From: Alain SAVARD <support@multicim.com>
Date: Sat, 7 Oct 2017 20:35:19 +0000 (-0400)
Subject: Simplify bonus for bishop on long diagonal
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=43c186c64503cffe6991c338f1813e36f8f49a29;hp=b36489742b3cfd045c1960fa299199401cd0265d

Simplify bonus for bishop on long diagonal

Removing 2 conditions, and increase the ThreatbyPawn to compensate.

Passed STC
http://tests.stockfishchess.org/tests/view/59dbde900ebc5916ff64be6d
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 14236 W: 2615 L: 2483 D: 9138

Passed LTC
http://tests.stockfishchess.org/tests/view/59dc26470ebc5916ff64be92
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 16552 W: 2136 L: 2010 D: 12406

Bench: 5234652
---

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index f34c01b6..aadde25a 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -31,11 +31,10 @@
 
 namespace {
 
-  const Bitboard LongDiagonals = 0x8142241818244281ULL; // A1..H8 | H1..A8
-  const Bitboard Center        = (FileDBB | FileEBB) & (Rank4BB | Rank5BB);
-  const Bitboard QueenSide     = FileABB | FileBBB | FileCBB | FileDBB;
-  const Bitboard CenterFiles   = FileCBB | FileDBB | FileEBB | FileFBB;
-  const Bitboard KingSide      = FileEBB | FileFBB | FileGBB | FileHBB;
+  const Bitboard Center      = (FileDBB | FileEBB) & (Rank4BB | Rank5BB);
+  const Bitboard QueenSide   = FileABB | FileBBB | FileCBB | FileDBB;
+  const Bitboard CenterFiles = FileCBB | FileDBB | FileEBB | FileFBB;
+  const Bitboard KingSide    = FileEBB | FileFBB | FileGBB | FileHBB;
 
   const Bitboard KingFlank[FILE_NB] = {
     QueenSide, QueenSide, QueenSide, CenterFiles, CenterFiles, KingSide, KingSide, KingSide
@@ -222,7 +221,7 @@ namespace {
   const Score CloseEnemies        = S(  7,  0);
   const Score PawnlessFlank       = S( 20, 80);
   const Score ThreatByHangingPawn = S( 71, 61);
-  const Score ThreatBySafePawn    = S(182,175);
+  const Score ThreatBySafePawn    = S(192,175);
   const Score ThreatByRank        = S( 16,  3);
   const Score Hanging             = S( 48, 27);
   const Score WeakUnopposedPawn   = S(  5, 25);
@@ -354,10 +353,8 @@ namespace {
                 // Penalty for pawns on the same color square as the bishop
                 score -= BishopPawns * pe->pawns_on_same_color_squares(Us, s);
 
-                // Bonus for bishop on a long diagonal without pawns in the center
-                if (    (LongDiagonals & s)
-                    && !(attackedBy[Them][PAWN] & s)
-                    && !(Center & PseudoAttacks[BISHOP][s] & pos.pieces(PAWN)))
+                // Bonus for bishop on a long diagonal which can "see" both center squares
+                if (more_than_one(Center & (attacks_bb<BISHOP>(s, pos.pieces(PAWN)) | s)))
                     score += LongRangedBishop;
             }