X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=e248b729361d8e1bac8e8d63d3fb2dc7b8d5ba64;hp=794fbde9b83366eb33e074e7b0b7fa921a5e4625;hb=2dd24dc4e618dc7b83799890fe7e84b09b6456b4;hpb=e82382703c96cfc480555e9db29d999e1f54a38f
diff --git a/src/movepick.cpp b/src/movepick.cpp
index 794fbde9..e248b729 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
@@ -18,249 +18,221 @@
along with this program. If not, see .
*/
-#include
#include
-#include "movegen.h"
#include "movepick.h"
#include "thread.h"
namespace {
- enum Sequencer {
- MAIN_SEARCH, CAPTURES_S1, KILLERS_S1, QUIETS_1_S1, QUIETS_2_S1, BAD_CAPTURES_S1,
- EVASION, EVASIONS_S2,
- QSEARCH_0, CAPTURES_S3, QUIET_CHECKS_S3,
- QSEARCH_1, CAPTURES_S4,
- PROBCUT, CAPTURES_S5,
- RECAPTURE, CAPTURES_S6,
+ 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
};
- // 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& ms) { return ms.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 [begin, end),
- // 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* begin, MoveStack* end)
+ // 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;
+ 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* s, 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;
- cur = end = moves;
- endBadCaptures = moves + MAX_MOVES - 1;
- ss = s;
-
- if (p.checkers())
- phase = EVASION;
-
- else
- {
- phase = MAIN_SEARCH;
-
- 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->staticEval < beta - PawnValueMg && d < 3 * ONE_PLY)
- captureThreshold = -PawnValueMg;
+ Square prevSq = to_sq((ss-1)->currentMove);
+ countermove = pos.this_thread()->counterMoves[pos.piece_on(prevSq)][prevSq];
- // Consider negative captures as good if still enough to reach beta
- else if (ss && ss->staticEval > beta)
- captureThreshold = beta - ss->staticEval;
- }
-
- ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE);
- end += (ttMove != MOVE_NONE);
+ 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,
- Square sq) : pos(p), H(h), cur(moves), end(moves) {
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, Square s)
+ : pos(p) {
assert(d <= DEPTH_ZERO);
- if (p.checkers())
- phase = EVASION;
+ if (pos.checkers())
+ stage = EVASION;
else if (d > DEPTH_QS_NO_CHECKS)
- phase = QSEARCH_0;
+ stage = QSEARCH_WITH_CHECKS;
else if (d > DEPTH_QS_RECAPTURES)
- {
- phase = QSEARCH_1;
+ stage = QSEARCH_WITHOUT_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 = RECAPTURE;
- recaptureSquare = sq;
+ stage = RECAPTURE;
+ recaptureSquare = s;
ttm = MOVE_NONE;
}
- ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE);
- end += (ttMove != MOVE_NONE);
+ ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE;
+ endMoves += (ttMove != MOVE_NONE);
}
-MovePicker::MovePicker(const Position& p, Move ttm, const History& h, PieceType pt)
- : pos(p), H(h), cur(moves), end(moves) {
+MovePicker::MovePicker(const Position& p, Move ttm, Value th)
+ : pos(p), threshold(th) {
assert(!pos.checkers());
- phase = PROBCUT;
-
- // In ProbCut we generate only captures better than parent's captured piece
- captureThreshold = PieceValue[MG][pt];
- ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE);
+ stage = PROBCUT;
- if (ttMove && (!pos.is_capture(ttMove) || pos.see(ttMove) <= captureThreshold))
- ttMove = MOVE_NONE;
+ // 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;
- end += (ttMove != 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 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* it = moves; it != end; ++it)
- {
- m = it->move;
- it->score = PieceValue[MG][pos.piece_on(to_sq(m))]
- - type_of(pos.piece_moved(m));
-
- if (type_of(m) == PROMOTION)
- it->score += PieceValue[MG][promotion_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;
+ const HistoryStats& history = pos.this_thread()->history;
- for (MoveStack* it = moves; it != end; ++it)
- {
- m = it->move;
- it->score = H.value(pos.piece_moved(m), 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, then bad-captures and quiet
- // moves with a negative SEE. This last group is ordered by the SEE score.
- Move m;
- int seeScore;
+ const CounterMoveStats* cm = (ss-1)->counterMoves;
+ const CounterMoveStats* fm = (ss-2)->counterMoves;
+ const CounterMoveStats* f2 = (ss-4)->counterMoves;
- if (end < moves + 2)
- return;
+ for (auto& m : *this)
+ m.value = history[pos.moved_piece(m)][to_sq(m)]
+ + (cm ? (*cm)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO)
+ + (fm ? (*fm)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO)
+ + (f2 ? (*f2)[pos.moved_piece(m)][to_sq(m)] : VALUE_ZERO);
+}
- for (MoveStack* it = moves; it != end; ++it)
- {
- m = it->move;
- if ((seeScore = pos.see_sign(m)) < 0)
- it->score = seeScore - History::MaxValue; // Be sure we are at the bottom
- else if (pos.is_capture(m))
- it->score = PieceValue[MG][pos.piece_on(to_sq(m))]
- - type_of(pos.piece_moved(m)) + History::MaxValue;
+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.
+ const HistoryStats& history = pos.this_thread()->history;
+ Value see;
+
+ for (auto& m : *this)
+ if ((see = pos.see_sign(m)) < VALUE_ZERO)
+ m.value = see - HistoryStats::Max; // At the bottom
+
+ 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
- it->score = H.value(pos.piece_moved(m), to_sq(m));
- }
+ m.value = history[pos.moved_piece(m)][to_sq(m)];
}
-/// MovePicker::generate_next() generates, scores and sorts the next bunch of moves,
-/// when there are no more moves to try for the current phase.
+/// 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() {
-void MovePicker::generate_next() {
+ assert(stage != STOP);
cur = moves;
- switch (++phase) {
+ switch (++stage) {
- case CAPTURES_S1: case CAPTURES_S3: case CAPTURES_S4: case CAPTURES_S5: case CAPTURES_S6:
- end = generate(pos, moves);
- score_captures();
- return;
+ case GOOD_CAPTURES: case QCAPTURES_1: case QCAPTURES_2:
+ case PROBCUT_CAPTURES: case RECAPTURES:
+ endMoves = generate(pos, moves);
+ score();
+ break;
- case KILLERS_S1:
+ case KILLERS:
+ killers[0] = ss->killers[0];
+ killers[1] = ss->killers[1];
+ killers[2] = countermove;
cur = killers;
- end = cur + 2;
- return;
-
- case QUIETS_1_S1:
- endQuiets = end = generate(pos, moves);
- score_noncaptures();
- end = std::partition(cur, end, has_positive_score);
- sort(cur, end);
- return;
-
- case QUIETS_2_S1:
- cur = end;
- end = endQuiets;
+ 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)
- sort(cur, end);
- return;
+ insertion_sort(cur, endMoves);
+ break;
- case BAD_CAPTURES_S1:
- // Just pick them in reverse order to get MVV/LVA ordering
+ case BAD_CAPTURES:
+ // Just pick them in reverse order to get correct ordering
cur = moves + MAX_MOVES - 1;
- end = endBadCaptures;
- return;
+ endMoves = endBadCaptures;
+ break;
- case EVASIONS_S2:
- end = generate(pos, moves);
- score_evasions();
- return;
+ case ALL_EVASIONS:
+ endMoves = generate(pos, moves);
+ if (endMoves - moves > 1)
+ score();
+ break;
- case QUIET_CHECKS_S3:
- end = generate(pos, moves);
- return;
+ case CHECKS:
+ endMoves = generate(pos, moves);
+ break;
- case EVASION: case QSEARCH_0: case QSEARCH_1: case PROBCUT: case RECAPTURE:
- phase = STOP;
- case STOP:
- end = cur + 1; // Avoid another next_phase() call
- return;
+ case EVASION: case QSEARCH_WITH_CHECKS: case QSEARCH_WITHOUT_CHECKS:
+ case PROBCUT: case RECAPTURE: case STOP:
+ stage = STOP;
+ break;
default:
assert(false);
@@ -268,81 +240,80 @@ void MovePicker::generate_next() {
}
-/// 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.
-template<>
-Move MovePicker::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() {
Move move;
while (true)
{
- while (cur == end)
- generate_next();
+ while (cur == endMoves && stage != STOP)
+ generate_next_stage();
- switch (phase) {
+ switch (stage) {
- case MAIN_SEARCH: case EVASION: case QSEARCH_0: case QSEARCH_1: case PROBCUT:
- cur++;
+ case MAIN_SEARCH: case EVASION: case QSEARCH_WITH_CHECKS:
+ case QSEARCH_WITHOUT_CHECKS: case PROBCUT:
+ ++cur;
return ttMove;
- case CAPTURES_S1:
- move = pick_best(cur++, end)->move;
+ case GOOD_CAPTURES:
+ move = pick_best(cur++, endMoves);
if (move != ttMove)
{
- assert(captureThreshold <= 0); // Otherwise we cannot use see_sign()
-
- if (pos.see_sign(move) >= captureThreshold)
+ if (pos.see_sign(move) >= VALUE_ZERO)
return move;
// Losing capture, move it to the tail of the array
- (endBadCaptures--)->move = move;
+ *endBadCaptures-- = move;
}
break;
- case KILLERS_S1:
- move = (cur++)->move;
+ case KILLERS:
+ move = *cur++;
if ( move != MOVE_NONE
- && pos.is_pseudo_legal(move)
&& move != ttMove
- && !pos.is_capture(move))
+ && pos.pseudo_legal(move)
+ && !pos.capture(move))
return move;
break;
- case QUIETS_1_S1: case QUIETS_2_S1:
- move = (cur++)->move;
+ case GOOD_QUIETS: case BAD_QUIETS:
+ move = *cur++;
if ( move != ttMove
- && move != killers[0].move
- && move != killers[1].move)
+ && move != killers[0]
+ && move != killers[1]
+ && move != killers[2])
return move;
break;
- case BAD_CAPTURES_S1:
- return (cur--)->move;
+ case BAD_CAPTURES:
+ return *cur--;
- case EVASIONS_S2: case CAPTURES_S3: case CAPTURES_S4:
- move = pick_best(cur++, end)->move;
+ case ALL_EVASIONS: case QCAPTURES_1: case QCAPTURES_2:
+ move = pick_best(cur++, endMoves);
if (move != ttMove)
return move;
break;
- case CAPTURES_S5:
- move = pick_best(cur++, end)->move;
- if (move != ttMove && pos.see(move) > captureThreshold)
+ case PROBCUT_CAPTURES:
+ move = pick_best(cur++, endMoves);
+ if (move != ttMove && pos.see(move) > threshold)
return move;
break;
- case CAPTURES_S6:
- move = pick_best(cur++, end)->move;
+ case RECAPTURES:
+ move = pick_best(cur++, endMoves);
if (to_sq(move) == recaptureSquare)
return move;
break;
- case QUIET_CHECKS_S3:
- move = (cur++)->move;
+ case CHECKS:
+ move = *cur++;
if (move != ttMove)
return move;
break;
@@ -355,10 +326,3 @@ Move MovePicker::next_move() {
}
}
}
-
-
-/// Version of next_move() to use at split point nodes where the move is grabbed
-/// from the split point's shared MovePicker object. This function is not thread
-/// safe so should be lock protected by the caller.
-template<>
-Move MovePicker::next_move() { return ss->sp->mp->next_move(); }