Evaluate mobility of pinned pieces exactly

ceebo · mcostalba · commit 091aff044516 · 2013-11-10T11:52:38.000+01:00
Previously some squares could be "incorrectly" awarded
to a pinned piece.

e.g. in 3k4/1q6/3b4/3Q4/8/5K2/B7/8 b - - 0 1 the black
bishop get 4 squares too many and the white queen gets 6.

Passed both short TC.
LLR: 2.97 (-2.94,2.94) [-1.50,4.50]
Total: 4871 W: 934 L: 817 D: 3120

And long TC:
LLR: 2.96 (-2.94,2.94) [0.00,6.00]
Total: 38968 W: 6113 L: 5837 D: 27018

bench: 9282549
diff --git a/src/bitboard.cpp b/src/bitboard.cpp
@@ -45,6 +45,7 @@ Bitboard AdjacentFilesBB[FILE_NB];
 Bitboard InFrontBB[COLOR_NB][RANK_NB];
 Bitboard StepAttacksBB[PIECE_NB][SQUARE_NB];
 Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
+Bitboard LineBB[SQUARE_NB][SQUARE_NB];
 Bitboard DistanceRingsBB[SQUARE_NB][8];
 Bitboard ForwardBB[COLOR_NB][SQUARE_NB];
 Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB];
@@ -225,6 +226,9 @@ void Bitboards::init() {
 
               for (Square s = s1 + delta; s != s2; s += delta)
                   BetweenBB[s1][s2] |= s;
+
+              PieceType pc = (PseudoAttacks[BISHOP][s1] & s2) ? BISHOP : ROOK;
+              LineBB[s1][s2] = (PseudoAttacks[pc][s1] & PseudoAttacks[pc][s2]) | s1 | s2;
           }
 }
 
diff --git a/src/bitboard.h b/src/bitboard.h
@@ -74,6 +74,7 @@ extern Bitboard AdjacentFilesBB[FILE_NB];
 extern Bitboard InFrontBB[COLOR_NB][RANK_NB];
 extern Bitboard StepAttacksBB[PIECE_NB][SQUARE_NB];
 extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
+extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
 extern Bitboard DistanceRingsBB[SQUARE_NB][8];
 extern Bitboard ForwardBB[COLOR_NB][SQUARE_NB];
 extern Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB];
diff --git a/src/evaluate.cpp b/src/evaluate.cpp
@@ -492,7 +492,7 @@ Value do_evaluate(const Position& pos) {
                             : pos.attacks_from<Piece>(s);
 
         if (ei.pinnedPieces[Us] & s)
-            b &= PseudoAttacks[QUEEN][pos.king_square(Us)];
+            b &= LineBB[pos.king_square(Us)][s];
 
         ei.attackedBy[Us][Piece] |= b;
 
