Use less reduction for escaping moves

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 0f524093c2d399c40ae08c25889f19aabf49b302..4b6b497a5b49b504031519b5fcb8137d6a76d1b9 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -789,7 +789,7 @@ namespace {
         &&  depth < 8
         &&  eval - futility_margin(depth, improving) - (ss-1)->statScore / 303 >= beta
         &&  eval >= beta
-        &&  eval < 28031) // larger than VALUE_KNOWN_WIN, but smaller than TB wins.
+        &&  eval < 28031) // larger than VALUE_KNOWN_WIN, but smaller than TB wins
         return eval;
 
     // Step 9. Null move search with verification search (~22 Elo)
@@ -1163,7 +1163,12 @@ moves_loop: // When in check, search starts here
           if (singularQuietLMR)
               r--;
 
-          // Increase reduction if next ply has a lot of fail high else reset count to 0
+          // Dicrease reduction if we move a threatened piece (~1 Elo)
+          if (   depth > 9
+              && (mp.threatenedPieces & from_sq(move)))
+              r--;
+
+          // Increase reduction if next ply has a lot of fail high
           if ((ss+1)->cutoffCnt > 3 && !PvNode)
               r++;
 
@@ -1860,12 +1865,9 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) {
           ss << (v >= beta ? " lowerbound" : v <= alpha ? " upperbound" : "");
 
       ss << " nodes "    << nodesSearched
-         << " nps "      << nodesSearched * 1000 / elapsed;
-
-      if (elapsed > 1000) // Earlier makes little sense
-          ss << " hashfull " << TT.hashfull();
-
-      ss << " tbhits "   << tbHits
+         << " nps "      << nodesSearched * 1000 / elapsed
+         << " hashfull " << TT.hashfull()
+         << " tbhits "   << tbHits
          << " time "     << elapsed
          << " pv";