Remove rank limitation for MinorBehindPawn

This is a functional simplification.  It seems like the rank restriction
for MinorBehindPawn can be removed.

STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 61195 W: 13404 L: 13360 D: 34431
http://tests.stockfishchess.org/tests/view/5b47e6f00ebc5978f4be3fc0

LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 31701 W: 5367 L: 5264 D: 21070
http://tests.stockfishchess.org/tests/view/5b48a2cb0ebc5978f4be4769

Bench: 4938702

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 9d98a63b6cd15afb6badaf708423c9dd5881e471..f4186686b6a2a5d6083050e55fc91e760f7e883b 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -337,9 +337,8 @@ namespace {
             else if (bb &= b & ~pos.pieces(Us))
                 score += Outpost[Pt == BISHOP][bool(attackedBy[Us][PAWN] & bb)];
 
-            // Bonus when behind a pawn
-            if (    relative_rank(Us, s) < RANK_5
-                && (pos.pieces(PAWN) & (s + pawn_push(Us))))
+            // Knight and Bishop bonus for being right behind a pawn
+            if (shift<Down>(pos.pieces(PAWN)) & s)
                 score += MinorBehindPawn;
 
             // Penalty if the piece is far from the king