From: Reuven Peleg <reuvenpe2005@gmail.com>
Date: Mon, 17 Jun 2013 10:49:11 +0000 (+0300)
Subject: Remove confusing optimization
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=e05c80a08859f6c4f0f599ca0b262ced00ad66fe;hp=7b31e81d77b636a635b327de91414a0585fedb2a

Remove confusing optimization

Here we skip the call to pos.attacks_from<ROOK>(s) in the 98%
of cases, testing the first 2 members first. Unfortunatly
code is a bit triky and not clear. So we give up to the
speed optimization in exchange of more code clarity.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
---

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index a19f346d..ea37bbeb 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -821,8 +821,7 @@ Value do_evaluate(const Position& pos, Value& margin) {
                 // If there is an enemy rook or queen attacking the pawn from behind,
                 // add all X-ray attacks by the rook or queen. Otherwise consider only
                 // the squares in the pawn's path attacked or occupied by the enemy.
-                if (   (forward_bb(Them, s) & pos.pieces(Them, ROOK, QUEEN))
-                    && (forward_bb(Them, s) & pos.pieces(Them, ROOK, QUEEN) & pos.attacks_from<ROOK>(s)))
+                if (forward_bb(Them, s) & pos.pieces(Them, ROOK, QUEEN) & pos.attacks_from<ROOK>(s))
                     unsafeSquares = squaresToQueen;
                 else
                     unsafeSquares = squaresToQueen & (ei.attackedBy[Them][ALL_PIECES] | pos.pieces(Them));