Retire candidate passed pawns

Before this commit, some pawns were considered "candidate" passed pawns and given half bonus. After this commit, all of these pawns are scored as passed pawns, and they do not receive less bonus.

STC:
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 21806 W: 4320 L: 4158 D: 13328
Ptnml(0-2): 367, 2526, 5001, 2596, 413
https://tests.stockfishchess.org/tests/view/5e86b4724411759d9d098639

LTC:
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 12590 W: 1734 L: 1617 D: 9239
Ptnml(0-2): 96, 1187, 3645, 1238, 129
https://tests.stockfishchess.org/tests/view/5e86d2874411759d9d098640

This PR and commit are dedicated to our colleague Stefan Geschwentner (@locutus2), one of the most respected and accomplished members of the Stockfish developer community. Stockfish is a volunteer project and has always thrived because of Stefan's talent, insight, generosity, and dedication. Welcome back, Stefan!

closes https://github.com/official-stockfish/Stockfish/pull/2613

Bench: 4831963

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 57491f343f9a6ee8fb5133aaba96beba4279d643..f4a5d4867b084ceb22d13194659cf3e25600eb03 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -638,11 +638,6 @@ namespace {
             }
         } // r > RANK_3
 
             }
         } // r > RANK_3
 

-        // Scale down bonus for candidate passers which need more than one
-        // pawn push to become passed.
-        if (!pos.pawn_passed(Us, s + Up))
-            bonus = bonus / 2;
-

         score += bonus - PassedFile * edge_distance(file_of(s));
     }
 
         score += bonus - PassedFile * edge_distance(file_of(s));
     }