Enable true 3 fold detection in search

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index b43ebd02ab848ae4f2675bd0eaba637b8f9532b8..785cf0efb8ec7ec055f369ec3566c88f9dd87ccf 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -524,7 +524,7 @@ namespace {
     if (!RootNode)
     {
         // Step 2. Check for aborted search and immediate draw
-        if (Signals.stop || pos.is_draw<false>() || ss->ply > MAX_PLY)
+        if (Signals.stop || (PvNode?pos.is_draw<false,false>():pos.is_draw<false,true>()) || ss->ply > MAX_PLY)
             return DrawValue[pos.side_to_move()];
 
         // Step 3. Mate distance pruning. Even if we mate at the next move our score
@@ -958,7 +958,7 @@ split_point_start: // At split points actual search starts from here
       // ran out of time. In this case, the return value of the search cannot
       // be trusted, and we don't update the best move and/or PV.
       if (Signals.stop || thisThread->cutoff_occurred())
-          return bestValue;
+          return value; // To avoid returning VALUE_INFINITE
 
       if (RootNode)
       {
@@ -1103,7 +1103,7 @@ split_point_start: // At split points actual search starts from here
     ss->ply = (ss-1)->ply + 1;
 
     // Check for an instant draw or maximum ply reached
-    if (pos.is_draw<true>() || ss->ply > MAX_PLY)
+    if (pos.is_draw<true,true>() || ss->ply > MAX_PLY)
         return DrawValue[pos.side_to_move()];
 
     // Transposition table lookup. At PV nodes, we don't use the TT for
@@ -1552,7 +1552,7 @@ void RootMove::extract_pv_from_tt(Position& pos) {
          && pos.is_pseudo_legal(m)
          && pos.pl_move_is_legal(m, pos.pinned_pieces())
          && ply < MAX_PLY
-         && (!pos.is_draw<false>() || ply < 2))
+         && (!pos.is_draw<false,true>() || ply < 2))
   {
       pv.push_back(m);
       pos.do_move(m, *st++);