From: Joona Kiiski <joona.kiiski@gmail.com>
Date: Sun, 21 Apr 2013 13:53:27 +0000 (+0100)
Subject: More aggressive post-futility pruning
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=8df17204f4469977604695e4ae5d63ae47a575ff

More aggressive post-futility pruning
---

diff --git a/src/search.cpp b/src/search.cpp
index 1fe895d3..80ac9b20 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -643,10 +643,10 @@ namespace {
         && !ss->skipNullMove
         &&  depth < 4 * ONE_PLY
         && !inCheck
-        &&  eval - FutilityMargins[depth][0] >= beta
+        &&  eval - FutilityMargins[depth][(ss-1)->futMc] >= beta
         &&  abs(beta) < VALUE_MATE_IN_MAX_PLY
         &&  pos.non_pawn_material(pos.side_to_move()))
-        return eval - FutilityMargins[depth][0];
+        return eval - FutilityMargins[depth][(ss-1)->futMc];
 
     // Step 8. Null move search with verification search (is omitted in PV nodes)
     if (   !PvNode
@@ -852,6 +852,8 @@ split_point_start: // At split points actual search starts from here
       // Update current move (this must be done after singular extension search)
       newDepth = depth - ONE_PLY + ext;
 
+      ss->futMc = 0;
+
       // Step 13. Futility pruning (is omitted in PV nodes)
       if (   !PvNode
           && !captureOrPromotion
@@ -874,6 +876,8 @@ split_point_start: // At split points actual search starts from here
           // Value based pruning
           // We illogically ignore reduction condition depth >= 3*ONE_PLY for predicted depth,
           // but fixing this made program slightly weaker.
+          ss->futMc = moveCount;
+
           Depth predictedDepth = newDepth - reduction<PvNode>(depth, moveCount);
           futilityValue =  ss->staticEval + ss->evalMargin + futility_margin(predictedDepth, moveCount)
                          + Gain[pos.piece_moved(move)][to_sq(move)];
diff --git a/src/search.h b/src/search.h
index bd210237..2300c762 100644
--- a/src/search.h
+++ b/src/search.h
@@ -47,6 +47,7 @@ struct Stack {
   Value staticEval;
   Value evalMargin;
   int skipNullMove;
+  int futMc;
 };