Introduce a function to compute NNUE accumulator

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index eccb97fd12c198cbf5efc1a1d19c2e26e7d91c92..5cb9750c3235a72d6c33fc99943c379c85ac4380 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -730,10 +730,10 @@ namespace {
         goto moves_loop;
     }
     else if (excludedMove) {
-        // excludeMove implies that we had a ttHit on the containing non-excluded search with ss->staticEval filled from TT
-        // However static evals from the TT aren't good enough (-13 elo), presumably due to changing optimism context
-        // Recalculate value with current optimism (without updating thread avgComplexity)
-        ss->staticEval = eval = evaluate(pos, &complexity);
+        // Providing the hint that this node's accumulator will be used often brings significant Elo gain (13 elo)
+        Eval::NNUE::hint_common_parent_position(pos);
+        eval = ss->staticEval;
+        complexity = abs(ss->staticEval - pos.psq_eg_stm());
     }
     else if (ss->ttHit)
     {
@@ -987,6 +987,8 @@ moves_loop: // When in check, search starts here
 
       Value delta = beta - alpha;
 
+      Depth r = reduction(improving, depth, moveCount, delta, thisThread->rootDelta);
+
       // Step 14. Pruning at shallow depth (~120 Elo). Depth conditions are important for mate finding.
       if (  !rootNode
           && pos.non_pawn_material(us)
@@ -996,7 +998,7 @@ moves_loop: // When in check, search starts here
           moveCountPruning = moveCount >= futility_move_count(improving, depth);
 
           // Reduced depth of the next LMR search
-          int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount, delta, thisThread->rootDelta), 0);
+          int lmrDepth = std::max(newDepth - r, 0);
 
           if (   capture
               || givesCheck)
@@ -1133,8 +1135,6 @@ moves_loop: // When in check, search starts here
       // Step 16. Make the move
       pos.do_move(move, st, givesCheck);
 
-      Depth r = reduction(improving, depth, moveCount, delta, thisThread->rootDelta);
-
       // Decrease reduction if position is or has been on the PV
       // and node is not likely to fail low. (~3 Elo)
       if (   ss->ttPv