Simplification: do razoring only for depth 1

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 87c87757bfee7eb912f02d6b5182b4c644dc2fbf..23608f7a379570ff72d27a42816ead695e82e7f5 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -67,7 +67,7 @@ namespace {
   const int SkipPhase[] = { 0, 1, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 6, 7 };
 
   // Razoring and futility margins
-  const int RazorMargin = 600;
+  const int RazorMargin = 590;
   Value futility_margin(Depth d) { return Value(150 * d / ONE_PLY); }
 
   // Futility and reductions lookup tables, initialized at startup
@@ -667,17 +667,9 @@ namespace {
 
     // Step 7. Razoring (skipped when in check)
     if (   !PvNode
-        &&  depth < 4 * ONE_PLY
+        &&  depth <= ONE_PLY
         &&  eval + RazorMargin <= alpha)
-    {
-        if (depth <= ONE_PLY)
-            return qsearch<NonPV, false>(pos, ss, alpha, alpha+1);
-
-        Value ralpha = alpha - RazorMargin;
-        Value v = qsearch<NonPV, false>(pos, ss, ralpha, ralpha+1);
-        if (v <= ralpha)
-            return v;
-    }
+        return qsearch<NonPV, false>(pos, ss, alpha, alpha+1);
 
     // Step 8. Futility pruning: child node (skipped when in check)
     if (   !rootNode