Try to prune also when approximateEval < beta

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index b86693289c8b2688070e74382a1b64c286528af2..5bbc0abd2d58514870af54133786b3595dcdc563 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -677,6 +677,14 @@ namespace {
     // searchMoves are verified, copied, scored and sorted
     RootMoveList rml(p, searchMoves);
 
+    if (rml.move_count() == 0)
+    {
+        if (PonderSearch)
+            wait_for_stop_or_ponderhit();
+
+        return pos.is_check()? -VALUE_MATE : VALUE_DRAW;
+    }
+
     // Print RootMoveList c'tor startup scoring to the standard output,
     // so that we print information also for iteration 1.
     std::cout << "info depth " << 1 << "\ninfo depth " << 1
@@ -1509,19 +1517,16 @@ namespace {
               continue;
 
           // Value based pruning
-          if (approximateEval < beta)
-          {
-              if (futilityValue == VALUE_NONE)
-                  futilityValue = evaluate(pos, ei, threadID) + FutilityValueMargin;
+          if (futilityValue == VALUE_NONE)
+              futilityValue = evaluate(pos, ei, threadID) + FutilityValueMargin;
 
-              futilityValueScaled = futilityValue - moveCount * IncrementalFutilityMargin;
+          futilityValueScaled = futilityValue - moveCount * IncrementalFutilityMargin;
 
-              if (futilityValueScaled < beta)
-              {
-                  if (futilityValueScaled > bestValue)
-                      bestValue = futilityValueScaled;
-                  continue;
-              }
+          if (futilityValueScaled < beta)
+          {
+              if (futilityValueScaled > bestValue)
+                  bestValue = futilityValueScaled;
+              continue;
           }
       }