X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fmovepick.cpp;h=b0469a66abd5f08ce6facf8754ea1344f895e887;hb=8dd6875240e05dbcc1fb6467ffb11ad360aa474c;hp=4b08e1b46d35c07e95bd65cf547e459f1bdbe86e;hpb=3e0753bef36e5efeed700d7277187f6fbd7275f5;p=stockfish
diff --git a/src/movepick.cpp b/src/movepick.cpp
index 4b08e1b4..51d85192 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) 2015-2018 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
@@ -18,401 +18,295 @@
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
-////
namespace {
- /// Variables
+ enum Stages {
+ MAIN_SEARCH, CAPTURES_INIT, GOOD_CAPTURES, KILLERS, COUNTERMOVE, QUIET_INIT, QUIET, BAD_CAPTURES,
+ EVASION, EVASIONS_INIT, ALL_EVASIONS,
+ PROBCUT, PROBCUT_CAPTURES_INIT, PROBCUT_CAPTURES,
+ QSEARCH, QCAPTURES_INIT, QCAPTURES, QCHECKS, QSEARCH_RECAPTURES, QRECAPTURES
+ };
- MovePicker::MovegenPhase PhaseTable[32];
- int MainSearchPhaseIndex;
- int EvasionsPhaseIndex;
- int QsearchWithChecksPhaseIndex;
- int QsearchWithoutChecksPhaseIndex;
+ // 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;
+ }
+ }
+ // 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) {
-////
-//// Functions
-////
+ std::swap(*begin, *std::max_element(begin, end));
+ return *begin;
+ }
+} // 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
-/// 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) : pos(p), H(h) {
- ttMove = ttm;
- if (ss)
- {
- mateKiller = (ss->mateKiller == ttm)? MOVE_NONE : ss->mateKiller;
- killer1 = ss->killers[0];
- killer2 = ss->killers[1];
- } else
- mateKiller = killer1 = killer2 = MOVE_NONE;
-
- movesPicked = numOfMoves = numOfBadCaptures = 0;
- checkKillers = checkLegal = finished = false;
-
- if (p.is_check())
- phaseIndex = EvasionsPhaseIndex;
- else if (d > Depth(0))
- phaseIndex = MainSearchPhaseIndex;
- else if (d == Depth(0))
- phaseIndex = QsearchWithChecksPhaseIndex;
- else
- phaseIndex = QsearchWithoutChecksPhaseIndex;
+/// 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 how important good move
+/// ordering is at the current node.
- Color us = pos.side_to_move();
+/// MovePicker constructor for the main search
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh,
+ const CapturePieceToHistory* cph, const PieceToHistory** ch, Move cm, Move* killers_p)
+ : pos(p), mainHistory(mh), captureHistory(cph), contHistory(ch), countermove(cm),
+ killers{killers_p[0], killers_p[1]}, depth(d){
- dc = p.discovered_check_candidates(us);
- pinned = p.pinned_pieces(us);
+ assert(d > DEPTH_ZERO);
- finished = false;
+ stage = pos.checkers() ? EVASION : MAIN_SEARCH;
+ ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE;
+ stage += (ttMove == MOVE_NONE);
}
+/// MovePicker constructor for quiescence search
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh, const CapturePieceToHistory* cph, Square s)
+ : pos(p), mainHistory(mh), captureHistory(cph), depth(d) {
-/// 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 (pos.checkers())
+ stage = EVASION;
- Move move;
+ else if (d > DEPTH_QS_RECAPTURES)
+ stage = QSEARCH;
- while (true)
+ 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
- phaseIndex++;
- switch (PhaseTable[phaseIndex]) {
-
- case PH_TT_MOVE:
- if (ttMove != MOVE_NONE)
- {
- assert(move_is_ok(ttMove));
- if (move_is_legal(pos, ttMove, pinned))
- return ttMove;
- }
- break;
-
- case PH_MATE_KILLER:
- if (mateKiller != MOVE_NONE)
- {
- assert(move_is_ok(mateKiller));
- if (move_is_legal(pos, mateKiller, pinned))
- return mateKiller;
- }
- break;
-
- case PH_GOOD_CAPTURES:
- numOfMoves = generate_captures(pos, moves);
- score_captures();
- std::sort(moves, moves + numOfMoves);
- movesPicked = 0;
- checkLegal = true;
- break;
-
- case PH_KILLERS:
- movesPicked = numOfMoves = 0;
- checkLegal = false;
- if (killer1 != MOVE_NONE && move_is_legal(pos, killer1, pinned) && !pos.move_is_capture(killer1))
- moves[numOfMoves++].move = killer1;
- if (killer2 != MOVE_NONE && move_is_legal(pos, killer2, pinned) && !pos.move_is_capture(killer2) )
- moves[numOfMoves++].move = killer2;
- break;
-
- case PH_NONCAPTURES:
- checkKillers = (numOfMoves != 0); // previous phase is PH_KILLERS
- numOfMoves = generate_noncaptures(pos, moves);
- score_noncaptures();
- std::sort(moves, moves + numOfMoves);
- movesPicked = 0;
- checkLegal = true;
- break;
-
- case PH_BAD_CAPTURES:
- // Bad captures SEE value is already calculated by score_captures()
- // 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_qcaptures();
- 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;
- }
+ stage = QSEARCH_RECAPTURES;
+ recaptureSquare = s;
+ return;
}
-}
+ ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE;
+ stage += (ttMove == 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.
+/// MovePicker constructor for ProbCut: we generate captures with SEE higher
+/// than or equal to the given threshold.
+MovePicker::MovePicker(const Position& p, Move ttm, Value th, const CapturePieceToHistory* cph)
+ : pos(p), captureHistory(cph), threshold(th) {
-Move MovePicker::get_next_move(Lock &lock) {
+ assert(!pos.checkers());
- lock_grab(&lock);
- if (finished)
- {
- lock_release(&lock);
- return MOVE_NONE;
- }
- Move m = get_next_move();
- if (m == MOVE_NONE)
- finished = true;
+ stage = PROBCUT;
+ ttMove = ttm
+ && pos.pseudo_legal(ttm)
+ && pos.capture(ttm)
+ && pos.see_ge(ttm, threshold) ? ttm : MOVE_NONE;
- lock_release(&lock);
- return m;
+ stage += (ttMove == MOVE_NONE);
}
+/// 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 are ordered using the histories.
+template
+void MovePicker::score() {
-/// 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().
-
-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.
- // While scoring captures it moves all captures with negative SEE values
- // to the badCaptures[] array.
- Move m;
- int seeValue;
-
- for (int i = 0; i < numOfMoves; i++)
- {
- m = moves[i].move;
- seeValue = pos.see(m);
- if (seeValue >= 0)
+ static_assert(Type == CAPTURES || Type == QUIETS || Type == EVASIONS, "Wrong type");
+
+ for (auto& m : *this)
+ if (Type == CAPTURES)
+ m.value = PieceValue[MG][pos.piece_on(to_sq(m))]
+ + Value((*captureHistory)[pos.moved_piece(m)][to_sq(m)][type_of(pos.piece_on(to_sq(m)))]);
+
+ else if (Type == QUIETS)
+ m.value = (*mainHistory)[pos.side_to_move()][from_to(m)]
+ + (*contHistory[0])[pos.moved_piece(m)][to_sq(m)]
+ + (*contHistory[1])[pos.moved_piece(m)][to_sq(m)]
+ + (*contHistory[3])[pos.moved_piece(m)][to_sq(m)];
+
+ else // Type == EVASIONS
{
- if (move_promotion(m))
- moves[i].score = QueenValueMidgame;
+ if (pos.capture(m))
+ m.value = PieceValue[MG][pos.piece_on(to_sq(m))]
+ - Value(type_of(pos.moved_piece(m)));
else
- moves[i].score = int(pos.midgame_value_of_piece_on(move_to(m)))
- -int(pos.type_of_piece_on(move_from(m)));
- }
- else
- {
- // Losing capture, move it to the badCaptures[] array
- assert(numOfBadCaptures < 63);
- moves[i].score = seeValue;
- badCaptures[numOfBadCaptures++] = moves[i];
- moves[i--] = moves[--numOfMoves];
+ m.value = (*mainHistory)[pos.side_to_move()][from_to(m)] - (1 << 28);
}
- }
}
-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;
- int hs;
-
- for (int i = 0; i < numOfMoves; i++)
- {
- m = moves[i].move;
- hs = H.move_ordering_score(pos.piece_on(move_from(m)), move_to(m));
+/// 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.
- // Ensure history is always preferred to pst
- if (hs > 0)
- hs += 1000;
+Move MovePicker::next_move(bool skipQuiets) {
- // pst based scoring
- moves[i].score = hs + pos.mg_pst_delta(m);
- }
-}
-
-void MovePicker::score_evasions() {
-
- for (int i = 0; i < numOfMoves; i++)
- {
- Move m = moves[i].move;
- if (m == ttMove)
- 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));
- }
-}
+ Move move;
-void MovePicker::score_qcaptures() {
+ switch (stage) {
- // Use MVV/LVA ordering
- for (int i = 0; i < numOfMoves; i++)
- {
- Move m = moves[i].move;
- if (move_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)));
- }
-}
+ case MAIN_SEARCH: case EVASION: case QSEARCH: case PROBCUT:
+ ++stage;
+ return ttMove;
+ case CAPTURES_INIT:
+ case PROBCUT_CAPTURES_INIT:
+ case QCAPTURES_INIT:
+ case QSEARCH_RECAPTURES:
+ endBadCaptures = cur = moves;
+ endMoves = generate(pos, cur);
+ score();
+ ++stage;
-/// 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.
+ // Rebranch at the top of the switch via a recursive call
+ return next_move(skipQuiets);
-Move MovePicker::pick_move_from_list() {
+ case GOOD_CAPTURES:
+ while (cur < endMoves)
+ {
+ move = pick_best(cur++, endMoves);
+ if (move != ttMove)
+ {
+ if (pos.see_ge(move, Value(-55 * (cur-1)->value / 1024)))
+ return move;
+
+ // Losing capture, move it to the beginning of the array
+ *endBadCaptures++ = move;
+ }
+ }
- assert(movesPicked >= 0);
- assert(!pos.is_check() || PhaseTable[phaseIndex] == PH_EVASIONS || PhaseTable[phaseIndex] == PH_STOP);
- assert( pos.is_check() || PhaseTable[phaseIndex] != PH_EVASIONS);
+ ++stage;
+ move = killers[0]; // First killer move
+ if ( move != MOVE_NONE
+ && move != ttMove
+ && pos.pseudo_legal(move)
+ && !pos.capture(move))
+ return move;
+ /* fallthrough */
+
+ case KILLERS:
+ ++stage;
+ move = killers[1]; // Second killer move
+ if ( move != MOVE_NONE
+ && move != ttMove
+ && pos.pseudo_legal(move)
+ && !pos.capture(move))
+ return move;
+ /* fallthrough */
+
+ case COUNTERMOVE:
+ ++stage;
+ move = countermove;
+ if ( move != MOVE_NONE
+ && move != ttMove
+ && move != killers[0]
+ && move != killers[1]
+ && pos.pseudo_legal(move)
+ && !pos.capture(move))
+ return move;
+ /* fallthrough */
+
+ case QUIET_INIT:
+ cur = endBadCaptures;
+ endMoves = generate(pos, cur);
+ score();
+ partial_insertion_sort(cur, endMoves, -4000 * depth / ONE_PLY);
+ ++stage;
+ /* fallthrough */
+
+ case QUIET:
+ if (!skipQuiets)
+ while (cur < endMoves)
+ {
+ move = *cur++;
+
+ if ( move != ttMove
+ && move != killers[0]
+ && move != killers[1]
+ && move != countermove)
+ return move;
+ }
+ ++stage;
+ cur = moves; // Point to beginning of bad captures
+ /* fallthrough */
+
+ case BAD_CAPTURES:
+ if (cur < endBadCaptures)
+ return *cur++;
+ break;
- switch (PhaseTable[phaseIndex]) {
+ case EVASIONS_INIT:
+ cur = moves;
+ endMoves = generate(pos, cur);
+ score();
+ ++stage;
+ /* fallthrough */
- case PH_GOOD_CAPTURES:
- case PH_KILLERS:
- case PH_NONCAPTURES:
- while (movesPicked < numOfMoves)
+ case ALL_EVASIONS:
+ while (cur < endMoves)
{
- Move move = moves[movesPicked++].move;
- if ( move != ttMove
- && move != mateKiller
- && (!checkKillers || (move != killer1 && move != killer2))
- && (!checkLegal || pos.pl_move_is_legal(move, pinned)))
+ move = pick_best(cur++, endMoves);
+ if (move != ttMove)
return move;
}
break;
- case PH_EVASIONS:
- if (movesPicked < numOfMoves)
- return moves[movesPicked++].move;
-
+ case PROBCUT_CAPTURES:
+ while (cur < endMoves)
+ {
+ move = pick_best(cur++, endMoves);
+ if ( move != ttMove
+ && pos.see_ge(move, threshold))
+ return move;
+ }
break;
- case PH_BAD_CAPTURES:
- while (movesPicked < numOfBadCaptures)
+ case QCAPTURES:
+ while (cur < endMoves)
{
- Move move = badCaptures[movesPicked++].move;
- if ( move != ttMove
- && move != mateKiller
- && pos.pl_move_is_legal(move, pinned))
+ move = pick_best(cur++, endMoves);
+ if (move != ttMove)
+ return move;
+ }
+ if (depth <= DEPTH_QS_NO_CHECKS)
+ break;
+ cur = moves;
+ endMoves = generate(pos, cur);
+ ++stage;
+ /* fallthrough */
+
+ case QCHECKS:
+ while (cur < endMoves)
+ {
+ move = cur++->move;
+ if (move != ttMove)
return move;
}
break;
- case PH_QCAPTURES:
- case PH_QCHECKS:
- while (movesPicked < numOfMoves)
+ case QRECAPTURES:
+ while (cur < endMoves)
{
- Move move = moves[movesPicked++].move;
- // Maybe postpone the legality check until after futility pruning?
- if ( move != ttMove
- && pos.pl_move_is_legal(move, pinned))
+ move = *cur++;
+ if (to_sq(move) == recaptureSquare)
return move;
}
break;
default:
- break;
+ assert(false);
}
- return MOVE_NONE;
-}
-
-/// MovePicker::init_phase_table() initializes the PhaseTable[],
-/// MainSearchPhaseIndex, EvasionPhaseIndex, QsearchWithChecksPhaseIndex
-/// and QsearchWithoutChecksPhaseIndex. It is only called once during
-/// program startup, and never again while the program is running.
-
-void MovePicker::init_phase_table() {
-
- int i = 0;
-
- // Main search
- MainSearchPhaseIndex = i - 1;
- PhaseTable[i++] = PH_TT_MOVE;
- PhaseTable[i++] = PH_MATE_KILLER;
- PhaseTable[i++] = PH_GOOD_CAPTURES;
- PhaseTable[i++] = PH_KILLERS;
- PhaseTable[i++] = PH_NONCAPTURES;
- PhaseTable[i++] = PH_BAD_CAPTURES;
- PhaseTable[i++] = PH_STOP;
-
- // Check evasions
- EvasionsPhaseIndex = i - 1;
- PhaseTable[i++] = PH_EVASIONS;
- PhaseTable[i++] = PH_STOP;
-
- // Quiescence search with checks
- QsearchWithChecksPhaseIndex = i - 1;
- PhaseTable[i++] = PH_TT_MOVE;
- PhaseTable[i++] = PH_QCAPTURES;
- PhaseTable[i++] = PH_QCHECKS;
- PhaseTable[i++] = PH_STOP;
-
- // Quiescence search without checks
- QsearchWithoutChecksPhaseIndex = i - 1;
- PhaseTable[i++] = PH_TT_MOVE;
- PhaseTable[i++] = PH_QCAPTURES;
- PhaseTable[i++] = PH_STOP;
+ return MOVE_NONE;
}