Null move dynamic reduction based on value

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index c4e061bd6cd1afb5d8bcc0035bda587668adb86d..e02529327435b46f49f4780d591877b201042cbf 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -310,7 +310,7 @@ namespace {
              Value *alpha, Value *beta, Value *bestValue,
              const Value futilityValue, const Value approximateValue,
              Depth depth, int *moves,
-             MovePicker *mp, Bitboard dcCandidates, int master, bool pvNode);
+             MovePicker *mp, int master, bool pvNode);
   void wake_sleeping_threads();
 
 #if !defined(_MSC_VER)
@@ -333,14 +333,14 @@ namespace {
 int perft(Position& pos, Depth depth)
 {
     Move move;
-    MovePicker mp = MovePicker(pos, MOVE_NONE, depth, H);
     int sum = 0;
+    MovePicker mp = MovePicker(pos, MOVE_NONE, depth, H);
 
     // If we are at the last ply we don't need to do and undo
     // the moves, just to count them.
     if (depth <= OnePly) // Replace with '<' to test also qsearch
     {
-        while ((move = mp.get_next_move()) != MOVE_NONE) sum++;
+        while (mp.get_next_move()) sum++;
         return sum;
     }
 
@@ -348,10 +348,10 @@ int perft(Position& pos, Depth depth)
     CheckInfo ci(pos);
     while ((move = mp.get_next_move()) != MOVE_NONE)
     {
-      StateInfo st;
-      pos.do_move(move, st, ci.dcCandidates, pos.move_is_check(move, ci));
-      sum += perft(pos, depth - OnePly);
-      pos.undo_move(move);
+        StateInfo st;
+        pos.do_move(move, st, ci, pos.move_is_check(move, ci));
+        sum += perft(pos, depth - OnePly);
+        pos.undo_move(move);
     }
     return sum;
 }
@@ -898,13 +898,14 @@ namespace {
                       << " currmovenumber " << i + 1 << std::endl;
 
         // Decide search depth for this move
+        bool moveIsCheck = pos.move_is_check(move);
         bool captureOrPromotion = pos.move_is_capture_or_promotion(move);
         bool dangerous;
-        ext = extension(pos, move, true, captureOrPromotion, pos.move_is_check(move), false, false, &dangerous);
+        ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous);
         newDepth = (Iteration - 2) * OnePly + ext + InitialDepth;
 
         // Make the move, and search it
-        pos.do_move(move, st, ci.dcCandidates);
+        pos.do_move(move, st, ci, moveIsCheck);
 
         if (i < MultiPV)
         {
@@ -1135,7 +1136,7 @@ namespace {
       newDepth = depth - OnePly + ext;
 
       // Make and search the move
-      pos.do_move(move, st, ci.dcCandidates, moveIsCheck);
+      pos.do_move(move, st, ci, moveIsCheck);
 
       if (moveCount == 1) // The first move in list is the PV
           value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID);
@@ -1208,8 +1209,8 @@ namespace {
           && idle_thread_exists(threadID)
           && !AbortSearch
           && !thread_should_stop(threadID)
-          && split(pos, ss, ply, &alpha, &beta, &bestValue, VALUE_NONE, VALUE_NONE, depth,
-                   &moveCount, &mp, ci.dcCandidates, threadID, true))
+          && split(pos, ss, ply, &alpha, &beta, &bestValue, VALUE_NONE, VALUE_NONE,
+                   depth, &moveCount, &mp, threadID, true))
           break;
     }
 
@@ -1313,7 +1314,13 @@ namespace {
         ss[ply].currentMove = MOVE_NULL;
 
         pos.do_null_move(st);
-        int R = (depth >= 5 * OnePly ? 4 : 3); // Null move dynamic reduction
+
+        // Null move dynamic reduction based on depth
+        int R = (depth >= 5 * OnePly ? 4 : 3);
+
+        // Null move dynamic reduction based on value
+        if (approximateEval - beta > PawnValueMidgame)
+            R++;
 
         nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
 
@@ -1424,7 +1431,7 @@ namespace {
       }
 
       // Make and search the move
-      pos.do_move(move, st, ci.dcCandidates, moveIsCheck);
+      pos.do_move(move, st, ci, moveIsCheck);
 
       // Try to reduce non-pv search depth by one ply if move seems not problematic,
       // if the move fails high will be re-searched at full depth.
@@ -1469,8 +1476,8 @@ namespace {
           && idle_thread_exists(threadID)
           && !AbortSearch
           && !thread_should_stop(threadID)
-          && split(pos, ss, ply, &beta, &beta, &bestValue, futilityValue, approximateEval, depth, &moveCount,
-                   &mp, ci.dcCandidates, threadID, false))
+          && split(pos, ss, ply, &beta, &beta, &bestValue, futilityValue, approximateEval,
+                   depth, &moveCount, &mp, threadID, false))
         break;
     }
 
@@ -1637,7 +1644,7 @@ namespace {
           continue;
 
       // Make and search the move
-      pos.do_move(move, st, ci.dcCandidates, moveIsCheck);
+      pos.do_move(move, st, ci, moveIsCheck);
       value = -qsearch(pos, ss, -beta, -alpha, depth-OnePly, ply+1, threadID);
       pos.undo_move(move);
 
@@ -1764,7 +1771,7 @@ namespace {
 
       // Make and search the move.
       StateInfo st;
-      pos.do_move(move, st, sp->dcCandidates, moveIsCheck);
+      pos.do_move(move, st, ci, moveIsCheck);
 
       // Try to reduce non-pv search depth by one ply if move seems not problematic,
       // if the move fails high will be re-searched at full depth.
@@ -1870,7 +1877,7 @@ namespace {
 
       // Make and search the move.
       StateInfo st;
-      pos.do_move(move, st, sp->dcCandidates, moveIsCheck);
+      pos.do_move(move, st, ci, moveIsCheck);
 
       // Try to reduce non-pv search depth by one ply if move seems not problematic,
       // if the move fails high will be re-searched at full depth.
@@ -2814,7 +2821,7 @@ namespace {
   bool split(const Position& p, SearchStack* sstck, int ply,
              Value* alpha, Value* beta, Value* bestValue, const Value futilityValue,
              const Value approximateEval, Depth depth, int* moves,
-             MovePicker* mp, Bitboard dcCandidates, int master, bool pvNode) {
+             MovePicker* mp, int master, bool pvNode) {
 
     assert(p.is_ok());
     assert(sstck != NULL);
@@ -2851,7 +2858,6 @@ namespace {
     splitPoint->alpha = pvNode? *alpha : (*beta - 1);
     splitPoint->beta = *beta;
     splitPoint->pvNode = pvNode;
-    splitPoint->dcCandidates = dcCandidates;
     splitPoint->bestValue = *bestValue;
     splitPoint->futilityValue = futilityValue;
     splitPoint->approximateEval = approximateEval;