Use (strict) greater-than-operator for 'improving'

pb00068 · snicolet · commit f63d112c710f · 2020-01-23T18:43:47.000+01:00
Currently on a normal bench run in ~0,7% of cases 'improving' is set to true although the static eval isn't improving at all, just keeping equal. It looks like the strict gt-operator is more appropriate here, since it returns to 'improving' its literal meaning without sideffects. STC {-1.00,3.00} failed yellow: https://tests.stockfishchess.org/tests/view/5e1ec38c8fd5f550e4ae1c28 LLR: -2.93 (-2.94,2.94) {-1.00,3.00} Total: 53155 W: 10170 L: 10109 D: 32876 Ptnml(0-2): 863, 6282, 12251, 6283, 892 non-regression LTC passed: https://tests.stockfishchess.org/tests/view/5e1f1c0d8fd5f550e4ae1c41 LLR: 2.98 (-2.94,2.94) {-1.50,0.50} Total: 23961 W: 3114 L: 3018 D: 17829 Ptnml(0-2): 163, 2220, 7114, 2298, 170 CLoses #2496 bench: 4561386
diff --git a/src/search.cpp b/src/search.cpp
@@ -625,7 +625,7 @@ namespace {
     Move ttMove, move, excludedMove, bestMove;
     Depth extension, newDepth;
     Value bestValue, value, ttValue, eval, maxValue;
-    bool ttHit, ttPv, inCheck, givesCheck, improving, didLMR, priorCapture;
+    bool ttHit, ttPv, inCheck, givesCheck, improving , didLMR, priorCapture;
     bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture, singularLMR;
     Piece movedPiece;
     int moveCount, captureCount, quietCount;
@@ -825,8 +825,9 @@ 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;
+    // (~13 Elo)
+    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
