CMH Pruning Tweak

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 62f02d835bfb192e2522d43b2ed02bf0a5304388..6275cdf283e3961fc5c4529b57b5788271434ea7 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -152,7 +152,7 @@ namespace {
 void Search::init() {
 
   for (int i = 1; i < MAX_MOVES; ++i)
-      Reductions[i] = int(21.3 * std::log(i + 0.25 * std::log(i)));
+      Reductions[i] = int(21.9 * std::log(i));
 }
 
 
@@ -760,6 +760,7 @@ namespace {
             ss->staticEval = eval = -(ss-1)->staticEval;
 
         // Save static evaluation into transposition table
+        if(!excludedMove)
         tte->save(posKey, VALUE_NONE, ss->ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval);
     }
 
@@ -780,7 +781,6 @@ namespace {
 
     // Step 7. Futility pruning: child node (~50 Elo)
     if (   !PvNode
-        &&  depth < 9
         &&  eval - futility_margin(depth, improving) >= beta
         &&  eval < VALUE_KNOWN_WIN) // Do not return unproven wins
         return eval;
@@ -907,7 +907,7 @@ namespace {
         && !ttMove)
         depth -= 2;
 
-moves_loop: // When in check, search starts from here
+moves_loop: // When in check, search starts here
 
     ttCapture = ttMove && pos.capture_or_promotion(ttMove);
 
@@ -1017,13 +1017,12 @@ moves_loop: // When in check, search starts from here
           {
               // Continuation history based pruning (~20 Elo)
               if (   lmrDepth < 5
-                  && (*contHist[0])[movedPiece][to_sq(move)] < CounterMovePruneThreshold
-                  && (*contHist[1])[movedPiece][to_sq(move)] < CounterMovePruneThreshold)
+                  && (*contHist[0])[movedPiece][to_sq(move)] < (depth == 1 ? 0 : -stat_bonus(depth-1))
+                  && (*contHist[1])[movedPiece][to_sq(move)] < (depth == 1 ? 0 : -stat_bonus(depth-1)))
                   continue;
 
               // Futility pruning: parent node (~5 Elo)
-              if (   lmrDepth < 7
-                  && !ss->inCheck
+              if (   !ss->inCheck
                   && ss->staticEval + 174 + 157 * lmrDepth <= alpha
                   &&  (*contHist[0])[movedPiece][to_sq(move)]
                     + (*contHist[1])[movedPiece][to_sq(move)]
@@ -1157,25 +1156,21 @@ moves_loop: // When in check, search starts from here
               r--;
 
           // Increase reduction for cut nodes (~3 Elo)
-          if (cutNode)
-              r += 1 + !captureOrPromotion;
+          if (cutNode && move != ss->killers[0])
+              r += 2;
 
-          if (!captureOrPromotion)
-          {
-              // Increase reduction if ttMove is a capture (~3 Elo)
-              if (ttCapture)
-                  r++;
-
-              ss->statScore =  thisThread->mainHistory[us][from_to(move)]
-                             + (*contHist[0])[movedPiece][to_sq(move)]
-                             + (*contHist[1])[movedPiece][to_sq(move)]
-                             + (*contHist[3])[movedPiece][to_sq(move)]
-                             - 4923;
-
-              // Decrease/increase reduction for moves with a good/bad history (~30 Elo)
-              if (!ss->inCheck)
-                  r -= ss->statScore / 14721;
-          }
+          // Increase reduction if ttMove is a capture (~3 Elo)
+          if (ttCapture)
+              r++;
+
+          ss->statScore =  thisThread->mainHistory[us][from_to(move)]
+                         + (*contHist[0])[movedPiece][to_sq(move)]
+                         + (*contHist[1])[movedPiece][to_sq(move)]
+                         + (*contHist[3])[movedPiece][to_sq(move)]
+                         - 4923;
+
+          // Decrease/increase reduction for moves with a good/bad history (~30 Elo)
+          r -= ss->statScore / 14721;
 
           // In general we want to cap the LMR depth search at newDepth. But if
           // reductions are really negative and movecount is low, we allow this move
@@ -1473,6 +1468,10 @@ moves_loop: // When in check, search starts from here
     {
       assert(is_ok(move));
 
+      // Check for legality
+      if (!pos.legal(move))
+          continue;
+
       givesCheck = pos.gives_check(move);
       captureOrPromotion = pos.capture_or_promotion(move);
 
@@ -1511,13 +1510,6 @@ moves_loop: // When in check, search starts from here
       // Speculative prefetch as early as possible
       prefetch(TT.first_entry(pos.key_after(move)));
 
-      // Check for legality just before making the move
-      if (!pos.legal(move))
-      {
-          moveCount--;
-          continue;
-      }
-
       ss->currentMove = move;
       ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck]
                                                                 [captureOrPromotion]