Decrease reduction for exact PV nodes

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index eb8aea24a13abc521c07016787e9ea30f3660b15..567f87660197e719cf83ab492191bd3d26945b30 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -259,11 +259,6 @@ void MainThread::search() {
       Thread::search(); // Let's start searching!
   }
 
-  // When playing in 'nodes as time' mode, subtract the searched nodes from
-  // the available ones before exiting.
-  if (Limits.npmsec)
-      Time.availableNodes += Limits.inc[us] - Threads.nodes_searched();
-
   // When we reach the maximum depth, we can arrive here without a raise of
   // Threads.stop. However, if we are pondering or in an infinite search,
   // the UCI protocol states that we shouldn't print the best move before the
@@ -283,6 +278,11 @@ void MainThread::search() {
       if (th != this)
           th->wait_for_search_finished();
 
+  // When playing in 'nodes as time' mode, subtract the searched nodes from
+  // the available ones before exiting.
+  if (Limits.npmsec)
+      Time.availableNodes += Limits.inc[us] - Threads.nodes_searched();
+
   // Check if there are threads with a better score than main thread
   Thread* bestThread = this;
   if (   !this->easyMovePlayed
@@ -543,7 +543,7 @@ namespace {
     Depth extension, newDepth;
     Value bestValue, value, ttValue, eval;
     bool ttHit, inCheck, givesCheck, singularExtensionNode, improving;
-    bool captureOrPromotion, doFullDepthSearch, moveCountPruning, skipQuiets, ttCapture;
+    bool captureOrPromotion, doFullDepthSearch, moveCountPruning, skipQuiets, ttCapture, pvExact;
     Piece movedPiece;
     int moveCount, quietCount;
 
@@ -813,6 +813,7 @@ moves_loop: // When in check search starts from here
                            &&  tte->depth() >= depth - 3 * ONE_PLY;
     skipQuiets = false;
     ttCapture = false;
+    pvExact = PvNode && ttHit && tte->bound() == BOUND_EXACT;
 
     // Step 11. Loop through moves
     // Loop through all pseudo-legal moves until no moves remain or a beta cutoff occurs
@@ -957,6 +958,10 @@ moves_loop: // When in check search starts from here
               if ((ss-1)->moveCount > 15)
                   r -= ONE_PLY;
 
+              // Decrease reduction for exact PV nodes
+              if (pvExact)
+                  r -= ONE_PLY;
+
               // Increase reduction if ttMove is a capture
               if (ttCapture)
                   r += ONE_PLY;
@@ -979,10 +984,10 @@ moves_loop: // When in check search starts from here
                              - 4000;
 
               // Decrease/increase reduction by comparing opponent's stat score
-              if (ss->statScore > 0 && (ss-1)->statScore < 0)
+              if (ss->statScore >= 0 && (ss-1)->statScore < 0)
                   r -= ONE_PLY;
 
-              else if (ss->statScore < 0 && (ss-1)->statScore > 0)
+              else if ((ss-1)->statScore >= 0 && ss->statScore < 0)
                   r += ONE_PLY;
 
               // Decrease/increase reduction for moves with a good/bad history