X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fmovepick.cpp;h=9cb8447f77840a410950780854d857f62d0db473;hb=5f222f1d98c9b4cb07aa2303f085c2064e7ea77a;hp=34cb642b4a514b60c12a0cf6d4d62beb235dc084;hpb=4dd7fccfd18a809cf1e3b589c2ec77f4b386dad6;p=stockfish
diff --git a/src/movepick.cpp b/src/movepick.cpp
index 34cb642b..9cb8447f 100644
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -1,14 +1,12 @@
/*
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) 2004-2021 The Stockfish developers (see AUTHORS file)
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 +16,250 @@
along with this program. If not, see .
*/
-
-////
-//// Includes
-////
-
#include
-#include "history.h"
-#include "movegen.h"
#include "movepick.h"
-#include "search.h"
-#include "value.h"
-
-
-////
-//// Local definitions
-////
namespace {
- 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
+ enum Stages {
+ MAIN_TT, CAPTURE_INIT, GOOD_CAPTURE, REFUTATION, QUIET_INIT, QUIET, BAD_CAPTURE,
+ EVASION_TT, EVASION_INIT, EVASION,
+ PROBCUT_TT, PROBCUT_INIT, PROBCUT,
+ QSEARCH_TT, QCAPTURE_INIT, QCAPTURE, QCHECK_INIT, QCHECK
};
- CACHE_LINE_ALIGNMENT
- const uint8_t MainSearchPhaseTable[] = { PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP};
- const uint8_t EvasionsPhaseTable[] = { 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};
-}
-
+ // partial_insertion_sort() sorts moves in descending order up to and including
+ // a given limit. The order of moves smaller than the limit is left unspecified.
+ void partial_insertion_sort(ExtMove* begin, ExtMove* end, int limit) {
+
+ for (ExtMove *sortedEnd = begin, *p = begin + 1; p < end; ++p)
+ if (p->value >= limit)
+ {
+ ExtMove tmp = *p, *q;
+ *p = *++sortedEnd;
+ for (q = sortedEnd; q != begin && *(q - 1) < tmp; --q)
+ *q = *(q - 1);
+ *q = tmp;
+ }
+ }
-////
-//// 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 History& h, SearchStack* ss) : pos(p), H(h) {
- int searchTT = ttm;
- ttMoves[0].move = ttm;
- finished = false;
- lastBadCapture = badCaptures;
+/// MovePicker constructor for the main search
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh, const LowPlyHistory* lp,
+ const CapturePieceToHistory* cph, const PieceToHistory** ch, Move cm, const Move* killers, int pl)
+ : pos(p), mainHistory(mh), lowPlyHistory(lp), captureHistory(cph), continuationHistory(ch),
+ ttMove(ttm), refutations{{killers[0], 0}, {killers[1], 0}, {cm, 0}}, depth(d), ply(pl) {
- if (ss)
- {
- 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;
-
- 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 + !searchTT;
- else if (d == Depth(0))
- phasePtr = QsearchWithChecksPhaseTable + !searchTT;
- else
- phasePtr = QsearchWithoutChecksPhaseTable + !searchTT;
-
- phasePtr--;
- go_next_phase();
+ assert(d > 0);
+
+ stage = (pos.checkers() ? EVASION_TT : MAIN_TT) +
+ !(ttm && pos.pseudo_legal(ttm));
}
+/// MovePicker constructor for quiescence search
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh,
+ const CapturePieceToHistory* cph, const PieceToHistory** ch, Square rs)
+ : pos(p), mainHistory(mh), captureHistory(cph), continuationHistory(ch), ttMove(ttm), recaptureSquare(rs), depth(d) {
-/// 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();
- sort_moves(moves, lastMove);
- return;
-
- case PH_KILLERS:
- curMove = killers;
- lastMove = curMove + 2;
- return;
-
- case PH_NONCAPTURES:
- lastMove = generate_noncaptures(pos, moves);
- score_noncaptures();
- 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.
- curMove = badCaptures;
- lastMove = lastBadCapture;
- sort_moves(badCaptures, lastMove);
- return;
-
- case PH_EVASIONS:
- assert(pos.is_check());
- lastMove = generate_evasions(pos, moves, pinned);
- score_evasions();
- sort_moves(moves, lastMove);
- return;
-
- case PH_QCAPTURES:
- lastMove = generate_captures(pos, moves);
- score_captures();
- sort_moves(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:
- lastMove = curMove + 1; // hack to be friendly for get_next_move()
- return;
-
- default:
- assert(false);
- return;
- }
+ assert(d <= 0);
+
+ stage = (pos.checkers() ? EVASION_TT : QSEARCH_TT) +
+ !( ttm
+ && (pos.checkers() || depth > DEPTH_QS_RECAPTURES || to_sq(ttm) == recaptureSquare)
+ && pos.pseudo_legal(ttm));
}
+/// MovePicker constructor for ProbCut: we generate captures with SEE greater
+/// than or equal to the given threshold.
+MovePicker::MovePicker(const Position& p, Move ttm, Value th, const CapturePieceToHistory* cph)
+ : pos(p), captureHistory(cph), ttMove(ttm), threshold(th) {
-/// 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)));
- }
+ assert(!pos.checkers());
+
+ stage = PROBCUT_TT + !(ttm && pos.capture(ttm)
+ && pos.pseudo_legal(ttm)
+ && pos.see_ge(ttm, threshold));
}
-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;
+/// MovePicker::score() assigns a numerical value to each move in a list, used
+/// for sorting. Captures are ordered by Most Valuable Victim (MVV), preferring
+/// captures with a good history. Quiets moves are ordered using the histories.
+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);
- }
-}
+ static_assert(Type == CAPTURES || Type == QUIETS || Type == EVASIONS, "Wrong type");
-void MovePicker::score_evasions() {
+ for (auto& m : *this)
+ if (Type == CAPTURES)
+ m.value = int(PieceValue[MG][pos.piece_on(to_sq(m))]) * 6
+ + (*captureHistory)[pos.moved_piece(m)][to_sq(m)][type_of(pos.piece_on(to_sq(m)))];
- Move m;
+ else if (Type == QUIETS)
+ m.value = (*mainHistory)[pos.side_to_move()][from_to(m)]
+ + 2 * (*continuationHistory[0])[pos.moved_piece(m)][to_sq(m)]
+ + 2 * (*continuationHistory[1])[pos.moved_piece(m)][to_sq(m)]
+ + 2 * (*continuationHistory[3])[pos.moved_piece(m)][to_sq(m)]
+ + (*continuationHistory[5])[pos.moved_piece(m)][to_sq(m)]
+ + (ply < MAX_LPH ? std::min(4, depth / 3) * (*lowPlyHistory)[ply][from_to(m)] : 0);
- 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)))
+ else // Type == EVASIONS
{
- 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));
- }
+ if (pos.capture(m))
+ m.value = PieceValue[MG][pos.piece_on(to_sq(m))]
+ - Value(type_of(pos.moved_piece(m)));
+ else
+ m.value = (*mainHistory)[pos.side_to_move()][from_to(m)]
+ + (*continuationHistory[0])[pos.moved_piece(m)][to_sq(m)]
+ - (1 << 28);
+ }
}
-/// 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 has already been searched previously.
+/// MovePicker::select() returns the next move satisfying a predicate function.
+/// It never returns the TT move.
+template
+Move MovePicker::select(Pred filter) {
-Move MovePicker::get_next_move() {
+ while (cur < endMoves)
+ {
+ if (T == Best)
+ std::swap(*cur, *std::max_element(cur, endMoves));
- assert(!pos.is_check() || *phasePtr == PH_EVASIONS || *phasePtr == PH_STOP);
- assert( pos.is_check() || *phasePtr != PH_EVASIONS);
+ if (*cur != ttMove && filter())
+ return *cur++;
- Move move;
+ cur++;
+ }
+ return MOVE_NONE;
+}
- while (true)
- {
- while (curMove != lastMove)
+/// 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, picking the move with the highest score from a list of generated moves.
+Move MovePicker::next_move(bool skipQuiets) {
+
+top:
+ switch (stage) {
+
+ case MAIN_TT:
+ case EVASION_TT:
+ case QSEARCH_TT:
+ case PROBCUT_TT:
+ ++stage;
+ return ttMove;
+
+ case CAPTURE_INIT:
+ case PROBCUT_INIT:
+ case QCAPTURE_INIT:
+ cur = endBadCaptures = moves;
+ endMoves = generate(pos, cur);
+
+ score();
+ ++stage;
+ goto top;
+
+ case GOOD_CAPTURE:
+ if (select([&](){
+ return pos.see_ge(*cur, Value(-69 * cur->value / 1024)) ?
+ // Move losing capture to endBadCaptures to be tried later
+ true : (*endBadCaptures++ = *cur, false); }))
+ return *(cur - 1);
+
+ // Prepare the pointers to loop over the refutations array
+ cur = std::begin(refutations);
+ endMoves = std::end(refutations);
+
+ // If the countermove is the same as a killer, skip it
+ if ( refutations[0].move == refutations[2].move
+ || refutations[1].move == refutations[2].move)
+ --endMoves;
+
+ ++stage;
+ [[fallthrough]];
+
+ case REFUTATION:
+ if (select([&](){ return *cur != MOVE_NONE
+ && !pos.capture(*cur)
+ && pos.pseudo_legal(*cur); }))
+ return *(cur - 1);
+ ++stage;
+ [[fallthrough]];
+
+ case QUIET_INIT:
+ if (!skipQuiets)
{
- move = (curMove++)->move;
-
- switch (phase) {
-
- case PH_TT_MOVES:
- if ( move != MOVE_NONE
- && move_is_legal(pos, move, pinned))
- return move;
- break;
-
- case PH_GOOD_CAPTURES:
- 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(int(lastBadCapture - badCaptures) < 63);
- lastBadCapture->move = move;
- lastBadCapture->score = seeValue;
- lastBadCapture++;
- }
- break;
-
- case PH_KILLERS:
- 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:
- 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:
- case PH_BAD_CAPTURES:
- return move;
-
- case PH_QCAPTURES:
- case PH_QCHECKS:
- // Maybe postpone the legality check until after futility pruning?
- if ( move != ttMoves[0].move
- && pos.pl_move_is_legal(move, pinned))
- return move;
- break;
-
- case PH_STOP:
- return MOVE_NONE;
-
- default:
- assert(false);
- break;
- }
+ cur = endBadCaptures;
+ endMoves = generate(pos, cur);
+
+ score();
+ partial_insertion_sort(cur, endMoves, -3000 * depth);
}
- 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.
+ ++stage;
+ [[fallthrough]];
+
+ case QUIET:
+ if ( !skipQuiets
+ && select([&](){return *cur != refutations[0].move
+ && *cur != refutations[1].move
+ && *cur != refutations[2].move;}))
+ return *(cur - 1);
+
+ // Prepare the pointers to loop over the bad captures
+ cur = moves;
+ endMoves = endBadCaptures;
+
+ ++stage;
+ [[fallthrough]];
-Move MovePicker::get_next_move(Lock &lock) {
+ case BAD_CAPTURE:
+ return select([](){ return true; });
- lock_grab(&lock);
- if (finished)
- {
- lock_release(&lock);
- return MOVE_NONE;
- }
- Move m = get_next_move();
- if (m == MOVE_NONE)
- finished = true;
+ case EVASION_INIT:
+ cur = moves;
+ endMoves = generate(pos, cur);
+
+ score();
+ ++stage;
+ [[fallthrough]];
+
+ case EVASION:
+ return select([](){ return true; });
+
+ case PROBCUT:
+ return select([&](){ return pos.see_ge(*cur, threshold); });
+
+ case QCAPTURE:
+ if (select([&](){ return depth > DEPTH_QS_RECAPTURES
+ || to_sq(*cur) == recaptureSquare; }))
+ return *(cur - 1);
+
+ // If we did not find any move and we do not try checks, we have finished
+ if (depth != DEPTH_QS_CHECKS)
+ return MOVE_NONE;
+
+ ++stage;
+ [[fallthrough]];
+
+ case QCHECK_INIT:
+ cur = moves;
+ endMoves = generate(pos, cur);
+
+ ++stage;
+ [[fallthrough]];
+
+ case QCHECK:
+ return select([](){ return true; });
+ }
- lock_release(&lock);
- return m;
+ assert(false);
+ return MOVE_NONE; // Silence warning
}