Synchronize pruning rules in search and sp_search

Regression test passed:

Mod - Orig: 365 - 351

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

diff --git a/src/search.cpp b/src/search.cpp
index c1f90e119a24d82379eac5521bb950ca2732f4de..0fe242dd120f9afe15a827c1d8a0b0805640d1e7 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1814,6 +1814,7 @@ namespace {
     bool useFutilityPruning =     sp->depth < SelectiveDepth
                               && !isCheck;
 
     bool useFutilityPruning =     sp->depth < SelectiveDepth
                               && !isCheck;
 

+    const int FutilityMoveCountMargin = 3 + (1 << (3 * int(sp->depth) / 8));

     const int FutilityValueMargin = 112 * bitScanReverse32(int(sp->depth) * int(sp->depth) / 2);
 
     while (    sp->bestValue < sp->beta
     const int FutilityValueMargin = 112 * bitScanReverse32(int(sp->depth) * int(sp->depth) / 2);
 
     while (    sp->bestValue < sp->beta


@@ -1842,31 +1843,30 @@ namespace {
           && !captureOrPromotion)
       {
           // Move count based pruning
           && !captureOrPromotion)
       {
           // Move count based pruning

-          if (   moveCount >= 2 + int(sp->depth)
+          if (   moveCount >= FutilityMoveCountMargin

               && ok_to_prune(pos, move, ss[sp->ply].threatMove)
               && sp->bestValue > value_mated_in(PLY_MAX))
               continue;
 
           // Value based pruning
               && ok_to_prune(pos, move, ss[sp->ply].threatMove)
               && sp->bestValue > value_mated_in(PLY_MAX))
               continue;
 
           // Value based pruning

-          if (sp->approximateEval < sp->beta)
+          if (sp->futilityValue == VALUE_NONE)

           {
           {

-              if (sp->futilityValue == VALUE_NONE)
-              {
-                  EvalInfo ei;
-                  sp->futilityValue = evaluate(pos, ei, threadID) + FutilityValueMargin;
-              }
+              EvalInfo ei;
+              sp->futilityValue = evaluate(pos, ei, threadID) + FutilityValueMargin;
+          }

 
 

-              if (sp->futilityValue < sp->beta)
+          Value futilityValueScaled = sp->futilityValue - moveCount * IncrementalFutilityMargin;
+
+          if (futilityValueScaled < sp->beta)
+          {
+              if (futilityValueScaled > sp->bestValue) // Less then 1% of cases

               {
               {

-                  if (sp->futilityValue > sp->bestValue) // Less then 1% of cases
-                  {
-                      lock_grab(&(sp->lock));
-                      if (sp->futilityValue > sp->bestValue)
-                          sp->bestValue = sp->futilityValue;
-                      lock_release(&(sp->lock));
-                  }
-                  continue;
+                  lock_grab(&(sp->lock));
+                  if (futilityValueScaled > sp->bestValue)
+                      sp->bestValue = futilityValueScaled;
+                  lock_release(&(sp->lock));

               }
               }

+              continue;

           }
       }
 
           }
       }