X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=3da4247a29e3cdff10de95c06838b7ddb173ae1c;hp=8089345546a1f1c58c31a8f3365fe0f2cf388c24;hb=e25de55faca30c2196612fcb208d88802ad29bae;hpb=a5d699d62fb625fba23b23bdeff2a68807ef6438
diff --git a/src/movepick.cpp b/src/movepick.cpp
index 80893455..3da4247a 100644
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -1,7 +1,7 @@
/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2009 Marco Costalba
+ Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -18,192 +18,212 @@
along with this program. If not, see .
*/
-
-////
-//// Includes
-////
-
#include
#include
-#include "history.h"
-#include "evaluate.h"
#include "movegen.h"
#include "movepick.h"
#include "search.h"
-#include "value.h"
-
-
-////
-//// Local definitions
-////
+#include "types.h"
namespace {
- /// Variables
-
- CACHE_LINE_ALIGNMENT
- const MovegenPhaseT MainSearchPhaseTable[] = { PH_STOP, PH_NULL_MOVE, PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP};
- const MovegenPhaseT MainSearchNoNullPhaseTable[] = { PH_STOP, PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP};
- const MovegenPhaseT EvasionsPhaseTable[] = { PH_STOP, PH_EVASIONS, PH_STOP};
- const MovegenPhaseT QsearchWithChecksPhaseTable[] = { PH_STOP, PH_TT_MOVES, PH_QCAPTURES, PH_QCHECKS, PH_STOP};
- const MovegenPhaseT QsearchWithoutChecksPhaseTable[] = { PH_STOP, PH_TT_MOVES, PH_QCAPTURES, PH_STOP};
+ enum Sequencer {
+ MAIN_SEARCH, TT_MOVE_S1, GOOD_CAPTURES_S1, KILLERS_S1, NONCAPTURES_1_S1,
+ NONCAPTURES_2_S1, BAD_CAPTURES_S1, STOP_S1,
+ EVASIONS, TT_MOVE_S2, EVASIONS_S2, STOP_S2,
+ CAPTURES_AND_CHECKS, TT_MOVE_S3, QCAPTURES_S3, QCHECKS_S3, STOP_S3,
+ CAPTURES, TT_MOVE_S4, QCAPTURES_S4, STOP_S4,
+ RECAPTURES, TT_MOVE_S5, RECAPTURES_S5, STOP_S5,
+ PROBCUT, TT_MOVE_S6, GOOD_CAPTURES_S6, STOP_S6
+ };
+
+ // Unary predicate used by std::partition to split positive scores from remaining
+ // ones so to sort separately the two sets, and with the second sort delayed.
+ inline bool has_positive_score(const MoveStack& move) { return move.score > 0; }
+
+ // Picks and pushes to the front the best move in range [firstMove, lastMove),
+ // it is faster than sorting all the moves in advance when moves are few, as
+ // normally are the possible captures.
+ inline MoveStack* pick_best(MoveStack* firstMove, MoveStack* lastMove)
+ {
+ std::swap(*firstMove, *std::max_element(firstMove, lastMove));
+ return firstMove;
+ }
}
-
-////
-//// Functions
-////
-
-
-/// Constructor for the MovePicker class. Apart from the position for which
-/// it is asked to pick legal moves, MovePicker also wants some information
+/// Constructors for the MovePicker class. As arguments we pass 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
/// search captures, promotions and some checks) and about how important good
/// 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)
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h,
+ Search::Stack* ss, Value beta) : pos(p), H(h), depth(d) {
+ captureThreshold = 0;
+ badCaptures = moves + MAX_MOVES;
+
+ assert(d > DEPTH_ZERO);
+
+ if (p.in_check())
{
- 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;
-
- movesPicked = numOfMoves = numOfBadCaptures = 0;
- finished = false;
-
- if (p.is_check())
- phasePtr = EvasionsPhaseTable;
- else if (d > Depth(0))
- phasePtr = useNullMove ? MainSearchPhaseTable : MainSearchNoNullPhaseTable;
- else if (d == Depth(0))
- phasePtr = QsearchWithChecksPhaseTable;
+ killers[0].move = killers[1].move = MOVE_NONE;
+ phase = EVASIONS;
+ }
else
- phasePtr = QsearchWithoutChecksPhaseTable;
+ {
+ killers[0].move = ss->killers[0];
+ killers[1].move = ss->killers[1];
+
+ // Consider sligtly negative captures as good if at low depth and far from beta
+ if (ss && ss->eval < beta - PawnValueMidgame && d < 3 * ONE_PLY)
+ captureThreshold = -PawnValueMidgame;
- Color us = pos.side_to_move();
+ // Consider negative captures as good if still enough to reach beta
+ else if (ss && ss->eval > beta)
+ captureThreshold = beta - ss->eval;
- dc = p.discovered_check_candidates(us);
- pinned = p.pinned_pieces(us);
+ phase = MAIN_SEARCH;
+ }
+
+ ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE);
+ phase += int(ttMove == MOVE_NONE);
+ go_next_phase();
}
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h, Square recaptureSq)
+ : pos(p), H(h) {
-/// MovePicker::get_next_move() is the most important method of the MovePicker
-/// class. It returns a new legal move every time it is called, until there
-/// are no more moves left of the types we are interested in.
+ assert(d <= DEPTH_ZERO);
-Move MovePicker::get_next_move() {
+ if (p.in_check())
+ phase = EVASIONS;
- Move move;
+ else if (d >= DEPTH_QS_CHECKS)
+ phase = CAPTURES_AND_CHECKS;
- while (true)
+ else if (d >= DEPTH_QS_RECAPTURES)
+ {
+ phase = CAPTURES;
+
+ // 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.is_capture_or_promotion(ttm))
+ ttm = MOVE_NONE;
+ }
+ else
{
- // If we already have a list of generated moves, pick the best move from
- // the list, and return it.
- move = pick_move_from_list();
- if (move != MOVE_NONE)
- {
- assert(move_is_ok(move));
- return move;
- }
-
- // Next phase
- phasePtr++;
- switch (*phasePtr) {
-
- case PH_NULL_MOVE:
- return MOVE_NULL;
-
- case PH_TT_MOVES:
- movesPicked = 0; // This is used as index to ttMoves[]
- break;
-
- case PH_GOOD_CAPTURES:
- numOfMoves = generate_captures(pos, moves);
- score_captures();
- std::sort(moves, moves + numOfMoves);
- movesPicked = 0;
- break;
-
- case PH_KILLERS:
- movesPicked = 0; // This is used as index to killers[]
- break;
-
- case PH_NONCAPTURES:
- numOfMoves = generate_noncaptures(pos, moves);
- score_noncaptures();
- std::sort(moves, moves + numOfMoves);
- movesPicked = 0;
- break;
-
- 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);
- movesPicked = 0;
- break;
-
- case PH_EVASIONS:
- assert(pos.is_check());
- numOfMoves = generate_evasions(pos, moves, pinned);
- score_evasions();
- std::sort(moves, moves + numOfMoves);
- movesPicked = 0;
- break;
-
- case PH_QCAPTURES:
- numOfMoves = generate_captures(pos, moves);
- score_captures();
- std::sort(moves, moves + numOfMoves);
- movesPicked = 0;
- break;
-
- case PH_QCHECKS:
- // Perhaps we should order moves move here? FIXME
- numOfMoves = generate_non_capture_checks(pos, moves, dc);
- movesPicked = 0;
- break;
-
- case PH_STOP:
- return MOVE_NONE;
-
- default:
- assert(false);
- return MOVE_NONE;
- }
+ phase = RECAPTURES;
+ recaptureSquare = recaptureSq;
+ ttm = MOVE_NONE;
}
+
+ ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE);
+ phase += int(ttMove == MOVE_NONE);
+ go_next_phase();
}
+MovePicker::MovePicker(const Position& p, Move ttm, const History& h, PieceType parentCapture)
+ : pos(p), H(h) {
-/// 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.
+ assert (!pos.in_check());
-Move MovePicker::get_next_move(Lock &lock) {
+ // In ProbCut we consider only captures better than parent's move
+ captureThreshold = PieceValueMidgame[Piece(parentCapture)];
+ phase = PROBCUT;
- lock_grab(&lock);
- if (finished)
- {
- lock_release(&lock);
- return MOVE_NONE;
- }
- Move m = get_next_move();
- if (m == MOVE_NONE)
- finished = true;
+ if ( ttm != MOVE_NONE
+ && (!pos.is_capture(ttm) || pos.see(ttm) <= captureThreshold))
+ ttm = MOVE_NONE;
- lock_release(&lock);
- return m;
+ ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE);
+ phase += int(ttMove == MOVE_NONE);
+ go_next_phase();
}
-/// 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::go_next_phase() generates, scores and sorts the next bunch
+/// of moves when there are no more moves to try for the current phase.
+
+void MovePicker::go_next_phase() {
+
+ curMove = moves;
+
+ switch (++phase) {
+
+ case TT_MOVE_S1: case TT_MOVE_S2: case TT_MOVE_S3:
+ case TT_MOVE_S4: case TT_MOVE_S5: case TT_MOVE_S6:
+ lastMove = curMove + 1;
+ return;
+
+ case GOOD_CAPTURES_S1:
+ case GOOD_CAPTURES_S6:
+ lastMove = generate(pos, moves);
+ score_captures();
+ return;
+
+ case KILLERS_S1:
+ curMove = killers;
+ lastMove = curMove + 2;
+ return;
+
+ case NONCAPTURES_1_S1:
+ lastNonCapture = lastMove = generate(pos, moves);
+ score_noncaptures();
+ lastMove = std::partition(curMove, lastMove, has_positive_score);
+ sort(curMove, lastMove);
+ return;
+
+ case NONCAPTURES_2_S1:
+ curMove = lastMove;
+ lastMove = lastNonCapture;
+ if (depth >= 3 * ONE_PLY)
+ sort(curMove, lastMove);
+ return;
+
+ case BAD_CAPTURES_S1:
+ // Bad captures SEE value is already calculated so just pick
+ // them in order to get SEE move ordering.
+ curMove = badCaptures;
+ lastMove = moves + MAX_MOVES;
+ return;
+
+ case EVASIONS_S2:
+ assert(pos.in_check());
+ lastMove = generate(pos, moves);
+ score_evasions();
+ return;
+
+ case QCAPTURES_S3:
+ case QCAPTURES_S4:
+ lastMove = generate(pos, moves);
+ score_captures();
+ return;
+
+ case RECAPTURES_S5:
+ lastMove = generate(pos, moves);
+ return;
+
+ case QCHECKS_S3:
+ lastMove = generate(pos, moves);
+ return;
+
+ case STOP_S1: case STOP_S2: case STOP_S3:
+ case STOP_S4: case STOP_S5: case STOP_S6:
+ lastMove = curMove + 1; // Avoid another go_next_phase() call
+ return;
+
+ default:
+ assert(false);
+ }
+}
+
+
+/// 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 next_move().
void MovePicker::score_captures() {
// Winning and equal captures in the main search are ordered by MVV/LVA.
@@ -222,151 +242,151 @@ void MovePicker::score_captures() {
Move m;
// Use MVV/LVA ordering
- for (int i = 0; i < numOfMoves; i++)
+ for (MoveStack* cur = moves; cur != lastMove; cur++)
{
- m = moves[i].move;
- if (move_is_promotion(m))
- moves[i].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)));
+ m = cur->move;
+ cur->score = PieceValueMidgame[pos.piece_on(to_sq(m))]
+ - type_of(pos.piece_moved(m));
+
+ if (is_promotion(m))
+ cur->score += PieceValueMidgame[Piece(promotion_piece_type(m))];
}
}
void MovePicker::score_noncaptures() {
- // 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.
- Piece piece;
- Square from, to;
- int hs;
-
- for (int i = 0; i < numOfMoves; i++)
- {
- from = move_from(moves[i].move);
- to = move_to(moves[i].move);
- piece = pos.piece_on(from);
- hs = H.move_ordering_score(piece, to);
- // Ensure history is always preferred to pst
- if (hs > 0)
- hs += 1000;
+ Move m;
+ Square from;
- // pst based scoring
- moves[i].score = hs + pos.pst_delta(piece, from, to);
+ for (MoveStack* cur = moves; cur != lastMove; cur++)
+ {
+ m = cur->move;
+ from = from_sq(m);
+ cur->score = H.value(pos.piece_on(from), to_sq(m));
}
}
void MovePicker::score_evasions() {
+ // 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;
- for (int i = 0; i < numOfMoves; i++)
+ // Skip if we don't have at least two moves to order
+ if (lastMove < moves + 2)
+ return;
+
+ 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 - History::MaxValue; // Be sure we are at the bottom
+ else if (pos.is_capture(m))
+ cur->score = PieceValueMidgame[pos.piece_on(to_sq(m))]
+ - type_of(pos.piece_moved(m)) + History::MaxValue;
+ else
+ cur->score = H.value(pos.piece_moved(m), to_sq(m));
}
}
+/// MovePicker::next_move() is the most important method of the MovePicker class.
+/// It returns a new pseudo 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 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.
-/// MovePicker::pick_move_from_list() picks the move with the biggest score
-/// from a list of generated moves (moves[] or badCaptures[], depending on
-/// the current move generation phase). It takes care not to return the
-/// transposition table move if that has already been serched previously.
+Move MovePicker::next_move() {
-Move MovePicker::pick_move_from_list() {
+ Move move;
- assert(movesPicked >= 0);
- assert(!pos.is_check() || *phasePtr == PH_EVASIONS || *phasePtr == PH_STOP);
- assert( pos.is_check() || *phasePtr != PH_EVASIONS);
+ while (true)
+ {
+ while (curMove == lastMove)
+ go_next_phase();
- switch (*phasePtr) {
+ switch (phase) {
- 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 TT_MOVE_S1: case TT_MOVE_S2: case TT_MOVE_S3:
+ case TT_MOVE_S4: case TT_MOVE_S5: case TT_MOVE_S6:
+ curMove++;
+ return ttMove;
+ break;
- case PH_GOOD_CAPTURES:
- while (movesPicked < numOfMoves)
- {
- Move move = moves[movesPicked++].move;
- if ( move != ttMoves[0]
- && move != ttMoves[1]
- && pos.pl_move_is_legal(move, pinned))
+ case GOOD_CAPTURES_S1:
+ move = pick_best(curMove++, lastMove)->move;
+ if (move != ttMove)
{
+ assert(captureThreshold <= 0); // Otherwise we must use see instead of see_sign
+
// Check for a non negative SEE now
int seeValue = pos.see_sign(move);
- if (seeValue >= 0)
+ if (seeValue >= captureThreshold)
return move;
- // 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;
+ // Losing capture, move it to the tail of the array
+ (--badCaptures)->move = move;
+ badCaptures->score = seeValue;
}
- }
- 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]
- && pos.pl_move_is_legal(move, pinned))
+ break;
+
+ case GOOD_CAPTURES_S6:
+ move = pick_best(curMove++, lastMove)->move;
+ if ( move != ttMove
+ && pos.see(move) > captureThreshold)
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]
- && pos.pl_move_is_legal(move, pinned))
+ break;
+
+ case KILLERS_S1:
+ move = (curMove++)->move;
+ if ( move != MOVE_NONE
+ && pos.is_pseudo_legal(move)
+ && move != ttMove
+ && !pos.is_capture(move))
return move;
- }
- break;
+ break;
+
+ case NONCAPTURES_1_S1:
+ case NONCAPTURES_2_S1:
+ move = (curMove++)->move;
+ if ( move != ttMove
+ && move != killers[0].move
+ && move != killers[1].move)
+ return move;
+ break;
- default:
- break;
+ case BAD_CAPTURES_S1:
+ move = pick_best(curMove++, lastMove)->move;
+ return move;
+
+ case EVASIONS_S2:
+ case QCAPTURES_S3:
+ case QCAPTURES_S4:
+ move = pick_best(curMove++, lastMove)->move;
+ if (move != ttMove)
+ return move;
+ break;
+
+ case RECAPTURES_S5:
+ move = (curMove++)->move;
+ if (to_sq(move) == recaptureSquare)
+ return move;
+ break;
+
+ case QCHECKS_S3:
+ move = (curMove++)->move;
+ if (move != ttMove)
+ return move;
+ break;
+
+ case STOP_S1: case STOP_S2: case STOP_S3:
+ case STOP_S4: case STOP_S5: case STOP_S6:
+ return MOVE_NONE;
+
+ default:
+ assert(false);
+ }
}
- return MOVE_NONE;
}