Delay SEE for scoring captures

[stockfish] / src / movepick.cpp

diff --git a/src/movepick.cpp b/src/movepick.cpp
index 6525c7506b8b180cc9f36574c6cc22452c2d96a4..c71572e7cf86bead8aa853dd16db512ab329e55d 100644 (file)
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -8,6 +8,7 @@
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
 
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
 

+

   Stockfish is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   Stockfish is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the


@@ -39,7 +40,7 @@ namespace {
 
   /// Variables
 
 
   /// Variables
 

-  MovePicker::MovegenPhase PhaseTable[32];  
+  MovePicker::MovegenPhase PhaseTable[32];

   int MainSearchPhaseIndex;
   int EvasionsPhaseIndex;
   int QsearchWithChecksPhaseIndex;
   int MainSearchPhaseIndex;
   int EvasionsPhaseIndex;
   int QsearchWithChecksPhaseIndex;


@@ -61,9 +62,8 @@ namespace {
 /// search captures, promotions and some checks) and about how important good
 /// move ordering is at the current node.
 
 /// search captures, promotions and some checks) and about how important good
 /// move ordering is at the current node.
 

-MovePicker::MovePicker(Position& p, bool pvnode, Move ttm, Move mk,
-                       Move k1, Move k2, Depth d) {
-  pos = &p;
+MovePicker::MovePicker(const Position& p, bool pvnode, Move ttm, Move mk,
+                       Move k1, Move k2, Depth d) : pos(p) {

   pvNode = pvnode;
   ttMove = ttm;
   mateKiller = (mk == ttm)? MOVE_NONE : mk;
   pvNode = pvnode;
   ttMove = ttm;
   mateKiller = (mk == ttm)? MOVE_NONE : mk;


@@ -112,16 +112,13 @@ Move MovePicker::get_next_move() {
     // Next phase
     phaseIndex++;
     switch (PhaseTable[phaseIndex]) {
     // Next phase
     phaseIndex++;
     switch (PhaseTable[phaseIndex]) {

+

     case PH_TT_MOVE:
         if (ttMove != MOVE_NONE)
         {
             assert(move_is_ok(ttMove));
     case PH_TT_MOVE:
         if (ttMove != MOVE_NONE)
         {
             assert(move_is_ok(ttMove));

-            Move m = generate_move_if_legal(*pos, ttMove, pinned);
-            if (m != MOVE_NONE)
-            {
-                assert(m == ttMove);
-                return m;
-            }
+            if (move_is_legal(pos, ttMove, pinned))
+                return ttMove;

         }
         break;
 
         }
         break;
 


@@ -129,17 +126,13 @@ Move MovePicker::get_next_move() {
         if (mateKiller != MOVE_NONE)
         {
             assert(move_is_ok(mateKiller));
         if (mateKiller != MOVE_NONE)
         {
             assert(move_is_ok(mateKiller));

-            Move m = generate_move_if_legal(*pos, mateKiller, pinned);
-            if (m != MOVE_NONE)
-            {
-                assert(m == mateKiller);
-                return m;
-            }
+            if (move_is_legal(pos, mateKiller, pinned))
+                return mateKiller;

        }
        break;
 
     case PH_GOOD_CAPTURES:
        }
        break;
 
     case PH_GOOD_CAPTURES:

-        numOfMoves = generate_captures(*pos, moves);
+        numOfMoves = generate_captures(pos, moves);

         score_captures();
         movesPicked = 0;
         break;
         score_captures();
         movesPicked = 0;
         break;


@@ -149,26 +142,26 @@ Move MovePicker::get_next_move() {
         break;
 
     case PH_NONCAPTURES:
         break;
 
     case PH_NONCAPTURES:

-        numOfMoves = generate_noncaptures(*pos, moves);
+        numOfMoves = generate_noncaptures(pos, moves);

         score_noncaptures();
         movesPicked = 0;
         break;
 
     case PH_EVASIONS:
         score_noncaptures();
         movesPicked = 0;
         break;
 
     case PH_EVASIONS:

-        assert(pos->is_check());      
-        numOfMoves = generate_evasions(*pos, moves);
+        assert(pos.is_check());
+        numOfMoves = generate_evasions(pos, moves);

         score_evasions();
         movesPicked = 0;
         break;
 
         score_evasions();
         movesPicked = 0;
         break;
 

-    case PH_QCAPTURES:      
-        numOfMoves = generate_captures(*pos, moves);
+    case PH_QCAPTURES:
+        numOfMoves = generate_captures(pos, moves);

         score_qcaptures();
         movesPicked = 0;
         break;
 
     case PH_QCHECKS:
         score_qcaptures();
         movesPicked = 0;
         break;
 
     case PH_QCHECKS:

-        numOfMoves = generate_checks(*pos, moves, dc);
+        numOfMoves = generate_checks(pos, moves, dc);

         movesPicked = 0;
         break;
 
         movesPicked = 0;
         break;
 


@@ -180,8 +173,6 @@ Move MovePicker::get_next_move() {
         return MOVE_NONE;
     }
   }
         return MOVE_NONE;
     }
   }

-  assert(false);
-  return MOVE_NONE;

 }
 
 
 }
 
 


@@ -190,19 +181,17 @@ Move MovePicker::get_next_move() {
 
 Move MovePicker::get_next_move(Lock &lock) {
 
 
 Move MovePicker::get_next_move(Lock &lock) {
 

-   Move m;
-

    lock_grab(&lock);
    if (finished)
    {
        lock_release(&lock);
        return MOVE_NONE;
    }
    lock_grab(&lock);
    if (finished)
    {
        lock_release(&lock);
        return MOVE_NONE;
    }

-   m = get_next_move();
+   Move m = get_next_move();

    if (m == MOVE_NONE)
        finished = true;
 
    if (m == MOVE_NONE)
        finished = true;
 

-   lock_release(&lock);   
+   lock_release(&lock);

    return m;
 }
 
    return m;
 }
 


@@ -217,37 +206,48 @@ void MovePicker::score_captures() {
   // Suprisingly, this appears to perform slightly better than SEE based
   // move ordering.  The reason is probably that in a position with a winning
   // capture, capturing a more valuable (but sufficiently defended) piece
   // Suprisingly, this appears to perform slightly better than SEE based
   // 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
   // the hanging piece will still be hanging (except in the unusual cases

-  // where it is possible to recapture with the hanging piece).  Exchanging
+  // where it is possible to recapture with the hanging piece). Exchanging

   // big pieces before capturing a hanging piece probably helps to reduce
   // big pieces before capturing a hanging piece probably helps to reduce

-  // the subtree size.
+  // the subtree size. Instead of calculating SEE here to filter out 
+  // loosing captures, we delay the filtering in pick_move_from_list()
+  Move m;
+

   for (int i = 0; i < numOfMoves; i++)
   {
   for (int i = 0; i < numOfMoves; i++)
   {

-      int seeValue = pos->see(moves[i].move);
-      if (seeValue >= 0)
-      {
-          if (move_promotion(moves[i].move))
-              moves[i].score = QueenValueMidgame;
-          else
-              moves[i].score = int(pos->midgame_value_of_piece_on(move_to(moves[i].move)))
-                              -int(pos->type_of_piece_on(move_from(moves[i].move)));
-      } else
-          moves[i].score = seeValue;
+      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)));

   }
 }
 
 void MovePicker::score_noncaptures() {
   }
 }
 
 void MovePicker::score_noncaptures() {

+  // 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;
+  int hs;

 
   for (int i = 0; i < numOfMoves; i++)
   {
 
   for (int i = 0; i < numOfMoves; i++)
   {

-      Move m = moves[i].move;
+      m = moves[i].move;
+

       if (m == killer1)
       if (m == killer1)

-          moves[i].score = HistoryMax + 2;
+          hs = HistoryMax + 2;

       else if (m == killer2)
       else if (m == killer2)

-          moves[i].score = HistoryMax + 1;
+          hs = HistoryMax + 1;

       else
       else

-         moves[i].score = H.move_ordering_score(pos->piece_on(move_from(m)), m);
+          hs = H.move_ordering_score(pos.piece_on(move_from(m)), m);
+
+      // Ensure moves in history are always sorted as first
+      if (hs > 0)
+          hs += 1000;
+
+      moves[i].score = hs + pos.mg_pst_delta(m);

   }
 }
 
   }
 }
 


@@ -258,12 +258,12 @@ void MovePicker::score_evasions() {
       Move m = moves[i].move;
       if (m == ttMove)
           moves[i].score = 2*HistoryMax;
       Move m = moves[i].move;
       if (m == ttMove)
           moves[i].score = 2*HistoryMax;

-      else if(!pos->square_is_empty(move_to(m)))
+      else if (!pos.square_is_empty(move_to(m)))

       {
       {

-          int seeScore = pos->see(m);
+          int seeScore = pos.see(m);

           moves[i].score = (seeScore >= 0)? seeScore + HistoryMax : seeScore;
       } else
           moves[i].score = (seeScore >= 0)? seeScore + HistoryMax : seeScore;
       } else

-          moves[i].score = H.move_ordering_score(pos->piece_on(move_from(m)), m);
+          moves[i].score = H.move_ordering_score(pos.piece_on(move_from(m)), m);

   }
   // FIXME try psqt also here
 }
   }
   // FIXME try psqt also here
 }


@@ -277,12 +277,29 @@ void MovePicker::score_qcaptures() {
       if (move_promotion(m))
           moves[i].score = QueenValueMidgame;
       else
       if (move_promotion(m))
           moves[i].score = QueenValueMidgame;
       else

-          moves[i].score = int(pos->midgame_value_of_piece_on(move_to(m)))
-                          -int(pos->midgame_value_of_piece_on(move_to(m))) / 64;
+          moves[i].score = int(pos.midgame_value_of_piece_on(move_to(m)))
+                          -int(pos.type_of_piece_on(move_from(m)));

   }
 }
 
 
   }
 }
 
 

+/// find_best_index() loops across the moves and returns index of
+/// the highest scored one.
+
+int MovePicker::find_best_index() {
+
+  int bestScore = -10000000, bestIndex = -1;
+
+  for (int i = movesPicked; i < numOfMoves; i++)
+      if (moves[i].score > bestScore)
+      {
+          bestIndex = i;
+          bestScore = moves[i].score;
+      }
+  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
 /// 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


@@ -293,69 +310,51 @@ void MovePicker::score_qcaptures() {
 
 Move MovePicker::pick_move_from_list() {
 
 
 Move MovePicker::pick_move_from_list() {
 

-  int bestScore = -10000000;

   int bestIndex;
   Move move;
 
   switch (PhaseTable[phaseIndex]) {
   case PH_GOOD_CAPTURES:
   int bestIndex;
   Move move;
 
   switch (PhaseTable[phaseIndex]) {
   case PH_GOOD_CAPTURES:

-      assert(!pos->is_check());
+      assert(!pos.is_check());

       assert(movesPicked >= 0);
 
       while (movesPicked < numOfMoves)
       {
       assert(movesPicked >= 0);
 
       while (movesPicked < numOfMoves)
       {

-          bestScore = -10000000;
-          bestIndex = -1;
-          for (int i = movesPicked; i < numOfMoves; i++)
+          bestIndex = find_best_index();
+
+          if (bestIndex != -1) // Found a possibly good capture

           {
           {

-              if (moves[i].score < 0)
+              move = moves[bestIndex].move;
+              int seeValue = pos.see(move);
+              if (seeValue < 0)

               {
                   // Losing capture, move it to the badCaptures[] array
                   assert(numOfBadCaptures < 63);
               {
                   // Losing capture, move it to the badCaptures[] array
                   assert(numOfBadCaptures < 63);

-                  badCaptures[numOfBadCaptures++] = moves[i];
-                  moves[i--] = moves[--numOfMoves];
-              }
-              else if (moves[i].score > bestScore)
-              {
-                  bestIndex = i;
-                  bestScore = moves[i].score;
+                  moves[bestIndex].score = seeValue;
+                  badCaptures[numOfBadCaptures++] = moves[bestIndex];
+                  moves[bestIndex] = moves[--numOfMoves];
+                  continue;

               }
               }

-          }
-          if (bestIndex != -1) // Found a good capture
-          {
-              move = moves[bestIndex].move;

               moves[bestIndex] = moves[movesPicked++];
               if (   move != ttMove
                   && move != mateKiller
               moves[bestIndex] = moves[movesPicked++];
               if (   move != ttMove
                   && move != mateKiller

-                  && pos->move_is_legal(move, pinned))
+                  && pos.pl_move_is_legal(move, pinned))

                   return move;
           }
       }
       break;
 
   case PH_NONCAPTURES:
                   return move;
           }
       }
       break;
 
   case PH_NONCAPTURES:

-      assert(!pos->is_check());
+      assert(!pos.is_check());

       assert(movesPicked >= 0);
 
       while (movesPicked < numOfMoves)
       {
       assert(movesPicked >= 0);
 
       while (movesPicked < numOfMoves)
       {

-          bestScore = -10000000;
-

           // 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.
           // 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.

-          if (pvNode || movesPicked < 12)
-          {
-              bestIndex = -1;
-              for (int i = movesPicked; i < numOfMoves; i++)
-                  if (moves[i].score > bestScore)
-                  {
-                      bestIndex = i;
-                      bestScore = moves[i].score;
-                  }
-          } else
-              bestIndex = movesPicked;
+          bestIndex = (pvNode || movesPicked < 12) ? find_best_index() : movesPicked;

 
           if (bestIndex != -1)
           {
 
           if (bestIndex != -1)
           {


@@ -363,26 +362,19 @@ Move MovePicker::pick_move_from_list() {
               moves[bestIndex] = moves[movesPicked++];
               if (   move != ttMove
                   && move != mateKiller
               moves[bestIndex] = moves[movesPicked++];
               if (   move != ttMove
                   && move != mateKiller

-                  && pos->move_is_legal(move, pinned))
+                  && pos.pl_move_is_legal(move, pinned))

                   return move;
           }
       }
       break;
 
   case PH_EVASIONS:
                   return move;
           }
       }
       break;
 
   case PH_EVASIONS:

-      assert(pos->is_check());
+      assert(pos.is_check());

       assert(movesPicked >= 0);
 
       while (movesPicked < numOfMoves)
       {
       assert(movesPicked >= 0);
 
       while (movesPicked < numOfMoves)
       {

-          bestScore = -10000000;
-          bestIndex = -1;
-          for (int i = movesPicked; i < numOfMoves; i++)
-              if(moves[i].score > bestScore)
-              {
-                  bestIndex = i;
-                  bestScore = moves[i].score;
-              }
+          bestIndex = find_best_index();

 
           if (bestIndex != -1)
           {
 
           if (bestIndex != -1)
           {


@@ -394,7 +386,7 @@ Move MovePicker::pick_move_from_list() {
     break;
 
   case PH_BAD_CAPTURES:
     break;
 
   case PH_BAD_CAPTURES:

-      assert(!pos->is_check());
+      assert(!pos.is_check());

       assert(badCapturesPicked >= 0);
       // It's probably a good idea to use SEE move ordering here, instead
       // of just picking the first move.  FIXME
       assert(badCapturesPicked >= 0);
       // It's probably a good idea to use SEE move ordering here, instead
       // of just picking the first move.  FIXME


@@ -403,28 +395,17 @@ Move MovePicker::pick_move_from_list() {
           move = badCaptures[badCapturesPicked++].move;
           if (   move != ttMove
               && move != mateKiller
           move = badCaptures[badCapturesPicked++].move;
           if (   move != ttMove
               && move != mateKiller

-              && pos->move_is_legal(move, pinned))
+              && pos.pl_move_is_legal(move, pinned))

               return move;
       }
       break;
 
   case PH_QCAPTURES:
               return move;
       }
       break;
 
   case PH_QCAPTURES:

-      assert(!pos->is_check());
+      assert(!pos.is_check());

       assert(movesPicked >= 0);
       while (movesPicked < numOfMoves)
       {
       assert(movesPicked >= 0);
       while (movesPicked < numOfMoves)
       {

-          bestScore = -10000000;
-          if (movesPicked < 4)
-          {
-              bestIndex = -1;
-              for (int i = movesPicked; i < numOfMoves; i++)
-                  if(moves[i].score > bestScore)
-                  {
-                      bestIndex = i;
-                      bestScore = moves[i].score;
-                  }
-          } else
-              bestIndex = movesPicked;
+          bestIndex = (movesPicked < 4 ? find_best_index() : movesPicked);

 
           if (bestIndex != -1)
           {
 
           if (bestIndex != -1)
           {


@@ -432,14 +413,14 @@ Move MovePicker::pick_move_from_list() {
               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?
               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->move_is_legal(move, pinned))
+              if (/* move != ttMove && */ pos.pl_move_is_legal(move, pinned))

                   return move;
           }
       }
       break;
 
   case PH_QCHECKS:
                   return move;
           }
       }
       break;
 
   case PH_QCHECKS:

-      assert(!pos->is_check());
+      assert(!pos.is_check());

       assert(movesPicked >= 0);
       // Perhaps we should do something better than just picking the first
       // move here?  FIXME
       assert(movesPicked >= 0);
       // Perhaps we should do something better than just picking the first
       // move here?  FIXME


@@ -447,7 +428,7 @@ Move MovePicker::pick_move_from_list() {
       {
           move = moves[movesPicked++].move;
           // Remember to change the line below if we decide to hash the qsearch!
       {
           move = moves[movesPicked++].move;
           // Remember to change the line below if we decide to hash the qsearch!

-          if (/* move != ttMove && */ pos->move_is_legal(move, pinned))
+          if (/* move != ttMove && */ pos.pl_move_is_legal(move, pinned))

               return move;
       }
       break;
               return move;
       }
       break;


@@ -458,11 +439,16 @@ Move MovePicker::pick_move_from_list() {
   return MOVE_NONE;
 }
 
   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::MovegenPhase MovePicker::current_move_type() const {
 
   return PhaseTable[phaseIndex];
 }
 

+

 /// MovePicker::init_phase_table() initializes the PhaseTable[],
 /// MainSearchPhaseIndex, EvasionPhaseIndex, QsearchWithChecksPhaseIndex
 /// and QsearchWithoutChecksPhaseIndex variables. It is only called once
 /// MovePicker::init_phase_table() initializes the PhaseTable[],
 /// MainSearchPhaseIndex, EvasionPhaseIndex, QsearchWithChecksPhaseIndex
 /// and QsearchWithoutChecksPhaseIndex variables. It is only called once