Remove useless razoring condition

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 2149df2ba8fe340326ac45be06440f981e7d8826..7eab970a866ea27f30f3a500240affc98fac1b8b 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -134,7 +134,6 @@ namespace {
   Value DrawValue[COLOR_NB];
   HistoryStats History;
   CounterMovesHistoryStats CounterMovesHistory;
-  GainsStats Gains;
   MovesStats Countermoves;
 
   template <NodeType NT, bool SpNode>
@@ -181,6 +180,17 @@ void Search::init() {
 }
 
 
+/// Search::reset() clears all search memory, to obtain reproducible search results
+
+void Search::reset () {
+
+  TT.clear();
+  History.clear();
+  CounterMovesHistory.clear();
+  Countermoves.clear();
+}
+
+
 /// Search::perft() is our utility to verify move generation. All the leaf nodes
 /// up to the given depth are generated and counted and the sum returned.
 template<bool Root>
@@ -339,10 +349,6 @@ namespace {
     beta = VALUE_INFINITE;
 
     TT.new_search();
-    History.clear();
-    CounterMovesHistory.clear();
-    Gains.clear();
-    Countermoves.clear();
 
     size_t multiPV = Options["MultiPV"];
     Skill skill(Options["Skill Level"]);
@@ -635,7 +641,7 @@ namespace {
         }
     }
 
-    // Step 5. Evaluate the position statically and update parent's gain statistics
+    // Step 5. Evaluate the position statically
     if (inCheck)
     {
         ss->staticEval = eval = VALUE_NONE;
@@ -664,23 +670,11 @@ namespace {
     if (ss->skipEarlyPruning)
         goto moves_loop;
 
-    if (   !pos.captured_piece_type()
-        &&  ss->staticEval != VALUE_NONE
-        && (ss-1)->staticEval != VALUE_NONE
-        && (move = (ss-1)->currentMove) != MOVE_NULL
-        &&  move != MOVE_NONE
-        &&  type_of(move) == NORMAL)
-    {
-        Square to = to_sq(move);
-        Gains.update(pos.piece_on(to), to, -(ss-1)->staticEval - ss->staticEval);
-    }
-
     // Step 6. Razoring (skipped when in check)
     if (   !PvNode
         &&  depth < 4 * ONE_PLY
         &&  eval + razor_margin(depth) <= alpha
-        &&  ttMove == MOVE_NONE
-        && !pos.pawn_on_7th(pos.side_to_move()))
+        &&  ttMove == MOVE_NONE)
     {
         if (   depth <= ONE_PLY
             && eval + razor_margin(3 * ONE_PLY) <= alpha)
@@ -850,7 +844,7 @@ moves_loop: // When in check and at SpNode search starts from here
       captureOrPromotion = pos.capture_or_promotion(move);
 
       givesCheck =  type_of(move) == NORMAL && !ci.dcCandidates
-                  ? ci.checkSq[type_of(pos.piece_on(from_sq(move)))] & to_sq(move)
+                  ? ci.checkSquares[type_of(pos.piece_on(from_sq(move)))] & to_sq(move)
                   : pos.gives_check(move, ci);
 
       dangerous =   givesCheck
@@ -907,8 +901,7 @@ moves_loop: // When in check and at SpNode search starts from here
           // Futility pruning: parent node
           if (predictedDepth < 7 * ONE_PLY)
           {
-              futilityValue =  ss->staticEval + futility_margin(predictedDepth)
-                             + 128 + Gains[pos.moved_piece(move)][to_sq(move)];
+              futilityValue = ss->staticEval + futility_margin(predictedDepth) + 256;
 
               if (futilityValue <= alpha)
               {
@@ -960,12 +953,15 @@ moves_loop: // When in check and at SpNode search starts from here
           ss->reduction = reduction<PvNode>(improving, depth, moveCount);
 
           if (   (!PvNode && cutNode)
-              || (  History[pos.piece_on(to_sq(move))][to_sq(move)]
-                  + CounterMovesHistory[pos.piece_on(prevMoveSq)][prevMoveSq]
-                                       [pos.piece_on(to_sq(move))][to_sq(move)] < VALUE_ZERO))
+              || (   History[pos.piece_on(to_sq(move))][to_sq(move)] < VALUE_ZERO
+                  && CounterMovesHistory[pos.piece_on(prevMoveSq)][prevMoveSq]
+                                        [pos.piece_on(to_sq(move))][to_sq(move)] <= VALUE_ZERO))
               ss->reduction += ONE_PLY;
 
-          if (move == countermove)
+          if (    move == countermove
+              || (   History[pos.piece_on(to_sq(move))][to_sq(move)] > VALUE_ZERO
+                  && CounterMovesHistory[pos.piece_on(prevMoveSq)][prevMoveSq]
+                                        [pos.piece_on(to_sq(move))][to_sq(move)] > VALUE_ZERO))
               ss->reduction = std::max(DEPTH_ZERO, ss->reduction - ONE_PLY);
 
           // Decrease reduction for moves that escape a capture
@@ -981,13 +977,6 @@ moves_loop: // When in check and at SpNode search starts from here
 
           value = -search<NonPV, false>(pos, ss+1, -(alpha+1), -alpha, d, true);
 
-          // Re-search at intermediate depth if reduction is very high
-          if (value > alpha && ss->reduction >= 4 * ONE_PLY)
-          {
-              Depth d2 = std::max(newDepth - 2 * ONE_PLY, ONE_PLY);
-              value = -search<NonPV, false>(pos, ss+1, -(alpha+1), -alpha, d2, true);
-          }
-
           doFullDepthSearch = (value > alpha && ss->reduction != DEPTH_ZERO);
           ss->reduction = DEPTH_ZERO;
       }
@@ -1273,7 +1262,7 @@ moves_loop: // When in check and at SpNode search starts from here
       assert(is_ok(move));
 
       givesCheck =  type_of(move) == NORMAL && !ci.dcCandidates
-                  ? ci.checkSq[type_of(pos.piece_on(from_sq(move)))] & to_sq(move)
+                  ? ci.checkSquares[type_of(pos.piece_on(from_sq(move)))] & to_sq(move)
                   : pos.gives_check(move, ci);
 
       // Futility pruning
@@ -1438,7 +1427,7 @@ moves_loop: // When in check and at SpNode search starts from here
     }
 
     // Extra penalty for TT move in previous ply when it gets refuted
-    if (is_ok((ss-2)->currentMove) && (ss-1)->currentMove == (ss-1)->ttMove)
+    if (is_ok((ss-2)->currentMove) && (ss-1)->currentMove == (ss-1)->ttMove && !pos.captured_piece_type())
     {
         Square prevPrevSq = to_sq((ss-2)->currentMove);
         HistoryStats& ttMoveCmh = CounterMovesHistory[pos.piece_on(prevPrevSq)][prevPrevSq];