X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=5163e87ca67710ed14f92224075e215ae2c6d85e;hp=ea332b7be37b4ae4b73be30ea8fa9277d5660ff2;hb=3a2cd370802db61dc3060b81d613444363cf0371;hpb=ef6fca98a0b70b82ba701e6969a80cd9daf78705

diff --git a/src/movepick.cpp b/src/movepick.cpp
index ea332b7b..5163e87c 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
@@ -70,18 +70,18 @@ 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;
+  badCaptureThreshold = 0;
   lastBadCapture = badCaptures;
 
   pinned = p.pinned_pieces(pos.side_to_move());
 
   if (ss && !p.is_check())
   {
-      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];
@@ -91,13 +91,28 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d,
   if (p.is_check())
       phasePtr = EvasionsPhaseTable;
   else if (d > Depth(0))
+  {
+      // Consider sligtly negative captures as good if at low
+      // depth and far from beta.
+      if (ss && ss->eval < beta - PawnValueMidgame && d < 3 * OnePly)
+          badCaptureThreshold = -PawnValueMidgame;
+
       phasePtr = MainSearchPhaseTable;
+  }
   else if (d == Depth(0))
       phasePtr = QsearchWithChecksPhaseTable;
   else
+  {
       phasePtr = QsearchWithoutChecksPhaseTable;
 
-  phasePtr += !searchTT - 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_or_promotion(ttm))
+          searchTT = ttMoves[0].move = MOVE_NONE;
+  }
+
+  phasePtr += int(!searchTT) - 1;
   go_next_phase();
 }
 
@@ -129,7 +144,7 @@ void MovePicker::go_next_phase() {
   case PH_NONCAPTURES:
       lastMove = generate_noncaptures(pos, moves);
       score_noncaptures();
-      sort_moves(moves, lastMove);
+      sort_moves(moves, lastMove, &lastGoodNonCapture);
       return;
 
   case PH_BAD_CAPTURES:
@@ -142,7 +157,7 @@ void MovePicker::go_next_phase() {
   case PH_EVASIONS:
       assert(pos.is_check());
       lastMove = generate_evasions(pos, moves);
-      score_evasions();
+      score_evasions_or_checks();
       return;
 
   case PH_QCAPTURES:
@@ -151,12 +166,12 @@ void MovePicker::go_next_phase() {
       return;
 
   case PH_QCHECKS:
-      // Perhaps we should order moves move here?  FIXME
       lastMove = generate_non_capture_checks(pos, moves);
+      score_evasions_or_checks();
       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 +221,6 @@ void MovePicker::score_noncaptures() {
   Move m;
   Piece piece;
   Square from, to;
-  int hs;
 
   for (MoveStack* cur = moves; cur != lastMove; cur++)
   {
@@ -214,18 +228,11 @@ 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 + mg_value(pos.pst_delta(piece, from, to));
+      cur->score = H.value(piece, to) + H.gain(piece, to);
   }
 }
 
-void MovePicker::score_evasions() {
+void MovePicker::score_evasions_or_checks() {
   // 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
@@ -233,16 +240,20 @@ void MovePicker::score_evasions() {
   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 ((seeScore = pos.see_sign(m)) < 0)
-          cur->score = seeScore;
+          cur->score = seeScore - HistoryMax; // Be sure 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;
       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));
   }
 }
 
@@ -251,6 +262,8 @@ 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() {
 
@@ -277,7 +290,7 @@ 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
@@ -292,14 +305,19 @@ Move MovePicker::get_next_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;
 
           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
@@ -340,21 +358,3 @@ Move MovePicker::get_next_move() {
   }
 }
 
-/// 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;
-}