X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fmovepick.cpp;h=9002c64c41b09b0944a7cc634721b28a805bacdc;hb=d5ba8e827d840995e79435986a8a7a2a45626eca;hp=6b7483eb99c0a782f529b71cbb950e8aaa7a791a;hpb=e9de96f0e417dc706882b645d14dbf41e7ccc467;p=stockfish
diff --git a/src/movepick.cpp b/src/movepick.cpp
index 6b7483eb..9002c64c 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) 2008-2009 Marco Costalba
+ 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
@@ -18,341 +18,301 @@
along with this program. If not, see .
*/
-
-////
-//// Includes
-////
-
-#include
#include
-#include "history.h"
-#include "movegen.h"
#include "movepick.h"
-#include "search.h"
-#include "value.h"
-
-
-////
-//// Local definitions
-////
+#include "thread.h"
namespace {
- CACHE_LINE_ALIGNMENT
- const MovegenPhaseT MainSearchPhaseTable[] = { PH_TT_MOVES, PH_GOOD_CAPTURES, 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};
-}
+ enum Stages {
+ MAIN_SEARCH, GOOD_CAPTURES, KILLERS, GOOD_QUIETS, BAD_QUIETS, BAD_CAPTURES,
+ EVASION, ALL_EVASIONS,
+ QSEARCH_WITH_CHECKS, QCAPTURES_1, CHECKS,
+ QSEARCH_WITHOUT_CHECKS, QCAPTURES_2,
+ PROBCUT, PROBCUT_CAPTURES,
+ RECAPTURE, RECAPTURES,
+ STOP
+ };
+
+ // 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;
+ }
+ }
+ // 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(*begin, *std::max_element(begin, end));
+ return *begin;
+ }
-////
-//// Functions
-////
+} // namespace
-/// 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
+/// Constructors of 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.
+/// 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 HistoryStats& h,
+ const CounterMoveStats& cmh, Move cm, Search::Stack* s)
+ : pos(p), history(h), counterMoveHistory(&cmh), ss(s), countermove(cm), depth(d) {
+
+ assert(d > DEPTH_ZERO);
+
+ stage = pos.checkers() ? EVASION : MAIN_SEARCH;
+ ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE;
+ endMoves += (ttMove != MOVE_NONE);
+}
MovePicker::MovePicker(const Position& p, Move ttm, Depth d,
- const History& h, SearchStack* ss) : pos(p), H(h) {
- ttMoves[0].move = ttm;
- if (ss)
- {
- ttMoves[1].move = (ss->mateKiller == ttm)? MOVE_NONE : ss->mateKiller;
- killers[0].move = ss->killers[0];
- killers[1].move = ss->killers[1];
- } else
- ttMoves[1].move = killers[0].move = killers[1].move = MOVE_NONE;
-
- finished = false;
- numOfBadCaptures = 0;
-
- Color us = pos.side_to_move();
-
- dc = p.discovered_check_candidates(us);
- pinned = p.pinned_pieces(us);
-
- if (p.is_check())
- phasePtr = EvasionsPhaseTable;
- else if (d > Depth(0))
- phasePtr = MainSearchPhaseTable;
- else if (d == Depth(0))
- phasePtr = QsearchWithChecksPhaseTable;
+ const HistoryStats& h, Square s)
+ : pos(p), history(h), counterMoveHistory(nullptr) {
+
+ assert(d <= DEPTH_ZERO);
+
+ if (pos.checkers())
+ stage = EVASION;
+
+ else if (d > DEPTH_QS_NO_CHECKS)
+ stage = QSEARCH_WITH_CHECKS;
+
+ else if (d > DEPTH_QS_RECAPTURES)
+ stage = QSEARCH_WITHOUT_CHECKS;
+
else
- phasePtr = QsearchWithoutChecksPhaseTable;
+ {
+ stage = RECAPTURE;
+ recaptureSquare = s;
+ ttm = MOVE_NONE;
+ }
- phasePtr--;
- go_next_phase();
+ ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE;
+ endMoves += (ttMove != MOVE_NONE);
}
+MovePicker::MovePicker(const Position& p, Move ttm, const HistoryStats& h, Value th)
+ : pos(p), history(h), counterMoveHistory(nullptr), threshold(th) {
-/// 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;
- phase = *(++phasePtr);
- switch (phase) {
-
- case PH_TT_MOVES:
- curMove = ttMoves;
- lastMove = curMove + 2;
- return;
-
- case PH_GOOD_CAPTURES:
- lastMove = generate_captures(pos, moves);
- score_captures();
- std::sort(moves, lastMove);
- return;
-
- case PH_KILLERS:
- curMove = killers;
- lastMove = curMove + 2;
- return;
-
- case PH_NONCAPTURES:
- lastMove = generate_noncaptures(pos, moves);
- score_noncaptures();
- std::sort(moves, lastMove);
- return;
-
- case PH_BAD_CAPTURES:
- // Bad captures SEE value is already calculated so just sort them
- // to get SEE move ordering.
- curMove = badCaptures;
- lastMove = badCaptures + numOfBadCaptures;
- std::sort(badCaptures, lastMove);
- return;
-
- case PH_EVASIONS:
- assert(pos.is_check());
- lastMove = generate_evasions(pos, moves, pinned);
- score_evasions();
- std::sort(moves, lastMove);
- return;
-
- case PH_QCAPTURES:
- lastMove = generate_captures(pos, moves);
- score_captures();
- std::sort(moves, lastMove);
- return;
-
- case PH_QCHECKS:
- // Perhaps we should order moves move here? FIXME
- lastMove = generate_non_capture_checks(pos, moves, dc);
- return;
-
- case PH_STOP:
- return;
+ assert(!pos.checkers());
- default:
- assert(false);
- return;
- }
+ stage = PROBCUT;
+
+ // In ProbCut we generate captures with SEE higher than the given threshold
+ ttMove = ttm
+ && pos.pseudo_legal(ttm)
+ && pos.capture(ttm)
+ && pos.see(ttm) > threshold ? ttm : MOVE_NONE;
+
+ endMoves += (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 get_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;
-
- // Use MVV/LVA ordering
- for (MoveStack* cur = moves; cur != lastMove; cur++)
- {
- m = cur->move;
- if (move_is_promotion(m))
- cur->score = QueenValueMidgame;
- else
- cur->score = int(pos.midgame_value_of_piece_on(move_to(m)))
- -int(pos.type_of_piece_on(move_from(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() {
- // 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;
+template<>
+void MovePicker::score() {
- for (MoveStack* cur = moves; cur != lastMove; cur++)
- {
- 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
- cur->score = hs + pos.pst_delta(piece, from, to);
- }
+ for (auto& m : *this)
+ m.value = history[pos.moved_piece(m)][to_sq(m)]
+ + (*counterMoveHistory)[pos.moved_piece(m)][to_sq(m)];
}
-void MovePicker::score_evasions() {
+template<>
+void MovePicker::score() {
+ // Try winning and equal captures ordered by MVV/LVA, then non-captures ordered
+ // by history value, then bad captures and quiet moves with a negative SEE ordered
+ // by SEE value.
+ Value see;
- Move m;
+ for (auto& m : *this)
+ if ((see = pos.see_sign(m)) < VALUE_ZERO)
+ m.value = see - HistoryStats::Max; // At the bottom
- for (MoveStack* cur = moves; cur != lastMove; cur++)
- {
- m = cur->move;
- if (m == ttMoves[0].move)
- cur->score = 2 * HistoryMax;
- else if (!pos.square_is_empty(move_to(m)))
- {
- int seeScore = pos.see(m);
- cur->score = seeScore + (seeScore >= 0 ? HistoryMax : 0);
- } else
- cur->score = H.move_ordering_score(pos.piece_on(move_from(m)), move_to(m));
+ else 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)];
+}
+
+
+/// generate_next_stage() generates, scores, and sorts the next bunch of moves
+/// when there are no more moves to try for the current stage.
+
+void MovePicker::generate_next_stage() {
+
+ assert(stage != STOP);
+
+ cur = moves;
+
+ switch (++stage) {
+
+ case GOOD_CAPTURES: case QCAPTURES_1: case QCAPTURES_2:
+ case PROBCUT_CAPTURES: case RECAPTURES:
+ endMoves = generate(pos, moves);
+ score();
+ break;
+
+ case KILLERS:
+ killers[0] = ss->killers[0];
+ killers[1] = ss->killers[1];
+ killers[2] = countermove;
+ cur = killers;
+ endMoves = cur + 2 + (countermove != killers[0] && countermove != killers[1]);
+ break;
+
+ case GOOD_QUIETS:
+ endQuiets = endMoves = generate(pos, moves);
+ score();
+ endMoves = std::partition(cur, endMoves, [](const ExtMove& m) { return m.value > VALUE_ZERO; });
+ insertion_sort(cur, endMoves);
+ break;
+
+ case BAD_QUIETS:
+ cur = endMoves;
+ endMoves = endQuiets;
+ if (depth >= 3 * ONE_PLY)
+ insertion_sort(cur, endMoves);
+ break;
+
+ case BAD_CAPTURES:
+ // Just pick them in reverse order to get correct ordering
+ cur = moves + MAX_MOVES - 1;
+ endMoves = endBadCaptures;
+ break;
+
+ case ALL_EVASIONS:
+ endMoves = generate(pos, moves);
+ if (endMoves - moves > 1)
+ score();
+ break;
+
+ case CHECKS:
+ endMoves = generate(pos, moves);
+ break;
+
+ case EVASION: case QSEARCH_WITH_CHECKS: case QSEARCH_WITHOUT_CHECKS:
+ case PROBCUT: case RECAPTURE: case STOP:
+ stage = STOP;
+ break;
+
+ default:
+ assert(false);
}
}
-/// 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.
-/// 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.
-Move MovePicker::get_next_move() {
+/// 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() {
- assert(!pos.is_check() || *phasePtr == PH_EVASIONS || *phasePtr == PH_STOP);
- assert( pos.is_check() || *phasePtr != PH_EVASIONS);
+ Move move;
while (true)
{
- switch (phase) {
+ while (cur == endMoves && stage != STOP)
+ generate_next_stage();
- case PH_TT_MOVES:
- while (curMove != lastMove)
+ switch (stage) {
+
+ case MAIN_SEARCH: case EVASION: case QSEARCH_WITH_CHECKS:
+ case QSEARCH_WITHOUT_CHECKS: case PROBCUT:
+ ++cur;
+ return ttMove;
+
+ case GOOD_CAPTURES:
+ move = pick_best(cur++, endMoves);
+ if (move != ttMove)
{
- Move move = (curMove++)->move;
- if ( move != MOVE_NONE
- && move_is_legal(pos, move, pinned))
+ if (pos.see_sign(move) >= VALUE_ZERO)
return move;
+
+ // Losing capture, move it to the tail of the array
+ *endBadCaptures-- = move;
}
break;
- case PH_GOOD_CAPTURES:
- while (curMove != lastMove)
- {
- Move move = (curMove++)->move;
- if ( move != ttMoves[0].move
- && move != ttMoves[1].move
- && pos.pl_move_is_legal(move, pinned))
- {
- // Check for a non negative SEE now
- int seeValue = pos.see_sign(move);
- if (seeValue >= 0)
- 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;
- }
- }
+ case KILLERS:
+ move = *cur++;
+ if ( move != MOVE_NONE
+ && move != ttMove
+ && pos.pseudo_legal(move)
+ && !pos.capture(move))
+ return move;
break;
- case PH_KILLERS:
- while (curMove != lastMove)
- {
- Move 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;
- }
+ case GOOD_QUIETS: case BAD_QUIETS:
+ move = *cur++;
+ if ( move != ttMove
+ && move != killers[0]
+ && move != killers[1]
+ && move != killers[2])
+ return move;
break;
- case PH_NONCAPTURES:
- while (curMove != lastMove)
- {
- Move 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;
- }
+ case BAD_CAPTURES:
+ return *cur--;
+
+ case ALL_EVASIONS: case QCAPTURES_1: case QCAPTURES_2:
+ move = pick_best(cur++, endMoves);
+ if (move != ttMove)
+ return move;
break;
- case PH_EVASIONS:
- case PH_BAD_CAPTURES:
- if (curMove != lastMove)
- return (curMove++)->move;
+ case PROBCUT_CAPTURES:
+ move = pick_best(cur++, endMoves);
+ if (move != ttMove && pos.see(move) > threshold)
+ return move;
+ break;
+
+ case RECAPTURES:
+ move = pick_best(cur++, endMoves);
+ if (to_sq(move) == recaptureSquare)
+ return move;
break;
- case PH_QCAPTURES:
- case PH_QCHECKS:
- while (curMove != lastMove)
- {
- Move move = (curMove++)->move;
- // Maybe postpone the legality check until after futility pruning?
- if ( move != ttMoves[0].move
- && pos.pl_move_is_legal(move, pinned))
- return move;
- }
+ case CHECKS:
+ move = *cur++;
+ if (move != ttMove)
+ return move;
break;
- case PH_STOP:
+ case STOP:
return MOVE_NONE;
default:
assert(false);
- break;
}
- go_next_phase();
}
}
-
-/// 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;
-}