X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=5c8338c0c19ab96d08f55879015d8f422002985c;hp=1b84f14ee83614ca1995e78b50f38d5e94ce8054;hb=6b16ebc82566a69b9336cca6aa7a19ab1824b85d;hpb=ec9b037e5f318c9a3af05d0fcc24d5d99891cd99
diff --git a/src/movepick.cpp b/src/movepick.cpp
index 1b84f14e..34d29562 100644
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -1,14 +1,14 @@
/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, 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
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
-
Stockfish is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
@@ -18,354 +18,333 @@
along with this program. If not, see .
*/
-#include
#include
-#include "movegen.h"
#include "movepick.h"
+#include "thread.h"
namespace {
- enum Sequencer {
- MAIN_SEARCH, TT_MOVE_S1, CAPTURES_S1, KILLERS_S1, QUIETS_1_S1,
- QUIETS_2_S1, BAD_CAPTURES_S1, STOP_S1,
- EVASIONS, TT_MOVE_S2, EVASIONS_S2, STOP_S2,
- CAPTURES_AND_CHECKS, TT_MOVE_S3, CAPTURES_S3, QUIET_CHECKS_S3, STOP_S3,
- CAPTURES, TT_MOVE_S4, CAPTURES_S4, STOP_S4,
- PROBCUT, TT_MOVE_S5, CAPTURES_S5, STOP_S5,
- RECAPTURES, CAPTURES_S6, STOP_S6
+ enum Stages {
+ MAIN_SEARCH, CAPTURES_INIT, GOOD_CAPTURES, KILLERS, COUNTERMOVE, QUIET_INIT, QUIET, BAD_CAPTURES,
+ EVASION, EVASIONS_INIT, ALL_EVASIONS,
+ PROBCUT, PROBCUT_INIT, PROBCUT_CAPTURES,
+ QSEARCH_WITH_CHECKS, QCAPTURES_1_INIT, QCAPTURES_1, QCHECKS,
+ QSEARCH_NO_CHECKS, QCAPTURES_2_INIT, QCAPTURES_2,
+ QSEARCH_RECAPTURES, QRECAPTURES
};
- // 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; }
+ // Our insertion sort, which is guaranteed to be stable, as it should be
+ void insertion_sort(ExtMove* begin, ExtMove* end)
+ {
+ ExtMove tmp, *p, *q;
+
+ for (p = begin + 1; p < end; ++p)
+ {
+ tmp = *p;
+ for (q = p; q != begin && *(q-1) < tmp; --q)
+ *q = *(q-1);
+ *q = tmp;
+ }
+ }
- // Picks and moves to the front the best move in the 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)
+ // pick_best() finds the best move in the range (begin, end) and moves it to
+ // the front. It's faster than sorting all the moves in advance when there
+ // are few moves, e.g., the possible captures.
+ Move pick_best(ExtMove* begin, ExtMove* end)
{
- std::swap(*firstMove, *std::max_element(firstMove, lastMove));
- return firstMove;
+ std::swap(*begin, *std::max_element(begin, end));
+ return *begin;
}
-}
+
+} // namespace
/// Constructors of the MovePicker class. As arguments we pass information
-/// to help it to return the presumably good moves first, to decide which
+/// 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.
+/// search captures, promotions, and some checks) and how important good move
+/// ordering is at the current node.
-MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h,
- Search::Stack* ss, Value beta) : pos(p), H(h), depth(d) {
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, Search::Stack* s)
+ : pos(p), ss(s), depth(d) {
assert(d > DEPTH_ZERO);
- captureThreshold = 0;
- curMove = lastMove = 0;
- badCaptures = moves + MAX_MOVES;
-
- if (p.in_check())
- phase = EVASIONS;
+ Square prevSq = to_sq((ss-1)->currentMove);
+ countermove = pos.this_thread()->counterMoves[pos.piece_on(prevSq)][prevSq];
- else
- {
- 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;
-
- // Consider negative captures as good if still enough to reach beta
- else if (ss && ss->eval > beta)
- captureThreshold = beta - ss->eval;
-
- phase = MAIN_SEARCH;
- }
-
- ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE);
- phase += (ttMove == MOVE_NONE);
+ stage = pos.checkers() ? EVASION : MAIN_SEARCH;
+ ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE;
+ stage += (ttMove == MOVE_NONE);
}
-MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h,
- Square sq) : pos(p), H(h), curMove(0), lastMove(0) {
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, Square s)
+ : pos(p) {
assert(d <= DEPTH_ZERO);
- if (p.in_check())
- phase = EVASIONS;
+ if (pos.checkers())
+ stage = EVASION;
- else if (d >= DEPTH_QS_CHECKS)
- phase = CAPTURES_AND_CHECKS;
+ else if (d > DEPTH_QS_NO_CHECKS)
+ stage = QSEARCH_WITH_CHECKS;
- else if (d >= DEPTH_QS_RECAPTURES)
- {
- phase = CAPTURES;
+ else if (d > DEPTH_QS_RECAPTURES)
+ stage = QSEARCH_NO_CHECKS;
- // 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 && !pos.is_capture_or_promotion(ttm))
- ttm = MOVE_NONE;
- }
else
{
- phase = RECAPTURES - 1;
- recaptureSquare = sq;
- ttm = MOVE_NONE;
+ stage = QSEARCH_RECAPTURES;
+ recaptureSquare = s;
+ return;
}
- ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE);
- phase += (ttMove == MOVE_NONE);
+ ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE;
+ stage += (ttMove == MOVE_NONE);
}
-MovePicker::MovePicker(const Position& p, Move ttm, const History& h,
- PieceType parentCapture) : pos(p), H(h) {
+MovePicker::MovePicker(const Position& p, Move ttm, Value th)
+ : pos(p), threshold(th) {
- assert (!pos.in_check());
+ assert(!pos.checkers());
- // In ProbCut we consider only captures better than parent's move
- captureThreshold = PieceValueMidgame[Piece(parentCapture)];
- curMove = lastMove = 0;
- phase = PROBCUT;
+ stage = PROBCUT;
- if ( ttm != MOVE_NONE
- && (!pos.is_capture(ttm) || pos.see(ttm) <= captureThreshold))
- ttm = MOVE_NONE;
+ // In ProbCut we generate captures with SEE higher than or equal to the given threshold
+ ttMove = ttm
+ && pos.pseudo_legal(ttm)
+ && pos.capture(ttm)
+ && pos.see_ge(ttm, threshold)? ttm : MOVE_NONE;
- ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE);
- phase += (ttMove == MOVE_NONE);
+ stage += (ttMove == MOVE_NONE);
}
-/// 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.
- // Suprisingly, this appears to perform slightly better than SEE based
- // move ordering. The reason is probably that in a position with a winning
- // capture, capturing a more valuable (but sufficiently defended) piece
- // first usually doesn't hurt. The opponent will have to recapture, and
- // the hanging piece will still be hanging (except in the unusual cases
- // where it is possible to recapture with the hanging piece). Exchanging
- // big pieces before capturing a hanging piece probably helps to reduce
- // the subtree size.
- // In main search we want to push captures with negative SEE values to
- // badCaptures[] array, but instead of doing it now we delay till when
- // the move has been picked up in pick_move_from_list(), this way we save
- // some SEE calls in case we get a cutoff (idea from Pablo Vazquez).
- Move m;
-
- for (MoveStack* cur = moves; cur != lastMove; cur++)
- {
- 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))];
- }
+/// score() assigns a numerical value to each move in a move list. The moves with
+/// highest values will be picked first.
+template<>
+void MovePicker::score() {
+ // Winning and equal captures in the main search are ordered by MVV, preferring
+ // captures near our home rank. Surprisingly, this appears to perform slightly
+ // better than SEE-based move ordering: exchanging big pieces before capturing
+ // a hanging piece probably helps to reduce the subtree size.
+ // In the main search we want to push captures with negative SEE values to the
+ // badCaptures[] array, but instead of doing it now we delay until the move
+ // has been picked up, saving some SEE calls in case we get a cutoff.
+ for (auto& m : *this)
+ m.value = PieceValue[MG][pos.piece_on(to_sq(m))]
+ - Value(200 * relative_rank(pos.side_to_move(), to_sq(m)));
}
-void MovePicker::score_noncaptures() {
+template<>
+void MovePicker::score() {
- Move m;
- Square from;
+ const HistoryStats& history = pos.this_thread()->history;
+ const FromToStats& fromTo = pos.this_thread()->fromTo;
- 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));
- }
-}
+ const CounterMoveStats* cmh = (ss-1)->counterMoves;
+ const CounterMoveStats* fmh = (ss-2)->counterMoves;
+ const CounterMoveStats* fmh2 = (ss-4)->counterMoves;
-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, then bad-captures and quiet
- // moves with a negative SEE. This last group is ordered by the SEE score.
- Move m;
- int seeScore;
+ Color c = pos.side_to_move();
- if (lastMove < moves + 2)
- return;
-
- for (MoveStack* cur = moves; cur != lastMove; cur++)
- {
- 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));
- }
+ for (auto& m : *this)
+ m.value = history[pos.moved_piece(m)][to_sq(m)]
+ + (cmh ? (*cmh)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO)
+ + (fmh ? (*fmh)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO)
+ + (fmh2 ? (*fmh2)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO)
+ + fromTo.get(c, m);
}
-
-/// MovePicker::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::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:
- lastMove = curMove + 1;
- return;
-
- case CAPTURES_S1: case CAPTURES_S3: case CAPTURES_S4:
- case CAPTURES_S5: case CAPTURES_S6:
- lastMove = generate(pos, moves);
- score_captures();
- return;
-
- case KILLERS_S1:
- curMove = killers;
- lastMove = curMove + 2;
- return;
-
- case QUIETS_1_S1:
- lastQuiet = lastMove = generate(pos, moves);
- score_noncaptures();
- lastMove = std::partition(curMove, lastMove, has_positive_score);
- sort(curMove, lastMove);
- return;
-
- case QUIETS_2_S1:
- curMove = lastMove;
- lastMove = lastQuiet;
- 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 QUIET_CHECKS_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 next_phase() call
- return;
-
- default:
- assert(false);
- }
+template<>
+void MovePicker::score() {
+ // Try captures ordered by MVV/LVA, then non-captures ordered by history value
+ const HistoryStats& history = pos.this_thread()->history;
+ const FromToStats& fromTo = pos.this_thread()->fromTo;
+ Color c = pos.side_to_move();
+
+ for (auto& m : *this)
+ if (pos.capture(m))
+ m.value = PieceValue[MG][pos.piece_on(to_sq(m))]
+ - Value(type_of(pos.moved_piece(m))) + HistoryStats::Max;
+ else
+ m.value = history[pos.moved_piece(m)][to_sq(m)] + fromTo.get(c, 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.
+/// 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 value from a list of generated moves
+/// taking care not to return the ttMove if it has already been searched.
Move MovePicker::next_move() {
Move move;
- while (true)
- {
- while (curMove == lastMove)
- next_phase();
+ switch (stage) {
- switch (phase) {
+ case MAIN_SEARCH: case EVASION: case QSEARCH_WITH_CHECKS:
+ case QSEARCH_NO_CHECKS: case PROBCUT:
+ ++stage;
+ return ttMove;
- case TT_MOVE_S1: case TT_MOVE_S2: case TT_MOVE_S3: case TT_MOVE_S4: case TT_MOVE_S5:
- curMove++;
- return ttMove;
- break;
+ case CAPTURES_INIT:
+ endBadCaptures = cur = moves;
+ endMoves = generate(pos, cur);
+ score();
+ ++stage;
- case CAPTURES_S1:
- move = pick_best(curMove++, lastMove)->move;
+ case GOOD_CAPTURES:
+ while (cur < endMoves)
+ {
+ move = pick_best(cur++, endMoves);
if (move != ttMove)
{
- assert(captureThreshold <= 0); // Otherwise we cannot use see_sign()
-
- int seeScore = pos.see_sign(move);
- if (seeScore >= captureThreshold)
+ if (pos.see_ge(move, VALUE_ZERO))
return move;
- // Losing capture, move it to the tail of the array
- (--badCaptures)->move = move;
- badCaptures->score = seeScore;
+ // Losing capture, move it to the beginning of the array
+ *endBadCaptures++ = move;
}
- 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;
+ ++stage;
+ move = ss->killers[0]; // First killer move
+ if ( move != MOVE_NONE
+ && move != ttMove
+ && pos.pseudo_legal(move)
+ && !pos.capture(move))
+ return move;
- case QUIETS_1_S1:
- case QUIETS_2_S1:
- move = (curMove++)->move;
- if ( move != ttMove
- && move != killers[0].move
- && move != killers[1].move)
- return move;
- break;
+ case KILLERS:
+ ++stage;
+ move = ss->killers[1]; // Second killer move
+ if ( move != MOVE_NONE
+ && move != ttMove
+ && pos.pseudo_legal(move)
+ && !pos.capture(move))
+ return move;
- case BAD_CAPTURES_S1:
- move = pick_best(curMove++, lastMove)->move;
+ case COUNTERMOVE:
+ ++stage;
+ move = countermove;
+ if ( move != MOVE_NONE
+ && move != ttMove
+ && move != ss->killers[0]
+ && move != ss->killers[1]
+ && pos.pseudo_legal(move)
+ && !pos.capture(move))
return move;
- case EVASIONS_S2:
- case CAPTURES_S3: case CAPTURES_S4:
- move = pick_best(curMove++, lastMove)->move;
+ case QUIET_INIT:
+ cur = endBadCaptures;
+ endMoves = generate(pos, cur);
+ score();
+ if (depth < 3 * ONE_PLY)
+ {
+ ExtMove* goodQuiet = std::partition(cur, endMoves, [](const ExtMove& m)
+ { return m.value > VALUE_ZERO; });
+ insertion_sort(cur, goodQuiet);
+ } else
+ insertion_sort(cur, endMoves);
+ ++stage;
+
+ case QUIET:
+ while (cur < endMoves)
+ {
+ move = *cur++;
+ if ( move != ttMove
+ && move != ss->killers[0]
+ && move != ss->killers[1]
+ && move != countermove)
+ return move;
+ }
+ ++stage;
+ cur = moves; // Point to beginning of bad captures
+
+ case BAD_CAPTURES:
+ if (cur < endBadCaptures)
+ return *cur++;
+ break;
+
+ case EVASIONS_INIT:
+ cur = moves;
+ endMoves = generate(pos, cur);
+ score();
+ ++stage;
+
+ case ALL_EVASIONS:
+ while (cur < endMoves)
+ {
+ move = pick_best(cur++, endMoves);
if (move != ttMove)
return move;
- break;
-
- case CAPTURES_S5:
- move = pick_best(curMove++, lastMove)->move;
- if ( move != ttMove
- && pos.see(move) > captureThreshold)
- return move;
- break;
-
- case CAPTURES_S6:
- move = pick_best(curMove++, lastMove)->move;
- if (to_sq(move) == recaptureSquare)
+ }
+ break;
+
+ case PROBCUT_INIT:
+ cur = moves;
+ endMoves = generate(pos, cur);
+ score();
+ ++stage;
+
+ case PROBCUT_CAPTURES:
+ while (cur < endMoves)
+ {
+ move = pick_best(cur++, endMoves);
+ if ( move != ttMove
+ && pos.see_ge(move, threshold))
return move;
- break;
-
- case QUIET_CHECKS_S3:
- move = (curMove++)->move;
+ }
+ break;
+
+ case QCAPTURES_1_INIT: case QCAPTURES_2_INIT:
+ cur = moves;
+ endMoves = generate(pos, cur);
+ score();
+ ++stage;
+
+ case QCAPTURES_1: case QCAPTURES_2:
+ while (cur < endMoves)
+ {
+ move = pick_best(cur++, endMoves);
if (move != ttMove)
return move;
+ }
+ if (stage == QCAPTURES_2)
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);
+ cur = moves;
+ endMoves = generate(pos, cur);
+ ++stage;
+
+ case QCHECKS:
+ while (cur < endMoves)
+ {
+ move = cur++->move;
+ if (move != ttMove)
+ return move;
}
+ break;
+
+ case QSEARCH_RECAPTURES:
+ cur = moves;
+ endMoves = generate(pos, cur);
+ score();
+ ++stage;
+
+ case QRECAPTURES:
+ while (cur < endMoves)
+ {
+ move = pick_best(cur++, endMoves);
+ if (to_sq(move) == recaptureSquare)
+ return move;
+ }
+ break;
+
+ default:
+ assert(false);
}
+
+ return MOVE_NONE;
}