Make razor margin depth independent

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index e0f6cba2c4567c23b0f4af09462207037d817835..214177a2afae1280eb296352fe59245dfd2c98cb 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -67,8 +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 margin based on depth
   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 margin based on depth

-  // razor_margin[0] is unused as long as depth >= ONE_PLY in search
-  const int razor_margin[] = { 0, 570, 603, 554 };
+  const int razor_margin = 600;

   Value futility_margin(Depth d) { return Value(150 * d / ONE_PLY); }
 
   // Futility and reductions lookup tables, initialized at startup
   Value futility_margin(Depth d) { return Value(150 * d / ONE_PLY); }
 
   // Futility and reductions lookup tables, initialized at startup


@@ -654,12 +653,12 @@ namespace {
     // Step 6. Razoring (skipped when in check)
     if (   !PvNode
         &&  depth < 4 * ONE_PLY
     // Step 6. Razoring (skipped when in check)
     if (   !PvNode
         &&  depth < 4 * ONE_PLY

-        &&  eval + razor_margin[depth / ONE_PLY] <= alpha)
+        &&  eval + razor_margin <= alpha)

     {
         if (depth <= ONE_PLY)
             return qsearch<NonPV, false>(pos, ss, alpha, alpha+1);
 
     {
         if (depth <= ONE_PLY)
             return qsearch<NonPV, false>(pos, ss, alpha, alpha+1);
 

-        Value ralpha = alpha - razor_margin[depth / ONE_PLY];
+        Value ralpha = alpha - razor_margin;

         Value v = qsearch<NonPV, false>(pos, ss, ralpha, ralpha+1);
         if (v <= ralpha)
             return v;
         Value v = qsearch<NonPV, false>(pos, ss, ralpha, ralpha+1);
         if (v <= ralpha)
             return v;