Adjust LMR with correction history

bench 1079115
official-stockfish · Dec 18, 2024 · 397b2f3 · 397b2f3
1 parent cf10644
commit 397b2f3
Showing 1 changed file with 24 additions and 19 deletions.
diff --git a/src/search.cpp b/src/search.cpp
@@ -78,25 +78,26 @@ constexpr int futility_move_count(bool improving, Depth depth) {
     return (3 + depth * depth) / (2 - improving);
 }
 
-// Add correctionHistory value to raw staticEval and guarantee evaluation
-// does not hit the tablebase range.
-Value to_corrected_static_eval(Value v, const Worker& w, const Position& pos, Stack* ss) {
+auto correction_value(const Worker& w, const Position& pos, Stack* ss) {
     const Color us    = pos.side_to_move();
     const auto  m     = (ss - 1)->currentMove;
     const auto  pcv   = w.pawnCorrectionHistory[us][pawn_structure_index<Correction>(pos)];
     const auto  macv  = w.majorPieceCorrectionHistory[us][major_piece_index(pos)];
     const auto  micv  = w.minorPieceCorrectionHistory[us][minor_piece_index(pos)];
     const auto  wnpcv = w.nonPawnCorrectionHistory[WHITE][us][non_pawn_index<WHITE>(pos)];
     const auto  bnpcv = w.nonPawnCorrectionHistory[BLACK][us][non_pawn_index<BLACK>(pos)];
-    int         cntcv = 1;
+    const auto  cntcv =
+      m.is_ok() ? (*(ss - 2)->continuationCorrectionHistory)[pos.piece_on(m.to_sq())][m.to_sq()]
+                 : 0;
 
-    if (m.is_ok())
-        cntcv = int((*(ss - 2)->continuationCorrectionHistory)[pos.piece_on(m.to_sq())][m.to_sq()]);
+    return (6384 * pcv + 3583 * macv + 6492 * micv + 6725 * (wnpcv + bnpcv) + 5880 * cntcv);
+}
 
-    const auto cv =
-      (6384 * pcv + 3583 * macv + 6492 * micv + 6725 * (wnpcv + bnpcv) + cntcv * 5880) / 131072;
-    v += cv;
-    return std::clamp(v, VALUE_TB_LOSS_IN_MAX_PLY + 1, VALUE_TB_WIN_IN_MAX_PLY - 1);
+// Add correctionHistory value to raw staticEval and guarantee evaluation
+// does not hit the tablebase range.
+template<typename CorrectionType>
+Value to_corrected_static_eval(Value v, const CorrectionType cv) {
+    return std::clamp(v + cv / 131072, VALUE_TB_LOSS_IN_MAX_PLY + 1, VALUE_TB_WIN_IN_MAX_PLY - 1);
 }
 
 // History and stats update bonus, based on depth
@@ -538,7 +539,7 @@ Value Search::Worker::search(
 
     // Dive into quiescence search when the depth reaches zero
     if (depth <= 0)
-        return qsearch < PvNode ? PV : NonPV > (pos, ss, alpha, beta);
+        return qsearch<PvNode ? PV : NonPV>(pos, ss, alpha, beta);
 
     // Limit the depth if extensions made it too large
     depth = std::min(depth, MAX_PLY - 1);
@@ -713,7 +714,8 @@ Value Search::Worker::search(
     }
 
     // Step 6. Static evaluation of the position
-    Value unadjustedStaticEval = VALUE_NONE;
+    Value      unadjustedStaticEval = VALUE_NONE;
+    const auto correctionValue      = correction_value(*thisThread, pos, ss);
     if (ss->inCheck)
     {
         // Skip early pruning when in check
@@ -738,8 +740,7 @@ Value Search::Worker::search(
         else if (PvNode)
             Eval::NNUE::hint_common_parent_position(pos, networks[numaAccessToken], refreshTable);
 
-        ss->staticEval = eval =
-          to_corrected_static_eval(unadjustedStaticEval, *thisThread, pos, ss);
+        ss->staticEval = eval = to_corrected_static_eval(unadjustedStaticEval, correctionValue);
 
         // ttValue can be used as a better position evaluation (~7 Elo)
         if (is_valid(ttData.value)
@@ -750,8 +751,7 @@ Value Search::Worker::search(
     {
         unadjustedStaticEval =
           evaluate(networks[numaAccessToken], pos, refreshTable, thisThread->optimism[us]);
-        ss->staticEval = eval =
-          to_corrected_static_eval(unadjustedStaticEval, *thisThread, pos, ss);
+        ss->staticEval = eval = to_corrected_static_eval(unadjustedStaticEval, correctionValue);
 
         // Static evaluation is saved as it was before adjustment by correction history
         ttWriter.write(posKey, VALUE_NONE, ss->ttPv, BOUND_NONE, DEPTH_UNSEARCHED, Move::none(),
@@ -1161,6 +1161,10 @@ Value Search::Worker::search(
 
         // These reduction adjustments have no proven non-linear scaling
 
+        r += 330;
+
+        r -= std::min(std::abs(correctionValue) / 32768, 2048);
+
         // Increase reduction for cut nodes (~4 Elo)
         if (cutNode)
             r += 2518 - (ttData.depth >= depth && ss->ttPv) * 991;
@@ -1532,7 +1536,8 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta)
         return ttData.value;
 
     // Step 4. Static evaluation of the position
-    Value unadjustedStaticEval = VALUE_NONE;
+    Value      unadjustedStaticEval = VALUE_NONE;
+    const auto correctionValue      = correction_value(*thisThread, pos, ss);
     if (ss->inCheck)
         bestValue = futilityBase = -VALUE_INFINITE;
     else
@@ -1545,7 +1550,7 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta)
                 unadjustedStaticEval =
                   evaluate(networks[numaAccessToken], pos, refreshTable, thisThread->optimism[us]);
             ss->staticEval = bestValue =
-              to_corrected_static_eval(unadjustedStaticEval, *thisThread, pos, ss);
+              to_corrected_static_eval(unadjustedStaticEval, correctionValue);
 
             // ttValue can be used as a better position evaluation (~13 Elo)
             if (is_valid(ttData.value) && !is_decisive(ttData.value)
@@ -1560,7 +1565,7 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta)
                 ? evaluate(networks[numaAccessToken], pos, refreshTable, thisThread->optimism[us])
                 : -(ss - 1)->staticEval;
             ss->staticEval = bestValue =
-              to_corrected_static_eval(unadjustedStaticEval, *thisThread, pos, ss);
+              to_corrected_static_eval(unadjustedStaticEval, correctionValue);
         }
 
         // Stand pat. Return immediately if static value is at least beta