Do move-count pruning in probcut

STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 4928 W: 1163 L: 1007 D: 2758

LTC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 20368 W: 3441 L: 3238 D: 13689
http://tests.stockfishchess.org/tests/view/5a98bea40ebc590297cc8e5d

Bench: 6361568

diff --git a/src/search.cpp b/src/search.cpp
index f6cf8de887cc655512884249d70301196b0e5a70..8a50c3b1e48916505da0bef2fd9750472d7cf6cd 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -757,10 +757,13 @@ namespace {
 
         Value rbeta = std::min(beta + 200, VALUE_INFINITE);
         MovePicker mp(pos, ttMove, rbeta - ss->staticEval, &thisThread->captureHistory);
 
         Value rbeta = std::min(beta + 200, VALUE_INFINITE);
         MovePicker mp(pos, ttMove, rbeta - ss->staticEval, &thisThread->captureHistory);

-
-        while ((move = mp.next_move()) != MOVE_NONE)
+        int probCutCount = 0;
+        while (  (move = mp.next_move()) != MOVE_NONE
+               && probCutCount < depth / ONE_PLY - 3)

             if (pos.legal(move))
             {
             if (pos.legal(move))
             {

+                probCutCount++;
+

                 ss->currentMove = move;
                 ss->contHistory = thisThread->contHistory[pos.moved_piece(move)][to_sq(move)].get();
 
                 ss->currentMove = move;
                 ss->contHistory = thisThread->contHistory[pos.moved_piece(move)][to_sq(move)].get();