl_move_is_legal(move, pinned))
return move;
- }
- break;
+ break;
- case PH_STOP:
- return MOVE_NONE;
+ case PH_QCHECKS:
+ move = (curMove++)->move;
+ if ( move != ttMoves[0].move
+ && pos.pl_move_is_legal(move, pinned))
+ return move;
+ break;
- default:
- assert(false);
- break;
+ case PH_STOP:
+ return MOVE_NONE;
+
+ default:
+ assert(false);
+ break;
+ }
}
go_next_phase();
}
- return MOVE_NONE;
}
-/// A variant of get_next_move() which takes a lock as a parameter, used to
-/// prevent multiple threads from picking the same move at a split point.
-
-Move MovePicker::get_next_move(Lock &lock) {
-
- lock_grab(&lock);
- if (finished)
- {
- lock_release(&lock);
- return MOVE_NONE;
- }
- Move m = get_next_move();
- if (m == MOVE_NONE)
- finished = true;
-
- lock_release(&lock);
- return m;
-}
projects / stockfish / blobdiff