Introduce static history

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index d854cd95d1d5dc75b13b698b0f95cf0de7485191..ab559696ebebfa5525eec84a8063a9ac995ae60e 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -807,6 +807,15 @@ namespace {
         tte->save(posKey, VALUE_NONE, ss->ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval);
     }
 
+    // Update static history for previous move
+    if (is_ok((ss-1)->currentMove) && !(ss-1)->inCheck && !priorCapture)
+    {
+        int bonus = ss->staticEval > -(ss-1)->staticEval + 2 * Tempo ? -stat_bonus(depth) :
+                    ss->staticEval < -(ss-1)->staticEval + 2 * Tempo ? stat_bonus(depth) :
+                    0;
+        thisThread->staticHistory[~us][from_to((ss-1)->currentMove)] << bonus;
+    }
+
     // Step 7. Razoring (~1 Elo)
     if (   !rootNode // The required rootNode PV handling is not available in qsearch
         &&  depth == 1
@@ -964,6 +973,7 @@ moves_loop: // When in check, search starts from here
     Move countermove = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq];
 
     MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory,
+                                      &thisThread->staticHistory,
                                       &thisThread->lowPlyHistory,
                                       &captureHistory,
                                       contHist,
@@ -1222,10 +1232,6 @@ moves_loop: // When in check, search starts from here
           }
           else
           {
-              // Increase reduction for captures/promotions if late move and at low depth
-              if (depth < 8 && moveCount > 2)
-                  r++;
-
               // Unless giving check, this capture is likely bad
               if (   !givesCheck
                   && ss->staticEval + PieceValue[EG][pos.captured_piece()] + 210 * depth <= alpha)
@@ -1511,6 +1517,7 @@ moves_loop: // When in check, search starts from here
     // queen and checking knight promotions, and other checks(only if depth >= DEPTH_QS_CHECKS)
     // will be generated.
     MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory,
+                                      &thisThread->staticHistory,
                                       &thisThread->captureHistory,
                                       contHist,
                                       to_sq((ss-1)->currentMove));
@@ -1554,7 +1561,6 @@ moves_loop: // When in check, search starts from here
 
       // Do not search moves with negative SEE values
       if (    bestValue > VALUE_TB_LOSS_IN_MAX_PLY
-          && !(givesCheck && pos.is_discovery_check_on_king(~pos.side_to_move(), move))
           && !pos.see_ge(move))
           continue;