Remove noLMRExtension flag

snicolet · snicolet · commit 8a74c0892869 · 2021-10-17T17:54:39.000+02:00
This simplification patch removes the noLMRExtension flag. It was introduced in June (see following link for that commit), but does not seem to be necessary anymore. Link: e1f181e STC: LLR: 2.94 (-2.94,2.94) <-2.50,0.50> Total: 21200 W: 5369 L: 5228 D: 10603 Ptnml(0-2): 67, 2355, 5616, 2494, 68 https://tests.stockfishchess.org/tests/view/616c03d299b580bf37797dcb LTC: LLR: 2.94 (-2.94,2.94) <-2.50,0.50> Total: 37536 W: 9387 L: 9278 D: 18871 Ptnml(0-2): 23, 3988, 10643, 4085, 29 https://tests.stockfishchess.org/tests/view/616c10f499b580bf37797ddd closes #3743 Bench: 4792969
diff --git a/src/search.cpp b/src/search.cpp
@@ -588,7 +588,7 @@ namespace {
     Value bestValue, value, ttValue, eval, maxValue, probCutBeta;
     bool givesCheck, improving, didLMR, priorCapture;
     bool captureOrPromotion, doFullDepthSearch, moveCountPruning,
-         ttCapture, singularQuietLMR, noLMRExtension;
+         ttCapture, singularQuietLMR;
     Piece movedPiece;
     int moveCount, captureCount, quietCount, bestMoveCount, improvement;
 
@@ -984,7 +984,7 @@ namespace {
                                       ss->ply);
 
     value = bestValue;
-    singularQuietLMR = moveCountPruning = noLMRExtension = false;
+    singularQuietLMR = moveCountPruning = false;
 
     // Indicate PvNodes that will probably fail low if the node was searched
     // at a depth equal or greater than the current depth, and the result of this search was a fail low.
@@ -1108,10 +1108,7 @@ namespace {
               if (   !PvNode
                   && value < singularBeta - 75
                   && ss->doubleExtensions <= 6)
-              {
                   extension = 2;
-                  noLMRExtension = true;
-              }
           }
 
           // Multi-cut pruning
@@ -1221,7 +1218,6 @@ namespace {
           // are really negative and movecount is low, we allow this move to be searched
           // deeper than the first move (this may lead to hidden double extensions).
           int deeper =   r >= -1                   ? 0
-                       : noLMRExtension            ? 0
                        : moveCount <= 3 && r <= -3 ? 2
                        : moveCount <= 5            ? 1
                        : PvNode && depth > 6       ? 1
