Enable LMR for dangerous moves

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 9ae28d3c55870b554a5681782442dbbc3569b3c3..c85cdb5d689fcc1ee47f336812a1d9d310595ec0 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -84,7 +84,7 @@ namespace {
 
   size_t PVSize, PVIdx;
   TimeManager TimeMgr;
-  int BestMoveChanges;
+  float BestMoveChanges;
   Value DrawValue[COLOR_NB];
   HistoryStats History;
   GainsStats Gains;
@@ -304,13 +304,14 @@ namespace {
   void id_loop(Position& pos) {
 
     Stack stack[MAX_PLY_PLUS_6], *ss = stack+2; // To allow referencing (ss-2)
-    int depth, prevBestMoveChanges;
+    int depth;
     Value bestValue, alpha, beta, delta;
 
     std::memset(ss-2, 0, 5 * sizeof(Stack));
     (ss-1)->currentMove = MOVE_NULL; // Hack to skip update gains
 
-    depth = BestMoveChanges = 0;
+    depth = 0;
+    BestMoveChanges = 0;
     bestValue = delta = alpha = -VALUE_INFINITE;
     beta = VALUE_INFINITE;
 
@@ -332,14 +333,14 @@ namespace {
     // Iterative deepening loop until requested to stop or target depth reached
     while (++depth <= MAX_PLY && !Signals.stop && (!Limits.depth || depth <= Limits.depth))
     {
+        // Age out PV variability metric
+        BestMoveChanges *= 0.8;
+
         // Save last iteration's scores before first PV line is searched and all
         // the move scores but the (new) PV are set to -VALUE_INFINITE.
         for (size_t i = 0; i < RootMoves.size(); i++)
             RootMoves[i].prevScore = RootMoves[i].score;
 
-        prevBestMoveChanges = BestMoveChanges; // Only sensible when PVSize == 1
-        BestMoveChanges = 0;
-
         // MultiPV loop. We perform a full root search for each PV line
         for (PVIdx = 0; PVIdx < PVSize; PVIdx++)
         {
@@ -437,7 +438,7 @@ namespace {
 
             // Take in account some extra time if the best move has changed
             if (depth > 4 && depth < 50 &&  PVSize == 1)
-                TimeMgr.pv_instability(BestMoveChanges, prevBestMoveChanges);
+                TimeMgr.pv_instability(BestMoveChanges);
 
             // Stop search if most of available time is already consumed. We
             // probably don't have enough time to search the first move at the
@@ -940,7 +941,6 @@ moves_loop: // When in check and at SpNode search starts from here
       if (    depth > 3 * ONE_PLY
           && !pvMove
           && !captureOrPromotion
-          && !dangerous
           &&  move != ttMove
           &&  move != ss->killers[0]
           &&  move != ss->killers[1])
@@ -1230,6 +1230,7 @@ moves_loop: // When in check and at SpNode search starts from here
           && !givesCheck
           &&  move != ttMove
           &&  type_of(move) != PROMOTION
+          &&  futilityBase > -VALUE_KNOWN_WIN
           && !pos.is_passed_pawn_push(move))
       {
           futilityValue =  futilityBase