X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=03344db772b8b9b69074b5748be52a0f4704ffd3;hp=0da6b61bbbbe99f176eea9a5c67f75db9cd8b306;hb=14dbeb22dd04f0954322a58c26833506fb4532a9;hpb=cf4df0327a3f30be345b0e9685b095be79e47cae

diff --git a/src/movepick.cpp b/src/movepick.cpp
index 0da6b61b..03344db7 100644
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -52,7 +52,7 @@ 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};
 }
@@ -71,13 +71,15 @@ namespace {
 /// 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) {
+                       const History& h, SearchStack* ss, Value beta) : pos(p), H(h) {
   int searchTT = ttm;
   ttMoves[0].move = ttm;
-  finished = false;
   lastBadCapture = badCaptures;
+  badCaptureThreshold = 0;
 
-  if (ss)
+  pinned = p.pinned_pieces(pos.side_to_move());
+
+  if (ss && !p.is_check())
   {
       ttMoves[1].move = (ss->mateKiller == ttm)? MOVE_NONE : ss->mateKiller;
       searchTT |= ttMoves[1].move;
@@ -86,21 +88,30 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d,
   } else
       ttMoves[1].move = killers[0].move = killers[1].move = MOVE_NONE;
 
-  Color us = pos.side_to_move();
-
-  dc = p.discovered_check_candidates(us);
-  pinned = p.pinned_pieces(us);
-
   if (p.is_check())
       phasePtr = EvasionsPhaseTable;
   else if (d > Depth(0))
-      phasePtr = MainSearchPhaseTable + !searchTT;
-  else if (d == Depth(0))
-      phasePtr = QsearchWithChecksPhaseTable + !searchTT;
+  {
+      // 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 + !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 += !searchTT - 1;
   go_next_phase();
 }
 
@@ -132,7 +143,7 @@ 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:
@@ -144,8 +155,8 @@ void MovePicker::go_next_phase() {
 
   case PH_EVASIONS:
       assert(pos.is_check());
-      lastMove = generate_evasions(pos, moves, pinned);
-      score_evasions();
+      lastMove = generate_evasions(pos, moves);
+      score_evasions_or_checks();
       return;
 
   case PH_QCAPTURES:
@@ -154,12 +165,12 @@ void MovePicker::go_next_phase() {
       return;
 
   case PH_QCHECKS:
-      // Perhaps we should order moves move here?  FIXME
-      lastMove = generate_non_capture_checks(pos, moves, dc);
+      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:
@@ -197,8 +208,8 @@ 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));
   }
 }
 
@@ -219,29 +230,36 @@ void MovePicker::score_noncaptures() {
       piece = pos.piece_on(from);
       hs = H.move_ordering_score(piece, to);
 
-      // Ensure history is always preferred to pst
+      // Ensure history has always highest priority
       if (hs > 0)
-          hs += 1000;
+          hs += 10000;
 
-      // pst based scoring
-      cur->score = hs + pos.pst_delta<Position::MidGame>(piece, from, to);
+      // Gain table based scoring
+      cur->score = hs + 16 * 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
+  // 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
+      if ((seeScore = pos.see_sign(m)) < 0)
+          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));
   }
 }
@@ -251,12 +269,11 @@ 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)
@@ -280,7 +297,7 @@ 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
@@ -303,6 +320,11 @@ Move MovePicker::get_next_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
@@ -312,11 +334,11 @@ Move MovePicker::get_next_move() {
                   return move;
               break;
 
-          case PH_EVASIONS:
           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
@@ -343,21 +365,3 @@ 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;
-}