Refine improving-logic

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index c856980b4249fb8302b3990b5a02b14b0c743bea..55e04ec363e90467665aa24c8c79dd578f96ea9e 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -812,8 +812,8 @@ namespace {
         &&  eval <= alpha - RazorMargin)
         return qsearch<NT>(pos, ss, alpha, beta);
 
-    improving =   ss->staticEval >= (ss-2)->staticEval
-               || (ss-2)->staticEval == VALUE_NONE;
+    improving =  (ss-2)->staticEval == VALUE_NONE ? (ss->staticEval >= (ss-4)->staticEval
+              || (ss-4)->staticEval == VALUE_NONE) : ss->staticEval >= (ss-2)->staticEval;
 
     // Step 8. Futility pruning: child node (~30 Elo)
     if (   !PvNode