Revert "null move reorder" series

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 944d9c6926a6b8a4e71eb0617f03743e5f380e0a..0c5ead46754c20411fe6ab3de99953dceb884524 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1281,21 +1281,57 @@ namespace {
     bool mateThreat = false;
     bool isCheck = pos.is_check();
 
-    bool useNullMove = (    allowNullmove
-                        //&&  depth > OnePly
-                        && !isCheck
-                        && !value_is_mate(beta)
-                        &&  ok_to_do_nullmove(pos)
-                        &&  approximateEval >= beta - NullMoveMargin);
+    // Null move search
+    if (    allowNullmove
+        &&  depth > OnePly
+        && !isCheck
+        && !value_is_mate(beta)
+        &&  ok_to_do_nullmove(pos)
+        &&  approximateEval >= beta - NullMoveMargin)
+    {
+        ss[ply].currentMove = MOVE_NULL;
+
+        StateInfo st;
+        pos.do_null_move(st);
+        int R = (depth >= 5 * OnePly ? 4 : 3); // Null move dynamic reduction
+
+        Value nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
+
+        pos.undo_null_move();
 
+        if (nullValue >= beta)
+        {
+            if (depth < 6 * OnePly)
+                return beta;
+
+            // Do zugzwang verification search
+            Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID);
+            if (v >= beta)
+                return beta;
+        } else {
+            // The null move failed low, which means that we may be faced with
+            // some kind of threat. If the previous move was reduced, check if
+            // the move that refuted the null move was somehow connected to the
+            // move which was reduced. If a connection is found, return a fail
+            // low score (which will cause the reduced move to fail high in the
+            // parent node, which will trigger a re-search with full depth).
+            if (nullValue == value_mated_in(ply + 2))
+                mateThreat = true;
+
+            ss[ply].threatMove = ss[ply + 1].currentMove;
+            if (   depth < ThreatDepth
+                && ss[ply - 1].reduction
+                && connected_moves(pos, ss[ply - 1].currentMove, ss[ply].threatMove))
+                return beta - 1;
+        }
+    }
     // Null move search not allowed, try razoring
-    if (    !useNullMove
-         && !value_is_mate(beta)
-         && depth < RazorDepth
-         && approximateEval < beta - RazorApprMargins[int(depth) - 2]
-         && ss[ply - 1].currentMove != MOVE_NULL
-         && ttMove == MOVE_NONE
-         && !pos.has_pawn_on_7th(pos.side_to_move()))
+    else if (   !value_is_mate(beta)
+             && depth < RazorDepth
+             && approximateEval < beta - RazorApprMargins[int(depth) - 2]
+             && ss[ply - 1].currentMove != MOVE_NULL
+             && ttMove == MOVE_NONE
+             && !pos.has_pawn_on_7th(pos.side_to_move()))
     {
         Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
         if (v < beta - RazorMargins[int(depth) - 2])
@@ -1312,7 +1348,7 @@ namespace {
 
     // Initialize a MovePicker object for the current position, and prepare
     // to search all moves.
-    MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply], useNullMove);
+    MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]);
 
     Move move, movesSearched[256];
     int moveCount = 0;
@@ -1328,48 +1364,6 @@ namespace {
            && (move = mp.get_next_move()) != MOVE_NONE
            && !thread_should_stop(threadID))
     {
-
-      // Null move search
-      if (move == MOVE_NULL)
-      {
-          ss[ply].currentMove = MOVE_NULL;
-
-          StateInfo st;
-          pos.do_null_move(st);
-          int R = (depth >= 5 * OnePly ? 4 : 3); // Null move dynamic reduction
-
-          Value nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
-
-          pos.undo_null_move();
-
-          if (nullValue >= beta)
-          {
-              if (depth < 6 * OnePly)
-                  return beta;
-
-              // Do zugzwang verification search
-              Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID);
-              if (v >= beta)
-                  return beta;
-          } else {
-              // The null move failed low, which means that we may be faced with
-              // some kind of threat. If the previous move was reduced, check if
-              // the move that refuted the null move was somehow connected to the
-              // move which was reduced. If a connection is found, return a fail
-              // low score (which will cause the reduced move to fail high in the
-              // parent node, which will trigger a re-search with full depth).
-              if (nullValue == value_mated_in(ply + 2))
-                  mateThreat = true;
-
-              ss[ply].threatMove = ss[ply + 1].currentMove;
-              if (   depth < ThreatDepth
-                  && ss[ply - 1].reduction
-                  && connected_moves(pos, ss[ply - 1].currentMove, ss[ply].threatMove))
-                  return beta - 1;
-          }
-          continue;
-      }
-
       assert(move_is_ok(move));
 
       bool singleReply = (isCheck && mp.number_of_moves() == 1);
@@ -1968,15 +1962,15 @@ namespace {
     bool includeAllMoves = (searchMoves[0] == MOVE_NONE);
 
     // Generate all legal moves
-    int lm_count = generate_legal_moves(pos, mlist);
+    MoveStack* last = generate_legal_moves(pos, mlist);
 
     // Add each move to the moves[] array
-    for (int i = 0; i < lm_count; i++)
+    for (MoveStack* cur = mlist; cur != last; cur++)
     {
         bool includeMove = includeAllMoves;
 
         for (int k = 0; !includeMove && searchMoves[k] != MOVE_NONE; k++)
-            includeMove = (searchMoves[k] == mlist[i].move);
+            includeMove = (searchMoves[k] == cur->move);
 
         if (!includeMove)
             continue;
@@ -1985,7 +1979,7 @@ namespace {
         StateInfo st;
         SearchStack ss[PLY_MAX_PLUS_2];
 
-        moves[count].move = mlist[i].move;
+        moves[count].move = cur->move;
         pos.do_move(moves[count].move, st);
         moves[count].score = -qsearch(pos, ss, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 1, 0);
         pos.undo_move(moves[count].move);