X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=e75db243cfcb2cb01d760c885536b29bc5a5992c;hp=b571cdf1787204e6c3e7c919da7c782de33439d4;hb=a00a336946fa9e6dcfa39f8b656413d2de032a89;hpb=1725ed39adcc4aa6d96117a7b83e1552b37a6baa

diff --git a/src/search.cpp b/src/search.cpp
index b571cdf1..e75db243 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -76,7 +76,7 @@ namespace {
   }
 
   constexpr int futility_move_count(bool improving, Depth depth) {
-    return (5 + depth * depth) * (1 + improving) / 2;
+    return (5 + depth * depth) * (1 + improving) / 2 - 1;
   }
 
   // History and stats update bonus, based on depth
@@ -150,7 +150,7 @@ namespace {
   Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth = 0);
 
   Value value_to_tt(Value v, int ply);
-  Value value_from_tt(Value v, int ply);
+  Value value_from_tt(Value v, int ply, int r50c);
   void update_pv(Move* pv, Move move, Move* childPv);
   void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus);
   void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus);
@@ -661,7 +661,7 @@ namespace {
     excludedMove = ss->excludedMove;
     posKey = pos.key() ^ Key(excludedMove << 16); // Isn't a very good hash
     tte = TT.probe(posKey, ttHit);
-    ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
+    ttValue = ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE;
     ttMove =  rootNode ? thisThread->rootMoves[thisThread->pvIdx].pv[0]
             : ttHit    ? tte->move() : MOVE_NONE;
     ttPv = PvNode || (ttHit && tte->is_pv());
@@ -899,7 +899,7 @@ namespace {
         search<NT>(pos, ss, alpha, beta, depth - 7, cutNode);
 
         tte = TT.probe(posKey, ttHit);
-        ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
+        ttValue = ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE;
         ttMove = ttHit ? tte->move() : MOVE_NONE;
     }
 
@@ -955,7 +955,45 @@ moves_loop: // When in check, search starts from here
       movedPiece = pos.moved_piece(move);
       givesCheck = pos.gives_check(move);
 
-      // Step 13. Extensions (~70 Elo)
+      // Calculate new depth for this move
+      newDepth = depth - 1;
+
+      // Step 13. Pruning at shallow depth (~170 Elo)
+      if (  !rootNode
+          && pos.non_pawn_material(us)
+          && bestValue > VALUE_MATED_IN_MAX_PLY)
+      {
+          // Skip quiet moves if movecount exceeds our FutilityMoveCount threshold
+          moveCountPruning = moveCount >= futility_move_count(improving, depth);
+
+          if (   !captureOrPromotion
+              && !givesCheck
+              && (!PvNode || !pos.advanced_pawn_push(move) || pos.non_pawn_material(~us) > BishopValueMg))
+          {
+              // Reduced depth of the next LMR search
+              int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), 0);
+
+              // Countermoves based pruning (~20 Elo)
+              if (   lmrDepth < 4 + ((ss-1)->statScore > 0 || (ss-1)->moveCount == 1)
+                  && (*contHist[0])[movedPiece][to_sq(move)] < CounterMovePruneThreshold
+                  && (*contHist[1])[movedPiece][to_sq(move)] < CounterMovePruneThreshold)
+                  continue;
+
+              // Futility pruning: parent node (~2 Elo)
+              if (   lmrDepth < 6
+                  && !inCheck
+                  && ss->staticEval + 250 + 211 * lmrDepth <= alpha)
+                  continue;
+
+              // Prune moves with negative SEE (~10 Elo)
+              if (!pos.see_ge(move, Value(-(31 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth)))
+                  continue;
+          }
+          else if (!pos.see_ge(move, Value(-199) * depth)) // (~20 Elo)
+                  continue;
+      }
+
+      // Step 14. Extensions (~70 Elo)
 
       // Singular extension search (~60 Elo). If all moves but one fail low on a
       // search of (alpha-s, beta-s), and just one fails high on (alpha, beta),
@@ -999,13 +1037,6 @@ moves_loop: // When in check, search starts from here
                && (pos.is_discovery_check_on_king(~us, move) || pos.see_ge(move)))
           extension = 1;
 
-      // Shuffle extension
-      else if (   PvNode
-               && pos.rule50_count() > 18
-               && depth < 3
-               && ++thisThread->shuffleExts < thisThread->nodes.load(std::memory_order_relaxed) / 4)  // To avoid too many extensions
-          extension = 1;
-
       // Passed pawn extension
       else if (   move == ss->killers[0]
                && pos.advanced_pawn_push(move)
@@ -1016,48 +1047,8 @@ moves_loop: // When in check, search starts from here
       if (type_of(move) == CASTLING)
           extension = 1;
 
-      // Calculate new depth for this move
-      newDepth = depth - 1 + extension;
-
-      // Step 14. Pruning at shallow depth (~170 Elo)
-      if (  !rootNode
-          && pos.non_pawn_material(us)
-          && bestValue > VALUE_MATED_IN_MAX_PLY)
-      {
-          // Skip quiet moves if movecount exceeds our FutilityMoveCount threshold
-          moveCountPruning = moveCount >= futility_move_count(improving, depth);
-
-          if (   !captureOrPromotion
-              && !givesCheck
-              && (!pos.advanced_pawn_push(move) || pos.non_pawn_material(~us) > BishopValueMg))
-          {
-              // Move count based pruning
-              if (moveCountPruning)
-                  continue;
-
-              // Reduced depth of the next LMR search
-              int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), 0);
-
-              // Countermoves based pruning (~20 Elo)
-              if (   lmrDepth < 4 + ((ss-1)->statScore > 0 || (ss-1)->moveCount == 1)
-                  && (*contHist[0])[movedPiece][to_sq(move)] < CounterMovePruneThreshold
-                  && (*contHist[1])[movedPiece][to_sq(move)] < CounterMovePruneThreshold)
-                  continue;
-
-              // Futility pruning: parent node (~2 Elo)
-              if (   lmrDepth < 6
-                  && !inCheck
-                  && ss->staticEval + 250 + 211 * lmrDepth <= alpha)
-                  continue;
-
-              // Prune moves with negative SEE (~10 Elo)
-              if (!pos.see_ge(move, Value(-(31 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth)))
-                  continue;
-          }
-          else if (  !(givesCheck && extension)
-                   && !pos.see_ge(move, Value(-199) * depth)) // (~20 Elo)
-                  continue;
-      }
+      // Add extension to new depth
+      newDepth += extension;
 
       // Speculative prefetch as early as possible
       prefetch(TT.first_entry(pos.key_after(move)));
@@ -1351,7 +1342,7 @@ moves_loop: // When in check, search starts from here
     // Transposition table lookup
     posKey = pos.key();
     tte = TT.probe(posKey, ttHit);
-    ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
+    ttValue = ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE;
     ttMove = ttHit ? tte->move() : MOVE_NONE;
     pvHit = ttHit && tte->is_pv();
 
@@ -1537,11 +1528,11 @@ moves_loop: // When in check, search starts from here
   // from the transposition table (which refers to the plies to mate/be mated
   // from current position) to "plies to mate/be mated from the root".
 
-  Value value_from_tt(Value v, int ply) {
+  Value value_from_tt(Value v, int ply, int r50c) {
 
     return  v == VALUE_NONE             ? VALUE_NONE
-          : v >= VALUE_MATE_IN_MAX_PLY  ? v - ply
-          : v <= VALUE_MATED_IN_MAX_PLY ? v + ply : v;
+          : v >= VALUE_MATE_IN_MAX_PLY  ? VALUE_MATE - v > 99 - r50c ? VALUE_MATE_IN_MAX_PLY  : v - ply
+          : v <= VALUE_MATED_IN_MAX_PLY ? VALUE_MATE + v > 99 - r50c ? VALUE_MATED_IN_MAX_PLY : v + ply : v;
   }