Use past SE information also for success cases

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 4424fe2f32d47b61aa1c82524b537f47d7d44ebc..58feb77d7038fc49dcb24821dbf9b762fa84925c 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -251,8 +251,8 @@ namespace {
   int MultiPV;
 
   // Time managment variables
-  int SearchStartTime, MaxNodes, MaxDepth, MaxSearchTime;
-  int AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime;
+  int SearchStartTime, MaxNodes, MaxDepth, OptimumSearchTime;
+  int MaximumSearchTime, ExtraSearchTime, ExactMaxTime;
   bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit;
   bool FirstRootMove, AbortSearch, Quit, AspirationFailLow;
 
@@ -401,7 +401,7 @@ bool think(const Position& pos, bool infinite, bool ponder, int time[], int incr
 
   // Initialize global search variables
   StopOnPonderhit = AbortSearch = Quit = AspirationFailLow = false;
-  MaxSearchTime = AbsoluteMaxSearchTime = ExtraSearchTime = 0;
+  OptimumSearchTime = MaximumSearchTime = ExtraSearchTime = 0;
   NodesSincePoll = 0;
   TM.resetNodeCounters();
   SearchStartTime = get_system_time();
@@ -475,12 +475,12 @@ bool think(const Position& pos, bool infinite, bool ponder, int time[], int incr
   if (UseTimeManagement)
   {
       get_search_times(myTime, myIncrement, movesToGo, pos.startpos_ply_counter(),
-                       &MaxSearchTime, &AbsoluteMaxSearchTime);
+                       &OptimumSearchTime, &MaximumSearchTime);
 
       if (get_option_value_bool("Ponder"))
       {
-          MaxSearchTime += MaxSearchTime / 4;
-          MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime);
+          OptimumSearchTime += OptimumSearchTime / 4;
+          OptimumSearchTime = Min(OptimumSearchTime, MaximumSearchTime);
       }
   }
 
@@ -626,20 +626,20 @@ namespace {
             if (   Iteration >= 8
                 && EasyMove == pv[0]
                 && (  (   rml.get_move_cumulative_nodes(0) > (nodes * 85) / 100
-                       && current_search_time() > MaxSearchTime / 16)
+                       && current_search_time() > OptimumSearchTime / 16)
                     ||(   rml.get_move_cumulative_nodes(0) > (nodes * 98) / 100
-                       && current_search_time() > MaxSearchTime / 32)))
+                       && current_search_time() > OptimumSearchTime / 32)))
                 stopSearch = true;
 
             // Add some extra time if the best move has changed during the last two iterations
             if (Iteration > 5 && Iteration <= 50)
-                ExtraSearchTime = BestMoveChangesByIteration[Iteration]   * (MaxSearchTime / 2)
-                                + BestMoveChangesByIteration[Iteration-1] * (MaxSearchTime / 3);
+                ExtraSearchTime = BestMoveChangesByIteration[Iteration]   * (OptimumSearchTime / 2)
+                                + BestMoveChangesByIteration[Iteration-1] * (OptimumSearchTime / 3);
 
             // Stop search if most of MaxSearchTime is consumed at the end of the
             // iteration. We probably don't have enough time to search the first
             // move at the next iteration anyway.
-            if (current_search_time() > ((MaxSearchTime + ExtraSearchTime) * 80) / 128)
+            if (current_search_time() > ((OptimumSearchTime + ExtraSearchTime) * 80) / 128)
                 stopSearch = true;
 
             if (stopSearch)
@@ -979,7 +979,7 @@ namespace {
     Move movesSearched[256];
     EvalInfo ei;
     StateInfo st;
-    const TTEntry* tte;
+    const TTEntry *tte, *ttx;
     Key posKey;
     Move ttMove, move, excludedMove, threatMove;
     Depth ext, newDepth;
@@ -1190,17 +1190,6 @@ namespace {
                            && is_lower_bound(tte->type())
                            && tte->depth() >= depth - 3 * OnePly;
 
-    // Avoid to do an expensive singular extension search on nodes where
-    // such search had already failed in the past.
-    if (  !PvNode
-        && singularExtensionNode
-        && depth < SingularExtensionDepth[PvNode] + 5 * OnePly)
-    {
-        TTEntry* ttx = TT.retrieve(pos.get_exclusion_key());
-        if (ttx && is_lower_bound(ttx->type()))
-            singularExtensionNode = false;
-    }
-
     // Step 10. Loop through moves
     // Loop through all legal moves until no moves remain or a beta cutoff occurs
     while (   bestValue < beta
@@ -1226,9 +1215,22 @@ namespace {
           && move == tte->move()
           && ext < OnePly)
       {
+          // Avoid to do an expensive singular extension search on nodes where
+          // such search have already been done in the past, so assume the last
+          // singular extension search result is still valid.
+          if (  !PvNode
+              && depth < SingularExtensionDepth[PvNode] + 5 * OnePly
+              && ((ttx = TT.retrieve(pos.get_exclusion_key())) != NULL))
+          {
+              if (is_upper_bound(ttx->type()))
+                  ext = OnePly;
+
+              singularExtensionNode = false;
+          }
+
           Value ttValue = value_from_tt(tte->value(), ply);
 
-          if (abs(ttValue) < VALUE_KNOWN_WIN)
+          if (singularExtensionNode && abs(ttValue) < VALUE_KNOWN_WIN)
           {
               Value b = ttValue - SingularExtensionMargin;
               ss->excludedMove = move;
@@ -2142,9 +2144,9 @@ namespace {
 
     bool stillAtFirstMove =    FirstRootMove
                            && !AspirationFailLow
-                           &&  t > MaxSearchTime + ExtraSearchTime;
+                           &&  t > OptimumSearchTime + ExtraSearchTime;
 
-    bool noMoreTime =   t > AbsoluteMaxSearchTime
+    bool noMoreTime =   t > MaximumSearchTime
                      || stillAtFirstMove;
 
     if (   (Iteration >= 3 && UseTimeManagement && noMoreTime)
@@ -2165,9 +2167,9 @@ namespace {
 
     bool stillAtFirstMove =    FirstRootMove
                            && !AspirationFailLow
-                           &&  t > MaxSearchTime + ExtraSearchTime;
+                           &&  t > OptimumSearchTime + ExtraSearchTime;
 
-    bool noMoreTime =   t > AbsoluteMaxSearchTime
+    bool noMoreTime =   t > MaximumSearchTime
                      || stillAtFirstMove;
 
     if (Iteration >= 3 && UseTimeManagement && (noMoreTime || StopOnPonderhit))