X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=a7e5bdac78ba0a9bf17304de41380cd667a9f5f6;hp=26627474536f37bd6e8f859ceb7a2cd909ef7dcd;hb=afae86bfb49471113f14f9f0f56f2a08d052242f;hpb=94dcac1feeb142a56ed2ebddb96ef672460f1d49
diff --git a/src/movepick.cpp b/src/movepick.cpp
index 26627474..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
@@ -18,11 +18,6 @@
along with this program. If not, see .
*/
-
-////
-//// Includes
-////
-
#include
#include "history.h"
@@ -31,11 +26,6 @@
#include "search.h"
#include "value.h"
-
-////
-//// Local definitions
-////
-
namespace {
enum MovegenPhase {
@@ -52,17 +42,12 @@ namespace {
CACHE_LINE_ALIGNMENT
const uint8_t MainSearchPhaseTable[] = { PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP};
- const uint8_t EvasionsPhaseTable[] = { PH_EVASIONS, 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
@@ -70,34 +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) : 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;
- finished = false;
- lastBadCapture = badCaptures;
+ badCaptureThreshold = 0;
+ badCaptures = moves + MOVES_MAX;
- if (ss)
+ 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;
+
+ // 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();
+}
+
+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;
+
+ assert(d <= DEPTH_ZERO);
pinned = p.pinned_pieces(pos.side_to_move());
if (p.is_check())
phasePtr = EvasionsPhaseTable;
- else if (d > Depth(0))
- phasePtr = MainSearchPhaseTable + !searchTT;
- else if (d == Depth(0))
- phasePtr = QsearchWithChecksPhaseTable + !searchTT;
+ else if (d >= DEPTH_QS_CHECKS)
+ phasePtr = QsearchWithChecksPhaseTable;
else
- phasePtr = QsearchWithoutChecksPhaseTable + !searchTT;
+ {
+ 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();
}
@@ -117,7 +135,7 @@ void MovePicker::go_next_phase() {
return;
case PH_GOOD_CAPTURES:
- lastMove = generate_captures(pos, moves);
+ lastMove = generate(pos, moves);
score_captures();
return;
@@ -127,36 +145,35 @@ void MovePicker::go_next_phase() {
return;
case PH_NONCAPTURES:
- lastMove = generate_noncaptures(pos, moves);
+ lastMove = generate(pos, moves);
score_noncaptures();
- sort_moves(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 = lastBadCapture;
+ lastMove = moves + MOVES_MAX;
return;
case PH_EVASIONS:
assert(pos.is_check());
- lastMove = generate_evasions(pos, moves);
+ lastMove = generate(pos, moves);
score_evasions();
return;
case PH_QCAPTURES:
- lastMove = generate_captures(pos, moves);
+ lastMove = generate(pos, moves);
score_captures();
return;
case PH_QCHECKS:
- // Perhaps we should order moves move here? FIXME
- lastMove = generate_non_capture_checks(pos, moves);
+ lastMove = generate(pos, moves);
return;
case PH_STOP:
- lastMove = curMove + 1; // hack to be friendly for get_next_move()
+ lastMove = curMove + 1; // Avoids another go_next_phase() call
return;
default:
@@ -206,7 +223,6 @@ void MovePicker::score_noncaptures() {
Move m;
Piece piece;
Square from, to;
- int hs;
for (MoveStack* cur = moves; cur != lastMove; cur++)
{
@@ -214,38 +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() {
- // Always try ttMove as first. Then 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, 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 ((seeScore = pos.see_sign(m)) < 0)
- cur->score = seeScore;
+ 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)) + HistoryMax;
+ - pos.type_of_piece_on(move_from(m)) + History::MaxValue;
else
- cur->score = H.move_ordering_score(pos.piece_on(move_from(m)), move_to(m));
+ cur->score = H.value(pos.piece_on(move_from(m)), move_to(m));
}
}
@@ -254,12 +264,11 @@ void MovePicker::score_evasions() {
/// 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() {
- assert(!pos.is_check() || *phasePtr == PH_EVASIONS || *phasePtr == PH_STOP);
- assert( pos.is_check() || *phasePtr != PH_EVASIONS);
-
Move move;
while (true)
@@ -283,29 +292,32 @@ Move MovePicker::get_next_move() {
{
// 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(int(lastBadCapture - badCaptures) < 63);
- lastBadCapture->move = move;
- lastBadCapture->score = seeValue;
- lastBadCapture++;
+ (--badCaptures)->move = move;
+ badCaptures->score = seeValue;
}
break;
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;
case PH_NONCAPTURES:
+
+ // Sort negative scored moves only when we get there
+ if (curMove == lastGoodNonCapture)
+ insertion_sort(lastGoodNonCapture, lastMove);
+
move = (curMove++)->move;
if ( move != ttMoves[0].move
&& move != ttMoves[1].move
@@ -320,11 +332,6 @@ Move MovePicker::get_next_move() {
return move;
case PH_EVASIONS:
- move = pick_best(curMove++, lastMove).move;
- if (pos.pl_move_is_legal(move, pinned))
- return move;
- break;
-
case PH_QCAPTURES:
move = pick_best(curMove++, lastMove).move;
if ( move != ttMoves[0].move
@@ -350,22 +357,3 @@ Move MovePicker::get_next_move() {
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;
-}