From: mstembera <MissingEmail@email>
Date: Sat, 24 Aug 2019 22:04:41 +0000 (-0700)
Subject: Remove temporary shelter array
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=5d1568632ca42b400dff73f5e74ae613e73ed889

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 8022ae51..bc1cf38a 100644
--- 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);
+  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 (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))
-      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);
@@ -256,7 +252,7 @@ Score Entry::do_king_safety(const Position& pos) {
   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