SEE Pruning Tweak (#2183)

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index b31157e4406c3755f6789da25df8fd13c556e215..f26ab959ba27ee829c9c07c9c4069b9b3a0a57ba 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -71,7 +71,7 @@ namespace {
   int Reductions[MAX_MOVES]; // [depth or moveNumber]
 
   Depth reduction(bool i, Depth d, int mn) {
-    int r = Reductions[d / ONE_PLY] * Reductions[mn] / 1024;
+    int r = Reductions[d / ONE_PLY] * Reductions[mn];
     return ((r + 512) / 1024 + (!i && r > 1024)) * ONE_PLY;
   }
 
@@ -149,7 +149,7 @@ namespace {
 void Search::init() {
 
   for (int i = 1; i < MAX_MOVES; ++i)
-     Reductions[i] = int(733.3 * std::log(i));
+     Reductions[i] = int(22.9 * std::log(i));
 }
 
 
@@ -239,19 +239,19 @@ void MainThread::search() {
       for (Thread* th: Threads)
           minScore = std::min(minScore, th->rootMoves[0].score);
 
-      // Vote according to score and depth
+      // Vote according to score and depth, and select the best thread
+      int64_t bestVote = 0;
       for (Thread* th : Threads)
+      {
           votes[th->rootMoves[0].pv[0]] +=
                (th->rootMoves[0].score - minScore + 14) * int(th->completedDepth);
 
-      // Select best thread
-      auto bestVote = votes[this->rootMoves[0].pv[0]];
-      for (Thread* th : Threads)
           if (votes[th->rootMoves[0].pv[0]] > bestVote)
           {
               bestVote = votes[th->rootMoves[0].pv[0]];
               bestThread = th;
           }
+      }
   }
 
   previousScore = bestThread->rootMoves[0].score;
@@ -283,7 +283,7 @@ void Thread::search() {
   Move  pv[MAX_PLY+1];
   Value bestValue, alpha, beta, delta;
   Move  lastBestMove = MOVE_NONE;
-  Depth lastBestMoveDepth = DEPTH_ZERO, rootDepth = DEPTH_ZERO;
+  Depth lastBestMoveDepth = DEPTH_ZERO;
   MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr);
   double timeReduction = 1, totBestMoveChanges = 0;
   Color us = rootPos.side_to_move();
@@ -404,17 +404,14 @@ void Thread::search() {
                   beta = (alpha + beta) / 2;
                   alpha = std::max(bestValue - delta, -VALUE_INFINITE);
 
+                  failedHighCnt = 0;
                   if (mainThread)
-                  {
-                      failedHighCnt = 0;
                       mainThread->stopOnPonderhit = false;
-                  }
               }
               else if (bestValue >= beta)
               {
                   beta = std::min(bestValue + delta, VALUE_INFINITE);
-                  if (mainThread)
-                      ++failedHighCnt;
+                  ++failedHighCnt;
               }
               else
                   break;
@@ -961,7 +958,7 @@ moves_loop: // When in check, search starts from here
 
           if (   !captureOrPromotion
               && !givesCheck
-              && !pos.advanced_pawn_push(move))
+              && (!pos.advanced_pawn_push(move) || pos.non_pawn_material(~us) > BishopValueMg))
           {
               // Move count based pruning (~30 Elo)
               if (moveCountPruning)
@@ -987,7 +984,8 @@ moves_loop: // When in check, search starts from here
               if (!pos.see_ge(move, Value(-29 * lmrDepth * lmrDepth)))
                   continue;
           }
-          else if (!pos.see_ge(move, -PawnValueEg * (depth / ONE_PLY))) // (~20 Elo)
+          else if ((!givesCheck || !(pos.blockers_for_king(~us) & from_sq(move)))
+                  && !pos.see_ge(move, -PawnValueEg * (depth / ONE_PLY))) // (~20 Elo)
                   continue;
       }