Remove temporary shelter array

Remove temporary array of shelters and avoid iterating over it each time to find
if the shelter values after castling are better than the current value.
Work done on top of https://github.com/official-stockfish/Stockfish/pull/2277

Speed benchmark did not measure any difference.

No functional change

diff --git a/src/pawns.cpp b/src/pawns.cpp
index 8022ae51c20d811adac0d0cb22d8208af8515e1b..bc1cf38af9c2706f54b793967866f632aa5c65c0 100644 (file)
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -231,21 +231,17 @@ Score Entry::do_king_safety(const Position& pos) {
   Square ksq = pos.square<KING>(Us);
   kingSquares[Us] = ksq;
   castlingRights[Us] = pos.castling_rights(Us);
   Square ksq = pos.square<KING>(Us);
   kingSquares[Us] = ksq;
   castlingRights[Us] = pos.castling_rights(Us);

+  auto compare = [](Score a, Score b) { return mg_value(a) <= mg_value(b); };

 
 

-  Score shelters[3] = { evaluate_shelter<Us>(pos, ksq),
-                        make_score(-VALUE_INFINITE, 0),
-                        make_score(-VALUE_INFINITE, 0) };
+  Score shelter = evaluate_shelter<Us>(pos, ksq);

 
   // If we can castle use the bonus after castling if it is bigger
 
   // If we can castle use the bonus after castling if it is bigger

+

   if (pos.can_castle(Us & KING_SIDE))
   if (pos.can_castle(Us & KING_SIDE))

-      shelters[1] = evaluate_shelter<Us>(pos, relative_square(Us, SQ_G1));
+      shelter = std::max(shelter, evaluate_shelter<Us>(pos, relative_square(Us, SQ_G1)), compare);

 
   if (pos.can_castle(Us & QUEEN_SIDE))
 
   if (pos.can_castle(Us & QUEEN_SIDE))

-      shelters[2] = evaluate_shelter<Us>(pos, relative_square(Us, SQ_C1));
-
-  for (int i : {1, 2})
-     if (mg_value(shelters[i]) > mg_value(shelters[0]))
-         shelters[0] = shelters[i];
+      shelter = std::max(shelter, evaluate_shelter<Us>(pos, relative_square(Us, SQ_C1)), compare);

 
   // In endgame we like to bring our king near our closest pawn
   Bitboard pawns = pos.pieces(Us, PAWN);
 
   // In endgame we like to bring our king near our closest pawn
   Bitboard pawns = pos.pieces(Us, PAWN);


@@ -256,7 +252,7 @@ Score Entry::do_king_safety(const Position& pos) {
   else while (pawns)
       minPawnDist = std::min(minPawnDist, distance(ksq, pop_lsb(&pawns)));
 
   else while (pawns)
       minPawnDist = std::min(minPawnDist, distance(ksq, pop_lsb(&pawns)));
 

-  return shelters[0] - make_score(0, 16 * minPawnDist);
+  return shelter - make_score(0, 16 * minPawnDist);

 }
 
 // Explicit template instantiation
 }
 
 // Explicit template instantiation