Remove passed_count from almostUnwinnable.

This simplification allows the almostUnwinnable flag to match endgames where the pawns are all on the same flank but are not symmetrical.

STC:
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 23356 W: 4543 L: 4395 D: 14418
Ptnml(0-2): 346, 2651, 5582, 2707, 392
https://tests.stockfishchess.org/tests/view/5e7b8f57e42a5c3b3ca2eb09

LTC:
LLR: 2.96 (-2.94,2.94) {-1.50,0.50}
Total: 31778 W: 4097 L: 4023 D: 23658
Ptnml(0-2): 199, 2853, 9729, 2891, 217
https://tests.stockfishchess.org/tests/view/5e7ba5ade42a5c3b3ca2eb16

closes https://github.com/official-stockfish/Stockfish/pull/2596

Bench 4777139

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index fad2a785acccfb26be33b7c138862f0304fde91d..d51325f0d990c84fc0aa231ec7a495a9902491e3 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -707,8 +707,7 @@ namespace {
     bool pawnsOnBothFlanks =   (pos.pieces(PAWN) & QueenSide)
                             && (pos.pieces(PAWN) & KingSide);
 
     bool pawnsOnBothFlanks =   (pos.pieces(PAWN) & QueenSide)
                             && (pos.pieces(PAWN) & KingSide);
 

-    bool almostUnwinnable =   !pe->passed_count()
-                           &&  outflanking < 0
+    bool almostUnwinnable =   outflanking < 0

                            && !pawnsOnBothFlanks;
 
     bool infiltration = rank_of(pos.square<KING>(WHITE)) > RANK_4
                            && !pawnsOnBothFlanks;
 
     bool infiltration = rank_of(pos.square<KING>(WHITE)) > RANK_4