X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fmovepick.cpp;h=a7e5bdac78ba0a9bf17304de41380cd667a9f5f6;hb=95212222c7444538b84326208e433ac12f15e9fb;hp=a9cc245dcb570702d316f4736152d550457fbef2;hpb=9ab84a816539ade23868f0383e39634e6ab88df5;p=stockfish
diff --git a/src/movepick.cpp b/src/movepick.cpp
index a9cc245d..a7e5bdac 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) 2008-2009 Marco Costalba
+ Copyright (C) 2008-2010 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
@@ -18,12 +18,6 @@
along with this program. If not, see .
*/
-
-////
-//// Includes
-////
-
-#include
#include
#include "history.h"
@@ -32,28 +26,28 @@
#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
+ };
+
CACHE_LINE_ALIGNMENT
- const MovegenPhaseT MainSearchPhaseTable[] = { PH_NULL_MOVE, PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP};
- const MovegenPhaseT MainSearchNoNullPhaseTable[] = { PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP};
- const MovegenPhaseT LowSearchPhaseTable[] = { PH_TT_MOVES, PH_NULL_MOVE, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP};
- const MovegenPhaseT EvasionsPhaseTable[] = { PH_EVASIONS, PH_STOP};
- const MovegenPhaseT QsearchWithChecksPhaseTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_QCHECKS, PH_STOP};
- const MovegenPhaseT QsearchWithoutChecksPhaseTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_STOP};
+ const uint8_t MainSearchPhaseTable[] = { PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP};
+ const uint8_t EvasionsPhaseTable[] = { PH_TT_MOVES, 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};
}
-////
-//// Functions
-////
-
-
/// 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
@@ -61,37 +55,67 @@ namespace {
/// 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, bool useNullMove) : pos(p), H(h) {
+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;
- if (ss)
+ badCaptureThreshold = 0;
+ badCaptures = moves + MOVES_MAX;
+
+ assert(d > DEPTH_ZERO);
+
+ pinned = p.pinned_pieces(pos.side_to_move());
+
+ if (p.is_check())
+ {
+ ttMoves[1].move = killers[0].move = killers[1].move = MOVE_NONE;
+ phasePtr = EvasionsPhaseTable;
+ }
+ else
{
- ttMoves[1].move = (ss->mateKiller == ttm)? MOVE_NONE : ss->mateKiller;
+ 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;
- finished = false;
- numOfBadCaptures = 0;
+ // 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;
+
+ phasePtr = MainSearchPhaseTable;
+ }
+
+ phasePtr += int(!searchTT) - 1;
+ go_next_phase();
+}
- Color us = pos.side_to_move();
+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;
- dc = p.discovered_check_candidates(us);
- pinned = p.pinned_pieces(us);
+ assert(d <= DEPTH_ZERO);
+
+ pinned = p.pinned_pieces(pos.side_to_move());
if (p.is_check())
phasePtr = EvasionsPhaseTable;
- else if (d >= Depth(3 * OnePly))
- phasePtr = useNullMove ? MainSearchPhaseTable : MainSearchNoNullPhaseTable;
- else if (d > Depth(0))
- phasePtr = useNullMove ? LowSearchPhaseTable : MainSearchNoNullPhaseTable;
- else if (d == Depth(0))
+ else if (d >= DEPTH_QS_CHECKS)
phasePtr = QsearchWithChecksPhaseTable;
else
+ {
phasePtr = QsearchWithoutChecksPhaseTable;
- phasePtr--;
+ // 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_or_promotion(ttm))
+ searchTT = ttMoves[0].move = MOVE_NONE;
+ }
+
+ phasePtr += int(!searchTT) - 1;
go_next_phase();
}
@@ -105,18 +129,14 @@ void MovePicker::go_next_phase() {
phase = *(++phasePtr);
switch (phase) {
- case PH_NULL_MOVE:
- return;
-
case PH_TT_MOVES:
curMove = ttMoves;
lastMove = curMove + 2;
return;
case PH_GOOD_CAPTURES:
- lastMove = generate_captures(pos, moves);
+ lastMove = generate(pos, moves);
score_captures();
- std::sort(moves, lastMove);
return;
case PH_KILLERS:
@@ -125,38 +145,35 @@ void MovePicker::go_next_phase() {
return;
case PH_NONCAPTURES:
- lastMove = generate_noncaptures(pos, moves);
+ lastMove = generate(pos, moves);
score_noncaptures();
- std::sort(moves, lastMove);
+ sort_moves(moves, lastMove, &lastGoodNonCapture);
return;
case PH_BAD_CAPTURES:
- // Bad captures SEE value is already calculated so just sort them
- // to get SEE move ordering.
+ // Bad captures SEE value is already calculated so just pick
+ // them in order to get SEE move ordering.
curMove = badCaptures;
- lastMove = badCaptures + numOfBadCaptures;
- std::sort(badCaptures, lastMove);
+ lastMove = moves + MOVES_MAX;
return;
case PH_EVASIONS:
assert(pos.is_check());
- lastMove = generate_evasions(pos, moves, pinned);
+ lastMove = generate(pos, moves);
score_evasions();
- std::sort(moves, lastMove);
return;
case PH_QCAPTURES:
- lastMove = generate_captures(pos, moves);
+ lastMove = generate(pos, moves);
score_captures();
- std::sort(moves, lastMove);
return;
case PH_QCHECKS:
- // Perhaps we should order moves move here? FIXME
- lastMove = generate_non_capture_checks(pos, moves, dc);
+ lastMove = generate(pos, moves);
return;
case PH_STOP:
+ lastMove = curMove + 1; // Avoids another go_next_phase() call
return;
default:
@@ -194,8 +211,8 @@ void MovePicker::score_captures() {
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)));
+ cur->score = pos.midgame_value_of_piece_on(move_to(m))
+ - pos.type_of_piece_on(move_from(m));
}
}
@@ -206,7 +223,6 @@ void MovePicker::score_noncaptures() {
Move m;
Piece piece;
Square from, to;
- int hs;
for (MoveStack* cur = moves; cur != lastMove; cur++)
{
@@ -214,32 +230,32 @@ void MovePicker::score_noncaptures() {
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);
+ cur->score = H.value(piece, to) + H.gain(piece, to);
}
}
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.
Move m;
+ int seeScore;
+
+ // Skip if we don't have at least two moves to order
+ if (lastMove < moves + 2)
+ return;
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)))
- {
- 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 ((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
+ cur->score = H.value(pos.piece_on(move_from(m)), move_to(m));
}
}
@@ -247,123 +263,97 @@ void MovePicker::score_evasions() {
/// 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 that has already been serched previously.
+/// 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() {
- assert(!pos.is_check() || *phasePtr == PH_EVASIONS || *phasePtr == PH_STOP);
- assert( pos.is_check() || *phasePtr != PH_EVASIONS);
+ Move move;
while (true)
{
- switch (phase) {
-
- case PH_NULL_MOVE:
- go_next_phase();
- return MOVE_NULL;
+ while (curMove != lastMove)
+ {
+ switch (phase) {
- case PH_TT_MOVES:
- while (curMove != lastMove)
- {
- Move move = (curMove++)->move;
+ case PH_TT_MOVES:
+ move = (curMove++)->move;
if ( move != MOVE_NONE
&& move_is_legal(pos, move, pinned))
return move;
- }
- break;
+ break;
- case PH_GOOD_CAPTURES:
- while (curMove != lastMove)
- {
- Move move = (curMove++)->move;
+ 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))
{
// Check for a non negative SEE now
int seeValue = pos.see_sign(move);
- if (seeValue >= 0)
+ if (seeValue >= badCaptureThreshold)
return move;
- // Losing capture, move it to the badCaptures[] array, note
+ // Losing capture, move it to the tail of the array, note
// that move has now been already checked for legality.
- assert(numOfBadCaptures < 63);
- badCaptures[numOfBadCaptures].move = move;
- badCaptures[numOfBadCaptures++].score = seeValue;
+ (--badCaptures)->move = move;
+ badCaptures->score = seeValue;
}
- }
- break;
+ break;
- case PH_KILLERS:
- while (curMove != lastMove)
- {
- Move move = (curMove++)->move;
+ case PH_KILLERS:
+ move = (curMove++)->move;
if ( move != MOVE_NONE
+ && move_is_legal(pos, move, pinned)
&& move != ttMoves[0].move
&& move != ttMoves[1].move
- && move_is_legal(pos, move, pinned)
&& !pos.move_is_capture(move))
return move;
- }
- break;
+ break;
+
+ case PH_NONCAPTURES:
+
+ // Sort negative scored moves only when we get there
+ if (curMove == lastGoodNonCapture)
+ insertion_sort(lastGoodNonCapture, lastMove);
- case PH_NONCAPTURES:
- while (curMove != lastMove)
- {
- Move move = (curMove++)->move;
+ move = (curMove++)->move;
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:
- if (curMove != lastMove)
- return (curMove++)->move;
- break;
-
- case PH_QCAPTURES:
- case PH_QCHECKS:
- while (curMove != lastMove)
- {
- Move move = (curMove++)->move;
- // Maybe postpone the legality check until after futility pruning?
+ break;
+
+ case PH_BAD_CAPTURES:
+ move = pick_best(curMove++, lastMove).move;
+ return 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))
return move;
- }
- break;
+ break;
+
+ case PH_QCHECKS:
+ move = (curMove++)->move;
+ if ( move != ttMoves[0].move
+ && pos.pl_move_is_legal(move, pinned))
+ return move;
+ break;
- case PH_STOP:
- return MOVE_NONE;
+ case PH_STOP:
+ return MOVE_NONE;
- default:
- assert(false);
- break;
+ default:
+ assert(false);
+ break;
+ }
}
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.
-
-Move MovePicker::get_next_move(Lock &lock) {
-
- lock_grab(&lock);
- if (finished)
- {
- lock_release(&lock);
- return MOVE_NONE;
- }
- Move m = get_next_move();
- if (m == MOVE_NONE)
- finished = true;
-
- lock_release(&lock);
- return m;
-}