Less NMP if the position was previously in PV.

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 6146bdf6b5ae9ac24f48cb2e3e3ca831bf8f7618..044187e5d90106cdd452fdbfcaebeb9d0b05c15a 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -393,6 +393,8 @@ void Thread::search() {
   contempt = (us == WHITE ?  make_score(ct, ct / 2)
                           : -make_score(ct, ct / 2));
 
+  int searchAgainCounter = 0;
+
   // Iterative deepening loop until requested to stop or the target depth is reached
   while (   ++rootDepth < MAX_PLY
          && !Threads.stop
@@ -410,6 +412,9 @@ void Thread::search() {
       size_t pvFirst = 0;
       pvLast = 0;
 
+      if (!Threads.increaseDepth)
+         searchAgainCounter++;
+
       // MultiPV loop. We perform a full root search for each PV line
       for (pvIdx = 0; pvIdx < multiPV && !Threads.stop; ++pvIdx)
       {
@@ -445,7 +450,7 @@ void Thread::search() {
           int failedHighCnt = 0;
           while (true)
           {
-              Depth adjustedDepth = std::max(1, rootDepth - failedHighCnt);
+              Depth adjustedDepth = std::max(1, rootDepth - failedHighCnt - searchAgainCounter);
               bestValue = ::search<PV>(rootPos, ss, alpha, beta, adjustedDepth, false);
 
               // Bring the best move to the front. It is critical that sorting
@@ -558,6 +563,12 @@ void Thread::search() {
               else
                   Threads.stop = true;
           }
+          else if (   Threads.increaseDepth
+                   && !mainThread->ponder
+                   && Time.elapsed() > Time.optimum() * fallingEval * reduction * bestMoveInstability * 0.6)
+                   Threads.increaseDepth = false;
+          else
+                   Threads.increaseDepth = true;
       }
 
       mainThread->iterValue[iterIdx] = bestValue;
@@ -814,8 +825,8 @@ namespace {
         &&  eval <= alpha - RazorMargin)
         return qsearch<NT>(pos, ss, alpha, beta);
 
-    improving =  (ss-2)->staticEval == VALUE_NONE ? (ss->staticEval >= (ss-4)->staticEval
-              || (ss-4)->staticEval == VALUE_NONE) : ss->staticEval >= (ss-2)->staticEval;
+    improving =  (ss-2)->staticEval == VALUE_NONE ? (ss->staticEval > (ss-4)->staticEval
+              || (ss-4)->staticEval == VALUE_NONE) : ss->staticEval > (ss-2)->staticEval;
 
     // Step 8. Futility pruning: child node (~50 Elo)
     if (   !PvNode
@@ -830,7 +841,7 @@ namespace {
         && (ss-1)->statScore < 23397
         &&  eval >= beta
         &&  eval >= ss->staticEval
-        &&  ss->staticEval >= beta - 32 * depth + 292 - improving * 30
+        &&  ss->staticEval >= beta - 32 * depth - 30 * improving + 120 * ttPv + 292
         && !excludedMove
         &&  pos.non_pawn_material(us)
         && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
@@ -1005,11 +1016,11 @@ moves_loop: // When in check, search starts from here
               // Futility pruning: parent node (~5 Elo)
               if (   lmrDepth < 6
                   && !inCheck
-                  && ss->staticEval + 255 + 182 * lmrDepth <= alpha
+                  && ss->staticEval + 235 + 172 * lmrDepth <= alpha
                   &&  thisThread->mainHistory[us][from_to(move)]
                     + (*contHist[0])[movedPiece][to_sq(move)]
                     + (*contHist[1])[movedPiece][to_sq(move)]
-                    + (*contHist[3])[movedPiece][to_sq(move)] < 30000)
+                    + (*contHist[3])[movedPiece][to_sq(move)] < 25000)
                   continue;
 
               // Prune moves with negative SEE (~20 Elo)
@@ -1017,7 +1028,11 @@ moves_loop: // When in check, search starts from here
                   continue;
           }
           else if (!pos.see_ge(move, Value(-194) * depth)) // (~25 Elo)
-                  continue;
+          {
+              if (captureOrPromotion && captureCount < 32)
+                  capturesSearched[captureCount++] = move;
+              continue;
+          }
       }
 
       // Step 14. Extensions (~75 Elo)
@@ -1104,7 +1119,7 @@ moves_loop: // When in check, search starts from here
       // Step 16. Reduced depth search (LMR, ~200 Elo). If the move fails high it will be
       // re-searched at full depth.
       if (    depth >= 3
-          &&  moveCount > 1 + 2 * rootNode
+          &&  moveCount > 1 + rootNode + (rootNode && bestValue < alpha)
           && (!rootNode || thisThread->best_move_count(move) == 0)
           && (  !captureOrPromotion
               || moveCountPruning
@@ -1149,7 +1164,7 @@ moves_loop: // When in check, search starts from here
               // hence break make_move(). (~2 Elo)
               else if (    type_of(move) == NORMAL
                        && !pos.see_ge(reverse_move(move)))
-                  r -= 2;
+                  r -= 2 + ttPv;
 
               ss->statScore =  thisThread->mainHistory[us][from_to(move)]
                              + (*contHist[0])[movedPiece][to_sq(move)]
@@ -1175,6 +1190,10 @@ moves_loop: // When in check, search starts from here
               r -= ss->statScore / 16384;
           }
 
+          // Increase reduction for captures/promotions if late move and at low depth
+          else if (depth < 8 && moveCount > 2)
+              r++;
+
           Depth d = clamp(newDepth - r, 1, newDepth);
 
           value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);