X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=0be426ab659b969b8073b0bb5c8c528f911a2451;hp=4be0f69a6ba5eef513fc02cbfd888c9ffb9e6357;hb=5bb766e826af935b159cbd2ab9c59b279930dc5e;hpb=a2e924039bb96c0b923512dbb6903de9bb6bbd21
diff --git a/src/movepick.cpp b/src/movepick.cpp
index 4be0f69a..0be426ab 100644
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -1,7 +1,7 @@
/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, 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
@@ -18,174 +18,131 @@
along with this program. If not, see .
*/
+#include
#include
#include "movegen.h"
#include "movepick.h"
-#include "search.h"
-#include "types.h"
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 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,
+ STOP
};
- CACHE_LINE_ALIGNMENT
- const uint8_t MainSearchTable[] = { PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP };
- const uint8_t EvasionTable[] = { PH_TT_MOVES, PH_EVASIONS, PH_STOP };
- const uint8_t QsearchWithChecksTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_QCHECKS, PH_STOP };
- const uint8_t QsearchWithoutChecksTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_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& move) { return move.score > 0; }
+
+ // 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)
+ {
+ std::swap(*firstMove, *std::max_element(firstMove, lastMove));
+ return firstMove;
+ }
}
-/// Constructor for the MovePicker class. Apart from the position for which
-/// it is asked to pick legal moves, MovePicker also wants some information
+/// 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.
MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h,
- SearchStack* ss, Value beta) : pos(p), H(h) {
- int searchTT = ttm;
- ttMoves[0].move = ttm;
- badCaptureThreshold = 0;
- badCaptures = moves + MAX_MOVES;
+ Search::Stack* ss, Value beta) : pos(p), H(h), depth(d) {
assert(d > DEPTH_ZERO);
- pinned = p.pinned_pieces(pos.side_to_move());
+ captureThreshold = 0;
+ curMove = lastMove = moves;
+ lastBadCapture = moves + MAX_MOVES - 1;
if (p.in_check())
- {
- ttMoves[1].move = killers[0].move = killers[1].move = MOVE_NONE;
- phasePtr = EvasionTable;
- }
+ phase = EVASION;
+
else
{
- ttMoves[1].move = (ss->mateKiller == ttm) ? MOVE_NONE : ss->mateKiller;
- searchTT |= ttMoves[1].move;
+ 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.
+ // Consider sligtly negative captures as good if at low depth and far from beta
if (ss && ss->eval < beta - PawnValueMidgame && d < 3 * ONE_PLY)
- badCaptureThreshold = -PawnValueMidgame;
+ captureThreshold = -PawnValueMidgame;
- phasePtr = MainSearchTable;
+ // Consider negative captures as good if still enough to reach beta
+ else if (ss && ss->eval > beta)
+ captureThreshold = beta - ss->eval;
}
- phasePtr += int(!searchTT) - 1;
- go_next_phase();
+ ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE);
+ lastMove += (ttMove != MOVE_NONE);
}
-MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h)
- : pos(p), H(h) {
- int searchTT = ttm;
- ttMoves[0].move = ttm;
- ttMoves[1].move = MOVE_NONE;
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h,
+ Square sq) : pos(p), H(h), curMove(moves), lastMove(moves) {
assert(d <= DEPTH_ZERO);
- pinned = p.pinned_pieces(pos.side_to_move());
-
if (p.in_check())
- phasePtr = EvasionTable;
- else if (d >= DEPTH_QS_CHECKS)
- phasePtr = QsearchWithChecksTable;
- else
+ phase = EVASION;
+
+ else if (d > DEPTH_QS_NO_CHECKS)
+ phase = QSEARCH_0;
+
+ else if (d > DEPTH_QS_RECAPTURES)
{
- phasePtr = QsearchWithoutChecksTable;
+ phase = QSEARCH_1;
- // 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 != MOVE_NONE && !pos.move_is_capture(ttm) && !move_is_promotion(ttm))
- searchTT = ttMoves[0].move = MOVE_NONE;
+ // 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;
+ ttm = MOVE_NONE;
}
- phasePtr += int(!searchTT) - 1;
- go_next_phase();
+ ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE);
+ lastMove += (ttMove != MOVE_NONE);
}
+MovePicker::MovePicker(const Position& p, Move ttm, const History& h, PieceType pt)
+ : pos(p), H(h), curMove(moves), lastMove(moves) {
-/// 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(pos, moves);
- score_captures();
- return;
-
- case PH_KILLERS:
- curMove = killers;
- lastMove = curMove + 2;
- return;
-
- case PH_NONCAPTURES:
- lastMove = generate(pos, moves);
- score_noncaptures();
- sort_moves(moves, lastMove, &lastGoodNonCapture);
- return;
-
- case PH_BAD_CAPTURES:
- // 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 PH_EVASIONS:
- assert(pos.in_check());
- lastMove = generate(pos, moves);
- score_evasions();
- return;
+ assert(!pos.in_check());
- case PH_QCAPTURES:
- lastMove = generate(pos, moves);
- score_captures();
- return;
+ phase = PROBCUT;
- case PH_QCHECKS:
- lastMove = generate(pos, moves);
- return;
+ // In ProbCut we generate only captures better than parent's captured piece
+ captureThreshold = PieceValueMidgame[pt];
+ ttMove = (ttm && pos.is_pseudo_legal(ttm) ? ttm : MOVE_NONE);
- case PH_STOP:
- lastMove = curMove + 1; // Avoid another go_next_phase() call
- return;
+ if (ttMove && (!pos.is_capture(ttMove) || pos.see(ttMove) <= captureThreshold))
+ ttMove = MOVE_NONE;
- default:
- assert(false);
- return;
- }
+ lastMove += (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().
+/// picked first by next_move().
void MovePicker::score_captures() {
// Winning and equal captures in the main search are ordered by MVV/LVA.
@@ -203,40 +160,35 @@ void MovePicker::score_captures() {
// 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 = pos.midgame_value_of_piece_on(move_to(m))
- - pos.type_of_piece_on(move_from(m));
+ cur->score = PieceValueMidgame[pos.piece_on(to_sq(m))]
+ - type_of(pos.piece_moved(m));
+
+ if (is_promotion(m))
+ cur->score += PieceValueMidgame[promotion_type(m)];
}
}
void MovePicker::score_noncaptures() {
Move m;
- Square from;
for (MoveStack* cur = moves; cur != lastMove; cur++)
{
m = cur->move;
- from = move_from(m);
- cur->score = H.value(pos.piece_on(from), move_to(m));
+ cur->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, and at the end bad-captures and non-captures with a
- // negative SEE. This last group is ordered by the SEE score.
+ // 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;
- // Skip if we don't have at least two moves to order
if (lastMove < moves + 2)
return;
@@ -245,106 +197,160 @@ void MovePicker::score_evasions() {
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.move_is_capture(m))
- cur->score = pos.midgame_value_of_piece_on(move_to(m))
- - pos.type_of_piece_on(move_from(m)) + History::MaxValue;
+ 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_on(move_from(m)), move_to(m));
+ cur->score = H.value(pos.piece_moved(m), to_sq(m));
}
}
-/// 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
+
+/// MovePicker::generate_next() generates, scores and sorts the next bunch of moves,
+/// when there are no more moves to try for the current phase.
+
+void MovePicker::generate_next() {
+
+ curMove = moves;
+
+ switch (++phase) {
+
+ 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:
+ // Just pick them in reverse order to get MVV/LVA ordering
+ curMove = moves + MAX_MOVES - 1;
+ lastMove = lastBadCapture;
+ return;
+
+ case EVASIONS_S2:
+ lastMove = generate(pos, moves);
+ score_evasions();
+ return;
+
+ case QUIET_CHECKS_S3:
+ lastMove = generate(pos, moves);
+ return;
+
+ case EVASION: case QSEARCH_0: case QSEARCH_1: case PROBCUT: case RECAPTURE:
+ phase = STOP;
+ case STOP:
+ lastMove = curMove + 1; // Avoid another next_phase() call
+ return;
+
+ default:
+ assert(false);
+ }
+}
+
+
+/// 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.
-Move MovePicker::get_next_move() {
+Move MovePicker::next_move() {
Move move;
while (true)
{
while (curMove == lastMove)
- go_next_phase();
+ generate_next();
switch (phase) {
- case PH_TT_MOVES:
- move = (curMove++)->move;
- if ( move != MOVE_NONE
- && pos.move_is_legal(move, pinned))
- return move;
- break;
+ case MAIN_SEARCH: case EVASION: case QSEARCH_0: case QSEARCH_1: case PROBCUT:
+ curMove++;
+ return ttMove;
- case PH_GOOD_CAPTURES:
- move = pick_best(curMove++, lastMove).move;
- if ( move != ttMoves[0].move
- && move != ttMoves[1].move
- && pos.pl_move_is_legal(move, pinned))
+ case CAPTURES_S1:
+ move = pick_best(curMove++, lastMove)->move;
+ if (move != ttMove)
{
- // Check for a non negative SEE now
- int seeValue = pos.see_sign(move);
- if (seeValue >= badCaptureThreshold)
+ assert(captureThreshold <= 0); // Otherwise we cannot use see_sign()
+
+ if (pos.see_sign(move) >= captureThreshold)
return move;
- // Losing capture, move it to the tail of the array, note
- // that move has now been already checked for legality.
- (--badCaptures)->move = move;
- badCaptures->score = seeValue;
+ // Losing capture, move it to the tail of the array
+ (lastBadCapture--)->move = move;
}
break;
- case PH_KILLERS:
+ case KILLERS_S1:
move = (curMove++)->move;
if ( move != MOVE_NONE
- && pos.move_is_legal(move, pinned)
- && move != ttMoves[0].move
- && move != ttMoves[1].move
- && !pos.move_is_capture(move))
+ && pos.is_pseudo_legal(move)
+ && move != ttMove
+ && !pos.is_capture(move))
return move;
break;
- case PH_NONCAPTURES:
- // Sort negative scored moves only when we get there
- if (curMove == lastGoodNonCapture)
- insertion_sort(lastGoodNonCapture, lastMove);
-
+ case QUIETS_1_S1: case QUIETS_2_S1:
move = (curMove++)->move;
- if ( move != ttMoves[0].move
- && move != ttMoves[1].move
+ if ( move != ttMove
&& move != killers[0].move
- && move != killers[1].move
- && pos.pl_move_is_legal(move, pinned))
+ && move != killers[1].move)
return move;
break;
- case PH_BAD_CAPTURES:
- move = pick_best(curMove++, lastMove).move;
- return move;
+ case BAD_CAPTURES_S1:
+ return (curMove--)->move;
- case PH_EVASIONS:
- case PH_QCAPTURES:
- move = pick_best(curMove++, lastMove).move;
- if ( move != ttMoves[0].move
- && pos.pl_move_is_legal(move, pinned))
+ case EVASIONS_S2: case CAPTURES_S3: case CAPTURES_S4:
+ move = pick_best(curMove++, lastMove)->move;
+ if (move != ttMove)
return move;
break;
- case PH_QCHECKS:
+ 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)
+ return move;
+ break;
+
+ case QUIET_CHECKS_S3:
move = (curMove++)->move;
- if ( move != ttMoves[0].move
- && pos.pl_move_is_legal(move, pinned))
+ if (move != ttMove)
return move;
break;
- case PH_STOP:
+ case STOP:
return MOVE_NONE;
default:
assert(false);
- break;
}
}
}