/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008 Marco Costalba
+ Copyright (C) 2008-2009 Marco Costalba
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
//// Includes
////
+#include <algorithm>
#include <cassert>
#include "history.h"
/// Variables
- MovePicker::MovegenPhase PhaseTable[32];
- int MainSearchPhaseIndex;
- int EvasionsPhaseIndex;
- int QsearchWithChecksPhaseIndex;
- int QsearchWithoutChecksPhaseIndex;
-
+ CACHE_LINE_ALIGNMENT
+ const MovegenPhaseT MainSearchPhaseTable[] = { PH_STOP, PH_NULL_MOVE, PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP};
+ const MovegenPhaseT EvasionsPhaseTable[] = { PH_STOP, PH_EVASIONS, PH_STOP};
+ const MovegenPhaseT QsearchWithChecksPhaseTable[] = { PH_STOP, PH_TT_MOVES, PH_QCAPTURES, PH_QCHECKS, PH_STOP};
+ const MovegenPhaseT QsearchWithoutChecksPhaseTable[] = { PH_STOP, PH_TT_MOVES, PH_QCAPTURES, PH_STOP};
}
-
////
//// Functions
////
/// search captures, promotions and some checks) and about how important good
/// move ordering is at the current node.
-MovePicker::MovePicker(const Position& p, bool pv, Move ttm,
- const SearchStack& ss, Depth d) : pos(p) {
- pvNode = pv;
- ttMove = ttm;
- mateKiller = (ss.mateKiller == ttm)? MOVE_NONE : ss.mateKiller;
- killer1 = ss.killers[0];
- killer2 = ss.killers[1];
- depth = d;
- movesPicked = 0;
- numOfMoves = 0;
- numOfBadCaptures = 0;
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d,
+ const History& h, SearchStack* ss, bool useNullMove) : pos(p), H(h) {
+ ttMoves[0] = ttm;
+ if (ss)
+ {
+ ttMoves[1] = (ss->mateKiller == ttm)? MOVE_NONE : ss->mateKiller;
+ killers[0] = ss->killers[0];
+ killers[1] = ss->killers[1];
+ } else
+ ttMoves[1] = killers[0] = killers[1] = MOVE_NONE;
+
+ movesPicked = numOfMoves = numOfBadCaptures = 0;
+ finished = false;
if (p.is_check())
- phaseIndex = EvasionsPhaseIndex;
- else if (depth > Depth(0))
- phaseIndex = MainSearchPhaseIndex;
- else if (depth == Depth(0))
- phaseIndex = QsearchWithChecksPhaseIndex;
+ phasePtr = EvasionsPhaseTable;
+ else if (d > Depth(0))
+ phasePtr = MainSearchPhaseTable;
+ else if (d == Depth(0))
+ phasePtr = QsearchWithChecksPhaseTable;
else
- phaseIndex = QsearchWithoutChecksPhaseIndex;
+ phasePtr = QsearchWithoutChecksPhaseTable;
Color us = pos.side_to_move();
dc = p.discovered_check_candidates(us);
pinned = p.pinned_pieces(us);
-
- finished = false;
}
}
// 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;
- }
+ phasePtr++;
+ switch (*phasePtr) {
+
+ case PH_NULL_MOVE:
break;
- case PH_MATE_KILLER:
- if (mateKiller != MOVE_NONE)
- {
- assert(move_is_ok(mateKiller));
- if (move_is_legal(pos, mateKiller, pinned))
- return mateKiller;
- }
+ case PH_TT_MOVES:
+ movesPicked = 0; // This is used as index to ttMoves[]
break;
case PH_GOOD_CAPTURES:
numOfMoves = generate_captures(pos, moves);
score_captures();
+ std::sort(moves, moves + numOfMoves);
movesPicked = 0;
break;
- case PH_BAD_CAPTURES:
- movesPicked = 0;
+ case PH_KILLERS:
+ movesPicked = 0; // This is used as index to killers[]
break;
case PH_NONCAPTURES:
numOfMoves = generate_noncaptures(pos, moves);
score_noncaptures();
+ std::sort(moves, moves + numOfMoves);
+ movesPicked = 0;
+ break;
+
+ case PH_BAD_CAPTURES:
+ // Bad captures SEE value is already calculated so just sort them
+ // to get SEE move ordering.
+ std::sort(badCaptures, badCaptures + numOfBadCaptures);
movesPicked = 0;
break;
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();
+ score_captures();
+ std::sort(moves, moves + numOfMoves);
movesPicked = 0;
break;
case PH_QCHECKS:
- numOfMoves = generate_checks(pos, moves, dc);
+ // Perhaps we should order moves move here? FIXME
+ numOfMoves = generate_non_capture_checks(pos, moves, dc);
movesPicked = 0;
break;
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
+ // 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
+ // 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.
+ // 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;
- int seeValue;
+ // Use MVV/LVA ordering
for (int i = 0; i < numOfMoves; i++)
{
m = moves[i].move;
- seeValue = pos.see(m);
- if (seeValue >= 0)
- {
- 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)));
- }
+ if (move_is_promotion(m))
+ moves[i].score = QueenValueMidgame;
else
- {
- // Losing capture, move it to the badCaptures[] array
- assert(numOfBadCaptures < 63);
- moves[i].score = seeValue;
- badCaptures[numOfBadCaptures++] = moves[i];
- moves[i--] = moves[--numOfMoves];
- }
+ moves[i].score = int(pos.midgame_value_of_piece_on(move_to(m)))
+ -int(pos.type_of_piece_on(move_from(m)));
}
}
// 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;
for (int i = 0; i < numOfMoves; i++)
{
- m = moves[i].move;
-
- if (m == killer1)
- hs = HistoryMax + 2;
- else if (m == killer2)
- hs = HistoryMax + 1;
- else
- hs = H.move_ordering_score(pos.piece_on(move_from(m)), m);
+ from = move_from(moves[i].move);
+ to = move_to(moves[i].move);
+ 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
- moves[i].score = hs + pos.mg_pst_delta(m);
+ moves[i].score = hs + pos.pst_delta<Position::MidGame>(piece, from, to);
}
}
for (int i = 0; i < numOfMoves; i++)
{
Move m = moves[i].move;
- if (m == ttMove)
+ if (m == ttMoves[0])
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)), m);
- }
-}
-
-void MovePicker::score_qcaptures() {
-
- // 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)));
+ moves[i].score = H.move_ordering_score(pos.piece_on(move_from(m)), move_to(m));
}
}
-/// find_best_index() loops across the moves and returns index of
-/// the highest scored one. There is also a second version that
-/// lowers the priority of moves that attack the same square,
-/// so that if the best move that attack a square fails the next
-/// move picked attacks a different square if any, not the same one.
-
-int MovePicker::find_best_index() {
-
- assert(movesPicked < numOfMoves);
-
- int bestIndex = movesPicked, bestScore = moves[movesPicked].score;
-
- for (int i = movesPicked + 1; i < numOfMoves; i++)
- if (moves[i].score > bestScore)
- {
- bestIndex = i;
- bestScore = moves[i].score;
- }
- return bestIndex;
-}
-
-int MovePicker::find_best_index(Bitboard* squares, int values[]) {
-
- assert(movesPicked < numOfMoves);
-
- int hs;
- Move m;
- Square to;
- int bestScore = -10000000, bestIndex = -1;
-
- for (int i = movesPicked; i < numOfMoves; i++)
- {
- m = moves[i].move;
- to = move_to(m);
-
- if (!bit_is_set(*squares, to))
- {
- // Init at first use
- set_bit(squares, to);
- values[to] = 0;
- }
-
- hs = moves[i].score - values[to];
- if (hs > bestScore)
- {
- bestIndex = i;
- bestScore = hs;
- }
- }
-
- if (bestIndex != -1)
- {
- // Raise value of the picked square, so next attack
- // to the same square will get low priority.
- to = move_to(moves[bestIndex].move);
- values[to] += 0xB00;
- }
- return bestIndex;
-}
-
-
/// 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
Move MovePicker::pick_move_from_list() {
- int bestIndex;
- Move move;
+ assert(movesPicked >= 0);
+ assert(!pos.is_check() || *phasePtr == PH_EVASIONS || *phasePtr == PH_STOP);
+ assert( pos.is_check() || *phasePtr != PH_EVASIONS);
- switch (PhaseTable[phaseIndex]) {
+ switch (*phasePtr) {
- case PH_GOOD_CAPTURES:
- assert(!pos.is_check());
- assert(movesPicked >= 0);
+ case PH_TT_MOVES:
+ while (movesPicked < 2) {
+ Move move = ttMoves[movesPicked++];
+ if ( move != MOVE_NONE
+ && move_is_legal(pos, move, pinned))
+ return move;
+ }
+ break;
+ case PH_GOOD_CAPTURES:
while (movesPicked < numOfMoves)
{
- bestIndex = find_best_index();
- move = moves[bestIndex].move;
- moves[bestIndex] = moves[movesPicked++];
- if ( move != ttMove
- && move != mateKiller
+ Move move = moves[movesPicked++].move;
+ if ( move != ttMoves[0]
+ && move != ttMoves[1]
&& pos.pl_move_is_legal(move, pinned))
- return move;
+ {
+ // 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;
+ }
}
break;
- case PH_NONCAPTURES:
- assert(!pos.is_check());
- assert(movesPicked >= 0);
+ case PH_KILLERS:
+ while (movesPicked < 2) {
+ Move move = killers[movesPicked++];
+ if ( move != MOVE_NONE
+ && move != ttMoves[0]
+ && move != ttMoves[1]
+ && move_is_legal(pos, move, pinned)
+ && !pos.move_is_capture(move))
+ return move;
+ }
+ break;
+ case PH_NONCAPTURES:
while (movesPicked < numOfMoves)
{
- // If this is a PV node or we have only picked a few moves, scan
- // the entire move list for the best move. If many moves have already
- // been searched and it is not a PV node, we are probably failing low
- // anyway, so we just pick the first move from the list.
- bestIndex = (pvNode || movesPicked < 12) ? find_best_index() : movesPicked;
- move = moves[bestIndex].move;
- moves[bestIndex] = moves[movesPicked++];
- if ( move != ttMove
- && move != mateKiller
+ Move move = moves[movesPicked++].move;
+ if ( move != ttMoves[0]
+ && move != ttMoves[1]
+ && move != killers[0]
+ && move != killers[1]
&& pos.pl_move_is_legal(move, pinned))
return move;
}
break;
case PH_EVASIONS:
- assert(pos.is_check());
- assert(movesPicked >= 0);
-
- while (movesPicked < numOfMoves)
- {
- bestIndex = find_best_index();
- move = moves[bestIndex].move;
- moves[bestIndex] = moves[movesPicked++];
- return move;
- }
- break;
+ if (movesPicked < numOfMoves)
+ return moves[movesPicked++].move;
+ break;
case PH_BAD_CAPTURES:
- assert(!pos.is_check());
- assert(movesPicked >= 0);
- // It's probably a good idea to use SEE move ordering here, instead
- // of just picking the first move. FIXME
- while (movesPicked < numOfBadCaptures)
- {
- move = badCaptures[movesPicked++].move;
- if ( move != ttMove
- && move != mateKiller
- && pos.pl_move_is_legal(move, pinned))
- return move;
- }
+ if (movesPicked < numOfBadCaptures)
+ return badCaptures[movesPicked++].move;
break;
case PH_QCAPTURES:
- assert(!pos.is_check());
- assert(movesPicked >= 0);
- while (movesPicked < numOfMoves)
- {
- bestIndex = (movesPicked < 4 ? find_best_index() : movesPicked);
- move = moves[bestIndex].move;
- moves[bestIndex] = moves[movesPicked++];
- // Remember to change the line below if we decide to hash the qsearch!
- // Maybe also postpone the legality check until after futility pruning?
- if (/* move != ttMove && */ pos.pl_move_is_legal(move, pinned))
- return move;
- }
- break;
-
case PH_QCHECKS:
- assert(!pos.is_check());
- assert(movesPicked >= 0);
- // Perhaps we should do something better than just picking the first
- // move here? FIXME
while (movesPicked < numOfMoves)
{
- move = moves[movesPicked++].move;
- // Remember to change the line below if we decide to hash the qsearch!
- if (/* move != ttMove && */ pos.pl_move_is_legal(move, pinned))
+ Move move = moves[movesPicked++].move;
+ // Maybe postpone the legality check until after futility pruning?
+ if ( move != ttMoves[0]
+ && pos.pl_move_is_legal(move, pinned))
return move;
}
break;
}
return MOVE_NONE;
}
-
-
-/// MovePicker::current_move_type() returns the type of the just
-/// picked next move. It can be used in search to further differentiate
-/// according to the current move type: capture, non capture, escape, etc.
-MovePicker::MovegenPhase MovePicker::current_move_type() const {
-
- return PhaseTable[phaseIndex];
-}
-
-
-/// MovePicker::init_phase_table() initializes the PhaseTable[],
-/// MainSearchPhaseIndex, EvasionPhaseIndex, QsearchWithChecksPhaseIndex
-/// QsearchNoCapturesPhaseIndex, QsearchWithoutChecksPhaseIndex and
-/// NoMovesPhaseIndex variables. 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;
- // PH_KILLER_1 and PH_KILLER_2 are not yet used.
- // PhaseTable[i++] = PH_KILLER_1;
- // PhaseTable[i++] = PH_KILLER_2;
- 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_QCAPTURES;
- PhaseTable[i++] = PH_QCHECKS;
- PhaseTable[i++] = PH_STOP;
-
- // Quiescence search without checks
- QsearchWithoutChecksPhaseIndex = i - 1;
- PhaseTable[i++] = PH_QCAPTURES;
- PhaseTable[i++] = PH_STOP;
-
-}